What the hell is XML

1
Introduction

• What the hell is XML?
• The Flash Native XML object.
• Flash Code Example, XML object use.
• XML Code Example, a file.
• Validating XML, Validation and Correctness.
• Viewing XML more of this in the tutorial.
• Showing External (Formatted) Text Files.
• Supported Tags HTML in text components.

2
What is XML?

• XML is principally concerned with the description
  and structure of data (content presentation are
  separate).
• Traditional methods of data storage and exchange
  employ a variety of schemes.
• Electronically, these usually are of the form of
  simple text files (Comma Separated Values etc.)
  or binary files.
• Both methods have their own advantages and
  disadvantages.
• CSV files contain data that can be easily read
  but lack a description of their own format.
• Binary files contain data and a description of
  its data format (as a Word document does) but are
  proprietary schemes that require specific
  applications to read them.

3
Illustrative Example

• Paper-based or Simple Text File
• Yvan Cartwright
• Staffordshire University
• y.j.f.cartwright_at_staffs.ac.uk
• Comma Separated Values
• Yvan,Cartwright,Staffordshire University,y.j.f.ca
  rtwright_at_staffs.ac.uk
• Binary a string of 0s and 1s
• 0101 1001 0111 0110 0110 0001 0110 1110 0010
  0000 etc.

4
Simple freeform XML File

• ltcontactgt
• ltnamegt
• ltfirstnamegtYvanlt/firstnamegt
• ltlastnamegtCartwrightlt/lastnamegt
• lt/namegt
• ltworkplacegtStaffordshire Universitylt/workplacegt
• ltemailgty.j.f.cartwright_at_staffs.ac.uklt/emailgt
• lt/contactgt

5
XML Well-formed and Valid

• The rules for XML files are much stricter than
  for HTML. A forgotten tag, or an attribute
  without quotes makes the file unusable.
• It is written in the official XML specification
• Applications are not allowed to try to
  second-guess the creator of a broken XML file
• If the file is broken, an application has to stop
  right there and issue an error.

6
Native XML object

• The XML object in Flash MX 2004 is much faster
  than in older versions.
• It is now a native object, built in to Flash.
• Also has more functionality (but not XPath).
• Older versions of Flash XML objects were hard to
  use.
• XML object follows same rules as other media
  loaders.

7
Code Examples

• // creates a new, empty XML object
• var my_xmlXML new XML()
• // defines how to react to loading of data
• my_xml.onLoad function(bOkayBoolean)
• if(bOkay true)
• trace(my_xml) // success
• else
• trace("An error occurred) // oops
• // now we are ready, try to get the xml data from
  the URL
• my_xml.load("example.xml")

8
Code Examples

• Example of HTML-like XML text.
• Note the contents of the first line.
• lt?xml version"1.0" encoding"utf-8"
  standalone"yes"?gt
• ltxhtmlgt
• ltpgtParagraph ltigtonelt/igt is full of rhubarb,
  rhubarb, rhubarblt/pgt
• ltpgtPara ltbgttwolt/bgt is also full of rhubarb,
  rhubarb, rhubarblt/pgt
• ltpgtBut para ltspan class"para3"gt3 contains no
  rhubarblt/spangt!lt/pgt
• ltpgtFourth, lta href"http//www.staffs.ac.uk/"gta
  link!lt/agtlt/pgt
• lt/xhtmlgt

9
Validating XML

• The Flash XML object is not a validator.
• We have to put good XML in to get good XML out.
• Badly formed XML will cause unpredictable
  behaviour by a Flash XML object.
• You should use other software to validate your
  XML as part of your software development and
  testing (e.g. http//www.ltg.ed.ac.uk/richard/xml
  -check.html).

10
Validation and Correctness

• Remember that valid XML is well structured XML.
• It doesnt mean that the content is correct!
• Flash XML objects can be used to build well
  structured XML documents.
• But the content is up to you!

11
Viewing XML

• We may choose to use XML in a variety of ways.
• One way is to use the contents to do something
  for example, custom settings.
• Or we could use it as dynamic content in a
  text-output area.
• This is very useful you can develop an
  application separately from the content.

12
External Text Files

• It is worth using external media files,
  dynamically loaded.
• Content is easy to update.
• Content is easy to work on as a team only one
  person needs access to the Flash doc.
• Simplifies the structure of the Flash doc.
• Makes the binary (SWF) load faster.
• Only load what you need.

13
Showing Formatted Text

• Flash Components include TextArea objects.
• They can hold HTML formatted text.
• Limited number of tags supported see next
  slide.
• Easy to load XML into a TextArea.
• Supports graphics, links, CSS!

14
Supported Tags

• Anchor tag (ltagt)
• lta href"../home.htm" target"_blank"gtGo homelt/agt
• Supports CSS alink, ahover, and aactive
• Bold tag (ltbgt)
• ltbgtThis is bold text.lt/bgt
• Break tag (ltbrgt)
• A line of textltbrgtNext line of textltbrgt
• Font tag (ltfontgt) But USE CSS INSTEAD!
• ltfont faceArial, Helv" size"24"
  color"0000FF"gtThis is green, 24-point
  textlt/fontgt

15
Supported Tags

• Image tag (ltimggt) many options.
• Italic tag (ltigt)
• That is very ltigtinterestinglt/igt.
• List item tag (ltligt)
• ltligtLemonslt/ligt
• Paragraph tag (ltpgt)
• textField.htmlText "ltp align'right'gtThis text
  is aligned on the right side of the text
  fieldlt/pgt"
• Span tag (ltspangt)
• ltspan classmyCSSstuffgtSome Textlt/spangt
• Text format tag (lttextformatgt) many options

16
High-Score Tables and XML

• We now have a mechanism to create XML objects
  within Flash.
• The information stored inside our XML documents
  is entirely up to us.
• In a game, we could store the users game
  statistics and send that information to a script.
• The script could then read the information and
  use it to update an online high score table.

17
High-Score Table Example

• ltgamegt
• ltplayergtYvanlt/playergt
• ltlevelgt5lt/levelgt
• ltscoregt23518lt/scoregt
• lttime_takengt756lt/time_takengt
• lt/gamegt

18
Score Code

• XML.prototype.ignoreWhite true
• // the text that goes inside the following
  constructor can be created from the variables in
  your Flash code that hold the required data
• var packet_xmlXML new XML("ltgamegtltplayergtYvanlt/
  playergtltlevelgt5lt/levelgt ltscoregt23518lt/scoregtlttime_
  takengt756lt/time_takengtlt/gamegt")
• packet_xml.xmlDecl "lt?xml version\"1.0\" ?gt"
• packet_xml.send("http//trentdev.soc.staffs.ac.uk/
  wwwdata/isi/highscores.asp", "_blank")
• // need to code an ASP/PHP/JSP script and put it
  on a server (Part 2!)

19
Reading XML Objects

• The previous example uses Flash to create an XML
  object and send that to an online server script
  for processing.
• This can be useful but reading XML objects (or
  documents) within Flash is just as important.
• You could be sent XML objects from a variety of
  sources including other Flash applications.
• For games, you can specify input files (level
  content) as an XML document.
• This could be created using a level editor that
  can export to XML. More on this in Part 2!

20
Conclusion

• Native XML object is fast
• Seen some XML code examples
• Seen an XML example file
• Discussed validating XML, validation and
  correctness
• We will view some XML in the tutorial
• Discussed showing external (formatted) text files
• Outlined supported tags for further details
  see
• http//livedocs.macromedia.com/flash/mx2004/main_7
  _2/wwhelp/wwhimpl/common/html/wwhelp.htm?contextF
  lash_MX_2004file00001040.html