May 2013 - dancer-users - lists.preshweb.co.uk

Streaming binary data without known size? Content-length problem.
by Andy Walker 12 May '13

12 May '13

While $working on a RESTFul application, I came across a situation where I needed to pack up a directory of files (already gzipped) and send them to the user. Rather than pulling everything into memory with Archive::Tar or creating a temporary file with File::Temp that would meet an uncertain fate after file_send depending on the deployment, I decided I would try and forkexec using a pipe and just stream the tar to the user. This was easy enough to accomplish with open and '-|' and then exec ('/path/to/tar', '-c', '-f', '-' ...); in the child. After that, it was a matter of duplicating parts of send_file, and I think this is where I got it wrong. Testing with raw Telnet saw the binary data come through, so I know that at least the piping worked, but when I tested the route as users would use it, the browser downloaded an empty file and curl -v, mentioned something about "* Excess found in a non pipelined read: excess = 7989". I looked in the printed headers, and saw that it defined Content-Length: 0, which I assume is part of the problem. I tried NOT sending it using the code below using: $response->{headers}->remove_header('Content-Length'); but was unable to remove it, and I'm not sure that's what I want to do anyway. Hijacking the stream and just catting binary data doesn't seem to be part of the spec, though I'd swear I've seen it done elswhere before, but I thought I would pick the collective brains of the mailing list and see. I eventually ended up just using File::Temp::tmpnam and having tar output to that file, which I then added to a var called 'cleanup' that an after hook deletes. Then I sent with file_send as normal. So, I suppose my main question is: would this work if I were somehow able to remove the Content-Length header? I'm thinking not and, if not, should I be using chunked transfer instead? Does Dancer support this? CODE: sub send_data { Dancer::Continuation::Route::FileSent->new( return_value => _send_data(@_) )->throw } sub _send_data { my ($fh, %options) = @_; my $env = Dancer::SharedData->request->env; die "Must have streaming" if ! $env->{'psgi.streaming'}; die "Must provide content_type\n" unless $options{content_type}; die "Must provide filename\n" unless $options{filename}; binmode $fh; my $response = Dancer::SharedData->response() || Dancer::Response->new(); $response->header('Content-Type' => $options{content_type}); $response->push_header('Content-Disposition' => "attachment; filename=\"$options{filename}\"" ); $response->streamed( sub { my ( $status, $headers ) = @_; return sub { my $respond = shift; my $writer = $respond->( [ $status, $headers, ] ); my $content = $response->content; my $bytes = $options{'bytes'} || '43008'; my $buf; while ( ( my $read = sysread $fh, $buf, $bytes ) != 0 ) { $writer->write($buf); } }; } ); return $response if $response; }

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Dancer v1.3113 on its way to CPAN
by Yanick Champoux 09 May '13

09 May '13

As the subject line says, a maintenance version of Dancer is on its way to CPAN (changelog excerpt below). Nothing major there, just a few fixes and improvements. As usual, thanks a bunch to all patch submitters and bug reporters! Enjoy! `/anick 1.3113 08.05.2013 [ ENHANCEMENTS ] * GH #869: leave body parameters alone if deserialization failed (brianphillips). * GH #914: add link to melezhik's psgi chef cookbook. * GH #923: implement lazy session flushing. (David Golden) [ BUG FIXES ] * GH #920: fix pod for Dancer::Development. (ppisar) [ DOCUMENTATION ] * GH #915: add warning about behaviour of hooks with multiple packages loaded by load_app (racke). * GH #918: Fix headers syntax in Dancer::Response perldoc (Vyacheslav Matyukhin).

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What versions Moo has Dancer2 been tested with?
by Mark Wood-Patrick 01 May '13

01 May '13

What versions Moo has Dancer2 been tested with running the following program use Dancer2; get '/' => sub { "Hello World" }; dance; I get Can't locate object method "apply_roles_to_package" via package "Moo::Role" at /home/app_perf_catalog/mwoodpatrick/mongodb/PORTool/Perl/Moo-1.001000/lib/Moo/Role.pm line 208. Compilation failed in require at /home/app_perf_catalog/mwoodpatrick/mongodb/PORTool/Perl/Dancer2/lib/Dancer2.pm line 8. BEGIN failed--compilation aborted at /home/app_perf_catalog/mwoodpatrick/mongodb/PORTool/Perl/Dancer2/lib/Dancer2.pm line 8. Compilation failed in require at simple.pl line 16. BEGIN failed--compilation aborted at simple.pl line 16. Mark Wood-Patrick ----------------------------------------------------------------------------------- This email message is for the sole use of the intended recipient(s) and may contain confidential information. Any unauthorized review, use, disclosure or distribution is prohibited. If you are not the intended recipient, please contact the sender by reply email and destroy all copies of the original message. -----------------------------------------------------------------------------------

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From Dancer launch Background Process
by Hugues Max 01 May '13

01 May '13

Hello I would like to launch in background a perl program ( or function who create lot of PDF) from my Dancer APP. and view in web page the log of this program. I've done a small test, ajax part works well, but if my process backgroup is too long with sleep , nothing works, web browser wait... What is the best way to do that ? use backtick ``, system, exec ? create sub or launch external perl program as my $output = qx|perl /util/generation.pl $id &|; print $output; or fork module ? thanks for your advice Hugues. post '/generationpdf' => sub { ... ... background(); } #my test background process sub background { open (LOG,">:encoding(UTF-8)",$PATHPDF."generationpdf.log") || die ("Problème d'ouverture du fichier de log $!"); say LOG "\n################################################"; for (my $i=0;$i<300;$i++) { # sleep 1; say LOG $i; } } AJAX PART ajax '/getloadavg' => sub { my $cmd = "tail ". $PATHPDF. "generationpdf.log"; { timestamp => time, loadavg => `$cmd`, }; TEMPLATE PART <pre>Calcul des PDF: <span id="flog"></span> </pre> <script type="text/javascript"> setInterval(function() { $.getJSON('[% request.uri_base %]/getloadavg', function(response) { var point = [ response.timestamp, response.log ];; $("#timestamp").text(response.timestamp); $("#flog").text(response.flog); }) }, 1000); </script>

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