Process Component Model 
In a process component model (SAP ProComp model) a process component is modeled from the provider view:
The model describes which operations and service interfaces process components use to access the data of provider process components and which operations the provider process component uses to access the other process component data.
Model the data using one or multiple Business Objects (BOs). A Business Object belongs to exactly one process component.
To keep the model transparent, always model synchronous operations from left to right and asynchronous operations from top to bottom. The following graphic illustrates this method (to make this simpler, it is assumed that there is only one BO).
General Structure of the Process Component Model
SAP uses interface patterns for synchronous access to BO data. You can select from the following interface patterns:
Manage Business Process Object: Interface pattern for modeling application accesses that do not need to be persisted.
Manage Master Data Object: Interface pattern for modeling access to master data objects.
Query Business Object: Interface pattern to model the search for data records.
Business Object Action: Interface pattern to model the execution of operations on data that is predefined in a business object (BO).
In the graphic this is shown as access using the Sync_In service interface. SAP recommends that customers use the same interface pattern for their own process component models.
More information: Modeling the Interfaces of a Process Component (Provider View)