A control method in a wireless communications network comprising a centralized controller, wherein the method comprises: generating, by a centralized controller in a communications network, a to-be-confirmed list according to a service type of a service flow and a data path type template, wherein the data path type template comprises all types of processing functions and comprises for each such type of processing function a selection instruction in association with the considered type of processing function, the to-be-confirmed list being a list of all first types of processing functions, the first types of processing functions being the types of processing functions in the data path template which are optional to the service flow; filtering, by the centralized controller, the list of first types of processing functions by applying to each first type of processing function in the list of first types of processing functions the associated selection instruction; generating, after filtering the list of first types of processing functions, a confirmed list, wherein the confirmed list is a list of all second types of processing functions, and the second types of processing functions are the types of processing functions in the first types of processing functions which are mandatory to the service flow; selecting, by the centralized controller, a corresponding processing instance for each second type of processing function according to a status of an instance of each function node in a network topology and the service quality of service, QoS, information of the service flow, and sequentially selecting a working policy and a working parameter for each processing instance, wherein the instance of each function node corresponds to one processing instance, and the network topology comprises types of processing functions of the instances of all the function nodes, connection relationships between the instances of all the function nodes, and statuses of the instances of all the function nodes; generating, by the centralized controller, a full path policy, wherein the full path policy comprises all the processing instances that the service flow sequentially flows through and the working policy and the working parameter that correspond to each processing instance; and sending, by the centralized controller, the full path policy to an instance of each function node according to the network topology; wherein the selection instruction indicates mandatory or optional. generating, by a centralized controller in a communications network, a to-be-confirmed list according to a service type of a service flow and a data path type template, wherein the data path type template comprises all types of processing functions and comprises for each such type of processing function a selection instruction in association with the considered type of processing function, the to-be-confirmed list being a list of all first types of processing functions, the first types of processing functions being the types of processing functions in the data path template which are optional to the service flow; filtering, by the centralized controller, the list of first types of processing functions by applying to each first type of processing function in the list of first types of processing functions the associated selection instruction; generating, after filtering the list of first types of processing functions, a confirmed list, wherein the confirmed list is a list of all second types of processing functions, and the second types of processing functions are the types of processing functions in the first types of processing functions which are mandatory to the service flow; selecting, by the centralized controller, a corresponding processing instance for each second type of processing function according to a status of an instance of each function node in a network topology and the service quality of service, QoS, information of the service flow, and sequentially selecting a working policy and a working parameter for each processing instance, wherein the instance of each function node corresponds to one processing instance, and the network topology comprises types of processing functions of the instances of all the function nodes, connection relationships between the instances of all the function nodes, and statuses of the instances of all the function nodes; generating, by the centralized controller, a full path policy, wherein the full path policy comprises all the processing instances that the service flow sequentially flows through and the working policy and the working parameter that correspond to each processing instance; and sending, by the centralized controller, the full path policy to an instance of each function node according to the network topology; wherein the selection instruction indicates mandatory or optional.