Copyright © 2012 Accenture All Rights Reserved.Copyright © 2012 Accenture All Rights Reserved. Accenture, its logo, and High Performance Delivered are trademarks of Accenture. Application Delivery Fundamentals 2.0: Java Module 21: Introduction to Elements of Enterprise Architecture

Copyright © 2012 Accenture All Rights Reserved. Module Objectives (1 of 2) At the end of this module, you will be able to: Explain the purpose of Enterprise Application Tiers. Describe the differences between a tier and a layer. Describe the differences between multi-tier architecture and multi-layer architecture. Describe the dependency principle of multi-layer architecture. Identify various multi-tier architecture models. 2

Copyright © 2012 Accenture All Rights Reserved. Module Objectives (2 of 2) At the end of this module, you will be able to: Describe the role of each tier within the Java EE application. Distinguish between logical and physical separation of tiers. Describe the rationale behind multi-tier and multi-layer applications. 3

Copyright © 2012 Accenture All Rights Reserved. Agenda This module will cover the following topics: Introduction to the Elements of EA Tiers and Layers Multi-tier/Multi-layer Architecture Multi-layer Architecture Dependency Principle Multi-tier Architecture Models Core Java EE Application Tier Roles Logical/Physical Separation of Tiers Multi-tier Vs. Multi-layer Applications Summary 4

Copyright © 2012 Accenture All Rights Reserved. [Half-page image. Size: 9.53cm x 25.4cm, Position: 0,0] “Enterprise Architecture (EA) is about understanding all of the different elements that go to make up the enterprise and how the elements inter-relate.” – Institute for Enterprise Architecture Developments Introduction to the Elements of EA (1 of 2) 5

Copyright © 2012 Accenture All Rights Reserved. Introduction to the Elements of EA (2 of 2) Application Client JSP Pages Dynamic HTML Pages Java Beans Database Client Tier Web Tier Business Tier EIS Tier Client Machine J2EE Server Machine Database Server Machine J2EE Application 2 J2EE Application 1 6

Copyright © 2012 Accenture All Rights Reserved. [Half-page image. Size: 9.53cm x 25.4cm, Position: 0,0] Layers refer to the logical organization of code. Tiers refer to the physical organization of the code. Tiers are places where layers reside. Tiers and Layers 7

Copyright © 2012 Accenture All Rights Reserved. Tiers and Layers TiersLayers Refer to physical separation.Refer to logical separation. Live in distinct processes or machines.Live typically within the same process and machine. May communicate remotely or locally.Remoting technology is not necessary. Client TierStorage Tier Business Layer Presentation Layer Storage Layer 8

Copyright © 2012 Accenture All Rights Reserved. Multi-tier/Multi-layer Architecture Multi-tier architectureMulti-layer architecture Tiers are physical separation and units of deployment. Examples are exe, archives, etc. Layers are the logical separation and units of design. One tier can be deployed to many machines.Layers are elements of design and help to obtain modularity and separation of concern. Multiple tiers can be deployed on one machine. Elements of layers are grouped as package and classes. Tier 1 Tier 2 Tier n Layer 1 Layer 2 Layer 3 Layer n 9

Copyright © 2012 Accenture All Rights Reserved. [Half-page image. Size: 9.53cm x 25.4cm, Position: 0,0] Definition of the Dependency Principle: Each layer depends on the layer below and not on the one above. Platform changes affect only the layer that runs on it. Multi-layer Architecture Dependency Principle 10

Copyright © 2012 Accenture All Rights Reserved. Multi-layer Architecture Dependency Principle An Example. This diagram is an example of the Dependency Principle in layers. Dependency Dependencies Client layer Presentation layer Model layer Persistence layer 11

Copyright © 2012 Accenture All Rights Reserved. Multi-layer Architecture Dependency Principle Dependency Principle – Violation Dependency The following code is an example depicting a violation of the Dependency Principle. 12

Copyright © 2012 Accenture All Rights Reserved. Multi-layer Architecture Dependency Principle Direct Dependency Business Delegate pattern: Weakens dependency of the Presentation layer on the Model layer. Encapsulates all Model Layer information required by presentation layer. Clients Lookup Service Business Delegate Business Service Uses Lookup/Create 13

Copyright © 2012 Accenture All Rights Reserved. Multi-tier Architecture Models: One tier 14

Copyright © 2012 Accenture All Rights Reserved. Multi-tier Architecture Models: Two tier Presentation Layer Model Layer Persistence Layer Drivers and Adapters 15

Copyright © 2012 Accenture All Rights Reserved. Multi-tier Architecture Models: Three tier Presentation layer Business layer Persistence layer and 16

Copyright © 2012 Accenture All Rights Reserved. Multi-tier Architecture Models: Multi-tier Java EE 17

Copyright © 2012 Accenture All Rights Reserved. [Half-page image. Size: 9.53cm x 25.4cm, Position: 0,0] Many applications can be described in terms of their tiers. The application functionality is built across such tiers. Core Java EE Application Tier Roles (1 of 2) 18

Copyright © 2012 Accenture All Rights Reserved. Core Java EE Application Tier Roles (2 of 2) The five different physical tiers and their responsibilities are displayed below. Represents the system and/or devices. Responsible for encapsulating UI displays, presentation logic, and invoking application business services. Responsible for providing business services. Responsible for communicating with the external resources. Responsible for storing business data. Presentation Tier Client Tier Business Tier Integration Tier Resource Tier 19

Copyright © 2012 Accenture All Rights Reserved. [Half-page image. Size: 9.53cm x 25.4cm, Position: 0,0] The ability to separate the logical and physical tiers is a crucial factor to the long-term viability of a system. Logical/Physical Separation of Tiers 20

Copyright © 2012 Accenture All Rights Reserved. Logical/Physical Separation of Tiers Logical Separation This diagram displays tiers distributed in terms of software infrastructure. 21

Copyright © 2012 Accenture All Rights Reserved. Logical/Physical Separation of Tiers Physical Separation This diagram displays tiers distributed across different types of hardware. 22

Copyright © 2012 Accenture All Rights Reserved. Multi-tier Vs. Multi-layer Applications Physical Independence: Can be deployed to different servers. Can run distributed application components on the computers best suited to their individual computing requirements. Logical Independence: Layers can be changed without impacting other modules. Physically Independent Logically Independent Use Common Services Rationale TierYes Use common services Supports Component distribution LayerNot necessarilyYesNo Modularity Separation of Concerns 23

Copyright © 2012 Accenture All Rights Reserved. Exercise - NewCodington Application Mapping to EA Tiers (1 of 2) Fill in the blanks in the following sentences: A. ______ are the logical separation and unit of design. B. The ___________ is responsible for storing business data. Definition: “Each layer (Presentation, Model, and Persistence) can depend on the layer below and not on the one above.” C. The definition above is known as Multi-layer ___________ Principle. D. The ________ Tier is responsible for providing business services. 24 Layers Resource Tier Dependency Business

Copyright © 2012 Accenture All Rights Reserved. Exercise - NewCodington Application Mapping to EA Tiers (2 of 2) In the image below find the suitable terms for A, B, C, D and E from the following list of terms: Presentation Tier Browser Business Tier Integration Tier MySQL 25 Presentation Tier Integration Tier Business Tier MySQL Browser

Copyright © 2012 Accenture All Rights Reserved. Questions and Comments 26

Copyright © 2012 Accenture All Rights Reserved. Module Summary (1 of 2) Different tiers work together within an Enterprise Architecture model. Dependency Principle means that the layer above depends on the layer below. Business Delegate pattern weakens the dependency between layers using decoupling. Different configurations and interactions within one-, two-, three- and n-tier architectures. 27 The key points from this module are:

Copyright © 2012 Accenture All Rights Reserved. Module Summary (2 of 2) Each of the five physical tiers have their own separate responsibilities. Physical and Logical independence can occur between multi-tier and multi-layer applications. Each layer and tier has a different role within the Java EE application and each has its own distinct attributes. 28