[Erlyaws-list] Large posts, partial post size, etc.

[Carsten S. <ca...@gn...>]

Hi!

I have been looking at the code related to partial_post_size, because
I wanted to make my CGI code make work with (which it doesn't at the
moment).  This would indeed be useful, as there is no reason to buffer
the entire post data, which will be interpreted by the CGI script.  I
would like to have some issues resolved first, however.

It seems that the current code assumes that partial posts will only
happen for file uploads, ie multipart/form-data.  The content type of
a post and it being large should be considered independent properties.

Also the interaction of the server code and the code implementing the
dynamic file by repeatedly calling the dynamic code with different
arguments seems quite un-Erlang-ish to me, if this is of any
importance.  Two other approaches come to my mind:

 * Have the dynamic code spawn a process that communicates with the
   server process similarly to the stream content handling.

 * Have the dynamic code return {get_more, Cont} where Cont is a real
   continuation, that is then called by the server code with the next
   chunk of data as the argument.

Independently of this, an api function to wrap partial post unaware
dynamic code would be beneficial, such that

<erl>
out(A) ->
       % code that does not know about partial posts, possibly calling
       % parse_post or using the raw A#arg.clidata
</erl>

could be easily replaced by

<erl>

out(A) ->
       yaws_api:call_with_entire_post_data(A, fun out_old/1).

out_old(A) ->
       % code that does not know about partial posts, possibly calling
       % parse_post or using the raw A#arg.clidata
</erl>

One could also think of always calling out/1 with the entire post
data, but calling out_partial if it exists.  I fear that setting
partial_post_size to a value different from nolimit might break a lot
of existing code, especially if the value is small.  Just think of
large text fields.

Greetings,

Carsten

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Carsten Schultz (2:40, 33:47), FB Mathematik, FU Berlin
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