Unit06.md

Unit 6: Data Transport   Data that needs to be sent across a network is rarely in plain text format.  This is in part because transporting data in plain text is not aesthetically pleasing, and you often need to present data to users in a visually appealing manner while conserving its organization.  In this unit, you will learn about XML, a means to organizing data hierarchically so that it can be transported easily.  You will learn how XML documents can be sent across a network and parsed on the receiving end for display.  You will also learn about XSLT and DTD, two schemas that, like XML, impose structure on documents.  These mechanisms ensure a certain degree of consistency in data transfer and display.

Unit 6 Time Advisory
This unit should take you approximately 18 hours to complete.

☐    Subunit 6.1: 3 hours

☐    Subunit 6.2: 3 hours

☐    Subunit 6.3: 3 hours

☐    Subunit 6.4: 3 hours

☐    Subunit 6.5: 3 hours

☐    Subunit 6.6: 3 hours

Unit6 Learning Outcomes
Upon successful completion of this unit, the student will be able to:

• Explain the consistency mechanisms for data transfer and display.
• Differentiate the coding rationale between HTML and XML.
• Explain the purpose and use of DTDs.
• Explain the purpose and use of XML schemas.
• Compare and contrast document-based and element-based parsing.
• Complete XML programming tasks. 

6.1 Extensible Markup Language (XML)  

• Reading: Hobart and William Smith Colleges: David J. Eck's Introduction to Programming Using Java: “Section 11.5: A Brief Introduction to XML” Link: Hobart and William Smith Colleges: David J. Eck's Introduction to Programming Using Java: “Section 11.5: A Brief Introduction to XML” (PDF)
   
  Instructions: Please read Section 11.5 in its entirety.  This reading provides a number of examples for using XML data.  Compile and run the samples included in this section. 

  Terms of Use: The article above is released under a Creative Commons Attribution-Non-Commercial-Share-Alike License 3.0.  It is attributed to David Eck and the original version can be found here.

6.2 Imposing Structure on XML Documents  

• Reading: Oracle's “Generating XML Data” Link: Oracle's “Generating XML Data” (HTML)
   
  Instructions: Please complete the “Generating XML Data” tutorial.  Pay special attention to the section starting with the “Creating a Document Type Definition” header, as this portion of the material discusses the format and restrictions of using DTDs for structure with XML.  Compile and run all of the samples in this tutorial.

  Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

6.3 Designing XML Schema  

• Reading: Sun Microsystem’s “Designing an XML Schema” Link: Sun Microsystem’s “Designing an XML Schema” (HTML)
   
  Instructions: Please complete the “Designing an XML Schema” tutorial.  Compile and run all of the samples in this tutorial.  How many files did you create?  Check your answer.

  Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

6.4 Processing Hierarchical Data  

• Reading: Sun Microsystem’s “Extensible Stylesheet Language Transformations” Link: Sun Microsystem’s “Extensible Stylesheet Language Transformations” (HTML)
   
  Instructions: Please complete the “Extensible Stylesheet Language Transformations” tutorial, which introduces the XSLT standard and defines mechanisms for addressing XML data (Xpath).
   
  What is Xalan?  Oracle tutorials in the subunits that follow use the sample code that can be found at the URL at the bottom of the page.  You might want to download the files to have them available as you need them.

  Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

6.4.1 Overview  

• Reading: Sun Microsystem’s “Introducing XSL, XSLT, and XPath” Link: Sun Microsystem’s “Introducing XSL, XSLT, and XPath” (HTML)
   
  Instructions: Please complete the “Introducing XSL, XSLT, and XPath” tutorial, which introduces the three subcomponents of XSLT and discusses the packages used in the JAXP transformation APIs.  Pay attention to each API and when it is used, as you will be using these APIs in code samples in your lessons.
   
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6.4.2 How XPath Works  

• Reading: Sun Microsystem’s “How XPath Works” Link: Sun Microsystem’s “How XPath Works” (HTML)
   
  Instructions: Please complete the “How XPath Works” tutorial, which explains the XPath mechanisms for addressing XML data.  XPath is one of the more complicated processes, so you may want to do a fast read of the lesson, and then go back and work to understand each concept in this tutorial. 
   
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6.4.3 Writing Out a DOM as an XML File  

• Reading: Sun Microsystem’s “Writing Out a DOM as an XML File” Link: Sun Microsystem’s “Writing Out a DOM as an XML File” (HTML)
   
  Instructions: Please complete the “Writing Out a DOM as an XML File” tutorial, which uses XPath mechanisms and the Xalan tool.  Refer back to the “How XPath Works” tutorial for additional competency in creating an XML File.
   
  Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

6.4.4 Generating XML from an Arbitrary File Structure  

• Reading: Sun Microsystem’s “Generating XML from an Arbitrary File Structure” Link: Sun Microsystem’s “Generating XML from an Arbitrary File Structure” (HTML)
   
  Instructions: Please complete the “Generating XML from an Arbitrary File Structure” tutorial, which walks you through the process to transform any existing structure to XML using DOM or SAX.
   
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6.4.5 Transforming XML Data with XSLT  

• Reading: Sun Microsystem’s “Transforming XML Data with XSLT” Link: Sun Microsystem’s “Transforming XML Data with XSLT” (HTML)
   
  Instructions: Please complete the “Transforming XML Data with XSLT” tutorial, which walks you through the steps to translate any XML input data to HTML output. 
   
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6.4.6 Transforming from the Command Line with Xalan  

• Assignment: Sun Microsystem’s “Transforming from the Command Line with Xalan” Link: Sun Microsystem’s “Transforming from the Command Line with Xalan” (HTML)
   
  Instructions: Please complete the “Transforming from the Command Line with Xalan” tutorial by running the code provided.  Xalan is a new tool for working with XML.  How is it different from the other tools used in your lessons?
   
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6.4.7 Concatenating Transformations with a Filter Chain  

• Reading: Sun Microsystem’s “Concatenating Transformations with a Filter Chain” Link: Sun Microsystem’s “Concatenating Transformations with a Filter Chain” (HTML)
   
  Instructions: Please complete the “Concatenating Transformations with a Filter Chain” tutorial, which introduces the concept of a filter chain and then provides the code to build one.  What is a filter chain, and what is its purpose?
   
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6.5 Java API for XML Processing (JAXP)  

• Reading: Sun Microsystem’s “Introduction to JAXP” Link: Sun Microsystem’s “Introduction to JAXP” (HTML)
   
  Instructions: Please complete the “Introduction to JAXP” tutorial, which lays out the technologies for using Java with XML data.  What is the purpose of JAXP?  What are its principle features?  Oracle tutorials in the subunits that follow use the sample code that can be found at the Chapter 5 header, “Simple API for XML.”  The files are listed at the end of the page.

  Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

6.5.1 SAX Methods  

• Reading: Sun Microsystem’s “The Simple API for XML APIs” Link: Sun Microsystem’s “The Simple API for XML APIs” (HTML)
   
  Instructions: Please complete the “The Simple API for XML APIs” tutorial, which graphically presents the event model for converting existing data to XML.  What principle methods does it use?

  Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

6.5.2 When to Use SAX?  

• Reading: Sun Microsystem’s “When to Use SAX” Link: Sun Microsystem’s “When to Use SAX?” (HTML)
   
  Instructions: Please complete the “When to Use SAX” tutorial, which presents a number of different uses for this parser.  How might it be used to perform data transport in a LAN?

  Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

6.5.3 Echoing an XML File with the SAX Parser  

• Assignment: Sun Microsystem’s “Echoing an XML File with the SAX Parser” Link: Sun Microsystem’s “Echoing an XML File with the SAX Parser” (HTML)
   
  Instructions: Please compile each event in this tutorial as instructed in each link.  What happens in each step?  Did your output match the tutorial? 

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6.5.4 Adding Additional Event Handlers  

• Reading: Sun Microsystem’s “Adding Additional Event Handlers” Link: Sun Microsystem’s “Adding Additional Event Handlers” (HTML)
   
  Instructions: Please complete the “Adding Additional Event Handlers” tutorial.  What are two methods for handling common SAX events described in this tutorial?

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6.5.5 Handling Errors with the SAX Parser  

• Reading: Sun Microsystem’s “Handling Errors with the Nonvalidating Parser” Link: Sun Microsystem’s “Handling Errors with the Nonvalidating Parser” (HTML)
   
  Instructions: Please complete the “Handling Errors with the Nonvalidating Parser” tutorial, which describes common errors and how to prevent them.  What are some of the common parsing errors you can avoid?

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6.6 Document-Based Parsing  

• Reading: Sun Microsystem’s “Document Object Model” Link: Sun Microsystem’s “Document Object Model” (HTML)
   
  Instructions: Please complete the “DOM Object Model” tutorial, which lays out the DOM model for using Java with XML data.  DOM is a tree structure with nodes.  What types of data are represented as nodes on a DOM “jtree”?   Oracle tutorials in the DOM subunits that follow use the sample code that can be found at the URL shown at the bottom of this tutorial.  You may want to download this code before you get to the subunits with tutorials that use the code for its examples.

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6.6.1 When to Use DOM  

• Reading: Sun Microsystem’s “When to Use DOM” Link: Sun Microsystem’s “When to Use DOM” (HTML)
   
  Instructions: Please complete the “When to Use DOM” tutorial.  How is DOM like SAX?  How is DOM different from SAX?  When is it better to utilize the DOM structure?
   
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6.6.2 Reading XML Data into a DOM  

• Reading: Sun Microsystem’s “Reading XML Data into a DOM” Link: Sun Microsystem’s “Reading XML Data into a DOM” (HTML)
   
  Instructions: Please complete the “Reading XML Data into a DOM” tutorial, which provides example code for creating a DOM.
   
  Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

6.6.3 Displaying a DOM Hierarchy  

• Reading: Sun Microsystem’s “Displaying a DOM Hierarchy” Link: Sun Microsystem’s “Displaying a DOM Hierarchy” (HTML)
   
  Instructions: Please complete the “Displaying a DOM Hierarchy” tutorial, which provides sample code to expose DOM nodes so that you might examine the structure.  This allows you to gain an understanding of DOM structure now as it is a useful diagnostic tool.   
   
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6.6.4 Examining the Structure of a DOM  

• Reading: Sun Microsystem’s “Examining the Structure of a DOM” Link: Sun Microsystem’s “Examining the Structure of a DOM” (HTML)
   
  Instructions: Please complete the “Examining the Structure of a DOM” tutorial, which walks you through how a node tree is generated.
   
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6.6.5 Constructing a User-Friendly JTree from a DOM  

• Reading: Sun Microsystem’s “Constructing a User-Friendly JTree from a DOM” Link: Sun Microsystem’s “Constructing a User-Friendly JTree from a DOM” (HTML)
   
  Instructions: Please complete the “Constructing a User-Friendly JTree from a DOM” tutorial.  How would you explain the internal structure of a DOM to a classmate who had problems with the assignments you just completed?
   
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6.6.6 Creating and Manipulating a DOM  

• Reading: Sun Microsystem’s “Creating and Manipulating a DOM” Link: Sun Microsystem’s “Creating and Manipulating a DOM” (HTML)
   
  Instructions: Please complete the “Creating and Manipulating a DOM” tutorial, which lays out the technologies for using Java with XML data.  What is the purpose of JAXP?  What are its principle features?
   
  Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.