The HTTP server stream expiration time, in seconds, or nil for unlimited. The stream expiration timer is reset at the start of each request and cleared when complete, and can be used to place a bounds on the total time a request takes to read and write data to the client. See ext:stream-expiration and also http:server-stream-timeout. The stream expiration time may be modified per request after reading the headers by the function http:server-service-headers-function, see http:request-stream-expiration.