History of XML Programming - Assignment Example

Exercise 8: Examine the evolution of the World Wide Web (WWW) in terms of the need for a general-purpose markup language. The early days of the WWW were very confusing period. Many programmers tried to come up with their own ideas on ways the web should develop, this threatened the web with a mass of uncoordinated protocols that required different software systems for different applications. This led to Tim Berners-Lee among others forming the World Wide Web Consortium to develop and promote standards for use on the Web. The Consortium ensures there are common standards used in all the browsers through a general-purpose markup language. According to (Liener) the World Wide Web Consortium has taken up the responsibility and task for evolving various protocols and standards that are associated with the WWW. Draw conclusions about the power and advantages of XML that have made it the global standard for enterprise data exchange. According to (Tidwell 4) XML has the ability to do data interchange. Most organizations rarely standardize their content on a single set of tools, therefore it takes a lot of work for different groups in different organizations to communicate. However XML will makes it easy and possible to send structured data across the internet ensuring nothing gets lost during translation. When using XML, you can receive XML-tagged data from another system, and the another system can receive data that is XMLtagged from your system. The two systems do not have to know how the other system is organized. If another person teams up with your organization, you will not be required to write code to exchange Data with different systems. The other system will simply be required to follow rules defined In the DTD. XML does makes it relatively easier for two or more computers to exchange data. The data is described using tags that define each piece of data. XML does not replace HTML, it is designed for use on different purposes. XML is the language used on the web for data interchange while HTML is the language used on the web for rendering. Compare and contrast Data Type Definitions (DTD) and XML Schemas. The major difference between XML Schema and DTDs is that XML Schema utilize an XML-syntax, while DTDs use a unique syntax that is held from SGML DTDs. XMLs heritage is in the Standard Generalized Markup Language (Peterson 12). DTDs are mostly criticized by developers because of the need to learn a new syntax. The opposite has always been true for XML Schema, which can be verbose, but also make use of tags and XML so that users of XML can find the syntax of XML Schema less intimidating. The main goal of the DTDs was to maintain a level of compatibility with SGML for all the applications may want to convert SGML DTDs to XML DTDs. The biggest difference between DTDs and XML Schema is its capacity to create and use datatypes in the Schema in conjunction with element and the attribute declarations DTD is not namespace-aware as they are part of the original XML specification as were specified later. It is possible to use DTDs with namespaces, but it requires you will be forced to define the prefixes in the DTD and using only those prefixes. Evaluate Global Elements, NameSpaces, and XML Metadata Models (XHTML, DocBook, Resource Description Framework (RDF), and Really Simple Syndication (RSS). RDF supports use of various conventions that facilitate modular interoperability among different metadata element sets(Miller). The conventions used include standard mechanisms that allow representation for semantics that are well grounded in a simple and powerful, data model. RDF provides a means for publishing both machine and human readable vocabularies. The namespaces serve as a way of grouping XML and to differentiate between elements that have the same name. Namespace comes into great use when the tags created by one user need to be differentiated from the tags created by a different user. This is basically achieved by assigning a name to the tags. The name is the namespace prefix. Global Elements help us in the reuse of content model definitions found within our defined XML Schema, this will be done using global types . When referring to global element declarations, we will use a ref attribute that will help us specify the name of our global element as its value. The Docbook namespace can basically be used to mark up technical publications and hardware and software manuals, there is no particular reason as to why it cannot be used for other topics RSS is the easiest way to publish frequently updated content such as news headlines or web logs. The real simple syndication document will contains the summary of the content of an associated site. The content length to be displayed through the RSS will depend on the length of the update or a predefined length. The RSS Reader will keep checking the subscribed sites regularly for any updates and downloads them to your site. Interpret the need, the principles, and the power of XSL and XSLT to create new content, manage site layout, extract information, and for document format conversion. Traditionally the alternative that has been used in document formatting has been the cascading style sheets however CSS styling has the following weakness CSS cannot reorder elements from the XML document. CSS cannot reorder add new elements. CSS cannot reorder decide which elements should be displayed/omitted. CSS cannot reorder provide functions for handling numbers/strings/Booleans As a result of the above mentioned weakness XSL and XSLT has become necessary as they are able to give a powerful data structural transformation, from your input to your desired output structure. An important facet of system development, in any programming language, is code reuse. XSLT has different ways of letting you write style sheets that can be used in different place XSLT and XSL has capacity to format data to the desired output structures and enrich it with target format constructs. Discuss the process for creating XML documents and apply this knowledge to develop XML and DTD documents. The process for creating XML document is composed of three major steps and these are: i) Defining your own tags On the first line of an XML document is the XML declaration, it is a must that you define your own tags. The XML declaration will makes clear that are communicating with XML and the particular version to be used. ii) DTD or the Schema If you intent to use a tag, you have to define the meaning of the tag. This definition will be stored in a DTD. Its possible to define your own DTD or just customize an existing DTD. iii) Display the results It is not a must for one to display XML document.You can have your data stored in a Database, If you wish to display the data,it is possible to do so. XML is not capable of executing such a task. However XML documents are made visible with the aid of a language that can define the presentation. XSL is created for such a purpose, the user presentation can also be defined using the Cascading Style Sheets. The following are the basic rules that govern a well formed document a) Ensure that your document contains a root element b) Ensure all other elements are children of root element c) Make sure all elements are correctly paired Analyze the ability of XML to facilitate inter-application and inter-tier communications. Utilizing XML it is possible to construct a system that can rapidly be easily redeployed to new platforms as they are developed. This is possible because XML does inherit from its own SGML lineage the idea of separating physical and logical data representations. Logically, digital asset can be said to be comprised of metadata and its content, physically, the two components may be stored in any number of ways. This is where the XML conception of entities is useful. Inter communication between different application has been a major problem.XML was developed as a solution to this problem it is used to make passing of data between various components much simple and remove the worry about different formats of input and output. It frees up system developers to concentrate on the core aspects of system coding. Most people see XML as a big solution to the question of whether fi les should be easily readable by human or software. Analyze the need to apply XSL and XSLT to standardize the look and feel across pages and to generate multiple formats of the same page. XSL Formatting is an alternative to CSS. XSLT is a reasonably simple and easy to understand. XSLT is basically based on the notion of templates. The idea is that you have to specify a number of template that each match XML in your source document. When a matching XML is found, the template can be activated then its contents added to the main output document hence its able to do a good job of standardizing the look and feel of pages to different formats depending on the template activated. The XSLT gives you the power to affect different elements with different formats according to ones preferences References 1. Joe, Liam. E, Quin Ayers . Beginning XML. Indianapolis . John Wiley & Sons, Inc.,2012 2. Leiner, Vinton, and David Clark. ” A brief history of internet. “ Internet Society. December 2003. Web. 3 April 2013. 3. Miller, Eric.” An Introduction to the Resource Description Framework”. D-Lib magazine. Computer Library Center, Inc, May 1998. Web. 01,April,2013. 4. Peterson ,David.” Mastering XSLT”. New York: Penguin, 2004. Print 5. Tidwell, Doug. Introduction to XML. Raleigh, NC.1999, print Read More