Appendix B. TCP/IP Application Exit Points and ProgramsCertain TCP/IP applications provide exit points that enable them to callcustomer-written exit programs. This appendix contains the following information:v Conceptual information on TCP/IP exit points and programsv General instructions on creating exit programs for TCP/IP applicationsv Descriptions of the TCP/IP application exit point interfacesv Specific instructions on how to prepare exit programs for each TCP/IPapplication exit point, with examples.TCP/IP Exit Points and Exit ProgramsAn exit point is a specific point in the TCP/IP application program where controlmay be passed to an exit program. An exit program is a program to which the exitpoint passes control.For each exit point, there is an associated programming interface, called an exitpoint interface. The exit point uses this interface to pass information between theTCP/IP application and the exit program. Each exit point has a unique name. Eachexit point interface has an exit point format name that defines how information ispassed between the TCP/IP application and the customer-written exit program.Different exit points may share the same exit point interface. When this is the case,multiple exit points can call a single exit program.Figure 62 shows how parameters and control are passed from the TCP/IPapplication program to the customer-written exit program and back again.Figure 62. TCP/IP Exit Point Processing© Copyright IBM Corp. 1997, 2001 79
