Logic parts

User-defined logic parts provide the business logic for your EGL applications. EGL offers two kinds of logic parts:
Generatable logic parts
EGL converts these parts into executable Java™ or COBOL programs. Specify EGL logic by using EGL statements in EGL functions. Generatable part types are classified by their number of entry points and the manner of their invocation:
Program
Program parts have a single entry point and you invoke them by starting, transferring to, or calling the program.
Library
Library parts support sharing functions and variables. Libraries are multiple entry point generatable parts that you access through direct calls to the shared library functions or through direct references to the shared library variables.
Service
Services are shared function libraries whose functions can be invoked locally or across a network (including the Internet). Services conform to Service Oriented Architecture specifications.
Handler
Handlers are multiple entry point programs whose external functions are invoked in response to an event. There are no handlers in the core EGL package; all EGL handlers involve some sort of user interface. See Handler part.
Prototype logic parts
These parts contain no logic of their own. Instead they provide information needed to invoke services, programs, and functions defined elsewhere. Prototype parts include:
Interface
Interface parts provide information needed to invoke a remote service.
ExternalType
ExternalType parts provide information needed to invoke methods associated with Java classes and objects.
Delegate
Delegate parts provide information for invoking an EGL function through a function pointer variable.
Functions
Functions are not parts, but are the major components of generatable logic parts. Functions contain the first executable code in the program (the main() function), or are called from other functions.

In addition to these main categories, there is a special case: standalone functions are not generatable, but are logic parts. EGL maintains standalone functions for compatibility; their use is discouraged in new code. For more, see Standalone Function part.

Most of these parts have unique sets of properties that you can set to control the behavior of the code that you generate from the EGL source.


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