E-Services course chapter II SOA - Reminder Version 2 Changes: Key words highlighted

1. E-Services
Chapter 2: SOA - Reminder
Mr. Abdessattar Ettaieb
ARS1/2 - 2016-2017

2. Content
Architectures: Old vs New
Service characteristics (SOA)
ServiceTypes (SOA)
What is SOA?
SOA principals
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3. Architectures:Old vs New
OLD ARCHITECTURE
◦ High cost
◦ Redundant connections
◦ Complex
◦ Not reusable and hard to
maintain
NEW ARCHITECTURE
◦ Reduce integration cost and complexity
◦ Efficiently manage business and technology
change
◦ Ensure high availability and scalability of the
digitized platform
◦ Mutable, Extensible, Reusable
◦ IT Governance and Compliance 2

4. Service characteristics (SOA)
Coarse-Grained: (composed of relatively large parts or particles).
◦ Using coarse-grained interfaces, a system of services controls access to the objects referenced by each service.While each service may be
implemented as an abstraction on a group of finer-grained objects, the objects themselves can be hidden from public access
Interfacable
◦ One service can implement many interfaces and also, many services may implement one common interface.
Locatable
◦ Before calling a service using bind and invoke, find should be called first.
Unique Instance
◦ A sevice is unique; it cannot be instanciated on the fly and also we cannot create many instances of it at the same time.
◦ A service is a Singleton.
Loosely-coupled
◦ In software terminology, loosely coupled refers to software where routines, modules, functions, and similar components are executed only as
needed, and do not run at the launch of the software application and while it is being used.
◦ Standards that connects services to clients and other services insure that:
◦ Clients and services are not coupled and this reduces dependencies.
◦ The use of XML documents, web services are a good example.
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5. ServiceTypes (SOA)
Presentation Services (Customer Layer)
◦ This category of capabilities addresses the support of presentation services,
which include a presentation, composite view and presentation control, and
the consumer-centric configuration of views.
Business Services
◦ It encapsulates the business logic (calculations, statistics, etc.), it may call
other services.
Data Access Services
◦ It handles the access to the database (connections, transactions, DML, etc.).
Integration Services
◦ It handles messages, data transfert…
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6. What is SOA?
Definition
• A service-oriented architecture is essentially a collection of services.These
services communicate with each other.The communication can involve
either simple data passing or it could involve two or more services
coordinating some activity,
• Service-Oriented Architecture (SOA) is an architectural style that supports
service-orientation.
• Service-orientation is a way of thinking in terms of services and service-
based development and the outcomes of services.
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7. What is SOA?
FromActors Perspective
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Manager
Architect
Developer
Integrator
Services that the company wants
to expose for its clients, partners
and other third-parties
A providor, consumer and service
description architecture
A standardized programming style
having specific paradigms,
technologies and tools A middleware providing
integration functionalities,
orchestration, monotoring and
services management.

8. SOA Principals(1/2)
Standardized Service Contract:
When a service is implemented as aWeb service, the service contract can be comprised of a WSDL
definition and multiple XML schema and policy definitions, as well as supplementary documents, such as
an SLA.
Service Loose Coupling
The application of this principle can effectively turn a service into a “black box” where the only
information made available about the service is what is published in its contract (which may encompass
what is also published in a service registry).
Service Abstraction
Service contracts only contain essential information and information about services is limited to what is
published in service contracts.
Service Reusability
Services contain and express agnostic logic and can be positioned as reusable enterprise resources.
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9. SOA Principals(2/2)
Service Autonomy
Autonomy enables service reuse.The more services are independent from one another — having
their own resources (database, legacies, etc.) — the more reuse and composition will be possible with
those services.
Service Statelessness
Services minimize resource consumption by deferring the management of state information when
necessary.
Service Discoverability
Services are supplemented with communicative meta data by which they can be effectively
discovered and interpreted.
Service Composability
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