GoogleCloudPubSubConnector

Categories

Web

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

Jump to Configuration

Typical Uses

  • Processing of event logging
  • 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 subscription.
  • After a Send action, output features represent messages sent to the topic.

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 GoogleCloudPubSubConnector 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 a key file.

  • Web Connection - Use a Google Cloud web connection stored in the FME web connections database
  • Service Account Key File - Use credentials json configured on the system, from the environment variable GOOGLE_APPLICATION_CREDENTIALS
Account

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

The connection can then be managed via Tools > FME Options... > Web Connections.
Project ID The Google Cloud project ID.
Action

The type of operation to perform. Choices are:

  • Receive
  • Send

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

Subscription

Subscription

The subscription to subscribe to messages. A topic can have multiple subscriptions.

Create Subscription

If Yes is selected, the subscription will be created automatically with the following subscription options.

Create Subscription Options

Topic

The topic to subscribe to.

Acknowledgment Deadline (secs)

The approximate amount of time that the service waits for the subscriber to acknowledge receipt of the message before resending. The default and minimum is 10 seconds. The maximum is 10 minutes.

Receive Messages Options

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. A timeout error occurs if no messages are received.

Max Number of Messages

In Batch mode, up to the specified number of messages. Often the service will return less.

Encoding

By default, the _value attribute contains the raw bytes received from the server. If an encoding is selected, the connector will instead attempt to decode the value of received message to a string using the selected encoding.

Topics

Topics

The topics where the message is sent. Multiple topics are space separated.

Create Missing Topics

If Yes is selected, topics will be created automatically if they do not exist.

Send Messages Options

Message Value

The actual message data. This must be a string or binary value. The value must match the encoding type.

Encoding

The encoding of the message value. The encoding must be appropriate for the message value.

Attributes

Additional attributes for the message. An attribute has a key and a value, which may be text strings or byte strings.

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

_id

The id of the message

_value

The value of the message

_timestamp

The message creation timestamp. Note that timestamps for sent messages are not available.

_partition

The partition the message is stored in

_attributes{}.name
_attributes{}.value

Structured list attributes containing the header keys and values of a received message. Note that the order of attributes may be arbitrary.

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 Google Cloud account
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