Documentum Development: Past, Present and Future

 

The Past

Using DAB the mode de jour was to develop against a Docbase; live, connected, whatever you want to call it.  You nominated a "System of Record" Docbase.  You then went about the business of defining all the artifacts; types, lifecycles, workflows, relations and so on and so forth, that collectively made up your Docapp (a DOCbase APPlication).

Your application(s) code would never execute against these particular artifacts, in this particular Docbase; because they really were just the definitions of resources that your application requires to be present in a production Docbase in order to run correctly. Meanwhile, the rest of your application artifacts; java classes, servlets & jsps, XML, etc, were all managed out of a source control system.

To prepare a content-rich application for distribution. Release engineering (releng) would checkout all the application artifacts, build and package them as an installer or as a war or an ear.  They would then also export the associated Docapp as a Docapp Archive and place with the application package.  These resources were then placed on a download site where customers could find them.

To install the application the customer would use the installer or deploy the war or ear. He would then use DAI to install the docapp archive into one or more production Docbases.

So, that is how it was.  The System of Record for your source artifacts was the Docbase itself.  But what was so wrong with that I hear some of your ask?  Well a few things as it happens:-

1. Having different Systems of Record is just plain wrong, and what made us so special anyway?
2. Versioning semantics for Docbase artifacts is not always the same as they are for source control, complicating development, histories, labelling and snapshoting
3. Releng needed to have and to know Docbases and to construct Docbases processes (not all of which were that automatable) which was hugely burdensome for them

With reference to the versioning semantics.  It is important for us all to recognize that the Docbase is just plain bad at development versioning.  For example, types in a Docbase cannot be versioned but code certainly depends on particular versions of types.  Now if we could have reliably versioned artifacts then we can support explicit versioned dependencies, even when the target environment does not support it. Explicit versioned dependencies allow us to bind code to specific versions of Docbase resources and have those dependencies validated.  The upsides of reliable versioning are hopefully evident.

The Present

Recognizing that content management would soon standardize through efforts like CMIS.  Recognizing that this would foster and entire industry of organizations building content-rich applications we knew we would have to address these shortcomings and move more mainstream.

So we built Composer and a system of linked XML-based artifacts and an install process that can transform these XML-based artifacts into Docbase objects, preserving the links by converting them to Docbase links; i.e. OIDs.

No longer is there a need for a "System of Record" Docbase.  Docbase artifacts can now be developed in the same eclipse IDE right alongside all your other application artifacts.  They can also be managed out of the same source control system, giving us reliable version semantics and greatly simplifying the releng process.

The Future

OK so we have ironed out that little wrinkle.  Docbase artifacts are now analogous to other source artifacts and therefore we are all now followers of the same development model.   In this respect we’ve become a bit more standard and hopefully removed a big barrier to entry for release engineering departments.  We believe this will help promote EMC|Documentum as the platform for developing content-rich applications.

So what’s next?

In a word "OSGi".

A phenomenon is sweeping the java community in the form of OSGi, a dynamic module system for Java. Most application servers are OSGi-based already.  And this phenomenon will undoubtedly impact the ECM community too. 

OSGi is mature.  It is over 10 years old and has grown out of embedded systems world.  So this is not new technology by any stretch.  It may just be new to some of us.  It is also standards-based. 

OSGi promotes a world of modules (bundles in their parlance) that can be dynamically inserted (or removed) into any live, running system with no interruptions in the services it provides.  Each bundle has versioned dependencies that the system will honour and enforce these.  And a system can support multiple versions of a module at any one time.

For all these reasons (and many others) I believe that OSGi is the perfect fundamental building block for next generation ECM solutions and solution frameworks.

It is also very important to recognize that in this future world of solutions and solution frameworks we may well also see direct, application hosted, manipulation of our XML systems of record.  As well as continuing to support the more traditional offline development model, both will co-exist quite happily side-by-side.  This direct manipulation will be supported by a family of web-based tooling built on the central core of the Composer tooling platform.

But this is still a little way in the future.  Because OSGi will effect how applications are delivered the most noticeable change you will see in the short-term will be to our friend the dar (Documentum Archive) which I believe is already set to become an OSGi bundle.  This will prepare the way for it to be just like every other piece of the solution.  Developed the same way, delivered the same way.  Depended upon, dependent upon others.  Really binding into the application as the vital constituent part that it really is. 

Conclusions

So what conclusions should you draw from this? 

Well if you are considering developing a content rich application (or larger) on Documentum then you need to be following Composer’s lead and adopting model-driven development.  Making XML models a central tenet of your development practices is the right thing to do.  Leverage Composer, the tooling platform, and in particular its EMF-based modelling and your not going to go too far wrong. 

Also getting more involved in Composer, the tooling platform, by extending it for your purposes by adding your own Docbase artifacts would be an excellent way to introduce yourself to the wonderful world of OSGi.

Happy Composing

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