2014 WVAGP GIS Conference, Charleston, WV 1

Online real-time tweets extraction, mapping and dissemination

Xiannian Chen and Gregory ElmesWest Virginia University

Chen & Elmes @ West Virginia University

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Geospatial data• Challenges that geospatial data face

• Traditional geospatial data updates are slow.• The real-time data is critical in disaster management.

• Crowdsourcing (Jeff Howe 2005, Brabham 2008)• VGI (Volunteered Geographic Information, Goodchild 2007)

• Real time geographic information from volunteers• “geographic information acquired and made available to others

through the voluntary activity of individuals or groups, with the intent of providing information about the geographic world” (Elwood, Goodchild, and Sui 2011)

Chen & Elmes @ West Virginia University

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Values of VGI• Captures of real time changes• Quick dissemination• A significant data source.• Individuals’ understandings of a local event• Rich in context

Chen & Elmes @ West Virginia University

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API and REST• Application Programming Interface

• A library that may include specification for routines, data structures, object classes, and variables

• An interface for software components to communicate• All social media websites provide API

• REST (REpresentational State Transfer, Fielding 2000)• A HTTP-based style to describe the resources it represents.• uses HTTP for all four CRUD (Create/Read/Update/Delete)• The access of REST services is a simple URL

Chen & Elmes @ West Virginia University

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Twitter and Tweets• Twitter: a real-time information network• Tweets

• created_at• coordinates• favorite_count, retweet_count• id• place• text• user• more information:

https://dev.twitter.com/docs/platform-objects/tweets

Chen & Elmes @ West Virginia University

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Twitter Search API• Twitter provides REST API to access tweets

• The resources are represented in RESTful style, which mean, in theory, users can get tweets by typing the URL with right parameters.

• Tweets, especially geo-tagged tweets• A sample URL for query:

• https://api.twitter.com/1.1/search/tweets.json?q=shooting&geocode=41.148693,-81.346292,100km&result_type=recent&until=2014-05-30&since=2014-05-29&count=100

Chen & Elmes @ West Virginia University

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Major query parameters• q – the search keywords• geocode – location with radius. Format: lat, long, 50mi.• since, until – the search time frame. Format: yyyy-mm-dd• count – the number of tweet in a query. <100• result_type – types of search results preferred to receive

• mixed: Include both popular and real time results in the response.• recent: return only the most recent results in the response.• popular: return only the most popular results in the response.

• more information: https://dev.twitter.com/docs/api/1.1/get/search/tweets

Chen & Elmes @ West Virginia University

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Authorization• Required in Twitter API v1.1.• Response of un-authorized request.

• {"errors":[{"message":"Bad Authentication data","code":215}]}• Using Twitter website to generate the authorization code

• API key• API secret• Access token• Access token secret

• Use and activate authorization through server-side programming technologies, e.g. PHP, Python.

Chen & Elmes @ West Virginia University

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System architecture for live VGI saving

Chen & Elmes @ West Virginia University

Serverfor Tweets

Client Application

Web Server

Server-GIS Application

Server

Geodatabase Server

Map Server

Tweet collection

Tweet storing

Live data saving Live mapping

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Implementation of live data saving

Chen & Elmes @ West Virginia University

ArcGIS Server

FeatureServer Service

RESTful map service

Tweets(FeatureClass

Field: KeywordField: LocationField: Message:::

Geodatabase

ArcGIS Desktop

Tweets(GIS Layer)

Symbologybased on keyword Web GIS platform

ArcGIS JavaScript API

Load(ArcSDE)

Publish(ArcGIS Server)

Write(ArcGIS JavaScript API)

Tweets

Twitter Search API

Geo-tagged Tweets

Geo Filter

Collect(Twitter API, PHP)

Filter(JavaScript)

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A live demo• http://157.182.212.204/tweets

Chen & Elmes @ West Virginia University

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Issues• Quality• Accuracy• Uncertainty• Credibility• Heterogeneities• Liability• Privacy• Confidentiality

Chen & Elmes @ West Virginia University

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Thanks and questions