MQTTConnector

Categories

Web

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Connects to an MQTT broker. Supports sending (producing) and receiving (consuming) messages.

Jump to Configuration

Typical Uses

  • Geoenrichment of data on an MQTT topic
  • Aggregation of data from MQTT topics and other message streams
  • Interoperability with Big Data analytics platforms

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 the broker.
  • After a Send action, output features represent messages sent to the broker.

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 MQTTConnector 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

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 MQTT web connection stored in the FME web connections database
  • Embedded - embed username and password as parameters in the transformer
Account

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

The connection can then be managed via Tools -> FME Options... -> Web Connections.
Broker URL, Broker Port Available when the credential source is Embedded. The broker URL and port allow FME to connect to the broker.
Enable SSL/TLS Available when the credential source is Embedded. Whether to use a secure connection. Secure connections typically use port 8883, while insecure connections typically use port 1883.
User Name, Password Available when the credential source is Embedded. The username and password to use when connecting to the broker. These are optional, allowing for anonymous access.
CA Certificate

Root CA certificate for broker.

Optional.
Client Certificate

Certificate for client authentication.

Optional.
Client Private Key

Private key for client authentication.

Optional.
Client ID

The client ID uniquely identifies the FME client to the broker. Some brokers require pre-registration of client IDs, while others allow the client to register ad-hoc.
Action

The type of operation to perform. Choices are:

  • Receive
  • Send
QoS Level

The MQTT protocol allows a Quality of Service (QoS) level to be set. The following levels are available:

  • At most once (level 0)
  • At least once (level 1)
  • Exactly once (level 2)

The QoS guarantees are achieved by performing differing levels of client-server handshake. As a result, higher QoS levels are expected to lower throughput.

The remaining parameters available depend on the value of the Request > Action parameter. Parameters for each Action are detailed below.

Receive Options

Topic

The topic to receive from. Topics are usually hierarchical, and can contain the wildcard `#` and `+`. For more information about topic format, please see the following MQTT wiki page: https://github.com/mqtt/mqtt.github.io/wiki/topic_format

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.

Send Options

Topic

The topic to send to. Topics are usually hierarchical, and can contain the wildcard `#` and `+`. For more information about topic format, please see the following MQTT wiki page: https://github.com/mqtt/mqtt.github.io/wiki/topic_format

Payload

The content of the message. This is often JSON, but can be any string, binary, integer or floating-point value.

Retain Message

Whether to set the message as the retained "last known good" value for the topic. Note that not all brokers support this setting.

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

_message_id

The sequential identifier for the message.

_payload

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

_topic

The topic the message received from or sent to.

_qos

The quality of service level with which the message was sent or received.

_retain

Whether the received message was the last retained value (Yes), or a live message (No).

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  
FME Licensing Level FME Base Edition and above
Aliases  
History Released FME 2019.0

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Examples may contain information licensed under the Open Government Licence – Vancouver