javascript client libraries for the (former) long tail of ogc standards
DESCRIPTION
Presented at FOSS4-G Europe 2014, Bremen Authors: Daniel Nüst ([email protected], 52°North GmbH) Matthes Rieke ([email protected], 52°North GmbH) Paul Breen ([email protected], British Antarctic Survey) More and more information technology is moving into a cloud-based infrastructures for both data storage as well as user interfaces and leverages browser technologies, i.e. Javascript and HTML5, also for mobile devices. Users always use the latest version and the environment is well controlled: an internet browser. General purpose libraries (e.g. jQuery) and web-application frameworks (e.g. AngularJS) facilitate the development of complex applications. In the geospatial domain such frameworks and libraries are combined with mapping libraries, such as OpenLayers (OL) or Leaflet, and visualisation libraries to build complex applications. These applications display geospatial data coming from standardized view and feature services, most importantly the Open Geospatial Consortium’s (OGC) Web Map Service (WMS) and Web Features Service (WFS). Both server and client libraries are mature and have reached a very stable level and wide distribution. What is missing today are generic libraries that operate at the same level of performance and quality to (i) access observation and time series data coming from OGC Sensor Observation Services (SOS), and (ii) control online geoprocesses published as an OGC Web Processing Service (WPS). These standards are less widespread than W(M,F)S but gain momentum as data volumes increase, for example with a myriad of smart sensors in the internet of things or new EO satellite missions, and subsequent requirements for sophisticated architectures for processing and management of time series data. Observing these developments lead to the birth of two new open source Javascript library projects that are presented in this talk. SOS.js (https://github.com/52North/sos-js) can access SOS data and be used for sophisticated lightweight browser applications for discovering and displaying time series data as plots, tables, and maps. wps-js (https://github.com/52North/wps-js/) is a client library for the WPS generating forms based on the standardized metadata from the service and interactively creating and submitting processing tasks. During the talk we demonstrate applications build with the libraries and share experiences from development. A goal for both libraries is to become independent of OL for request and response encoding and provide service access with a minimal footprint. We see an advantage of developing such small and focussed libraries maintained by field experts in these non-mainstream domains. We’ll happily discuss if this is the best approach and pose the following question: Is there a (technical, organisational) way to build a compatible Javascript client frameworks across all geo-service standards?TRANSCRIPT
JavaScript Client Libraries for the (Former) Long Tail of OGC Standards
FOSS4G-Europe, Bremen, July 2014
Daniel Nüst (52°North GmbH), Matthes Rieke (52N), Paul Breen (BAS)
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http://commons.wikimedia.org/wiki/File:Long_tail.svg
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2014JavaScript is on the rise (node, JS engines)
Cloud
jQuery
AngularJS, Dojo, ExtJS, …
OpenLayers, Leaflet, GeoExt, …
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Motivation
Create generic client libraries because…
applications move to the browser,WPS and SOS reach(ed) 2nd version,need to build apps, and
we don’t want to repeat ourselves.
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SOS.JS AND WPS-JSComing up: new project introduction and demonstration
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WPS-JS
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About wps-js
JavaScript WPS Client to build interactive forms to control standardized processes.
Build on: OpenLayers (requests, XML)
GitHub: https://github.com/52North/wps-js
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htt
ps:
//w
ww
.ohlo
h.n
et/
p/w
ps-
js
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OGC WPS“Geo-ready” web processing standard
GetCapabilitiesDescribeProcessExecute
WPS-G, WPS-T
More: http://www.ogcnetwork.net/wps
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wps-js FeaturesForm generation based on process descriptions
WPS 1.0.0
Interactive execution of processes
Pre-configuration of UI/form
Style-free
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Demo
http://nuest.github.io/wps-js/http://geostatistics.demo.52north.org/wps/client.htmlhttp://geoviqua.dev.52north.org/wps-js-client/
Simple calculatorTable output
Data intercomparison and colocation(pre-configuration)
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http://geoviqua.dev.52north.org/wps-js-client/demo/geca-intercomparison/client.html?
source=Testlink&_pdPortlet_WAR_geoportal_uuid=067a17f9-8d37-4d15-b405-
25e701dd03b0&_pdPortlet_WAR_geoportal_uuid=31172be3-01ae-4d4d-b500-
8e734a1d5432&hide=false
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SOS.JS
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About SOS.jsJavascript library to browse, visualise, and access, data from an OGC Sensor Observation Service.
Basis: OpenLayers
GitHub: https://github.com/52North/sos-js
History…
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htt
ps:
//w
ww
.ohlo
h.n
et/
p/s
os-
js
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Live Demos
http://basmet.nerc-bas.ac.uk/sos/http://52north.github.io/sos-js/http://sensors.geonovum.nl/sos-js-test/sos-app-test.html
[integrated in 52°North SOS]
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ExperiencesShortest path to beta (OL)
Raw time series data can be handled in JSXML is possible, of course JSON is simpler…
Hard to reach “completeness” when driven by projects
Be aware of CORS when you deploy services
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GoalsUseful and usable libraries for application developers (not SWE/processing experts)
Facilitate usage of WPS and SOS
Minimal footprintFlexible use (domain applications)
User-friendly interfaces
Non-copyleft licenses
Be used by OpenLayers
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Steps1) Become independent…
from mapping librariesfrom specific frameworksmodularizerelease version 1.0
2) Extend developer/user community
3) Ease usage (plugins for JS libs/JS mapping)
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Challenges
“lib-independent library”
JavaScript modularization
Coordination and community building
Testing and service compatibility
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@FiveTwoN
http://blog.52north.org/
52north.org/communities/
Is there a (technical, organisational) way to build a compatible JavaScript OGC client across all standards?