Abstract:
An information processing apparatus is disclosed that uses a function of an external apparatus using certificate information from an authentication apparatus for authenticating a user. The information processing apparatus includes: a receiving unit that receives authentication information for causing the authentication apparatus to authenticate the user; a first acquiring unit that acquires first certification information indicating that the user has been authenticated by sending the authentication information to the authentication apparatus; and a second acquiring unit that acquires second certification information for using a function of the external apparatus from the authentication apparatus based on the first certification information. It is possible to provide an information processing apparatus that, even if a certificate for using a service expires, can continue using the service without having the user notice the expiration.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to an information processing apparatus that uses a service based on electronic certification information, an authentication apparatus that provides the certification information to the information processing apparatus, and an external apparatus that provides the service to the information processing apparatus. 
   2. Description of the Related Art 
   When a client accesses a server to receive a service via a network, the client is generally required to present authentication information such as a user name and a password. Such authentication information is required to prevent unauthorized users from accessing the server. 
   However, especially in the case of the Internet, it is not preferable that such authentication information is often transmitted through the network since many unnamed users may access the transmitted authentication information. 
   To avoid such a problem, an electronic certificate (hereinafter referred to as a “ticket”), instead of the authentication information, may be presented to the server. The ticket certifies that the user is authorized and has been authenticated. 
   The client first presents the user name and the password, for example, to an authentication server in which ticketing function is installed. The authentication server authenticates the client, and issues a ticket. 
   When the client presents the ticket to a particular server and requests for a service, the particular server requests the authentication server to verify the authenticity of the ticket. The particular server provides the client with the requested service subject to the verification of the authenticity of the ticket by the authentication server. 
   The ticket does not contain the authentication information such as the password. The ticket is valid for a validity period in which the client can use the service of the particular server. According to such arrangements, if the ticket is stolen, damage caused by the inauthentic use of the ticket would be less serious than inauthentic use of stolen password. The use of the ticket ensures to improve the security of the network. 
   “Single sign-on” technique has been already introduced in order to save user&#39;s time to input the user name and the password, for example. In the case of the single sign-on technique, when the user uses services of multiple servers, the user is required to input the user name and the password, for example, only once when the user has a ticket issued. Once the ticket is issued, the user can user the services of the multiple servers: by using the ticket, without inputting the user name and the password, for example. 
   However, as described above, the ticket is valid only for a validity period. When the ticket expires, the ticket is no more valid. The user cannot use a service of a server without a valid ticket. 
   The user needs to have another ticket issued in order to use the service of the server. The user needs to input the user name and the password, for example, again. The user may feel this troublesome. 
   SUMMARY OF THE INVENTION 
   Accordingly, it is a general object of the present invention to provide novel and useful information processing apparatus, authentication apparatus, and external apparatus in which at least one of the above problems is eliminated. 
   Another and more specific object of the present invention is to provide an information processing apparatus that, even if an electronic certificate for using a predetermined service has expired, can continue using the service without having the user notice the expiration, an authentication apparatus that provides the electronic certificate to the information processing apparatus, and an external apparatus that provides the information processing apparatus with the predetermined service. 
   To achieve at least one of the above objects, according to a first aspect of the present invention, an information processing apparatus that uses a function of an external apparatus using certificate information from an authentication apparatus for authenticating a user is characterized in that the information processing apparatus includes: 
   a receiving unit that receives authentication information for causing the authentication apparatus to authenticate the user; 
   a first acquiring unit that acquires first certification information indicating that the user has been authenticated by sending the authentication information to the authentication apparatus; and 
   a second acquiring unit that acquires second certification information for using a function of the external apparatus from the authentication apparatus based on the first certification information. 
   According to a second aspect of the present invention, an authentication apparatus is characterized by including: 
   an authentication unit that receives authentication information for authenticating a user, the authentication information being sent via a network from the information processing apparatus as claimed in claim  1 ; 
   a first certification information generating unit that generates first certification information indicating that the user has been authenticated based on the authentication information; and 
   a transmitting unit that transmits the first certification information generated by the first certification information generating unit to the information processing apparatus. 
   According to a third aspect of the present invention, an external apparatus is characterized by including: 
   a request receiving unit that receives via a network a request for providing a predetermined function, the request being transmitted with the second certification information from the information processing apparatus as claimed in claim  1 ; and 
   a processing performing unit that performs processing related to the request for providing a predetermined function; 
   wherein the processing performing unit performs processing related to the request based on the second certification information. 
   According to the present invention, it is possible to provide an information processing apparatus that, even if an electronic certificate for using a predetermined service has expired, can continue using the service without having the user notice the expiration, an authentication apparatus that provides the electronic certificate to the information processing apparatus, and an external apparatus that provides the information processing apparatus with the predetermined service. 
   Other objects, features, and advantages of the present invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a network diagram showing a Web system according to an embodiment; 
       FIG. 2  is a block diagram showing the hardware structure of a Web server according to an embodiment; 
       FIG. 3  is a schematic diagram showing the functional structure of a Web server according to an embodiment; 
       FIG. 4  is a schematic diagram for explaining the function of an authentication plug-in object and an authentication server according to an embodiment; 
       FIG. 5  is a sequence diagram for explaining authentication processing of a Web system according to an embodiment; 
       FIG. 6  is a sequence diagram for explaining authentication processing of a Web system according to an embodiment; 
       FIG. 7  is a sequence diagram for explaining authentication processing of a Web system according to an embodiment; 
       FIG. 8  shows an exemplary master ticket management table according to an embodiment; 
       FIG. 9  shows an exemplary SOAP message for calling a master ticket issuance method according to an embodiment; 
       FIG. 10  is a data diagram showing the data structure of a master ticket according to an embodiment; 
       FIG. 11  shows an exemplary SOAP message for calling a master ticket issuance method according to an embodiment; 
       FIG. 12  shows an exemplary master ticket management table according to an embodiment; 
       FIG. 13  shows an exemplary authentication information management table according to an embodiment; 
       FIG. 14  shows an exemplary SOAP message for calling an authentication ticket issuance method according to an embodiment; 
       FIG. 15  shows an exemplary SOAP message including response information of an authentication ticket issuance method according to an embodiment; 
       FIG. 16  is a sequence diagram for explaining authentication processing in response to a user&#39;s request for another service according to an embodiment; 
       FIG. 17  is a sequence diagram for explaining authentication processing in response to a user&#39;s request for another service according to an embodiment; 
       FIG. 18  is a sequence diagram for explaining authentication processing in response to a user&#39;s request for another service according to an embodiment; 
       FIG. 19  shows an exemplary SOAP message for calling an authentication ticket issuance method using a master ticket registered in a master ticket management table according to an embodiment; 
       FIG. 20  shows an exemplary SOAP message including response information of an authentication ticket issuance method; and 
       FIG. 21  is a network diagram showing a Web system configured by image processing apparatuses according to an embodiment. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The preferred embodiments of the present invention are described in detail below with reference to the drawings.  FIG. 1  is a network diagram showing a Web system according to an embodiment of the present invention. As shown in  FIG. 1 , a Web system  1  includes a Web server  10 , a terminal  20 , an authentication server  30 , a document management server  40 , and a document delivery server  50 . They are connected to each other via a network  60  such as the Internet and a LAN. 
   The Web server  10  is a computer that is capable for providing the terminal  20  with a Web page in which information requested by the terminal  20  is displayed. A Web page is data in the form of HTML or XML, for example, that a general purpose Web browser can display. When providing the Web page to the terminal  20 , the Web server  10  uses the authentication server  30 , the document management server  40 , and the document delivery server  50 , for example, on necessity basis. 
   The terminal  20  is a communication terminal such as a personal computer (PC), a personal digital assistant (PDA), or a cellular phone, which is provided with a Web browser. The user can browse the Web page provided by the Web server  10  with the browser. 
   The authentication server  30  is a computer that authenticates (authentication function) Web system  1  users based on their user names and passwords, for example. The authentication server  30  makes the authentication function available via the network  60  as a Web service (authentication service). 
   The document management server  40  is a computer in which a document database for managing document information is provided. The document management server  40  registers, retrieves, and updates document information (document management functions), and make the document management functions available via the network  60  as a Web service (document management service). 
   The document delivery server  50  delivers document data (document delivery function), and this document delivery function is made available via the network  60  as a Web service (document delivery service). The document data selected by the terminal  20  is delivered to a destination designated by the terminal  20 . 
   The authentication server  30 , the document management server  40 , and the document delivery server  50  provide their functions as Web services, which can be called by RPC of SOAP. Accordingly, the three servers may be collectively referred to as a “SOAP server”. 
   The Web server  10  is described in detail below.  FIG. 2  is a block diagram showing the hardware structure of the Web server  10  according to an embodiment. The Web server  10  includes CPU  1011 , ROM  1012 , RAM  1013 , a secondary storage unit  1014 , a network interface (I/F)  1015 , and a drive unit  1016 . 
   The CPU  1011  is a control unit for controlling the entire system of the Web server  10 . The CPU  1011  executes various control programs and various application programs stored in the ROM  1012  and the secondary storage unit  1014  in order to control the Web server  10 , control communications via the network  60 , acquire and edit data, for example. 
   The ROM  1012  is a memory unit for mainly storing the control programs of the Web server  10 . The RAM  1013  is a memory unit for temporally storing data as a working memory of the CPU  1011 . 
   The secondary storage unit  1014  is a storage unit for storing various application programs and data. The network interface  1015  is an interface for connecting the Web server  10  to the network  60 . 
   The drive unit  1016  is a drive unit for reading programs according to an embodiment stored in a recording medium  1017  such as a CD-ROM. 
   The Web server may be provided with an operation unit (not shown) such as a keyboard and a mouse for receiving instructions from the user, and a display unit (not shown) such as a liquid crystal display or a CRT display for displaying the results of operations. 
   The other SOAP servers may be configured in the same manner as the Web server  10  shown in  FIG. 2 . Programs for realizing the functions of the SOAP servers may be stored in a recording medium and can be provided. The SOAP server realizes the functions defined by the programs by reading the recording medium such as a CD-ROM with the drive unit  1016 . 
   The functional configuration of the Web system  1  according to an embodiment is described below.  FIG. 3  is a schematic diagram showing the functional configuration of the Web server  10 . As shown in  FIG. 3 , the Web server  10  includes a Web server program  11 , a Web application  12 , a plug-in controller  13 , an authentication plug-in manager  14 , a document management plug-in manager  15 , a document delivery plug-in manager  16 , an authentication plug-in object  17 , a document management plug-in object  18 , and a document delivery plug-in object  19 . 
   The Web server program  11  is a daemon program that receives various requests from the terminal  20  as HTTP requests using HyperText Transfer Protocol (HTTP), calls the Web application  12  corresponding to the request, and transmits the Web pages generated by the Web application  12  to the terminal  20 . 
   The Web application  12  is a kind of Web applications. Its major function is to generates Web pages represented in HTML format, for example. When generating the Web pages, the Web application  12  acquires, if necessary, an authentication plug-in object  17 , a document management plug-in object  18 , or a document delivery plug-in object  19  (hereinafter correctively referred to as “plug-in object”), for example, via the plug-in controller  13 . The Web application  12  can use the functions of various SOAP servers via such objects. The plug-in controller  13  is a module for providing common interface through which the Web application  12  can acquire various plug-in objects. That is, the plug-in controller  13  accepts requests for an object via the common interface (method) regardless the type of the object. For example, the plug-in controller  13  according to the embodiment accepts the request for an object by a method “getPlugin( )” (a plug-in acquiring method). Each Web application  12  acquires an object by calling the common plug-in acquiring method whatever the type of the object is. 
   The authentication plug-in manager  14 , the document management plug-in manager  15 , and the document delivery plug-in manager  16  manages the life cycles of plug-in objects based on the types of the plug-in objects. That is, the object manager has, for example, function for generating a corresponding plug-in object and function for discarding the corresponding plug-in object as methods. 
   The authentication plug-in object  17 , the document management plug-in object  18 , and the document delivery plug-in object  19  are provided for transparently providing the functions of the authentication server  30 , the document management server  40 , and the document delivery server  50 , respectively, to the Web application  12  via method interface. In response to a call for the method from the Web application  12 , the plug-in object provides the function of the SOAP server to the Web application  12  by calling the corresponding method using RPC of SOAP. 
   In the embodiment, a plug-in includes a plug-in manager and a plug-in object. For example, the plug-in (authentication plug-in) corresponding to the authentication server  30  includes the authentication plug-in manager  14  and the authentication plug-in object  17 . Similarly, the plug-in (document management plug-in) corresponding to the document management server  40  includes the document management plug-in manager  15  and the document management plug-in object  18 . The plug-in (document delivery plug-in) corresponding to the document delivery server  50  includes the document delivery plug-in manager  16  and the document delivery plug-in object  19 . 
   Thus, if a new plug-in is to be added, for example, if the plug-in corresponding to a print server for printing document data, a print plug-in manager and a print plug-in object are to be installed. 
   a document management service  45  for managing documents (document management function) as a Web service is installed in the document management server  40 . A document management service  45  includes a SOAP processing unit  41 , a document management unit  42 , and an authentication ticket verification unit  43 . The SOAP processing unit  41  is a module that receives a SOAP message including information for calling the method transmitted by the document management plug-in  17 , and calls the requested method based on the SOAP message. 
   The document management unit  42  is a module in which various methods for providing the document management functions are installed. The methods installed in the document management unit  42  are called by the RPC of SOAP. 
   The authentication ticket verification unit  43  is a module for verifying the authenticity of an authentication ticket. The authentication ticket is data including information indicating that the user has been authenticated by the authentication server  30 , or data including pointer information of the information. When the authentication server  30  authenticates the user based on the authentication information input by the user, the authentication server issues the authentication ticket. 
   A document delivery service  55  for delivering documents as a Web service is installed in the document delivery server  50 . The document delivery service  55  includes a SOAP processing unit  51 , a document delivery unit  52 , and an authentication ticket verification unit  53 . The SOAP processing unit  51  and the authentication ticket verification unit  53  have similar functions to the SOAP processing unit  41  and the authentication ticket verification unit  43 , respectively, of the document management server  40 . The document delivery unit  52  is a module in which various methods for delivering documents (document delivery function) are installed. That is, the RPC of SOAP calls the methods installed in the document delivery unit  52 . 
     FIG. 4  is a functional block diagram showing the authentication plug-in object and the authentication server. As shown in  FIG. 4 , the authentication plug-in object  17  includes an authentication method  171 , a master ticket acquisition method  172 , an authentication ticket acquisition method  173 , an authentication information management table  174 , and a master ticket management table  175 . 
   The authentication method  171  is a method for accepting a request for authentication based on the authentication information from the user. The authentication method  171  requests authentication requested by the plug-in controller  13  to the authentication server  30  by calling the master ticket acquisition method  172  or the authentication ticket acquisition method  173 , for example. The authentication method  171  returns the authentication ticket issued as the result of the authentication to the authentication method  171 . The authentication method  171  accepts the user name and the password related to the authentication request as parameters. 
   The master ticket acquisition method  172  is a method that acquires the master ticket from the authentication server  30  by transmitting to the authentication server  30  a request for the authentication based on the user name and the password designated as the parameters of the authentication method  171 . 
   The master ticket is data that indicates that the user is authenticated by the authentication server  30  as the authentication ticket is, but both tickets are different in usage. 
   The authentication ticket is valid in a limited range such as in a single SOAP server. For example, an authentication ticket that is issued for the document management server  40  cannot be used by other SOAP servers. The authentication ticket verification unit of a SOAP server does not accept any authentication ticket that is not issued for the SOAP server. Accordingly, if the authentication ticket is stolen, the owner of the authentication ticket may fail to prevent the SOAP server for which the authentication ticket has been issued from being accessed. The person who has stolen the authentication ticket cannot access any SOAP server other than the SOAP server for which the authentication ticket has been issued. 
   On the other hand, the master ticket is a ticket valid for all SOAP servers that accept authentication using a ticket. The user can obtain an authentication ticket by presenting the master ticket. Accordingly, if the master ticket is stolen, the owner of the master ticket cannot prevent the entire system that accepts authentication using a ticket from being accessed by an unauthorized user who has stolen the master ticket. 
   The two different types of tickets are defined so as to improve the security of network. The authentication ticket is defined for preventing the master ticket from being transmitted often via the network. According to this arrangement, the master ticket needs to be used only on limited occasions such as the issuing of an authentication ticket based on the request of the master ticket owner. 
   The authentication ticket acquisition method  173  is a method for acquiring an authentication ticket from the authentication server  30  by transmitting a request for the issuance of the authentication ticket to the authentication server  30  using the master ticket that the master ticket acquisition method  172  has obtained from the authentication server  30 . 
   The authentication information management table  174  is a table for retaining authentication information of a user such as a password input by the user. The master ticket management table  175  is a table for retaining a master ticket acquired by the master ticket acquisition method  172 . 
   On the other hand, an authentication service  35  is installed in the authentication server  30 . The authentication service  35  provides authentication function as Web service. The authentication service  35  includes a SOAP processing unit  31 , an authentication processing unit  32 , a master ticket issuance unit  33 , and an authentication ticket issuance unit  34 . 
   The SOAP processing unit  31  is a similar module to the SOAP processing unit of other SOAP servers such as the document management server  40 . The authentication processing unit  32  is a module in which authentication function for users based on their authentication information is installed. The authentication processing unit  32  accepts a request for using the authentication function via a method interface. That is, the method installed in the SOAP processing unit  31  is called by the RPC of SOAP. 
   The master ticket issuance unit  33  is a module for generating a master ticket for a user who is authenticated by the authentication processing unit  32 . The authentication ticket issuance unit  34  is a module for generating an authentication ticket based on the master ticket. 
   The processing steps performed by the Web system  1  are described below.  FIGS. 5 ,  6 , and  7  are sequence diagrams for explaining the authentication of a user who uses the Web system for the first time. It is noted that the “user who uses the Web system for the first time” is a user who intends to use the functions of the document management server  40  and/or the document delivery server  50 , for example, but has not been authenticated by the authentication server  30  yet. 
   Using the Web browser of the terminal  30 , the user inputs a URL of a Web page (hereinafter referred to as “document list page”) in which document list information is displayed in order to browse the list information (hereinafter referred to as “document list information”) of document data managed by the document management server  40 . In response to the user&#39;s input, the terminal  30  transmits a HTTP request for requesting the transmission of a document list page to the Web server  10  (S 11 ). 
   In the Web server  10 , the Web application  12  is called by the Web server program  11  that has received the HTTP request from the terminal  30 . The Web application  12  needs to acquire the document management plug-in object  18  in order to obtain the document list information. The Web application  12  requests the plug-in controller  13  to provide the document management plug-in object  18  by calling a plug-in acquisition method (getPlugin( )) of the plug-in controller  13  (S 12 ). A plug-in name (“document management” in this case) that indicates the type of the plug-in object to be acquired is designated as the parameter of the plug-in acquisition method. 
   The plug-in controller  13  determines the type of plug-in in which the requested plug-in object (document management plug-in object  18 ) is included based on the plug-in name designated as the parameter of the plug-in acquisition method. The plug-in controller  13  requests the plug-in manager to provide the plug-in object by calling the plug-in acquisition method (getPlugin( )) of the plug-in manager (document management plug-in object manager  14 ) of the plug-in. 
   An authentication ticket may be designated as the parameter of the plug-in acquisition method of the plug-in manager. However, no authentication ticket is designated as the parameter in this case. As will be appreciated, the authentication ticket designated as the parameter is used for establishing a session with the document management server  40 . Some SOAP servers, however, may not need the authentication of the user for establishing a session. Thus, it is worth to try establishing a session with the document management server  40  before obtaining user authentication (without authentication ticket). 
   In step S 14  subsequent to step S 13 , the document management plug-in manager  15  converts the document management plug-in object  18  into an instance. After being converted into an instance, the document management plug-in object requests the document management server  40  to establish a session by calling a session establishment method (startSession( )) of the document management server  40  using the RPC of SOAP (S 15 ). It is possible to designate the authentication ticket as the parameter of the session establishment method. However, as described above, no authentication ticket is designated as the parameter. 
   In the present embodiment, the document management server  40  is installed in a manner in which only an authenticated user can access the document management server  40 . That is, the authentication ticket verification unit  53  of the document management server  40  is designed to verify the authenticity of the authentication ticket that may be designated as the parameter of the session establishment method. However, in this case, no authentication ticket is designated as the parameter of the session establishment method. As a result, the document management server  40  transmits a message that, since the user has not been authenticated, the document management server cannot establish a session (authentication error) to the document management plug-in object  18  as response information of the session establishment method (S 16 ). 
   The authentication error is returned from the document management plug-in object  18  to the plug-in controller  13  via the document management plug-in manager  15  (S 17 , S 18 ). 
   In response to receipt of the authentication error, the plug-in controller  13  determines that the authentication ticket is needed for using the document management server  40 . As a result, the plug-in controller  13  requests (getPlugin( )) the authentication plug-in manager  14  to provide the authentication object in order to have the authentication server  30  to issue the authentication ticket (S 19 ). 
   The authentication plug-in manager  14  converts the authentication plug-in object  17  into an instance (S 20 ), and returns the authentication plug-in object  17  to the plug-in controller  13  (S 21 ). 
   The plug-in controller  13  requests the authentication plug-in object  17  to issue the authentication ticket for the document management server  40  by calling an authentication method  171  of the authentication plug-in object  17  (S 22 ). It is possible to designate the authentication information such as the user name and password of the user. However, since the user has not input the authentication information yet at this stage. As a result, the plug-in controller  13  calls the authentication method  171  without designating the authentication information as a parameter. 
   The plug-in controller  13  calls the authentication method  171  without requesting the user to input the user&#39;s authentication information and designating the authentication information as the parameter. The reason is that, as will be appreciated, if the current user has an experience of acquiring an authentication ticket, the current user may successfully acquire the authentication ticket without designated the authentication information as the parameter of the authentication method. 
   In step S 23 , since no authentication information is designated as the parameter of the authentication method, the authentication plug-in object  17  determines whether the current user has an experience of being authenticated by referring to the master ticket management table  175 . 
     FIG. 8  shows an exemplary master ticket management table. As shown in  FIG. 8 , the master ticket management table  175  includes data items corresponding to an ID, a master ticket, and a URL of the authentication service, for example, and is used for retaining master tickets that have been issued for users. 
   The ID is a number for uniquely identifying each record. The master ticket is the master ticket itself that has been issued. The authentication service URL is a URL for the authentication service of the authentication server that has issued the master ticket. 
   At this stage, since the user has not been authenticated by the authentication server  30  yet, no master ticket has been registered in the master ticket management table  175 . As a result, the authentication method  171  of the authentication plug-in object  17  returns a message that the authentication ticket cannot be issued for the user (authentication error) to the plug-in controller  13  (S 24 ). 
   The plug-in controller  13  returns the authentication error to the Web application  12  as response information of the plug-in acquisition method called in step S 12  (S 25 ). 
   In response to receipt of the authentication error, the Web application  12  determines that the Web application  12  needs to request the user to input the authentication information, and generates a Web page (hereinafter referred to as “log-in page”) through which the user can input the user name and password (S 26 ). The log-in page is transmitted from the Web application  12  to the terminal  20  via the Web server program  11 , and is displayed by the Web browser of the terminal  20  (S 27 ). 
   If the user inputs the authentication information such as the user name and password through the log-in page, the terminal  20  transmits a request (HTTP request) for transmitting the document list page to the Web server  10  again with the authentication information ( FIG. 6 , S 28 ). 
   The Web application  12  requests the plug-in controller  13  to provide the document management plug-in object  17  by calling the plug-in acquisition method of the plug-in controller  13  in the same manner as step S 12  (S 29 ). In this case, the authentication information received from the terminal  20  is designated as the parameter of the plug-in acquisition method. 
   Since the authentication information is designated as the parameter of the plug-in acquisition method, the plug-in controller  13  requests the authentication plug-in manager  14  to provide the authentication plug-in object  17  by calling the plug-in acquisition method of the authentication plug-in manager  14  (S 30 ). The authentication plug-in manager  14  acquires the authentication plug-in object  17  converted into an instance in step S 20  (S 31 ), and returns the authentication plug-in object  17  to the plug-in controller  13  (S 32 ). 
   The plug-in controller  13  requests for the authentication ticket for the document management server  40  again by calling the authentication method  171  of the authentication plug-in object  17  (S 33 ). It is noted that the authentication information received from the terminal  20  is designated as the parameter of the authentication method this time. 
   Since the authentication information is designated as the parameter, the authentication method  171  calls the master ticket acquisition method  172  to acquire the master ticket required for having an authentication ticket issued. The master ticket acquisition method  172  transmits a request (SOAP message) for authentication and issuance of the master ticket based on the authentication information to the authentication server  30  by calling the master ticket issuance method of the authentication processing unit  32  of the authentication server  30  using the RPC of SOAP (S 34 ). 
     FIG. 9  shows an exemplary SOAP message for calling the master ticket issuance method. In the SOAP message  61  of  FIG. 9 , a portion indicated by a reference numeral  611  is information for calling the master ticket issuance method. The tag name “authenticateByPassword” of a tag  612  is the method name of the master ticket issuance method. Descriptions  613 ,  614 , and  615  indicate the parameter of the master ticket issuance method. The descriptions  613  and  614  correspond to the user name and the password, respectively. The description  615  corresponds to the validity period (the unit being minutes) of the requested master ticket. 
   In step S 35  subsequent to step S 34 , the master ticket issuance method of the authentication processing unit  32  is called by the SOAP processing unit  31  that has received the SOAP message  61  ( FIG. 9 ). The authentication processing unit  32  authenticates the current user based on the authentication information such as the user name and password designated as the parameter of the master ticket issuance method. 
   If the current user is authenticated, a master ticket issuance unit  33  generates the master ticket for the current user based on a request from the authentication processing unit  32  (S 36 ). 
     FIG. 10  is a data diagram showing the exemplary data structure of the master ticket. As shown in  FIG. 10 , the master ticket includes a ticket ID, validity range, validity period, authenticated user ID, and MIC. 
   The ticket ID is a code for uniquely identifying the issued ticket. The validity range is information for identifying either the master ticket or the authentication ticket, and in the case of the authentication ticket, the range in which the authentication ticket can be used. That is, if the ticket is the master ticket, the entry of the validity range is “master”. If the ticket is the authentication ticket, a domain name or a server name, for example, is recorded as the entry of the validity range in order to identify the range in which the authentication ticket can be used. 
   The validity period is a period in which an authentication ticket can be issued based on the ticket. The validity period is determined based on the validity period designated as the parameter of the authentication method. An expired ticket is invalid. According to this arrangement, damage caused by a stolen master ticket can be prevented from expanding unlimitedly. 
   The authentication user ID is a user ID of an authenticated user. The MIC is a code for verifying that the ticket has not been altered on its way. 
   In step S 37  subsequent to step S 36 , the authentication processing unit  32  outputs the master ticket generated by the master ticket issuance unit  33  to the SOAP processing unit  31  as response information of the master ticket issuance method. Then, the SOAP processing unit  31  serializes the master ticket, and transmits a SOAP message including the serialized master ticket as response information to the authentication plug-in object  17 . 
     FIG. 11  shows an exemplary SOAP message including response information of the master ticket issuance method. In the SOAP message  62  of  FIG. 11 , a portion indicated by a reference numeral  621  is the response information. That is, a character string between &lt;returnValue&gt; tags in a description  622  is the serialized master ticket. 
   In step S 38  subsequent to step S 37 , the authentication method  171  of the authentication plug-in object  17  registers the master ticket received from the authentication server  30  in the master ticket management table  175 , and further registers the authentication information such as the user name and password input through the log-in page in the authentication information management table  174 . 
     FIG. 12  shows an exemplary master ticket management table in which a master ticket has been registered. As shown in  FIG. 12 , the contents of the master ticket and the URL of the authentication server  30  that has issued the master ticket. 
     FIG. 13  shows an exemplary authentication information management table. As shown in  FIG. 13 , the authentication information management table  174  includes data items such as an ID, the user name, the password, and an authentication service URL. 
   The ID is a number for uniquely identifying each record, and is the same value as the corresponding record in the master ticket management table  175 . That is, the ID is used for correlating the record of the authentication information management table  174  and the record of the master ticket management table  175 . 
   The user name and password are those of the authenticated user. The authentication service URL is a URL of the authentication service of the authentication server  30  that has issued the master ticket, and carries the same value as the corresponding record of the master ticket management table  175 . 
   According to the present embodiment, the record of the authentication information management table  174  and the record of the master ticket management table  175  correspond one to one. As a result, information of both tables may be managed by a single table. 
   In step S 39  subsequent to step S 38 , the authentication method  171  calls the authentication ticket acquisition method  173  by designating the master ticket acquired in step S 37  as the parameter in order to have an authentication ticket issued. In response to the call, the authentication ticket acquisition method  173  transmits a request (SOAP message) for issuing the authentication ticket to the authentication server  30  by calling the authentication ticket issuance method of the authentication processing unit  32  of the authentication server  30  using the RPC of SOAP. 
     FIG. 14  shows an exemplary SOAP message for calling the authentication ticket issuance method. In the SOAP message  63  of  FIG. 14 , a portion indicated by a reference numeral  631  is call information for the authentication ticket issuance method. That is the tag name “createAuthTicket” of a tag  632  is the method name of the authentication ticket issuance method. Descriptions  633 ,  634 , and  635  are parameter information of the authentication ticket issuance method. The description  633  corresponds to the master ticket. The description  634  corresponds to validity period (the unit being minutes) of the requested authentication ticket. The description  635  corresponds to a validity range of the requested authentication ticket. 
   In step S 40  subsequent to step S 39 , in response to receipt of the SOAP message ( FIG. 14 ), the SOAP processing unit  31  calls the authentication ticket issuance method of the authentication processing unit  32 . The authentication processing unit  32  verifies the authenticity of the master ticket designated as the parameter of the authentication ticket issuance method. The authenticity of the master ticket is verified by determining that the master ticket has not been expired and is not altered, for example. 
   Once the authenticity of the master ticket is verified, the authentication ticket issuance unit  34  generates an authentication ticket based on the master ticket in response to a request from the authentication processing unit  32  (S 41 ). The authentication ticket may have the same data structure as the master ticket shown in  FIG. 10 . According to another embodiment, the authentication ticket may be pointer information of user information managed by the authentication server  30 . 
   The authentication processing unit  32  outputs the authentication ticket generated by the authentication ticket issuance unit  34  to the SOAP processing unit  31  as response information of the authentication ticket issuance method. In response to the output, the SOAP processing unit  31  serializes the authentication ticket, and transmits a SOAP message including the serialized authentication ticket as response information to the authentication plug-in object  17  (S 42 ). 
     FIG. 15  shows an exemplary SOAP message including response information of the authentication ticket issuance method. In the SOAP message  64  of  FIG. 11 , a portion indicated by a reference numeral  641  is the response information. A character string between &lt;returnValue&gt; tags indicated by a reference numeral  642  is the serialized authentication ticket. 
   In step S 43  subsequent to step S 42 , the authentication method  171  returns a de-serialized authentication ticket to the plug-in controller  13  as response information. 
   Following the above steps, the plug-in controller  13  acquires the authentication ticket for the document management server  40  for the current user. Then, the plug-in controller  13  requests the document management plug-in manager  15  to provide the document management plug-in object  18  by calling the plug-in acquisition method (getPlugin( )) of the document management plug-in manager  15  again using the acquired authentication ticket as the parameter ( FIG. 7 , S 44 ). 
   The document management plug-in manager  15  requests the document management plug-in object  18  converted into an instance in step S 14  to establish a session with the document management server  40  using the authentication ticket as the parameter (S 45 ). The document management plug-in object  18  calls the session establishment method (startSession( )) of the document management server  40  using the authentication ticket issued based on the master ticket as the parameter by the RPC of SOAP (S 46 ). 
   In the document management server  40 , the authentication ticket verification unit  43  determines, for example, whether the current user being the owner of the authentication ticket is permitted to access the document management server  40  by verifying the authentication ticket designated as the parameter of the session establishment method (S 47 ). 
   Once a determination is made that the current user is permitted to access the document management server  40 , the document management unit  42  of the document management server  40  establishes a session, and transmits a message that a session has been established to the document management plug-in object  18  as response information of the session establishment method (S 48 ). 
   The document management plug-in object  18  returns a message that a session has successfully established to the document management plug-in manager  15  (S 49 ). In response to receipt of the message, the document management plug-in manager  15  outputs the document management plug-in object  18  to the plug-in controller  13  (S 50 ). The document management plug-in object  18  is returned to the Web application  12  as response information of the plug-in acquisition method called in step S 29  (S 51 ). 
   The Web application  12  acquires the document management plug-in object  18 , and requests the document management plug-in object  18  to acquire the document list information (S 52 ). The document management plug-in object  18  request the document management server  40  to transmit the document list information by calling the document list acquisition method of the document management unit  42  of the document management server  40  using the RPC of SOAP (S 53 ). 
   The document management unit  42  acquires the document list information, and transmits the document list information to the document management plug-in object  18  as response information of the document list acquisition method (S 54 ). 
   The document management plug-in object  18  returns the received document list information to the Web application  12  (S 55 ). In response, the Web application  12  generates the document list page for displaying the document list information (S 56 ). The document list page is transmitted from the Web application  12  to the terminal  20  via the Web server program  11 , and displayed by the Web browser of the terminal  20  (S 57 ). 
   According to the above process, the authentication information and master ticket of the user has been retained in the authentication information management table  174  or the master ticket management table  175  using the document management service of the Web system  1 . 
   Next, the operation of the Web system  1  in the case in which the user uses a service other than the document management service is described below. 
     FIGS. 16 through 18  are sequence diagrams for explaining authentication processing in the case in which the user requests for another service. 
   The user requests for delivery of document data through the document list page displayed by the Web browser of the terminal  20 . In response to the user&#39;s request, the terminal  30  transmits a HTTP request for requesting the Web server  10  to deliver the document data (S 61 ). 
   In the Web server  10 , in response to receipt of the HTTP request from the terminal  20 , the Web server program  11  calls the Web application  12 . It is necessary to acquire a document delivery plug-in object  19  for the document delivery server  50  to deliver the document data. The Web application  12  designates the plug-in name (“document delivery”) of the document delivery plug-in as the parameter, and calls the plug-in acquisition method (getplugin( )) of the plug-in controller  13  (S 62 ). 
   The plug-in controller  13  calls the plug-in acquisition method of the document delivery plug-in manager  16  without designating the authentication ticket as the parameter in the same manner in which the document management plug-in object  18  has been acquired ( FIG. 5 , S 13 ). The plug-in controller  13  does not care whether the current user has been authenticated (S 63 ). 
   The document delivery server  50  is installed in the same manner as the document management server  40  in which only authenticated users have access thereto. Accordingly, steps S 64  through S 72  are identical to steps S 14  through S 22 . 
   That is, the document delivery plug-in object  19  is made into an instance (S 64 ). The document delivery plug-in object  19  requests for establishing a session with the document delivery server  50  (S 65 ). In response to the request, the document delivery server  50  returns the authentication error (S 66 ). The authentication error is returned to the plug-in controller  13  via the document delivery plug-in manager  16  (S 67 , S 68 ). 
   Since the plug-in controller  13  acquires the authentication ticket, the plug-in controller can acquire authentication plug-in object  17  (S 69  through S 71 ). The plug-in controller  13  requests the authentication plug-in object  17  to issue an authentication ticket for the document delivery server  50  by calling the authentication method  171  of the authentication plug-in object  17  without designating the authentication information as the parameter (S 72 ). 
   The authentication method  171  acquires the master ticket from the master ticket management table  175  ( FIG. 12 ) (S 73 ). Since the master ticket management table  175  retains the master ticket issued retained as described above, the master ticket retained in the master ticket management table  175  is used. 
   The authentication method  171  calls the authentication ticket acquisition method  173  with designating the master ticket acquired from the master ticket management table  175  as the parameter in order to have the authentication ticket issued. In response to calling, the authentication ticket acquisition method  173  transmits a request (SOAP message) for issuing the authentication ticket to the authentication server  30  by calling the authentication ticket issuance method of the authentication processing unit  32  of the authentication server  30  using the RPC of SOAP (S 74 ). 
     FIG. 19  shows an exemplary SOAP message for calling the authentication ticket issuance method using the master ticket registered in the master ticket management table. The SOAP message  65  of  FIG. 19  is configured in the same manner as the SOAP message  63  in  FIG. 14 . Accordingly, its detailed description is omitted. 
   In step S 75  subsequent to step S 74 , the authentication processing unit  32  of the authentication server  30  verifies the authenticity of the master ticket designated as the parameter of the authentication ticket issuance method in the same manner as step S 40  ( FIG. 6 ). If the master ticket is verified as being authentic, the process proceeds to step S 85  in which the authentication ticket issuance unit  34  generates an authentication ticket for the current user. 
   However, the master ticket may have expired. In such a case, the verification of the authenticity of the master ticket is not achieved, and steps S 75  through S 84  are performed. 
   That is, the verification processing unit  32  transmits a message that the master ticket has already expired to the authentication plug-in object  17  as response information of the authentication ticket issuance method (S 76 ). The authentication plug-in object  17  acquires the authentication information of the current user from the authentication information management table  174  in order to have the master ticket being issued (S 77 ), and calls the master ticket issuance method of the authentication processing unit  32  of the authentication server  30  using the RPC of SOAP by designating the authentication information as the parameter (S 78 ). The master ticket is issued in the same manner as steps S 35  through S 37  ( FIG. 6 ) (S 79  through S 81 ). 
   In step S 82 , the authentication method  171  of the authentication plug-in object  17  updates the expired master ticket registered in the master ticket management table  175  with the newly acquired master ticket. The authentication method  171  of the authentication plug-in object  17  calls the master ticket issuance method using the RPC of SOAP designating the newly acquired master ticket as the parameter (S 83 ). 
   The authentication processing unit  32  of the authentication server  30  verifies the authenticity of the master ticket (S 84 ). If the authenticity is verified, error processing ends, and the authentication ticket issuance unit  34  generates the authentication ticket in the same manner as step S 75  in which the authenticity of the master ticket is verified (S 85 ). 
   In step S 86  subsequent to step S 85 , the authentication processing unit  32  outputs the authentication ticket generated by the authentication ticket issuance unit  34  to the SOAP processing unit  31  as response information of the authentication ticket issuance method. The SOAP processing unit  31  serialized the authentication ticket, and transmits a SOAP message including the serialized authentication ticket as response information to the authentication plug-in object  17 . 
     FIG. 20  shows an exemplary SOAP message including response information of the authentication ticket issuance method. The SOAP message  66  of  FIG. 20  is configured in the same manner as the SOAP message  64  of  FIG. 15 . Thus, its detailed description is omitted. 
   In step S 87  subsequent to step S 86 , the authentication method  171  returns the de-serialized authentication ticket to the plug-in controller  13  as response information. 
   As a result of the above process, the plug-in controller  13  has acquired the authentication ticket for the document delivery server  50  for the current user. Then, the plug-in controller  13  requests the document delivery plug-in manager  16  to provide the document delivery plug-in object  19  by calling the plug-in acquisition method (getplugin( )) of the document delivery plug-in manager (S 88 ). The process from step S 88  to S 102  is basically identical to the process from step S 44  to S 57  ( FIG. 7 ) except for the fact that the document delivery service (document delivery server  30 ) is the service to be used. 
   The document delivery plug-in manager  16  requests the document delivery plug-in object  19  made into an instance in step S 64  to establish a session with the document delivery server  50  using the authentication ticket as the parameter (S 89 ). The document delivery plug-in object  19  calls the session establishment method (startSession( )) of the document delivery server  50  designating the authentication ticket issued based on the master ticket retained in the master ticket management table  175  as the parameter using the RPC of SOAP (S 90 ). 
   In the document delivery server  50 , the authentication ticket verification unit  53  determines whether, for example, the current user being the owner of the authentication ticket is permitted to use the document delivery server  50  by verifying the authentication ticket designated as the parameter of the session establishment method (S 91 ). 
   It is noted that in the case in which the account of the current user for the document delivery server  50  is generated under the same user name as the account for the document management server  40 , the user who has been authenticated for the document management server  40  would be probably authenticated for the document delivery server  50 . 
   If the current user is verified to be permitted to use the document delivery server  50 , the document delivery unit  52  of the document delivery server  50  establish a session, and transmits a message that the session has been established to the document delivery plug-in object  19  as response information of the session establishment method (S 92 ) The document delivery plug-in object  19  returns the message that the session has successfully established to the document delivery plug-in manager  16  (S 93 ). The document delivery plug-in object  19  is returned from the document delivery plug-in manager  16  to the Web application  12  via the plug-in controller  13  (S 94 , S 95 ). 
   In response to acquisition of the document delivery plug-in object  19 , the Web application  12  requests the document delivery plug-in object  19  to deliver the document data (S 96 ). The document delivery plug-in object  19  requests the document delivery server  50  to deliver the document data by calling the document delivery method of the document delivery unit  52  of the document delivery server  50  using the RPC of SOAP (S 97 ). 
   The document delivery unit  52  delivers the document data (S 98 ), and transmits information related to the result of the delivery of the document data (hereinafter referred to as “delivery result information”) to the document delivery plug-in object  19  as response information of the document delivery method (S 99 ). 
   The document delivery plug-in object  19  returns the received delivery result information to the Web application  12  (S 100 ). In response to the returning, the Web application  12  generates a Web page (hereinafter referred to as “result notification page”) for displaying the delivery result information (S 101 ). The result notification page is transmitted from the Web application  12  to the terminal  20  via the Web server program  11 , and is displayed by the Web browser of the terminal  20  (S 102 ). 
   In step S 91 , in the case of the accounts of the current user for both servers are different, even if the user is authenticated for the document management server  40 , the authentication of the user for the document delivery server  50  may be rejected. Thus, the log-in page is transmitted to the terminal  20  again to request the user to input the authentication information for the document delivery server  50 . If the user inputs the authentication information for the document delivery server  50 , the same steps as those from step S 28  ( FIG. 6 ) are performed. As a result, a new master ticket is issued based on the input authentication information, and an authentication ticket is issued based on the issued master ticket. The user can use the document delivery server  50  with the authentication ticket. If another request for using the SOAP server is made afterward, the master ticket issued for the use of the document management server  40  and the master ticket issued for the use of the document delivery server  50  are used for authentication one by one. 
   As described above, in the case of the Web system  1  according to an embodiment, the authentication information used for the issuing of the master ticket in the past is retained in the authentication information management table  174 . According to this arrangement, even if the master ticket expires, and a new master ticket needs to be issued, it is not necessary to request the user to input the authentication information again. 
   If the user has been using the function of the document management server  40  and intends to additionally use the function of the document delivery server  50 , the authentication of the document delivery server  50  is performed based on the authentication information input for the use of the function of the document management server  40  and the master ticket issued based on the authentication information. According to this arrangement, the user does not need to input the authentication information again. The user does not need to spend time to input the authentication information again. 
   According to the present embodiment, two types of tickets, the master ticket and the authentication ticket, are used. However, even if only the master ticket is used, the same effect as that of the present embodiment can be realized. 
   Recently, embedded systems dedicated for specific purposes that function as Web servers, for example, in the same manner as a computer does are provided. An image processing apparatus called a multi function peripheral (MFP) having multiple functions such as printing, copying, and facsimile is a kind of the embedded system. The recently available image processing apparatuses may function as Web servers, and store (document management function) document data that are copied, or received as facsimile messages. 
   Accordingly, if the Web system  1  according to the present embodiment is configured with such image processing apparatuses, the same effect can be realized.  FIG. 21  is a network diagram showing the configuration of a Web system in which such image processing apparatuses are used. In  FIG. 21 , the same components as those of  FIG. 1  are referred to by the same reference numerals, and their description is omitted. 
   Compared with the Web system  1  of  FIG. 1 , a Web system  400  of  FIG. 21  includes image processing apparatuses  410 ,  420 , and  430  instead of the Web server  10 , the authentication server  30 , the document management server  40 , and the document delivery server  50 . 
   The image processing apparatus has Web server function  411  corresponding to the functions installed in the Web server  10 , that is, the Web server program  11 , the Web application  12 , the plug-in controller  13 , the plug-in managers, the plug-in objects, for example, and the authentication service  35  installed in the authentication server  30 . 
   The image processing apparatus has the same document management service  45  as the document management server  40 . The image processing apparatus  430  has the same document delivery service  55  as the document delivery server  50 . As a result, the image processing apparatus  410  functions in the same manner as the Web server  10  and the authentication server do. The image processing apparatus  420  functions in the same manner as the document management server  40  does. The image processing apparatus  430  functions in the same manner as the document delivery server  50  does. The Web system  400  according to an embodiment can realize the effect of the present invention in the same manner as the Web system  1 . 
   The document management function and the document delivery function are closely associated with the image processing apparatus. All the functions may be installed in each image processing apparatus, rather than being distributed to the multiple image processing apparatuses. 
   The preferred embodiments of the present invention are described above. The present invention is not limited to these embodiments, but variations and modifications may be made without departing from the scope of the present invention. 
   This patent application is based on Japanese priority patent application No. 2003-291046 filed on Aug. 11, 2003, the entire contents of which are hereby incorporated by reference.