There are two ways of implementing OSWorkflow: the first is embedding OSWorkflow in your application and the second is using OSWorkflow as a standalone workflow server.
If your needs are just workflow support in one application, then incorporating the OSWorkflow libraries and using the API is sufficient. An example application architecture diagram showing the Business Process Layer that is responsible for tracking the business process in the application is as follows:
The addition of this layer to the standard three adds workflow capabilities to the domain model. This domain model contains the abstract entities of the business domain that travel with the business process. Remember, that each layer can talk only to the layers above and below, so the Business Domain Layer handles Business Process Layer objects. The section entitled Embedding OSWorkflow into your Applications in Chapter 4 will cover this architectural option.