yaws

Saurabh80 wrote:
> can i invoke a default module on a request to the the yaws server and parse
> all the data myself
> 
> i.e. when - http://my-server:8080 is called
> 
> default module : foo:init() or foo:init(Args) gets called. I want to do the
> parsing of the header information myself. 
> 
> I do not want to use appmods.

If you really want to do _all_ the parsing yourself,
it doesn't really sound as if you need an HTTP server,
you want to write one ?

So no, there are no user hooks at that level in Yaws.

/klacke

On 2/26/09, Claes Wikstrom <klacke@...> wrote:
> Saurabh80 wrote:
>  > can i invoke a default module on a request to the the yaws server and parse
>  > all the data myself
>  >
>  > i.e. when - http://my-server:8080 is called
>  >
>  > default module : foo:init() or foo:init(Args) gets called. I want to do the
>  > parsing of the header information myself.
>  >
>  > I do not want to use appmods.
>
>
> If you really want to do _all_ the parsing yourself,
>  it doesn't really sound as if you need an HTTP server,
>  you want to write one ?
>
>  So no, there are no user hooks at that level in Yaws.

I agree with klacke, and I'm also wondering why you don't want to use
an appmod, given that all the headers are passed to you. Can you
explain further what you're trying to do and why an appmod won't work?

--steve

Which module and function in yaws does this. basically i want to stream the
request parameters to some other port. so that i can keep yaws as a
webserver and at the backend do the session management and stuff myself. 
I am trying to explore possibilities to use yaws in the j2ee world.



Claes Wikström wrote:
> 
> Saurabh80 wrote:
>> can i invoke a default module on a request to the the yaws server and
>> parse
>> all the data myself
>> 
>> i.e. when - http://my-server:8080 is called
>> 
>> default module : foo:init() or foo:init(Args) gets called. I want to do
>> the
>> parsing of the header information myself. 
>> 
>> I do not want to use appmods.
> 
> If you really want to do _all_ the parsing yourself,
> it doesn't really sound as if you need an HTTP server,
> you want to write one ?
> 
> So no, there are no user hooks at that level in Yaws.
> 
> /klacke
> 
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On 2/26/09, Saurabh80 <saurabh80@...> wrote:
>
>  Which module and function in yaws does this. basically i want to stream the
>  request parameters to some other port. so that i can keep yaws as a
>  webserver and at the backend do the session management and stuff myself.
>  I am trying to explore possibilities to use yaws in the j2ee world.

J2EE, huh? Better you than me. ;-)

The Arg type that's passed from Yaws to all out/1 functions contains
all the headers -- basically it contains everything that's associated
with the request. If you want to pass all request info along, the Arg
already has it all, so your best bet is to extract what you need from
there and pass it along.

For example, if you want all the headers but don't want to go through
all the trouble of digging through records field-by-field to get them,
here's one way to do that within an out/1 function (beware, only
partially tested):

-define(HEADER_FIELDS, record_info(fields, headers)).

hdr_to_string(Hdr) when is_atom(Hdr) ->
    lists:map(fun($_) -> $-; (C) -> C end, atom_to_list(Hdr));
hdr_to_string(Hdr) when is_list(Hdr) ->
    Hdr.

out(A) ->
    [_|Header_vals] = tuple_to_list(A#arg.headers),
    Headers1 = lists:map(fun({Hdr, Val}) ->
                                 {hdr_to_string(Hdr), Val}
                         end, lists:zip(?HEADER_FIELDS, Header_vals)),
    Other = lists:map(fun({http_header, _, K, _, V}) ->
                              {hdr_to_string(K), V}
                      end, proplists:get_value("other", Headers1)),
    Headers = lists:append([proplists:delete("other", Headers1), Other]),

At this point, Headers will be a proplist of header name string keys
and their string values. The special record_info call (which is
compile-time only, hence the macro) lets us walk the whole headers
record without having to change our code if that record ever changes.
Comments on improvements to this approach are most welcomed.

--steve

Thanks Steve for your reply. I tried using the code snippet you gave me but
i am getting this error

yaws code at appmod:0 crashed or ret bad val:{"connection","keep-alive"}
Req: {http_request,'GET',{abs_path,"/context"},{1,1}}

Need Help on this too :-)

On Fri, Feb 27, 2009 at 4:20 AM, Steve Vinoski <vinoski@...> wrote:

> On 2/26/09, Saurabh80 <saurabh80@...> wrote:
> >
> >  Which module and function in yaws does this. basically i want to stream
> the
> >  request parameters to some other port. so that i can keep yaws as a
> >  webserver and at the backend do the session management and stuff myself.
> >  I am trying to explore possibilities to use yaws in the j2ee world.
>
> J2EE, huh? Better you than me. ;-)
>
> The Arg type that's passed from Yaws to all out/1 functions contains
> all the headers -- basically it contains everything that's associated
> with the request. If you want to pass all request info along, the Arg
> already has it all, so your best bet is to extract what you need from
> there and pass it along.
>
> For example, if you want all the headers but don't want to go through
> all the trouble of digging through records field-by-field to get them,
> here's one way to do that within an out/1 function (beware, only
> partially tested):
>
> -define(HEADER_FIELDS, record_info(fields, headers)).
>
> hdr_to_string(Hdr) when is_atom(Hdr) ->
>    lists:map(fun($_) -> $-; (C) -> C end, atom_to_list(Hdr));
> hdr_to_string(Hdr) when is_list(Hdr) ->
>    Hdr.
>
> out(A) ->
>    [_|Header_vals] = tuple_to_list(A#arg.headers),
>    Headers1 = lists:map(fun({Hdr, Val}) ->
>                                 {hdr_to_string(Hdr), Val}
>                         end, lists:zip(?HEADER_FIELDS, Header_vals)),
>    Other = lists:map(fun({http_header, _, K, _, V}) ->
>                              {hdr_to_string(K), V}
>                      end, proplists:get_value("other", Headers1)),
>    Headers = lists:append([proplists:delete("other", Headers1), Other]),
>
> At this point, Headers will be a proplist of header name string keys
> and their string values. The special record_info call (which is
> compile-time only, hence the macro) lets us walk the whole headers
> record without having to change our code if that record ever changes.
> Comments on improvements to this approach are most welcomed.
>
> --steve
>

I should have been clearer that the code snippet wasn't complete. It
leaves off where you get a proplist of headers and their values, but
it doesn't fully complete the out/1 function. If you take the function
exactly as I originally showed it but add this line to the bottom it
should be fine:

{status, 200}.

Your task will then be to put your "communicate with J2EE" code in
between the bottom two lines:

Headers = lists:append([proplists:delete("other", Headers1), Other]),
%% insert code to talk to J2EE here
{status, 200}.

For your real code, presumably your J2EE system will return various
status and data to you for return to your web client, so eventually
you'll need to replace that {status,200} with something to convey the
real results.

--steve


On 2/27/09, Saurabh Dutta <saurabh80@...> wrote:
> Thanks Steve for your reply. I tried using the code snippet you gave me but
> i am getting this error
>
> yaws code at appmod:0 crashed or ret bad
> val:{"connection","keep-alive"}
> Req: {http_request,'GET',{abs_path,"/context"},{1,1}}
>
> Need Help on this too :-)
>
>
> On Fri, Feb 27, 2009 at 4:20 AM, Steve Vinoski <vinoski@...> wrote:
> >
> > On 2/26/09, Saurabh80 <saurabh80@...> wrote:
> > >
> > >  Which module and function in yaws does this. basically i want to stream
> the
> > >  request parameters to some other port. so that i can keep yaws as a
> > >  webserver and at the backend do the session management and stuff
> myself.
> > >  I am trying to explore possibilities to use yaws in the j2ee world.
> >
> > J2EE, huh? Better you than me. ;-)
> >
> > The Arg type that's passed from Yaws to all out/1 functions contains
> > all the headers -- basically it contains everything that's associated
> > with the request. If you want to pass all request info along, the Arg
> > already has it all, so your best bet is to extract what you need from
> > there and pass it along.
> >
> > For example, if you want all the headers but don't want to go through
> > all the trouble of digging through records field-by-field to get them,
> > here's one way to do that within an out/1 function (beware, only
> > partially tested):
> >
> > -define(HEADER_FIELDS, record_info(fields, headers)).
> >
> > hdr_to_string(Hdr) when is_atom(Hdr) ->
> >    lists:map(fun($_) -> $-; (C) -> C end, atom_to_list(Hdr));
> > hdr_to_string(Hdr) when is_list(Hdr) ->
> >    Hdr.
> >
> > out(A) ->
> >    [_|Header_vals] = tuple_to_list(A#arg.headers),
> >    Headers1 = lists:map(fun({Hdr, Val}) ->
> >                                 {hdr_to_string(Hdr), Val}
> >                         end, lists:zip(?HEADER_FIELDS, Header_vals)),
> >    Other = lists:map(fun({http_header, _, K, _, V}) ->
> >                              {hdr_to_string(K), V}
> >                      end, proplists:get_value("other", Headers1)),
> >    Headers = lists:append([proplists:delete("other",
> Headers1), Other]),
> >
> > At this point, Headers will be a proplist of header name string keys
> > and their string values. The special record_info call (which is
> > compile-time only, hence the macro) lets us walk the whole headers
> > record without having to change our code if that record ever changes.
> > Comments on improvements to this approach are most welcomed.
> >
> > --steve
> >
>
>

Thanks Steve. Appreciate the help extended. Let me now dig my head into this
:-)

On Fri, Feb 27, 2009 at 1:32 PM, Steve Vinoski <vinoski@...> wrote:

> I should have been clearer that the code snippet wasn't complete. It
> leaves off where you get a proplist of headers and their values, but
> it doesn't fully complete the out/1 function. If you take the function
> exactly as I originally showed it but add this line to the bottom it
> should be fine:
>
> {status, 200}.
>
> Your task will then be to put your "communicate with J2EE" code in
> between the bottom two lines:
>
> Headers = lists:append([proplists:delete("other", Headers1), Other]),
> %% insert code to talk to J2EE here
> {status, 200}.
>
> For your real code, presumably your J2EE system will return various
> status and data to you for return to your web client, so eventually
> you'll need to replace that {status,200} with something to convey the
> real results.
>
> --steve
>
>
> On 2/27/09, Saurabh Dutta <saurabh80@...> wrote:
> > Thanks Steve for your reply. I tried using the code snippet you gave me
> but
> > i am getting this error
> >
> > yaws code at appmod:0 crashed or ret bad
> > val:{"connection","keep-alive"}
> > Req: {http_request,'GET',{abs_path,"/context"},{1,1}}
> >
> > Need Help on this too :-)
> >
> >
> > On Fri, Feb 27, 2009 at 4:20 AM, Steve Vinoski <vinoski@...> wrote:
> > >
> > > On 2/26/09, Saurabh80 <saurabh80@...> wrote:
> > > >
> > > >  Which module and function in yaws does this. basically i want to
> stream
> > the
> > > >  request parameters to some other port. so that i can keep yaws as a
> > > >  webserver and at the backend do the session management and stuff
> > myself.
> > > >  I am trying to explore possibilities to use yaws in the j2ee world.
> > >
> > > J2EE, huh? Better you than me. ;-)
> > >
> > > The Arg type that's passed from Yaws to all out/1 functions contains
> > > all the headers -- basically it contains everything that's associated
> > > with the request. If you want to pass all request info along, the Arg
> > > already has it all, so your best bet is to extract what you need from
> > > there and pass it along.
> > >
> > > For example, if you want all the headers but don't want to go through
> > > all the trouble of digging through records field-by-field to get them,
> > > here's one way to do that within an out/1 function (beware, only
> > > partially tested):
> > >
> > > -define(HEADER_FIELDS, record_info(fields, headers)).
> > >
> > > hdr_to_string(Hdr) when is_atom(Hdr) ->
> > >    lists:map(fun($_) -> $-; (C) -> C end, atom_to_list(Hdr));
> > > hdr_to_string(Hdr) when is_list(Hdr) ->
> > >    Hdr.
> > >
> > > out(A) ->
> > >    [_|Header_vals] = tuple_to_list(A#arg.headers),
> > >    Headers1 = lists:map(fun({Hdr, Val}) ->
> > >                                 {hdr_to_string(Hdr), Val}
> > >                         end, lists:zip(?HEADER_FIELDS, Header_vals)),
> > >    Other = lists:map(fun({http_header, _, K, _, V}) ->
> > >                              {hdr_to_string(K), V}
> > >                      end, proplists:get_value("other", Headers1)),
> > >    Headers = lists:append([proplists:delete("other",
> > Headers1), Other]),
> > >
> > > At this point, Headers will be a proplist of header name string keys
> > > and their string values. The special record_info call (which is
> > > compile-time only, hence the macro) lets us walk the whole headers
> > > record without having to change our code if that record ever changes.
> > > Comments on improvements to this approach are most welcomed.
> > >
> > > --steve
> > >
> >
> >
>