AzureEventHubsConnector

Categories

Web

Related Transformers

AzureIoTConnector

AzureQueueStorageConnector

GoogleCloudPubSubConnector

KafkaConnector

SQSConnector

Accesses the Azure Event Hubs to send, receive, or checkpoint messages.

Jump to Configuration

Typical Uses

  • Receive and send messages from an event hub
  • Interoperability with Big Data analytics platforms

How does it work?

The AzureEventHubsConnector connects to Azure’s Event Hubs through the Kafka protocol using the Azure Event Hub SDK. Supports publishing, receiving messages, and checkpointing messages. A message is also known in the Azure documentation as an event.

Configuration

Input Ports

This transformer accepts any feature.

Output Ports

The output of this transformer will vary depending on the action performed. Message data and metadata are presented as feature attributes.

  • After a Receive action, output features represent messages received from Azure Event Hub.
  • After a Send action, output features represent messages sent to Azure Event Hub.

The incoming feature is output through this port.

Features that cause the operation to fail are output through this port. An fme_rejection_code attribute, having the value ERROR_DURING_PROCESSING, will be added, along with a more descriptive fme_rejection_message attribute which contains more specific details as to the reason for the failure.

Note  If a feature comes in to the AzureEventHubsConnector already having a value for fme_rejection_code, this value will be removed.

Rejected Feature Handling: can be set to either terminate the translation or continue running when it encounters a rejected feature. This setting is available both as a default FME option and as a workspace parameter.

Parameters

Credential Source

Required for authentication. Using a web connection integrates best with FME, but in some cases, you may wish to use one of the other sources.

  • Web Connection - use an Azure Event Hubs web connection stored in the FME web connections database
  • Embedded - An event hub connection string

Account

Available when the credential source is Web Connection. To create an Azure Event Hubs connection, click the 'Account' drop-down box and select 'Add Web Connection...'.

The connection can then be managed via Tools -> FME Options... -> Web Connections.

Embedded Credentials

Event Hub Connection String

Available when the Credential Source is Embedded. The connection string is found in the Azure Portal Event Hubs Namespace under Shared Access Policies.

Action

The type of operation to perform. Choices are:

  • Receive
  • Send
  • Checkpoint

Event Hubs

The event hub to connect to.

Some parameters are variable, depending on the value of the Request > Action parameter.

Send Options

Payload

The content of the message.

This is often JSON, but can be any string, binary, integer or floating-point value.

Partition ID

(Optional) The specific partition ID to send to.

If empty, a message will be assigned to a random partition using round-robin.

Message Properties

(Optional) Additional properties to send with each message.

Key

The custom name of the property.

Value

The content of the property.

Receives messages from the front of the queue.

Checkpointing is also enabled, but optional.

Receive Options

Consumer Group

The name of the consumer group to view the event hub stream.

Consumer groups are created in the Azure portal. The default is ‘$Default’.

Receive Mode

Two message receiving options are available:

  • Stream: The connector continues to receive messages indefinitely. The translation needs to be terminated in order to stop reception.
  • Batch: Only a given number of messages are received before the connection is closed.
Batch Size

In Batch mode, specifies the number of messages to read per batch.

Partition ID

(Optional) If specified, the client will receive from this partition only.

If empty, the client will receive from all partitions.

It is recommended that there is only one active receiver on a partition per consumer group.

Prefetch Count

(Optional) The number of messages to prefetch from Azure.

Default is 300.

Starting Position

(Optional) Start receiving from this event position if there is no checkpoint data for the partition.

Checkpoint data will be used if available.

Default (empty) is @latest which receives only new events. -1 starts receiving at the beginning of the stream Can be a string, integer or a datetime.

Starting Position Mode

Determines whether the starting position is inclusive or not. Default is exclusive.

Checkpoint Store (Azure Blob) - Optional

See Parameters - Checkpoint Action for more details.

Container Name

The container name for the blob store.

Connection String

A connection string to an Azure Storage account.

Checkpoint Interval

(Optional) Submits a checkpoint store to Azure blob every nth message. The default checkpoints only at the end of the stream.

There will always be a checkpoint at the end of a message stream.

The checkpoint action manually checkpoints a message using the Azure Blob checkpoint store.

This option is used if there is post-processing of a message in a workspace in which you want the checkpoint to happen later after the message is received.

Checkpoint Options

Received Message ID

The _receive_id attribute from a receiving transformer (with the Receive action) used to identify a message to checkpoint.

Checkpoint Store (Azure blob)

Checkpoint store is optional for the Receive action and required for the Checkpoint action. It is used to store the partition load-balancing and checkpoint data when receiving events. Load balancing does not apply when receiving from a single partition.

If a checkpoint store is not provided, the checkpoint will be maintained internally in memory, and the client will receive events without load-balancing.

When used, a checkpoint store uses an Azure storage container to store offset information. The offset information is used to start receiving at the same position at the next receive.

Container Name

The container name for the blob store.

Connection String

A connection string to an Azure Storage account.

Checkpoint Interval

(Optional) Submits a checkpoint store to Azure blob every nth message. The default checkpoints only at the end of the stream.

There will always be a checkpoint at the end of a message stream.

The following attributes can be selected for inclusion on the output features. Each output feature represents a message that was either sent or received.

_payload

The message payload. UTF-8 string if possible to decode, otherwise binary or numeric.

_enqueued_time

The timestamp when the message was sent.

_offset

The offset of the message.

_partition_key

The partition of the message.

_properties

A key, value pair of message properties.

_receive_id

An id generated to identify the message used for the Checkpoint action.

_sequence_number

The sequence number of the message.

_system_properties

Metadata set by the Event Hubs Service associated with the message.

Editing Transformer Parameters

Using a set of menu options, transformer parameters can be assigned by referencing other elements in the workspace. More advanced functions, such as an advanced editor and an arithmetic editor, are also available in some transformers. To access a menu of these options, click beside the applicable parameter. For more information, see Transformer Parameter Menu Options.

Defining Values

There are several ways to define a value for use in a Transformer. The simplest is to simply type in a value or string, which can include functions of various types such as attribute references, math and string functions, and workspace parameters. There are a number of tools and shortcuts that can assist in constructing values, generally available from the drop-down context menu adjacent to the value field.

Using the Text Editor

The Text Editor provides a convenient way to construct text strings (including regular expressions) from various data sources, such as attributes, parameters, and constants, where the result is used directly inside a parameter.

Text Editor

Using the Arithmetic Editor

The Arithmetic Editor provides a convenient way to construct math expressions from various data sources, such as attributes, parameters, and feature functions, where the result is used directly inside a parameter.

Arithmetic Editor

Conditional Values

Set values depending on one or more test conditions that either pass or fail.

Parameter Condition Definition Dialog

Content

Expressions and strings can include a number of functions, characters, parameters, and more.

When setting values - whether entered directly in a parameter or constructed using one of the editors - strings and expressions containing String, Math, Date/Time or FME Feature Functions will have those functions evaluated. Therefore, the names of these functions (in the form @<function_name>) should not be used as literal string values.

String Functions

These functions manipulate and format strings.

Special Characters

 A set of control characters is available in the Text Editor.

Math Functions

Math functions are available in both editors.
Date/Time Functions Date and time functions are available in the Text Editor.

Math Operators

These operators are available in the Arithmetic Editor.

FME Feature Functions

These return primarily feature-specific values.

FME Parameters

FME and workspace-specific parameters may be used.
Creating and Modifying User Parameters Create your own editable parameters.

Dialog Options - Tables

Transformers with table-style parameters have additional tools for populating and manipulating values.

Row Reordering

Enabled once you have clicked on a row item. Choices include:

  • Add a row
  • Remove a row
  • Move current row up one
  • Move current row down one
  • Move current row to top
  • Move current row to bottom

Cut, Copy, and Paste

Enabled once you have clicked on a row item. Choices include:

  • Cut a row - delete and copy to clipboard
  • Copy a row to the clipboard
  • Paste a row from the clipboard

Cut, copy, and paste may be used within a transformer, or between transformers.

Filter

Start typing a string, and the matrix will only display rows matching those characters. Searches all columns. This only affects the display of attributes within the transformer - it does not alter which attributes are output.

Import

Import populates the table with a set of new attributes read from a dataset. Specific application varies between transformers.

Reset/Refresh

Generally resets the table to its initial state, and may provide additional options to remove invalid entries. Behavior varies between transformers.

Note: Not all tools are available in all transformers.

Reference

Processing Behavior

Feature-Based

Feature Holding

No
Dependencies Microsoft Azure Account with the Event Hubs Service
Aliases  
History  

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Examples may contain information licensed under the Open Government Licence – Vancouver and/or the Open Government Licence – Canada.