One of the most important aspects when designing and constructing an Information System is its architecture. This also applies to complex systems such as System of Information Systems (SoIS). Thus , we aim to propose an architectural model of System of Information Systems (SoIS). Though Architecture-based approaches have been promoted as a means of controlling the complexity of systems construction and evolution , what we really look for in this paper is an architectural model to aggregate services from already constructed systems. Nevertheless , it would be a good practice to compare the presented architecture of SoIS to other architecture-based approaches such as Service Oriented Architecture (SOA). Also , it is beneficial to examine how we can use the well-established standards of SOA for the designing of SoIS. In this paper we present an architectural model for System of Information Systems , and highlight the standards of Service Oriented Architecture that might help us in this task .