Abstract: A system and method for incremental change synchronization among multiple copies of data is disclosed. To achieve the synchronization a genera synchronization model is used. The synchronization model establishes a one-way data flow path to allow incremental changes to be transferred from a copy of data that incorporates the incremental changes to a copy of data that does not yet incorporate the incremental changes. To achieve this one-way data flow path, the synchronization model uses an agent, a data collector, and a data synchronizer. The data collector collects incremental changes transferred to it and applies the incremental changes to a copy of data. A data synchronizer transfers incremental changes to a data collector. An agent controls the synchronization process by making a connection between a data collector and a data synchronizer and then directing the data synchronizer to transfer data to the data collector.

Abstract: In one aspect, the disclosed technique detects common leading byte patterns in the integers so that these patterns need only be stored once in the encoded byte stream. Those integers that share a common leading byte pattern are stored in truncated form, without their common leading bytes. These truncated integers may themselves be further examined to determine if any of them share additional common leading bytes beyond those already detected. Thus, the technique lends itself naturally to description using the language of trees. Integers with a common leading byte pattern are stored as child nodes, their parent being the node containing the common byte pattern. Child nodes consist only of those bytes remaining after the initial byte pattern has been extracted; the greater the number of children, the greater are the efficiency gains. All the children of a given tree or subtree are similarly examined for common leading byte patterns, ignoring those bytes that are already accounted for in their ancestor nodes.

Abstract: A messaging system user's mailbox is moved using a method in which the mailbox is flagged as being moved and a message arriving for the user during the move is delivered to a holding area to await re-delivery to the mailbox after the move is completed. A combination of non-volatile memory and volatile memory is used to ensure the message's delivery in the event of a power loss or other system failure.

Abstract: A variety of processes, e.g., electronic mail, word processing, database applications, etc., reside on a system, e.g., an operating system. Independent levels of security are maintained for the different processes without requiring the user to pass a security test to gain access to each process. The system includes a directory of system identifiers assigned to users. Each process includes a directory of process-specific identifiers for users of that process. The system identifiers and process identifiers are associated in a predetermined manner. Therefore, a user may gain access to a process only when the user's system identifier is associated with the desired process-specific identifier.

Abstract: A technique for generating a unique record index for a collection of data records. A parent index is generated and attached to a parent data record, and serves as the record index. When a child data record is generated, a child index is generated and is appended to its parent index, and the combination is the record index for that child data record. The record index allows a collection of data records to be sorted and displayed efficiently according to their logical position in a collection. The technique finds application in an electronic mail messaging system, wherein a conversation index is generated for each electronic message.

Abstract: In a one aspect, a technique for tracking the status of records in replicated databases. Sets of identifiers (e.g., record identifiers or change numbers) are stored by individual replicas, and in some cases conveyed between replicas. The sets comprise lists of intervals, with each interval being either a single number (in the case of the interval containing only one identifier) or a pair of numbers representing the low and high bounds of the interval. Stored as lists of intervals, the sets can usually be efficiently compressed for compact storage or transmission. The technique is particularly useful for tracking the status of message records in distributed messaging systems. It is also particularly useful in "push" replication schemes as the status information represented by the sets of identifiers can be replicated simply by each replica sending its set of identifiers to other replicas.

Abstract: Information items commonly have a unique portion and a common portion that is the same for multiple items. The common portions of information items are stored once. Each common portion is assigned a globally unique single-instance identifier. Each unique portion of an information item stores the single-instance identifier of the associated common portion. A reference count, stored with the common portion, reflects the number of unique portions associated with the common portion. When an information item is created or distributed, the single-instance identifier of the common portion is used to ensure that multiple copies of the common portion are not stored.

Abstract: Deleted database records are identified not by the use of tombstones (pairs of record IDs and change numbers) but by storing for each database replica a set of deleted record IDs without associated change numbers (DRID data). The DRID data can include not only IDs of deleted records but also IDs that were never assigned to the database by the server (e.g., IDs assigned to records of other databases). The DRID data can be compactly stored as a list of intervals, with each interval describing a range of IDs across which records have either been deleted or never assigned to the database. Replication is accomplished by periodically sending the DRID data, or incremental versions thereof, to other replicas, which delete records identified by the received DRID data, and update their existing DRID data by combining it with received DRID data.

Abstract: In an electronic mail system comprising a local computer that can be connected to a message server over a data link, mechanisms are provided to convert large identification codes used by the message server to store and access messages and folders into shorter identification codes used by the local computer to access locally stored copies of the messages or folders. The large server identification codes, including a 46-byte folder codes and 70-byte message codes, are converted using a conversion technique that operates in one of two modes, depending on whether the data link to a master conversion map on the message server is available and operative. In the first mode, to convert the codes to 8-byte codes, the technique uses a local cache that retains mapping information produced in conversions using the master conversion map. In the second mode, three types of local maps are implemented as B-trees are used to convert the codes first to the 8-byte codes and then to 4-byte codes.

Abstract: Systems and methods of time based data expiration in a replication environment are presented. The systems and methods of the present invention allow different age limits to be set on each individual server in a network. A network can therefore be configured with some servers having no age limit and other servers having a wide range of differing age limits. Systems and methods for handling mixed data sets that include some data objects which are allowed to expire and some data objects which do not expire are also presented. In all cases, the time based data expiration systems and methods are designed to insure proper operation of the replication process and any associated data recovery process. Specifically, expired data will not be recovered via any data recovery mechanism and servers will not attempt to recover missing data from a server that has expired that data.

Abstract: A system and method for replica administration without data loss is disclosed. In a replication environment where data is replicated around a network and where any system can make changes to the data, data loss may occur if one copy of the data is deleted before changes made to that copy are replicated to other systems in the network. The present invention describes a robust administration environment which prevents inadvertent data loss by verifying that changes made to a local copy of the data reside on at least one other system in the network. The system and method of the present invention also provide a mechanism to allow an administrator to bypass such safeguards in appropriate circumstances in order to handle special cases such as total removal of the data from the network. The replica administration environment is implemented by defining various states that represent the level of participation in the replication of the data.

Abstract: A single processor/storage device provides multilingual support for a computer system. Information is divided into two parts. The first part is initially stored in a first character set, e.g., the character set in which it was created. A tag, identifying the character set, is associated with the first part. The second part is stored in a universal character set. The first part is converted to another character set only when requested. Indices may be generated from the second part using specified language sorting rules.