Re: Query on Fix T 1.1 for 5.0
Mahesh Kumaraguru <>
22 Mar 2008 11:04PM ET> Hi Mahesh,
>
> Can you please explain me a bit about the Transport Independence
> Framework 1.1 for Fix 5.0 I don't belong to a technical background but
> am very much interested in knowing what it is and how does it
> differentiates from the previous fix versions.
>
> Regards, Sunil Singh
Hi Sunil,
FIX is a connectivity protocol and involves two parties - a client (Buy side) and a Server (Sell side).
FIX has two layers
Session layer (also known as Transport layer)
Application layer (also known as Business layer)
Session layer is responsible for :-
1. Starting and ending Sessions.
2. Delivering Application messages between the parties maintaining order of messages.
3. Helping recover Application messages that get lost in transit.
Individual message integrity is performed using body length and checksum, presence of mandatory tags, conditionally required tags, optional tags and the permitted values in these based on message type and FIX version.
Application / Business layer consists of the messages which the Buy side and Sell side want to exchange with each other (Orders, Executions, IOI, etc...).
Please note that the Buy and Sell side are not at all interested in exchanging Session messages. To take a non-FIX but similar example - me and my pen pal "X" located in a different geographical location want to exchange letters, we are only interested in the letter(s), we are not interested in the postal cover with from and to addresses, postage stamp, postal receipt etc. But since I shall be using the postal system to send letter, I shall have to put it in a cover, paste the appropriate value of postage stamp and if I want a tracking number / confirmation of delivery, I need to take it to a post office and obtain a tracking number. This postal system in this example is "Transport". Now let me expand this "Postal example". Instead of only using the postal system, I decide to also try private "Courier services". Some changes would be required - like the postage stamp is not valued by courier, cannot drop it into a post box etc.
Back to FIX. Initially when FIX was designed, thought nothing in FIX dictates that TCP be used as transport protocol, but TCP was probably the most widely used reliable transport protocol avaiable. Now as many different reliable transports are available, FIX is in the process of accomodating changes to permit FIX messages to be distilled to a form such that any transport mechanism could be used efficiently. I had posted the structure of such a distillate at
http://fixprotocol.org/discuss/read/94232f30
FIXT.1.1 permits multiple different versions of FIX messages to coexist in a single session. Upto FIX.4.4 a Single session could only have messages of the same version flowing between counterparties. With FIXT.1.1, the only requirement is that all Session messages be FIXT.1.1.
You can join the active discussion of FIX.5.0 which is the Application version complimenting FIXT.1.1 at
http://fixprotocol.org/discuss/47
http://fixprotocol.org/discuss/55
Feel free to post any more questions you have to the appropriate forum.
Regards,
K. Mahesh
