PDF is not a part of W3 standards. Even though wide range of browsers informally support it (usually with separate pluggable PDF viewers), you should never rely in the fact the client system has such support.
You can switch to pure HTML. If PDFs are essential for the business (which would be the pretty usual case), you can do one of the two:
- Provide PDF content (using the content type "application/pdf" as needed, please see http://www.iana.org/assignments/media-types/media-types.xhtml#application[^]).
The rest of it will depends on the client side. If in-browser viewer of PDF is available to the client's browser, the document will be shown, otherwise, the user will get an option: open the document using default PDF viewer installed on the client system or download the file. If no default viewer is installed, the user will be left with the option to download it. After downloading, the use may decide to view the document somehow; this is left to the user.
Personally, I think this is a very best option, not only because it is the simplest, also, it is the least intrusive and convenient for most reasonable users. - Alternatively, you could somehow map PDF onto HTML (which have no one-to-one correspondence, because rendering concepts are radically different) and convert PDF to some HTML representation on the fly:
http://bit.ly/JUPgLO[^].
Good luck,
—SA