Invoke EJB Action
Hi there,
I had the problem, that I should invoke several SLSB operations located on another JBoss AS instance. For this purpose I wrote several actions doing all the jndi lookup stuff and so on...
Now I coded an action that is configured via jboss-esb.xml that uses reflection to do all the stuff for me and I only have one custom action that invokes any SLSB.
I thought maybe someone finds this helpful, so here is the code:
public class EJBProcessor extends AbstractActionLifecycle {
private static final Logger log = Logger.getLogger(EJBProcessor.class);
public static final String EJB_NAME = "ejb-name";
public static final String JNDI_NAME = "jndi-name";
public static final String EJB_METHOD = "method";
public static final String JAVA_TYPE = "type";
public static final String INICTXFACTORY = "initial-context-factory";
public static final String PROVIDERURL = "provider-url";
public static final String OUT_VAR = "esb-out-var";
public static final String DEFAULT_OUT = "DEFAULT_EJB_OUT";
public static final int ARG_PREFIX_LENGTH = 3;
protected ConfigTree configTree;
private Map<String, String> ejbRef;
private Map<Integer, Argument> ejbParams;
private List<String> ejbParamTypeNames;
public EJBProcessor(ConfigTree config) {
configTree = config;
}
public Message process(Message msg) throws ActionProcessingException, ConfigurationException {
ejbRef = new HashMap<String, String>();
ejbParams = new HashMap<Integer, Argument>();
ejbParamTypeNames = new ArrayList<String>();
// Get the configuration from jboss-esb.xml
ejbRef.put(EJB_NAME, configTree.getAttribute(EJB_NAME));
ejbRef.put(JNDI_NAME, configTree.getAttribute(JNDI_NAME));
ejbRef.put(EJB_METHOD, configTree.getAttribute(EJB_METHOD));
ejbRef.put(INICTXFACTORY, configTree.getAttribute(INICTXFACTORY));
ejbRef.put(PROVIDERURL, configTree.getAttribute(PROVIDERURL));
if (configTree.getAttribute(OUT_VAR) != null) {
ejbRef.put(OUT_VAR, configTree.getAttribute(OUT_VAR));
} else {
ejbRef.put(OUT_VAR, DEFAULT_OUT);
}
// Get all parameters for the EJB method, defined in jboss-esb.xml
ConfigTree[] subElements = configTree.getAllChildren();
for (ConfigTree child : subElements) {
Integer argNum;
String jType;
String esbLocation;
argNum = Integer.parseInt(child.getName().substring(ARG_PREFIX_LENGTH));
jType = child.getAttribute(JAVA_TYPE);
esbLocation = child.getWholeText();
ejbParams.put(argNum, new Argument(jType, esbLocation));
ejbParamTypeNames.add(jType);
}
// Check for missing configuration values
for (String conf : ejbRef.values()) {
if (conf == null) {
throw new ConfigurationException("Error configuring EJBProcessor");
}
}
// Build Properties for InitialContext lookup
Properties props = new Properties();
props.put(Context.INITIAL_CONTEXT_FACTORY, ejbRef.get(INICTXFACTORY));
props.put(Context.PROVIDER_URL, ejbRef.get(PROVIDERURL));
try {
// Get the InitialContext
InitialContext iniCtx = new InitialContext(props);
// Lookup and narrow
EJBHome home = (EJBHome) PortableRemoteObject.narrow(
(EJBHome) iniCtx.lookup(
ejbRef.get(JNDI_NAME)), EJBHome.class);
// Get the EJB metadata
EJBMetaData metaData = home.getEJBMetaData();
Class homeClass = metaData.getHomeInterfaceClass();
Class remoteClass = metaData.getRemoteInterfaceClass();
// convert handle to real home type
home = (EJBHome) javax.rmi.PortableRemoteObject.narrow(home,
homeClass);
if (!(metaData.isSession() && metaData.isStatelessSession())) {
throw new ActionProcessingException("Only SLSBs are supported!");
}
EJBObject theRemote = (EJBObject) this.create(homeClass, home);
// Assemble parameter array
Object[] param = new Object[ejbParams.size()];
for (int i = 0; i < ejbParams.size(); i++) {
// get the parameter from the esb message and
// cast it to the in the jboss-esb.xml specified type
param[ i ] = Class.forName(ejbParams.get(i).getType()).cast(msg.getBody().get(ejbParams.get(i).getLoc()));
}
msg.getBody().add(ejbRef.get(OUT_VAR), this.invoke(remoteClass, theRemote, ejbRef.get(EJB_METHOD), param));
log.debug("###########################################");
log.debug(msg);
log.debug("###########################################");
} catch (Exception e) {
throw new ActionProcessingException("Got an error while processing EJB " + ejbRef.get(EJB_NAME), new Throwable(e.getCause()));
}
return msg;
}
private static Object create(Class c, Object obj) throws Exception {
Object ret = null;
Method create = c.getMethod("create");
ret = create.invoke(obj);
return ret;
}
private Object invoke(Class c, Object obj, String mname, Object[] params) throws Exception {
// The return Object
Object r = null;
// Assemble method signature array
Class[] sigArray = new Class[ejbParams.size()];
for (int i = 0; i < ejbParams.size(); i++) {
sigArray[ i ] = Class.forName(ejbParams.get(i).getType());
}
// Get the specified method
Method method = c.getMethod(mname, sigArray);
// finally invoke it...
r = method.invoke(obj, params);
return r;
}
// Helper inner class for method arguments and where to find it in the esb message
class Argument {
private String type;
private String loc;
public Argument(String javaType, String esbLoc) {
type = javaType;
loc = esbLoc;
}
public String getType() {
return type;
}
public void setType(String type) {
this.type = type;
}
public String getLoc() {
return loc;
}
public void setLoc(String loc) {
this.loc = loc;
}
}
}
It is not at all well tested, but it works for me.
This is how you can configure it:
<action name="EJBTest" class="de.isogmbh.soa.crm.util.ESBActions.EJBProcessor"> <property name="ejb-name" value="MyStatelessSessionBean" /> <property name="jndi-name" value="ejb/MyStatelessSessionBean" /> <property name="initial-context-factory" value="org.jnp.interfaces.NamingContextFactory" /> <property name="provider-url" value="localhost:1099" /> <property name="method" value="myMethod" /> <property name="esb-out-var" value="MY_OUT_LOCATION"/> <property name="ejb-params"> <arg0 type="java.lang.String">named-message-body-content1</arg0> <arg1 type="java.lang.String">named-message-body-content2</arg1> <arg2 type="java.lang.String">named-message-body-content3</arg2> <arg3 type="java.lang.String">named-message-body-content4</arg3> </property> </action>
Further info:
<property name="esb-out-var" value="MY_OUT_LOCATION"/>
This line is optional and specifies the location where to store the result in the message (e.g. message.getBody.add("MY_OUT_LOCATION", Object). If it is not present the result is stored as "DEFAULT_EJB_OUT".
<property name="ejb-params"> <arg0 type="java.lang.String">named-message-body-content1</arg0> <arg1 type="java.lang.String">named-message-body-content2</arg1> <arg2 type="java.lang.String">named-message-body-content3</arg2> <arg3 type="java.lang.String">named-message-body-content4</arg3> </property>
This tells the action where to find the parameters in the message and the type of the parameters.
(e.g. <arg0 type="java.lang.String">named-message-body-content1</arg0> means the first argument of the SLSB method is a String and can be found in message.getBody().get("named-message-body-content1"))
Greetings,
Dominik
