Service Oriented Architecture

Service Oriented ArchitectureService Oriented Architecture

Overview of the syllabusOverview of the syllabus
♣ SOA characteristics
♣ Principles of service orientation
♣ Web service and its role in SOA
♣ Service oriented analysis
♣ Service oriented design
♣ SOA platforms
♣ SOA support in J2EE and .NET
♣ SOA standards
♣ Service composition (BPEL)
♣ Security in SOA

Prerequisite for understanding SOAPrerequisite for understanding SOA
♣Basic knowledge of object orientation
♣Understanding of web technologies
♣Basics of java programming
♣Basics of internet programming
♣Software Paradigms

Overview of the contentOverview of the content
♣Current trends
♣Software paradigms
♣Application architecture
♣Web based systems
♣2-tier and 3-tier architecture
♣Web based technologies
♣ component based systems

Current trends …Current trends …
♣ Internet based solution
♣ Complexity of the software
♣ Growth in hardware mobile and other smart
devices
♣ Demand for novel / customized services

Software paradigms…Software paradigms…
♣ Procedure oriented
♣ Object-oriented
♣ Component based
♣ Event-driven
♣ Logic based
♣ Aspect-oriented
♣ Service oriented

The monolithic mainframe application
architecture
♣ Separate, single-function applications, such
as order-entry or billing
♣ Applications cannot share data or other
resources
♣ Developers must create multiple instances of
the same functionality (service).
♣ Proprietary (user) interfaces

The distributed application
architecture
♣ Integrated applications
♣ Applications can share resources
♣ A single instance of functionality (service) can
be reused.
♣ Common user interfaces
♣ Bottom-up approach
♣ Real world scenario

Web based systems …
♣ Client-server model
♣ Client side technologies
♣ Server side technologies
♣ Web client, Web servers
♣ Application servers

Basic idea of TiersBasic idea of Tiers
Thick
client
Databas
e server
Tier 1: GUI
interactions with the
user and basic
validations
Request
Response
Tier 3: Database
processing
Web
server
Tier 2: Application
logic, Transaction
Management, Calls to
the database server
Applicati
on server

2-tier architecture2-tier architecture
Database
Driver
Database
Driver
DatabaseDatabase
Tier Boundary
Business
Logic
Business
Logic
Business
Logic
Business
Logic
Business
Logic
Business
Logic
Presentation
Logic
Presentation
Logic
Data Layer
Presentation / Business Layer

Two tier architectureTwo tier architecture
• Deployment costs are high
• Database driver switching costs are high
• Business logic migration costs are high
• The client has to recompile if the BL is changed
• Network performance suffers

N-Tier architectureN-Tier architecture
DatabaseDatabase
Business
Logic
Business
Logic
Database
Driver
Database
Driver
Business
Logic
Business
Logic
Business
Logic
Business
Logic
Presentation
Logic
Presentation
Logic
Data Layer
Tier Boundary
Tier Boundary

N-Tier architectureN-Tier architecture
• Deployment costs are low
• Database switching costs are low
• Business migration costs are low
• A firewall can secure parts of the
deployment
• Each tier can vary independently
• Communication performance suffers
• Maintenance costs are high

Presentation tier technologiesPresentation tier technologies
At client or server? Property Microsoft Technology Sun Technology
Client HTTP (Web) based HTML browser
(Internet Explorer)
HTML browser
(Netscape Navigator)
ActiveX Controls Java Applets
Non-HTTP based COM clients CORBA clients
Communication
Protocol between
client and server
DCOM RMI, IIOP
Server For creating dynamic
Web pages
ISAPI, ASP NSAPI, Servlets, JSP
Other pages HTML, XML HTML, XML

Business tier technologiesBusiness tier technologies
Purpose Microsoft Technology Sun Technology
Transaction handing,
Business Objects
COM, MTS EJB (Session Beans)
Queuing and Messaging MSMQ IBM’s MQSeries, Java
Messaging Service (JMS)
Database access ADO, OLE, ODBC JDBC, J/SQL (via Entity
Beans)

Microsoft Web TechnologiesMicrosoft Web Technologies
HTML
Browser
HTML
Browser
ASP ISAPI
HTML/XML pages
Firewall
COM
Client
ActiveX
Control
DCOM DCOM
DCOM
MTS Transactional
Components
MSMQ Queuing
Services
ADO/OLE/ODBC
Database Access
Database Database
Database Tier
Presentation Tier
Business Tier

Sun’s Web TechnologiesSun’s Web Technologies
HTML
Browser
HTML
Browser
Servlet JSP
HTML/XML pages
Firewall
CORBA
Client
Java
Applet
RMI/IIOP
RMI/IIOP
EJB Session Beans
MQSeries/Java Messaging
Service (JMS)
JDBC / SQL/J
Database Database
Database Tier
Presentation Tier
Business Tier
RMI/IIOP
EJB Entity Beans

Component World …Component World …
♣ Justification for component
♣ Interface
♣ Implementation
♣ Reusability
♣ standards

Eject
Skip
- Volume +
- Bass +
Actual
implementation
in terms of
voltages,
signals, currents
etc.
External
world (a user
of the audio
system)
Interface Implementation
Interface and ImplementationInterface and Implementation

Technologies for implementingTechnologies for implementing
componentscomponents
♣ RMI / EJB
♣ CORBA
♣ COM, DCOM, COM+
♣ Limitations
♣ Web services (XML based standards)

Basic model of distributed systemBasic model of distributed system
Service
Registry
Service
Requestor
Service
provider
find
Bind
Publish

An Archetypal Distributed Objects System
o b je c t c l i e n t o b je c t s e r v e r
c l i e n t
p r o x y
s e r v e r
p r o x y
r u n t i m e
s u p p o r t
n e t w o r k
s u p p o r t
n e t w o r k
s u p p o r t
p h y s i c a l d a t a p a t h
l o g i c a l d a t a p a t h
o b je c t
r e g i s t r y
r u n t i m e
s u p p o r t

Distributed Object Systems / ProtocolsDistributed Object Systems / Protocols
• The distributed object paradigm has been
widely adopted in distributed applications, for
which a large number of mechanisms based on
the paradigm are available. Among the most
well known of such mechanisms are:
~ Java Remote Method Invocation (RMI),
~ the Common Object Request Broker Architecture
(CORBA) systems,
~ the Distributed Component Object Model
(DCOM),
~ mechanisms that support the Simple Object
Access Protocol (SOAP).

RMI architectureRMI architecture
Client
Browse
r
Web
server
HTML
Java applets
Stub
Applicatio
n server
Skeleton
Object
Implementation
HTML
pages
JRMP / IIOP
HTTP
Applets

CORBA architectureCORBA architecture
Client
Brows
er
Web
server
HTML
Java applets
Client
ORB
Application
server
Server
ORB
Object
Implementation
HTML
pages
IIOP
HTTP
Applets

DCOM architectureDCOM architecture
Client
Browse
r
Web
server
HTML
ActiveX
Controls
Proxy
Applicatio
n server
Stub
Object
Implementation
HTML
pages
DCOM
HTTP
ActiveX

Limitations of ComponentsLimitations of Components
♣Tightly coupled
♣Cross language/ platform issues
♣Interoperability issues
♣Maintenance and management
♣Security issues

Application Centric
Finance
DistributionManufacturing
Supply
Narrow Consumers
Limited Business Processes
Overlapped resources
Overlapped providers
Business
scope
Integration
Architecture
Business functionality is
duplicated in each application
that requires it.
EAI ‘leverage’ application silos
with the drawback of data and
function redundancy.
bound to
EAI vendor
Redundancy

What are services?What are services?
♣ A service is
Autonomous unit of automated business
logic
Accessible to other systems
♣ A service represents
Business process
Sub process
Activity (process step)
(or multiple)

What is Service Architecture?
• A collection of
services
• classified into types
• arranged into layers
• Governed by architectural
patterns and policies
services
identification
granularity
dependency
type typetype
source:TietoEnator AB, Kurts
Bilder

SOA is a software architecture model
in which business functionality are logically grouped
and encapsulated into self contained,distinct and
reusable units called services that
represent a high level business concept
can be distributed over a network
can be reused to create new business applications
contain contract with specification of the purpose,
functionality, interfaces (coarse grained), constraints,
usage
SOA Defined

SOA is a software architecture model
in which business functionality are logically grouped
and encapsulated into self contained,distinct and
reusable units called services that
represent a high level business concept
can be distributed over a network
can be reused to create new business applications
contain contract with specification of the purpose, functionality,
interfaces (coarse grained), constraints, usage
SOA Defined
Services are autonomous, discrete and reusable units of
business functionality exposing its capabilities in a form
of contracts. Services can be independently evolved,
moved, scaled even in runtime.
Services are autonomous, discrete and reusable units of
business functionality exposing its capabilities in a form
of contracts. Services can be independently evolved,
moved, scaled even in runtime.

Big (outer) vs. Little (inner) SOA

Service RelationshipsService Relationships
GUI Applications
Student
This is not a use case
Goals Business
Processes
Services
Business
Applications
uses
has
help users
achieve
participates
in
invokes
supported
by
are realized
by (partially)
exposes
orchestrate / are composed of

Why SOA?Why SOA?
♣ Heterogeneous cross-platform
♣ Reusability at the macro (service) level rather
than micro(object) level
♣ Interconnection to - and usage of - existing IT
(legacy) assets
♣ Granularity, modularity, composability,
componentization
♣ Compliance with industry standards

SOA is an evolutionary step
 for architecture

in reusability and communication

Project-ware SOAEAI
in distributed communications
source:Sam Gentile

Features of SOAFeatures of SOA
♣ Self- describing Interface (WSDL)
♣ Message communication via formally defined
XML
♣ Services are maintained in a registry
♣ Each service has a Quality Of Service
♣ Applications adapt to changing technologies
♣ Easy integration of applications with other
systems
♣ Leverage existing investments in legacy
applications

Service Architecture CompositionService Architecture Composition
♣ Service architectures are composed of
Services
• Units of processing logic
• Example: Credit card Service
Messages
• Units of communications between services
• Needed for services to do their job
Operations
• Units of Work
• Example: Determine Cost of Attendance
Processes
• Composed / orchestrated groups of services
• Example: Financial Aid Disbursement

SOA principlesSOA principles
♣ Service Encapsulation
♣ Service Loose coupling
♣ Service Contract
♣ Service abstraction
♣ Service Documentation
♣ Service reusability
♣ Service composability
♣ Service autonomy
♣ Service optimization and Discovery
♣ Service statelessness

Loose Coupling
“Service contracts impose low consumer coupling
requirements and are themselves decoupled from their
surrounding environment."
Create specific types of relationships within and outside
of service boundaries with a constant emphasis on
reducing (“loosening”) dependencies
between
 Service contract
 Service implementation
 Service consumers
Source: Thomas Erl

Standardized Service Contracts
∀ “Services within the same service inventory are in
compliance with the same contract design standards."
∀ Services use service contract to
 Express their purpose
 Express their capabilities
∀ Use formal, standardized service contracts
∀ Focus on the areas of
 Functional expression
 Data representation
 Policy
Source: Thomas Erl

Abstraction
∀ “Service contracts only contain essential
information and information about services is
limited to what is published in service contracts”
∀ Avoid the proliferation of unnecessary service
information, meta-data.
∀ Hide as much of the underlying details of a
service as possible.
 Enables and preserves the loosely coupled
relationships
 Plays a significant role in the positioning and
design of service compositions Source: Thomas Erl

Reusability
∀ “Services contain and express agnostic logic and
can be positioned as reusable enterprise
resources."
∀ Reusable services have the
following characteristics:
 Defined by an agnostic functional context
 Logic is highly generic
 Has a generic and extensible contract
 Can be accessed concurrently
Source: Thomas Erl

Composability
∀ "Services are effective
composition
participants,
regardless of the size
and complexity of the
composition."
∀ Ensures services are
able to participate in
multiple compositions
to solve multiple larger
problems
Source: Thomas Erl

Autonomy
∀ "Services exercise a high level of control over
their underlying runtime execution environment."
∀ Represents the ability of a service to carry out its
logic independently of outside influences
∀ To achieve this, services must be more isolated
∀ Primary benefits
 Increased reliability
 Behavioral predictability
Source: Thomas Erl

Discoverability
∀ "Services are supplemented with communicative
meta data by which they can be effectively
discovered and interpreted."
∀ Service contracts contain appropriate meta data for
discovery which also communicates purpose and
capabilities to humans
∀ Store meta data in a
service registry or profile
documents
Source: Thomas Erl

Statelessness
∀ "Services minimize resource consumption by
deferring the management of state information
when necessary."
∀ Incorporate state management deferral
extensions within a service design
∀ Goals
 Increase service scalability
 Support design of agnostic
logic and improve service reuse
Source: Thomas Erl

Applying SOA - Governance
Goal: Establish SOA organization governance (SOA
Board) that governs SOA efforts and breaks down
capabilities into non-overlapping services
 Governance is a program that makes sure
people do what is ‘right’
 In conjunction with software, governance controls
the development and operation of software

∀Policies
 Codification of laws, regulations, corporate
guidelines and best practices
 Must address all stages of the service lifecycle
(technology selection, design, development
practices, configuration management, release
management, runtime management, etc.)

∀Processes
 Enforce policies
 System-driven processes (code check-in, code
builds, unit tests)
 Human-driven process (requests, design
reviews, code reviews, threat assessment, test
case review, release engineering, service
registration, etc.)

∀Metrics
 Measurements of service reuse, compliancy
with policy, etc.
 Organization
 Governance program should be run by SOA
Board, which should have cross-functional
representatives

Business functionality has to be made available as services.
Service contracts must be fixed
Implemented services must be designed with reuse in mind.
This creates some overhead.
Potential service users must be involved in the design
process and will have influence on the service design
Applying SOA - Challenges
∀ Service Orientation
∀ Reuse
∀ Sharing of Responsibilities
∀ Increased complexity!

(Source: Enterprise SOA: Service Oriented Architecture Best Practices
by Dirk Krafzig, Karl Banke, and Dirk Slama, Prentice Hall 2004)
Applying SOA – Renovation
Roadmap

Service Oriented Architecture modelService Oriented Architecture model

Before SOA – After SOA
source:IBM

Why SOA?
To enable Flexible, Federated Business Processes
Enabling a virtual federation of
participants to collaborate in an
end-to-end business process
Enabling alternative
implementations
Enabling reuse of
Services
Enabling virtualization of business resources Enabling aggregation from multiple
providers
Identification
Ticket Sales
Ticket Collection
Inventory
Logistics
Manufacturing
Availability
Service
Service
Service
Service
Service
Service
Service
Service Service
Service
Ordering
Bilder

Why SOA? To enable Business Process Optimization
and the Real Time Enterprise (RTE)
Seamless End to End Process
Internal Systems
SOA Pattern: Standardized Service
provided by multiple suppliers
Service from Multiple Suppliers
SOA Patterns: Single, Multi-Channel
Service for consistency
BPM Expressed in
terms of Services
Provided/Consumed
Enterprise
Bilder
Smart Clients
Stores POS
Mobile
3rd
Party Agents
Portal
Service to Customers

Why SOA?
Enable Structural Improvement
ERP X Process Z Partner A Process Y
Service
Standardizing capabilities Information Consistency
Policy Consistency
e.g. Single Customer
Details Service
Consolidation/
Selection
process
Reducing impact
of change
Encapsulating
implementation
complexity
ERP Z
CRM
System 2
CRM
System 1
Product
System
Policy Rationalization and Evolution
Resource Virtualization
e.g. Multiple
Sources of
Customer Details

Service Architecture Organized by Layers
Reasons for Layering
1. Flexible composition.
2. Reuse.
3. Functional standardization in
lower levels
4. Customization in higher
layers
5. Separation of Concerns.
6. Policies may vary by Layer
Example Layers
Presentation
& workflow
Composed Services
Basic Services
Underlying
API
according to:TietoEnator AB,
Kurts Bilder

Different layers of SOADifferent layers of SOA

Service Composition ExampleService Composition Example
Aid
Disbursement
Process
FA
Award
Service
Registration
Service
Loan
Service
Bursar
Service
FA System
Microsoft .NET
Registrar System
Mainframe
Dept of Ed
???
Bursar
Java on Linux
Aid Disburse
Service
Is Realized By
Are Executed In / Controlled By
Orchestrates
account info
Debit Account
Service
Interface
Layer
App
Logic
Not
Physical

Applying services to the problemApplying services to the problem
Monolithic
Before
The System
After
S1 S2 S4S3
System replacement is a total process
System modules are tightly interdependent
making change difficult
System composed of many logical service
units (decomposition)
Underlying business logic decoupled as
much as possible from other services
(autonomy and loose coupling)

Goal of SOAGoal of SOA
♣ Loosely coupled
♣ The goal for a SOA is a world wide mesh of
collaborating services, which are published
and available for invocation on the Service
Bus.
♣ SOA is not just an architecture of services
seen from a technology perspective, but the
policies, practices, and frameworks by which
we ensure the right services are provided and
consumed.

Major service types
Basic Services:
 Data-centric and logic-centric services
 Encapsulate data behavior and data model and
ensures data consistency (only on one
backend).
 Basic services are stateless services with high
degree of reusability.
 Represent fundamental SOA maturity level and
usually are build on top existing legacy API
(underlying services.

Major service types
Composed Services :
expose harmonized access to inconsistent basic
services technology (gateways, adapters, façades,
and functionality-adding services).
Encapsulate business specific workflows or
orchestrated services.

SOA Benefits SummarySOA Benefits Summary
♣ Allow us to execute complex business
processes by composing systems from small,
less complex building blocks
♣ Fosters collaborative business and technical
environment through sharing and coordination
of services
♣ Create outward facing self-service applications
not constrained by organizational boundaries
♣ Enables creating adaptive, agile systems that
are resilient to changes in the business
environment

ConclusionsConclusions
♣ SOA represents a fundamental change to the
way information systems will designed in the
future
♣ Long term impact on IT portfolio management
is dramatic
♣ Adds a significant dimension to system
evaluation process
♣ Undertaking SOA requires commitment from
all levels of the organization and significant
investments (people, process, and tools)

Service Oriented Architecture

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