Access control method and system

An access control method used at a second Web system when a Web client connected to a first Web system via a network and viewing information provided by the first Web system changes an access destination to the second Web system, the access control method comprising the steps of:

• transferring certification information to the first Web system in response to a certification information obtaining request from the first Web system;
• receiving from the Web client an access request that requests the second Web system to provide information;
• and
• recognizing information relating to the certification information from the access request.

An access control method used at a Web client when the Web client connected to a first Web system via a network and viewing information provided by the first Web system changes an access destination to the second Web system, the access control method comprising the steps of:

• transferring to the first Web system a request to change the access destination based on information provided by the first Web system;
• receiving from the first Web system a transition instruction including identification information that specifies the second Web system and certification information responding to the request to change the access destination;
• and
• accessing the second Web system, using the received certification information.

An access control method used at a first Web system when a Web client connected to the first Web system via a network and viewing information provided by the first Web system changes an access destination to a second Web system, the access control method comprising the steps of:

• receiving from the Web client an access destination change request that requests changing an access destination to the second Web system;
• requesting the second Web system for certification information based on the received access destination change request;
• receiving certification information from the second Web system;
• storing identification information that specifies the access destination and the certification information associated with the identification information;
• and
• transferring to the Web client the identification information and the certification information responding to the access destination change request.

An access control system used at a first Web system when a Web client connected to the first Web system via a network and viewing information provided by the first Web system changes an access destination to a second Web system that provides services via the network, the access control system comprising:

• a storage device that stores user identification information that discriminates the user who uses the Web client and information including the number of usage of the services provided by the second Web system;
• a device that receives from the Web client an access destination change request that requests changing an access destination to the second Web system;
• a device that adds a number to the number of usage of the services in response to the access destination change request;
• a device that transfers to the Web client identification information that specifies the access destination, certification information responding to the access destination change request and the user identification information;
• and
• a device that charges the user for the use of the services according to the number of usage of the services stored.

An access control method used when a Web client connected to a first Web system via a network and viewing information provided by the first Web system changes an access destination to a second Web system, the access control method comprising the steps of:

• at the Web client, transferring to the first Web system an access destination change request based on information provided by the first Web system;
• at the first Web system, receiving from the Web client the access destination change request that requests changing a destination to the second Web system, and transferring to the second Web system a certification information obtaining request that requests certification information in response to the access destination change request;
• at the second Web system, transferring to the first Web system certification information in response to the certification information obtaining request transferred from the first Web system;
• at the first Web system, transferring to the Web client identification information that specifies the access destination and certification information responding to the access destination change request;
• at the Web client, receiving from the first Web system a transition instruction including identification information that specifies the second Web system and certification information responding to the access destination change request, and changing an access destination to the second Web system according to the transition instruction;
• and
• at the second Web system, receiving from the Web client an access request that requests the second Web system to provide information, and extracting information relating to the certification information from the access request.