by Dinesh Thakur Category: introduction to Servlet

HTTP headers are the request to a server for information and the resulting response. When you input an address into your browser, it sends a request to the server hosting the domain and the server responds. You can see the request and response using the basic HTTP Header Viewer. The HTTP Header Viewer can be used to view the Headers or Headers and Content of any valid http:/ / url. When the HEAD is selected, the request is for the server to only send header information. AGET selection requests both headers and file content just like a browser request. Information in response headers may include:

• Response status: 200 is a valid response from the server.

• Date of request.

• Server details: type, configuration and version numbers. For example, the PHP version.

• Cookies: cookies set on your system for the domain.

• Last-modified: this is only available if set on the server and is usually the time the requested file was last modified.

• Content-Type: TEXT/HTML is a HTML web page, TEXT/XML an XML file. Content of files that are not text based will be displayed in their encoded form. This means you will not see an image for a gif file but the underlying encoding will be displayed. For text based files including web pages (.html, .htm, .php .asp), Cascading Style Sheets (.css), JavaScript (.js), and XML files (.xml) the file content will be displayed. The content displayed is the same as displayed when using View Source in a browser.

 

HTTP header viewer

URL: Input a full URL including the http://. Any valid http://URL is acceptable. This can be used to view the http headers and content of your own web pages or any public pages or files on the internet.

HEAD: responds with HTTP headers only.

GET: responds with HTTP headers and content.

Protocol

Every communication system uses a prescribed Performa to exchange messages. So in all these syntaxes, semantics and synchronization are defined by protocols. In communication, the protocols are implemented upon the parties involved. Protocols can be designed as software or hardware or both. For example, in digital systems protocol is expressed in algorithms.

There are two kinds of protocol

1. Application Level Protocol: It defines rules of interaction between software and software application.

2. Network Level Protocol: It defines rules for interaction between computers.

For example: TCP/IP

• Protocol HTTP defines the set of rules that are required to transfer hypertext (text with hyperlink) between browser window to web server and web server to browser window.

• Version HTTP 1.0, 1.1(latest).

Request url:

http://localhost: 2020/DateApp/test

(send blank request)

http://Iocalhost :2020/DateApp/test?p1=val1 &p2=va12

(send the request with data)

Pl= val &p2 = val2 (Query String)

Here p1 and p2 are request parameter names-val1 and val2 are request parameter values.

                            UNDERSTANDING HTTP REQUEST

HTTP request: http request carries multiple details, which can be remembered as H2P2 details HTTP response: http response carries multiple details they can remembered as SCH details.

Details for http://localhost:2020IDateApp/testl?sno=101&sname=raja

H2P2:

H: http request methodology

Example: GET/POST/PUT /DELETE, etc.

H: http request headers

Example: User: -agent, accept, accept-language

P: path of requested web resource program (DateApp / testl)

P: request parameter (sno=101,sname=raja)

SCH details of http response

S: http response status code (100-599)

C: http response content(output of web resource program)

H: http response header

Example: (refresh, contextType, contextLength)





About Dinesh Thakur

Dinesh ThakurDinesh Thakur holds an B.SC (Computer Science), MCSE, MCDBA, CCNA, CCNP, A+, SCJP certifications. Dinesh authors the hugely popular blog. Where he writes how-to guides around Computer fundamental , computer software, Computer programming, and web apps. For any type of query or something that you think is missing, please feel free to Contact us.