Module Coverage

Each module should cover a particular scope of an application, preferably without replicating the functionality available in another module. In addition, a module should be appropriately sized; if the module can be sensibly broken into sub components, then smaller modules should be created instead of one large monolithic module.

For example: A designer may decide to write a module to provide security services to a target server installation. As part of this module, the designer decides to install a firewall and a set of hardening scripts.

In this case, the designer should investigate whether another module already covers either of these two areas and could be leveraged. In addition, if either the firewall or hardening scripts may be used elsewhere in isolation from each other, it may be more flexible to create them as two modules rather than bundling them together.