Problem with http server on Esp8266 with response of about 25kByte

[scaprile]

I seem to remember some post somewhere from one of the developers… did you try using the RPC interface instead ?
Anyway, searching for ‘mg_send’ in this forum returns interesting results (and it’s free!):

Sending HTTP response in pieces

Yes, check the send_iobuf length before mg_send_, and if it is larger than some reasonable threshold, do not send but rather wait for another poll cycle. This is what default file handler does. See https://github.com/cesanta/mongoose/blob/master/src/mg_http.c Function mg_http_transfer_file_data()

Need a way to flush tcp send buffer

Also, https://github.com/mongoose-os-apps/http-fetch If you’re not using Mongoose OS but plain Mongoose Library, you can process the MG_EV_HTTP_CHUNK message which is fired for every chunk in the upload. Alternatively, for a non-chunked upload, use MS_EV_RECV. Using Mongoose OS is preferrable however, because there is already a FS.* set of functions for managing files, and you can upload large files to ESP8266 with no issues.