Web Technology Questions

- A web worker is a JavaScript which runs in the background. It exists in external files. 

 - It is independent of other scripts and does not affect the performance of the page. 

 - Web workers are usually used for CPU intensive tasks.

XML, Extensible Markup Language, is an open, text based markup language that provides structural and semantic information to data. XML is a metalanguage that can be used to create other language. It is used to structure and describe data that can be understood by other applications. Using XML, we can separate the user interface from data.

Features of XML :

- XML is a generalized markup language that means one can define his/her own tag sets.

- A valid XML document contains rules and is self-describing.

- The rules that are found in DTD allow the documents to be validated.

SQL Server is having a fantastic feature to retrieve data persisted in the form of XML format. The data in the XML format can be retrieved using FOR XML clause appending to the SELECT statement.

It offers 3 modes.

- “FOR XML AUTO": Returns XML elements that are nested, based on which tables are listed in the "from" part of the query, and which fields are listed in the "select" part.

- "FOR XML RAW": Returns XML elements with the "row" prefix (ex: ""). Each column in a table is represented as an attribute and null column values aren't included.

- "FOR XML EXPLICIT": Explicit mode is the most complex shaping method used in SQL Server 2000. It allows users to query a data source in such a way that the names and values of the returned XML are specified before the query batch is executed. 

The <span> tag is used to group inline-elements in a document.

The <span> tag provides no visual change by itself.

The <span> tag provides a way to add a hook to a part of a text or a part of a document.

EX :

<p>My Car Color is <span style="color:blue">blue</span> </p>

- Class selector can be given to an overall block. This is sometimes termed as block element as well, whereas ID selector identifies a unique name and a style for a specific element. 

- ID selector declares the style for only one particular element which can be differentiated from other element, whereas Class selector is being given for the whole complete block.

With HTML5, it is possible for the web pages to store the data locally in the user's browser. This web storage is much faster and secured than the cookies. Also, a larger amount of data can be stored without causing any adverse effect to the performance of the website. 

The data here is not included with every server request. It is used ONLY when it is asked for. It is only that particular web page that can access the data stored by itself.

Web application provides services (Free and Paid) apart from information.

Ex: Online Banking System

It provides Bank  information , Branches & ATM information, Loans information etc...

And It provides balance enquiry, Fund transfer, Bill payments like services.

Some important differences between Canvas and SVG:

- Canvas is resolution dependent while SVG is not. 

- Canvas does not provide any support for event handlers while SVG does. 

- Canvas is suitable for graphic-intensive games while SVG is not suitable for gaming.

- Canvas is suitable for small rendering areas while SVG is suitable for large rendering areas like Google maps.