How They Work:“How Twitter Works, Part III”

In the previous episode, we explored how Twitter bases its application programming interface (API) off the Representational State Transfer (REST) architecture. REST architecture refers to a collection of network design principles that define resources and ways to address and access data. The architecture is a design philosophy, not a set of blueprints, there’s no single prescribed arrangement of computers, servers and cables. For Twitter, a REST architecture in part means that the service works with most Web syndication formats. Web syndication is a pretty simple concept: An application gathers information from one source and sends it out to various destinations. There are a few syndication formats used on the Web. Twitter is compatible with two of them. Really Simple Syndication (RSS) and Atom Syndication Format (Atom). Both formats retrieve data from one resource and send it to another. One potential headache for Twitter is SMS spoofing, a technique that allows someone to post messages from another person’s cell phone number. In the early days of SMS messaging, this was pretty easy to do: Many cell phone service providers allowed people to send messages from an online form to a cell phone. One of the fields in the form was “from,” and people could put anything they wanted in the field. A mischievous person could enter your phone number in the “from” field and send a message to Twitter. Your Twitter page would receive these fake messages as would everyone in your network as if you had legitimately posted them. There aren’t many sites that allow this kind of messaging anymore, but several Web pages specifically designed to spoof SMS messages have appeared. Spoofing can be a big problem on Twitter and other similar systems, though it is controllable, but if that changes, then Twitter may have to look into ways to prevent it in the future. Twitter will also send messages over SMS to cell phones even if you use a desktop or Web-based application to post your Tweet. When you post your message, you tell Twitter to send the message out to all the appropriate outlets through the syndication format. Twitter sends the Tweet out to the cell phones of anyone in your network who has added a cell phone number to his or her Twitter account. For other users, the message may only appear on a Web page or in a computer desktop application. Twitter members in the many countries can interact with the service through their cell phones by sending text messages; for example, in the USA, you can send the message to 40404, where as in Canada, the code is 21212, in the UK use the code +44 7624 801423. Through text messages, you can subscribe to other members’ feeds, turn off feeds, add friends to your network or even delete your account. eddie@afrowebs.com