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Additional Web Protocols

Additional Web Protocols. JavaScript and XML An overview of web languages and emerging technologies. JavaScript Overview. Scripting Language that uses a similar syntax to Java (or C/C++) developed by Netscape. Permits a higher level of interaction in Web pages. Low level Example….. :

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Additional Web Protocols

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  1. Additional Web Protocols JavaScript and XML An overview of web languages and emerging technologies

  2. JavaScript Overview Scripting Language that uses a similar syntax to Java (or C/C++) developed by Netscape. Permits a higher level of interaction in Web pages Low level Example….. : <html> <body> <script language="JavaScript"> document.write('Hello'); </script> </body> </html>

  3. JavaScript Alerts <html> <body> <script language="JavaScript"> alert('This is an Alert Box!'); </script> </body> </html> Display a dialogue box message

  4. Variables in JavaScript • Just like any other programming language var age = 35; var height = “”; var name = “Gordon”; “var” part declares the variable Defining a variable to use later String variable example

  5. Functions Hint: Use functions if you want to do the same thing more than once HTML comment For backwards compatibility <html> <script language="JavaScript"> <!-- hide the code function myFunctionname() { document.write('Welcome to my homepage!<br>'); document.write('This is JavaScript!<br>'); } myFunctionname(); myFunctionname(); myFunctionname(); // --> </script> </html>

  6. What are Event Handlers? The image changes as a result of a user action causing a ‘link event’ to occur

  7. Creating an Image Rollover • Note: Authoring packages sure as Dreamweaver make creation of these easier ! • However, it is important you understand the technology behind Web pages Example JavaScript Event Handlers <a href="#" onMouseOver="document.button1.src='button2.gif'" onMouseOut="document.button1.src='button1.gif'"> <img src="button1.gif" name="button1" width=140 height=30 border=0></a>

  8. Image Swapping Standard Image tag used to load first image <img src="button1.gif" name="button1" width=140 height=30 border=0> Mouse Out Event Occurs 2 Reset Source Address onMouseOut="document.button1.src='button1.gif'" 1 Mouse Over Link Event Occurs Image Source Address set to second image onMouseOver="document.button1.src='button2.gif'"

  9. The HTML-document The Document Object Model - DOM • JavaScript organises all elements on a web-page into a hierarchy • Every element is seen as an object. • Each object can have certain properties and methods. • JavaScript can easily manipulate the objects

  10. HTML-document hierarchy Example To refer to the elements in JavaScript code document.forms[0].elements[0].value

  11. Form Object Types What to run when submit is pressed <FORM METHOD="POST" ACTION="mailto:emailname@emailaddress"> Surname <INPUT TYPE="TEXT" NAME="surname" > <BR><BR> <INPUT TYPE="submit" NAME="Submit" VALUE="Submit"> </FORM>

  12. Blur <INPUT TYPE="CHECKBOX" NAME="Popgrp" VALUE="Blur"> <BR> Five <INPUT TYPE="CHECKBOX" NAME="Popgrp" VALUE="Five"> <BR> Steps <INPUT TYPE="CHECKBOX" NAME="Popgrp" VALUE="Steps"> Note the same name is given as this is one object on the form Male <INPUT TYPE="RADIO" NAME="Gender" VALUE="Male"> Female <INPUT TYPE="RADIO" NAME="Gender" VALUE="Female">

  13. <TEXTAREA NAME="comments" ROWS=5 COLS=20> </TEXTAREA>

  14. Lists <SELECT> <SELECT NAME="Subjects" SIZE=5 MULTIPLE> <OPTION>English Language <OPTION>Mathematics <OPTION>Physics <OPTION>History <OPTION>Art <OPTION>Chemistry </SELECT>

  15. Some examples of JavaScript Objects <form action="http://osiris.sunderland.ac.uk/gun-scripts/survey.pl" name=“myForm” method="POST"> <input type="text" name=”email" size=30> document.myForm.email.value <select name="why"> <option value=0 selected>Choose one... <option value=1>It was in Sunderland <option value=2>It looked interesting <option value=3>It was an uptodate course <option value=4>My parents made me <option value=5>It was the only offer I had <option value=6>Other </select> document.myForm.comments.value document.myForm.why.value <textarea name="comments" rows=5 cols=70 wrap="VIRTUAL"> </textarea>

  16. <html> <head> <script language="JavaScript"> <!-- hide function calculation() { var x=parseFloat(document.calcu.numa.value); var y=parseFloat(document.calcu.numb.value); var result= x + y; alert(result); } // --> </script> </head> <body> <h3>My first Calculator</h3> <form name="calcu"> Input A <input type="text" name="numa" value=""> <br> Input B <input type="text" name="numb" value=""> <br> <input type="button" value="Calculate" onClick="calculation()"> </form> </body></html> assignment name of objects on form Forms, Function andJavaScript Example

  17. Data Conversion On the last example we converted a string to a real number Using parseFloat(String) Exercise: The following all convert a string to an Integer value of 10. What does the second parameter represent ? parseInt(“A”, 16) parseInt(“12”, 8) parseInt(“1010”, 2) parseInt(“10”, 10)

  18. Data Conversion Answer: The radix of the number e.g. the base of the number system Base 16 parseInt(“A”, 16) parseInt(“12”, 8) parseInt(“1010”, 2) parseInt(“10”, 10) Base 8 (1*8+1*2=10) Base 2 (1*8+0*4+1*2+0*1=10) Base 10

  19. Same Functionbetter code ! <html> <head> <script language="JavaScript"> <!-- hide function calculation(x,y) { var result= parseFloat(x) + parseFloat(y); alert(result); } // --> </script> </head> <body> <h3>My first Calculator</h3> <form name="calcu"> Input A <input type="text" name="numa" value=""> <br> Input B <input type="text" name="numb" value=""> <br> <input type="button" value="Calculate" onClick="calculation(document.calcu.numa.value, document.calcu.numb.value)"> </form> </body></html> Passing data to a function

  20. How is JavaScriptused on the Web? • To create documents ‘on-the-fly’ (client sided) • creating and closing windows, creating new documents • i.e. Pop up adverts – These are now normally blocked by default in Web Browsers • Form validation (client sided) • to reduce the load on servers by checking forms prior to posting • To increase the functionality of the user interface • improve the user interface e.g. Rollovers, Interactive Menu Systems

  21. Creating documents‘on-the-fly’ Example: Opens a new Browser window without a status bar, toolbar or menubar and then loads a new page into the window <html> <head> <script language="JavaScript"> <!-- hide function openWin2() { myWin= window.open('http://osiris.sund.ac.uk/','new_window_1', 'width=400,height=300,status=no,toolbar=no,menubar=no'); } // --> </script> </head> <body> <form> <input type="button" value="Open New Window" onClick="openWin2();"> </form> </body> </html>

  22. Another example When no file name is given, the result is a blank document function openWin3() { myWin= window.open('','new_window_1','width=400,height=300, status=no,toolbar=no,menubar=no'); // open document for further output myWin.document.open(); // create document myWin.document.write("<html><head><title>On-the-fly"); myWin.document.write("</title></head><body>"); myWin.document.write("<center><font size=3>"); myWin.document.write("This HTML-document has been created "); myWin.document.write("with the help of JavaScript!"); myWin.document.write("</font></center>"); myWin.document.write("</body></html>"); // close the document - (not the window!) myWin.document.close(); } Using JavaScript to generate HTML

  23. StandardObjects <html><head> <script Language="JavaScript"> <!-- hide var timeStr, dateStr; function clock() { now= new Date(); hours= now.getHours(); minutes= now.getMinutes(); seconds= now.getSeconds(); timeStr= "" + hours; if (minutes < 10) timeStr+= ":0" + minutes else timeStr+= ":" + minutes; if (seconds < 10) timeStr+= ":0" + seconds else timeStr+= ":" + seconds; document.clock.time.value = timeStr; date= now.getDate(); month= now.getMonth()+1; year= now.getYear(); dateStr= "" + month; if (date < 10) dateStr+= "/0" + date else dateStr+= "/" + date; dateStr+= "/" + year; document.clock.date.value = dateStr; Timer= setTimeout("clock()",1000); } // --> </script> </head> <body onLoad="clock()"> <form name="clock"> Time: <input type="text" name="time" size="8" value=""><br> Date: <input type="text" name="date" size="8" value=""> </form></body></html> Use the actual time and date as a new one isn’t specified The Date Object Returns the date and time time date Rerun the function every 1000 msec

  24. Form validation (client sided) • Can be used to • Check that all parts of the form have been completed • Check that certain characters exist • e.g. checking for the @ symbol in email address text input fields

  25. Form validation (client sided) Example function Test if the value is blank function emailtest() { if (document.myForm.email.value == "" || document.myForm.email.value.indexof('@', 0) == -1) alert("No valid e-mail address!"); else alert("OK!"); } OR Test if the value contains an @ symbol

  26. Form validation (client sided) Checking a form before it is processed by a CGI script function validate() { var formokay = true; some if statements checking the form fields (if any are invalid set the formokay to false) return formokay; } <form … onSubmit=“return validate()”> The onSubmit event handler is used

  27. COMPLETE EXAMPLE <HTML> <HEAD> <TITLE>Feedback Form</TITLE> <script language="JavaScript"> <!-- Hide function testemail(form) { var emailok = true; if (form.EMAIL.value == "" || form.EMAIL.value.indexOf('@', 0) == -1) { alert("No valid e-mail address!"); emailok=false; } return emailok; } // --> </script> </HEAD> <BODY> <h3>Feedback form</h3> <FORM METHOD="POST" NAME="feedback" ACTION="mailto:gary.unthank@sunderland.ac.uk" onSubmit="return testemail(document.feedback)"> Please enter your comments about our product<BR> <TEXTAREA NAME="comments" ROWS=5 COLS=20></TEXTAREA> <BR><BR>Please enter your email address<BR> <INPUT TYPE="TEXT" NAME="EMAIL" > <BR><BR> <INPUT TYPE="submit" NAME="SUBMIT" VALUE="Submit"> </FORM></BODY> </HTML>

  28. What is XML? An introduction to XML • XML = Extensible Markup Language • related to Standard Generalized Markup Language (SGML) • XML documents contain data only. They do not contain formatting information like HTML • Thus, it is up to the end user application to decide how the information is displayed • e.g. on a mobile phone or the Web via a Browser

  29. <?xml version = "1.0"?> <!-- Your first XML page --> <article> <title>Example One: An example XML page</title> <date>Jan 01, 2002</date> <author> <firstname>Gary</firstname> <secondname>Unthank</secondname> </author> <summary>The first example XML document</summary> <content>A very short page of XML I created to show how XML is displayed on the Web </content> </article> XML ParserProcessing an XML document IE 5.5 msxml parser Sample XML document Checks the XML document and processes the data. In IE 5.5.+ this results in the the page being displayed

  30. Example XML document <?xml version = "1.0"?> <!-- Your first XML page --> <article> <title>Example One: An example XML page</title> <date>Jan 01, 2002</date> <author> <firstname>Gary</firstname> <secondname>Unthank</secondname> </author> <summary>The first example XML document</summary> <content>A very short page of XML I created to show how XML is displayed on the Web </content> </article> XML declaration W3C current standard 1.0 Every XML document must contain one root element in which all others are placed within

  31. XML - The semantic Web • XML permits document authors to create their own markup for any type of information • Alternatively XML documents can reference an external document that defines the document structure • Document Type Definition (DTD) • Schema (created in XML) • many parsers currently do not support Schemas due to it being a recent development • The aim being to make a Web that is machine readable i.e. search more effectively

  32. Document Type Definition (DTD) A DTD enables an XML parser to verify whether an XML document is valid <!ELEMENT SimpleDTD ( title, date, author, summary, content )> <!ELEMENT title ( #PCDATA )> <!ELEMENT date ( #PCDATA )> <!ELEMENT author ( firstname, secondname )> <!ELEMENT firstname ( #PCDATA )> <!ELEMENT secondname ( #PCDATA )> <!ELEMENT summary ( #PCDATA )> <!ELEMENT content ( #PCDATA )> DTDs use Extended Backus-Naur Form e.g. the syntax, rules and structure #PCDATA Fields must contain parsed character data i.e. not <, >, and &

  33. Adding a DTD referenceto an XML page <?xml version = "1.0"?> <!DOCTYPE SimpleDTD SYSTEM "simpleDTD.dtd"> <article> <title>Example two: An example XML page using DTD</title> <date>Jan 01, 2002</date> <author> <firstname>Gary</firstname> <secondname>Unthank</secondname> </author> <summary>The first example XML document using DTD</summary> <content>A very short page of XML I created to show how XML is displayed on the Web (also uses DTD) </content> </article> SYSTEM : External DTD file

  34. XML Schema • Like XML documents schems are XML files (which have .xsd file extension) • Like DTDs these permit you to define the valid structure of an XML document • Schema also define valid element types • i.e. strings, number etc. • Read ‘Ian Stuart’s guide to Schema’ to see further example Schema. • http://lucas.ucs.ed.ac.uk/xml-schema

  35. Example: XML Schema XML-Schema elements are prefixed by xsd: <?xml version = "1.0"?> <xsd:schema xmlns:xsd = "http://www.w3.ord/2001/XMLSchema" > <xsd:element name = "article"> <xsd:complexType> <xsd:element name = "title" type = "xsd:string"/> <xsd:element name = "date" type = "xsd:string"/> <xsd:element name = "author" type = "xsd:string"/> <xsd:complexType> <xsd:element name = "firstname" type = "xsd:string"/> <xsd:element name = "secondname" type = "xsd:string"/> </xsd:complexType> </xsd:element> <xsd:element name = "summary" type = "xsd:string"/> <xsd:element name = "content" type = "xsd:content"/> </xsd:complexType> </xsd:element> </xsd:schema>

  36. Example: XML Schema Same as the previous example except a reference to the Schema is made Use elements defined by W3C <?xml version = "1.0"?> <article xmlns:xsi = "http://www.w3.ord/2001/XMLSchema-instance" xsi:MysimpleSchema = "simpleXMLSchema.xsd" > <title>Example three: An example XML page using an XML Schema</title> <date>Jan 01, 2002</date> <author> <firstname>Gary</firstname> <secondname>Unthank</secondname> </author> <summary>The first example XML document using an XML Schema</summary> <content>A very short page of XML I created to show how XML is displayed on the Web (also uses XML Schema) </content> </article> My XML Schema ! i.e. the file shown on the previous slide

  37. Why bother ? What is wrong with HTML ? • XML permits users to evolve their own XML for their particular needs • BioML : for describing biopolymer sequence information • MathML : for displaying Mathematics on the Web • CML : for describing chemical information • Structuring documents with XML helps organise the web and will improve the Web • e.g. searching the Web will be easier as the meaning of the text and graphics will be defined

  38. Machine Based Tutorial • The tutorial session requires you to: • Implement the JavaScript examples from today’s lecture and complete the further exercises • Additionally, create: • an XML page and a DTD page on a topic of your choice • an XML page and a Schema on a topic of your choice • Read through the first 6 hours (chapters) of the key text book (Bruce, B - Sams Teach Yourself Dreamweaver MX 2004 in 24 hours) in preparation for the next session.

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