If you're a user of Google Analytics, then no doubt you're familiar with the Data Export API. You are also probably aware that Google replaced the Data Export API with the Core Reporting API in December of last year. Google gave developers six months to switch over to the new API and those six months are just about up.
Google announced today that the Data Export API in Google Analytics will start the process of being shut down next week. If you have an app that uses the outdated API, it's suggested that you switch over to the new Core Reporting API. If not, your app will "experience service outages."
The "service outages" will be caused by Google redirecting Data Export API requests over to the Core Reporting API. This is all part of the process of taking the Data Export API out back. It will be finally laid to rest on July 10. During the next month, you should start seeing Data Feed requests returning Core Reporting API responses.
Some people don't like change and actively avoid it whenever possible. For those people, Google has also released version 2.4 of the Core Reporting API. It's backwards compatible with Data Export 2.3 and won't cause any conflicts once the change occurs.
Since most sensible people will be starting with version 3.0 and going from there, Google has created a nice developer guidel. It contains sample code from the major client libraries that the Core Reporting API supports.
If you're new to the Analytics API in general, Google has also created a dedicated tutorial to show budding developers how to take advantage of Analytics. It's pretty in-depth so it should set you up with all the knowledge you need to start building applications that use the Analytics API.