Question

I could see a couple of examples to read from the http stream. But how to write to a http input stream using python?

Answer 1

You could use standard library module httplib: in the HTTPConnection.request method, the body argument (since Python 2.6) can be an open file object (better be a “pretty real” file, since, as the docs say, “this file object should support fileno() and read() methods”; but it could be a named or unnamed pipe to which a separate process can be writing). The advantage is however dubious, since (again per the docs) “The header Content-Length is automatically set to the correct value” — which, since headers come before body, and the file’s content length can’t be known until the file is read, implies the whole file’s going to be read into memory anyway.

If you’re desperate to “stream” dynamically generated content into an HTTP POST (rather than preparing it all beforehand and then posting), you need a server supporting HTTP’s “chunked transfer encoding”: this SO question‘s accepted answer mentions that the popular asynchronous networking Python package twisted does, and gives some useful pointers.