Exploring the Impact of Systems Architecture and Systems Requirements on Systems Integration Complexity Dr. Rashmi Jaini, Anithashree Chandrasekaran, George Elias, Dr. Robert Cloutier Stevens Institute of Technology [email protected], [email protected], [email protected], [email protected] Abstract development projects in the government The need to perform faster systems sector. integration of complex systems require the Keywords: System Architecture, System architect and design team understand how Integration, Integration Complexity, System the selected architecture and design Requirements components will impact the system Introduction integration processes complexity. System It is necessary to determine if integration process complexity is an integration of the defined physical elements outcome of the interaction between degree and interfaces in system architecture of feasibility and level of effort required to contributes to system integration process understand, describe, implement, manage complexity. Today’s systems are usually and document the system integration process expected to function independently and in for a given system development and cooperation with the existing systems operational environment. This paper (system of systems). The cooperating analyzes the cause and effect relationships systems undergo frequent changes and between the system requirements, interoperability becomes a key factor and a architecture and the system integration major contributor to system integration processes complexity. In order to address process complexity. Interoperability is based systems integration issues upfront in the on the existence of the conceptual view design phase it is necessary to determine if [Carney and Oberndoff, 2004]. The the architecture and design of components, conceptual view can be embodied in sub-systems, processes and interfaces requirements and architecture/design and the impacts (and to what extent) system system architecture determines the level of integration process complexity. This paper interoperability. The system integration also defines, and analyzes the impact of the process complexity includes interoperability. different system architecture and The major focus of the paper is on requirements factors on system integration the cause and effect relationship between process complexity. A research framework system requirements, system architecture, is developed to understand the cause and and system integration process complexity. effect relationships between the system The paper is based on the research that requirements, architecture and integration includes system engineering literature process. Finally, the paper proposes reviews, study of industry best practices and recommendations based on the causality a survey of the system engineering leads for results. These conclusions are based on eight different development projects in a research undertaken by the authors on 8 government organization. The research methodology used for this study is provided in Figure 1. This paper is organized in a were selected. The selection of these similar outline, first establishing the context activities and factors were based on the by defining and discussing system assumption that these activities contribute integration process, and its complexity towards better requirements and architecture classification. In order to understand, and would also reduce the system analyze and prioritize the causal factors a integration process complexity, and improve cause and effect relationship model was the quality of system verification and developed and relevant attributes of good validation. A survey was then developed to requirements and architecture were verify and validate this. Finally, this paper identified. These requirements and discusses a set of research questions and the architecture attributes define the activities findings to further provide a meaningful involved in these two critical phases and analysis of these relationships between enable a relatively simplified integration system requirements, architecture and process. Next, a set of activities/factors of integration process complexity. system requirements and system architecture Research Methodology: Cause and Effect Relationship between SR, SA and SI Process Complexity Our research knowledge base in SI Research on factors of system Research on system integration models, methodologies and requirements and architecture that process complexity practices approaches impact SI process Review of Review Literature & Literature Industry best best Industry Define SI process Identify the cause and effect relationships complexity & its between system requirements, architecture classification and integration process complexity on the reviews on Synthesis based based Synthesis Identify significant factors of system Research Questions & requirements and system architecture that Survey analysis Survey Development result in improving SI process & quality of synthesis analysis & & analysis V&V SI process SI process complexity survey survey complexity Figure 1 Research Methodology System Integration Process Systems integration is the process Complexity that links the systems engineering life cycle System integration (SI) process is process from requirements to verification defined as a set of activities that transforms and validation and ultimately the stakeholder requirements into an implementation of the system as shown in operational system by unifying the process the Figure 2. This linking process is also components and product components while called traceability, which is an integral ensuring compliance to the specified levels component of an effective systems of component operations and integration process. interoperability/interdependence. The system architecture and design is determined by the system requirements 2 which are originated and derived from the allocates the system functionality into stakeholder requirements. Requirements components, sometimes referred to as specification involves translating system Hardware Configuration Items (HWCI) and requirements into a formal representation of Computer Software Configuration Items interrelated units. The output of this process (CSCI), and defines the interfaces between serves as a blueprint of the system which these configuration items. The complexity of guides and controls all the subsequent the systems integration process may be development activities [Dogru, et.al, 1992]. determined by the functional and physical The architecture and design decomposes and decomposition of the system architecture. REQUIREMENTS FUNCTIONAL/PHYSICAL ARCHITECTURE S Input Reqts System Y S Output Reqts T Processing Reqts E M Non-Functional Reqts SubSystem 1 S U Input Reqts B S Output Reqts Y SubSystem 2 S T Processing Reqts E M Non-Funct. Reqts Systems Integration 1 S U Input Reqts B S Output Reqts Y S CSCI 1 – Application X T Processing Reqts E M Non-Funct. Reqts 2 CSCI 2 – Application Y HWCI 1 – Processor CSCI 1 Reqts . CSCI 1 Reqts As you create your architecture (design), you . HWCI 1 Reqts determine the requirements allocation and trace . between the requirements and design . Figure 2 System Integrationii Figure 2 demonstrates the process by providing strategy of system decomposition, which the functional architecture enables the data storage, inter-process and user requirements to be traced and defined for communication each of the configuration items that are a The importance of the system integration part of the physical architecture. These process in the development of a system and requirements form the basis for hardware its successful implementation can be and software detail design and development. understood and appreciated by Requirements are usually allocated to understanding and familiarizing with these functions (within the functional SI process activities. Despite the large architecture), that are performed by physical investments that are made, many integration elements. In [Rossak and Prasad, 1991] efforts fail for a number of technical, Rossak and Prasad state that integration organizational and management, and architectures for system of systems serve as migration planning reasons. The technical a general pattern to define the basic layout issues include the following [Smith, et al. of an integrated system. The integration 2002]: architectures deal with the development of new system parts and the post-facto ¾ Legacy systems originated from integration of already existing solutions by 3 unplanned, stovepipe development or understand, describe, implement, manage were developed as batch, single tier. and document the system integration process ¾ Data is specific to the applications and activities are shown in Table 1. This list is was not designed for sharing. based on our system integration framework ¾ The legacy systems were not initially and system integration process model (SIPM) designed for new quality-attribute [Jain, et al. 2007a, 2007b]. requirements and are being affected by Table 1 Factors that impact degree of needs for interoperability, performance, feasibility and level of effort required for security, and usability. SI ¾ The scope for the integration effort is not adequately defined. Factors that impact ¾ Decisions are made without performing Degree of feasibility Level of effort required adequate analyses (sometimes referred to Availability of the Documentation of the as “management by magazine”) integration (including system requirements V&V) methodologies