Pub/Sub

The Cloud Pub/Sub connector lets you perform insert, delete, update, and read operations on Google Cloud Pub/Sub data.

Before you begin

Before using the Pub/Sub connector, do the following tasks:

In your Google Cloud project:
- Grant the roles/connectors.admin IAM role to the user configuring the connector.
- Grant the following IAM roles to the service account that you want to use for the connector:
  - roles/pubsub.publisher
  A service account is a special type of Google account intended to represent a non-human user that needs to authenticate and be authorized to access data in Google APIs. If you don't have a service account, you must create a service account. For more information, see Creating a service account.
- Enable the following services:
  - secretmanager.googleapis.com (Secret Manager API)
  - connectors.googleapis.com (Connectors API)
  To understand how to enable services, see Enabling services.
If these services or permissions have not been enabled for your project previously, you are prompted to enable them when configuring the connector.

Configure the connector

Configuring the connector requires you to create a connection to your data source (backend system). A connection is specific to a data source. It means that if you have many data sources, you must create a separate connection for each data source. To create a connection, do the following steps:

In the Cloud console, go to the Integration Connectors > Connections page and then select or create a Google Cloud project.
Go to the Connections page
Click + CREATE NEW to open the Create Connection page.
In the Location section, choose the location for the connection.
1. Region: Select a location from the drop-down list.
  For the list of all the supported regions, see Locations.
2. Click NEXT.
In the Connection Details section, complete the following:
1. Connector: Select Pub/Sub from the drop down list of available Connectors.
2. Connector version: Select the Connector version from the drop down list of available versions.
3. In the Connection Name field, enter a name for the Connection instance.
  Connection names must meet the following criteria:
  - Connection names can use letters, numbers, or hyphens.
  - Letters must be lower-case.
  - Connection names must begin with a letter and end with a letter or number.
  - Connection names cannot exceed 63 characters.
4. Optionally, enter a Description for the connection instance.
5. Service Account: Select a service account that has the required roles.
6. Optionally, configure the Connection node settings:
  - Minimum number of nodes: Enter the minimum number of connection nodes.
  - Maximum number of nodes: Enter the maximum number of connection nodes.
  A node is a unit (or replica) of a connection that processes transactions. More nodes are required to process more transactions for a connection and conversely, fewer nodes are required to process fewer transactions. To understand how the nodes affect your connector pricing, see Pricing for connection nodes. If you don't enter any values, by default the minimum nodes are set to 2 (for better availability) and the maximum nodes are set to 50.
7. Project ID: Google Cloud project ID where the Pub/Sub instance resides.
8. Topic ID: Optionally, enter the name of the Pub/Sub topic where the message should be published.
  If you don't specify a topic name here, you can specify the topic at runtime by configuring the topic parameter in the PublishMessage action.
9. Optionally, click + ADD LABEL to add a label to the Connection in the form of a key/value pair.
10. Click NEXT.
In the Authentication section, enter the authentication details.
1. The Pub/Sub connection doesn't require any authentication.
2. Click NEXT.
Review: Review your connection and authentication details.
Click Create.

Entities, operations, and actions

All the Integration Connectors provide a layer of abstraction for the objects of the connected application. You can access an application's objects only through this abstraction. The abstraction is exposed to you as entities, operations, and actions.

Entity: An entity can be thought of as an object, or a collection of properties, in the connected application or service. The definition of an entity differs from a connector to a connector. For example, in a database connector, tables are the entities, in a file server connector, folders are the entities, and in a messaging system connector, queues are the entities.
However, it is possible that a connector doesn't support or have any entities, in which case the Entities list will be empty.
Operation: An operation is the activity that you can perform on an entity. You can perform any of the following operations on an entity:
- List
- Get
- Create
- Update
- Delete
Selecting an entity from the available list, generates a list of operations available for the entity. For a detailed description of the operations, see the Connectors task's entity operations. However, if a connector doesn't support any of the entity operations, such unsupported operations aren't listed in the Operations list.
Action: An action is a first class function that is made available to the integration through the connector interface. An action lets you make changes to an entity or entities, and vary from connector to connector. However, it is possible that a connector doesn't support any action, in which case the Actions list will be empty.

System limitations

The Pub/Sub connector can process a maximum of 27 transactions per second, per node, and throttles any transactions beyond this limit. By default, Integration Connectors allocates 2 nodes (for better availability) for a connection.

For information on the limits applicable to Integration Connectors, see Limits.

Note: The number of Integration Connectors nodes will autoscale dynamically based on your usage. However, if you want to reserve capacity for large volumes without waiting for autoscaling, you can adjust the minimum node value for a connection. More nodes are required to process more transactions for a connection. Conversely, fewer nodes are required if a connection processes fewer transactions. To configure the node values, do the following:

If you are a pay-as-you-go customer, configure the minimum and maximum node value in the edit connection page.
If you are a subscription based customer, contact support.

The maximum transactions that a node can handle depends on various factors. So, before adjusting the minimum nodes for better throughput, it is recommended you check if your backend systems are set up optimally to handle the required traffic.

Actions

This section describes the actions supported by the Pub/Sub connector.

PublishMessage action

This action publishes a message to a Pub/Sub topic. The following table describes the input parameters of the PublishMessage action.

Parameter name	Required	Data type	Description
topic	No	String	Name of the topic to which you want to publish the message.
message	Yes	String	The message you want to publish. The message should be a stringified JSON and the maximum message size supported is 10 MB.
attributes	No	String	Custom metadata (in the form of stringified JSON) as key-value pairs.

Note: The results of all the entity operations and actions will be available as a JSON response in the Connectors task's connectorOutputPayload response parameter after you run your integration.

Schema validation for messages

When you create a topic in Pub/Sub, you can choose to assign the topic a new or an existing schema. For more information, see create and manage schemas in Pub/Sub. If you have assigned a schema to a topic, your published messages are automatically validated against the schema and if a message doesn't confirm to the schema, the message isn't published.

Examples

This examples in this section describe the following operations:

Publish a message to a topic

The following table lists the sample scenarios and the corresponding configuration in the Connectors task:

Task Configuration

Publish a message to a topic

Task	Configuration
Publish a message to a topic	In the `Configure connector task` dialog, click `Actions`. Select the `PublishMessage` action, and then click Done. In the Task Input section of the Connectors task, click `connectorInputPayload` and then enter a value similar to the following in the `Default Value` field: {"message" : "This is a test message.", "topic":"mytopic", "attributes":"{\"key1\":\"value1\"}"} Click Save. This example publishes the specified `message` to the `mytopic` topic. Running this example, returns a response smiliar to the following in the Connector task's `connectorOutputPayload` output variable: {"messageIds": [ "7865292560686229"]}

In the Configure connector task dialog, click Actions.
Select the PublishMessage action, and then click Done.
In the Task Input section of the Connectors task, click connectorInputPayload and then enter a value similar to the following in the Default Value field:
```
{"message" : "This is a test message.",
"topic":"mytopic",
"attributes":"{\"key1\":\"value1\"}"}
```
Click Save.

This example publishes the specified message to the mytopic topic.

Running this example, returns a response smiliar to the following in the Connector task's connectorOutputPayload output variable:

{"messageIds": [
"7865292560686229"]}

Use terraform to create connections

You can use the Terraform resource to create a new connection.

To learn how to apply or remove a Terraform configuration, see Basic Terraform commands.

To view a sample terraform template for connection creation, see sample template.

When creating this connection by using Terraform, you must set the following variables in your Terraform configuration file:

Parameter name	Data type	Required	Description
project_id	STRING	True	Google Cloud project ID where the Pub/Sub instance resides.
topic_id	STRING	False	Name of the Pub/Sub topic where the message should be published.

Use the Pub/Sub connection in an integration

After you create the connection, it becomes available in both Apigee Integration and Application Integration. You can use the connection in an integration through the Connectors task.

To understand how to create and use the Connectors task in Apigee Integration, see Connectors task.
To understand how to create and use the Connectors task in Application Integration, see Connectors task.

Get help from the Google Cloud community

You can post your questions and discuss this connector in the Google Cloud community at Cloud Forums.

What's next

Understand how to suspend and resume a connection.
Understand how to monitor connector usage.
Understand how to view connector logs.