Roots of SOA

ROOTS OF SOA

1. Roots of SOA

2. Characteristics of SOA

3. Comparing SOA to client-server and distributedinternet architectures

4. Anatomy of SOA

5. How components in an SOA interrelate

6. Principles of service orientation

Introduction:

Pre-requisite Discussion:

Application architecture is to an application development team what a blueprint is to a team of construction workers. Different organizations document different levels of application architecture.

An SOA can refer to an application architecture or the approach used to standardize technical architecture across the enterprise.

Contents:

CHARACTERISTICS OF SOA:

Service-oriented architecture:

·        An SOA can refer to an application architecture or the approach used to standardize technical architecture across the enterprise.

The components of the basic (first-generation) Web services framework.

This framework can be applied to implement services in just about any environment.

Services are discoverable and dynamicallybound. Services are self-contained and modular.

Services stress interoperability. Services are loosely coupled.

Services have a network-addressable interface.

Services have coarse-grained interfaces. Services are location-transparent. Services are composable.

Service-oriented architecture supports self-healing.

CONTEMPORARY SOA

•         Major software vendors are continually conceiving new Web services specifications and building increasingly powerful XML and Web services support into current technology platforms.

•         The result is an extended variation of service-oriented architecture we refer to as contemporary SOA.

SOA increases quality of service

•         Ability for tasks to be carried out in a secure manner, protecting the contents of a message, as well as access to individual services.

•         Reliability so that message delivery or notification of failed delivery can be guaranteed.

•         Overhead imposed by SOAP message and XML content processing does not inhibit the execution of a task.

SOA is based on open standards

Standard open technologies are used within and outside of solution boundaries.

SOA supports vendor diversity

SOA promotes discovery

SOA encourages intrinsic interoperability

SOA promotes federation

SOA promotes architectural composability

•         Different solutions can be composed of different extensions and can continue to interoperate as long as they support the common extensions required.

SOA encourages intrinsic reusability

SOA emphasizes extensibility

•         Extensible services can expand functionality with minimal impact.

SOA supports a service-oriented business modeling paradigm

Partitioning business logic into services that can then be composed has significant implications as to how business processes can be modeled

SOA implements layers of abstraction

•         Application logic created with proprietary technology can be abstracted through a dedicated service layer.

SOA promotes loose coupling throughout the enterprise

SOA promotes organizational agility

Client server Architecture:

•         Mainframe back-ends served thin clients, are considered an implementation of the single-tier client-server architecture Mainframe systems natively supported both synchronous and asynchronous communication. The latter approach was used primarily to allow the server to continuously receive characters from the terminal in response to individual key-strokes. Only upon certain conditions would the server actually respond.

Distributed Internet Architecture:

•         Distributing application logic among multiple components (some residing on the client, others on the server) reduced deployment headaches by centralizing a greater amount of the logic on servers. Server-side components, now located on dedicated application servers, would then share and manage pools of database connections, alleviating the burden of concurrent usage on the database server A single connection could easily facilitate multiple users.

How the components of a service-oriented architecture relate.

How the components of a service-oriented architecture define each other.

ANATOMY OF SOA

Application architecture is to an application development team what a blueprint is to a team of construction workers. Different organizations document different levels of application architecture.

Service-oriented architecture:

An SOA can refer to an application architecture or the approach used to standardize technical architecture across the enterprise.

The components of the basic (first-generation) Web services framework.

This framework can be applied to implement services in just about any environment.

1. Logical components of the Web services framework

Each Web service contains one or more operations. This diagram introduces a new symbol to represent operations separately from the service.

Each operation governs the processing of a specific function the Web service is capable of performing.

The processing consists of sending and receiving SOAP messages,

The Web services framework provides us not only with a technology base for enabling connectivity, it also establishes a modularized perspective of how automation logic, as a whole, can be comprised of independent units.

The following fundamental parts of the framework:

·        SOAP messages

·        Web service operations

·        Web services

·        activities

The latter three items represent units of logic that perform work and communicate using SOAP messages.

·        messages

·        operations

·        services

·        processes (and process instances)

^Ø   The one exception is the use of "process" instead of "activity."

^Ø   the word "activity" is used in different contexts when modeling service-oriented business processes.

^Ø   Web service activity is typically used to represent the temporary interaction of a group of Web services,

^Ø   a process is a static definition of interaction logic. An activity is best compared to an instance of a process wherein a group of services follow a particular path through the process logic to complete a task.

·        messages = units of communication

·        operations = units of work

·        services = units of processing logic (collections of units of work)

·        processes = units of automation logic (coordinated aggregation of units of work)

Figure 4 provides us with a primitive view of how operations and services represent units of logic that can be assembled to comprise a unit of automation logic.

Figure 4. A primitive view of how SOA modularizes automation logic into units.

The messages are a suitable means by which all units of processing logic (services) communicate. No actual processing of that logic can be performed without issuing units of communication (in this case, messages).

Figure 5 A primitive view of how units of communication enable interaction between units of logic.

The purpose of these views is simply to express that processes, services, and operations, on the most fundamental level, provide a flexible means of partitioning and modularizing logic.

Regardless of the technology platform used, this remains the most basic concept that underlies service-orientation.

3. Components of an SOA

·        A message represents the data required to complete some or all parts of a unit of work.

·        An operation represents the logic required to process messages in order to complete a unit of work (Figure 6).

Figure 6. The scope of an operation within a process.

Components of SOA

·        A service represents a logically grouped set of operations capable of performing related units of work.

·        A process contains the business rules that determine which service operations are used to complete a unit of automation. In other words, a process represents a large piece of work that requires the completion of smaller units of work.

Figure 7. Operations belonging to different services representing various parts of process logic.

SIGNIFICANCE:

The SOA is important because without this no service can be provided to the user easy and efficiently

APPLICATION AREA:

The service oriented architecture is used in all the web oriented service application in internet.

GLOSSARY:

CSA: client server architecture

DIA: Distributed internet architecture

SOA: service Oriented Architecture

SOAP: Simple object access protocol