The ASPxCallback control represents a non visual component that allows callbacks to be sent from the client side and processed both on the server and client sides.
The ASPxCallback component implements a comprehensive client-side functionality to enable operating callbacks on the client. The client-side object model contains the client object for the ASPxCallback component (ASPxClientCallback), its method required to send a callback to the server (ASPxClientCallback.PerformCallback), a method that indicates whether a callback is in processing (ASPxClientControlBase.InCallback) and an event allowing it to perform the final client processing of the callback (ASPxClientCallback.CallbackComplete). A handler for the available client-side event can be assigned by using the component's ASPxCallback.ClientSideEvents property. An instance of the ASPxClientCallback object can be easily identified on the client by using the client programmatic identifier set via the ASPxCallback.ClientInstanceName property.
The required server-side processing of a callback sent from the client side by using the ASPxClientCallback.PerformCallback method can be performed in a handler of the component's server-side ASPxCallback.Callback event.