Created question in FIWARE Q/A platform on 10-03-2016 at 16:03
Please, ANSWER this question AT http://stackoverflow.com/questions/35921306/fiware-cygnus-issue-with-collections-names

Question:
Fiware - Cygnus: Issue with collection's names

Description:
I have encountered a strange behaviour on the Cygnus module. I’m using Context Broker version 0.28 and Cygnus version 0.13. Let’s suppose that I have loaded on the CB (Context Broker) some entities similars to this one:

(curl 172.21.0.33:1026/v1/updateContext -s -S
--header 'Fiware-Service: cb33_1003_06'
--header 'Fiware-ServicePath: /Lugar'
--header 'Content-Type: application/json'
-header 'Accept: application/json' -d @ | python -mjson.tool) <<EOF

{
"contextElements": [
{
"type": "Acceso_Wifi",
"isPattern": "false",
"id": "AP_1.3",
"attributes": [

,

,
{
"name": "position",
"type": "coords",
"value": "13.322326, -1.983824",
"metadatas": [

]
}
]
}
],
"updateAction": "APPEND"
}

EOF

And now I subscribe the Cygnus:

(curl 172.21.0.33:1026/v1/subscribeContext -s -S
--header 'Fiware-Service: cb33_1003_06'
--header 'Fiware-ServicePath: /Lugar'
--header 'Content-Type: application/json'
-header 'Accept: application/json' -d @ | python -mjson.tool) <<EOF
{
"entities": [

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

],
"throttling": "PT1S"
}
EOF

The CB will send one notification to the Cygnus for each matching entity loaded previously on the CB database. Let’s assume that there are 3 entities that meet the subscription’s criteria. In that case, one collection will be created on the Cygnus for each one of these entities (I’m using the default dm-by-entity data model). The problem is that the collection's name are not well formed. The Fiware-ServicePath is concatenated once per each entity, on each collection name:

cygnus2_/Lugar_Lugar_Lugar_AP_1.1_Acceso_Wifi
cygnus2_/Lugar_Lugar_Lugar_AP_1.2_Acceso_Wifi
cygnus2_/Lugar_Lugar_Lugar_AP_1.3_Acceso_Wifi

If we update one of these entities, a new collection will be created with a correct name:

cygnus2_/Lugar_AP_1.1_Acceso_Wifi
cygnus2_/Lugar_Lugar_Lugar_AP_1.1_Acceso_Wifi
cygnus2_/Lugar_Lugar_Lugar_AP_1.2_Acceso_Wifi
cygnus2_/Lugar_Lugar_Lugar_AP_1.3_Acceso_Wifi

On this example there were just 3 entities, but as the amount of matching entities increases, the longer will be the collection's name. And when it arrives to 50 characters, a warning will be raised and no collection will be created.

org.apache.flume.source.http.HTTPBadRequestException: 'fiware-servicePath' header length greater than 50)
at com.telefonica.iot.cygnus.handlers.OrionRestHandler.getEvents(OrionRestHandler.java:209)
at org.apache.flume.source.http.HTTPSource$FlumeHTTPServlet.doPost(HTTPSource.java:184)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:725)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:814)
at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:511)
at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:401)
at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182)
at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:766)
at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
at org.mortbay.jetty.Server.handle(Server.java:326)
at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542)
at org.mortbay.jetty.HttpConnection$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)

¿It’s that behaviour due to an incorrect configuration, or it’s Cygnus’s problem?