soa bratislava soa part1 lecture 3 dr. withalm 11-sep-15

SOA BratislavaSOA Bratislava

SOA Part1 Lecture 3SOA Part1 Lecture 3

Dr. Withalm Apr 22, 2023

04/22/23 Dr.Withalm2 SOA Bratislava

Lectures at the University of Bratislava/Autumn 2009

28.09.2009 Lecture 1 Evolution Of Architectures- The long Way from OO to SOA

05.10.2009 Lecture 2 WEB-Services& Semantic WEB

12.10.2009 Lecture 3 SOA-Technological Basis

19.10.2009 Lecture 4 SOA-Basing on J2EE

23.11.2009 Lecture 5 SOA-Focus on Business Processes

30.11.2009 Lecture 6 B2B Frameworks and related Standards

07.12.2009 Lecture 7 WEB 2.0 & GRID


Today’s Agenda

Overview of SOA

SOA and WS and related Technologies

Future of WEB Applications

Event-Driven Business Processes


Summary of lecture 2

Business needs request Web Services

EAI : enables the integration of different applications within a company

Prevailing standards/technologies are CORBA, COM,..

Web Portals: enable Internet users to order products/services

Prevailing standards/technologies are HTTP, CGI, Servlet, Applets

Web Services: enable different applications to order products/services

Standards are the dark side of WS

Different standardization bodies: influenced by the big vendors

Most used and established are : SOAP, WSDL, and UDDI

SOA: enables not only synchronous mode

Semantic Web: Ontology, Agents and Languages as OWL, RDF

Ontology: most likely to be established in specific domains

Obstacles : not only technical but also political


Service-Oriented Architecture

Developers will shift their focus to business processes and away from software functionality. Software will become a facilitator of rapid business change, not an inhibitor.

The value creation in software will shift to subscription services and away from packaged software, and to composite applications (i.e., best of breed) and away from monolith suites.

(Source: Gartner August 2005)


Service Oriented Architecture (SOA)/1

The term Service-Oriented Architecture (SOA) expresses a software architectural concept that defines the use of services to support the requirements of software users.

In a SOA environment, nodes on a network make resources available to other participants in the network as independent services that the participants access in a standardized way.

Most definitions of SOA identify the use of Web services (using SOAP and WSDL) in its implementation.

However, one can implement SOA using any service-based technology.


Service Oriented Architecture (SOA) /2

Unlike traditional object-oriented architectures SOA comprise loosely joined, highly interoperable

application services. Because these services interoperate over different

development technologies (such as Java and .NET), the software components become very reusable.

SOA provides a methodology and framework for documenting enterprise capabilities and can support integration and consolidation activities.

SOA is not a product, although several vendors offer products which can form the basis of a SOA.


Service Oriented Architecture (W3C)

A distributed system, consists of discrete software agents that work together to implement some intended functionality. Those agents in a distributed system communicate by hardware/software protocol stacks.

Transport

Service

Description


SOA Core Principles

Business Driven The business drives the services, and the services

drive the technology. Bussiness Agility

Business agility is a fundamental business requirement.

Constant Change A successful SOA is always in flux.


Business Driven

The business drives the services, and the services drive the technology.

In essence, services act as a layer of abstraction between the business and the technology.

The service-oriented architect must understand the dynamic relationships between the needs of the business and the available services on the one hand, as well as the technical underpinnings that offer the layer of abstraction required by the services.


Business Agility

Business agility is a fundamental business requirement.

Instead of dealing with concrete requirements from

business, SOA considers the next level of abstraction:

The ability to respond to changing requirements is

the new ''meta-requirement.''

The entire architecture -- from the hardware on up --

must reflect the business agility requirement.


Constant Change

A successful SOA is always in flux.

To visualize how a SOA is supposed to work, it is better to think of a living organism or an ecosystem rather than the traditional ''building a house'' metaphor that gave software architecture its name.

IT environments are in a constant state of change, so the

work of a service-oriented architect is never done.


The Service Fabric

All different services available inside or outside an organization can be seen as a large network of computing resources where each node is providing a distinctive service to users and programs alike – the network becomes a service fabric – the ecosystem for the enterprise.


The New Application

The application as a network of services - the whole is more than the sum of its parts…


Vision

The future of the application is the virtual collection of services based on the Service Oriented Architecture developed and enhanced on demand and made available for service consumption in the service fabric of the Internet of tomorrow.


Service Categories

User (Interface) Services Business (Logic) Services Data (Backend) Services


User Services

UserService

BusinessService

BusinessService

BusinessService


Business Services

The programmatic access of a service and its (business) functionality is the main aspect of a service - often called a Business Logic Service.

This Business Service has to provide a distinctive service to its service consumers and can utilize other services to fulfill its task.

BusinessService


Data Services

The data store is accessed through standardized protocols and is exchanging data in XML format.

BusinessService

Data (Backend) Service


Service Manager Pattern

The service manager acts not only as a proxy for the business component but depending on the capabilities of the web server and

component container might also manage several other activities important to the delivery of web service

such as data and protocol translation, security, or state management.

ServiceClient

ServiceManager

ServiceImplementation


Aggregation

BusinessService

BusinessService

BusinessService

BusinessService


Integration

DataStore

BusinessService

Messages

Component


Orchestration

BusinessService

BusinessService

BusinessService

BusinessService


Services Orchestration and Choreography /1

No service is an island.

The key point about service-oriented computing is

that involves extended, loosely coupled activities

among two or more autonomous business partners.

Such activities can be thought of

as (business) processes that engage several services in a manner

that brings about the desired (business) outcome.



Web services are rapidly emerging as the most practical approach

for integrating a wide array of customer, vendor, and business-partner applications.

While many companies have begun to deploy individual Web services,

the real value will come when enterprises can connect services together,

providing higher value to an organisation.



In order to communicate and integrate services

for achieving a collaboration between enterprises,

it will be necessary to coordinate them,

which involve the necessity of offering support to the services composition.

Early experience shows that to make the most of new Web services investments

there must be a standard approach to Web services composition.


Services Orchestration and Choreography /4Orchestration/1

Refers to an executable business process

that may interact with both internal and external Web services.

Orchestration describes how Web services can interact at the message level,

including the business logic and execution order of the interactions.


Services Orchestration and Choreography /5Orchestration/2

These interactions may span applications and/or organisations,

and result in a long-lived, transactional process.

With orchestration, the process is always controlled

from the perspective of one of the business parties.

It takes the view of a process as a program or a partial order of operations

that need to be executed.


Services Orchestration and Choreography/6Choreography/1

More collaborative in nature,

where each party involved in the process

describes the part they play in the interaction.

Choreography tracks the sequence of messages

that may involve multiple parties and multiple sources.


Services Orchestration and Choreography/7Choreography/2

It is associated with the public message exchanges

that occur between multiple Web services.

this takes the view of a process as being

a set of message exchanges between participants.


Services Orchestration and Choreography/8



Orchestration differs from choreography in that it describes

a process flow between services,

controlled by a single party.

More collaborative in nature (see above Figure),

choreography tracks the sequence of messages

involving multiple parties,

where no one party truly “owns” the conversation.



It could be distinguished as Orchestration defines procedure

and Choreography defines protocol.

Above figure shows this issue,

where in "orchestration" there is a defined flow of processes

that will be executed,

and in "choreography" each WS knows

how it should act when an event comes in.


Aggregation Tier

PresentationService

AggregationService

Presentation Tier

Aggregation Tier

Business Logic Tier

Data Tier

BusinessService

BusinessService

DataService


ObjectProgram

ComponentHomogeneous Application

Service-Oriented ArchitectureSmall Enterprise, Complex Applications

Web ServicesB2B Market, Global Enterprise

ORB

MOM

Typical Access Via:

OOD

CBD

SOA

Tim

e

HTTP + XML

Evolution of Application Deployment Styles

Source: 2003


Programming Paradigm

It is there and running, simply connect and use.

Print Service

Service Consumer

Archiving Service

Back Office Service

Put together to build a complex device

Wire together to build a small device

Programming Paradigm

Object Orientation:Aligned with fine-grained business objects Reuse of source code based on the notion of typesIncreased maintainability and modifiability of the program code through encapsulationComponent Orientation:Aligned with mid-grained business functions Reuse based on prefabricated, executable codeIncreased maintainability and modifiability of the application through compositionService Orientation:Aligned with coarse-grained business processesFlexibility and extensibility through composition, federation, and orchestration of servicesIncreased interoperability and scalability through loose-coupling

Real World Analogy


Programming Approaches/1Declarative programming

describes only the problem inference mechanism tries to solve the problem

described provided by the respective program runtime

environment e.g. Prolog


Programming Approaches/2Event-driven programming

reacts to outside events and takes corresponding action typical programs developed with this approach include

graphical user interfaces that react to user input control programs that react to external environmental

conditions, e.g. to changes in temperature


Programming Approaches/3Procedural programming

Represents a sequential algorithm which is being executed step by step

The execution of the algorithm is governed by data which can also be modified by the algorithm


Programming Approaches/4Structured programming

Extension of procedural programming The main problem is broken down into several sub problems

each sub problem is solved Advantage: considerable simplification of individual algorithms

functions, procedures or modules The overall program is also easier to maintain and service


Impact – Development / Project Management

Keeping InvestmentsSmall (Changes)Focus is KnowledgePlatform AgnosticArchitecture Centric

More like CMOngoing ActivityFocus is OperationBusiness Driven


Service-Oriented Architecture

Develop Orchestrate

DeploySecure

Access

Integrate

Manage

Analyze


ROI Improvements

ROI

Time

Objects

Components

Services


Component Concepts

Topics

Standardization Proprietary Proprietary Open

Coupling Tight Tight Loose

Granularity Fine Fine to Coarse Business relevant

Implementation Monolithic Separate Independent

Interfaces Defined Formal Contractual

Objects Components Services


Componentization

ROI

Time

Custom

EAI

Services


Componentization Concepts

Topics

Standardization Proprietary Proprietary Open

Separation Applicationspecific

Applicationindependent

Implementationindependent

Scope Internal Some external Internal/External

Custom EAI Services


Evolution of SOA

Scope

Granularity

Events

Services

Components

Methods

Subroutines

TechnicalComponents

BusinessComponents

Affinity withBusiness Models

(Source: Gartner)


Defining ‘Event’

Ordinary event: Something that happened in the real world. A large or small change in the state of the universe.

Ordinary business event: A meaningful change in the state of the enterprise or of something relevant to the enterprise, such as a customer order, an employee address change, the arrival of a shipment at a loading dock, a bill payment or a truck breakdown.

Software event: A binary record of an ordinary event. Data, often packaged in the form of a message or electronic document, that describes an ordinary event.

(Source: Gartner)


Event-Driven Business Processes

Conventional: Build-to-stock Event-driven: Build-to-order

Conventional: Static pricing Event-driven: Yield management through dynamic pricing

Conventional: Periodic reports and ad hoc inquiry Event-driven: Supply chain monitoring

(Source: Gartner)


Events Are Already Applied in Many Ways

Event-Driven Business Processes (With or Without Computers) Work is triggered by a stimulus from outside.

Event-Driven (or “Message-Driven”) Application Systems An application system organizes its flow around the sending and receiving

of computer events.

Event-Driven System Software Operating systems use event loops to schedule and dispatch internal

services; management tools track the status of hardware and software components by listening to events.

Event-Driven Function in an Application Program A particular section of a GUI application is triggered when a mouse is

clicked on the associated screen icon.

(Source: Gartner)


Business Components: Service-Oriented

Service-Oriented Architecture Interaction Uses interface metadata One-to-one connections Client directs flow Data flows are predictable and linear Closed to unforeseen input once process begins

Client Server

InterfaceProxy

InterfaceStub

(Source: Gartner)


Business Components: Event-Driven

Event-Driven Notification Uses event descriptor metadata Many-to-many connections Sink (recipient) determines flow of logic Dynamic, parallel, asynchronous flows Can react to new external input while process is in

flight

Source SinkEvent

(Source: Gartner)


Business Component Architecture

SOA Interaction Coupled Conversational Subordinate Closed-ended

EDA Notification Decoupled Notification/subscription Autonomous Open-ended

(Source: Gartner)


Business Components - Five Patterns

SOA InteractionConversational

Request/Reply

ProgramA

ProgramB

“Microflow” Process

ProgramA

ProgramB

Call

Return

ProgramA

ProgramB

Send

Receive

ProgramA

ProgramB

Put

GetQueue

Event NotificationMessage Passing

Store and Forward

Publish and Subscribe ProgramA

ProgramB

ProgramB

Publish

Subscribe

Coupled

De-Coupled


Enterprise Service Bus (ESB)

An Enterprise Service Bus is an emerging standard for integrating enterprise applications in an

implementation-independent fashion at a coarse-grained service level (leveraging the

principles of service-oriented architecture) via an event-driven and XML-based¹ messaging

engine (the bus). An enterprise service bus generally provides an

abstraction layer on top of an Enterprise Messaging System which allows integration architects to exploit the value

of messaging without writing code.


ESB - Overview

In an ESB, applications and event-driven services are tied together in a loosely coupled fashion. This allows them to operate independently from one another while still providing value to a broader business function.


Service and Service Container

Ser vi ce

Service Container

Invocation and Management Framework

Service Endpoint

Service Messaging System(Enterprise Service Bus - ESB)

Methods

Service Interface


Service Variations

ESB

SOAP

HTTP

WS

Se

rv ice

Ap

plic

at io

n

Se

rv ice

Se

rv ice

We

b S

erv

ice

Ap

plica

t ion

Se

rv ice

Java

Java C# C++


System Configuration and Monitoring

Service Container

Invocation and Management Framework

Ap

plic

atio

n

Cu

sto

m

Serv

ice

We

b S

erv

ice

Brid

ge

Ad

ap

ter

HTTPXXXX

Cu

sto

m

Se

rvic

e

SystemConfiguration

System Diagnostics&

Monitoring

Discovery&

Configuration

ESB


Summary

Service Oriented Architecture (SOA) is an important step towards flexible and scalable solutions. Especially when seen not just as another RPC mechanism but rather as a message based communication means between business components.

The link with well-known Internet technologies is the foundation for the development of new applications and the backbone of integration with existing solutions.

The use of SOA and the integration of rich internet applications (RIA) is the cornerstone of the next generation of Web Applications.

SOA BratislavaSOA Bratislava

Thank youfor your attention!


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soa bratislava soa part1 lecture 3 dr. withalm 11-sep-15

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