coverage-rest-client

DEPRECATED! Some of the functionality of this library has been integrated natively within the CoverageJSON format (tiling support). The rest is too experimental and will not be developed further here.

An experimental library that wraps Coverage or Coverage Collection objects and runs operations like subsetting through a REST API that follows the "Coverage Data REST API Core Specification" instead of loading the complete data and doing it locally.

Usage

coverage-rest-client can be used in browsers only.

Standalone minified and source versions can be found in the releases section. The library can also be used within npm, currently as a GitHub dependency only due to its experimental character.

As an example, we use the covjson-reader library to load a CoverageJSON document which then is wrapped with the coverage-rest-client library in order to support pagination and run operations like subsetting or collection filtering server-side:

<script src="https://cdn.jsdelivr.net/covjson-reader/0.7/covjson-reader.min.js"></script>
<script src="coverage-rest-client.min.js"></script>
<script>
var url = 'http://example.com/temperature.covjson'
CovJSON.read(url).then(function (cov) {
  return CoverageREST.wrap(cov, {loader: CovJSON.read})
}).then(function (cov) {
  // work with REST-enabled coverage data object
}).catch(function (e) {
  // there was an error when loading the coverage data
  console.log(e)
})

How it works

The magic is in the currently experimental .ld (as in linked data) property of a coverage data object. This property is a JSON-LD document and can contain API metadata which this library then may understand. Currently it has support for most of the techniques described in the "Coverage Data REST API Core Specification".

For the interested ones: All HTTP Link headers (which may be used for pagination) are generically transformed and copied into the JSON-LD object by the covjson-reader library. The transformation is simply to prefix registered relations with http://www.iana.org/assignments/relation/ and treat the Link header as an RDF triple. By doing this, there is a uniform way to handle API control data both in HTTP headers and embedded in the coverage data document itself.

Note that this library currently supports arbitrary JSON-LD and uses the jsonld.js parser which is not that lightweight in terms of file size. It may be the case that in the future a JSON-LD profile for such coverage-related REST API control data is created which would force a specific JSON-LD structure and allow easier processing without a full JSON-LD parser.

Acknowledgments

This library is developed within the MELODIES project.