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Earlier this year, the Association for Computing Machinery (ACM) in its January 2019 issue of Communication Design Quarterly (CDQ), talked about how developers use API documentation when getting into a new API and also suggested a few guidelines for writing effective API documentation.

Application Programming Interfaces (APIs) are standardized and documented interfaces that allow applications to communicate with each other, without having to know how they are implemented. Developers often turn to API references, tutorials, example projects, and other resources to understand how to use them in their projects. To support the learning process effectively and write optimized API documentation, this study tried to answer the following questions:

  • Which information resources offered by the API documentation developers use and to what extent?
  • What approaches developers take when they start working with a new API?
  • What aspects of the content hinders efficient task completion?

API documentation and content categories used in the study

The study was done on 12 developers (11 male and 1 female), who were asked to solve a set of pre-defined tasks using an unfamiliar public API. To solve these tasks, they were allowed to refer to only the documentation published by the API provider.

The participants used the API documentation about 49% of the time while solving the task. On an individual level, there was not much variation, with the means for all but two participants ranging between 41% and 56%. The most used content category was API reference, followed by the Recipes page. The aggregate time spent on both Recipes and Samples categories was almost equal to the time spent on the API reference category. The Concepts page, however, was used less often as compared to the API reference.


Source: ACM

These findings show that the API reference is an important source of information, not only to solve specific programming issues when working with an API developers already have some experience with, but even in the initial stages of getting into a new API, in line with Meng et al. (2018),” the study concludes.

How do developers learn a new API

The researchers observed two different problem-solving behaviors that were very similar to the opportunistic and systematic developer personas discussed by Clarke (2007).

Developers with the opportunistic approach tried to solve the problem in an “exploratory fashion”. They were more intuitive, open to making errors, and often tried solutions without double-checking in the documentation. This group was the one who does not invest much time to get a general overview of the API before starting with the first task. Developers from this group prefer fast and direct access to information instead of large sections of the documentation.

On the contrary, developers with the systematic approach tried to first get a deeper understanding of the API before using it. They took some time to explore the API and prepare the development environment before starting with the first task. This group of developers attempted to follow the proposed processes and suggestions closely. They were also able to notice parts of the documentation that were not directly relevant to the given task.

What aspects of API documentation make it hard for developers to complete tasks efficiently?

Lack of transparent navigation and search function

Some participants felt that the API documentation lacked a consistent system of navigation aids and did not offer side navigation including within-page links. Developers often required a search function when they were missing a particular piece of information, such as a term they did not know. As the documentation used in the test did not offer a search field, developers had to use a simple page search instead, which was often unsuccessful.

Issues with high-level structuring of API documentation

The participants observed several problems in the high-level structuring of the API documentation, that is, the split of information in Concepts, Samples, API reference, and so on. For instance, to search for a particular piece of information, participants sometimes found it difficult to decide which content category to select. It was particularly unclear how the content provided in the Samples and Recipes were distinct.

Unable to reuse code examples

Most of the time participants developed their solution using the sample code provided in the documentation. However, the efficient use of sample code was hindered because of the presence of placeholders in the code referencing some other code example.

Few guidelines for writing efficient API documentation

  • Organizing the content according to API functionality: The API documentation should be divided into categories that reflect the functionality or content domain of the API. So participants would have found it more convenient if instead of dividing documentation into “Samples,” “Concepts,” “API reference” and “Recipes,” the API used categories such as “Shipment Handling,” “Address Handling” and so on.
  • Enabling efficient access to relevant content: While designing API documentation, it is important to take specific measures for improved accessibility to content that is relevant to the task at hand. This can be done by organizing the content according to API functionality, presenting conceptual information integrated with related tasks, and providing transparent navigation and powerful search function.
  • Facilitating initial entry into the API: For this, you need to identify appropriate entry points into the API and relate particular tasks to specific API elements. Provide clean and working code examples, provide relevant background knowledge, and connect concepts to code.
  • Supporting different development strategies: While creating the API documentation, you should also keep in mind the different strategies that developers adopt when approaching a new API. Both the content and the way it is presented should serve the needs of both opportunistic and systematic developers.

These were some observations and implications from the study. To know more, read the paper: How Developers Use API Documentation: An Observation Study.

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