Apache NiFi

Apache NiFi Introduction

Apache NiFi is an easy to use, powerful, and reliable system to process and distribute data.

Apache NiFi supports powerful and scalable directed graphs of data routing, transformation, and system mediation logic.

Apache NiFi includes the following capabilities:

• Browser-based user interface
  • Seamless experience for design, control, feedback, and monitoring
• Data provenance tracking
  • Complete lineage of information from beginning to end
• Extensive configuration
  • Loss-tolerant and guaranteed delivery
  • Low latency and high throughput
  • Dynamic prioritization
  • Runtime modification of flow configuration
  • Back pressure control
• Extensible design
  • Component architecture for custom Processors and Services
  • Rapid development and iterative testing
• Secure communication
  • HTTPS with configurable authentication strategies
  • Multi-tenant authorization and policy management
  • Standard protocols for encrypted communication including TLS and SSH

PutIoTDBRecord

This is a processor that reads the content of the incoming FlowFile as individual records using the configured ‘Record Reader’ and writes them to Apache IoTDB using native interface.

Properties of PutIoTDBRecord

property	description	default value	necessary
Host	The host of IoTDB.	null	true
Port	The port of IoTDB.	6667	true
Username	Username to access the IoTDB.	null	true
Password	Password to access the IoTDB.	null	true
Prefix	The Prefix begin with root. that will be add to the tsName in data. It can be updated by expression language.	null	true
Time	The name of time field	null	true
Record Reader	Specifies the type of Record Reader controller service to use for parsing the incoming data and determining the schema.	null	true
Schema	The schema that IoTDB needs doesn‘t support good by NiFi. Therefore, you can define the schema here. Besides, you can set encoding type and compression type by this method. If you don’t set this property, the inferred schema will be used. It can be updated by expression language.	null	false
Aligned	Whether using aligned interface? It can be updated by expression language.	false	false
MaxRowNumber	Specifies the max row number of each tablet. It can be updated by expression language.	1024	false

Inferred Schema of Flowfile

There are a couple of rules about flowfile:

1. The flowfile can be read by Record Reader.
2. The schema of flowfile must contain a time field with name set in Time property.
3. The data type of time must be STRING or LONG.
4. Fields excepted time must start with root..
5. The supported data types are INT, LONG, FLOAT, DOUBLE, BOOLEAN, TEXT.

Convert Schema by property

As mentioned above, converting schema by property which is more flexible and stronger than inferred schema.

The structure of property Schema:

{
	"fields": [{
		"tsName": "s1",
		"dataType": "INT32",
		"encoding": "RLE",
		"compressionType": "GZIP"
	}, {
		"tsName": "s2",
		"dataType": "INT64",
		"encoding": "RLE",
		"compressionType": "GZIP"
	}]
}

Note

1. The first column must be Time. The rest must be arranged in the same order as in field of JSON.
2. The JSON of schema must contain timeType and fields.
3. There are only two options LONG and STRING for timeType.
4. The columns tsName and dataType must be set.
5. The property Prefix will be added to tsName as the field name when add data to IoTDB.
6. The supported dataTypes are INT32, INT64, FLOAT, DOUBLE, BOOLEAN, TEXT.
7. The supported encoding are PLAIN, DICTIONARY, RLE, DIFF, TS_2DIFF, BITMAP, GORILLA_V1, REGULAR, GORILLA, CHIMP, SPRINTZ, RLBE.
8. The supported compressionType are UNCOMPRESSED, SNAPPY, GZIP, LZO, SDT, PAA, PLA, LZ4, ZSTD, LZMA2.

Relationships

relationship	description
success	Data can be written correctly or flow file is empty.
failure	The shema or flow file is abnormal.

QueryIoTDBRecord

This is a processor that reads the sql query from the incoming FlowFile and using it to query the result from IoTDB using native interface. Then it use the configured ‘Record Writer’ to generate the flowfile

Properties of QueryIoTDBRecord

property	description	default value	necessary
Host	The host of IoTDB.	null	true
Port	The port of IoTDB.	6667	true
Username	Username to access the IoTDB.	null	true
Password	Password to access the IoTDB.	null	true
Record Writer	Specifies the Controller Service to use for writing results to a FlowFile. The Record Writer may use Inherit Schema to emulate the inferred schema behavior, i.e. An explicit schema need not be defined in the writer, and will be supplied by the same logic used to infer the schema from the column types.	null	true
iotdb-query	The IoTDB query to execute. Note: If there are incoming connections, then the query is created from incoming FlowFile's content otherwise"it is created from this property.	null	false
iotdb-query-chunk-size	Chunking can be used to return results in a stream of smaller batches (each has a partial results up to a chunk size) rather than as a single response. Chunking queries can return an unlimited number of rows. Note: Chunking is enable when result chunk size is greater than 0	0	false

Relationships

relationship	description
success	Data can be written correctly or flow file is empty.
failure	The shema or flow file is abnormal.