Data Replication with SQL Remote
PART 1. Introduction to SQL Remote
CHAPTER 2. SQL Remote Replication Concepts
While SQL Remote can provide replication services in many different environments, its features are designed with the following characteristics in mind:
SQL Remote should be a solution even when no administration load can be assigned to the remote databases, as in mobile workforce applications.
Data communication among the sites may be occasional and indirect: it need not be permanent and direct.
Memory and resource requirements at remote sites are assumed to be at a premium.
The following examples show some typical SQL Remote setups.
Server-to-laptop replication for mobile workforcesSQL Remote provides two-way replication between a database on an office network and personal databases on the laptop computers of sales representatives. Such a setup may use an e-mail system as a message transport.
The office server may be running a server to manage the company database. The Message Agent at the company database runs as a client application for that server.
The laptop computers may be running Windows 95 or Windows NT, and each sales representative has an Adaptive Server Anywhere personal server to manage their own data.
While away from the office, a sales representative can make a single phone call from their laptop to carry out the following functions:
Collect new e-mail.
Send any e-mail messages they have written.
Collect publication updates from the office server.
Submit any local updates, such as new orders, to the office server.
The updates may include, for example, new specials on the products the sales representative handles, or new pricing and inventory information. These are read by the Message Agent on the laptop and applied to the sales rep's database automatically, without requiring any additional action on the sales representative's part.
The new orders recorded by the sales representative are also automatically submitted to the office without any extra action on the part of the sales representative.
Server-to-server replication among officesSQL Remote provides two-way replication between database servers at sales offices or outlets and a central company office, without requiring database administration experience at each sales office beyond the initial setup and that required to maintain the server.
SQL Remote is not designed for up-to-the-minute data availability at each site. Instead, it is appropriate where data can be replicated at periods of an hour or so.
Such a setup may use an e-mail system to carry the replication, if there is already a company-wide e-mail system. Alternatively, an occasional dial-up system and file transfer software can be used to implement a FILE message system.
SQL Remote is easy to configure to allow each office to receive their own set of data. Tables that are of office interest only (staff records, perhaps, if the office is a franchise) may be kept private in the same database as the replicated data.
Layers can be added to SQL Remote hierarchies: for example, each sales office server could act as a consolidated database, supporting remote subscribers who work from that office.