Fiware - Context broker: Issue with NGSIv2 subscriptions

问题

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": [
            {
                "idPattern": ".*",
                "type": "density_algorithm"
            }
        ],
        "condition": {
            "attrs": []
        }
    },
    "notification": {
        "http": {
            "url": "http://172.21.0.33:5050/notify"
        },
        "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": [
        {
            "type": "density_algorithm",
            "isPattern": "true",
            "id": ".*"
        }
    ],
    "attributes": [],
    "reference": "http://172.21.0.33:5050/notify",
    "duration": "P1M",
    "notifyConditions": [
        {
            "type": "ONCHANGE",
            "condValues": []
        }
    ]
}
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

回答1:

For the time being, NGSIv2 notifications are not supported in Cygnus. It is expected to be implemented, but it has not been scheduled yet.

However, you can use attrFormat (inside nofitication field) equal to legacy to use NGSIv1 notification format (have a look to more detailed information here). NGSIv1 notification format is fully supported by Cygnus, so that should work.

来源：https://stackoverflow.com/questions/37836534/fiware-context-broker-issue-with-ngsiv2-subscriptions