Worked with this kind of tech for a few years... And trash it to go with Aspose components.

It's slow, and really hard to debug when it's not working (not only pdf output but merge fields).

Aspose is a complete no brainer, yet so many clients complain about the extra cost. Somehow they don't see the hours of their own time debugging this stuff as invariably costing far more.

Close. You don't even need a Windows service. Just us a serialized queue using MSMQ. Write the queue listener in Javascript and register with COM+. Excel automation on the server is easy if you do it right, and impossible if you do it wrong.

Most of the devs I've encountered over the years who want to use Excel server side have never heard of queuing.

> Just us a serialized queue using MSMQ. Write the queue listener in Javascript and register with COM+.

Sure, but now you have MSMQ and COM+ to deal with...and debugging/fixing when it breaks (under load), or isn't secured properly.

The smart folks shell out for a copy of Aspose Cells and get the job finished on time.

Subsequent to my MSMQ approach, I did a project with Aspose. It's a pretty good toolkit, and I would recommend it over the MSMQ/COM+ complexity - Unless you absolutely have to automate Office, which is sometimes true.

On more recent projects in last ~12 months, I have used OpenXML.