httplib¶

HTTP/1.1 client library

<intro stuff goes here> <other stuff, too>

HTTPConnection goes through a number of “states”, which define when a client may legally make another request or fetch the response for a particular request. This diagram details these state transitions:

(null)

HTTPConnection()

v

Idle

putrequest()

v

Request-started

( putheader() )* endheaders()

v

Request-sent

response = getresponse()

v

Unread-response [Response-headers-read]

|____________________ | | | response.read() | putrequest() v v

Idle Req-started-unread-response

______/|

/ |

response.read() | | ( putheader() )* endheaders()

v v

Request-started Req-sent-unread-response

response.read()

v

Request-sent

This diagram presents the following rules:

– a second request may not be started until {response-headers-read} – a response [object] cannot be retrieved until {request-sent} – there is no differentiation between an unread response body and a

partially read response body

Note: this enforcement is applied by the HTTPConnection class. The

HTTPResponse class does not enforce this state machine, which implies sophisticated clients may accelerate the request/response pipeline. Caution should be taken, though: accelerating the states beyond the above pattern may imply knowledge of the server’s connection-close behavior for certain requests. For example, it is impossible to tell whether the server will close the connection UNTIL the response headers have been read; this means that further requests cannot be placed into the pipeline until it is known that the server will NOT be closing the connection.

Logical State __state __response ————- ——- ———- Idle _CS_IDLE None Request-started _CS_REQ_STARTED None Request-sent _CS_REQ_SENT None Unread-response _CS_IDLE <response_class> Req-started-unread-response _CS_REQ_STARTED <response_class> Req-sent-unread-response _CS_REQ_SENT <response_class>