Reviewing Proposals for Standardizing Web Maps

The geospatial community has, for some time, recognized that there is a disconnect between maps on the web and the underlying technology upon which web maps build. On one hand, the web standards and web browsers do not properly consider the needs of web maps. On the other, web map implementations are typically JavaScript libraries that do not leverage the strengths of the web platform but instead work against it to achieve the desired interaction model. The geospatial community set out to address this by proposing a new markup language for maps and extensions to HTML.

Maps on the web today are not sufficiently accessible; people who use assistive technologies such as screen readers are often not able to access and understand information on a web map. Furthermore, web maps as they are available today have suboptimal performance in terms of loading time and responsiveness, which at best is a suboptimal user experience and at worst excludes access for users with very slow internet connections or low-end devices. These problems could potentially be solved by implementing features and capabilities related to maps in web browsers. However, this work suffers from lack of browser vendor participation, and so is not yet being considered for implementation.

In 2020, we reviewed the following documents through the lens of a would-be skeptical browser implementer and reported 20 issues with feedback and recommendations:

• MapML Explainer
• The HTML <map> Element proposal
• Map Markup Language
• Use Cases and Requirements for Standardizing Web Maps

We found that the explainer and the technical specifications had fundamental issues and may need significant changes, but the Use Cases and Requirements document is very much on the right track.

We outlined recommendations for a process for standardizing web maps to increase the likelihood of success: 1) get the different parties to agree to the use cases and requirements; 2) make sure the right expertise is involved when designing solutions to maintain core aspects of the web platform, such as web compatibility, security, and accessibility; and 3) evaluate how well the proposed solution meets the use cases and compare with other existing solutions.

When designing solutions, we suggest following the Extensible Web Manifesto: first standardize the underlying low-level capabilities that explain the high-level feature, and then specify the high-level feature in terms of those low-level capabilities to allow for JavaScript libraries to iterate on the design.

We identified two missing primitives on the web platform that we think are fundamental to web maps’ interaction model: panning and zooming. We reported an issue to the CSS WG to initiate a discussion.

We have asked browser vendors and HTML and CSS standards communities to review the use cases and requirements, and join the W3C/OGC Joint Workshop Series on Maps for the Web in September-October 2020, where we attended and gave a presentation.