TheAPIchangesshouldprovidebothsourceandbinary()forprogramswrittentotheoriginalAPI.Thatis,existingprogrambinariesshouldcontinuetooperatewhenrunonasystemsupportingthenewAPI.Inaddition,existing()thatarere-compiledandrunonasystemsupportingthenewAPIshouldcontinuetooperate.Simplyput,theAP(_______)formulticastreceiversthatspecifysourcefiltersshouldnotbreakexistingprograms.ThechangestotheAPIshouldbeassmallaspossibleinordertosimplicitythetaskofconvertingexisting()receiverapplicationstousesourcefilters.Applicationsshouldbeabletodeletewhenthenew()filterAPIsareunavailable(e.g.,callsfailwiththeENOTSUPPerror)andreactgracefully(e.g.,reverttooldnon-source-filterAPIordisplayameaningfulerrormessagetotheuser). 横线处应选()。
A.connections B.changes C.resources D.considerations正确答案B
