RTSE requires a basic data delivery service, which it obtains by invoking P-DATA from the Presentation Layer. RTSE also requires synchronization services provided by the Session Layer. The user of RTSE requires very little knowledge of the Session Layer, only that it provides for one way or two-way-alternate communication modes. RTSE itself will invoke other Session Layer services to provide for protection against data loss. Specifically, RTSE requires tools to distinguish between data that has been delivered safely to the destination application and that which is not yet known to be secure. It also needs to be able to request the retransmission of data that did not make it to its intended destination. We will investigate those services in detail when we discuss the Session Layer and will also discuss why we need these additional services on top of the reliable transport service offered in the Transport Layer.
RTSE addresses a limited set of potential failures on a remote system. In distributed application development, many types of conflicts and inconsistencies can arise if cooperating processes are not carefully coordinated. In the next section, we consider problems and approaches to addressing those problems.