When and Where to be Closed (Replicate)

By Donald Firesmith Principal Engineer
Software Application Solutions Department

Due to advances in software and hardware innovations, Department of Defense (DoD) systems today are extremely capable and complex. Nevertheless, they likewise deal with increasing scale, calculation, and security difficulties. Intensifying these difficulties, DoD systems were traditionally developed utilizing stove-piped architectures that lock the Federal government into a little number of system integrators, each developing proprietary point options that are pricey to establish and sustain over the lifecycle. Although these stove-piped options have actually been bothersome (and unsustainable) for many years, the spending plan cuts happening under sequestration are inspiring the DoD to renew its concentrate on determining alternative ways to drive down expenses, develop more budget-friendly acquisition options, and enhance acquisition program efficiency. An appealing method to fulfill these objectives is Open Systems Architecture (OSA), which integrates

This post broadens on earlier protection of how acquisition specialists and system integrators can use OSA practices to successfully break down big monolithic service and technical architectures into workable and modular options that can incorporate development more quickly and lower overall ownership expenses.

What is OSA and How Should It Be Applied?

By meaning, an OSA is any system (or software application) architecture that displays the following 3 useful qualities:

  1. It is modular, being disintegrated into architectural elements that are cohesive, loosely combined with other elements (and external systems), and encapsulate (conceal) their executions behind noticeable user interfaces.
  2. Its essential user interfaces in between architectural elements comply with open user interface requirements ( that is, agreement based, commonly utilized, and quickly offered to possible users).
  3. Its essential user interfaces have actually been confirmed to comply with the associated open user interface requirements.

By mandating specialists to engineer OSA (e.g., through Much Better Purchasing Power 3.0), federal government acquisition companies wish to accomplish numerous advantages, 2 of the most crucial of which are to increase competitors amongst designers of the architectural elements and to prevent supplier lock when it concerns obtaining and upgrading these elements. Offered these advantages, federal government program workplaces might think in the beginning look that all system architectures ought to be totally open. This impression is particularly real when one thinks about the DoD policies (such as DoDI 5000.02) that need program workplaces to make sure defense specialists produce open system architectures.

One important word in the meaning of open system architectures, nevertheless, exposes this preliminary impression to be incorrect. The meaning does not state that all user interfaces should comply with open user interface requirements, however rather just essential user interfaces should be open. Additionally, if one takes a look at real system architectures, one rapidly finds out that openness is not black and white however rather a matter of degree. Some user interfaces are extremely open (e.g., they comply with utilized worldwide requirements), some user interfaces are fairly open (i.e., they comply with less-widely utilized, more application-domain-specific requirements or commonly utilized de facto requirements), some user interfaces are a little open (e.g., they comply with product-line-specific conventions), and some user interfaces are basically closed (i.e., they are system-unique or comply with contractor-proprietary “requirements”).

Steps to Making an OSA

Numerous actions needed to produce an OSA are explained listed below.

  • Action 1: Choose how to modularize the system. The primary OSA modularization method generally decays the system into independently procurable architectural elements to support competitors, reduce supplier lock, and make it possible for innovation refresh. This method is utilized to recognize the essential architectural elements of the system that ought to be open, while the other parts possibly might be closed or partly open. The user interfaces of these essential elements are then specified as the essential user interfaces that ought to comply with open user interface requirements.
  • Action 2: Figure out the associated open user interface requirements to utilize for essential user interfaces. When should a user interface be determined as a essential user interface and, for that reason, when should that user interface be open? The response is truly a matter of cost-benefit analysis. While there are plainly advantages to being open, there are likewise associated expenses and difficulties. Mandating making use of an open user interface requirement might require the replacement of an existing closed (e.g., proprietary) user interface, training the designers to utilize the brand-new user interface requirement, and decreased designer efficiency till the brand-new user interface requirement is mastered.
  • Action 3: Confirm conformance to the open user interface requirements. As pointed out previously, an open user interface needs to be confirmed (through screening or fixed analysis) to adhere, both syntactically and semantically, to the associated open user interface requirement. It is likewise crucial to file and validate any implementation-defined parts of the requirement.

In theory and if all things were equivalent, it would be excellent if all architectural elements were modular and open. In practice, nevertheless, all things are not equivalent and other quality characteristics (such as reliability, efficiency, toughness, security, and security) might be more crucial than openness alone for some architectural elements. Completely excellent factors might for that reason exist for why these elements ought to not be open or at many partly open. For instance, complying with a particular open user interface requirement might reduce system efficiency or have unfavorable security implications. To put it simply, when crafting a system architecture, the designers should weigh completing requirements (particularly the non-functional quality characteristics) versus each other, and openness is just one such requirement to think about when making engineering and service compromises.

In summary, designers of OSA-based options ought to bypass openness in those parts of the system and software application architecture where the list below conditions hold:

  1. There are no strong factors to make the architectural part independently procurable. For instance, there is presently just a single supplier certified, or the expenses of transitioning far from a sole-source agreement would be extreme or unaffordable provided present or visualized financing levels. Keep in mind that program supervisors and designers require to understand that short-term and long-lasting cost might be rather various, which an over-emphasis on short-term cost might be a case of “cent smart and pound silly.”
  2. There are bypassing factors to breach modularity or to modularize in a manner that decreases competitors. For instance, the existing badly modularized architecture would cost excessive or take too long to re-architect.
  3. There are bypassing factors to utilize fairly closed user interface requirements, to utilize exclusive requirements, or to utilize no requirement at all. For instance, no open user interface basic exists, the open user interface requirements lead to insufficient quality (e.g., efficiency, toughness, security, or security), the open user interfaces requirements are too immature or not adequately defined, or the expense of changing an existing proprietary user interface surpasses the expected expense savings from making the user interface more open.

When choices are made to utilize closed or fairly unopen architectures, it is essential to record the associated reasonings and reasons. This documents is indispensable when compromises and options concerning openness needs to be reviewed (e.g., due to fast modifications in innovations and the focus on getting required abilities by incorporating independent systems into systems-of-systems).

Keep in mind that absolutely nothing in the above validates overlooking openness, and it must not be misused as a reason to craft a closed system architecture. Program workplaces ought to make sure that integrators supply appropriate reason for the fairly or totally closed parts of the system architecture which they are not preventing openness to prevent competitors and make sure supplier lock.


Although an OSA will probably lead to crucial advantages (particularly if openness is kept through the advancement and lifecycle), both DoD policy and excellent system/software architecture engineering acknowledge that a 100-percent open system architecture is generally unreachable. Additionally, openness needs to be weighed versus completing requirements to acquire the very best architectural service.

Extra Resources

To check out the SEI Post The Significance of Automated Screening in Open Systems Architecture Efforts, by Douglas C. Schmidt please click here

To check out the abstract and discussion products from the SATURN 2015 conversation Open Systems Architectures: Development and Obstacles, please click here

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