Accessing Objects in an Independent ASP Using DDM Connections

When a file or data queue object resides in an independent ASP (IASP), a DDM connection can report that the object is in a library that does not exist. This error happens if steps are not taken to ensure that the DDM connection is going to connect to the IASP. With TCP/IP connections, this setup is fairly simple to configure. It is a bit more complicated with SNA or APPC connections, so I break it down into separate discussions.

TCP/IP Connections

The first step is done when an IASP is created. A relational database directory entry for the database name of the IASP is created in the system ASP on the system that the IASP resides on. For example, a system called RMTSYS contains an IASP named MYASP. When I display the relational database directory entries by using the WRKRDBDIRE command, I see one for relational database MYASP with a remote location of LOOPBACK.

I can take advantage of this database name to create a DDM data queue in the system ASP that connects to a data queue in a library in the IASP. For my example, I have a library called IASPLIB in the IASP named MYASP. Within IASPLIB, I create a FIFO (first in, first out) data queue called IASPLIB/IASPDQ. Because my user profile refers to a job description with an initial ASP group of MYASP, I can access this data queue without any problem provided I am using my user profile. Other jobs receive errors that say it cannot find the IASPLIB library (message CPF9810). To correct this problem, I create a DDM data queue in my library, MYSYSLIB (which is in the system ASP), with the following command:

CRTDTAQ DTAQ(MYSYSLIB/SYSASPDQ) TYPE(*DDM) RMTDTAQ(IASPLIB/IASPDQ) RMTLOCNAME(*RDB) +
RDB(MYASP) TEXT('DDM DATA QUEUE TO MYASP OVER LOOPBACK')

Any jobs that run with a job description without MYASP as the initial ASP group can now read and write by using the DDM data queue rather than the actual data queue in the IASP. You can do the same thing on a remote system. The only difference is that you must create the relational database directory entry for the IASP on the remote system.

APPC Connections

APPC connections are a bit more complex because they do not simply refer to the relational database name. There are a number of objects that must be created and modified to make some connections use objects that are in libraries in IASPs. To use the libraries in the IASP, it is necessary to use a job description that has the initial ASP group set to my IASP. To ensure that DDM connections use this job description with APPC connections, we must create a user profile that uses our modified job description. The user profile is used because we have a custom communications entry that specifies that this user profile is used when a specific communications mode description is used. We must create that mode description as well.

Example

Step 1: On the remote system, SYSTEMA, type the following commands to create all of these objects and to modify a subsystem description so that the jobs use our new profile:

CRTDUPOBJ OBJ(QDFTJOBD) FROMLIB(QGPL) OBJTYPE(*JOBD) NEWOBJ(IASPJOBD)

CHGJOBD JOBD(IASPJOBD) INLASPGRP(MYASP)

CRTUSRPRF USRPRF(IASPUSER) PASSWORD(TEMP0RARY) TEXT('User profile for MYASP') JOBD(QGPL/IASPJOBD)

CRTMODD MODD(IASPMOD) MAXSSN(64) MAXCNV(64) LCLCTLSSN(0) DTACPR(*ALLOW) INDTACPR(*LZ10) OUTDTACPR(*LZ10) TEXT('APPC CONNECTIONS TO MYASP IASP')

ADDCMNE SBSD(QCMN) DEV(*ALL) JOBD(QGPL/IASPJOBD) DFTUSR(IASPUSER) MODE(IASPMOD)

Step 2: On the local system, SYSTEMB, we must create the mode description and define the DDM data queue to use it. We connect to the same data queue as in the TCP example, which is the IASPDQ data queue in the IASPLIB. Type the following commands:

CRTMODD MODD(IASPMOD) MAXSSN(64) MAXCNV(64) LCLCTLSSN(0) DTACPR(*ALLOW) INDTACPR(*LZ10) OUTDTACPR(*LZ10) TEXT('APPC CONNECTIONS TO MYASP IASP ON SYSTEMA')

CRTDTAQ DTAQ(MYLIB/APPCIASPDQ) TYPE(*DDM) RMTDTAQ(IASPLIB/IASPDQ) RMTLOCNAME(SYSTEMA) MODE(IASPMOD)

When you read or write to the MYLIB/APPCIASPDQ data queue on SYSTEMB, it makes an APPC connection to SYSTEMA and read and write data to the IASPDQ data queue in the IASPLIB library. This library is not normally accessible to a connection to SYSTEMB because the library is in an ASP other than the system ASP.