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Introduction
    Overview
    Service Inventory Blueprints
    Service-Oriented Analysis
    Service-Oriented Design

Service Models
    Service Layers
    Entity Services
    Task Services
    Utility Services

Delivery Processes
    Top Down vs. Bottom Up
    The Inventory Analysis
Cycle (Part I)
    The Inventory Analysis
Cycle (Part II)
    The Inventory Analysis
Cycle (Part III)
    Choosing a Delivery Strategy

The Service-Oriented
Analysis Process
    Process Overview
    Information Gathering Steps
    Service Modeling Process (Part I)
    Service Modeling Process (Part II)

Service-Oriented
Design Processes
    Process Overview
    Design Processes and
Service Models
    Design Processes and Service-Orientation

Additional Resources
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    Consulting


The Service-Oriented Analysis Process

Service Modeling Process (Part II)

The iterative nature of the aforementioned inventory analysis allows for service candidates to be repeatedly revised and refined prior to the creation of corresponding services.

The service modeling steps displayed in the previous figure are explained in detail in "Service-Oriented Architecture: Concepts, Technology, and Design." In a nutshell, a business process definition is decomposed (Step 1) into its most detailed representation, resulting in a series of granular actions. Those suitable for service encapsulation become potential service capability candidates (Step 2).

The service logic of each capability candidate is assessed in terms of whether it is specific or agnostic to the current business process. Agnostic capability candidates are grouped into agnostic service candidates usually based on entity and utility service models (Step 3), whereas non-agnostic capability candidates are placed into a task service candidate with a functional scope usually equivalent to the business process (Step 4).

During subsequent iterations of this process, the chances of identifying already defined capability candidates increase. Therefore, a separate discovery step (not shown) is added to ensure that no redundant capability or service candidates are introduced into the blueprint. Also select service-orientation principles are applied to shape modeled service candidates in preparation for their eventual designs (Step 5).

The following three service-orientation principles are typically applied during the service modeling process:

• Service Reusability

• Service Autonomy

• Service Discoverability

After the initial set of service candidates is established, a candidate composition is assembled and subjected to possible runtime scenarios (Step 6). Subsequently, each of the identified service capability candidates is further studied to explore any additional processing requirements that may be needed to carry out its functionality. This kicks off the second half of the service modeling process (Steps 7–12) during which additional utility service capability candidates are generally defined. The process ends with an extended composition candidate modeling step and a final revision of all capability and service candidate definitions created so far.

This page contains excerpts from:

SOA Principles of Service Design
by Thomas Erl

(ISBN: 0132344823, Prentice Hall/PearsonPTR, Hardcover,
240+ Full Color Illustrations, 573 pages)

Free Color Poster (see www.soaposters.com).
For more information about this book, visit
www.soabooks.com/psd/.
The Prentice Hall Service-Oriented Computing Series from Thomas Erl
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