First and second network nodes and methods thereof are provided. The method for the first network node to manage a second network node in a mobile communication system includes receiving, from a plurality of second network nodes, application programming interface (API) information related to each of the plurality of second network nodes, composing a plurality of second network node chainings based on the API information, selecting, when an API request is received from an external server, one of the plurality of second network node chainings for supporting the API request, and transmitting the API request to a second network node included in the selected second network node chaining.