# Filter command and query functions

Applications can modify endpoint and channel parameters by sending commands to the filters that make up the endpoint or channel. Applications can also query configuration and status information for particular endpoints and channels by sending queries to the filters that make up the endpoint or channel. In both cases, the MSPP API returns events containing buffers that the application must explicitly release.

Function | Synchronous/ Asynchronous | Description
mspSendCommand | Asynchronous | Sends a command to an MSPP endpoint or channel filter.
mspSendQuery | Asynchronous | Provides filter configuration or status information.
mspReleaseBuffer | Synchronous | Frees returned event buffers (generated as a result of mspSendQuery or mspSendCommand calls) so the application can reuse them. This function executes synchronously.
mspGetFilterHandle | Synchronous | Retrieves a filter ID associated with an MSPP API endpoint filter or channel filter.

Note: mspSendQuery and mspSendCommand events return buffered information that the application must release with mspReleaseBuffer.

Refer to the Endpoint filter summary for a list of supported filters and the commands and queries that apply to them.