EdgeX Source

eKuiper provides built-in support for EdgeX source stream, which can subscribe the message from EdgeX message bus and feed into the eKuiper streaming process pipeline.

Stream definition for EdgeX

EdgeX already defines data types in readings, so it’s recommended to use schema-less stream definition in EdgeX source as in below.

# cd $eKuiper_base
# bin/kuiper CREATE STREAM demo'() with(format="json", datasource="demo" type="edgex")'

EdgeX source will try to get the data type of fields,

• convert to related data type if field of a type can be found in the readings’s ValueType field;
• or keep original value if field of a type can not be found in the readings’s ValueType field;
• or if failed to conver the value, then the value will be dropped, and a warning message print in the log;

The types defined in readings will be converted into related data types that supported in eKuiper.

Boolean

If ValueType value of the reading is Bool, then eKuiper tries to convert to boolean type. Following values will be converted into true.

• “1”, “t”, “T”, “true”, “TRUE”, “True”

Following will be converted into false.

• “0”, “f”, “F”, “false”, “FALSE”, “False”

Bigint

If ValueType value of the reading is INT8 , INT16, INT32, INT64,`UINT , UINT8 , UINT16 , UINT32 , UINT64 then eKuiper tries to convert to Bigint type.

Float

If ValueType value of the reading is FLOAT32, FLOAT64, then eKuiper tries to convert to Float type.

String

If ValueType value of the reading is String, then eKuiper tries to convert to String type.

Boolean array

Bool array type in EdgeX will be converted to boolean array.

Bigint array

All of INT8 , INT16, INT32, INT64,`UINT , UINT8 , UINT16 , UINT32 , UINT64 array types in EdgeX will be converted to Bigint array.

Float array

All of FLOAT32, FLOAT64 array types in EdgeX will be converted to Float array.

Global configurations

The configuration file of EdgeX source is at $ekuiper/etc/sources/edgex.yaml. Below is the file format.

#Global Edgex configurations
default:
  protocol: tcp
  server: localhost
  port: 5573
  topic: events
  messageType: event
#  optional:
#    ClientId: client1
#    Username: user1
#    Password: password

Use can specify the global EdgeX settings here. The configuration items specified in default section will be taken as default settings for all EdgeX source.

protocol

The protocol connect to EdgeX message bus, default value is tcp.

server

The server address of EdgeX message bus, default value is localhost.

port

The port of EdgeX message bus, default value is 5573.

connectionSelector

specify the stream to reuse the connection to EdgeX message bus. The connection profile located in connections/connection.yaml.

edgex:
  redisMsgBus: #connection key
    protocol: redis
    server: 127.0.0.1
    port: 6379
    type: redis
    #  Below is optional configurations settings for mqtt
    #  type: mqtt
    #  optional:
    #    ClientId: client1
    #    Username: user1
    #    Password: password
    #    Qos: 1
    #    KeepAlive: 5000
    #    Retained: true/false
    #    ConnectionPayload:
    #    CertFile:
    #    KeyFile:
    #    CertPEMBlock:
    #    KeyPEMBlock:
    #    SkipCertVerify: true/false

There is one configuration group for EdgeX message bus in the example, user need use edgex.redisMsgBus as the selector. For example

#Global Edgex configurations
default:
  protocol: tcp
  server: localhost
  port: 5573
  connectionSelector: edgex.redisMsgBus
  topic: events
  messageType: event
  #  optional:
  #    ClientId: client1
  #    Username: user1
  #    Password: password

Note: once specify the connectionSelector in specific configuration group , all connection related parameters will be ignored , in this case protocol: tcp | server: localhost | port: 5573

topic

The topic name of EdgeX message bus, default value is events. Users can subscribe to the topics of message bus directly or subscribe to topics exported by EdgeX application service. Notice that, the message type of the two types of topics are different, remember to set the appropriate messageType property.

type

The EdgeX message bus type, currently three types of message buses are supported. If specified other values, then will use the default redis value.

• zero: Use ZeroMQ as EdgeX message bus.
• mqtt: Use the MQTT broker as EdgeX message bus.
• redis: Use Redis as EdgeX message bus. When using EdgeX docker compose, the type will be set to this by default.

messageType

The EdgeX message model type. If connected to the topic of EdgeX application service, the message model is an “event”. Otherwise, if connected to the topic of EdgeX message bus directly to receive the message from device service or core data, the message is a “request”. There are two available types of messageType property:

• event: The message will be decoded as a dtos.Event type. This is the default.
• request: The message will be decoded as a requests.AddEventRequest type.

optional

If MQTT message bus is used, some other optional configurations can be specified. Please notice that all of values in optional are string type, so values for these configurations should be string - such as KeepAlive: "5000" . Below optional configurations are supported, please check MQTT specification for the detailed information.

• ClientId

• Username

• Password
• Qos
• KeepAlive
• Retained
• ConnectionPayload
• CertFile
• KeyFile
• CertPEMBlock
• KeyPEMBlock
• SkipCertVerify

Override the default settings

In some cases, maybe you want to consume message from multiple topics from message bus. eKuiper supports to specify another configuration, and use the CONF_KEY to specify the newly created key when you create a stream.

#Override the global configurations
demo1: #Conf_key
  protocol: tcp
  server: 10.211.55.6
  port: 5571
  topic: events

If you have a specific connection that need to overwrite the default settings, you can create a customized section. In the previous sample, we create a specific setting named with demo1. Then you can specify the configuration with option CONF_KEY when creating the stream definition (see stream specs for more info).

Sample

create stream demo1() WITH (FORMAT="JSON", type="edgex", CONF_KEY="demo1");

The configuration keys used for these specific settings are the same as in default settings, any values specified in specific settings will overwrite the values in default section.