Patent Publication Number: US-11399011-B2

Title: Method for transmitting data and server device for supporting same

Description:
TECHNICAL FIELD 
     Various embodiments of the disclosure relate to a method of transmitting data and a server device supporting the same. 
     BACKGROUND ART 
     A user terminal, such as a smartphone, a tablet PC, or the like may transmit or receive data to or from an external server, using wireless/wired communication. For example, when a user executes an application on a smartphone, a tablet PC, or the like, the data processed by the executed application may be stored in an external server device. The user terminal may update or delete the information stored in the server device at the request of the user. 
     The server device may migrate the data stored therein, to another server device. For example, in the case where the existing server is updated to a new server, in the case where a server is installed in a new region, in the case where data is backed up, in the case where a part of data is stored separately, or the like, data migration may occur between server devices. 
     DISCLOSURE 
     Technical Problem 
     The data migration method between servers uses 1) a method of transmitting data without interrupting the service to be provided to a user terminal, 2) a method of transmitting data after interrupting a service (shut down), or the like. 
     1) In the case of the method of transmitting data without interrupting a service, when data is updated or deleted at the request of a user while the data is migrated, the consistency of data may be broken or the loss of data may occur. 
     2) In the case of the method of transmitting data after interrupting a service, the service provided to a user terminal is interrupted until the data migration task is completed, thereby causing inconvenience to a user. 
     Technical Solution 
     According to various embodiments of the disclosure, a data transmitting method and a server device supporting the same may provide a service without shut-down of a server. 
     According to various embodiments of the disclosure, a server device may include a memory, a communication interface, and a processor. The processor may be configured to transmit a service blocking request for a specified user, to an authentication server processing a request of a user terminal, to receive user data for the user from a first server, to transmit the user data to a second server, and to notify the authentication server that the transmission is completed, when the transmission of the user data is completed. Other various embodiments as understood from the specification are also possible. 
     Advantageous Effects 
     According to various embodiments of the disclosure, a data transmitting method and a server device supporting the same may migrate user data between servers without server shut-down to continuously provide a service during data migration. 
     According to various embodiments of the disclosure, a data transmitting method and a server device supporting the same may temporarily block the request of a user terminal corresponding to user data being migrated, thereby securing data consistency. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIG. 1  is a configuration diagram illustrating a data transmitting system, according to various embodiments. 
         FIG. 2  is a flowchart illustrating an operation of a relay server, according to various embodiments. 
         FIG. 3  is a flowchart illustrating an operation of an authentication server, according to various embodiments. 
         FIG. 4  is a signal flowchart illustrating a procedure of migrating target user data, according to various embodiments. 
         FIG. 5  is an exemplification diagram for describing migration of user data, according to various embodiments. 
         FIG. 6  illustrates a method of grouping user data and then transmitting the grouped user data, according to various embodiments. 
         FIG. 7  is a UI exemplification diagram of a user terminal, according to various embodiments. 
         FIG. 8  is a block diagram illustrating a user terminal, according to various embodiments. 
     
    
    
     MODE FOR INVENTION 
     Hereinafter, various embodiments of the disclosure may be described with reference to accompanying drawings. Accordingly, those of ordinary skill in the art will recognize that modification, equivalent, and/or alternative on the various embodiments described herein can be variously made without departing from the scope and spirit of the disclosure. With regard to description of drawings, similar components may be marked by similar reference numerals. 
     In the disclosure, the expressions “have”, “may have”, “include” and “comprise”, or “may include” and “may comprise” used herein indicate existence of corresponding features (e.g., components such as numeric values, functions, operations, or parts) but do not exclude presence of additional features. 
     In the disclosure, the expressions “A or B”, “at least one of A or/and B”, or “one or more of A or/and B”, and the like may include any and all combinations of one or more of the associated listed items. For example, the term “A or B”, “at least one of A and B”, or “at least one of A or B” may refer to all of the case (1) where at least one A is included, the case (2) where at least one B is included, or the case (3) where both of at least one A and at least one B are included. 
     The terms, such as “first”, “second”, and the like used in the disclosure may be used to refer to various components regardless of the order and/or the priority and to distinguish the relevant components from other components, but do not limit the components. For example, “a first user device” and “a second user device” indicate different user devices regardless of the order or priority. For example, without departing the scope of the disclosure, a first component may be referred to as a second component, and similarly, a second component may be referred to as a first component. 
     It will be understood that when an component (e.g., a first component) is referred to as being “(operatively or communicatively) coupled with/to” or “connected to” another component (e.g., a second component), it may be directly coupled with/to or connected to the other component or an intervening component (e.g., a third component) may be present. In contrast, when an component (e.g., a first component) is referred to as being “directly coupled with/to” or “directly connected to” another component (e.g., a second component), it should be understood that there are no intervening component (e.g., a third component). 
     According to the situation, the expression “configured to” used in the disclosure may be used as, for example, the expression “suitable for”, “having the capacity to”, “designed to”, “adapted to”, “made to”, or “capable of”. The term “configured to” must not mean only “specifically designed to” in hardware. Instead, the expression “a device configured to” may mean that the device is “capable of” operating together with another device or other parts. For example, a “processor configured to (or set to) perform A, B, and C” may mean a dedicated processor (e.g., an embedded processor) for performing a corresponding operation or a generic-purpose processor (e.g., a central processing unit (CPU) or an application processor) which performs corresponding operations by executing one or more software programs which are stored in a memory device. 
     Terms used in the disclosure are used to describe specified embodiments and are not intended to limit the scope of the disclosure. The terms of a singular form may include plural forms unless otherwise specified. All the terms used herein, which include technical or scientific terms, may have the same meaning that is generally understood by a person skilled in the art. It will be further understood that terms, which are defined in a dictionary and commonly used, should also be interpreted as is customary in the relevant related art and not in an idealized or overly formal unless expressly so defined in various embodiments of the disclosure. In some cases, even if terms are terms which are defined in the disclosure, they may not be interpreted to exclude embodiments of the disclosure. 
     A user terminal according to various embodiments of the disclosure may include at least one of, for example, smartphones, tablet personal computers (PCs), mobile phones, video telephones, electronic book readers, desktop PCs, laptop PCs, netbook computers, workstations, servers, personal digital assistants (PDAs), portable multimedia players (PMPs), Motion Picture Experts Group (MPEG-1 or MPEG-2) Audio Layer 3 (MP3) players, mobile medical devices, cameras, or wearable devices. According to various embodiments, the wearable device may include at least one of an accessory type (e.g., watches, rings, bracelets, anklets, necklaces, glasses, contact lens, or head-mounted-devices (HMDs), a fabric or garment-integrated type (e.g., an electronic apparel), a body-attached type (e.g., a skin pad or tattoos), or a bio-implantable type (e.g., an implantable circuit). 
     According to various embodiments, the user terminal may be a home appliance. The home appliances may include at least one of, for example, televisions (TVs), digital video disk (DVD) players, audios, refrigerators, air conditioners, cleaners, ovens, microwave ovens, washing machines, air cleaners, set-top boxes, home automation control panels, security control panels, TV boxes (e.g., Samsung HomeSync™, Apple TV™, or Google TV™), game consoles (e.g., Xbox™ or Play Station™), electronic dictionaries, electronic keys, camcorders, electronic picture frames, and the like. 
     According to another embodiment, an user terminal may include at least one of various medical devices (e.g., various portable medical measurement devices (e.g., a blood glucose monitoring device, a heartbeat measuring device, a blood pressure measuring device, a body temperature measuring device, and the like), a magnetic resonance angiography (MRA), a magnetic resonance imaging (MRI), a computed tomography (CT), scanners, and ultrasonic devices), navigation devices, Global Navigation Satellite System (GNSS), event data recorders (EDRs), flight data recorders (FDRs), vehicle infotainment devices, electronic equipment for vessels (e.g., navigation systems and gyrocompasses), avionics, security devices, head units for vehicles, industrial or home robots, automated teller machines (ATMs), points of sales (POSs) of stores, or internet of things (e.g., light bulbs, various sensors, electric or gas meters, sprinkler devices, fire alarms, thermostats, street lamps, toasters, exercise equipment, hot water tanks, heaters, boilers, and the like). 
     According to an embodiment, the user terminal may include at least one of parts of furniture or buildings/structures, electronic boards, electronic signature receiving devices, projectors, or various measuring instruments (e.g., water meters, electricity meters, gas meters, or wave meters, and the like). According to various embodiments, the user terminal may be one of the above-described devices or a combination thereof. A user terminal according to an embodiment may be a flexible electronic device. Furthermore, a user terminal according to an embodiment of the disclosure may not be limited to the above-described electronic devices and may include other electronic devices and new electronic devices according to the development of technologies. 
       FIG. 1  is a configuration diagram illustrating a data transmitting system, according to various embodiments. 
     Referring to  FIG. 1 , a data transmitting system  101  may include a first server (or origin server)  110 , a second server (or target server)  120 , a relay server  130 , an authentication server  140 , and a user terminal  150 . 
     According to various embodiments, each of the first server (or origin server)  110 , the second server (or target server)  120 , the relay server  130 , the authentication server  140 , and the user terminal  150  may include a processor, a memory, and a communication interface. The processor may perform the operations necessary for the operation of each device (server or terminal). The memory may store data necessary for the operation of each device (server or terminal). The communication interface may transmit or receive data to or from an external device. 
     According to various embodiments of the disclosure, the first server (origin server)  110  may be a server providing the related service (e.g., a cloud service, a game service, a payment service, or the like) at the request of the user terminal  150 . For example, when the user terminal  150  executes an application, various requests associated with a user or an application may occur in the user terminal  150 . The user terminal  150  may transmit the requests to the first server  110 . The first server  110  may perform arithmetic operations at the requests received from the user terminal  150  or may store data (hereinafter referred to as “user data”) associated with a user. The user data stored in the first server  110  may be changed or deleted at the requests. 
     According to various embodiments, the first server  110  may migrate the stored user information to the second server  120  through the relay server  130  based on the internal or external policy. In this case, the service provided to the user terminal  150  through the first server  110  may be continuously provided through the second server  120 . According to an embodiment, when the migration of the user data to the second server  120  is completed, the first server  110  may delete the stored user data. 
     According to various embodiments, the first server  110  may be a server positioned in a region different from the region of the second server  120 . For the efficiency of a service, the first server  110  may migrate the user data to the second server  120 . 
     The second server (target server)  120  may receive and store user data stored in the first server  110  via the relay server  130 . For example, the second server  120  may be a server positioned in a region different from the region of the first server  110 . In various embodiments, after the user data is migrated, the second server  120  may provide a service according to the request of the user terminal  150 . 
     The relay server (or migration server)  130  may receive the user data from the first server  110  to transmit the user data to the second server  120 . 
     According to various embodiments, while the user data is migrated, the relay server  130  may request the authentication server  140  to block the service provision to the user terminal  150  corresponding to the user data being migrated. When a data migration task is completed, the relay server  130  may request the authentication server  140  to resume the service being blocked. In this way, data loss occurring in the procedure of migrating user data may be prevented. 
     According to various embodiments of the disclosure, the authentication server  140  may receive a service request (e.g., data load/update/deletion request or the like) from the user terminal  150  to transmit the service request to a server (e.g., the first server  110  or the second server  120 ) storing the user data. For example, before the user data is migrated, the authentication server  140  may transmit the service request of the user terminal  150  to the first server  110 . After the user data is migrated from the first server  110  to the second server  120 , the authentication server  140  may transmit the service request of the user terminal  150  to the second server  120 . 
     In  FIG. 1 , an embodiment of the disclosure is exemplified as the single user terminal  150  is connected to the authentication server  140 . However, the disclosure is not limited thereto. For example, various electronic devices of a plurality of users (e.g., user ‘A’, user ‘B’, user ‘C’ . . . ) may be connected to the authentication server  140  by wire or wirelessly. Furthermore, various electronic devices (e.g., a first smartphone, a second smartphone, a tablet PC, a laptop PC, or the like registered with the same account) registered with the account of the same user may be connected to the authentication server  140 . 
     According to various embodiments, the authentication server  140  may block or resume the service request of the user terminal  150  at the request of the relay server  130 . For example, when the user data is migrated from the first server  110  to the second server  120 , the authentication server  140  may block the service request of the user terminal  150  to the first server  110 . When the migration of the user data from the first server  110  to the second server  120  is completed, the authentication server  140  may transmit the service request of the user terminal  150  to the second server  120 . 
     According to various embodiments of the disclosure, the user terminal  150  may be a terminal used by a user. The user terminal  150  may transmit a service request (e.g., data load/update/deletion request or the like) to the authentication server  140 . 
     According to various embodiments, the user terminal  150  may be a plurality of electronic devices used by a plurality of users (e.g., user ‘A’, user ‘B’, user ‘C’ . . . ). Alternatively, the user terminal  150  may be a plurality of electronic devices registered with the account of the same user. For example, the user terminal  150  may be a smartphone, a tablet PC, a laptop PC, or the like, which is registered with the account of the user ‘A’. 
     According to various embodiments, while the user data is migrated, when the user terminal  150  transmits a service request to the authentication server  140 , the user terminal  150  may receive the specified error code from the authentication server  140 . The user terminal  150  may again attempt to transmit the service request in the background method, after a specified time or may notify a user that it is impossible to use the corresponding service temporarily (e.g., a pop-up window). 
     According to various embodiments, a server device may include a memory, a communication interface, and a processor. The processor may be configured to transmit a service blocking request for a specified user, to an authentication server processing a request of a user terminal, to receive user data for the user from a first server, to transmit the user data to a second server, and to notify the authentication server that the transmission is completed, when the transmission of the user data is completed. 
     According to various embodiments, the processor may transmit the service blocking request when receiving a start signal for migration of the user data from the first server. The start signal may include account information about the user or device information about the user terminal associated with the user. 
     According to various embodiments, the service blocking request may include account information about the user or device information about the user terminal associated with the user. 
     According to various embodiments, the processor may be configured to transmit a request signal for the user data to the first server. The processor may be configured to transmit the request signal when receiving a response signal for the service blocking request from the authentication device. 
     According to various embodiments, the processor may be configured to receive verification data for the transmitted user data from the second server and to transmit received verification data to the first server. 
     According to various embodiments, the processor may be configured to transmit connection information about the second server to the authentication server when the transmission of the user data is completed. 
     According to various embodiments, the processor may be configured to request the authentication server to transmit a service request, which occurs in the user terminal associated with the user, to the second server when the transmission of the user data is completed. 
     According to various embodiments, a data transmitting system may include a user terminal, a first server storing user data for a user, a second server in which the user data is migrated and stored, a relay server relaying migration of the user data between the first server and the second server, and an authentication server transmitting a service request occurring in the user terminal, to the first server or the second server. The relay server may transmit a service blocking request for a specified user to the authentication server. The relay server may receive the user data for the user from the first server. The relay server may transmit the user data to the second server, and the relay server may notify the authentication server that the transmission is completed, when the transmission of the user data is completed. 
       FIG. 2  is a flowchart illustrating an operation of a relay server, according to various embodiments. 
     Referring to  FIG. 2 , in operation  210 , the relay server  130  may transmit a service blocking request for the user terminal  150  (hereinafter referred to as a “target user terminal”) corresponding to the user data to be migrated (or being migrated), to the authentication server  140 . The service blocking request may be a signal that makes it possible to block the request when the target user terminal requests the first server  110  to update or delete the user data stored in the first server  110 . 
     For example, when the data of the user ‘A’ is to be migrated (or is being migrated) from the first server  110  to the second server  120 , the relay server  130  may transmit the service blocking request for the target user terminal registered with the account of the user ‘A’, to the authentication server  140 . The authentication server  140  may block the request in response to the received service blocking request, when the target user terminal registered with the account of the user ‘A’ makes a request for changing or deleting the user data stored in the first server  110 . 
     In operation  220 , the relay server  130  may receive user data (hereinafter referred to as “target user data”) for the blocked user, from the first server  110 . In an embodiment, the relay server  130  may receive a response signal to the service blocking request, from the authentication server  140 . The response signal may be a signal indicating that the authentication server  140  completes the block to the target user terminal. When receiving the response signal (e.g., receiving a blocking complete message from the authentication server  140 ), the relay server  130  may transmit a request signal for migrating user data, to the first server  110 . The first server  110  may transmit target user data to the relay server  130  in response to the request signal. 
     In operation  230 , the relay server  130  may transmit the received target user data to the second server  120 . The second server  120  may store the received target user data. According to various embodiments, the relay server  130  may receive verification data associated with the target user data from the second server  120 . The relay server  130  may transmit the result of receiving the verification data to the first server  110 . 
     In operation  240 , the relay server  130  may notify the authentication server  140  of the migration completion of the target user data. When the migration of the target user data is completed, the authentication server  140  may transmit the service request of the target user terminal to the second server  120 . For example, the authentication server  140  may transmit a request that makes it possible to update or delete the stored user data to the second server  120 . 
     According to various embodiments, a data transmitting method performed by a server device may include transmitting a service blocking request for a specified user, to an authentication server processing a request of a user terminal, receiving user data for the user from a first server, transmitting the user data to a second server, and notifying the authentication server that the transmission is completed, when the transmission of the user data is completed. 
     According to various embodiments, the transmitting of the service blocking request may include receiving a start signal for migration of the user data from the first server. The receiving of the start signal may include receiving account information about the user or device information about a user terminal associated with the user. 
     According to various embodiments, the transmitting of the service blocking request may include transmitting account information about the user or device information about the user terminal associated with the user to the authentication server. 
     According to various embodiments, the receiving of the user data may include transmitting a request signal for the user data to the first server. The transmitting of the request signal may include transmitting the request signal when receiving a response signal for the service blocking request from the authentication device. 
     According to various embodiments, the data transmitting method may further include receiving verification data for the transmitted user data from the second server and transmitting received verification data to the first server. 
     According to various embodiments, the notifying of the authentication server that the transmission is completed may include transmitting connection information about the second server to the authentication server. 
     According to various embodiments, the notifying of the authentication server that the transmission is completed may include requesting the authentication server to transmit a service request, which occurs in the user terminal associated with the user, to the second server. 
       FIG. 3  is a flowchart illustrating an operation of an authentication server, according to various embodiments. 
     Referring to  FIG. 3 , in operation  310 , the authentication server  140  may receive a service blocking request for a target user terminal, from the relay server  130 . The service blocking request may be a signal that makes it possible to block the request when the target user terminal requests the first server  110  to update or delete the user data stored in the first server  110 . 
     In operation  320 , the authentication server  140  may block the service request of the target user terminal. For example, the authentication server  140  may block the corresponding request when the target user terminal requests the first server  110  to update or delete the user data stored in the first server  110 . 
     According to various embodiments, when receiving a request for changing/deleting user data from a target user terminal, the authentication server  140  may transmit a specified error code indicating that user data is being migrated, to the target user terminal. When receiving the error code, the target user terminal may again transmit the request after a specified time or may output a user notification (e.g., a pop-up window). The additional information about the user notification may be provided through  FIG. 7 . 
     According to an embodiment, when a plurality of target user terminals registered with the account of a user are present, the authentication server  140  may block the service for all of the plurality of target user terminals. 
     According to an embodiment, when the target user terminal makes a request for the service that loads the stored data without changing or deleting the user data, the authentication server  140  may allow access to the user data stored in the first server  110 . 
     In operation  330 , the authentication server  140  may receive the migration complete message of the target user data from the relay server  130 . In various embodiments, the migration complete message may include connection information (e.g., network information, identification information, or the like) about a server (e.g., the second server  120 ) in which the target user data is migrated. 
     In operation  340 , the authentication server  140  may resume the service request of the target user terminal, when receiving the migration complete message. The authentication server  140  may transmit the service request to a server (e.g., the second server  120 ), in which the target user data is migrated and stored. 
     The authentication server  140  may continuously block the target user terminal from accessing the first server  110  that provides a service before data is migrated. The target user terminal may receive the same service through the second server  120 . 
       FIG. 4  is a signal flowchart illustrating a procedure of migrating target user data, according to various embodiments. In  FIG. 4 , an embodiment is exemplified as the data of a single user USER  1  is migrated. However, embodiments of the disclosure are not limited thereto. 
     Referring to  FIG. 4 , in operation  410 , the relay server  130  may transmit a service blocking request for a target user terminal registered with the account of the USER  1 , to the authentication server  140 . The service blocking request may be a signal that makes it possible to block the request when the target user terminal requests the first server  110  to update or delete the user data stored in the first server  110 . For example, the service blocking request may include account information of the USER  1  or device information of the target user terminal. 
     According to various embodiments, the relay server  130  may transmit the service blocking request in response to the start signal (not illustrated) received from the first server  110 . The start signal may include account information of a user or device information (e.g., device identification information) of the user terminal  150 . 
     In operation  412 , the authentication server  140  may block at least part of requests of the target user terminal associated with the target user data stored in the first server  110 . 
     For example, the user executes an app in the target user terminal and then the executed app generates a request for changing user data stored in the first server  110 , the authentication server  140  may transmit a specified error code indicating that the requested user data is being migrated, to the target user terminal. The target user terminal may notify the user that it is impossible to temporarily perform the request of the app being executed, through a user notification (e.g., a pop-up window) based on the received error code. 
     According to various embodiments, in operation  415 , the authentication server  140  may notify the relay server  130  that the block to the target user terminal is completed. 
     According to various embodiments, in operation  420 , the relay server  130  may transmit a signal for making a request for the target user data to the first server  110 , when the service block to the target user terminal is completed. 
     In operation  425 , the first server  110  may transmit target user data to the relay server  130 . The first server  110  may transmit all of pieces of target user data or may sequentially transmit pieces of target user data. 
     In operation  430 , the relay server  130  may transmit the received target user data to the second server  120 . The relay server  130  may transmit all of pieces of received target user data or may sequentially transmit pieces of received target user data. 
     In operation  432 , the second server  120  may store the received target user data. 
     According to various embodiments, in operation  435 , the second server  120  may transmit an acknowledgment message to the relay server  130 , when the storing of the target user data is completed. In an embodiment, the acknowledgment message may include verification data for verifying the storing of the target user data. 
     In operation  440 , the relay server  130  may notify the authentication server  140  of the migration completion of the target user data. The relay server  130  may provide the authentication server  140  with information (e.g., network information, identification information, or the like) about the second server  120  in which the target user data is migrated. 
     In operation  442 , the authentication server  140  may switch the target of the service request of the target user terminal to the second server  120  in which the target user data is migrated and stored. In an embodiment, the authentication server  140  may transmit the specified code indicating that the migration of the target user data is completed, to the target user terminal. 
     According to various embodiments, in operation  445 , the authentication server  140  may transmit an acknowledgment message to the relay server  130 . 
     According to various embodiments, when the authentication server  140  receives a service request from the target user terminal, in operation  450 , the authentication server  140  may transmit the service request to the second server  120 . 
       FIG. 5  is an exemplification diagram for describing migration of user data, according to various embodiments.  FIG. 5  is, but is not limited to, an example. 
     Referring to  FIG. 5 , the data transmitting system  101  may include the first server (or origin server)  110 , the second server (or target server)  120 , the relay server  130 , the authentication server  140 , and a target user terminal  151 . 
     The first server  110  may store target user data  111 . In a state before the target user data  111  is migrated to the second server  120 , when the service request of the target user terminal  151  occurs, the authentication server  140  may transmit the service request to the first server  110 . 
     For example, the target user terminal  151  may transmit a request signal for updating or deleting third data Data # 3  of the target user data  111 , to the authentication server  140 . The authentication server  140  may transmit the request signal to the first server  110 . The first server  110  may update or delete the third data Data # 3  depending on the request signal. The first server  110  may transmit the processed result to the target user terminal  151  through the authentication server  140 . 
     According to various embodiments, when the first server  110  migrates the target user data  111  to the second server  120 , the first server  110  may transmit a start signal (not illustrated) to the relay server  130 . The start signal may include the account information of the target user and the device information (e.g., device identification information) of the target user terminal  151 . 
     In operation  510 , the relay server  130  may transmit the service blocking request for the target user terminal  151  corresponding to the target user data  111 , to the authentication server  140 . For example, the service blocking request may include the account information of the target user, the device information of the target user terminal  151 , or the like. 
     In operation  512 , the authentication server  140  may block a request for allowing the target user terminal  151  to access the target user data of the first server  110 , in response to the service blocking request. For example, the authentication server  140  may transmit a specified error code indicating that user data is being migrated, to the target user terminal  151 . 
     In operation  525 , the relay server  130  may receive the target user data  111  from the first server  110 . 
     In operation  530 , the relay server  130  may transmit the received target user data  111  to the second server  120 . The second server  120  may store copy data  121  of the target user data  111 . 
     In operation  540 , the relay server  130  may notify the authentication server  140  of the migration completion of the target user data. The relay server  130  may provide the authentication server  140  with information (e.g., network information, identification information, or the like) about the second server  120 . 
     In operation  550 , the authentication server  140  may transmit the service request of the target user terminal  151  to the second server  120 . When the service request that has previously occurred in the running app is present, the target user terminal  151  may attempt a service request again in the background method. 
       FIG. 6  illustrates a method of grouping user data and then transmitting the grouped user data, according to various embodiments. However,  FIG. 6  is exemplary, and the disclosure is not limited thereto. 
     Referring to  FIG. 6 , the first server  110  may classify and group the stored user data depending on an attribute (e.g., recent access frequency, data change frequency, data capacity, or the like). The first server  110  may migrate user data to the second server  120  in different methods depending on the attribute of each group. 
     For example, the first server  110  may group the stored user data into first to third groups  610  to  630  depending on the recent access frequency and may store the grouped result. The first server  110  may continuously maintain the first group  610 , in which the recent access frequency is relatively high, in the first server  110 . The first server  110  may transmit the second group  620 , in which the recent access frequency is relatively low, to the second server  120  by using the relay server  130 . The first server  110  may directly transmit the third group  630 , in which recent access does not occur, to the second server  120  in the server shut-down method. Alternatively, the first server  110  may transmit the first group  610  to the second server  120  by using the relay server  130  at a first time (e.g., 4 AM˜6 AM). The second group  620  may be transmitted to the second server  120 , using the relay server  130  at a second time (e.g., 12 AM˜2 AM). The third group  630  may be transmitted to the second server  120 , using the relay server  130  at a third time (e.g., 8 AM˜10 AM). 
     The authentication server  140  may receive information about migration of user data from the first server  110  or the relay server  130 . When the service request of the user terminal  150  occurs, the authentication server  140  may transmit the service request to a server (e.g., the first server  110  or the second server  120 ) storing user data. 
       FIG. 7  is a UI exemplification diagram of a user terminal, according to various embodiments. However,  FIG. 7  is exemplary, and the disclosure is not limited thereto. 
     Referring to  FIG. 7 , the authentication server  140  may store state information of user data corresponding to each of user terminals  151  and  152 , in an internal storage device  141 . The state information may include information about a server storing the user data, information about whether the user data is being migrated, or the like. 
     The authentication server  140  may process the service request from the user terminals  151  and  152 , based on the stored state information. 
     For example, when receiving the service request from the user terminal  151 , the authentication server  140  may identify state information  141   a  corresponding to the user terminal  151 . The authentication server  140  may identify that the user data corresponding to the user terminal  151  is in a migration state and may transmit the specified error code to the target user terminal  151 . When receiving the error code, the user terminal  151  may again transmit the service request after a specified time or may display a user notification  151   a.    
     For another example, when receiving the service request from the user terminal  152 , the authentication server  140  may identify a server (server ‘A’) storing the user data corresponding to the user terminal  152 . The authentication server  140  may transmit the received service request to the server ‘A’. The user terminal  152  may output the progress through a user notification  152   a.    
       FIG. 8  illustrates a block diagram of a user terminal, according to various embodiments. 
     A user terminal  801  may include, for example, all or a part of the electronic device  801  illustrated in  FIG. 8 . The electronic device  801  may include one or more processors (e.g., an application processor (AP))  810 , a communication module  820 , a subscriber identification module  824 , a memory  830 , a sensor module  840 , an input device  850 , a display  860 , an interface  870 , an audio module  880 , a camera module  891 , a power management module  895 , a battery  896 , an indicator  897 , and a motor  898 . The processor  810  may drive, for example, an operating system (OS) or an application to control a plurality of hardware or software components connected to the processor  810  and may process and compute a variety of data. For example, the processor  810  may be implemented with a System on Chip (SoC). According to an embodiment, the processor  810  may further include a graphic processing unit (GPU) and/or an image signal processor. The processor  810  may include at least a part (e.g., a cellular module  821 ) of components illustrated in  FIG. 8 . The processor  810  may load a command or data, which is received from at least one of other components (e.g., a nonvolatile memory), into a volatile memory and process the loaded instruction or data. The processor  810  may store result data in the nonvolatile memory. 
     The communication module  820  may include the cellular module  821 , a Wi-Fi module  823 , a Bluetooth (BT) module  825 , a GNSS module  827 , and a near field communication (NFC) module  828 . The cellular module  821  may provide, for example, voice communication, video communication, a character service, an Internet service, or the like over a communication network. According to an embodiment, the cellular module  821  may perform discrimination and authentication of the user terminal  801  within a communication network by using the subscriber identification module (e.g., a SIM card)  824 . According to an embodiment, the cellular module  821  may perform at least a portion of functions that the processor  810  provides. According to an embodiment, the cellular module  821  may include a communication processor (CP). According to an embodiment, at least a part (e.g., two or more) of the cellular module  821 , the Wi-Fi module  823 , the BT module  825 , the GNSS module  827 , or the NFC module  828  may be included within one Integrated Circuit (IC) or an IC package. According to another embodiment, at least one of the cellular module  821 , the Wi-Fi module  823 , the BT module  825 , the GNSS module  827 , or the NFC module  828  may transmit and receive an RF signal through a separate RF module. The subscriber identification module  824  may include, for example, a card and/or embedded SIM that includes a subscriber identification module and may include unique identify information (e.g., integrated circuit card identifier (ICCID)) or subscriber information (e.g., international mobile subscriber identity (IMSI)). 
     The memory  830  may include an internal memory  832  or an external memory  834 . For example, the internal memory  832  may include at least one of a volatile memory (e.g., a dynamic random access memory (DRAM), a static RAM (SRAM), a synchronous DRAM (SDRAM), or the like), a nonvolatile memory (e.g., a one-time programmable read only memory (OTPROM), a programmable ROM (PROM), an erasable and programmable ROM (EPROM), an electrically erasable and programmable ROM (EEPROM), a mask ROM, a flash ROM, a flash memory, a hard drive, or a solid state drive (SSD). The external memory  834  may include a flash drive such as compact flash (CF), secure digital (SD), micro secure digital (Micro-SD), mini secure digital (Mini-SD), extreme digital (xD), a multimedia card (MMC), a memory stick, or the like. The external memory  834  may be operatively and/or physically connected to the user terminal  801  through various interfaces. 
     The sensor module  840  may measure, for example, a physical quantity or may detect an operation state of the user terminal  801 . The sensor module  840  may convert the measured or detected information to an electric signal. For example, the sensor module  840  may include at least one of a gesture sensor  840 A, a gyro sensor  840 B, a barometric pressure sensor  840 C, a magnetic sensor  840 D, an acceleration sensor  840 E, a grip sensor  840 F, the proximity sensor  840 G, a color sensor  840 H (e.g., red, green, blue (RGB) sensor), a biometric sensor  840 I, a temperature/humidity sensor  840 J, an illuminance sensor  840 K, or an UV sensor  840 M. Although not illustrated, additionally or alternatively, the sensor module  840  may further include, for example, an E-nose sensor, an electromyography (EMG) sensor, an electroencephalogram (EEG) sensor, an electrocardiogram (ECG) sensor, an infrared (IR) sensor, an iris sensor, and/or a fingerprint sensor. The sensor module  840  may further include a control circuit for controlling at least one or more sensors included therein. According to an embodiment, the user terminal  801  may further include a processor that is a part of the processor  810  or independent of the processor  810  and is configured to control the sensor module  840 . The processor may control the sensor module  840  while the processor  810  remains at a sleep state. 
     The input device  850  may include, for example, a touch panel  852 , a (digital) pen sensor  854 , a key  856 , or an ultrasonic input unit  858 . For example, the touch panel  852  may use at least one of capacitive, resistive, infrared and ultrasonic detecting methods. Also, the touch panel  852  may further include a control circuit. The touch panel  852  may further include a tactile layer to provide a tactile reaction to a user. The (digital) pen sensor  854  may be, for example, a part of a touch panel or may include an additional sheet for recognition. The key  856  may include, for example, a physical button, an optical key, or a keypad. The ultrasonic input device  858  may detect (or sense) an ultrasonic signal, which is generated from an input device, through a microphone (e.g., a microphone  888 ) and may check data corresponding to the detected ultrasonic signal. 
     The display  860  may include a panel  862 , a hologram device  864 , a projector  866 , and/or a control circuit for controlling the panel  862 , the hologram device  864 , or the projector  866 . The panel  862  may be implemented, for example, to be flexible, transparent or wearable. The panel  862  and the touch panel  852  may be integrated into a single module. According to an embodiment, the panel  862  may include a pressure sensor (or force sensor) that measures the intensity of touch pressure by a user. The pressure sensor may be implemented integrally with the touch panel  852 , or may be implemented as at least one sensor separately from the touch panel  852 . The hologram device  864  may display a stereoscopic image in a space using a light interference phenomenon. The projector  866  may project light onto a screen so as to display an image. For example, the screen may be arranged in the inside or the outside of the user terminal  801 . The interface  870  may include, for example, a high-definition multimedia interface (HDMI)  872 , a universal serial bus (USB)  874 , an optical interface  876 , or a D-subminiature (D-sub)  878 . Additionally or alternatively, the interface  870  may include, for example, a mobile high definition link (MHL) interface, a SD card/multi-media card (MMC) interface, or an infrared data association (IrDA) standard interface. 
     The audio module  880  may convert a sound and an electric signal in dual directions. The audio module  880  may process, for example, sound information that is input or output through a speaker  882 , a receiver  884 , an earphone  886 , or the microphone  888 . For example, the camera module  891  may shoot a still image or a video. According to an embodiment, the camera module  891  may include at least one or more image sensors (e.g., a front sensor or a rear sensor), a lens, an image signal processor (ISP), or a flash (e.g., an LED or a xenon lamp). The power management module  895  may manage, for example, power of the user terminal  801 . According to an embodiment, a power management integrated circuit (PMIC), a charger IC, or a battery or fuel gauge may be included in the power management module  895 . The PMIC may have a wired charging method and/or a wireless charging method. The wireless charging method may include, for example, a magnetic resonance method, a magnetic induction method or an electromagnetic method and may further include an additional circuit, for example, a coil loop, a resonant circuit, a rectifier, or the like. The battery gauge may measure, for example, a remaining capacity of the battery  896  and a voltage, current or temperature thereof while the battery is charged. The battery  896  may include, for example, a rechargeable battery and/or a solar battery. 
     The indicator  897  may display a specific state of the user terminal  801  or a part thereof (e.g., the processor  810 ), such as a booting state, a message state, a charging state, and the like. The motor  898  may convert an electrical signal into a mechanical vibration and may generate the following effects: vibration, haptic, and the like. The user terminal  801  may include a processing device (e.g., a GPU) for supporting a mobile TV. The processing device for supporting the mobile TV may process media data according to the standards of digital multimedia broadcasting (DMB), digital video broadcasting (DVB), MediaFLO™, or the like. Each of the above-mentioned components of the electronic device according to various embodiments of the disclosure may be configured with one or more components, and the names of the components may be changed according to the type of the user terminal. In various embodiments, some components of the electronic device (e.g., the user terminal  801 ) may be omitted or other additional components may be added. Furthermore, some of the components of the electronic device may be combined with each other so as to form one entity, so that the functions of the components may be performed in the same manner as before the combination. 
     The term “module” used in this disclosure may include a unit composed of hardware, software and firmware and may be interchangeably used with the terms “unit”, “logic”, “logical block”, “part” and “circuit”. The “module” may be an integrated part or may be a minimum unit for performing one or more functions or a part thereof. The “module” may be implemented mechanically or electronically and may include at least one of an application-specific IC (ASIC) chip, a field-programmable gate array (FPGA), and a programmable-logic device for performing some operations, which are known or will be developed. At least a part of an apparatus (e.g., modules or functions thereof) or a method (e.g., operations) according to various embodiments may be, for example, implemented by instructions stored in computer-readable storage media in the form of a program module. The instruction, when executed by a processor, may cause the processor to perform a function corresponding to the instruction. A computer-readable recording medium may include a hard disk, a floppy disk, a magnetic media (e.g., a magnetic tape), an optical media (e.g., a compact disc read only memory (CD-ROM) and a digital versatile disc (DVD), a magneto-optical media (e.g., a floptical disk)), and an internal memory. Also, the one or more instructions may contain a code made by a compiler or a code executable by an interpreter. A module or a program module according to various embodiments may include at least one of the above components, or a part of the above components may be omitted, or other components may be further included. Operations performed by a module, a program module, or other components according to various embodiments may be executed sequentially, in parallel, repeatedly, or in a heuristic method or some operations may be executed in different sequences or may be omitted. Alternatively, other operations may be added.