Home > Articles > Software Development & Management > Architecture and Design

An Interview with Paul Clements on Documenting Software Architectures

  • Print
  • + Share This
John Morley interviews Paul Clements about why he wrote Documenting Software Architectures: Views and Beyond, Second Edition. Paul explains why we need to be able to document an architecture so that others can successfully use it, maintain it, and build a system from it.
Like this article? We recommend

John Morley: Why did you create a second edition?

Paul Clements: We thought that the message of the first edition was really strong, but that it was becoming technologically outdated. For example, in the first edition we relied on an outdated version of the Unified Modeling Language (UML) to make many points. We tried very hard to make the book notation-independent but not notation-free. Since UML is the de facto standard for architecture documentation, we needed to have an edition available that uses the current version of UML. But there were many other things we added and updated as well.

John: What else is new in this edition?

Paul: We introduced several architectural styles into the book that have come into widespread use since the first edition, especially service-oriented architectures. We also treat the architecture-level documentation of a software system’s data model. We also cover aspect orientation, and the system’s installation and production environments as architectural styles.

We’ve added a new chapter about reviewing an architecture document to make sure it’s serving its stakeholders as intended.

This edition is much more Agile-friendly, orienting its advice to be consistent with the Agile Manifesto’s entreaty to value working software over comprehensive documentation. We talk about using new ways to capture architecture, from wikis to whiteboards.

We added three appendices about languages for architecture: UML, SysML (Systems Modeling Language), and AADL (the Architecture Analysis and Design Language). These appendices form mini reference guides from an architectural perspective.

Years of use and feedback led us to make several improvements in the suggested templates for architecture documentation. The templates are also more flexible, and we lay out different options for arranging documentation. And we have a whole new section on documenting the rationale behind architectural decisions.

We updated the comprehensive example of a documented architecture. It will resonate with more people; it’s a web-based, service-oriented system, more in today’s industrial mainstream. To make the book smaller and allow us to maintain the example over time, we put it online.

And, as I mentioned, since the first edition was published, the UML has graduated to version 2.0 and beyond. That opened up new possibilities for more documenting various architecture constructs in a more straightforward way, especially components and connectors. Where necessary, our figures are updated to reflect the new constructs.

John: What is the significance of the bird’s wing on the cover of this book?

Paul: When people talk about architecture, they typically use a metaphor of building architecture, rooms and hallways. I think physiological systems are a much better metaphor for systems and software architectures. Buildings certainly have architectures, but buildings, for the most part, just sit there and don’t do anything. In a bird’s wing, there are bone structures, nerve structures, circulatory structures, and so on. Feathers are replicated complex substructures, but no two are exactly alike. You build a lot of systems that way. What’s fantastic about a bird’s wing is that when you put all those structures together you get astonishing behavior with incredible quality attributes.

John: In the book’s preface, you write that the purpose of the book is to answer the question, "How do you document an architecture so that others can successfully use it, maintain it, and build a system from it?" Why is that important?

Paul: There’s a quote from Thucydides that goes something like this: If you have a good idea, but you don’t have the facility to express it, you might as well not have had it. An uncommunicated architecture is a useless architecture. You might as well have not bothered, and had your architects sweep the halls or empty the trash. Communicating the architecture is the crowning achievement after creating it.

John: You also write that “we believe what an architect really needs is guidance in which architecture and its stakeholders are the first-class citizens, and language is relegated more appropriately to a supporting role. That’s what we’ve tried to provide with this book.” Why do you think that?

Paul: Language often constrains thought and influences the way we think about problems. We tried to write a book that was first about the things you want to express, and second about how to express those things in various available notations. In many cases, we say “Instead of creating a UML diagram, you might want to just make a table or write an ordered list.”

What do you want to say about an architecture, so that other people can use it? You want to talk about architectural elements, the relationships among elements, the properties of elements, the behavior of elements in concert with one another, and the interfaces the elements provide in order to interact with one another. All of those are first-class citizens in documentation.

Once you know the important stuff to say, then you can talk about how to express it in the notation of your choice. There are a ton of books on UML, SysML, and others. We think those books take a more parochial view than we want to take.

John: If there could be just one thing you want people to know about this book, what would it be?

Paul: We made a conscious effort to make sure that a reader will never open the book and see just two pages of solid text. We tried to make the book visually appealing, and the layout of the book is crafted to do that.

We’ve put in over 200 figures and a couple of dozen tables. There are lots of illustrated examples of architecture diagrams in various notations. Here’s how you show a uses view, here’s how you show a service-oriented view, here’s how you show an install view, and so forth. Every page has something visual on it, such as notes in the margins to point people to more information, give definition of terms, and give quotes that provide context. At the very least on a page there is a bulleted list of important points. There isn’t a single page with just pure text.

For information on the software engineering course based on this book, please visit http://www.sei.cmu.edu/training/p33.cfm.

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