Data processing: database and file management or data structures – Database design – Data structure types
Reexamination Certificate
2000-04-28
2003-09-23
Mizrahi, Diane (Department: 2175)
Data processing: database and file management or data structures
Database design
Data structure types
C707S793000, C707S793000
Reexamination Certificate
active
06625602
ABSTRACT:
TECHNICAL FIELD
The present invention relates to the field of workflow transaction processing in computer systems. More particularly, the invention relates to hierarchical transactions and compensation in computer systems.
BACKGROUND OF THE INVENTION
Workflow applications are related to businesses, governments, and other organizations where information and work product flows between various persons or departments. Workflow generally is the flow of information and control in such organizations. In a business setting, workflow processes include sales and order processing, purchasing tasks, inventory control and management, manufacturing and production control, shipping and receiving, accounts payable, and the like. Businesses continually strive to define, document, and streamline such processes in order to effectively compete.
Computer systems and associated software now provide tools with which businesses and other organizations can improve workflow. Software tools may be used to model business workflow processes or schedules and identify inefficiencies and possible improvements. In addition, where a process involves exchanging data between people, departments, plants, or even between separate companies, computer systems and networks can be used to implement such exchanges. These systems and software tools are further able to implement large-scale computations and other data or information processing which typically are associated with business related information. Automation of such information processing has led to many efficiency improvements in the modern business world; and workflow management includes effective management of information flow and control in an organization's business processes. Automation of workflow management is now allowing businesses and other organizations to further improve performance by executing workflow transactions in computer systems, including global computer networks, such as the Internet.
Many applications for workflow tools are internal to a business or organization. With the advent of networked computers having modems or other type communications links, computer systems at remote locations can now communicate easily with one another. Such enhanced communication allow computer system workflow applications to be used between remote facilities within a company. An example includes forwarding a customer order from a corporate headquarters to a remote field sales office for verification by an appropriate sales person, and returning a verification to the headquarters. Workflow applications also can be of particular utility in processing business transactions between different companies. In a typical application, two companies having a buyer-seller relationship may desire to automate generation and processing of purchase orders, product shipments, billing, and collections. Automating such processes can result in significant efficiency improvements which are not otherwise possible. However, this inter-company application of workflow technology requires co-operation of the companies and proper interfacing of the individual company's existing computer systems.
Thus far, workflow application tools have been developed which provide some capability for automating business workflow by defining workflow applications. Many business transactions are of a short duration. For example, a buyer may wish to transmit a purchase order number along with a list of products being purchased to a seller, and the seller may wish to respond with a confirmation of the order and an expected shipment date. This type of transaction may involve a general consumer purchasing products from a retailer, or alternatively two large corporate entities which do business regularly. The data associated with the order and the confirmation may be relatively small and the transmission time for the data may be on the order of fractions of a second. A workflow application running in a computer system may allocate system resources to the transaction during its pendency, which is generally very short—i.e. has a small latency. In this scenario, the system would use a conventional database transaction, i.e. an ACID transaction. An ACID transaction locks database information for the duration of the transaction. However, there are other types of business workflow transactions which have significantly longer durations and which may occupy system resources for an unacceptably long time. Such transactions often are called long running transactions.
Examples of long running transactions may include manufacturing or production control systems wherein a product is manufactured according to a particular workflow. It is common for a product to be manufactured in separate subassemblies, possibly at remote facilities. In such a situation, the time between production initiation and completion may be days, weeks or even months. A workflow application which tracks or manages progress of such workflow may be resident in a computer system for a very long time. Moreover, the application may wait several weeks for the product to reach an intermediate assembly stage, perform some bookkeeping function which lasts for several seconds, and then remain waiting again for several days for the next production stage. Such long running transactions may occupy system resources for unacceptable periods of time, while performing a relatively small amount of work. Consequently, there remains a need for workflow application tools which can execute long running transactions in a computer system, while utilizing system resources judiciously.
System resources in this regard, may include allocated space in memory for executable code and associated data, as well as permissive access to databases. In order to maintain data coherency, access to certain elements of data may be restricted to (exclusively allocated to), a specific instance of a workflow transaction until the transaction completes, (e.g., aborts or commits). Access to these data elements is denied to other transactions or objects while the transaction of interest is active. Once a running transaction successfully completes, or commits, the data is unlocked (e.g. becomes available for access by other transactions or programs). On the other hand, if the transaction fails or aborts, a transaction log is consulted and data manipulations performed by the aborted transaction are undone, (e.g., rolled back).
Heretofore, transaction commit rules and roll-back methods have been provided in order to ensure ACID properties of transactions. Transactions have conventionally been thought of as collections or groupings of operations on physical and abstract application states. ACID properties include atomicity, consistency, isolation, and durability.
Atomicity refers to a transaction's change to a state of an overall system happening all at once or not at all. Consistency refers to a transaction being a correct transformation of the system state, and essentially means that the transaction is a correct program. Although transactions execute concurrently, isolation ensures that transactions appear to execute before or after another transaction, because intermediate states of transactions are not visible to other transactions until the transaction commits (e.g., the data is locked during execution). Durability refers to once a transaction completes successfully (commits), its activities or its changes to the state become permanent and survive failures.
In conventional transaction processing systems and methods, an application program starts a new transaction, and thereafter, the operations performed by the program are part of the transaction until the transaction commits or aborts, including all operations performed by other programs on behalf of the transaction. If no failures occur, the program informs the outside world that the transaction is a complete and correct transformation by committing. Otherwise, the transaction aborts and data manipulations, messages, etc. are undone by roll-back procedures. To an outsider, the transaction appears to be atomic, because the tra
Andrews Anthony
Beckman Brian
Levy Marc
Mehta Bimal
Meredith Lucius Gregory
Amin & Turocy LLP
Microsoft Corporation
Mizrahi Diane
Spiegel Michael
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