HTTP GET and HTTP POST requests

Suppose the external site wishes to call a method of a Web Service.
It needs to indicate to the Web Service the name of the method to call and the arguments to be passed to the method.
And the external site is expecting the Web Service to return a value to the external site.
This communication is done by sending an HTTP request to the webserver of the Web Service's site.

Most of the billions of queries sent every day through the WWW are HTTP GET requests.
For example, when you type the following URL into the location box of a browser:
```
0167: http://www.a.com/pictures/index.htm
```
the browser will contact port 80 of the computer known as www.a.com

and send the following lines to it:

0168: GET /pictures/index.htm HTTP/1.1
0169: Host: www.a.com
0170: Content-Type: text/html
0171:

www.a.com will return lines like the following to the browser:

0172: HTTP/1.1 200 OK
0173: Date: Mon, 29 Mar 2004 14:40:58 GMT
0174: Server: Apache/1.3.27 (Unix) PHP/4.3.2 mod_ssl/2.8.12 OpenSSL/0.9.6g
0175: Last-Modified: Mon, 29 Mar 2004 14:37:27 GMT
0176: Accept-Ranges: bytes
0177: Content-Type: text/html; charset=iso-8859-1
0178: Content-Length: 31
0179: 
0180: <html>
0181: <p>
0182: hello world!
0183: </p>
0184: </html>

Although most WWW pages are produced by means of an HTTP GET request, some WWW pages are the result of an HTTP POST request. HTTP POST requests often occur when you click on the submit button of a web form. For example, suppose a WWW page provides the following web form:

0185: <form method="POST" action="http://www.a.com/pictures/query.php">
0186:     <input type="text" name="last"/>
0187:     <input type="text" name="first"/>
0188:     <input type="text" name="age"/>
0189:     <input type="submit" value="submit/>
0190: </form>

Suppose the visitor to this WWW page types some values (say Bloggs, Fred and 27) into the three textboxes and then clicks the submit button. Because the form has a method attribute of "POST", an HTTP POST request will be generated:

0191: POST /pictures/query.php HTTP/1.1
0192: Host: www.a.com
0193: Content-Type: application/x-www-form-urlencoded
0194: Content-Length: XXXX
0195: 
0196: last=Bloggs&first=Fred&age=27