Abstract:
An apparatus, method and program for dividing a conversational dialog into utterance. The apparatus includes a computer processor; a word database for storing spellings and pronunciations of words; a grammar database for storing syntactic rules on words; a pause detecting section which detects a pause location in a channel making a main speech among conversational dialogs inputted in at least two channels; an acknowledgement detecting section which detects an acknowledgement location in a channel not making the main speech; a boundary-candidate extracting section which extracts boundary candidates in the main speech, by extracting pauses existing within a predetermined range before and after a base point that is the acknowledgement location; and a recognizing unit which outputs a word string of the main speech segmented by one of the extracted boundary candidates after dividing the segmented speech into optimal utterance in reference to the word database and grammar database.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority under 35 U.S.C. §120 to U.S. patent application Ser. No. 11/964,858 filed Dec. 27, 2007, which claims priority under 35 U.S.C. §119 to Japanese Patent Application No. 2006-350936 filed Dec. 27, 2006, the entire text of which is specifically incorporated by reference herein. 
     
    
     BACKGROUND 
       [0002]    The present invention relates to a technique for accurately detecting a system failure, and particularly relates to a technique for accurately detecting a failure in a system where a plurality of servers communicate with each other. 
         [0003]    In recent years, a large scale website is provided not by a single server but by a system including a plurality of servers. This type of system is called a multi-tier server system, and includes a servlet server for performing control over an HTTP protocol, an application server for operating a called application, a database server for performing the transaction of a database, and the like. In order to detect a failure which occurs in this type of multi-tier server system, a server for monitoring provided separately from this server group, is conventionally used. 
         [0004]    The server for monitoring regularly collects the status of a server in a system from each server. For example, the statuses of hardware such as a supply voltage, the temperature of a CPU and a CPU busy rate are collected. Thereafter, when the statuses are different from normal ones, it is judged that an anomaly is occurring in the system. However, a judgment as to an anomaly occurring in software may fail by using only this type of server for monitoring. For this reason, each server is made capable of detecting a software-based failure by measuring a time required for a transaction requested by the server to another server, and by judging whether or not the length of the required time is within a predetermined range. 
         [0005]    Refer to the following Japanese Patent Application Laid-open Publication No. 2001-282759 and Japanese Patent Application Laid-open Publication No. 2003-196178 as referential techniques related to failure detection. 
         [0006]    In the above-mentioned multi-tier server system, there is a case where a first server requests a second server for a transaction, and where the requested second server further requests a third server for the transaction. In this case, even if a transaction response returned to the first server is delayed, the first server cannot determine which one of the second and third servers has a failure. In such a case, if the first server determines that a failure occurs in the second server, and changes a transmission path for a transaction request and the like, the processing efficiency is likely to decrease unnecessarily. 
         [0007]    Furthermore, when a program which is operated on a server is written in a Java language (a registered trademark), Java middleware may regularly perform garbage collection (GC). GC is processing for releasing a memory region which is reserved by a program but is no longer used, and is carried out independently from the operations of the program, and regularly, for example. In this case, although the processing in the server is temporarily delayed, it returns to the original state immediately after GC is completed. From the viewpoint of efficient use of a system, it is inconvenient to judge such a temporal state as a failure occurring in a server. 
       SUMMARY 
       [0008]    Against this background, an object of the present invention is to provide a system, a method and a program which are capable of solving the above problems. The object can be achieved by using a combination of features recited in the independent claims in the scope of claims. In addition, the dependent claims specify more specific advantageous examples of the present invention. 
         [0009]    In order to solve the above problems, in an aspect of the present invention, provided is a system including: a plurality of dispatcher apparatuses which dispatch a transaction requested by an external terminal apparatus; a plurality of first-tier servers which process the dispatched transactions; and at least one second-tier server which processes a part of the transaction in response to a request received from the first-tier server. Each of the dispatcher apparatuses includes: a storage device which stores a status table indicating an operation status of each second-tier server; a transferring unit which transfers a transaction request received from the external terminal apparatus to a first-tier server selected from the plurality of the first-tier servers, in order to dispatch the requested transaction; a table generator which receives the operation status of each of the second-tier servers included in a transaction response corresponding to the transferred transaction request, which evaluates the operation status of each of the second-tier servers based on the received operation status, which generates a status table indicating the operation status of each of the second-tier servers, and which stores the status table in the storage device; a table transmitter which reads the generated status table from the storage device in response to the generation of the status table, and which transmits the status table to each of the first-tier servers; and a first table updating unit which updates the status table stored in the storage device by use of the received status table in response to the reception of the status table from any of the first-tier servers. Each of the first-tier servers includes: a storage device which stores a status table indicating an operation status of each second-tier servers; a request transmitter which transmits the transaction request to the second-tier server in response to the reception of the transaction request transferred from the transferring unit of one of the dispatcher apparatuses, in order to cause the second-tier server to process a part of the requested transaction; a status returning unit which returns, to the dispatcher apparatus, the status of the transaction response to the transaction request transmitted to the second-tier server, as the operation status of the second-tier server, the status of the transaction response included in the transaction response to the transaction request transferred from the transferring unit of the dispatcher apparatus; a second table updating unit which updates a status table already stored in the memory by use of the status table received from the status table from the table transmitter of the dispatcher apparatus, in response to the reception of the status table; and a table returning unit which returns the updated status table to each of the dispatcher apparatuses, in response to the update of the status table. Moreover, provided are a method for managing the status of each server by use of the system, and a program for allowing a plurality of information processing apparatuses to function as the system. 
         [0010]    Note that the above mentioned summary of the invention does not cite all the necessary characters of the present invention, and that a subcombination of the groups of these characters can be the present invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    For a more complete understanding of the present invention and the advantage thereof, reference is now made to the following description taken in conjunction with the accompanying drawings. 
           [0012]      FIG. 1  shows an example of a configuration of an information system  10 . 
           [0013]      FIG. 2  shows an entire configuration of the information system  10  according to the present embodiment. 
           [0014]      FIG. 3  shows a functional configuration of a dispatcher apparatus  100 - 1 . 
           [0015]      FIG. 4  shows a functional configuration of a servlet server  110 - 1 . 
           [0016]      FIG. 5  shows an example of a data structure of a status table stored in a storage device  300  or  400 . 
           [0017]      FIG. 6  shows a specific example of processing that the dispatcher apparatus  100 - 1  transmits and receives a transaction request and a transaction response. 
           [0018]      FIG. 7  shows a detailed example of processing in S 640 . 
           [0019]      FIG. 8  shows a specific example that the servlet server  110 - 1  transmits and receives a transaction request and a transaction response. 
           [0020]      FIG. 9  is a state transition diagram of operation statuses sequentially updated in S 860 . 
           [0021]      FIG. 10  shows a process of operation statuses sequentially updated by the information system  10  according to the present invention. 
           [0022]      FIG. 11  shows an example of a hardware configuration of an information processing apparatus  500  functioning as the dispatcher apparatus  100 - 1  or the servlet server  110 - 1 . 
       
    
    
     DETAILED DESCRIPTION 
       [0023]    Hereinafter, the present invention will be described by using an embodiment of the present invention. However, the following embodiment does not limit the present invention recited in the scope of claims, and all the combinations of features described in the embodiment are not always necessary for solving means of the present invention. 
         [0024]      FIG. 1  shows an example of a configuration of an information system  10 . The information system  10  includes dispatcher apparatuses  100 - 1  to - 2 , servlet servers  110 - 1  to - 4 , APP servers  120 - 1  to - 3 , a DB server  130 , a database  135 , a system monitor  140 , and an information sharing apparatus  150 . Each of the dispatcher apparatuses  100 - 1  to - 2  is directly connected to the servlet servers  110 - 1  to - 4 . In addition, the dispatcher apparatuses  100 - 1  to - 2  dispatch transactions requested by an external terminal apparatus to the servlet servers  110 - 1  to - 4 . 
         [0025]    For example, each of the dispatcher apparatuses  100 - 1  to - 2  may transfer transaction requests which are sequentially received to each of the servlet servers  110 - 1  to - 4  by a round-robin method. In other words, the dispatcher apparatus  100 - 1  transfers a first-received transaction request, a second-received transaction request, a third-received transaction request, and a fourth-received transaction request to the servlet server  110 - 1 , the servlet server  110 - 2 , the servlet server  110 - 3 , and the servlet server  110 - 4 , respectively. From the fifth, starting from first again, a transaction request is transferred to the servlet server  110 - 1 . 
         [0026]    Each of the servlet servers  110 - 1  to - 4  is an example of a first-tier server according to the present invention. Specifically, they are HTTP servers and the like. Furthermore, each of the servlet servers  110 - 1  to - 4  performs processing in response to transaction requests dispatched from the dispatcher apparatuses  100 - 1  to - 2 . There may be a case where a need to call a predetermined application program or to access a database arises during the processing. In such a case, each of the servlet servers  110 - 1  to - 4  further transmits transaction requests to the APP (application) servers  120 - 1  to - 3  or the DB server  130 , and causes them to process at least a part of transactions requested by an external terminal apparatus. Each of the APP servers  120 - 1  to - 3  is an example of a second-tier server according to the present invention, and processes a part of transactions requested by an external terminal apparatus in response to requests from the servlet servers  110 - 1  to - 4 . The DB server  130  may read data from the database  135  during the processing, or may update the database  135 . Incidentally, the DB server  130 , too, is an example of the second-tier server. In other words, the second-tier servers include a server which receives a request indirectly via another server/apparatus (here, the APP servers  100 - 1  to - 3 ) and processes a part of requested transactions in response to the request, other than a server which receives a request directly from the servlet server. 
         [0027]    The system monitor  140  receives data showing the status of each of the following apparatuses/servers from agent software operating in the dispatcher apparatuses  100 - 1  to - 2 , the servlet servers  110 - 1  to - 4 , the APP servers  120 - 1  to - 3 , and the DB server  130 , and the like. For example, data showing the following will be received in the system monitor  140 : a CPU utilization in each apparatus/server; an operation status of a hardware such as an access frequency of a hard disk drive; and a physical status such as temperatures of a CPU and a housing. Then, the information sharing apparatus  150  judges as to whether or not an anomaly occurs in any of the apparatuses/servers included in the information system  10  according to each pieces of data received by the system monitor  140 . Thereafter, the information sharing apparatus  150  performs processing, such as notifying the judgment result to the outside and halting the apparatus/server in which the anomaly has occurred. 
         [0028]    According to the information system  10  shown in  FIG. 1 , it is conceivable that an anomaly which has occurred in the information system  10  can be detected by monitoring the status of each apparatus/server in the information system  10 . However, there is a case where an anomaly caused mainly by software cannot be detected appropriately, due to the configuration of this type of information system  10 . For example, in a case of deadlock whose cause is a failure such as a design for software, the software itself is operating normally as designed, so that the failure occurrence cannot be detected appropriately due to the status of a CPU and the like. Moreover, the system monitor  140  and the information sharing apparatus  150  are necessary in addition to an originally necessary server/apparatus. Hence, even if the other servers/apparatuses are normal, there is a possibility that an anomaly is mistakenly detected due to the abnormalities of the system monitor  140  and the information sharing apparatus  150  themselves. 
         [0029]    On the other hand, according to the information system  10  which will hereinafter be described, it is possible to detect various kinds of abnormalities without having a bad effect on the original operations of the information system  10 , by incorporating a mechanism for detecting an anomaly into a mechanism for transmitting and receiving a transaction request and a transaction response. 
         [0030]    The descriptions will hereinafter be given in detail. 
         [0031]      FIG. 2  shows an entire configuration of the information system  10  according to the embodiment. As in  FIG. 1 , the information system  10  includes the dispatcher apparatuses  100 - 1  to - 2 , the servlet servers  110 - 1  to - 4 , the APP servers  120 - 1  to - 3 , the DB server  130 , and the database  135 . However, different from the information system  10  shown in  FIG. 1 , the information system  10  in  FIG. 2  may not include the system monitor  140  and the information sharing apparatus  150 . The overview of processing in each of the dispatcher apparatuses  100 - 1  to - 2 , the servlet servers  110 - 1  to - 4 , the APP servers  120 - 1  to - 3 , the DB server  130 , and the database  135  is the same as those described in  FIG. 1 . However, each server/apparatus performs processing for detecting an anomaly, in addition to the reception/transmission of a transaction request and a transaction response. Moreover, each server/apparatus includes a mechanism used to detect an anomaly, and this mechanism measures a time required from transmission of a transaction request to another server/apparatus until reception of the transaction response thereof. 
         [0032]      FIG. 3  shows a functional configuration of the dispatcher apparatus  100 - 1 . The dispatcher apparatus  100 - 1  has a storage device  300 , a transferring unit  310 , a table generator  320 , a table transmitter  330 , a first table updating unit  340 , and a halt judging unit  350 . Firstly, simple descriptions will be given of a relation between each of these members and hardware resources. The storage device  300  stores information necessary for each of the other members, and is realized by a RAM  1020  or a hard disk drive  1040 , both of which will be described later. The transferring unit  310  and the table transmitter  330  transmit and receive information, and are carried out by causing a CPU  1000  and a communication interface  1030 , which will be described later, to operate in accordance with an installed program. The table generator  320 , the first table updating unit  340 , and the halt judging unit  350  are to judge on the operation, processing, and condition of information, and are performed by causing the CPU  1000  described later to operate in accordance with an installed program. 
         [0033]    The memory  300  is provided to store a status table showing the operation status of each apparatus/server. Specifically, the status table indicates the operations status of each of the servlet servers  110 - 1  to - 4 , the APP servers  120 - 1  to - 3 , and the DB server  130 . In addition, the operation status is any one of a normal status, a heavy-load status in which the server is in operation but requires a time equal to or more than a threshold value for processing, an abnormal status in which the server is out of operation, a suspicious heavy-load status in which the server is suspected to be in a heavy-load status, and a suspicious abnormal status in which the server is suspected to be in an abnormal status. 
         [0034]    The transferring unit  310  transfers a transaction request received from an external terminal apparatus to one of the servlet servers  110  selected from the plurality of servlet servers  110 - 1  to - 4 , in order to dispatch the requested transaction. As described above, the selection of the servlet server  110  may be performed by the round-robin method. The table generator  320  receives the operations status of each of the APP servers  120 - 1  to - 3  and the DB server  130  included in the transaction response corresponding to the transferred transaction request. 
         [0035]    Here, the reception of the operation status included in the transaction response is preferably the information which indicates a time required for processing requested by the servlet servers  110 - 1  to - 4  to the APP servers  120 - 1  to - 3  in response to the transaction request. In other words, in a case where the transferring unit  310  transfers a transaction request A to the servlet server  110 - 1 , and where the servlet server  110 - 1  which has received the transaction request A transmits a transaction request B to the APP server  120 - 1  in response to the request A, a time required for processing corresponding to the transaction request B is received the time included in the transaction response A for the transaction request A. 
         [0036]    As specific examples, each operation status can be described as follows: the abnormal status indicates that the required time is more than five seconds; the heavy-load status indicates that the required time is more than two seconds and less than or equal to 5 seconds; and the normal status indicates that the required time is less than or equal to two seconds. At the point of the reception by the table generator  320 , the operation status may be a numeric value itself indicating such required time, or may be one which indicates each status already judged in response to the numeric value. Moreover, the operation status may be one which indicates another index value showing the status of processing in each server/apparatus other than the required time. 
         [0037]    As an example of the index value, cited are throughput and latency of processing, and the like. Furthermore, the table generator  320  may be configured not to receive a time required for each processing as the operation status, but to receive an average time required for the plurality of transactions whose response are received for a fixed period of time as the operation status. Then, the table generator  320  evaluates the operation status of each of the APP servers  120 - 1  to - 3  and the DB server  130  in response to the received operation status, generates a status table indicating each evaluated operation status, and stores the operation status in the memory  300 . 
         [0038]    The evaluation of the operation status may be processing to handle the received operation status itself of one APP server  120  as the operation status of the APP server  120 , or may be processing to fix a single operation status in response to a plurality of operation statuses when the plurality of different operation statuses of the same APP server  120  are received. Moreover, the table generator  320  may evaluate the operation status of each servlet server  110  according to a time required from transmission of a transaction request to each of the servlet servers  110 - 1  to - 4  until reception of the transaction response to the transaction request, and may generate a status table including the evaluated operation status. 
         [0039]    The table transmitter  330  reads the generated status table from the memory  300  in response to the generation of the status table, and transmits the status table to each of the servlet servers  110 - 1  to - 4 . The first table updating unit  340  updates the status table already stored in the memory  300  by use of the received status table in response to the reception of the status table from any one of the servlet servers  110 - 1  to - 4 . The halt judging unit  350  stops the table generator  320  receiving the operation status and the table transmitter  330  transmitting the status table, on condition that the operation statuses of all of the servlet servers  110  are not in the normal statuses in the status table stored in the memory  300 . 
         [0040]    Note that descriptions will be omitted of each function which the dispatcher apparatus  100 - 2  has since the functions are approximately the same as those of the dispatcher apparatus  100 - 1 . 
         [0041]      FIG. 4  shows a functional configuration of the servlet server  110 - 1 . The servlet server  110 - 1  has a storage device  400 , a request transmitter  410 , a status returning unit  420 , a second table updating unit  430 , and a table returning unit  440 . Similarly to the case of the dispatcher apparatus  100 - 1 , descriptions will firstly be given of a relation with hardware resource. The memory  400  stores information necessary for each of the other members. For example, the memory  400  is performed by the RAM  1020  or the hard disk drive  1040 , both of which will be described later. The request transmitter  410  and the table returning unit  440  transmit and receive a transaction response and the like, and are carried out by causing the CPU  1000  and the communication interface  1030 , both of which will be described later, to operate in accordance with an installed program. The status returning unit  420  and the second table updating unit  430  judge the operation, processing, and condition of information, and are performed by causing the CPU  1000 , which will be described later, to be operated by an installed program. 
         [0042]    The memory  400  is provided to store a status table which shows the operation status of each of the servlet servers  110 - 1  to - 4 , the APP servers  120 - 1  to - 3 , and the DB server  130 . The request transmitter  410  transmits a transaction request to the APP server  120 - 1  to - 3  or the DB server  130  (hereinafter, referred to as the APP server  120 - 1  and the like) in response to the reception of the transaction request transferred from the memory  300  of one of the dispatcher apparatus (for example, the dispatcher apparatus  100 - 1 ), in order to cause the APP server  120 - 1  and the like to process a part of the requested transaction. The status returning unit  420  returns, to the dispatcher apparatus  100 - 1 , the status of a transaction response to the transaction request that the request transmitter  410  has transmitted to the APP server  120 - 1  and the like, as the operation status of the APP server  120 - 1 , the transaction response included in the transaction request transferred from the memory  300  of the dispatcher apparatus  100 - 1 . 
         [0043]    Here, the status of a transaction response indicates a time required from transmission of a transaction request until reception of the transaction response, for example. In other words, as an example of processing, the request transmitter  410  resets a timer when transmitting a transaction request to the APP server  120 - 1 , refers to the value of the timer when receiving a transaction response to the transaction request, and measures a time required for the processing. In this manner, the required time indicates the status of the transaction response. 
         [0044]    The second table updating unit  430  updates the status table already stored in the memory  400  by use of the received status table, in response to the reception of the status table from the table transmitter  330  of one of the dispatcher apparatus (for example, the dispatcher apparatus  100 - 1 ). The second table updating unit  430  may store the received status table in the memory  400  when no status table is stored in the memory  400 . In response to the update of the status table, the table returning unit  440  returns the updated status table to each of the dispatcher apparatuses. The return destination is not limited to the transmission source of the status table to the second table updating unit  430 , but is all of the dispatcher apparatuses  100  connected directly to the servlet server  110 - 1 . Furthermore, the status table to be returned may be transmitted in a manner included in the messages of transaction responses from the servlet servers  110 - 1  to - 4  to the dispatcher apparatuses  100 - 1  to - 2 . 
         [0045]    As described above with reference to  FIGS. 3 and 4 , in the information system  10 , the dispatcher apparatuses  100  and the servlet servers  110  transmit status tables to each other and reflect their contents. With this, it is possible to cause the operation status of each server/apparatus to be appropriately shared between the dispatcher apparatuses  100 - 1  to - 2  and the servlet servers  110 - 1  to - 4 . Even in a case where the operation status is normal but a single transaction accidentally takes time for processing, it is possible for each server/apparatus to prevent the status from being mistakenly judged, by updating the status table already stored in response to a plurality of received status tables. 
         [0046]      FIG. 5  shows an example of a data structure of a status table stored in the storage devices  300  or  400 . Each of the storage devices  300  and  400  stores the operation statuses of the servers/apparatuses identified with the servers&#39; IDs as status tables while associating the tables with the servers&#39; IDs. Moreover, each of the storage devices  300  and  400  further stores version IDs which show the time of revising the status tables while associating the status tables with the version IDs. Note that the storage devices  300  and  400  are independently managed in the dispatcher apparatuses  100  and the servlet servers  110 , respectively. 
         [0047]    As a specific example, the memory  300  stores the server ID of the servlet server  110 - 1  in association with the normal status as the operation status of the server. On the other hand, the memory  300  stores the server ID of the APP server  120 - 1  in association with the suspicious heavy-load status as the operation status of the server. In addition, the memory  300  stores the server ID of the DB server  130  in association with the normal status as the operation status of the server. The version ID allows the time and order of a revision to be discriminated. Accordingly, judgment can be made as to whether or not the status table should be updated. The following are the specific descriptions. 
         [0048]    With regard to processing related to a version ID in the storage device  300 , whenever generating a new status table, the table generator  320  generates a version ID in association with the new status table, the version ID indicating that the new status table is generated in a revision after a previously generated status table is generated, and stores the version ID in the storage device  300 . For example, if a version ID is managed as an integer value, the table generator  320  increments an already stored version ID and stores the version ID in the memory  300 , whenever generating a new status table. The cycle to generate a status table is determined, in common to the dispatcher apparatuses  100 - 1  to - 2 , to be every several minutes or every several seconds, for example. For this reason, although the IDs of status tables generated are approximately synchronous, they are not necessarily in perfect synchronization, since the processing to keep synchronization between the dispatcher apparatuses  100 - 1  and  100 - 2  is not performed. 
         [0049]    Furthermore, the table transmitter  330  reads a status table which has been generated by the table generator  320  and has been stored in the memory  300  from the memory  300  while associating the status table with a version ID, and transmits the status table to each of the servlet servers  110 - 1  to - 4 . With regard to processing related to a version ID in the memory  400 , on condition that the received version ID in association with the status table indicates a revision performed at the same time as or after the revision indicated by the version ID stored in the memory  400 , the second table updating unit  430  updates a status table stored in the memory  400  in response to the received status table. In this case, the second table updating unit  430  stores the received version ID in the memory  400  while associating the version ID with the updated status table. 
         [0050]    In addition, in response to the update of the status table, the table returning unit  440  returns the updated status table to each dispatcher apparatus  100  while associating the table with the version ID corresponding to the status table used for the update. Upon receipt of returned table, the first table updating unit  340  updates the status table stored in the storage device  300  by using the received status table, on condition that the received version ID indicates a revision at the same time as or after the revision indicated by the version ID in the storage device  300 . 
         [0051]    As described above, it is possible to select and refer to the latest status table alone, even if the arrival of a part of a status table is delayed due to congested communication traffic, since a status table is managed in association with a version ID. 
         [0052]      FIG. 6  shows a specific example of processing in which the dispatcher apparatus  100 - 1  transmits and receives a transaction request and a transaction response. The dispatcher apparatus  100 - 1  performs the following processing, for example, regularly or whenever receiving some requests/responses. When receiving a transaction request from an external terminal apparatus (S 600 : YES), the dispatcher apparatus  100 - 1  transfers the transaction request to a servlet server  110  selected from the plurality of servlet servers  110 - 1  to - 4  (S 610 ). When receiving a transaction response to the transferred transaction request (S 620 : YES), the transferring unit  310  returns the transaction response to the external terminal apparatus (S 630 ). 
         [0053]    Next, the table generator  320  generates a status table in response to the message of the transaction response (S 640 ). Specifically, the table generator  320  obtains the operation status of each of the APP servers  120 - 1  to - 3  and the DB server  130  from the messages of the transaction responses, and evaluates the operation status for each server/apparatus of the APP servers  120 - 1  to - 3  and the DB server  130  in response to the obtained operation status. In addition, the table generator  320  evaluates the operation statuses of the servlet servers  110 - 1  to - 4  in response to a time required from transmission of the transaction request until reception of the transaction response thereof. The evaluated operation status is generated while being included in a status table. A newly generated status table is stored in the storage device  300  by replacing the status table already stored in the storage device  300 . Moreover, a version ID is incremented. Additionally, the evaluation for an operation status is based on an operation status included in a plurality of transaction responses received within a predetermined period in the past, and may be made for the same server/apparatus in response to a plurality of operation statuses. Detailed descriptions will be given later. Note that the table generator  320  does not have to update the storage device  300  by using a newly generated status table when the newly generated status table is compared with an already stored status table and found out to be the same as the already stored one. In this case, the table transmitter  330  which will be described later does not have to transmit the status table in S 660 . 
         [0054]    Next, the halt judging unit  350  judges whether or not a condition of halt of transmitting and receiving a status table is satisfied (S 650 ). The condition of halt is that all of the operation statuses of the servlet servers  110 - 1  to - 4  are not in the normal state, for example. This is because in such case, the mutual transmission of status tables between the dispatcher apparatuses  100 - 1  to - 2  and the servlet servers  110 - 1  to - 4  are not performed smoothly. If the condition of halt is not satisfied (S 650 : NO), the table transmitter  330  reads the generated status table from the storage device  300  and transmits the table to each servlet server  110  (S 660 ). If the condition of halt is satisfied (S 650 : YES), the table transmitter  330  does not transmit the status table, and moves on to the next processing. 
         [0055]    Incidentally, even in the case where the condition of halt is satisfied, the halt judging unit  350  may resume the reception of an operation status by the table generator  320  and the transmission of a status table by the table transmitter  330 , on condition that a predetermined period has elapsed after the condition is satisfied. In a case where the condition of halt is satisfied immediately after the resumption, the halt judging unit  350  stops the reception of the operation status and the transmission of the status table, and then waits for a period longer than the above predetermined period. After the period elapsed, the halt judging unit  350  resumes the reception of the operation status and the transmission of the status table. In this manner, it is possible to reduce the load of the information system  10  as much as possible upon failure occurrence and to facilitate restoration from the failure, by extending standby time in accordance with the delay in the restoration from a failure. 
         [0056]    Furthermore, the first table updating unit  340  judges whether or not new status tables have been received from the servlet servers  110 - 1  to - 4  (S 670 ). In other words, in response to the reception of the status table received from any of the servlet servers  110 - 1  to - 4 , the first table updating unit  340  judges whether or not the version ID received in association with the status table indicates a revision at the same time as or after the revision indicated by the version ID already stored in the storage device  300 . Having been revised at the same time as or after means that the number of the received version ID is the same as or greater than the number of the version ID already stored, for example. On condition that the new status table has been received (S 670 : YES), the first table updating unit  340  updates the status table stored in the storage device  300  by use of the received status table (S 680 ). 
         [0057]    Note that when receiving status tables from the servlet servers  110  while performing processing to generate a new status table, it is desirable that the table transmitter  330  should transmit a newly generated status table, and then the first table updating unit  340  should try to update the status table. In this manner, it is possible to increase the information on a time required for the evaluation of an operation status in the whole information system  10 , by giving priority to the evaluation for the operation status according to a time required for processing and the like. Consequently, the accuracy of the evaluation of an operation status can be increased. 
         [0058]      FIG. 7  shows a detailed example of processing in S 640 . With reference to  FIG. 7 , detailed descriptions will be given of processing in which the table generator  320  evaluates the operation status of each apparatus/server in response to the message of a transaction response received by the transferring unit  310 . The table generator  320  receives the operation statuses of the each server/apparatus included in the statuses of a plurality of transaction responses received from the servlet servers  110 - 1  to - 4  within a predetermined time in the past, and then counts the received operation statuses (S 700 ). An example of the specific processing will hereinafter be described. 
         [0059]    Firstly, the table generator  320  performs the following processing for each transaction response. The table generator  320  computes a time required from transmission of the corresponding transaction request until reception of the transaction response thereof. This is carried out by resetting a timer upon transmitting a transaction request in the table generator  320  and referring to the timer upon receiving a transaction response. This time is set as a time A. Moreover, the table generator  320  obtains, from the messages of the transaction responses, the time required for the transactions requested by the servlet servers  110  to the APP servers  120 , in response to the transaction request. This time is set as a time B. Then, the table generator  320  computes the time required for processing in the servlet servers  110  by subtracting the time B from the time A. 
         [0060]    When the APP servers  120  have further requested transactions to the DB server  130  following the transaction request, the table generator  320  further obtains the required time from the messages. This time is set as a time C. In this case, the table generator  320  computes the time required for processing in the APP servers  120  by subtracting the time C from the required time B measured in the servlet servers  110 . In this manner, the table generator  320  computes the time required for each of a plurality of transactions derivatively and sequentially requested from one transaction request. The required time is converted into the information of an operation status while setting the above-mentioned five and two seconds to be the threshold values. The table generator  320  performs the above processing for each transaction response received within the above-mentioned predetermined time in the past. Then, the table generator  320  counts the operation status judged in this manner in each of the servlet servers  110 - 1  to - 4 , the APP servers  120 - 1  to - 3 , and the DB server  130 . 
         [0061]    Next, the table generator  320  judges whether or not any of operation statuses counted regarding the servlet server  110  indicates heavy-load or abnormal statuses for each of the servlet servers  110 - 1  to - 4  (S 710 ). On condition that any of the counted operation statuses indicates the heavy-load or abnormal statuses concerning all of the servlet servers  110  (S 710 : YES), the halt judging unit  350  judges that the condition of the halt of transmitting and receiving a status table is satisfied (S 720 ), and completes the processing in the drawing. In this case, the table generator  320  does not have to generate a status table. 
         [0062]    Next, the table generator  320  processes the following for each of the APP servers  120 - 1  to - 3  and the DB server (hereinafter targeted processing is referred to as a relevant server) (S 730 ). On condition that the ratio of operation statuses indicting that the relevant server operates normally, to all the received operation statuses is a predetermined reference value (N) (S 740 : YES), the table generator  320  evaluates the relevant server to be in the normal status (S 750 ). It is desirable that the reference value (N) should be an extremely small value larger than 0. This is because once an anomaly occurs in a server, the following processing tends to be further delayed, and the situation rarely improves even temporarily. In other words, when processing which can be judged to be normal is slightly observed, it is hard to consider that the processing has accidentally been completed normally in the abnormal status, and it is natural to consider that other processing is accidentally taking time in the normal status. Hence, the table generator  320  can evaluate that the relevant server is in the normal status as long as one operation status showing the normal status is included. 
         [0063]    When the relevant server is not evaluated to be in the normal status (S 740 ), the table generator  320  then judges whether or not the ratio of operation statuses indicating that the relevant server operates under heavy-load, to all the received operation statuses is equal to or more than a predetermined reference value (K) (S 760 ). On condition that the ratio is equal to or more than the reference value (K) (S 760 : YES), the table generator  320  evaluates that the relevant server is in the heavy-load status (S 770 ). It is desirable that the reference value (K), too, should be an extremely small value larger than 0. The table generator  320  may judge that the relevant server is in the heavy-load status even if the other operation statuses show the abnormal statuses as long as even one operation status indicating that the heavy-load status is included. On condition that the ratio of operation statuses indicating that the relevant server operates under heavy-load, to all the received operation statuses is less than the reference value (K) (S 760 : NO), the table generator  320  judges that the relevant server is in the suspicious abnormal status (S 780 ). The table generator  320  repeats the above processing for each of the APP servers  120 - 1  to - 3  and the DB server  130  (S 790 ). 
         [0064]      FIG. 8  shows a specific example of processing that the servlet server  110 - 1  transmits and receives a transaction request and a transaction response. In response to the reception of a transaction request transferred from the storage device  300  of one of the dispatcher apparatus (for example, the dispatcher apparatus  100 - 1 ) (S 800 : YES), the request transmitter  410  transmits the transaction request to the APP server  120 - 1  and the like in order to cause the APP servers  120 - 1  to - 3  to process a part of the requested transaction (S 810 ). Assume that the destination is set to be the APP server  120 - 1 , for example. When the request transmitter  410  receives a transaction response to the transaction request that the request transmitter  410  has transmitted to the APP server  120 - 1  (S 820 : YES), the status returning unit  420  obtains the status of the transaction response as the operation status of the APP server  120 - 1  (S 830 ). A time required from the transaction request to the transaction response may be obtained from the APP server  120 - 1 , for example. Then, the status returning unit  420  returns the operation status of the APP server  120 - 1  to the dispatcher apparatus  100 - 1 , the operation status included in the transaction response to the transaction request transferred from the storage device  300  of the dispatcher apparatus  100 - 1  (S 840 ). 
         [0065]    Next, the second table updating unit  430  judges whether or not a new status table has been received from one of the dispatcher apparatuses (for example, the dispatcher apparatus  100 - 1 ) (S 850 ). In other words, in response to the reception of the status table from the dispatcher apparatus  100 - 1 , the second table updating unit  430  judges to have received a new status table, on condition that a version ID received in association with the status table indicates a revision at the same time as or after the revision indicated by the version ID already stored in the storage device  400 . On condition that the new status table has been received (S 850 : YES), the second table updating unit  430  updates the status table stored in the storage device  400 , by use of the received status table (S 860 ). In this manner, a status table is updated every time a status table is received. Accordingly, the information on status tables received from each of the dispatcher apparatuses  100 - 1  to - 2  is combined and reflected on the status table of the storage device  400 . Then, the table returning unit  440  returns the updated status tables to each of the dispatcher apparatuses  100 - 1  to - 2  (S 870 ). 
         [0066]      FIG. 9  is a state transition diagram of operation statuses sequentially updated in S 860 . The second table updating unit  430  updates each of the operation statuses of the APP servers  120 - 1  to - 3  and the DB server  130 , the statuses being managed in a status table, in accordance with the state transition diagram shown in  FIG. 9 . Specifically, on condition that the operation status of a server targeted for processing is not in the normal status in a status table already stored in the storage device  400  but is in the normal status in a status table received from the table transmitter  330  of the dispatcher apparatuses  100 , the second table updating unit  430  updates the operation status of the relevant server to the normal status. In other words, any of the heavy-load, abnormal, suspicious heavy-load and suspicious abnormal statuses is updated to the normal status on condition that the normal status is received. 
         [0067]    Additionally, on condition that the operation status of a server targeted for processing is in the normal status in a status table already stored in the storage device  400  and is in the abnormal or suspicious abnormal status in a status table received from the table transmitter  330  of the servlet server  110 , the second table updating unit  430  updates the operation status of the relevant server to the suspicious abnormal status. In other words, even if the abnormal status has been received, it is not immediately judged in the second table updating unit  430  to be in the abnormal status. Then, on condition that the predetermined period has elapsed without restoring the operation status to the normal status after updating the operation status to the suspicious abnormal status, the second table updating unit  430  updates the operation status to the abnormal status. 
         [0068]    Furthermore, on condition that the operation status of a server targeted for processing is in the normal status in a status table already stored in the storage device  400  and is in the heavy-load status in a status table received from the table transmitter  330  of the servlet server  110 , the second table updating unit  430  updates the operation status of the relevant server to the heavy-load status. In other words, even if the heavy-load status has been received, it is not immediately judged in the second table updating unit  430  to be in the heavy-load status. Then, on condition that the predetermined period has elapsed without restoring the operation status to the normal status after updating the operation status to the suspicious heavy-load status, the second table updating unit  430  updates the operation status to the heavy-load status. 
         [0069]      FIG. 10  shows the process that operation statuses are sequentially updated by the information system  10  according to the embodiment. For convenience of explanation here, it is assumed that the information system  10  includes the dispatcher apparatuses  100 - 1  to - 2 , the servlet server  110 - 1 , and the APP servers  120 - 1  to - 3 , and that does not include the servlet server  110 - 2  and the DB server  130 . Additionally, the APP servers  120 - 1  to - 3  are represented as A to C, respectively, in the table. Moreover, the initial value of a version ID is set to 0. In other words, storage devices in all servers/apparatuses store the numeric value of 0 as the version ID. Furthermore, it is assumed that a status table includes the operation statuses of the APP servers  120 - 1  to - 3 , and that does not include the operation statuses of the servlet servers  110 - 1  to - 2 . 
         [0070]    At the point of a time  0  to be the initial status, the storage device  300  of the dispatcher apparatus  100 - 1  stores a status table in which any of the operation statuses of the APP servers  120 - 1  to  3  are the normal statuses. This status table is represented as A, B, C. The same goes for the storage device  300  of the dispatcher apparatus  100 - 2  and the storage device  400  of the servlet server  110 - 1 . At the point of a time  1  after the time  0 , the table generator  320  judges the operation status of the APP server  120 - 3  to be the suspicious abnormal status. This is because, for example, any of processings carried out in the APP server  120 - 1  within a fixed period in response to a request from the dispatcher apparatus  100 - 1  needed the time required for the statuses to be judged as the abnormal statuses. The status table at this time is represented as A, B, and C (−). The symbol − indicates the abnormal status, and the symbol (−) indicates the suspicious abnormal status. At this point, the version ID is incremented to be 1 in the storage device  300  of the dispatcher apparatus  100 - 1 . However, the version ID is still 0 in the servlet server  110 - 1 . Hence, the version ID is described as 0 in the table. 
         [0071]    At a time  2 , the second table updating unit  430  of the servlet server  110 - 1  receives a status table from the table transmitter  330  of the dispatcher apparatus  100 - 1 . The APP server  120 - 3  is in the normal status in the status table already stored in the storage device  300 , but the APP server  120 - 3  is in the suspicious abnormal status in the received status table. Accordingly, the second table updating unit  430  of the servlet server  110 - 1  updates the operation status to the suspicious abnormal status. Hence, the status table shows A, B, and C (−) also in the servlet server  110 - 1 . 
         [0072]    Furthermore, at the same time  2 , the table generator  320  of the dispatcher apparatus  100 - 2  generates a status table independently from the dispatcher apparatus  100 - 1 , slightly later than the dispatcher apparatus  100 - 1 . At this point, the table generator  320  judges the operation status of the APP server  120 - 2  to be the suspicious abnormal status. This is because the time required for the status to be judged as the abnormal status is needed for any of processings carried out in the APP server  120 - 2  in response to a request received from the dispatcher apparatus  100 - 2  within a fixed period, for example. The status table generated as a result shows A, B (−), and C. At this point, all version IDs of the dispatcher apparatuses  100 - 1  to - 2  and the servlet server  110 - 1  become 1. 
         [0073]    At a time  3 , the table returning unit  440  of the servlet server  110 - 1  transmits status tables to the dispatcher apparatuses  100 - 1  and  100 - 2 . In the dispatcher apparatus  100 - 1 , the stored status table and the received status table are the same. Accordingly, no processing is carried out. In the dispatcher apparatus  100 - 2 , the two version IDs in the stored and received status tables are 1 and identical. Accordingly, the first table updating unit  340  updates the stored status table by use of the received status table. For example, the stored status table is replaced by use of the received status table. As a result, the status table indicates A, B, C (−) in the storage device  300  of the dispatcher apparatus  100 - 2 . 
         [0074]    At a time  4 , the table generator  320  of the dispatcher apparatus  100 - 2  judges again that the operation status of the APP server  120 - 2  is in the suspicious abnormal status. This is because any of the processings carried out in the APP server  120 - 2  in response to a request of the dispatcher apparatus  100 - 2  needed the time required for the status to be judged as the abnormal status even in the next fixed period. A status table generated as a result indicates A, B (−), and C. In addition, the generated version ID is 2. Then, in the next time  5 , the table transmitter  330  of the dispatcher apparatus  100 - 2  transmits the generated status table to the servlet server  110 - 1 . 
         [0075]    The second table updating unit  430  of the servlet server  110 - 1  updates a stored status table by use of the received status table, since the number of the received version ID  2  is greater than that of the stored version ID  1 . With regard to the APP server  120 - 2 , the stored operation status is the normal status, and the received operation status is the suspicious abnormal status. Accordingly, the second table updating unit  430  updates the operation status of the APP server  120 - 2  to the suspicious abnormal status. With regard to the APP server  120 - 3 , the stored operation status is the suspicious abnormal status, and the received operation status is the normal status. Accordingly, the second table updating unit  430  updates the operation status of the APP server  120 - 3  to the normal status. As a result, the status table indicates A, B (−), and C. 
         [0076]    At the next time  6 , the table returning unit  440  of the servlet server  110 - 1  returns the updated status table to each of the dispatcher apparatuses  100 - 1  to - 2 . In the dispatcher apparatus  100 - 2 , the already stored status table and the received status table are the same. For this reason, the first table updating unit  340  carries out no processing. On the other hand, the servlet server  110 - 1  receives the status table A, B (−), and C, which is different from the stored status table, and also replace the stored status table with the received status table since the version IDs indicates that the revision is made at the same period of time. As a result, the status table becomes A, B (−), and C. 
         [0077]    At the next times  7  and  8 , the table generators  320  of the dispatcher apparatuses  100 - 1  to - 2  evaluate the operation statuses of the APP servers  120 - 1  to - 3 . However, the operation statuses are the same as those before the evaluation. Hence, the descriptions of the operation statuses do not change in  FIG. 10 . Similarly, the second table updating unit  430  of the servlet server  110 - 1  receives the status tables from the dispatcher apparatuses  100 - 1  to - 2 . However, the status table is the same as the already stored status table. Hence, the description of the status table does not change in  FIG. 10 . 
         [0078]    At a time  9 , the second table updating unit  430  of the servlet server  110 - 1  updates the operation status of the APP server  120 - 2  to the abnormal status, since a predetermined time has elapsed after the update of the operation status of the APP server  120 - 2  to the suspicious abnormal status. The updated operation statuses are returned to the dispatcher apparatuses  100 - 1  to - 2  while the updated operation statuses are included in the status table. As a result, the status table indicates A, B-, and C. At a time  10 , the first table updating units  340  of the dispatcher apparatuses  100 - 1  to - 2  updates the already stored status tables by use of the received status tables. As a result, the status tables indicate A, B-, and C. 
         [0079]      FIG. 11  shows an example of a hardware configuration of an information processing apparatus  500  functioning as the dispatcher apparatus  100 - 1  or the servlet server  110 - 1 . The information processing apparatus  500  includes a CPU peripheral unit, an input/output unit, and a legacy input/output unit. The CPU peripheral unit includes the CPU  1000 , the RAM  1020 , and a graphics controller  1075 , all of which are mutually connected to one another via a host controller  1082 . The input/output unit includes the communication interface  1030 , the hard disk drive  1040 , and a CD-ROM drive  1060 , all of which are connected to the host controller  1082  via an input/output controller  1084 . The legacy input/output unit includes a ROM  1010 , a flexible disk drive  1050 , and an input/output chip  1070 , all of which are connected to the input/output controller  1084 . 
         [0080]    The host controller  1082  connects the RAM  1020  to the CPU  1000  and the graphic controller  1075 , both of which access the RAM  1020  at a higher transfer rate. The CPU  1000  is operated in accordance with programs stored in the ROM  1010  and the RAM  1020 , and controls each of the components. The graphics controller  1075  obtains image data that the CPU  1000  or the like generates in a frame buffer provided in the RAM  1020 , and causes the obtained image data to be displayed on a display device  1080 . Instead of this, the graphics controller  1075  may internally include a frame buffer in which the image data generated by the CPU  1000  or the like is stored. 
         [0081]    The input/output controller  1084  connects the host controller  1082  to the communication interface  1030 , a hard disk drive  1040 , and the CD-ROM drive  1060 , all of which are relatively high-speed input/output devices. The communication interface  1030  communicates with an external device via a network. In the hard disk drive  1040 , programs and data used by the information processing apparatus  500  are stored. The CD-ROM drive  1060  reads a program or data from a CD-ROM  1095 , and provides the RAM  1020  or the hard disk drive  1040  with the read-out program or the data. 
         [0082]    Furthermore, the input/output controller  1084  is connected to relatively low-speed input/output devices such as the ROM  1010 , the flexible disk drive  1050  and the input/output chip  1070 . In the ROM  1010 , stored are programs such as a boot program executed by the CPU  1000  at a start-up time of the information processing apparatus  500  and a program depending on hardware of the information processing apparatus  500 . The flexible disk drive  1050  reads a program or data from a flexible disk  1090 , and provides the RAM  1020  or the hard disk drive  1040  with the read-out program or the data, via the input/output chip  1070 . The input/output chip  1070  is connected to the flexible disk  1090  and various kinds of input/output devices, for example, through a parallel port, a serial port, a keyboard port, a mouse port, and the like. 
         [0083]    A program to be provided to the information processing apparatus  500  is provided by a user with the program stored in a storage medium such as the flexible disk  1090 , the CD-ROM  1095 , and an IC card. The program is read from the storage medium via the input/output chip  1070  and/or the input/output controller  1084 , and is installed and executed on the information processing apparatus  500 . An operation that the program causes the information processing apparatus  500  or the like to execute, is identical to the operation of the dispatcher apparatus  100 - 1  and the servlet server  110 - 1  described by referring to  FIGS. 1 to 10 . Accordingly, the description thereof will be omitted here. Note that description will also be omitted of operations and hardware configurations of the dispatcher apparatus  100 - 2  and the servlet servers  110 - 2  to - 4  since the operations and the hardware configurations are substantially identical to the operation of the information processing apparatus  500  shown in  FIG. 11 . 
         [0084]    The program described above may be stored in an storage medium. As the storage medium, any one of the following media may be used: an optical storing medium such as a DVD and a PD; a magneto-optical storage medium such as an MD; a tape medium; and a semiconductor memory such an IC card, in addition to the flexible disk  1090  and the CD-ROM  1095 . Alternatively, the program may be provided to the information processing apparatus  500  via a network, by using, as a storage medium, a storage device such as a hard disk and a RAM, provided in a server system connected to a private communication network or to the Internet. 
         [0085]    As described above, according to the information system  10  of the embodiment, it is possible to transmit and receive an operation status by including in a message such as a transaction request and a transaction response. Accordingly, an additional apparatus is not required other than originally necessary apparatuses and servers. Furthermore, it is possible to detect a wide range of failures including failures originated from software. Moreover, even in a case where the relation of calls is hierarchical in a manner that a server A requests a transaction to another server B and the server B then requests the transaction to a server C, it is possible to accurately judge the spot of causing a failure. In addition, by exchanging the evaluation results of the operations statuses between the dispatcher apparatuses  100  and the servlet servers  110 , it is possible to correct wrong evaluation and a mistake in temporary evaluation. For example, it is possible to avoid mistakenly judging a transaction delayed temporarily due to a GC of Java (a registered trademark), and to increase the accuracy of operation status evaluation. 
         [0086]    Hereinabove, the present invention has been described by using the embodiment, but the technical scope of the present invention is not limited to the aforementioned embodiment. It is obvious to those skilled in the art that various modifications and improvements can be made in the aforementioned embodiment. It is obvious from the description of the scope of claims that a modified or improved embodiment is also included in the technical scope of the present invention.