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Using Application Integration

Introduction to Application Integration

This document provides instructions for using adapters built with the BEA WebLogic Integration Adapter Development Kit (ADK). It explains how to define Application View services and events and use them in your business processes in a WebLogic Integration environment.

This section provides the following topics:

- Before You Begin

- Creating an Interface to an Adapter

- Defining an Application View

- Using an Application View in a Workflow

- Using an Application View with Web Services

Note: Because all adapters and applications are different, the instructions provided in this document are generic: they are not written for a specific adapter or application. For details about the DBMS adapter provided with the ADK, see The DBMS Adapter in Developing Adapters.

Before You Begin

Before you can begin using adapters to integrate your enterprise, you must set up your environment and learn about how WebLogic Integration uses adapters and Application Views to help achieve integration.

This section provides the following information:

- Software Prerequisites

- Familiarizing Yourself with Basic Concepts

Software Prerequisites

Note: For a detailed list of prerequisites, see the BEA WebLogic Platform Release Notes.

Make sure the following prerequisites are satisfied:

- You have installed WebLogic Platform.

- You have installed JDK 1.3.1. The JDK 1.3 development kit is automatically installed when you install WebLogic Platform. If you prefer, however, you may install your own version, as long as it is 1.3.1-compliant.

- You have included BEA WebLogic Integration as part of your WebLogic Platform installation.

- You have deployed each adapter for which you will define Application Views.

In this release, the application integration functionality of WebLogic Integration is packaged in a single, self-contained J2EE EAR file. This packaging enables you to deploy application integration capabilities on any valid WebLogic Server domain. For example, Web services developers and WebLogic Portal developers can use Application Views to interact with EIS applications. For more information, see Modular Deployment of Application Integration.

Familiarizing Yourself with Basic Concepts

If you are not familiar with the basic concepts of application integration, we recommend that you take the time to read the overview of application integration provided in Introducing Application Integration.

Then you will be ready to learn how to address practical issues, such as when to use one application integration method rather than another, and how to implement the method you select.

Creating an Interface to an Adapter

For each adapter to be used in your enterprise, you must provide an interface to the services and events that it provides. You can create such an interface in either of two ways: by defining Application Views or by writing custom code.

Application views provide the most convenient method of accessing an adapter's resources. In most situations you will probably choose this method for exposing the application functions provided by each adapter. However, if you require more control over an adapter's functions than that afforded by Application Views, you may also write custom code.

You are responsible for deciding whether your enterprise can derive greater benefit from Application Views or custom code. The following sections provide basic guidelines for choosing between these two methods. For details, see Defining an Application View.

When to Define an Application View

Most enterprise information system (EIS) applications can be integrated easily by defining Application Views. In general, you should define Application Views if one or more of the following criteria are true:

- You have more than one EIS in your enterprise, and you lack developers with detailed, thorough knowledge of all systems.

- You want to construct business processes using the WebLogic Integration Studio.

- You need to update the parameters of an adapter or one of its processes.

When to Write Custom Code

You should write custom code as an interface to an adapter only if one or more of the following criteria are true:

- You have only one EIS in your enterprise and your developer has thorough, detailed knowledge of the EIS involved in the business processes being coded.

- You do not need to use the business process management (BPM) functions provided by WebLogic Integration.

- Your code will never require changes.

Defining an Application View

An Application View for an adapter is an XML-based interface between WebLogic Server and a particular EIS application. You must define an Application View for each adapter used by your enterprise.

This section describes:

- What Is Defined by an Application View Definition

- How to Define an Application View

What Is Defined by an Application View Definition

When you define an Application View, you must configure communication parameters for it, and then add services and/or events to it. The Application View's services and events expose specific functions of the application. The communication parameters of the Application View govern how the Application View connects to the target EIS.

An Application View definition specifies:

- A unique name for the Application View

- Security privileges for users of the Application View

- Parameters for the:

- Application

- Network connections between the application and the Application View

- Management of the pool of connections available to the Application View

- Load balancing to be performed by the Application View

How to Define an Application View

This section provides a high-level overview of the procedure you must complete to define Application Views for adapters. For detailed instructions, see Defining an Application View.

Defining an Application View involves the following steps:

- Step 1: Name and Configure Connection Parameters for an Application View

- Step 2: Add Services and Events to the Application View

- Step 3: Test Services and Events

Step 1: Name and Configure Connection Parameters for an Application View

The first step in defining an Application View for an adapter is to log on to the Application View Console, optionally create or select one or more folders in which the Application View will reside, and configure EIS connection parameters for it.

For details about creating and configuring an Application View, see the following topics:

- Step 1: Log On to the Application View Console

- Steps 2 and 3: Define an Application View and Configure Connection Parameters

Step 2: Add Services and Events to the Application View

Services and events support a subset of an application's business processes by enabling WebLogic Server clients to interact with the application functions you specify. The services and events offered by an Application View allow specific types of transactions between WebLogic Server and the EIS application.

For details about adding services and events to an Application View, see the following topics:

- Step 4A: Add a Service to an Application View

- Step 6B: Test an Application View's Events

Step 3: Test Services and Events

Verify that your services or events interact properly with the EIS application.

For details about testing services and events, see the following topics:

- Step 6A: Test an Application View's Services

- Step 6B: Test an Application View's Events

Using an Application View in a Workflow

Once you define an Application View in your WebLogic Integration environment, you can deploy it on WebLogic Server and use it to implement your enterprise's business processes in a business process workflow.

You can use Application Views in business processes in either of the following ways:

- By designing business process workflows in the WebLogic Integration Studio

- By writing custom code

When an Application View is used in your business process workflow, the end result is a deployed electronic representation of your enterprise's business process. The workflow specifies the transactions to be performed by your applications to accomplish the business processes. The Application Views perform the transactions themselves.

Using an Application View in the WebLogic Integration Studio

The most common way to use an Application View in your enterprise's business processes is by designing a workflow in the WebLogic Integration Studio. The Studio is a graphical user interface (GUI) for designing business process workflows. These workflows can include Application View services and events.

You can use an Application View to support services and events in any of the following four ways:

- Task 1: Set Up a Task Node to Call an Application View Service

- Task 2: Set Up an Event Node to Wait for a Response from an Asynchronous Application View Service

- Task 3: Create a Workflow Started by an Application View Event

- Task 4: Set Up an Event Node to Wait for an Application View Event

For detailed information about each task, see Using Application Views in the Studio.

Using an Application View by Writing Custom Code

If you do not implement your business process by using an Application View through the Studio, you must write custom Java code, instead. For instructions, see Using Application Views by Writing Custom Code.

Choosing a Method for Implementing a Business Process

WebLogic Integration allows you to implement your business processes by using either of two methods: by creating a workflow in the Studio or by writing custom code. Any business process can be implemented as a Studio workflow.

Custom coding, however, should be attempted only if the target business process is extremely simple and specialized. In this document, custom coding is described only as an alternate method to be used in situations that require it. For a list of such situations, see When to Write Custom Java Code.

When to Use the WebLogic Integration Studio

Use the WebLogic Integration Studio to implement a business process if one or more of the following criteria are true:

- Your business processes require complicated error management, persistent processes, and sophisticated conditional branching.

For example, if your business process must receive numerous events, select a subset of them, perform complex branched actions, generate many complex messages, and send the messages to various WebLogic Server clients, then you should use the Studio.

- Your business process requires periodic changes.

The Studio reduces the number of required compile/test/debug cycles.

- Your developers (like those in most organizations) are valuable and scarce.

When to Write Custom Java Code

Write custom code to implement a business process only if one or more of the following criteria are true:

- Your business process is simple; that is, it includes no complicated error recovery, long-lived processes, conditional branching, or joining of the process flow.

For example, if your business process performs a limited set of actions on an incoming message, and then routes the message to a small number of client applications, you can safely write custom code for it.

- You do not anticipate the need for frequent updates to the business process.

Whenever you update custom code, a full compile/test/debug cycle, which can be costly, is required.

- Your organization can afford to allocate developers for the job of implementing business processes in code.

Using an Application View with Web Services

A developer of Web Services can use an AppView Control to provide users of BEA WebLogic Workshop with a Web Service that interacts with an EIS application. The interaction is implemented using a Java API. A Web services developer is not required to be an expert on the EIS to use its capabilities. A developer can invoke Application View services both synchronously and asynchronously, and can subscribe to Application View events using simple Java objects. For more information about using AppView Controls, see Application View Control: Accessing an Enterprise Application from a Web Service in BEA WebLogic Workshop online documentation at the following location:

>     http://edocs.bea.com/workshop/docs70/help/index.html#guide/
>     controls/appview/conAppViewCtrlAccessAnEnterpriseAppFromAJWS.html