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e-docs > WebLogic Platform > WebLogic Integration > AI Topics > Using Application Integration > Using Application Views by Writing Custom Code |
Using Application Integration |
Using Application Views by Writing Custom Code
If you are a developer, you may want to modify an Application View by writing custom code. You can use most Application View features through the Application View Console, but some features can be used only by writing custom code.
This section presents two sample scenarios in which custom code is used:
Scenario 1: Creating Connections with Specific Credentials
If you need to assign a security level to an Application View before invoking services on it, you can do so by setting credentials for the appropriate EIS. To do so, use the ApplicationView methods setConnectionSpec() and getConnectionSpec(). Both methods use a ConnectionSpec object.
You can instantiate a ConnectionSpec object in either of two ways: you can use the ConnectionRequestInfoMap class provided by the BEA WebLogic Integration Adapter Development Kit (ADK), or you can implement your own class. If you implement your own class, you must include the following four interfaces: ConnectionSpec, ConnectionRequestInfo, Map, and Serializable.
Implementing ConnectionSpec
Before you can use setConnectionSpec() or getConnectionSpec(), you must instantiate a ConnectionSpec object. Use the ConnectionRequestInfoMap class provided by the ADK, or derive your own class.
To implement ConnectionSpec:
Calling setConnectionSpec() and getConnectionSpec()
After you implement the ConnectionSpec class and instantiate a ConnectionSpec object, you can use both with the following ApplicationView methods:
The following listing provides the code for setConnectionSpec().
Listing 4-1 Complete Code for setConnectionSpec()
/**
* Sets the connectionSpec for connections made to the EIS. After the
* ConnectionSpec is set it will be used to make connections to the
* EIS when invoking a service. To clear the connection spec, and use
* the default connection parameters, call this method using null.
*
* @params connectionCriteria connection criteria for the EIS.
*/
public void setConnectionSpec(ConnectionSpec connectionCriteria)
{
m_connCriteria = connectionCriteria;
}
The following listing provides the code for getConnectionSpec().
Listing 4-2 Complete Code for getConnectionSpec()
/**
* Returns the ConnectionSpec set by setConnectionSpec. If no
* ConnectionSpec has been set null is returned.
*
* @returns ConnectionSpec
*/
public ConnectionSpec getConnectionSpec()
{
return m_connCriteria;
}
Using the ConnectionSpec Class
To set the ConnectionSpec class, pass it a properly initialized ConnectionSpec object. To clear the ConnectionSpec class, pass it a ConnectionSpec object with a null value.
Listing 4-3 shows an example of how ConnectionSpec is used.
Listing 4-3 Example Use of ConnectionSpec Class
Properties props = new Properties();
ApplicationView applicationView = new ApplicationView(getInitialContext(props),"appViewTestSend");
ConnectionRequestInfoMap map = new ConnectionRequestInfoMap();
// map properties here
map.put("PropertyOne","valueOne");
map.put("PropertyTwo","valueTwo");
.
.
.
//set new connection spec
applicationView.setConnectionSpec(map);
IDocumentDefinition requestDocumentDef = applicationView.getRequestDocumentDefinition("serviceName");
SOMSchema requestSchema = requestDocumentDef.getDocumentSchema();
DefaultDocumentOptions options = new DefaultDocumentOptions();
options.setForceMinOccurs(1);
options.setRootName("ROOTNAME");
options.setTargetDocument(DocumentFactory.createDocument());
IDocument requestDocument = requestSchema.createDefaultDocument(options);
requestDocument.setStringInFirst("//ROOT/ElementOne","value");
requestDocument.setStringInFirst("//ROOT/ElementTwo","value");
.
.
.
// the service invocation will use the connection spec set to connect to the EIS
IDocument result = applicationView.invokeService("serviceName", requestDocument);
System.out.println(result.toXML());
Scenario 2: Custom Coding a Business Process
Although the simplest way of using Application Views in business processes is through the WebLogic Integration Studio, you always have the alternative of writing custom Java code to represent your business processes. If you are a developer who writes custom code, we recommend that you familiarize yourself with the simple example presented in this section to demonstrate how a custom business process can be written.
For a thorough comparison of the two methods for using Application Views, see Choosing a Method for Implementing a Business Process.
About This Scenario
Suppose your company uses a customer relationship management (CRM) system and an order processing (OP) system. Management wants to make sure that whenever a customer is created on the CRM system, the creation of a corresponding customer record on the OP system is triggered. Therefore, they ask you, their Java developer, to create a business process that keeps the information maintained by these two systems synchronized. The attached Java class, SyncCustomerInformation, implements this business logic.
This example does not cover everything you can do using custom code. It simply demonstrates the basic steps required to implement your organization's business processes and serves as a template you can use for custom coding your own business processes.
This scenario uses a concrete example class called SyncCustomerInformation to explain how to write custom code. In general, you must perform the following two steps to create custom code that uses an Application View in a business process:
Before You Begin
The following prerequisites must be met before you start writing custom code to implement a business process:
In addition, this scenario is based on the assumption that the following prerequisites have been met:
Note: Your organization must have its own folders and Application Views.
Note: Get the information specific to your organization from your system administrator.
Creating the SyncCustomerInformation Class
Before you can start writing custom code, you must have a Java class representing each application required for the business process. If the necessary Java classes do not exist, create them now. This example calls for one application class called SyncCustomerInformation. Of course, you will use different variable names in your own code. To create the SyncCustomerInformation Java class:
When a New Customer event is received, the onEvent method of the listener is called.
The onEvent method calls a method to respond to the event. In this example, the onEvent method provides the event object that contains the data associated with the event. The method called to respond to the event is called handleNewCustomer.
Code for Sample Java Class
The following listing contains the full source code for the SyncCustomerInformation Java class. This code implements the business logic for the scenario described earlier in this section. Use it as a template for writing code to implement your enterprise's business processes.
Listing 4-4 Full Class Source Code for SyncCustomerInformation
import java.util.Hashtable;
import javax.naming.*;
import java.rmi.RemoteException;
import com.bea.wlai.client.*;
import com.bea.wlai.common.*;
import com.bea.document.*;
/**
* This class implements the business logic for the 'Sync Customer Information'
* business process. It uses the WLAI API to listen to events from the CRM
* system, and to invoke services on the OP system. It assumes that there
* are two ApplicationViews defined and deployed in the 'EastCoast'
* namespace. The Application Views and their required events and services
* are shown below.
*
* CustomerManagement
* events (NewCustomer)
* services (none)
*
* OrderProcessing
* events (none)
* services (CreateCustomer)
*/
public class SyncCustomerInformation
implements EventListener
{
/**
* Main method to start this application. No args are required.
*/
public static void
main(String[] args)
{
// Check that we have the information needed to connect to the server.
if (args.length != 3)
{
System.out.println("Usage: SyncCustomerInformation ");
System.out.println(" <server url> <user id> <password>");
return;
}
try
{
// Create an instance of SyncCustomerInformation to work with
SyncCustomerInformation syncCustInfo =
new SyncCustomerInformation(args[0], args[1], args[2]);
// Get a connection to WLAI
InitialContext initialContext = syncCustInfo.getInitialContext();
// Get a reference to an instance of the 'EastCoast.CustomerManagement'
// Application View
ApplicationView custMgmt =
new ApplicationView(initialContext, "EastCoast.CustomerManagement");
// Add the listener for 'New Customer' events. In this case we have
// our application class implement EventListener so it can listen for
// events directly.
custMgmt.addEventListener("NewCustomer", syncCustInfo);
// Process up to 10 events and then quit.
syncCustInfo.setMaxEventCount(10);
syncCustInfo.processEvents();
}
catch (Exception e)
{
e.printStackTrace();
}
return;
}
/**
* EventListener method to respond to 'New Customer' events
*/
public void
onEvent(IEvent newCustomerEvent)
{
try
{
// Print the contents of the incoming 'New Customer' event.
System.out.println("Handling new customer: ");
System.out.println(newCustomerEvent.toXML());
// Handle it
IDocument response = handleNewCustomer(newCustomerEvent.getPayload());
// Print the response
System.out.println("Response: ");
System.out.println(response.toXML());
// If we have processed all the events we want to, quit.
m_eventCount++;
if (m_eventCount >= m_maxEventCount)
{
quit();
}
}
catch (Exception e)
{
e.printStackTrace();
System.out.println("Quitting...");
quit();
}
}
/**
* Handles any 'New Customer' event by invoking the 'Create Customer'
* service on the 'Order Processing' ApplicationView. The response
* document from the service is returned as the return value of this
* method.
*/
public IDocument
handleNewCustomer(IDocument newCustomerData)
throws Exception
{
// Get an instance of the 'OrderProcessing' ApplicationView.
if (m_orderProc == null)
{
m_orderProc =
new ApplicationView(m_initialContext, "EastCoast.OrderProcessing");
}
// Transform the data in newCustomerData to be appropriate for the
// request document for 'Create Customer' on the 'Order Processing'
// ApplicationView.
IDocument createCustomerRequest =
transformNewCustomerToCreateCustomerRequest(newCustomerData);
// Invoke the service
IDocument createCustomerResponse =
m_orderProc.invokeService("CreateCustomer", createCustomerRequest);
// Return the response
return createCustomerResponse;
}
// ---------------------------------------------
// Member Variables
// ---------------------------------------------
/**
* The url for the WLAI server (e.g. t3://localhost:7001)
*/
private String m_url;
/**
* The user id to use when logging into WLAI.
*/
private String m_userID;
/**
* The password to use when logging in to WLAI as the user given in
* m_userID.
*/
private String m_password;
/**
* The initial context to use when communicating with WLAI
*/
private InitialContext m_initialContext;
/**
* An instance of the 'East Coast.Order Processing' ApplicationView for
* use in handleNewCustomer.
*/
private ApplicationView m_orderProc;
/**
* Hold the maximum number of events to be processed in handleNewCustomer
*/
private int m_maxEventCount;
/**
* Count of the events processed in handleNewCustomer
*/
private int m_eventCount;
/**
* A monitor variable to enable us to wait until we are asked to quit
*/
private String m_doneMonitor = new String("Done Monitor");
/**
* A flag indicating we are done or not.
*/
private boolean m_done = false;
// ------------------------------------------------
// Utility Methods
// ------------------------------------------------
/**
* Constructor.
*/
public SyncCustomerInformation(String url, String userID, String password)
{
m_url = url;
m_userID = userID;
m_password = password;
}
/**
* Establish an initial context to WLAI.
*/
public InitialContext
getInitialContext()
throws NamingException
{
// Set up properties for obtaining an InitialContext to the WLAI server.
Hashtable props = new Hashtable();
// Fill in the properties with the WLAI host, port, user id, and password.
props.put(Context.INITIAL_CONTEXT_FACTORY,
"weblogic.jndi.WLInitialContextFactory");
props.put(Context.PROVIDER_URL, m_url);
props.put(Context.SECURITY_PRINCIPAL, m_userID);
props.put(Context.SECURITY_CREDENTIALS, m_password);
// Connect to the WLAI server
InitialContext initialContext = new InitialContext(props);
// Store this for later
m_initialContext = initialContext;
return initialContext;
}
/**
* Transform the document in the 'New Customer' event to the document
* required by the 'Create Customer' service.
*/
public IDocument
transformNewCustomerToCreateCustomerRequest(IDocument newCustomerData)
throws Exception
{
// We could do an XSLT transform here, or manually move data from the
// source to the target document. The details of this transformation
// are out of the scope of this sample. For information on XSLT see
// http://www.w3.org/TR/xslt. For more information on manually moving
// data between documents, see the JavaDoc documentation for the
// com.bea.document.IDocument interface.
return newCustomerData;
}
/**
* Event processing/wait loop
*/
public void
processEvents()
{
synchronized(m_doneMonitor)
{
while (!m_done)
{
try
{
m_doneMonitor.wait();
}
catch (Exception e)
{
// ignore
}
}
}
}
/**
* Sets the max number of events we want to process.
*/
public void
setMaxEventCount(int maxEventCount)
{
m_maxEventCount = maxEventCount;
}
/**
* Method to force this application to exit (cleanly)
*/
public void
quit()
{
synchronized(m_doneMonitor)
{
m_done = true;
m_doneMonitor.notifyAll();
}
}
}