Replication is not a one-size-fits-all solution. Businesses have different application requirements, and SQL Server 7.0 delivers a broad range of replication solutions to meet them. Envision a spectrum of application requirements with site autonomy (all sites operating in a disconnected state) at one end, and transactional consistency (all sites are guaranteed to have the same data values at the same time) at the opposite end.
An application's position along the range of requirements determines the appropriate replication solution. For example, contrast the requirements of a sales force automation system with those of an accounts receivable system. Both applications use replication for distributing data. However, the company's mobile sales force can take customer orders on laptop computers while disconnected from the central office network. The lack of a network connection (and an accurate report of inventory) must not prevent the salesperson from taking and submitting the order. Thus, the need for autonomy in the sales application outweighs the risk of taking orders for out-of-stock items (back orders are allowed). In contrast, the invoices sent out by the accounts receivable department must be completely accurate and current for auditing purposes. In this case, transactional consistency outweighs the need for employee autonomy.
SQL Server provides three types of replication you can use as you design your applications:
Each of these types provides different capabilities and different attributes to satisfy the needs for site autonomy and transaction consistency. However, these are not mutually exclusive technologies. It is common for the same application to use multiple replication types.