Evan Prodromou 20 Nov 2008


Microblogging sites like Twitter, Jaiku, Pownce and Yammer are a popular communication mechanism for experienced social media users. Major sites, however, are community silos, and users of one site cannot interact or have social links with users of another site. I describe an open, HTTP-based protocol for sharing microblogging messages across security domain boundaries. This protocol is in use on the popular Web site, the many sites that use its Open Source software, and at least one other Open Source implementation. OpenMicroBlogging may provide a valuable model for inter-site sociality in other application domains.


Microblogging is a popular Web application sector that lets users share brief (usually <1000 character) messages with people in their social network over multiple communications channels: Web, feeds, instant messaging (IM), mobile text messaging (e.g. SMS), and dedicated desktop and/or mobile clients.

The genre was popularized by San-Francisco-based Twitter, expanded by Google-owned Jaiku and independent Pownce. During the summer of 2008, as market-leader Twitter suffered performance problems, several new services started, hoping to stake a claim in the market. Most successful were Plurk, Rejaw, Kwippy, Yammer, and

Market outlook

The winner-take-all expectations of Web startups are rarely, if ever, fulfilled. Since Twitter recovered from the worst of its performance problems, some pundits have pronounced the death of other microblogging sites, to the exclusive favor of Twitter. The network effect is a powerful force that keeps users attached to social networking services with large populations; with an estimated 5 million users Twitter overshadows all other competitors.

However, it's rare in Web technologies that an application sector with many many competitors will collapse to a monopoly. It may be more realistic to compare the current state of the microblogging market to the social network domain in 2003-4.

As early leader stumbled in performance, tiny upstarts like Facebook and MySpace began to grab the attention of disgruntled users. The cohesive nature of the early leader gave way to today's one to two dozen major social networks, none of which allow intercommunication or shared sociality.

The federation model

A more positive model may be found in the email systems of the early 1990s. Commercial messaging systems of the time rarely extended beyond organizational boundaries, and consumer services like AOL, Genie, Prodigy and CompuServe saw competitive advantage in preventing their users from interacting with users of other services. This balkanized system collapsed as users began to appreciate the advantage of internetworked electronic mail, based on the simple (perhaps even simplistic) SMTP transport. Few, if any, messaging silos remained by the end of the decade.

The federated model used by SMTP email and XMPP for instant messaging provides a reasonable network architecture for interoperable microblogging services. Users of one service may use proprietary or ad hoc standards to interact with the service itself, but service-to-service communication should be governed by simple, extensible protocols. Universal addressing of user accounts and use of the DNS system for namespacing and identity portability are additional patterns worth translating into the microblogging world.


OpenMicroBlogging (OMB) is an ad hoc standard developed for the microblogging platform. The site's Open Source software can be downloaded and installed on practically any hosting service that supports PHP 5 and MySQL. To make this code-sharing meaningful and useful, the author developed the OMB standard to allow software installations to interoperate. Since the launch of, at least one other implementation,, has been released.

The base functionality for OpenMicroBlogging is cross-site subscription. Here, a user Alice of one microblogging site,, authorizes another microblogging service,, to send notices posted by a user she is interested in, Bob, to her microblogging 'inbox'. The authorization process uses the OAuth protocol and OAuth Discovery draft protocol to assure Alice's service that she indeed approves of this subscription.

After subscription, Bob's service,, uses simple predefined HTTP POST messages to to push notices to Alice's inbox. If Bob's user profile or other personal information are updated, it may also push profile data to Alice's service.

Each OMB account has an alphanumeric nickname scoped by the domain name of the OMB server. Accounts are uniquely identified by URIs; for Laconica, these are unchangeable URLs of users' home pages, but the protocol remains open for other non-URL URI formats.

In its 0.1 version, OMB is in use on the network of installed Laconica instances, totalling somewhere around 50-100 servers producing 10-20K notices per day. Future versions of the protocol will address direct 'private' messaging between services; passing rendered HTML instead of plain text; better authentication of partner services; and optional, unauthorized 'reply' notices.

Future developments

Our intention is to begin a community marketing push in 2009 to get further commitments to the OpenMicroBlogging standard from both Open Source and proprietary developers and service providers. Already, new projects for implementing in projects such as Drupal are being considered. Proprietary service providers may see an open microblogging network as a significant aid to competing with a market leader found in

It may also be possible to extend the simple subscription-and-push model of OpenMicroBlogging to other social networking software to provide similar distributed functionality. Using the profile URL of a user as a universal addressing mechanism should be translatable to many photo-sharing, social networking, social bookmarking, and other Web arenas.

We anticipate that Open Source software will continue to lead the way on federated models of sociality on the Web. The nature of Open Source software lends itself to many small, isolated implementations; network effect advantages only accrue when installations interoperate.