In this chapter, we have introduced the notions of timeliness and reliability. We have seen that a simple RPC system can be enhanced to provide Atomic Operations, and that by annotating an interface specification, we can provide enough information to implement objects which provide failure transparency. At the same time, concurrency transparency is provided through analysing the concurrency predicates, so that independent atomic operations can execute in a timely way, while dependent ones are serialized correctly. <#724#>#tex2html_wrap3846#<#724#> Open Real Time systems are a long way off in reality. The mission-critical nature of real time systems has meant that the cost of a a single supplier is balanced by the value of testing and stability of the system they supply. Until distributed realtime systems are far better understood, it is unlikely that we will see many multivendor systems running air-traffic or health system control. <#725#>#tex2html_wrap3848#<#725#>