There are important distributed computing systems which are neither massive nor high performance. Examples are: telecommunications systems, transportation or power networks, embedded control systems (such as embedded electronics in automobiles), or Systems on a Chip. Many of them are embedded systems, i.e., not directly visible to the user. For these systems, performance is not a primary issue, major issues are reviewed in this paper. Then, we focus on a particular but important point, namely the  correct implementation of specifications on distributed architectures.