Orion client API can roughly be divided into services and library objects.
Orion Application Services support file read/write, command registration and access, user login, preferences, and dialogs for examples. The Services are contributed by plugins (?) and (?) and used by library objects (?) and by plugins; Services are available via a service registry. All requests of a service are made through the registry, so that the registry can use appropriate communication mechanisms, depending on where the service resides (locally or in another domain). They are not instantiated in client code, nor are references to service objects maintained in client code. All interaction with services are asynchronous. If there is a return value to be obtained from a service upon issuing a particular request, it is provided via a callback object passed in by the client.
Library objects are either stateless objects providing utility functions, or stateful objects that are instantiated directly by each client that needs one. Library objects never contain shared state that is available to multiple plugins or services.
See the Orion Developer Guide for complete details on available client APIs and services.
See Source Documentation for object and method programming interfaces.