An instant message (IM) interface configured to extend a target application over an IM link of a communication network is provided according to the invention. The IM interface includes a communication interface configured to transfer a reply IM to an originating application. The IM interface further includes a processing system configured to obtain data from the target application and provide an output form to a messaging Application Programming Interface (messaging API). The output form is provided from a set of Forms Definition Language (FDL) forms. The messaging API is substantially protocol-dependent and the set of FDL forms is protocol-independent. The processing system is further configured to generate the reply IM in an originating application protocol using the data, the output form, and one or more protocol-specific libraries of the messaging API. The reply IM is an originating application protocol-specific IM.