4. Conditions and Loops | WS-BPEL 2.0 Beginner's Guide

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WS-BPEL 2.0 Beginner's Guide

By : Matjaz B Juric

4.8 (5)

WS-BPEL 2.0 Beginner's Guide

4.8 (5)

By: Matjaz B Juric

Overview of this book

If you are a software architect, a designer, a software developer, an SOA and BPM architect, a project manager, or a business process analyst who is responsible for the design and development of business processes, composite applications, and BPM/SOA solutions, then this book is for you. You should have a clear grasp of general SOA concepts including business processes and web services, but no prior knowledge of the BPEL language is required.

Preface

Preface

What this book covers

What you need for this book

Who this book is for

Conventions

Time for action – heading

Reader feedback

Customer support

Free Chapter

1. Hello BPEL

1. Hello BPEL

Introduction to BPEL

Installing Oracle JDeveloper and SOA Suite

Time for action – installing the JDK and setting environment

Time for action – installing JDeveloper and SOA Suite

Time for action – creating a default domain

Developing our first BPEL process

Time for action – creating the SOA composite application

Time for action – creating XML Schema for the BPEL process

Time for action – modifying WSDL

Time for action – implementing the BPEL process

Deploying the first BPEL process

Time for action – deploying the BPEL process

Testing our first BPEL process

Time for action – testing the BPEL process

Understanding the BPEL language

The BPEL structure

Bookstore BPEL process with branches

Time for action – more sophisticated BPEL process

Time for action – deploying and testing the second BPEL process

Summary

2. Service Invocation

2. Service Invocation

Service invocation and orchestration

Developing the book warehousing process

Time for action – creating the book warehousing process

Time for action – developing the book warehousing process

Understanding sequential invocation

Understanding partner links

Parallel service invocation

Time for action – developing parallel flows

Understanding a parallel flow

Summary

3. Variables, Data Manipulation, and Expressions

3. Variables, Data Manipulation, and Expressions

Variables in BPEL

Variables in BookWarehousingBPEL

Time for action – review of existing variables

Time for action – creating XML type variables

Time for action – creating XML element variables

Time for action – creating a message type variable

Data manipulation and assignments

Time for action – copying variables

Expressions

Time for action – copying variable parts

Manipulating data for external partner links

Time for action – creating the AnotherBookstoreBPEL process

Time for action – extending the BookWarehousing process

Validating variables

Time for action – validating variables

The XSLT transformations

Time for action – using XSLT transformations

Summary

4. Conditions and Loops

4. Conditions and Loops

Conditions

Time for action – selecting the bookstore with the lowest quantity

Time for action – implementing VintageBookstore

Time for action – selecting VintageBookstore

Loops

Adding loops to our example

Time for action – adding the BookOrderManagement process

Time for action – adding the loop

Time for action – the loop

Executing in parallel

Time for action – executing in parallel

Delays

Time for action – adding

Ending a process

Empty activities

Summary

5. Interaction Patterns in BPEL

5. Interaction Patterns in BPEL

Understanding asynchronous invocations

Time for action – implementing an asynchronous invocation

Understanding asynchronous service invocations

Time for action – creating an asynchronous BPEL process

Summary

6. Fault Handling and Signaling

6. Fault Handling and Signaling

Introducing faults and fault handlers

Time for action – adding fault handlers

Modeling execution errors with WS-BPEL 2.0 standard faults

Modeling logical (explicit) errors with the activity

Modeling errors propagated from external web services

Understanding fault handlers and signaling

WSDL faults

Handling faults

In-line fault handling

Time for action – signaling faults

Summary

7. Working with Scopes

7. Working with Scopes

Introducing scopes

Time for action – adding scopes

Time for action – the fault and termination handlers

Summary

8. Dynamic Parallel Invocations

8. Dynamic Parallel Invocations

Introducing dynamic parallel invocations

Time for action – adding a activity

Time for action – configuring the activity within a activity

Time for action – initializing the input variable within a activity

Initializing a dynamic partner link

Time for action – initializing a dynamic partner link

Time for action – appending multiple values to a variable

Summary

9. Human Tasks

9. Human Tasks

Understanding human tasks

Preparing an asynchronous example

Adding a human task to the BookWarehousingBPEL process

Time for action – creating a human task definition

Time for action – configuring the human task title

Time for action – specifying a human task payload

Time for action – assigning a human task

Time for action – configuring human task deadlines

Time for action – configuring human task notifications

Time for action – invoking a human task from the BPEL process

Time for action – configuring human task case branches

Time for action – creating human task forms

Deploying and testing human tasks

Time for action – deploying the human task

Time for action – testing the human task

Summary

10. Events and Event Handlers

10. Events and Event Handlers

Understanding events

Developing an event-driven BPEL process

Time for action – declaring a business event

Time for action – developing an event-driven book shelving BPEL process

Triggering a business event from a BPEL process

Time for action – triggering BookshelfEvent from the book warehousing BPEL process

Adding an event handler to the Book Warehousing BPEL process

Time for action – adding an event handler to the BPEL process

Time for action – adding onEvent to the callback interface

Time for action – specifying alarm event handler activities

Time for action – adding a message handler to the BPEL process

Time for action – declaring the cancel operation on the BPEL process interface

Time for action – specifying message event activities

Asynchronous invocations and events

Time for action – invoking the WarehousingConfirmation service

Time for action – waiting for callback

Time for action – waiting for onFault and onEvent callbacks

Time for action – adding an alarm event for callback

Summary

11. Compensations

11. Compensations

Introducing compensation in business processes

Time for action – adding compensation handlers

Time for action – triggering a fault within the BPEL process

Time for action – triggering compensation for the BPEL process

Summary

A. Pop Quiz Answers

Chapter 1, Hello BPEL

Chapter 2, Service Invocation

Chapter 3, Variables, Data Manipulation, and Expressions

Chapter 4, Conditions and Loops

Chapter 5, Interaction Patterns in BPEL

Chapter 6, Fault Handling and Signaling

Chapter 7, Working with Scopes

Chapter 8, Dynamic Parallel Invocations

Chapter 9, Human Tasks

Chapter 10, Events and Event Handlers

Chapter 11, Compensations

Index

Index

Time for action – selecting the bookstore with the lowest quantity

In the previous chapter, we introduced three bookstores into our composite BPEL application, BookstoreA, BookstoreB, and AnotherBookstore. Let's now modify the conditions in the <if> activity, where we select the bookstore with the lowest book quantity. We have to compare three book quantities of stores in the BookstoreAResponse, BookstoreBResponse, and AnotherBookstoreResponse variables. To access the BookstoreAResponse quantity, we should use the following XPath expression:

$BookstoreAResponse.payload/ns1:StockQuantity

Similarly, we would access the BookstoreB and AnotherBookstore stock quantities.

To select the lowest quantity, we should do the following comparisons:

Compare the BookstoreA stock quantity to BookstoreB and AnotherBookstore. If the BookstoreA stock quantity is lower or equal in both cases, select BookstoreA.
Compare the BookstoreB stock quantity to BookstoreA and AnotherBookstore. If the BookstoreB stock...

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