How to provide a Database lookup table to third party system

Question

Hi All, 
 I have a requirement to process requests from system A to system B, here Appian acts as a mediator between system A & system B, like validating and grouping the data, etc. 
 There will be a huge data flow between system A and Appian(~40,000 records per request). To reduce the number of records, system A has to filter the data and send it to Appian, but the problem is the filtering criteria is based on customer and the customer details are present in the form of database table in Appian. 
 Now, we have to make the database table as a lookup and system A will look into the table and filter the data. 
 Can anyone suggest how to make the database table as a lookup. 
 Thanks in advance. 
 Regards, Someshwar

aloks0189 · Answer

Hi someshwarp  I believe, you system A is going to communicate Appian using Web API, in such case,  sending that huge amount of data to this service is never a good idea. 
 However if that is your requirement you can send those data to Appian Web API in form of JSON through body, now Appian Web API will trigger a process and will pass entire body to the process through parameter, just to avoid huge data processing in Web API. 
 You need to place parsing logic along with lookup operation and return the final response as outbound to the system B, in such case system B must have an API exposed which will be invoked by Appian once your request got processed. 
 Hope this will give an overview to proceed further in order to achieve your requirement.