5.1 The request

A client, like a web browser, sends an HTTP request to the server. An HTTP request looks like this:

    POST /;login HTTP/1.1
    Host: localhost:8080
    User-Agent: Mozilla/5.0
    Accept: text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5
    Accept-Language: es,en;q=0.8,fr;q=0.5,pt;q=0.3
    Accept-Encoding: gzip,deflate
    Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7
    Keep-Alive: 300
    Connection: keep-alive
    Referer: http://localhost:8080/;login_form
    Content-Type: application/x-www-form-urlencoded
    Content-Length: 34

    username=toto%40xxx.com&password=a

As you see it is basically a file, which is sent through the wire, from the client to the server. It has a simple readable format, which consists of three parts:

• The request line. It is the first line, and contains: the request method, the requested uri and the protocol version.

• The headers. Each line after the request line, and before the first blank line, is a header; where a header has a name and a value. Headers are used to information about the client (User-Agent, Agent), about the connection (Keep-Alive, Connection), etc.

• The body. At the end, separated from the header by a blank line, comes the body. It contains extra information, for example the values of a form, or a file that is uploaded. Most requests do not include a body.

To work with HTTP requests (and responses) itools.http offers a file handler:

    >>> from itools.http import Request
    >>>
    >>> request = Request('request.txt')
    >>> request
    <itools.http.request.Request object at 0x2b59beffc6d8>
    >>>
    >>> print request.method
    POST
    >>> print request.request_uri
    /;login
    >>> print request.http_version
    HTTP/1.1
    >>> print request.get_header('user-agent')
    Mozilla/5.0

Here there is a summary of the programming interface of request objects (the details can be found in the reference chapter):

• set_header(name, value)

• has_header(name)

• get_header(name)

• get_referrer()

• get_parameter(name, default=None, type=None))

• has_parameter(name)

• set_cookie(name, value)

• get_cookie(name)