Wny no seqnum and checksum in FIXML

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Imported from previous forum

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Hi,

I have checked DTD for 4.2, why there are no seqnum and checksum elements on FIXML?

Is it no longer useful?

Regards,
Wing

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[ original email was from Ryan Pierce - rpierce@taltrade.com ]
> I have checked DTD for 4.2, why there are no seqnum and checksum elements on FIXML?
>
> Is it no longer useful?

FIX defines a data representation (Tag=Value), an ordered, reliable delivery protocol, a dictionary of fields, a catalog of business messages, and rules governing their use and state transitions.

FIXML throws out the Tag=Value data representation in favor of XML, it throws out the reliable delivery protocol entirely, and it keeps the same dictionary, catalog, and rules.

Exchanging XML in an ordered, reliable way is a problem that’s been solved many times over. FIXML is therefore independent of transport protocol, so FIX session fields like CheckSum and MsgSeqNum are gone, as well as session-level messages like Resend Request. You can send FIXML via any number of products, including encapsulating it inside a normal FIX message, in which case you would have a CheckSum and MsgSeqNum inside the Tag=Value part of the message so that the FIX engines can sequence and verify integrity of the messages.