1. A server system to facilitate an exchange of messages in an electronic trading system with a plurality of remote client applications, the server system comprising: a plurality of application servers; a plurality of API servers; wherein each of the plurality of application servers and API servers includes a processor coupled to a memory; a plurality of server applications hosted on the plurality of application servers; and a plurality of Application Programming Interfaces (APIs) hosted on the plurality of API servers, the plurality of APIs configured to provide programmatic access of the plurality of server applications to the plurality of remote client applications, each of the API servers being configured to: receive request messages compiled by at least one of said plurality of remote client applications, each request message compiled by combining an abstract message portion with an API-specific message portion, wherein the abstract message portion is created by an abstract message payload and the API-specific message portion is created by an extended message payload and an identified XML schema definition specific to a targeted API of the plurality of APIs; parse and extract the abstract message payload and the extended message payload from said request messages; and perform activity requested in the abstract message payload and the extended message payload, said activity performed by calling at least one of said plurality of server applications; wherein each of the plurality of APIs is configured to communicate with a server application and each of the plurality of server applications is configured to communicate with said remote client applications through more than one of said plurality of APIs.