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Standards and Increasing Maintainability on Web- based Systems James Eaton SE4112/16/2006.

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Presentation on theme: "Standards and Increasing Maintainability on Web- based Systems James Eaton SE4112/16/2006."— Presentation transcript:

1 Standards and Increasing Maintainability on Web- based Systems James Eaton SE4112/16/2006

2 2 Overview  Advantages of using standards  Costs of using standards  Organizations  HTML  CSS  JavaScript  XML  Accessibility

3 Information from 3 Why Are Standards Important  Lower Cost of Production  Allows more people and devices to access web sites  Allows for backward compatibility  Search engines can do a better job  Increase Maintainability

4 Information from 4 Costs of No Standards  Some web sites could only be displayed correctly on a certain browser  Developers would have to write the same code multiple times for each browser and some people would still be left out  Loss of appeal and functionality to be multiple browser compliant

5 Information from 5 Costs of No Standards  Tricks that would work for getting pages to display correctly on multiple browsers would not work in the next generation of browsers  People with disabilities cannot access web sites

6 6 Organizations  W3C – World Wide Web Consortium  ISO – International Organization for Standardization  ECMA – European Association for Standardizing Information and Communications Systems

7 Information from 7 HTML  Stands for Hyper Text Markup Language  An HTML file can be created using a text editor like notepad or a program like front page  An HTML file is a text file that contains markup tags which tell the Web browser how to display the page

8 8 Example HTML Example simple simple green green

9 Information from 9 HTML 4.01  Original HTML was designed to define the content of a document and not intended to contain tags for formatting  All formatting can be removed and put into a style sheet  Specification

10 10 Example of HTML 4.01 Example p { color: green }

simple

green


11 Information from 11 XHTML  Extensible Hyper Text Markup Language  XHTML hopes to replace HTML  XHTML is stricter than HTML 4.01 but is almost identical  XHTML allows you to write well-formed documents that are also backward compatible

12 12 XHTML  “Ensures that elements are properly nested” This text is bold and italic This text is bold and italic  “XHTML documents must be well-formed”  “Tag names must be in lowercase” Tags in HTML aren’t case sensitive Tags in HTML aren’t case sensitive  “All XHTML elements must be closed” This does not follow XHTML This does not follow XHTML But will work in HTML But will work in HTML Information from

13 13 CSS  Cascading Style Sheet  Allows for separating structure and presentation  Styles define how to display HTML elements  Cascading Order: 1. Browser Default 2. External Style Sheet 3. Internal Style Sheet 4. Internal Style

14 14 Example of Bad Code Example simple simple green green

15 15 Same Example Code Example p { color: green }

simple

green


16 16 Validate   is XHTML 1.0 Strict  W3C is a source of recommendations for Web designers but is not a standards group  ISO is a standards group that can give their seal of approval

17 17 Standards  HTML 4 is an SGML application conforming to International Standard ISO Standard Generalized Markup Language [ISO8879]  SGML is a language for describing markup languages Information from

18 Infomation from 18 Validating HTML  An HTML file is validated against a DTD   DTD stands for Document Type Definition  DTDs define the document structure with a list of legal elements  Three document types available for HTML are Strict, Transitional, and Frameset  The DTD must be the first line in the file

19 Information from 19 Strict    Strict follows the W3C specification exactly and does not allow deprecated elements or attributes  It does not allow framesets

20 Information from 20 Transitional    This allows everything the strict DTD allows and allows deprecated elements and attributes  This also does not allow framesets

21 Information from 21 Frameset    This includes everything in the transitional DTD and allows framesets

22 Information from 22 Validating XHTML  Works the same as HTML but would include these DTDs at the top of your file instead  

23 Information from 23 Validating CSS  Specification   Firefox extensions

24 Information from 24 JavaScript  JavaScript is a scripting language that allows for additional interactivity Dynamic Text Dynamic Text Validate Data Validate Data  JavaScript is nothing like Java  ECMAScript is the official name  ECMA is standardizing JavaScript

25 Information from 25 JavaScript  international.org/publications/standards/Ec ma-262.htm

26 Information from 26 XML  Extensible Markup Language  XML was designed to describe data  XML tags are not predefined  XML should be self-descriptive  /

27 27 Example XML XSLT Cookbook XSLT Cookbook Sal Mangano Sal Mangano ...

28 Information from 28 XML Validation   XML definition

29 Information from 29 XSLT  Extensible Stylesheet Language Transformations   XSLT can transform XML into different formats like HTML or WML to be displayed on the correct browser  XSL is like a stylesheet for XML  

30 30 Example XSLT

Shelve

TitleAuthor

31 Information from 31 Server-Side Scripting  Dynamically edit, change, or add any content of a Web page  Respond to queries or data submitted from HTML forms

32 Information from 32 Accessibility  WAI – Web Accessibility Initiative  Created by W3C in 1997  Set of guidelines on how to make information accessible to people with disabilities and more browsers 

33 Information from 33 Reasons to Increase Accessibility  It will improve your reputation and image  It will improve your customer satisfaction  It will increase your number of visitors  It will let your visitors stay longer at your site  It will increase the number of returning visitors  It will make your site more usable also for people with no disabilities

34 Infromation from 34 Reasons to Increase Accessibility  It will make your site more usable for users with images turned off  It will make your site more usable for users with older equipment  It will let you reach the fastest growing population: older people

35 Information from 35 Things to Consider  Use the alt attribute  Use a short but descriptive title  Use relative size values  Avoid stylish fonts  Always define a background color  Watch for color contrasts

36 Information from 36 Accessibility  Search engines can index information accurately  Newer web browsers will be able to access old pages  Validators can be used to find errors  Transition to new devices like PDAs

37 37 Conclusion  By following standards, development time can be decreased, maintainability can be increased, and debugging becomes easier.

38 38 References     


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