Web Terminologies: Useful for web application testers - Part I

Web technology Guide

If you are working on web application testing then you should be aware of different web terminologies. This page will help you to learn all basic and advanced web terminologies that will definitely help you to test your web projects.
Web terminologies covered in this page are:
What is internet, www, TCP/IP, HTTP protocol, SSL (Secure socket layer), HTTPS, HTML, Web server, Web client, Proxy server, Caching, Cookies, Application server, Thin client, Daemon, Client side scripting, Server side scripting, CGI, Dynamic web pages, Digital certificates and list of HTTP status codes. 

• Internet
– A global network connecting millions of computers.
• World Wide Web (the Web)
– An information sharing model that is built on top of the Internet, utilizes HTTP protocol and browsers (such as Internet Explorer) to access Web pages formatted in HTML that are linked via hyperlinks and the Web is only a subset of the Internet (other uses of the Internet include email (via SMTP), Usenet, instant messaging and file transfer (via FTP)
• URL (Uniform Resource Locator)
– The address of documents and other content on the Web. It is consisting of protocol, domain and the file. Protocol can be either HTTP, FTP, Telnet, News etc., domain name is the DNS name of the server and file can be Static HTML, DOC, Jpeg, etc., . In other words URLs are strings that uniquely identify resources on internet.
• TCP/IP
– TCP/IP protocol suite used to send data over the Internet. TCP/IP consists of only 4 layers - Application layer, Transport layer, Network layer & Link layer 

Internet Protocols:
Application Layer - DNS, TLS/SSL, TFTP, FTP, HTTP, IMAP, IRC, NNTP, POP3, SIP, SMTP, SNMP, SSH, TELNET, BitTorrent, RTP, rlogin.
Transport Layer- TCP, UDP, DCCP, SCTP, IL, RUDP,
Network Layer - IP (IPv4, IPv6), ICMP, IGMP, ARP, RARP, ...
Link Ethernet Layer- Wi-Fi, Token ring, PPP, SLIP, FDDI, ATM, DTM, Frame Relay, SMDS,
• TCP (Transmission Control Protocol)

• –  Enables two devices to establish a connection and exchange data.
  
• –  In the Internet protocol suite, TCP is the intermediate layer between the Internet Protocol below it, and an application above it. Applications often need reliable pipe-like connections to each other, whereas the Internet Protocol does not provide such streams, but rather only unreliable packets. TCP does the task of the transport
  layer in the simplified OSI model of computer networks.
  
• –  It is one of the core protocols of the Internet protocol suite. Using TCP, applications on networked hosts can create connections to one another, over which they can exchange data or packets. The protocol guarantees reliable and in-order delivery of sender to receiver data. TCP also distinguishes data for multiple, concurrent applications (e.g. Web server and e-mail server) running on the
  same host.
  • IP
  
• –  Specifies the format of data packets and the addressing protocol. The Internet Protocol (IP) is a data-oriented protocol used for communicating data across a packet-switched internet work. IP is a network layer protocol in the internet protocol suite. Aspects of IP are IP addressing and routing. Addressing refers to how end hosts become assigned IP addresses. IP routing is performed by all hosts, but most importantly by internetwork routers
  

• IP Address
– A unique number assigned to each connected device, often assigned dynamically to users by an ISP on a session-by-session basis – dynamic IP address. Increasingly becoming dedicated, particularly with always-on broadband connections – static IP address.

Packet
– A portion of a message sent over a TCP/IP Network. It contains
content and destination
• HTTP (Hypertext Transfer Protocol)

• –  Underlying protocol of the World Wide Web. Defines how messages are formatted and transmitted over a TCP/IP network for Web sites. Defines what actions Web servers and Web browsers take in response to various commands.
  
• –  HTTP is stateless. The advantage of a stateless protocol is that hosts don't need to retain information about users between requests, but this forces the use of alternative methods for maintaining users' state, for example, when a host would like to customize content for a user who has visited before. The common method for solving this problem involves the use of sending and requesting cookies. Other methods are session control, hidden variables, etc
  
• –  example: when you enter a URL in your browser, an HTTP command is sent to the Web server telling to fetch and transmit the requested Web page
  

o HEAD: Asks for the response identical to the one that would correspond to a GET request, but without the response body. This is useful for retrieving meta- information written in response headers, without having to transport the entire content.
o GET : Requests a representation of the specified resource. By far the most common method used on the Web today.
o POST : Submits user data (e.g. from a HTML form) to the identified resource. The data is included in the body of the request.
o PUT: Uploads a representation of the specified resource.
o DELETE: Deletes the specified resource (rarely implemented).
o TRACE: Echoes back the received request, so that a client can see what intermediate servers are adding or changing in the request.
o OPTIONS:
o Returns the HTTP methods that the server supports.
This can be used to check the functionality of a web
server.
o CONNECT: For use with a proxy that can change to
being an SSL tunnel.

HTTP pipelining
– appeared in HTTP/1.1. It allows clients to send multiple requests at once, without waiting for an answer. Servers can also send multiple answers without closing their socket. This results in fewer roundtrips and faster load times. This is particularly useful for satellite Internet connections and other connections with high latency as separate requests need not be made for each file. Since it is possible to fit several HTTP requests in the same TCP packet, HTTP pipelining allows fewer TCP packets to be sent over the network, reducing network load. HTTP pipelining requires both the client and the server to support it. Servers are required to support it in order to be HTTP/1.1 compliant, although they are not required to pipeline responses, just to accept pipelined requests.
• HTTP-Tunnel
– technology allows users to perform various Internet tasks despite the restrictions imposed by firewalls. This is made possible by sending data through HTTP (port 80). Additionally, HTTP-Tunnel technology is very secure, making it indispensable for both average and business communications. The HTTP-Tunnel client is an application that runs in your system tray acting as a SOCKS server, managing all data transmissions between the computer and the network.
• HTTP streaming
– It is a mechanism for sending data from a Web server to a Web browser in response to an event. HTTP Streaming is achieved through several common mechanisms. In one such mechanism the web server does not terminate the response to the client after data has been served. This differs from the typical HTTP cycle in which the response is closed immediately following data transmission. The web server leaves the response open such that if an event is received, it can immediately be sent to the client. Otherwise the data would have to be queued until the client's next request is made to the web server. The act of repeatedly queing and re-requesting information is known as a Polling mechanism. Typical uses for HTTP Streaming include market data distribution (stock tickers), live chat/messaging systems, online betting and gaming, sport results, monitoring consoles and Sensor network monitoring.

 

HTTP referrer
– It signifies the webpage which linked to a new page on the Internet. By checking the referer, the new page can see where the request came from. Referer logging is used to allow websites and web servers to identify where people are visiting them from, for promotional or security purposes. Since the referer can easily be spoofed (faked), however, it is of limited use in this regard except on a casual basis. A dereferer is a means to strip the details of the referring website from a link request so that the target website cannot identify the page which was clicked on to originate a request. Referer is a common misspelling of the word referrer. It is so common, in fact that it made it into the official specification of HTTP – the communication protocol of the World Wide Web – and has therefore become the standard industry spelling when discussing HTTP referers.
• SSL (Secure Sockets Layer)

• –  Protocol for establishing a secure connection for transmission, it uses the HTTPS convention
  
• –  SSL provides endpoint authentication and communications privacy over the Internet using cryptography. In typical use, only the server is authenticated (i.e. its identity is ensured) while the client remains unauthenticated; mutual authentication requires public key infrastructure (PKI) deployment to clients. The protocols allow client/server applications to communicate in a way designed to prevent eavesdropping, tampering, and message forgery.
  
• –  SSL involves a number of basic phases:
  o Peer negotiation for algorithm support
  

o Public key encryption-based key exchange and certificate-based authentication
o Symmetric cipher-based traffic encryption
o During the first phase, the client and server negotiate which cryptographic algorithms will be used. Current
implementations support the following choices:
o for public-key cryptography: RSA, Diffie-Hellman, DSA or Fortezza;
o for symmetric ciphers: RC2, RC4, IDEA, DES, Triple DES or AES;
o For one-way hash functions: MD5 or SHA. 

HTTPS
– is a URI scheme which is syntactically identical to the http: scheme normally used for accessing resources using HTTP. Using an https: URL indicates that HTTP is to be used, but with a different default port and an additional encryption/authentication layer between HTTP and TCP. This system was invented by Netscape Communications Corporation to provide authentication and encrypted communication and is widely used on the Web for security-sensitive communication, such as payment transactions.
• HTML (Hypertext Markup Language)

• –  The authoring language used to create documents on the World Wide Web
  
• –  Hundreds of tags can be used to format and layout a Web page’s content and to hyperlink to other Web content.
  • Hyperlink
  

– Used to connect a user to other parts of a web site and to other web
sites and web-enabled services.
• Web server
– A computer that is connected to the Internet. Hosts Web content
and is configured to share that content.

– Webserver is responsible for accepting HTTP requests from clients, which are known as Web browsers, and serving them Web pages, which are usually HTML documents and linked objects (images, etc.).

• Examples:

o Apache HTTP Server from the Apache Software Foundation.
o Internet Information Services (IIS) from Microsoft.
o Sun Java System Web Server from Sun Microsystems,
formerly Sun ONE Web Server, iPlanet Web Server,
and Netscape Enterprise Server.
o Zeus Web Server from Zeus Technology 

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