THIRD TASK

What is XML well formedness and how could you measure it?

 XML Well Formed ness is another term to describe how an XML document is to be properly constructed, following its syntax and constructions rules.
An XML document that is well formed will contain:

•    A One root element – which refers to an XML document which is constructed with only the first element to appear in the document. This root element always defines what type of file is being created, and such an element in XML can be called by whatever name the developer chooses.

•    Correct nesting – This refers to an XML document which contains its elements in correct nests which are all properly closed at the end.

•    Well-Formed Entities – This refers to the proper naming of entities with-in the XML document. In XML, such entity must be created in the DTD or the Document Type Definition. Creating the entity requires appropriate use of XML syntax.

What is XML validation and how could you measure it?

The validation of an XML document can only be measures by making sure that the document if well formed. If a document follows the criteria of ‘well-formed’, it must then be validated via the input a DTD. This DTD which can be chosen by the developer must be referenced in the XML processor. Note that the DTD will also define the rules and type of document, thus being the only method for defying the validation of the XML document. In order to measure the validation, one can simply run the file and see whether or not the processor accepts the document. Note that the processor will not acknowledge the document unless its DTD is properly referenced.

How can XML be best presented?

XML is ‘best’ presented if the rules of well formed ness are followed. In other words, opening and closing tags correctly, constructing and placing the document inside a HTML body, if it’s supposed to be used in a web page. Depending on the type of content that is being displayed, one may argue that the way to display content may change to fit each style uniquely. But in terms of actually writing an XML document, its presentation must be done in accordance to the standard rules.

What is the importance of the first line of an XML document?

 The first line that usually appears when writing XML is as follows: <?xml version="1.0" encoding=”utf-8”?> xml version="1.0" is the version of XML currently being used. The version number has to conform to the XML document being written else the document has an error. All XML documents use characters from the Unicode range, meaning any correct Unicode character will not produce errors inside an XML document. These characters can be encoded for storage in different ways called encodings, an example is encoding=”utf-8” as seen above.

What are the differences and uses between elements and attributes?

An element essentially describes the data that it holds. They are usually defined by their name and data type.

Attributes provide additional information about elements, for example, the file type. It may not be part of the element but is necessary for the software to manipulate the element. Attributes do not actually hold raw data like elements do. There is no set rule about when to use elements or attributes. It is generally dependent on your application.

What is AJAX?

Ajax short for Asynchronous JavaScript and XML is a group of interrelated web development techniques used on the client-side to create interactive web applications. With Ajax, web applications can retrieve data from the server asynchronously in the background without interfering with the display and behavior of the existing page. The use of Ajax techniques has led to an increase in interactive or dynamic interfaces on web pages. Data is usually retrieved using the XMLHttpRequest object. Despite the name, the use of XML is not actually required, nor do the requests need to be asynchronous.Like DHTML and LAMP, Ajax is not a technology in itself, but a group of technologies. Ajax uses a combination of HTML and CSS to mark up and style information. The DOM is accessed with JavaScript to dynamically display, and to allow the user to interact with, the information presented. JavaScript and the XMLHttpRequest object provide a method for exchanging data asynchronously between browser and server to avoid full page reloads.