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Transaction Routing Events Summary

The DPC application sends a transaction request to a server application by initiating a cooperative flow. The resulting cooperative flow contains the transaction code and NEXTLOCATION. This cooperative flow initiates a series of transaction routing events in the Client Manager, which varies based on whether or not the Directory Services user exit is enabled.

The following represents a summarized sequence of transaction routing events with Directory Services enabled:

1. Upon startup, the Client Manager calls the IEFDP_InitDir() Directory Services user exit function. With the supplied sample user exit, this function reads a file containing a list of trancode-to-server mappings. This file should map each supported transaction code to the host name of the target server expected to service that transaction code.
2. A DPC application sends a transaction request containing the transaction code and, optionally, the NEXTLOCATION by issuing a dialog flow to a server application. (NEXTLOCATION is required to locate the name of the desired target server if the transaction resides on multiple servers).
3. The Client Manager receives the cooperative flow data, extracts the transaction code and NEXTLOCATION value, and passes those values to the IEFDP_SearchDir() Directory Services user exit function.
4. The IEFDP_SearchDir() function implements a user-defined transaction routing scheme. Schemes can include using a binary search routine or using the value of the NEXTLOCATION system attribute to identify the name of the destination target server.
5. The IEFDP_SearchDir() function then returns to the Client Manager either the name of a target server or a NULL value.
   • If Directory Services does not return a NULL value, Client Manager checks its target server configurations. If the desired target server is defined, the request is forwarded to that server.
   • If the IEFDP_SearchDir() function returns a NULL value to the Client Manager, the Client Manager attempts to send the request to the default server. If a default server has not been specified, the Client Manager cannot route the transaction and, as a result, returns an error to the client application.
6. When the Client Manager is shut down, the IEFDP_CleanupDir() Directory Services user exit function is called to allow any necessary cleanup to be performed.

The following represents a summarized sequence of transaction routing events with Directory Services disabled:

1. Client Manager receives the transaction request and attempts to forward the transaction request to the default server.
2. If a default server has not been specified, the Client Manager cannot route the transaction and returns an error to the client application.