Many modern business are information-centric - their database-powered applications are key company assets.  As competition mounts, your customers demand increased levels of database availability and security, including protection from downtime due to causes ranging from hardware failure to theft of a server.  They recognize that the database is often a single point of failure not only of the applications, but overall productivity as well.

Not long ago, database deployments fell under one of two distinct configurations - centralized databases on a large server accessed by all users, or individual database servers with limited views of the data.  While these uses served their purposes, both entailed certain limitations.  A central database is a single point of failure, and remote users with low bandwidth or sporadic connections challenge the configuration.  In decentralized structures, maintaining an up-to-date view of the company database for all users is an equal challenge.

Collectively, these trends point to new requirements on data availability; your customers require that mission-critical data must be where users need it when they need it.  And, it must be safe and secure at all times.

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Your Solution

Pervasive DataExchange, Pervasive's database replication solution, addresses these issues.  It reliably moves data between two or more Pervasive.SQL databases to maintain warm backup systems, drive data into reporting servers, or synchronize multiple remote databases.

The DataExchange technology works by capturing and sharing changes from one Pervasive.SQL database to other databases in a DataExchange replication network.  Each database is augmented with DataExchange, which adds two software components to a Pervasive.SQL database, the Replication Event Handler and the Replication Engine.

  • The Replication Event Handler (REH) plugs directly into the Pervasive.SQL database engine.  Specifically, the REH is a set of DLLs that operate within the database engine, so if the database is running, the replication event handler is running as well.  The database engine activates the REH when there is a change event (insert, update, delete).  The REH then makes note of the event in one of its private control tables.

  • The Replication Engine is a separate process that performs the actual replication task.  It reads the control tables to determine what records have changed since the last replication session.  It then groups these into packets and shares them with the other replication engines participating in the DataExchange network.  These other engines then apply the updates to their own databases.  The replication process occurs either continuously, or at scheduled intervals, or on demand.  The replication engine does not require constant network connectivity, so DataExchange is suitable for scenarios with intermittent connectivity, like remote users with dialup connections.

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Advanced DataExchange Capabilities

  • Replication normally occurs at the transactional (Btrieve) level, so data definition files (DDFs) are not required.

  • Packets are encrypted using a 128-bit key.  This enhances security by eliminating the possibility of unauthorized viewing of the database changes.

  • Conflicts are detected and resolved.  Conflicts occur when the same record in two databases is edited at the same time.  In most applications, data conflicts are rare or nonexistent.  In cases where data conflicts may occur, there are default and user-definable resolution rules.

  • Network topology is flexible.  While most DataExchange networks include only two databases replicating back and forth, multiple database scenarios and organizations are possible.  Supported topologies include ring, hub and spoke, peer to peer and hierarchical.

  • Fine-grained data segmentation is possible.  This includes vertical (particular columns are treated as a unit), horizontal (groups of records are treated as a unit) and referential (records from different tables that are linked by a referential integrity structure are treated as a unit).  This allows tight control over what set of database content is replicated where.

  • In addition, DataExchange includes a full suite of design, maintenance and monitoring tools.

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DataExchange in Action

Pervasive DataExchange is in use around the world, generating value for customers in different ways.  Read what they have to say:

  • Disaster recovery: DataExchange drives data from a production server to a warm backup at an offsite location.  Says Brian Swords, vice president , Corporate Trust, Bank of New York, "Pervasive's database replication technology and willingness to provide immediate support have been critical to our disaster recovery efforts following the World Trade Center tragedy".

  • Data sharing: DataExchange synchronizes multiple databases, giving a unified view of data across databases and geographies.  Says Jan Molenaar, ICT manager, Ubbink Garden, "We are so satisfied with the Pervasive DataExchange solution that we are planning to extend it to our other locations.  This will spread the benefits of our real-time data-sharing network throughout the entire company."

  • Data reporting: DataExchange loads the database of a reporting server or web site with fresh content from a production server.  Says Henry White. court IT director, Court System of Gwinnet County, Giorgia, "Pervasive's DataExchange will power the link between our justice information system and the Web portal, driving data to the portal and eliminating costly application development tasks."

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