Contract-First Approach Still

There’s one thing I want to mention about my last post on contract-first methodology.
In service inventory, Entity Services layers might be generated by a tool, as opposite to the goodness about write the contract by hand.

Last century, when I other web developers endeavors were working with JavaScript/HTML, we could notice how different code was depending on the handcraft’s origins (notepad or other advanced tools for that time).

Companies already have their system and database models. Moving to SOA is a strategy that could take years . Advantage from tools could be taken if we do generate contract from database tables and thereafter, and also generate services and users interfaces from those very contracts. For all those legacy work, this approach should be nice.

What a hell, man? You may ask now.

One thing which intrigues me is runtime coupling between objects. When using WCF to generate contracts for your services and the visual studio solution might have many services within. Of course you may want to reuse some comportment instead of creating them when you are build service compositions. But, if you need to change those objects (or contract), you will realize a horrible buildtime coupling problems and you may need to upgrade all consumer contracts instead of just release another WSDL contract version at you service.

Again, balance the situation is good. SOA has to be intrinsically with the financial economies. If the company is already established in its industry and need more power, SOA is a mandatory tool. If the company still about to grow, SOA is an option that the advantages and slows might incommodities.

Bouncing puppies for WSDL Contract First Approach

Ohh.. Bloody hell!! Contract First Approach or Not?  What about the common sense of proved advantages and what to do when we have infinite services to create and loads of business domains to take care of?

Lets take Tomas Erls books’s approach into account by imagining the following scenario:

- 50 Business Entity (which would compose something like 35 Entity Services)
- 5 Business Process (which would compose something like 10 Task Services and 10 Utility Services.

Have a look here and here and reflect about the scenario I’ve shown. To much code indeed and space for human mistakes. What about the work to convert WSDL into client and server code as shown here. That’s not simple, isn’t it?

Migration to a SOA ecosystem needs some sort Model Driven development and deal with contract-to-technology coupling if we want to things more quickly. We still need model and plan accordingly but we shouldn’t take so much time to write one or two service compositions. I know about SOA vendor option but in the first moment can be a good idea to trust a technology plataform.

Thus, I believe:

If we are within the boundaries of the enterprise or/and the services are not requested by many consumers, we may not need the contract-first approach but still need to care about governance.
if we need to communicate outside the boundaries of the enterprise, we need to do Contract-First approach so we can make sure we ‘re experience the partner experience in communication with us.

Thereafter, go with velocity!!