from Common import *
from Servlet import Servlet
class HTTPServlet(Servlet):
"""A HTTP servlet.
HTTPServlet implements the respond() method to invoke methods such as
respondToGet() and respondToPut() depending on the type of HTTP request.
Example HTTP request methods are GET, POST, HEAD, etc.
Subclasses implement HTTP method FOO in the Python method respondToFoo.
Unsupported methods return a "501 Not Implemented" status.
Note that HTTPServlet inherits awake() and respond() methods from
Servlet and that subclasses may make use of these.
See also: Servlet
FUTURE
* Document methods (take hints from Java HTTPServlet documentation)
"""
## Init ##
def __init__(self):
Servlet.__init__(self)
self._methodForRequestType = {} # a cache; see respond()
## Transactions ##
def respond(self, trans):
"""Respond to a request.
Invokes the appropriate respondToSomething() method depending on the
type of request (e.g., GET, POST, PUT, ...).
"""
request = trans.request()
httpMethodName = request.method()
# For GET and HEAD, handle the HTTP If-Modified-Since header:
# if the object's last modified time is the same
# as the IMS header, we're done.
if httpMethodName in ('GET', 'HEAD'):
lm = self.lastModified(trans)
if lm:
lm = time.strftime('%a, %d %b %Y %H:%M:%S GMT',
time.gmtime(lm))
trans.response().setHeader('Last-Modified', lm)
ifModifiedSince = request.environ().get(
'HTTP_IF_MODIFIED_SINCE', None)
if not ifModifiedSince:
ifModifiedSince = request.environ().get(
'If-Modified-Since', None)
if ifModifiedSince and ifModifiedSince.split(';')[0] == lm:
trans.response().setStatus(304, 'Not Modified')
# print "304", request.serverSidePath()
return
method = self._methodForRequestType.get(httpMethodName, None)
if not method:
methName = 'respondTo' + httpMethodName.capitalize()
method = getattr(self, methName, self.notImplemented)
self._methodForRequestType[httpMethodName] = method
method(trans)
def notImplemented(self, trans):
trans.response().setStatus(501, 'Not Implemented')
def lastModified(self, trans):
"""Get time of last modification.
Return this object's Last-Modified time (as a float),
or None (meaning don't know or not applicable).
"""
return None
def respondToHead(self, trans):
"""Respond to a HEAD request.
A correct but inefficient implementation.
"""
res = trans.response()
w = res.write
res.write = lambda *args: None
self.respondToGet(trans)
res.write = w
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