Realtime Compute for Apache Flink:ApsaraMQ for RocketMQ connector

Background information

ApsaraMQ for RocketMQ is a distributed messaging middleware service developed by Alibaba Cloud based on Apache RocketMQ. The service provides low latency, high concurrency, high availability, and high reliability. ApsaraMQ for RocketMQ provides the asynchronous decoupling and load shifting features for distributed application systems. The service also supports features for Internet applications, including message accumulation, high throughput, and reliable retry.

Features

Prerequisites

Resources are created in the ApsaraMQ for RocketMQ console. For more information, see Create resources.

Limits

• Only Realtime Compute for Apache Flink that uses VVR 2.0.0 or later supports the ApsaraMQ for RocketMQ connector.

• Only Realtime Compute for Apache Flink that uses VVR 8.0.3 or later supports ApsaraMQ for RocketMQ 5.x instances.

• In Realtime Compute for Apache Flink that uses VVR of a version earlier than 6.0.2, the deployment parallelism for an ApsaraMQ for RocketMQ source table must be less than or equal to the number of partitions in a topic of ApsaraMQ for RocketMQ. This limit is removed from Realtime Compute for Apache Flink that uses VVR 6.0.2 or later. You can set the deployment parallelism to a value that is greater than the number of partitions in the topic of ApsaraMQ for RocketMQ in advance. You do not need to manually adjust the deployment parallelism when an ApsaraMQ for RocketMQ instance is scaled in.

• The ApsaraMQ for RocketMQ connector uses pull consumers to consume messages. All subtasks share data consumption.

Syntax

CREATE TABLE mq_source(
  x varchar,
  y varchar,
  z varchar
) WITH (
  'connector' = 'mq5',
  'topic' = '<yourTopicName>',
  'endpoint' = '<yourEndpoint>',
  'consumerGroup' = '<yourConsumerGroup>'
);

Parameters in the WITH clause

• Common parameters

  Parameter	Description	Data type	Required	Default value	Remarks
  connector	The type of the connector.	STRING	Yes	No default value	In ApsaraMQ for RocketMQ 4.x, set the value to mq. In ApsaraMQ for RocketMQ 5.x, set the value to mq5.
  endPoint	The endpoint of ApsaraMQ for RocketMQ.	STRING	Yes	No default value	ApsaraMQ for RocketMQ supports the following types of endpoints: For deployments that run on VVR 3.0.1 or later, use Transmission Control Protocol (TCP) endpoints. To obtain the required endpoint, perform the following steps: Internal endpoints of ApsaraMQ for RocketMQ that resides in the classic network or a virtual private cloud (VPC) of Alibaba Cloud: Log on to the ApsaraMQ for RocketMQ console. In the left-side navigation pane, click Instances. On the page that appears, find the required instance and click Details in the Actions column. On the Instance Details page, click the Endpoints tab. You can view the endpoint that corresponds to Internal Access in the TCP Endpoint section. Public endpoint of ApsaraMQ for RocketMQ: Log on to the ApsaraMQ for RocketMQ console. In the left-side navigation pane, click Instances. On the page that appears, find the required instance, and click Details in the Actions column. On the Instance Details page, click the Endpoints tab. You can view the endpoint that corresponds to Internet Access in the TCP Endpoint section. Important Due to changes in the network security policies of Alibaba Cloud, connection issues may occur when Realtime Compute for Apache Flink connects to the public ApsaraMQ for RocketMQ service. We recommend that you use the internal ApsaraMQ for RocketMQ service. The ApsaraMQ for RocketMQ service that resides in the internal network does not support cross-origin access. For example, if your Realtime Compute for Apache Flink service resides in the China (Hangzhou) region but your ApsaraMQ for RocketMQ service resides in the China (Shanghai) region, Realtime Compute for Apache Flink cannot access ApsaraMQ for RocketMQ. If you want to access ApsaraMQ for RocketMQ over the Internet, you must configure network address translation (NAT). For more information, see Create and manage an Internet NAT gateway. For Realtime Compute for Apache Flink deployments that run on VVR of a version earlier than 3.0.1, the old endpoint of ApsaraMQ for RocketMQ is no longer available. You must update your deployments to adapt to the VVR version. Important If you use the ApsaraMQ for RocketMQ connector whose VVR version is earlier than 3.0.1, you must update your Realtime Compute for Apache Flink deployments to VVR 3.0.1 or later and change the value of the endPoint parameter to the new endpoint of ApsaraMQ for RocketMQ. This reduces the risks of instability or unavailability that are caused by the old endpoint of ApsaraMQ for RocketMQ. For more information, see Service notices of Realtime Compute for Apache Flink.
  topic	The name of the topic.	STRING	Yes	No default value	N/A.
  accessId	ApsaraMQ for RocketMQ 4.x: the AccessKey ID of your Alibaba Cloud account. ApsaraMQ for RocketMQ 5.x: the username of the ApsaraMQ for RocketMQ instance.	STRING	ApsaraMQ for RocketMQ 4.x: yes ApsaraMQ for RocketMQ 5.x: no	No default value	ApsaraMQ for RocketMQ 4.x: For more information how to obtain the AccessKey ID of your Alibaba Cloud account, see the "How do I view information about the AccessKey ID and AccessKey secret of the account?" section of the Console operations topic. Important To protect your AccessKey pair, we recommend that you specify the AccessKey ID by using the key management method. For more information, see Manage keys. ApsaraMQ for RocketMQ 5.x: If you want to access an ApsaraMQ for RocketMQ instance over the Internet, set this parameter to the username of the ApsaraMQ for RocketMQ instance in the ApsaraMQ for RocketMQ console. If you want to access an ApsaraMQ for RocketMQ instance whose client is deployed on an Elastic Compute Service (ECS) instance over an internal network, you do not need to set this parameter.
  accessKey	ApsaraMQ for RocketMQ 4.x: the AccessKey secret of your Alibaba Cloud account. ApsaraMQ for RocketMQ 5.x: the password of the ApsaraMQ for RocketMQ instance.	STRING	ApsaraMQ for RocketMQ 4.x: yes ApsaraMQ for RocketMQ 5.x: no	No default value	ApsaraMQ for RocketMQ 4.x: For more information how to obtain the AccessKey secret of your Alibaba Cloud account, see the "How do I view information about the AccessKey ID and AccessKey secret of the account?" section of the Console operations topic. Important To protect your AccessKey pair, we recommend that you specify the AccessKey secret by using the key management method. For more information, see Manage keys. ApsaraMQ for RocketMQ 5.x: If you want to access an ApsaraMQ for RocketMQ instance over the Internet, set this parameter to the password of the ApsaraMQ for RocketMQ instance in the ApsaraMQ for RocketMQ console. If you want to access an ApsaraMQ for RocketMQ instance whose client is deployed on an ECS instance over an internal network, you do not need to set this parameter.
  tag	The tag of the message that is subscribed to or written.	STRING	No	No default value	For an ApsaraMQ for RocketMQ source table, only a single tag can be read. For an ApsaraMQ for RocketMQ result table, you can configure multiple tags. Separate multiple tags with commas (,). Note For an ApsaraMQ for RocketMQ result table, only ApsaraMQ for RocketMQ 4.x instances are supported. If you use an ApsaraMQ for RocketMQ 5.x instance, you can specify the tag of a message by using the fields in an ApsaraMQ for RocketMQ result table.
  nameServerSubgroup	The name server group.	STRING	No	No default value	For the ApsaraMQ for RocketMQ service that resides in the classic network or a VPC of Alibaba Cloud, you must set this parameter to nsaddr4client-internal. For the ApsaraMQ for RocketMQ service that can be accessed over the Internet, you do not need to configure this parameter. Note This parameter is supported only in VVR whose version is in the range of 2.1.1 to 3.0.0. In VVR 3.0.1 or later, this parameter is not supported.
  encoding	The encoding format.	STRING	No	UTF-8	N/A.
  instanceID	The ID of the ApsaraMQ for RocketMQ instance.	STRING	No	No default value	If the ApsaraMQ for RocketMQ instance does not use a separate namespace, the instanceID parameter cannot be configured. If the ApsaraMQ for RocketMQ instance uses a separate namespace, you must configure the instanceID parameter. Note Only ApsaraMQ for RocketMQ 4.x instances support this parameter. If you use an ApsaraMQ for RocketMQ 5.x instance, you do not need to set this parameter.

• Parameters that are exclusive to source tables

  Parameter	Description	Data type	Required	Default value	Remarks
  consumerGroup	The name of the consumer group.	STRING	Yes	No default value	N/A.
  pullIntervalMs	The wait interval of the source if no data can be consumed from the upstream storage system.	INT	Yes	No default value	Unit: milliseconds. You cannot configure the rate at which ApsaraMQ for RocketMQ messages are read because no throttling mechanism is available. Note Only ApsaraMQ for RocketMQ 4.x instances support this parameter. If you use an ApsaraMQ for RocketMQ 5.x instance, you do not need to set this parameter.
  timeZone	The time zone of the instance.	STRING	No	No default value	Example: Asia or Shanghai.
  startTimeMs	The time to start reading data.	LONG	No	No default value	The timestamp. Unit: milliseconds.
  startMessageOffset	The start offset to consume messages.	INT	No	No default value	This parameter is optional. If you set this parameter, messages are consumed from the time specified by this parameter.
  lineDelimiter	The row delimiter used when a message block is parsed.	STRING	No	\n	N/A.
  fieldDelimiter	The field delimiter.	STRING	No	\u0001	The delimiter varies based on the mode in which the terminal of ApsaraMQ for RocketMQ works. In read-only mode, the delimiter is \u0001. This is the default mode. In this mode, the delimiter is invisible. In edit mode, the delimiter is ^A.
  lengthCheck	The rule for checking the number of fields parsed from a row of data.	INT	No	NONE	Valid values: NONE: This is the default value. If the number of fields that are parsed from a row of data is greater than the specified number of fields, data is extracted from left to right based on the order of specified fields. If the number of fields that are parsed from a row of data is smaller than the specified number of fields, this row of data is skipped. SKIP: If the number of fields that are parsed from a row of data does not match the number of specified fields, this row of data is skipped. EXCEPTION: If the number of fields that are parsed from a row of data is different from the specified number of fields, an exception is reported. PAD: Data is padded from left to right based on the order of specified fields. If the number of fields that are parsed from a row of data is greater than the specified number of fields, data is extracted from left to right based on the order of specified fields. If the number of fields parsed from a row of data is smaller than the number of defined fields, the values of the missing fields are padded with null. Note SKIP, EXCEPTION, and PAD are optional values.
  columnErrorDebug	Specifies whether to enable debugging.	BOOLEAN	No	false	If you set this parameter to true, a log entry that indicates a parsing exception is returned.
  pullBatchSize	The maximum number of messages that can be pulled at a time.	INT	No	64	Only Realtime Compute for Apache Flink that uses VVR 8.0.7 or later supports this parameter.

• Parameters that are exclusive to result tables

  Parameter	Description	Data type	Required	Default value	Remarks
  producerGroup	The name of the producer group.	STRING	Yes	No default value	N/A.
  retryTimes	The number of retries for writing data to the table.	INT	No	10	N/A.
  sleepTimeMs	The retry interval.	LONG	No	5000	N/A.
  partitionField	The partition key column. You can specify a field as a partition key column.	STRING	No	No default value	This parameter is required if the mode parameter is set to partition. Note Only Realtime Compute for Apache Flink that uses VVR 8.0.5 or later supports this parameter.

Data type mappings

Examples

• Source table

  • CSV format

    For example, a CSV message is recorded in the following format:

    1,name,male 
    2,name,female

    Note

    An ApsaraMQ for RocketMQ message can contain zero to more data records. Multiple data records are separated by \n.

    You can execute the following DDL statement to declare an ApsaraMQ for RocketMQ source table in a Realtime Compute for Apache Flink deployment:

    • ApsaraMQ for RocketMQ 5.x

    CREATE TABLE mq_source(
      id varchar,
      name varchar,
      gender varchar,
      topic varchar metadata virtual
    ) WITH (
      'connector' = 'mq5',
      'topic' = 'mq-test',
      'endpoint' = '<yourEndpoint>',
      'consumerGroup' = 'mq-group',
      'fieldDelimiter' = ','
    );

    • ApsaraMQ for RocketMQ 4.x

    CREATE TABLE mq_source(
      id varchar,
      name varchar,
      gender varchar,
      topic varchar metadata virtual
    ) WITH (
      'connector' = 'mq',
      'topic' = 'mq-test',
      'endpoint' = '<yourEndpoint>',
      'pullIntervalMs' = '1000',
      'accessId' = '${secret_values.ak_id}',
      'accessKey' = '${secret_values.ak_secret}',
      'consumerGroup' = 'mq-group',
      'fieldDelimiter' = ','
    );

  • Binary format

    • ApsaraMQ for RocketMQ 5.x

      CREATE TEMPORARY TABLE source_table (
        mess varbinary
      ) WITH (
        'connector' = 'mq5',
        'endpoint' = '<yourEndpoint>',
        'topic' = 'mq-test',
        'consumerGroup' = 'mq-group'
      );
      
      CREATE TEMPORARY TABLE out_table (
        commodity varchar
      ) WITH (
        'connector' = 'print'
      );
      
      INSERT INTO out_table
      select 
        cast(mess as varchar)
      FROM source_table;

    • ApsaraMQ for RocketMQ 4.x

      CREATE TEMPORARY TABLE source_table (
        mess varbinary
      ) WITH (
        'connector' = 'mq',
        'endpoint' = '<yourEndpoint>',
        'pullIntervalMs' = '500',
        'accessId' = '${secret_values.ak_id}',
        'accessKey' = '${secret_values.ak_secret}',
        'topic' = 'mq-test',
        'consumerGroup' = 'mq-group'
      );
      
      CREATE TEMPORARY TABLE out_table (
        commodity varchar
      ) WITH (
        'connector' = 'print'
      );
      
      INSERT INTO out_table
      select 
        cast(mess as varchar)
      FROM source_table;

• Result table

  • Create an ApsaraMQ for RocketMQ result table.

    • ApsaraMQ for RocketMQ 5.x

      CREATE TABLE mq_sink (
        id INTEGER,
        len BIGINT,
        content VARCHAR
      ) WITH (
        'connector'='mq5',
        'endpoint'='<yourEndpoint>',
        'topic'='<yourTopicName>',
        'producerGroup'='<yourGroupName>'
      );

    • ApsaraMQ for RocketMQ 4.x

      CREATE TABLE mq_sink (
        id INTEGER,
        len BIGINT,
        content VARCHAR
      ) WITH (
        'connector'='mq',
        'endpoint'='<yourEndpoint>',
        'accessId'='${secret_values.ak_id}',
        'accessKey'='${secret_values.ak_secret}',
        'topic'='<yourTopicName>',
        'producerGroup'='<yourGroupName>'
      );

      Note

      If the messages of your ApsaraMQ for RocketMQ instance are in the binary format, only one field can be defined in the DDL statement and the field must be of the VARBINARY data type.

  • Create an ApsaraMQ for RocketMQ result table in which the values of the keys and tags fields are defined as the keys and tags of ApsaraMQ for RocketMQ messages.

    • ApsaraMQ for RocketMQ 5.x

      CREATE TABLE mq_sink (
        id INTEGER,
        len BIGINT,
        content VARCHAR,
        keys VARCHAR METADATA,
        tags VARCHAR METADATA
      ) WITH (
        'connector'='mq5',
        'endpoint'='<yourEndpoint>',
        'topic'='<yourTopicName>',
        'producerGroup'='<yourGroupName>'
      );

    • ApsaraMQ for RocketMQ 4.x

      CREATE TABLE mq_sink (
        id INTEGER,
        len BIGINT,
        content VARCHAR,
        keys VARCHAR METADATA,
        tags VARCHAR METADATA
      ) WITH (
        'connector'='mq',
        'endpoint'='<yourEndpoint>',
        'accessId'='${secret_values.ak_id}',
        'accessKey'='${secret_values.ak_secret}',
        'topic'='<yourTopicName>',
        'producerGroup'='<yourGroupName>'
      );

FAQ

How does the connector for the ApsaraMQ for RocketMQ source table learn the change in the number of partitions in a topic when new partitions are created in the topic?