Hi Jimmie,

I implemented part of the FIX protocol as part of one of my projects a
while ago.  I made very few classes.  The fields mostly map to simple
Smalltalk classes like strings, ints, decimals, data and times.  Some
fields are compound fields in that they contain other fields and are
repeated in groups.

I did not make a class for each FIX message.  I used dictionaries to map
what fields were expected in each FIX message.  I mapped the FIX number
based field names to symbols that I made up that made sense to me and
matched the FIX name for the field.  This made for fairly simple code to
parse/print FIX messages to and from my FIX message class.  The data is
stored in dictionaries with my symbols as keys and the Smalltalk value of
the FIX field as the value in the dictionary.

This may not seem like good Smalltalk practice but I found that I wasn't
really interested in doing anything with the FIX classes other than reading
in FIX messages (data) and sending out FIX messages.  For working with the
data, I had other classes the matched what the system was doing.  This
often involved getting/sending much of the same data to/from another system
that had its own message format.

In that case I have basically the same data in a whole bunch of classes
that match say a non FIX message format and an equal number of classes that
match the FIX format.  Which one should you use to work with the data
within the system?  So, on both sides I have simple classes that basically
just move the field data to and from dictionaries by parsing or printing
the values in the correct format.

This made for some less than pretty code like:

	asc := msg at: #AccountSourceCode.

instead of:

	asc := msg accountSourceCode.

but it allowed for moving large numbers of fields from one message format
to another with a loop that ran a dictionary that had matching symbolic
field names for each message format.

	orderedCollectionOfFieldsToCopy do: [:f | | fixSymbol |
		fixSymbol := dictionaryOfCorrespondingFields at: f.
		fixMessage at: f put: (nonFixData at: fixSymbol).
	].

Again, I don't know if this is in the best tradition of Smalltalk but in my
multi message format environment, it seemed best.

Lou
-----------------------------------------------------------
Louis LaBrunda
Keystone Software Corp.
SkypeMe callto://PhotonDemon
mailto:Lou at Keystone-Software.com http://www.Keystone-Software.com