Limiting Fetching of Business Components Attributes in JClient

Note: Starting in JDeveloper 10g, users who work with the design time tools in JDeveloper will by default obtain the optimization described in this topic.

Use this topic if you develop applications outside of JDeveloper using the provided APIs for ADF Business Components and do not create view object metadata (XML files).

You can optimize startup time for a Business Components client application and the remotely deployed Business Components by specifying the list of view object attributes that your client uses. If you create a project without the metadata, by coding to the API, you will want to add fetchAttributeProperties() to the bootstrap code of the client forms with a list of only the attributes used by the form. Without this method call, your client form would fetch all control hint properties (including the attributes format and label for example) for all the attributes of the named view objects in the application module, in a single network roundtrip.

For example, when you do not intend to use all the attributes of the ADF JClient form's bound view object, with the fetchAttributeProperties() method, your JClient form fetches only the information required to layout your forms, while ignoring the attributes you do not require.

Note: In local mode deployment (the client and Business Components reside in the same VM), the fetching of attribute properties is not supported.

To minimize retrieving of attribute properties (outside of the JDeveloper design time):

Call fetchAttributeProperties() on the ApplicationModule:

The method takes as arguments a list of view object names and a list of attribute names for each view object. The lists may include all or some of the attributes. If your forms require all the attributes of a view object, you may specify null as the attribute argument. In this case, the startup time improvement may not be significant since your form uses all the attributes of the view object anyway.

Note: When you use the JClient Form or Panel wizards to generate complete forms, the fetchAttributeProperties() method is added for you.

You should call fetchAttributeProperties() in the JClient bootstrap code, immediately after the Data Control object is created. In the following example, the custom properties for three attributes of the first view object and five attributes of the second view object are downloaded.


	

	 // bootstrap application

     JUMetaObjectManager.setBaseErrorHandler(new JUErrorHandlerDlg());
     JUMetaObjectManager mgr = JUMetaObjectManager.getJUMom();
     mgr.setJClientDefFactory(null);
     BindingContext ctx = new BindingContext();
     ctx.put(DataControlFactory.APP_PARAM_ENV_INFO, new JUEnvInfoProvider());
     ctx.setLocaleContext(new DefLocaleContext(null));
     HashMap map = new HashMap(4);
     map.put(DataControlFactory.APP_PARAMS_BINDING_CONTEXT, ctx);
     mgr.loadCpx("DataBindings.cpx", map);
     DCDataControl app = (DCDataControl)ctx.get("model_AppModuleDataControl");
              app.setClientApp(DCDataControl.JCLIENT);

       

     app.getApplicationModule().fetchAttributeProperties(new String[]

         {"VO1", "VO2"}, new String[][]

            {

                {"VO1Attr1", "VO1Attr2", "VO1Attr3"},

                    {"VO2Attr1", "VO2Attr2", "VO2Attr3", "VO2Attr4", "VO2Attr5"}

             }, null);

      

      ...

Calling fetchAttributeProperties() will prevent property methods such as getFormat() or getLabel() from being called on the Business Components attribute definition whenever the form is created.