Hello list,
The subject pretty much says it all: I''m looking for a way to send the
output from a long-running, slowly-outputting system command to the
browser without the app hanging until that system command completes.
I''ve tried the obvious idioms (see below), but there doesn''t
seem to be
a way to prevent the application blocking on the system command. When
(eventually) foo completes, the data is sent to the browser, but the
poor user has to sit watching the egg-timer until all of the data has
been slurped into memory by rails before it starts the send. I''d like
the data to start streaming to the browser as soon as it becomes
available from the system command.
I have tried:
backticks
IO.popen
Proc.new { ... File.popen ... }
Perhaps I need something other than send_data? Is there a way to jump
out of rails to use exec from the controller ("application failed to
start")?
I am considering POSTing to a small bespoke CGI. Or maybe I could do
something cunning with Net::SSH channels? The first of these will
certainly work, but neither seem very satisfactory. What am I missing?
Thanks for any enlightment,
Martin.
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Martin Carpenter wrote:> Hello list, > > The subject pretty much says it all: I''m looking for a way to send the > output from a long-running, slowly-outputting system command to the > browser without the app hanging until that system command completes. > I''ve tried the obvious idioms (see below), but there doesn''t seem to be > a way to prevent the application blocking on the system command. When > (eventually) foo completes, the data is sent to the browser, but the > poor user has to sit watching the egg-timer until all of the data has > been slurped into memory by rails before it starts the send. I''d like > the data to start streaming to the browser as soon as it becomes > available from the system command. > > I have tried: > backticks > IO.popen > Proc.new { ... File.popen ... } > > Perhaps I need something other than send_data? Is there a way to jump > out of rails to use exec from the controller ("application failed to > start")? > > I am considering POSTing to a small bespoke CGI. Or maybe I could do > something cunning with Net::SSH channels? The first of these will > certainly work, but neither seem very satisfactory. What am I missing? > > > Thanks for any enlightment, > > Martin.Pretty sure that rails doesn''t do streaming of any sort. You could spin up a BackgroundDRB process, and send the user to a page with a big happy animated gif that says loading. And refresh, or make a little AJAX call, every few seconds. If the job is done, get its data, show it to the user. Or do some sort of polling to get the computed values from your background process as it chugs along. Someone may know of a way, but I don''t think rails is capable of streaming much of anything. -- Posted via http://www.ruby-forum.com/. --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To post to this group, send email to rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org To unsubscribe from this group, send email to rubyonrails-talk-unsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en -~----------~----~----~----~------~----~------~--~---
On 29 May 2008, at 21:26, Martin Carpenter wrote:> > > Hello list, > > The subject pretty much says it all: I''m looking for a way to send the > output from a long-running, slowly-outputting system command to the > browser without the app hanging until that system command completes. > I''ve tried the obvious idioms (see below), but there doesn''t seem to > be > a way to prevent the application blocking on the system command. When > (eventually) foo completes, the data is sent to the browser, but the > poor user has to sit watching the egg-timer until all of the data has > been slurped into memory by rails before it starts the send. I''d like > the data to start streaming to the browser as soon as it becomes > available from the system command. > > I have tried: > backticks > IO.popen > Proc.new { ... File.popen ... } > > Perhaps I need something other than send_data? Is there a way to jump > out of rails to use exec from the controller ("application failed to > start")? >Use a mongrel handler? That won''t block your app (but ties you to mongrel) Fred> I am considering POSTing to a small bespoke CGI. Or maybe I could do > something cunning with Net::SSH channels? The first of these will > certainly work, but neither seem very satisfactory. What am I missing? > > > Thanks for any enlightment, > > Martin. > > > > > >--~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To post to this group, send email to rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org To unsubscribe from this group, send email to rubyonrails-talk-unsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en -~----------~----~----~----~------~----~------~--~---
On Thu, 2008-05-29 at 23:57 +0100, Frederick Cheung wrote:> Use a mongrel handler? That won''t block your app (but ties you to > mongrel)Thanks Fred, good suggestion (although I also don''t particularly like being tied to mongrel, it does happen to be what we''re using, and it gets me over the hump for now). The other big help was Alex''s re-emphasis of the word "streaming" which got me thinking about audio and video streaming, and turned up this nice blog entry: http://blog.rubyenrails.nl/articles/2008/02/23/breaking-out-of-rails-mvc-with-mongrel-handlers Problem solved! I have a couple of smaller issues if there''s anyone with any deeper mongrel handler knowledge here - for instance, I would like to redirect_to a controller (possibly setting flash[:error] on the way) if there''s a problem, but redirect_to is undefined. I''d also like to DRY-up my handler since I''ve reimplemented (copy/paste) a couple of small private methods from my controller - they could be moved to the model, but then I can''t see how to call those from the mongrel handler either? The mongrel documentation is a little... sparse :-/ Thanks again, Martin. --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To post to this group, send email to rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org To unsubscribe from this group, send email to rubyonrails-talk-unsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en -~----------~----~----~----~------~----~------~--~---
On May 30, 6:48 pm, Martin Carpenter <mcarpen...-GANU6spQydw@public.gmane.org> wrote:> On Thu, 2008-05-29 at 23:57 +0100, Frederick Cheung wrote: > > Use a mongrel handler? That won''t block your app (but ties you to > > mongrel) > > Thanks Fred, good suggestion (although I also don''t particularly like > being tied to mongrel, it does happen to be what we''re using, and it > gets me over the hump for now). The other big help was Alex''s > re-emphasis of the word "streaming" which got me thinking about audio > and video streaming, and turned up this nice blog entry: > > http://blog.rubyenrails.nl/articles/2008/02/23/breaking-out-of-rails-... > > Problem solved! > > I have a couple of smaller issues if there''s anyone with any deeper > mongrel handler knowledge here - for instance, I would like to > redirect_to a controller (possibly setting flash[:error] on the way) if > there''s a problem, but redirect_to is undefined. I''d also like to DRY-up > my handler since I''ve reimplemented (copy/paste) a couple of small > private methods from my controller - they could be moved to the model, > but then I can''t see how to call those from the mongrel handler either? > The mongrel documentation is a little... sparse :-/The mongrel handler is just ruby code in the same memory space as the rest of your app. Put the shared code in a module and include it in both handler & controller Your mongrel handler isn''t a controller so all the niceties like the flash and redirect_to are gone. If you want to redirect then you''ll need to generate the 302 response yourself. Be wary about calling code from your app, there are bits of rails that are not thread safe. Fred --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To post to this group, send email to rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org To unsubscribe from this group, send email to rubyonrails-talk-unsubscribe@googlegroups.com For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en -~----------~----~----~----~------~----~------~--~---
On Fri, 2008-05-30 at 11:05 -0700, Frederick Cheung wrote:> The mongrel handler is just ruby code in the same memory space as the > rest of your app. Put the shared code in a module and include it in > both handler & controllerAll fixed - thanks for the assistance! Martin. --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To post to this group, send email to rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org To unsubscribe from this group, send email to rubyonrails-talk-unsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en -~----------~----~----~----~------~----~------~--~---