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Edge-Hub Sink Stream

Function

DLI writes the data analyzed and processed by edge jobs to the edge-hub for subsequent processing.

It is applicable to IoT scenarios. It extends the real-time stream computing capability from the cloud to the edge, quickly and accurately analyzes and processes stream data in real time at the edge, and improves the speed and efficiency of data processing and computing. In addition, data is preprocessed at the edge, effectively reducing invalid data to the cloud, reducing resource consumption, and improving analysis efficiency. By managing edge nodes of users, Intelligent EdgeFabric (IEF) extends cloud applications to edge nodes and associates edge and cloud data. IEF also provides unified on-cloud O&M capabilities, such as device/application monitoring and log collection, to offer a complete edge computing solution that contains integrated services under edge and cloud collaboration. For more information about IEF, see the Intelligent EdgeFabric User Guide.

Syntax

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CREATE SINK STREAM stream_id (attr_name attr_type (',' attr_name attr_type)* )
   WITH (
     type = "edgehub", 
     topic = "", 
     encode = "", 
     json_config = "", 
ENABLE_OUTPUT_NULL = "",
     field_delimiter = ''
  );

Keywords

Table 1 Keyword description

Parameter

Mandatory

Description

type

Yes

Indicates the data source type. edgehub indicates that the data source is the edge-hub of IEF.

topic

Yes

Theme, which is the name of the theme in the edge-hub that needs to consume data.

encode

Yes

Data encoding format. The value can be csv and json.

  • field_delimiter must be specified if this parameter is set to csv.
  • json_config must be specified if this parameter is set to json.

field_delimiter

No

Separator used to separate every two attributes. If encode is set to csv, you can use this parameter to specify the separator between CSV fields. By default, the comma (,) is used.

If encode is set to json, you do not need to set separators between attributes.

json_config

No

If encode is set to json, this parameter can be used to specify the mapping between the JSON field and stream definition field. The format is as follows:

"field1=data_json.field1;field2=data_json.field2;field3=$"

In the preceding information, field3=$ indicates that the value of field3 is a JSON string.

enable_output_null

No

If encode is set to json, this parameter can be used to configure whether to output an empty field.

  • The value true indicates that an empty field is generated (the value is null).
  • The value false indicates that no empty field is generated.

Example

Write data in CSV format to the edge-hub topic abcd.

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CREATE SINK STREAM excellent_students(
  name string,
  score int)
WITH (
  type = "edgehub",
  topic = "abcd",
  encode = "csv",
  field_delimiter = ","
);
Parent topic: Creating a Sink Stream