Rails - Apr 2005 - Good AJAX related example app source code or tutorials for Rails?

So, my other question for the day is regarding good places to delve into 
the mysteries of AJAX + Rails. I''ve found a couple of apps whose
authors
kindly offered the source code for download, thereby assisting me 
greatly in figuring out Rails in general, and some of how AJAX ties in, 
but I still feel like I''ve got big gaps in my knowledge. For those who 
might benefit from the couple of Apps with source code available as I 
did, they''re available here:

http://www.rousette.org.uk/blog/archives/2004/11/28/rails-gtd-application/

http://darthapo.com/repos/taskthis.html

Are there any other good examples of fleshed out applications from which 
to learn? Obviously, I''ve gone through all the tutorials on the RoR 
website, the onLAMP tutorial, the OReilly tutorial(s), etc... so what 
I''m looking for are BIGGER more complicated applications which really 
flex the Rails framework. Any examples of AJAX are just gravy I suppose. 
Any assistance is greatly appreciated.

Perhaps some people can handle reading the API documentation, but I am 
not one of those... if I had 90% of the knowledge and just needed a 
refresher or a little tidbit then the documentation would work perfectly 
for that, but the lack comprehensive documentation... i.e. in the middle 
between super specific/technical and entry level tutorial... it can be 
difficult to get past the initial tutorials because they don''t do much 
for really implementing much beyond just the bare basics of Rails.

Anyway, if one of the upcoming five Rails books was available I''m sure 
they''d help a lot to fleshing out my knowledge, ah well. June
isn''t that
far away, right?

Ciao, Abe B.


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On 4/27/05, Abe Burnett
<abe.burnett-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:
> So, my other question for the day is regarding good places to delve into
> the mysteries of AJAX + Rails. I''ve found a couple of apps whose
authors
> kindly offered the source code for download, thereby assisting me..
> *snip *
IMO the key with ajax (or flash for that matter) is to keep it
unobtrusive as possible, so that it becomes just another way to
edit/update your data in-page (for example) rather than providing the
whole basis of your UI.  Rails is great for ajax because you are
already rendering things as partials, so there''s very little
additional code.

A great example is the excellent blog software Typo [1], where
commenting is done via ajax; you enter the details on the form, it
updates the page with your comment.

<tangent="on">

However (afaik) this doesn''t show you the comments that have been
entered _since_ your last page load, so maybe a good way to learn
ajax+rails would be to extend this functionality, and return all new
comments in the same batch :)  [2]

That isn''t to say that ajax couldn''t be used for something
cool like
rendering partials from the *client* side, to take advantage of
memcache/mod_cache/squid/something else that''s good at returning fast
queries.  If anyone''s interested in this, buzz me because I''m
planning
on working on it this week.

</tangent>


Is this what you had in mind?  Or were you looking for a gmail-type app?

--courtenay

[1] http://typo.leetsoft.com
[2] you''d probably do this by embedding a last_comment_id in the
comment form, and return a collection of partials where id >
last_comment_id.

Abe Burnett wrote:
> Are there any other good examples of fleshed out applications from 
> which to learn? 
EliteJournal and RForum are the ones I am familiar with. Both are quite 
fully "fleshed out" as you put it :)

-- 
Best regards,

Alexey Verkhovsky

Ruby Forum: http://ruby-forum.org        (moderator)
RForum:     http://rforum.andreas-s.net  (co-author)
Instiki:    http://instiki.org           (maintainer)

Courtenay wrote:
> <tangent="on">
> That isn''t to say that ajax couldn''t be used for
something cool like
> rendering partials from the *client* side, to take advantage of
> memcache/mod_cache/squid/something else that''s good at returning
fast
> queries.  If anyone''s interested in this, buzz me because
I''m planning
> on working on it this week.
> </tangent>
I''m not sure what you mean by rendering partials from the client side
or
how it could take advantage of a fast cache or proxy.  Could you elaborate?

Thanks!
jeremy

Courtenay wrote:
>On 4/27/05, Abe Burnett
<abe.burnett-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
>  
>
>>So, my other question for the day is regarding good places to delve into
>>the mysteries of AJAX + Rails. I''ve found a couple of apps
whose authors
>>kindly offered the source code for download, thereby assisting me..
>>*snip *
>>    
>>
>
>IMO the key with ajax (or flash for that matter) is to keep it
>unobtrusive as possible, so that it becomes just another way to
>edit/update your data in-page (for example) rather than providing the
>whole basis of your UI.  Rails is great for ajax because you are
>already rendering things as partials, so there''s very little
>additional code.
>
>A great example is the excellent blog software Typo [1], where
>commenting is done via ajax; you enter the details on the form, it
>updates the page with your comment.
>
><tangent="on">
>
>However (afaik) this doesn''t show you the comments that have been
>entered _since_ your last page load, so maybe a good way to learn
>ajax+rails would be to extend this functionality, and return all new
>comments in the same batch :)  [2]
>
>That isn''t to say that ajax couldn''t be used for something
cool like
>rendering partials from the *client* side, to take advantage of
>memcache/mod_cache/squid/something else that''s good at returning
fast
>queries.  If anyone''s interested in this, buzz me because
I''m planning
>on working on it this week.
>
></tangent>
>
>
>Is this what you had in mind?  Or were you looking for a gmail-type app?
>
>--courtenay
>
>[1] http://typo.leetsoft.com
>[2] you''d probably do this by embedding a last_comment_id in the
>comment form, and return a collection of partials where id >
>last_comment_id.
>
>  
>
Thanks very much for the thoughtful response Courtenay! I see a major 
strength of AJAX as being what it''s capable of doing client side. The 
primary thing I detest about web apps up to this point is the amount of 
traffic they generate, how every user action requires a request to the 
server and a page refresh. Talk about archaic! Or, at least it really 
seems about high time that we moved closer to behavior traditionally 
only available in software applications running from a users computer. 
AJAX blows my hair back because (as I understand it anyway), you can 
essentially allow the user to continue using your application while you 
put backend processes into the background, so that the user doesn''t
have
to wait for processing unless absolutely necessary.

Like, I''m not sure at all what it''d take to actually do, but
in the
comment example you referred to regarding Typo it would make sense to 
accept the users comment and display it immediately, while in the 
background writing that comment to the database. Thus, no page refresh, 
and the user can continue to use the web page or the site as a whole 
without waiting for the process of storing the comment to occur.

So, is it not currently possible (using available features) to render 
partials from the client side? And if not, what are the possible means 
of accomplishing such and the various reasons for doing it one way and 
not another? A very entertaining and enlightening tangent, btw.

I''ll take a look at Typo and see what I can learn from it. Thanks for 
the suggestion!

Ciao, Abe B.


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hey bitsweat!

on my box, apache + mod_cache easily churns out 1200 requests/second
whereas rails on its own is about 12/second. (heavy lifting involved).
 so my theory was, why not use the fast apache memory-caching to cache
some partials or actions, and spit them back without having to go
through the whole rails overhead?

sure, you use some more tcp sockets, but it might make sense.  note
that I haven''t actually tried this, :)

this is intended for a community site where some of the data is
user-specific (like, being able to edit things, or browser detection)
but most can be cached for everyone.  I got this idea after reading of
Mozilla''s woes with caching--where people would get old data (based on
server-side browser sniffing).

So you set up the page, with the user stuff, and empty containers, and
inside the page is some javascript which contains ajax calls, which
fill out the rest of the page.

note that this does NOT break the back button, because you''re still
viewing html pages; just that parts of the content are filled out with
an ajax call.. and hopefully it all degrades back flat.

1] you set up a controller in rails that returns just the partial,
just like you would with a form update
2] in your html, you setup a window.onload that does an ajax call
3] ..which fills out the relevant containers.


hope this makes some sense.

--courtenay

On 4/27/05, Jeremy Kemper <jeremy-w7CzD/W5Ocjk1uMJSBkQmQ@public.gmane.org>
wrote:
> Courtenay wrote:
> > <tangent="on">
> > That isn''t to say that ajax couldn''t be used for
something cool like
> > rendering partials from the *client* side, to take advantage of
> > memcache/mod_cache/squid/something else that''s good at
returning fast
> > queries.  If anyone''s interested in this, buzz me because
I''m planning
> > on working on it this week.
> > </tangent>
> 
> I''m not sure what you mean by rendering partials from the client
side or
> how it could take advantage of a fast cache or proxy.  Could you elaborate?
> 
> Thanks!
> jeremy
>

> Thanks very much for the thoughtful response Courtenay! I see a major
> strength of AJAX as being what it''s capable of doing client side.
The
> primary thing I detest about web apps up to this point is the amount of
> traffic they generate, how every user action requires a request to the
> server and a page refresh. Talk about archaic! Or, at least it really
> seems about high time that we moved closer to behavior traditionally
> only available in software applications running from a users computer.
> AJAX blows my hair back because (as I understand it anyway), you can
> essentially allow the user to continue using your application while you
> put backend processes into the background, so that the user
doesn''t have
> to wait for processing unless absolutely necessary.
the problem is, if you keep browsing (move away from the page), any
requests you sent are possibly cancelled.

actually, in my apps i especially like to use ajax for deleting rows
in scaffold tables.
you hit "delete" and the delete button changes to text,
"deleting..."
thus preventing it from being clicked. then when the action is
successful, the whole row fades/squishes/hides from view.  I think I
wrote this up on the ror wiki.

The same with saving; the line is re-rendered *from the db as a
partial* to maintain consistency - that way you know your data is
saved the way you want.

> Like, I''m not sure at all what it''d take to actually do,
but in the
> comment example you referred to regarding Typo it would make sense to
> accept the users comment and display it immediately, while in the
> background writing that comment to the database. Thus, no page refresh,
> and the user can continue to use the web page or the site as a whole
> without waiting for the process of storing the comment to occur.
you actually *do* want to hang around for errors, db problems,
validation problems. so rendering straight to the page isn''t
necessarily such a good idea. note that there is no "best practice"
way of handling errors at this stage...

--courtenay

On 4/27/05, Courtenay <court3nay-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:
> on my box, apache + mod_cache easily churns out 1200 requests/second
> whereas rails on its own is about 12/second. (heavy lifting involved).
>  so my theory was, why not use the fast apache memory-caching to cache
> some partials or actions, and spit them back without having to go
> through the whole rails overhead?
Does mod_cache gives you something more than the webserver independent
rails caching? How did you measure that 12 request/second?

Zsombor

-- 
http://deezsombor.blogspot.com

On 4/27/05, Dee Zsombor
<dee.zsombor-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:
> On 4/27/05, Courtenay
<court3nay-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> > on my box, apache + mod_cache easily churns out 1200 requests/second
> > whereas rails on its own is about 12/second. (heavy lifting involved).
> >  so my theory was, why not use the fast apache memory-caching to cache
> > some partials or actions, and spit them back without having to go
> > through the whole rails overhead?
>
> Does mod_cache gives you something more than the webserver independent
> rails caching? How did you measure that 12 request/second?
>
> Zsombor
The reqs/second I got from running ab.

The in-rails caching I haven''t measured; I guess it''s likely
that
using the in-rails caching is just as fast for the relevant fragments?
 I haven''t tested this, and don''t really know how to. Which is
where
you guys come in ;)

My vague calculations work on the idea that you can run two apps, one
"Generic" with sessions disabled (for the performance boost) and one,
smaller app "User" with just the session-relevant code.

Starts to get mightily complex!

The idea was that you can''t beat the webserver cache for pure speed,
even with rails caching or whatever, because with rails there''s still
a bit of overhead, even in loading the cache.