Presence map and mandatory

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1

Imported from previous forum

2

Hi all,

Suppose one input message is coming to FAST decoder and decoder will generate one output message, I want to know if the presence map is refering to input message and mandatory/optional is refreing to output message.

Thank you

3

Michael, I don’t understand your question.
Please rephrase/elaborate.
/Rolf

Hi all,

Suppose one input message is coming to FAST decoder and decoder will
generate one output message, I want to know if the presence map is
refering to input message and mandatory/optional is refreing to
output message.

Thank you

4

I think I know what you are asking. Presence map and mandatory/optional attributes of fields are elements of the template and allow you to determine how the data was coded on the wire. They thus all refer to the input message.

The assumption is that all fields which are either explicitly in the input message or can be derived from the template and a previous input message (dictionary value) will also be in the output message.

I has nothing to do with the “Req’d” attribute of FIX defining whether a field in a FIX message is mandatory or optional.

Does this answer your question?

Regards,
Hanno.

Hi all,

Suppose one input message is coming to FAST decoder and decoder will
generate one output message, I want to know if the presence map is
refering to input message and mandatory/optional is refreing to
output message.

Thank you

5

Thank you Rolf and Hanno.

At the beginning, it is a bit contradiction. If a field is mandatory, then why it occupies a field in PAMP. After reading some threads here. I found that the mandatory does not related to PMAP. It just states whether this field is nullable or not.

Thank all you again.

Michael

I think I know what you are asking. Presence map and mandatory/optional
attributes of fields are elements of the template and allow you to
determine how the data was coded on the wire. They thus all refer to the
input message.

The assumption is that all fields which are either explicitly in the
input message or can be derived from the template and a previous input
message (dictionary value) will also be in the output message.

I has nothing to do with the “Req’d” attribute of FIX defining whether a
field in a FIX message is mandatory or optional.

Does this answer your question?

Regards, Hanno.

Hi all,

Suppose one input message is coming to FAST decoder and decoder will
generate one output message, I want to know if the presence map is
refering to input message and mandatory/optional is refreing to output
message.

Thank you

6

Michael,

I found that the mandatory does not related to PMAP.
It just states whether this field is nullable or not.

A clarification:

A pmap (presence map) entry generally indicates if a field is present in the stream. The pmap is only used to express optionality in one case; for an optional group.

/Rolf