Eclipse

53 posts

Development for and with Eclipse

Package Drone 0.0.3

There is a new version of package drone – 0.0.3!

See the release notes on github for Version 0.0.3

Beside a lot new features, which are described in the release notes, the two most interesting topics are:

Two working workflows

Now depending on the channel configuration it is now possible to run channels either for Maven Tycho or by manually uploading artifacts. The output always can be consumed as P2 repository.

With Maven Tycho the P2 metadata created by Tycho gets uploaded and used by the P2 adapter to create the P2 repository data.

In plain OSGi mode Package Drone extracts the dependency information directly from the uploaded artifacts and uses it in order to create virtual P2 meta data file. In both cases the P2 adapter uses the same way to construct the final repository.

For the plain OSGi mode it is also possible to create a generated P2 feature artifact. For this a new instance of a generated P2 feature is created, the meta data like Feature ID, version, etc are manually provided, and package drone will add all bundles in the channel to the feature automatically, so that there always is a feature available for plain OSGi bundles.

The plain OSGi mode is extremely interesting if you need to consume OSGi bundles which are hosted on Maven Central, but have no P2 repository available.

Which hopefully will also be one of the next features in package drone, a replicated artifacts, from Maven Central (or any other Maven 2 repository).

The replacement of spring

I started with Spring WebMVC in order to have an easy start. The idea always was to have a OSGi style, modular application. And Spring simply can provide the base for that. While Spring might be a nice framework for monolithic web applications, it simply is not modular enough for OSGi. Yes, you head right, Spring is not modular enough. First of all, Spring cannot be brought into the OSGi environment, working between bundles. Having one bundle with all and everything inside is ok. But splitting it up seems impossible.

In the past there was Spring Dynamic Modules (Spring DM), which changed to Eclipse Virgo now. However Spring DM is dead and Eclipse Virgo seems only provides part of what you need, and almost nothing when it comes to the web.

So the solution was to write a small web dispatching layer, use the idea of Spring’s @Controller mechanism and use real OSGi. Controllers now get registered as OSGi service, once they have all their dependencies met. A central dispatcher servlet provides access to all controllers, no matter which bundle registers them. Once the service is gone, the controller is removed. By having real dynamic services it is easily possible to add new functionality, menu entries, resources during runtime, running in the same web context. Install and update plugins, perform a simple setup, things that every PHP web application can do.

Of course the downside is, that part of Spring’s functionality gets replicated, but it simply was to much trouble to split off parts of Spring WebMVC.

Releasing “Package Drone” 0.0.1

A package repository for Maven Tycho, OSGi and all the rest.

Itch: I want to have a software repository where Maven Tycho can deploy to and P2 can read from. Also I would like to re-use this repository as an OBR or OSGi R5 repository, and possibly as Maven repository.

Scratch: Package Drone, version 0.0.1

Now there already is the Nexus Repository and the Nexus Unzip Plugin. However this essentially uploads a full P2 repository ZIP file and uses Nexus as a plain web server, hosting that zipped P2 repository.

Instead I would like to not only have a P2 repository, but also an OSGi R5 repository, based on the same OSGi bundles uploaded. I would also like to upload bundles created by the Maven Bundle Plugin, or BNDtools. Also would I like to make a full, Maven like, release using Tycho and later host this as a Maven 2 repository. Now package drone is not quite there yet, but the basic Tycho Deploy -> P2 Consume workflow already works to some degree.

Package Drone is hosted on github and there is a small readme and wiki.

Be warned, this is alpha quality software. If it works for you, fine. If not please help me fix it!

OSGi EE – Modular Web Applications

Creating a modular web application in Java still is a tricky task. While there has been some improvement with web fragments, this still is far away from what you actually want.

But what is it that you (or better I) want:

  • Modularity – Make the application extensible using plugins. Not just one big block. Install additional functionality with a few clicks
  • Easy setup – Setting up a JEE server like JBoss can be a pain in the ass. First you have to configure your datasource with some obscure XML file. It would be way better to be directed to some sort of setup screen, asking for all database (etc.) information first. Guiding you through a setup process. With JEE your web application won’t even start if your JPA data source cannot be loaded since the driver is not specified.

Now there are a lot of applications which provide this flexibility. Atlassian, Jenkins, and a few more, all do a great job. Most PHP web applications guide you through a web setup when you first install the software. So why can’t Java do this out of the box?

When you think of modularity and services, OSGi immediately comes into my mind. However “the Web” still is a strange place for OSGi setups. Yes you can register a servlet with OSGi and access it through “http”. But that is just the start. You want JSP, Form Validation, maybe even Spring WebMVC.

There are a few setups I stumbled over, pax runner with pax web. However they bring in a pretty old jetty 7, when there is jetty 9.2.x with Servlet 3.1 support. There are some Apache Karaf tutorials, however there is also no JSP support, just a custom Vaadin bridge.

Jetty 9.2.x claims to have OSGi support out of the box. In combination with Eclipse Equinox this should be an easy setup. And although it really works, you know what you have to do. I got it working in the Eclipse IDE, but it still provides most things you really want.

In order to be able to reproduce it myself, I made a few ant script and sample projects out of what I learned and decided to put them up on github.

So if you want to build modular web applications with Jetty, Equinox, Eclipse, Hibernate Validation, Spring WebMV and more (with a recent version of all components) you can have a look at https://github.com/ctron/osgiee.

If you have more examples working or find a bug, please let me know ;-)

Fixing the theming issue with Eclipse RCP applications in E4

It seems that migrating from Eclipse RCP 3.x to E4 (Eclipse 4.x) is not a quick win. If you already have an RCP based application the switch to E4 turns out to be a real problem. As is the E4 way if you want some sort of “custom” application that features some IDE components (like a perspective switcher or about dialog). It seems a bit strange that the migration from 3 to 4 is such a bumpy ride. Although there a are lots of tutorials, they mostly only scratch the surface of the task to convert a full blown RCP application. But this should be a rant on E4, I hope that the next releases improve that situation a lot.

When I migrated our RCP Application (OSTC from openSCADA) to E4 using the RCP bundle of E4. This seems not to be a real E4 application, but allows one to run a legacy, 3.x, application inside the new E4 environment. A quick it-just-works migration, still you miss all the E4 fun. But at the first start the user interface looked up bit garbled up. Some black line drawing artifacts. The tabs where a bit “dull” compared to the facy new tabs in E4.

The solution was pretty simple, the final RCP application was missing the bundle “org.eclipse.platform” which contained the themes and the necessary resources.

Fixing the Mint-X theme for Eclipse/SWT

If you are running Mint, Eclipse and you like the Mint-X theme, you might be a bit frustrated every time you open up Eclipse. Especially with Eclipse 4.2 the design of the toolbars is pretty messed up. See the launchpad bug entry: https://bugs.launchpad.net/linuxmint/+bug/1168281

eclipse1

Gladly this is only a minor glitch which can be fixed easily. Hopefully the change of the github pull request will find its way into Mint.

Access to WMI in Java using Eclipse SWT OLE integration

Today I ran into a problem which could easily solved using a short WMI query. The problem was that the query must be executed within a Java UI application. Googling for a solution I came only up with either quite some ugly workarounds (like generating a VBScript fragment, forking off the VBScript runtime and parsing the result) or some full blown COM/DCOM interfaces (like J-Integra or J-Interop). Although I really like J-Interop (we are using it for DCOM when accessing OPC server in OpenSCADA Utgard) it has some drawbacks. For J-Interop every access (even local access) is a network based access. Since J-Interop only supports DCOM it is free of any platform specific code but required the machine to be accessible using “remoting” functionality (DCOM). Since I wanted to query the WMI from a UI application and I am sure that the WMI query will stay on the Win32 version of the application I was not keen on adding “remoting” as a requirement to the UI application.

After some digging I remembered that SWT brings an OLE interface which provides direct COM access. So I started poking around and finally come up with a solution that works quite well.

For the impatient: The full source code is available from github https://github.com/ctron/wmisample and the screenshot is here.

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Eclipse Install Issue

I just stumbled over a strange issue when installing an additional plugin into a fresh Eclipse installation:
An error occurred while collecting items to be installed
session context was:(profile=SDKProfile, phase=org.eclipse.equinox.internal.p2.engine.phases.Collect, operand=, action=).
No repository found containing: osgi.bundle,org.eclipse.team.cvs.ssh,3.2.100.I20090508-2000

I was unable to add any new plugin and searching Google for help was not successfull. There was an issue somewhere in the Eclipse Bugzilla that the plugin org.eclipse.team.cvs.ssh was optional and no longer installed or required. Seems that P2 thinks the somewhat required for the installation process.

ButI found one hint that deactivating the option “Contact all update sites during install to find required software” helps. And it did.

Screenshot of Eclipse Dialog