Abstract:
Provider are a method, system, and program for maintaining data in a distributed computing environment. Data is stored at a primary storage site. A data structure is processed indicating an association of data sets in the stored data, secondary storage sites, and update frequencies. In response to processing the data structure, a determination is made of one of a plurality of secondary storage sites and a determination is made of at least one data set to transmit to the determined secondary storage site at an update frequency. The determined data set is transmitted to the determined secondary storage site according to the update frequency.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a method, system, and program for maintaining data in a distributed computing environment for processing transaction requests.  
           [0003]    2. Description of the Related Art  
           [0004]    In a common transaction model for Internet electronic commerce (e-commerce), a consumer retrieves Internet web pages (e.g., Hypertext Markup Language (HTML) pages, Extensible Markup Language (XML) pages, etc.) from a retailer&#39;s web site to select a product and then purchase the product online, typically using a credit card number. The consumer will retrieve one page, such as the product search and selection page, and select a product within the page displayed within a graphical user interface (GUI), such as an HTML browser, and then submit the page back to the retailer web site. The retailer web site will then transmit pages to the consumer&#39;s browser including fields where the consumer enters billing and credit card information, which is then submitted back to the retailer&#39;s web site to process the transaction. The retailer Web site will typically confirm completion of the transaction to the consumer&#39;s browser upon determining that there is sufficient inventory to fulfill the purchase and verifying the provided credit card number.  
           [0005]    One of the noticeable effects of the above e-commerce transaction model is the transmission or network delays that occur when the data is transmitted back-and-forth between the consumer browser and the retailer web site. Such delays increase as the distance between the retailer web site and consumer also increases. The consumer oftentimes experiences this delay by having to wait for a submitted page including user entered information to be received by the retailer web site and having to wait to receive the next page that is part of the transaction.  
           [0006]    For these reasons, there is a need in the art for improved techniques for enabling remote transactions over a network, such as commercial transactions.  
         SUMMARY OF THE PREFERRED EMBODIMENTS  
         [0007]    Provided are a method, system, and program for maintaining data in a distributed computing environment. Data is stored at a primary storage site. A data structure is processed indicating an association of data sets in the stored data, secondary storage sites, and update frequencies. In response to processing the data structure, a determination is made of one of a plurality of secondary storage sites and a determination is made of at least one data set to transmit to the determined secondary storage site at an update frequency. The determined data set is transmitted to the determined secondary storage site according to the update frequency.  
           [0008]    In further implementations, the data structure includes entries, wherein each entry indicates at least one data set to be transmitted to at least one secondary site at one update frequency.  
           [0009]    Still further, the data sets in the primary storage site transmitted to at least one of the secondary storage sites comprises product information used in an electronic commerce web site. Client requests for product information from the primary storage site are received and the client request for product information is redirected to one of the secondary storage sites. Product information is returned from the secondary storage site to which the client request is redirected to a client originating the client request.  
           [0010]    Further provided are a method, system, and program for processing a transaction. Transaction data is transmitted from one primary storage site to a plurality of secondary storage sites. A transaction request is received at one secondary storage site and processed to include transaction data from the secondary storage site that was transmitted from the primary storage site. The processed transaction request including transaction data is transmitted from the secondary storage site to the primary storage site to approve the transaction. The transaction request at the primary storage site is approved if the transaction data included in the received transaction request is consistent with the transaction data maintained at the primary storage site.  
           [0011]    In further implementations, the transaction request received at the secondary storage site comprises a request to access resources. A determination is made from the transaction data at the secondary storage site that was transmitted from the primary storage site as to whether the requested resource is available. A message indicating that the requested resource is not available is returned if the transaction data at the secondary storage site indicates that the requested resource is not available.  
           [0012]    Yet further, the transaction request received at the secondary storage site comprises a request to purchase a product. Determination is made from the transaction data at the secondary storage site that was transmitted from the primary storage site of pricing information for the requested product. A response to return to a client originating the transaction request indicating the pricing information for the requested product is generated at the secondary storage site. The generated response is transmitted to the client.  
           [0013]    The described implementations provide techniques for propagating data from a primary site to secondary storage sites so that transaction requests can be directed to the secondary storage site to handle. With the described implementations, the transaction requests are processed at the secondary storage site with data transmitted from the primary storage site. The processed transaction request is then submitted to the primary site to approve the transaction to ensure that the transaction data at the secondary storage site is consistent with that at the primary storage site. In this way, many of the transaction processing operations are performed at the secondary sites, which may be closer in geographical proximity to the clients initiating the transaction requests.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]    Referring now to the drawings in which like reference numbers represents corresponding parts throughout:  
         [0015]    [0015]FIG. 1 illustrates a distributed computing environment in which aspects of the invention are implemented;  
         [0016]    [0016]FIGS. 2 a  and  2   b  illustrate additional distributed computing environments in which further aspects of the invention are implemented;  
         [0017]    [0017]FIG. 3 illustrates a data structure for providing information on how to propagate data sets to secondary servers in accordance with implementations of the invention;  
         [0018]    [0018]FIGS. 4 and 5 illustrate logic to schedule data mirroring operations in accordance with implementations of the invention;  
         [0019]    [0019]FIG. 6 illustrates logic to process data requests in accordance with implementations of the invention; and  
         [0020]    [0020]FIGS. 7 and 8 illustrate logic to process a transaction request in accordance with implementations of the invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0021]    In the following description, reference is made to the accompanying drawings which form a part hereof, and which illustrate several embodiments of the present invention. It is understood that other embodiments may be utilized and structural and operational changes may be made without departing from the scope of the present invention.  
         [0022]    [0022]FIG. 1 illustrates a distributed computing environment in which aspects of the invention are implemented. A primary server  2  maintains a Hypertext Transfer Protocol (HTTP) server  4  to respond to HTTP requests from clients  6   a,    6   b  . . .  6   n  in geographical location A ( 8 ) and clients  10   a,    10   b  . . .  10   n  in geographical location B ( 12 ) over a network  14 . The primary server  2  further includes transaction code  5  to process transaction requests as described below. The clients  6   a,    6   b  . . .  6   n  and  10   a,    10   b  . . .  10   n  may include HTTP clients, such as Hypertext Markup Language (HTML) browsers (not shown) to transmit HTTP requests for information to the HTTP server  4 . The network  14  may comprise any type of network known in the art, such as a Wide Area Network, the Internet, an Intranet, a Local Area Network (LAN), etc. The geographical locations A ( 8 ) and B ( 12 ) may be separated by a significant geographical distance from geographical location C ( 16 ), which includes the primary server  2 . For instance, the location C ( 14 ) may be separated by a distance of thousands of miles from locations A ( 8 ) and B ( 12 ), or on separate continents, different states, etc.  
         [0023]    The primary server  2  is capable of accessing data from primary storage  18 , which includes database data  20 , such as database tables, and content  22 , such as textual information, multimedia content (e.g., audio files, movie files, images, etc.). The primary server  2  includes a data copy program  24  capable of propagating data from the primary storage  18  to secondary servers  30   a  and  30   b  at locations A ( 8 ) and B ( 12 ) to store in secondary storages  32   a  and  32   b,  respectively. The secondary servers  30   a  and  30   b  further include data copy programs  34   a  and  34   b,  respectively, to receive data from the primary server data copy program  24  and store received data in the secondary storages  32   a  and  32   b.  In certain implementations, the data copy program  24 ,  30   a,  and  30   b  may comprise the International Business Machines Corporation (IBM) Extended Remote Copy (XRC) or Peer-to-Peer Remote Copy (PPRC) products that ensure that updates to a primary location are applied to a secondary location in real time. Alternatively, the data copy programs  24   a,    30   a,  and  30   b  may comprise any program capable of replicating data and data updates at a primary location to mirror sites. Although two secondary sites at locations A ( 8 ) and B ( 12 ) are shown, additional sites, including additional secondary servers and storages, may be incorporated into the distributed computing environment of the described implementations.  
         [0024]    The secondary servers  30   a  and  30   b  further include HTTP servers  36   a  and  36   b,  respectively, to respond to HTTP requests from the clients  6   a,    6   b  . . .  6   n  and  10   a,    10   b  . . .  10   n.  The secondary servers also include transaction code  37   a  and  37   b  to process client requests in the manner described below. The secondary storages  32   a  and  32   b  include location specific database data  38   a  and  38   b  and location specific content  40   a  and  40   b.  The location specific data  38   a,    38   b,    40   a,  and  40   b  are subsets of the data  20  and  22  maintained in the primary storage  20  and  22 . For instance, the primary storage  18  includes database data  20  and content  22  for all geographical locations. The data routing map  42  provides information on how data in the primary storage database data  20  and content  22  maps to the location sites A ( 8 ) and B ( 12 ). The data copy program  24  would access the data routing map  42  to determine which secondary server site to send data so that location A specific data is sent to secondary server  30   a  and location B specific data is sent to secondary server  30   b.    
         [0025]    In certain implementations, the clients  6   a,    6   b  . . .  6   n  and  10   a,    10   b  . . .  10   n  would submit HTTP requests for data in the primary storage  18  to the primary server  2  over network  14 . The HTTP server  4  may then redirect requests from the clients  6   a,    6   b  . . .  6   n  and  10   a,    10   b  . . .  10   n  to the secondary server  30   a  and  30   b  at the location that is the situs of the originating client, i.e., requests from clients  6   a,    6   b  . . .  6   n  would be redirected to the secondary server  30   a  at location A ( 8 ) and requests from clients  10   a,    10   b  . . .  10   n  would be redirected to secondary server  30   b  at location B ( 12 ). In certain implementations, because the secondary storages  32   a  and  32   b  maintain location specific data, the secondary servers  30   a  and  30   b  can service requests from the clients  6   a,    6   b  . . .  6   n  and  10   a,    10   b  . . .  10   n  from location specific data.  
         [0026]    In certain of the implementations, a portion of the data in the secondary storages  32   a  and  32   b  may be common data maintained at all remote locations A and B, and other of the data at the remote sites may be specific to the particular location. For instance, in implementations where the primary server comprises a retailer e-commerce web site, the database  20  may maintain customer account information, such as address and payment information, and inventory information. The content  22  may maintain information on products and services provided by the retailer. The retailer would further maintain the secondary sites at the locations A and B to service client requests from the secondary storages systems within their geographic proximity. In this way, network related delays resulting from the processing of commercial communications between the clients  6   a,    6   b  . . .  6   n  and  10   a,    10   b  . . .  10   n  and the server processing the transaction are minimized because the distance of the network transaction is reduced. The content  40   a  and  40   b  may include the same data on the retailer products and services, and thus not differ between geographical sites. However, the location specific database data  38   a  and  38   b  may include information on only those clients  6   a,    6   b  . . .  6   n  and  10   a,    10   b  . . .  10   n  within the geographical location of the secondary server  30   a  and  30   b,  such that location A database data  38   a  would include customer information for clients  6   a,    6   b  . . .  6   n,  and not clients  10   a,    10   b  . . .  10   n,  and database data  38   b  would include customer information for clients  10   a,    10   b  . . .  10   n  and not clients  6   a,    6   b  . . .  6   n.    
         [0027]    In the implementation shown in FIG. 1, the clients  6   a,    6   b  . . .  6   n  and  10   a,    10   b  . . .  10   n,  secondary servers  30   a  and  30   b,  and primary server  2  communicate over a common network  14 , such as the Internet or any other network known in the art. FIGS. 2 a  and  2   b  illustrate an additional implementation where, as shown in FIG. 2 a,  the primary server  102  and secondary servers  130   a  and  130   b  communicate over a private network  114 , which may comprise any network limited to authorized members of the organization, i.e., employees etc. The private network  114 , may comprise a Wide Area Network (WAN), Storage Area Network (SAN), Intranet, Local Area Network (LAN), Virtual Private Network (VPN), etc. Separately, as shown in FIG. 2 b,  the clients  106   a,    106   b  . . .  106   n  and  110   a,    110   b  . . .  110   n,  primary server  102 , and secondary servers  130   a  and  130   b  may communicate over a separate network  116 , such as the Internet. In this way, the primary server  102  propagates data to the secondary servers  130   a  and  130   b  through a private network separate from the network the clients  106   a,    106   b  . . .  106   n  and  110   a,    110   b  . . .  110   n  use to access the data.  
         [0028]    Still further alternative distributed computing environments are possible. For instance, in certain implementations, a separate network may exist between the clients  106   a,    106   b  . . .  106   n  and  110   a,    110   b  . . .  10   n  and the secondary servers  130   a  and  103   b  in a particular geographical location, such as a Storage Area Network (SAN), Local Area Network (LAN), etc. Yet further, the clients may communicate with the secondary server within their geographical location through a common subnet of the Internet, such that each geographical location comprises a separate subnet. Any other network architecture or arrangement known in the art may also be used to connect the clients, primary server and secondary servers.  
         [0029]    As discussed, when propagating data to the remote secondary servers  30   a  and  30   b,  the primary server  2 , and data copy program  24  therein may use a data routing map  42 , or any other data structure, to determine how to route data to the secondary sites. FIG. 3 illustrates an example in one implementation of the information the data routing map  42  would maintain for each data set to be mirrored at a remote secondary site. The data routing map  42  maintains an entry  200  for each data set to be separately mirrored to one or more of the remote secondary servers  30   a  and  30   b.  Each entry  200  includes a data set information  202  indicating the data sets to be mirrored. The data set information  202  may indicate specific files, a directory, a database table, records in a database, etc. In certain instances, the data set information  202  may indicate a query, such that all data in the database data  20  and/or content  22  satisfying the query is part of the data set to mirror. For instance, the query may indicate a particular location, such that all database records having the location value, i.e., all customers within a particular geographic region, form a data set to mirror to a particular server  30   a,    30   b.    
         [0030]    Each entry  200  further indicates an update frequency  204  that specifies how frequently data from a particular data set  202  is mirrored to the remote site. For instance, critical data, such as payment and address information, inventory information, etc., may be immediately mirrored to the remote sites, such that any updates to such critical data are immediately copied to the remote site in real time. In this way, the secondary storages  32   a  and  32   b  maintain the most recent updates for such critical data. In certain implementations, the data copy program  24  may transfer updates to critical data immediately to the secondary servers  30   a  and  30   b  when such updates are applied to the primary storage  18 , such that the update does not complete until the secondary server  30   a  and  30   b  acknowledges receiving the update. However, less critical data may be updated at less frequent intervals, such as once a day, etc. For instance, the retailer product advertising and pricing information may be mirrored only once a day as such data does not frequently change. The target server information  206  indicates the one or more secondary servers  30   a,    30   b  to receive the data sets. For instance, data that is common among the geographical locations, such as certain advertising and pricing information, may be propagated to all secondary servers  30   a  and  30   b,  whereas geographical specific data may be propagated to the one or more servers within that specific region.  
         [0031]    [0031]FIG. 4 illustrates logic implemented in the data copy program  24  at the primary server  2  to propagate updated data to the secondary servers  30   a  and  30   b.  At block  250 , the data copy program  24  begins the process to schedule data mirroring operations. For each entry  200  (FIG. 3) in the data routing map  42  that does not require real-time updates, the data copy program  24  schedules (at block  252 ) a mirroring operation to occur at an interval equivalent to the specified update frequency  204  for the entry  200 . The scheduled mirroring operation would indicate the data set entries  200  to include in the mirroring operation and the target secondary site(s). At block  260 , the data copy program  24  processes a scheduled mirroring operation. A loop is performed at blocks  262  through  268  for each data set entry  200  specified for the scheduled mirroring operation. The data specified in the data set  202  for the entry  200 , which may comprise database data  20 , content  22  or data satisfying a query defined for the mirroring operation, is accessed (at bock  264 ) from primary storage  18  and sent (at block  266 ) to each secondary server  30   a,    30   b  specified in the target server information  206 .  
         [0032]    At block  270 , in response to receiving an update to data that is a member of a data set  202  specified in an entry  200  as having an high update frequency  204 , such as “real-time”, control proceeds to block  272  to determine the one or more secondary servers  30   a  and  30   b  specified in the target server information  206 . The updates are then sent (at block  274 ) to the determined secondary server(s) to apply to the attached secondary storage  32   a,    32   b.    
         [0033]    With the logic of FIG. 4, updated data to the primary storage  18  is propagated to the secondary storages according to an update frequency specified for the data. This allows updates to more critical data to be updated immediately at the secondary storage, whereas less critical data that does not change frequently may be updated with less frequency. Further, the data copy programs  34   a  and  34   b  at the secondary servers  30   a  and  30   b,  respectively, would send any updates to the data at the secondary storage  32   a,    32   b  to the primary server  2 . This allows the clients to update data at the secondary server to which they were redirected.  
         [0034]    In the logic of FIG. 4, the update frequency indicated a time interval at which to propagate non-critical data to the secondary servers  30   a  and  30   b.  In alternative implementations, the update frequency may comprise one or more threshold triggers other than a time interval. For instance, the update frequency may indicate a threshold percentage of non-critical data that has been modified, e.g., 10%, such that after modification of such threshold percentage of the non-critical data, the updated non-critical data is propagated to the secondary servers  30   a  and  30   b.  Still further, the update frequency criteria may also indicate a threshold count of the number of updates to non-critical data, such that upon reaching the threshold count value, the modified non-critical data is propagated to the secondary servers  30   a  and  30   b.  Alternative update frequency criteria may be applied in lieu of the time interval frequency described with respect to FIG. 4 or in addition to FIG. 4, such that the non-critical data is propagated to secondary sites upon the occurrence of one or more triggering events, e.g., expiration of a specified time interval, updating a threshold percentage of non-critical data, performing a threshold number of updates to non-critical data, etc. Different criteria may be maintained for different groups of the non-critical data, i.e., different data sets  202  indicated in different entries  200  (FIG. 3).  
         [0035]    [0035]FIG. 5 illustrates logic implemented in the data copy program  24  to propagate non-critical data when the update frequency  204  indicates a time interval, threshold percentage of updated non-critical data, and/or a threshold absolute number of updates to non-critical data. In the logic of FIG. 5, each of these checks are described as being considered together. However, in additional implementations, only one of these checks may be performed to determine when to propagate non-critical data, or any combination of the different checks may be used. Control begins at block  280  after propagating updates to non-critical data to the target server(s)  206 . In response, a timer is cleared (at block  282 ) that is used to determine when a time interval specified in the update frequency  204  (FIG. 3) has expired, an update percentage count is cleared (at block  284 ) indicating the percentage of non-critical data that has been updated, and an update count is cleared (at block  286 ) indicating the number of updates to non-critical data that have been performed. Upon the occurrence of any one of the above thresholds being satisfied at blocks  288 ,  290  or  292 , the updated non-critical data is then propagated (at block  294 ) to the one or more target servers  30   a  and  30   b  indicated in the target server field  206 .  
         [0036]    [0036]FIG. 6 illustrates logic implemented in the primary  2  and secondary  30   a,    30   b  servers to handle data requests from clients. Control begins at block  300  with the primary HTTP server  4  receiving a request for data from a client  6   a,    6   b  . . .  6   n,    10   a,    10   b  . . .  10   n  and determining (at block  302 ) a redirect secondary server  30   a,    30   b,  and redirecting the requesting client to that redirect secondary server. The HTTP server  4  may use any criteria known in the art for selecting a secondary server  30   a,    30   b  as the redirect server. In certain implementations, the HTTP server  4  may select the secondary server  30   a,    30   b  that is within the defined location of the client, e.g., client  6   a,    6   n  . . .  6   n  requests are redirected to secondary server  30   a.  Additionally, the HTTP server  4  may perform load balancing to redirect the request to the secondary server with the lowest current load, thereby minimizing server load delays. Still further, the HTTP server  4  may apply a combination of factors, or any other redirection selection factors known in the art.  
         [0037]    At block  310  in FIG. 6, one secondary server  30   a,    30   b  receives the redirected client request. FIG. 1 shows how client requests  50   a  and  50   b  are redirected at path  52   a  and  52   b  to one secondary server  30   a  and  30   b,  respectively. After redirection, the client may communicate directly with the secondary server  30   a  and  30   b,  as shown on paths  54   a  and  54   b.  If (at block  312 ) the requested data is not within the secondary storage  32   a,    32   b,  then the secondary server  30   a,    30   b  requests (at block  314 ) the requested data from the primary server  2  and stores the returned data in the secondary storage  32   a,    32   b.  From block  314  or the yes branch of block  312 , the requested data is returned (at block  316 ) to the client initiating the request.  
         [0038]    [0038]FIG. 7 illustrates logic implemented in the transaction code  37   a  and  37   b  in the secondary servers  30   a,    30   b  to process a redirected transaction request from a client  6   a,    6   n  . . .  6   n,    10   a,    10   b  . . .  10   n.  Control begins at block  320  upon the HTTP server  36   a,    36   b  in one secondary server  30   a,    30   b  receiving a redirected transaction request from the client, such as a request to purchase or procure goods or services. If (at block  322 ) the location database data  38   a,    38   b  indicates that the requesting client is not registered, then the transaction code  37   a,    37   b  transmits (at block  324 ) a registration page to the client  6   a,    6   b  . . .  6   n,    10   a,    10   b . . .    10   n  requesting the client to register. Upon receiving the returned client registration information, the transaction code  37   a,    37   b  updates (at block  326 ) the location database data  38   a,    38   b  with the new client registration information and then sends the new client registration information to the primary server  2 . The primary server  2  would then propagate the received client registration information to the other secondary servers so all remote sites maintain consistent information. The location database data  38   a,    38   b  may include different database tables, such as a customer registration table including information on a registered customer, such as address, billing, and credit card information, tables including information on product pricing and inventory. As discussed, the information in the location database data  38   a,    38   b  may be specific to the location, such as all customers within the defined location.  
         [0039]    If (at block  322 ) the requesting client is registered, then the transaction code  37   a,    37   b  generates (at block  328 ) a transaction object and assigns a unique identifier (ID) to the transaction. The transaction object may comprise a record in a database table providing information on a client transaction prior to finalization or some data structure maintaining information on a client initiated transaction. Additionally, in workflow processing environments, such as the IBM MQSeries** workflow environment, the transaction may comprise a piece of workflow that is processed at different nodes in a workflow management scheme. At block  330 , the transaction code  37   a,    37   b  receives selection of items for the transaction from the client, e.g., selected goods and services. If (at block  332 ) the location database data  38   a,    38   b  indicates that the selected items are not available, i.e., not in current inventory or unable to be provided, then the transaction code  37   a,    37   b  returns (at block  334 ) a message to the requesting client that the requested items are unavailable. At this time, the requesting client may be provided the option to backorder the items. If (at block  332 ) the requested items are available, then indication of the items are added (at block  336 ) to the transaction, i.e., transaction object or database record.  
         [0040]    The transaction code  37   a,    37   b  then accesses (at block  338 ) client customer information and accesses (at block  340 ) pricing information for the selected product from the location database data  38   a,    38   b  or content  40   a,    40   b  and then generates (at block  342 ) a transaction approval page for the client including the unique transaction ID, customer information, selected transaction items, cost of selected items, and a request for selection of a payment method. The transaction approval page is returned to the client  6   a,    6   b  . . .  6   n,    10   a,    10   b  . . .  10   n.  In alternative implementations, different types of information may be included in the pages transmitted to the application to accomplish the transaction.  
         [0041]    [0041]FIG. 8 illustrates logic implemented in the secondary and primary server transaction code  5 ,  37   a,    37   b  to process a client approval of a transaction. Control begins at block  350  with the secondary server transaction code  37   a,    37   b  receiving acceptance from a transaction approval form sent to a requesting client. The transaction code  37   a,    37   b  then begins (at block  352 ) a process to approve the transaction by verifying data from the location database data  38   a,    38   b  and obtain approval from the credit card issuer for the transaction. As mentioned, the processing may be implemented by a workflow model. If (at block  354 ) the transaction is not approved, then a disapproved message is returned to the client, perhaps stating the reason for the disapproval, e.g., failure of credit card authorization. If the transaction is approved, then the secondary server transaction code  37   a,    37   b  sends (at block  358 ) the transaction information to the primary server  2  to finally approve of the transaction.  
         [0042]    At block  360 , the primary server transaction code  5  receives the request to approve the transaction and transaction information from the secondary server  30   a,    30   b.  In response, the primary server transaction code  5  processes (at block  362 ) the primary database data  20  to verify the availability of the items included in the transaction and the customer information. In certain implementations, the payment or credit card approval may be performed at the primary server and not the secondary server as shown in FIG. 8. If (at block  364 ) all transaction information is consistent with the information maintained in the primary database data  20 , then the primary server transaction code  5  initiates (at block  366 ) a process to carry out the transaction, such as starting a workflow to execute the transaction, gather the transacted items, ship the items, and bill the customer&#39;s credit card. The primary server transaction code  5  returns (at block  368 ) approval to the secondary server  30   a,    30   b  submitting the approval request. In response to the received approval, the secondary server transaction code  37   a,    37   b  returns (at block  380 ) a page or message to the requesting client that the transaction was approved.  
         [0043]    If (at block  364 ) the primary server transaction code  5  determined that some of the received transaction information is not consistent with the data in the primary storage  18 , then the transaction code  5  would generate and transmit (at block  380 ) a message to the secondary server  30   a,    30   b  that the data was not verified and include the data from the primary site that is inconsistent with the data gathered from the secondary storage  32   a,    32   b.  In response to receiving the message, the secondary server transaction code  37   a,    37   b  would update (at block  382 ) the location database data  38   a,    38   b  and/or content  40   a,    40   b  with the data received from the primary server  2 . The transaction code  37   a,    37   b  would then generate and transmit (at block  384 ) a revised transaction approval page to the client  6   a,    6   b  . . .  6   n,    10   a,    10   b  . . .  10   n  including previous transaction data updated with new information from the primary storage  18  that was inconsistent with the data previously included in the transaction, for instance any price change information or customer billing or contact information, product information, etc. Control would then return to block  350  to await the client&#39;s acceptance of the revised transaction.  
         [0044]    With the described implementations, most of the parts of a transaction and most data verification and gathering occurs at a remote secondary server from data mirrored for that location in the secondary storage. Ths architecture improves response times to client requests by reducing the transmission distance of the requests because the client is redirected to communicate with a more geographically proximate server and by redistributing the load from the primary server to remote secondary servers. Moreover, in certain implementations, data is propagated to the secondary servers in a manner that provides the secondary sites with data in a timely manner and conserves network bandwidth. This is accomplished by propagating updates to critical data, such as customer information, payment information, inventory information, etc., at a high frequency, such as real time, and propagating updates to data that changes less frequently at greater intervals.  
         [0045]    Still further, with the described implementations, data and transaction consistency is maintained because final approval of the transaction is obtained from a primary storage site, which includes the most recent version of data and ensures that a transaction processed at a secondary site is not based on stale or inconsistent data.  
       Additional Implementation Details  
       [0046]    The described data mirroring and transaction techniques may be implemented as a method, apparatus or article of manufacture using standard programming and/or engineering techniques to produce software, firmware, hardware, or any combination thereof. The term “article of manufacture” as used herein refers to code or logic implemented in hardware logic (e.g., an integrated circuit chip, Programmable Gate Array (PGA), Application Specific Integrated Circuit (ASIC), etc.) or a computer readable medium (e.g., magnetic storage medium (e.g., hard disk drives, floppy disks,, tape, etc.), optical storage (CD-ROMs, optical disks, etc.), volatile and non-volatile memory devices (e.g., EEPROMs, ROMs, PROMs, RAMs, DRAMs, SRAMs, firmware, programmable logic, etc.). Code in the computer readable medium is accessed and executed by a processor. The code in which preferred embodiments are implemented may further be accessible through a transmission media or from a file server over a network. In such cases, the article of manufacture in which the code is implemented may comprise a transmission media, such as a network transmission line, wireless transmission media, signals propagating through space, radio waves, infrared signals, etc. Of course, those skilled in the art will recognize that many modifications may be made to this configuration without departing from the scope of the present invention, and that the article of manufacture may comprise any information bearing medium known in the art.  
         [0047]    The messages and information returned to the clients in response to transaction related requests may comprise pages, such as HTML or XML pages transmitted using the HTTP protocol or comprise e-mail messages or instant messaging messages.  
         [0048]    In the described implementations one instance of a primary server and primary storage is shown. In further implementations, the primary site may comprise multiple primary servers and primary storages. In certain implementations, two secondary storage sites are shown each including one secondary server and secondary storage. In further implementations, there may be more than two secondary storage sites at different geographical locations and each site may include multiple secondary servers and/or secondary storages.  
         [0049]    The preferred logic of FIGS.  4 - 8  described specific operations occurring in a particular order. Further, the steps may be performed in parallel as well as sequentially. In alternative embodiments, certain of the logic operations may be performed in a different order, modified or removed and still implement preferred embodiments of the present invention. Morever, steps may be added to the above described logic and still conform to the preferred embodiments. Yet further, steps may be performed by a single processing unit or by distributed processing units.  
         [0050]    In the described implementations, the transaction initiated by the client comprised a transaction to purchase goods or services from a commercial retailer e-commerce web site. In alternative implementations, the transactions processed in the manner described above may comprise any type of transaction requesting resources or interactions that a client would transmit across a network. Thus, the described implementations are not limited to commercial e-commerce type operations and may encompass any network transaction known in the art that is serviced from a server.  
         [0051]    In certain implementations, the distributed systems communicated across the networks using the HTTP protocol for transmitting documents between computers within a network. However, those skilled in the art will appreciate that any communication protocol may be used to transmit information in accordance with implementations of the invention.  
         [0052]    In certain implementations, the secondary servers transmitted pages of data to the clients in the HTML or XML file format. However, any document or data format known in the art may be used to transmit information between the systems.  
         [0053]    The foregoing description of the described implementations has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Many modifications and variations are possible in light of the above teaching. It is intended that the scope of the invention be limited not by this detailed description, but rather by the claims appended hereto. The above specification, examples and data provide a complete description of the manufacture and use of the composition of the invention. Since many embodiments of the invention can be made without departing from the spirit and scope of the invention, the invention resides in the claims hereinafter appended.