Pub/Sub client libraries

This page shows how to get started with the Cloud Client Libraries for the Pub/Sub API. Client libraries make it easier to access Google Cloud APIs from a supported language. Although you can use Google Cloud APIs directly by making raw requests to the server, client libraries provide simplifications that significantly reduce the amount of code you need to write.

Read more about the Cloud Client Libraries and the older Google API Client Libraries in Client libraries explained .

Install the client library

C++

For information about this client library's requirements and install dependencies, see Setting up a C++ development environment .

C#

Install-Package Google.Cloud.PubSub.V1 -Pre

For more information, see Setting Up a C# Development Environment .

Go

go get cloud.google.com/go/pubsub

For more information, see Setting Up a Go Development Environment .

Java

If you are using Maven , add the following to your pom.xml file. For more information about BOMs, see The Google Cloud Platform Libraries BOM .

 < dependencyManagement 
>  
< dependencies 
>  
< dependency 
>  
< groupId>com 
 . 
 google 
 . 
 cloud 
< / 
 groupId 
>  
< artifactId>libraries 
 - 
 bom 
< / 
 artifactId 
>  
< version>26 
 . 
 66 
 . 
 0 
< / 
 version 
>  
< type>pom 
< / 
 type 
>  
< scope>import 
< / 
 scope 
>  
< /dependency 
> </ 
 dependencies 
>
< /dependencyManagement 
>

< dependencies 
> <dependency> 
 <groupId>com.google.cloud</ 
 groupId 
>  
< artifactId>google 
 - 
 cloud 
 - 
 pubsub 
< / 
 artifactId 
>  
< /dependency 
>

< / 
 dependencies 
>

If you are using Gradle , add the following to your dependencies:

  implementation 
  
 platform 
 ( 
 'com.google.cloud:libraries-bom:26.66.0' 
 ) 
 implementation 
  
 'com.google.cloud:google-cloud-pubsub'

If you are using sbt , add the following to your dependencies:

  libraryDependencies 
  
 += 
  
 "com.google.cloud" 
  
 % 
  
 "google-cloud-pubsub" 
  
 % 
  
 "1.141.3"

If you're using Visual Studio Code, IntelliJ, or Eclipse, you can add client libraries to your project using the following IDE plugins:

The plugins provide additional functionality, such as key management for service accounts. Refer to each plugin's documentation for details.

For more information, see Setting Up a Java Development Environment .

Node.js

npm install @google-cloud/pubsub

For more information, see Setting Up a Node.js Development Environment .

PHP

composer require google/cloud-pubsub

For more information, see Using PHP on Google Cloud .

Python

pip install --upgrade google-cloud-pubsub

For more information, see Setting Up a Python Development Environment .

Ruby

gem install google-cloud-pubsub

For more information, see Setting Up a Ruby Development Environment .

Set up authentication

To authenticate calls to Google Cloud APIs, client libraries support Application Default Credentials (ADC) ; the libraries look for credentials in a set of defined locations and use those credentials to authenticate requests to the API. With ADC, you can make credentials available to your application in a variety of environments, such as local development or production, without needing to modify your application code.

For production environments, the way you set up ADC depends on the service and context. For more information, see Set up Application Default Credentials .

For a local development environment, you can set up ADC with the credentials that are associated with your Google Account:

Install the Google Cloud CLI. After installation, initialize the Google Cloud CLI by running the following command:
```
gcloud  
init
```
If you're using an external identity provider (IdP), you must first sign in to the gcloud CLI with your federated identity .
If you're using a local shell, then create local authentication credentials for your user account:
```
gcloud  
auth  
application-default  
login
```
You don't need to do this if you're using Cloud Shell.

If an authentication error is returned, and you are using an external identity provider (IdP), confirm that you have signed in to the gcloud CLI with your federated identity .

A sign-in screen appears. After you sign in, your credentials are stored in the local credential file used by ADC .

Use the client library

The following example shows how to use the client library to create a Pub/Sub topic.

C++

  namespace 
  
 pubsub 
  
 = 
  
 :: 
 google 
 :: 
 cloud 
 :: 
 pubsub 
 ; 
 namespace 
  
 pubsub_admin 
  
 = 
  
 :: 
 google 
 :: 
 cloud 
 :: 
 pubsub_admin 
 ; 
 []( 
 pubsub_admin 
 :: 
 TopicAdminClient 
  
 client 
 , 
  
 std 
 :: 
 string 
  
 project_id 
 , 
  
 std 
 :: 
 string 
  
 topic_id 
 ) 
  
 { 
  
 auto 
  
 topic 
  
 = 
  
 client 
 . 
 CreateTopic 
 ( 
  
 pubsub 
 :: 
 Topic 
 ( 
 std 
 :: 
 move 
 ( 
 project_id 
 ), 
  
 std 
 :: 
 move 
 ( 
 topic_id 
 )). 
 FullName 
 ()); 
  
 // Note that kAlreadyExists is a possible error when the library retries. 
  
 if 
  
 ( 
 topic 
 . 
 status 
 (). 
 code 
 () 
  
 == 
  
 google 
 :: 
 cloud 
 :: 
 StatusCode 
 :: 
 kAlreadyExists 
 ) 
  
 { 
  
 std 
 :: 
 cout 
 << 
 "The topic already exists 
 \n 
 " 
 ; 
  
 return 
 ; 
  
 } 
  
 if 
  
 ( 
 ! 
 topic 
 ) 
  
 throw 
  
 std 
 :: 
 move 
 ( 
 topic 
 ). 
 status 
 (); 
  
 std 
 :: 
 cout 
 << 
 "The topic was successfully created: " 
 << 
 topic 
 - 
> DebugString 
 () 
 << 
 " 
 \n 
 " 
 ; 
 }

C#

  using 
  
  Google.Cloud.PubSub.V1 
 
 ; 
 using 
  
  Grpc.Core 
 
 ; 
 using 
  
 System 
 ; 
 public 
  
 class 
  
 CreateTopicSample 
 { 
  
 public 
  
 Topic 
  
 CreateTopic 
 ( 
 string 
  
 projectId 
 , 
  
 string 
  
 topicId 
 ) 
  
 { 
  
  PublisherServiceApiClient 
 
  
 publisher 
  
 = 
  
  PublisherServiceApiClient 
 
 . 
  Create 
 
 (); 
  
 var 
  
 topicName 
  
 = 
  
  TopicName 
 
 . 
  FromProjectTopic 
 
 ( 
 projectId 
 , 
  
 topicId 
 ); 
  
  Topic 
 
  
 topic 
  
 = 
  
 null 
 ; 
  
 try 
  
 { 
  
 topic 
  
 = 
  
 publisher 
 . 
  CreateTopic 
 
 ( 
 topicName 
 ); 
  
 Console 
 . 
 WriteLine 
 ( 
 $"Topic {topic. Name 
} created." 
 ); 
  
 } 
  
 catch 
  
 ( 
  RpcException 
 
  
 e 
 ) 
  
 when 
  
 ( 
 e 
 . 
  Status 
 
 . 
  StatusCode 
 
  
 == 
  
  StatusCode 
 
 . 
  AlreadyExists 
 
 ) 
  
 { 
  
 Console 
 . 
 WriteLine 
 ( 
 $"Topic {topicName} already exists." 
 ); 
  
 } 
  
 return 
  
 topic 
 ; 
  
 } 
 }

Go

  // Sample pubsub-quickstart creates a Google Cloud Pub/Sub topic. 
 package 
  
 main 
 import 
  
 ( 
  
 "context" 
  
 "fmt" 
  
 "log" 
  
 "cloud.google.com/go/pubsub/v2" 
  
 "cloud.google.com/go/pubsub/v2/apiv1/pubsubpb" 
 ) 
 func 
  
 main 
 () 
  
 { 
  
 ctx 
  
 := 
  
 context 
 . 
 Background 
 () 
  
 // Sets your Google Cloud Platform project ID. 
  
 projectID 
  
 := 
  
 "YOUR_PROJECT_ID" 
  
 // Creates a client. 
  
 client 
 , 
  
 err 
  
 := 
  
 pubsub 
 . 
 NewClient 
 ( 
 ctx 
 , 
  
 projectID 
 ) 
  
 if 
  
 err 
  
 != 
  
 nil 
  
 { 
  
 log 
 . 
 Fatalf 
 ( 
 "Failed to create client: %v" 
 , 
  
 err 
 ) 
  
 } 
  
 defer 
  
 client 
 . 
 Close 
 () 
  
 // Sets the id for the new topic. 
  
 topicID 
  
 := 
  
 "my-topic" 
  
 pbTopic 
  
 := 
  
& pubsubpb 
 . 
 Topic 
 { 
  
 Name 
 : 
  
 fmt 
 . 
 Sprintf 
 ( 
 "projects/%s/topics/%s" 
 , 
  
 projectID 
 , 
  
 topicID 
 ), 
  
 } 
  
 // Creates the new topic. 
  
 topic 
 , 
  
 err 
  
 := 
  
 client 
 . 
 TopicAdminClient 
 . 
 CreateTopic 
 ( 
 ctx 
 , 
  
 pbTopic 
 ) 
  
 if 
  
 err 
  
 != 
  
 nil 
  
 { 
  
 log 
 . 
 Fatalf 
 ( 
 "Failed to create topic: %v" 
 , 
  
 err 
 ) 
  
 } 
  
 fmt 
 . 
 Printf 
 ( 
 "Topic %v created.\n" 
 , 
  
 topic 
 ) 
 }

Java

  import 
  
 com.google.cloud.pubsub.v1. TopicAdminClient 
 
 ; 
 import 
  
 com.google.pubsub.v1. Topic 
 
 ; 
 import 
  
 com.google.pubsub.v1. TopicName 
 
 ; 
 import 
  
 java.io.IOException 
 ; 
 public 
  
 class 
 CreateTopicExample 
  
 { 
  
 public 
  
 static 
  
 void 
  
 main 
 ( 
 String 
 ... 
  
 args 
 ) 
  
 throws 
  
 Exception 
  
 { 
  
 // TODO(developer): Replace these variables before running the sample. 
  
 String 
  
 projectId 
  
 = 
  
 "your-project-id" 
 ; 
  
 String 
  
 topicId 
  
 = 
  
 "your-topic-id" 
 ; 
  
 createTopicExample 
 ( 
 projectId 
 , 
  
 topicId 
 ); 
  
 } 
  
 public 
  
 static 
  
 void 
  
 createTopicExample 
 ( 
 String 
  
 projectId 
 , 
  
 String 
  
 topicId 
 ) 
  
 throws 
  
 IOException 
  
 { 
  
 try 
  
 ( 
  TopicAdminClient 
 
  
 topicAdminClient 
  
 = 
  
  TopicAdminClient 
 
 . 
 create 
 ()) 
  
 { 
  
  TopicName 
 
  
 topicName 
  
 = 
  
  TopicName 
 
 . 
 of 
 ( 
 projectId 
 , 
  
 topicId 
 ); 
  
  Topic 
 
  
 topic 
  
 = 
  
 topicAdminClient 
 . 
 createTopic 
 ( 
 topicName 
 ); 
  
 System 
 . 
 out 
 . 
 println 
 ( 
 "Created topic: " 
  
 + 
  
 topic 
 . 
  getName 
 
 ()); 
  
 } 
  
 } 
 }

Node.js

  // Imports the Google Cloud client library 
 const 
  
 { 
 PubSub 
 } 
  
 = 
  
 require 
 ( 
 ' @google-cloud/pubsub 
' 
 ); 
 async 
  
 function 
  
 quickstart 
 ( 
  
 projectId 
  
 = 
  
 'your-project-id' 
 , 
  
 // Your Google Cloud Platform project ID 
  
 topicNameOrId 
  
 = 
  
 'my-topic' 
 , 
  
 // Name for the new topic to create 
  
 subscriptionName 
  
 = 
  
 'my-sub' 
 , 
  
 // Name for the new subscription to create 
 ) 
  
 { 
  
 // Instantiates a client 
  
 const 
  
 pubsub 
  
 = 
  
 new 
  
  PubSub 
 
 ({ 
 projectId 
 }); 
  
 // Creates a new topic 
  
 const 
  
 [ 
 topic 
 ] 
  
 = 
  
 await 
  
 pubsub 
 . 
 createTopic 
 ( 
 topicNameOrId 
 ); 
  
 console 
 . 
 log 
 ( 
 `Topic 
 ${ 
 topic 
 . 
 name 
 } 
 created.` 
 ); 
  
 // Creates a subscription on that new topic 
  
 const 
  
 [ 
 subscription 
 ] 
  
 = 
  
 await 
  
 topic 
 . 
 createSubscription 
 ( 
 subscriptionName 
 ); 
  
 // Receive callbacks for new messages on the subscription 
  
 subscripti on 
 
 . 
  on 
 
 ( 
 'message' 
 , 
  
 message 
  
 = 
>  
 { 
  
 console 
 . 
 log 
 ( 
 'Received message:' 
 , 
  
 message 
 . 
 data 
 . 
 toString 
 ()); 
  
 process 
 . 
 exit 
 ( 
 0 
 ); 
  
 }); 
  
 // Receive callbacks for errors on the subscription 
  
 subscripti on 
 
 . 
  on 
 
 ( 
 'error' 
 , 
  
 error 
  
 = 
>  
 { 
  
 console 
 . 
 error 
 ( 
 'Received error:' 
 , 
  
 error 
 ); 
  
 process 
 . 
 exit 
 ( 
 1 
 ); 
  
 }); 
  
 // Send a message to the topic 
  
 await 
  
 topic 
 . 
  publishMessage 
 
 ({ 
 data 
 : 
  
 Buffer 
 . 
  from 
 
 ( 
 'Test message!' 
 )}); 
 }

Python

  from 
  
 google.cloud 
  
 import 
 pubsub_v1 
 # TODO(developer) 
 # project_id = "your-project-id" 
 # topic_id = "your-topic-id" 
 publisher 
 = 
 pubsub_v1 
 . 
  PublisherClient 
 
 () 
 topic_path 
 = 
 publisher 
 . 
 topic_path 
 ( 
 project_id 
 , 
 topic_id 
 ) 
 topic 
 = 
 publisher 
 . 
 create_topic 
 ( 
 request 
 = 
 { 
 "name" 
 : 
 topic_path 
 }) 
 print 
 ( 
 f 
 "Created topic: 
 { 
 topic 
 . 
 name 
 } 
 " 
 )

Ruby

  # Imports the Google Cloud client library 
 require 
  
 "google/cloud/pubsub" 
 # Instantiates a client 
 pubsub 
  
 = 
  
 Google 
 :: 
 Cloud 
 :: 
  PubSub 
 
 . 
  new 
 
 topic_admin 
  
 = 
  
 pubsub 
 . 
  topic_admin 
 
 # The name for the new topic 
 # topic_id = "your-topic-id" 
 # Creates the new topic 
 topic 
  
 = 
  
 topic_admin 
 . 
 create_topic 
  
 name 
 : 
  
 pubsub 
 . 
 topic_path 
 ( 
 topic_id 
 ) 
 puts 
  
 "Topic 
 #{ 
 topic 
 . 
 name 
 } 
 created."

Additional resources

C++

The following list contains links to more resources related to the client library for C++:

C#

The following list contains links to more resources related to the client library for C#:

Go

The following list contains links to more resources related to the client library for Go:

Java

The following list contains links to more resources related to the client library for Java:

Node.js

The following list contains links to more resources related to the client library for Node.js:

PHP

The following list contains links to more resources related to the client library for PHP:

Python

The following list contains links to more resources related to the client library for Python:

Ruby

The following list contains links to more resources related to the client library for Ruby:

Additional Pub/Sub API libraries

Language	Library
Java	java-pubsub-group-kafka-connector

Pub/Sub client libraries Stay organized with collections Save and categorize content based on your preferences.

Install the client library

C++

C#

Go

Java

Node.js

PHP

Python

Ruby

Set up authentication

Use the client library

C++

C#

Go

Java

Node.js

Python

Ruby

Additional resources

C++

C#

Go

Java

Node.js

PHP

Python

Ruby

Additional Pub/Sub API libraries

Pub/Sub client libraries