Release 10.1A: OpenEdge Deployment:
Managing 4GL Applications

> ## Library overview

> OpenEdge provides two types of r-code libraries: standard and memory-mapped. A standard library contains r-code procedures that execute in local memory. A memory-mapped library contains r-code procedures that execute in shared memory.

> When you execute r-code procedures from either a standard library in local memory or a memory-mapped library in shared memory, you gain the following advantages:

> - Faster access to r-code.

> - Fewer file open and close operations.

> - Less I/O to temporary files.

> When you execute r-code procedures from a memory-mapped library in shared memory, you gain the following additional advantages:

> - Even faster access to r-code.

> - Requires less memory because multiple users access the same r-code segments in shared memory.

> When loading and executing r-code procedures from operating system files in a directory, OpenEdge must open and close each file individually. When loading and executing r-code procedures from standard or memory-mapped libraries, OpenEdge opens only one file—the library itself—to access all of the r-code files in the library.

> The r-code files that you place in a library are called members. OpenEdge opens a library the first time you run a member procedure from the library. The library stays open until the end of your Progress 4GL session or until you remove the library from the PROPATH. For more information about how standard and memory-mapped libraries interact with PROPATH during a Progress 4GL session, see the "Libraries and PROPATH" section.

> For information about monitoring and optimizing r-code execution during a client session, see Chapter 1, " Progress 4GL Client Deployment Overview." For more information about r-code structure and execution, see Appendix B "R-code Features and Functions."

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