Intellisync

The Intellisync Anywhere [19] product family from Pumatech always makes synchronization `Fastsync enabled' by using one central server to which mobile devices always synchronize. This means that all synchronizing devices have to maintain status flags of updates with respect to only the central server, allowing for a Fastsync every time. Figure 2.6 shows a typical company network using the Intellisync architecture to setup and maintain a mobile device network for a Microsoft Exchange server. Information held at the exchange server is used to update information held on the Intellisync server. In addition, changes made by end users are stored on the Intellisync server and periodically synchronized with the exchange server. This periodic synchronization will result in a delay in the time it takes for updates made on the Exchange server to be available to users. The centralized approach creates a central point of failure. If the central server is congested, the entire network suffers. In addition, scalability with the number of devices in the network is a serious issue because the load on the server increases linearly with increasing devices in the network.

Figure 2.6: Intellisync Anywhere server installed on a company's network

On the upside, there are many secondary benefits of a centralized scheme, including the feasibility of centralized security policy and easier methods of broadcasting information in an organization's network (such as policy changes, event schedules etc.). The EDISON architecture proposed in [20] also relies on a centralized, shared server with which all hosts synchronize. The server maintains an incremental log of updates so that the hosts can always use Fastsync instead of Slowsync (see Section  2.2.1). This architecture is not designed for the general case where a device may synchronize with any other device on a peer-to-peer basis. In general, a distributed architecture based on peer-to-peer synchronization provides much better network performance, in terms of robustness and scalability, than a centralized architecture [21,22,23].