Building amqsdlq sample Dead Letter Handler.

MQ provides a sample Dead Letter Queue Handler in /opt/mqm/samp/dlq/ (on Ubuntu). It looks and behaves just like runmqdlq. I think trying to extend it, for example to filter on MSGID or CORRELID would be difficult, and it would be easier to write a small program just to process one message with input queue, and pass filter parameters.

Build it

There are no instructions in the IBM documentation on how to build this. I used the following

  • create a directory to contain the code, for example mkdir ~/dlq
  • go to this directory cd ~/dlq
  • copy the code from MQ cp -r /opt/mqm/samp/dlq/* .
  • make the directory rw chmod +w ~/dlq
  • install a yacc compiler sudo apt install byacc
  • issue the make command make all -f amqodqx.mk

If you get

gcc -m64 -I. -I/opt/mqm/inc -c -o amqodqka.o amqodqka.c
Assembler messages:
Fatal error: can’t create amqodqka.o: Permission denied

Your directory is not read/write. Use the chmod command.

If you get

yacc amqodqma.y
make: yacc: Command not found

You need to install a yacc compiler. I used sudo apt install byacc .

I dont undestand why I got this message, because the build for the yacc files is commented out. It may be there is a default make for yacc.

The YACC ( compiler generator) produces a c file. If you are not changing the keywords, you could rename the .y and .l files, so they are not used, and so use the shipped c files. In this case you will not need the yacc compiler.

Run it

  • export ODQ_MSG=amqsdlq.msg This is needed for the message catalog
  • ./amqsdlq SYSTEM.PROTECTION.ERROR.QUEUE QMA < /home/colinpaice/mqams/dlq.rul
    • for a while it failed with a syntax error in line 1 of the file, I rebuilt it, then suddenly it worked.
    • Ctrl-c ended it
  • ./amqsdlq ? gave me a segmentation core dump

I changed the make file to build a client

cc -m64 -o amqsdlqc… -lmqic_r

You should ensure you use a TLS channel if you do run this as a client.

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