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re: Repeating groups
Scott Atwell / American Century <>
10 Aug 1998 2:12PM ETThere is a working group investigating the applicability of using XML for FIX message bodies which would provide a standard-based way to "block" the various repeating groups.
> > Since the first field of a repeating group is required if that group is used, I simply use the presence of that first field as a "row" delimiter. That works pretty well and is pretty clean. It works equally effective on sub-repeating groups.
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> I do the same to detect the presence of the next-group. However, to detect the end-of-last-group requires checking that the "last-tag" does NOT belong to the allowed group tags, i.e, when examining a tag when parsing the last group, the tag must be checked against each allowed tag to determine if it is part of the group. If not, then the group has ended. If there were a required last-group-tag, per repeating-group type, then this would simplify transition OUT of a group.
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> I can live with repeating groups within groups. I just hoped for a simpler solution.
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> There is nothing wrong with the current message scheme. However, I am more interested in regularizing groups so that it is (1) simple to create groups and add fields; and (2)cleanly separate implemention into formatting and business logic.
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> My 2nd proposal (300=type) suggests that by enumerating groups and homogenizing the delimination of repeating-group-fields, its easy to add custom groups (another enumerated value) and fields (just add more fields within a group-delimiter) without creating more parsing rules/tables for each group-type. What I am trying to do is separate the low-level field parsing/separation logic from the higher-level business verfication/parsing logic. As it is now, each group that is added requires its own "Number-of-groups" tag-group-identifier, and a list of allowed tags thus restricting the "growability" of FIX messages that is so appealing.
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> In effect, by enumerating groups, groups become mini-FIX messages within FIX-messages.
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re: Repeating groups
Scott Atwell / American Century 10 Aug 1998 2:12PM ET
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