Method and apparatus for replicating information

Abstract

The present invention provides the ability to use an existing store-and-forward massaging network such as an electronic mail system to replicate data between computer sites. The replication provided by the present invention can be useful with software applications, such as workgroup applications, to replicate data located on multiple sites. Workgroup replication data is sent to other sites via electronic mail (“e-mail”) messages. The present invention provides reliability features to handle errors in electronic mail transmissions. For example, the present invention provides the ability to reassemble objects at a replication site such that an object and all of its dependencies exist prior to the object's use at the site. Messages referred to as “ACK” messages are used to communicate a site's state and to provide other control information. Each site maintains latency information to determine transmission failures.

1 - 22 . (canceled)  
   
   
       23 . A method for replicating information, the method comprising: 
 maintaining, at a first computer site, a first collection of objects;    maintaining, at the first computer site, information about a second collection of objects, the second collection being maintained at a second computer site, and the second-collection information including information identifying at least one object from within the second collection and state information about the object identified from within the second collection;    receiving, at the first computer site using asynchronous communication via a messaging system, at least one message including object information about the object identified from within the second collection; and    using the received message as a basis for managing the first collection.    
   
   
       24 . The method of  claim 23  wherein the first collection comprises state information about at least one of the objects in the first collection.  
   
   
       25 . The method of  claim 23  further comprising maintaining, at the first computer site, information about the first collection including information identifying at least one object from within the first collection and state information about the object identified from within the first collection.  
   
   
       26 . The method of  claim 25  further comprising: 
 requesting an object from within the second collection in response to a determination that an object is to be sent from the second collection at the second computer site;    receiving the requested object from the second collection; and    updating the first collection of objects at the first computer site to include the requested object.    
   
   
       27 . The method of  claim 23  wherein state information comprises condition information about the object identified from within the second collection.  
   
   
       28 . The method of  claim 23  wherein using the received message to manage the first collection comprises updating the information about the second collection based on the received message.  
   
   
       29 . The method of  claim 23  further comprising: 
 determining whether to send a message to notify the second computer site about a state of an object included in the first collection at the first computer site; and    sending a message to notify the second computer site in response to a determination to send a message to notify the second computer site about a state of an object included in the first collection.    
   
   
       30 . The method of  claim 29  wherein sending a message to notify the second computer site comprises sending a message to the second computer site.  
   
   
       31 . The method of  claim 23  wherein receiving the message comprises receiving, at the first computer site using asynchronous communications via a messaging system, state information about at least one object in the second collection.  
   
   
       32 . The method of  claim 31  wherein using the received message as a basis for managing the first collection comprises updating state information in the information about the second collection based on the received message.  
   
   
       33 . The method of  claim 31  wherein: 
 the first collection comprises state information about at least one of the objects in the first collection, and    using the received message to manage the first collection comprises updating state information in the first collection based on the received message.    
   
   
       34 . The method of  claim 23  further comprising determining whether a dependency exists for an object in the second collection.  
   
   
       35 . The method of  claim 34  further comprising resolving a dependency for an object in the second collection based on a determination that the dependency exists for the object in the second collection.  
   
   
       36 . An apparatus for replicating information, the apparatus being configured to: 
 maintain, at a first computer site, a first collection of objects;    maintain, at the first computer site, information about a second collection of objects, the second collection being maintained at a second computer site, and the second-collection information including information identifying at least one object from within the second collection and state information about the object identified from within the second collection;    receive, at the first computer site using asynchronous communication via a messaging system, at least one message including object information about the object identified from within the second collection; and    use the received message as a basis for managing the first collection.    
   
   
       37 . The apparatus of  claim 36  wherein the first collection comprises state information about at least one of the objects in the first collection.  
   
   
       38 . The apparatus of  claim 36  further configured to maintain, at the first computer site, information about the first collection including information identifying at least one object from within the first collection and state information about the object identified from within the first collection.  
   
   
       39 . The apparatus of  claim 38  further configured to: 
 request an object from within the second collection in response to a determination that an object is to be sent from the second collection at the second computer site;    receive the requested object from the second collection; and    update the first collection of objects at the first computer site to include the requested object.    
   
   
       40 . The apparatus of  claim 36  wherein state information comprises condition information about the object identified from within the second collection.  
   
   
       41 . The apparatus of  claim 36  wherein using the received message to manage the first collection comprises updating the information about the second collection based on the received message.  
   
   
       42 . The apparatus of  claim 36  further configured to: 
 determine whether to send a message to notify the second computer site about a state of an object included in the first collection at the first computer site; and    send a message to notify the second computer site in response to a determination to send a message to notify the second computer site about a state of an object included in the first collection.    
   
   
       43 . The apparatus of  claim 36  wherein receiving the message comprises receiving, at the first computer site using asynchronous communications via a messaging system, state information about at least one object in the second collection.  
   
   
       44 . The apparatus of  claim 43  wherein using the received message as a basis for managing the first collection comprises updating state information in the information about the second collection based on the received message.  
   
   
       45 . The apparatus of  claim 43  wherein: 
 the first collection comprises state information about at least one of the objects in the first collection, and    the apparatus being further configured to update state information in the first collection based on the received message.    
   
   
       46 . The apparatus of  claim 36  further configured to determine whether a dependency exists for an object in the second collection.  
   
   
       47 . A system for replicating information, the system comprising: 
 means for maintaining, at a first computer site, a first collection of objects;    means for maintaining, at the first computer site, information about a second collection of objects, the second collection being maintained at a second computer site, and the second-collection information including information identifying at least one object from within the second collection and state information about the object identified from within the second collection;    means for receiving, at the first computer site using asynchronous communication via a messaging system, at least one message including object information about the object identified from within the second collection; and    means for using the received message as a basis for managing the first collection.