The first open-source challenge to the pioneering microblogging site Twitter launched earlier this month. Identi.ca, built using open-source software Laconica, was started by the Montreal-based company Control Yourself. The site is getting attention from microbloggers who hope that Identi.ca will improve upon Twitter, which has been plagued by problems.

The trend of microblogging--which allows users to express themselves in short bursts that are then distributed to a network of friends--is reaching new heights. According to TwitDir, a site that tracks Twitter statistics, more than two million people have accounts with the microblogging service. But in spite of widespread fascination with the hip startup, the company has been struggling even as its popularity peaks, suffering from downtime and trouble accommodating the site's burgeoning population. While many users have stayed loyal to the service, others have investigated alternatives, such as Jaiku, Pownce, and Plurk.

Twitter launched its free service in October 2006, making it possible for people to answer the question "What are you doing?" by sending text messages or instant messages, or posting to the Twitter website. Users could watch the stream of posts on the public timeline, or "follow" specific Twitter users in order to receive their updates. Since then, third-party developers have built a variety of applications, such as Twhirl, that give users even more options for how to interact with the service. In addition to posting updates about the minutiae of daily life, people began using Twitter to communicate with each other at conferences, organize meet-ups, and distribute links to news stories and images.

Evan Prodromou, Identi.ca's founder, says that he came to see Twitter as a form of communication on a level with e-mail, blogging, and podcasting. "I was starting to feel dependent personally on Twitter as a communication medium," he says, "and I realized that's not the way that the Web that we've built works. Having one company be the sole controller of a particular communication medium is kind of difficult. It's not something that is sustainable in the long run for the Web." Prodromou says that he felt people needed an open-source version of the tool.

Identi.ca started out as a stripped-down version of Twitter, with only the most basic capabilities. (Identi.ca, for example, does not yet support posting by text message, although users can post through the Web interface or instant messages.) In the two weeks since Identi.ca's launch, however, the developer community has quickly added several features, including a search function and the ability for users to track updates in response to their own.

Beyond simply replicating features of Twitter, however, Prodromou made a few important changes to how Identi.ca's open-source core, Laconica, is set up. The software is designed so that anyone who wants to host a microblogging site can do so by running Laconica on his own servers. Because of this, Laconica includes features that allow people hosted on different servers to subscribe to each other's posts. To do this, Prodromou wrote OpenMicroBlogging, a suggested standard for use in communication between microblogging services. The standard is based largely on OAuth, an existing standard that allows users to give websites "valet keys" to their personal information, sharing what is needed but keeping the rest protected. Prodromou says that he envisions a federated network of microblogs, able to share data with each other without relying on a single organization's servers to keep the system running.