Rapido: A Sketching Tool for Web API Designers

Ronnie Mitra Director of API Design

CA Technologies ronnie.mitra@gmail.com

ABSTRACT Well-designed Web APIs must provide high levels of usability and must “get it right” on the first release. One strategy for accomplishing this feat is to identify usability issues early in the design process before a public release.

Sketching is a useful way of improving the user experience early in the design phase. Designers can create many sketches and learn from them.

The Rapido tool is designed to automate the Web API sketching process and help designers improve usability in an iterative fashion.

Keywords API, design, sketching, REST, Web API, usability

1. INTRODUCTION Over the years, a number of books, papers and talks have been published to provide design guidance for Web API Designers.

The expert advice in this domain often highlights three important characteristics for well-designed APIs:

APIs should provide ‘just enough’ functionality to meet user requirements

APIs should follow a user-centered design approach APIs should not break existing applications

This advice presents an interesting challenge for the modern API designer. They must create interfaces that provide good user experiences within the constraint of limiting breaking changes.

Joshua Bloch illustrates this challenge in one of his maxims for good design: “Public APIs, like diamonds, are forever. You have one chance to get it right so give it your best.” [1]

This paper introduces sketching as a method for improving API user experiences in the design phase, before implementation. It also introduces a tool called Rapido that has been created to facilitate the act of sketching web APIs.

2. SKETCHING An implicit but important part of many design processes is the sketching phase. Sketching has been proposed as a formal component of many design processes including interaction design [2], mechanical design [3] and engineering[4].

In broad terms, a sketch is a form of design that includes relatively less detail than a formal design. Sketches carry connotations of being formed quickly and effortlessly.

Copyright is held by the International World Wide Web Conference Committee (IW3C2). IW3C2 reserves the right to provide a hyperlink to the author's site if the Material is used in electronic media. WWW 2015 Companion, May 18–22, 2015, Florence, Italy. ACM 978-1-4503-3473-0/15/05. http://dx.doi.org/10.1145/2740908.2743040

They often capture abstract thoughts from a designer’s mind and can be used to record experimentation with new ideas that might otherwise be forgotten.

In his book “Sketching User Experiences”, Bill Buxton highlights the importance of sketching in all design processes and identifies that sketching is central to design thinking and learning[5]. Buxton also explains how sketches can be used to improve the user experience within an interaction design context by allowing designers to produce many experimental concepts that are iteratively refined in pursuit of the best final concept.

For the Web API designer, sketching offers a method to achieve rapid design iterations at the beginning of a design process. By creating a sketch, reviewing it and applying the lessons learned to a new sketch a designer can identify and solve usability problems in the early phases of design.

When incorporated into a design process that includes user testing and prototype development, the designer can improve the odds that the overall user experience will be improved.

There are many ways to produce sketches, but we will focus on four popular sketching methods and discuss the benefits and limitations of each.

2.1 Drawing A simple and accessible method for sketching is to put pencil to paper, marker to whiteboard or digital pen to canvas.

Drawing can be a powerful way of representing the memories or abstractions of the human mind. While the quality level of a drawing may differ depending on the artist’s level of artistic skill, the use of a drawing to communicate an idea is as central to the human experience as spoken language[6].

2.1.1 Benefits One of the great advantages to drawing a sketch is the ease with which one can start.

Almost every designer should be capable of effortlessly creating a doodle. This simple act doesn’t require strenuous thought regarding the process of drawing. But, these rough sketches can provide a sufficient level detail to capture the important aspects of an early phase design regardless of their aesthetic appeal.

The human proficiency for drawing simple images and the speed at which a low fidelity drawing can be rendered makes it easy for the sketch artist to draw many sketches in a short time, disposing of sketches as they go.

For example, a designer considering a CRUD API might initially draw the low fidelity sketch depicted in figure 1 using simple boxes and lines.

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3.7 Benefits The main strength of the Rapido tool is that it combines the holistic, low-fidelity, visual properties of the drawing method with the higher-fidelity literal properties of the writing method.

The visual nature of the sketching canvas also affords designers the ability to “play” with their designs, experimenting with different types of transitions and relationships.

Finally, the lack of support for dynamic responses, logical flows and message header detail may discourage designers from investing too much time in the sketch resulting in improved levels of disposability.

3.8 Limitations While the low-fidelity of the Rapido tool helps designers create many disposable sketches, it prevents them from capturing important detailed characteristics of their APIs such as security controls, error handling and logical behavior.

Another challenge is that the focus on specialized support for CRUD conventions and hypermedia formats hinders broader experimentation. For example, it is difficult to use Rapido to design a new hypermedia media type or a new message format.

In addition, the current set of media types and service description formats is limited. This limits the usefulness of the tool to communities of users who use these particular formats. Hopefully in the future additional media types and formats will be supported.

Finally, many of the design decisions made for the Rapido tools are based on assumptions and hypothesis about user behaviour. In practice, the sketching needs of API designers may not be accurately reflected in the interaction design of the tool.

4. CONCLUSION API designers who are interested in producing high quality interfaces should consider incorporating a sketching method into their design process.

While there are many different ways to sketch an API, the Rapido tool attempts to consolidate the benefits from the most popular methods to provide a sketching process with good disposability, experimentability, socializability and learnability.

By unbundling the sketching experience from the design, prototype and implementation experience Rapido attempts to provide a higher quality sketching experience for designers.

5. REFERENCES [1] Joshua Bloch. 2006. How to design a good API and why it

matters. In Companion to the 21st ACM SIGPLAN symposium on Object-oriented programming systems, languages, and applications (OOPSLA '06). ACM, New York, NY, USA, 506-507. DOI=10.1145/1176617.1176622 http://doi.acm.org/10.1145/1176617.1176622

[2] Bill Verplank. 2009. Interaction Design Sketchbook.

[3] David G. Ullman, Stephen Wood, David Craig. The importance of drawing in the mechanical design process. Computers & Graphics 14, 2 (1990), 263--274.

[4] Drawing Gym, Teaching Engineers to Draw.: http://www.ucl.ac.uk/drawing-gym/. Accessed: March 9th, 2015

[5] Bill Buxton. 2007. Sketching User Experiences: Getting the Design Right and the Right Design. Morgan Kaufmann Publishers Inc., San Francisco, CA, USA.

[6] Neil Cohn. 2012. Explaining ‘I Can’t Draw’: Parallels between the Structure and Development of Language and Drawing.

[7] Marian Petre. 2013. UML in practice. In Proceedings of the 2013 International Conference on Software Engineering (ICSE '13). IEEE Press, Piscataway, NJ, USA, 722-731.

[8] Ole Lensmar. An Overview of REST Metadata Formats: http://apiux.com/2013/04/09/rest-metadata-formats/. Accessed: March 8th, 2015.

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[10] The Object Constraint Language: Precise Modeling With Uml (Addison-Wesley Object Technology Series) (13 October 1998) by Jos B. Warmer, Anneke G. Kleppe

[11] Ronnie Mitra, Rapido: http://www.rapidodesigner.com

[12] Apiary. http://apiary.io/. Accessed: March 9th, 2015

[13] I. Zuzak, I. Budiselic, and G. Delac. 2011. A FINITE-STATE MACHINE APPROACH FOR MODELING AND ANALYZING RESTFUL SYSTEMS.

[14] M. Amundsen, L. Richardson. 2012. RESTFul Web APIs. O’Reilly Media.

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