The High Level Architecture (HLA) time management is concerned with mechanisms for guaranteeing message order, process synchronization and execution correctness in distributed simulations. Time management greatly influences on the scales of applications, especially for the computation of Greatest Available Logical Time (GALT) and the implementation of optimistic services. StarLink is an RTI with central architecture, which is compliant with the IEEE 1516 standard. This paper systematically describes the implementation algorithms for main time management services in StarLink. Two smart and efficient algorithms about GALT computation and optimistic services are also introduced, which are suitable for many RTIs such as RTI1.3-NG, pRTI and DRTI. For the GALT algorithm, it is not necessary for an RTI to resolve the recursion nor any deadlock. For optimistic services, a simple mechanism without rollback in an RTI is also introduced; therefore, it can greatly simplify the development of an RTI.