Unless you've been on holiday at sea for the last year, you've undoubtedly stumbled across the term "Web 2.0" in your Internet travels. As far as buzzwords go, "Web 2.0" is a great one. It captures the idea of a next-generation Internet: Web 2.0 is not just a small improvement; it's big enough to be a full-version change.
Typically, folks point at sites like YouTube, Facebook, MySpace and Twitter as examples of Web 2.0. More than anything else, Web 2.0 seems to be about usergenerated content, communities and collaboration. Sites like YouTube get their content entirely from users; the site itself is merely a platform and has no content or value on its own. The value comes from the people. This is true for social networking sites like Facebook, where user-provided data and user collaboration are the central theme. From this, I think there is a simple litmus test for characterizing Web 2.0. If you were the only user of the application, would it bring you a lot of value? If the answer is a resounding no, there�s a good chance that it's a Web 2.0 app. YouTube, Facebook, MySpace and Twitter all pass this test.
Indeed, the best-known Web 2.0 sites aren't just about user content, they are about users collaborating about user-generated content. YouTube isn't just about uploading pictures; it's about commentaries, ratings, tag clouds and communications among users about that content. Facebook isn't just about personal webpages; it's about sharing information with your friends and comparing your likes and dislikes with others'.
However, something is missing from these sites, something big. If Web 2.0 is all about collaboration and communities, then it is missing the most important form of collaboration within communities: real-time collaboration. Human beings naturally crave real-time interaction - voice, video and instant messaging. Real-time interaction is how people work together when they really need to get something done, discuss an idea, and make a decision..
Imagine, then, how much better Web 2.0 could be if real-time interaction were part of the puzzle. Consider Facebook for a moment. One of its features is the virtual "poke." You poke a friend, who sees your poke, and that's it. What the feature lacks, however, is the natural follow-up that happens in the real world. When you pass someone in the hall and say, "How's it going?" sometimes that person will actually answer, and you have a conversation. Consequently, it would be natural to allow someone to respond to a poke with a voice chat when both users are online and browsing the site at the same time.
Facebook allows its users to define groups, which can have their own discussion lists, officers, photos, videos, news and so on. Often, the discussion lists are a large number of short messages from various members, collectively forming a conversation. More compelling would be if you could see who else was viewing the same group page at that time, and join an ongoing voice chat specific for that group. The chatrooms could allow for real-time text conversations, stored for those viewing the page later.
As for YouTube, imagine a persistent voice and text chatroom associated with each video. With a single click, you could join the rooms associated with the video you were watching and be able to talk about it live with others. It would be even more compelling if users could "share the remote" and be able to rewind, fast-forward and restart the video that the group is seeing. For familyoriented video and picture sites, like Flickr, it would allow a website to replicate the experience of sitting in the living room with your family and flipping through a photo album. That would be truly compelling.
This is where Session Initiation Protocol fits in. By using SIP as another part of the Web 2.0 technology toolkit, these applications can add real-time interaction - with IM, presence, voice, video and real-time text. Furthermore, the large number of existing SIP networks would allow those networks to be integrated with Web 2.0 applications. For example, SIP can help users without VoIP via a simple PSTN outdial from a regular phone. SIP and IM and presence (SIMPLE) interfaces into public IM providers would allow traditional presence to be integrated into these apps as well.
So, even though Web 2.0 is not something that is very well-defined, one thing is clear - Web 2.0 is about communities of users that, together, create a network effect that provides significant value. It's the same formula that makes real-time interaction valuable. Joining the two, by using SIP to bring real-time abilities to Web 2.0 apps, is just natural.
Jonathan Rosenberg is a Cisco Fellow and the co-author of SIP and SIMPLE.
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