I am coding a website on witch users have to add reports (Word document\'s) and to make possible to view them I convert *.doc to *.pdf, and then displaying them throught pdf.js.
The answer, from Microsoft, is no:
Microsoft does not currently recommend, and does not support, Automation of Microsoft Office applications from any unattended, non-interactive client application or component (including ASP, ASP.NET, DCOM, and NT Services), because Office may exhibit unstable behavior and/or deadlock when Office is run in this environment.
From Considerations for Server-Side Automation of Office
From experience, here are the issues we encountered:
There are other ways to do this, however, as covered in this StackOverflow question and answers
You may consider pre-converting the word documents - for example, is it possible, when the document is uploaded, to also create the PDF then? That way, your server is simply serving up a PDF document and has to do very little work in servicing the request.