PATENT ABSTRACT
An instant messaging communication system including information terminals and an instant messaging server is provided. The information terminals are configurable for use by searching users or search target users. The information terminal of a searching user acquires, from the instant messaging server, search target user information, and searches the search target user information for a search target user matching a profile created by the searching user. The information terminal of a search target user registers the search target user profile with the instant messenger server. The instant messenger server is a conduit among the searching users and the search target users, automatically sending updated information to the searching users upon registering a new search target user or updating the information of a search target user. Because the terminals perform the search and the server acts as a conduit, reliability and efficiency of the instant messenger network is improved.

PATENT DESCRIPTION
BACKGROUND OF THE INVENTION 
   The present invention relates to an information terminal capable of exchanging messages via a network, and also to a server and a program for providing a service required by the information terminal for exchange of messages. 
   With the recent diffusion of the Internet, there is noticed an increase in the number of users who transfer various data to and/or from partners through the Internet. A known system adapted for such transfer of data is, for example, an IM (Instant Messaging) system which transfers text information via the Internet and performs communication in real time with partners. 
   In the conventional IM system, at the time of connection via the Internet, there are automatically displayed, on the terminal screen in use, the state of connection of a pre-registered partner to the Internet, and any message from the partner, wherein messages are exchanged in real time, or a chat or file is sent (e.g., as described in Cited non-patent reference 1). 
   Also in the IM system, personal information of each user registered in an IM server is provided for some other user who is in a formed relation of exchange. For example, in case a user A and a user B have formed a relation of exchange, the user B is registered as a buddy of the user A on a buddy list for the user A, while the user A is registered as a buddy of the user B on a buddy list for the user B. 
   In forming a relation of exchange, one user (e.g., user A) transmits an “invitation” to the other user (e.g., user B), and the user B having received the “invitation” transmits a “consent” in the case of accepting the “invitation” from the user A (i.e., in the case of forming a relation of exchange). 
   When the user A invites the user B, it is necessary for the user A to know the ID of the user B. And when the user B sends a “consent” to the user A, it is necessary for the user B to know the ID of the user A. For acquiring the ID, both persons negotiate directly with each other to tell the respective ID mutually. 
   In another known method, the personal information of each user is saved in the IM server, and one user as a searching person searches the ID of the other user who is an interesting target person for the searching user, and the result of such a search is sent as a reply to the terminal of the searching person. More specifically, a search condition is given from the terminal of the searching user to the IM server, so that the IM server can collate the given search condition with the personal information of each user to thereby find out some user who satisfies the given search condition. 
   [Cited Non-patent Reference 1] 
   Digital Creators Liaison Conference, Multimedia Internet Dictionary, “Instant Messaging”, [online], [Searched Aug. 4, 2003], Internet, &lt;URL:
     http://www.kaigisho.ne.jp/literacy/midic/data/k2/k2122.ht m&gt;   

   However, in the conventional search system, the information that satisfies the search condition is retrieved, at the time of input of the search condition by the searching user, from the personal information stored in the database of the IM server, and then the retrieved personal information is sent to the searching user. Therefore, even in case the personal information in the database of the IM server is changeable in real time, if the result of the search has once been sent to the searching user, the updated contents of the database are not reflected on the search result given to the searching user. Thus, there arises a problem that, if some user adapted for satisfying the search condition has appeared after execution of the search, the searching user fails to be notified of the fact. 
   Moreover, since all searches are executed wholly in the IM server, loads are concentrated on the IM server so that, particularly at a time of congestion, there may occur a fall of the reply efficiency as viewed from the searching users. 
   SUMMARY OF THE INVENTION 
   The present invention has been accomplished in view of the circumstances mentioned above. And it is an object of the invention to provide improvements in an information terminal, a server and a program, wherein entire loads for processing exchange of messages are dispersed in the server and the information terminals of users, so that concentration of loads on the server alone can be avoided to consequently achieve enhancement in both the reliability (usability) and the reply efficiency of a service. 
   And another object of the present invention resides in providing an information terminal, a server and a program adapted for executing a search of a message exchange partner always on the basis of the updated latest information. 
   According to a first aspect of the present invention, there is provided an information terminal. This terminal includes a user information provider for transmitting, via a network to a server which provides a service for searching a message exchange partner, user information inclusive of ID information to indicate a service utilizing purpose of the self user, and enabling the server to register the transmitted user information therein; a user information acquirer for acquiring, from the server via the network, the user information of the other user logged in currently to the service; an ID information setter for setting the ID information indicative of the service utilizing purpose of the self user; a detailed information memory for storing detailed information of a searching condition or a searched condition of the self user; a detailed information memory for storing detailed information of a searching condition or a searched condition of the self user; a searched condition acquirer for collating the ID information in the user information of the other user acquired by the user information acquirer, with the ID information of the self user set by the ID information setter, and acquiring, via the network, the detailed information of the searched condition stored in the detailed information memory of the coincident other user; and a decider for collating the detailed information of the searched condition acquired by the searched condition acquirer, with the detailed information of the searching condition stored in the detailed information memory of the self user, and deciding, as a message exchange partner, the other user who satisfies the predetermined condition of coincidence. 
   In the present invention, the requirements for the server are merely to transmit and/or receive the user information to and/or from the information terminal of each user and then to manage such user information of each user, wherein collation of the ID information, which is included in the user information and indicates the service utilizing purpose, is executed in the information terminal of the searching user. Further, the information terminal of the searching user acquires the detailed information of the searched condition directly from the information terminal of the other user via the network, and then collates the acquired detailed information of the searched condition with the detailed information of the self user&#39;s searching condition. Therefore, the entire loads for processing exchange of messages are dispersed in the server and the information terminals of the users to consequently avoid concentration of the loads on the server alone, hence improving the reliability (usability) of the service and the reply efficiency thereof. 
   In the information terminal of the present invention, whenever any new user information has been registered in the server by the other user, the user information acquirer may acquire the registered user information of the other user from the server via the network. Whereby the information terminal of the searching user is rendered capable of searching the message exchange partner on the basis of the latest information even after its log in. 
   Also in the information terminal of the present invention, whenever any user information of the other users registered already in the server has been updated, the user information acquirer may acquire the user information of the other user from the server via the network, whereby the information terminal of the searching user is rendered capable of searching the message exchange partner on the basis of the updated latest information even after its log in. 
   Further in the information terminal of the present invention, the user information includes connection information necessary for connection to the self user via the network, and the searched condition acquirer is connected to the other user on the basis of the connection information, and acquires the detailed information of the searched condition, which is stored in the detailed information memory of the relevant other user, via the network. That is, the information terminal of the searching user is rendered capable of transferring the detailed information of the searched condition, on the basis of the connection information, by peer-to-peer connection to the information terminal of the target other user. 
   According to a second aspect of the present invention, there is provided a server for providing, via a network, a service for searching a message exchange partner to each user of the information terminal. This server includes a user information manager for acquiring, from the information terminal of the user logged in to the service, user information inclusive of ID information indicating a service utilizing purpose, and managing the acquired user information; and a user information distributor for distributing the user information of the user managed in the user information manager, to the information terminals of the other users logged in currently. 
   The requirements for the server of the present invention are merely to transmit and/or receive the user information to and/or from the information terminal of each user and to manage such user information of each user, hence avoiding concentration of the loads on the server alone to consequently improve the reliability (usability) of the service and the reply efficiency thereof. 
   Also in the server of the present invention, whenever any new user information has been registered in the user information manager, the user information distributor may distribute the registered user information to the information terminals of the other users logged in currently to the service. As a result, the information terminal of the searching user becomes capable of searching the message exchange partner on the basis of the latest information even after its log in. 
   Further in the server of the present invention, whenever any of the user information managed by the user information manager has been updated, the user information distributor may distribute the updated user information to the information terminals of the other users logged in currently to the service. As a result, the information terminal of the searching user becomes capable of searching the message exchange partner on the basis of the updated information even after its log in. 
   And according to a third aspect of the present invention, there is provided a program for enabling a computer to function as: a user information provider for transmitting, via a network to a server which provides a service for searching a message exchange partner, user information inclusive of ID information to indicate a service utilizing purpose of the self user, and enabling the server to register the transmitted user information therein; a user information acquirer for acquiring, from the server via the network, the user information of the other user logged in currently to the service; an ID information setter for setting the ID information indicative of the service utilizing purpose of the self user; a detailed information memory for storing detailed information of a searching condition or a searched condition of the self user; a searched condition acquirer for collating the ID information in the user information of the other user acquired by the user information acquirer, with the ID information of the self user set by the ID information setter, and acquiring, via the network, the detailed information of the searched condition stored in the detailed information memory of the coincident other user; and a decider for collating the detailed information of the searched condition acquired by the searched condition acquirer, with the detailed information of the searching condition stored in the detailed information memory of the self user, and deciding, as a message exchange partner, the other user who satisfies the predetermined condition of coincidence. 
   Therefore, the functional requirements for the server are merely to transmit and/or receive the user information to and/or from the information terminal of each user, and to manage such user information. Meanwhile, collation of the ID information, which is included in the user information and indicates the service utilizing purpose, is executed in the user&#39;s information terminal having a computer where the program of the present invention is installed. And in the user&#39;s information terminal having a computer with the program of the present invention installed therein, the detailed information of the searched condition is acquired directly from the information terminal of the other user via the network, and the detailed information of the searched condition thus acquired is collated with the detailed information of the self user&#39;s searching condition. Thus, the loads necessary for exchange of messages are dispersed in the server and the information terminals of the users to consequently avoid concentration of the loads on the server alone, hence improving the reliability (usability) of the service and the reply efficiency thereof. 
   As described above, according to the present invention, the entire loads for processing exchange of messages are dispersed in the server and the information terminals of the users, and concentration of the loads on the server alone can be avoided to eventually achieve enhancement in the reliability (usability) of the service and the reply efficiency thereof. Further, it becomes possible for any user to search a message exchange partner on the basis of the latest information even after log in. 
   The above and other features and advantages of the present invention will become apparent from the following description which will be given with reference to the illustrative accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an overall block diagram showing the whole structure of an IM communication system according to a first embodiment of the present invention; 
       FIG. 2  is a diagram showing a composition of user information managed on a user management database in  FIG. 1 ; 
       FIG. 3  shows an example of a GUI picture used to input a searching condition in case a search category is an auction; 
       FIG. 4  shows an example of a PD (Profile Description) owned by an exhibitor in the auction; 
       FIG. 5  shows an example of a PD owned by a bidder in the auction; 
       FIG. 6  is a flowchart showing the operation of an IM client in  FIG. 1 ; 
       FIG. 7  is a flowchart showing the operation of an IM communication service executor in the IM server in  FIG. 1 ; 
       FIG. 8  is a diagram showing a display example of a search result; 
       FIG. 9  is an overall block diagram showing the whole structure of an IM communication system according to a second embodiment of the present invention; 
       FIG. 10  is a diagram showing a composition of user information managed on a user management database in  FIG. 9 ; 
       FIG. 11  shows an example of a searching person PD owned by a user who participates as a searching person in a friend search; 
       FIG. 12  shows an example of a search target person PD owned by a user who participates as a search target person in a friend search; 
       FIG. 13  is a flowchart showing the operation of an IM client in  FIG. 9 ; and 
       FIG. 14  is a flowchart showing the operation of an IM communication service executor in the IM server in  FIG. 9 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Hereinafter some preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. 
     FIG. 1  is an overall block diagram showing the whole structure of an IM communication system according to a first embodiment of the present invention. 
   As shown in this diagram, an IM communication system  100  includes an IM server  1  consisting of a computer to provide an IM communication service; client devices  2  ( 2 - 1 ,  2 - 2 , . . . ,  2 -n) which are user terminals to receive the IM communication service provided by the IM server  1 , each client device consisting of a PC (Personal Computer), a PDA (Personal Digital Assistant), a mobile telephone or the like; and a network  3  such as the Internet via which the IM server  1  and the client devices  2  are mutually connectable. 
   The IM server  1  is equipped with an IM communication service executor  11  as, e.g., middleware to execute IM communication service. Each client device  2  is equipped with an IM client  20  as, e.g., middleware to receive the IM communication service provided by the IM communication service executor  11  in the IM server  1 . 
   In the IM server  1 , the IM communication service executor  11  sets a room  13  as a virtual place where users of plural client devices  2  start to search partners for communication via the network  3 . Also the IM communication service executor  11  manages, on a user management database  12 , the user information related to users who are capable of utilizing the IM communication service. 
     FIG. 2  is a diagram showing a composition of the user information  30  managed on the user management database  12 . As shown in this diagram, the user information  30  is composed of user ID  31 , end point information  32 , a PSID (Profile Space ID) list  33 , presence information  34 , nicknames  35  and so forth. 
   The user ID  31  is an ID given uniquely to an individual user capable of utilizing the IM communication service. The end point information  32  indicates an application operating on the user&#39;s client device  2  and becoming a partner for communication. The PSID list  33  is a list of PSID held by the user. PSID (Profile Space ID) signifies a search category such as “auction”, “friend search” or the like. In other words, this PSID is identification information indicative of a service utilizing purpose. The presence information  34  signifies the present connection state (online/offline, etc.) of the user. And the nickname  35  is a common name determined optionally by the user himself. 
   The IM communication service executor  11  has a function of first acquiring the user information  30  from the IM client  20  of the user logged in as a search target person to the room  13 , then storing the acquired user information  30  in the user management database  12 , and managing the same therein. 
   Also the IM communication service executor  11  has a function of replying the user information  30  of the search target person managed on the user management database  12 , in response to an acquisition request sent from the IM client  20  of the user logged in as a searching person to the room  13 . 
   Further the IM communication service executor  11  has a function of, upon occurrence of every log-in of a new user as a search target person, distributing the user information of the new search target person to the IM clients  20  of the entire searching persons logged in currently to the room  13 . 
   Here, the user of the IM client  20  can selectively decide as to whether he becomes a searching person or a search target person when, for example, logging in to the room  13 . And according to the information of this selection, the IM communication service executor  11  in the IM server  1  manages as to whether each of the individual users logged in currently to the room  13  is a searching person or a search target person. 
   Meanwhile, the IM client  20  of the client device  2  has an IM communicator  21 , a search condition input  22 , a search engine  23 , a search result display  24 , and a PD saver  25 . 
   In the PD saver  25 , detailed information of the user&#39;s searching condition or searched condition is stored as PD (Profile Description). In particular, when the user logs in to the room  13  as a searching person, detailed information of the searching condition needs to be stored as PD for a searching person in the PD saver  25 ; and when the user logs in to the room  13  as a search target person, detailed information of the searched condition needs to be stored as PD for a search target person in the PD saver  25 . 
   The IM communicator  21  executes a process of IM communication between the IM communication service executor  11  of the IM server  1  and the IM client  20  of the other client device  2 . More specifically, the IM communicator  21  receives, from the IM communication service executor  11  of the IM server  1 , the user information  30  of the search target person logged in currently to the room  13 , and processes the peer-to-peer communication with the IM client  20  of the search target person. 
   The search condition input  22  gives the searching condition, which has been inputted from the searching person or user via an application  26 , to the search engine  23 . More specifically, the application  26  displays a GUI (Graphical User Interface) picture for input of the searching condition on the display  28  of the client device  2 , then the search condition input  22  reads in the data of the searching condition inputted by the user through manipulation of an input unit  27  on the GUI picture, and gives such data of the searching condition to the search engine  23 . 
     FIG. 3  shows an example of a GUI picture  40  for input of the searching condition in case the search category is “auction”. As shown here, the GUI picture  40  for input of the searching condition includes input columns  41 - 45  for inputting data such as PSID, kind of exhibited article, brand name, year of use, quality and so forth. When the user depresses an OK button  46  after inputting desired data into these columns  41 - 45  by manipulating the input unit  27 , then the data inputted into the columns  41 - 45  are delivered to the search engine  23  via the search condition input  22 . 
   The search engine  23  has a function of searching the desired subject person, who is one of the search target persons and is coincident with the PSID in the searching condition inputted from the searching person via the search condition input  22 , out of the PSID list  33  included in the user information  30  of the search target persons acquired from the IM communication service executor  11  of the server  1  via the IM communicator  21 . 
   Further, in accordance with the user information  30  of the search target person coincident in regard to the PSID, the search engine  23  requests the IM client  20  of the search target person to transmit the PD (Profile Description) via the IM communicator  21 , and then collates the received reply PD of the search target person with the self PD (of the searching person) saved in the self PD saver  25 . 
     FIG. 4  shows exemplary contents of a PD  50  owned by an exhibitor (searched person) in an “auction”. As shown here, in the PD  50  of the exhibitor, there are described some integral values or ranges thereof which signify the contents determined by each exhibitor with regard to plural data items, such as kind of exhibited article, brand name, year of use, price, quality and so forth. 
     FIG. 5  shows exemplary contents of a PD  60  owned by a bidder (searching person) in an “auction”. As shown here, in the PD  60  of the bidder, there are described some integral values or ranges thereof which signify the contents determined by each bidder with regard to plural data items, such as kind of a desired bid article, brand name, year of use, price, quality and so forth. 
   The search engine  23  collates the PD  50  of the search target person with the self PD  60  (of the searching person) in respect of each data item, then acquires, as a result of the search, the search target person having the coincident contents of the data items, subsequently requests the IM client  20  of the search target person to register the self (searching person), and receives a reply therefrom. 
   The search result display  24  displays the search result, which has been obtained from the search engine  23 , on a display unit  28 . 
   Further in the client device  2 , there is installed an application  26  for internally communicating with the IM client  20  and executing a specific processing routine by the use of the information acquired externally by the IM client  20 . This application  26  is one represented by the end point information  32 . 
   Now an explanation will be given on the operation of the IM communication system  100  according to this embodiment. 
     FIG. 6  is a flowchart showing the operation of an IM client  20 , particularly the operation of an IM client  20 A of a searching person and that of an IM client  20 B of a search target person. And  FIG. 7  is a flowchart showing the operation of the IM communication service executor  11  in the IM server  1 . 
   First a user, who desires to be a search target person, sends a log-in request to the room  13  which is set by the IM communication service executor  11  in the IM server  1  (step  601 ). Upon reception of such a log-in request from the search target person (step  701 , YES at step  702 ), the IM communication service executor  11  in the IM server  1  executes a log-in process that authenticates the ID and the password included in the received log-in request, and replies the result of the authentication to the IM client  20 B (step  703 ). 
   The user as a search target person confirms a success in logging in to the room  13  through the picture on the display unit  28  or the like, and then sets end point information  32  and a PSID list  33 , which are to be registered as user information  30 , in the user management database  12  of the IM server  1  (step  602 ). After completion of such setting, the IM client  20 B transmits, via the IM communicator  21 , the set user information to the IM communication service executor  11  of the IM server  1  together with a registration request (step  603 ). 
   Upon reception of such a registration request (YES at step  704 ), the IM communication service executor  11  of the IM server  1  registers both the registration request and the received user information in the user management database  12  (step  705 ). 
   Thereafter, regardless of a request from the IM client  20 A of the searching person, the IM communication service executor  11  of the IM server  1  transmits the user information of the search target person, which has been registered newly in the user management database  12 , to the IM client  20 A of the search target person (step  709 ). 
   Meanwhile, in case the user desiring to be a searching person has sent a log-in request to the room  13  via the IM client  20 A (step  621 ), the IM communication service executor  11  in the IM server  1  accepts the log-in request from the searching person (YES at step  702 ), then executes a log-in process that authenticates the ID and the password included in the received log-in request, and replies the result of the authentication to the IM client  20 A (step  703 ). 
   Upon reception of a notice that signifies a success of logging in to the room  13  from the IM communication service executor  11  of the IM server  1 , the IM client  20 A of the searching person displays, on the screen of the display unit  28 , a GUI picture  40  for inputting a search condition as shown in  FIG. 3  for example, thereby urging the user to input the search condition including the PSID. When the searching person has inputted the search condition inclusive of the PSID on the GUI picture  40  and has depressed the OK button  46 , the search condition including the PSID and inputted onto the GUI picture  40  is taken in by the search condition input  22  and then is delivered to the search engine  23  (step  622 ). And after completion of setting the search condition in the search engine  23 , the IM communicator  21  sends a request for acquisition of the user information of the search target person to the IM communication service executor  11  of the IM server  1 . 
   Upon reception of the request for acquiring the user information of the search target person (YES at step  708 ), the IM communication service executor  11  of the IM server  1  transmits the user information of the entire search target persons, who are currently registered in the user management database  12 , to the IM client  20 A of the request-source searching person (step  710 ). 
   After the user information of the search target persons transmitted from the IM communication service executor  11  of the IM server  1  has been received by the IM communicator  21  (step  623 ), the IM client  20 A of the searching person enables the search engine  23  to execute a search, with regard to the received user information  30  of the entire search target persons, to find any search target person whose PSID is coincident with the PSID in the search condition inputted from every user via the search condition input  22  (step  624 ). 
   When any search target person with the coincident PSID has been found (YES at step  625 ), the search engine  23  instructs the IM communicator  21  to acquire the target person PD (e.g., PD  50  in  FIG. 4 ) owned by the relevant search target person. Then, in compliance with this instruction, the IM communicator  21  sends a request to the IM client  20 B of the relevant search target person for acquiring the target person PD (step  626 ). 
   In case any search target person with the coincident PSID has not been found at step  625  (NO at step  625 ), the IM client  20 A of the searching person enables the IM communicator  21  to send a request again to the IM communication service executor  11  of the IM server  1  for acquiring the user information of the search target person, and after receiving a reply (step  623 ), the IM client  20 A enables the search engine  23  to search any search target person having the coincident PSID of the searching condition (step  624 ). And the processing routine of steps  623 ,  624  and  625  is repeated until any search target person with the coincident PSID of the searching condition is found. 
   In response to the request for acquiring the PD (step  604 ), the IM client  20 B of the search target person reads out the target person PD from the PD saver  25 , and transmits the PD via the IM communicator  21  to the IM client  20 A of the searching person who is a PD request source (step  605 ). 
   Upon reception of the search target person PD (step  627 ), the IM client  20 A of the searching person enables the search engine  23  to collate the contents of the search target person PD with the the contents of the searching person PD (e.g., PD  60  in  FIG. 5 ), which is saved in the self PD saver  25 , with regard to every corresponding data item (step  628 ), and if any search target person having more than one data item of a coincident value has been found (YES at step  629 ), then the IM client  20 A sends a request via the IM communicator  21  to the IM client  20 B of the relevant search target person to register the self searching person. 
   In case the collation result obtained at step  628  signifies that there is no data item with any coincident value (NO at step  629 ), the IM client  20 A of the searching person enables the IM communicator  21  to send a request again to the IM communication service executor  11  of the IM server  1  for acquiring the user information of the search target persons. And thereafter the processing routine of step  623  to step  629  is repeated until data items with coincident values are found in the collation at step  628 . 
   The IM client  20 B of the search target person having received the registration request registers the searching person, who is a registration requester, as a communication partner, and then sends back a reply to the IM client  20 A of the searching person (step  606 ). 
   Subsequently in the IM client  20 B of the search target person, a decision is made by the user as to whether there is any change in the user information (step  607 ). And if the result of this decision signifies no change, the operation proceeds to step  608 . In case the result of the decision signifies any change, the operation returns to step  602  where the user information is set. And at step  608 , a decision is made by the user whether the detailed information is to be provided or not. 
   Meanwhile, upon reception of the reply indicative of completion of the registration from the IM client  20 B of the search target person, the IM client  20 A of the searching person registers the search target person as a search result of a communication partner, and displays the search result on the display unit  28 .  FIG. 8  shows a display example of some search result. As shown here, the search result is displayed as a list of the user information of the searched target persons. Thereafter, peer-to-peer communication can be performed between the IM client  20 A of the searching person and the IM client  20 B of the search target person. 
   In case the search category is “auction”, the searching person is permitted thereafter to request the searched target person for acquiring the detailed information of any exhibited article (YES at step  633 , step  634 ). The detailed information includes the image of an exhibited article, description of detailed specifications and so forth, such as HTML (Hyper Text Markup Language) type for example. The detailed information is processed by the application  26  such as Web browser installed in the client device  2 , and is displayed on the display unit  28 . 
   In response to the request from the IM client  20 A of the searching person for acquisition of the detailed information (step  610 ), the IM client  20 B of the search target person transmits the detailed information to the IM client  20 A of the searching person (step  611 ) in case the decision at step  608  is so set as to provide the detailed information (YES at step  608 ). 
   In another case where the decision is so set as not to provide the detailed information (NO at step  608 ) in the IM client  20 B of the search target person, the detailed information is not transmitted to the relevant searching person, and the IM client  20 B stands by for a request of PD acquisition from a next searching person (step  609 ). 
   The IM client  20 A of the searching person having received the detailed information delivers the received detailed information to the application  26  such as Web browser installed in the client device  2  (step  635 ). The application  26  having thus received the detailed information converts the detailed information into another format readable on the browser screen of the display unit  28 , and then provides the converted information to the user (step  636 ), whereby the user, i.e., the searching person, is notified of the detailed information of the exhibited article. 
   Instead of a request for acquiring the detailed information from the search target person searched this time (NO at step  632 ), the searching person is capable of instructing the IM server  1 , by means of the input unit  27 , to request the IM client  20 A for re-acquisition of the user information of the search target person. Consequently, in the IM client  20 A of the searching person, the processing routine subsequent to step  623  is repeated. Therefore, if the contents of the user management database  12  in the IM server  1  has been updated after the preceding request for acquisition of the user information, it is possible for the IM client  20 A of the searching person to acquire, at step  623 , the latest user information of the search target person that represents the reply result reflecting the updated contents, and at step  624 , a search for a different search target person is executed by the search engine  23 . 
   Prior to sending an instruction for a request for re-acquisition of the user information of the search target person, the user is capable of recalling, whenever necessary, the searching condition input GUI picture  40 , such as that shown in  FIG. 3 , onto the display unit  28 , and re-setting the searching condition inclusive of the PSID on the GUI picture  40  (YES at step  633 , step  622 ). Consequently, at step  624 , a search for a target person can be executed under different searching condition by the search engine  23 . 
   When the IM client  20 B of the search target person needs to change the self user information registered in the user management database  12  of the IM server  1  (YES at step  607 ), the IM client  20 B changes the internal user information in the client device  2  at step  602 , and then transmits a change request, inclusive of the changed user information, to the IM communication service executor  11  of the IM server  1  (step  603 ). 
   In response to the request for changing the user information (YES at step  706 ), the IM communication service executor  11  of the IM server  1  rewrites the corresponding user information in the user management database  12  with the changed user information included in the change request (step  707 ). Thereafter, the IM communication service executor  11  of the IM server  1  transmits the changed user information to the IM client  20 A of the searching person without conforming to a request from the IM client  20 A of the searching person (step  709 ). Then the IM client  20 A of the searching person delivers the received user information  30  to the search engine  23 , and enables the search engine  23  to execute a search for a target person having the coincident PSID (step  624 ). 
   The processing routine of the IM communication service executor  11  of the IM server  1  shown in  FIG. 7  is executed in response to every request received from each of the IM clients  20 A and  20 B, such as a request for log-in, a request for registration of user information, a request for change of user information, a request for acquisition of user information and so forth. 
   Thus, in the IM communication system  100  of this embodiment, the IM client  20  behaves as either an IM client  20 A of a searching person or an IM client  20 B of a search target person. The IM client  20 B of the search target person registers the user information inclusive of a self PSID list in the user management database  12  of the IM server  1 . The IM client  20 A of the searching person acquires, from the IM server  1 , the user information inclusive of the PSID list of the search target persons registered in the user management database  12 , and then searches a target person whose PSID is coincident with the self PSID. And when the search target person has been found, the IM client  20 A requests the relevant search target person to transmit its PD, and then collates the received PD with the self PD, thereby specifying the search target person who satisfies the desired condition of the searching person. That is, in the case of “auction” for example, the searching person specifies the search target person whose exhibited article satisfies the desired condition of the bidder. 
   Therefore, according to the IM communication system  100  of this embodiment, the following advantageous effects are achieved. 
   The requirements for the IM server  1  are merely to transmit and/or receive the user information to and/or from the client device  2  of each user and to manage such user information  30  of each user, wherein collation of the PSID, which is included in the user information  30  and indicates the service utilizing purpose, is executed by the client device  2  of the user who is a searching person. Meanwhile, the client device  2  of the user who is a search target person directly acquires, from the client device  2  of some other user, the target person PD  50  via the network  3 , and collates the acquired target person PD  50  with the searching person PD  60  of the self user. Accordingly, the entire processing loads needed for exchange of messages are dispersed in the IM server  1  and each client device  2  to consequently avoid concentration of the loads on the IM server  1  alone, hence improving the reliability (usability) of the service and the reply efficiency thereof. 
   Also in the IM communication system of this embodiment, whenever new user information has been registered or changed by any search target person, the newly registered or changed user information is transmitted to the IM client  20 A of the searching person, regardless of the presence or absence of any request from the IM client  20 A of the searching person, and the processing routine subsequent to the collation of the PSID is executed by the IM client  20 A, so that it becomes possible for the IM client  20 A of the searching person to search the target person on the basis of the updated latest information even after its log in. 
   Next, an explanation will be given on another IM communication system representing a second embodiment of the present invention. 
   In this IM communication system, there is no selection of a searching person or a search target person by a user when an IM client logs in to a room. The IM client of every user having logged in to the room behaves as each IM client of both a searching person and a search target person. 
     FIG. 9  is an overall block diagram showing the whole structure of this IM communication system. 
   As shown in this diagram, an IM communication system  200  includes an IM server  201  consisting of a computer to provide IM communication service; client devices  202  ( 202 - 1 ,  202 - 2 , . . . ,  202 -n) which are user terminals to receive the IM communication service provided by the IM server  201 , each client device consisting of a PC (Personal Computer), a PDA (Personal Digital Assistant), a mobile telephone or the like; and a network  203  such as the Internet via which the IM server  201  and the client devices  202  are mutually connectable. 
   The IM server  201  is equipped with an IM communication service executor  211  as, e.g., middleware to execute IM communication service. Each client device  202  is equipped with an IM client  220  as, e.g., middleware to receive the IM communication service provided by the IM communication service executor  211  in the IM server  201 . 
   In the IM server  201 , the IM communication service executor  211  sets a room  213  as a virtual place where users of plural client devices  202  start to search opposite persons for communication. Also the IM communication service executor  211  manages, on a user management database  212 , the user information related to users who are capable of utilizing the IM communication service. 
     FIG. 10  is a diagram showing a composition of the user information  230  managed on the user management database  212 . As shown in this diagram, the user information  230  is composed of user ID  231 , end point information  232 , a list  233  of PSID (Profile Space ID) for search target persons, presence information  234 , nicknames  235  and so forth. 
   The user ID  231  is an ID given uniquely to an individual user capable of utilizing the IM communication service. The end point information  232  indicates an application operating on the user&#39;s client device  202  and becoming an opposite person for communication. The PSID list  233  for search target persons is a list of PSID held by the user as a search target person. PSID (Profile Space ID) signifies a search category such as “auction”, “friend search” or the like. In other words, this PSID is identification information indicative of a service utilizing purpose. The presence information  234  signifies the present connection state (online/offline, etc.) of the user. And the nickname  235  is a common name determined optionally by the user himself. 
   The IM communication service executor  211  has a function of acquiring the user information  230  from the IM client  220  of the user logged in to the room  213 , storing the user information  230  in the user management database  212 , and managing the user information  230 . 
   Also the IM communication service executor  211  has a function of transmitting, to the IM client  220  of the user logged in to the room  213 , the user information  230  of the other entire users managed on the user management database  212 . 
   Further, the IM communication service executor  211  has a function of transmitting, upon occurrence of every log-in of a new user, such user information  230  to the IM clients  220  of the other entire users logged in currently to the room  213 . 
   Meanwhile, the IM client  220  of the client device  202  has an IM communicator  221 , a searching person PSID memory  223 , a search engine  224 , a search result display  225 , and a PD saver  226 . 
   In the PD saver  226 , detailed information of the user&#39;s searching condition and searched condition is stored as PD (Profile Description) for a searching person and PD for a search target person. 
   The IM communicator  221  executes a process of IM communication between the IM communication service executor  211  of the IM server  201  and the IM client  220  of the other client device  202 . More specifically, the IM communicator  221  receives, from the IM communication service executor  211  of the IM server  201 , the user information  230  of the other user logged in currently to the room  213 , and processes the peer-to-peer communication with the IM client  220  of the other user. 
   The searching person PSID memory  223  stores therein a list of PSID for searching persons. 
   The search engine  224  has a function of collating the search target person PSID list  233  in the user information  230  of the other user acquired from the IM communication service executor  211  of the IM server  201 , with the searching person PSID list stored in the searching person PSID memory  223 , and searching the search target person who forms a predetermined pair with regard to the PSID of the searching person. More specifically, in case PSID=1 signifies a friend search to a searching person and PSID=2 signifies a friend search to a search target person, if “1” is stored as PSID in the searching person PSID memory  223  and “2” is included as PSID in the searching person PSID list  233  in the user information  230  of the search target person, then the relevant search target person is obtained as a result of the search. 
   Further, in accordance with the user information  230  of the searched target person, the search engine  224  requests the IM client  220  of the relevant search target person to transmit the PD (Profile Description) thereof via the IM communicator  221 , and then collates the received reply PD of the search target person with the PD of the searching person saved in the self PD saver  226 . 
     FIG. 11  shows exemplary contents of a searching person PD  250  owned by a user who participates as a searching person in “friend search”. As shown here, in the searching person PD  250 , there are described some integral values or ranges thereof which signify the contents determined by each searching person with regard to plural data items, such as sex, age or its range, native place and so forth of the search target person. 
     FIG. 12  shows exemplary contents of a search target person PD  260  owned by a user who participates as a search target person in “friend search”. As shown here, in the search target person PD  260 , there are described some integral values which signify the respective contents of plural data items, such as sex, age, native place and so forth of the search target person. 
   The search engine  224  collates the PD  250  of the searching person with the self PD  260  of the search target person in respect of each data item, then acquires, as a result of the search, the search target person having the coincident contents of the data items, subsequently requests the IM client  220  of the relevant search target person to register the self (searching person), and receives a reply therefrom. 
   The search result display  225  displays the search result, which has been obtained from the search engine  224 , on a display unit  228 . 
   Further in the client device  202 , there is installed an application  227  for internally communicating with the IM client  220  and executing a specific processing routine by the use of the information acquired externally by the IM client  220 . This application  227  is one represented by the end point information  232 . 
   Next, an explanation will be given on the operation of this IM communication system. 
     FIG. 13  is a flowchart showing the operation of an IM client  220 , particularly the operation of an IM client  220 A of a searching person and that of an IM client  220 B of a search target person. The IM client  220  of every user logged in to the room  213  behaves as both the IM client  220 A of the searching person and the IM client  220 B of the search target person.  FIG. 14  is a flowchart showing the operation of the IM communication service executor  211  in the IM server  201 . 
   First, a user sends a log-in request via the IM client  220 A or  220 B to the room  213  set by the IM communication service executor  211  in the IM server  201  (steps  1301 ,  1321 ). Upon reception of such a log-in request from the user (step  1401 , YES at step  1402 ), the IM communication service executor  211  in the IM server  201  executes a log-in process that authenticates the ID and the password included in the received log-in request, and replies the result of the authentication to the IM client  220 A or  220 B (step  1403 ). 
   After succeeding in the authentication, the IM communication service executor  211  in the IM server  201  transmits the user information  230  of the other entire users managed on the user management database  212  to the IM client  220 A or  220 B of the user logged in to the room  213  (step  1404 ). 
   The user as a search target person confirms a success in logging in to the room  213  through the picture on the display unit  228  or the like, and then sets end point information  232 , a search target person PSID list  233 , a nickname  235  and so forth, which are to be registered as user information  230 , in the user management database  212  of the IM server  201  (step  1302 ). After completion of such setting, the IM client  220 B transmits, via the IM communicator  221 , the set user information to the IM communication service executor  211  of the IM server  201  together with a registration request (step  1303 ). 
   Upon reception of such a registration request (YES at step  1405 ), the IM communication service executor  211  of the IM server  201  registers both the registration request and the received user information in the user management database  212  (step  1406 ). 
   Thereafter, the IM communication service executor  211  of the IM server  201  transmits the user information of the search target person, which has been registered newly in the user management database  212 , to the IM clients  220  of the other entire users logged in currently to the room  213  (step  1410 ). 
   The IM client  220 A of the searching person acquires the user information of the search target person transmitted from the IM server  201  (step  1322 ), and delivers the acquired user information to the search engine  224 . 
   The search engine  224  collates the search target person PSID list  233 , which is included in the acquired user information  230  of the other users, with the searching person PSID list stored in the searching person PSID memory  223  (step  1323 ), and searches the target person who forms a predetermined pair with the searching person PSID (step  1324 ). 
   Subsequently, the search engine  224  instructs the IM communicator  221  to acquire the search target person PD (e.g., PD  260  in  FIG. 12 ) owned by the searched target person. And in response to this instruction, the IM communicator  221  sends a request to the IM client  220 B of the relevant search target person for acquiring the search target person PD (step  1325 ). 
   In case the result at step  1324  signifies that any search target person to form a predetermined pair with the searching person PSID has not been found (NO at step  1324 ), the IM client  220 A of the searching person enables the IM communicator  221  to send a request to the IM communication service executor  211  of the IM server  201  for acquiring the user information of the search target person. And upon reception of such a request for acquiring the user information of the search target person (YES at step  1409 ), the IM communication service executor  211  of the IM server  201  transmits the user information of the other entire search target persons, who are currently registered in the user management database  212 , to the IM client  220 A of the request-source searching person (step  1411 ). 
   After acquiring the user information of the search target persons from the IM communication service executor  211  of the IM server  201  (step  1322 ), the IM client  220 A of the searching person enables the search engine  223  to collate again the search target person PSID list  233 , which is included in the acquired user information  230  of the other entire users, with the searching person PSID list stored in the searching person PSID memory  223  (step  1323 ). And the processing routine of steps  1322 ,  1323  and  1324  is repeated until finding a search target person who forms a predetermined pair with the searching person PSID. 
   In response to the request for acquiring the PD (step  1304 ), the IM client  220 B of the search target person reads out the target person PD from the PD saver  226 , and transmits the PD via the IM communicator  221  to the IM client  220 A of the searching person who is a PD request source (step  1305 ). 
   Upon reception of the search target person PD (step  1326 ), the IM client  220 A of the searching person enables the search engine  224  to collate the contents of the search target person PD with the the contents of the searching person PD (e.g., PD  250  in  FIG. 11 ), which is saved in the self PD saver  226 , with regard to every corresponding data item (step  1327 ), and if any search target person having more than one data item of a coincident value has been found (YES at step  1328 ), then the IM client  220 A sends a request via the IM communicator  221  to the IM client  220 B of the relevant search target person to register the self searching person. 
   In case any search target person satisfying the predetermined coincident condition has not been found (NO at step  1328 ), the IM client  220 A of the searching person enables the IM communicator  221  to send a request again to the IM communication service executor  211  of the IM server  201  for acquiring the user information of the search target persons. And thereafter the processing routine of step  1322  to step  1328  is repeated until a desired search target person satisfying the predetermined coincident condition is found in the collation at step  1328 . 
   The IM client  220 B of the search target person having received the registration request from the IM client  220 A of the searching person registers the relevant searching person, who is a registration requester, as a communication partner, and then sends back a reply to the IM client  220 A of the searching person (step  1306 ). 
   Subsequently in the IM client  220 B of the search target person, a decision is made by the user as to whether there is any change in the user information (step  1307 ). And if the result of this decision signifies no change, the operation proceeds to step  1308 . In case the result of the decision signifies any change, the operation returns to step  1302  where the user information is set. 
   Meanwhile, upon reception of the reply indicative of completion of the registration from the IM client  220 B of the search target person, the IM client  220 A of the searching person registers the search target person as a search result of a communication partner, and displays the search result on the display unit  228  (step  1330 ). 
   Thereafter, the IM client  220 A of the searching person and the IM client  220 B of the search target person can perform peer-to-peer communication. 
   In case the search category is “friend search”, subsequent exchange of IM between the searching person and the search target person can be performed by both applications  227  thereof (steps  1331 ,  1332 ,  1308  and  1309 ). 
   When the IM client  220 B of the search target person needs to change the self user information registered in the user management database  212  of the IM server  201  (YES at step  1307 ), the IM client  220 B changes the internal user information in the client device  202  at step  1302 , and then transmits a change request, inclusive of the changed user information, to the IM communication service executor  211  of the IM server  201  (step  1303 ). 
   In response to the request for changing the user information (YES at step  1407 ), the IM communication service executor  211  of the IM server  201  rewrites the corresponding user information in the user management database  212  with the changed user information included in the change request (step  1408 ). Thereafter, the IM communication service executor  211  of the IM server  201  transmits the changed user information to the IM clients  220  of the other entire users logged in currently to the room  213  (step  1410 ). Then the IM client  220 A of the searching person delivers the received user information  230  to the search engine  224 , and enables the search engine  224  to execute a search for a target person (step  1323 ). 
   The processing routine of the IM communication service executor  211  of the IM server  201  shown in  FIG. 14  is executed in response to every request received from each of the IM clients  220 A and  220 B, such as a request for log-in, a request for registration of user information, a request for change of user information, a request for acquisition of user information and so forth. 
   Thus, in this IM communication system  200 , the IM client  220  behaves as both the IM client  220 A of the searching person and the IM client  220 B of the search target person. When any user logs in to the room  213 , the user information  230  of the other entire users managed on the user management database  212  is transmitted to the IM client  220  of the user logged in. The IM client  220 A of the searching person acquires the user information of the search target person transmitted from the IM server  201 , then enables the search engine  224  to collate the search target person PSID list  233 , which is included in the acquired user information  230  of the other users, with the searching person PSID list stored in the searching person PSID memory  223 , and searches any target person who forms a predetermined pair with the searching person PSID. Subsequently, the search engine  224  acquires the search target person PD owned by the searched target person, and collates the acquired search target person PD with the searching person PD saved in the self PD saver  226 , thereby specifying the search target person who satisfies the desired condition of the searching person. That is, in the case of “friend search” for example, the search target person satisfying the condition of sex, age and so forth desired by the searching person is specified as a friend, i.e., as an IM communication partner. 
   Therefore, according to this IM communication system  200 , the following advantageous effects are achieved. 
   The information transmitted and received between the IM server  201  and each client  202  is merely the user information  230  of each user. The search target person PD  260 , which is the information necessary for specifying the search target person who satisfies the desired condition of the searching person, is transferred directly between the IM client  220 A of the searching person and the IM client  220 B of the search target person, and the collation of the search target person PD  260  with the searching person PD  250  is performed in the IM client  220 A. Therefore, it becomes possible to avoid concentration of the loads on the IM server  201  alone, hence improving the reliability (usability) of the service and the reply efficiency thereof. 
   Also in the IM communication system of this embodiment, whenever new user information has been registered or changed in the IM server  201 , the newly registered or changed user information is transmitted to the IM clients  220  of the other entire users, and the processing routine subsequent to the collation of the PSID is executed by each of the IM clients  220 , so that the IM client  220 A of the searching person is rendered capable of searing the target person on the basis of the updated latest information even after its log in. 
   It is to be understood that the present invention is not limited to the embodiments mentioned hereinabove, and it is a matter of course that a variety of other changes and modifications may be added within the scope not departing from the spirit of the present invention.