Internet Engineering Tomasz Babczy ński, Zofia ... · Presentation Tier JSP Pages, servlets, and other user interface elements Business Tier EJB components and other business objects

InternetInternet EngineeringEngineering

Tomasz BabczyTomasz Babczyńński, ski, ZofiaZofia KruczkiewiczKruczkiewiczTomasz KubikTomasz Kubik

InformationInformation systems systems modellingmodelling–– UML and UML and service description languagesservice description languages

I. Design patterns used to build the Integration

TierD.Alur, J.Crupi, D. Malks, Core J2EE. Desin Patterns

1. The definition of the Integration Tier – a five-tiered model of logical separation of tasks

2. Basic Integration Tier design issues

3. Bad practices when designing the IntegrationTier

4. Analysis of basic design issues

Design patterns used to build the Integration



Multitiered Information System by D.Alur, J.Crupi, D. Malks, Core J2EE. Desin Patterns

Client Tier

Customer applications, applets, elements of

the graphical user interface

Presentation Tier JSP Pages, servlets, and other user

interface elements

Business Tier EJB components and other business

objects

Integration Tier JMS, JDBC, connectors and connections

with external systems

Resource Tier Databases, external systems and other

resources

Interacting with the user, device and user interface

presentation

Login, session management, content creation and delivery,

formatting and validation

Business logic, transactions, data and services

Resource adapters, external systems, mechanisms for

resource, control flow

Resources, data and external services

EIS (Enterprise Information System ) Tier(Tutorial Java EE 5)

Business Tier

Application Client

And Optional

JavaBeans

Components

Web Browser,

Web Pages,

Applets, and

Optional

JavaBeans

Components

Client Tier

Java EE

Server

EIS Tier Database and

Legacy Systems

Java Persistence Entities

Session Beans

Message-Driven Beans

Web Tier

Web Pages

Servlets

JavaBeens

Components

(Optional)





Basic issues of Integration Tier design

1. Managing access to data

2. Managing connections to a database - the pool calls

Managing access to data (1)

• Data access code is embedded in the Presentation Tier or Business Tier, which is used for other purposes such as:

– Servlet, EJB component– As a result, these classes are occupied with additional

functions, performance and scalability. It would be better to introduce the Integration Tier and affecting place the code to access data there.

• Data access code is located in a tier of integration, but does not cache the results obtained during the various accesses to databases.– If you need to increase scalability and improve performance,

cache processing results in a database, avoiding duplication of operations directly at the database level.

Managing access to data (2)

•Data access code is extracted from the classes that are used to

meet other objectives

•Data access code should be placed logically and physically closer

to a data source

Any class

Code of Data Access

Client, Presentation or Business Tier

ResourceTier

ResourceTier

Data Bases

Data Bases

Any class

Code of Data Access

Client, Presentation or Business Tier

Integration Tier

Manage connections to a database - the pool calls

Connections

returned to

connection

pool

Client,

Presentation or Business

Layer

Resource

Layer

DAO

DAO

DAO

Data Bases

Client, Presentation or

Business Layer

Resource

Layer

Data Bases

DAO

DAO

DAO

Used active connection

Active connections

Used active

connection

Active connections

Database connections are not

shared, which decreases

performance and scalability.

The pool of shared connections

improves performance and scalability






Bad practices

• Performing data validation

• Data structures from Presentation Tier are available

• Data structures from Business Tiers are available

• Sharing the Presentation and Business Tiers of objects an active connection to the database

• Direct integration of exception handling in the tiers of the presentation and business

• To transmit data between Presentation and Business Tiers and the tier of integration is not used auxiliary object class

• No encryption of sensitive data






4. Analysis of Basic design issues

Design cases

1. Hiding data access logic in a separate tier

2. Separation of persistence mechanisms from the

object model

3. Asynchronic calls of services

4. Facility of access to services by using the XML

Langugew and internet protocols

Problem 1 – Hiding data access logic in a separate tier.

Data Access Object

Client Tier

Servlets,JSP

Business Tier

ClientBusinessDelegate

1

DataBase

ResourceTier

Code of Data Access

Integration Tier

Presentation Tier

Servlets and JSP with presentation logic and

controller to separate layers

Session Component with business logic

Data Acces logic with

direct accesss to databases

Session Component

relational or

object-oriented

database, LDAP,

file system,

repository XML

Architecture of information system

Requirements

• You need to implement data access mechanisms to retrieve and modify data in the permanent storage

• The persistent storage system should be separated from the rest of application - it does not disclose exceptions, data structures, objects related to types of sql libraries

• You should create an uniform interface to access data stored in various sources for example. in RDBMS, LDAP, OODB, XML repository, flat file

• Data access logics should be organized and data access functionsshould be hidden in one location to achieve greater portability and ease of maintenance code

• It can be stateless

• It does not cache data obtained during data collection

Implementation

• Custom data access object

• Data Access Factory

• A collection of transfer objects

• Buffered collection of lines

• Collection of read-only

• lines Wrapper List (Wrapper Rowset List)

Result

• Hides data access

• Creates object-oriented mechanisms for data access and conceals of database schemas

• Facilitates data migration by replacing the DAO Tier

• Reduces the complexity of client code

• Introduces an additional tier

• Puts all the data access code inside a separate tier

• A design requires a hierarchy of classes

• Introduces complexity for the use of object-oriented data access methods

implements

the CRUD

operations

relational or object-

oriented database,

LDAP, file system,

repository XML result of a query

Download data

Insert data

Update data

Delete data

Problem 2 – The separation of persistence mechanisms

from the object model. Domain Store

Possible solutions of persistence mechanisms

• No object model exists - a solution to the problem 1

• Persistence mechanism is implemented in containers, which are objects of "entity" (strategy-CMP Container-Managed Persistence) - no inheritance in the object model

• Persistence mechanism is implemented at the premises of "entity" (strategy BMP - Bean-Managed Persistence); code of persistence mixed with the object model (no inheritance)

• The mechanism of persistence is placed in the object model of "entity" - code of persistence mixed with the object model

• The mechanism of persistence is separated from the object model of "entity" based on all object-oriented patterns

Model of Business Tier based on 2, 3, 5 solutions of persitsence

C lien t

Bu sin ess

lo gic

Se ss io n

F ac ade as Se ss io n

F acad e

T ransa c tion L og ic m anag ed by

Se ssion C om pon ent,

s pe cia l com pon en ts

o r C on tene r

C l ient or P resen ta tion

T ie r B usin ess T ie r

Co mpon entEnti ty A

C omp onentEn tity B

Co mpon entEnti ty C

Architecture of 5-tiered information system

Servlets,

JSP

Client

Entity

Component

Business

Delegate 1 Data

Base

Code of Data Access

Servlets and JSP with

presentation logic and controller to separate layers

Session Component with business logic, Entity Components as

persistence transaction objects

Data Acces

logic with JPA accesss to

databases

Session Component

Client Tier

Business Tier

Resource

Tier

Integration

Tier Presentation Tier

Requirements

• Implementation of persistence mechanisms in business objects such as "entity " should be avoided

• It should be refrained from objects of type "entity" that use the persistence mechanisms of the container.

• The application can run in a web container.

• Object models use inheritance and complex relationships.

• The mechanism of persistence can be realized in two ways:

– make your own skeleton of persistence

– or use a out-of-box solutions based on JDO or own O-R solutions,

Result

• Create custom implementation of persistence is a complex task• Loading and saving multi-level tree of objects requires

optimization• Allows you to better understand the mechanisms of persistence

principles• Advanced mechanisms for persistence may be too powerful for a

simple object model• Facilitated testing of object model• Separation of business object model from the persistence logic

Implementation

• Custom implementation of persistence• Downloading of the on-demand• JDO (Java Data Object)

Data model

Business Tier

Create and persist business object

Download data

Create and perform the Query

II. Example of multitiered web application

1. Two examples of architectures of the multitieredapplication as the Visual Web Java Server Pagesapplications

2. The Visual Web Java Server Pages applicationbased on synchronization data by application

2.1. Structure of project

2.2. Business Service Subtier

2.3. Application Service of Business Tier

2.4. Integration Tier

2.5. Presentation Tier

Example of multitiered web application

1. Two examples of the architectures of the

multitiered application as the Visual Web Java

Server Pages applications

JavaServer Faces Standard Request-Response Life Cycle

Example of the architecture of web application based on

synchronization data by databases (1)

ApplicationBean1

Application Service

Sun pattern

SessionBean1 Session Facade

Sun pattern

JSF Pages JSF Pages JSF Pages

Client1 Client2 Client3

Data base

Library

Directory

Object Model Gof Patterns: Facade: TFacade Factory: TFactory Flyweight: TTitle_book

Integration Layer (EntityManager,…)

TopLink Gof and Sun Patterns: Domain Store Transfer Object Facade (XXXController) Factory


Sun pattern


Sun pattern

Object Model Gof Patterns: Facade: TFacade Factory: TFactory Flyweight: TTitle_book



Object Model Gof Patterns: Facade: TFacade

Factory: TFactory Flyweight: TTitle_book



Resource

Tier

Integration

Tier

Business

Tier

Presentation

Tier

Client

Tier

Architecture of web application based on

synchronization data by databases (2)

• many clients of the Client Tier as the www pages

• many JSF pages of the Presentation Tier – each client has ownpages

• many Session Facade Components of the Business Tier(SessionBean1) as remote facades of the Business Service Subtier (Java Application project) based on the POJO objects –each client has own SessionBean1 and the own Business Service Subtier

• own Domain Store Components of the Integration Tier

Applicat ionBean1 Application Service

Sun pattern

SessionBean1

Session Facade

Sun pattern

JSF Page JSF Page JSF Page

Client1 Client2 C lient3

Data Base

Library Directory

Object Model Gof Patterns:

Facade: TFacade Factory: TFactory Flyweight: TTitle_book

Integration Layer (EntityManager,…) TopLink Gof and Sun Patterns: Domain Store Transfer Object

Facade (XXXController) Factory

SessionBean1

Session Facade

Sun pattern

SessionBean1

Session Facade

Sun pattern

Resource

Tier

Integration

Tier

Business

Tier

Presentation

Tier

Client

Tier

Example of the architecture of web application based on

synchronization data by application (1)

Architecture of web application based on

synchronization data by application (2)

• many clients of the Client Tier as the www pages

• many JSF pages of the Presentation Tier – each client has ownpages

• common Application Service Component of the Business Tier(ApplicationBean1) as the remote facade of the Business Service Subtier (Java Application project) based on the POJO objects – each client uses the common ApplicationBean1

• common Domain Store Components of the Integration Tier

Example of multiered web application

1. Two examples of architectures of the multitiered

application as the Visual Web Java Server Pages

applications

2. The Visual Web Java Server Pages application

based on synchronization datas by application


Integration

Tier:

Facades of

Domain Store

Business Tier:

Business

Service Subtier

as Application

Service with

Object model

Presentation

Tier:

JSF pages

Business Tier:

Application

Service

Presentation

Tier

Business Tier:

Session Façade

Application Service

Classes of

Presentation Tier

Business Tier

Integration Tier




applications





Classes

of

Business

Service

Subtier

Facade of

Business Service Subtier

as POJO class (1):

business logic methods

of subtier

Facade of


as POJO class (2):

business logic methods of

subtier

Facade of


as POJO class (3):

summarization of business logic

Example of Entity class from

Object Model of

Business Service Subtier (1):

Persistence Annotation

Example of Entity class from

Object Model of

Business Service Subtier (2):

business logic methods




applications






binding data

of JSF

Component

remote method for methods of





applications







Example of

Controller class as

Facade of

Integration Tier

Tables generated from

Entities of Object Model of

Business Service Subtier by

Domain Store Components of

Integration Tier

Example of multiered web application

1. Two examples of architectures of the multitieredapplication as the Visual Web Java Server Pages applications

2. The Visual Web Java Server Pages applicationbased on synchronization datas by application





2.5. Presentation Tier

Links to other pages of web

application

addtitle_action

Method of event: the click of

the addtitle button

Method of www response

Methods the FragmentBox

Component as the subview

of the Titles form view

storetitle_action

Method of event: the click of

the storetitle button

Method of www response

Documents

Internet Engineering Tomasz Babczy ński, Zofia ... · Presentation Tier JSP Pages, servlets, and other user interface elements Business Tier EJB components and other business objects