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The IRAPI provides applications with access to abstract capabilities and does not require the application to directly manage the hardware resources required to provide those capabilities.
The IRAPI attempts to make resources available when the application calls functions that implicitly require resources (for example, play or record). When a channel frees the resource, the IRAPI makes it available to other applications running on the platform. In addition, the IRAPI supports reserving, freeing, and querying of resources. Where required, an application may pre-allocate resources to guarantee that those resources are available when needed. When applications need to be isolated applications from each other to avoid resource contention, an application can be restricted to use a only subset of available resources.
The IRAPI provides consistent resource allocation failure modes for both explicit and implicit requests for dynamic resources. If a required resource is not immediately available, applications can fail the request immediately, arrange to wait for the resource forever, or wait for the resource for some fixed period of time. In the last case, if the resource is not available within the time period, the application is notified of the failure with an event.
Library states are used by the IRAPI library to maintain information about channel activities and to prevent applications from attempting illegal operation sequences. In most cases, applications respond to the events as they occur and seldom need to know the library state.
