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1. eVolution Service Bus (VSB)

The eVolution Service Bus (VSB) is a development and execution environment dedicated to complex distributed applications of the Internet of the future.

These applications are open and dynamic choreographies of extremely heterogeneous objects and services, including lightweight integrated systems (such as sensors, actuators and networks of the latter), mobile systems (such as smartphone applications), and systems resource-rich computing (such as systems hosted on corporate servers and cloud infrastructures).

The goal of VSB is to allow developper to perfectly interconnect services and things within choreography that use heterogeneous interaction protocols at the middleware layer, such as SOAP Web Services, REST Web Services, or things using CoAP, MQTT. So far the VSB supports following protocols :

  • SOAP
  • REST
  • CoAP
  • MQTT
  • Websocket
  • DPWS

In addition, the VSB provides a monitoring API for this interconnected services and things.

2. Requirements

VSB ensures interoperability of services and things developped in Java.

3. Inteconnecting services and things

To interconnect services and things, developer has to generate a middleware artifact that we call Binding Component (BC) that ensures this interconnection :

Binding Component

For instance based on the above figure, to generate the BC we need to follow this steps :

  • Create a maven based project

  • Creating the Generic Interface Description Language (GIDL) of the service or thing to interconnect

Relying on the above figure, we have to create the GIDL of the Temperature ressource. By using the GIDL eclipse plugin or the VSB Web Console.

  • Updating the pom.xml
Add repository :

<repository>
  <id>ow2-nexus-releases</id> 
  <name>OW2 Release Repository</name>
  <url>http://repository.ow2.org/nexus/content/repositories/releases</url>
</repository>

Add dependecy :

<dependency>
    <groupId>eu.chorevolution.vsb</groupId>
    <artifactId>vsb-manager-api</artifactId>
    <version>2.1.2</version>
</dependency>
  • Generate BC as follow :
VsbManager vsbm = new VsbManager();
vsbm.setServiceEndpoint("HOST-IP_TEMPERATURE_SENSOR", "HOST-PORT_TEMPERATURE_SENSOR");
vsbm.setBusEndpoint("HOST-IP_CLIENT","HOST-PORT_CLIENT");
vsbm.generateWar(PATH_TO_GIDL, ProtocolType.REST, "REST_to_COAP");

After executing this lines of codes, the BC will be generated into the temporary folder of the system.

4. Monitoring services and things

To monitor services and things, VSB provides two APIs.

  • Agent used as probe, that will be included into the services or things to monitor
  • AgentListener used as collector of monitored informations

To do so, first add maven dependency

<dependency>
	<groupId>eu.chorevolution.vsb</groupId>
	<artifactId>monitor</artifactId>
	<version>2.1.2</version>
</dependency>
  • Probe injection with the Agent API : The agent has to be injected into the code of the service or things to monitor, at entry and exit point of the function or operation to monitor.
// To initialize the Agent object
Agent agent = new Agent("NAME_OF_SERVICE_OR_THING_TO_MONITOR", "HOST_ADDRESS_OF_SERVICE_OR_THING_TO_MONITOR", PORT_NUMBER_OF_SERVICE_OR_THING_TO_MONITOR);
// To fire an event to the listener
String event = "event";
agent.fire(event);

/* This method fires the below information : 
event-time+"-"+event+"-NAME_OF_SERVICE_OR_THING_TO_MONITOR";*/
  • API Listener :
// To initialize the AgentListener object
AgentListener listener = new AgentListener("NAME_OF_SERVICE_OR_THING_TO_MONITOR", "HOST_ADDRESS_OF_SERVICE_OR_THING_TO_MONITOR", "PORT_NUMBER_OF_SERVICE_OR_THING_TO_MONITOR");

// To open connection with the SERVICE_OR_THING_TO_MONITOR
listener.connect();

// To get the monitored informations
while(listener.isConnect()){
    
    String data = listener.getMessageListened();
    System.out.println(data);
}
// To close connection with the SERVICE_OR_THING_TO_MONITOR
listener.disconnect();

5. GIDL example


<?xml version="1.0" encoding="UTF-8"?>
<gidl:GIDLModel xmi:version="2.0" xmlns:xmi="http://www.omg.org/XMI" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:gidl="http://eu.chorevolution/modelingnotations/gidl" hostAddress="http://jinx.viktoria.chalmers.se:3000/" protocol="REST">
  <hasInterfaces role="provider">
    <hasOperations name="waypointWeatherInformation" type="two_way_sync" qos="reliable">
      <hasScope name="waypointWeatherInformation" verb="POST" uri="waypointWeatherInformation"/>
      <inputData name="request" context="body" media="json">
        <hasDataType xsi:type="gidl:ComplexType" name="segmentInformationRequest" minOccurs="one" maxOccurs="one">
			<hasDataType xsi:type="gidl:ComplexType" name="waypoint0" minOccurs="one" maxOccurs="one">
				<hasDataType xsi:type="gidl:SimpleType" name="lat" minOccurs="one" maxOccurs="one" type="string"/>
				<hasDataType xsi:type="gidl:SimpleType" name="lon" minOccurs="one" maxOccurs="one" type="string"/>
			</hasDataType>
		    <hasDataType xsi:type="gidl:ComplexType" name="waypoint1" minOccurs="one" maxOccurs="one">
				<hasDataType xsi:type="gidl:SimpleType" name="lat" minOccurs="one" maxOccurs="one" type="string"/>
				<hasDataType xsi:type="gidl:SimpleType" name="lon" minOccurs="one" maxOccurs="one" type="string"/>
			</hasDataType>
        </hasDataType>
      </inputData>
      <outputData name="response" context="body" media="json">
		<hasDataType xsi:type="gidl:ComplexType" name="segmentWeatherInformationResponse" minOccurs="one" maxOccurs="one">
			<hasDataType xsi:type="gidl:ComplexType" name="waypoint0" minOccurs="one" maxOccurs="one">
				<hasDataType xsi:type="gidl:SimpleType" name="lat" minOccurs="one" maxOccurs="one" type="string"/>
				<hasDataType xsi:type="gidl:SimpleType" name="lon" minOccurs="one" maxOccurs="one" type="string"/>
			</hasDataType>
			<hasDataType xsi:type="gidl:ComplexType" name="waypoint1" minOccurs="one" maxOccurs="one">
				<hasDataType xsi:type="gidl:SimpleType" name="lat" minOccurs="one" maxOccurs="one" type="string"/>
				<hasDataType xsi:type="gidl:SimpleType" name="lon" minOccurs="one" maxOccurs="one" type="string"/>
			</hasDataType>
			<hasDataType xsi:type="gidl:ComplexType" name="weatherInfo" minOccurs="one" maxOccurs="one">
				<hasDataType xsi:type="gidl:SimpleType" name="roadTemperature" minOccurs="one" maxOccurs="one" type="string"/>
				<hasDataType xsi:type="gidl:SimpleType" name="airTemperature" minOccurs="one" maxOccurs="one" type="string"/>
				<hasDataType xsi:type="gidl:SimpleType" name="airRelativeHumidity" minOccurs="one" maxOccurs="one" type="string"/>
				<hasDataType xsi:type="gidl:SimpleType" name="windForce" minOccurs="one" maxOccurs="one" type="string"/>
			</hasDataType>
			<hasDataType xsi:type="gidl:SimpleType" name="type" minOccurs="one" maxOccurs="one" type="string"/>
		</hasDataType>
      </outputData>    
	</hasOperations>
  </hasInterfaces>
</gidl:GIDLModel>

6. Who do I talk to?

Patient NTUMBA: patient.ntumba AT inria.fr (developer/architect)

Georgios Bouloukakis: Georgios.Bouloukakis AT inria.fr (designer/architect)

Nikolaos Georgantas: nikolaos.georgantas AT inria.fr (designer)