# &develguide;

## Available Functions

### `register_qoscb (qos, type, cb, param)`

Register a new callback to the qos.

Meaning of the parameters is as follows:

- struct qos_ctx_st* qos - qos to register callback to. It may be NULL only for QOSCB_CREATED callback type, which is not a per qos type.

- int type - types of callbacks; more types may be registered for the same callback function; only QOSCB_CREATED must be registered alone. Possible types:

  - QOSCB_CREATED - called when a new qos context is created - it's a global type (not associated to any qos).

  - QOSCB_ADD_SDP - called when a new SDP was added to the qos context - it's a per qos type.

  - QOSCB_UPDATE_SDP - called when an existing SDP is updated - it's a per qos type.

  - QOSCB_REMOVE_SDP - called when an existing SDP is removed - it's a per qos type.

  - QOSCB_TERMINATED - called when the qos is terminated.

- qos_cb cb - callback function to be called. Prototype is: void (qos_cb) (struct qos_ctx_st *qos, int type, struct qos_cb_params *params);

- void *param - parameter to be passed to the callback function.