Sunday, October 25, 2009

Willy's SOA Manifesto

Yep, my own. Although it may have some shared ideas, this is not a group agreement, nor the savior of what is now known as SOA (which is what is being done so far), nor something made for others to follow. It is just what I believe, what I follow, and what I teach each time I can.

So, here it is.


1. Commons.
a. SOA is an acronym composed of the words Service Oriented Architecture, which relates to an architectural style that is based on the rules of the service metaphor.
b. A Metaphor is an application of the figure of speech concept to the IT design discipline. Using metaphors in architectural design actually refers to observing the rules of behavior of a particular entity in the business domain, and mimic them with an architectural element.
c. A Service is conceived as a cohesive (and coherent) business functionality, technologically neutral, offered through a uniform interface. A Service is a plain, homonymous metaphor of a business service.
d. For an architecture, Orientation describes the guidelines, principles and decisions that are based on the rules that govern the metaphor behavior.
e. The Architecture refers to an actual style that defines the architectural constrains, suitability and consequences of using it.

From (a) to (e) :
SOA is an architectural style whose components, constrains and principles
are driven by the service metaphor.

2. Delta
By definition, and in contra-position from some usual implementation, SOA IS NOT:
a. An Indirection Layer for interoperability.
b. A Decoration Wrap for legacy code accessibility.
c. A Component from a whole that represents one architecture instance
d. A Service Group or container of services
e. A Business Process Container.
f. A Modernization Agent
g. An Object Distribution Technology
h. An Antagonist of REST
i. A ROI salvation
j. A Way of Life, A Philosophy of Doing or a Trend (It is an architecture style!)
Corollary of (j): SOA cannot be killed, it cannot just die.
It can be suitable for a problem or not.

By definition, and in contra-position from some usual implementation, Services ARE NOT:
a. Necessarily Web Services as defined in the WSA.
b. Ways to implement RPC nor RMI.
c. Exposed Methods or Objects.
d. Defined by the process they execute
e. Necessarily Stateless (YES, they should not necessarily be Stateless).

3. Principles.
Whenever there is the opportunity when working with SOA, people should
a. Favor Business Value exposed in the business domain OVER Business Value exposed with IT domain.
b. Favor Composability OVER Integration through Interoperability, AND favor Integration through Interoperability INSTEAD of Distribution.
c. Favor Metaphor rules INSTEAD of Tool rules
d. Favor Pure Document Style INSTEAD of RPC/RMI style. (NO WRAP TRICKS ALLOWED)
e. Favor Messaging OVER Other communication options.
f. Favor Business needs OVER specific IT practices (like optimization or flexibility)
g. Favor Entity documents OVER commanding documents
h. Favor Versionable documents OVER Structurally static documents.

So it is written.

William Martinez Pomares

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