CPT374 Tutorial-Laboratory Sheet Two

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1 CPT374 Tutorial-Laboratory Sheet Two Objectives: Understanding XML DTDs Tutorial Exercises Exercise 1 - An introduction to XML DTD Go to and read the 15 examples provided in the ZVON DTD tutorial. Answer the following questions: 1.1 What is the "internal subset" of a DTD? What is the "external subset"? What advantages does one have over the other? 1.2 Is it possible to have both external and internal subset in a DTD? Provide an example. 1.3 What is an Element Content Model? What is the difference between this model and the Mixed Content Model? 1.4 Why are the following declarations illegal? <!ELEMENT text (#PCDATA footnote)> <!ELEMENT text (start, #PCDATA, end)> 1.5 What is the difference between ID and IDREF? 1.6 What is the difference between an internal and an external (parsed) entity? Provide examples. 1.7 What are parameter entities? Where can they be referenced? Exercise 2 - A DTD example using ID and IDREFS Write an XML DTD (mywml.dtd) for representing MyWML (My Wireless Markup Language) documents. A MyWML consists of one or more card elements. One attribute in your DTD should be an ID type, another attribute should be an IDREF type, and another attribute should be an enumerated type. Attributes should be optional except for ``type'', ``href'', and ``src, which must always be supplied. Your DTD must be written in such a way that the following MyWML document (mywml.xml) conforms to it. State any additional assumptions you need to make about the structure of MyWML documents. <?xml version="1.0"?> <!DOCTYPE mywml SYSTEM "mywml.dtd"> <mywml> <card id="card1" title="main page"> <do type="accept" label="next"> <go href="card2" /> </do> <emph>welcome</emph> select NEXT to go to last page. </card> <card id="card2" title="other page"> <do type="accept" label="next"> <go href="card3" /> </do> <do type="accept" label="prev"> <go href="card1" /> </do> <img alt="logo" src="logo.wbmp" /> select NEXT to go to last page. </card> Tutorial-Laboratory Sheet Two Page 1 of 9

<card id="card3" title="last page"> <do type="prev" label="back"> <prev /> </do> <p> Last Page </p> </card> </mywml> Laboratory Exercises Exercise 3 Creating DTD and validating XML against DTD using

2 <card id="card3" title="last page"> <do type="prev" label="back"> <prev /> </do> Last Page </card> </mywml> Laboratory Exercises Exercise 3 Creating DTD and validating XML against DTD using Eclipse We will now create a project in a slightly different way. I am sure you would not like to save all of your work in a folder called XMLExamples! Follow these steps- File New Project Choose the General option as shown below. Click Next. Give a name to the project. This time, Eclipse will create a folder inside the workspace directory. Call it say- Lab2Demo Click Next and then Finish. You will now be able to see Lab2Demo directory in the Package Explorer. Right click at it inside Package Explorer and choose the option New Other Scroll down to XML folder, open it. Add the XML file from above exercise to the project. After Eclipse has created an empty template, you can add the code for mwml.xml to it. I have already supplied you with the code in a zipped archive for this week. Now we need to add a DTD (call it mywml.dtd) to validate this XML file, Now right-click at the name of the name of the project and choose New Other option, a dialog box will appear and choose DTD this time. Eclipse does something silly- it adds an XML declaration at the top of empty DTD template- PLEASE REMOVE IT. DTD is not an XML file. Tutorial-Laboratory Sheet Two Page 2 of 9

3 In the final window you will now see the following (REMOVE THE XML declaration line from the top) Start writing the DTD or copy the code from the supplied file. Once it is completed, have a look at the Outline window on the right-hand-side Tutorial-Laboratory Sheet Two Page 3 of 9

Note: These panes do not appear like that in Eclipse- this

Right-click at the XML file name in the Package Explorer and

In case of errors, the errors are pointed out as red icon

4 Note: These panes do not appear like that in Eclipse- this is an edited image! Right-click at the XML file name in the Package Explorer and choose the option Validate - the in-built parser of Eclipse will validate XML document against DTD. If there is no error, Eclipse would notify you. In case of errors, the errors are pointed out as red icon next to the offending line- move your mouse on that icon and it will display a detailed error. Tutorial-Laboratory Sheet Two Page 4 of 9

5 Exercise 4 - Marking up text using a DTD Consider the following DTD: <!ELEMENT address-book <!ELEMENT entry <!ELEMENT name <!ELEMENT fname <!ELEMENT lname <!ELEMENT address <!ATTLIST address <!ELEMENT street <!ELEMENT region <!ELEMENT postal-code <!ELEMENT locality <!ELEMENT country <!ELEMENT tel <!ATTLIST tel <!ELEMENT fax <!ATTLIST fax <!ELEMENT <!ATTLIST (entry+)> (name,address*,tel*,fax*, *)> (#PCDATA fname lname)*> (street,region?,postal-code,locality,country)> preferred (true false) false > preferred (true false) false > preferred (true false) false > EMPTY> href CDATA #REQUIRED preferred (true false) false > Now consider the following text: John Doe 34 Fountain Square Plaza Cincinnati, OH USA (preferred) jdoe@ .com Jack Smith jsmith@ .com Using the supplied DTD, create an XML document that contains the above text. How can you do this using Eclipse? Create a Project and, Right-click at Project name and Invoke New XML File wizard using workbench menu File>New>Other>XML>XML On the XML File Name page select a project or folder to contain the XML file and type a name for it. Next, depending on what type of gramma file you need choose, select the Create XML file from DTD file radio button. Tutorial-Laboratory Sheet Two Page 5 of 9

The next choice you have to do is to select your DTD file (it should pre exist somewhere). You can select it from the workspace (you can import files into the workspace if they are not there).

6 The next choice you have to do is to select your DTD file (it should pre exist somewhere). You can select it from the workspace (you can import files into the workspace if they are not there). Click Next button. On the Select Root Element page select from the following content options: o Create optional attributes - both mandatory and optional attributes will be generated. o Create optional elements - both mandatory and optional elements will be generated. o Create first choice of required choice - the first option of a required choice will be generated in your XML file. o Fill elements and attributes with data - any elements and attributes generated will be filled with sample data. If you do not select any of these options, then only the minimum amount of content required for the XML file will be created. Rest is self-explanatory. The advantage of this approach is that- as you create an XML document, it is constantly validated against DTD for any errors. Tutorial-Laboratory Sheet Two Page 6 of 9

7 Exercise 5 - XML Namespaces and DTD Consider the following XML document (invalid-internal.xml): <?xml version="1.0"?> <!DOCTYPE kbs:myroot [ <!ELEMENT kbs:myroot (kbs:child1, kbs:child2+) > <!ATTLIST kbs:myroot xmlns:kbs CDATA #FIXED " <!ELEMENT kbs:child1 (#PCDATA) > <!ELEMENT kbs:child2 (#PCDATA) > ]> <kbs:myroot> <child1>invalid</child1> <child2>doc</child2> </kbs:myroot> Validate this document against its DTD by using Eclipse. Does it validate? Why (not)? If it does not validate, fix it so that the XML document gets validated against its DTD. Try to also include an external DTD into the XML document. Tutorial-Laboratory Sheet Two Page 7 of 9

8 SELF-EXERCISE Exercise 6 - A DTD example Inspect the DTD below and try to work out all its components: 1: <?xml version = "1.0" encoding = "UTF-8"?> 2:  6: <!ELEMENT Invoice (ShipTo, Date, ItemInfo+, Summary*)> 7: <!ATTLIST Invoice version CDATA #IMPLIED> 8:  9: <!ELEMENT ShipTo (Name, (CustomerID SocSecNo), 10: Address?, City?, State?, Zip?)> 11: <!ELEMENT Name (First, Last)> 12: <!ELEMENT First 13: <!ELEMENT Last 14: <!ELEMENT CustomerID 15: <!ATTLIST CustomerID sex (male female unknown) #REQUIRED> 16:  17: <!ELEMENT SocSecNo 18: <!ELEMENT Address 19: <!ELEMENT City 20: <!ELEMENT State 21: <!ELEMENT Zip 22: <!ELEMENT Date  23: <!ELEMENT ItemInfo (ItemName?, SKU, Quantity, Weight, Price+, 24: Note?, Divider?)> 25: <!ELEMENT ItemName 26: <!ELEMENT SKU 27: <!ELEMENT Quantity 28: <!ELEMENT Weight 29: <!ATTLIST Weight unitofmeasure (lb oz) "oz" 30: measurementtype CDATA #FIXED "US" > 31:  32: <!ELEMENT Price 33: <!ELEMENT Note (#PCDATA Link Emph )* > 34: <!ELEMENT Emph 35: <!ELEMENT Link 36: <!ELEMENT Divider EMPTY > 37: <!ELEMENT Summary ANY > Replace the line: 6: <!ELEMENT Invoice (ShipTo, Date, ItemInfo+, Summary*)> with the line: 6: <!ELEMENT Invoice (ShipTo, BillTo?, Date, ItemInfo+, Summary*)> and insert the following line into the DTD, : between lines 10 and 11: <!ELEMENT BillTo (Name, (CustomerID SocSecNo), Address?, City?, State?, Zip?)> The modified DTD shows that both ShipTo and BillTo have the same content model. How can we use a parameter entity to express this more elegantly? Change your DTD to use a parameter entity and validate your document against it. Tutorial-Laboratory Sheet Two Page 8 of 9

9 Exercise 7- in built templates in Eclipse Create a new Project. File New Project In the dialog box that appears, expand Examples menu and choose Editing and validating XML files option Click Next and then Finish- have a look at the Project that gets created in the Package Explorer (XML Examples) Explore the various directories- it has various XML and DTD examples. Tutorial-Laboratory Sheet Two Page 9 of 9

Introduction to XML. When talking about XML, here are some terms that would be helpful:

Introduction to XML. When talking about XML, here are some terms that would be helpful: Introduction to XML XML stands for the extensible Markup Language. It is a new markup language, developed by the W3C (World Wide Web Consortium), mainly to overcome limitations in HTML. HTML is an immensely