Enterprise Systems Engineering Key Concepts
- 1 Introduction
- 2 Closing the Gap
- 3 Role of Requirements in ESE
- 4 Enterprise Entities and Relationships
- 5 Enterprise Architecture Frameworks & Methodologies
- 6 References
- 7 Comments from SEBok 0.5 Wiki
- 8 SEBoK Discussion
The purpose of traditional systems engineering (TSE) is to bring together a diversity of discipline experts to address a wide range of problems inherent in the development of a large, complex , “single” system (Blanchard and Fabrycky 2010; Hall 1989; Sage and Rouse 2009). Enterprise systems engineering (ESE) expands beyond this traditional basis to “consider the full range of SE services increasingly needed in a modern organization where information-intensive systems are becoming central elements of the organization’s business strategy” (Carlock and Fenton 2001, 242-261). The traditional role of systems engineering (SE) is heavily involved in system acquisition and implementation, especially in the context of government acquisition of very large, complex military and civil systems (e.g., F22 fighter jet and air traffic control systems).
ESE encompasses this traditional role in system acquisition, but also incorporates enterprise strategic planning and enterprise investment analysis (along with others as described below). These two additional roles for SE at the enterprise level are “shared with the organization’s senior line management, and tend to be more entrepreneurial, business-driven, and economic in nature in comparison to the more technical nature of classical systems engineering” (Carlock and Fenton 2001, 242-261).
Closing the Gap
The MITRE Corporation has done significant development of ESE practices.
Today the watchword is enterprise systems engineering, reflecting a growing recognition that an “enterprise” may comprise many organizations from different parts of government, from the private and public sectors, and, in some cases, from other nations. (MITRE 2004)
(Rebovich 2006) says there are “new and emerging modes of thought that are increasingly being recognized as essential to successful systems engineering in enterprises.” In addition to the TSE process areas, MITRE has included the following process areas in their ESE process (DeRosa 2005) to close the gap between ESE and product SE:
- Strategic Technical Planning
- Enterprise Architecture
- Capabilities-Based Planning Analysis
- Technology Planning
- Enterprise Analysis and Assessment
These ESE processes are shown in the context of the entire enterprise in the figure below (DeRosa 2006). The ESE processes are shown in the middle with business processes on the left and TSE processes on the right. These business processes are described in the article called Related Business Activities. The TSE processes are well documented in many sources, especially in the ISO/IEC 15288 standard (2008).
SE is viewed by many organizations and depicted in many process definitions as bounded by the beginning and end of a system development project. In MITRE this restricted definition was referred to as TSE. Many have taken a wider view seeking to apply SE to the “whole system” and “whole life cycle.” For example, Hitchins (1993) sets out a holistic, whole-life, wider system view of SE centered on operational purpose. Elliott and Deasley (2007) discuss the differences between development phase SE and in-service SE.
In contrast to TSE, the ESE discipline is more like a “regimen” (Kuras and White 2005) that is responsible for identifying “outcome spaces,” shaping the development environment, coupling development to operations, and rewarding results rather than perceived promises (DeRosa 2005). ESE must continually characterize the operational environmental and the results of enterprise or SoS interventions to stimulate further actions within and among various systems in the enterprise portfolio . Outcome spaces are characterized by a set of desired capabilities that help meet enterprise objectives, as opposed to definitive “user requirements” based on near-term needs. Enterprise capabilities must be robust enough to handle unknown threats and situations in the future. A detailed description of previous MITRE views on ESE can be found in (Rebovich and White 2011).
Role of Requirements in ESE
TSE typically translates user needs into system requirements that drive the design of the system elements. The system requirements must be “frozen” long enough for the system components to be designed, developed, tested, built, and delivered to the end users (which can sometimes take years, and in the case of very large, complicated systems like spacecraft and fighter jets, more than a decade).
ESE, on the other hand, must account for the fact that the enterprise must be driven not by requirements (that rarely can even be defined, let alone made stable) but instead by continually changing organizational visions, goals, governance priorities, evolving technologies, and user expectations. An enterprise consists of people, processes, and technology where the people act as “agents” of the enterprise:
Ackoff has characterized an enterprise as a “purposeful system” composed of agents who choose both their goals and the means for accomplishing those goals. The variety of people, organizations, and their strategies is what creates the inherent complexity and non-determinism in an enterprise. ESE must account for the concerns, interests and objectives of these agents. (Swarz et al. 2006) (See also Complexity)
Whereas TSE focuses on output-based methodologies (e.g., functional analysis and object-oriented analysis), ESE is obligated to emphasize outcomes (e.g., business analysis and mission needs analysis), especially those related to the enterprise goals and key mission needs.
Enterprise Entities and Relationships
An enterprise “system” has different entities and relationships than you might find in a product/service system (see note 1). These can be usefully group into two categories: asset items and conceptual items. An example of an asset is hardware and software. Examples of conceptual items are things like analysis, financial elements, markets, policies, process, and strategy.
- Note 1. An “enterprise system” should not be confused with the enterprise “perceived as a system.” An enterprise system is a product (or service) system used across the enterprise, such as payroll, financial accounting, or enterprise resource planning applications, and consolidated data center, data warehouse, and other such facilities and equipment used across one or more organizations.
Products and services are sometimes treated as “assets” as shown in the figure below (Troux 2010). This categorization of enterprise items comes from the semantic model (i.e., metamodel) used in the Troux Architect modeling tool for characterization and analysis of an enterprise architecture. Other enterprise entities of interest are things like information, knowledge, skills, finances, policies, process, strategy, markets, and resources, but these are categorized as "concept" items (in this particular schema). Further details on how to use this metamodel's entities and relationships is provided by Reese (2010).
The application/software and infrastructure/hardware domains are likely the most familiar to systems engineers (as illustrated in the figure below). The application/software domain contains things like the deployed software itself plus applications, modules, servers, patches, functions, and messages. The infrastructure/hardware domain contains things like the hardware itself plus networks and different kinds of hardware like computing hardware, cabinets, and network devices. There might different subtypes of computing hardware like computers, servers, desktops, laptops, and mainframes. You can see from this elaboration of these domains that an enterprise architecture "schema" can be quite extensive in the kinds of things it can model.
The less technical domains would be things like policy, market, strategy, transition, financial, knowledge and skill, and analysis. In a typical enterprise architecture schema like this there could over a hundred types of modeling objects grouped into these domains. The examples give above are from the Troux Semantics metamodel used in the Troux Architect modeling tool for enterprise architecture activities. Other enterprise modeling tools have similar metamodels (or sometimes called “schemas”). See Reese (2010) for more details on how to use the metamodel shown in the figure above.
Enterprise Architecture Frameworks & Methodologies
Enterprise architecture frameworks are collections of standardized viewpoints, views and models that can be used when developing architectural descriptions of the enterprise. These architecture descriptions can be informal based on simple graphics and tables or informal based on more rigorous modeling tools and methods. ISO/IEC 42010 (2011) specifies how to create architecture descriptions.
These frameworks relate to descriptive models of an enterprise, with conventions agreed in particular communities. There are various frameworks and methodologies available that assist in the development of an enterprise architecture . Some of these are described below.
The “standard” entities and relationships used in architecture modeling of an enterprise are specified in metamodels and viewpoint specifications in various domain-specific architecture frameworks. The figure below, as one example, shows the metamodel for the TRAK architecture framework (TRAK 2011). This framework was developed primarily for the rail industry in the United Kingdom but has been used in other domains as well.
The figure below shows the metamodel for the United States Department of Defense (DoD) Architecture framework (DoD 2010). "DoDAF defines a set of views that act as mechanisms for visualizing, understanding, and assimilating the broad scope and complexities of an architecture description through tabular, structural, behavioral, ontological, pictorial, temporal or graphical means. It is especially suited to large systems with complex integration and interoperability challenges, and is apparently unique in its use of 'operational views' detailing the external customer's operating domain in which the developing system will operate." (http://en.wikipedia.org/wiki/DODAF)
A related framework is the Ministry of Defense (MOD) Architecture Framework (MODAF): "Initially the purpose of MODAF was to provide rigour and structure to support the definition and integration of MOD equipment capability, particularly in support of Network Enabled Capability (NEC). More recently, MOD has additionally been using MODAF to underpin the use of the Enterprise Architecture approach to the capture of the information about the business to identify the processes and resources required to deliver the vision expressed in the strategy." (http://en.wikipedia.org/wiki/Modaf)
Some frameworks (like The Open Group Architecture Framework (TOGAF)) are more properly called methodologies since they focus on the process (see figure below) by which artifacts are created and how they are used. Other frameworks (like Zachman and CIO Council 1999) are more properly called taxonomies since they define and categorize the kinds of elements of interest to the enterprise analyst (Ref: A Comparison of the Top Four Enterprise-Architecture Methodologies, http://msdn.microsoft.com/en-us/library/bb466232.aspx).
The figure below shows the Zachman architecture framework (taxonomy) (Zachman 1987 and 1992). The columns represent the six “interrogatives” of why, how, what, who, where, and when, and these can be considered to be “stakeholder concerns” of the enterprise stakeholders. These columns also represent data (i.e., the “what”), functions, networks, people, time, and motivation. The rows represent the different stakeholder “perspectives”: contextual (planners), conceptual (owners), logical (designers), physical (builders), and detailed (subcontractors or suppliers). These rows also represent the following “perspectives”: scope (i.e., contextual), business model, system model, technology model, and detailed representations.
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