In ASTRA, the primary form of interaction between agents is through the use of an Agent Communication Language (ACL). ASTRA supports direct interaction through FIPA ACL-based message passing. This ACL supports a range of message type which must be must be one of the standard FIPA ACL Performatives:

accept-proposal agree cancel cfp confirm disconfirm
failure inform inform-if inform-ref not-understood propogate
propose proxy query-if query-ref refuse reject-proposal
request request-when request-whenever subscribe

To get started with understanding agent communication, this lesson will initially focus on request and inform messages.