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Silverlight 4 supports relative paths for your service references, no more silly workarounds to deploy to different environments.

The relative path is based on the location of the xap file, so if you xap is located on http://www.mysite.com/ClientBin/MyApp.xap and your service is on http://www.mysite.com/Services/MyService.svc then your relative path for your entpoint address will be "../Services/MyService.svc"

Today I successfully passed exam S90.02 and with that I earned my Certified SOA Professional rank :)

The exam format is the same as S90.01, 50 questions (true/false, single choice or multiple choice questions), 1 hour to finish and the pass rate is 78. 45 minutes should be enough to answer all questions and review them a second time.

What do you need to know to pass? Basically what the title of the exam says, the concepts of the technologies behind SOA:
- WSDL, SOAP
- contracts
- XML, XML Schema
- Service roles
- REST
- ESB
- WS-* specifications

So you have to understand what they are used for and how they relate but not how to implement them.

Introduction

A service is the essential artifact in SOA, everything revolves around it, you'll be analyzing, modeling, designing, implementing, governing and versioning services. A service is a specialized piece of business logic, a piece of software that is designed by following the ideas, principles and patterns in mind that will fulfill a specific business need. Finally, some logic implemented as a web service is not automatically a (SOA) service.

Classifying services

When you're modeling and designing services you'll see that most services can be classified as a Utility, Entity or Task service:

- utility services: these are the services that don't have any real business knowledge and they are the most agnostic, this gives them the highest reuse potential. Utility services could encapsulate logging, notification,...

- entity services: these will most likely support CRUD operations on business entities such as clients and orders. Although they are working with business entities they are still very business agnostic, they don't have any knowledge of the business process that is using them. This gives them a also a high reuse potential.

- task services: they are specialized in executing a specific business task and so they have specific business knowledge and rules, this makes them less likely candidates to be reused

Modeling/designing services ...

Before you start a specific service implementation think about the big picture first and make an enterprise service blueprint. This is a high level overview of the services that will probably be needed by the enterprise. It will give you more guidance, direction, help set priorities and avoid future overlap between services.

Business is at the core of a SOA solution so everything starts by a specific business need that needs to be fulfilled. Then it's no surprise that the SOA delivery life cycle starts with the business analysis. When this is done the service modeling can start, this is to conceptualize the services that will fulfill the business need, this must be done by the business analyst and architect to keep the business and services aligned. Now comes the design fase, here the final services are chosen and get their technical design from the architect. Now the actual development of the services can start. A future article will go into more detail about the SOA delivery life cycle.

Always keep the principles and goals of SOA in your mind, are the services loosely coupled, do I have a standardize service contract, what will be the impact on the governance... Make every service as specialized and agnostic as you can, this will greatly enhance their reuse potential and avoid overlap with other services.

Service Implementations

Once your services are designed you can start implementing them. The technology that you'll be using is up to you, you're not limited by only SOAP based web services. The services can be also implemented as components or REST services. You don't necessary need to use an "open" technology, if your enterprise is completely Microsoft oriented you could use WCF over TCP with binary encoding and you would still be doing SOA.

This morning I went to take the exam S90.01 and passed without too much difficulties, 96/100 isn't that bad I guess :-)

This exam is to test your basic understanding of Service-Orientation, here is a list of the things you have to be familiar with:
- services and related stuff (contracts, inventories...)
- delivery lifecycle
- the 8 principles
- the 7 strategic goals and benefits
- the 4 characteristics

You don't need to memorize them or know every aspect of them but be familiar with the terms and understand their meaning and the relationships between them.

The exam consists of 50 questions, these can be true/false, single choice or multiple choice questions. The pass rate is 80 and you have 1 hour to finish, this is more than enough time. I went over the questions in about 30 minutes then went over them again and was completely finished after 45 minutes.

As for the study materials, basically you have enough with the book SOA: Principles of Service Design. You don't need to read the entire book but I suggest you do this anyway, compared to the other books this one is still a modest sized book and you'll need it for the other exams as well. I also bought the course materials and this is quite handy to repeat the course once you read the book, you can go through it in 1 hour to refresh your knowledge.

Hope this was useful and as always, if you have any questions just shout (but don't ask to get sample questions).