Architecture - Apply The Correct Data From The GUI To The Parameters For The Rule And Execute The Rule

I have a very simple Business Rules Engine that has only three methods. One gets all the rules for the current operation, one will retrieve a list of parameters for the rules, the last applies the rules. The rules are stored in the database as user defined functions using parameters. The client will call the BRE pass in the operation and a Lot Number and the BRE checks for any rules that apply to this operation for this Lot. The client gets a list of rules that apply (the names of the corresponding UDF's in the database) and at which step in the operation the rule applies. When the material gets to a step that has a rule, it calls BRE to get parameters for the UDF for that operation, fills in the parameters with data contained in the GUI and calls the BRE to apply the rule with this lot's specific data. Multiple lots can share the same rule that is why there are parameters for the UDF. This all works well. However, this is assuming we have a set number of rules for each lot at each operation. If the lot needs a new rule applied at this operation we have to add a new rule and corresponding UDF into the BRE database. This is not a problem, the client will now see two rules, however, it only knows how to apply the parameters for the first rule, and there is no code for applying the parameters for the second rule.

For example: Rule 1 states that only the same Lot number items can be put into a carton. So the UDF expects one parameter called LotID and one parameter called Carton ID. It runs the rule (UDF) with these parameters and checks to ensure the lots match. Now the Lot requires a second rule: Only 25 items can be packed in the carton. We create a new rule and corresponding UDF, but this rule has the CartonID and a quantity associated with it.

The GUI can handle Rule 1 because it knows how to apply the correct data from the GUI to the parameters for the Rule and execute the rule, so LotID from the GUI = LotID in the parameter name in the UDF and CartonID from the GUI = CartonID parameter name in the UDF. Now there is a new rule, the GUI sees this new rule, gets the parameters, but has no way to applying the quantity to the new parameter to execute the rule without having to change the GUI. We don't expect there to be many rule changes, however, when they do occur we don't want to have to recompile the GUI every time. Does anyone have any suggestions on how to create a class that could determine the how to apply set the correct parameters? We have thought about a table in a database that maps the parameter names in the UDF with parameter names in the GUI so when we add a new UDF we update the table with the corresponding data from the GUI. That could work but may get cumbersome and would require us to make sure that, that table is kept current. Another suggestion was to name the parameters in the UDF the same as the parameters in the GUI, but this too, would require us to maintain the names in two locations.