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Web Streams
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Web Streams

Data Velocity reached the Web shore. Indeed, the Web is already adding new protocols and APIs (e.g. WebSockets, and EventSource). The Web of Data is also evolving to tame Velocity without neglecting Variety. The RDF Stream Processing (RSP) community is actively addressing these challenges by proposing continuous query languages and working prototypes. The problem of Streaming Linked Data publication is currently under investigation. So far, the RSP community efforts have contributed middleware, engines, and vocabularies that address the scientific and technical challenges. Nevertheless, a set of guidelines that showcase how to reuse existing resources to publish streams on the Web is still missing.

This repository contains the code related to the paper A Cookbook for Publishing Streaming Linked Data.

The idea of a Cookbook for publishing Streaming Linked Data is based on the publication lifecycle prescribed by W3C. Particularly, (i) We make use of TripleWave, R2RML/RML, VoCaLS, RSP-QL, as well as other resources for RDF Stream publishing and processing. (ii) We bootstrap a catalogue of Web Streams, highlighting the requirements that drove our selection of three examples of wild streams: DBpedia Live changes, Wikimedia EventStreams, and the Global Database of Events, Language and Tone (GDELT). (iii) Last but not least, we open sourced our code, and make it available on for public use at


In the following, we will show how to run this software in order to produce some RDF streams locally on a device, created from data coming from the Web. The only requirement is to have Java on the machine.

Download and Run


The build file can be downloaded here and run with java 8

java -jar webstreams.jar

This will start the application with the default settings, which means that the GDELT Events Stream will be provided at http://localhost:8080/events .

To visualize the stream you can use an utility like wscat or every other method suitable for WebSockets.

Please note that the stream will start in 10 seconds after the launch of the application; then, in the case of GDELT Streams, a check for new data will be made every 5 minutes.

Manual Configuration

You can use a simple properties file in order to modify the behavior of the application. Create a text file called "" and place it in the same folder of the jar file. You can specify the following values:

Property name Possible values Description Default value
host IP address or "localhost" The IP on which the web server will be deployed. localhost
sgraphport [1024-65535] Port to access sgraphs. 8081
streamport [1024-65535] Port to access streams. 8080
streamToCreate gdelt_mentions, gdelt_events, gdelt_gkg, wikimedia, dbpedia This specifies which stream will be deployed. gdelt_events
stream_header String ??? GDELT Events header
stream_mapping_path Path Path to load the mapping file from. /streams/mapping/geldt_events.ttl
stream_sgraph_path Path Path to load the sgraph file from. /streams/sgraphs/events.ttl
geldtLastUpdateUrl Url URL of data/stream to gather the data from.
wikimediaStreamUrl Url URL of data/stream to gather the data from.
DBPediaLastUpdateUrl Url URL of data/stream to gather the data from.

Default values will be used for fields not specified in

Prebuilt Docker images running each of the published streams with default configuration hare available on Docker Hub

docker pull streamreasoning/webstreams_{stream}:latest

where stream can be:

For instance

docker pull streamreasoning/webstreams_gkg:latest
docker run -p 8080:8080 -p 8081:8081 streamreasoning/webstreams_gkg:latest

Example of user defined properties

For example, if you want to run GDELT GKG Stream, your should look like this:


GDELT Header

The following header should be used for GDELT streams:









The project can be build using maven

maven clean package 

or using the included make file

make build
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