3 ms·

At the end of the day, how do you implement scalable multi-threaded continuations? Yes the code has a better allure, but it's not exactly hard to add parameters

At the end of the day, how do you implement scalable multi-threaded continuations? Yes the code has a better allure, but it's not exactly hard to add parameters to http requests. Having used a few frameworks, I can tell you it's also easier to debug code that's closer to http requests. Being able to simply look at what's being passed in a simple way and understand everything instantaneously is a big advantage. Actually, this argument is more about the tools at hand, but there are definitively more and better tools to analyze http requests than anything else.

johnwatson11218 16y ago
yea I hear you. The problem I have will passing the http parameters is that it only goes one level deep. If you want to nest it arbitrarily you would have to build up a comma separated list of values to refer to all the places you need to return to. At that point, if you think of this list of return places as a set of pointers it is as if you are implementing a stack. Having this kind of thing as a first class construct could maybe allow this to be checked by the compiler. To be honest the details of implementing 'scalable multi-threaded continuations' is beyond my skill level.
draegtun 16y ago
Yes scaling continuations based web apps can be a big headache. I think this is why the Seaside developers have been scaling back continuations and making them optional in the framework: http://lists.squeakfoundation.org/pipermail/seaside/2007-December/015565.html http://lists.squeakfoundation.org/pipermail/seaside/2007-Dec... Coroutines are an interesting lighter alternative (though will still suffer from threading & session affinity issues). See coro based libraries/frameworks influenced by Seaside like Continuity (http://continuity.tlt42.org/ http://continuity.tlt42.org/) & Nagare (http://www.nagare.org/ http://www.nagare.org/) (which I think uses coros?). Here is a fulling working Continuity example: use strict; use warnings; use Continuity; use HTML::AsSubs; Continuity->new->loop; sub main { my $r = shift; ########################################### # helpers my $update_billing_info = sub { return 1 if eval { $r->param('updated') }; return; }; my $display_update_billing_info = sub { $r->print( form( input( {type => 'checkbox', name => 'updated'}, 'updated?' ), br, input( {type => 'submit'} ), p( "No. of tries thus far - $_[0]" ), )->as_HTML ); }; my $render_checkout_screen = sub {$r->print("Updated after $_[0] submits!")}; ########################################### # business logic my $count_tries; while (not $update_billing_info->()) { $display_update_billing_info->( $count_tries++ ); $r->next; } $render_checkout_screen->( $count_tries ); }

johnwatson11218 16y ago

yea I hear you. The problem I have will passing the http parameters is that it only goes one level deep. If you want to nest it arbitrarily you would have to build up a comma separated list of values to refer to all the places you need to return to. At that point, if you think of this list of return places as a set of pointers it is as if you are implementing a stack. Having this kind of thing as a first class construct could maybe allow this to be checked by the compiler. To be honest the details of implementing 'scalable multi-threaded continuations' is beyond my skill level.

draegtun 16y ago

Yes scaling continuations based web apps can be a big headache. I think this is why the Seaside developers have been scaling back continuations and making them optional in the framework: http://lists.squeakfoundation.org/pipermail/seaside/2007-December/015565.html http://lists.squeakfoundation.org/pipermail/seaside/2007-Dec... Coroutines are an interesting lighter alternative (though will still suffer from threading & session affinity issues). See coro based libraries/frameworks influenced by Seaside like Continuity (http://continuity.tlt42.org/ http://continuity.tlt42.org/) & Nagare (http://www.nagare.org/ http://www.nagare.org/) (which I think uses coros?). Here is a fulling working Continuity example: use strict; use warnings; use Continuity; use HTML::AsSubs; Continuity->new->loop; sub main { my $r = shift; ########################################### # helpers my $update_billing_info = sub { return 1 if eval { $r->param('updated') }; return; }; my $display_update_billing_info = sub { $r->print( form( input( {type => 'checkbox', name => 'updated'}, 'updated?' ), br, input( {type => 'submit'} ), p( "No. of tries thus far - $_[0]" ), )->as_HTML ); }; my $render_checkout_screen = sub {$r->print("Updated after $_[0] submits!")}; ########################################### # business logic my $count_tries; while (not $update_billing_info->()) { $display_update_billing_info->( $count_tries++ ); $r->next; } $render_checkout_screen->( $count_tries ); }