INTERNET

Assalamualaikum readers !

In this entry we would like to explain the general idea about internet. Nowadays, there is no doubt that everyone is using the internet. But, how many of us know about the history and the development of internet. Thus, we are here to help you so that we will appreciate the technologies that are available for us.

Internet

Internet is the largest network of networks in the world. It uses TCP/IP protocols and packet switching. It runs on any communications substrate. ARPAnet was created in 1968 by DARPA (Defense Advanced Research Projects Agency) with BBN (Bolt, Beranek & Newman). In 1970, first five nodes were invented. Later, in 1974 Vint Cerf specified TCP. On January 1 of 1984, TCP/IP was used for its messaging.

History of Internet

Benefits of Internet

- Inventing digital networking

- Survivability of an infrastructure to send or receive high-speed electronic messages.

- Reliability of computer messaging

URL (Universal Resource Located)

Each page of information on the web has a unique address called the URL at which it can be found. For example :

http://faculty.uscupstate.edu/atzacheva/lecture1.html

http - protocol

faculty.uscupstate.edu - host name

atzacheva, lecture1, html - file name

Protocols Names	Use
ftp://	File transfer
http://	Hypertext
https://	Hypertext secure
Mailto:	Sending email
News:	Requesting news
Telnet://	Remote log in

Problems before the invention of Internet

1. Using different packet-switching networks 

    - only nodes on the same network could commmunicate

2. Application-layer getaways

    - difficult to deploy new Internet-wide applications

3. No global addressability

After the invention of Internet earlier, there are Internetworking problem but this problem was overcome by using the IP solution. IP solution is a Internet-layer gateaways & global adresses. It is simple, application-independent, lowest denominator and network service. Then we have Network-layer Overlay model which define a new protocol (IP) and map all application or networks to IP.

Original TCP/IP (Cerf & Kahn)

No separation between transport (TCP) and network (IP) layers. It uses one common header and also byte-based sequence number to flow control but not congestion control.

Today's TCP/IP

Separate transport (TCP) and network (IP) layer. Now it is congestion control.

Converting a 32-bit Internet Address to Dotted Decimal Format

01011110000101001100001111011100

1) Divide the IP address into four octets 

01011110 00010100 11000011 11011100 

2) Convert each binary octet into a decimal number 

01011110 = 64+16+8+4+2 = 94 00010100 = 16+4 = 20 11000011 = 128+64+2+1 = 195 11011100 = 128+64+16+8+4 = 220

3) Write out the decimal values separated by periods 94.20.195.220

Here the link for details of IP address : IP address

Domain Name System

It is difficult for us to remember the IP addresses of all the websites. The domain name system translates between domain names and IP addresses of devices connected to the Internet. Examples of top level domains are : .com, .biz and .edu

That is all from us. Thank you for reading :)

XML

Assalamualaikum my friends!

What is XML? Is it same with HTML?
No. It is not. XML stands for Extensible Markup Language. This language is much like HTML but its tags are not predefined, however XML is not replacement for HTML.

Differences between XML and HTML 

XML :
- Designed to transport and store data, with focus on what data is.
- It is about carrying information.
- All elements must be properly nested within each other:
<b><i>This text is bold and italic</i></b>
- The white-space in a document is not truncated

HTML :
- Designed to display data, with focus on how data looks
- It is about displaying information
- Improperly nested elements are allowed:
<b><i>This text is bold and italic</b></i>
- Truncates multiple white-space characters to one single white-space:
HTML: Hello my name is Tove
Output: Hello my name is Tove

There are three types of XML :

Number	Types of XML
1	Document
2	Tree
3	Table

XML document

<?xml version="1.0" encoding="ISO-8859-1"?>

<note>

<to>Tove</to>

<from>Jani</from>

<heading>Reminder</heading>

<body>Don't forget me this weekend!</body>

</note>

Now, we will explain briefly how to create XML document. Firstly, we put the XML declaration at the first line. It defines the XML version (1.0) and the encoding used (ISO-8859-1 = Latin-1/West European character set). The next line describes the root element of the document : <note>. The next four lines are the child elements of the root and the last line defines the end of the root element : </note>

XML tree

XML documents can form a tree structure. Here are the example of XML tree :

The image above represents one book in the XML below:

<bookstore>

<book category="COOKING">

<title lang="en">Everyday Italian</title>

<author>Giada De Laurentiis</author>

<year>2005</year>

<price>30.00</price>

</book>

<book category="CHILDREN">

<title lang="en">Harry Potter</title>

<author>J K. Rowling</author>

<year>2005</year>

<price>29.99</price>

</book>

<book category="WEB">

<title lang="en">Learning XML</title>

<author>Erik T. Ray</author>

<year>2003</year>

<price>39.95</price>

</book>

</bookstore> 

XML table

The image below represent the XML table :

I think that is all from us this time. If you want to know more details about this XML, you may watch this video : An Introduction to XML

Thanks for reading. Till we meet again :)