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Software Documentation: Identifying Authoritative Knowledge

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When it comes to software documentation, we need to become our own curators, working on all the knowledge that is already there to turn it into something meaningful and useful. This chapter demonstrates how to start turning knowledge into something useful through curation, while embracing that this knowledge is continuously changing.

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This chapter is from the book

Remember that most of the knowledge related to a system is already there in that system—and there is a lot of it. One crucial way to exploit all that knowledge is through curation. The idea of curation is to select the few relevant bits of knowledge out of the ocean of data in the system, in order to help people working on it in their future work assignments. Because this system is always changing, it is safest to ensure that this curation evolves naturally, without any manual maintenance.

Dynamic Curation

In art exhibitions, the curator is as important as the director in a movie. In contemporary art, the curator selects and often interprets works of art. For example, the curator searches for prior work and places that inspired the artist, and he or she proposes a narrative or a structured analysis that links the selected works together in a way that transcends each individual piece. When a work that is essential for the exhibition is not in the collection, the curator will borrow it from another museum or from a private collection or may even commission the artist to create it. In addition to selecting works, the curator is responsible for writing labels and catalog essays and overseeing the scenography of the exhibition to help convey the chosen messages.

When it comes to documentation, we need to become our own curators, working on all the knowledge that is already there to turn it into something meaningful and useful.

Curators select works of art based on many objective criteria, such as the artist name, the date and place of creation of the works, or the private collectors who first bought the works. They also rely on more subjective criteria, such as the relationships to art movements or to major events in history, such as wars or popular scandals. The curator needs metadata about each painting, sculpture, or video performance. When the metadata is missing, the curator has to create it, sometimes by doing research.

Curation is something that you already do, perhaps without being aware of it. For example, when you are asked to demo an application to a customer or to a top manager, you have to choose just a few use cases and screens to show in order to convey a message, such as “everything is under control” or “buy our product because it will help you do your job.” If you have no underlying message, it’s likely that your demo with be an unconvincing mess.

Unlike in art exhibitions, in software development what we need is more like a living exhibition with content that adjusts according to the latest changes. As the knowledge evolves over time, we need to automate the curation on the most important topics.

Therefore: Adopt the mindset of a curator to tell a meaningful story out of all the available knowledge in the source code and artifacts. Don’t select a fixed list of elements. Instead, rely on tags and other metadata in each artifact to dynamically select the cohesive subset of knowledge that is of interest for the long term. Augment the code when the necessary metadata is missing and add any missing pieces of knowledge when they are needed for the story.

Curation is the act of selecting relevant pieces out of a large collection to create a consistent narrative that tells a story. It’s like a remix or a mashup. Curation is key for knowledge work like software development. Source code is full of knowledge about many facets of the development, and different parts of it are of varying degrees of importance. On anything bigger than a toy application, extracting knowledge from the source artifacts immediately overflows our regular cognitive capabilities with too many details, and the knowledge becomes meaningless and therefore useless (see Figure 5.1).


Figure 5.1 Too much information is as useless as no information

The solution is to aggressively filter the signal from the noise for a particular communication intent; as the little buffoon monster in Figure 5.1 says, “Too much information is as useless as no information.” What would be the noise from a particular perspective might be the signal from another perspective. For example, the method names are an unnecessary detail in an architecture diagram, but they might be important in a close-up diagram about how two classes interact, with one being an adapter to the other.

Curation as its core is the selection of pieces of knowledge to include or to ignore, according to a chosen editorial perspective. It’s a matter of scope. Dynamic curation goes one step further, with the ability to do the selection continuously on an ever-changing set of artifacts.

Examples of Dynamic Curation

A Twitter search is an example of automated dynamic curation, and it is a resource in itself that you can follow just as you would follow any Twitter handle. People on Twitter also do a manual form of curation when they retweet content they have (more or less) carefully selected according to their own editorial perspective (perhaps). A Google search is another example of simple automated curation.

As another example, selecting an up-to-date subset of artifacts based on a criterion is something we do every day when using an IDE:

  • Show every type with a name that ends with “DAO.”

  • Show every method that calls this method.

  • Show every class that references this class.

  • Show every class that references this annotation.

  • Show every type that is a subtype of this interface.

When a tag is missing to help select the pieces, you should introduce it with annotations, naming conventions, or any other means. When a piece of knowledge is missing, in order to show a complete picture, you need to add it in a just-in-time fashion.

Editorial Curation

Curation is an editorial act. Deciding on an editorial perspective is the essential step. There should be one and only one message at a time. A good message is a statement with a verb, like “No dependency is allowed from the domain model layer to the other layers” rather than just “Dependencies between layer,” where there is no message, and it’s up to the reader to guess what is meant. At a minimum, dynamic curation should be given an expressive name that reflects the intended message.

Low-Maintenance Dynamic Curation

Selecting subsets of knowledge can be hazardous if done in a rigid way. For example, a direct reference to a list of classes, tests, or scenarios will rapidly become obsolete and will require maintenance. It is a form of copy and paste, and it makes change more expensive; it also is subject to the risk of someone forgetting to update it. This is not a good practice, and it should be avoided at all cost.

You can describe the artifacts of interest in a stable way by using one of the stable selection criteria described here:

  • Folder organization: For example, “everything in the folder named ‘Return Policy’”

  • Naming conventions: For example, “every test with ‘Nominal’ in its name”

  • Tags or annotations: For example, “every scenario tagged as ‘WorkInProgress’”

  • Links registry over which you have control (which may need some maintenance from time to time, but at least it is in a central place): For example, “the URL registered under this shortlink”

  • Tool output: For example, “every file that has been processed by the compiler, as visible in its log”

When you use stable criteria, the work is done by tools that automatically extract the latest content that meets the criteria to insert it into the published output. Because it is fully automated, it can be run as often as possible—perhaps continuously on each build.

One Corpus of Knowledge for Multiple Uses

Everything can be curated—code, configuration, tests, business behavior scenarios, datasets, tools, data, and so on. All the knowledge available can be considered as a huge corpus, accessible via automated means for analysis and curated extractions.

Provided that the content of the knowledge corpus is adequately tagged, it is possible to extract by curation out of it a business view of a glossary (that is, a living glossary), a technical view of the architecture (that is, a living diagram), and any other perspective you can imagine, including the following:

  • Audience-specific content, such as business-readable content only versus technical details

  • Tasks-specific content, such as how to add one more currency

  • Purpose-specific content, such as an overview of content versus a references section

Curation is possible only to the extent that metadata about the source knowledge is available to enable relevant selection of material of interest.

Scenario Digests

Curation is not just about code; it’s also about tests and scenarios. A good example of dynamic curation is a scenario digest, in which the corpus of business scenarios is curated under various dimensions in order to publish reports tailored for particular audiences and purposes.

When a team makes use of BDD together with an automated tool such as Cucumber, a large number of scenarios are written in feature files. Not every scenario is equally interesting for everyone and for every purpose, so you need a way to do a dynamic curation of the scenarios, and for that you need to have the scenarios marked with a nicely designed system of tags. Remember from Chapter 2, “Behavior-Driven Development as an Example of Living Specifications,” that tags are documentation.

Each scenario can have tags like the following:

1  @acceptancecriteria @specs @returnpolicy @nominalcase
2  Scenario: Full reimbursement for return within 30 days
3  ...
5  @acceptancecriteria @specs @returnpolicy @nominalcase
6  Scenario: No reimbursement for return beyond 30 days
7  ...
9  @specs @returnpolicy @controversial
10 Scenario: No reimbursement for return with no proof of purchase
11  ...
13 @specs @returnpolicy @wip @negativecase
14 Scenario: Error for unknown return
15  ...

Note that almost all these tags are totally stable and intrinsic to the scenario they relate to. I say almost because @controversial and @wip (work in progress) are actually not meant to last too long, but they are convenient for a few days or weeks for easy reporting.

Thanks to all these tags, it is easy to extract only a subset of scenarios, by title only or complete with step-by-step descriptions. The following are some examples:

  • When meeting business experts who have very limited time, perhaps you could focus only on the information tagged @keyexample and @controversial:

    1 @keyexample or @controversial Scenarios:
    2 - Full reimbursement for return within 30 days
    3 - No reimbursement for return with no proof of purchase
  • When reporting to the sponsor about the progress, the @wip and @pending scenarios are probably more interesting for this audience, along with the proportion of @acceptancecriteria passing green:

    1 @wip, @pending or @controversial Scenarios:
    2 - Error for unknown return
  • When onboarding a new team member, going through the @nominalcase scenarios of each @specs section may be enough:

    1 @nominalcase Scenarios:
    2 - Full reimbursement for return within 30 days
    3 - No reimbursement for return beyond 30 days
  • Compliance officers want everything that is not @wip. However, even in that case, they might want to have the big document show a summary of the @acceptancecriteria first and the rest of the scenarios in addendum.

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