Question

I am using the python code examples from “http://www.quickfixengine.org” and have a question. I create my application using the code segment shown below

import quickfix

if len(sys.argv) < 2: return
fileName = sys.argv[1]

try:
    settings = quickfix.SessionSettings(fileName)
    application = quickfix.MyApplication()
    storeFactory = quickfix.FileStoreFactory(settings)
    logFactory = quickfix.FileLogFactory(settings)
    initiator = quickfix.SocketInitiator(application, storeFactory, settings, logFactory)
    initiator.start()
    # while condition == true: do something
    initiator.stop()
except quickfix.ConfigError, e:
    print e

The connection is made and I get logged in, and now I want to send a message (an order, for example). The provided code segment for that is:

def sendOrderCancelRequest:
    message = quickfix.Message();
    header = message.getHeader();

    header.setField(...)
    *<...build the header and body...>*
    message.setField(...)

    Session.sendToTarget(message)

My question is about that Session object. Where/How is that created? Does it get created with something like Session = quickfix.Session(), or something else that they are not showing? I’ve tried a few things, but with the dearth of documentation its just trial and error…

Answer 1

Session is not an object, it’s a class. In this case, sendToTarget() is static method.

Session, maintains a class-static list of sessions. sendToTarget()‘s uses the header fields in your message (or those you explicitly supply) to determine which session to send on.

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EDIT: I misread your question. Here’s an answer to what you asked.

The session is created in the bowels of the QF engine. It’s created by a SessionFactory, which is itself created in the initialize() function of Initiator and Acceptor. This is stuff you only need to get into if you feel like hacking on the engine source.

As an app developer, you really don’t need a handle to the session. If you think you do, then I’m guessing you’re probably planning to do something that is not recommended (such as wanting to programmatically reset seq#s, which is a common newbie Bad Idea on the QF lists).

If you really want a handle to it, you can use Session.lookupSession() or one of the getSession() functions of Initiator or Acceptor. But again, I don’t see any reason to bother. I’m a seasoned QF user, and I had to go look this up, because it’s something I never ever do.