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javapluginsosgienterprise
black sensei
black sensei

Reputation: 6678

Questions about Spring DM,OSGi and web application

I've started looking at osgi with the main purpose to achieve the task ahead of me. Basically i would be able to distribute an web based application and build specific features of the whole web app separately in such a way that i can deploy at A my web app with features a,b,c and deploy at B with features a,c,d.

A little like how one can install plugin in joomla. So for example when i want to add a different aspect of the web application, i would build a small war with all the html and its admin section and have this feature admin section available in the main admin panel.

Second question is about Spring DM. most likely i will be using Spring and it seem logical i see what Spring DM has to offer.After downloading Spring DM .1.2.1 i found out that its lib folder contains spring jars for version 2.5.6.SEC01 but i planned on using 3.1.2 so am a little confuse as how everything will play nice together.

Thanks for reading

Upvotes: 1

Views: 493

Answers (2)

chad
chad

Reputation: 7519

I'm not sure you need to be considering OSGi, at least not directly, to achieve your state requirements. You said:

Basically i would be able to distribute an web based application and build specific features of the whole web app separately in such a way that i can deploy at A my web app with features a,b,c and deploy at B with features a,c,d.

If these are youre requirements, then you don't actually need to concern yourself with OSGi directly, but rather find a web app framework that supports modular extensions. Which most likely means that the framework itself uses OSGi. I'm not familiar with Spring, but I do know that Struts 2 ( a comparable web app framework ) has an OSGi based plugin meant to achieve your use case.

On the other hand, if your idea is to play with OSGi, then I suggest you pick a lower level task, such as writing a web application framework, rather than a web app itself.

Upvotes: 0

Peter Kriens
Peter Kriens

Reputation: 15372

I've just been doing such an exercise so I can shed some light how you do it without the overhead of Spring. I've made a clear division: all application code is in the browser, all data handling is in the server. With HTML5 the browser has grown up to an impressive, portable, and powerful application environment. One has multiprocessing, messaging, modularity, and amazing visuals. I am using angularjs as the framework in the browser.

Angular works with a central routing table mapping the hash part of the page url to "modules" in Javascript. This makes it very easy to define what modules are part of the application. The server can easily control this part.

On the server side I have bundles that carry the Javascript code, the html fragments and the data handling. I based this on the OSGi Http Server model since it is more flexible. However, I added proper support for static resources in bundles: caching, streaming, ranges, etc.

In the server I used DS and bndtools to develop the bundles. This is an impressive development experience since it works like Smalltalk. You change and it is immediately reflected in the server. Adding bundles, removing bundles, the server keeps on running. Server restarts are rare during development.

The disadvantage is that there are unfortunately very few components that leverage OSGi. Most components, with Spring being the archetypical example, rely heavily on class loading hacks to wire applications from a central point. This is fundamentally not modular. For this reason I had to develop many highly cohesive and uncoupled components that leverage the OSGi service model. Once I get time I will donate them to an open source project.

Upvotes: 4

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