Hi Masad,
In DP we do support "streaming" where steaming means that DP will send the first packet to the back end before receiving the last packet of the request. Same for responses, DP will send the first packet before receiving the last.
There is a strict requirement that your DP policy NOT touch the body. If you touch the body then DP will transparently/invisibly flip to buffering mode. In buffer mode DP waits to transmit the first packet until receiving 100% of the content.
https://www.ibm.com/docs/en/datapower-gateway/10.5.x?topic=supplemental-streaming
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Ivan Heninger
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