Forum OpenACS Q&A: returning pages in "chunks"

I have a large page whose loading takes a few seconds and I want it to
return in "chunks" so that the user doesn't have to wait for the
complete page to be returned after about 30 seconds. Is there any
simple (or not so simple) solution to that?

Hmm, I think my question is not specific enough ;)

The problem at hand is...I have a big database query that takes some time. The user doesn't get to see anything till the tcl page has run through. Then ad_return_template is being invoked and the html is being generated.

I want that "one-off" thing to be broken down into chunks, ideally like this:

• return some information
• loop through the database query's result and return it in chunks
• return some more information.

Uh, some more information I forgot. The style of the "header" and "information" is to be fetched from the corresponding adp file, so it is (unfortunately ;) not possible to use ns_write exclusively.

Please post your code.

You can split your template into 2 pieces and call "ns_adp_parse -file filename" for each piece.

ReturnHeaders
ns_write [ns_adp_parse -file /path/to/top_half.template.adp]
ns_write "the long stuff here"
ns_write [ns_adp_parse -file /path/to/bottom_half.template.adp]

Tom, sure, it works. You'll want to use template::adp_parse rather than ns_adp_parse, though.

Then you just have to make sure you split up all the master templates you're going to be calling into separate "top" and "bottom" templates. E.g., for the typical case where you have a master for your package, and then a site-wide default-master as well, you'd have something like:

In /packages/my-package/www/my-page.tcl:

set this_dir [file dirname [ad_conn file]]
set template_file "$this_dir/master-top"
set template_top [template::adp_parse $template_file [list title $title context_bar $context_bar]]

In /packages/my-package/www/master.adp:

<include src="master-top" title="@title@" context_bar="@context_bar@">

<slave>

<include src="master-bottom" right_side_sig="@right_side_sig@">

In /packages/my-package/www/master-top.adp:

<master src="/www/default-master-top">
<property name=focus>@focus@</property>
<property name=title>@title@</property>
<property name=context_bar>@title@</property>

<h2>@title@</h2>
@context_bar@
<hr>

<slave>

You get the idea... Only mildy annoying to do, at worst.