S5 – Service States

The S5 Service States View specifies the possible states a service may have, and the possible transitions between those states.

Concerns Addressed

• Detailed Service Specifications.
• Outline requirements for Service behaviour.
• Service implementation guidance.

Background

It is generally considered good practice to make services stateless – i.e. consumers of a service are not aware of what state the service is in. However, in specifying a service, it is often necessary to specify the allowable states so as to constrain how implementations of the service will behave. The S5 View is a specification of those states, and the possible transitions between them.

Usage

• Service behaviour specification.

Representation

• UML.
• Other state transition models.

Detailed View Description

S5 views are usually UML (or similar) state transition models.

Figure 3-20

An S5 view may also specify performance constraints (e.g. the maximum duration a service may be in a particular state):

Figure 3-21

Key Elements and Their Relationships

Figure

Meta-Model

The detailed meta-model and element list for S5, Service States, is at paragraph 4.3.6.