Weblog for the AMIS Technology corner
Posts tagged mediator
Publish SOA Composite application as EJB to be invoked from Java applications using EJB Binding
Jun 14th
With the recent (April 2010) SOA Suite 11g R1 Patch Set 2 (11.1.1.3.0), several new capabilities have been added to the SOA Suite. One these is the EJB Binding. Or rather, an enhanced version of this binding. In previous releases, this binding was available to provide interaction with SDO enabled EJBs – based on a WSDL interface and XML messages. The PS2 release added full Java support to the EJB binding. This means that we do not have to concern ourselves with WSDL and XSD that maps to the Java interface we want to invoke or expose, nor with sending a XML based payload when we invoke the composite service. All we need is the Java interface that describes either the EJB that we want to invoke (for an EJB Binding Reference) or that we want to expose (for an EJB Binding Service).
Steps:
1. Create Composite like always
2. Create a Java Interface (and possibly Java domain classes or bean types describing the structure of the input and ouput of the methods on the EJB (that should correspond with the operations available in the Composite application)
package nl.amis.utilities;
public interface FilterAndTranslate {
public String translate(String input);
}
Note: steps 1 and 2 can be reversed; especially when you want to work according to the contract (or design) driven approach, that would probably be best.
Note: thusfar I have only been successful with a Java interface that only uses simple types (my own domain objects and beans prevented deployment of the EJB for some reason)
3. Create an EJB Binding in the Services lane, based on this Java interface. Specify the JNDI Name for this EJB. For example: FilterAndTranslateEJB
Calling an EJB from a SOA Composite Application using the EJB Binding based on Java Interface
Jun 13th
I am currently reworking Chapter 12 for the SOA Suite 11g Handbook. This chapter describes various types of interaction SOA Composite Applications can have with Java applications and components. Since the initial creation of this chapter – some 6 months ago – we have had the Patch Set 2 release of the SOA Suite. This patch set introduced some additional functionality in this particular area of the SOA Suite, including the EJB Binding directly based on a Java Interface rather than on an SDO service created for the EJB. While that last option did the job, it requires manipulation of the EJB that is to be invoked – to SDO enable it – and that was undesirable and sometimes even impossible.
This article describes about the simplest way to get going with the EJB Binding – Java based – in Patch Set 2 (11.1.1.3.0). Building on this example, you will probably find yourself able to do useful things with it.
The steps we will go through are:
1. Create the EJB that is to be invoked from the Composite application through EJB Binding. Make sure the remote interface is created as well.
2. Deploy this EJB (in this simple example to the same WebLogic Managed Server that is running the SOA Suite)
3. Create a new SOA Composite Application
4. Copy the remote interface to the SCA-INF/src directory (or copy a JAR containing that interface to SCA-INF/lib)
5. Create an EJB Binding Reference. Configure it to invoke the EJB created and deployed above; specify the Java Interface that describes the interaction
6. Create a Mediator that is wired to the EJB Binding Reference; create mappings from the input and output of the Mediator to the XML structure derived by JDeveloper from the Java Interface definition
7. Finish the composite application; from here on it is ‘business as usual’ since none of the other components in the applications are aware that the Mediator talks to something ’special’ like an EJB.
Book review of: Getting Started With Oracle SOA Suite 11g R1: A Hands-On Tutorial
Apr 18th
Getting Started With Oracle SOA Suite 11g R1: A Hands-On Tutorial
Authors: Demed L’Her, Heidi Buelow, Jayaram Kasi, Manas Deb, Prasen Palvankar (aka Oracle Product Management for SOA Suite)
A hands-on tutorial is what the cover of the book promises, and that is exactly what you get. A quick, very hands-on introduction into the most important components in the SOA Suite 11g. In no time at all, readers will be able to get a composite application up and running. An application that leverages many of the essential features and functions in the SOA Suite.
Some books are primarily an introduction into a certain topic, with lots of theory, background and explanations of what, why and how. Other books are mainly reference material that you use to look things up when you need them. This book is neither – it offers very little in the way of explanation and background and it would be fairly useless as reference guide. It is however a very good way to get to know the SOA Suite – both design time and run time – and get a feel for how to develop for it and run applications in it.
The book contains a large number of informative screenshots and also provides the salient code snippets. It is very focused on getting specific jobs done, and for these jobs it has all the information and illustrations you may need. It is hard to not get it to work following the very detailed instructions.
The book – or at least the paper copy I am holding – is written for the very first 11gR1 release, that was published on July 1st 2009. The functions made available with PS1 release (November 2009) are not discussed therefore.
SOA Suite 11g – Using Spring Component to mimic Http Binding and integrate RESTful services
Dec 16th
In an earlier post, I showed for the Oracle SOA Suite 11g how we can use the Mediator's Java Callout functionality to integrate RESTful services into our SOA Composite applications, even though we currently have no Http Binding Service nor WSIF support (SOAP Java Binding) at our disposal in the SOA Suite – link to article. In SOA Suite 11g PS1 – released in November 2009 – is the preview (not yet officially supported and only available for PoC and early trials – of Spring components. This feature provides another way of integrating Java classes into our SOA Composite applications.
This article demonstrates how we can use the Spring component to bind our SOA Composite Application to the RESTful Translation service provided by Google.
The Oracle SOA Suite 11g HttpBinding or another way to call RESTful services from SOA Composite Applications
Dec 15th
I wanted to take a quick look at REST(ful) WebServices and see how those can be integrated into the SCA based SOA Composite Applications that we create with the Oracle SOA Suite. Currently, it does not have the HTTP binding that the 10.1.3 release of the SOA Suite used to have. So what are the alternatives?
In this article, I want to demonstrate a way of calling RESTful (simple http request based) services into a SOA Composite application. I show one way of doing so using the Google Translation Service, a RESTful service described at http://code.google.com/apis/ajaxlanguage/documentation/ and to be accessed at http://ajax.googleapis.com/ajax/services/language/translate?v=1.0&q=hello%20world&langpair=en%7Cit. This service takes a string to translate and an indication of a source and a destination language. Though maybe not formally resource oriented enough to be called REST-style (or RESTful) service by some, it is a service that does not require SOAP or WS* but simply a HTTP Get request. So at least quite restful.
In this article I will use the work I did and described in the previous article: Leveraging RESTful Services from Java application using Jersey (Introduction). Using project Jersey's support for clients of RESTful services and the JSON-SIMPLE library to interpret the response I get from the GoogleTranslation service, I will hook up with the RESTful Service. Then I will leverage the Mediator Java Callout mechanism to integrate this REST-service-client into a SOA Composite application. The Mediator I create will be the fully SOA Suite integrated front-end of this RESTful Service.
SOA Suite 11g – introducing Mediator Java Callouts for debug, audit and …
Dec 13th
The Mediator component in SOA Suite 11g has a the option to specify a Java Callout, one for every WSDL operation. The Java Callout refers to a Java Class, either on the SOA Suite's classpath or deployed as part of the SOA Composite application. This class should implement interface oracle.tip.mediator.common.api.IJavaCallout and a convenient way of doing so is by extending AbstractJavaCalloutImpl in package oracle.tip.mediator.common.api.
The Java Callout is invoked by the Mediator on a number of times, prior to and after performing the Routing Rule and each of the cases in it. The Java Callout class can implement a number of methods, one for each specific event or stage in the Mediator process. These methods get access to the input message as well as the transformation result. That means that the callout class can inspect, validate, log, audit and even manipulate these messages, their payloads, headers and properties. Interestingly enough, the methods are not static what I thought might be the case. The first one to be called is an initialize() that has you initialize the callout class instance to prepare the object for further callout processing. This means that all stages in a single Mediation action are processed by the same callout object. This allows you to compare for example the pre and post transformation values.
The methods that the callout interface specifies are: initialize, preRouting (before any routing rule cases are processed), preRoutingRule (before one specific routing rule is processed), preCallbackRouting (This method is called before Mediator finishes executing callback handling. You can customize this method to perform callback auditing and custom fault tracking.) , postCallbackRouting, postRoutingRule, postRouting.
This article shows a simple example of creating a SOA Composite Application – the simplest one you can create I believe using the new 11g feature of Echo – with use of the Java Callout class.
OOW 2009: Introducing SOA and Oracle SOA Suite 11g for Database Professionals
Oct 11th
The Oracle Open World 2009 conference is almost underway. On Monday 12th October I will do two presentations, and I am done preparing the first one of them (the one that has actually sold one – probably scheduled in a small room).This presentation is one in which I introduce the key concepts and objectives of SOA (Service Oriented Architecture) as well as the Oracle SOA Suite 11g to an audience of database professionals. Whether DBA or Database Developer, SOA is unavoidable. But what (exactly) is it? And how does it impact – positively or negatively – the work and lives of database professionals? What can a database professional do to work well with SOA and the SOA technology once that starts being implemented in her or his organization?
SOA Suite 11g (TP4) – Create Mediator based SCA Composite Application from XSD – write to output file using File Adapter
Jan 22nd
A quick overview of you can create an SCA Composite Application that publishes a WebService interface, accepts SOAP Messages and write their contents to a file, appending a new record to the current contents. In the center of the composite sits a Mediator. Its interface is based on a WSDL that is created directly from an XSD document that describes the XML messages that have to be processed. The Mediator is then exposed as Service through a simple drag & drop operation. An outgoing file adapter service is created that writes its input in a comma separated record format to an existing file. Finally with another drag and drop, the Meditor is wired to this File Adapter Service and – with more dragging & dropping – the mapping between the incoming XML message and the outgoing CSV record is created.
This is all done using Oracle 11g SOA Suite, Technology Preview 4.
