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<H2><A NAME="SECTION00132420000000000000000"><!--x--></A><A NAME="asynchat-example"><!--z--></A>
<BR>
11.24.2 asynchat Example
</H2>
<P>
The following partial example shows how HTTP requests can be read with
<tt class="class">async_chat</tt>. A web server might create an <tt class="class">http_request_handler</tt> object for
each incoming client connection. Notice that initially the
channel terminator is set to match the blank line at the end of the HTTP
headers, and a flag indicates that the headers are being read.
<P>
Once the headers have been read, if the request is of type POST
(indicating that further data are present in the input stream) then the
<code>Content-Length:</code> header is used to set a numeric terminator to
read the right amount of data from the channel.
<P>
The <tt class="method">handle_request()</tt> method is called once all relevant input
has been marshalled, after setting the channel terminator to <code>None</code>
to ensure that any extraneous data sent by the web client are ignored.
<P>
<div class="verbatim"><pre>
class http_request_handler(asynchat.async_chat):
def __init__(self, conn, addr, sessions, log):
asynchat.async_chat.__init__(self, conn=conn)
self.addr = addr
self.sessions = sessions
self.ibuffer = []
self.obuffer = ""
self.set_terminator("\r\n\r\n")
self.reading_headers = True
self.handling = False
self.cgi_data = None
self.log = log
def collect_incoming_data(self, data):
"""Buffer the data"""
self.ibuffer.append(data)
def found_terminator(self):
if self.reading_headers:
self.reading_headers = False
self.parse_headers("".join(self.ibuffer))
self.ibuffer = []
if self.op.upper() == "POST":
clen = self.headers.getheader("content-length")
self.set_terminator(int(clen))
else:
self.handling = True
self.set_terminator(None)
self.handle_request()
elif not self.handling:
self.set_terminator(None) # browsers sometimes over-send
self.cgi_data = parse(self.headers, "".join(self.ibuffer))
self.handling = True
self.ibuffer = []
self.handle_request()
</pre></div>
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<span class="release-info">Release 2.3.4, documentation updated on May 20, 2004.</span>
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