breathing code

The other day I released a Plone 4 compatible version of collective.pdfpeek in which I’ve implemented an asynchronous processing queue for pdf to image conversions. In the initial versions of pdfpeek, a user would be forced to wait for their pdf file to be processed, one page at a time, by ghostscript, before Plone returned a response to their browser. Talk about a bad user experience. Many PDF files are so large that this time spent waiting by the user became unacceptably long. So I’ve tried to work around this by implementing a simple queue where a conversion job is added to the queue when a PDF file is uploaded to a file object in Plone. One can then either process the queue manually by visiting a certain url as admin, or preferably by automating this process with cron and curl or via a zope clock server process. When the user uploads a PDF file, a conversion job is added to the queue and the user can then go about their business, adding or editing other content and return to the file object later to see the image previews available once the conversion job in the queue has been processed. collective.pdfpeek 0.18 works under Plone 3, but the integration doctests currently need some attention in order to get them passing on both Plone 3 and 4, so that is why version 0.18 only “officially” supports Plone 4.