|
|
|
|
|
|
Defining the Plug-In Session EJB
This section explains how to define the plug-in session EJB. It includes the following topics:
Overview
To define the plug-in session EJB, you must implement the three predefined interfaces described in the following table.
The following sections describe each interface and the methods that you must implement when defining the plug-in session EJB. Excerpts from the plug-in sample are included.
Session EJB Interface
By definition, a session EJB must implement the javax.ejb.SessionBean and its methods.
Note: The contents of the SessionBean interface methods may be empty, or they may simply return a message to the log; but they must be implemented.
The following table lists the session EJB methods that you must implement.
For more information about these methods, see the javax.ejb.SessionBean Javadoc. The following code listing is an excerpt from the plug-in sample that shows how to implement the javax.ejb.SessionBean interface and its methods. This excerpt is taken from the SamplePluginBean.java file in the WLI_HOME/samples/bpm_api/plugin/src/com/bea/wlpi/tour/po/plugin directory. Notable lines of code are shown in bold. Listing 3-1 Implementing the Session EJB Interface For more information about the plug-in sample, see BPM Plug-In Sample.
package com.bea.wlpi.tour.po.plugin;
import com.bea.wlpi.common.VersionInfo;
import com.bea.wlpi.common.plugin.*;
import com.bea.wlpi.common.plugin.PluginData;
import com.bea.wlpi.server.plugin.InstanceNotification;
import com.bea.wlpi.server.plugin.Plugin;
import com.bea.wlpi.server.plugin.PluginManagerCfg;
import com.bea.wlpi.server.plugin.PluginManagerCfgHome;
import com.bea.wlpi.server.plugin.TaskNotification;
import com.bea.wlpi.server.plugin.TemplateDefinitionNotification;
import com.bea.wlpi.server.plugin.TemplateNotification;
import java.lang.reflect.Constructor;
import java.util.MissingResourceException;
import java.util.ResourceBundle;
import java.util.Locale;
import java.net.URL;
import javax.ejb.CreateException;
import javax.ejb.SessionBean;
import javax.ejb.SessionContext;
import javax.naming.InitialContext;
import javax.rmi.PortableRemoteObject;
import java.io.*
/**
* @homeInterface com.bea.wlpi.server.plugin.PluginHome
* @remoteInterface com.bea.testplugin.SamplePlugin
* @statemode Stateless
*/
public class SamplePluginBean implements SessionBean {
private SessionContext ctx;
private final static String PLUGIN_MANAGER_CFG_HOME =
"java:comp/env/ejb/PluginManagerCfg";
private static byte[] ICON_BYTE_ARRAY;
// implements javax.ejb.SessionBean
public void ejbActivate() {
} // implements javax.ejb.SessionBean
public void ejbRemove() {
}
// implements javax.ejb.SessionBean
public void ejbPassivate() {
}
// implements javax.ejb.SessionBean
public void setSessionContext(SessionContext ctx) {
this.ctx = ctx;
}
.
.
.
Plug-In Home Interface
The home interface has been defined for you by the BPM plug-in framework. The com.bea.wlpi.server.plugin.PluginHome interface extends the javax.ejb.EJBHome interface and defines the home interface for all plug-ins.
The following table describes the method defined by the PluginHome home interface.
For more information about the home interface, see the com.bea.wlpi.server.plugin.PluginHome Javadoc. The following code listing is an excerpt from the plug-in sample that shows how to implement ejbCreate() method for the single create() method that is declared in the home interface, and define a custom plug-in icon for the Studio interface view. This excerpt is taken from the SamplePluginBean.java file in the WLI_HOME/samples/bpm_api/plugin/src/com/bea/wlpi/tour/po/plugin directory. Listing 3-2 Implementing the Home Interface Method For more information about the plug-in sample, see BPM Plug-In Sample.
// implements javax.ejb.SessionBean
public void ejbCreate() throws CreateException {
try {
ICON_BYTE_ARRAY = InfoObject.imageStreamToByteArray(
getClass().getResourceAsStream("Sample.gif"));
} catch (IOException ioe) {
ioe.printStackTrace();
}
}
Plug-In Remote Interface
The remote interface is defined for you by the BPM plug-in framework. The com.bea.wlpi.server.plugin.Plugin interface extends the javax.ejb.EJBObject interface and defines the remote interface for all plug-ins.
When defining the plug-in session EJB, you must implement the Plugin remote interface, including its methods.
The Plugin remote interface defines methods in the following categories:
The following sections describe, by category, the Plugin remote interface methods that you must implement.
Note: The contents of the remote interface methods may remain empty, or they may simply return a message to the log; but they must be implemented.
Lifecycle Management Methods
The following table defines the lifecycle management methods that are defined by the remote interface that you must implement. For more information about the BPM plug-in lifecycle, see Managing Lifecycle Tasks.
For more information about the methods of managing the remote interface lifecycle, see the com.bea.wlpi.server.plugin.Plugin Javadoc. Notification Methods The following table defines the notification methods that are defined by the remote interface that you must implement. Note: In order to receive notifications, the plug-in must register as a notification listener. For more information, see Using Plug-In Notifications.
For more information about remote interface notification methods, see the com.bea.wlpi.server.plugin.Plugin Javadoc. Plug-In Information Methods The following table defines the plug-in information methods that are defined by the remote interface that you must implement.
For more information about remote interface plug-in information methods, see the com.bea.wlpi.server.plugin.Plugin Javadoc. Object Manufacturing Method The following table defines the object manufacturing method that are defined by the remote interface that you must implement.
For more information about remote interface object manufacturing method, see the com.bea.wlpi.server.plugin.Plugin Javadoc. Example of Implementing the Remote Interface The following code listing is an excerpt from the plug-in sample that shows how to implement the remote interface and its methods. This excerpt is taken from the SamplePluginBean.java file in the WLI_HOME/samples/bpm_api/plugin/src/com/bea/wlpi/tour/po/plugin directory. Notable lines of code are shown in bold. Listing 3-3 Implementing the Remote Interface For more information about the plug-in sample, see BPM Plug-In Sample.
Copyright © 2002 BEA Systems, Inc. All rights reserved.
// Plugin implementation
/**
* Initialize the Plugin.
*/
public void init() {
log("init called");
}
/**
* Deinitialize the Plugin.
*/
public void exit() {
log("exit called");
}
/**
* Load the Plugin. The plugin should register its
* interest in various system events at this point.
* @param pluginData Plugin configuration data.
* @see PluginManager#addTemplateListener
* @see PluginManager#addTemplateDefinitionListener
* @see PluginManager#addInstanceListener
* @see PluginManager#addTaskListener
* @throws PluginException
*/
public void load(PluginObject pluginData) throws PluginException {
log("load called");
// Enable this block to subscribe to notifications.
/*
PluginManagerCfg pm = null;
try {
pm = getPluginManagerCfg();
Plugin plugin = (Plugin)ctx.getEJBObject();
pm.addInstanceListener(plugin, PluginConstants.EVENT_NOTIFICATION_ALL);
pm.addTaskListener(plugin, PluginConstants.EVENT_NOTIFICATION_ALL);
pm.addTemplateDefinitionListener(plugin, PluginConstants.EVENT_NOTIFICATION_ALL);
pm.addTemplateListener(plugin, PluginConstants.EVENT_NOTIFICATION_ALL);
} catch (Exception e) {
e.printStackTrace();
throw new PluginException(SamplePluginConstants.PLUGIN_NAME, "Unable to get PluginManager");
} finally {
try {
if (pm != null)
pm.remove();
} catch (Exception e) {
}
}
*/
log("loaded");
}
/**
* Unload the plugin. The plugin framework will deregister the plugin
* if it had subscribed to any event notifications.
*/
public void unload() {
log("unload called");
}
public PluginDependency[] getDependencies() {
log("getDependencies called");
return null;
}
public String getName() {
return SamplePluginConstants.PLUGIN_NAME;
}
public VersionInfo getVersion() {
return SamplePluginConstants.PLUGIN_VERSION;
}
/**
* Return descriptive information about the plugin
* @param lc The locale in which to localize display strings.
* @return Descriptive information about the Plugin.
*/
public PluginInfo getPluginInfo(Locale lc) {
log("getPluginInfo called");
return createPluginInfo(lc);
}
public void setConfiguration(PluginObject config) throws PluginException {
}
/**
* Return a complete description of the plugins capabilities. To add new
* subcategories and actions, the plugin should use the category IDs
* passed in via the <code>info</code> parameter passed to identify the
* parent categories, and {@link ActionCategoryInfo#ID_PLUGIN} as the new category ID.
* The PluginManager merges the CategoryInfo array returned by this call with
* the current structure (as passed via the <code>info</code> parameter), and
* replaces references to {@link ActionCategoryInfo#ID_PLUGIN} with ne
private PluginInfo createPluginInfo(Locale lc) {
HelpSetInfo helpSet;
PluginInfo pi;
SampleBundle bundle = new SampleBundle(lc);
String name = bundle.getString("pluginName");
String desc = bundle.getString("pluginDesc");
String helpName = bundle.getString("helpName");
String helpDesc = bundle.getString("helpDesc");
helpSet = new HelpSetInfo(SamplePluginConstants.PLUGIN_NAME, helpName,
helpDesc,
new String[]{ "htmlhelp/Sample", "index" },
HelpSetInfo.HELP_HTML);
pi = new PluginInfo(SamplePluginConstants.PLUGIN_NAME, name, desc, lc,
SamplePluginConstants.VENDOR_NAME,
SamplePluginConstants.VENDOR_URL,
SamplePluginConstants.PLUGIN_VERSION,
SamplePluginConstants.PLUGIN_FRAMEWORK_VERSION,
null, null, helpSet);
return pi;
}
// It is necessary to create these objects afresh each time, because we
// relinquish ownership of the result and the plugin framework assigns
// a system ID to each item. Reassignment will cause an
// IllegalStateException.
private CategoryInfo[] getCategoryInfo(SampleBundle bundle) {
ActionInfo checkInventoryAction =
new ActionInfo(SamplePluginConstants.PLUGIN_NAME, 1,
bundle.getString("checkInventoryName"),
bundle.getString("checkInventoryDesc"), ICON_BYTE_ARRAY,
ActionCategoryInfo.ID_NEW,
ActionInfo.ACTION_STATE_ALL,
SamplePluginConstants.CHECKINV_CLASSES);
ActionInfo sendConfirmAction =
new ActionInfo(SamplePluginConstants.PLUGIN_NAME, 2,
bundle.getString("sendConfirmName"),
bundle.getString("sendConfirmDesc"), ICON_BYTE_ARRAY,
ActionCategoryInfo.ID_NEW,
ActionInfo.ACTION_STATE_ALL,
SamplePluginConstants.SENDCONF_CLASSES);
ActionCategoryInfo[] actions =
new ActionCategoryInfo[]{ checkInventoryAction, sendConfirmAction };
CategoryInfo[] catInfo =
new CategoryInfo[]{ new CategoryInfo(SamplePluginConstants.PLUGIN_NAME,
0, bundle.getString("catName"),
bundle.getString("catDesc"),
ActionCategoryInfo.ID_NEW,
actions) };
return catInfo;
}
private void log(String msg) {
System.out.println("SamplePlugin: " + msg);
}
Required browser: Netscape 4.0 or higher, or Microsoft Internet Explorer 4.0 or higher.