March 2002 — Special Feature

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How SIF Works

SIF Zone Functions

Now that we understand the parts of a SIF Zone - the ZIS, the Agents and the Data Objects - let's take a closer look at how a Zone functions. A SIF Zone uses a "publish and subscribe" model, which is similar to how you get a magazine delivered to your home. Unless you register with the magazine you will not receive it. (We'll leave junk mail out for the moment). Once you have registered with the magazine, sub-scribed in fact, you receive a copy of the magazine whenever it is published.

Agents do the same thing in a SIF Zone. Once a ZIS is set up, each SIF-enabled software application registers with the ZIS so that it can communicate with the SIF Zone. An Application can then act as a provider for and/or a subscriber to various Data Objects. In a basic example, a Student Information System (SIS), might act as the provider of the StudentPersonal Data Object and a Library or Food Service Application would subscribe to events for that object. Since each of these applications is part of the Zone, whenever there is a change to student information in the SIS system, the SIS would publish an Event that is relayed by the ZIS to all subscribers. This lets them know that a change has taken place (see Figure 2: How SIF Works on Pages 4-5).

Because of the way a Zone is configured, all of this notification happens instantly and automatically. As a result, as soon as a new student is added to the school or someone's phone number is updated, that information is automatically transferred to all of the subscribing systems and updated almost instantly. In addition, because of the way the Zone is configured, it is possible to distribute this information to as many systems as are authorized to receive it, eliminating large amounts of data entry.









Elements of a SIF Zone

There are four elements that make up a SIF Zone. The logical grouping of software applications that allow SIF to work are:

Software Application

  • A software program implemented within a school or district.

SIF Data Object

  • Sets of information shared by software applications using the rules of the SIF Specification.
  • The contents of Data Objects are defined by the SIF Specification.
  • Data Objects are shared through SIF messages and written using standard XML notation.

SIF Agent