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127 lines
4.3 KiB
TeX
127 lines
4.3 KiB
TeX
\section{Standard Module \sectcode{httplib}}
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\stmodindex{httplib}
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\index{HTTP}
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\renewcommand{\indexsubitem}{(in module httplib)}
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This module defines a class which implements the client side of the
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HTTP protocol. It is normally not used directly --- the module
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\code{urllib} uses it to handle URLs that use HTTP.
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\stmodindex{urllib}
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The module defines one class, \code{HTTP}. An \code{HTTP} instance
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represents one transaction with an HTTP server. It should be
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instantiated passing it a host and optional port number. If no port
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number is passed, the port is extracted from the host string if it has
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the form \code{host:port}, else the default HTTP port (80) is used.
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If no host is passed, no connection is made, and the \code{connect}
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method should be used to connect to a server. For example, the
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following calls all create instances that connect to the server at the
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same host and port:
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\begin{verbatim}
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>>> h1 = httplib.HTTP('www.cwi.nl')
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>>> h2 = httplib.HTTP('www.cwi.nl:80')
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>>> h3 = httplib.HTTP('www.cwi.nl', 80)
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\end{verbatim}
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Once an \code{HTTP} instance has been connected to an HTTP server, it
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should be used as follows:
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\begin{enumerate}
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\item[1.] Make exactly one call to the \code{putrequest()} method.
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\item[2.] Make zero or more calls to the \code{putheader()} method.
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\item[3.] Call the \code{endheaders()} method (this can be omitted if
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step 4 makes no calls).
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\item[4.] Optional calls to the \code{send()} method.
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\item[5.] Call the \code{getreply()} method.
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\item[6.] Call the \code{getfile()} method and read the data off the
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file object that it returns.
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\end{enumerate}
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\subsection{HTTP Objects}
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\code{HTTP} instances have the following methods:
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\renewcommand{\indexsubitem}{(HTTP method)}
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\begin{funcdesc}{set_debuglevel}{level}
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Set the debugging level (the amount of debugging output printed).
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The default debug level is \code{0}, meaning no debugging output is
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printed.
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\end{funcdesc}
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\begin{funcdesc}{connect}{host\optional{\, port}}
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Connect to the server given by \var{host} and \var{port}. See the
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intro for the default port. This should be called directly only if
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the instance was instantiated without passing a host.
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\end{funcdesc}
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\begin{funcdesc}{send}{data}
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Send data to the server. This should be used directly only after the
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\code{endheaders()} method has been called and before
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\code{getreply()} has been called.
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\end{funcdesc}
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\begin{funcdesc}{putrequest}{request\, selector}
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This should be the first call after the connection to the server has
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been made. It sends a line to the server consisting of the
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\var{request} string, the \var{selector} string, and the HTTP version
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(\code{HTTP/1.0}).
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\end{funcdesc}
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\begin{funcdesc}{putheader}{header\, argument\optional{\, ...}}
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Send an RFC-822 style header to the server. It sends a line to the
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server consisting of the header, a colon and a space, and the first
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argument. If more arguments are given, continuation lines are sent,
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each consisting of a tab and an argument.
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\end{funcdesc}
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\begin{funcdesc}{endheaders}{}
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Send a blank line to the server, signalling the end of the headers.
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\end{funcdesc}
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\begin{funcdesc}{getreply}{}
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Complete the request by shutting down the sending end of the socket,
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read the reply from the server, and return a triple (\var{replycode},
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\var{message}, \var{headers}). Here \var{replycode} is the integer
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reply code from the request (e.g.\ \code{200} if the request was
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handled properly); \var{message} is the message string corresponding
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to the reply code; and \var{header} is an instance of the class
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\code{rfc822.Message} containing the headers received from the server.
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See the description of the \code{rfc822} module.
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\stmodindex{rfc822}
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\end{funcdesc}
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\begin{funcdesc}{getfile}{}
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Return a file object from which the data returned by the server can be
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read, using the \code{read()}, \code{readline()} or \code{readlines()}
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methods.
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\end{funcdesc}
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\subsection{Example}
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\nodename{HTTP Example}
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Here is an example session:
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\begin{verbatim}
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>>> import httplib
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>>> h = httplib.HTTP('www.cwi.nl')
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>>> h.putrequest('GET', '/index.html')
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>>> h.putheader('Accept', 'text/html')
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>>> h.putheader('Accept', 'text/plain')
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>>> h.endheaders()
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>>> errcode, errmsg, headers = h.getreply()
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>>> print errcode # Should be 200
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>>> f = h.getfile()
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>>> data f.read() # Get the raw HTML
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>>> f.close()
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>>>
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\end{verbatim}
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