Service Oriented Architecture (SOA) And Web Services by vev19514

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									Service Oriented Architecture
            (SOA)
      And Web Services

              By
        Ahmed Chaudhary




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Presentation overview

• Introduction to SOA
  – Through Examples and Metaphors
• Introduction to Web Services
  – Brief overview of XML Technologies
• Comparison of SOA and services with
  other paradigms
• Benefits and limitations of SOA

                                         2
A business trip in the not so
       distant future




                                3
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Information Technology used in
this trip
• Keeping track of all the customer contacts in an online
    repository
•   Obtaining Company Contact Information from an
    External Service
•   Online Calendar Services
•   Getting Updates on Clients to Be Visited While on the
    Road
•   Travel Agency Service
•   Car Rental Service
•   Airlines and Hotel
•   Services as Commodities


                                                            5
Another Example




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SOA Explained

• A service-oriented architecture is
  essentially a collection of services.
• These services communicate with each
  other
• Some mechanism of connecting services
  to each other is needed. Those
  connections are Web Services.

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What is a service ?

• A function that is well-defined
• Self-contained
• Does not depend on the context or state
 of other services.




                                            8
The Mail-Order Business
• A Mail-Order Business is Asynchronous
   – Work Requests Arrive in Bags of Mail
   – Product Arrives in Shipments
• Each Message (Order) Is a Transaction
   – Goods Are Prepared and Packed
   – Payment Is Processed
   – Stuff is Shipped
• Standards and Interchangeability Required
   – Both Goods and Forms
• Mail-Order Is a Service-
  Oriented Architecture!
   – Well defined functions
   – Self-contained
   – Independent
                                              9
How Services Work




                    10
Web Services

• Web services are the mechanism for
  connecting services programmatically and
  are based on standards.
• Other existing connection mechanisms:
  – CORBA
  – DCOM
  – EDI etc.


                                             11
How Web Services Work




                        12
More on Web Services

• Web services can be published, located, and invoked
  across the Web.
• The standards required to do so are:
   – Simple Object Access Protocol (SOAP), also known as service-
     oriented architecture protocol, an XML-based RPC and
     messaging protocol
   – Web Service Description Language (WSDL), a descriptive
     interface and protocol binding language
   – Universal Description, Discovery, and Integration (UDDI), a
     registry mechanism that can be used to look up Web service
     descriptions


                                                                    13
Some points about Web Services

• Services aren’t tied to user interfaces.
• Services can be implemented in any
  language, COBOL, Java, etc., but all
  services must support the same
  invocation/communication protocols (for
  example XML/SOAP)



                                             14
Introduction to XML and
  related Technologies




                          15
What is XML?

• XML stands for EXtensible Markup
  Language
• XML is a markup language much like
  HTML
• XML was designed to describe data
• XML tags are not predefined. You must
  define your own tags

                                          16
An Example




             17
What is an XML Schema?

• The purpose of an XML Schema is to
 define the building blocks of an XML
 document
  – defines elements that can appear in a
    document
  – defines which elements are child elements
  – defines the order of elements
  – defines the number of child elements
  – defines data types for elements and attributes
                                                 18
What is SOAP?




                19
What is WSDL?

• WSDL stands for Web Services Description
  Language.
• WSDL is a document written in XML.
• The document describes a Web service. It
  specifies the location of the service and
  the operations (or methods) the service
  exposes.

                                          20
Comparisons of SOA




                     21
SOA vs CORBA & DCOM




                      22
   SOA vs. Enterprise Integration
        Architecture (EIA)
• EIA is being reactive
• SOA is being proactive




                                    23
Services vs. Components

• A service is a coarse-grained processing
  and maps to a business function
• A component typically maps to business
  entities and the business rules




                                             24
An example component model




                             25
Revisiting the Business Trip




                               26
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Why do we need SOA?
• There's little "green field" anymore
  – New stuff needs existing stuff
  – Existing stuff needs new stuff
• Heterogeneous Systems
  – No single OS-family / HW-platform
• Deal with "Big Bang" Effect
  – Everything keeps drifting farther away from
    everything else
  – Access/Manipulate data from anywhere
                                                  28
SOA Benefits
•   Leverage existing assets.
•   Easier to integrate and manage complexity.
•   More responsive and faster time-to-market.
•   Reduce cost and increase reuse.
•   Be ready for what lies ahead.




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SOA Limitations

• SOA requires an environmental framework
• Pending security issues
• Handling Transactions




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Summary
• SOA is an architectural style that encourages the
  creation of loosely coupled business services
  Loosely coupled services that are interoperable
  and technology-agnostic enable business
  flexibility
• An SOA solution consists of a composite set of
  business services that realize an end-to-end
  business process
• Each service provides an interface-based service
  description to support flexible and dynamically re-
  configurable processes

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Q&A




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