Author Archives: yohan

Integration Testing with MongoDB & Spring Data

Integration Testing is an often overlooked area in enterprise development. This is primarily due to the associated complexities in setting up the necessary infrastructure for an integration test. For applications backed by databases, it’s fairly complicated and time-consuming to setup databases for integration tests, and also to clean those up once test is complete (ex. data files, schemas etc.), to ensure repeatability of tests. While there have been many tools (ex. DBUnit) and mechanisms (ex. rollback after test) to assist in this, the inherent complexity and issues have been there always.

But if you are working with MongoDB, there’s a cool and easy way to do your unit tests, with almost the simplicity of writing a unit test with mocks. With ‘EmbedMongo’, we can easily setup an embedded MongoDB instance for testing, with in-built clean up support once tests are complete. In this article, we will walkthrough an example where EmbedMongo is used with JUnit for integration testing a Repository Implementation.
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STS in OS X – Where’s the sts.ini?

I’ve been using STS (SpringSource Tool Suite) on OS X Lion for sometime now, and today I realized that it’s getting a bit slow. I thought of tuning the heap size a bit to give it more memory, so I went into the installation to look for eclipse.ini, and there was none. So I googled, and found that STS bundles a ‘sts.ini’ file instead. Unfortunately for me, I wasn’t able to find this one in the folder either! Startled, I tried searching on the directory, etc, but it was not there. After googling around a bit more, I found in Spring Forums that the actual sts.ini file for Mac OS comes inside the application bundle. So if you are using Mac OS, and want to edit the sts.ini file, here are the steps.

  1. Go to your STS installation, and right-click on STS Application
  2. Select ‘Show Package Contents’
  3. A new Finder window will open and show the content of the application bundle. Go to ‘Contents’ directory in this window.
  4. Inside ‘Contents’, go to ‘MacOS’ directory

In this folder (Contents/MacOS) you will find the actual executable (STS) and the STS.ini file. Do your changes to STS.ini file (ex.changing Xmx) and save it just like you would under Linux / Windows with eclipse.ini / sts.ini.

Eventing with Spring Framework

Spring Framework, since it’s inception, included an eventing mechanism which can be used for application-wide eventing. This eventing mechanism was developed to be used internally by Spring Framework for eventing, such as notification of context being refreshed, etc, but it can be used for application specific custom events as well. This eventing API is based on  an interface named {java}org.springframework.context.ApplicationListener{/java}, which defined one method named {java}onApplicationEvent{/java}. Below code snippet shows a simple events listener which just logs the event information.


import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.context.ApplicationEvent;
import org.springframework.context.ApplicationListener;

public class MyEventListener implements ApplicationListener {

	private static final Log LOG = LogFactory.getLog(MyEventListener.class);
	public void onApplicationEvent(ApplicationEvent event) {"Event Occurred : " + event);

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JAX-WS: Working with .NET Web Services

If you happen to write a JAX-WS Web Services client for a service which is written using .NET Platform, you might come across the below error message when you execute wsimport command.

A class/interface with the same name “?????” is already in use. Use a class customization to resolve this conflict.

This happens because .NET generated WSDL documents may contain multiple elements with same name, which leads to a naming conflict when JAXB attempts to generate bindings. If you ever come across this situation, the solution is very simple. You just have to instruct the JAXB generator to automatically resolve any naming conflicts that might occur during the code generation. This can be done by providing -B-XautoNameResolution argument to wsimport tool. Note that the ‘-B-XautoNameResolution’ has no spaces. -B is used to pass instructions to JAXB Schema Compiler.

An example would be:

wsimport -d gen-src -verbose -B-XautoNameResolution

Note that generated code will refer to duplicate names with a numeric suffix. For example, if there are two elements with name ‘XYZ’, one class will be ‘XYZ’, and the other occurrence will be named as ‘XYZ2’.

Getting SOA Right – Thinking Beyond ‘The Right Angles’

Cable Mess

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There was a time when Service Oriented Architecture was a buzzword. That time is now long gone, and SOA has become one of the essentials of enterprise software architecture. Due to the adaptation of SOA by many leading enterprises (such as Facebook, Amazon) and software systems, there is a trend of everyone wanting to be ‘service oriented’. Engineers talk about building web services, JSON services, RESTful APIs, but a significant number of them have been mislead by various misnomers (no pun intended) regarding SOA.

SOA is based on a concept which is inline with the basics of object orientation, and component based software engineering. What it advocates is to build services that focuses on a specific functionality (thus coherent), and to have a well defined API, backed by an encapsulated implementation. There’s more to it (and above sentence does no justice to SOA, I agree), but that’s the basic idea behind SOA. This might be one reason why Gregor Hohpe calls it ‘Same Old Architecture’ [1]. However, this simplicity is often mistaken, and solutions which are not at all SOA are labelled as SOA today.

One of the nicest descriptions of SOA is the one circulated by Jeff Bezos, CEO of Amazon within his organization. Steve Yegge, who was an ex-amazonian and currently works for Google, wrote and amazing article about how well Amazon developed their platform in a SOA way, and how Google should improve on the platforming and SOA front. Yes, you heard that right. Even Google, the tech-giant is yet to learn the right use of SOA. Steve’s post was supposed to be published in an internal blog of Google, but he mistakenly published it in his public blog (which was withdrawn later). If you are interested, you can still read it at (which is a very insightful article).

Coming back to the topic, Jeff Bezos circulated the following at Amazon around 2002, when he decided that Amazon should build a platform. He never said it’s SOA, and he didn’t care about technology. Yet it worked, and transformed Amazon to the massive services platform it is today. Bezos said,

  1. All teams will henceforth expose their data and functionality through service interfaces.
  2. Teams must communicate with each other through these interfaces.
  3. There will be no other form of interprocess communication allowed: no direct linking, no direct reads of another team’s data store, no shared-memory model, no back-doors whatsoever. The only communication allowed is via service interface calls over the network.
  4. It doesn’t matter what technology they use. HTTP, Corba, Pub-Sub, custom protocols — doesn’t matter. Bezos doesn’t care.
  5. All service interfaces, without exception, must be designed from the ground up to be externalizable. That is to say, the team must plan and design to be able to expose the interface to developers in the outside world. No exceptions.
  6. Anyone who doesn’t do this will be fired.

Above six points (or the first five) lays down the foundation for building a service oriented architecture. All communication happens through well-defined service interfaces, no exceptions. Each service is self-contained. Services are re-usable and externalizable. Another key point that should be highlighted is that ‘technology is not important’ for SOA. SOA is an architecture which can be applied for any technology.
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