MQTTConnector
Connects to an MQTT broker. Supports sending (producing) and receiving (consuming) messages.
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.
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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:
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QoS Level |
The MQTT protocol allows a Quality of Service (QoS) level to be set. The following levels are available:
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:
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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.
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.
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.
These functions manipulate and format strings. | |
Special Characters |
A set of control characters is available in the Text Editor. |
Math functions are available in both editors. | |
Date/Time Functions | Date and time functions are available in the Text Editor. |
These operators are available in the Arithmetic Editor. | |
These return primarily feature-specific values. | |
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
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Enabled once you have clicked on a row item. Choices include:
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Cut, Copy, and Paste
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Enabled once you have clicked on a row item. Choices include:
Cut, copy, and paste may be used within a transformer, or between transformers. |
Filter
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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
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Import populates the table with a set of new attributes read from a dataset. Specific application varies between transformers. |
Reset/Refresh
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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 |
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Feature Holding |
No |
Dependencies | |
Aliases | |
History | Released FME 2019.0 |
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Examples may contain information licensed under the Open Government Licence – Vancouver and/or the Open Government Licence – Canada.