You can use the adobe online pdf-html converter but the user must access the link and be able to enter the URL of the pdf to convert. You can enable this, for a particular online pdf, such as done here:
This is done using a form. The form action points to the adobe conversion page at http://access.adobe.com/perl/convertPDF.pl but passes as a hidden field (named url) the actual url of the pdf file to convert. This must be an absolute URL. For example:
for Version 11.21.01
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