Online/Offline Applications

Microsoft® SQL Server™ 2000 replication offers a solution to the problem of data accessibility while traveling and at disconnected locations. Business users often need to use laptops or handheld computers when traveling and need a way to access data, often on demand, when using a modem to dial into corporate networks or connect to an intranet or the Internet.

Working online, using replication, mobile users can receive data from the central server (which would typically be the Publisher) when they connect to the corporate wide area network (WAN) or local area network (LAN), or over the Internet. They can then make changes to data immediately, or they can modify data offline and propagate those changes to the originating database and to other locations when they reconnect to the network.

Because data modifications made at Subscribers are performed asynchronously at the original server and then sent to other servers, transactional replication using the queued updating option, or merge replication are often the types of replication used for mobile or disconnected users.

Note When planning for an online/offline application that uses replication, plan for occasional maintenance in the deployment of the application and a way to transfer new datasets to the disconnected Subscribers.

Example

Northwind Traders has sales representatives in various regions who need to take current customer and order information with them and update it as they travel. The Northwind corporate office decides to publish data from the CUSTOMERS, ORDERS and ORDER DETAILS tables stored in a central online transactional processing (OLTP) database and filter the data based on the region where the sales representative works. The laptop or handheld computers used by the sales representatives will be the Subscribers to the data, and the sales representatives will be able to update the data as necessary when away from the office and offline.

Because the sales representatives make frequent data modifications and are often disconnected, Northwind administrators decide to use merge replication. When the sales representatives reconnect to the network, they can synchronize their data changes with changes made at other locations.

Online/Offline Applications

See Also