Section 15.6. Deployment Specifications

15.6. Deployment Specifications

Installing software is rarely as easy as dropping a file on a machine; often you have to specify configuration parameters before your software can execute. A deployment specification is a special artifact specifying how another artifact is deployed to a node. It provides information that allows another artifact to run successfully in its environment.

Deployment specifications are drawn as a rectangle with the stereotype <<deployment spec>>. There are two ways to tie a deployment specification to the deployment it describes:

• Draw a dependency arrow from the deployment specification to the artifact, nesting both of these in the target node.

• Attach the deployment specification to the deployment arrow, as shown in Figure 15-19.

The deploy.wsdd file, shown in Figure 15-19, is the standard deployment descriptor file that specifies how a web service is deployed to the Axis web service engine. This file states which class executes the web service and which methods on the class can be called. You can list these properties in the deployment specification using the name : type notation. Figure 15-20 shows the deploy.wsdd deployment specification with the properties className and allowedMethods.

Figure 15-19. Equivalent ways of tying a deployment specification to the deployment it describes

Figure 15-20. Showing the properties of a deployment specification: the notation on the right shows an instance populated with values

The symbol on the right shows an instance of a deployment specification populated with values. Use this notation if you want to show the actual property values instead of just the types.

This chapter has only briefly mentioned instances of elements in deployment diagrams, but you can model instances of nodes, artifacts, and deployment specifications. In deployment diagrams, many modelers don't bother to specify that an element is an instance if the intent is clear. However, if you want to specify property values of a deployment specification (as on the right side of Figure 15-20), then this is a rare situation where a UML tool may force you to use the instance notation.

Currently, many UML tools don't support the deployment specification symbol. If yours is one of them, you can attach a note containing similar information.

You don't need to list every property in a deployment specificationonly properties you consider important to the deployment. For example, deploy.wsdd may contain other properties such as allowed roles, but if you're not using that property or it's insignificant (i.e., it's the same for all your web services), then leave it out.