IMS Connectivity in an On Demand Environment: A Practical Guide to IMS Connectivity

138 IMS Connectivity in an On Demand Environment: A Practical Guide to IMS Connectivity

Figure 9-4 The function of the HWSYDRU0 user exit

The HWSYDRU0 exit is only an example, and when you use it, the following sequence of

events occurs:

1. The prerouting exit (DFSYPRX0) sets up addressability to the parameters that are passed

to the HWSYDRU0 exit.

2. The output member name in the output parameter list is set to blanks.

3. HWSYDRU0 determines the action to take based on whether the name in the input

destination parameter (that is, the destination where the message is to be sent) is an IMS

LTERM or an IMS Connect destination. After HWSYDRU0 makes this determination, it

takes a course of action and sets the contents of register 15 on exit.

9.5.4 Debugging the IMS OTMA exits

When you need to debug an IMS OTMA exit, HWSYPRX0 or HWSYDRU0, keep in mind that

they can be called in a cross-memory environment. In addition, those exits must be reentrant.

write to operator (WTO) can be used to display debug messages, but you have to be careful:

 You must use the LIST-EXECUTE form of WTO, that is, WTO MF=(E,WTOMSG), or you

will find 0C4 abends in the IMS control region.

 You must use LINKAGE=BRANCH if you are running in a cross-memory environment.

Example 9-3 shows how WTOs can be safely issued from an IMS OTMA exit routine.

Example 9-3 Issuing WTOs from an IMS OTMA exit routine

LA R7,WTOMSG

BAL R10,DOWTO

DOWTO DS 0H

L R5,ADDRWORK ADDRESS OF 512-BYTE WORK AREA

LTR R5,R5 IS THERE A WORK AREA?

BZR R10 NO - JUST RETURN

USING WTOD,R5 TELL ASSEMBLER

MVC WTOMSGE,WTOMSGL MOVE MESSAGE MASK

MVC WTOTEXT,0(R7) MOVE MESSAGE TEXT

DFSYPRX0

routes to

OTMA client

ALTPCB ISRT TO CLIENT01

ALTPCB ISRT TO CLIENT02

:

ALTPCB ISRT TO CLIENT09

IMS Application

ALTPCB ISRT TO TPIPE001

ALTPCB ISRT TO TPIPE002

:

ALTPCB ISRT TO TPIPE100

ALTPCB ISRT TO TPIPE900

ALTPCB ISRT TO TPIPE901

:

ALTPCB ISRT TO TPIPE999

HWSYDRU0

specifies

final destination

(Tpipe name)

IMS OTMA

TPIPE NAME : CLIENT01

TPIPE NAME : CLIENT02

TPIPE NAME : CLIENT09

TPIPE NAME : MEMBER0

TPIPE NAME : MEMBER9

Chapter 9. IMS Connect user exit support 139

EPAR R0 PRIMARY ASID

ESAR R1 SECONDARY ASID

CLR R0,R1 PRIMARY = SECONDARY?

BNE DOWTOX NO - IN XM MODE

WTO MF=(E,WTOMSGE) WTO TRACE MESSAGE

BR R10 RETURN TO CALLER

DOWTOX DS 0H

WTO MF=(E,WTOMSGE),LINKAGE=BRANCH

BR R10 RETURN TO CALLER

DROP R5 TELL ASSEMBLER

EJECT

WTOMSGL WTO ‘ ', X

ROUTCDE=(11),DESC=(7),MF=L

WTOD DSECT

WTOMSGE DS 0CL58 REENTRANT WTO MESSAGE

DS CL2 TEXT LENGTH

DS CL2 MCSFLAGS

WTOTEXT DS CL50

DS CL4 ROUTING AND DESCRIPTOR CODES

140 IMS Connectivity in an On Demand Environment: A Practical Guide to IMS Connectivity