OpenUP/OpenUP_baseline_EN/exported_HTML_1_0/openup/guidances/guidelines/entity_control_boundary_pattern.html - epf/org.eclipse.epf.nl-libraries - Git at Google

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 Element Name: entity_control_boundary_pattern.xmi<br/><br/>
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 <!-- START:presentationName,_uF-QYEAhEdq_UJTvM1DM2Q CRC: 3808310074 -->Entity-Control-Boundary Pattern<!-- END:presentationName,_uF-QYEAhEdq_UJTvM1DM2Q -->
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 <!-- START:briefDescription,_uF-QYEAhEdq_UJTvM1DM2Q CRC: 1547844432 -->This guideline describes a rapid way to build a design that is robust enough to realize the functional requirements.<!-- END:briefDescription,_uF-QYEAhEdq_UJTvM1DM2Q -->
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 <!-- START:mainDescription,-awaQ_2dwhGyKRoVKQ-esPQ CRC: 3490029770 --><p>
     When identifying the elements for a scenario of system behavior, you can align each participating element with one of
     three key perspectives: <b>Entity</b>, <b>Control</b>, or <b>Boundary</b>. Although specifics of languages, frameworks,
     and heuristics of quality design will drive the final design, a first cut that covers required system behavior can
     always be assembled with elements of these three perspectives.
 </p>
 <p>
     This pattern is similar to the Model View Controller pattern (described here [<a class="elementLinkWithUserText" href="./../../../openup/guidances/supportingmaterials/references_6CCF393.html#BUS96" guid="_9ToeIB83Edqsvps02rpOOg">BUS96</a>]
     and here [<a class="elementLinkWithUserText" href="./../../../openup/guidances/supportingmaterials/references_6CCF393.html#WIKP-MVC" guid="_9ToeIB83Edqsvps02rpOOg">WIKP-MVC</a>], among other places), but the Entity Control Boundary (ECB) pattern is not
     solely appropriate for dealing with user interfaces, and it gives the controller a slightly different role to play.
 </p>
 <h4 align="left">
     ECB&nbsp;pattern example
 </h4>
 <p>
     &nbsp;<img alt="" src="./resources/ebc_diagram.JPG" />
 </p>
 <h3>
     Entity elements
 </h3>
 <p>
     An entity is a long-lived, passive element that is responsible for some meaningful chunk of information. This is not to
     say that entities are "data," while other design elements are "function." Entities perform behavior organized around
     some cohesive amount of data.
 </p>
 <p>
     An example of an entity for a customer service application is a Customer entity that manages all information about a
     customer. A design element for&nbsp;this entity would include data about the customer, behavior to manage the data,
     behavior to validate customer information&nbsp;and to perform other business calculations, such as "Is this customer
     allowed to purchase product X?"
 </p>
 <p>
     The identification of the entities as part of this pattern can be done many times at different levels of abstraction
     from the code, at different levels of granularity in size, and from the perspectives of different contexts. For
     example, you could do an analysis pass on a scenario of creating a marketing campaign and identify the customer element
     with various customer data elements, such as name and address, plus various required behaviors, such as the management
     of the name and address data and the ability to rate the customer based on some algorithm (such an application of this
     pattern would be abstract from code, coarse-grained, and have no specific context). Later, you could do a pass on the
     same scenario applying an architectural mechanism for database access that breaks the address out as its own element,
     moves the responsibility for storing and retrieving customers to a new control element, and identifies specific
     database decisions, such as the use of primary keys in the entities. (Such an application of this pattern would be
     closer to the code, finer-grained, and aligned with a database&nbsp;context.)
 </p>
 <h3>
     Control elements
 </h3>
 <p>
     A control element manages the flow of interaction of the scenario. A control element could manage the end-to-end
     behavior of a scenario. or it could manage the interactions between a subset of the elements. Behavior and business
     rules relating to the information relevant to the scenario should be assigned to the entities; the control elements are
     responsible only for the flow of the scenario.
 </p>
 <p>
     CreateMarketingCapmpaign is an example of a control element for a customer service application. This design element
     would&nbsp;be responsive to certain frontend boundary elements and would collaborate with other entities,
     control&nbsp;elements, and backend boundary elements to support the creation of a marketing campaign.
 </p>
 <p>
     As with the entity example here, there might be many passes over the identification of control elements. A first pass
     might be an analysis pass that identifies one control element for a scenario, with behavior to make sure that the
     design can support the flow of events. A&nbsp;subsequent pass might find controllers to manage reusable collaborations
     of low-level elements that will map to a specific code&nbsp;unit to be written.
 </p>
 <h3>
     Boundary elements
 </h3>
 <p>
     A boundary element lies on the periphery of a system or subsystem, but within it. For any scenario being considered
     either across the whole system or within some subsystem, some boundary elements will be "front end" elements that
     accept input from outside of the area under design, and other elements will be "back end," managing communication to
     supporting elements outside of the system or subsystem.
 </p>
 <p>
     Two examples of boundary elements for a customer service application might be a front end MarketingCampaignForm and a
     back end BugdetSystem element. The MarketingCampaignForm would manage the exchange of information between a user and
     the system, and the BugdetSystem would manage the exchange of information between the system and an external system
     that manages budgets.
 </p>
 <p>
     An analysis pass could identify one boundary element for each external relevant to a scenario. Subsequently, these
     could be broken down into multiple boundary elements or small communities made up of collaborating elements of all
     three stereotypes.
 </p>
 <h3>
     Walking through the scenario
 </h3>
 <p>
     You can walk through a scenario initiated by something outside of the boundaries of the system or subsystem being
     designed and distribute the responsibility to perform behavior supporting the scenario to the elements identified of
     each type. The appropriate design element responsible for each action in the scenario will be as described in the
     definition of each of the element types described here previously.
 </p>
 <p>
     In addition to identifying the behavior necessary to perform the scenario, the initiation of this behavior from design
     element to design element identifies the necessary relationships. There are certain appropriate relations between the
     participating elements. An element can communicate with other elements of the same kind. Control elements can
     communicate with each of the other two kinds, but entities and boundary elements should not communicate directly.
 </p>
 <p>
     This table shows appropriate links between design elements.
 </p>
 <table cellspacing="2" cellpadding="2" width="400" summary="Appropriate Links" border="1">
     <tbody>
         <tr>
             <td>
             </td>
             <th scope="col">
                 <center>
                     Entity
                 </center>
             </th>
             <th scope="col">
                 <center>
                     Boundary
                 </center>
             </th>
             <th scope="col">
                 <center>
                     Control
                 </center>
             </th>
         </tr>
         <tr>
             <th scope="row">
                 Entity
             </th>
             <td>
                 <center>
                     X
                 </center>
             </td>
             <td>
             </td>
             <td>
                 <center>
                     X
                 </center>
             </td>
         </tr>
         <tr>
             <th scope="row">
                 Boundary
             </th>
             <td>
             </td>
             <td>
             </td>
             <td>
                 <center>
                     X
                 </center>
             </td>
         </tr>
         <tr>
             <th scope="row">
                 Control
             </th>
             <td>
                 <center>
                     X
                 </center>
             </td>
             <td>
                 <center>
                     X
                 </center>
             </td>
             <td>
                 <center>
                     X
                 </center>
             </td>
         </tr>
     </tbody>
 </table>
 <p>
     By applying this pattern, you can put a robust design together that identifies the elements, behavior, and
     relationships necessary to support a scenario.
 </p><!-- END:mainDescription,-awaQ_2dwhGyKRoVKQ-esPQ -->
 </body>
 </html>
	<?xml version="1.0" encoding="UTF-8"?>
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	<title>openup&#92;guidances&#92;guidelines&#92;&#92;entity_control_boundary_pattern.xmi</title>
	</head>
	<!-- WARNING: do not modify the generated comments in this file below this line. They are used as markers for the import process. -->
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	Element Name: entity_control_boundary_pattern.xmi<br/><br/>
	<!-- END NON-TRANSLATABLE -->
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	<!-- START NON-TRANSLATABLE -->
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	<!-- END NON-TRANSLATABLE -->
	<!-- START:presentationName,_uF-QYEAhEdq_UJTvM1DM2Q CRC: 3808310074 -->Entity-Control-Boundary Pattern<!-- END:presentationName,_uF-QYEAhEdq_UJTvM1DM2Q -->
	<br/><br/><br/>
	<!-- START NON-TRANSLATABLE -->
	Attribute: briefDescription<br/><br/>
	<!-- END NON-TRANSLATABLE -->
	<!-- START:briefDescription,_uF-QYEAhEdq_UJTvM1DM2Q CRC: 1547844432 -->This guideline describes a rapid way to build a design that is robust enough to realize the functional requirements.<!-- END:briefDescription,_uF-QYEAhEdq_UJTvM1DM2Q -->
	<br/><br/><br/>
	<!-- START NON-TRANSLATABLE -->
	Attribute: mainDescription<br/><br/>
	<!-- END NON-TRANSLATABLE -->
	<!-- START:mainDescription,-awaQ_2dwhGyKRoVKQ-esPQ CRC: 3490029770 --><p>
	When identifying the elements for a scenario of system behavior, you can align each participating element with one of
	three key perspectives: <b>Entity</b>, <b>Control</b>, or <b>Boundary</b>. Although specifics of languages, frameworks,
	and heuristics of quality design will drive the final design, a first cut that covers required system behavior can
	always be assembled with elements of these three perspectives.
	</p>
	<p>
	This pattern is similar to the Model View Controller pattern (described here [<a class="elementLinkWithUserText" href="./../../../openup/guidances/supportingmaterials/references_6CCF393.html#BUS96" guid="_9ToeIB83Edqsvps02rpOOg">BUS96</a>]
	and here [<a class="elementLinkWithUserText" href="./../../../openup/guidances/supportingmaterials/references_6CCF393.html#WIKP-MVC" guid="_9ToeIB83Edqsvps02rpOOg">WIKP-MVC</a>], among other places), but the Entity Control Boundary (ECB) pattern is not
	solely appropriate for dealing with user interfaces, and it gives the controller a slightly different role to play.
	</p>
	<h4 align="left">
	ECB pattern example
	</h4>
	<p>
	<img alt="" src="./resources/ebc_diagram.JPG" />
	</p>
	<h3>
	Entity elements
	</h3>
	<p>
	An entity is a long-lived, passive element that is responsible for some meaningful chunk of information. This is not to
	say that entities are "data," while other design elements are "function." Entities perform behavior organized around
	some cohesive amount of data.
	</p>
	<p>
	An example of an entity for a customer service application is a Customer entity that manages all information about a
	customer. A design element for this entity would include data about the customer, behavior to manage the data,
	behavior to validate customer information and to perform other business calculations, such as "Is this customer
	allowed to purchase product X?"
	</p>
	<p>
	The identification of the entities as part of this pattern can be done many times at different levels of abstraction
	from the code, at different levels of granularity in size, and from the perspectives of different contexts. For
	example, you could do an analysis pass on a scenario of creating a marketing campaign and identify the customer element
	with various customer data elements, such as name and address, plus various required behaviors, such as the management
	of the name and address data and the ability to rate the customer based on some algorithm (such an application of this
	pattern would be abstract from code, coarse-grained, and have no specific context). Later, you could do a pass on the
	same scenario applying an architectural mechanism for database access that breaks the address out as its own element,
	moves the responsibility for storing and retrieving customers to a new control element, and identifies specific
	database decisions, such as the use of primary keys in the entities. (Such an application of this pattern would be
	closer to the code, finer-grained, and aligned with a database context.)
	</p>
	<h3>
	Control elements
	</h3>
	<p>
	A control element manages the flow of interaction of the scenario. A control element could manage the end-to-end
	behavior of a scenario. or it could manage the interactions between a subset of the elements. Behavior and business
	rules relating to the information relevant to the scenario should be assigned to the entities; the control elements are
	responsible only for the flow of the scenario.
	</p>
	<p>
	CreateMarketingCapmpaign is an example of a control element for a customer service application. This design element
	would be responsive to certain frontend boundary elements and would collaborate with other entities,
	control elements, and backend boundary elements to support the creation of a marketing campaign.
	</p>
	<p>
	As with the entity example here, there might be many passes over the identification of control elements. A first pass
	might be an analysis pass that identifies one control element for a scenario, with behavior to make sure that the
	design can support the flow of events. A subsequent pass might find controllers to manage reusable collaborations
	of low-level elements that will map to a specific code unit to be written.
	</p>
	<h3>
	Boundary elements
	</h3>
	<p>
	A boundary element lies on the periphery of a system or subsystem, but within it. For any scenario being considered
	either across the whole system or within some subsystem, some boundary elements will be "front end" elements that
	accept input from outside of the area under design, and other elements will be "back end," managing communication to
	supporting elements outside of the system or subsystem.
	</p>
	<p>
	Two examples of boundary elements for a customer service application might be a front end MarketingCampaignForm and a
	back end BugdetSystem element. The MarketingCampaignForm would manage the exchange of information between a user and
	the system, and the BugdetSystem would manage the exchange of information between the system and an external system
	that manages budgets.
	</p>
	<p>
	An analysis pass could identify one boundary element for each external relevant to a scenario. Subsequently, these
	could be broken down into multiple boundary elements or small communities made up of collaborating elements of all
	three stereotypes.
	</p>
	<h3>
	Walking through the scenario
	</h3>
	<p>
	You can walk through a scenario initiated by something outside of the boundaries of the system or subsystem being
	designed and distribute the responsibility to perform behavior supporting the scenario to the elements identified of
	each type. The appropriate design element responsible for each action in the scenario will be as described in the
	definition of each of the element types described here previously.
	</p>
	<p>
	In addition to identifying the behavior necessary to perform the scenario, the initiation of this behavior from design
	element to design element identifies the necessary relationships. There are certain appropriate relations between the
	participating elements. An element can communicate with other elements of the same kind. Control elements can
	communicate with each of the other two kinds, but entities and boundary elements should not communicate directly.
	</p>
	<p>
	This table shows appropriate links between design elements.
	</p>
	<table cellspacing="2" cellpadding="2" width="400" summary="Appropriate Links" border="1">
	<tbody>
	<tr>
	<td>
	</td>
	<th scope="col">
	<center>
	Entity
	</center>
	</th>
	<th scope="col">
	<center>
	Boundary
	</center>
	</th>
	<th scope="col">
	<center>
	Control
	</center>
	</th>
	</tr>
	<tr>
	<th scope="row">
	Entity
	</th>
	<td>
	<center>
	X
	</center>
	</td>
	<td>
	</td>
	<td>
	<center>
	X
	</center>
	</td>
	</tr>
	<tr>
	<th scope="row">
	Boundary
	</th>
	<td>
	</td>
	<td>
	</td>
	<td>
	<center>
	X
	</center>
	</td>
	</tr>
	<tr>
	<th scope="row">
	Control
	</th>
	<td>
	<center>
	X
	</center>
	</td>
	<td>
	<center>
	X
	</center>
	</td>
	<td>
	<center>
	X
	</center>
	</td>
	</tr>
	</tbody>
	</table>
	<p>
	By applying this pattern, you can put a robust design together that identifies the elements, behavior, and
	relationships necessary to support a scenario.
	</p><!-- END:mainDescription,-awaQ_2dwhGyKRoVKQ-esPQ -->
	</body>
	</html>