Service Oriented Architecture , Its Tenets and Challenges

7/31/2019 Service Oriented Architecture , Its Tenets and Challenges

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S ERVICE ORIENTED ARCHITECTURE , ITS TENETS AND CHALLENGES

Presented By:-Vatesh Pasrija

Shobhit Khandelwal1


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T ABLE OF CONTENT

Introduction to Service Oriented ArchitectureType of Service Oriented ArchitecturesSoftware Service Engineering Tenets

Research Issues and Challenges

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S ERVICE ORIENTED ARCHITECTURE

Service Oriented Architecture or SOA for short is a newarchitecture for the development of loosely coupleddistributed applications. In fact service-orientedarchitecture is collection of many services in the network.These services communicate with each other and thecommunications involves data exchange & even servicecoordination.SOA is based on the Web Services.Broadly SOA can be classified into two terms: Services and Connections .

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S ERVICE ORIENTED ARCHITECTURE Services:

A service is a function or some processing logic or business processing that is well-defined, self-contained, and does not depend on the context or state of other services.Example of Services are:-

Loan Processing Services , which can be self-contained unit for process theLoan Applications.Weather Services , which can be used to get the weather information. Anyapplication on the network can use the service of the Weather Service to get theweather information.

Connections: Connections means the link connecting these self-contained distributed services witheach other, it enable client to Services communications.In case of Web services SOAP over HTTP is used to communicate between theservices.

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SOA comprises of the followingService Consumption AssembliesService Pool

Service Provider Pool contains:Process Services: implemented in BPELBusiness Activity: Wrapped java ComponentsData/Resource Access Service: SQL adapters and connectors

Service Consumption Assemblies are mainly WebServers.Consumers and Producers communicate over ESB usingSOAP as a message exchange protocol.

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S ERVICE ORIENTED ARCHITECTURE COMPONENTS


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S ERVICE ORIENTED ARCHITECTURE


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ENTERPRISE S ERVICE BUS

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Web Service Description Language(WSDL)SOA functions and services are defined by a description languageknown as WSDL.The WSDL defines the interface to communicate directly with the

application business logic.In particular, all clients can directly communicate with application withXML messages through service interfaces with WSDL.

Simple Object Access Protocol(SOAP) All the Service Request and Replies are messages which areformatted according to SOAP.SOAP presents a light-weighted protocol used for communicationover the Internet using protocol like HTTP/HTTPs etc.The SOAP request is received by run-time service (Listener) thataccept SOAP message, extracts the XML message body, transformsthe XML message into a native protocol, and pass the request toactual business process within the enterprise.


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KEY P OINTS TO SOA

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S OFTWARE S ERVICE ENGINEERING : TENETS

Software Service Engineering is the science andapplication of concepts, models, methods and tools todesign, develop(source), deploy, and maintain business-aligned and SOA-based software systems in a disciplined,

reproducible and repeatable manner.Tenets are the principles without which is it very difficult toguarantee that the developed software system and itsservices meet the standards and are loosely coupled and

specified via clean and proper interface.

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S IX TENETS

The following are some of the SSE tenets:-Technical FederationDynamism or VirtualizationOrganizational FederationExplicit Boundaries or service contractsHeterogeneityBusiness-IT alignment

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1.T ECHNICAL FEDERATION Its states that SSE should be able to cater the service enabled softwareapplications that are logically and physically distributed.

Services should be independent and loosely coupled.

SSE should support Message based communication via ESB and encourage Asynchronous and Non-blocking interaction between service consumer andservice provider.

SSE should favor send and forget, store and forward principle through the useof ESB queue. Hence increase flexibility and reliability.

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2.D YNAMISM This Tenet states that services must be aggregated into service compositionat runtime via late binding to support specific task.(forming agile servicenetwork )Loose coupling and late binding are two key principle for increasing theadaptability of service application.

For Example service consumption assemblies may lookup available processservices at runtime, depending on the content of incoming user requests( e.g

regular or premium customer).So a process can service can pick up adifferent business activity service based on current processing state andrequired quality of service.

This scenario can be achieved by using Pipe-and-Filters and Model ViewController Pattern.

Lookup Registry

is be needed.

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3.O RGANIZATIONAL FEDERATION

SSE should be shaped around the belief stating that developmentand maintenance are often conducted in distributed organizationalunits, possibly involving multiple lines of business, other enterpriseand government institutions.Organizational federation requires sound distributed governancemechanism accommodating the individual needs of the variousstakeholders.For Example parts of application are developed by a separate projectteam(which may be geographically distributed but are managedcentrally).

In SOA, each service provider in the service pool and each servicecomposition assembly may be developed autonomously by a differentunit or legal entity.

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4.E XPLICIT BOUNDARIES (S ERVICE CONTRACTS )Services in SOA should have clear boundaries.

These clear boundaries must be provided in form of servicecontracts that captures goals and constraints i.e. pre- and post-conditions.Structural Contract:- An intrinsic part of the service contractsentails the service interface that specifies the messages a service

understands and the service endpoints that are available.Behavioral Contract:- Enriching the service interface withadditional semantic information such as scenarios or behavior allows a more robust and stable service composition.Policy Contract:- This is amended with Service Level

Agreements(SLAs) between service consumers and serviceprovider which allow service consumer to express the expectedand service provider to specify the available QoS.

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5.H ETROGENEITY

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This Tenet states that any SSE concept, method or tool must provideheterogeneity and the context in which the architecture elementsmust operate.In other words, system should be platform independent.SSE has to deal with services that may be deployed on various

platforms including mobile devices, compute clouds or any legacysystems and have been developed under various programmingparadigms such as OO and CBD.For Example, the user client may be a PHP script etc whereas theprocess might be a executable BPEL process hosted by BPM engine

and business activity service might be implemented as java or C#components etc. Hence making system platform independent.


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5.H ETROGENEITY

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6.B USINESS -IT ALIGNMENT SSE should adopt new style of development such that SOAapplications can be systematically and routinely mapped to businessprocesses.For example, process services are responsible for managing sessionstate and preserving process and resource integrity. The control flowsinside the executable processes have to be aligned with the wantsand needs of business users.From the architectural viewpoint, business rules provide an additionalway of expressing business semantics inside an application and suchrules are used to assure that system meet regulatory compliance lawsand business policies.SSE challenge is to integrate such business rules into overall serviceengineering lifecycle and programming model.

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7.H OLISTIC ENGINEERING APPROACH

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EXAMPLE OF SOA(A UTOMOTIVE WORK ORDER )

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S ERVICE MODEL EXAMPLE

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BUSINESS P ROCESS MODEL

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RESEARCH ISSUES AND CHALLENGES Integration of various software platforms.

Change management and runtime integration

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Servicerequester

Provider Requester

ServiceProvider

(J2EE )

ServiceProvider

(.NET )


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RESEARCH ISSUES AND CHALLENGES

Reliability and robustness of services.For Example: Should be able to handle simultaneously many requests of pizza delivery

Cater the logically and physically distributed service

Forward and backward compatibility issues

In SOA applications, the context in which this property may be usedis to vast to be decided in advance.

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RESEARCH ISSUES AND CHALLENGES

The mapping from requirements to services fulfilling them

Difficult to bring in a uniform mechanism.

challenge of integrating and making heterogeneous systems work

Testing

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REFERENCES

Software Service EngineeringService oriented architecture: Approaches,Technologies and Research Issues

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Documents

Service Oriented Architecture , Its Tenets and Challenges