docs/4_APIs_and_Services/4.5_Message_Signaling/4_AGL_Service_Signal_Composer/4_SignalComposerAPI.md

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   2 edit_link: ''
   3 title: Signal Composer API
   4 origin_url: >-
   5   https://git.automotivelinux.org/apps/agl-service-signal-composer/plain/docs/part-1/4-SignalComposerAPI.md?h=master
   6 ---
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   9
  10 # Signal Composer API
  11
  12 ## subscribe/unsubscribe
  13
  14 Using subscribe you can get update on change for signals you chose and you can
  15 using wildcard to subscribe several signals in the same time.
  16
  17 ```json
  18 signal-composer subscribe {"signal": "rear_left*"}
  19 ON-REPLY 1:signal-composer/subscribe: {"jtype":"afb-reply","request":{"status":"success","uuid":"3d4b743b-7ac6-4d3c-8fce-721107f9dee5"}}
  20 ```
  21
  22 Then event comes up like the following:
  23
  24 ```json
  25 ON-EVENT signal-composer/257b343e-8ea9-4cd7-8f9e-1904fa77f8f2({"event":"signal-composer\/257b343e-8ea9-4cd7-8f9e-1904fa77f8f2","data":{"uid":"rear_left_door","event":"low-can\/messages.doors.rear_left.open","timestamp":4833910845032292484,"value":false},"jtype":"afb-event"})
  26 ```
  27
  28 Unsubscribe happens the same way. When no more signals are holded by the client
  29 then it unsubscribe from the *AGL Application Framework* event handle.
  30
  31 ## addObjects
  32
  33 Let you add sources or signals objects to the signal composer service after
  34 its initialization phase. Use this verb and specify the file as argument, you
  35 could use only the file name or the file name with its absolute path.
  36
  37 ```json
  38 signal-composer addObjects {"file": "sig_doors.json"}
  39 ON-REPLY 1:signal-composer/addObjects: {"jtype":"afb-reply","request":{"status":"success","uuid":"00d7a519-816e-486a-8163-3afb1face4fa"}}
  40 signal-composer addObjects {"file": "/tmp/sig_doors.json"}
  41 ON-REPLY 2:signal-composer/addObjects: {"jtype":"afb-reply","request":{"status":"success"}}
  42 ```
  43
  44 You can follow the activity using the service log journal and check that the
  45 correct number of objects has been added.
  46
  47 > **CAUTION**: You need to get the following permission to be able to load new
  48 objects : `urn:AGL:permission::platform:composer:addObjects`
  49
  50 ## get
  51
  52 You can get a signal value be requesting the API with the verb *get*:
  53
  54 ```json
  55 signal-composer get {"signal": "vehicle_speed", "options": {"average": 10}}
  56 signal-composer get {"signal": "vehicle_speed", "options": {"minimum": 10}}
  57 signal-composer get {"signal": "vehicle_speed", "options": {"maximum": 10}}
  58 signal-composer get {"signal": "vehicle_speed"}
  59 ```
  60
  61 You apply some simple mathematical functions by default present in the
  62 binding, by default **last** is used:
  63
  64 - **average**: make an average on X latest seconds.
  65 - **minimum**: return the minimum value found in the X latest seconds.
  66 - **maximum**: return the maximum value found in the X latest seconds.
  67 - **last**: return the latest value.
  68
  69 ## list
  70
  71 Verb **list** will output the list of defined signals.