CS 415 N-Tier Application Development By Umair Ashraf July 5,2013 National University of Computer and Emerging Sciences Lecture # 8 Introduction to Service Oriented architecture

Agenda/Contents for Today’s Lecture  SOA Introduction  SOA Myths and Facts  Evolution of SOA  Understanding Services  SOA Reference Model  Examples

Service Oriented Architecture (SOA) SOAs are like snowflakes – no two are alike.” - David Linthicum

Introduction to SOA  The SOA Elephant  SOA is a bit like John Godfrey Saxe’s poem about the blind men and the elephant.  The man touching the trunk believes it to be a snake  The man touching the tusk believes it to be a spear  The man touching the ear believes it to be a fan  The man touching the elephant’s side believes it to be a wall  The man touching the tail believes it to be a rope  The man touching the legs believes they are trees.

Problems addressed by service oriented architecture

Definitions for SOA  A loosely-coupled architecture designed to meet the business needs of the organization.  A set of components which can be invoked, and whose interface descriptions can be published and discovered (W3C).  A paradigm for organizing and utilizing distributed capabilities that may be under the control of different ownership domains. It provides a uniform means to offer, discover, interact with and use capabilities to produce desired effects consistent with measurable preconditions and expectations. (OASIS)

Simple Definition - SOA A method of design, deployment, and management of both applications and the software infrastructure where:  All software is organized into business services that are network accessible and executable.  Service interfaces are based on public standards for interoperability.

Characteristics of SOA  Quality of service, security and performance are specified.  Software infrastructure is responsible for managing.  Services are cataloged and discoverable.  Data are cataloged and discoverable.  Protocols use only industry standards.

What is a service ?  A Service is a reusable component.  A Service changes business data from one state to another.  A Service is the only way how data is accessed.  If you can describe a component in WSDL, it is a Service.

SOA Myths and Facts

Example – A City  Let's take your average cosmopolitan city.  It is already full of service-oriented businesses. Individual companies are service-oriented in that each provides a distinct service that can be used by multiple consumers.  Collectively, these businesses comprise a business community.  It makes sense for a business community not to be served by a single business outlet providing all services.  By decomposing the community into specialized, individual outlets, we achieve an environment in which these outlets can be distributed.

SOA-Loose Architecture For services to interact and accomplish something meaningful, they must exchange information. A communications framework capable of preserving their loosely coupled relationship is therefore required. One such framework is messaging. After a service sends a message on its way, it loses control of what happens to the message thereafter. That is why we require messages to exist as "independent units of communication." This means that messages, like services, should be autonomous.

The Evolution of SOA Service Orientation (SO) is the natural evolution of current development models  The, 80s saw object-oriented models  Component-based development model in the 90s  Now we have service orientation (SO)

The Evolution… From Three-Tier Applications Presentation Layer Databases Application Business Layer

The Evolution to: SOA-Based Applications Databases Presentation Process #1 Process #2 Process #3 Service Components

Calls for a Paradigm Shift Service Oriented Architecture Functionality Driven Long development cycles Tightly Coupled Application Specific Designed to last Data Oriented Traditional Architecture Process Oriented Iterative development Loosely Coupled Heterogeneous Designed for change Business Service Oriented       SOA v/s Traditional Architecture But must be built on standards to enhance interoperability

Service-Oriented Architecture: Key Concepts Service A unit of business functionality that can be invoked over the network Web service A service that is called in a standard way, so anyone can use it without knowing its internals “Loosely coupled” When services are self-contained, and can be easily combined and disassembled, they are called loosely coupled. Service- Oriented Architecture A standards-based platform that lets you model, develop, find, and combine services into flexible business processes Orchestration Combining and assembling services into a coherent business process – also known as business process management

DoD Concept How to Organize for SOA Enterprise Information Environment Business Mission WarFighting Mission Intelligence Mission Army, Navy Air Force Agencies Combatant Commands Programs Focus of this Presentation

Organization of Infrastructure Services Infrastructure Services (Enterprise Information) Data Services Security Services Computing Services Communication Services Application Services

Organization of Data Services Data Services Discovery Services Management Services Collaboration Services Interoperability Services Semantic Services

Organization of Security Services Security Services Transfer Services Protection Services Certification Services Systems Assurance Authentication Services

Organization of Computing Services Computing Services Computing Facilities Resource Planning Control & Quality Configuration Services Financial Management

Organization of Communication Services Communication Services Interoperability Services Spectrum Management Connectivity Arrangements Continuity of Services Resource Management

Organization of Application Services Application Services Component Repository Code Binding Services Maintenance Management Portals Experimental Services

A Few Key SOA Protocols  Universal Description, Discovery, and Integration, UDDI. Defines the publication and discovery of web service implementations.  The Web Services Description Language, WSDL, is an XML-based language that defines Web Services.  SOAP is the Service Oriented Architecture Protocol. It is a key SOA in which a network node (the client) sends a request to another node (the server).  The Lightweight Directory Access Protocol, or LDAP is protocol for querying and modifying directory services.  Extract, Transform, and Load, ETL, is a process of moving data from a legacy system and loading it into a SOA application.

SOA Interoperability Goals for the Department of Defense  Interoperability of solutions across the DoD strategic goal.  Rules for sharing of data and services across the enterprise.  Enforcement of standards.  All data, services, and applications shall be accessible, understandable, and trusted.  Global Information Grid for sharing of information with Federal Departments, Department of Homeland Security, the Intelligence Community, state and local governments, allied, coalition, non-governmental organizations (NGOs), academic, research and business partners.

27 Example of Customizable Web Services ( www. salesforce.com )

Fee database Data Services ESB: Routes to appropriate core system DDA / Current Account Internet Banking Business Process: Stop Payment Process Services Orchestration: Business Logic: If Customer_Status = Gold Service_Fee = $8 else Service_Fee = $20 Security: Authenticate userRegistry and Repository: Find Stop Payment Service, Charge Fee service Manage and monitor Banking Examples of SOA

Place customer orders: 1. Basic Data Service – access operations, 2. Composed Services - business logic, 3. Process Services – complex business logic

A Unified Patience Journal System

Why SOA Saves Code  Provides a standard way of interacting with shared software.  Enables software to become building blocks for reuse.  Shifts focus to application assembly rather than design.  Creates new applications out of existing components.  Integrates with applications in other enterprises.

Reference Material 