Abstract:
A data transaction system allows performing a transaction related to a data unit, where the data unit can be independently saved and retrieved, from an upper layer to a storage layer without causing a database deadlock related to the data unit in the storage layer. The data transaction system uses a first stage for transferring the data unit from the upper layer to the storage layer, and a second stage to save the transferred data unit independent of the upper layer. The data transaction system guarantees data consistency in applications using multiple layer architecture and at the same time avoiding cost and inefficiencies related to a database deadlock scenario.

Description:
TECHNICAL FIELD 
   This patent relates generally to computer software and more particularly to business application software using the Internet. 
   BACKGROUND 
   Computers and computer software make a very important part of modern life and business. Specifically, for any business organization to stay competitive, it is imperative that it uses various computer based software to manage data, customers, employees, etc. Businesses use a number of different software for virtually every function of their daily operations, including payroll, customer relation management, accounting, inventory management, etc. Each of these various software generally use one or more underlying database to store data and a number of graphical user interface (GUI) based forms to interact with the computer user. Depending on the business model, there may also be one or more intermediate layers operating between such database and the forms presented to the end user. This is especially true in the case of software using the Internet or other similar platform to provide applications. 
   For example, various accounting systems, customer relation management systems, human resource management systems, etc., operate as multilayer applications that run in network environment, allowing multiple users to access the system from multiple locations. These applications use a storage layer or a data layer to store data that may be accessed by the various locations over the network. For example, a database server or a collection of database servers may be used to store data used by such an application. Each of the various locations use an upper layer, such as a presentation layer or an interaction layer, to present the data from users or other application, to interact with users and other applications to receive, provide and change data, etc. 
   An example of such an upper layer may be an Internet browser, a spreadsheet application, an active server pages (ASP) application, etc., where such an upper layer may query data for one or more users, receive data from one or more users, and communicate data to the storage layer for storage. Quite often it is possible that one or more of the multiple users may need to transfer data to the storage layer at nearly the same time. In such a situation, it is imperative that the consistency of data passed to the storage layer is guaranteed. For example, for an accounting system using such multiple layer architecture, one user of the upper layer may be posting a transaction involving a bank account, while at the same time, another user may be querying the storage layer to get information related to the same bank account. Such an attempt by multiple users to access the bank account form the storage layer may cause a database deadlock, either denying access to both users, or in a worse case, communicating erroneous information to one or more of such multiple users. Therefore, these is a need to ensure that users interacting with multiple layer applications via an upper layer are able to initiate and commit transactions between such upper layer and the storage layer without causing database deadlock. 
   SUMMARY 
   A data transaction system allows performing a transaction related to a data unit, where the data unit can be independently saved and retrieved, from an upper layer to a storage layer without causing a database deadlock related to the data unit in the storage layer. The data transaction system uses a first stage for transferring the data unit from the upper layer to the storage layer, and a second stage to save the transferred data unit independent of the upper layer. The data transaction system guarantees data consistency in applications using multiple layer architecture and at the same time avoiding cost and inefficiencies related to a database deadlock scenario. 

   
     BRIEF DESCRIPTION OF DRAWINGS 
     The present patent is illustrated by way of examples and not limitations in the accompanying figures, in which like references indicate similar elements, and in which: 
       FIG. 1  is a block diagram of a network interconnecting a plurality of computing resources; 
       FIG. 2  is a block diagram of a computer that may be connected to the network of  FIG. 1 ; 
       FIG. 3  illustrates a block diagram of a two-stage transaction handling system; and 
       FIG. 4  illustrates a flowchart of a two-stage transaction handling program that may be used by the system of  FIG. 3 . 
   

   DESCRIPTION 
   Although the following text sets forth a detailed description of numerous different embodiments, it should be understood that the legal scope of the description is defined by the words of the claims set forth at the end of this patent. The detailed description is to be construed as exemplary only and does not describe every possible embodiment since describing every possible embodiment would be impractical, if not impossible. Numerous alternative embodiments could be implemented, using either current technology or technology developed after the filing date of this patent, which would still fall within the scope of the claims defining the invention. 
   It should also be understood that, unless a term is expressly defined in this patent using the sentence “As used herein, the term ‘______’ is hereby defined to mean . . . ” or a similar sentence, there is no intent to limit the meaning of that term, either expressly or by implication, beyond its plain or ordinary meaning, and such term should not be interpreted to be limited in scope based on any statement made in any section of this patent (other than the language of the claims). To the extent that any term recited in the claims at the end of this patent is referred to in this patent in a manner consistent with a single meaning, that is done for sake of clarity only so as to not confuse the reader, and it is not intended that such claim term by limited, by implication or otherwise, to that single meaning. Finally, unless a claim element is defined by reciting the word “means” and a function without the recital of any structure, it is not intended that the scope of any claim element be interpreted based on the application of 35 U.S.C. § 112, sixth paragraph. 
   Network 
     FIG. 1  illustrates a network  10  that may be used to implement an XML versioning system described herein. The network  10  may be the Internet, a virtual private network (VPN), or any other network that allows one or more computers, communication devices, databases, etc., to be communicatively connected to each other. The network  10  may be connected to a personal computer  12  and a computer terminal  14  via an Ethernet  16  and a router  18 , and a landline  20 . On the other hand, the network  10  may wirelessly connected to a laptop computer  22  and a personal data assistant  24  via a wireless communication station  26  and a wireless link  28 . Similarly, a server  30  may be connected to the network  10  using a communication link  32  and a mainframe  34  may be connected to the network  10  using another communication link  36 . As it will be described below in further detail, one or more components of the dynamic software provisioning system may be stored and operated on any of the various devices connected to the network  10 . 
   Computer 
     FIG. 2  illustrates a computing device in the form of a computer  110  that may be connected to the network  10  and used to implement one or more components of the dynamic software provisioning system. Components of the computer  110  may include, but are not limited to a processing unit  120 , a system memory  130 , and a system bus  121  that couples various system components including the system memory to the processing unit  120 . The system bus  121  may be any of several types of bus structures including a memory bus or memory controller, a peripheral bus, and a local bus using any of a variety of bus architectures. By way of example, and not limitation, such architectures include Industry Standard Architecture (ISA) bus, Micro Channel Architecture (MCA) bus, Enhanced ISA (EISA) bus, Video Electronics Standards Association (VESA) local bus, and Peripheral Component Interconnect (PCI) bus also known as Mezzanine bus. 
   Computer  110  typically includes a variety of computer readable media. Computer readable media can be any available media that can be accessed by computer  110  and includes both volatile and nonvolatile media, removable and non-removable media. By way of example, and not limitation, computer readable media may comprise computer storage media and communication media. Computer storage media includes volatile and nonvolatile, removable and non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules or other data. Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disks (DVD) or other optical disk storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to store the desired information and which can accessed by computer  110 . Communication media typically embodies computer readable instructions, data structures, program modules or other data in a modulated data signal such as a carrier wave or other transport mechanism and includes any information delivery media. The term “modulated data signal” means a signal that has one or more of its characteristics set or changed in such a manner as to encode information in the signal. By way of example, and not limitation, communication media includes wired media such as a wired network or direct-wired connection, and wireless media such as acoustic, radio frequency, infrared and other wireless media. Combinations of the any of the above should also be included within the scope of computer readable media. 
   The system memory  130  includes computer storage media in the form of volatile and/or nonvolatile memory such as read only memory (ROM)  131  and random access memory (RAM)  132 . A basic input/output system  133  (BIOS), containing the basic routines that help to transfer information between elements within computer  110 , such as during start-up, is typically stored in ROM  131 . RAM  132  typically contains data and/or program modules that are immediately accessible to and/or presently being operated on by processing unit  120 . By way of example, and not limitation,  FIG. 1  illustrates operating system  134 , application programs  135 , other program modules  136 , and program data  137 . 
   The computer  110  may also include other removable/non-removable, volatile/nonvolatile computer storage media. By way of example only,  FIG. 1  illustrates a hard disk drive  140  that reads from or writes to non-removable, nonvolatile magnetic media, a magnetic disk drive  151  that reads from or writes to a removable, nonvolatile magnetic disk  152 , and an optical disk drive  155  that reads from or writes to a removable, nonvolatile optical disk  156  such as a CD ROM or other optical media. Other removable/non-removable, volatile/nonvolatile computer storage media that can be used in the exemplary operating environment include, but are not limited to, magnetic tape cassettes, flash memory cards, digital versatile disks, digital video tape, solid state RAM, solid state ROM, and the like. The hard disk drive  141  is typically connected to the system bus  121  through a non-removable memory interface such as interface  140 , and magnetic disk drive  151  and optical disk drive  155  are typically connected to the system bus  121  by a removable memory interface, such as interface  150 . 
   The drives and their associated computer storage media discussed above and illustrated in  FIG. 1 , provide storage of computer readable instructions, data structures, program modules and other data for the computer  110 . In  FIG. 1 , for example, hard disk drive  141  is illustrated as storing operating system  144 , application programs  145 , other program modules  146 , and program data  147 . Note that these components can either be the same as or different from operating system  134 , application programs  135 , other program modules  136 , and program data  137 . Operating system  144 , application programs  145 , other program modules  146 , and program data  147  are given different numbers here to illustrate that, at a minimum, they are different copies. A user may enter commands and information into the computer  20  through input devices such as a keyboard  162  and pointing device  161 , commonly referred to as a mouse, trackball or touch pad. Other input devices (not shown) may include a microphone, joystick, game pad, satellite dish, scanner, or the like. These and other input devices are often connected to the processing unit  120  through a user input interface  160  that is coupled to the system bus, but may be connected by other interface and bus structures, such as a parallel port, game port or a universal serial bus (USB). A monitor  191  or other type of display device is also connected to the system bus  121  via an interface, such as a video interface  190 . In addition to the monitor, computers may also include other peripheral output devices such as speakers  197  and printer  196 , which may be connected through an output peripheral interface  190 . 
   The computer  110  may operate in a networked environment using logical connections to one or more remote computers, such as a remote computer  180 . The remote computer  180  may be a personal computer, a server, a router, a network PC, a peer device or other common network node, and typically includes many or all of the elements described above relative to the computer  110 , although only a memory storage device  181  has been illustrated in  FIG. 1 . The logical connections depicted in  FIG. 1  include a local area network (LAN)  171  and a wide area network (WAN)  173 , but may also include other networks. Such networking environments are commonplace in offices, enterprise-wide computer networks, intranets and the Internet. 
   When used in a LAN networking environment, the computer  110  is connected to the LAN  171  through a network interface or adapter  170 . When used in a WAN networking environment, the computer  110  typically includes a modem  172  or other means for establishing communications over the WAN  173 , such as the Internet. The modem  172 , which may be internal or external, may be connected to the system bus  121  via the user input interface  160 , or other appropriate mechanism. In a networked environment, program modules depicted relative to the computer  110 , or portions thereof, may be stored in the remote memory storage device. By way of example, and not limitation,  FIG. 1  illustrates remote application programs  185  as residing on memory device  181 . It will be appreciated that the network connections shown are exemplary and other means of establishing a communications link between the computers may be used. 
   Two-Stage Transaction Handling System 
     FIG. 3  illustrates a block diagram of a two-stage transaction handling system  200  that may be used to process a data transaction between an upper layer and a storage layer. The system  200  is illustrated as operating between an upper layer  202  and a storage layer  204 . The upper layer  202  and the storage layer  204  are communicatively connected with each other via a network  206  such as the network  10 , the Internet, etc. The upper layer may be any of the commercially used application layers, such as for example, the .Net® layer provided by the Microsoft corporation, whereas the storage layer  204  may be implemented using a database server. 
   The upper layer  202  may include an application  210  that may interact with a user via a graphical user interface (GUI) or with other applications running on the upper layer. The application  210  may receive data and/or requests from a user to retrieve data related to a data unit, to update data related to a data unit, etc., where such data unit may be stored on the storage layer  204 . 
   The data unit may be a master data unit that may represent a master data record that may be saved and retrieved independently, and that may have an independent function associated with it. An example of a master data unit for an accounting application may be a customer account record. Such a master data unit may have one or more child data associated with it. For example, the billing address of a customer is child data associated with the customer account record master data. Another example of master data unit for an accounting application is a sales invoice record, which may have a number of sales line items, each of which is a child data unit. 
   The system  200  may include a marking module  212  and an insert module  214  to handle such request from the application  210  to query, change, update, etc., operations to be performed on the data unit. Specifically the marking module may be used to mark a particular data unit before a specific operation on that specific data unit is transferred to the storage layer  204  as well as to mark that specific data unit after an acknowledgement is received from the storage layer. 
   The insert module  214  may include various procedures, such as a procedure to set various read only properties of the data unit based on current information received from the system  200 , the properties including a CreatedBy property, a UpdateBy property, etc. The functioning of the marking module  212  and the insert module  214  are further described below in  FIG. 4 . One of ordinary skill in the art would understand that each of the various modules  214 ,  216 , etc., may be implemented by software, hardware, firmware or as any combination thereof. 
   While in the system  200 , the upper layer  202  is illustrated to have only the modules  212  and  214  communicating with the application  210 , in an alternate implementation, other modules may also be used. For example, in am implementation, the upper layer  202  may also have a concurrency check module that is used to perform a concurrency check such as an optimistic concurrency check or a pessimistic concurrency check to guard from multiple users or applications accessing the same data unit record at the same time. 
   The storage layer  204  may include a database  216  having a plurality of data tables. The database  216  may be implemented using a database server having an SQL® database or any other database well-known to those of ordinary skill in the art. The database  216  may include a table for storing values related to various instances of the data unit. Thus the database  216  may have tables for each of the various child data related to a master data unit such as a customer account, etc. Normally, a number of applications may request values from these tables via a query or may request to set the values in this table by initiating data transactions with the database  216 . 
   In the two-stage transaction system  200  illustrated in  FIG. 3 , the storage layer may also include a validation module  218 , a transaction module  220  and a rollback module  222  that may interact with the database  216 . The validation module  218  may be used to perform a validation of input data to a table related to the data unit, to confirm that the input data is valid according to one or more business rules that may be stored in the validation module  218 . For example, if the input data to a customer account data unit includes a customer age of five years and if the validation module  218  includes a business rule that requires minimum customer age to be fifteen years, the validation module  218  may determine that the input data to the customer account table is invalid. 
   The transaction module  220  may be used to perform a data transaction with the database  216 . For example, the transaction module  218  may include various routines for updating a value in a table from the database  216 , where such a table is related to the data unit, etc. The rollback module  222  may be used to roll back a transaction performed on a table related to the data unit within the database  216 . The rollback module  222  may include a clean-up routine that may be used to clean up data input to a table in the database  216 , if necessary. One of ordinary skill in the art would understand that each of the various modules  218 ,  220 ,  222 , etc., may be implemented as software, as hardware or as any combination thereof. 
   Now referring to  FIG. 4 , a flowchart illustrates a two-stage transaction handling program  300  that may be used by the data transaction system  200 . The program  300  may be implemented on a distributed platform where various functions, denoted by the blocks of the flowchart in  FIG. 4 , are performed at different locations on a network, such as the network  10 . Moreover, various modules  212 - 222  of the data transaction system  200  may be used to perform different functions of the program  300 . It is possible that the program  300  is implemented by software, firmware, and hardware or by any combination thereof. For example, one of the function of the program  300  that is performed by the insert module  214  may be implemented in software while another function of the program  300  that is performed by the validation module  218  may be implemented in hardware, etc. 
   At a block  302  the system  200  receives a request in the upper layer  202  for a data transaction related to a data unit that is stored on the database  216 . Such request may be received from a client using a graphical user interface that provides access to data stored in the database  216 , or in any other related manner. An example of a request received by the program  200  supporting a distributed accounting system may be a request to update a sales invoice record. 
   Upon receiving such a request, at a block  304 , the marking module  212  marks up the sales invoice record in an upper layer data table. Specifically, the marking module  212  may mark up the sales invoice record as invalid. The sales invoice record may be a master data unit that can be saved and retrieved independently and it may have one or more business functions associated with it. Moreover, the sales invoice record may also have a plurality of child data associated with it, such as various lines of a sales invoice. The marking module may mark up only the sales invoice data unit as it may not be necessary to mark up the child data. 
   Subsequently at a block  306 , the insert module  214  inserts data into the upper layer data table related to the sales invoice record. For example, if a user has requested to set a sales tax field in the sales invoice record to be of first value, the insert module  214  will set the sales tax value in the upper layer data table related to the sales invoice record to be equal to first value. The user may insert various information related to other lines of the sales invoice record as well, in which case the insert module would insert various values as provided by the user into the upper layer table related to the sales invoice record. 
   After inserting various value, at a block  308 , the insert module  214  may initiate various post save procedures attached to the sales invoice record. Subsequently, at the block  310 , the data system  200  also initiates a database transaction by transferring the updated sales invoice record to the database  216 . 
   Once the storage layer  204  receives information regarding the initiation of the database transaction related to the sales invoice record, at a block  310 , the system  200  initiates a database transaction. 
   At a block  312 , the validation module  218  may perform a validation of input data to a table in the database  216  related to the sales invoice record. The validation module  218  may confirm that the input data is valid according to one or more business rules related to the sales invoice record. Such rules may be stored in the validation module  218 . 
   If the validation module  218  determines that the input data to be input to the table in the database  216  related to the sales invoice is valid, at a block  314 , the transaction module  220  may post the sales invoice. If it is necessary to merge some data related to the sales invoice record with any other database records, at a block  316 , the transaction module  220  may perform such merging operation. Once the various database tables related to the sales invoice record has been updated and merged, at a block  318 , the transaction module  220  commits the transaction of updating the sales invoice record. 
   If at the block  312 , the validation module  218  determines that the input data to be input to the table in the database  216  related to the sales invoice is not valid, at a block  322  the rollback module  222  may perform any data clean up necessary to bring the database table related to the sales invoice record back to the state it was before the database transaction was initiated at the block  310 . At a block  322 , the rollback module  222  may also roll back the database transaction performed at the block  310 . 
   Finally, at a block  320 , the marking module  212  updates the status of the upper layer data table related to the sales invoice record. The marking module  212  may receive a communication from the storage layer as to whether the database transaction was committed at the block  318  or whether it was rolled back at the block  324 . If the database transaction was committed at the block  318 , the marking module may change to the status of the upper layer data table related to the sales invoice record from invalid to valid. On the other hand, if the database transaction was rolled back at the block  324 , the marking module may restore the data of the upper layer data table related to the sales invoice record to its value prior to the insert operation performed at the block  306 . 
   Although the forgoing text sets forth a detailed description of numerous different embodiments of the invention, it should be understood that the scope of the invention is defined by the words of the claims set forth at the end of this patent. The detailed description is to be construed as exemplary only and does not describe every possible embodiment of the invention because describing every possible embodiment would be impractical, if not impossible. Numerous alternative embodiments could be implemented, using either current technology or technology developed after the filing date of this patent, which would still fall within the scope of the claims defining the invention. 
   Thus, many modifications and variations may be made in the techniques and structures described and illustrated herein without departing from the spirit and scope of the present invention. Accordingly, it should be understood that the methods and apparatus described herein are illustrative only and are not limiting upon the scope of the invention.