Re: [Cppcms-users] async connections and response headers

[Artyom <art...@ya...>]

Ok, after quick look on our code the problem is obvious:

You can't change response headers **after** writing data to output stream
as in *CGI protocol all headers must be written before the response body.

See: 
http://art-blog.no-ip.info/cppcms_ref_v0_99_1/classcppcms_1_1http_1_1response.html#39e48c676a3f2c79b26d60b8d455658c



So you must do all changed in headers before writing to output stream.

So instead of:

        release_context()->async_complete_response();

You need:

        
        response().set_content_header("text/plain");
        response().status(200);
        response().out() << "test";
        release_context()->async_complete_response();

Notes:

- Status is assumed be default in CGI protocols as 200, so you don't
  need to set it explicitly, one status like 404, 400 or 301
  require explicit CGI header Status:
- You may use response().set_plain_text_header() instead of writing:
  response().set_content_header("text/plain"); (which does the same).

So in short you may write this as:

        response().set_plain_text_header();
        response().out() << "test";
        release_context()->async_complete_response();

Note, set_content_header(std::string) still adds charset by default,
  
See: 
http://art-blog.no-ip.info/cppcms_ref_v0_99_1/classcppcms_1_1http_1_1response.html#50ae55ff605bc655f5b19021f0f4f71d


So if you want to set raw header use set_header(name,value) function.



> what remains is the header issue. my  test application still sends only
> the content without headers. i attached  capture from wireshark of the
> http conversation between server and browser  and the scgi conversation
> between nginx and the application. while in the  http conversation no
> response headers are shown the scgi dump shows that at  least
> content-type and x-powered had been sent. nginx obviously filtered  them
> out due to the missing standard headers. the test application has  been
> compiled against svn-1317.
> 
> i also attached the application again  since i did the changes you
> suggested. i also tried to set the status code  explicitly without success.
> 

Artyom