Responding to CMIP requests

This section provides an overview of the types of responses, both positive and negative, that the VTAM topology agent provides, given an input CMIP request. Subsequent sections describe the details of monitoring VTAM® resources by using the CMIP requests.

A CMIP request message is really a form of a protocol data unit (PDU), as are the various kinds of response messages. The following list provides a summary of the types of PDUs used by the VTAM topology agent:

ROIVapdu: The ROIV message represents a request message and is usually an unsolicited message. In one case, an ROIV represents one of a set of linked-reply messages, but even in this case the ROIV is treated as a request message. The ROIV request messages are either confirmed (requiring a response) or unconfirmed (allowing no response), depending on the particular operation being requested. The linked-reply ROIV message might contain the requested response data, or it might contain an indication that an error has occurred. All requests that are sent to the VTAM topology agent are ROIV messages.
RORSapdu: The RORS message represents a final response message. It is sent only in response to a previous ROIV request message and only if the ROIV request requires a response message. An ROIV request message can have a maximum of one RORS message sent in response. Therefore, if a request requires multiple reply messages, all but the final reply messages must be in the form of ROIV linked-reply messages. The VTAM topology agent sends RORS messages in response to all confirmed requests that it receives, when the subsequent processing is successful. An RORS message is also sent if an error occurred and the error indication was sent as part of a linked-reply ROIV message.
ROERapdu: The ROER message represents a negative response message. It is used to indicate the unsuccessful processing for a request message. For the ROER message to be used for a response, it must be the only message in the response. Therefore, if one or more linked-reply ROIV messages are sent in a response and then an error occurs, the ROER message cannot be used to indicate the processing error. Instead, the error is indicated in an additional linked-reply ROIV, followed by an RORS.