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Service Oriented
Architecture
Vinod Wilson – Architect – Crestron Electronics
SOA Fundamentals
INTRODUCTION TO SERVICE-ORIENTATION
Three individuals, each capable of providing a distinct
service.
A company that employs these
three people can compose their
capabilities to carry out its
business.
INTRODUCTION TO SERVICE-ORIENTATION
• Even though each individual contributes a distinct service, for the
company to function effectively, its staff also needs to have
fundamental, common characteristics, such as availability, reliability,
and the ability to communicate using the same language
Services in Business Automation
Service with
Invoice Service
contract
Service with
Invoice Service
contract as REST
Services Are Collections of Capabilities
• When discussing services, it is important to remember that a single
service can offer an API that provides a collection of capabilities.
• They are grouped together because they relate to a functional
context established by the service.
Service-Orientation as a Design Paradigm
• Fundamentally, service-orientation shapes suitable units of solution
logic as enterprise resources that can be designed to solve immediate
concerns while still remaining agnostic to the greater problem.
• This provides the constant opportunity to reutilize the capabilities
within those units to solve other problems as well.
SOA terms
• Service composition
• A service composition is a coordinated aggregate of services
• Service inventory
• A service inventory is an independently standardized and governed collection
of complementary services within a boundary that represents an enterprise
or a meaningful segment of an enterprise
• Domain service inventory
• When an organization has multiple service inventories, this term is further
qualified as domain service inventory
SOA terms
A collection of standardized services can form the basis of
a service inventory that can be independently governed
within its own physical deployment environment.
Service-Orientation Design Principles
• Standardized Service Contract (291)
• Services within the same service inventory are in compliance with the same contract design standards.
• Service Loose Coupling (293)
• Service contracts impose low consumer coupling requirements and are themselves decoupled from their surrounding environment
• Service Abstraction (294)
• Service contracts only contain essential information and information about services is limited to what is published in service contracts.
• Service Reusability (295)
• Services contain and express agnostic logic and can be positioned as reusable enterprise resources.
• Service Autonomy (297)
• Services exercise a high level of control over their underlying runtime execution environment.
• Service Statelessness (298)
• Services minimize resource consumption by deferring the management of state information when necessary.
• Service Discoverability (300)
• Services are supplemented with communicative metadata by which they can be effectively discovered and interpreted.
• Service Composability (302)
• Services are effective composition participants, regardless of the size and complexity of the composition.
How service-orientation design principles
collectively shape service design
Benefits of Service Orientation
Increased Amounts of Reusable Solution Logic
Business processes are automated by a
series of business process–specific
services (top layer) that share a pool of
business process–agnostic services
(bottom layer).
Reduced Amounts of Application-Specific Logic
Business Process A can be automated by
either Application A or Service
Composition A. The delivery of
Application A can result in a body of
solution logic that is all specific to and
tailored for the business process. Service
Composition A would be designed to
automate the process with a combination
of reusable services and 40% of
additional logic specific to the business
process.
Reduced Volume of Logic Overall
The quantity of solution logic shrinks as an enterprise
transitions toward a standardized service inventory
comprised of “normalized” services
Inherent Interoperability
Services from different parts of a
service inventory can be combined
into new compositions. If these
services are designed to be
intrinsically interoperable, the effort
to assemble them into new
composition configurations is
significantly reduced.
EFFECTS OF SERVICE-ORIENTATION ON THE
ENTERPRISE
• Service-Orientation and the Concept of “Application”
Service-Orientation and the Concept of
“Integration”
GOALS AND BENEFITS OF SERVICE-ORIENTED
COMPUTING
Increased Intrinsic Interoperability
Services are designed to be intrinsically interoperable
regardless of when and for which purpose they are
delivered. In this example, the intrinsic interoperability of
the Invoice and Timesheet services delivered by Project
Teams A and B allow them to be combined into a new
service composition by Project Team C.
Increased Federation
Three service contracts establishing a federated set of
endpoints, each of which encapsulates a different
implementation.
Increased Vendor Diversification Options
A service composition consisting of three
services, each of which encapsulates a different
vendor automation environment. If service-
orientation is adequately applied to the services,
underlying disparity will not inhibit their ability
to be combined into effective compositions.
Benefits of SOA
FOUR PILLARS OF SERVICE-ORIENTATION
• Teamwork – Cross-project teams and cooperation are required.
• Education – Team members must communicate and cooperate based
on common knowledge and understanding.
• Discipline – Team members must apply their common knowledge
consistently.
• Balanced Scope – The extent to which the required levels of
Teamwork, Education, and Discipline need to be realized is represented
by a meaningful yet manageable scope.
•
Thank You