Home > Articles > Software Development & Management

Managing Software Debt: Executable Design

📄 Contents

  1. Principles of Executable Design
  2. Executable Design in Practice
  3. Summary
  • Print
  • + Share This
Executable Design is a method for driving the implementation of software functionality. Going beyond how we write automated tests, Executable Design also involves how they are structured inside projects, how they are executed in different environments, and a way to think about what the next test should be. Chris Sterling discusses the concepts behind Executable Design.
This chapter is from the book
  • If we are not enhancing the design then we are just writing a bunch of tests.
  • An anonymous developer in a meeting about a Test-First development implementation

Principles of Executable Design

Executable Design is an approach involving existing well-known practices, helpful principles, and a mind-set shift from traditional views on software design. There have been many projects, conversations, and mistakes involved in defining Executable Design as described in this chapter. There is always room for improvement and perspective. Please take what you can from this chapter and apply it to your own context. In fact, this is an essential principle of Executable Design:

  • The way we design can always be improved.

This particular principle is not all that controversial. There is a continuous flow of writing about design methods and ideas in our industry. It does, however, suggest the notion that following a single design method is not recommended. By trying multiple methods of design, teams continue to learn and innovate for the sake of their applications.

People in our industry strive for the "best" design methods for software. This has led to many innovations that are in common use today, such as UML and Inversion of Control. In the development of these design methods many ideas were considered and changes were made along the way. In application development, teams also consider ideas and make changes based on their current understanding of the application's design. It is easy sometimes to choose an architectural design style such as Model-View-Controller (MVC), peer-to-peer, and service-oriented. But when these architectural design styles are put into practice to implement a solution of any size, many decisions must be made about specifics in the design. This has led to the following principle of Executable Design:

  • We will not get it "right" the first time.

This has been shown to be true in my career in the following situations:

  • Abstracting web design from application behavior
  • Creating a text formatting library for portable devices
  • Using model-driven development on a project

Although we will not usually get the design "right" on the first attempt, the design does tend to settle out for most applications. It has come to my attention over the years that

  • We're more likely to get it "right" the third time.

I am positive that it is not always the third time, but that is not the point of this statement at all. The point is for team members to construct software so that changes can be incorporated at any point in time. If we accept that we're more likely to get the design "right" closer to the third attempt, we will build software to support change. This gets us to our next principle of Executable Design:

  • Design and construct for change rather than longevity.

If software is designed and constructed for change, it will be technically and economically feasible to change the software for new needs rather than rewriting it. Designing and constructing with such discipline that changes are easily supported at any time is quite difficult. It takes tremendous discipline when patterns of technical debt, such as schedule pressure as discussed in Chapter 2, are introduced to a team. It is my opinion that we cannot rely on disciplined design over a long period of time by every team member. Therefore, our last principle of Executable Design is

  • Lower the threshold of pain.

At a workshop in Grand Rapids, Michigan, on technical debt, Matt Heusser proposed that technical debt could be an outcome of individual developers not having to deal with the consequences of their actions. The decisions that we make each day in developing software lead to technical debt because of a "moral hazard."

  • Moral hazard is the view that parties insulated from risk may behave differently from the way they would behave if they were fully exposed to the risk.

This does not mean that team members act in a malicious or dishonest way. It means that if individual team members are insulated from the long-term effects of a decision, they will not take as much care in the short term. Matt's example was that a person may take a shortcut in developing a feature because that person is not going to be working on the code one year from now when it must be changed to support a new feature.

Immediately following Matt's discussion on moral hazard, Chet Hendrickson pointed out that a good way to minimize the moral hazard problem is by "lowering the threshold of pain." For instance, Chet brought up how many people approach doing their taxes in the United States. They could incrementally update their tax information for two hours each month. Instead, many of us wait until two weeks prior to the deadline to complete our tax forms. We push to complete our taxes by the deadline because the potential headache of tax evasion is strong enough that a pain threshold would be crossed.

Teams can agree to a threshold of pain they are willing to tolerate and put in feedback mechanisms to let them know when that threshold is crossed. In XP, there are multiple frequencies of feedback provided. Pair programming enables team members to provide feedback within seconds. Test-Driven Development (TDD) and acceptance testing provide feedback within minutes of the changes. By using continuous integration teams are provided feedback within tens of minutes on how all of their code works together. Having an on-site customer representative in close proximity can support getting feedback on an implementation detail within hours of starting work on it. Teams working in time-boxed iterations get feedback from stakeholders within weeks. Getting feedback as close to when an action has been taken is critical to the evolutionary nature of software development using XP.

Identifying a threshold for providing feedback to the team is also a critical aspect of Executable Design. Automating the feedback, when possible, enforces the team's threshold. The feedback could be automated in each team member's development environment, the continuous integration server, and promotion of software to servers exposed to stakeholders.

On some legacy development platforms there could be costs that make frequent feedback difficult or even seemingly impractical. Teams should work toward the shortest frequency of feedback at all levels of the software development process that is practical and feasible in their context. The frequency of feedback that a team can attain is probably more than initially thought.

To recap the principles that drive Executable Design:

  • The way we design can always be improved.
  • We'll get it "right" the third time.
  • We will not get it "right" the first time.
  • Design and construct for change rather than longevity.
  • Lower the threshold of pain.

Taking on the Executable Design mind-set is not easy. I continually use these principles in design discussions for products, technology, code, tests, business models, management, and life. It has been helpful for me to reflect on situations where these principles have caused me to change my position or perspective. From these reflections I have found more success in setting proper expectations, learning from others in the design process, and designing better solutions for the situation.

Teams can tailor their practices and tools and still be in alignment with the Executable Design principles. The rest of this chapter will provide a set of suggestions about practices and tools to support an Executable Design approach. By no means are these suggestions the only ways to apply the principles or the only ways that I have seen them applied. These suggestions are only examples to help clarify their application to the software development process. If they work for your current context, your team has a place to start. But please do not stop once you apply them successfully. Remember the first principle:

  • The way we design can always be improved.
  • + Share This
  • 🔖 Save To Your Account

InformIT Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from InformIT and its family of brands. I can unsubscribe at any time.

Overview


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information


To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.

Surveys

Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites, develop new products and services, conduct educational research and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.

Newsletters

If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information


Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.

Security


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.

Children


This site is not directed to children under the age of 13.

Marketing


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information


If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.

Choice/Opt-out


Users can always make an informed choice as to whether they should proceed with certain services offered by InformIT. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.informit.com/u.aspx.

Sale of Personal Information


Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents


California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure


Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.

Links


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact


Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice


We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020