A system comprising: a first edge server including a first processor ; a second edge server ; and a terminal , wherein the first edge server and the second edge server are disposed on an edge of a cloud network, the terminal is configured to establish an encryption communication for service processing with the second edge server ; the encryption communication is based on a session information comprising a session identifier, ID, and an encryption key; the session information is published by the second edge server in shared information stored in a distributed storage in a form of a blockchain across the first edge server , a cloud server and the second edge server in the cloud network; upon determining that the service processing for the terminal is to be switched to the first edge server , the second edge server is configured to notify the terminal of information about the first edge server ; the first edge server is configured to: receive a service request from the terminal ; if the service request includes a session identifier, ID, determine whether the session ID in the service request corresponds to the session information published by the second edge server in the shared information stored in the distributed storage; and if the determination is positive, start encryption communication with the terminal using the encryption key in the session information; and the first processor is configured to: if the determination is negative, generate a new session information comprising a new session ID and a new encryption key for encryption communication with the terminal and publishing the new session information in the shared information; and if the service request does not include a session ID, generate a new session information comprising a new session ID and a new encryption key for encryption communication with the terminal and publishing the new session information in the shared information. a first edge server including a first processor ; a second edge server ; and a terminal , wherein the first edge server and the second edge server are disposed on an edge of a cloud network, the terminal is configured to establish an encryption communication for service processing with the second edge server ; the encryption communication is based on a session information comprising a session identifier, ID, and an encryption key; the session information is published by the second edge server in shared information stored in a distributed storage in a form of a blockchain across the first edge server , a cloud server and the second edge server in the cloud network; upon determining that the service processing for the terminal is to be switched to the first edge server , the second edge server is configured to notify the terminal of information about the first edge server ; if the determination is negative, generate a new session information comprising a new session ID and a new encryption key for encryption communication with the terminal and publishing the new session information in the shared information; and if the service request does not include a session ID, generate a new session information comprising a new session ID and a new encryption key for encryption communication with the terminal and publishing the new session information in the shared information. <EOS>