Loading User Data Source Classes at Runtime

This topic describes the two methods for dynamically load UDS classes and how you can load UDS classes.

You can create your reports using user data source (UDS), user defined objects (UDO), and user defined formulas (UDF). When you publish the reports using UDS, UDO, or UDF to your production environment, Logi Report requires the UDS, UDO, or UDF jars to be in the class path or part of the EAR bundle. You need to shut down your application and wrap the new UDS, UDO, or UDF classes into the WAR or EAR or put them in the class path of the application server. This might be difficult for you. A better way is that you can load the classes at runtime without shutting down your application, for a standalone Logi Report Server, or in your embedded application server calling the Server API.

You need to call two important methods in the Server API to dynamically load your UDS classes:

String jet.server.api.ServerEnv.getDynamicClassDir()
Retrieves the path of the dynamic classes of the report server.
static void jet.server.api.engine.ReportEngineFactory.loadClasses(String path)
Loads the dynamic classes from the location specified by the path parameter.

To load UDS classes, follow the steps:

Specify a folder location on the machine where Logi Report Server runs to hold all the UDS/UDO/UDF jar files, so that you can specify to load the classes from that folder. When Logi Report Server initializes, you can specify the location in one of the following ways (their priority is from highest to lowest):
- Using the Server API static void jet.server.api.http.HttpUtil.initEnv(java.util.Properties props)
  Use the key server.dynamic.class.dir to set the location, for example:
  System.getProperties().put("server.dynamic.class.dir", "C:\\LogiReport\\Server\\dynamic"); HttpUtil.initEnv(System.getProperties());
- Using the option -Dserver.dynamic.class.dir in the server/application startup file
  It will be loaded to system properties. Here is an example:
  -Dserver.dynamic.class.dir=YOUR_FOLDER
- Using the property server.dynamic.class.dir in the server.properties file located in <install_root>\bin
  The default value of this property is <install_root>\dynamicclasses. Here is an example:
  server.dynamic.class.dir=YOUR_FOLDER
Check the dynamic UDS/UDO/UDF folder any time by calling the method static String jet.server.api.ServerEnv.getDynamicClassDir().
Usage of the method:
HttpUtil.getHttpRptServer().getServerEnv().getDynamicClassDir()
Example:
System.out.println("Dynamic path"+httpRptServer.getServerEnv().getDynamicClassDir());
You can get the path's value in your own properties file. You can even copy your UDS/UDO/UDF jar files to the preceding folders programmatically.
Specify to load classes at runtime by calling the method static void jet.server.api.engine.ReportEngineFactory.loadClasses(java.lang.String path). The parameter path is the dynamic class folder.
For example:
ReportEngineFactory.loadClasses(httpRptServer.getServerEnv().getDynamicClassDir());

Technical issues:

Server only loads *.jar or *.zip packages in the specified folder including resource files (recommended *.jar), which excludes the sub directories and unpackaged classes.
If there are duplicated classes having the same package and class name in different *.jar files, the default loading sequence is in time order. Server loads the latest modified file first, and neglects the older ones.
If you split one dynamic UDS classes into different *.jar or *.zip packages and also want to take advantage of dynamic loader, then you should follow the rules:
- The jar with the main class implementing JRUserDataSource class of the dynamic UDS must be in the dynamic class folder.
- The classes in the *.jar or *.zip packages in the dynamic class folder can call or refer the classes under the JVM's class path. However, it cannot work in reverse.
If your UDS classes also go to load the recourse files,
- You should bundle the resource files into a jar no matter whether it is in the same class jar file.
- In addition, the classes (in the *.jar or *.zip ) in the dynamic class folder can get the recourse files both in the dynamic class folder and under the JVM class path. However, the classes under the JVM class path cannot get the resource files in the dynamic class folder.
When you call the API for loading the classes, Logi Report Server does not kill the running catalogs and reports but runs them using the old UDS classes, and freezes new reports until the loading action has finished.
Logi Report Server tries loading dynamic classes in the preceding way. If failed, it will try loading them in the traditional way (using the class path in the Logi Report Server startup file, or EAR/EAR in embedded integration environment). Once it fails to find the classes, it throws ClassNotFoundException.
For the UDO classes, only the creator class and render class can be loaded.

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