COBOL applications can be modernized so that they run in the Enterprise Server environment. A modernized COBOL application can be deployed as a service that perform the application's operations.
A service provides access to specific business functionality. A COBOL program implemented as a service reads in a parameter block, processes it and returns a results block.
A service that you create within Enterprise Server can contain one or more operations, depending on the name you give the service and which request handler is associated with it (if any). If you create a service with no request handler associated with it or if the name you use does not contain a valid separator, the service and the operation are one and the same. The Enterprise Server documentation uses the term "simple service" for services of this type. System services such as the Deploy service of the default Enterprise Server instance, ESDEMO are simple services.