Administering Java applications

Use the mqsichangeproperties command to tune the JVM parameters to ensure that there are sufficient resources for all the Java applications that are deployed to the integration server. For more details, see mqsichangeproperties command and JVM parameter values.

Java user-defined nodes are manually installed onto a broker as either a PAR file or a JAR file. Because PAR and JAR files are only loaded by the broker on startup, the broker must be restarted. For more details, see Packaging a Java user-defined node.

A PAR file is given its own Java classloader, ensuring that the node classes are isolated from any other node classes.

For more details, see User-defined node class loading.

A JavaCompute node is deployed to an integration server as part of a BAR file. A JavaCompute node can specify a JavaClassLoader configurable service to be used by the node. A JavaClassLoader configurable service defines the behavior of the classloaders that are used by the node. For more details, see JavaCompute node classloading.

If a JavaCompute node specifies a JavaClassloader configurable service, you must define a configurable service with the name specified by the node on the broker. For more details, see JavaCompute node classloading using a configurable service.

You can identify Java methods to invoke from ESQL routines by using the CREATE FUNCTION statement or the CREATE PROCEDURE statement with a LANGUAGE clause of JAVA. You use the EXTERNAL NAME clause of the statement to specify the fully-qualified class and name of the method. To find the Java class that contains a method, the broker uses the search algorithm that is described in Deploying Java classes. You can optionally specify a JavaClassLoader configurable service when you identify a Java method in this way. The JavaClassLoader configurable service defines the behavior of the classloader that is used to load the class specified in the EXTERNAL NAME clause. If you include a CLASSLOADER clause in a CREATE FUNCTION statement or a CREATE PROCEDURE statement, you must ensure that the corresponding configurable service is defined on the broker. For more details, see JavaClassLoader configurable service.

ESQL Java routines and JavaCompute nodes that specify the same JavaClassLoader configurable service share one instance of the classloader. Therefore, the nodes and the routines use the same in-memory version of Java classes, and have access to the same static variables. The classloading mechanism for ESQL routines is the same as for JavaCompute nodes; for more details, see JavaCompute node classloading using a configurable service.