Browser request/server response, GET & POST requests

Browser request/server response, GET & POST requests

21:19
Some of the most important concepts in JMETER are 

 - HTTP request
- request header
- response header
- response data

 Before using them in a project, a few details for each is needed.

 Browser Request - Server Response 

 Most of the user interactions with a website through a browser results into a HTTP request sent to the web server.

 Example:

     1. open the browser

     2. open a web page

     3. interact with the web page

     4. the page changes:

 - a part of the page changes

 - the page is reloaded

 - a new page is loaded
Every time the page changes, the browser sends a HTTP request to the server.

 The server generates the new page and sends the new page as a response to the browser.

 The browser renders the new page for the user.








A HTTP request has the following template:





HTTP request types: GET and POST
Two commonly used HTTP methods are:

 GET request   - Used for requesting data from the web server

 POST request - Submits data to be processed to a web server
The GET Method

Query strings (name/value pairs) are sent in the URL of a GET request:

       GET /test/demo_form.asp?name1=value1&name2=value2

 Characteristics of GET requests:

 1. GET requests can be cached

 2. GET requests remain in the browser history

 3. GET requests can be bookmarked

 4. GET requests should never be used when dealing with sensitive data

 5. GET requests have length restrictions

 6. GET requests should be used only to retrieve data




The POST Method

 Query strings (name/value pairs) are sent in the HTTP message body of a POST request:

        POST /test/demo_form.asp HTTP/1.1
        Host: demo.com
        name1=value1&name2=value2

Characteristics of POST requests:

 1. POST requests are never cached
 
2. POST requests do not remain in the browser history

 3. POST requests cannot be bookmarked

 4. POST requests have no restrictions on data length

BROWSER REQUEST


The following info is included in a browser request in the request header:

- request type: GET/POST

- protocol type and version (HTTP)

- URL: hostname + URI 

        http://wwwa.autotrader.ca/cars/bc/vancouver/?prv=BC&loc=vancouver&prx=100

request type = GET
protocol type = HTTP
port = 80
hostname = wwwa.autotrader.ca
URI = cars/bc/vancouver/?prv=BC&loc=vancouver&prx=100
        Query String = prv=BC&loc=vancouver&prx=100


- client:

accept: text/html, application /xhtml+xml, .....
accept encoding: gzip, deflate, .....
accept language: en-US, en
user agent: Mozilla/5.0, apple webkit, chrome, safari

         The user agent depends on the browser type and device type:
  1. Firefox: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:32.0) Gecko/20100101 Firefox/32.0
  2. Internet Explorer: Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.1; WOW64; Trident/4.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; .NET4.0C; .NET4.0E)
  3. Chrome: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko  Chrome/38.0.2125.104 Safari/537.36
  4. Nexus 7 tablet: Mozilla/5.0 (Linux; Android 4.3; Nexus 7 Build/JSS15Q) AppleWebKit/537.36 (KHTML, like Gecko)   Chrome/29.0.1547.72 Safari/537.36
  5. Iphone 6 smartphone: Mozilla/5.0 (iPhone; CPU iPhone OS 8_0 like Mac OS X) AppleWebKit/600.1.3 (KHTML, like Gecko) Version/8.0 Mobile/12A4345d Safari/600.1.4


- cookies info

- transport:

connection info: keep alive
host name
WEB SERVER RESPONSE

 The web server response has 2 parts:
Response Data

        Page content sent by the web server to the browser
Response Header

HTTP/1.1 200 OK

Server: nginx/1.1.19

Date: Wed, 22 Oct 2014 18:21:19 GMT

Content-Type: text/html;charset=utf-8

Cache-Control: max-age=0, private, must-revalidate

Set-Cookie: agency_id=BC-VANCOUVER; path=/

Set-Cookie: language=en-CA; path=/; expires=Tue, 22-Oct-2019 18:21:18 GMT

Set-Cookie: page_size=10; path=/; expires=Thu, 22-Oct-2015 18:21:18 GMT

Set-Cookie: SRV=app09; path=/; domain=.bibliocommons.com

Cache-control: private

Age: 1

Connection: close



 PRACTICE BY YOURSELF

The easiest way of getting familiar with the concepts from this post is through a web proxy 
like FIDDLER 2.

 You can download it from http://www.telerik.com/fiddler.

 After downloading it, install the app and start it.

 You will see in FIDDLER2 all web requests captured from all open browsers.

 You can get access to lots of information about web requests in FIDDLER 2 in just a few 
minutes:

- requests embedded in the web page that corresponds to a web request (URL)




- request header



- response header and response data

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Alex Siminiuc