Abstract:
A method and system for transmitting information based on social network is provided in the present invention, in order to solve the problem that information transmission within users of a social network may cost high resources. The method includes: calculating information transmission capacity of an obtained user identity according to user information corresponding to the obtained user identity; storing user identities of which transmission capacities are greater than a predetermined threshold into an initial seed user queue; and transmitting information to be sent to a client of which the user identity is stored in the initial seed user queue. Since information to be sent is targeted transmitted to users in a social network having relative high transmission capacities, the cost of information transmission within the users will be reduced.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to computer technology, and more particularly relates to a method and system for transmitting information based on social network. 
       BACKGROUND OF THE INVENTION 
       [0002]    In the existing Internet, a social network formed by online netizens not only includes a relation between individual users, but also includes one to many relation and many to many relation. The social network includes online users and their relation networks. In the social network, there are massive users and massive relation data. Therefore, how to perform a low-cost and effective transmission of information within the massive users of the social network, e.g., propagandize and promote public benefit activities within netizens, becomes a problem to be solved. In a conventional technology, information concerning propagation and promotion of public benefit activities is randomly sent within netizens. It is apparent that to propagandize and promote information to random users in the social network has a poor pertinence, and may cost high resources for achieving a good effect. For example, when information is to be sent to 1,000 users based on an instant messaging (IM) platform, the 1,000 users for receiving the information to be sent may be selected from 10,000 users. If a desired result is not achieved, another 1,000 users has to be selected randomly for receiving the information, which may occupy a great deal of resources for the IM platform. The same problem also exists in a Web 2.0-based social network. 
       SUMMARY OF THE INVENTION 
       [0003]    In the conventional art, information transmission within users of a social network may cost high resources. In order to solve this problem, a method for transmitting information based on social network is provided in an embodiment of the present invention, including: 
         [0004]    calculating information transmission capacity of an obtained user identity according to user information corresponding to the obtained user identity; 
         [0005]    storing user identities of which transmission capacities are greater than a predetermined threshold into an initial seed user queue; and 
         [0006]    transmitting information to be sent to a client of which the user identity is stored in the initial seed user queue. 
         [0007]    Further, a system for transmitting information based on social network is provided in an embodiment of the present invention, including: 
         [0008]    a calculation module, adapted for calculating information transmission capacity of an obtained user identity according to user information corresponding to the obtained user identity; 
         [0009]    a writing module, adapted for storing user identities of which transmission capacities are greater than a predetermined threshold into an initial seed user queue; and 
         [0010]    a transmitting module, adapted for transmitting information to be sent to a client of which the user identity is stored in the initial seed user queue. 
         [0011]    Further, a system for transmitting information based on social network is provided in an embodiment of the present invention, including: 
         [0012]    a server, adapted for calculating information transmission capacity of an obtained user identity according to user information corresponding to the obtained user identity, storing user identities of which transmission capacities are greater than a predetermined threshold into an initial seed user queue, expanding the initial seed user queue to get an expanded user queue including a predetermined number of user identities according to the user relation information corresponding to the user identities in the initial seed user queue, and transmitting information to be sent to a client of which the user identity is stored in the initial seed user queue; and 
         [0013]    a client with a user identity included in the initial seed user queue, adapted for transmitting information to be sent to other clients of which user identities are included in the expanded user queue. 
         [0014]    It can be seen from the above scheme provided in embodiments of the present invention that, since information to be sent is transmitted to target users in a social network having relative high transmission capacities, the cost of information transmission within the users will be reduced. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0015]      FIG. 1  is a flow chart illustrating a method provided in the first embodiment of the present invention; 
           [0016]      FIG. 2  is a flow chart illustrating a method provided in the first embodiment of the present invention; 
           [0017]      FIG. 3  is a block diagram illustrating a system provided in the second embodiment of the present invention; 
           [0018]      FIG. 4  is a block diagram illustrating a system provided in the third embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0019]    The first embodiment of the present invention provides a method for transmitting information based on social network, of which the process is shown in  FIG. 1  which includes the following steps. 
         [0020]    Step  101 : extracting activity level information and user relation information bound to user identities from a user information database of social network users, and storing them. 
         [0021]    Here, the activity level information may include one or more of the following information: online time of a user, a frequency of interacting with friends, a frequency of visiting friends&#39; spaces, a frequency of updating a log space etc., for indicating activity level of the user in the social network. The activity level information can be stored in a way shown in Table 1. 
         [0000]    
       
         
               
               
               
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                 Unique 
                   
                   
                   
                   
               
               
                 identity 
               
               
                 in 
               
               
                 a social 
                   
                 Frequency of 
                 Frequency of 
                 Frequency of 
               
               
                 network 
                 Online 
                 interacting with 
                 visiting friends&#39; 
                 updating a log 
               
               
                 system 
                 time 
                 friends 
                 spaces 
                 space 
               
               
                   
               
             
             
               
                 10001 
                 3 hours 
                 30 times per day 
                 3 times per day 
                 0.3 times per day 
               
               
                 10002 
                 2 hours 
                 20 times per day 
                 2 times per day 
                 0.2 times per day 
               
               
                   
               
             
          
         
       
     
         [0022]    User relation information is expressed as (ID 1 , relation type  1 ), . . . , (IDn, relation type  2 ), used to represent relation of a user with other users in the social network. For example, relation types are defined as friend, awareness and stranger. For user A, he has a friend B and is aware of C. Also, user A has a visit to a stranger D&#39;s blog. Then, the user relation information of user A can be described as (B, Friend), (C, Awareness) and (D, Stranger), which is shown in Table 2. 
         [0000]    
       
         
               
               
             
           
               
                 TABLE 2 
               
               
                   
               
               
                 User identity in a 
                   
               
               
                 social network system 
                 User relation information 
               
               
                   
               
             
             
               
                 10001 
                 (ID1, relation type 1), . . . , (IDn, relation type 2) 
               
               
                 10002 
                 (ID1, relation type 2), . . . , (IDn, relation type 1) 
               
               
                   
               
             
          
         
       
     
         [0023]    Step  102 : calculating transmission capacity of each user identity according to the activity level information and the user relation information of the user identity, and sorting the transmission capacities in a descending order. 
         [0024]    For example, an activity level component f n x n  corresponding to activity level information x n  is obtained according to the activity level information x n  corresponding to user identity  10001  and a coefficient f n  of the activity level information x n , a quantified value A (user ID) of the activity level information corresponding to the user identity is obtained via summing up all activity level components of the user identity, a quantified value R (user ID) of user relation information of the user identity is obtained according to all the user relation information r 1 , r 2 , . . . , r j  corresponding to the user identity, and the transmission capacity T (user ID) of the user identity is obtained via evaluating a weighted sum of the quantified value A (user ID) of the activity level information corresponding to the user identity and the quantified value R (user ID) of the user relation information corresponding to the user identity. 
         [0025]    The activity level information corresponding to the user identity is calculated as follows: 
         [0000]    
       
         
           
             
               
                 A 
                  
                 
                     
                 
                  
                 
                   ( 
                   
                     user 
                      
                     
                         
                     
                      
                     ID 
                   
                   ) 
                 
               
               = 
               
                 
                   ∑ 
                   
                     n 
                     = 
                     1 
                   
                   N 
                 
                  
                 
                   
                     f 
                     n 
                   
                    
                   
                     x 
                     n 
                   
                 
               
             
             , 
           
         
       
     
         [0000]    wherein A (user ID) represents a quantified value of activity level information corresponding to a user identity. 
         [0026]    Here, N represents the total number of activity level information corresponding to a user identity, x n  represents activity level information corresponding to a user identity, f n  represents a coefficient of activity level information corresponding to a user identity wherein 
         [0000]    
       
         
           
             
               
                 ∑ 
                 
                   n 
                   = 
                   1 
                 
                 N 
               
                
               
                 f 
                 n 
               
             
             = 
             1. 
           
         
       
     
         [0027]    The user relation information corresponding to the user identity is calculated as follows: 
         [0000]    
       
         
           
             
               
                 R 
                  
                 
                     
                 
                  
                 
                   ( 
                   
                     user 
                      
                     
                         
                     
                      
                     ID 
                   
                   ) 
                 
               
               = 
               
                 
                   ∑ 
                   
                     j 
                     = 
                     1 
                   
                   M 
                 
                  
                 
                   r 
                   j 
                 
               
             
             , 
           
         
       
     
         [0000]    wherein M represents the total number of relation types included in user relation information of a user identity, R (user ID) represents a quantified value of user relation information corresponding to a user identity, r j  represents a quantified value of a relation type included in user relation information corresponding to a user identity. 
         [0028]    The transmission capacity corresponding to the user identity is calculated via evaluating a weighted sum of A (user ID) and R (user ID) as follows: T (user ID)=A (User ID)*f+R (User ID)*(1−f), wherein T (user ID) represents a transmission capacity corresponding to a user identity, and f is a weight factor. 
         [0029]    Step  103 : selecting a predetermined percentage of user identities according to a sorting result of transmission capacities in a descending order, and saving the selected user identities into an initial seed user queue. 
         [0030]    Of course, selecting a predetermined proportion of user identities according to corresponding transmission capacities ranked in a descending order is, in fact, to choose user identities having transmission capacities greater than a predetermined threshold, and a threshold value can be set appropriately to fit the proportion of user identities being selected to the predetermined proportion. For example, there are 10,000 user identities ranked according to their transmission capacities in a descending order, and a predetermined proportion of the user identities, e.g., 10% are chosen to be added into the initial seed user queue. The top 1,000 user identities are selected according to a predetermined threshold, wherein the predetermined threshold should be less than the transmission capacity corresponding to the 1,000th user identity while greater than the transmission capacity corresponding to the 1,001th user identity. In an instance, the initial seed user queue can have two user identities, such as  10001  and  10002 , and the user relation information corresponding to  10001  may include ( 10002 , relation type  1 ) or not include  10002 . Likewise, the user relation information corresponding to  10002  may include ( 10001 , relation type  1 ) or not include  10001 . 
         [0031]    Step  104 : as to every two user identities in the initial seed user queue, if there is a relation chain between them, a user identity on the relation chain is also put into the initial seed user queue. 
         [0032]    For example, user relation information corresponding to user identity  10001  in the initial seed user queue includes ( 10003 , relation type  1 ), and user relation information corresponding to user identity  10002  includes ( 10003 , relation type  2 ). Then, there is a relation chain between user identity  10001  and user identity  10002 , i.e.,  10001 - 10003 - 10002 , and user identity  10003  on the relation chain previously not included in the initial seed user queue can be added into the initial seed user queue. That is, user identities  10001  and  10002  are two user identities having a transmission capacity greater than a predetermined threshold, and a relation chain created by their respective user relation information includes at least one other user identity, e.g.,  10003 , wherein user identity  10003  does not belong to the selected user identities having a transmission capacity greater than a predetermined threshold. Then, user identity  10003  will be saved to the initial seed user queue. Similarly, when user relation information corresponding to user identity  10001  in the initial seed user queue includes ( 10003 , relation type  1 ), user relation information corresponding to user identity  10003  not belonging to the initial seed user queue includes ( 10004 , relation type  1 ), and user relation information corresponding to user identity  10002  includes ( 10004 , relation type  2 ), user identities  10001  and  10002  have a relation chain  10001 - 10003 - 10004 - 10002  between them. Thereafter, user identities  10003  and  10004  on the relation chain not previously included in the initial seed user queue are added to the initial seed user queue. After user identity  10003  is added into the initial seed user queue, subsequent transmission of information to be sent within an expanded user queue derived from the initial seed user queue is more efficient. 
         [0033]    Step  105 : expanding the initial seed user queue by using the relation chain for growth outward to form the expanded user queue until the number of user identities in the expanded user queue reaches a specified amount. 
         [0034]    As shown in  FIG. 2 , a specific implementation of step  105  can include the following steps. 
         [0035]    Step  1051 : establishing an empty expanded user queue. 
         [0036]    Step  1052 : removing the first user identity in the initial seed user queue, and adding it into the expanded user queue. 
         [0037]    Step  1053 : traversing all user relation information of the first user identity being removed, determining whether there is a user identity with the largest transmission capacity that has not yet appeared in both the initial seed user queue and the expanded user queue, and if yes, proceeding to step  1055 ; otherwise, proceeding to step  1054 . 
         [0038]    Step  1054 : checking whether the initial seed user queue is empty, and if yes, proceeding to step  1056  for ending the growth; otherwise, performing step  1055 . 
         [0039]    Step  1055 : adding the user identity to the end of the initial seed user queue, checking whether the expanded user queue reaches a specified size, and if yes, proceeding to step  1056  for ending the growth; otherwise, turning to step  1052 . 
         [0040]    Step  1056 : ending the growth of the expanded user queue, and saving the user identities of the expanded user queue as a user group list of the social network. 
         [0041]    Step  1057 : transmitting information to be sent to a client with a user identity included in the initial seed user queue, and forwarding by the client the information to be sent to other clients having user identities recorded in the user group list. As an example, the client can be a software client, web page or wireless mobile and so on. 
         [0042]    The second embodiment of the present invention provides a system for transmitting information based on social network, which has a structure shown in  FIG. 3  including: a server  10  and a client  20 . 
         [0043]    Server  10  is adapted for storing activity level information and user relation information bound to user identities extracted by server  10  from a user information database of social network users. 
         [0044]    Here, the activity level information may include: online time of a user, a frequency of interacting with friends, a frequency of visiting friends&#39; spaces, a frequency of updating a log space etc., for indicating activity level of the user in the social network. The activity level information can be stored in a way shown in Table 1. 
         [0000]    
       
         
               
               
               
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                 Unique 
                   
                   
                   
                   
               
               
                 identity 
               
               
                 in 
               
               
                 a social 
                   
                 Frequency of 
                 Frequency of 
                 Frequency of 
               
               
                 network 
                 Online 
                 interacting with 
                 visiting friends&#39; 
                 updating a log 
               
               
                 system 
                 time 
                 friends 
                 spaces 
                 space 
               
               
                   
               
             
             
               
                 10001 
                 3 hours 
                 30 times per day 
                 3 times per day 
                 0.3 times per day 
               
               
                 10002 
                 2 hours 
                 20 times per day 
                 2 times per day 
                 0.2 times per day 
               
               
                   
               
             
          
         
       
     
         [0045]    User relation information is expressed as (ID 1 , relation type  1 ), . . . , (IDn, relation type  2 ), used to represent relation of a user with other users in the social network. For example, relation types are defined as friend, awareness and stranger. For user A, he has a friend B and is aware of C. Also, user A has a visit to a stranger D&#39;s blog. Then, the user relation information of user A can be described as (B, Friend), (C, Awareness) and (D, Stranger), which is shown in Table 2. 
         [0000]    
       
         
               
               
             
           
               
                 TABLE 2 
               
               
                   
               
               
                 User identity in a 
                   
               
               
                 social network system 
                 User relation information 
               
               
                   
               
             
             
               
                 10001 
                 (ID1, relation type 1), . . . , (IDn, relation type 2) 
               
               
                 10002 
                 (ID1, relation type 2), . . . , (IDn, relation type 1) 
               
               
                   
               
             
          
         
       
     
         [0046]    The activity level information and the user relation information can be stored on server  10  in a form as shown in Table 1 and Table 2, respectively. Also, they can be stored on other accessible storage spaces of server  10  in other forms. 
         [0047]    Server  10  is adapted for calculating transmission capacity of each user identity according to the activity level information and the user relation information of the user identity, and sorting the transmission capacities in a descending order. 
         [0048]    For example, an activity level component f n x n  corresponding to activity level information x n  is obtained according to the activity level information x n  corresponding to user identity  10001  and a coefficient f n  of the activity level information x n , a quantified value A (user ID) of the activity level information corresponding to the user identity is obtained via summing up all activity level components of the user identity, a quantified value R (user ID) of user relation information of the user identity is obtained according to all the user relation information r 1 , r 2 , . . . , r j  corresponding to the user identity, and the transmission capacity T (user ID) of the user identity is obtained via evaluating a weighted sum of the quantified value A (user ID) of the activity level information corresponding to the user identity and the quantified value R (user ID) of the user relation information corresponding to the user identity. 
         [0049]    The activity level information corresponding to the user identity is calculated as follows: 
         [0000]    
       
         
           
             
               
                 A 
                  
                 
                     
                 
                  
                 
                   ( 
                   
                     user 
                      
                     
                         
                     
                      
                     ID 
                   
                   ) 
                 
               
               = 
               
                 
                   ∑ 
                   
                     n 
                     = 
                     1 
                   
                   N 
                 
                  
                 
                   
                     f 
                     n 
                   
                    
                   
                     x 
                     n 
                   
                 
               
             
             , 
           
         
       
     
         [0000]    wherein A (user ID) represents a quantified value of activity level information corresponding to a user identity. 
         [0050]    Here, N represents the total number of activity level information corresponding to a user identity, x n  represents activity level information corresponding to a user identity, f n  represents a coefficient of activity level information corresponding to a user identity wherein 
         [0000]    
       
         
           
             
               
                 ∑ 
                 
                   n 
                   = 
                   1 
                 
                 N 
               
                
               
                 f 
                 n 
               
             
             = 
             1. 
           
         
       
     
         [0051]    The user relation information corresponding to the user identity is calculated as follows: 
         [0000]    
       
         
           
             
               
                 R 
                  
                 
                     
                 
                  
                 
                   ( 
                   
                     user 
                      
                     
                         
                     
                      
                     ID 
                   
                   ) 
                 
               
               = 
               
                 
                   ∑ 
                   
                     j 
                     = 
                     1 
                   
                   M 
                 
                  
                 
                   r 
                   j 
                 
               
             
             , 
           
         
       
     
         [0000]    wherein M represents the total number of relation types included in user relation information of a user identity, R (user ID) represents a quantified value of user relation information corresponding to a user identity, r j  represents a quantified value of a relation type included in user relation information corresponding to a user identity. 
         [0052]    The transmission capacity corresponding to the user identity is calculated via evaluating a weighted sum of A (user ID) and R (user ID) as follows: T (user ID)=A (User ID)*f+R (User ID)*(1-f), wherein T (user ID) represents a transmission capacity corresponding to a user identity, and f is a weight factor. 
         [0053]    Server  10  is adapted for selecting a predetermined percentage of user identities according to a sorting result of transmission capacities in a descending order, and saving the selected user identities into an initial seed user queue. 
         [0054]    Of course, selecting a predetermined proportion of user identities according to corresponding transmission capacities ranked in a descending order is, in fact, to choose user identities having transmission capacities greater than a predetermined threshold, and a threshold value can be set appropriately to fit the proportion of user identities being selected to the predetermined proportion. For example, there are 10,000 user identities ranked according to their transmission capacities in a descending order, and a predetermined proportion of the user identities, e.g., 10% are chosen to be added into the initial seed user queue. The top 1,000 user identities are selected according to a predetermined threshold, wherein the predetermined threshold should be less than the transmission capacity corresponding to the 1,000th user identity while greater than the transmission capacity corresponding to the 1,001th user identity. 
         [0055]    Server  10  is adapted for putting a user identity on a relation chain into the initial seed user queue if there is the relation chain between every two user identities in the initial seed user queue. 
         [0056]    For example, user relation information corresponding to user identity  10001  in the initial seed user queue includes ( 10003 , relation type  1 ), and user relation information corresponding to user identity  10002  includes ( 10003 , relation type  2 ). Then, there is a relation chain between user identity  10001  and user identity  10002 , i.e.,  10001 - 10003 - 10002 , and user identity  10003  on the relation chain previously not included in the initial seed user queue can be added into the initial seed user queue. Similarly, when user relation information corresponding to user identity  10001  in the initial seed user queue includes ( 10003 , relation type  1 ), user relation information corresponding to user identity  10003  not belonging to the initial seed user queue includes ( 10004 , relation type  1 ), and user relation information corresponding to user identity  10002  includes ( 10004 , relation type  2 ), user identities  10001  and  10002  have a relation chain  10001 - 10003 - 10004 - 10002  between them. Thereafter, user identities  10003  and  10004  on the relation chain not previously included in the initial seed user queue are added to the initial seed user queue. 
         [0057]    Server  10  is adapted for expanding the initial seed user queue by using the relation chain for growth outward to form the expanded user queue until the number of user identities in the expanded user queue reaches a specified scale. 
         [0058]    Server  10  is adapted for establishing an empty expanded user queue. Also, server  10  is adapted for removing user identities from an initial seed user queue according to transmission capacities of user identities ranked in a descending order. For example, server  10  firstly removes the first user identity having the largest transmission capacity, traverses all user relation information of the first user identity being removed, selects from all the user relation information a user identity with the largest transmission capacity that has not yet appeared in the initial seed user queue and adds it into the initial seed user queue, and adds the first user identity into the expanded user queue. Then, server  10  removes the second user identity having the second largest transmission capacity out of the initial seed user queue, traverses all user relation information of the second user identity being removed, selects from all the user relation information a user identity with the largest transmission capacity that has not yet appeared in both the initial seed user queue and the expanded user queue. Server  10  continuously removes user identities from the initial seed user queue, selects from all the user relation information of the removed user identities a new user identity to be added into the initial seed user queue, and adds the removed user identities into the expanded user queue until the number of user identities in the expanded user queue reaches a predetermined amount. 
         [0059]    For example, user identities are ranked in a descending order as  10001 ,  10002  and  10003  according to transmission capacities of the user identities in an initial seed user queue. First, server  10  removes  10001  from the initial seed user queue and adds it into an expanded user queue. At the same time, server  10  goes through all user relation information corresponding to  10001  and chooses user identity  10011 , and adds  10011  to the end of the initial seed user queue. Here, candidate user identities include  20001 ,  10011  and  10003 , and the sequence of the user identities is  10003 ,  10011  and  20001  ranked according to transmission capacities in a descending order. Then, the initial seed user queue is  10002 ,  10003  and  10011 , and the expanded user queue is  10001 . 
         [0060]    Also, server  10  removes  10002  from the initial seed user queue and adds it into the expanded user queue. At the same time, server  10  goes through all user relation information corresponding to  10002  and chooses user identity  10012 , and adds  10012  to the end of the initial seed user queue. Here, candidate user identities include  20002 ,  10012  and  10003 , and the sequence of the user identities is  10003 ,  10012  and  20002  ranked according to transmission capacities in a descending order. Then, the initial seed user queue is  10003 ,  10011  and  10012 , and the expanded user queue is  10001  and  10002 . 
         [0061]    Further, server  10  removes  10003  from the initial seed user queue and adds it into the expanded user queue. At the same time, server  10  goes through all user relation information corresponding to  10003  and chooses user identity  10013 , and adds  10013  to the end of the initial seed user queue. Here, candidate user identities include  20003 ,  10013 ,  10001  and  10002 , and the sequence of the user identities is  10001 ,  10002 ,  10013  and  20003  ranked according to transmission capacities in a descending order. Then, the initial seed user queue is  10011 ,  10012  and  10013 , and the expanded user queue is  10001 ,  10002  and  10003 . 
         [0062]    Further, server  10  removes  10011  from the initial seed user queue and adds it into the expanded user queue. At the same time, server  10  goes through all user relation information corresponding to  10011  and chooses no user identity that can be added into the end of the initial seed user queue. Here, candidate user identities include  10001  and  10012 , while  10001  is in the expanded user queue and  10012  is in the initial seed user queue. Then, the initial seed user queue is  10012  and  10013 , and the expanded user queue is  10001 ,  10002 ,  10003  and  10011 . 
         [0063]    Further, server  10  removes  10012  from the initial seed user queue and adds it into the expanded user queue. At the same time, server  10  goes through all user relation information corresponding to  10012  and chooses user identity  10112 , adds  10112  to the end of the initial seed user queue. Here, candidate user identities include  20002 ,  10002  and  10112 , and the sequence of the user identities is  10002 ,  10112  and  20002  ranked according to transmission capacities in a descending order. Then, the initial seed user queue is  10013  and  10112 , and the expanded user queue is  10001 ,  10002 ,  10003 ,  10011  and  10012 . If a predetermined number of user identities in the expanded user queue is 5, server  10  ends the growth at this time. 
         [0064]    If the predetermined number of user identities of the expanded user queue is 8, server  10  continues to remove  10013  and  10112  from the initial seed user queue and add them into the expanded user queue, respectively. At the same time, server  10  goes through all user relation information corresponding to  10013  and  10112 , but finds no user identity that can be added to the end of the initial seed user queue. Then, the initial seed user queue is empty, and the expanded user queue is  10001 ,  10002 ,  10003 ,  10011 ,  10012 ,  10013  and  10112 . After that, server  10  ends the growth. 
         [0065]    The above is merely a preferred instance. Broadly speaking, server  10  can form an expanded user queue via expanding the initial seed user queue by using a relation chain for growth outward, until the number of user identities of the expanded user queue meets a specified scale. 
         [0066]    Server  10  may perform the following steps when forming the expanded user queue according to the initial seed user queue by using a relation chain for growth outward. 
         [0067]    Step  2051 : establishing an empty expanded user queue. 
         [0068]    Step  2052 : removing a first user identity from the initial seed user queue, and adding it into the expanded user queue. 
         [0069]    Step  2053 : traversing all user relation information of the first user identity being removed, determining whether there is a user identity with the largest transmission capacity that has not yet appeared in both the initial seed user queue and the expanded user queue, and if yes, proceeding to step  2055 ; otherwise, proceeding to step  2054 . 
         [0070]    Step  2054 : checking whether the initial seed user queue is empty, and if yes, proceeding to step  2056  for ending the growth; otherwise, performing step  2055 . 
         [0071]    Step  2055 : adding the user identity to the end of the initial seed user queue, checking whether the expanded user queue reaches a specified size, and if yes, proceeding to step  2056  for ending the growth; otherwise, turning to step  2052 . 
         [0072]    Step  2056 : ending the growth of the expanded user queue, and saving the user identities of the expanded user queue as a user group list of the social network. 
         [0073]    Then, server  10  transmits the information to be sent to a client having the user identity recorded in the initial seed user queue. 
         [0074]    Client  20 , which has the user identity recorded in the initial seed user queue, receives the information to be sent, and transmits the information to clients having user identities included in the user group list. 
         [0075]    The third embodiment of the present invention provides a system for transmitting information based on social network having a structure as shown in  FIG. 4 , which includes: 
         [0076]    a calculation module  201 , adapted for calculating information transmission capacity of an obtained user identity according to user information corresponding to the obtained user identity; 
         [0077]    a writing module  202 , adapted for storing user identities of which transmission capacities are greater than a predetermined threshold into an initial seed user queue; and 
         [0078]    a transmitting module  203 , adapted for transmitting information to be sent to a client of which the user identity is stored in the initial seed user queue. 
         [0079]    Specifically, the calculation module  201  is adapted for: calculating information transmission capacity of an obtained user identity according to activity level information and user relation information corresponding to the obtained user identity. 
         [0080]    The system further includes: 
         [0081]    an expansion module  204 , adapted for expanding the initial seed user queue to get an expanded user queue including a predetermined number of user identities according to the user relation information corresponding to the user identities in the initial seed user queue; 
         [0082]    a dissemination module  205 , adapted for transmitting the information to be sent to a client with a user identity included in the expanded user queue via the client with the user identity included in the initial seed user queue. 
         [0083]    Further, the calculation module  201  is adapted for: calculating information transmission capacity of an obtained user identity according to online time of a user, and/or a frequency of interacting with friends, and/or a frequency of visiting friends&#39; spaces, and/or a frequency of updating a log space, and user relation information corresponding to the obtained user identity. 
         [0084]    Further, the calculation module  201  is adapted for calculating the activity level information corresponding to the user identity as follows: 
         [0000]    
       
         
           
             
               
                 A 
                  
                 
                     
                 
                  
                 
                   ( 
                   
                     user 
                      
                     
                         
                     
                      
                     ID 
                   
                   ) 
                 
               
               = 
               
                 
                   ∑ 
                   
                     n 
                     = 
                     1 
                   
                   N 
                 
                  
                 
                   
                     f 
                     n 
                   
                    
                   
                     x 
                     n 
                   
                 
               
             
             , 
           
         
       
     
         [0000]    wherein A (user ID) represents a quantified value of activity level information corresponding to a user identity. 
         [0085]    Here, N represents the total number of activity level information corresponding to a user identity, x n  represents activity level information corresponding to a user identity, f n  represents a coefficient of activity level information corresponding to a user identity wherein 
         [0000]    
       
         
           
             
               
                 ∑ 
                 
                   n 
                   = 
                   1 
                 
                 N 
               
                
               
                 f 
                 n 
               
             
             = 
             1. 
           
         
       
     
         [0086]    Also, the user relation information corresponding to the user identity is calculated by the calculation module  201  as follows: 
         [0000]    
       
         
           
             
               
                 R 
                  
                 
                     
                 
                  
                 
                   ( 
                   
                     user 
                      
                     
                         
                     
                      
                     ID 
                   
                   ) 
                 
               
               = 
               
                 
                   ∑ 
                   
                     j 
                     = 
                     1 
                   
                   M 
                 
                  
                 
                   r 
                   j 
                 
               
             
             , 
           
         
       
     
         [0000]    wherein M represents the total number of relation types included in user relation information of a user identity, R (user ID) represents a quantified value of user relation information corresponding to a user identity, r j  represents a quantified value of a relation type included in user relation information corresponding to a user identity. 
         [0087]    Also, the transmission capacity corresponding to the user identity is calculated by the calculation module  201  via evaluating a weighted sum of A (user ID) and R (user ID) as follows: T (user ID)=A (User ID)*f+R (User ID)*(1−f), wherein T (user ID) represents a transmission capacity corresponding to a user identity, and f is a weight factor. 
         [0088]    Further, the writing module  202  is further adapted for: adding another user identity into the initial seed user queue when it is determined that a relation chain formed by user relation information of two user identities having a transmission capacity larger than a predetermined threshold includes the another user identity not previously included in the initial seed user queue, wherein the another user identity does not belong to the selected user identities having a transmission capacity larger than a predetermined threshold. 
         [0089]    The calculation module is adapted for: obtaining an activity level component corresponding to activity level information of a user identity according to both the activity level information and a coefficient of the activity level information; 
         [0090]    calculating the sum of all activity level components corresponding to a user identity to get a quantified value of the activity level information corresponding to the user identity; 
         [0091]    obtaining a quantified value of user relation information of the user identity according to all user relation information corresponding to the user identity; and 
         [0092]    calculating a weighted sum of the quantified value of the activity level information corresponding to the user identity and the quantified value of the user relation information corresponding to the user identity to get the transmission capacity of the user identity. 
         [0093]    The writing module is further adapted for: storing user identities of which transmission capacities are smaller than a predetermined threshold into the initial seed user queue. 
         [0094]    Further, the expansion module  204  is further adapted for: removing user identities from an initial seed user queue in a descending order according to transmission capacities of the user identities; traversing all user relation information corresponding to the removed user identities; selecting a user identity having the largest transmission capacity and has not yet included in both the initial seed user queue and the expanded user queue, and adding the user identity into the initial seed user queue; and adding the removed user identities into the expanded user queue until the predetermined number of the user identities of the expanded user queue is arrived. 
         [0095]    The expansion module is further adapted for: removing user identities from an initial seed user queue, selecting a user identity according to all user relation information corresponding to the removed user identities and adding the user identity into the initial seed user queue, and adding the removed user identities into the expanded user queue. 
         [0096]    It is clear that those skilled in the art can make various modifications and variations on the present invention without departing from the spirit and scope of the present invention. Thus, if the modifications and variations of the present invention are within the scope of claims of the present invention and its equivalent technology, the present invention is also intended to include these modifications and variations.