149 lines
5.0 KiB
TeX
149 lines
5.0 KiB
TeX
\section{\module{httplib} ---
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HTTP protocol client}
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\declaremodule{standard}{httplib}
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\modulesynopsis{HTTP protocol client (requires sockets).}
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\indexii{HTTP}{protocol}
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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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\refmodule{urllib}\refstmodindex{urllib} uses it to handle URLs that
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use HTTP.
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The module defines one class, \class{HTTP}:
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\begin{classdesc}{HTTP}{\optional{host\optional{, port}}}
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An \class{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{\var{host}:\var{port}}, else the default HTTP port (80)
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is used. If no host is passed, no connection is made, and the
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\method{connect()} method should be used to connect to a server. For
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example, the following calls all create instances that connect to the
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server at the 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 \class{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 \method{putrequest()} method.
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\item[2.] Make zero or more calls to the \method{putheader()} method.
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\item[3.] Call the \method{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 \method{send()} method.
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\item[5.] Call the \method{getreply()} method.
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\item[6.] Call the \method{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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\end{classdesc}
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\subsection{HTTP Objects}
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\class{HTTP} instances have the following methods:
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\begin{methoddesc}{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{methoddesc}
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\begin{methoddesc}{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{methoddesc}
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\begin{methoddesc}{send}{data}
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Send data to the server. This should be used directly only after the
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\method{endheaders()} method has been called and before
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\method{getreply()} has been called.
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\end{methoddesc}
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\begin{methoddesc}{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{methoddesc}
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\begin{methoddesc}{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{methoddesc}
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\begin{methoddesc}{endheaders}{}
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Send a blank line to the server, signalling the end of the headers.
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\end{methoddesc}
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\begin{methoddesc}{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
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\code{(\var{replycode}, \var{message}, \var{headers})}. Here,
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\var{replycode} is the integer reply code from the request (e.g.,
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\code{200} if the request was handled properly); \var{message} is the
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message string corresponding to the reply code; and \var{headers} is
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an instance of the class \class{mimetools.Message} containing the
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headers received from the server. See the description of the
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\refmodule{mimetools}\refstmodindex{mimetools} module.
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\end{methoddesc}
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\begin{methoddesc}{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 \method{read()}, \method{readline()} or
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\method{readlines()} methods.
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\end{methoddesc}
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\subsection{Examples}
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\nodename{HTTP Examples}
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Here is an example session that uses the \samp{GET} method:
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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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\end{verbatim}
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Here is an example session that shows how to \samp{POST} requests:
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\begin{verbatim}
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>>> import httplib, urllib
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>>> params = urllib.urlencode({'spam': 1, 'eggs': 2, 'bacon': 0})
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>>> h = httplib.HTTP("www.musi-cal.com:80")
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>>> h.putrequest("POST", "/cgi-bin/query")
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>>> h.putheader("Content-length", "%d" % len(params))
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>>> h.putheader('Accept', 'text/plain')
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>>> h.putheader('Host', 'www.musi-cal.com')
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>>> h.endheaders()
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>>> h.send(paramstring)
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>>> reply, msg, hdrs = h.getreply()
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>>> print errcode # should be 200
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>>> data = h.getfile().read() # get the raw HTML
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\end{verbatim}
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