Mule in Action

John D'Emic, Victor Romero, David Dossot

• Publisher: Manning
• Year: 2014
• ISBN:
  9781638352945
• Topic: Ciencia de la computación
• Subtopic: Programación en Java

Summary Mule in Action, Second Edition is a totally-revised guide covering Mule 3 fundamentals and best practices. It starts with a quick ESB overview and then dives into rich examples covering core concepts like sending, receiving, routing, and transforming data. About the Technology An enterprise service bus is a way to integrate enterprise applications using a bus-like infrastructure. Mule is the leading open source Java ESB. It borrows from the Hohpe/Woolf patterns, is lightweight, can publish REST and SOAP services, integrates well with Spring, is customizable, scales well, and is cloud-ready. About the Book Mule in Action, Second Edition is a totally revised guide covering Mule 3 fundamentals and best practices. It starts with a quick ESB overview and then dives into rich examples covering core concepts like sending, receiving, routing, and transforming data. You'll get a close look at Mule's standard components and how to roll out custom ones. You'll also pick up techniques for testing, performance tuning, and BPM orchestration, and explore cloud API integration for SaaS applications.Written for developers, architects, and IT managers, this book requires familiarity with Java but no previous exposure to Mule or other ESBs.Purchase of the print book includes a free eBook in PDF, Kindle, and ePub formats from Manning Publications. What's Inside

• Full coverage of Mule 3
• Integration with cloud services
• Common transports, routers, and transformers
• Security, routing, orchestration, and transactions

About the Authors David Dossot is a software architect and has created numerous modules and transports for Mule. John D'Emic is a principal solutions architect and Victor Romero a solutions architect, both at MuleSoft, Inc. Table of Contents
PART 1 CORE MULE

• Discovering Mule
• Processing messages with Mule
• Working with connectors
• Transforming data with Mule
• Routing data with Mule
• Working with components and patterns
• PART 2 RUNNING MULE
• Integration architecture with Mule
• Deploying Mule
• Exception handling and transaction management with Mule
• Securing Mule
• Tuning Mule
• PART 3 TRAVELING FURTHER WITH MULE
• Developing with Mule
• Writing custom cloud connectors and processors
• Augmenting Mule with orthogonal technologies

Part 1. Core Mule

Mule is a lightweight, event-driven enterprise service bus and an integration platform and broker. As such, it resembles more a rich and diverse toolbox than a shrink-wrapped application. In the first chapter of this book, we’ll introduce you to the history of its origins and the competing projects that exist on the market, and then we’ll immediately dive into a quick tutorial that will get your feet wet and your mouth watering!

In chapter 2, we’ll go through an extensive review of the principles involved in processing messages with Mule. You’ll learn the notions of flows, message sources, and processors and will look deep into the structure of the Mule message. The Mule Expression Language (MEL) will be introduced too.

Chapter 3 will be the first one dedicated to one of the major moving parts of Mule: transports and connectors. You’ll discover the most prominent protocols that the platform supports in the context of actual configuration samples. You’ll also learn how connectors can help you interact with the cloud by looking at a simple Twitter example.

A second important feature of Mule is message transformation. Chapter 4 will show you how to take advantage of Mule transformers and how to create new ones.

Message routing is a crucial facet of enterprise message buses. We’ll explore the advanced capacities of Mule in this domain in chapter 5.

Finally, we’ll close this first part with chapter 6, which will focus on components and patterns, the places where message and business logic happens in Mule.

Chapter 1. Discovering Mule

This chapter covers

• An introduction to enterprise integration
• Building, testing, and deploying your first Mule application

All it takes is a simple request: send this to Salesforce, publish that to Twitter, connect to the inventory mainframe. All of a sudden, your application, which was living a happy digital life in splendid isolation, has to connect to a system that’s not only remote but also exotic. It speaks a different language, or speaks a known language but uses a bizarre protocol, or it can only be spoken to at certain times during the night...in Asia. It goes up and down without notice. Soon, you start thinking in terms of messages, transformation, protocols, and connectors. Welcome to the world of integration!

The IT landscape has been shaped by years of software evolution, business mergers, and third-party API integration, which led to a complex panorama of heterogeneous systems of all ages and natures. Strategic commercial decisions or critical reorganizations heavily rely on these systems working together as seamlessly as possible. The need for application integration is thus a reality that all enterprise developers will have to deal with during the course of their careers. As Michael Nygard, author of Release It! (Pragmatic Bookshelf, March 2007) states, “Real enterprises are always messier than the enterprise architecture would ever admit. New technologies never quite fully supplant old ones. A mishmash of integration technologies will be found, from flat-file transfer with batch processing to publish/subscribe messaging.”

Developing integration applications encompasses a variety of difficulties:

• Protocol— Applications can accept input from a variety of means, ranging from a local filesystem to a RESTful API.
• Data format— Speaking the right protocol is only part of the solution, since applications can use almost any form of representation for the data they exchange.
• Invocation styles— Synchronous, asynchronous, RPC, messaging, and batch call semantics entail very different integration strategies.
• Lifecycle and management— Applications of different origins that serve varied purposes tend to have disparate development, maintenance, and operational lifecycles.
• Error handling— Error handling is crucial in any application and is amplified with applications that are forced to integrate with remote, and often unreliable, systems.
• Monitoring— Integration applications often have more esoteric monitoring requirements than a traditional web or server-side application. These include the monitoring of transactions per second, awareness of the latency of remote servers, and the absence of events, to name a few.

This book is about Mule, the leading open source enterprise integration platform, which will help you tackle these difficulties and much more. Mule frees you from much of the plumbing associated with enterprise application integration, allowing you to focus on your application’s core requirements.

In this chapter, you’ll gain a high-level understanding of Mule before we dive head first into building a real, complete Mule application. This will prepare you for the rest of the book, in which you’ll learn how Mule lets you focus your development effort on solving business problems instead of fighting low-level integration “donkey work.”

1.1. Enterprise Integration Patterns and service-oriented architecture

The last decade or so has seen a renaissance of application integration. Gone are the days of proprietary messaging stacks and closed APIs. Open platforms, protocols, and services dominate the landscape. Nothing is more evidence of this than the “API Explosion” of recent years as companies, organizations, and governments race to expose their data. REST, JSON, and lightweight message brokers lead the charge but, as always, don’t allow you to throw out what’s already in place (or more importantly, what alread...