You’ve definitely heard about
Xtext, the famous text modeling framework,
community award winner . We are all looking forward to the new project management wonder: the
release of Helios, upcoming on June the 23rd, which will include Xtext 1.0.0. In this article, I want do describe some aspects of integration of Xtext-based languages into IDE.
Read the rest of this entry »
Yesterday, I discovered a funny nuance in Java programming language, which I didn’t know before and decided to share it with you. I was designing an API for transport of changes in relationships between two DTO types. Since I wanted to support batch changes, I created the class for carrying these:
class ManyToManyDelta<S extends BaseDto<?>, T extends BaseDto<?>> {
List<SimpleRelationship<S,T>> relationshipsToAdd;
List<SimpleRelationship<S,T>> relationshipsToRemove;
...
}
class SimpleRelationship<V extends BaseDto<?>, W extends BaseDto<?>> {
// BaseDto classes are identified by the parameterized Id
Id<V> left;
Id<W> right;
SimpleRelationship(BaseDto<V> one, BaseDto<W> another) {
left = one.getId();
right = another.getId();
}
}
Having this structure, you can model the relationship between two instances of types A and B by an instance of SimpleRelationship<A>. If you want to communicate the creation of a relationship you would put the latter into the relatioshipToAdd list, if you want to model the deletion, you would put it into the relatioshipToRemove list.
Now I it was time to develop methods for access of the relationship lists inside of the ManyToManyDelta:
class ManyToManyDelta<S extends BaseDto<?>, T extends BaseDto<?>> {
...
public void add(SimpleRelationship<S, T> toAdd) {
if (toAdd == null) { /* react */}
this.relatioshipToAdd.add(toAdd);
}
...
}
You could think that you have a batch update (e.g. an Array or List) of SimpleRelatioship objects you would like to add them by one invocation instead of a series of invocation. e.G:
class ManyToManyDelta<S extends BaseDto<?>, T extends BaseDto<?>> {
...
public void add(SimpleRelationship<S, T>[] toAdd) {
if (toAdd == null) { /* react */}
this.relatioshipToAdd.addAll(Arrays.asList(toAdd));
}
public void add(SimpleRelationship<S, T> toAdd) {
if (toAdd == null) { /* react */}
this.relatioshipToAdd.add(toAdd);
}
...
}
Using the varargs feature of Java you could also write equivalent:
class ManyToManyDelta<S extends BaseDto<?>, T extends BaseDto<?>> {
...
public void add(SimpleRelationship<S, T>... toAdd) {
if (toAdd == null) { /* react */}
this.relatioshipToAdd.addAll(Arrays.asList(toAdd));
}
...
}
That would be nice, right? By the way, it is a good idea, to write some client code, during the development of API. This discovers potential problems:
... A entityA = ...; B entityB = ...; ManyToManyDelta<A, B> delta = new ManyToManyDelta<A,B>(); delta.add(new SimpleRelationship<A,B>(entityA, entityB));
Coding this result in a type safety warning: A generic array of SimpleRelationship is created for a varargs parameter. Which reveals a problem in a Java language: you can not create an array of parameterized types. And resulting from this fact, you can not use that as varargs argument.
Finally, if you want to create convenience methods for one and many items, you have to do it in a old-fashined way, by providing overloaded methods.
The JavaServer Faces (JSF) 2.0 is the newest Java presentation technology that is covered in JSR-314 and was publicly released on July 01, 2009. It became a part of the JEE6 standard and can be comfortably used in conjunction with other JEE frameworks, with Spring or just on its own. This article reveals the possible scenarios and shows the required configuration for the usage of JSF 2.0 with EJB 3.1 and with Spring 3.0. It also discusses several auxilary technologies which can be used along with JSF 2.0. Read the rest of this entry »
The Eclipse RCP became a prominent platform for building client software. One of the delivery mechanisms supported by Eclipse RCP is Sun’s Java Web Start (JWS). Since Galileo Edition some changes has been introduced in the platform. This article provides some hints for creation of the RCP delivered by Java Web Start.
In order to package the RCP I suggest to use feature-based products as described in a previous article. Following it, you should have a top-level plug-in (also refered as product-defining plug-in) and top-level feature, which is called “wrap”-feature in the context of the Java Web Start.
Before you start with Java Web Start (JWS), export the product and make sure it starts as a standalone application. In doing so, you have to ensure that your references to the plug-ins are correct. One of the way of doing it is to hit the Validate button in the top left of the product editor. 
If the validation is successful, try to export the product. The PDE builder will run and create a distribution. The errors of the compiler/builder/assembler, if any, are reported to files zipped to the logs.zip file in the distribution directory.
I just returned from the furious event given by Adam Bien on
Real World Java EE Practices. The presentation has been held in Lehmanns Bookstore in Hamburg in co-operation with the JUGHH. It was a full success with no space left in the bookstore. I think, I got the last seat and there were some people standing.
Adam made it in an hour and presented many interesting topics. He started with new subjects introduces in JEE6, like optional local interfaces, cronjob-like Timer Service and other nice goodies. Then he covered new stuff from JEE like REST and CDI (Context and Dependency Injection). Finally, he moved to the best practices, patterns and anti-pattern. As usual, it was quick and precise – Adam answered many questions and gave a good overview of the technology.
After the presentation, JUGHH / Lehmanns offer a glass of sparkling wine for the smaller audience and Adam spoke about the possibility to speak about JavaFX next time. This time I left my camera at home and only had my phone with me, so sorry for the low-resolutioned picture…
AbstractAbout two years ago, I published an article about Exposing the Functionality implemented in Stateless Session Beans (EJB 2.1) using Web Services. J2EE 1.4 times are over and the new version of the Java Enterprise framework, called Java Enterprise Edition 5 (JavaEE 5, or simply JEE) has emerged. In this article the same business scenario is repeated in the new framework.
Before we dive into code examples, some software is required. The good news about the software is, that it also evolved over time. Here is what we use:
Accessing a relational database system from Java is a basic step required for many applications. The JEE architecture defines a standard for gaining this access, calls Java Connector Architecture (JCA). This article is a short HOWTO of configuring JCA-compliant datasource to a Firebird 2.x RDBMs using JBoss AS 5.1.0 as example. This tutorial is based on a Windows installation, but can be easily ported to Linux, or other OS.
For the configuration of the datasource two steps are required:
jaybird-*.rar)firebird-ds.xml configuration
An event of
annual series of Eclipse Demo Camps is taking place in Hamburg again. The event was planned in November, but takes actually place in December. As usually
Peter and
Martinare responsible for the organization. To make it short:
If you want to attend, make sure you find a minute to write you name down in EclipseWiki. I suppose these kind of events is well-known. If you never heard of that – look at the interesting topics and the attendee list of more than one hundred people. You will have the opportunity to listen to the talks, to speak with interesting people and get some news from Eclipse Commiters and Users. In the end you usually get some food and bevereges, to make the atmosphere a little more relaxed. If you never been there it is worth to visit…
Even if some time has passed since the events EWiTa 2009 and Eclipse Summit Europe 2009, I would like to share my impressions, since I took part in both events…
EWiTa 2009 stands for Elmshorner Wirtschaftsinfromatiktag, that is German for “Elmshorn Business Information Systems Day”. The event has been organized by Frank Zimmermann, of
Nordakademie – a private university in Northern Germany. Even if the event is not an official sequel of the
MDSD Today, there were many similarities. The event had two tracks: the process modeling track and the MDSD track. After an excellent keynote from Mathias Weske about the importance of collaboration during the process of (business) modeling I stayed in the business track to listen to the Andrea Grass (
oose GmbH) on the combination of UML and BPMN 2.0. To say the truth, I’m not a big fan of this approach, especially, because the conceptual mismatch of modeling of business behavior and technical behavior. After a coffee break I enjoyed an excellent talk of
itemis), reporting about the success story of xText in a big project of Deutsche Börse AG (German Stock Exchange).
After a small lunch, I was listening to two Arcando consultants reporting about their eTicketing project. The strange thing about this talk was that they just made some ads on a standard Microsoft product. After this, I enjoyed an interesting talk on business modeling based on CobIT process. Finally, I switched the track again to MDSD and listend to the an interesting usage of MDSD techniques for generation of DynPro and ABAP code.
In general I enjoyed the event. I think the MDSD track was a little more technical, but the combination was good.
The Eclipse Summit Europe 2009 (ESE 2009) took place on October 27-29 in Ludwigsburg, Germany, it is the European complement to the EclipseCon in the US. In contrast to the spring event in Santa Clara, CA, the ESE is an autumn event in a beautiful baroque town near Stuttgart. The event lasted three days and is a must for Eclipse-related technology people. As usual, the venue was great, the keynotes excellent and the talks interesting. And of course it was the place to meet the committers, evangelists, see them in action, talk to them and discuss the future directions.
The first day is an arrival day. People arrive during the day, some of them are already there. I was visiting the Modeling Track the whole day and had much fun with Ed Merks, Eike Stepper and Thomas Schindl in the morning. Later, in the Modeling Symposium, Eike showed the eDine RCP based on CDO, UBS envisioned the modeling tool pipeline and so on, and so on. About 10 people showed different technologies on and about modeling. Intersting, unstructured and relaxed. And of course, the first evening is the opportunity to speak with all the Eclipse VIPs and drink a cold beer.
The main conference day was Wednesday and it started with a great keynote on functional programming held by Don Syme, the father of F#. Suprisingly, the talk was about F#. For some of us, there was not enough functional beauty exposed in the talk, so I scheduled a private session with Don and he told
Markus Voelter,
Heiko Behrens and
me about some interesting F# features.
I took part in the How about I/O session on JPicus. A very interesting tool for tracking I/O problems in Java programs developed by SAP. The Climb The Tower of Babel was about the Eclipse translation project. Intersting is the runtime editor allowing you to translate you runnig application. After a delicios lunch, I enjoyed two modeling talks: Xtext and EMF Query. The itemis team introduced some really new features, which make Xtext in my oppinion to a unique technology. Just to mention few of them: white-space aware parsing, usage of scopes and qualified names, usage of index (construted by a builder) in your own language, separation of markers and annotations in the editor, integration of the generator on-save, declarative quick-fix in your DSL, strings with special meaning, references to java types, and much more… The EMF Query is a project developed by the SAP team, that leverages the index by a query language. The language is a SQL-like DSL for querying the EMF-based models. The infrastructure is very intersting and allows complex scenarios with multiple model providers – very technical, and I believe, very interesting project.
After the keynote on the importance of software ecosystems and a deep economical analysis of Eclipse ecosystem, I switched off the track to be able to prepare
my talk. I was reporting about the IDE for TLA+ which I was building the last nine month at Microsoft Research, and which will be
available soon. The main emphasis of the talk, was not the demo of the IDE, but the exchange of experiences on building one. Especially, I focused on the possible pitfalls and conceptual mismatches of IDEs depending on the integrated language. The slides will be available soon.
At the end, I enjoyed the event very much. I even liked it more than EclipseCon. Modeling still seems to be the most interesting part of Eclipse ecosystem. Technologies like Xtext and CDO gain maturity, new technolgoes like EMF Query are being developed. It was nice to see the people again… As usual, some pictures:
After
providing the basic example of how the Eclipse Common Navigator Framework (CNF) can be used to display custom content, this article focuses on the main feature of the CNF – the contribution of content to the same navigator by several independent plug-ins. First of all, I will explain some minor changes introduced to the CNF in the Gallileo Edition, then I will focus on the content itself and finally provide an overview of how the action contributions can be provided. In the end of the post, some ideas on control of dynamic content are explained.
There are two noticeable changes in the CNF that have been added with Eclipse Galileo. The return type of the method Read the rest of this entry »
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