Do you need to protect a new web service with a patent?

If I came up with a new web service or API in the US (like gravatar) my understanding is that I have exactly one year to fill a patent on the service unique process if I want any rights to it. To save money during that first year I could also file a Provisional Patent to buy some time and save some money in the short run.

Anyway, the US uses "first to invent" to protect inventors that are beaten by others who might file first even if they did not invite the [noun/idea] first. In other words, if you made it first then you get first dibs on the patent.

So my question is, if I release a web API like gravatar or disqus before I filed anything - would I be in danger of someone liking my idea and stealing it if they file first - or would I have a couple months to work on the patent after the launch without worry since it's clear I released the site/API first?

My main concern is that someone will like what I did, copy it, patent it first, and then sue me for using their patented process.