GoogleCloudPubSubConnector

Connects to Google Cloud Pub/Sub to create topics and subscriptions or send and receive messages.

Typical Uses

Sending and receiving messages
Creating topics and subscriptions

How does it work?

The GoogleCloudPubSubConnector uses your account credentials to connect to Pub/Sub and perform various tasks:

Action	Task
Receive	Receive messages from a subscription.
Send	Send messages to a topic.

Optional Input Port

This transformer has two modes, depending on whether a connector is attached to the Input port or not:

Input-driven: When input features are connected, the transformer runs once for each feature it receives in the Input port.
Run Once: When no input features are connected, the transformer runs one time.

When the Input port is in use, the Initiator output port is also enabled.

Heartbeat

When Action is Receive and the connection is still alive (Receive Mode is Stream or a batch is not yet complete), heartbeat features are output at a specified interval after a period of non-activity.

Heartbeat features have two attributes:

_heartbeat_id: Integer starting at 0. This is a unique identifier for each heartbeat feature output from this port.
_heartbeat_counter: Integer starting at 0 that resets whenever the connector receives a new message and a new period of inactivity begins. This counter represents the number of consecutive heartbeat features.

Configuration

Input Ports

Output Ports

Output

Features with added attributes, as specified in parameters and according to Action:

Action	Output - Input-Driven	Output - Run Once
Receive	Multiple features, one for each message received, with details about the message.	Multiple features, one for each message received, with details about the message.
Send	Input feature with details about the sent message.	New feature with details about the sent message.

Parameters

Authentication

Credential Source

Select the type of credentials to use:

Web Connection (Recommended): Use a Google Cloud web connection.
Service Account Key File: Use credentials already configured on the system, in the key file specified in the environment variable GOOGLE_APPLICATION_CREDENTIALS.

Account

When Credential Source is Web Connection, select or create a Web Connection connecting to a Google Cloud Web Service.

See Using Web Connections.

Project ID

Specify the Google Cloud project ID.

Action > Receive

Subscription

Specify the subscription to subscribe to.

A topic may have multiple subscriptions.

Create Subscription

Select an action to perform if the specified Subscription does not exist:

Yes: Create a new subscription.
No: Output the feature via the <Rejected> port.

Create Subscription Options

When Create Subscription is Yes:

Topic

Specify the topic for the new subscription.

Acknowledgment Deadline (secs)

Specify the approximate amount of time that the service waits for the subscriber to acknowledge receipt of the message before resending.

Default and minimum is 10 seconds. Maximum is 10 minutes.

Receive Options

Mode

Select a message receiving method:

Stream: The connector continues to receive messages indefinitely. The translation must be terminated to stop receiving.
Batch: Only a given number of messages are received before the connection is closed.

Max Number of Messages

When Mode is Batch, specify the number of messages to read per batch.

Encoding

Select the message encoding.

The default encoding, Binary (fme-binary), preserves the raw bytes received from the server.

If an alternate encoding is selected, the connector will attempt to convert the message to a string using that encoding.

Heartbeat

Interval

Specify the duration of a period of inactivity before a heartbeat feature is emitted, in Time Units.

Default is 1.

Time Unit

Select the Interval unit:

Seconds
Minutes
Hours (default)
Days

Output Attributes

Attributes to Add

Select any available attributes to be included on the output features:

_attributes{}.key _attributes{}.value	Structured list attributes containing the header keys and values of a received message. Note that the order of attributes may be arbitrary.
_id	The message id.
_timestamp	The message creation timestamp. Note that timestamps for sent messages are not available.
_value	The message content.

Action > Send

Topics

Specify the topics to send the message to.

Multiple topics are space-separated.

Create Missing Topics

Select an action to perform if the specified Topic does not exist:

Yes: Create a new topic.
No: Output the feature via the <Rejected> port.

Send Options

Message Value

Provide the message content.

This must be a string or binary value and must match the selected Encoding.

Encoding

Select the message content encoding.

Attributes

(Optional) Set any additional attributes for the message. An attribute has a key and a value, which may be text strings or byte strings.

Output Attributes

Attributes to Add

Select any available attributes to be included on the output features:

_attributes{}.key _attributes{}.value	Structured list attributes containing the header keys and values of a received message. Note that the order of attributes may be arbitrary.
_id	The message id.
_value	The message content.

Editing Transformer Parameters

Transformer parameters can be set by directly entering values, using expressions, or referencing other elements in the workspace such as attribute values or user parameters. Various editors and context menus are available to assist. To see what is available, click beside the applicable parameter.

How to Set Parameter Values

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.

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.

Content Types

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

Table Tools

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.

For more information, see Transformer Parameter Menu Options.

Reference

Processing Behavior	Feature-Based
Feature Holding	No
Dependencies	Google Cloud account
Aliases
History	Released FME 2019.0

FME Online Resources

The FME Community and Support Center Knowledge Base have a wealth of information, including active forums with 35,000+ members and thousands of articles.

Search for all results about the GoogleCloudPubSubConnector on the FME Community.

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