This morning, Alfresco announced the general availability of the public Alfresco API. The public Alfresco API allows developers to create custom applications (desktop, mobile, or cloud) that persist content to Alfresco in the Cloud. The API includes CMIS plus some Alfresco REST calls that provide functionality CMIS does not cover.
To use the Alfresco API, all you have to do is become a registered developer at http://developer.alfresco.com. Once you've verified your email address, you can add applications to your profile. Each application has a unique authentication key and a secret. OAuth2 is used to handle authentication.
Once you have your authentication key and secret, you can start making calls against the API. Calls that hit the Alfresco REST part of the API return JSON. Calls that leverage CMIS return AtomPub XML. If you already know how to make CMIS calls, you already know how to use the Alfresco API--just grab the latest version of your favorite CMIS client, like OpenCMIS or cmislib, and pass in the authorization header.
Here are some resources to help you get started:
Alfresco Developer Portal
Alfresco API Documentation
Introduction Presentation from JavaOne
Alfresco API Screencasts showing how to register for an application key and how to execute simple command-line Java applications that leverage the API
Sample Java code showing simple command-line examples with Google's OAuth2 client and the Alfresco API.
Python examples showing the same command-line examples as the Java examples above.
If you want to discuss the public Alfresco API, use this forum.