Distribution of a centralized database

A method in a data processing system for synchronizing database objects contained in a centralized database management system with copies of the database objects stored with clients that utilize the copies of the database objects, the synchronizing performed by a synchronizing agent, comprising the steps of:

• one of the clients sending a request for a writelock on a selected one of the database objects to the synchronizing agent, the client having a copy of the selected database object;
• the synchronizing agent receiving the writelock request and sending the writelock request to the centralized database management system, the synchronizing agent being detached from the centralized database management system;
• the centralized database management system granting the writelock request;
• the synchronizing agent accessing a directory structure containing indications of allocating clients that have allocated the selected database object and sending a callback message to each of the allocating clients requesting a response when the allocating client has completed use of the selected database object, the callback message indicating that the selected database object will become updated;
• the client modifying a portion of the selected database object and sending an indication to the synchronizing agent to update the centralized database management system;
• the synchronizing agent receiving the indication, waiting to receive the response from each allocating client, and sending the indication to the centralized database management system after receiving the response from each allocating client;
• and
• the centralized database management system receiving the indication and updating the selected database object.

A method in a data processing system for distributing copies of database objects contained in a centralized database to clients that utilize the copies of the database objects, the distribution performed by a distribution agent, comprising the steps of:

• under control of the distribution agent which is detached from the centralized database,
• receiving a request from a client for a writelock on a selected one of the database objects, the client having a copy of the selected database object;
• requesting the writelock from the centralized database wherein the centralized database grants the writelock;
• sending an indication that the writelock has been granted to the client wherein the client modifies the copy of the selected object;
• determining allocating clients that have a copy of the selected object;
• sending a notification to the allocating clients requesting a response when the allocating clients have completed use of the selected object, the notification indicating that the selected object will become updated;
• receiving a request from the client requesting that the centralized database be updated to reflect the modifications;
• waiting until receiving the response from each allocating client to ensure that each allocating client has completed use of the selected object;
• and
• updating the centralized database after receiving the response from each allocating client.

A method in a data processing system for distributing copies of database objects contained in a centralized database to clients that utilize the copies of the database objects, the distribution performed by a distribution agent, the method performed by one of the clients having a copy of a selected one of the database objects, comprising the steps of:

• sending a request for a writelock on the selected one of the database objects to the distribution agent which is detached from the centralized database such that the distribution agent determines allocating clients currently having a copy of the selected database object and requests a notification from each allocating client when the allocating client has completed use of the copy of the selected database object;
• receiving from the distribution agent an indication that the writelock has been granted;
• modifying the copy of the selected database object;
• and
• sending a request to the distribution agent to update the centralized database to reflect the modification made to the copy of the selected database object, wherein the distribution agent waits until receiving the notification from each of the allocating clients before updating the centralized database.

A method in a data processing system for synchronizing a database object contained in a centralized database with a copy of the database object stored with a client that performs transactions utilizing the copy of the database object, the synchronizing performed by a synchronizing agent, the method performed by the client comprising the steps of:

• receiving a callback message from the synchronizing agent indicating that the database object will be updated and the copy will become out of date, the synchronizing agent being detached from the centralized database;
• determining whether a transaction is in progress which utilizes the database object;
• when it is determined that the transaction is in progress which utilizes the database object,
• delaying a response to the callback message until the transaction has completed;
• and
• responding to the synchronizing agent indicating that the database object is no longer being used by the client when the transaction has completed;
• and
• when it is determined that the transaction is not in progress which utilizes the database object,
• responding to the synchronizing agent indicating that the database object is not being used by the client.

A method in a data processing system having a centralized database with database objects, having clients with copies of the database objects that utilize the copies of the database objects, and having a synchronizing agent, comprising the steps of:

• under control of the synchronizing agent which is detached from the centralized database,
• distributing a copy of one of the database objects to one of the clients;
• and
• synchronizing the copy of the database object with the centralized database such that the client is notified when the copy of the database object will become out of date.

A data processing system, comprising:

• a client computer, further comprising:
• a memory containing a copy of a selected database object and containing a client that requests that a writelock be placed on the selected database object, that modifies the selected database object after the writelock has been granted, and that generates an update indication to request update of the selected database object;
• and
• a processor for running the client;
• and
• a server computer, further comprising:
• a secondary storage device containing a database with database objects including the selected database object;
• a memory containing
• a directory structure with indications of allocating clients that have allocated the selected database object for access;
• a database management system for managing the database and for granting writelocks on the database objects;
• and
• a distribution agent detached from the database management system that receives the writelock request from the client, that obtains a writelock from the database management system for the selected database object, that accesses the directory structure to determine the allocating clients, that sends each allocating client a message requesting a response when the allocating client has completed use of the selected database object, that receives the update indication from the client, that waits until receiving the response from each allocating client, and that sends the update indication to the database management system after receiving the response from each allocating client;
• and
• a processor for running the database management system and the distribution agent.

A data processing system, comprising:

• a secondary storage device having a database with database objects;
• and
• a memory containing:
• a database management system that manages the database;
• a client for maintaining a copy of one of the database objects until being notified that the copy is no longer valid;
• a synchronization agent detached from the database management system that determines when the database object is to be updated and that notifies the client when the database object is to be updated and will no longer be a valid representation of the database object;
• and
• a processor for running the database management system, the client, and the synchronization agent.

A computer-readable medium containing instructions for controlling a data processing system to distribute copies of database objects contained in a centralized database to clients that utilize the copies of the database objects, the distribution performed by a distribution agent performing the steps of:

• under control of the distribution agent which is detached from the centralized database,
• receiving a request from a client for a writelock on a selected one of the database objects, the client having a copy of the selected database object;
• requesting the writelock from the centralized database wherein the centralized database grants the writelock;
• sending an indication that the writelock has been granted to the client wherein the client modifies the copy of the selected object;
• determining allocating clients that have a copy of the selected object;
• sending a notification to the allocating clients requesting a response when the allocating clients have completed use of the selected object, the notification indicating that the selected object will become updated;
• receiving a request from the client requesting that the centralized database be updated to reflect the modifications;
• waiting until receiving the response from each allocating client to ensure that each allocating client has completed use of the selected object;
• and
• updating the centralized database after receiving the response from each allocating client.

A computer-readable medium containing instructions for controlling a data processing system to perform a method for distributing copies of database objects contained in a centralized database to clients that utilize the copies of the database objects, the distribution performed by a distribution agent, the method performed by one of the clients having a copy of a selected one of the database objects, the method comprising the steps of:

• sending a request for a writelock on the selected one of the database objects to the distribution agent which is detached from the centralized database such that the distribution agent determines allocating clients currently having a copy of the selected database object and requests a notification from each allocating client when the allocating client has completed use of the copy of the selected database object;
• receiving from the distribution agent an indication that the writelock has been granted;
• modifying the copy of the selected database object;
• and
• sending a request to the distribution agent to update the centralized database to reflect the modification made to the copy of the selected database object, wherein the distribution agent waits until receiving the notification from each of the allocating clients before updating the centralized database.

A computer-readable medium containing instructions for controlling a data processing system to perform a method for synchronizing a database object contained in a centralized database with a copy of the database object stored with a client that performs transactions utilizing the copy of the database object, the synchronizing performed by a synchronizing agent, the method performed by the client by performing the steps of:

• receiving a callback message from the synchronizing agent indicating that the database object will be updated and the copy will become out of date, the synchronizing agent being detached from the centralized database;
• determining whether a transaction is in progress which utilizes the database object;
• when it is determined that the transaction is in progress which utilizes the database object,
• delaying a response to the callback message until the transaction has completed;
• and
• responding to the synchronizing agent indicating that the database object is no longer being used by the client when the transaction has completed;
• and
• when it is determined that the transaction is not in progress which utilizes the database object,
• responding to the synchronizing agent indicating that the database object is not being used by the client.

A computer-readable medium containing instructions for controlling a data processing system to perform a method, the data processing system having a centralized database with database objects, having clients with copies of the database objects that utilize the copies of the database objects, and having a synchronizing agent, the method comprising the steps of:

• under control of the synchronizing agent which is detached from the centralized database,
• distributing a copy of one of the database objects to one of the clients;
• and
• synchronizing the copy of the database object with the centralized database such that the client is notified when the copy of the database object will become out of date.

A method in a data processing system for distributing copies of database objects contained in a centralized database to clients that utilize the copies of the database objects, the distribution performed by a distribution agent, comprising the steps of:

• under control of the distribution agent which is detached from the centralized database,
• receiving an update request from a client to modify a selected one of the database objects;
• passing the update request to the centralized database wherein the centralized database indicates that the update request will be successfully processed,
• determining allocating clients that have a copy of the selected object;
• sending a notification to the allocating clients requesting a response when the allocating clients have completed use of the selected object, the notification indicating that the selected object will become updated;
• receiving a commit request from the client requesting that the centralized database be updated to reflect the modifications requested by the update request;
• waiting until receiving the response from each allocating client to ensure that each allocating client has completed use of the selected object;
• and
• updating the centralized database after receiving the response from each allocating client.

A computer-readable medium containing instructions for controlling a data processing system to perform a method for distributing copies of database objects contained in a centralized database to clients that utilize the copies of the database objects, the distribution performed by a distribution agent, the method comprising the steps of:

• under control of the distribution agent which is detached from the centralized database,
• receiving an update request from a client to modify a selected one of the database objects;
• passing the update request to the centralized database wherein the centralized database indicates that the update request will be successfully processed,
• determining allocating clients that have a copy of the selected object;
• sending a notification to the allocating clients requesting a response when the allocating clients have completed use of the selected object, the notification indicating that the selected object will become updated;
• receiving a commit request from the client requesting that the centralized database be updated to reflect the modifications requested by the update request;
• waiting until receiving the response from each allocating client to ensure that each allocating client has completed use of the selected object;
• and
• updating the centralized database after receiving the response from each allocating client.