Hello,
I am at the architecture/design stages of building a large/complex
enterprise system that will be operated over a distributed (multi-site/WAN)
environment, which will be composed of numerous components with a resulting
complex dependency matrix. To over simplify the description of the system,
it will be composed of numerous reusable services and interconnected
enterprise and web applications. To make management a bit more complicated,
our team will be running this system on at least three segregated networks.
All this makes me mindful of the maintenance and deploy/runtime management
(provisioning, configuration, deployment, runtime-configuration)
implications. I've already decomposed my system, and I know generally how I
want it to behave, but at this scale, I'm finding that traditional EE
architecture (n-tier) and management techniques (GF admin console, etc) just
doesn't seem like it will be enough.
In steps OSGi+EE hybrid applications.
I've been following these developments for quite some time on Mr. Gupta's (
http://www.java.net/blog/6125) and Mr. Sahoos (
http://www.java.net/blog/111589) blogs, played with implementing Felix,
converting some of my services to OSGi services that comply with core,
compendium, or enterprise service APIs. Good times. Last night I
implemented a simple hybrid application based on a recent screencast (
http://blogs.sun.com/arungupta/entry/screencast_32_osgi_enabled_java), which
was easy enough (BTW, well done GF team). GFv3 really provides some great
facilities for OSGi bundle management. With all this good stuff, though, I
have hesitations implementing my application in this hybrid manner.
While GF is my application server of choice for both development and
production, I can't assume my management/customers will feel the same way
for all time into eternity. In its current state, hybrid applications are
proprietary (I believe it was Arun who admitted this in the screencast),
which certainly kills vendor neutrality. In addition to this, I can't help
but feel that the way of going about packaging and deploying the hybrid
application is a bit off from what I would like to see. Rather than
building a bundle that depends on a service API (for example, a bundle that
defines the web container or the EJB 3.1 container API), I am modifying my
bundle (added manifest properties) to run in the GF environment. While this
isn't necessarily bad, especially since the OSGi spec says this is OK, I
can't help but get the feeling that this scenario goes against the spirit of
the OSGi. I believe this may be a result of the H2 kernel running on top of
the OSGi container, rather than itself being services used by an OSGi
container, which is understandable, but it gives me hesitance because it
tells me that there is no future hope for vendor neutrality down this path
(since the H2 kernel isn't used by other vendors such as JBoss, etc). What
I would like to see (I believe) is the ability for me to make an ejb
module/web archieve/enterprise application, provide the OSGi-specific
classes I want (ServiceTracker, etc) and simply deploy it to an OSGi
container and allow me to pick/choose my service implementations for the web
container/ejb container, etc.
As far as my questions go....is there anyone out there that is implementing
(or seriously considering implementing, as I am) hybrid EE6/OSGi
applications in production? Does anyone have any thoughts on my views on
the vendor neutrality aspect...or generally how the hybrid application is
put together?
Thanks,
Steve