Business delegate pattern: Difference between revisions

Revision as of 00:01, 22 June 2016

Revision as of 12:35, 22 June 2016

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'''Business delegate''' is a [[Java Platform, Enterprise Edition|Java EE]] design pattern.

<ref name=":o_cjp">{{Cite web|url = http://www.oracle.com/technetwork/java/businessdelegate-137562.html|title = Core J2EE Patterns - Business Delegate|date = |accessdate = 22 June 2016|website = Oracle|publisher = Oracle|last = |first = }}</ref> This pattern is directing to reduce the [[Coupling (computer programming)|coupling]] in between business serives and the connected presentation-tier, and to hide the implementation details of services (including lookup and accessabilityaccessibility of [[Enterprise JavaBeans|EJB]] architecture.<ref name=":o_cjp"/><ref name=":stdd">{{Cite book|title = Screening Technical Design Document - Version 2.0|last = |first = |publisher = Indiana state|year = |___location = Indiana, USA|volume = |pages = 7}}</ref> Business delegates acts as an adaptor to invoke business objects from the presentation tier.<ref name=":pjeesp">{{Cite book|title = Pro Java EE Spring Patterns|last = Kayal|first = D.|publisher = Apress|year = 2008|___location = New York|volume = |pages = 161-166161–166}}</ref>

==Structure==

Requests to access underlying business services are sent from clients, and lookup services are used by business delegates to locate the business service components.<ref name=":o_cjp"/>

===Components===

Basic components are Business delegate, Lookup service and business service.

====Business delegate====

Control and protection are provided through business delegate which can have two types of constructures, without ID and with ID, where

ID is a string version of the reference to a remote object such as EJBHome or EJBObject.<ref name=":o_cjp"/>

====Lookup Service====

Business service is located by lookup service which is used by the business delegate. the implementation details of business service lookup is encapsulated by lookup service.<ref name=":o_cjp"/>

====Business Service====

This a business-tier component, such as an enterprise bean or a JMS component, which provides the required service to the client. <ref name=":o_cjp"/>

==Consequences==

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* More flexibility and maintanability as intermediate business delegate layer decouples the business layer from the presentation layer.

* Business delegate exposes a uniform API to the presentatoinpresentation tier to access business logic.<ref name=":pjeespo_cjp"/><ref name=":o_cjppjeesp"/>

==Concerns==

FollwingFollowing concers can be considered:

* Maintenance due the extra layer that incresesincreases the number of classes in the application.

* Business delegate should take care of the changes of the remote business object interfaces, and these types of changes are rare.<ref name=":pjeesp"/>

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Resource Delegate:

<Source lang="java">

public class ResourceDelegate {

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Remote interface for ResouceSession:

<source lang="java">

public class ResourceDelegate {

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{{Design Patterns Patterns}}

[[Category:Software design patterns]]