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As discussed earlier, resources are allocated to channels, either explicitly or implicitly, to serve the needs of the program. The Resource Manager (RM) driver is used to control access of resources across all processes attempting to use them.
Resources are described to RM when the system initializes or when speech resources are put into service. The usage vector, described in the following section, describes the load the resource usage imposes on the speech resource.
RM uses an algorithm whereby the least functional, lightest loaded speech resource is selected. For example, if a system contains 2 speech resources, one supporting voice record and play and the other supporting voice record and play, recognition and echo cancellation, and play resources are requested, RM selects from the speech resource supporting only record and play first since it is least functional.
When a card is gracefully taken out of service by a maintenance process, all current allocations are maintained but no new allocations are allowed. This allows allocations to be released from a card until the card is idle, at which time it is released to the maintenance process.
If a maintenance process forcibly removes a card from service, any current activities on the card are terminated. Any activities terminated in this way receive an IRE_<activity>_DONE event with the modifiers of IREM_ERROR and IRER_RESOURCE_REMOVED. For each resource explicitly allocated by a channel on the affected card, an IRE_RESOURCE_REMOVED event is generated by the IRAPI, informing the application of the resource removal.
