Processing a request from a sending computer that is a co-member of a message group of a sysplex coupled together using a signaling service includes the steps of: determining, by a receiving computer, that a signaling service message has been received from the sending computer, wherein the signaling service message relates to a data transfer between the sending computer and the receiving computer and wherein the data transfer relates to an exchange of one or more files between the sending and receiving computers using a communications channel other than the signaling service. This processing also includes decoding, by the receiving computer, a control block data structure associated with the signaling service message to determine contents of the control block data structure; and performing, by the receiving computer, an action related to the data transfer based on the contents of the control block data structure associated with the signaling service message.