Capabilities Based Communication Model for High-Performance Distributed Applications

Typical high-performance distributed applications con-sist of clients accessing computational and information re-sources implemented by remote servers. Different clients may have different requirements for accessing a single server resource. A server resource may also want to pro-vide different kinds of accesses for different clients, depend-ing on factors such as the amount of trust between the server and a client. The requirements or attributes of remote ac-cess, such as data compression (and encryption) or client authentication, can be encapsulated under the concept of remote access capabilities. This paper presents a capabilities based model of com-munication and describes how it is implemented at appli-cation level in a programming environment called Open HPC++. Open HPC++ capabilities are associated with a remote reference and determine the kinds of remote ac-cess that it supports. Capabilities can be exchanged be-tween processes, and can also be changed dynamically to helps applications adapt to varying run-time environments. Capabilities also work with the load-balancing features of Open HPC++ to help applications achieve higher perfor-mance. The paper presents a set of experiments to demon-strate the usefulness of the capabilities based model. It also describes Open HPC++’s communication protocol adap-tivity mechanism, which is the basis of the capabilities based model. 1