Hello!

I'm a beginner in YAWL, and I've started to test a simple Custom service to a further YAWL work integration with JADEX. To accomplish this, i've followed the tutorial in the YAWL technical manual at chapter 3. My custom service and project structure can be visualized here: https://github.com/Shothogun/YAWL-JADEX-CustomService-

So basically I just followed the tutorial steps, but at the "Add service" page step when I fill the forms information and click on "Add", the Yawl console log lags for a brief moment and shows up this message:

2021-01-10 10:18:18,622 [DEBUG] TestService :- ** TEST BEGINS **
2021-01-10 10:18:18,638 [ERROR] YEngine :- Failure returned from startCase - Rolling back Hibernate TXN
org.yawlfoundation.yawl.exceptions.YStateException: No specification found with ID [simpletest - version 0.1]
at org.yawlfoundation.yawl.engine.YSpecificationTable.getSpecificationForCaseStart(YSpecificationTable.java:147) ~[yawl-lib-4.3.1.jar:?]
at org.yawlfoundation.yawl.engine.YEngine.startCase(YEngine.java:735) ~[yawl-lib-4.3.1.jar:?]
at org.yawlfoundation.yawl.engine.YEngine.launchCase(YEngine.java:917) [yawl-lib-4.3.1.jar:?]
at org.yawlfoundation.yawl.engine.YEngine.launchCase(YEngine.java:897) [yawl-lib-4.3.1.jar:?]
at org.yawlfoundation.yawl.engine.interfce.EngineGatewayImpl.launchCase(EngineGatewayImpl.java:765) [yawl-lib-4.3.1.jar:?]
at org.yawlfoundation.yawl.engine.interfce.interfaceB.InterfaceB_EngineBasedServer.processPostQuery(InterfaceB_EngineBasedServer.java:322) [yawl-lib-4.3.1.jar:?]
at org.yawlfoundation.yawl.engine.interfce.interfaceB.InterfaceB_EngineBasedServer.doPost(InterfaceB_EngineBasedServer.java:227) [yawl-lib-4.3.1.jar:?]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:650) [servlet-api.jar:?]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:731) [servlet-api.jar:?]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303) [catalina.jar:7.0.65]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) [catalina.jar:7.0.65]
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) [tomcat7-websocket.jar:7.0.65]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241) [catalina.jar:7.0.65]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) [catalina.jar:7.0.65]
at org.yawlfoundation.yawl.util.CharsetFilter.doFilter(CharsetFilter.java:61) [yawl-lib-4.3.1.jar:?]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241) [catalina.jar:7.0.65]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) [catalina.jar:7.0.65]
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220) [catalina.jar:7.0.65]
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122) [catalina.jar:7.0.65]
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:505) [catalina.jar:7.0.65]
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:170) [catalina.jar:7.0.65]
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103) [catalina.jar:7.0.65]
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:956) [catalina.jar:7.0.65]
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116) [catalina.jar:7.0.65]
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:423) [catalina.jar:7.0.65]
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1079) [tomcat-coyote.jar:7.0.65]
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:625) [tomcat-coyote.jar:7.0.65]
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:316) [tomcat-coyote.jar:7.0.65]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [?:1.8.0_241]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [?:1.8.0_241]
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-coyote.jar:7.0.65]
at java.lang.Thread.run(Thread.java:748) [?:1.8.0_241]

And probably because of this error, when i add this service at an test workflow and start its case this error show up at console:

2021-01-10 10:26:00,792 [INFO ] ResourceMap :- Resourcing specification parse completed for task: Task
<failure><reason>Invalid or expired session.</reason></failure>
org.yawlfoundation.yawl.exceptions.YAWLException: <failure><reason>Invalid or expired session.</reason></failure>
at org.yawlfoundation.yawl.engine.interfce.interfaceB.InterfaceBWebsideController.checkOut(InterfaceBWebsideController.java:320)
at org.yawlfoundation.yawl.testService.TestService.handleEnabledWorkItemEvent(TestService.java:97)
at org.yawlfoundation.yawl.engine.interfce.interfaceB.InterfaceB_EnvironmentBasedServer$EventHandler.run(InterfaceB_EnvironmentBasedServer.java:173)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)

I don't know where and what my error could be(war file, .java class file, web.xml...). Somebody could help me please?