Saturday, November 11, 2006

E-Governance

E-Governance
PwC e-Governance group has been working with governments (across Central, State and Local level) in India and in the region to design and implement ICT projects. It also assists multi-lateral funding agencies to modernize governments, leverage ICT power by conceptualizing, designing and supporting ICT project implementation that enhance efficiency, effectiveness and transparency in the delivery of public services.

PwC’s strength lies in the understanding of government business and in application of ICTs in bringing about significant reforms in people, process and technology aspects related to government functioning.

If this is your situation:
· You want to design a project/programme that proposes to significantly improve the quality and speed of service delivery
· You want to increase the efficiency of your existing processes by identifying the non value-adds and conducting a Government Process Re-engineering for faster delivery of services.
· You want to design an IT Roadmap for the department/agencies
· You need support to identify the training and infrastructure requirements for employee capacity building.
· You need programme/project management for progress tracking, project appraisal and effective implementation
· You want to change the existing Application and IT environment based on the process changes/changing rules and regulations
· You need support in designing the functional requirements for implementing an e-government application
· You want to design a change management and communication strategy for effective implementation of e-Government Project
· You want to design a change management and communication strategy for effective implementation of e-Government project
· You want to design PPP options for delivering services
· You want to audit IT projects including monitoring of service level agreements, evaluation of application technology
· You want to design a Monitoring and evaluation framework for the department’s IT initiatives
· You want advise on effective backend computerization process of the departments
· You want to design a Sustainable Revenue model for delivering the services to the citizens
· You want to conduct an e-readiness assessment of the departments/agencies
· You want to conduct strategic planning, design balance score card for your agency



How PwC can help you

Whatever is the complexity or urgency of the situation, the e-Governance Practice can provide expert support and solutions. It combines technology, BPR, capacity building and project management skills to help resolve issues, especially when government organizations are facing problems with existing processes or there is capacity shortage to implement a project or when they have the desire to increase efficiency.

Our Services:

Strategic Planning:

To extract benefits from any e-Governance initiative, it is imperative that the initiative is part of a larger strategic plan of the government and forms part of a larger reform agenda. We work with government agencies to develop a clear Vision, well articulated Strategic Priorities & Development Plans (in line with development agenda), robust Performance Management Systems/ Balance Scorecards, Monitoring & Evaluation frameworks, e-Government Strategies/e-governance Readiness Assessments etc.

Government Process Re-engineering (GPR) & ICT Development:

To optimize the benefits of e-Governance initiative, PwC helps clients undertake and implement process improvements/process re-engineering through proven approaches, such as Global Best Practices studies, Performance Improvement studies, Bench-marking studies etc. Its proven methodologies in this area include, Innovation approach, Process Improvement through Benefits Management (PITBM), Integrated Definition (IDeF) for Process Mapping etc., leading to well-defined processes and functional and technical requirements of the ICT Solution.

Project Structuring, including Public Private Partnerships (PPPs):

Translating a well articulated vision of success and sound strategy to a good and bankable project is the essence of project structuring. PwC helps structure projects that clearly define measurable service delivery outcomes, especially through public-private partnership (PPP) mode. The objective of project structuring is to ensure project sustainability from a technical, financial and operational perspective. For example, PwC’s E-Government Partnership Diagnostic Tool helps governments and private sector assess the level of trust in any PPP based ICT project.

Institutional Strengthening & Capacity Building:

Gaps in government department capacity and weak organization structure are some of the major challenges of e-Governance projects in developing countries. PwC helps clients in identifying and addressing these capacity gaps through various options, such as Training Needs Assessment (TNA), Human Resource Development (HRD), Institutional Strengthening, Strategic sourcing and Outsourcing etc.




Programme and Project Management, including Bid Process Management:

Providing hand-holding support during the crucial stage of implementation has been a forte of PwC. As a part of project management, PwC undertakes bid process management, continual monitoring and mid-course correction, issue escalation and resolution during project implementation stage, knowledge management etc. PwC’s proven methodologies, such as Project (Support) Office Methodology, Project & Programme Management (PPM) Methodology, Benefits Realisation Methodology etc., would form part of its solution approach in this area. Effective project/programme management is often what makes well-conceived projects succeed.

Audit of ICT Projects:

PwC undertakes IT project audits in security and control areas surrounding Information Systems, Performance Testing of ICT Solutions, post-implementation review of ICT Solutions etc.

Whatever the complexity or urgency of the situation your organisation faces, the e-Governance practice can provide expert support and solutions. We combine Technology, BPR, Capacity building and Project management skills to Government organizations that are facing issues with existing processes, lack of capacity to implement a project and desire to increase efficiency in delivering services to the citizens.


http://www.pwc.com/extweb/service.nsf/docid/0CBBDEB6EC5024C88525716300387515

Friday, September 29, 2006

Torrents


Torrents
Creating and publishing torrents
To share a file or group of files through BitTorrent, clients first create a “torrent”. This is a small file, which contains metadata about the files to be shared, and about the host computer that coordinates the file distribution. The exact information contained in the torrent file depends on the version of the BitTorrent protocol. However, a torrent file always has the suffix. torrent. Torrent files contain an “announce” section, which specifies the URL of the tracker, and an “info” section, which contains (suggested) names for the files, their lengths, the piece length used, and a SHA-1 hash code for each piece, which clients should use to verify the integrity of the data they receive. Clients who have finished downloading the file may also choose to act as seeders, providing a complete copy of the file. After the torrent file is created, a link to it is placed on a website or elsewhere, and it is registered with a tracker. BitTorrent trackers maintain lists of the clients currently participating in the torrent. The computer with the initial copy of the file is referred to as the initial seeder.

Downloading torrents and sharing files
Using a web browser, users navigate to the site listing the torrent, download it, and open it in a BitTorrent client. After opening the torrent, the BitTorrent client connects to the tracker, which provides it with a list of clients currently downloading the file or files. A group of peers on a BitTorrent or P2P connected with each other to share a particular torrent is generally referred to as a swarm.

Initially, there may be no other peers in the swarm, in which case the client connects directly to the initial seeder and begins to request pieces. The BitTorrent protocol breaks down files into a number of much smaller pieces, typically a quarter of a megabyte (256 kB) in size. Larger file sizes typically have larger pieces. For example, a 4.37-GB file may have a piece size of 4 MB (4096 kB). Pieces are checked as they are received using a hash algorithm to ensure that they are error-free.

As peers enter the swarm, they begin sharing pieces with one another, instead of downloading directly from the seeder. Clients incorporate mechanisms to optimize their download and upload rates, for example using a tit for tat scheme. Peers download pieces in a random order, to increase the opportunity to exchange data, which is only possible if two peers have a different subset of the file.

The effectiveness of the peer-to-peer data exchange depends largely on the policies used by clients to determine whom to send data to. Clients will prefer to send data to peers that send data back to them, which encourages fair sharing, but strict policies often result in suboptimal situations, where newly joined peers are unable to receive any data (because they don't have any pieces yet to share themselves) and two peers with a good connection between them do not exchange data simply because neither of them wants to take the initiative. To counter these effects, the official BitTorrent client uses a mechanism called “optimistic unchoking”, where the client will reserve a portion of its available bandwidth for sending pieces to random peers (not necessarily known-good partners, so called preferred peers), in hopes of discovering even better partners and to ensure newcomers get a chance to join the swarm.

Terminology
Availability
The number of full copies of the file available to the client. Each seed adds 1.0 to this number, as they have one complete copy of the file. A connected peer with a fraction of the file available adds that fraction to the availability, if no other peer has this part of the file. (ie. a peer with 65.3% of the file downloaded increases the availability by 0.653. However, if two peers both have the same portion of the file downloaded - say 50% - and there is only one seeder, the availability is 1.5).

Choked
Describes a peer to whom the client refuses to send file pieces. A client chokes another client in several situations:
· The second client is a seed, in which case it does not want any pieces (ie. it is completely uninterested)
· The client is already uploading at its full capacity (ie. the value for max_uploads has been reached)

Interested
Describes a downloader who wishes to obtain pieces of a file the client has. For example, the uploading client would flag a downloading client as 'interested' if that client did not possess a piece that it did, and wished to obtain it.

Leech
A leech is usually a peer who has a negative effect on the swarm by having a very poor share ratio - in other words, downloading much more than they upload. Most leeches are users on asymmetric internet connections and do not leave their BitTorrent client open to seed the file after their download has completed. However, some leeches intentionally avoid uploading by using modified clients or excessively limiting their upload speed. The term leech, however, can be used simply to describe a peer - or any client that does not have 100% of the data.

Peer
A peer is one instance of a BitTorrent client running on a computer on the Internet to which other clients connect and transfer data. Usually a peer does not have the complete file, but only parts of it. However, in the colloquial definition, "peer" can be used to refer to any participant in the swarm (in this case, it's synonymous with "client").

Scrape
This is when a client sends a request to the tracking server for information about the statistics of the torrent, such as with whom to share the file and how well those other users are sharing.

Seeder
A seeder is a peer that has a complete copy of the torrent and still offers it for upload. The more seeders there are, the better the chances are for completion of the file.

Snubbed
An uploading client is flagged as snubbed if the downloading client has not received any data from it in over 60 seconds.

Superseed
When a file is new, much time can be wasted because the seeding client might send the same file piece to many different peers, while other pieces have not yet been downloaded at all. Some clients, like ABC, Azureus, BitTornado, TorrentStorm, and µTorrent have a "superseed" mode, where they try to only send out pieces that have never been sent out before, making the initial propagation of the file much faster. This is generally used only for a new torrent, or one, which must be re-seeded because no other seeds are available.

Swarm
Together, all peers (including seeders) sharing a torrent are called a swarm. For example, six ordinary peers and two seeders make a swarm of eight.

Torrent
A torrent can mean either a .torrent metadata file or all files described by it, depending on context. The torrent file contains metadata about all the files it makes downloadable, including their names and sizes and checksums of all pieces in the torrent. It also contains the address of a tracker that coordinates communication between the peers in the swarm.

Tracker
A tracker is a server that keeps track of which seeds and peers are in the swarm. Clients report information to the tracker periodically and in exchange receive information about other clients to which they can connect. The tracker is not directly involved in the data transfer and does not have a copy of the file.

Comparison to other file sharing systems

BitTorrent 4.0.4 running under Windows XP
The method used by BitTorrent to distribute files parallels the one used by the eDonkey2000 network, but nodes in eDonkey's file sharing network usually share and download a much larger number of files, making the bandwidth available to each transfer much smaller. Also eDonkey has queue-based system wherein there might be 200 people sharing the file but only one or two have queue free. Hence a user ends up getting files from only a few and rising up in rank in other users' queue list (while getting no download from them). BitTorrent transfers are typically very fast, because all nodes in a group concentrate on transferring a single file or collection of files. While the original eDonkey2000 client provided little "leech resistance", most new clients have some sort of system to encourage uploaders. eMule, for example, has a credits system whereby a client rewards other clients that upload to it by increasing their priority in its queue. However, the nature of the eDonkey2000 concept means download speeds tend to be much more variable, although the number of available files is far greater.

A similar method to BitTorrent was the Participation Level introduced in Kazaa in 2002. A user's Participation Level would increase when they uploaded and decrease when they downloaded. Then when a user uploaded a file, the person with the highest Participation Level would get it first, then the next highest, and so on. This can be visualized as a pyramid, with the clients who have the most upload bandwidth available at the top and those with less bandwidth on progressively lower levels.
This is the most efficient way to distribute a file to a large number of users: it is probable that even the people at the bottom of the pyramid will get the file faster than if the file was served by a non-P2P method. Unfortunately, the implementation adopted by Kazaa is considered by some to be flawed as it relies on the client accurately reporting their Participation Level and therefore it is easy to cheat using one of the many unofficial clients.

Authorized use of BitTorrent
A growing number of individuals and organizations are using BitTorrent to distribute their own material. Many adopters report that only by using BitTorrent technology, with its dramatically reduced demands on networking hardware and bandwidth, could they afford to distribute their files.

Software
Many major open source and free software projects encourage BitTorrent as well as conventional downloads of their products to increase availability and reduce load on their own servers. Examples include OpenOffice.org and most major Linux distributions, including SUSE and Ubuntu. BitTorrent is also used to distribute updates to the BitTorrent client itself, as well as to other clients such as Azureus and BitComet.

Games
Various sites on the Internet like gameupdates.org offers authorized game files via BitTorrent; the demo of the flight sim X-Plane is offered via BitTorrent, as are the World of Warcraft ingame patches. Another such example is PlaneShift, a free open-source MMORPG, which uses BitTorrent for its primary method of distribution.
Films

The film studio Warner Brothers Entertainment plans to distribute its films and TV shows using Bittorrent. The fan-film Star Wars: Revelations is distributing two DVD images as well as the film by itself via BitTorrent, while Star Wreck: In the Pirkinning and Cactuses, both feature-length films, were provided for download via BitTorrent.

Music
The SXSW (South by South West) music festival in Austin, Texas has released two packages of mp3 music files—nearly a thousand tracks—from their 2006 festival by BitTorrent download, along with trailers to two DVD films that can be purchased. Babyshambles, Pete Doherty's band, distributes two collections of music, Shaking and Withdrawn Megamix and Untitled by Bittorrent from their official website. In 2005, the rock group Harvey Danger began distributing their third full-length album, Little by Little..., using BitTorrent. Discipline Global Mobile (the record label/website begun by Robert Fripp) uses BitTorrent technology to distribute. The free music portal Jamendo also uses BitTorrent to distribute its 1000+ albums.

Conferences
Some Free and Open Source Software conferences have made their video recordings avaliable, such as DupalCon 2005, International Free Software Forum - fisl6.0 and fisl7.0, HITBSecConf 2003, 2004 and 2005, YAPC::NA::2005, GPLv3 European Conference, Triangle Bloggers Conference Chaos Communication Congress 22C3 just to name a few.
Other material

Peter Jackson's production diaries for King Kong have been posted for download using BitTorrent technology. Universal Studios also released footage of its film, "Fast and Furious: Tokyo Drift" with BitTorrent (http://www.bittorrent.com/tokyo_drift.html). Several anime companies have also used BitTorrent technology to release teaser episodes and trailers online for promotional purposes, as a sign of embracing technology that is often seen as a direct competitor. Furthermore, the NASA space agency recently included BitTorrent as a means to download some of their larger space image files.

Legal issues
BitTorrent, like any other file transfer protocol, can be used to distribute files without the permission of the copyright holder, the same as photocopiers can be used to duplicate books. BitTorrent has received some criticism for this ability.

Copyright enforcement
BitTorrent trackers have been frequent targets of raids and shutdowns due to claims of copyright infringement. BitTorrent metafiles do not actually store copyrighted data per se, and thus it is often claimed that BitTorrent trackers, which only store and track the metafiles and usually do not share any potentially copyrighted data, must therefore be legal. Despite this claim, there has been tremendous legal pressure, usually on behalf of the MPAA and RIAA, to shut down numerous BitTorrent trackers.

In December 2004, the Finnish police raided a major BitTorrent site, Finreactor.
The case is before the courts, and approximately 60 people, mostly administrators and moderators, are facing charges. Software and media companies are seeking damages worth 3.5 million euros in total. Two defendants were acquitted by reason of being underage at the time but they are being held liable for legal fees and compensation for illegal distribution ranging up to 60,000 euros. The court set their fine at 10% of the retail price of products distributed.

Suprnova.org, one of the most popular early BitTorrent sites, closed in December 2004, supposedly due to the pressure felt by Sloncek, the founder and administrator of the site. In December 2004, Sloncek revealed that Slovenian authorities had in fact confiscated the Suprnova computer servers. LokiTorrent, arguably the biggest torrent source after the demise of Suprnova, closed down soon after Suprnova. Allegedly, after threats from the MPAA, Edward Webber (known as 'lowkee'), webmaster of the site, was ordered by the court to pay a fine and supply the MPAA with logs (the IP addresses of visitors).

Webber, in the weeks following his receipt of the subpoena, had begun a fundraising campaign to pay lawyers fees in a legal battle against the MPAA. Webber raised approximately US$45,000 through a PayPal-based donation system. It is unclear how much of that money went to the MPAA, but taking into account the amount of damages he most likely had to pay, probably much of it. Following the agreement, the MPAA changed the LokiTorrent website to display a message intended to intimidate file sharers. Webber did not comment on this change.

On May 25, 2005, the popular BitTorrent website EliteTorrents.org was shut down by the United States Federal Bureau of Investigation and Immigration and Customs Enforcement. At first it was thought that a malicious hacker had gained control of the website, but it was soon discovered that the website had been taken over by the US government. Ten search warrants relating to members of the website were executed. - Newspaper, Butler Eagle, PA

On October 24, 2005, a 38-year-old Hong Kong BitTorrent user Chan Nai-ming (using the handle Lit. The master of cunning, while the magistrate referred to him as Big Crook) allegedly distributed the three movies Daredevil, Red Planet and Miss Congeniality in violation of copyright, subsequently uploading the torrent file to a newsgroup (See HKSAR v Chan Nai Ming). He was convicted of breaching the copyright ordinance, Chapter 528 of Hong Kong law. The magistrate remarked that Chan's act caused significant damage to the interest of copyright holders. He was released on bail for HK$5,000, awaiting a sentencing hearing, though the magistrate himself admitted the difficulty of determining how he should be sentenced due to the lack of precedent for such a case. On November 7, 2005, he was sentenced to jail for three months but was immediately granted parole pending an appeal to the High Court.

On November 23, 2005, the movie industry and Bram Cohen, the creator of BitTorrent, signed a deal they hoped would reduce the number of unlicensed copies shared on the downloading network. The deal covered films found via the bittorrent.com website run by BitTorrent, Inc. It meant BitTorrent.com had to remove any links to unlicensed copies of films made by seven Hollywood movie studios. As it covered only the BitTorrent.com website, it is unclear what overall effect this has had on copyright infringement on the network.

In June 2006, the popular website Newnova.org, an exact replicant of Suprnova, was also subject to closure.

The Pirate Bay is another popular BitTorrent website which was formed out of a Swedish anti-copyright group. The site also contains torrents, which point to copies of copyright-protected material. The Pirate Bay is notorious for its "legal" section in which letters and replies on the subject of alleged copyright infringements are publicly displayed. The replies are written in a humorous manner and a hard copy of one was even sold on eBay for USD $255. On May 31, 2006, however, Swedish police raided The Pirate Bay’s servers, which are based in Sweden,; the site owners might be facing charges for copyright infringement or facilitating it according to the accusations on the search warrant. No charges have been made so far. However, after securing new servers in The Netherlands and using a recent backup, The Pirate Bay was back online in less than 72 hours. Recently, The Pirate Bay has returned to Sweden. The return has been facilitated by the public and media backlash against the Swedish Government's actions. The Pirate Bay is now, supposedly, going to counter-sue the Swedish government for millions of Swedish kronor (SEK) lost from having their website shut down.

HBO, in an effort to combat the distribution of its programming on BitTorrent networks, has been sending out cease and desist letters to the Internet Service Providers of BitTorrent users. Many users have reported receiving letters from their ISP's that threatened to cut off their internet service if the alleged infringement continues. HBO, unlike the RIAA, has so far declined to sue anyone for sharing the files.

Legal defenses
There are two major differences between BitTorrent and many other peer-to-peer file-trading systems, which advocates suggest make it less useful to those sharing copyrighted material without authorization. First, BitTorrent itself does not offer a search facility to find files by name. A user must find the initial torrent file by other means, such as a web search. Second, BitTorrent makes no attempt to conceal the host ultimately responsible for facilitating the sharing: a person who wishes to make a file available must run a tracker on a specific host or hosts and distribute the tracker address(es) in the .torrent file. While it is possible to simply operate a tracker on a server that is located where the copyright holder cannot take legal action, this feature of the protocol does imply some degree of vulnerability that other protocols lack. It is far easier to request that the server's ISP shut the site down than it is to find and identify every user sharing a file on a traditional peer-to-peer network. However, with the use of a distributed hash table (DHT), a tracker is no longer required, although they are often still used so that clients that do not support DHT can still connect to the swarm.

Etiquette
Because BitTorrent relies on the upstream bandwidth of its users — and the more users, the more aggregate bandwidth is available for sharing the files — it is considered good etiquette to leave one's BitTorrent client open after downloading has completed so that others may continue to gain from the file that has been distributed.

It is not clear, however, how long one should leave their client open after downloading has finished. Many trackers/sites ask their users to seed at least 72 hours and/or until a share ratio of 1.0 is reached. Members-only trackers and sites enforce this rule, thus files on these websites have a higher traffic than others, and the torrents on these websites remain active longer than other free torrent sites/trackers. Many clients report the byte traffic upstream as well as down, so the user can see how much they have contributed back to the network. Some clients also report the "share ratio", a number relating the amount of data uploaded to the amount downloaded. A share ratio of 1.0 means that a user has uploaded as much data as they have downloaded. A share ratio greater than 1 means that a user has uploaded more than they have downloaded. It is generally considered good form to at least share back the equivalent amount of traffic as the original file size.

Share ratios are more important on BitTorrent than they are on other peer-to-peer file sharing networks, because many BitTorrent trackers require users to maintain a minimum global share ratio. On some trackers that require users to register, the minimum global share ratio may start at around 0.5 and increase over time, so that the user has adequate time to upload and share their files. Users with a share ratio below the minimum may be put into a restricted "upload-only" mode, where they may not download until their share ratio reaches the minimum.

While it is impossible for all users who download a given torrent to achieve a 1.0 ratio on it (because the net ratio of all users is 1.0 and the original source doesn't download anything), it is more of a guideline to encourage the average upstream of a given network. Some networks, for example, prevent access to new torrents for the first 24-48 hours that the torrent is active to people with overall ratios of less than 1.0 and a certain amount of data uploaded.

The amount of time the client is left open may be more important than the amount of traffic contributed, since new users attempting to download a file will first need to find peers hosting the file.

Many advanced trackers now track statistics such as how many seeders and downloaders were on a torrent at the time of a user's disconnect as many consider this information more important than just the user's ratio of data downloaded/uploaded.

Limitations and security vulnerabilities
BitTorrent does not offer its users anonymity. It is possible to obtain the IP addresses of all current, and possibly previous, participants in a swarm from the tracker. This may expose users with insecure systems to attacks.

Another drawback is that BitTorrent file sharers, compared to users of client/server technology, often have little incentive to become seeders after they finish downloading. The result of this is that torrent swarms gradually die out, meaning a lower possibility of obtaining older torrents. Some BitTorrent websites have attempted to address this by recording each user's download and upload ratio for all or just the user to see, as well as the provision of access to older torrent files to people with better ratios. Also, users who have low upload ratios may see slower download speeds until they upload more. This prevents users from leeching, since after a while they become unable to download much faster than 1-10 kB/s on a high-speed connection. Some trackers exempt dial-up users from this policy, because they cannot upload faster than 1-5 kB/s.

BitTorrent is best suited to continuously connected broadband environments, since dial-up users find it less efficient due to frequent disconnects and slow download rates.

New developments
The BitTorrent protocol is still under development and therefore may still acquire new features and other enhancements such as improved efficiency.

In May 2005, Bram Cohen released a new beta version of BitTorrent that eliminated the need for web site hosting of centralized servers known as "trackers". It is now possible to have a torrent up in minutes, with a file, a website, and no understanding of how it works. In addition, Cohen launched a new search service on BitTorrent's website, similar to those found on other popular sites such as The Pirate Bay.

Cohen explained that the tracker removal feature is part of his ongoing effort to make publishing files online "painless and disruptively cheap". The move is only one of several designed to remove BitTorrent's dependence on centralized trackers.
This change is said to cause some trouble in the legal efforts to shut down illegal file sharing. However, Tarun Sawney, BSA Asia antipiracy director, said BitTorrent files could still be identified, since with or without the tracker sites, actual users still host the infringing files.

Alternative approaches
The BitTorrent protocol provides no way to index torrent files. As a result, a comparatively small number of websites have hosted the large majority of torrents linking to copyright material, rendering those sites especially vulnerable to lawsuits. In response, some developers have sought ways to make publishing of files more anonymous while still retaining BitTorrent's speed advantage. The Shareaza client, for example, provides three alternatives to BitTorrent: eDonkey2000, Gnutella, and Shareaza's native network, Gnutella2 (G2). If the tracker is down, it can finish the file over the other protocols, and/or find new (Shareaza) peers over G2. The use of distributed trackers is also one of the goals for Azureus 2.3.0.2 and BitTorrent 4.1.2. Another interesting idea that has surfaced recently in Azureus is virtual torrent. This idea is based on the distributed tracker approach and is used to describe some web resource. Right now, it is used for instant messaging. It is implemented using a special messaging protocol and requires an appropriate plugiIn. Anatomic P2P is another approach, which uses a decentralized network of nodes that route traffic to dynamic trackers.

BitTorrent search / Trackerless torrents
Recently, Bram Cohen released his own BitTorrent search engine, which searches popular BitTorrent trackers for torrents, although it does not host nor track torrents itself. From software version 4.2.0, BitTorrent also supports "trackerless" torrents, featuring a DHT implementation that allows the client to download torrents that have been created without using a BitTorrent tracker.

Web seeding (unofficial feature)
One recently implemented feature of BitTorrent is web seeding. The advantage of this feature is that a site may distribute a torrent for a particular file or batch of files and make those files available for download from that same web server application; this can simplify seeding and load balancing greatly once support for this feature is implemented in the various BitTorrent clients. In theory, this would make using BitTorrent almost as easy for a web publisher as simply creating a direct download while allowing some of the upload bandwidth demands to be placed upon the downloaders (who normally use only a very small portion of their upload bandwidth capacity). This feature is an unofficial one, created by TheSHAD0W, who created BitTornado. The latest version of the popular download manager, GetRight supports downloading a file from both HTTP/FTP protocols and using BitTorrent.

Broadcatching
Another proposed feature combines RSS and BitTorrent to create a content delivery system dubbed broadcatching. Since a Steve Gillmor column for Ziff-Davis in December 2003, the discussion has spread quickly among many bloggers (Techdirt, Ernest Miller, and former TechTV host Chris Pirillo, for example). As Scott Raymond explained:
"I want RSS feeds of BitTorrent files. A script would periodically check the feed for new items, and use them to start the download. Then, I could find a trusted publisher of an Alias RSS feed, and 'subscribe' to all new episodes of the show, which would then start downloading automatically — like the 'season pass' feature of the TiVo."
While potential illegal uses abound as is the case with any new distribution method, this idea lends itself to a great number of ideas that could turn traditional distribution models on their heads, giving smaller operations a new opportunity for content distribution. The system leans on the cost-saving benefit of BitTorrent, where expenses are virtually non-existent; each downloader of a file participates in a portion of the distribution. One early adoption of this concept is IPTV show mariposaHD, which uses BitTorrent to distribute large (1-2 GB) WMVHD files of high-definition video.

RSS feeds layered on top keep track of the content, and because BitTorrent does cryptographic hashing of all data, subscribers to the feed can be sure they're getting what they think they're getting, whether that winds up being the latest Sopranos episode, or the latest Sveasoft firmware upgrade. (Naturally, however, ensuring that the same data reaches all nodes neglects the possibility that the original, source file may be corrupted or incorrectly labeled.)
One of the first open source attempts to create a client specifically for this was Democracy Player. The idea is already gaining momentum however, with other Free Software clients such as PenguinTV and KatchTV also now supporting broadcatching.

APIs
The BitTorrent web-service MoveDigital has made available ability to any web application capable of parsing XML through its standard Representational State Transfer (REST) based interface. Additionally, Torrenthut is developing a similar torrent API that will provide the same features, as well as further intuition to help bring the torrent community to Web 2.0 standards. Alongside this release is a first PHP application built using the API called PEP, which will parse any Really Simple Syndication (RSS 2.0) feed and automatically create and seed a torrent for each enclosure found in that feed.

Encryption
Protocol header encrypt (PHE), Message stream encryption (MSE), or Protocol encryption (PE) are features of some BitTorrent clients that attempt to make BitTorrent hard to throttle. MSE and PE are two names for the same protocol. At the moment Azureus, Bitcomet and µTorrent, the three biggest BitTorrent clients, support MSE/PE encryption.

Some ISPs throttle BitTorrent traffic because it makes up a large proportion of total traffic and the ISPs don't want to spend money purchasing extra capacity. Encryption makes BitTorrent traffic harder to detect and therefore harder to throttle. Recently, ISPs have announced possible future hardware upgrades in order to minimize BitTorrent traffic. Several universities have already taken these steps, including the University of Maryland, College Park, Emory University, Brigham Young University, ASU, UTC, and WPI. ISPs sometimes use products such as Allot Inc.'s NetEnforcer to try to throttle encrypted BitTorrent traffic.

Peer exchange
Peer exchange (PEX) is another method to gather peers for BitTorrent in addition to trackers and DHT. Peer exchange checks with known peers to see if they know of any other peers.

Multitracker
Another unofficial feature is an extension to the BitTorrent metadata format proposed by John Hoffman. It allows the use of multiple trackers per file, so if one tracker fails, others can continue supporting file transfer. It is implemented in several clients, such as BitTornado,KTorrent and µTorrent. Trackers are placed in groups, or tiers, with a tracker randomly chosen from the top tier and tried, moving to the next tier if all the trackers in the top tier fail.

BitTorrent-related applications
Because of the open nature of the protocol, many clients have been developed that support numerous platforms and written using various programming languages.

Thursday, September 28, 2006

Blog

Blog
A blog is website that contains written material, links or photos being posted all the time, usually by one individual, on a personal basis. The term is a shortened form of weblog, although the latter term has since fallen into disuse.

Blog Basics
Blog Defined
A weblog or blog is a web-based publication of periodic articles (posts), usually presented in reverse chronological order. It is an online journal with one or many contributors.

Blog Content
Besides straight text and hyperlinks, some blogs specialize in incorporating other forms of media such as images, video, or a particular theme. Many bloggers that otherwise stick to text may use audioblogging to be able to phone in or otherwise post spoken entries on their blogs. A notable, niche type of blog is the MP3 blog, which specializes in posting music from specific genres. New words have been coined for many of these content-typed blogs, such as "moblog" (for "mobile blog").
Components of a Blog Post

A blog is made up of the following components:
Post Date - date:time the post was published
Category - category the post is labeled with (can be one or more)
Title - main title of the post
Body - main content of the post
Trackback - links back from other sites
Comments - comments added by readers
Permalink - the URL of the full, individual article
Footer - usually at the bottom of the post, often showing post date/time, author, category, and stats such as number of comments or trackbacks.
Difference from traditional sites

Blogs differ from traditional web sites in that, rather then being composed of many individual pages connected by hyperlinks, they are composed of a few templates (usually Main Page, Archive Page, and Individual Article/Item Page), into which content is fed from a database. This provides many advantages over traditional sites, including:
it allows for easy creation of new pages, since new data is entered into a simple form (usually with Title, Category, and the body of the article), and then submitted.

The templates take care of adding the article to the home page, creating the new full article page (permalink), and adding the article to the appropriate date or category-based archive it allows for easy filtering of content for various presentation, like by date, category, author, or one of many other attributes
most blog platforms allow the administrator to invite and add other authors, whose permissions and access are easily managed

Difference from Forums or Newsgroups
Blogs differ from forums or newsgroups in that only one person or group can create new subjects for discussion on their blog. A network of blogs can act similarly to a single forum in that each individual entity in the blog network creates subjects of their choosing for others to discuss; these different subjects are presented in a thread-like format on a meta-forum with no one single poster having any greater control over the content of the thread than any other. Such networks require substantial interlinking to pull off, and so a group blog with multiple people holding posting rights is more common. Because they "go first," blog owners often has control over how a subject is discussed on their blog due to their ability to frame the issue.

History
Precursors
Electronic communities existed before internetworking, but generally had some quality to them. For example the AP wire was, in effect, similar to a large chat room where there were "wire fights" and electronic conversations. Another pre-digital electronic community, Amateur (or "ham") radio, allowed individuals who set up their own broadcast equipment to communicate with others directly. Ham radio also had logs called "glogs" that were personal diaries made using wearable computers in the early 1980s.

Before blogging became popular, digital communities took many forms, including Usenet, email lists and bulletin boards. In the 1990s Internet forum software, such as WebX, created running conversations with threads. The term "thread", in reference to consecutive messages on one specific topic of discussion, comes from email lists and Usenet as well, and "to post" from electronic bulletin boards, borrowing usage directly from their corkboard predecessors. Many of the terms from weblogging were created in these earlier media.

Diarists kept journals on the Web: most called themselves online diarists, journalists, journallers, or journalers. A few called themselves escribitionists. The Open Pages webring contained members of the online-journal community. The first famous journaller was probably Justin Hall.

Other forms of journals kept online also existed. A notable example was game programmer John Carmack's widely read journal, published via the finger protocol.
Websites, including both corporate sites and personal homepages, had and still often have "What's New" or "News" sections, often on the index page and sorted by date.

Blogging begins
Blogging combined the personal web page with tools to make linking to other pages easier, specifically blogrolls and TrackBacks, as well as comments and afterthoughts. This way, instead of a few people being in control of threads on a forum, or anyone able to start threads on a list, there was a moderating effect that was the personality of the weblog's owner. Justin Hall, who began eleven years of personal blogging in 1994 while a student at Swarthmore College, is generally recognized as one of the earliest bloggers.

The term "weblog" may have been coined by Jorn Barger in December 1997. The shorter version, "blog", was coined by Peter Merholz, who, in April or May of 1999, broke the word weblog into the phrase "we blog" in the sidebar of his weblog. This was interpreted as a short form of the noun and also as a verb to blog, meaning "to edit one's weblog or a post to one's weblog". The site Open Diary, while not using the term blog until recently, launched in 1998, had over 2000 diaries by 1999, and near 400 000 as of September 2005. Blog usage spread during 1999, with the word being further popularized by the near-simultaneous arrival of the first hosted weblog tools: Evan Williams and Meg Hourihan's company Pyra Labs launched Blogger (which was purchased by Google in February 2003) and Paul Kedrosky's GrokSoup. As of March 2003, the Oxford English Dictionary included the terms weblog, weblogging and weblogger in their dictionary.

One of the pioneers of the tools that make blogging more than merely websites that scroll is Dave Winer. One of his most important contributions was the creation of servers which weblogs would ping to show that they had been updated. Blog reading utilities use the aggregated update data to show a user when their favorite blogs have new posts.

Blogging's rise to influence
Among the first established political blogs with U.S.-wide audiences were Andrew Sullivan's AndrewSullivan.com, Ron Gunzburger's Politics1.com, Jerome Armstrong's MyDD.com, and Markos Moulitsas Zúniga's DailyKos -- all of which launched widely read blogs in 2001-02. The first blog-driven political controversy was probably the fall of U.S. Senate Majority Leader Trent Lott, who had remarked, at a party honoring U.S. Senator Strom Thurmond, that Thurmond's leadership abilities may have made him a good President. Since Thurmond had spent much of his early political career sympathetic to white supremacists, Lott's statements were conveyed in the media to be racist. In the aftermath, bloggers such as Josh Marshall strove to demonstrate that his remarks were not an isolated misstatement, by finding evidence including quotes from other previous speeches of Lott's which were taken to be racist. Their efforts kept the story alive in the press until a critical mass of disapproval forced Lott to resign his position as Senate Majority Leader.

By this point blogging was enough of a phenomenon that how-to manuals had begun to appear, primarily focusing on using the tools, or creating content. But the importance of a blog as a way of building an electronic community had also been written on, as had the potential for blogs as a means of publicizing other projects. Established schools of journalism began researching the blogging phenomenon, and noting the differences between current practice of journalism and blogging.
Since 2003, blogs have gained increasing notice and coverage for their role in breaking, shaping, or spinning news stories. One of the most significant events was the sudden emergence of an interest in the Iraq war, which saw both left-wing and right-wing bloggers taking measured and passionate points of view that did not reflect the traditional left-right divide. The blogs which gathered news on Iraq, both left and right, exploded in popularity. The use of blogs by established politicians and political candidates—particularly Howard Dean and Wesley Clark—to express opinions on the war and other issues of the day, cemented their role as a news source. Meanwhile, the increasing number of experts who blogged, such as Daniel Drezner and J. Bradford DeLong, gave blogs a built-in source of in-depth analysis.
The Iraq war was the first "blog war" in another way: Iraqi bloggers gained wide readership, and one, Salam Pax, published a book of his blog. Blogs were also created by soldiers serving in the Iraq war. Such "milblogs" gave readers a new perspective on the realities of war, as well as often offering differing viewpoints from those of official news sources. Blogs were often used to draw attention to obscure news sources, for example posting links to the traffic cameras in Madrid as a huge anti-terrorism demonstration filled the streets in the wake of the March 11 attacks. Bloggers would often provide nearly-instant commentary on televised events, which became a secondary meaning of the word "blogging", such as "I am blogging Rice's testimony," i.e., "I am posting my reactions to Rice's testimony to my blog as I watch it".

By the end of 2003 top rated blogs Instapundit, Daily Kos, and Atrios were receiving over 75,000 unique visitors per day.

Blogging goes mainstream
In 2004, the role of blogs became increasingly mainstream, as political consultants, news services and candidates began using them as tools for outreach and opinion formation. Even politicians not actively involved in a campaign such as Tom Watson, a UK Labour Party MP, began to use blogging as a means for creating a bond with constituents and creating a channel for their ideas and opinions. Minnesota Public Radio broadcast a program by Christopher Lydon and Matt Stoller called "The Blogging of the President", which covered the transformation in politics that blogging seemed to presage. The Columbia Journalism Review began regular coverage of blogs and blogging. Anthologies of blog pieces began to reach print, and blogging personalities began appearing on radio and television. In the summer of that year both the Democratic and Republican National Conventions credentialed bloggers, and blogs became a standard part of the publicity arsenal, with mainstream programs, such as Chris Matthews' Hardball, forming their own blogs. Merriam-Webster's Dictionary declared "blog" as the word of the year in 2004.

Blogs were some of the driving forces behind the "Rathergate" scandal involving Dan Rather of CBS and memos used on the show 60 Minutes II. Within 72 hours a group of conservative bloggers had built a case that they were likely forgeries. The evidence presented eventually created such concern over the issue that CBS was forced to address the situation and make an apology for their inadequate reporting techniques. Two months later, Dan Rather announced that he would step down from the CBS anchor chair. This is viewed by many bloggers as the advent of blogs' acceptance by the mass media as a source of news. It also showed how blogs could keep the pressure on an established news source, forcing defenses and then a retraction of the original story.

Blogging is also used now to break consumer complaints and vulnerabilities of products, in the way that Usenet and email lists once were. One such example is accusations about vulnerability of Kryptonite 2000 locks.

Bloggers have also moved over to other media. Duncan Black (a.k.a. Atrios), Glenn Reynolds, Markos Moulitsas Zúniga (a.k.a. Kos), Ana Marie Cox (a.k.a. Wonkette), and others have appeared on radio and/or television. Hugh Hewitt is an example of a media personality who has moved in the other direction, adding to his reach in "old media" by being an influential blogger.

In the United Kingdom, The Guardian newspaper launched a redesign in September 2005, which included a daily digest of blogs on page 2.

In January 2005, Fortune magazine listed Peter Rojas, Xeni Jardin, Ben Trott and Mena Trott, Jonathan Schwartz, Jason Goldman, Robert Scoble, and Jason Calacanis as eight bloggers that business people "could not ignore."

Blogging and culture
Blogging however, was as much about technology as politics, and the proliferation of tools to run blogs and the communities around them connected blogging with the Open Source movement. Writers such as Larry Lessig and David Weinberger used their blogs to promote not just blogging, but more generally different social models. One of the running discussions within journalism and blogging is what "blogging" means for the way news "happens" and is covered. This leads to questions over intellectual property and the role of the mass media in society. Many bloggers differentiate themselves from the mainstream media, while others are members of that media working through a different channel.

Many bloggers have large agendas, and see blogging as part of Open Source Politics, or the ability of people to participate more directly in politics, helping to frame the debate. Some institutions see blogging as a means of "getting around the filter" and pushing messages directly to the public.

The free speech imperative of the blog world has also had a deep social impact. For example, a number of companies have clashed with bloggers, firing a few of them (for example Heather Armstrong, Mark Jen or Jessica Cutler).

Blogs have also been seen as repositories for information about the state of mind of certain people: in some cases, they could provide insight in the minds of people who committed suicide, people who committed crimes, or people who were victims of a crime.

Blogs have also had an influence on minority languages, bringing together scattered speakers and learners; this is particularly the case with Scottish Gaelic blogs, whose creators can be found as far away from traditional Gaelic areas as Kazakhstan and Alaska. Blogs are also used regularly by Welsh language activists. Minority language publishing has traditionally been expensive, with a small readership, and blogs effectively counteract this.

Creating and publishing weblogs
Since their introduction, a number of software packages have appeared to allow people to create their own weblog. Blog hosting sites and Web services to provide editing via the Web have proliferated. Common examples include Blogger and LiveJournal.
Many more advanced bloggers prefer to generate their blogs by using server-side web applications such as Nucleus CMS, Movable Type, bBlog, WordPress, Drupal, b2evolution, boastMachine, Antville, Serendipity and Textpattern to publish on their own website or a third party site, or to host a group of blogs for a company or school. Such programs provide greater flexibility and power, but require more knowledge. If they provide a Web interface for editing, server-based systems make it easy for travelers to create and edit text; many travelers like to produce their travelblogs from Internet cafes while they travel around the globe.

In addition, some people program their own blogs from scratch by using PHP, CGI, ASP, Perl, ColdFusion or other server side software. While these are much more difficult to create, they add a maximum potential for creativity.

The phenomena of multi-blogging refers to individuals, businesses or institutions that maintain multiple blogs simultaneously. If one runs a single blog, technically they are a blogger; however if one creates, maintains, and runs 2, 10, 50, 100 or more blogs, they are a multi-blogger.

Two features which are common to blogging are "blogrolls" and "commenting" or "feedback."

A blogroll is a list of other blogs that are linked separately from any article. This is one means by which a blogger creates a context for his blog, by listing other blogs that are similar to his/her own, or blogs the blogger thinks may be of relevance to users. It is also used as measure of the number of citations a blog has, and is used to rank "blog authority" in a manner similar to the way that Google uses hard coded HTML linking to create "page rank." Still another use of the "blogroll" is reciprocal linking: bloggers agree to link to each other, or link to another blog in hopes of getting a link in return.

Another central, and sometimes controversial, aspect of blogging is the use of a feedback comment systems. A comment system allows users to post their own comments on an article or "thread." Some blogs do not have comments, or have a closed commenting system which requires approval from those running the blog. For other bloggers, including several very prominent ones, comments are the crucial feature which distinguishes a "true" blog from other kinds of blogs. Commenting can either be built into the software, or added by using a service such as HaloScan. If a blog has regular commenters, this is referred to as the blog's community.

Tools such as Ecto, Elicit and w.bloggar allow users to maintain their Web hosted blog without the need to be online while composing or editing posts. Enhancements to weblog technology continue to be developed, such as the TrackBack feature introduced by Movable Type in 2002 and subsequently adopted by other software companies to enable automatic notification between websites of related content—such as a post on a particular topic or one which responds to a post on another blog. Blog has gone as far as implementing threaded trackbacks on comments, and comments on trackbacks.

Blogs with features such as TrackBack are credited with complicating search engine page ranking techniques. Integrating these into search engines has proven to be a challenge, and has been used to deliberately "push" page rankings. However, as one Google executive remarked, it is the search engine's job to find the ways that a website represents a "vote" for another website.

Web hosting companies and online publications also provide blog creation tools, such as Salon, Tripod, and America Online.

Types of weblogs
News and Politics
When discussed in the news, the term blog is often understood to refer to a political blog. Political blogs may take a number of forms. Often an individual will link to articles from news web sites and post their own comments as well. Others focus on long essays about current political topics. Most news, activism, and issue-based weblogs follow the same format.

Of note is the recent trend of political candidates to incorporate blogging into their campaigns. Lower level politicians may do their own blogging, while more prominent candidates, such as presidential candidates, will leave the blogging to their campaign staff.

Personal
In common speech, the term blog is often used to describe an online diary or journal, such as LiveJournal. The weblog format of an online diary makes it possible for users without much experience to create, format, and post entries with ease. People write their day-to-day experiences, complaints, poems, prose, illicit thoughts and more, often allowing others to contribute, fulfilling to a certain extent Tim Berners-Lee's original view of the World Wide Web as a collaborative medium. In 2001, mainstream awareness of online diaries began to increase dramatically.

Online diaries are integrated into the daily lives of many teenagers and college students, with communications between friends playing out over their blogs. Even fights may be posted in the diaries, with not-so-veiled insults of each other easily readable by all their friends, enemies, and complete strangers. Xanga is a very popular portal for blogs of this type.

Personal opinions on experiences and hobbies are very common in the blog world. Blogs have given the opportunity for people to express their views to a mass audience. What may have been created to be used among a few friends may be viewed by the internet-using public.

Topical
Topical blogs focus on a specific niche, often a technical one. An example is Google Blog, covering nothing but news about Google. Another example is a soldier blog. Many blogs now allow categories, which means a general blog can be reshuffled to become a topical blog at the user's need. Topical blogs can also cover local information.

Health
Blogs written as personal accounts of living with a specific health issue, sharing information about the experience with others who have an interest in that health issue and providing mutual support. A major category of health blogs are medical blogs, which themselves generally fall into two categories. One type is a blog written by a health care professional about his or her work experiences, medical news or other personal thoughts. A more recent trend is a blog that deals with actual patient cases. This latter blog allows other physicians to submit cases to the web site. Physicians can then offer comments or help with the case. Although still in its infancy, this format could theoretically improve patient care by allowing the primary doctor to get feedback by other experts in the field. When writing about patient cases, health care professionals must protect their patients' confidentially as mandated by HIPAA.

Literary
Given the obvious focus on words, it is not surprising that the Grub Street tradition has continued on the internet with daily commentary emanating from literary blogs (or litblog).

Travel
Famous explorers wrote their journeys down on paper. These days, modern travelers have used blogs as a way to share their stories and photos, even while they are traveling around the world.

Research
An increasing number of scholars and students blog their research notes, combining the traditional scholar's private notebook with public discussion. A related genre is the anonymous professor's blog, where the various issues related to academia may be freely discussed.

Legal
Blogs by lawyers or law students, or which discuss law and legal affairs are often referred to as blawgs. By extension, the creator of such a blog is a blawger, sometimes spelled blawgger.

The coining of the term blawg is generally attributed by blawgers to Denise Howell of Bag and Baggage. See Jeff Rosen Gets All Mixed Up on Blawgs, Blogging and Other Things by law blogger Dennis Kennedy (criticizing Jeff Rosen for limiting the definition of blawg to law-student blogs, and for failing to credit Denise).
Some blawgs are narrow and deal with a focused and/or technical area of law.
Others, like the Volokh Conspiracy, deal with whatever topic the blawgers wish to discuss.

Media
Some blogs serve as media watchdogs, reporting on falsehoods or inconsistencies that are presented as facts in the mass media. Many media blogs are focused exclusively on one newspaper or television network.

Religious
Some blogs discuss religious topics. Religious blogs show the public's points of view on various controversies both in religion and in politics, economics, and life in general.

Collaborative (also collective or group)
Many weblogs are written by more than one person about a specific topic. Collaborative weblogs can be open to everyone or limited to a group of people. MetaFilter is an example of this type of weblog.

Slashdot, whose status as a blog has been debated, nevertheless has a team of editors who approve and post links to technology news stories throughout the day. Although Slashdot does not refer to itself as a weblog, it shares some characteristics with weblogs.

Indymedia is an early (1999) example of a collaborative blog (although the term blog wasn't in circulation yet) that was created to cover a specific event (the WTO in Seattle), but has since spread around the world.

A new form of blog represents a fusion of bloggers and traditional media sources, allowing for topics covered in the traditional media, both print and broadcast, to be fleshed out on the web. One prominent early example of this sort of blog is the Dallas Morning News editor's blog.

Eclectic
From the Slashdot style blog comes eclectic blogs, which tend to focus on specific niches. Such sites contain articles and stories from other blogs and news sources on the web. There are often few articles actually written by the authors of these blogs and instead the blogs themselves tend to function as passageways for readers to find the actual source of the article or original posting.

Educational
Blogs have been used for several educational applications. Students can use weblogs as records of their learning and teachers can use weblogs as records of what they taught. For example, a teacher can blog a course, recording day-by-day what was taught, including links to Internet resources, and specifying what homework students are required to carry out. This application has many advantages: (1) a student can quickly catch-up if they miss a class; (2) the teacher can use the blog as a course plan; and (3) the blog serves as an accurate summary of the course that prospective students or new teachers can refer to.

There are other educational applications of blogs. Students can blog an educational excursion, recording day-by-day (or hour by hour) where they went, what they saw and what they learned - including photographs, audio or video. The collaborative features of blogs can be used to permit several students to contribute to the blog.

Directory
Directory weblogs are useful for web-surfers because they often collect numerous web sites with interesting content in an easy to use and constantly updated format.
News-related weblogs can fall into this category or be political blogs.

Directory weblogs should not be confused these with weblog directories, such as BlogWise.

These provide a more structured collection of weblog links, and will often offer novel services and interesting views of the data within the directory. These can be a good source of like-minded bloggers, or bloggers situated near you.
Forums/Other CMS systems

An internet forum can sometimes be regarded as a weblog, though usually there is a distinction between the two; the most obvious difference is that in a forum any user can post a new topic of discussion, while in a blog only one or a handful of site owners can do so. However, if forum software is used for the purposes of publishing, for example, an online journal, it could be regarded as a weblog. The distinction between blogs and forums is sometimes gray in real life, and sites such as Slashdot, Indymedia and Daily Kos can all be said to combine elements of the two.

Business
Entrepreneurial
A number of entrepreneurs are establishing blogs to promote their businesses. Often business blogs act as a showcase for entrepreneurs to provide a window into the behind-the-scenes goings on at their business, presenting a more personal "face" to the public rather than a cold corporate persona. In some cases the blog itself is the core of the business bringing in revenue from advertising, selling products or information.

Corporate
Increasingly, employees of corporations are posting official or semi-official blogs about their work. The employers however, do not always appreciate the endeavor. In January 2005 Joe Gordon was fired from Waterstone's bookshop in Edinburgh, Scotland, because he referred to his boss as an "asshole in sandals." In 2004 Ellen Simonetti, a Delta Air Lines flight attendant, was fired for posing in uniform on her blog. David Corby was fired from Wells Fargo in 2002 after he complained about a department policy forcing employees to wear American flag pins to show support for the victims of the September 11, 2001 attacks. He described the event as fascist. Perhaps the most famous case of all occurred when "Troutgirl" Joyce Park was fired from Friendster because she discussed the rationale behind the website's technology conversion from J2EE to PHP on her blog.

Other employers have reacted differently. For instance, when Power Line bloggers were attacked by a Star Tribune columnist, one of the bloggers' employers came to his defense.

With the rise in popularity of blogs in 2004 senior management caught on to the trend and by January 2005 several types of organizations, including universities, had started using blogs to communicate with their stakeholders. Some believe this corporate takeover of a tool that was used primarily by Internet enthusiasts will lead to a decrease in the popularity of the medium. Others believe that the use of blogs by organizations will add new voices and vitality to the medium. At any rate, there is little evidence that the growth rate of the blogosphere has slowed. A prime example of senior management blogging is GM's Fastlane blog [10], edited, among others, by GM vice chairman Bob Lutz.

In 2005 the Electronic Frontier Foundation (EFF) published the guide How to Blog Safely (About Work or Anything Else).

Busiplogs
Business spam blogs (busiplogs), a term coined by LS Blogs, are blogs that are specifically written in order to promote a product/service or business. They have no value, or information of interest, to anyone other than their owner. They are specifically designed to only promote their business. Usually the quality of the blog is low, and often the content is drawn from third party sites.

Advice
Many weblogs provide expert advice.
Many small businesses are also using blogs to offer advice and better connect with their clients. These blogs are particularly prevalent in the real estate industry where agents typically have a great deal of flexibility in marketing themselves.
Another type of small online business using blogs are independent software development firms.

Personification Blogging
That act of blogging for a non-human being or object. An example would be writing a blog for your dog.

Common terms
Blogging, like any hobby, has developed something of a specialised vocabulary. The following is an attempt to explain a few of the more common phrases and words, including etymologies when not obvious. For a complete list, see List of blogging terms.

Audioblog
A blog where the posts consist mainly of voice recordings sent by mobile phone, sometimes with some short text message added for metadata purposes. (cf. podcasting)

Blog feed
The XML-based file in which the blog hosting software places a machine-readable version of the blog so that it may be "syndicated" for further distribution on the web. Formats such as RSS and Atom are used to structure the XML file.

Blogosphere
All blogs, or the blogging community.

Blogroll
A list of blogs. Usually a blogger features a list of his favorite blogs in the sidebar of his blog. These lists can be made dynamic using services like BlogRolling.

Blog site
The web location (URL) of a blog, which may be either a dedicated domain, a sub-domain, or embedded within a web site.

Blogsite, sometimes confused with a simple blog or blog site, but a blogsite is a web site which combines blog feeds from a variety of sources, as well as non-blog sources, and adds significant value over the raw blog feeds.


Blogstorm
When a large amount of activity, information and opinion erupts around a particular subject or controversy in the blogosphere, it is sometimes called a blogstorm or blog swarm.

Comment spam
Like e-mail spam. Robot “spambots” flood a blog with advertising in the form of bogus comments. A serious problem that requires bloggers and blog platforms to have tools to exclude some users or ban some addresses in comments.

Dark Blog
A non-public blog (e.g. behind a firewall)

Moblog
A portmanteau of "mobile" and "blog". A blog featuring posts sent mainly by mobile phone, using SMS or MMS messages. They are photo- or videoblogs (mobvlog).

Permalink
Permanent link. The unique URL of a single post. Use this when you want to link to a post somewhere.

Ping
The alert in the TrackBack system that notifies the original poster of a blog post when someone else writes an entry concerning the original post.

Photoblog
A blog mostly containing photos, posted constantly and chronologically.

Podcasting
Posting audio and video material on a blog and its RSS feed, for digital players.

RSS aggregator
Software or online service allowing a blogger to read an RSS feed, especially the latest posts on his favourite blogs. Also called a reader, or feedreader.

RSS feed
The file containing a blog’s latest posts. It is read by an RSS aggregator/reader and shows at once when a blog has been updated. It may contain only the title of the post, the title plus the first few lines of a post, or the entire post.

TrackBack
A system that allows a blogger to see who has seen the original post and has written another entry concerning it. The system works by sending a 'ping' between the blogs, and therefore providing the alert.

Troll
A commenter whose sole purpose is to attack the views expressed on a blog, for example, a liberal going to a conservative blog, or vice versa. Many trolls will leave their remarks on multiple posts and continue to visit the blog, sparking spirited debate amongst the blog's regular readers. Trolls' verbosity can range from eloquent to crass, although most trolls probably fall into the latter category.

Ebook

Ebook

An ebook is an electronic (or digital) version of a book. The term is used ambiguously to refer to either an individual work in a digital format, or a hardware device used to read books in digital format. Some users deprecate the second meaning in favour of the more precise "ebook device."

Though e-texts are available as digitally encoded books and the term is often used synonymously with the term ebook, that usage is deprecated. The term e-text is used for the more limited case of data in ASCII text format, while the more general e-book can be in a specialized (and, at times, proprietary) file format. An exception to this rule is the academic e-text, which commonly includes components such as facsimile images, apparatus criticus, and scholarly commentary on the work from one or more editors specially qualified to edit the author or work in question.

An ebook is commonly bundled by a publisher for distribution (as an ebook, an ezine, or a internet newspaper), whereas e-text is distributed in ASCII (or plain text), or in the case of academic works, in the form of discrete media such as compact discs. Metadata relating to the text are sometimes included with etext (though it appears more frequently with ebooks). Metadata commonly include details about author, title, publisher, and copyright date; less common are details regarding language, genre, relevant copyright conventions, etc.

Formats
The ebook community has many options when it comes to choosing a format for production. While the average end user might arguably simply want to read books, every format has its exponents and champions, and debates over "which format is best" can become intense. For the average end user to read a book, every format has its advantages and disadvantages. Formats available include, but are by no means limited to:

Image files
An ebook can be distributed as a sequence of images, one for each page. In this way, any image format can be used as an ebook format. This method of distribution produces files very much larger than all others, and also has the disadvantage that the user cannot select text, nor can the ebook be read by a screen reader. Distribution as images is most suitable for comic books, books about art, or other very visual works.

Rich Text Format
Published as an .rtf
A standard formalized by Microsoft Corporation for specifying formatting of documents. RTF files are actually ASCII files with special commands to indicate formatting information, such as fonts and margins.

Hyper Text Markup Language
Commonly known as HTML
HTML is the markup language used for most web pages. eBooks using HTML can be read using a standard browser (e.g., Mozilla, Firefox, or Microsoft Internet Explorer), with no need for special equipment.

CHM Format
Also known as Microsoft Compressed HTML Help
CHM format is an enhanced version of the HTML format. The main difference is the single file instead a set of files for HTML format.

PostScript
Published as an .ps
PostScript is a page description language used primarily in the electronic and desktop publishing areas for describing the contents of a printed page in a higher level than the actual output bitmap.

Standard Generalized Markup Language
Commonly known as SGML
Standardized metalanguage for the description of markup languages; a set of rules for using whatever markup vocabulary is adopted. This includes the Text Encoding

Initiative (TEI) standard.
eXtensible Markup Language
Published as an .xml
A subset of SGML constituting a particular text markup metalanguage for defining markup languages for the interchange of structured data. The Unicode Standard is the reference character set for XML content. XML is a trademark of the World Wide Web Consortium.

TeX
The TeX format is a popular academic format. TeX is a typesetting system written by Donald Knuth, especially for technical writing applications in the scientific communities of mathematics and computer science. TeX can typeset complex mathematical formulas, but is now also being used for many other typesetting tasks especially in template packages. Few people write in plain TeX any more. LaTeX is a TeX document preparation system. LaTeX offers programmable features and facilities for automating aspects of typesetting and desktop publishing, especially numbering and cross-referencing, tables and figures, page layout, bibliographies. LaTeX was originally written in 1984 by Leslie Lamport and has become a leading method for using TeX (current version: 2ε)

Portable Document Format
Published as a .pdf
A file format created by Adobe Systems, initially to provide a standard form for storing and editing printed publishable documents. Because documents in .pdf format can easily be seen and printed by users on a variety of computer and platform types, they are very common on the World Wide Web.

PDF files are created mainly using Adobe Acrobat, but Acrobat Capture and other Adobe products also support their creation, as do third-party products such as PDFCreator, OpenOffice.org, and FOP. Acrobat Reader (now simply called Adobe Reader) is Adobe's product used to view PDF files. PDF files typically contain product manuals, brochures, magazine articles, or flyers as they can embed fonts, images, and other documents. A PDF file contains one or more page images, each of which you can zoom in on or out from. The PDF format can include interactive elements such as buttons for forms entry and for triggering sound and Quicktime or AVI movies. Acrobat PDF files are optimized for the Web by rendering text before graphic images and hypertext links. Adobe's PDF-like eBook format is incorporated into their reader.

DjVu
Published as .djvu
DjVu is a file format that has been long in obscurity (in other words, since 1996), but that is starting to surface now that free tools to manipulate the files are available.

DjVu is a format that particularly excels in storing scanned images. There are even advanced compressors especially specializing in low-color images, such as text documents. Individual files may contain single pages, or they can be collections of multiple pages.

The images are divided in separate layers (such as multi-color, low-resolution, lossily-compressed background layer, and few-colors, high-resolution, tightly-compressed foreground layer), each compressed in best applicable method. The files are also designed to decompress very fast, even faster than vector-based formats.

The advantage of DjVu is that it is possible to take a high-resolution scan (300-400 DPI), good enough for both on-screen and printing, and store it very efficiently. Several dozens of 300 DPI black-and-white scans can be stored in less than a megabyte.

Microsoft
Published as an .lit
The MS reader uses patented ClearType® display technology. Navigation works with a keyboard, mouse, stylus, or through electronic bookmarks. The Catalogue Library records reader books in a personalized "home page". A user can add annotations and notes to any page, create large-print eBooks with a single command, or create free-form drawings in the reader pages. A built-in dictionary allows the user to look up words.

eReader (formerly Palm Digital Media)
Published as a .pdb
eReader is a program for viewing Palm Digital Media electronic books. Versions are available for PalmOS, PocketPC, Symbian OS, Windows, and Macintosh. The reader shows text one page at a time as paper books do. eReader supports embedded hyperlinks and images. Most eReader formatted books are encrypted, with the key being the purchaser's full name and credit card number.

Mobipocket
Published as a .prc
The Mobipocket Reader has a home page library. Readers can add blank pages in any part of a book and add free-hand drawings. Annotations — highlights, bookmarks, notes, and drawings — can be applied, organized, and recalled from a single location. Mobipocket Reader has electronic bookmarks, appearing in the page margins. Dictionaries allow users to look up definitions through a built-in Lookup function.
The reader has a full screen mode for the reading experience and has Microsoft ClearType® support. On Palm OS, readers can use sub-pixel rendering with the MobiType® font. Mobipocket Reader is the only eBook Reader running on nearly all PDA types (Palm OS, Pocket PC and Windows CE, Tablet PC, Casio BE-300, Psion, Symbian OS Smartphones, Franklin eBookMan) and PCs.

The Mobipocket eBook format based on the Open eBook standard using XHTML can include java-script and frames for a dynamic display, which makes Mobipocket the best solution for professional content such as medical reference eBooks and dictionaries. It also supports native SQL queries to be used with embedded databases.
The Mobipocket encryption system is not a password based system. Its DRM relies on the PDA hardware serial number.

Mobipocket also provides a free eNews service. A reader can subscribe to notable periodicals, or create custom channels. Software on the PC updates the subscriptions and sends them automatically to the PDA.

ExeBook
Published as an .exe
ExeBook is a compiler that produces an ebook file that, when executed, produces a simulated book onscreen, complete with page texture. The etext is encrypted as graphic images so that automatic text copying is very difficult. The fear of exe files picking up viruses, however, is hampering its acceptance.

DesktopAuthor
Published as an .exe and .dnl
DesktopAuthor is an electronic publishing suite that allows creation of digital web books with virtual turning pages. Digital web books of any epublication type can be written in this format, including ebrochures, ebooks, digital photo albums, ecards, digital diaries, online resumes, quizzes, exams, tests, forms and surveys. DesktopAuthor packages the ebook into a ".dnl" or ".exe" book. Each can be a single, plain stand-alone executable file which does not require any other programs to view it. DNL files can be viewed inside a web browser or stand-alone via the DNL Reader.
Comparison with printed books

Advantages
Text can be searched, except when represented in the form of images.
Take up little space.

Hundreds (or thousands) may be carried together on one device.
Approximately 500 average ebooks can be stored on one CD (equivalent to several shelves' worth of print books)

Because they take up little space, eBooks can be offered indefinitely, with no 'out of print' date, allowing authors to continue to earn royalties indefinitely (copyright law permiting), and allowing readers to find older works by favorite readers.

Ebooks may be read in low light or even total darkness, with a back-lit device.
Type size and type face may be adjusted. However, enlarging e.g. a PDF document magnifies the text but preserves the original layout and spacing; a practical limit on zooming follows from the requirement to keep a text column within the width of the screen (otherwise horizontal scrolling would be needed during and after reading each line, which would be very cumbersome). However, tagged PDFs can be reflowed in Acrobat 6 and 7, eliminating the horizontal-scrolling problem in zoomed PDFs. For more on zooming in, see Electronic maps.

Can be used with text-to-speech software.

Readily reformatted for independent platforms.

Instantly copied

When a backup is kept in a remote place, cannot be lost by fire, etc.
Once distributed, elimination is hard to impossible.

Distributed at low cost.

Distributed instantly, allowing readers to begin reading at once, without the need to visit a bookstore

Simultaneously share book (if networked).

Errors may be easily corrected with downloadable lists of errata or simply with corrected text. (This can also be an advantage for printed books, in different circumstances.)

At the moment, ebooks are commonly published by independent publishing houses, which can mean greater editorial and authorial freedom and more room for experimentation.

An inexpensive format for works that require color.

An excellent choice of format for works that benefit from search and cross-reference capabilities, such as dictionaries, reference works, certain kinds of textbooks.

Disadvantages
From the user's point of view:

Can be incompatible with new or replacement hardware or software

Require care in handling and storage of the files, to avoid damage or loss

Reading can be hard on the eyes

Lacks the quality of a print book as an item

From the publisher/author's point of view:
Can in some cases be hacked, or disseminated without approval from the author or publisher (some formats are more susceptible to this than others)

Not normally a good format choice for works that have extensive and/or large illustrations, such as works in art history, photography, large maps, etc.

Print book Advantages
Less eye strain over extended reading time

If small, very portable.

Usable in adverse environmental conditions.

Robust and durable.

Readable when severely damaged.

Requires no power source, and no alternative reading device like a PC or a palmtop.

Errors are "forever"; this unchangeability sometimes adds to its value.

Has more value as "collector's items," e.g., first editions

At the moment, print books are primarily published by established houses including
numerous international conglomerates, which can result in greater funds available for promotion of a title.

Disadvantages
From the user's point of view: Can be priced in a way that inhibits availability

From the user's and author's point of view: Can be put out of print and made unavailable to readers

From the author's point of view: Can be difficult to get a publisher to amend errata
Can be an awkward format for reference works or works that have many internal crossreferences.

An expensive format for works that require color, since color printing commonly requires several passes of paper through the press (one pass per color).

Video On Demand

Video On Demand

VOD systems are systems which allow users to select and watch video content over a network as part of an interactive television system. VOD systems are either "streaming", in which viewing can start as the video streams over the Internet (or other network), or "download", in which the program is brought in its entirety to a set-top box before viewing starts.

All download and some streaming video on demand systems allow the user to pause, fast forward, fast rewind, slow forward, slow rewind, jump to previous/future frame etc. In other words to provide a large subset of VCR functionality. For streaming systems this requires more effort on the part of the server, and may also require greater network bandwidth.

It is possible to put video servers on LANs, in which case they can provide very rapid response to users. Streaming video servers can also serve a wider community via a WAN, in which case the responsiveness may be reduced. Nevertheless, it is possible to provide streaming VOD services over a wide area network. Download VOD services are practical to homes equipped with cable modems or DSL lines.

The first commercial VOD service took place in Hong Kong around 1990. The technology was not mature, Video CDs were much cheaper, and pay TV was not common in Hong Kong. Hong Kong Telecom lost a large amount of money and the service was shut down after it was acquired by Pacific Century Cyberworks in 2000.

VOD services are now available in all parts of the USA. Streaming VOD systems are available from cable providers (similar to cable modem technology) who use the large downstream bandwidth present on cable systems to deliver movies and television shows. Users can typically pause, fast-forward, and rewind VOD movies due to the low latency and random-access nature of cable technology. The large distribution of a single signal makes streaming VOD impractical for most satellite TV systems; however, EchoStar recently announced a plan to offer video on demand programming to PVR-owning subscribers of its DISH Network satellite TV service. The programs are automatically recorded on the PVR, then the users can watch, play, pause, and seek at their convenience. VOD is also quite common in more expensive hotels. Internet download VOD systems are widely available.

It is possible to implement VOD using methods such as bandwidth skimming, which can deliver O(log n) scaling as the number of users increase.

Near Video on Demand
Near Video on Demand (NVOD) is an Pay-per-view consumer video technique used by multi-channel broadcasters using high-bandwidth distribution mechanisms such as satellite and Cable television. Multiple copies of a programme are broadcast at short time intervals (typically 10–20 minutes) providing convenience for viewers, who can watch the programme without needing to tune in at a scheduled point in time.
This form of broadcasting uses large amounts of bandwidth and is only viable for operators with large amounts of spare capacity.

Video on Demand Providers
Download independent and world film here at World Cinema Online
Comcast has a video-on-demand service in the US.
Time Warner Cable has a video-on-demand service in the US.
Cox Communications has deployed video-on-demand service in several of its US locations.

Charter Communications offers a video-on-demand service in most of its US markets.
HomeChoice has a video-on-demand service in the London area of the UK.
Rogers Cable and Shaw Communications have video-on-demand service in Canada.
MovieBeam a video-on-demand service by Disney.
Movielink a video-on-demand service that provides movies for download to desktop and laptop PCs.
CinemaNow a video-on-demand service that provides movies for download to desktop and laptop PCs (including titles in High Defnition 720p/5.1).
NTL in the UK has a Video on Demand service on Digital cable in their Glasgow, Swansea, Cardiff, Luton and Nottingham franchise areas.
Cablevision has IO Digital Cable a video-on-demand service in the US.
TransACT services parts of Canberra (Australia)
Akimbo is a broadband internet based video-on-demand service that delivers standard definition video content to televisions in the US and Canada.
Síminn provides video-on-demand service in Iceland.

Voice over IP (VOIP)

Voice over IP (VOIP)

A typical analog telephone adapter for connecting an ordinary phone to a VoIP network
Voice over Internet Protocol (also called VoIP, IP Telephony, Internet telephony, and Digital Phone) is the routing of voice conversations over the Internet or any other IP based network. The voice data flows over a general-purpose packed-switched network, instead of traditional dedicated, circuit-switched voice transmission lines.
Protocols used to carry voice signals over the IP network are commonly referred to as Voice over IP or VoIP protocols. They may be viewed as commercial realizations of the experimental Network Voice Protocol (1973) invented for the ARPANET.
Voice over IP traffic may be deployed on any IP network, including ones lacking a connection to the rest of the Internet, for instance on a private building-wide LAN.

Advantages
Cost
In general, phone service via VoIP costs less than equivalent service from traditional sources, mainly due to selling below market costs. There are also some cost savings due to using a single network to carry voice and data. This is especially true when users have existing under-utilized network capacity that they can use for VoIP without any additional costs. One must note that the maximum upstream in your Internet connection is the final throttle and service is not as good as standard telco services. VoIP phone calls (even international) are widely regarded as free. While there is a cost for their Internet service, using VoIP over this service usually does not involve any extra charges, so the users view the calls as free. There are a number of services that have sprung up to facilitate this type of "free" VoIP call.

Functionality
VoIP makes easy some things that are difficult to impossible with traditional phone networks:
Incoming phone calls can be automatically routed to your VoIP phone, irrespective of where you are connected to the network. Take your VoIP phone with you on a trip, and anywhere you connect it to the Internet, you can receive your incoming calls.
Call center agents using VoIP phones can work from anywhere with a sufficiently fast Internet connection.

VoIP phones can integrate with other services available over the Internet, including sending and receiving messages or data files in parallel with the voice conversation, audio conferencing, managing address books and passing information about whether others (e.g. friends or colleagues) are available online to interested parties.

Drawbacks
VoIP technology still has a few shortcomings that have led some to believe that it's not ready for widespread deployment. However, most industry analysts have predicted that 2005 is the Year of Inflection, which is the year in which more IP PBX ports will ship than legacy digital PBX ports.

Implementation challenges
Because IP does not provide any mechanism to ensure that data packets are delivered in sequential order, or provide any Quality of Service guarantees, VoIP implementations may face problems dealing with latency, especially if satellite circuits are involved. They are faced with the problem of restructuring streams of received IP packets, which can come in any order and have packets missing, to ensure that the ensuing audio stream maintains a proper time consistency.

Another main challenge is routing VoIP traffic to traverse certain firewalls and NAT. Intermediary devices called Session Border Controllers (SBC) are often used to achieve this, though some proprietary systems such as Skype traverse firewall and NAT without a SBC by using users' computers as super node servers to route other people's calls.

Keeping packet latency acceptable can also be a problem, simply due to transmission distances.

Reliability
Telephones connected directly to telephone company phone lines, which in the event of a power failure are kept functioning by back-up generators or batteries located at the telephone exchange. However, household VoIP hardware uses broadband modems and other equipment powered by household electricity, which may be subject to outages. In order to use VoIP during a power outage, anUPS or a generator must be installed on the premises. It should be noted that many early adopters of VoIP are also users of other phone equipment such as PBX and cordless phone bases that also rely on power not provided by the telephone company.

Some broadband connections may have less than desirable reliability. Where IP packets are lost or delayed at any point in the network between VoIP users, there will be a momentary drop-out of voice. This is more noticeable in highly congested networks and/or where there is long distances and/or interworking between end points.

Emergency calls
The nature of IP makes it difficult to geographically locate network users. Emergency calls, therefore, can not easily be routed to a nearby call center, and are impossible on some VoIP systems. Moreover, in the event that the caller is unable to give an address, emergency services may be unable to locate them in any other way. Following the lead of mobile phone carriers, several VoIP carriers are already implementing a technical work-around. The US government had set a deadline, requiring VoIP carriers to implement eg11, however, the deadline is being appealed by several of leading VoIP companies.

This is a different situation with IPBX systems, where these corporate systems often have full e911 capabilities built into the system.

A simple solution to this problem is to store the local emergency numbers on speed dial which is usually even faster than having to be transfered by the 911 operator.
Integration into global telephone number system

Whilst the traditional Plain Old Telephone System (POTS) and mobile phone networks share a common global standard which allocates and identifies any specific telephone line, there is no widely adopted similar standard for VoIP networks. Some allocate an E.164 number which can be used for VoIP as well as incoming/external calls. However, there are often different, incompatible schemes when calling between VoIP providers which use short codes that are provider specific.

Single point of calling
With commercial services such as Vonage, it is possible to connect the VoIP router into the existing central phone box in the house and have VoIP at every phone already connected. Other services, such as Skype & PeerMe require the use of a computer, so they are limited to single point of calling. Some services, such as BroadVoice provide the ability to connect WiFi SIP phones so that service can be extended throughout the premises, and off-site to any location with an open hotspot..

Mobile phones
Telcos and consumers have invested billions of dollars in mobile phone equipment. In developed countries, mobile phones have achieved nearly complete market penetration, and many people are giving up landlines and using mobiles exclusively. Given this situation, it is not entirely clear whether there would be a significant higher demand for VoIP among consumers until either a) public or community wireless networks have similar geographical coverage to cellular networks (thereby enabling mobile VoIP phones, so called WiFi phones) or b) VoIP is implemented over legacy 3G networks. However, "dual mode" handsets, which allow for the seamless handover between a cellular network and a WiFi network, are expected to help VoIP become more popular.

Adoption
Mass-market telephony
A major development starting in 2004 has been the introduction of mass-market VoIP services over broadband Internet access services, in which subscribers make and receive calls as they would over the PTSN. This requires an analog telephone adapter (ATA) to connect a telephone to the broadband Internet connection. Full phone service VoIP phone companies provide inbound and outbound calling with a DID. Many offer unlimited calling to the U.S., and sometimes to Canada or to selected countries in Europe or Asia, for a flat monthly fee. One advantage of this is the ability to make and receive calls as one would at home, anywhere in the world, at no extra cost. As calls go via IP, this does not incur charges as call diversion does via the PSTN, and the called party does not have to pay for the call.

For example, somebody may call someone on a number with a U.S. area code, but one could be in London, and if someone were to call another number with that area code, it would be treated as a local call, regardless of where that person is in the world. However, the broadband phone is likely to complement, rather than replace a PSTN line, as it still needs a power supply, while calling the U.S. emergency services number 911, may not automatically be routed to the nearest local emergency dispatch center, and would be of no use for subscribers outside the U.S.

Another challenge for these services is the proper handling of outgoing calls from fax machines, TiVo/ReplayTV boxes, satellite television receivers, alarm systems, conventional modems or FAXmodems, and other similar devices that depend on access to a voice-grade telephone line for some or all of their functionality. At present, these types of calls sometimes go through without any problems, but in other cases they will not go through at all. And in some cases, this equipment can be made to work over a VoIP connection if the sending speed can be changed to a lower bits per second rate. If VoIP and cellular substitution becomes very popular, some ancillary equipment makers may be forced to redesign equipment, because it would no longer be possible to assume a conventional voice-grade telephone line would be available in almost all homes in North America and Western-Europe. The TestYourVoIP website offers a free service to test the quality of or diagnose an Internet connection by placing simulated VoIP calls from any Java-enabled Web browser, or from any phone or VoIP device capable of calling the PSTN network.

Corporate and telco use
Although few office environments and even fewer homes use a pure VoIP infrastructure, telecommunications providers routinely use IP telephony, often over a dedicated IP network, to connect switching stations, converting voice signals to IP packets and back. The result is a data-abstracted digital network which the provider can easily upgrade and use for multiple purposes.

Corporate customer telephone support often use IP telephony exclusively to take advantage of the data abstraction. The benefit of using this technology is the need for only one class of circuit connection and better bandwidth use. Companies can acquire their own gateways to eliminate third-party costs, which is worthwhile in some situations.

VoIP is widely employed by carriers, especially for international telephone calls. It is commonly used to route traffic starting and ending at conventional PSTN telephones.

Many telecommunications companies are looking at the IP Multimedia Subsystem which will merge Internet technologies with the mobile world, using a pure VoIP infrastructure. It will enable them to upgrade their existing systems while embracing Internet technologies such as the Web, email, instant messaging, presence, and video conferencing. It will also allow existing VoIP systems to interface with the conventional PSTN and mobile phones.

Electronic Numbering (Enum) uses standard phone numbers (E.164) but allows connections entirely over the Internet. If the other party uses Enum, the only expense is the Internet connection.

Legal
As the popularity of VoIP grows, and PSTN users switch to VoIP in increasing numbers, governments are becoming more interested in regulating VoIP in a manner similar to PSTN services.

In the US, the Federal Communications Commission now requires all VoIP operators who don't support Enhanced 911 to attach a sticker warning that traditional 911 services aren't available. The FCC recently required VoIP operators to support CALEA wiretap functionality. The Telecommunications Act of 2005 proposes adding more traditional PSTN regulations, such as local number portability and universal service fees.