Nov. 11 Required Readings: XML

1) Martin Bryan.  Introducing the Extensible Markup Language (XML): http://www.is-thought.co.uk/xmlintro.htm    
     I found this reading to be hard to follow because of all of the coding jargon and because I knew nothing about XML before reading it. I also feel that the reading could've been organized a little bit better, but the follow are the main points I took away from the reading:
An XML file normally consists of:

1. an XML processing instruction

2.A document type declartion

3. A fully-tagged document instance with matching element type name to document type name

• XML- a subset of the Standard Generalized Markup Language that is designed to make it easy to interchange structured documents over the Internet
• After defining the role of each element of text in a formal model (DTD), users of XML can check that each component of document occurs in a vaild place within the exchanged data stream- DTD is not required and if no DTD is available an XML system can assign a default definition for undeclared components of the markup.
• XML is not a standardized way of coding text- it is a formal language that can be used to pass info about the component parts of a document to another computer system-XML is flexible enough to be able to describe any logical text structure
• To use XML- users need to know how the markup tags are delimited from normal text and in which order the various elements should be used in- systems that understand XML can provide a list of vail elements and will add the required delimiters. When the system does not understand XML users can enter tags manually for later validation
• Elements- are entered between matched angle brackets
• Entity references- start with & and end with ;
• A Document Type Definition (DTD) must be created to define tag sets
• If attributes of elements are not defined with a start tag in XML the program will use default elements
• Commonly used text can be declared within the DTD as a text entity 
• XML provides many techniques for special elements- usually notation declaration is required to tell the program what to do with the reference files's unparsed data 

3) Extending you Markup: a XML tutorial by Andre Bergholz: http://xml.coverpages.org/BergholzTutorial.pdf
      This article did a much better job of explaining XML jargon and made the first reading much easier to understand. Unlike the first reading, this reading defines and explains acronyms before using the acronyms through out the reading. The first reading is so much more confusing than this one that it shouldn't be a required reading.

But what I took away the most from this reading includes:

• XML- is semantic language that lets you meaningfully annotate text.
• XML documents look a lot like HTML documents
• XML elements can be nested and attributes can be attached to them- attributes must be in quotes and tags must be balanced or explicitly close
• DTD's define the structure of XML documents- users can specify the set, order, and attributes of tags
• When an XML document conforms to its DTD its called valid- a DTD can be included in the XML or contained in a separate file
• DTD elements- can be nonterminal or terminal and DTD attributes can have zero to many attributes- attribute definitions don't impose order on when the attributes occur-DTDs expressive power is limited
• XML extensions let you link more than one source

4) XML Schema Tutorial http://www.w3schools.com/Schema/default.asp  

     Just like all the previous tutorials- at first I was a little lost, but I caught on. I liked how this week we read readings about the code first and then did the tutorial.