Created question in FIWARE Q/A platform on 15-06-2016 at 15:06
Please, ANSWER this question AT http://stackoverflow.com/questions/37836534/fiware-context-broker-issue-with-ngsiv2-subscriptions

Question:
Fiware - Context broker: Issue with NGSIv2 subscriptions

Description:
I'm working with an Orion context broker version 1.2.0. I have subscribed in it two different cygnus (0.11 and 0.13) using NGSIv2, as follows:

(curl 172.21.0.23:1026/v2/subscriptions s -S --header 'Fiware-Service: prueba_015_adapter' --header 'Fiware-ServicePath: /Prueba/Planta_3' --header 'Content-Type: application/json' -d @ ) <<EOF
{
"description": "Cygnus subscription",
"subject": {
"entities": [

],
"condition":

},
"notification": {
"http":

,
"attrs": []
}
}
EOF

But when the context broker sends a notification to any of these cygnus modules, the next error appears in the log:

15 jun 2016 12:46:48,641 INFO [1469152682@qtp-857344131-3153] (com.telefonica.iot.cygnus.handlers.OrionRestHandler.getEvents:150) - Starting transaction (1463998603-759-0001644173) 15 jun 2016 12:46:48,641 INFO [1469152682@qtp-857344131-3153] (com.telefonica.iot.cygnus.handlers.OrionRestHandler.getEvents:232) - Received data ({"subscriptionId":"57612ed9efa20b5b23e71bd5","data":[{"id":"C-A2","type":"density_algorithm","densityPlan":{"type":"string","value":"C-A2","metadata":{}},"devices":{"type":"string","value":"43","metadata":{}},"timestamp":{"type":"string","value":"2016-06-15T12:53:26.294+02:00","metadata":{}}}]}) 15 jun 2016 12:46:48,641 INFO [1469152682@qtp-857344131-3153] (com.telefonica.iot.cygnus.handlers.OrionRestHandler.getEvents:255) - Event put in the channel (id=957931298, ttl=-1) 15 jun 2016 12:46:48,642 WARN [1469152682@qtp-857344131-3153] (com.telefonica.iot.cygnus.interceptors.GroupingInterceptor.intercept:289)

• No context responses within the notified entity, nothing is done 15 jun 2016 12:46:48,642 WARN [1469152682@qtp-857344131-3153] (org.apache.flume.source.http.HTTPSource$FlumeHTTPServlet.doPost:203)
• Error appending event to channel. Channel might be full. Consider increasing the channel capacity or make sure the sinks perform faster. org.apache.flume.ChannelException: Unable to put batch on required channel: org.apache.flume.channel.MemoryChannel {name: mongo-channel}

  at org.apache.flume.channel.ChannelProcessor.processEventBatch(ChannelProcessor.java:200)
  at org.apache.flume.source.http.HTTPSource$FlumeHTTPServlet.doPost(HTTPSource.java:201)
  at javax.servlet.http.HttpServlet.service(HttpServlet.java:725)
  at javax.servlet.http.HttpServlet.service(HttpServlet.java:814)
  at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:511)
  at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:401)
  at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182)
  at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:766)
  at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
  at org.mortbay.jetty.Server.handle(Server.java:326)
  at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542)
  at org.mortbay.jetty.HttpConnection$RequestHandler.content(HttpConnection.java:945)
  at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:756)
  at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:218)
  at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404)
  at org.mortbay.jetty.bio.SocketConnector$Connection.run(SocketConnector.java:228)
  at org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:582) Caused by: java.lang.IllegalArgumentException: put() called with null event!
  at com.google.common.base.Preconditions.checkArgument(Preconditions.java:88)
  at org.apache.flume.channel.BasicTransactionSemantics.put(BasicTransactionSemantics.java:89)
  at org.apache.flume.channel.BasicChannelSemantics.put(BasicChannelSemantics.java:80)
  at org.apache.flume.channel.ChannelProcessor.processEventBatch(ChannelProcessor.java:189)
  ... 16 more

If I use NGSIv1 instead to register both subscriptions, everything goes fine: no log error is shown and the data is persisted into both cygnus modules.

(curl 172.21.0.23:1026/v1/subscribeContext s -S --header 'Fiware-Service: prueba_015_adapter' --header 'Fiware-ServicePath: /Prueba/Planta_3' --header 'Content-Type: application/json' --header 'Accept: application/json' -d @ ) <<EOF
{
"entities": [

],
"attributes": [],
"reference": "http://172.21.0.33:5050/notify",
"duration": "P1M",
"notifyConditions": [

]
}
EOF

I'm sending the entities to the context broker using NGSIv1. ¿Can the problem be due to an incompatibility between NGSIv1 and NGSIv2?

Thanks in advance