I am an ISV and I am integrating a web service into the package I am creating. That web service will need to call back into the user's SF org. Is there a best practice for how to enable this without requiring the user to store his/her password? Is there a best practice paper for how this type of integration should be built?

I am an ISV and I am integrating a web service into the package I am creating. That web service will need to call back into the user's SF org. Is there a best practice for how to enable this without requiring the user to store his/her password? Is there a best practice paper for how this type of integration should be built?