The differences between Cloud and Grid computing are listed below:

1. Cloud computing normally runs in a set of homogeneous computers, but Grid, on the other hand, runs on heterogeneous computers.

 2. Grid computing is normally focused on an intensive calculus, while Cloud Computing offers two types of calculuses: standard and intensive.

3. Grid computing is open-source while Cloud Computing is not.[7]. This creates interoperatibility problems between today’s Clouds.

4. Most Grids use a batch-scheduled compute model, while in Cloud Computing all users share all the resources at the same time. And this is why latency sensitive applications, which could run in Grids, could no be supported in Cloud Computing.

5. Grids do not rely on virtualization as much as Cloud does.

6. Cloud Computing does not support as much provenance as Grid does[4], which is a “derivation history of a data product, including all the data sources, intermediate data products,and the procedures that were applied to produce the data product”.

7. High Performance computing is better supported in Grid computing than in Cloud Computing.

8. Grid is distributed, has multiple research user communities (including users accessing resources from varied administration domains) and is grouped in Virtual Organisations. Cloud Computing, on the other hand, usually has only one research community and a common group of system administrators that take care of the entire Cloud.

9. Grid is mostly publicly funded at local, national and international levels, while Cloud Computing is funded mainly by its users

10. Grid computing, must share user and resource inter- faces to allow providers to connect their resources, while Cloud Computing attempts to share only the user interface while the resources interfaces are hidden and given in an abstract way.

11. In Grid computing, the trust model is based on identity delegation, where users can access and browse resources,which are not highly abstracted and virtualized at different Grid sites. In Cloud computing resources are abstracted and virtualized and this trust model does not exist since everything is inside the same Cloud.

12. While in Grid computing, storing very small files (e.g.1-byte files) is not economically suitable, in CloudComputin it is.

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Internet Technology

1.     What do you mean by Network infrastructure? Explain with suitable example.

2.     What do you mean by Internet? Explain its history in brief.

3.     Explain the terms domain, domain name system, marine cables, teleports, terrestrial links and satellite with example.

4.     How does TCIP/IP differ from OSI?

5.     Compare and Contrast IPV4 and IPV6.

6.     Explain header structures of IPV4 and IPV6.

7.     What do you mean by RFC? Explain its importance.

8.     What do you mean by POP? How does it differ from SMTP?

9.     Explain N-tiered client/server architecture with example.

10.  What do you mean by HTTP? Explain its headers and characteristics.

11.  What is AJAX? Explain its working and importance.

12.  Explain browser as rendering engine.

13.  What are the steps required to configure Internet servers? Explain with any example.

14.  Differentiate among Internet, Intranet and Extranet.

15.  Explain the concept of VPN.

16.  Why is UMS important? What are its features and importance’s?

17.  Explain the working of VOIP?

18.  What is IRC? Why is it required? What are its pro and cons?

19.  What do you mean by e-commerce? What are its types? Explain with examples.

20.  What do you mean by grid computing? How does it differ from Cloud computing?

21.  What do you mean by cloud computing? What are its characteristics? List the servicers offered by cloud computing.

22.  What do you mean by CMS? Why is it required? Explain its advantage and disadvantages.

23.  What do you mean by data warehouse? Explain its architecture.

24.  What do you mean by data mining? Explain its methods.

25.  Explain why data center is important.

26.  Write down the Intranet implementations guidelines. 

27. What do you mean by Satellite Communication? Define Satellite link.

28. What do you understand by URL naming convention? Explain its parts. 

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Structure of Web Browser

Fig: Structure of Web Browsers

All the modern browsers have following parts:

1. The user interface - This consists of  the address bar, back/forward button, bookmarking menu etc. Every part of the browser display except the main window where you see the requested page.
2. The browser engine - The browser engine performs the actions between the UI and the rendering engine.
3. The rendering engine - It is responsible for displaying the requested content. For example if the requested content is HTML, it is responsible for parsing the HTML and CSS and displaying the parsed content on the screen.
4. Networking - It is used for network calls, like HTTP requests. It has platform independent interface and underneath implementations for each platform.
5. UI backend - It is used for drawing basic widgets like combo boxes and windows. It exposes a generic interface that is not platform specific. Underneath it uses the operating system user interface methods.
6. JavaScript interpreter. It is used to parse and execute the JavaScript code.
7. Data storage. The browser needs to save all sorts of data on the hard disk, for examples, cookies. The new HTML specification (HTML5) defines 'web database' which is a complete (although light) database in the browser.This is a persistence layer.

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The browser's main Functionality

The browser main practicality is to gift the net resource you select, by requesting it from the server and displaying it on the browser window. The resource is typically associate degree markup language document, however can also be a PDF, image, or different kind. the placement of the resource is such by the user employing a URI (Uniform resource Identifier).

The method the browser interprets and displays markup language files is per the markup language and CSS specifications. These specifications ar maintained by the W3C (World Wide net Consortium) organization, that is that the standards organization for the net.
For years browsers conformed to solely a district of the specifications and developed their own extensions. That caused serious compatibility problems for net authors. these days most of the browsers additional or less adjust to the specifications.

Browsers' interface have plenty in common with one another. Among the common interface parts are:

•     Address bar for inserting the URI
•     Back and forward buttons
•     Bookmarking choices
•     A refresh and stop buttons for refreshing and stopping the loading of current documents
•     Home button that gets you to your home page

Strangely enough, the browser's interface isn't per any formal specification, it simply comes from sensible practices formed over years of expertise and by browsers imitating one another. The HTML5 specification does not outline UI parts a browser should have, however lists some common parts. Among those ar the address bar, standing bar and gear bar. There are, of course, options distinctive to a particular browser like Firefox's downloads manager. Learn more »

CHECKSUM

The error detection method used by the higher layer protocols is called checksum. It consists of two arts. They are,

1.     checksum generator

2.     checksum checker

Checksum Generator:

In the sender, the checksum generator subdivides the data unit into equal segments of n bits. These segments are added with each other by using one’s complement arithmetic in such a way that the total is also n bits long. That total is then complemented and appended to the end of the data unit.

Checksum Checker:

The receiver subdivides the data unit as above and adds all segments together and complements the result. If the extended data unit is intact, the total value found by adding the data segments and the checksum field should be zero. Otherwise the packet contains an error and the receiver rejects it.

EXAMPLE

At the sender

Data unit:   10101001 00111001

10101001

00111001

Sum   1100010

Checksum 00011101

At the receiver

1)

Received data: 10101001 00111001 00011101

10101001

00111001

00011101

Sum 11111111

Complement 00000000

It means that the patter is ok.

2)

Received data: 1010111 111001 00011101

10101111

11111001

00011101

Result 11000101

Carry   1

Sum 11000110

Complement 00111001

It means that the patter is corrupted.

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CRC is based on binary division. In this a sequence of redundant bits, called CRC remainder is appended to the end of a data unit so that the resulting data unit becomes exactly divisible by a second predetermined binary number. At its destination, the incoming data unit is divided by the same number. If at this step there is no reminder, the data unit is assumed to be intact and therefore accepted. A remainder indicates that the data unit has been changed in transit and therefore must be rejected.

Here, the remainder is the CRC. It must have exactly one less bit than the divisor, and appending it to the end of the data string must make the resulting bit sequence exactly divisible by the divisor.

Fig: How CRC Works

First, a string of n-1 0s is appended to the data unit. The number of 0s is one less than the number of bits in the divisor which is n bits. Then the newly elongated data unit is divided by the divisor using a process called binary division. The remainder is CRC. The CRC is replaces the appended 0s at the end of the data unit.

The data unit arrives at the receiver first, followed by the CRC. The receiver treats whole string as the data unit and divides it by the same divisor that was used to find the CRC remainder. If the remainder is 0 then the data unit is error free. Otherwise it having some error and it must be discarded.

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The Hypertext Transfer Protocol (HTTP) is a protocol used mainly to access data on the World Wide Web. The protocol transfer all data in the form of plain text, hypertext, audio, video, and so on. However it is called the hypertext transfer protocol because its efficiency allows its use in a hypertext environment where there are rapid jumps from one document to another.

HTTP functions like a combination of FTP and SMTP. It is similar to FTP because it transfers files and uses the services of TCP. However, it is much simpler than FTP because it uses only data are transferred between the client and the server.

HTTP is like SMTP because the data transferred between the client and server look like SMTP messages. In addition, the format of the messages is controlled by MIME-like headers.

However, HTTP differs from SMTP in the way the messages are sent from the client to the server and from the server to the client. Unlike SMTP, the HTTP messages are not destined to be read by humans; they are read and interpreted by the HTTP server and HTTP client (browser). SMTP messages are stored and forwarded, but HTTP messages are delivered immediately.

The idea of HTTP is very simple. A client sends a request, which looks like mail, to the server. The server sends the response, which looks like a mail reply, to the client. The request and response messages carry data in the form of a letter with MIME-like format.

The commands from the client to the server are embedded in a letter like request message. The contents of the requested file or other information are embedded in a letter like response message.

Fig: HTTP

HTTP Transaction

Figure illustrates the HTTP transaction between the client and server. The client initializes the transaction by sending a request message. The server replies by sending a response.

Messages

There are two general types of HTTP messages, shown in figure request and response. Both message types follow almost the same format.

Request Messages

A request message consists of a request line, headers, and sometimes a body.

 Response Message

            A response message consists of a status line, headers, and sometimes a body.

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File transfer protocol (FTP) is the standard mechanism provided by TCP/IP for copying a file from one host to another. Transferring files from one computer to another is one of the most common tasks expected from a networking or internetworking environment.

Fig: FTP

Although transferring files from one system to another seems simple and straight-forward. Some problems must be dealt with first. For example, two systems may use different file name conventions. Two systems may have different ways to represent text and data. Two systems may have different directory structures. All of these problems have been solved by FTP in a very simple and elegant approach.

FTP differs from other client-server applications in that it establishes two connections between the hosts. One connection is used for data transfer, the other for control information (commands and responses). Separation of commands and data transfer makes FTP more efficient. The control connection uses very simple rules of communication. On the other hand, needs more complex rules due to the variety of data types transferred.

The client has three components:

·      The user interface

·      The client control process

·      The client data transfer process

The server has two components:

·      The server control process

·      Server data transfer process

The control connection is made between the control processes. The data connection is made between the data transfer processes.

The control connection remains connected during the entire interactive FTP session. The data connection is opened and then closed for each file transferred. It opens each time commands that involve transferring files are used, and it closes when the file is transferred. The two FTP connections, control and data, use different strategies and different port numbers.

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What is CMS?
A Web Content Management System can be defined as a software system that bestows website authoring, association, and administration tools designed to permit individuals with little knowledge of web programming languages or markup languages to build and organize website content with relative ease.

A CMS features include ease of use, and simplicity in modification and extension, ease of design change and manipulation, user management, page managements, menus management etc. A great CMS should permit users, who have no previous experience of traditional website coding, to be able to easily build and manipulate their websites.

CMS design

A CMS website can be designed using Content Management System.  Users can simply add text and images to a site, resize images, edit and delete text within the website. A CMS Website should also allow us to have free creative reign on our design, offer us an unlimited amount of pages for our website, and be SEO (Search Engine Optimization) friendly. The design of website can be edited according to our desire provided we have little or more web designing knowledge. The best practice found in the market is to use the templates that best fit our requirement. We can get thousands of templates free on Internet or we can simply purchase them from template developers.

Why to use CMS?
The CMS we use to create a website is simple, quick and requires no previous experience by the user.  Everything you need to design your website, is built into our CMS website builder. 

Some of the advantages of using CMS are;
* Easy to use – no technical or previous web experience is required.
* Can update from any Internet connection in the world.
* Unlimited free email support from our Support Team.
* Save money by creating your own website.
* Save money by updating your website whenever you need.
* Every change can be made from within your site builder login panel
* Suitable for people with only the most limited of computer knowledge.

Choices

If you are thinking what alternatives do I have for CMS, then that is a worth question. There are lots of different alternatives in CMS builders. Some of them are: Drupal, TYPO3, Joomla, Wordress. It does not matter which one do you choose, what matters is you choose one and gain its structure knowledge and usability knowledge. It is better to select one and work on it rather than going for more than one option.

Drawbacks

If the website is large enough, user may require training, planning, and certifications. Maintaining CMS may require license updates, upgrades, and hardware maintenance. Larger CMS can experience latency if hardware infrastructure is not up to date, if databases are not being utilized correctly, and web cache files that have to be reloaded every time data is updated grow large. Because the URLs of many CMSs are dynamically generated with internal parameters and reference information, they are often not stable enough for static pages and other Web tools, particularly search engines, to rely on them.

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