The repository includes all you need to test SEPA, a publish-subscribe architecture designed to support information level interoperability by means of Semantic Web technologies. The architecture is built on top of a generic SPARQL endpoint where publishers and subscribers use standard SPARQL Updates and Queries. Notifications about events (i.e., changes in the RDF knowledge base) are expressed in terms of added and removed SPARQL binding results since the previous notification.
Developers can benefit of a set of API implementing a Producer-Aggregator-Consumer design pattern.
For more details on the current implementation and how you can contribute please follow this link.
Clone the repository: git clone https://github.com/arces-wot/SEPABins.git
The SEPA broker needs to connect to a SPARQL endpoint supporting the SPARQL 1.1 Protocol. For you convenience, the repository includes an instance of Blazegraph.
From a command shell move to the Endpoint folder and run the endpoint: java -jar blazegraph.jar
If Blazegraph started correctly, you would see something like the following:
Welcome to the Blazegraph(tm) Database.
Go to http://192.168.1.11:9999/blazegraph/ to get started.
Otherwise, Blazegraph failed to start. This can be due to the JRE version: If you are using Java 9, try forcing the use of Java 8 JRE: /Library/Java/JavaVirtualMachines/jdk1.8.0_65.jdk/Contents/Home/bin/java -jar blazegraph.jar
In any case, please refer to the Blazegraph web site to download and run the last version (the one we provide is just for the purpose of quickly testing SEPA and may not be updated).
From a command shell, move to the Engine folder and type: java -Dlog4j.configurationFile=./log4j2.xml -jar engine-0-SNAPSHOT.jar
The following welcome message would be displayed:
##########################################################################################
# ____ _____ ____ _ #
# / ___|| ____| _ \ / \ #
# \___ \| _| | |_) / _ \ #
# ___) | |___| __/ ___ \ #
# |____/|_____|_| /_/ \_\ #
# #
# SPARQL Event Processing Architecture #
# #
# #
# This program comes with ABSOLUTELY NO WARRANTY #
# This is free software, and you are welcome to redistribute it under certain conditions #
# GNU GENERAL PUBLIC LICENSE, Version 3, 29 June 2007 #
# #
# #
# @prefix git: <https://github.com/> . #
# @prefix dc: <http://purl.org/dc/elements/1.1/> . #
# #
# git:arces-wot/sepa dc:title 'SEPA' ; #
# dc:creator git:lroffia ; #
# dc:contributor git:relu91 ; #
# dc:format <https://java.com> ; #
# dc:publisher <https://github.com> . #
##########################################################################################
SPARQL 1.1 endpoint
----------------------
SPARQL 1.1 Query | http://localhost:9999/blazegraph/namespace/kb/sparql (Method: POST)
SPARQL 1.1 Update | http://localhost:9999/blazegraph/namespace/kb/sparql (Method: POST)
----------------------
SPARQL 1.1 Protocol (https://www.w3.org/TR/sparql11-protocol/)
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SPARQL 1.1 Query | http://192.168.1.3:8000/query
SPARQL 1.1 Update | http://192.168.1.3:8000/update
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SPARQL 1.1 SE Protocol (http://mml.arces.unibo.it/TR/sparql11-se-protocol.html)
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SPARQL 1.1 Subscribe | ws://192.168.1.3:9000/subscribe
----------------------
*****************************************************************************************
* SEPA Broker Ver 1.0.0 is up and running *
* Let Things Talk! *
*****************************************************************************************
To close the broker just type CTRL+X:
Stopping HTTP gate...
Stopping WebSocket gate...
Stopping Processor...
Stopped...bye bye :-)
SEPA applications are built around the JSON Semantic Application Profile (JSAP). A demo application can be found in the Chat folder. The JSAP file is named chat.jsap. The chat demo repository can be found here. From a command shell, move to the Chat folder and type: java -jar Chat.jar
The output should look like:
2021-04-12T18:58:36,779 [INFO ] main (DeleteAll.java:23) Delete all
2021-04-12T18:58:36,903 [INFO ] main (SEPAChatTest.java:88) Register client: ChatBot0
2021-04-12T18:58:36,955 [INFO ] main (SEPAChatTest.java:88) Register client: ChatBot1
2021-04-12T18:58:37,272 [INFO ] Thread-0 (ChatMonitor.java:98) *******************************************************
2021-04-12T18:58:37,272 [INFO ] Thread-0 (ChatMonitor.java:99) user|messages|received|sent|removed|brokenRec|brokenRem
2021-04-12T18:58:37,272 [INFO ] Thread-0 (ChatMonitor.java:100) *******************************************************
2021-04-12T18:58:37,273 [INFO ] Thread-0 (ChatMonitor.java:104) http://wot.arces.unibo.it/chat/user/ChatBot0|5|0|0|0|false|false
2021-04-12T18:58:37,273 [INFO ] Thread-0 (ChatMonitor.java:104) http://wot.arces.unibo.it/chat/user/ChatBot1|5|0|0|0|false|false
2021-04-12T18:58:37,308 [INFO ] main (ChatClient.java:34) http://wot.arces.unibo.it/chat/user/ChatBot0 joining the chat...
2021-04-12T18:58:37,366 [INFO ] main (ChatClient.java:49) http://wot.arces.unibo.it/chat/user/ChatBot0 chat joined!
2021-04-12T18:58:37,393 [INFO ] main (ChatClient.java:34) http://wot.arces.unibo.it/chat/user/ChatBot1 joining the chat...
2021-04-12T18:58:37,441 [INFO ] main (ChatClient.java:49) http://wot.arces.unibo.it/chat/user/ChatBot1 chat joined!
2021-04-12T18:58:38,275 [INFO ] Thread-0 (ChatMonitor.java:98) *******************************************************
2021-04-12T18:58:38,276 [INFO ] Thread-0 (ChatMonitor.java:99) user|messages|received|sent|removed|brokenRec|brokenRem
2021-04-12T18:58:38,276 [INFO ] Thread-0 (ChatMonitor.java:100) *******************************************************
2021-04-12T18:58:38,276 [INFO ] Thread-0 (ChatMonitor.java:104) http://wot.arces.unibo.it/chat/user/ChatBot0|5|3|2|1|false|false
2021-04-12T18:58:38,277 [INFO ] Thread-0 (ChatMonitor.java:104) http://wot.arces.unibo.it/chat/user/ChatBot1|5|2|2|0|false|false
2021-04-12T18:58:39,279 [INFO ] Thread-0 (ChatMonitor.java:98) *******************************************************
2021-04-12T18:58:39,280 [INFO ] Thread-0 (ChatMonitor.java:99) user|messages|received|sent|removed|brokenRec|brokenRem
2021-04-12T18:58:39,280 [INFO ] Thread-0 (ChatMonitor.java:100) *******************************************************
2021-04-12T18:58:39,280 [INFO ] Thread-0 (ChatMonitor.java:104) http://wot.arces.unibo.it/chat/user/ChatBot0|5|5|4|3|false|false
2021-04-12T18:58:39,281 [INFO ] Thread-0 (ChatMonitor.java:104) http://wot.arces.unibo.it/chat/user/ChatBot1|5|5|4|2|false|false
2021-04-12T18:58:40,286 [INFO ] Thread-0 (ChatMonitor.java:98) *******************************************************
2021-04-12T18:58:40,286 [INFO ] Thread-0 (ChatMonitor.java:99) user|messages|received|sent|removed|brokenRec|brokenRem
2021-04-12T18:58:40,286 [INFO ] Thread-0 (ChatMonitor.java:100) *******************************************************
2021-04-12T18:58:40,287 [INFO ] Thread-0 (ChatMonitor.java:104) http://wot.arces.unibo.it/chat/user/ChatBot0|5|5|5|5|false|false
2021-04-12T18:58:40,287 [INFO ] Thread-0 (ChatMonitor.java:104) http://wot.arces.unibo.it/chat/user/ChatBot1|5|5|5|5|false|false
The demo application is configured to simulate two chat bots, exchanging 5 messages each other. The messagges are sent, received and the removed.
SEPA comes with a dashboard that provides all the functionalities needed to interact with a SEPA broker (using JSAP files). The dashboard repository can be found here. In the Dashboard folder run it from a command shell as: java -jar SepaDashboard-0-SNAPSHOT-jar-with-dependencies.jar
Now, let's use the dashboard to inspect what has been produced by the chat demo:
- Click on the
Load JSAPbutton. Move to theChatand locate thechat.jsap. Open it. - Query for registered users: select
USERSon the right list box and clickQUERY
What you have done can be done with a common SPARQL endpoint. But SEPA can do more...press SUBSCRIBE. A new tab is opened with the notifications on changes in the registered users. Grey lines indicate "old" values, while white lines indicate "new" values.
Run again the chat demo and see the notifications on the dashboard. Now move back to SPARQL tab and QUERY for messages SENT to http://wot.arces.unibo.it/chat/user/ChatBot0. No messages have been sent ... press SUBSCRIBE ... and run the chat demo again ...
This is what we intend for Dynamic Linked Data! Don't be shy...join us!