Handling feed changes

[farski]

It'd be great if folks who have implemented logic for determining when feeds change could share the decisions they've made about how to handle that. When I've done this in the past, the the main cases have been: are any episodes new, have any episodes disappeared, and have any episodes changed. That last being the trickiest. I know there are lot of ways to approach it, and they tend to be subjective.

[cqr]

At RadioPublic, we consider the feed changed if a single significant byte has changed. We strip out content that the apps do not use and then hash the result and use that as an etag. If the content gets to the apps, they will parse and reconcile on the device.

During the process that strips out content that the apps don't use, we also normalize whitespace.