Help:SIDs

A Service Interaction Diagram (SID) graphically illustrates workflow amongst two or more services.

It is recommended that you depict workflow within FREMA using this notation.

Example of an SID


How to interpret an SID


 * The top line indicates the Actor(s) who interact with the system. Actors generate requests or events(e.g. "sign on" above), and provide input data (e.g. "Message 1" above).  These in turn trigger behaviour in one or more service descriptions.
 * The top line also specifies the service descriptions which participate and co-operate with each other in this system.
 * The vertical boxes indicate the time period(s) a service description is active; note Take Assessment is active throughout the entire SID, whereas Schedule is active in two smaller bursts.
 * In general, an SID should be read top-down left-to-right; there is an implicit time-line which begins with the very first interaction with the first service description. In this example, it is the sign on interaction between Candidate and the Take Assessment service description.
 * Reading left to right show the chain of interactions amongst co-operating services. In this example, the second interaction is from Take Assessment to Authenticate and Authorise Candidate.
 * Interactions are depicted via two types of arrow
 * request: a full arrow represents invoking a method of another service description
 * response: a broken arrow represents the information returned following a request
 * Note, in the above, there are several interactions which begin and end at Take Assessment. This represents the service description calling an internal method of itself, rather than of another service description.