This chapter provides principles for the use and deployment of IT resources across the enterprise.

This chapter builds on work done by the US Air Force in establishing its Headquarters Air Force Principles for Information Management (June 29, 1998), with the addition of other input materials.

Introduction

Principles are general rules and guidelines, intended to be enduring and seldom amended, that inform and support the way in which an organization sets about fulfilling its mission.

In their turn, principles may be just one element in a structured set of ideas that collectively define and guide the organization, from values through to actions and results.

Depending on the organization, principles may be established at any or all of three levels:

• Enterprise principles provide a basis for decision-making throughout an enterprise, and inform how the organization sets about fulfilling its mission. Such enterprise-level principles are commonly found in governmental and not-for-profit organizations, but are encountered in commercial organizations also, as a means of harmonizing decision-making across a distributed organization. In particular, they are a key element in a successful architecture governance strategy (see Architecture Governance).
• Information Technology (IT) principles provide guidance on the use and deployment of all IT resources and assets across the enterprise. They are developed in order to make the information environment as productive and cost-effective as possible.
• Architecture principles are a subset of IT principles that relate to architecture work. They reflect a level of consensus across the enterprise, and embody the spirit and thinking of the enterprise architecture. Architecture principles can be further divided into:
  • Principles that govern the architecture process, affecting the development, maintenance, and use of the enterprise architecture
  • Principles that govern the implementation of the architecture, establishing the first tenets and related guidance for designing and developing information systems

These sets of principles form a hierarchy, in that IT principles will be informed by, and elaborate on, the principles at the enterprise level; and architecture principles will likewise be informed by the principles at the two higher levels.

The remainder of this section deals exclusively with architecture principles.

Characteristics of Architecture Principles

Architecture principles define the underlying general rules and guidelines for the use and deployment of all IT resources and assets across the enterprise. They reflect a level of consensus among the various elements of the enterprise, and form the basis for making future IT decisions.

Each architecture principle should be clearly related back to the business objectives and key architecture drivers.

Components of Architecture Principles

It is useful to have a standard way of defining principles. In addition to a definition statement, each principle should have associated rationale and implications statements, both to promote understanding and acceptance of the principles themselves, and to support the use of the principles in explaining and justifying why specific decisions are made.

A recommended template is given in Recommended Format for Defining Principles .

An example set of architecture principles following this template is given in Example Set of Architecture Principles .

Developing Architecture Principles

Architecture principles are typically developed by the Lead Architect, in conjunction with the enterprise CIO, Architecture Board, and other key business stakeholders.

Appropriate policies and procedures must be developed to support the implementation of the principles.

Architecture principles will be informed by overall IT principles and principles at the enterprise level, if they exist. They are chosen so as to ensure alignment of IT strategies with business strategies and visions. Specifically, the development of architecture principles is typically influenced by the following:

• Enterprise mission and plans: the mission, plans, and organizational infrastructure of the enterprise.
• Enterprise strategic initiatives: the characteristics of the enterprise - its strengths, weaknesses, opportunities, and threats - and its current enterprise-wide initiatives (such as process improvement and quality management).
• External constraints: market factors (time-to-market imperatives, customer expectations, etc.); existing and potential legislation.
• Current systems and technology: the set of information resources deployed within the enterprise, including systems documentation, equipment inventories, network configuration diagrams, policies, and procedures.
• Computer industry trends: predictions about the usage, availability, and cost of computer and communication technologies, referenced from credible sources along with associated best practices presently in use.

Qualities of Principles

Merely having a written statement that is called a principle does not mean that the principle is good, even if everyone agrees with it.

A good set of principles will be founded in the beliefs and values of the organization and expressed in language that the business understands and uses. Principles should be few in number, future-oriented, and endorsed and championed by senior management. They provide a firm foundation for making architecture and planning decisions, framing policies, procedures, and standards, and supporting resolution of contradictory situations. A poor set of principles will quickly become disused, and the resultant architectures, policies, and standards will appear arbitrary or self-serving, and thus lack credibility. Essentially, principles drive behavior.

There are five criteria that distinguish a good set of principles:

• Understandable: the underlying tenets can be quickly grasped and understood by individuals throughout the organization. The intention of the principle is clear and unambiguous, so that violations, whether intentional or not, are minimized.
• Robust: enable good quality decisions about architectures and plans to be made, and enforceable policies and standards to be created. Each principle should be sufficiently definitive and precise to support consistent decision-making in complex, potentially controversial situations.
• Complete: every potentially important principle governing the management of information and technology for the organization is defined. The principles cover every situation perceived.
• Consistent: strict adherence to one principle may require a loose interpretation of another principle. The set of principles must be expressed in a way that allows a balance of interpretations. Principles should not be contradictory to the point where adhering to one principle would violate the spirit of another. Every word in a principle statement should be carefully chosen to allow consistent yet flexible interpretation.
• Stable: principles should be enduring, yet able to accommodate changes. An amendment process should be established for adding, removing, or altering principles after they are ratified initially.

Applying Architecture Principles

Architecture principles are used to capture the fundamental truths about how the enterprise will use and deploy IT resources and assets. The principles are used in a number of different ways:

1. To provide a framework within which the enterprise can start to make conscious decisions about IT
2. As a guide to establishing relevant evaluation criteria, thus exerting strong influence on the selection of products or product architectures in the later stages of managing compliance to the IT architecture
3. As drivers for defining the functional requirements of the architecture
4. As an input to assessing both existing IS/IT systems and the future strategic portfolio, for compliance with the defined architectures. These assessments will provide valuable insights into the transition activities needed to implement an architecture, in support of business goals and priorities
5. The Rationale statements (see below) highlight the value of the architecture to the enterprise, and therefore provide a basis for justifying architecture activities
6. The Implications statements (see below) provide an outline of the key tasks, resources, and potential costs to the enterprise of following the principle; they also provide valuable inputs to future transition initiative and planning activities
7. Support the architecture governance activities in terms of:
   • Providing a "back-stop" for the standard Architecture Compliance assessments where some interpretation is allowed or required
   • Supporting the decision to initiate a dispensation request where the implications of a particular architecture amendment cannot be resolved within local operating procedure

Principles are inter-related, and need to be applied as a set.

Principles will sometimes compete; for example, the principles of "accessibility" and "security" tend towards conflicting decisions. Each principle must be considered in the context of "all other things being equal".

At times a decision will be required as to which information principle will take precedence on a particular issue. The rationale for such decisions should always be documented.

A common reaction on first reading of a principle is "this is motherhood", but the fact that a principle seems self-evident does not mean that the principle is actually observed in an organization, even when there are verbal acknowledgements of the principle.

Although specific penalties are not prescribed in a declaration of principles, violations of principles generally cause operational problems and inhibit the ability of the organization to fulfil its mission.

Example Set of Architecture Principles

Too many principles can reduce the flexibility of the architecture. Many organizations prefer to define only high-level principles, and to limit the number to between 10 and 20.

The following example illustrates both the typical content of a set of architecture principles, and the recommended format for defining them, as explained above.

Another example of architecture principles is contained in the US Government's Federal Enterprise Architecture Framework (FEAF - see FEAF).

Business Principles

Principle 1:

Primacy of Principles

Statement:

These principles of information management apply to all organizations within the enterprise.

Rationale:

The only way we can provide a consistent and measurable level of quality information to decision-makers is if all organizations abide by the principles.

Implications:

• Without this principle, exclusions, favoritism, and inconsistency would rapidly undermine the management of information.
• Information management initiatives will not begin until they are examined for compliance with the principles.
• A conflict with a principle will be resolved by changing the framework of the initiative.

Principle 2:

Maximize Benefit to the Enterprise

Statement:

Information management decisions are made to provide maximum benefit to the enterprise as a whole.

Rationale:

This principle embodies "service above self". Decisions made from an enterprise-wide perspective have greater long-term value than decisions made from any particular organizational perspective. Maximum return on investment requires information management decisions to adhere to enterprise-wide drivers and priorities. No minority group will detract from the benefit of the whole. However, this principle will not preclude any minority group from getting its job done.

Implications:

• Achieving maximum enterprise-wide benefit will require changes in the way we plan and manage information. Technology alone will not bring about this change.
• Some organizations may have to concede their own preferences for the greater benefit of the entire enterprise.
• Application development priorities must be established by the entire enterprise for the entire enterprise.
• Applications components should be shared across organizational boundaries.
• Information management initiatives should be conducted in accordance with the enterprise plan. Individual organizations should pursue information management initiatives which conform to the blueprints and priorities established by the enterprise. We will change the plan as we need to.
• As needs arise, priorities must be adjusted. A forum with comprehensive enterprise representation should make these decisions.

Principle 3:

Information Management is Everybody's Business

Statement:

All organizations in the enterprise participate in information management decisions needed to accomplish business objectives.

Rationale:

Information users are the key stakeholders, or customers, in the application of technology to address a business need. In order to ensure information management is aligned with the business, all organizations in the enterprise must be involved in all aspects of the information environment. The business experts from across the enterprise and the technical staff responsible for developing and sustaining the information environment need to come together as a team to jointly define the goals and objectives of IT.

Implications:

• To operate as a team, every stakeholder, or customer, will need to accept responsibility for developing the information environment.
• Commitment of resources will be required to implement this principle.

Principle 4:

Business Continuity

Statement:

Enterprise operations are maintained in spite of system interruptions.

Rationale:

As system operations become more pervasive, we become more dependent on them; therefore, we must consider the reliability of such systems throughout their design and use. Business premises throughout the enterprise must be provided with the capability to continue their business functions regardless of external events. Hardware failure, natural disasters, and data corruption should not be allowed to disrupt or stop enterprise activities. The enterprise business functions must be capable of operating on alternative information delivery mechanisms.

Implications:

• Dependency on shared system applications mandates that the risks of business interruption must be established in advance and managed. Management includes but is not limited to periodic reviews, testing for vulnerability and exposure, or designing mission-critical services to assure business function continuity through redundant or alternative capabilities.
• Recoverability, redundancy, and maintainability should be addressed at the time of design.
• Applications must be assessed for criticality and impact on the enterprise mission, in order to determine what level of continuity is required and what corresponding recovery plan is necessary.

Principle 5:

Common Use Applications

Statement:

Development of applications used across the enterprise is preferred over the development of similar or duplicative applications which are only provided to a particular organization.

Rationale:

Duplicative capability is expensive and proliferates conflicting data.

Implications:

• Organizations which depend on a capability which does not serve the entire enterprise must change over to the replacement enterprise-wide capability. This will require establishment of and adherence to a policy requiring this.
• Organizations will not be allowed to develop capabilities for their own use which are similar/duplicative of enterprise-wide capabilities. In this way, expenditures of scarce resources to develop essentially the same capability in marginally different ways will be reduced.
• Data and information used to support enterprise decision-making will be standardized to a much greater extent than previously. This is because the smaller, organizational capabilities which produced different data (which was not shared among other organizations) will be replaced by enterprise-wide capabilities. The impetus for adding to the set of enterprise-wide capabilities may well come from an organization making a convincing case for the value of the data/information previously produced by its organizational capability, but the resulting capability will become part of the enterprise-wide system, and the data it produces will be shared across the enterprise.

Principle 6:

Compliance with Law

Statement:

Enterprise information management processes comply with all relevant laws, policies, and regulations.

Rationale:

Enterprise policy is to abide by laws, policies, and regulations. This will not preclude business process improvements that lead to changes in policies and regulations.

Implications:

• The enterprise must be mindful to comply with laws, regulations, and external policies regarding the collection, retention, and management of data.
• Education and access to the rules. Efficiency, need, and common sense are not the only drivers. Changes in the law and changes in regulations may drive changes in our processes or applications.

Principle 7:

IT Responsibility

Statement:

The IT organization is responsible for owning and implementing IT processes and infrastructure that enable solutions to meet user-defined requirements for functionality, service levels, cost, and delivery timing.

Rationale:

Effectively align expectations with capabilities and costs so that all projects are cost-effective. Efficient and effective solutions have reasonable costs and clear benefits.

Implications:

• A process must be created to prioritize projects.
• The IT function must define processes to manage business unit expectations.
• Data, application, and technology models must be created to enable integrated quality solutions and to maximize results.

Principle 8:

Protection of Intellectual Property

Statement:

The enterprise's Intellectual Property (IP) must be protected. This protection must be reflected in the IT architecture, implementation, and governance processes.

Rationale:

A major part of an enterprise's IP is hosted in the IT domain.

Implications:

• While protection of IP assets is everybody's business, much of the actual protection is implemented in the IT domain. Even trust in non-IT processes can be managed by IT processes (email, mandatory notes, etc.).
• A security policy, governing human and IT actors, will be required that can substantially improve protection of IP. This must be capable of both avoiding compromises and reducing liabilities.
• Resources on such policies can be found at the SANS Institute (www.sans.org/newlook/home.php).

Data Principles

Principle 9:

Data is an Asset

Statement:

Data is an asset that has value to the enterprise and is managed accordingly.

Rationale:

Data is a valuable corporate resource; it has real, measurable value. In simple terms, the purpose of data is to aid decision-making. Accurate, timely data is critical to accurate, timely decisions. Most corporate assets are carefully managed, and data is no exception. Data is the foundation of our decision-making, so we must also carefully manage data to ensure that we know where it is, can rely upon its accuracy, and can obtain it when and where we need it.

Implications:

• This is one of three closely-related principles regarding data: data is an asset; data is shared; and data is easily accessible. The implication is that there is an education task to ensure that all organizations within the enterprise understand the relationship between value of data, sharing of data, and accessibility to data.
• Stewards must have the authority and means to manage the data for which they are accountable.
• We must make the cultural transition from "data ownership" thinking to "data stewardship" thinking.
• The role of data steward is critical because obsolete, incorrect, or inconsistent data could be passed to enterprise personnel and adversely affect decisions across the enterprise.
• Part of the role of data steward, who manages the data, is to ensure data quality. Procedures must be developed and used to prevent and correct errors in the information and to improve those processes that produce flawed information. Data quality will need to be measured and steps taken to improve data quality - it is probable that policy and procedures will need to be developed for this as well.
• A forum with comprehensive enterprise-wide representation should decide on process changes suggested by the steward.
• Since data is an asset of value to the entire enterprise, data stewards accountable for properly managing the data must be assigned at the enterprise level.

Principle 10:

Data is Shared

Statement:

Users have access to the data necessary to perform their duties; therefore, data is shared across enterprise functions and organizations.

Rationale:

Timely access to accurate data is essential to improving the quality and efficiency of enterprise decision-making. It is less costly to maintain timely, accurate data in a single application, and then share it, than it is to maintain duplicative data in multiple applications. The enterprise holds a wealth of data, but it is stored in hundreds of incompatible stovepipe databases. The speed of data collection, creation, transfer, and assimilation is driven by the ability of the organization to efficiently share these islands of data across the organization.

Shared data will result in improved decisions since we will rely on fewer (ultimately one virtual) sources of more accurate and timely managed data for all of our decision-making. Electronically shared data will result in increased efficiency when existing data entities can be used, without re-keying, to create new entities.

Implications:

• This is one of three closely-related principles regarding data: data is an asset; data is shared; and data is easily accessible. The implication is that there is an education task to ensure that all organizations within the enterprise understand the relationship between value of data, sharing of data, and accessibility to data.
• To enable data sharing we must develop and abide by a common set of policies, procedures, and standards governing data management and access for both the short and the long term.
• For the short term, to preserve our significant investment in legacy systems, we must invest in software capable of migrating legacy system data into a shared data environment.
• We will also need to develop standard data models, data elements, and other metadata that defines this shared environment and develop a repository system for storing this metadata to make it accessible.
• For the long term, as legacy systems are replaced, we must adopt and enforce common data access policies and guidelines for new application developers to ensure that data in new applications remains available to the shared environment and that data in the shared environment can continue to be used by the new applications.
• For both the short term and the long term we must adopt common methods and tools for creating, maintaining, and accessing the data shared across the enterprise.
• Data sharing will require a significant cultural change.
• This principle of data sharing will continually "bump up against" the principle of data security. Under no circumstances will the data sharing principle cause confidential data to be compromised.
• Data made available for sharing will have to be relied upon by all users to execute their respective tasks. This will ensure that only the most accurate and timely data is relied upon for decision-making. Shared data will become the enterprise-wide "virtual single source" of data.

Principle 11:

Data is Accessible

Statement:

Data is accessible for users to perform their functions.

Rationale:

Wide access to data leads to efficiency and effectiveness in decision-making, and affords timely response to information requests and service delivery. Using information must be considered from an enterprise perspective to allow access by a wide variety of users. Staff time is saved and consistency of data is improved.

Implications:

• This is one of three closely-related principles regarding data: data is an asset; data is shared; and data is easily accessible. The implication is that there is an education task to ensure that all organizations within the enterprise understand the relationship between value of data, sharing of data, and accessibility to data.
• Accessibility involves the ease with which users obtain information.
• The way information is accessed and displayed must be sufficiently adaptable to meet a wide range of enterprise users and their corresponding methods of access.
• Access to data does not constitute understanding of the data. Personnel should take caution not to misinterpret information.
• Access to data does not necessarily grant the user access rights to modify or disclose the data. This will require an education process and a change in the organizational culture, which currently supports a belief in "ownership" of data by functional units.

Principle 12:

Data Trustee

Statement:

Each data element has a trustee accountable for data quality.

Rationale:

One of the benefits of an architected environment is the ability to share data (e.g., text, video, sound, etc.) across the enterprise. As the degree of data sharing grows and business units rely upon common information, it becomes essential that only the data trustee makes decisions about the content of data. Since data can lose its integrity when it is entered multiple times, the data trustee will have sole responsibility for data entry which eliminates redundant human effort and data storage resources.

Note:

A trustee is different than a steward - a trustee is responsible for accuracy and currency of the data, while responsibilities of a steward may be broader and include data standardization and definition tasks.

Implications:

• Real trusteeship dissolves the data "ownership" issues and allows the data to be available to meet all users' needs. This implies that a cultural change from data "ownership" to data "trusteeship" may be required.
• The data trustee will be responsible for meeting quality requirements levied upon the data for which the trustee is accountable.
• It is essential that the trustee has the ability to provide user confidence in the data based upon attributes such as "data source".
• It is essential to identify the true source of the data in order that the data authority can be assigned this trustee responsibility. This does not mean that classified sources will be revealed nor does it mean the source will be the trustee.
• Information should be captured electronically once and immediately validated as close to the source as possible. Quality control measures must be implemented to ensure the integrity of the data.
• As a result of sharing data across the enterprise, the trustee is accountable and responsible for the accuracy and currency of their designated data element(s) and, subsequently, must then recognize the importance of this trusteeship responsibility.

Principle 13:

Common Vocabulary and Data Definitions

Statement:

Data is defined consistently throughout the enterprise, and the definitions are understandable and available to all users.

Rationale:

The data that will be used in the development of applications must have a common definition throughout the Headquarters to enable sharing of data. A common vocabulary will facilitate communications and enable dialogue to be effective. In addition, it is required to interface systems and exchange data.

Implications:

• We are lulled into thinking that this issue is adequately addressed because there are people with "data administration" job titles and forums with charters implying responsibility. Significant additional energy and resources must be committed to this task. It is key to the success of efforts to improve the information environment. This is separate from but related to the issue of data element definition, which is addressed by a broad community - this is more like a common vocabulary and definition.
• The enterprise must establish the initial common vocabulary for the business. The definitions will be used uniformly throughout the enterprise.
• Whenever a new data definition is required, the definition effort will be co-ordinated and reconciled with the corporate "glossary" of data descriptions. The enterprise data administrator will provide this co-ordination.
• Ambiguities resulting from multiple parochial definitions of data must give way to accepted enterprise-wide definitions and understanding.
• Multiple data standardization initiatives need to be co-ordinated.
• Functional data administration responsibilities must be assigned.

Principle 14:

Data Security

Statement:

Data is protected from unauthorized use and disclosure. In addition to the traditional aspects of national security classification, this includes, but is not limited to, protection of pre-decisional, sensitive, source selection-sensitive, and proprietary information.

Rationale:

Open sharing of information and the release of information via relevant legislation must be balanced against the need to restrict the availability of classified, proprietary, and sensitive information.

Existing laws and regulations require the safeguarding of national security and the privacy of data, while permitting free and open access. Pre-decisional (work-in-progress, not yet authorized for release) information must be protected to avoid unwarranted speculation, misinterpretation, and inappropriate use.

Implications:

• Aggregation of data, both classified and not, will create a large target requiring review and de-classification procedures to maintain appropriate control. Data owners and/or functional users must determine whether the aggregation results in an increased classification level. We will need appropriate policy and procedures to handle this review and de-classification. Access to information based on a need-to-know policy will force regular reviews of the body of information.
• The current practice of having separate systems to contain different classifications needs to be rethought. Is there a software solution to separating classified and unclassified data? The current hardware solution is unwieldy, inefficient, and costly. It is more expensive to manage unclassified data on a classified system. Currently, the only way to combine the two is to place the unclassified data on the classified system, where it must remain.
• In order to adequately provide access to open information while maintaining secure information, security needs must be identified and developed at the data level, not the application level.
• Data security safeguards can be put in place to restrict access to "view only", or "never see". Sensitivity labeling for access to pre-decisional, decisional, classified, sensitive, or proprietary information must be determined.
• Security must be designed into data elements from the beginning; it cannot be added later. Systems, data, and technologies must be protected from unauthorized access and manipulation. Headquarters information must be safeguarded against inadvertent or unauthorized alteration, sabotage, disaster, or disclosure.
• Need new policies on managing duration of protection for pre-decisional information and other works-in-progress, in consideration of content freshness.

Application Principles

Principle 15:

Technology Independence

Statement:

Applications are independent of specific technology choices and therefore can operate on a variety of technology platforms.

Rationale:

Independence of applications from the underlying technology allows applications to be developed, upgraded, and operated in the most cost-effective and timely way. Otherwise technology, which is subject to continual obsolescence and vendor dependence, becomes the driver rather than the user requirements themselves.

Realizing that every decision made with respect to IT makes us dependent on that technology, the intent of this principle is to ensure that Application Software is not dependent on specific hardware and operating systems software.

Implications:

• This principle will require standards which support portability.
• For Commercial Off-The-Shelf (COTS) and Government Off-The-Shelf (GOTS) applications, there may be limited current choices, as many of these applications are technology and platform-dependent.
• Application Program Interfaces (APIs) will need to be developed to enable legacy applications to interoperate with applications and operating environments developed under the enterprise architecture.
• Middleware should be used to decouple applications from specific software solutions.
• As an example, this principle could lead to use of Java, and future Java-like protocols, which give a high degree of priority to platform-independence.

Principle 16:

Ease-of-Use

Statement:

Applications are easy to use. The underlying technology is transparent to users, so they can concentrate on tasks at hand.

Rationale:

The more a user has to understand the underlying technology, the less productive that user is. Ease-of-use is a positive incentive for use of applications. It encourages users to work within the integrated information environment instead of developing isolated systems to accomplish the task outside of the enterprise's integrated information environment. Most of the knowledge required to operate one system will be similar to others. Training is kept to a minimum, and the risk of using a system improperly is low.

Using an application should be as intuitive as driving a different car.

Implications:

• Applications will be required to have a common "look and feel" and support ergonomic requirements. Hence, the common look and feel standard must be designed and usability test criteria must be developed.
• Guidelines for user interfaces should not be constrained by narrow assumptions about user location, language, systems training, or physical capability. Factors such as linguistics, customer physical infirmities (visual acuity, ability to use keyboard/mouse), and proficiency in the use of technology have broad ramifications in determining the ease-of-use of an application.

Technology Principles

Principle 17:

Requirements-Based Change

Statement:

Only in response to business needs are changes to applications and technology made.

Rationale:

This principle will foster an atmosphere where the information environment changes in response to the needs of the business, rather than having the business change in response to IT changes. This is to ensure that the purpose of the information support - the transaction of business - is the basis for any proposed change. Unintended effects on business due to IT changes will be minimized. A change in technology may provide an opportunity to improve the business process and, hence, change business needs.

Implications:

• Changes in implementation will follow full examination of the proposed changes using the enterprise architecture.
• We don't fund a technical improvement or system development unless a documented business need exists.
• Change management processes conforming to this principle will be developed and implemented.
• This principle may bump up against the responsive change principle. We must ensure the requirements documentation process does not hinder responsive change to meet legitimate business needs. The purpose of this principle is to keep us focused on business, not technology needs - responsive change is also a business need.

Principle 18:

Responsive Change Management

Statement:

Changes to the enterprise information environment are implemented in a timely manner.

Rationale:

If people are to be expected to work within the enterprise information environment, that information environment must be responsive to their needs.

Implications:

• We have to develop processes for managing and implementing change that do not create delays.
• A user who feels a need for change will need to connect with a "business expert" to facilitate explanation and implementation of that need.
• If we are going to make changes, we must keep the architectures updated.
• Adopting this principle might require additional resources.
• This will conflict with other principles (e.g., maximum enterprise-wide benefit, enterprise-wide applications, etc.).

Principle 19:

Control Technical Diversity

Statement:

Technological diversity is controlled to minimize the non-trivial cost of maintaining expertise in and connectivity between multiple processing environments.

Rationale:

There is a real, non-trivial cost of infrastructure required to support alternative technologies for processing environments. There are further infrastructure costs incurred to keep multiple processor constructs interconnected and maintained.

Limiting the number of supported components will simplify maintainability and reduce costs.

The business advantages of minimum technical diversity include: standard packaging of components; predictable implementation impact; predictable valuations and returns; redefined testing; utility status; and increased flexibility to accommodate technological advancements. Common technology across the enterprise brings the benefits of economies of scale to the enterprise. Technical administration and support costs are better controlled when limited resources can focus on this shared set of technology.

Implications:

• Policies, standards, and procedures that govern acquisition of technology must be tied directly to this principle.
• Technology choices will be constrained by the choices available within the technology blueprint. Procedures for augmenting the acceptable technology set to meet evolving requirements will have to be developed and emplaced.
• We are not freezing our technology baseline. We welcome technology advances and will change the technology blueprint when compatibility with the current infrastructure, improvement in operational efficiency, or a required capability has been demonstrated.

Principle 20:

Interoperability

Statement:

Software and hardware should conform to defined standards that promote interoperability for data, applications, and technology.

Rationale:

Standards help ensure consistency, thus improving the ability to manage systems and improve user satisfaction, and protect existing IT investments, thus maximizing return on investment and reducing costs. Standards for interoperability additionally help ensure support from multiple vendors for their products, and facilitate supply chain integration.

Implications:

• Interoperability standards and industry standards will be followed unless there is a compelling business reason to implement a non-standard solution.
• A process for setting standards, reviewing and revising them periodically, and granting exceptions must be established.
• The existing IT platforms must be identified and documented.

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Downloads of the TOGAF documentation, are available under license from the TOGAF information web site. The license is free to any organization wishing to use TOGAF entirely for internal purposes (for example, to develop an information system architecture for use within that organization). A hardcopy book is also available from The Open Group Bookstore as document G063.