Configuring the Java Native Interface (JNI) libraries

IBM® WebSphere® MQ classes for JMS applications, that either connect to a queue manager using the bindings transport, or that connect to a queue manager using the client transport, and use the channel exit programs written in languages other than Java, need to be run in an environment that accesses the Java Native Interface (JNI) libraries.

About this task

To set up this environment, you must configure the environment's library path so that the Java virtual machine (JVM) can load the mqjbnd library before you start the IBM WebSphere MQ classes for JMS application.

IBM WebSphere MQ provides two Java Native Interface (JNI) libraries:

mqjbnd: This library is used by applications that connect to a queue manager using the bindings transport. It provides the interface between the IBM WebSphere MQ classes for JMS and the queue manager. The mqjbnd library installed with IBM WebSphere MQ Version 7.5 can be used to connect to any IBM WebSphere MQ Version 7.5 (or earlier) queue manager.
mqjexitstub02: The mqjexitstub02 library is loaded by the IBM WebSphere MQ classes for JMS when an application connects to a queue manager using the client transport and uses a channel exit program written in a language other than Java.

On certain platforms, IBM WebSphere MQ installs 32-bit and 64-bit versions of these JNI libraries. The location of the libraries for each platform is shown in Table 1

Table 1. The location of the IBM WebSphere MQ classes for JMS libraries for each platform
Platform	Directory containing the IBM WebSphere MQ classes for JMS libraries
AIX®	`MQ_INSTALLATION_PATH`/java/lib (32 bit libraries) `MQ_INSTALLATION_PATH`/java/lib64 (64 bit libraries)
HP-UX	`MQ_INSTALLATION_PATH`/java/lib (32 bit libraries) `MQ_INSTALLATION_PATH`/java/lib64 (64 bit libraries)
Linux (POWER® , x86-64 and zSeries s390x platforms)	`MQ_INSTALLATION_PATH`/java/lib (32 bit libraries) `MQ_INSTALLATION_PATH`/java/lib64 (64 bit libraries)
Linux (x86 platform) Linux ( zSeries platform)	`MQ_INSTALLATION_PATH` /java/lib
Solaris (x86-64 and SPARC platforms)	`MQ_INSTALLATION_PATH`/java/lib (32 bit libraries) `MQ_INSTALLATION_PATH`/java/lib64 (64 bit libraries)
Windows	`MQ_INSTALLATION_PATH`\java\lib (32 bit libraries) `MQ_INSTALLATION_PATH`\java\lib64 (64 bit libraries)
`MQ_INSTALLATION_PATH` represents the high-level directory in which IBM WebSphere MQ is installed.

Procedure

Configure the JVM's java.library.path property, which can be done in two ways:

By specifying the JVM argument as shown in the following example:
```
-Djava.library.path=<path_to_library_directory>
```
For example, for a 64-bit JVM on Linux® for a default location installation, specify:
```
-Djava.library.path=/opt/mqm/java/lib64
```
By configuring the shell's environment such that the JVM will set up its own java.library.path. This path varies by platform and by the location in which you installed IBM WebSphere MQ. For example, for a 64-bit JVM and a default IBM WebSphere MQ installation location, you can use the following settings:
```
export LIBPATH=/usr/mqm/java/lib64:$LIBPATH
```
```
export LD_LIBRARY_PATH=/opt/mqm/java/lib64:$LD_LIBRARY_PATH
```
```
set PATH=C:\Program Files\IBM\MQ\java\lib64;%PATH%
```

An example of the exception stack that you see when the environment has not been configured correctly is as follows:

Caused by: com.ibm.mq.jmqi.local.LocalMQ$4: CC=2;RC=2495;
AMQ8598: Failed to load the WebSphere MQ native JNI library: 'mqjbnd'.
    at com.ibm.mq.jmqi.local.LocalMQ.loadLib(LocalMQ.java:1268)
    at com.ibm.mq.jmqi.local.LocalMQ$1.run(LocalMQ.java:309)
    at java.security.AccessController.doPrivileged(AccessController.java:400)
    at com.ibm.mq.jmqi.local.LocalMQ.initialise_inner(LocalMQ.java:259)
    at com.ibm.mq.jmqi.local.LocalMQ.initialise(LocalMQ.java:221)
    at com.ibm.mq.jmqi.local.LocalMQ.<init>(LocalMQ.java:1350)
    at com.ibm.mq.jmqi.local.LocalServer.<init>(LocalServer.java:230)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:86)       
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:58)       
    at java.lang.reflect.Constructor.newInstance(Constructor.java:542)
    at com.ibm.mq.jmqi.JmqiEnvironment.getInstance(JmqiEnvironment.java:706)
    at com.ibm.mq.jmqi.JmqiEnvironment.getMQI(JmqiEnvironment.java:640)
    at com.ibm.msg.client.wmq.factories.WMQConnectionFactory.createV7ProviderConnection(WMQConnectionFactory.java:8437)       
    ... 7 more
Caused by: java.lang.UnsatisfiedLinkError: mqjbnd (Not found in java.library.path)
    at java.lang.ClassLoader.loadLibraryWithPath(ClassLoader.java:1235)
    at java.lang.ClassLoader.loadLibraryWithClassLoader(ClassLoader.java:1205)
    at java.lang.System.loadLibrary(System.java:534)
    at com.ibm.mq.jmqi.local.LocalMQ.loadLib(LocalMQ.java:1240)
    ... 20 more

After either the 32-bit or 64-bit environment has been set up, start the IBM WebSphere MQ classes for JMS application using the command:
```
java application-name
```
where application-name is the name of the IBM WebSphere MQ classes for JMS application to be run.
An exception containing IBM WebSphere MQ Reason Code 2495 (MQRC_MODULE_NOT_FOUND) is thrown by the IBM WebSphere MQ classes for JMS if:
- The IBM WebSphere MQ classes for JMS application is run in a 32-bit Java runtime environment, and a 64-bit environment has been set up for the IBM WebSphere MQ classes for JMS, as the 32-bit Java runtime environment is unable to load the 64-bit Java Native Library.
- The IBM WebSphere MQ classes for JMS application is run in a 64-bit Java runtime environment, and a 32-bit environment has been set up for the IBM WebSphere MQ classes for JMS, as the 64-bit Java runtime environment is unable to load the 32-bit Java Native Library.