Transaction replication system and method for supporting replicated transaction-based services

In a computer network, an extinsible architecture for providing replicated services to end users of the network, the architecture comprising:

• a replication service that provides generic transaction replication services to other services of the network, the replication service running on at least one computer of the network and providing a software interface that enables the other services to use the generic transaction replication services;
• a first end-user service that provides a first content-based service to end users of the network, the first end-user service running on, and storing replicated copies of a first dataset on, a first plurality of servers that are interconnected by the network, the first end-user service configured to implement a client side of the software interface, and configured to use the replication service to replicate transactions among the first plurality of servers to maintain consistency between the replicated copies of the first dataset;
• and
• a second end-user that provides a second content-based service to end-users of the network, the second content-based service distinct from the first content-based service, the second end-user service running on, and storing replicated copies of a second dataset on, a second plurality of servers that are interconnected by the network, the second plurality of servers different from the first plurality of servers, the second end-user service configured to implement the client side of the software interface, and configured to use the replication service to replicate transactions among the second plurality of servers to maintain consistency between the replicated copies of the second dataset;
• wherein the replication service selectively takes individual servers of at least the first plurality of servers off-line when an inconsistency occurs between the replicated first datasets, the replication service thereby preventing end users from accessing inconsistent copies of the first dataset.

A computer-readable medium having strored thereon an executable service application that provides generic transaction replication services, the service application configured to run on a computer of a network in association with an end-user service in which service content data is replicated across a plurality of servers, the service application configured to communicate with, and to provide the generic transaction services to, the end-user service over the network via an application program interface (API) of the service application, the service application further configured to process update transactions received from the end-user service, and to dispatch the update transactions over the network to the plurality of servers for processing, the update transactions specifying updates to the service content data, wherein the service application responds to receipt of an update transaction from the end-user service by at least:

• (a) recording the update transaction within a transaction log on the computer;
• (b) dispatching the update transaction to each of the plurality of servers for processing;
• (c) monitoring the processing of the update transaction by each of the plurality of servers;
• and (d) Automatically taking at lest one server of the plurality of servers off-line when it is determined in step C that the at least one server has reached a transaction-processing outcome that is different from a final transaction-processing outcome reached by the plurality of servers.

A client-server type service that provides clients with read/write access to service content data, the service comprising:

• a group of locally-interconnected servers, each server of the group locally storing a respective copy of the service content data, the servers of the group configured to receive client requests over a network, the client requests including client update requests that specify modifications to the service content data;
• and
• a server application, the server application separately running on each server of the group and providing at least client access to the service content data, the server application configured to, on each respective server group:
• (a) receive the client update requests and generate update transactions therefrom,
• (b) forward the update transactions over the network to a transaction replication service for replication across the group, the transaction replication service separate from the client-server service and running on at least one computer that is not part of the group, and
• (c) receive and process update transactions dispatched to the group over the network by the transaction replication service, to modify a respective copy of the service content data,
• wherein the server application is further configured to, on each respective server of the group, return a transaction status code to the transaction replication service over the network, the transaction status code indicating, for the respective server, at least a success or failure of an update transaction;
• and
• Wherein the transaction replication service selectively takes at least one server of the group of servers off-line when it is determined that the at least one server was reached an outcome that is inconsistent with a final outcome reached by the group servers.

A transaction replication system for performing generic transaction replication services for groups of application servers, each application server of a group running a transaction-based service application that is adapted to use the transaction replication system to pass service-specific information between the servers of the group as transactions, the system comprising:

• a replication computer, the replication computer separate from and locally connected to the application servers of the group by a local area network and configured to receive transactions over the network from the application servers of the group, the replication computer configured to maintain a transaction log, the transaction log containing transactions previously received by the replication computer from individual application servers of the group;
• and
• a replication service application running on the replication computer to implement a generic transaction replication service, the transaction replication service configured to replicate received transactions by forwarding the received transactions to every application server of the group for processing;
• the transaction replication service further configured to, when a transaction is received by the replication computer from one of the applications servers of the group, do each of:
• (a) store the transaction in the transaction log;
• (b) forward the transaction to each application server of the group for immediate processing,
• (c) receive a status code from each application server of the group, the status code indicating, for each respective application server of the group, whether or not the transaction was successfully processed,
• (d) determine a final outcome of the transaction, and
• (e) take off-line an application server of the group which is inconsistent with the final outcome reached by the group.

A method of rapidly processing client update requests which specify updates to server data, replicated copies of the server data stored on respective servers of a group, the method comprising the steps of:

• (a) on at least one server of the group, doing each of:
• (a1) receiving client update requests and generating update transactions therefrom, the update transactions specifying updates to the server data,
• (a2) forwarding the update transactions over a network to a transaction replication service for replication across the group,
• (a3) responding to an update transaction received over the network from the transaction replication service by attempting to immediately process the update transaction, to update a replicated copy of the server data, without first generating a response message on the network, so the dispatched update transactions are completed in a single phase, and
• (a4) returning a status code to the transaction replication service to indicate a "success" or a "failure" of an update transaction processed in step (a3);
• and
• (b) at a computer running a replication service application that implements the transaction replication service, doing each of:
• (b1) receiving update transactions from the servers of the group,
• (b2) dispatching the update transactions received in step (b1) to the servers of the group,
• (b3) receiving status codes from the servers of the group and determining a final outcome of a corresponding transaction therefrom, and
• (b4) when a server of the group is inconsistent with the final outcome, automatically taking the inconsistent server off-line to remove the inconsistency.

In a computer network in which each server of a plurality of servers stores a respective copy of a dataset, a method of updating copies of the dataset stored by the plurality of servers, the method comprising the steps of:

• sending an update transaction over the network from a computer to the plurality of servers, the update transaction specifying an update to the dataset, the computer separate from the plurality of servers and running software that manages updates to the dataset;
• at each server of the plurality, responding to the update transaction by (i) attempting to perform the update, without generating message traffic on the network prior to said attempting, and (ii) after attempting to perform the update, returning a report message over the network to the computer, the report message indicating an outcome of the update transaction;
• and
• When the report messages returned by the plurality of servers indicate that an inconsistency exists between copies of the dataset, applying a voting protocol to selectively takes at least one server of the plurality of servers off-line to resolve the inconsistency.