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<h1 class="chapter-title"><span class="chapter-titlelabel">Chapter 7: </span>Creating the Data Model</h1><div class="section">
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<a name="217"></a>Overview</h2>
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<p class="para">Most books about J2EE skip the data-modeling and database design phases of development. But I have found that both steps are critical to the success of a J2EE application. As part of the development team, a technical architect should have a basic knowledge of data modeling. Further, in some companies, the architect is responsible for designing the application database. Just as object-modeling exercises help produce good code, data-modeling exercises help produce good database designs. (I have to admit, however, that the many years I spent as a database designer and administrator may have prejudiced my views as to the importance of data modeling.)</p>
<p class="para">In addition, I find data-modeling concepts useful in designing XML document formats, such as DTDs and schemas. Applying data-modeling concepts to XML document design is a bit unconventional. The thought process behind deciding if a data item is an element or an attribute is similar to deciding between entities and attributes in data modeling. In addition, one-to-many relationships in data modeling translate directly to the child element concept in XML documents. I'll provide some details and examples in this section to show how you can implement data models as XML document formats.</p>
<p class="para">Although relational databases may someday be usurped by object databases, I don't see any signs of that occurring in today's market. For now, because relational databases are part of most J2EE applications, most technical <a name="219"></a><a name="IDX-86"></a>architects need to have at least a basic understanding of data-modeling concepts.</p>
<p class="last-para">If you're more comfortable with data modeling than with object modeling, feel free to take the easier path by doing data-modeling activities before object modeling. All the <i class="emphasis">entities</i> (defined in the <a href="LiB0048.html#220" target="_parent" class="chapterjump">next section</a>) in the data model are potential identifications of data access objects, business objects, and value objects. Although the two modeling disciplines use different terms, they are quite similar conceptually.</p>
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