Claus Ibsen (@davsclaus) riding the Apache Camel: A few recent Apache Camel presentations on youtube. Q&A With Claus Ibsen on Apache Camel. If you have ever been faced with the task of integrating multiple enterprise services, Apache Camel is definately a tool you should have in your toolbox. In this Q&A, Claus Ibsen shares some insights into the origins of Camel, how to get started, some of the challenges working on a such an ambitious project, and where Camel is going.
What was the inspiration for the development of Camel? A decade ago the book Enterprise Integration Patterns was published. The book contains a catalog of integration solutions that its authors, Gregor Hohpe and Bobby Wolff, had encountered during their years as integration consultants. You can say this book is the equivalent of the famous gang-of-four-book. James Strachan, the creator of Apache Camel, meet Gregor in person to discuss his book, and after that he was inspired to write a software implementation of the book. So in essence he wanted to write a small independent routing library that implements the EIP patterns from the book. ExcelConverterBean. Tutorial-Business-Partners. Tutorial Business Partners Under Construction This tutorial is a work in progress. Background and Introduction Business Background So there's a company, which we'll call Acme. Sadly, Acme's sales people are, technically speaking, doormats. The result is pretty much what you'd expect.
Customer 1: XML over FTPCustomer 2: CSV over HTTPCustomer 3: Excel via e-mail Now on the Acme side, all this has to be converted to a canonical XML format and submitted to the Acme accounting system via JMS. So it turns out Camel can handle all this: Listen for HTTP, e-mail, and FTP filesGrab attachments from the e-mail messagesConvert XML, XLS, and CSV files to a canonical XML formatread and write JMS messagesroute based on company IDformat e-mails using Velocity templatessend outgoing e-mail messages Tutorial Background This tutorial will cover all that, plus setting up tests along the way.
Before starting, you should be familiar with: You'll learn: High-Level Diagram First, the input from the customers to Acme: Critical HL7 Usecases With Camel, ActiveMQ, Elasticsearch – Software Blog. HL7 over MLLP is a very common transport mechanisms for systems that can speak the HL7 protocol format. JBoss Fuse is a very powerful microservices-style integration platform and has a proven track record for building flexible, resilient, highly available integration scenarios for critical health-care providers.
Additionally, replacing legacy vendors like SeaBeyond on JCAPS is the sweet spot for these types of Fuse implementations. I’ve recently posted a pilot or set of POC code at github that walks through some important use cases as well as some best practices for using Fuse and Fuse Fabric (fabric8). Criticality of integrations The integrations that get deployed as part of a Fuse implementation that support health-care usecases, including HL7 integrations, are typically part of Tier 1 applications with utmost uptime and resilience requirements. Overall architecture This POC divides a typical flow into 3 individually deployable microservices: JBoss Fuse Fuse insight!
Getting Started. Java Tip: Write an SOA integration layer with Apache Camel. In this Java tip, learn how to use Apache Camel to develop a quick-and-easy integration layer for a service-oriented architecture. Apache Camel lets you configure Camel integration components for web service endpoints; message transformation, routing, and aggregation; and exception handling. All with a minimum of Java coding. Introduction Integration is a top priority for enterprise projects that seek to connect multiple web service endpoints quickly, efficiently, and maintainably.
From a development standpoint, integration can also be a serious challenge. One way to ease that challenge is by using an integration framework like Apache Camel. Apache Camel's API and out-of-the-box components implement many common enterprise integration patterns (EIPs), making it relatively simple and easy to do integration tasks such as connecting web services, performing XSL transformations, logging audits, and more. An enterprise integration scenario Figure 1. Async. Async Available as of Camel 2.0 The asynchronous API in Camel have been rewritten for Camel 2.0, and the information on this page applies for Camel 2.0 and later. The Async API in Camel is primarily divided in two areas 1. Initiating an Async messaging from the client 2. Turning a route into Async using the threads DSL Before we look at these two areas we start with a bit of background information and looks at the concept from at a higher level using diagrams.
Then we check out the first area how a client can initiate an Async message exchange and we also throw in the synchronous message exchange in the mix as well so we can compare and distill the difference. Background The new Async API in Camel 2.0 leverages in much greater detail the Java Concurrency API and its support for executing tasks asynchronous. A few concepts to master When doing messaging there are a few aspects to keep in mind. First of all a caller can initiate a message exchange as either: synchronousasynchronous 1. 1. 1. 1. Cluster computing - Apache Camel with ActiveMQ clustering. Processor.
The Processor interface is used to implement consumers of message exchanges or to implement a Message Translator Using a processor in a route Once you have written a class which implements processor like this... You can then easily use this inside a route by declaring the bean in Spring, say via the XML (or registering it in JNDI if that is your Registry) Then in Camel you can do Using the process DSL In your route you can also use the process DSL syntax for invoking a processor. If you need to lookup the processor in the Registry then you should use the processRef DSL: Why use process when you can use to instead? The process can be used in routes as an anonymous inner class such: This is usable for quickly whirling up some code. Turning your processor into a full Component There is a base class called ProcessorEndpoint which supports the full Endpoint semantics given a Processor instance.
See Also. Antipatterns/Misuse When Using Apache Camel | Making Development Simple. This is not a reflection on Apache Camel as a product, but simply some observation of patterns in Camel misuse in my current project's codebase. It is also not a reflection of the development team I work with, as most of the problems have occurred due to the learning curve in a newly formed team and in using a new framework. Hopefully, if others have experienced similar problems, this will help. Feel free to share anti-patterns and misuse you have seen when using Camel. Using Camel routes/processors for business logic. Business logic should be in an ordinary POJO and a Camel processor could be used to invoke the bean. Or just use the bean (bean:) component directly in your routes. Not mocking business logic. Writing Camel integration or component tests but no sub-route unit tests.
Insufficient Camel integration testing. Putting unnecessary Camel endpoints into configuration. It should NOT be use to assert that the correct things have been received by the mock. So instead of: use: ServletListener Component. Available as of Camel 2.11 This component is used for bootstrapping Camel applications in web applications. For example beforehand people would have to find their own way of bootstrapping Camel, or rely on 3rd party frameworks such as Spring to do it. Sidebar Icon This component supports Servlet 2.x onwards, which mean it works also in older web containers; which is the goal of this component. Though Servlet 2.x requires to use a web.xml file as configuration. For Servlet 3.x containers you can use annotation driven configuration to boostrap Camel using the @WebListener, and implement your own class, where you boostrap Camel.
Maven users will need to add the following dependency to their pom.xml for this component: Using You would need to chose one of the following implementations of the abstract class org.apache.camel.component.servletlistener.CamelServletContextListener. Options Examples See Servlet Tomcat No Spring Example. Configuring routes Using a RouteBuilder class Using package scanning. Dynamic change endpoint camel. Downloads - camelinaction - Camel in Action Source Code.