CS 415 N
-
Tier Application Development
By Umair Ashraf
July 5 ,2013
National University of Computer and Emerging Sciences
Lecture
# 8
Introduction to Service Oriented architecture
Agenda/Contents for Today’s Lecture
SOA Introduction
SOA Myths and Facts
Evolution of SOA
Understanding Services
SOA Reference Model
Examples
Service Oriented Architecture (SOA)
SOAs are like snowflakes
–
no two are alike.”
-
David Linthicum
Introduction to SOA
The SOA Elephant
SOA is a bit like John Godfrey Saxe’s poem about the blind men and the elephant.
The man touching the trunk believes it to be a snake
The man touching the tusk believes it to be a spear
The man touching the ear believes it to be a fan
The man touching the elephant’s side believes it to be a wall
The man touching the tail believes it to be a rope
The man touching the legs believes they are trees.
Problems addressed by service oriented architecture
Definitions for SOA
A loosely
-
coupled architecture designed to meet the business
needs of the organization.
A set of components which can be invoked, and whose
interface descriptions can be published and discovered (W3C).
A paradigm for organizing and utilizing distributed capabilities
that may be under the control of different ownership domains.
It provides a uniform means to offer, discover, interact with
and use capabilities to produce desired effects consistent with
measurable preconditions and expectations. (OASIS)
Simple Definition
-
SOA
A method of design, deployment, and management of both
applications and the software infrastructure where:
All software is organized into business services that are
network accessible and executable.
Service interfaces are based on public standards for
interoperability.
Characteristics of SOA
Quality of service, security and performance are specified.
Software infrastructure is responsible for managing.
Services are cataloged and discoverable.
Data are cataloged and discoverable.
Protocols use only industry standards.
What is a service ?
A Service is a reusable component.
A Service changes business data from one state to
another.
A Service is the only way how data is accessed.
I
f you can describe a component in WSDL, it is a Service.
SOA Myths and Facts
Example
–
A City
Let's take your average cosmopolitan city.
It
is already full of service
-
oriented businesses. Individual
companies are service
-
oriented in that each provides a
distinct service that can be used by multiple consumers.
Collectively
, these businesses comprise a business
community.
It
makes sense for a business community not to be
served by a single business outlet providing all services.
By
decomposing the community into specialized,
individual outlets, we achieve an environment in which
these outlets can be distributed.
SOA
-
Loose Architecture
For
services to interact and accomplish something meaningful, they must exchange
information. A communications framework capable of preserving their loosely coupled
relationship is therefore required. One such framework is messaging. After a service
sends a message on its way, it loses control of what happens to the message thereafter.
That is why we require messages to exist as "independent units of communication."
This means that messages, like services, should be autonomous.
The Evolution of SOA
Service Orientation (SO) is the natural evolution of current
development models
The, 80s saw object
-
oriented models
Component
-
based development model in the 90s
Now we have service orientation (SO)
The Evolution…
From Three
-
Tier Applications
Presentation
Layer
Databases
Application
Application
Application
Business Layer
The Evolution to:
SOA
-
Based Applications
Databases
Presentation
Process #1
Process #2
Process #3
Service
Components
Calls for a Paradigm Shift
Service Oriented Architecture
Functionality Driven
Long development cycles
Tightly Coupled
Application Specific
Designed to last
Data Oriented
Traditional Architecture
Process Oriented
Iterative development
Loosely Coupled
Heterogeneous
Designed for change
Business Service Oriented
SOA v/s Traditional Architecture
But must be built on standards
to enhance interoperability
Service
-
Oriented Architecture:
Key Concepts
Service
A unit of business functionality that can be
invoked over the network
Web service
A service that is called in a standard way, so
anyone can use it without knowing its internals
“Loosely
coupled”
When services are self
-
contained, and can be
easily combined and disassembled, they are called
loosely coupled.
Service
-
Oriented
Architecture
A standards
-
based platform that lets you model,
develop, find, and combine services into flexible
business processes
Orchestration
Combining and assembling services into a
coherent business process
–
also known as
business process management
DoD
Concept How to Organize for SOA
Enterprise Information Environment
Business Mission
WarFighting Mission
Intelligence Mission
Army, Navy
Air Force
Agencies
Combatant
Commands
Programs
Focus of this
Presentation
Organization of Infrastructure Services
Infrastructure
Services
(Enterprise Information)
Data
Services
Security
Services
Computing
Services
Communication
Services
Application
Services
Organization of Data Services
Data
Services
Discovery
Services
Management
Services
Collaboration
Services
Interoperability
Services
Semantic
Services
Organization of Security Services
Security
Services
Transfer
Services
Protection
Services
Certification
Services
Systems
Assurance
Authentication
Services
Organization of Computing Services
Computing
Services
Computing
Facilities
Resource
Planning
Control &
Quality
Configuration
Services
Financial
Management
Organization of Communication Services
Communication
Services
Interoperability
Services
Spectrum
Management
Connectivity
Arrangements
Continuity of
Services
Resource
Management
Organization of Application Services
Application
Services
Component
Repository
Code Binding
Services
Maintenance
Management
Portals
Experimental
Services
A Few Key SOA Protocols
Universal Description, Discovery, and Integration,
UDDI
. Defines the
publication and discovery of web service implementations.
The Web Services Description Language,
WSDL
, is an XML
-
based
language that defines Web Services.
SOAP
is the Service Oriented Architecture Protocol. It is a key SOA
in which a network node (the client) sends a request to another node
(the server).
The Lightweight Directory Access Protocol, or
LDAP
is protocol for
querying and modifying directory services.
Extract, Transform, and Load,
ETL
, is a process of moving data from a
legacy system and loading it into a SOA application.
SOA Interoperability Goals for the
Department of Defense
Interoperability of solutions across the
DoD
strategic goal.
Rules for sharing of data and services across the enterprise.
Enforcement of standards.
All data, services, and applications shall be accessible,
understandable, and trusted.
Global Information Grid for sharing of information with
Federal Departments, Department of Homeland Security, the
Intelligence Community, state and local governments, allied,
coalition, non
-
governmental organizations (NGOs), academic,
research and business partners.
27
Example of Customizable Web Services
(
www
.
salesforce.com
)
Fee database
Data Services
ESB: Routes to appropriate core system
DDA / Current Account
Internet Banking
Business Process: Stop Payment
Process Services
Orchestration:
Business Logic: If
Customer_Status = Gold
Service_Fee = $8 else
Service_Fee = $20
Security: Authenticate user
Registry and Repository: Find
Stop Payment Service, Charge
Fee service
Manage and monitor
Banking Examples of SOA
Place customer orders:
1. Basic Data Service
–
access
operations, 2. Composed Services
-
business logic, 3. Process Services
–
complex business logic
A Unified Patience Journal System
Why SOA Saves Code
Provides a standard way of interacting with shared
software.
Enables software to become building blocks for reuse.
Shifts focus to application assembly rather than design.
Creates new applications out of existing components.
Integrates with applications in other enterprises.
Reference Material
http://msdn.microsoft.com/en
-
us/library/bb833022.aspx
http://msdn.microsoft.com/en
-
us/library/aa480021.aspx
http://edizsaykol.weebly.com/serviceorientedarchitectures.html
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