Patent Publication Number: US-9843627-B2

Title: Information processing method, information processing device, and storage medium

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation application of International Application PCT/JP2012/002139 filed on Mar. 28, 2012, the entire contents of which are incorporated herein by reference. 
    
    
     FIELD 
     The embodiment discussed herein is related to an information processing method, an information processing device, and a storage medium. 
     BACKGROUND 
     Cloud computing is a user environment where users receive services through networks such as the Internet, and the spread of cloud computing has been promoted in recent years. In cloud computing, many tenants (users) use servers installed in a large data center or the like. This method causes an advantage of scale, and a unit price for use of an infrastructure of the data center may be reduced. Since the tenants may outsource operations and management of the servers to a provider (service provider) that provides services, a cost of the operations and management may be reduced. 
       FIGS. 1A and 1B  are diagrams illustrating examples of the type of a multi-tenant architecture that achieves cloud computing.  FIG. 1A  illustrates a multi-tenant architecture called an Infrastructure-as-a-Service-based (IaaS-based) virtual native Platform as a Service (PaaS). As illustrated in  FIG. 1A , the virtual native PaaS has a layer structure composed of constituent elements such as hardware, virtual machines, operating systems (OSs), databases (DBs), and application software (hereinafter referred to as applications). In the virtual native PaaS, only a hardware infrastructure is shared by tenants. A virtual machine, an OS, a DB, and an application are used for each of the tenants. In the virtual native PaaS, each tenant may freely select and combine a virtual machine, an OS, a DB, and an application. 
       FIG. 1B  illustrates a multi-tenant architecture called a multi-tenant native PaaS. As illustrated in  FIG. 1B , the architecture that is called the multi-tenant native PaaS has a layer structure composed of constituent elements such as hardware, an OS, a DB, an application, and the like. In the multi-tenant native PaaS, not only the hardware but also the OS, the DB, and the application are shared by tenants. Only business processes that are executed by this infrastructure are different for the tenants. In the multi-tenant native PaaS, the application and the DB are shared by the tenants. Thus, an aggregation efficiency of the infrastructure is high and efficiencies of operations and management may be improved. As related art, there are Japanese Laid-open Patent Publication Nos. 2010-140209, 2011-154540, 10-134066, 11-53191, Junichi Niino, “Course of Evolution of PaaS and Cloud Platform without Virtualization”, online, searched on Mar. 7, 2012, &lt;URL: http://www.publickey1.jp/blog/11/paas_1.html&gt;, and the like. 
     In the virtual native PaaS, the virtual machines, the OSs, the DBs, and the applications are different for the tenants, and processes are separately executed for the tenants in an actual operation. Thus, the architecture is redundant and is not efficient, and servers of a data center may not be effectively used in the virtual native PaaS. In addition, a provider of the virtual native PaaS manages combinations of a large number of constituent elements. Thus, operations and management of the servers are complex, and an operation cost (running cost) per tenant is high. 
     In the multi-tenant native PaaS, the OS, the DB, and middleware are shared by multiple tenants, as described above. Thus, each tenant does not freely select an OS, a DB, and the type of an application, and the flexibility of selecting an architecture is low. 
     SUMMARY 
     According to an aspect of the invention, an information processing method to be executed by a processor included in an information processing device, the information processing method includes receiving a plurality of requests for constituent elements including a hardware and a software from a plurality of terminal devices; determining, among the plurality of requests, a pair of requests which is different from each other, a similarity of the pair of requests being a level more than a predetermined threshold; selecting terminal devices corresponding the pair of requests; setting a common request including a common element requested by at least two of the selected terminal devices, the common request being different from each of the pair of requests; transmitting the common request and cost information corresponding to the common request to the selected terminal devices, the cost information being cheaper than each of the pair of requests. 
     The object and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the claims. 
     It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention, as claimed. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIGS. 1A and 1B  are diagrams illustrating examples of the type of a multi-tenant architecture that achieves cloud computing; 
         FIG. 2  is a diagram illustrating an example of a cloud computing system according to an embodiment; 
         FIG. 3  is a flowchart of operations of an information processing device according to the embodiment; 
         FIG. 4A  is a diagram illustrating an example of resources requested for use by tenants; 
         FIG. 4B  is a diagram illustrating an example of a data structure of resource information stored in a memory; 
         FIG. 5  is a flowchart of a process of calculating similarities; 
         FIG. 6  is a diagram illustrating an example of corresponding relationships between the types of methods for changing a resource and load levels representing loads caused by changes; 
         FIG. 7  is a state transition diagram illustrating an example of resources requested for use by tenants; 
         FIG. 8  is a diagram illustrating an example of the calculation of distances between resources used by a tenant and resources used by another tenant; 
         FIG. 9  is a diagram illustrating an example of results of calculating similarities between resources requested for use by the tenants illustrated in  FIGS. 4A and 4B ; 
         FIG. 10A  is a diagram illustrating an example in which combinations of tenants targeted for sharing are extracted; 
         FIGS. 10B and 10C  are state transition diagrams illustrating examples of the extracted combinations of the tenants targeted for the sharing; 
         FIG. 11  is a flowchart of an example of a process of determining similar resources and calculating operation costs; 
         FIG. 12  is a flowchart of a modified example of the process of determining similar resources and calculating operation costs; 
         FIG. 13  is a diagram illustrating an example of presenting, to the target tenants, information of the similar resources and the operation costs when the similar resources are used; 
         FIG. 14  is a flowchart of a modified example of operations of the information processing device according to the embodiment; 
         FIG. 15  is a diagram illustrating an example of resources before the execution of the sharing and resources after the execution of the sharing; 
         FIG. 16  is a diagram illustrating results of calculating, based on the example illustrated in  FIG. 12 , the numbers of constituent elements of resources before and after the execution of the sharing and the numbers of types of the constituent elements of the resources before and after the execution of the sharing; 
         FIGS. 17A and 17B  are diagrams illustrating an example of the type of a multi-tenant architecture that is achieved in the embodiment; 
         FIGS. 18A and 18B  are diagrams illustrating another example of the type of the multi-tenant architecture that is achieved in the embodiment; and 
         FIGS. 19A and 19B  are diagrams illustrating examples of a definition of distances between resources of servers. 
     
    
    
     DESCRIPTION OF EMBODIMENT 
     Hereinafter, an embodiment is described in detail with reference to  FIGS. 1 to 19B . 
       FIG. 2  is a diagram illustrating an example of an information processing system according to the embodiment. As illustrated in  FIG. 2 , the information processing system includes a cloud system infrastructure  1 , terminals  2 , and an information processing device  3 . The cloud system infrastructure  1 , the terminals  2 , and the information processing device  3  are connected to each other and able to communicate with each other. 
     The cloud system infrastructure  1  is installed, for example, in a data center and includes servers  1   a ,  1   b ,  1   c , and  1   d  configured to provide services to many tenants. The tenants may receive desired services from the cloud system infrastructure  1  through a network such as the Internet. Each of the servers  1   a  to  1   d  may operate with a resource including, as constituent elements, multiple types of software such as an OS and an application, for example. 
     The cloud system infrastructure  1  includes a management terminal  4 . The management terminal  4  is connected to the servers  1   a  to  1   d  and able to communicate with the servers  1   a  to  1   d . The management terminal  4  may cause each of the servers  1   a  to  1   d  to execute processes such as a process of upgrading an OS and a process of installing software, based on signals received from the information processing device  3 . 
     The terminals  2  are user interfaces owned by the tenants that use the cloud system infrastructure  1 . The tenants own the different terminals.  FIG. 2  exemplifies terminals  2   a ,  2   b ,  2   c ,  2   d , and  2   e  owned by five tenants. The terminals  2  are personal computers (PCs) or mobile terminals such as mobile phones, for example. 
     Functions of units of the information processing device  3  are described below. The information processing device  3  includes a memory  5 , a memory  6 , a processor  7 , an interface (I/F)  8 , and an interface (I/F)  9 . 
     The memory  5  is an example of a storage unit. The memory  5  is electrically connected to the processor  7 . The memory  5  may store request information representing resources requested by the tenants that use the cloud system infrastructure  1 . The memory  5  may store information on costs of operations with resources. As the memory  5 , a semiconductor memory such as a random access memory (RAM) or a flash memory, or a hard disk drive (HDD), may be used, for example. The information processing device  3  may have a plurality of the memories  5 . 
     The memory  6  is electrically connected to the processor  7 . The memory  6  may store an information processing program for executing a process of sharing a resource (or aggregating resources). As the memory  6 , a semiconductor memory such as a read only memory (ROM) or a flash memory, or an HDD, may be used, for example. The information processing device  3  may have a plurality of the memories  6 . The memory  5  and the memory  6  may be formed by a single memory. 
     The processor  7  is an example of a processing unit. The processor  7  may execute the information processing program based on the information representing the resources and stored in the memory  5  and the information representing the costs of the operations with the resources and stored in the memory  5 . The processor  7  executes, in accordance with the information processing program, a process (described later) of collecting resource information, a process (described later) of calculating similarities, a process (described later) of determining a similar resource, a process (described later) of calculating a cost, and the process (described later) of executing sharing. The processor  7  is a central processing unit (CPU), for example. 
     The interface (I/F)  8  has an input and output interface function of transmitting and receiving a signal between the processor  7  and the cloud system infrastructure  1  and connecting the processor  7  to the cloud system infrastructure  1 . The interface (I/F)  8  may transmit a signal to the management terminal  4  of the cloud system infrastructure  1  based on a signal received from the processor  7 . The interface (I/F)  8  may transmit a signal to the processor  7  based on a signal received from the management terminal  4 . 
     The interface (I/F)  9  is an input and output interface of transmitting and receiving a signal between the processor  7  and the terminals  2   a  to  2   e  of the tenants and connecting he processor  7  to the terminals  2   a  to  2   e . The interface (I/F)  9  may transmit a signal to a destination terminal among the terminals  2   a  to  2   e  based on a signal received from the processor  7 . The interface (I/F)  9  may receive signals from the terminals  2   a  to  2   e  and transmit a signal to the processor  7  based on the signals received. 
     Next, operations of the information processing device  3  according to the embodiment are described. 
       FIG. 3  is a flowchart of the operations of the information processing device  3  according to the embodiment. 
     The processor  7  acquires information of resources requested for use by the tenants and causes the acquired information of the resources to be stored in the memory  5  (in S 101 ). The information of the resources is information of constituent elements such as hardware, OSs, DBs, and applications, for example. The information of the resources requested for use by the tenants includes not only information of a resource selected when a new tenant applies for use of the cloud system infrastructure  1 , but also information of a resource used by an existing tenant that has started using the cloud system infrastructure  1 . An example of operations when information of OSs and applications is acquired as the information of the resources is described below. 
       FIG. 4A  is a diagram illustrating an example of the resources requested for use by the tenants.  FIG. 4B  is a diagram illustrating an example of a data structure of the information representing the resources and stored in the memory. In the example illustrated in  FIG. 4A , the tenants that use the cloud system infrastructure  1  are tenants A, B, C, D, E, and F. 
     The tenant A requests use of a server that has a resource including OS-a  4 . 0  as an OS and App-a  2 . 0  as an application, a resource including OS-a  4 . 5  as an OS and App-a  2 . 4  as an application, and a resource including OS-a  4 . 2  as an OS and App-b  4 . 1  as an application. The tenant B requests use of a server that has a resource including OS-a  4 . 5  as an OS and App-a  2 . 4  as an application and a resource including OS-a  4 . 5  as an OS and App-b  4 . 1  as an application. 
     The tenant C requests use of a server that has a resource including OS-c  1 . 0  as an OS and App-c  2 . 6  as an application and a resource including OS-a  4 . 5  as an OS and App-b  4 . 1  as an application. The tenant D requests use of a server that has a resource including OS-b  3 . 0  as an OS and App-c  7 . 0  as an application, a resource including OS-b  1 . 0  as an OS and App-c  6 . 0  as an application, and a resource including OS-b  2 . 0  as an OS and App-d  10  as an application. 
     The tenant E requests use of a server that has a resource including OS-b  2 . 0  as an OS and App-c  7 . 0  as an application and a resource including OS-b  2 . 0  as an OS and App-b  5 . 0  an application. The tenant F requests use of a server that has a resource including OS-b  2 . 0  as an OS and App-c  7 . 0  as an application and a resource including OS-b  2 . 0  as an OS and App-b  4 . 0  as an application. 
     The numbers written on the right sides of the OSs and applications represent version numbers of the software. Regarding the same type of software, the larger the number, the newer the version. The resources of the tenants A, B, C, D, E, and F are not limited to the aforementioned resources. 
       FIG. 4B  illustrates the combinations of the resources of the servers requested for use by the tenants or the combinations of the applications and the OSs for the tenants. In order to acquire information of the aforementioned resources, a method for receiving the information by requesting the information to the tenants that use the cloud system infrastructure  1  or a method for searching and extracting the information of the resources from information of contacts with tenants held by the information processing device  3  may be used. Alternatively, the memory  5  has, stored therein, the information of the resources, and the information of the resources may be acquired by requesting the latest information to only tenants for which time periods that elapse after the latest times of updating the stored information exceed a predetermined time period. According to this method, information may not be acquired from all the tenants upon the execution of the information processing program. Thus, the information of the resources may be efficiently acquired and a processing time may be reduced. 
     The information of the resources may be acquired when a new tenant applies for use of the cloud system infrastructure  1  or when the number of tenants exceed a certain number and cost-effectiveness is expected to be obtained by the sharing. Alternatively, the information of the resources may be acquired at regular or irregular time intervals. Alternatively, the information of the resources may be acquired when a request to reduce a cost of operating a server is received from a tenant or when a cost of operating the cloud system infrastructure  1  is to be reduced by a provider. 
     Return to  FIG. 3 . Subsequently, the processor  7  calculates similarities between the resources based on the acquired information of the resources (in S 102 ). An example of a method for calculating the similarities is described with reference to  FIGS. 5 and 6 . 
       FIG. 5  is a flowchart of a process of calculating the similarities. 
     The processor  7  reads, from the memory  5 , the information of the resources requested for use by the tenants (in S 201 ). 
       FIG. 6  is a diagram illustrating an example of corresponding relationships (load level information) between the types of operations of changing a resource and load levels representing loads caused by changes. Methods for changing a resource of a server include an upgrade, patch application, installation, a downgrade, and the like. The upgrade is a process of updating a version of software to a newer version (or writing the newer version over the older version). The patch application is a process of extracting only a part (difference information) called a patch file and to be changed, correcting a part of the program using the enumerated file, and thereby slightly upgrading the program. The installation is to newly install software in a computer and enable the software to be used. The downgrade is a process of updating a version of software to an older version. 
     Loads such as a cost caused by a change and a time period for the change vary depending on a method for changing a resource. Thus, in the example illustrated in  FIG. 6 , a load level is set as a value for each of the methods for changing a resource. The larger a value of a load level, the larger a load caused by a change. For example, a load caused by a change operation that is installation of an application or a downgrade of an application is larger than a load caused by a change operation that is an upgrade of an OS or application or patch application. A load caused by a change operation that is switching of OSs, a downgrade of an OS or a change of a DB is larger than a load caused by a change operation that is installation of an application or a downgrade of an application. According to a method for quantifying the levels of loads caused by changes, it is possible to quantitatively recognize how resources of servers are changed with small loads. Thus, the sharing may be efficiently executed. In the embodiment, a load level that represents a load caused by a change is referred to as a “distance”. The information illustrated in  FIG. 6  is registered in the memory  5  or  6  in advance. Information may be added to the information illustrated in  FIG. 6 . The information illustrated in  FIG. 6  may be changed. 
     Return to  FIG. 5 . Subsequently, the processor  7  calculates a distance for each of combinations of resources before changes and resources after the changes (in S 202 ). 
       FIG. 7  is a state transition diagram illustrating an example of the resources requested for use by the tenants.  FIG. 7  illustrates results of calculating, based on the load level information illustrated in  FIG. 6 , distances caused by changes of resources  21 ,  22 ,  23 ,  24 ,  25 ,  26 , and  27  to other resources. Resources from which arrows extend represent resources before the changes, while resources to which the arrows extend represent resources after the changes. Each of arrows that point both directions represents that a distance caused by a change of a certain resource to another resource is the same as a distance caused by a change of the other resource to the certain resource. In  FIG. 7 , UPG represents an upgrade and DNG represents a downgrade. 
     A method for calculating a distance caused by a change of the resource  21  to the resource  22  is described below. 
     As illustrated in  FIG. 7 , the resource  21  includes OS-a  4 . 5  as an OS and App-a  2 . 4  as an application. The resource  22  includes OS-a  4 . 5  as an OS and App-a  2 . 6  as an application. Since the type of the OS of the resource  21  before the change is the same as the type of the OS of the resource  22  after the change, the OS is not changed. Thus, referring to  FIG. 6 , a distance related to the OS is 0. The types of the applications of the resources  21  and  22  are the same, while the versions of the applications of the resources  21  and  22  are different from each other and are  2 . 4  and  2 . 6 , respectively. Since the version of the application of the resource  22  is newer than the version of the application of the resource  21 , the application is changed by upgrading. Referring to  FIG. 6 , a distance caused by upgrading an application is 1. Thus, the distance caused by the change from the resource  21  to the resource  22  is calculated by summing the distance related to the OS and the distance related to the applications or is calculated to be 0+1=1. 
     Next, a method for calculating a distance caused by a change in a direction opposite to the aforementioned direction or by the change from the resource  22  to the resource  21  is described. 
     Since the type of the OS of the resource  21  before the change is the same as the type of the OS of the resource  22  after the change, the OS is not changed. Referring to  FIG. 6 , a distance related to the OS is 0. The types of the applications of the resources  21  and  22  are the same, while the versions of the applications of the resources  21  and  22  are different from each other and are  2 . 4  and  2 . 6 , respectively. Since the version of the application of the resource  21  is older than the version of the application of the resource  22 , the application is changed by downgrading. Referring to  FIG. 6 , a distance caused by downgrading an application is 2. Thus, the distance caused by the change from the resource  22  to the resource  21  is calculated by summing the distance related to the OS and the distance related to the applications or is calculated to be 0+2=2. When the distances are compared with each other, the load caused by the change from the resource  21  to the resource  22  is smaller than the load caused by the change from the resource  22  to the resource  21 . It is apparent that distances may be different depending on a change from a certain resource to another resource and a change from the other resource to the certain resource. 
     As another example, a method for calculating a distance caused by a change from the resource  23  to the resource  24  is described below. The resource  23  includes OS-a  4 . 0  as an OS and App-a  2 . 4  as an application. The resource  24  includes OS-a  4 . 5  as an OS and no application installed. Since the type of the OS of the resource  23  before the change is the same as the type of the OS of the resource  24  after the change, the OS is not changed. Referring to  FIG. 6 , a distance related to the OS is 0. The resource  24  after the change does not include an application installed. Thus, the application is changed by uninstalling the application. Thus, referring to  FIG. 6 , a distance caused by the change of the application is 2. Thus, the distance caused by the change from the resource  23  to the resource  24  is calculated by summing the distance related to the OS and the distance related to the application or is calculated to be 0+2=2. 
     Next, a method for calculating a distance caused by a change in a direction opposite to the aforementioned direction or by the change from the resource  24  to the resource  23  is described. Since the type of the OS of the resource  23  before the change is the same as the type of the OS of the resource  24  after the change, the OS is not changed. Referring to  FIG. 6 , a distance related to the OS is 0. The resource  24  does not include an application installed. Thus, the application is changed by installing the application. Referring to  FIG. 6 , a distance caused by the change of the application is 2. Thus, the distance caused by the change from the resource  24  to the resource  23  is calculated by summing the distance related to the OS and the distance related to the application or is calculated to be 0+2=2. In the embodiment, it is apparent that distances may be the same regardless of changes of resources and that a load caused by a change from a certain resource to another resource and a load caused by a change from the other resource to the certain resource may not be substantially different. 
     According to the embodiment, values that represent loads caused by changes and correspond to the types of methods for changing a resource are set, values are assigned to each of combinations of resources included in a server before changes and resources included in a server after the changes and are summed. According to this method, it is possible to quantitatively recognize that a load caused by the sharing is reduced by selecting a certain resource to be changed and a resource to which the certain resource is to be changed. 
     Return to  FIG. 5 . Subsequently, the processor  7  calculates similarities between the resources requested for use by the tenants (in S 203 ). The similarities between the resources requested for use by the tenants may be calculated according to Equation (1). 
     
       
         
           
             
               
                 
                   
                     
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     In Equation (1), Dis(T m , T n ) represents a distance between tenants T m  and T n . Dis(T m , T n ) represents a similarity between a resource to be used by the tenant T m  and a resource to be used by the tenant T n  in a case where the resource to be used by the tenant T m  is changed to the resource to be used by the tenant T n . C(T m , i) represents an i-th resource (an application and an OS) of the tenant T m . D(C(T m , i), C(T n , j)) represents a distance between the resource C(T m , i) and a resource C(T n , j). D(C(T m , i), C(T n , j)) represents a similarity between the resource C(T m , i) and the resource C(T n , j) in a case where the resource C(T m , i) is changed to the resource C(T n , j). 
       FIG. 8  illustrates an example in which a distance between a resource to be used by a tenant T 1  and a resource to be used by a tenant T 2  is calculated. As illustrated in  FIG. 8 , the resource to be used by the tenant T 1  includes two resources  31  and  32 , while the resource to be used by the tenant T 2  includes three resources  33 ,  34 , and  35 . Each of arrows illustrated in  FIG. 8  points from a resource of the tenant T 1  or T 2  to a resource of the other tenant T 1  or T 2  so as to ensure that the resources cause a distance between the resources to be smallest. Numbers within parentheses represent loads caused by changes. 
     A distance caused by a change from the tenant T 1  to the tenant T 2  may be calculated as follows, for example. When each of the resources  31  and  32  of the tenant T 1  is to be changed to any of the resources of the tenant T 2 , resources that cause distances from the resources  31  and  32  to be smallest are searched from the resources  33 ,  34 , and  35 . As illustrated in  FIG. 8 , a resource that causes a distance between the resource and the resource  31  to be smallest is the resource  33  (the distance between the resources  31  and  33  is 0). A resource that causes a distance between the resource and the resource  32  is the resource  35  (the distance between the resources  32  and  35  is 2). Thus, a similarity D dis  (T 1 , T 2 ) between the tenants T 1  and T 2  when the tenant T 1  is changed to the tenant T 2  is calculated according to Equation (1) by summing the two distances or calculated to be 0+2=2. 
     A distance caused by a change from the tenant T 2  to the tenant T 1  may be calculated as follows, for example. When each of the resources  33 ,  34  and  35  of the tenant T 2  is to be changed to any of the resources of the tenant T 1 , resources that cause distances from the resources  33 ,  34 , and  35  to be smallest are searched from the resources  31  and  32 . As illustrated in  FIG. 8 , a resource that causes a distance between the resource and the resource  33  to be smallest is the resource  31  (the distance between the resources  31  and  33  is 0). A resource that causes a distance between the resource and the resource  34  is the resource  31  (the distance between the resources  31  and  34  is 2). A resource that causes a distance between the resource and the resource  35  is the resource  32  (the distance between the resources  32  and  35  is 6). Thus, a similarity D dis  (T 2 , T 1 ) between the tenants T 2  and T 1  when the tenant T 2  is changed to the tenant T 1  is calculated according to Equation (1) by summing the three distances or calculated to be 0+2+4=6. 
       FIG. 9  is a diagram illustrating an example of results of calculating similarities between resources requested for use by the tenants A, B, C, D, E, and F illustrated in  FIG. 4 . In  FIG. 9 , symbols A to F written along vertical lines represent the tenants that use resources before changes, while symbols A to F written along horizontal lines represent the tenants that use resources after the changes. As a value that represents a similarity is reduced, the similarity becomes higher and a load caused by a change is reduced. When a tenant that uses a resource before a change is the same as a tenant that uses a resource after the change, the tenant is not changed and “−” is illustrated in  FIG. 9 . In the example illustrated in  FIG. 9 , when a tenant that uses a resource before a change is the tenant C, and a tenant that uses a resource after the change is the tenant E, a similarity between the tenants C and E is 12. 
     When the process of S 203  is terminated, the processor  7  determines, based on the similarities calculated, target tenants that are tenants related to the sharing (in S 103 ). 
     In S 103 , the processor  7  sets a threshold for the similarities. Then, the processor  7  extracts, from the information illustrated in  FIG. 9 , a combination of tenants between which a similarity is lower than the set threshold.  FIGS. 10A, 10B, and 10C  illustrate examples of the extraction of the combination of the tenants targeted for the sharing. In the embodiment, the threshold for the similarities is set to 10. As illustrated in  FIG. 10A , combinations of tenants that request use of certain resources to be aggregated and tenants that request use of resources into which the certain resources are to be aggregated are extracted so as to ensure that thresholds for similarities between the tenants are less than 10. Numbers surrounded by circles represent the thresholds of less than 10. Thus, the tenants A, B, C, E, and F are determined as tenants targeted for the sharing. 
     Return to  FIG. 3 . Subsequently, a similar resource is determined and an operation cost is calculated (in S 104 ). 
     The similar resource is a resource that may be shared by multiple tenants and is a candidate resource to be shared. For example, the similar resource includes a part of an existing resource already used by the multiple tenants. It is preferable that the similar resource be similar to a configuration of a resource requested by the tenants as much as possible. 
     An example of a method for determining a similar resource and a method for calculating an operation cost is described with reference to  FIGS. 10A, 10B, 10C, and 11 .  FIG. 11  is a flowchart of an example of a process of determining a similar resource and calculating an operation cost. 
     First, the tenants are grouped based on the calculated distances between the tenants (in S 301 ). Referring to  FIG. 10A , the tenants A, B, and C may be grouped into a single group. The tenants E and F may be grouped into a single group. 
     Subsequently, a similar resource within each of the groups is determined (in S 302 ).  FIGS. 10B and 10C  are state transition diagrams illustrating examples of the combinations of the tenants extracted and targeted for the sharing. In  FIGS. 10B and 10C , blocks from which arrows extend represent tenants that request use of certain resources to be aggregated, while blocks to which the arrows extend represent tenants that request use of resources into which the certain resources are to be aggregated. 
     The similar resource may be determined as follows, for example. 
     Referring to  FIG. 10B , a resource that is among resources requested for use by the tenants A, B, and C and into which resources are to be aggregated with a small load is determined using similarities. 
     If resources of the tenants B and C are aggregated into a resource of the tenant A, a similarity corresponding to a change from the resource of the tenant B to the resource of the tenant A is 4. However, a similarity corresponding to a change from the resource of the tenant C to the resource of the tenant A is a value (similarity of 10) equal to the threshold and is not extracted. Thus, a method for aggregating the resources of the tenants B and C into the resource of the tenant A is excluded from candidates for the method for determining the similar resource. 
     If the resources of the tenants A and C are aggregated into the resource of the tenant B, a similarity corresponding to a change from the resource of the tenant A to the resource of the tenant B is 3. A similarity corresponding to a change from the resource of the tenant C to the resource of the tenant B is 6. Thus, if the resources of the tenants A and C are aggregated into the resource of the tenant B, the sum of the similarities are calculated to be 3+6=9. 
     If the resources of the tenants A and B are aggregated into the resource of the tenant C, a similarity corresponding to a change from the resource of the tenant A to the resource of the tenant C is 6. A similarity corresponding to a change from the resource of the tenant B to the resource of the tenant C is 6. Thus, if the resources of the tenants A and B are aggregated into the resource of the tenant C, the sum of the similarities are calculated to be 6+6=12. 
     The sums of the similarities are compared based on the calculated results. Then, the method that causes the sum of the similarities to be smallest and is to aggregate the resources of the tenants A and C into the resource of the tenant B is determined as the method for determining the similar resource. 
     Referring to  FIG. 10C , a resource that is among resources of the tenants E and F and into which a resource is to be aggregated with a smaller load is determined using similarities. 
     If the resource of the tenant E is aggregated into the resource of the tenant F, a similarity corresponding to a change from the resource of the tenant E to the resource of the tenant F is 2. If the resource of the tenant F is aggregated into the resource of the tenant E, a similarity corresponding to a change from the resource of the tenant F to the resource of the tenant E is 1. Thus, the method that causes the similarity to be smaller and is to aggregate the resource of the tenant F into the resource of the tenant E is determined as the method for determining the similar resource. 
       FIG. 12  is a flowchart of a modified example of the process of determining a similar resource and calculating an operation cost. A similar resource determined may cause a failure of an operation of a server. For example, if an OS is downgraded to an older version due to the execution of the sharing, and an application installed does not have compatibility with the OS of the older version, the application may not be executed and may cause a failure. In the modified example illustrated in  FIG. 12 , after a similar resource is determined, a process of determining whether or not an operation with the similar resource is possible is additionally executed. 
     Processes to be executed in S 301  and S 302  illustrated in  FIG. 12  are the same as the processes to be executed in S 301  and S 302  illustrated in  FIG. 11 . After a similar resource within each of the groups is determined in S 302 , it is determined whether or not operations with the similar resources determined are possible (in S 304 ). Whether or not the operations with the similar resources are possible is determined by searching information stored in the memory  5  and representing constraints for OS constituent elements and confirming whether or not the operations with the similar resources are possible, for example. If it is determined that the operations with the similar resources are possible (Yes in S 304 ), the process proceeds to S 303 . If it is determined that an operation with any of the similar resources is not possible (No in S 304 ), the process returns to S 302  and the similar resource within an interested group is determined again. 
     By determining whether or not an operation with a similar resource is possible after determination of the similar resource, a resource that is not suitable for an operation may be removed. Thus, the accuracy of determining a similar resource may be improved. 
     Return to  FIG. 11 . An operation cost when the similar resource is used by a tenant is calculated (in S 303 ). 
     The processor  7  calculates information on the cost of the operation with the similar resource based on information of the similar resource determined in S 302  and information stored in the memory  5  and representing the costs of the operations with the resources. 
     First, an operation cost per tenant is described. For example, the operation cost c per tenant is expressed by Equation (2). 
     
       
         
           
             
               
                 
                   
                     c 
                     = 
                     
                       S 
                       + 
                       
                         P 
                         · 
                         
                           ( 
                           
                             1 
                             - 
                             
                               
                                 n 
                                 - 
                                 1 
                               
                               T 
                             
                           
                           ) 
                         
                       
                     
                   
                   ; 
                 
               
               
                 
                   Equation 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   
                     ( 
                     2 
                     ) 
                   
                 
               
             
           
         
       
     
     In Equation (2), S is a fixed cost per tenant, P×(1−(n−1)/T) is a variable cost that varies due to sharing of a resource, P is the maximum value of the variable cost per tenant, T is the total number of tenants, and n is the number of tenants that share the resource. 
     For example, when all 100 tenants separately use different resources, T=100 and n=1. When T=100, n=1, and T and n are substituted into Equation (2), an operation cost c silo  is expressed by Equation (3) and is maximal.
 
 c   silo   =S+P   Equation (3);
 
     For example, when all the 100 tenants shares a single resource, T=100 and n=100. When T=100, n=100, and T and n are substituted into Equation (2), an operation cost c share  is expressed by Equation (4) and is minimal. 
     
       
         
           
             
               
                 
                   
                     
                       c 
                       share 
                     
                     = 
                     
                       S 
                       + 
                       
                         P 
                         100 
                       
                     
                   
                   ; 
                 
               
               
                 
                   Equation 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   
                     ( 
                     4 
                     ) 
                   
                 
               
             
           
         
       
     
     The amount (reduction effect) c silo −c share  of a reduction, caused by the execution of the sharing, in the cost of an operation with the resources may be calculated according to Equation (5) using Equations (3) and (4).
 
 c   silo   −c   share =0.99 ·P   Equation (5);
 
     Then, an operation cost c (A, B, C)  when the resources of the tenants A and C are aggregated into the resource of the tenant B is calculated. In this case, the three tenants among the six tenants share the resource. Thus, when T=6, n=3, and T and n are substituted into Equation (2), the operation cost c (A, B, C)  may be calculated according to Equation (6).
 
 c   (A,B,C)   =S+ ⅔ ·P   Equation (6);
 
     The amount c silo −c (A, B, C)  of a reduction, caused by the execution of the sharing, in the operation cost may be calculated according to Equation (7) using Equations (3) and (6).
 
 c   silo   −c   (A,B,C) =⅓ ·P   Equation (7);
 
     An operation cost c (E, F)  when the resource of the tenant E or F is aggregated into the resource of the other tenant E or F is calculated. In this case, the two tenants among the six tenants share the resource. Thus, when T=6, n=2, and T and n are substituted into Equation (2), the operation cost c (E, F)  may be calculated according to Equation (8).
 
 c   (E,F)   =S+ ⅚ ·P   Equation (8);
 
     The amount c silo−c   (E, F)  of a reduction, caused by the execution of the sharing, in the operation cost may be calculated according to Equation (9).
 
 c   silo   −c   (E,F) =⅙ ·P   Equation (9);
 
     The actual operation costs expressed by Equations (2) to (9) may be calculated by acquiring values of S and P from the information, stored in the memory  5 , of the costs of the operations with the resources and substituting the acquired values into Equations (2) to (9). 
     When S 303  is terminated, the generated information (resource information) of the similar resource and information of the cost of an operation with the similar resource are presented to the target tenants (in S 105 ). 
     In this case, an operation cost when a resource requested by the target tenants is used, and an operation cost when the similar resource is used, may be presented. Alternatively, the amount of a reduction, caused by the use of the similar resource instead of the resource requested for use by the target tenants, in the operation cost may be presented. The amount of the reduction in the operation cost is the difference between the operation cost when the resource requested by the tenants is used and the operation cost when the similar resource is used. Alternatively, the operation costs and the amount of the reduction in the operation cost may be presented. 
     In S 105 , the processor  7  transmits, to the interface (I/F)  9  included in the information processing device  3 , a signal to instruct the interface (I/F)  9  to transmit, to terminals owned by the target tenants, the information of the similar resource and the information on the cost, calculated in S 303 , of the operation with the similar resource. The interface (I/F)  9  transmits, based on the signal received from the processor  7 , the signal including the information of the similar resource and the information of the amount of the reduction in the cost of the operation with the similar resource to the terminals that are among the terminals  2   a  to  2   e  and owned by the target tenants. 
       FIG. 13  is a diagram illustrating an example in which the information of the similar resource and the information of the cost of the operation with the similar resource are presented to the target tenants.  FIG. 13  illustrates the example in which the amount of a reduction in an operation cost is presented as the information of the cost of the operation with the similar resource. 
     As illustrated in  FIG. 13 , the information processing device  3  transmits, to the terminals  2   a ,  2   b , and  2   c  of the tenants A, B, and C, information related to a similar resource and to be used to aggregate the resources of the tenants A and C into the resource of the tenant B and information of the amount (c silo −c (A, B, C) =(⅓)×P) of the reduction, obtained upon the execution of the similar resource, in the cost of the operation with the resources. The information processing device  3  presents, to the tenants E and F, information related to a similar resource and to be used to aggregate the resource used by the tenant F into the resource used by the tenant E and information of the amount (c silo −c (E, F) =(⅙)×P) of a reduction, obtained upon the execution of the sharing, in a cost of an operation with the resources. Since the tenant D is not a target tenant, the information processing device  3  does not transmit the aforementioned information to the terminal  2   d  of the tenant D. 
     In this manner, the difference between an operation cost when a resource requested by target tenants is used and an operation cost when a similar resource is used is presented to the target tenants. Thus, the target tenants obtain, as an option, the resource similar to the requested resource and may quantitatively recognize a cost advantage caused by the use of the similar resource. Thus, the target tenants may easily determine whether to use the requested resource or the similar resource. 
     Subsequently, the target tenants, which receive the information on the similar resource and the information of the amount of the reduction in the cost of the operation with the resources, determine whether to approve the use of the similar resource while comparing costs caused by the change of the resources with the cost advantage. If the target tenants approve the use of the similar resource, terminals owned by the target tenants transmit, to the interface (I/F)  9 , a signal representing that the target tenants approve the use of the similar resource. If the target tenants do not approve the use of the similar resource, the terminals owned by the target tenants transmit, to the interface (I/F)  9 , a signal representing that the target tenants do not approve the use of the similar resource. 
     Return to  FIG. 3 . Subsequently, the processor  7  determines whether or not all the target tenants approve the use of the similar resource (in S 106 ). If the processor  7  determines that all the target tenants approve the use of the similar resource (Yes in S 106 ), the processor  7  transmits, to the interface (I/F)  8 , a signal to instruct to share the interested resource. The interface (I/F)  8  transmits, to the management terminal  4  included in the cloud system infrastructure  1 , a signal to instruct to transition to the sharing. The management terminal  4  receives the signal to instruct to transition to the sharing and execute the sharing such as an upgrade or installation in an interested server among the servers  1   a  to  1   d.    
     If the processor  7  determines that any of the target tenants does not approve the use of the similar resource (No in S 106 ), the processor  7  excludes, from the target tenants, the tenant that does not approve the use of the similar resource (in S 108 ). After that, the processor  7  determines whether or not target tenants exist (in S 109 ). If the processor  7  determines that the target tenants do not exist (No in S 109 ), the processor  7  terminates the process since the sharing is not executed. If the processor  7  determines that the target tenants exist (Yes in S 109 ), the process returns to S 104 , and the processor  7  determines a resource similar to resources used by the remaining tenants and calculates a cost advantage again. 
     In this manner, the processor  7  excludes, from target tenants, a tenant that does not approve the use of a similar resource, and the processor  7  repeats the process until all target tenants approve the use of the similar resource. Thus, the sharing may be executed by a method optimal for the target tenants after all the target tenants approve the use of the similar resource. 
     Even if the provider presents information of a similar resource to target tenants, the provider may not immediately obtain answers from the target tenants. Especially, if the provider obtains approval results from almost all tenants to which the information of the similar resource has been presented, and the provider does not obtain an approval result from a part of the target tenants, the sharing is delayed while not being executed. Thus, a tenant determined whether to approve the use of a similar resource may face a disadvantage and the amount of a reduction in an operation cost may change due to a change of market conditions. Thus, before the information processing device  3  transmits information of a similar resource to target tenants, it is preferable that a predetermined time period after the transmission of the information be set as a time period for an answer. 
       FIG. 14  is a flowchart of a modified example of operations of the information processing device according to the embodiment. In the example illustrated in  FIG. 14 , processes to be executed before S 105  are the same as the processes illustrated in  FIG. 3 . A time is measured while a time when the information of the similar resource and the information of the operation cost when the similar resource is used are transmitted in S 105  is treated as a start time (in S 110 ). In S 110 , a clock or the like that is included in the processor  7  may measure the time. 
     Subsequently, the processor  7  determines whether or not the processor  7  has received approval results from the terminals of the target tenants (in S 111 ). If the processor  7  has received the approval results from the terminals of the target tenants (Yes in S 111 ), the process proceeds to S 106 . If the processor  7  determines that the processor  7  does not receive the approval result from a terminal of any of the target tenants (No in S 111 ), the processor  7  determines whether or not a predetermined time period elapses after the transmission (S 112 ). If the processor  7  determines that the predetermined time period elapses after the transmission (Yes in S 112 ), the processor  7  determines that the interested target tenant does not approve the use of the similar resource (in S 113 ). If the processor  7  determines that the predetermined time period does not elapse after the transmission (No in S 112 ), the process returns to S 111 . 
     In this manner, the predetermined time period after transmission is set as the time period for an answer, a target tenant that does not provide an approval result within the time period for an answer is treated as a disapproving tenant and excluded from target tenants, and the determination of a resource that is similar to a resource used by remaining tenants is quickly promoted. Thus, a delay of the sharing may be suppressed. 
       FIG. 15  is a diagram illustrating an example of resources before the execution of the sharing and resources of after the execution of the sharing. As illustrated in  FIG. 15 , after the sharing, the tenants A, B, and C use a server that has a resource including OS-a  4 . 5  as an OS and App-a  2 . 4  as an application and a resource including OS-a  4 . 5  as an OS and App-b  4 . 1  as an application. Since the tenant D is not a tenant targeted for the sharing, a resource of the tenant D is not changed. After the sharing, the tenants E and F use a server that has a resource including OS-b  2 . 0  as an OS and App-b  7 . 0  as an application and a resource including OS-b  2 . 0  as an OS and App-b  5 . 0  as an application. In this manner, the tenants A, B, and C may reduce a resource by the sharing. 
       FIG. 16  is a diagram illustrating results of calculating, based on the example illustrated in  FIG. 15 , the numbers of constituent elements of resources before and after the execution of the sharing and the numbers of types of the constituent elements of the resources before and after the execution of the sharing. Aggregation ratios illustrated in  FIG. 16  are defined as ratios of the numbers before the aggregation to the numbers after the aggregation. The smaller the aggregation ratios illustrated in  FIG. 16 , the larger effects of the aggregation. As illustrated in  FIG. 16 , the number of constituent elements and the number of types of the constituent elements may be reduced by the execution of the sharing. It is apparent that the aggregation effect corresponding to the numbers of the constituent elements before and after the execution of the sharing is larger than the aggregation effect corresponding to the numbers of the types of the constituent elements before and after the execution of the sharing. Thus, an operation cost may be reduced while the complexity and scale of a system are suppressed. 
     According to the embodiment, a similar resource is determined based on similarities calculated based on information of resources. Then, a cost of an operation with the similar resource determined is calculated, and information of the similar resource and information on the cost of the operation with the similar resource are presented to target tenants. Thus, an architecture of cloud computing may be efficiently, flexibly used by the provider and the tenants. Specifically, the provider obtains approval from tenants, and an architecture of a server installed in a data center may be simplified. As a result, the complexity of the server may be improved, and an operation cost per tenant may be reduced. In addition, each tenant may recognize an advantage provided by the provider and select a resource. Thus, the flexibility of the selection may be obtained. 
       FIGS. 17A and 17B  are diagrams illustrating an example of the type of a multi-tenant architecture that is achieved in the embodiment.  FIG. 17B  illustrates a configuration including a plurality of multi-tenant native PaaSs. The configuration illustrated in  FIG. 17B  is achieved by grouping and aggregating resources that are the same as or similar to each other or and are included in servers used by tenants and forming the plurality of multi-tenant native PaaSs that are relatively small, as illustrated in  FIG. 17A . 
       FIGS. 18A and 18B  are diagrams illustrating another example of the type of the multi-tenant architecture that is achieved in the embodiment.  FIG. 18B  illustrates a configuration in which all tenants do not use a single multi-tenant native PaaS and share only a part of resources. This configuration illustrated in  FIG. 18B  is achieved by extracting the part to be shared from resources used by the tenants so as to share the part and cause the configuration to form a single architecture while referencing a configuration illustrated in  FIG. 18A . 
     Although the embodiment is described above, the techniques disclosed herein are not limited to the specific embodiment and may be modified or changed in various manners.  FIGS. 19A and 19B  are diagrams illustrating modified examples of the definition of distances between resources. In the embodiment, load levels that represent loads caused by changes of resources are used as distances. As illustrated in  FIG. 19A , however, costs for changes of resources may be expressed by distances. In addition, as illustrated in  FIG. 19B , times (numbers of processes) for changes of resources may be used as distances. 
     All examples and conditional language recited herein are intended for pedagogical purposes to aid the reader in understanding the invention and the concepts contributed by the inventor to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions, nor does the organization of such examples in the specification relate to a showing of the superiority and inferiority of the invention. Although the embodiment of the present invention has been described in detail, it should be understood that the various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the invention.