# SW Designer container development

A container encapsules a component, i.e. it encloses an existing components and delegates ports to it. The following figure depicts a container enclosing an component. The principal idea is that the container handles the treatment of non-functional properties. Therefore, the existing component can focus on the implementation of the business logic. It is therefore also called executor, a term introduced by the OMG standard CORBA component model (CCM).

There are two different ways how a container can influence the execution of an executor. Either via interception or via extension. The two variants are shown in the sequel.

## How to create a container interceptor

A container interceptor is basically a delegation connector between a port of the container and the executor. Thus, it can be defined in the same way as a connector, but needs to carry the stereotype interceptor.

Further expansion as for a <a href="connector.html">connector</a>

## Container rules

A container rule defines which container extensions and/or interceptors should be applied. The concept of a container rule has been introduced, since some aggregation/interceptor combinations depend on each other. T==heir independ selection would be error prone, instead a single container rule selects the combination.

There are two different kinds of rules:

- local rules that are only visible to a component owning them
- global rules that are visible for all models that import the model library. In both

cases, the container rule is principally a stereotyped UML class. In the first case, it is a sub-class owned by the component, which is typically created by the container rule dialog available for the package. In the second the container rule is a normal class owned by a package; use the SW Designer palette to create the rule. Then, right on the rule to edit its properties.