Problem

The following error can be observed during Server Transfer push operations over the PeSIT transfer protocol:

Error during transfer operation: com.axway.st.client.pesit.PesitNetworkException: Didn't receive expected SENDENDED_IND response on time (NN seconds)

Resolution

The PeSIT protocol uses regular acknowledgments for parts of the file being transferred. These acknowledgments are determined according to the "Checkpoint Interval" and the "Checkpoint Window" parameters. The "Checkpoint Interval" determines the number of bytes between two checkpoints. The "Checkpoint Window" determines how many checkpoints can go unacknowledged before the sender (ST in this case) stops transmitting.

During the transfer, if ST does not receive any message, including checkpoint acknowledgment for more than the time specified in the "Connection timeout" setting in the Transfer Site, ST will log the above error message and will terminate the transfer.

The "Checkpoint Interval" and the "Checkpoint Window" parameters have to be configured in a way to require the remote site to send checkpoint acknowledgments that are frequent enough to prevent from reaching the "Connection timeout". Commonly, these two parameters - the "Checkpoint Interval" and the "Checkpoint Window" - are set to 0, which has the meaning of infinitely high checkpoint interval, hence no requiring checkpoint acknowledgments. This configuration will cause the above error when transferring larger files, whose transfer time takes longer than the "Connection timeout" defined in the Transfer Site in seconds.