Python backend

[jonasblixt]

I'm trying to use grpc-web with a python backend. I keep getting the following output from the grpc-web-client:

status 13 Response closed without headers

Perhaps someone can point me in the right direction

Debug output from the grpc-server:
localhost:4200..User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_13_0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/61.0.3163.100 Safari/537.36..Access-Control-Request-Headers: content-type,x-grpc-web..Accept: */*..Referer: http://localhost:4200/login..Accept-Encoding: gzip, deflate, br..Accept-Language: en-US,en;q=0.8,en-GB;q=0.6,sv;q=0.4....' D1013 11:20:41.749662000 123145419489280 chttp2_transport.c:2546] set connectivity_state=4 D1013 11:20:41.749700000 123145419489280 connectivity_state.c:171] SET: 0x7fa8f5072850 server_transport: READY --> SHUTDOWN [close_transport] error=0x7fa8f4e89030 {"created":"@1507886441.749660000","description":"Failed parsing HTTP/2","file":"src/core/ext/transport/chttp2/transport/chttp2_transport.c","file_line":2342,"grpc_status":14,"referenced_errors":[{"created":"@1507886441.749656000","description":"Connect string mismatch: expected 'P' (80) got 'O' (79) at byte 0","file":"src/core/ext/transport/chttp2/transport/parsing.c","file_line":104}]}

//Jonas

[MarcusLongmuir]

Hey @jonpe960

grpc-web-client requires that the gRPC server supports the compatibility wrapper that this repo contains. There is a golang wrapper that you can use if you're writing your gRPC server in golang, otherwise you can use the grpcwebproxy in front of a gRPC server written in another language.

The reason you're seeing this error is because the server is ending the body that contains the messages and then attempts to send the trailers (that include the status of the response) as a headers frame after the body. Currently browsers don't support receiving this additional headers frame so the client can't determine the status of the response. This the issue that the server wrappers work around.

Please reopen the issue if I've misunderstood your issue.