When to Use XML and When Not to Use It in Java

Encode Code 39 Extended in Java When to Use XML and When Not to Use It
When to Use XML and When Not to Use It
Code 3/9 Drawer In Java
Using Barcode maker for Java Control to generate, create Code-39 image in Java applications.
In 4, you braved the waters of abstract data modeling, so now it's time to get concrete Building your XML DTD is the next step in data-oriented application design The first question you must ask, while looking at your abstract data model diagram from 4 (see Figure 4-7) is "Where doesn't XML fit " Identify the parts of your data model that make more sense as purely relational entities Such parts usually are supporting data, such as key words and author names For example, in CyberCinema there's no reason to list valid reviewers in an XML file The reviewers and details about them (for example, names and e-mail addresses) can be stored in a relational table The reviews themselves are best stored as XML
Bar Code Creation In Java
Using Barcode maker for Java Control to generate, create bar code image in Java applications.
Think Like an Archeologist
Recognize Barcode In Java
Using Barcode recognizer for Java Control to read, scan read, scan image in Java applications.
Put yourself in the mindset of an archeologist in the future, leafing through a collection of your XML instances If you're thinking, "I am not writing this application for future archeologists," you're missing the point The Rosetta stone wasn't created for the benefit of future archeologists; it was created for the dissemination of information in its own time By carefully building and documenting the DTD, you make your data more useful not only for today but also in the future Suppose you're an archeologist who came across a collection of XML instances Consider what information must be in those instances in order for you to reconstruct the application that created them o crack the code of this found data Let's use as an example the simple e-mail application we built a data model for in 4 Your first step should be to "roughout" an XML vocabulary by creating some XML instances This helps you understand the tagging structure before jumping headfirst into DTD design Create a few of these dummy files They're not intended to be used by your programs; they're just a tool to help you visualize what the XML files will look like and how they need to be structured A first stab at an XML instance for this application might look like the following:
Code-39 Drawer In Visual C#
Using Barcode encoder for .NET framework Control to generate, create Code 39 image in .NET framework applications.
<E-MAIL> <FROM>Dan Appelquist</FROM> <TO>Bill Gates</TO> <SUBJECT>I Like Windows</SUBJECT> <BODY>Thanks for all the hard work</BODY>
Code 39 Full ASCII Drawer In VS .NET
Using Barcode generation for ASP.NET Control to generate, create Code-39 image in ASP.NET applications.
</E-MAIL>
Drawing USS Code 39 In .NET Framework
Using Barcode creator for Visual Studio .NET Control to generate, create Code 3 of 9 image in .NET framework applications.
This XML instance makes it easy for us to distinguish the From: field from the To: field and so on, but it doesn't help us construct an application in conjunction with a relational database We're designing this XML to work hand-in-hand with a relational database In particular, we have to understand where numerical ID numbers come into play Relational database schemas use numerical ID numbers in order to identify items uniquely and to preserve cross-references Most of these ID numbers are generated as they are needed: When you insert a new row into a table, you first generate a new ID number Depending on how your database works, ID number generation may be an automatic feature; it may involve setting up a database sequence, a feature of a database that generates consecutive unique numbers Or it could be a number generated somewhere in the application and inserted into the database In any case, it is a number that's unique at least to a particular set of items (for example, e-mail messages in our simple e-mail application) For our e-mail application, if we assume that ID numbers are going to be assigned to each e-mail message, those numbers have to be reflected in the XML instance as well, so that we know which XML instances match up with which rows in our relational database We do that by adding an ID attribute to the E-MAIL element we've created Note that the name "ID" doesn't have any special meaning in XML instances; I simply decided to call it that Because users are another item that will be stored in the relational database, we'll also include an ID field in our TO and FROM elements Our message subject and body don't need unique IDs because they are unique to the message itself Now have the following:
Code 3 Of 9 Generation In VB.NET
Using Barcode maker for Visual Studio .NET Control to generate, create Code 39 Full ASCII image in .NET framework applications.
<E-MAIL ID="1"> <FROM ID="2">Dan Appelquist</FROM> <TO ID="3">Bill Gates</TO> <SUBJECT>I Like Windows</SUBJECT> <BODY>Thanks for all the hard work</BODY> </E-MAIL>
Make ANSI/AIM Code 39 In Java
Using Barcode drawer for Java Control to generate, create Code39 image in Java applications.
Again, adopting the perspective of an archeologist in the future, suppose you came across thousands of XML instances in the preceding format You could reconstruct not only a database of messages but also a database of all users who were part of this system You could reconstruct entire conversations If a user changed his or her name sometime during the operational period of the system, you wouldn't care because you'd be able to identify users by their unique IDs In this manner, XML makes it possible for you to "future-proof" your documents
Data Matrix 2d Barcode Encoder In Java
Using Barcode generation for Java Control to generate, create Data Matrix 2d barcode image in Java applications.
Oh, by the way, if you happen not to be a future archeologist, but a system administrator or database administrator or DBA, frantically trying to reconstruct a database after a system crash, you may be thankful that the DTD was well designed Future-proofing also means disaster-proofing your data
Painting Bar Code In Java
Using Barcode encoder for Java Control to generate, create barcode image in Java applications.
UCC - 12 Creation In Java
Using Barcode drawer for Java Control to generate, create UPC Symbol image in Java applications.
Make UCC - 12 In Java
Using Barcode maker for Java Control to generate, create UPCE image in Java applications.
Making UPC-A Supplement 5 In .NET Framework
Using Barcode generation for ASP.NET Control to generate, create UCC - 12 image in ASP.NET applications.
Making Bar Code In .NET
Using Barcode encoder for ASP.NET Control to generate, create barcode image in ASP.NET applications.
ANSI/AIM Code 128 Encoder In C#.NET
Using Barcode maker for .NET Control to generate, create Code 128 image in .NET framework applications.