JP6425257B1 - System migration method, migration system and program to reduce migration burden and risk accompanying parallel operation of new and old systems - Google Patents

Abstract

[Objective] To reduce the transition burden and risk involved in parallel operation of new and old systems. In a three-tier system having a Web server, an AP server and a DB server, the Web server is the current Web server 10 and the new Web server 11, the AP server is the current AP server 20 and the new AP server 21, and the DB server , And the current DB server 30. Then, at the transition stage from the current system to the new system, the current Web server 10 may use only the current system, or use only the new system, for each customer and / or each user of the customer. Display either the new or old usage setting screen to select or to use. Further, the current DB server 30 stores a combined selection table for setting whether or not to switch the current system and the new system for each customer and / or user of the customer. [Selected figure] Figure 1

Description

  The present invention relates to a system migration method involved in parallel operation of new and old systems.

  Conventionally, when transitioning from a new system to an old system, there is known a method of completing the transition without stopping the service.

  For example, Patent Document 1 discloses an information management system or the like for migrating an existing system that manages data to be updated sequentially to a new system. In this system, the current system that has received a transaction request message from the in-store terminal executes transaction processing and transmits a transaction result message. In this case, a data header is added to update the customer management information of the next system. Then, the control unit of the next system that has received the transaction result message updates the customer management information. When a transaction is made at an ATM terminal or a net transaction server, the current system sends a transaction linkage message to the back end hub. Then, the next system which has received the update request message from the back end hub executes update processing of the customer management information. Further, in the individual transfer process, the next system specifies the transfer status of the transfer source and the transfer destination, and updates the account information and the customer management information according to the transfer status.

  Further, Patent Document 2 discloses an access control program and the like for updating software accompanied by a change in the configuration of a database without stopping a service by software. The access control program is operable on a plurality of information processing apparatuses connected to the first database and the second database, and is executed along with the update of the first software operating on the plurality of information processing apparatuses. During the process of data transfer from the first database to the second database, an access request from the first software to the database is received, information on the version of the first software included in the access request, and data from the first database to the second database Based on the information on the transition status, the computer is made to execute processing of determining a database to which the access request is to be transmitted to the first database or the second database.

JP, 2013-250629, A JP, 2016-099709, A

  System migration involves migration burdens and risks not only on the system provider side but also on the customer side. In particular, in a large-scale system with tens of thousands of users and hundreds of screens, when updating the system, it is unclear whether all users can establish a switchable system at the same time. Need to be In addition, it is desirable to be able to temporarily return to the old system if a failure occurs during migration. However, in the conventional system migration method, the migration from the old system to the new system is one-way, and both the new system and the old system are operated concurrently during the transition period, and it is not possible to go back and forth at any time.

  Therefore, in the present invention, in view of the above problems, it is an object of the present invention to reduce the transition burden and risk involved in parallel operation of the new and old systems.

  In order to solve the above-mentioned subject, the present invention provides the following solutions.

(1) A method of migrating a system from a current system to a new system in a 3-tier system having a web server, an AP server and a DB server, wherein the web server is a current web server and a new web server, and the AP server is a current AP server and new AP server, the DB server is a current DB server, and in the transition stage from the current system to the new system, the current Web server is for each customer and / or for each user of the customer, Displaying a new / old usage setting screen for setting whether to use only the current Web server, to use only the new Web server, or to select and use one of both Web servers. To feature

(2) In the configuration of (1), the current DB server stores a combined selection table for setting whether or not to switch the current system and the new system for each of the customer and / or the user of the customer. It is characterized by including.

(3) In the configuration of the above (1) or (2), the new AP server converts the data input / selected in the new screen displayed by the new Web server into a format that can be processed by the current AP server Data conversion means are provided.

(4) In the above configurations (1) to (3), the current Web server displays a new / old selection screen after login to the current system, and when the user selects a new screen, the customer ID And a new login screen for logging in to the new system by taking over the user ID.

(5) In the configurations from (1) to (4), the setting is made on the new and old usage setting screen to deactivate the selection of the current system on the new and old selection screen after the migration is completed.

(6) In the configuration of (5), the selection of the current system is restored according to the request of the customer even after the selection of the current system is deactivated.

(7) A migration system in a three-tier system having a web server, an AP server and a DB server, wherein the web server is a current web server and a new web server, the AP server is a current AP server and a new AP server, The DB server is the current DB server,
During the transition from the current system to the new system, the current web server may use only the current web server or only the new web server for each customer and / or each user of the customer. It is characterized in that it comprises new and old usage setting means for setting which one of both Web servers is to be selected and used.

(8) A program for migrating from a current system to a new system in a 3-tier system having a web server, an AP server and a DB server, wherein the web server is a current web server and a new web server, and the AP server is The current AP server and the new AP server, the DB server is a current DB server, and in the transition stage from the current system to the new system, the current Web server is for each customer and / or for each user of the customer The computer displays a new / old usage setting screen for setting whether to use only the current Web server, to use only the new Web server, or to select and use one of both Web servers. It is characterized by having it run.

  According to the present invention, it is possible to reduce the transition burden and risk involved in parallel operation of new and old systems.

It is a figure showing an outline of transition transition of a system concerning an embodiment of the present invention. It is a figure which shows the detailed transfer step in the transfer period of phase 1. FIG. It is a figure which shows the function structure of each server in the transfer step of phase 1. FIG. It is a figure which shows an example of the combined use selection table stored in user information DB. It is a figure which shows the control flow of the screen transition in the present web server. It is a figure which shows the screen transition of new and old system combined use. It is a following figure showing screen transition of new and old system combined use.

  Hereinafter, with reference to the drawings, modes (hereinafter, embodiments) for carrying out the present invention will be described in detail. In the following drawings, the same elements are denoted by the same reference numerals or symbols throughout the description of the embodiments.

(Transition policy)
The migration system (hereinafter referred to as the present system) targeted by the present invention is a so-called "3-tier system", and it is a presentation layer (user interface layer) and a data access layer (database layer). And, in between, there are three layers called business logic layer (application layer). In this system, the presentation layer is implemented on a web server (web server), the business logic layer is implemented on an AP server (application server), and the data access layer is implemented on a DB server (database server). Business Logic (Business Logic) expresses various entities (products, customers, inventory, etc.) handled in specific operations in business software, and also their relationship, processing method, flow of operations, etc. Is a program code that implements application-specific processing and rules.

  The transition period of this system can be roughly divided into Phase 1 which is a transition period in which new and old systems can be used in parallel (parallel operation), and phase 2 which is a transition period in which only new systems are used. Hereinafter, in the present specification, only the transition period of phase 1 is covered. In Phase 1, there will be many developments that have a large impact on customers, such as full screen renovations and the introduction of new portals, as described below. The old system can be used in combination. Although all customers already use only the new system after the completion of phase 1, the purpose of phase 2 is to transfer the processing inside the system from the old system to the new system.

  Although details will be described later, the new system web server sets the current web server only, the new web server only, and either of both web servers for each customer and / or customer user Display By making it possible to use the new and old systems together, the transition burden and risk on the customer side are reduced, and the contingency plan (emergency contingency plan) at the time of new system release, for example, It is simplified, for example, by

  Also, in phase 1, the database (DB) is shared between the new and old systems, and data migration from the old system to the new system, such as masters and transaction data, does not occur. Do only). During the phase 1 transition period, first, the functions will be enhanced centering on the Web server which is the user interface layer, and the AP server and the DB server will be enhanced in phase 2.

  FIG. 1 shows an outline of transition transition of a system according to an embodiment of the present invention. As illustrated, before migration, the customer's user accesses the current Web server 10, and inputs / selects data from the current screen (business screen) generated by the current Web server 10, and based on the data, The current AP server 20 executes the current business logic (hereinafter, referred to as “current BL”), stores the processing result in the current DB of the current DB server 30, and displays the processing result on the current screen.

  Next, in the phase 1 transition period, as described above, instead of migrating all customers at once, first migrate some customers (such as close customers) who can quickly migrate to the new system. Establish a "partial customer migration phase" to make the old system and the new system compatible. Hereinafter, such a customer will be referred to as "a migratable customer". At the customer transition stage, customers who are not ready for transition (called “non-migrated customers”) will be asked to continue using the old system, and as soon as their environment is ready, they will become migratable customers. Can.

  When the migratable customer accesses the new Web server 11, a new screen is displayed in which the current screen is renewed. From the new screen, processing is delivered to the new AP server 21, and the new AP server 21 does not immediately implement the new business logic (new BL), but all the functions of the current BL (transition) through the bridge. Make available the function improvement from before). Here, the bridge, which will be described in detail later, has a function of converting the contents of data possessed by the new system into a format that can be executed by the old system, and linking data with the old system.

  The current AP server 20 that has received the converted data from the new AP server 21 executes the current BL. Here, the current BL in the transition stage may be upgraded from the current BL before the transition. Also, the current AP server 20 exchanges data with the current DB server 30, but has a function to distinguish whether the processing result notification destination is the current Web server 10 or the new AP server 21. .

  Then, when all the customers use the new Web server 11 (all customers have been migrated), the current Web server 10 is stopped, and the transition period of phase 1 is ended. Thereafter, the migration toward phase 2 is started, and eventually all servers will be replaced with only new servers.

(Phase 1 transition detailed step)
FIG. 2 shows stages (steps 0 to 4) in which the detailed transition step in the transition period of phase 1 is further subdivided. The following will be described in order.

  Step 0 is a stage in which the development side carries out function confirmation by a confirmation customer (such as a training store user) in a production environment.

  Step 1 is the stage of migrating close customers at several key locations (target customers are selected mainly for customers using new functions).

Step 2 is a stage in which all customers are divided into several groups, and each group is sequentially transferred.
In steps 1 and 2, a new / old selection screen is displayed for selecting which of old and new is to be used for a migratable customer (when new screen is selected, the customer ID / user ID is taken over and transition is made to the login screen of the new environment). The migratable customer can access the current login screen at the same URL as the current. Also, since the URL of the new system is different from the current URL, it is possible to directly access it by registering it in the "favorites" menu.

Step 3 is a preparatory period for bases / customers who could not transition during the period of step 2. If time is required for authority approval of bases, etc., it is necessary to continue to use the current system at the customer's convenience. Period, etc. In step 3, the new environment can be accessed only by deactivating the login button to the current system. In addition, it is assumed that the old system selection button is revived by individual handling only for the customer who has made a request to the site. The process of restoring the button can be performed from the setting screen of the system operator.
In addition, the setting screen of the system operator is called “new and old usage setting screen”, and not only the spare period due to the convenience of the base / customer as in step 3 above, but also the convenience of the migrating system side, for example, as described above It is also used when you want to shift from some customers in stages instead of transferring all customers at once.

  Step 4 is the final step of phase 1 and stops the use of the current Web server 10 after all customers have been migrated. At this stage, when the URL of the current Web server 10 is accessed, the portal login page is automatically transitioned. This transition is realized by the redirect function. In addition, a portal login page is what becomes an entrance (entrance) which can access a plurality of business systems, and the details will be described later.

(Functional configuration)
FIG. 3 is a diagram showing the functional configuration of each server at the phase 1 transition stage. As illustrated, the migration of this system targets a three-tier system of current Web server 10, current AP server 20, current DB server 30, new Web server 11, new AP server 21, and new DB server 31, but Each server may be one or more than one.

  The new Web server 11 includes a customer terminal communication unit 101, a login control unit 102, and a new screen control unit 103. The current Web server 10 includes a customer terminal communication unit 101, a login control unit 102, a new and old selection screen control unit 111, An old screen control unit 112 and a new screen control unit 103A are provided.

  The customer terminal communication unit 101 controls communication with a customer's user terminal (not shown), and the login control unit 102 causes the user terminal to display a login screen for authenticating an authorized user. From the login screen, the user inputs a customer ID (company ID), a user ID, and a user password, and if it is verified that the user is an authorized user, the process proceeds to the subsequent processes. At this time, processing after login differs between the current Web server 10 and the new Web server 11.

  The new Web server 11 only causes the new screen control unit 103 to display a new screen, and delivers the data input and selected by the user to the new AP server 21. However, when the login is completed, the current Web server 10 once passes control to the new and old selection screen control means 111, and the new and old selection screen control means 111 allows the user to select which screen of the old and new systems to use. Display the new / old selection screen. When the user selects to use the new system, the new screen control means 103A displays the login screen of the new Web server 11, and when the login authentication of the user is completed again, the new screen is displayed. When the user selects to use the old system, the current screen control means 112 displays the current screen. The user inputs and selects data for performing work from the new screen or the current screen. The new screen transitions to a portal screen, and the user interface is renewed, so that the current screen can be used until the user gets used to the new screen.

  While the new / old selection screen (new / old selection means) is for the customer / user to select the usage mode of the new / old system, the system operator uses the new / old usage setting screen (new / old use setting means). Setting screen for setting the usage form of each customer / user, that is, only the old system can be used, only the new system can be used, and the new or old can be used. Means).

  Here, the new AP server 21 does not have a means (new BL execution means) for executing business logic like the current AP server 20, but instead has a new / old data conversion means 211 (bridge). The bridge converts the contents of data of the new system into a form that can be read (executed) by the old system, and performs the function of linking data to the old system.

Specifically, the bridge performs the following processing.
(1) A template for calling a function of the old system is used as an input parameter, and a part for calling the function of the old system is executed.
(2) Call the function of the old system based on the specified contents.
(3) The old system executes the function and converts the returned result into a form that can be read by the new system.

  That is, data input / selected from the new screen is passed to the bridge, and converted into a format that can be executed by the current BL execution unit 201 of the current AP server 20. Further, the bridge processes the result processed by the current BL execution unit 201 into a format that can be displayed on the new screen by the new screen control unit 103. On the other hand, the data input / selected from the current screen is transferred to the current BL execution means 201 of the current AP server 20 as it is, because conversion is not necessary. By the function of this bridge, a new BL execution means (not shown) may be implemented at the time of phase 2 transition, and the current BL execution means 201 is used until then.

  For specific examples of the login screen and the new / old selection screen, refer to FIGS. 6 and 7 described later. In the example of FIG. 6 and FIG. 7, overseas corporate Internet banking (referred to as overseas corporate IB or simply IB) is assumed as a business example. Although details are omitted, a new login screen, portal screen, new IB screen, and the like can be used by the touch panel type mobile terminal.

  The current DB server 30 includes a user information DB 301 storing contract information of customers and customer users, registration information, and the like, and various work DBs 302 storing data necessary for actual various work. The user information DB 301 stores a combined selection table in which it is set whether to permit the combination of the new and old systems for each customer or each user. The combined selection table will be described with reference to FIG. Note that the reason why the user information DB 301 is stored in the current DB server 30 is that access can be made from either the old or the new during migration.

  The new DB server 31 does not directly store data related to migration, but can store part of various business data when there is a possibility that the storage capacity of the current DB server 30 runs short. The storage capacity may be insufficient because it is assumed that the current function is upgraded along with the migration. That is, according to this migration system, not only migration of the system but also upgrading of the current function can be performed without expanding the capacity of the current DB server. Also, the new DB server 31 may store data about functions that can be newly made on a portal screen that is not in the current system. In addition, in Phase 2, a table to be transferred from the current DB server 30 to the new DB server 31 is also stored in part as the new DB server 31 is renewed. In general, a portal refers to the entrance where the user uses the Internet, or a place (web) that is always used as a base, but here a function for providing menu screens of a plurality of tasks. Means.

(User information DB)
FIG. 4 is a diagram showing an example of the combination selection table stored in the user information DB 301. As shown in FIG.
The user information DB 301 includes a combination selection table shown in addition to the user's contract information, registration information, etc. (not shown). The combined selection table is a table that includes a “switchability flag” that can specify either new or old system for each customer. The possibility of switching may be specified not only for each customer ID (company code) but also for each user ID in the customer. Note that instead of the switching availability flag, switching selection values such as “available only in old system”, “available only in new system”, and “available in combination with new and old system” may be used. The combination selection table is set by the new and old usage setting screen used by the system operator.

  By doing this, the customer or the user can use the new and old systems together during the transition period. Here, it is possible to turn on / off the new / old switching availability simply by changing the switching availability flag provided for each customer (or each user). That is, the customer or user can move back and forth between the old and new systems at any time. For example, if a customer who normally uses the old system uses the new system, uses the new system as training, or even if the customer has already migrated to the new system, the new system should fail Can temporarily return to the old system and continue work.

  In particular, in a large-scale system with many users and many screens, when updating the system, it is not clear whether all users can establish a switchable system at the same time. It can be provided. In addition, as a service provider / operator, even if there is a problem with the new system, it is possible to instantly switch to the old system, so there is less psychological burden when trying out the new system.

(Process flow of screen transition)
FIG. 5 is a diagram showing a control flow of screen transition in the current Web server 11. Since the contents already described below are included, they will be briefly described.

  First, in step S10, the current login screen is displayed, and in step S11, if it is possible to authenticate that there is an authorized user, the combination selection table described in FIG. 4 is read out (step S12).

  Next, in step S13, referring to the combined selection table, it is determined whether or not it is a combined use customer (or combined use user), and if it is a combined use customer (or combined use user), the new and old selection screen is displayed (Step S14). If it is determined in step S13 that the customer is not a combination-usable customer, the current screen is displayed (step S16).

  Then, in step S15, it is determined which of old and new has been selected, and when "old" is selected, the current screen is displayed (step S16). If "new" is selected, a new login screen is displayed (step S17). Next, in step S17A, if authentication on the new login screen is completed and it can be confirmed that the user is an authorized user, the process proceeds to step S18. However, if the authentication fails, the process returns to step S17 again to display a new login screen. However, it is needless to say that an error occurs when login fails a predetermined number of times, and the process is stopped.

  If "new" is selected, it is checked again whether or not the user is an authorized user, and when the authorized user completes login, a portal screen is displayed (step S18). In step S19, it is determined which task has been selected from the portal screen, and when a task of IB (Internet banking) is selected, a new IB screen is displayed (step S20). If a task other than the IB task is selected, the task screen (other system screen) is displayed (step S21).

(Screen transition)
FIG. 6 and FIG. 7 are diagrams showing screen transitions in combination with new and old systems. The new and old transition diagram of FIG. 6 summarizes the screen transitions in step 1 and step 2 shown in FIG. Further, the new and old screen transition diagram of FIG. 7 is a summary of the screen transition in step 3 shown in FIG.

  As shown in FIG. 6, in the case of a migration non-migrated customer, when the company ID (customer ID), user ID, and password are input from the current login screen 400 and the login button is pressed, the current IB screen 410 is displayed.

  In the case of a migratable customer, when the new URL is accessed, a new login screen 401 is directly displayed. On the other hand, when the current URL is accessed, the current login screen 400 is displayed. When login is completed on the current login screen 400, the new / old selection screen 500 is displayed once. The new and old selection screen 500 is a screen for selecting a screen (system) to be used, and it is possible to select whether to use a new screen (new system) or a current screen (old system). When “new” is selected on this screen, the company ID and the user ID are inherited, and a new login screen 401 is displayed. When "old" is selected on the new / old selection screen 500, a current IB screen 410 for Internet banking (IB), which is a business screen of the current system, is displayed. Note that it is possible to call another system from the current IB screen 410 before the transition.

  In addition, the new login screen 401 may include an authentication unit such as fingerprint authentication in order to support access from a touch panel type mobile terminal such as a tablet terminal. When authentication is completed by entering a company ID (customer ID), a user ID, and a password on the new login screen 401, a portal screen 600 is displayed. However, when the new login screen 401 is displayed from the new / old selection screen 500, the ID is taken over, and therefore, it is not necessary to input the ID again (the password needs to be input again).

  When the authentication on the new login screen 401 is normally completed, the portal screen 600 is displayed. Portal screen 600 is a screen serving as the entrance to other systems as well as Internet banking, and a single that enables login with the same ID and password without entering ID and password again to any system. Each system can be accessed by the sign-on method. When the internet banking (IB) is selected on the portal screen 600, the new IB screen 411 is displayed, and when another system is selected, the other system screen 700 is displayed.

  Now, let us explain the explanation of FIG. This figure is a screen transition diagram in step 3 (preliminary period) described in FIG. The basic flow is the same as in the case of FIG. 6, but the new / old selection screen 501 in this case is for a customer (referred to as “new / old selection unnecessary customer”) which does not require selection of new or old among migratable customers. The selection for the current screen (old system) is deactivated. Therefore, only the new screen (new system) can be selected. Of course, when a new screen is selected, the new login screen 401 is displayed, and when authentication is completed on the new login screen 401, the portal screen 600 is displayed in the same manner. Although not shown, there may be a new / old selection screen 501 in which only the old screen (old system) can be selected.

  It is needless to say that it is possible to select the current screen (old system) on the new and old selection screen 500 for the “new and old selected customer” which also uses the new and old systems even in step 3. The information is set in the user information DB 301 according to the request of the customer as to whether the “new or old selection unnecessary customer” or the “new and old selection required customer” is selected. Moreover, although illustration is abbreviate | omitted in FIG. 7, both new and old selection unnecessary customers and new and old selection required customers are permitted to access a new URL and to use a new system.

  This completes the description of the present system, but the functional configuration of each server in FIG. 3 is merely an example, and one functional block (database and functional processing unit) may be divided, or a plurality of functional blocks may be grouped together to form one It may be configured as a functional block. In each function processing unit, a central processing unit (CPU) incorporated in the apparatus reads a computer program stored in a storage device such as a read only memory (ROM), a flash memory, a solid state drive (SSD), or a hard disk. , By a computer program executed by the CPU. That is, each function processing unit reads and writes necessary data such as a table from a database (DB) stored in a storage device or a storage area on a memory, and in some cases, the computer program It is realized by controlling hardware (for example, an input / output device, a display device, a communication interface device). Further, the database (DB) in the embodiment of the present invention may be a commercial database, but also means a mere collection of tables and files, and the internal structure of the database itself is not limited.

(Effect of the embodiment)
The migration method of the present system described above produces the following remarkable effects.
Both new and old systems can be used in the transition phase by the transition-related new / old switch enable / disable flag, and it becomes possible to go back and forth. Here, it is possible to turn on / off the new / old switching by simply changing the flag provided for each customer and each user.
Also, in a system with many users and many screens, when updating the system, it is not clear whether all users can switch simultaneously, so it is possible to set up a training period separately for each user. (Can be switched separately if the user ID is different even within the same customer).
Here, during the transition period, customers can freely choose to start using the new system, and it is possible to use only the old system, or to use only the new system, or in combination. And it is also possible to go back to the old system even after migrating to the new system.
In addition, as a service provider / operator, even if there is a problem with the new system, it is possible to instantly switch to the old system, so there is less psychological burden when trying out the new system.
Thus, in this migration system, it is easy to move from the new system to the old system as well as to move from the old system to the new system.

  As mentioned above, although the present invention was explained using an embodiment, it is needless to say that the technical scope of the present invention is not limited to the range given in the above-mentioned embodiment. It is apparent to those skilled in the art that various changes or modifications can be added to the above embodiment. It is also apparent from the scope of the claims that the embodiments added with such alterations or improvements can be included in the technical scope of the present invention.

  Although the present invention has been described as the invention of the system migration method, the present invention can also be grasped as the invention of a migration system or a program in the system.

10 Current Web Server 11 New Web Server 20 Current AP Server 21 New AP Server 30 Current DB Server 31 New DB Server 101 Customer Terminal Communication Means 102 Login Control Means 103 New Screen Control Means (New Web Server Side)
103A New Screen Control Means (Current Web Server Side)
111 New and old selection screen control means 112 Current screen control means 201 Current BL execution means 211 New and old data conversion means (bridge)
301 User Information DB
302 Various business DB
400 Current login screen 401 New login screen 410 Current IB screen 411 New IB screen 500, 501 New and old selection screen 600 Portal screen 700 Other system screen

Claims (8)

A method of migrating a system from a current system to a new system in a three-tier system having a web server, an AP server and a DB server,
The web server is a current web server and a new web server, the AP server is a current AP server and a new AP server, and the DB server is a current DB server.
During the transition from the current system to the new system, the current web server may use only the current web server or only the new web server for each customer and / or each user of the customer. A system migration method comprising displaying a new and old usage setting screen for setting which one of both Web servers is to be selected and used.   The current DB server includes storing a combination selection table for setting whether or not to switch the current system and the new system for each of the customer and / or the user of the customer. System migration method described.   The new AP server includes new and old data conversion means for converting data input and selected in a new screen displayed by the new Web server into a format that can be processed by the current AP server. System migration method described in.   The current Web server displays a new / old selection screen after login to the current system, and when the user selects a new screen, a new login for logging in to the new system by taking over the customer ID and the user ID. The system migration method according to any one of claims 1 to 3, wherein a screen is displayed.   The system migration method according to any one of claims 1 to 4, wherein after the migration is completed, setting to deactivate the selection of the current system on the new and old selection screen is performed on the new and old usage setting screen. .   The system migration method according to claim 5, characterized in that, even after the selection of the current system is inactivated, the selection of the current system is restored according to the request of the customer. A migration system in a three-tier system having a web server, an AP server, and a DB server,
The web server is a current web server and a new web server, the AP server is a current AP server and a new AP server, and the DB server is a current DB server.
In the transition stage from the current system to the new system, the current Web server makes only the current Web server available or only the new Web server available for each customer and / or each user of the customer. A migration system comprising new and old usage setting means for setting which one of Web servers is to be selected and used. A program for migrating from a current system to a new system in a 3-tier system having a web server, an AP server and a DB server,
The web server is a current web server and a new web server, the AP server is a current AP server and a new AP server, and the DB server is a current DB server.
In the transition stage from the current system to the new system, the current Web server makes only the current system available for each customer and / or each user of the customer, or uses only the new Web server, or both. A program which causes a computer to execute a step of displaying a new and old usage setting screen for setting which one of the Web servers is selected and used.

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