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White Papers

I have just uploaded two papers: Agile Software Development of Service Oriented Architectures, Business Process Models and Enterprise Service Buses Service Oriented Architecture Strategies They can be downloaded from: http://www.maxant.ch/white-papers

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Reporting Stats

A few years ago when I was the integration architect in charge of my Global 500 customers EAI projects, the product that we used did not really offer any way to track the number of messages travelling through the system. To get around this, we added a little library that recorded a small amount of information about each message. The idea was that every application (message flow) within the EAI system would be instrumented with this code and we would gain an oversight over which interfaces were the important ones and which ones made a return on their investment. The sort of data we collected was: Interface / Application / Process Name Message Type Message Size Timestamp Status (eg. IN, OUT, SUCCESS, FAIL) Correlation Token (in case several messages belonged together) Error (ie. details of an error) Custom Data (specific to each interface / app / process) There was probably more... it was a few years ago now :-) Anyway, we soon discovered that there were applications that were not even being used, even though our customers had paid many tens of thousands of dollars for them (ok, I admit that isn't a lot of money in the IT world). Since then Google has created its "Analytics" offering which generates some excellent reports for web site statistics. Indeed, maxant has always collected web stats for the websites it runs. It is very important to know your users / customers usage patterns, in order to be able to understand their real…

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Spring Services Anywhere

I recently embarked on some Spring "re-training" (I haven't looked at it in a few years and it was time to get my skills up to scratch again). Since the last time I looked at Spring, I have worked on a couple of rich (thick) client projects where it was almost impossible to find people with both server skills and GUI skills (the market is quite good at the moment and people like me with all those skills get snapped up very quickly ). Anyway, since it is hard to find strong GUI programmers who also know how to deploy an app server and start it, it becomes desirable to be able to run the services inside the same JVM as the GUI programmer is developing in. There is then no wasted time due to EJB configurations and all the crap that comes with server development. About 18 months ago, I got around the problem by quickly implementing a clever service locator. It worked brilliantly, the only real problem being that we had a few bugs because people had developed code which worked when services were local but not when they were remote. The effort in fixing those bugs was however minimal. On my current project, we are using a proprietary framework based on Inversion of Control and Dependency Injection. Based upon its configuration, a client can call services locally or remotely too. If calling services remotely, they are invoked inside a stateless session bean which uses reflection and proxies…

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Secure Remoting with Spring and JBoss

If you are faced with having to write a rich client application in a multi-tier Java EE environment, you will typically connect to the application server over RMI. In theory, you are meant to use the servers Application Client Container and deploy your application as a client in that container. You probably won't do that though, because the client container is unfriendly for many reasons: As an example, the WebSphere 6.1 Client Container is a 200 megabyte install, Client Containers tend to be started as batch commands which set up the environment in which your application will run. If you however have an application that is meant to be started with a sexy launcher, as is the case with Eclipse RCP applications, you will struggle to get the environment created properly by the launcher, and its not supported by the vendor anyway, If you need to connect to the server securely (ie. so that serverside you have a valid security context allowing you to authorise users to call given services), then I personally have never been able to get the security callback mechanism to work. Theoretically you can tell the container to call your code at the point which it logs on to the server in order to get the credentials (eg. you can pop up a little login window), For these reasons, I have never ever used a client container in a production environment. Instead I have repeatedly gone to the trouble of getting the client environment fit so…

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OSGi – Just another fad?

In the last few weeks I have heard the term OSGi come up more and more, and one blog posting I read suggested that it was the hot topic of 2008. So I started to research a little. I am currently working heavily with the Eclipse Rich Client Platform building applications which use services deployed to IBM WebSphere. Both these platforms are built up on OSGi (the standard) and both use Eclipse Equinox (an implementation of the standard). So it must be important right? Well you don't have to read too much before you start to get the feeling that you have been there and done that before. One aim of OSGi is to provide a micro kernel for deploying and managing services. Well, from a high level, JMX (MBeans) already does that. Not enough? Well there used to be a project called Apache Avalon Phoenix, which was a mirco kernal and although that project died and was resurrected as Loom from Codehaus (which incidentally has a very interesting history of Apache and Phoenix), it is still the basis of some big projects like the Apache James mail server. Other micro kernals? How about JBoss? There is a good blog article dicussing how JBoss has been based on a micro kernel for some time now. The idea is nothing new and in fact in their case, OSGi does not really go far enough that they could be solely based on it. Actually, doesn't the Java EE EJB specification let you…

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Eclipse Help / Infocenter – External Web Application Mode

Previously in this blog, the Eclipse Help / Infocenter was discussed and details on how to set up the help for an RCP application were given. But often you want to have your help for an application online as well as part of the product, for example if the customer does not have the latest version of the product installed. Indeed the IBM and Eclipse web sites have what they call an Infocenter - an online version of their help system. In reality, when the Eclipse Help System is running, it runs as an embedded web server within your application. So in theory, it should be possible to deploy that as a standard web application. Quoting the Eclipse Help, "The help system can run in three modes: workbench (normal), infocenter, and standalone." Normal is when it is part of your application. Infocenter is when it runs as a seperate process acting as a web server. Standalone is when it is used outside of an RCP application. In fact, from Eclipse 3.4 upwards, it can also be deployed as a standard Java EE web application. The following blog shows how to deploy that help to a standard Java EE web server, namely Tomcat 5.5. Unfortunately, at the time of writing, there is no simple way to get this running. Neither is there any good tutorial showing how to overcome the pitfalls of the descriptions provided in the Eclipse 3.4 Help (search for WAR and you will get the details). Those details…

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Eclipse Help / Infocenter – Workbench Mode

Eclipse offers plugin authors the ability to add Eclipse Help to their plugins. Opening that help will give a nice window with searchable help, something like this (click on the image to see it in full size): The following blog entry shows how to integrate help into an RCP application (or indeed a plugin or feature). The first thing you need to do, is to extend your plugin.xml to tell your plugin that you want to have help. In the source view of your plugin.xml include the following extension points:      To go with these entries, you now need to add the help folder to your plugin project:      The html folder under the help folder contains simple HTML documents for each page of help that you want to write. The toc.xml file is the table of contents which defines what appears in the left pane of the help system when it is opened. The help_contexts.xml file contains mappings from "context names" to files which are relevant for that context. Contexts are used when opening context sensitive help, for example when pushing the F1 button. An example of the toc.xml follows:     <toc label="BookStore"> <topic label="Introduction" href="help/html/general/overview.html"></topic> <topic label="Starting Up" href="help/html/general/startup.html"></topic> <topic label="The Process" href="help/html/general/process.html"></topic> <topic label="Screens"> <topic label="Customers" href="help/html/views/Customers.html"></topic> <topic label="Products" href="help/html/views/Products.html"></topic> </topic> <topic label="Frequently Asked Questions" href="help/html/general/faq.html"></topic> </toc> An example of the help_contexts.xml follows:      <?xml version="1.0" encoding="UTF-8"?> <!--==================================================================== Definition of Context-Sensitive-Help (for the F1 Button) ========================================================================--> <contexts> <!--==================================================================== In the code, set the context on the control…

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GUI Performance Enhancement Strategies

Graphical User Interfaces (GUIs) tend to be event driven. A user performs an action and the GUI sends that event to any interested components through a Model-View-Controller mechanism. When the events being sent represent fine grained actions (for example a single field on a form changed, as opposed to coarse grained events like the form being submitted), the performance of the GUI can become an issue. Other examples of when performance of the GUI might become an issue are: when the model in the GUI is large, when the GUI needs to process the data a lot in preparation for displaying it (either client or server side), when the GUI is poorly implemented and duplicate listeners exist meaning that components are refreshed multiple times, unnecessarily. The following strategy has been used to help improve GUI performance. This list is ordered with the easiest / most important tasks (least effort, best improvement) at the top: ensure a clean MVC implementation, without duplicate listeners, add data caches, optimise caches (e.g. they hold more than one object graph), optimise refreshing of non-active elements. 1) Clean MVC Implementation First of all, read the MVC article on this blog. Then, using a profiler or debugger follow your controller as it fires model change events. Are any model listeners fired more than once for any reason? If they are, it is less than optimal and you need to first look for mistakes in the programming logic. If there really is a good reason that the event…

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Extreme Productivity

A year ago I was the architect of a small project (Project A) building a Client / Server application, based on Eclipse SWT/JFace/RCP, Websphere, Oracle, JMS and an Object Relation Mapping (ORM) tool, Hibernate. We were 3.5 developers on average, and we finished in 7 months. We used Feature Driven Development (FDD, similar to eXtreme Programming) as its implementation methodology. This year I worked as a lead developer on a much larger project (Project B), which I joined in its second half. The project as a whole had nearly 50 people on it at times, although our part was again an Eclipse SWT/JFace/RCP Client using a Websphere Server with Oracle and a different ORM tool, Toplink. We were 5 developers on average, finishing in 9 months. Here a kind of waterfall based methodology was used. In my spare time, I work on a tiny project, BookStore. Again an Eclipse SWT/JFace/RCP Client but not using Websphere, and instead of Oracle it uses MySQL but also with Hibernate. Its developed by just me. I do however track time spent on implementation, as well as metrics. The methodology used here is an extremely Agile one, where the documents are in the code (unless its really major, then it gets its own document), priority is given to bug fixing, then feature development, then product improvement. The aim is to be able to release a stable version at any time so that bugs can be fixed super quick. The product auto-updates from the web, to…

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