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mq-golang

This repository demonstrates how you can call IBM MQ from applications written in the Go language.

The repository originally also contained programs that exported MQ statistics to monitoring systems. These programs have been moved to a GitHub repository called mq-metric-samples.

A minimum level of MQ V8 is required to build these packages, although it should be possible to connect as a client to even older versions of queue manager.

Health Warning

This package is provided as-is with no guarantees of support or updates. You cannot use IBM formal support channels (Cases/PMRs) for assistance with material in this repository.

There are also no guarantees of compatibility with any future versions of the package; the API is subject to change based on any feedback. Versioned releases are made in this repository to assist with using stable APIs. Future versions will follow semver guidance so that breaking changes will only be done with a new major version number on the module.

See the DEPRECATIONS file for any planned changes to the API.

MQI Description

The ibmmq directory contains a Go package, exposing an MQI-like interface. With a few tiny exceptions noted below, the package implements the full-function MQI. Any application you might have written using the C or COBOL MQI ought to be easily convertible to the Go equivalent.

The intention is to give an API that is more natural for Go programmers than the common procedural MQI. For example, fixed length string arrays from the C API such as MQCHAR48 are represented by the native Go string type. Conversion between these types is handled within the ibmmq package itself, removing the need for Go programmers to know about it.

Sample programs are provided to demonstrate various features of using the MQI. See the README in the samples directory for more information about those programs. Detailed information about the MQI and application design can be found in the MQ product documentation. Although that doesn't mention Go as a language, the principles for all applications apply.

A limited trace capability is available so you can see the MQI verbs being executed. To use this, either set the MQIGO_TRACE environment variable to any non-empty value or call the ibmmq.SetTrace(true) function.

The mqmetric directory contains functions to help monitoring programs access MQ status and statistics. This package is not needed for general application programs.

Using the package

To use code in this repository, you will need to be able to build Go applications. You must also have a copy of MQ installed to build against. The package uses cgo to access the MQI C structures and definitions. It assumes that MQ has been installed in the default location (on a Linux platform this would be /opt/mqm) but this can be changed with environment variables if necessary.

Windows compatibility is also included. Current versions of the Go compiler permit standard Windows paths (eg including spaces) so the CGO directives can point at the normal MQ install path.

Getting started

If you are unfamiliar with Go, the following steps can help create a working environment with source code in a suitable tree. Initial setup tends to be platform-specific, but subsequent steps are independent of the platform.

MQ Client SDK

The MQ Client SDK for C programs is required in order to compile and run Go programs. You may have this from an MQ Client installation image (eg rpm, dep for Linux; msi for Windows).

For Linux x64 and Windows systems, you may also choose to use the MQ Redistributable Client package which is a simple zip/tar file that does not need any privileges to install:

Linux

  • Install the Go runtime and compiler. On Linux, the packaging may vary but a typical directory for the code is /usr/lib/golang.
  • Create a working directory. For example, mkdir $HOME/gowork
  • Install the git client and the gcc C compiler

Windows

  • Install the Go runtime and compiler. On Windows, the common directory is c:\Go
  • Ensure you have a gcc-based compiler. The variant that seems to be recommended for cgo is the tdm-gcc-64 64-bit compiler suite. The default gcc compiler from Cygwin does not work because it tries to build a Cygwin-enabled executable but the MQ libraries do not work in that model; the mingw versions build Windows-native programs.
  • Create a working directory. For example, mkdir c:\Gowork
  • Set an environment variable for the compiler
set CC=x86_64-w64-mingw32-gcc.exe

Common

  • Make sure your PATH includes routes to the Go compiler, the Git client, and the C compiler.

  • Change to the directory you created earlier.

  • Use git to get a copy of the MQ components into a new directory in the workspace.

    git clone [email protected]:ibm-messaging/mq-golang.git src/github.com/ibm-messaging/mq-golang

  • If you have not installed MQ libraries into the default location, then set environment variables for the C compiler to recognise those directories. You may then get messages from the compiler saying that the default MQ directories cannot be found, but those warnings can be ignored. The exact values for these environment variables will vary by platform, but follow the corresponding CFLAGS/LDFLAGS values in mqi.go

For example, on Linux:

   export MQ_INSTALLATION_PATH=/my/mq/dir  # This will also be set from the setmqenv command
   export CGO_CFLAGS="-I$MQ_INSTALLATION_PATH/inc"
   export CGO_LDFLAGS="-L$MQ_INSTALLATION_PATH/lib64 -Wl,-rpath,$MQ_INSTALLATION_PATH/lib64"

Or on Windows:

  set CGO_CFLAGS=-Ic:\IBM-MQC-Redist-Win64\tools\c\include -D_WIN64
  set CGO_LDFLAGS=-L c:\IBM-MQC-Redist-Win64\bin64 -lmqm
  • Sample programs can be compiled directly:
cd src/github.com/ibm-messaging/mq-golang/samples
go build -o /tmp/mqitest mqitest/*.go

At this point, you should have a compiled copy of the program in /tmp. See the samples directory for more sample programs.

Building in a container

The buildSamples.sh script in this directory can also be used to create a container which will install the MQ Client SDK, compile the samples and copy them to a local directory. If you use this approach, you do not need to install a local copy of the compiler and associated tools, though you will still need a copy of the MQ C client runtime libraries for wherever you execute the programs.

Go Modules

The packages in this repository are set up to be used as Go modules. See the go.mod file in the root of the repository.

Support for modules started to be introduced around Go 1.11 and has been firmed up in various modification level updates in each of the compiler levels since then. It is now recommended to use at least version 1.17 of the compiler.

Use of modules means that packages do not need to be independently compiled or installed. Environment variables such as GOROOT and GOPATH that were previously required are now redundant in module mode.

To use the MQ module in your application, your go.mod file contains

  require (
    github.com/ibm-messaging/mq-golang/v5 v5.x.y
  )

and your application code includes

  import ibmmq "github.com/ibm-messaging/mq-golang/v5/ibmmq"

If you have not moved to using modules in your application, you should continue using the older levels of these packages. For example, you can continue to use dep with Gopkg.toml referring to

[[constraint]]
  name = "github.com/ibm-messaging/mq-golang"
  version = "4.1.4"

Those older versions are not maintained, so it is strongly recommended you do move to using modules.

Related Projects

These GitHub-hosted projects are related to or derived from this one. This is not a complete list. Please let me know, via an issue, if you have another project that might be suitable for inclusion here.

Repository Description
ibm-messaging/mq-metric-samples Extracts metrics for use in Prometheus, Influx
JSON consumers etc.
ibm-messaging/mq-golang-jms20 JMS-style messaging interface for Go applications
ibm-messaging/mq-container Building MQ into containers. Uses features from this package
for configuration and monitoring
felix-lessoer/qbeat Extract monitoring and statistics from MQ for use in Elasticsearch
ibm-messaging/mq-mqi-nodejs A similar MQI interface for Node.js applications

Limitations

Package 'ibmmq'

  • All regular MQI verbs are available through the ibmmq package.
  • The only unimplemented area of MQI function is the use of Distribution Lists: they were rarely used, and the Publish/Subscribe operations provide similar capability.
  • Go is not supported for writing MQ Exits, so structures and methods for those features are not included.

Package 'mqmetric'

  • The monitoring data published by the queue manager and exploited in the mqmetric package is not available before MQ V9. A limited set of metrics can be monitored for MQ V8 instances by setting the ConnectionConfig.UsePublications configuration option to false.
  • There was a queue manager limitation which did not permit resource publications to be made about queues whose name includes '/'. This restriction was removed in MQ 9.3. Attempting to monitor such a queue on an older queue manager results in a warning logged by the mqmetric package.

History

See CHANGELOG in this directory.

Issues and Contributions

Feedback on the utility of this package, thoughts about whether it should be changed or extended are welcomed.

For feedback and issues relating specifically to this package, please use the GitHub issue tracker.

Contributions to this package can be accepted under the terms of the Developer's Certificate of Origin, found in the DCO file of this repository. When submitting a pull request, you must include a statement stating you accept the terms in the DCO.

Copyright

© Copyright IBM Corporation 2016, 2023