Subscribe with synchronous pull

Uses synchronous pull to receive messages.

Explore further

For detailed documentation that includes this code sample, see the following:

Receive messages from a pull subscription

Code sample

C++

Before trying this sample, follow the C++ setup instructions in the Pub/Sub quickstart using client libraries . For more information, see the Pub/Sub C++ API reference documentation .

To authenticate to Pub/Sub, set up Application Default Credentials. For more information, see Set up authentication for a local development environment .

  []( 
 google 
 :: 
 cloud 
 :: 
 pubsub 
 :: 
 Subscriber 
  
 subscriber 
 ) 
  
 { 
  
 auto 
  
 response 
  
 = 
  
 subscriber 
 . 
 Pull 
 (); 
  
 if 
  
 ( 
 ! 
 response 
 ) 
  
 throw 
  
 std 
 :: 
 move 
 ( 
 response 
 ). 
 status 
 (); 
  
 std 
 :: 
 cout 
 << 
 "Received message " 
 << 
 response 
 - 
> message 
 << 
 " 
 \n 
 " 
 ; 
  
 std 
 :: 
 move 
 ( 
 response 
 - 
> handler 
 ). 
 ack 
 (); 
 }

C#

Before trying this sample, follow the C# setup instructions in the Pub/Sub quickstart using client libraries . For more information, see the Pub/Sub C# API reference documentation .

To authenticate to Pub/Sub, set up Application Default Credentials. For more information, see Set up authentication for a local development environment .

  using 
  
  Google.Cloud.PubSub.V1 
 
 ; 
 using 
  
  Grpc.Core 
 
 ; 
 using 
  
 System 
 ; 
 using 
  
 System.Linq 
 ; 
 using 
  
 System.Threading 
 ; 
 public 
  
 class 
  
 PullMessagesSyncSample 
 { 
  
 public 
  
 int 
  
 PullMessagesSync 
 ( 
 string 
  
 projectId 
 , 
  
 string 
  
 subscriptionId 
 , 
  
 bool 
  
 acknowledge 
 ) 
  
 { 
  
  SubscriptionName 
 
  
 subscriptionName 
  
 = 
  
  SubscriptionName 
 
 . 
  FromProjectSubscription 
 
 ( 
 projectId 
 , 
  
 subscriptionId 
 ); 
  
  SubscriberServiceApiClient 
 
  
 subscriberClient 
  
 = 
  
  SubscriberServiceApiClient 
 
 . 
  Create 
 
 (); 
  
 int 
  
 messageCount 
  
 = 
  
 0 
 ; 
  
 try 
  
 { 
  
 // Pull messages from server, 
  
 // allowing an immediate response if there are no messages. 
  
  PullResponse 
 
  
 response 
  
 = 
  
 subscriberClient 
 . 
  Pull 
 
 ( 
 subscriptionName 
 , 
  
 maxMessages 
 : 
  
 20 
 ); 
  
 // Print out each received message. 
  
 foreach 
  
 ( 
  ReceivedMessage 
 
  
 msg 
  
 in 
  
 response 
 . 
  ReceivedMessages 
 
 ) 
  
 { 
  
 string 
  
 text 
  
 = 
  
 msg 
 . 
 Message 
 . 
  Data 
 
 . 
 ToStringUtf8 
 (); 
  
 Console 
 . 
 WriteLine 
 ( 
 $"Message {msg.Message.MessageId}: {text}" 
 ); 
  
 Interlocked 
 . 
 Increment 
 ( 
 ref 
  
 messageCount 
 ); 
  
 } 
  
 // If acknowledgement required, send to server. 
  
 if 
  
 ( 
 acknowledge 
 && 
 messageCount 
 > 
 0 
 ) 
  
 { 
  
 subscriberClient 
 . 
  Acknowledge 
 
 ( 
 subscriptionName 
 , 
  
 response 
 . 
  ReceivedMessages 
 
 . 
 Select 
 ( 
 msg 
  
 = 
>  
 msg 
 . 
  AckId 
 
 )); 
  
 } 
  
 } 
  
 catch 
  
 ( 
  RpcException 
 
  
 ex 
 ) 
  
 when 
  
 ( 
 ex 
 . 
  Status 
 
 . 
  StatusCode 
 
  
 == 
  
  StatusCode 
 
 . 
  Unavailable 
 
 ) 
  
 { 
  
 // UNAVAILABLE due to too many concurrent pull requests pending for the given subscription. 
  
 } 
  
 return 
  
 messageCount 
 ; 
  
 } 
 }

Go

Before trying this sample, follow the Go setup instructions in the Pub/Sub quickstart using client libraries . For more information, see the Pub/Sub Go API reference documentation .

To authenticate to Pub/Sub, set up Application Default Credentials. For more information, see Set up authentication for a local development environment .

  import 
  
 ( 
  
 "context" 
  
 "fmt" 
  
 "io" 
  
 "sync/atomic" 
  
 "time" 
  
 "cloud.google.com/go/pubsub" 
 ) 
 func 
  
 pullMsgsSync 
 ( 
 w 
  
 io 
 . 
 Writer 
 , 
  
 projectID 
 , 
  
 subID 
  
 string 
 ) 
  
 error 
  
 { 
  
 // projectID := "my-project-id" 
  
 // subID := "my-sub" 
  
 ctx 
  
 := 
  
 context 
 . 
 Background 
 () 
  
 client 
 , 
  
 err 
  
 := 
  
 pubsub 
 . 
  NewClient 
 
 ( 
 ctx 
 , 
  
 projectID 
 ) 
  
 if 
  
 err 
  
 != 
  
 nil 
  
 { 
  
 return 
  
 fmt 
 . 
 Errorf 
 ( 
 "pubsub.NewClient: %w" 
 , 
  
 err 
 ) 
  
 } 
  
 defer 
  
 client 
 . 
 Close 
 () 
  
 sub 
  
 := 
  
 client 
 . 
 Subscription 
 ( 
 subID 
 ) 
  
 // Turn on synchronous mode. This makes the subscriber use the Pull RPC rather 
  
 // than the StreamingPull RPC, which is useful for guaranteeing MaxOutstandingMessages, 
  
 // the max number of messages the client will hold in memory at a time. 
  
 sub 
 . 
 ReceiveSettings 
 . 
 Synchronous 
  
 = 
  
 true 
  
 sub 
 . 
 ReceiveSettings 
 . 
 MaxOutstandingMessages 
  
 = 
  
 10 
  
 // Receive messages for 10 seconds, which simplifies testing. 
  
 // Comment this out in production, since `Receive` should 
  
 // be used as a long running operation. 
  
 ctx 
 , 
  
 cancel 
  
 := 
  
 context 
 . 
 WithTimeout 
 ( 
 ctx 
 , 
  
 10 
 * 
 time 
 . 
 Second 
 ) 
  
 defer 
  
 cancel 
 () 
  
 var 
  
 received 
  
 int32 
  
 err 
  
 = 
  
 sub 
 . 
 Receive 
 ( 
 ctx 
 , 
  
 func 
 ( 
 _ 
  
 context 
 . 
 Context 
 , 
  
 msg 
  
 * 
 pubsub 
 . 
 Message 
 ) 
  
 { 
  
 fmt 
 . 
 Fprintf 
 ( 
 w 
 , 
  
 "Got message: %q\n" 
 , 
  
 string 
 ( 
 msg 
 . 
 Data 
 )) 
  
 atomic 
 . 
 AddInt32 
 ( 
& received 
 , 
  
 1 
 ) 
  
 msg 
 . 
 Ack 
 () 
  
 }) 
  
 if 
  
 err 
  
 != 
  
 nil 
  
 { 
  
 return 
  
 fmt 
 . 
 Errorf 
 ( 
 "sub.Receive: %w" 
 , 
  
 err 
 ) 
  
 } 
  
 fmt 
 . 
 Fprintf 
 ( 
 w 
 , 
  
 "Received %d messages\n" 
 , 
  
 received 
 ) 
  
 return 
  
 nil 
 }

Java

Before trying this sample, follow the Java setup instructions in the Pub/Sub quickstart using client libraries . For more information, see the Pub/Sub Java API reference documentation .

To authenticate to Pub/Sub, set up Application Default Credentials. For more information, see Set up authentication for a local development environment .

  import 
  
 com.google.cloud.pubsub.v1.stub.GrpcSubscriberStub 
 ; 
 import 
  
 com.google.cloud.pubsub.v1.stub. SubscriberStub 
 
 ; 
 import 
  
 com.google.cloud.pubsub.v1.stub.SubscriberStubSettings 
 ; 
 import 
  
 com.google.pubsub.v1. AcknowledgeRequest 
 
 ; 
 import 
  
 com.google.pubsub.v1. ProjectSubscriptionName 
 
 ; 
 import 
  
 com.google.pubsub.v1. PullRequest 
 
 ; 
 import 
  
 com.google.pubsub.v1. PullResponse 
 
 ; 
 import 
  
 com.google.pubsub.v1. ReceivedMessage 
 
 ; 
 import 
  
 java.io.IOException 
 ; 
 import 
  
 java.util.ArrayList 
 ; 
 import 
  
 java.util.List 
 ; 
 public 
  
 class 
 SubscribeSyncExample 
  
 { 
  
 public 
  
 static 
  
 void 
  
 main 
 ( 
 String 
 ... 
  
 args 
 ) 
  
 throws 
  
 Exception 
  
 { 
  
 // TODO(developer): Replace these variables before running the sample. 
  
 String 
  
 projectId 
  
 = 
  
 "your-project-id" 
 ; 
  
 String 
  
 subscriptionId 
  
 = 
  
 "your-subscription-id" 
 ; 
  
 Integer 
  
 numOfMessages 
  
 = 
  
 10 
 ; 
  
 subscribeSyncExample 
 ( 
 projectId 
 , 
  
 subscriptionId 
 , 
  
 numOfMessages 
 ); 
  
 } 
  
 public 
  
 static 
  
 void 
  
 subscribeSyncExample 
 ( 
  
 String 
  
 projectId 
 , 
  
 String 
  
 subscriptionId 
 , 
  
 Integer 
  
 numOfMessages 
 ) 
  
 throws 
  
 IOException 
  
 { 
  
 SubscriberStubSettings 
  
 subscriberStubSettings 
  
 = 
  
 SubscriberStubSettings 
 . 
 newBuilder 
 () 
  
 . 
 setTransportChannelProvider 
 ( 
  
 SubscriberStubSettings 
 . 
 defaultGrpcTransportProviderBuilder 
 () 
  
 . 
 setMaxInboundMessageSize 
 ( 
 20 
  
 * 
  
 1024 
  
 * 
  
 1024 
 ) 
  
 // 20MB (maximum message size). 
  
 . 
 build 
 ()) 
  
 . 
 build 
 (); 
  
 try 
  
 ( 
  SubscriberStub 
 
  
 subscriber 
  
 = 
  
 GrpcSubscriberStub 
 . 
 create 
 ( 
 subscriberStubSettings 
 )) 
  
 { 
  
 String 
  
 subscriptionName 
  
 = 
  
  ProjectSubscriptionName 
 
 . 
 format 
 ( 
 projectId 
 , 
  
 subscriptionId 
 ); 
  
  PullRequest 
 
  
 pullRequest 
  
 = 
  
  PullRequest 
 
 . 
 newBuilder 
 () 
  
 . 
 setMaxMessages 
 ( 
 numOfMessages 
 ) 
  
 . 
 setSubscription 
 ( 
 subscriptionName 
 ) 
  
 . 
 build 
 (); 
  
 // Use pullCallable().futureCall to asynchronously perform this operation. 
  
  PullResponse 
 
  
 pullResponse 
  
 = 
  
 subscriber 
 . 
 pullCallable 
 (). 
 call 
 ( 
 pullRequest 
 ); 
  
 // Stop the program if the pull response is empty to avoid acknowledging 
  
 // an empty list of ack IDs. 
  
 if 
  
 ( 
 pullResponse 
 . 
  getReceivedMessagesList 
 
 (). 
 isEmpty 
 ()) 
  
 { 
  
 System 
 . 
 out 
 . 
 println 
 ( 
 "No message was pulled. Exiting." 
 ); 
  
 return 
 ; 
  
 } 
  
 List<String> 
  
 ackIds 
  
 = 
  
 new 
  
 ArrayList 
<> (); 
  
 for 
  
 ( 
  ReceivedMessage 
 
  
 message 
  
 : 
  
 pullResponse 
 . 
  getReceivedMessagesList 
 
 ()) 
  
 { 
  
 // Handle received message 
  
 // ... 
  
 ackIds 
 . 
 add 
 ( 
 message 
 . 
 getAckId 
 ()); 
  
 } 
  
 // Acknowledge received messages. 
  
  AcknowledgeRequest 
 
  
 acknowledgeRequest 
  
 = 
  
  AcknowledgeRequest 
 
 . 
 newBuilder 
 () 
  
 . 
 setSubscription 
 ( 
 subscriptionName 
 ) 
  
 . 
 addAllAckIds 
 ( 
 ackIds 
 ) 
  
 . 
 build 
 (); 
  
 // Use acknowledgeCallable().futureCall to asynchronously perform this operation. 
  
 subscriber 
 . 
 acknowledgeCallable 
 (). 
 call 
 ( 
 acknowledgeRequest 
 ); 
  
 System 
 . 
 out 
 . 
 println 
 ( 
 pullResponse 
 . 
  getReceivedMessagesList 
 
 ()); 
  
 } 
  
 } 
 }

Node.js

Before trying this sample, follow the Node.js setup instructions in the Pub/Sub quickstart using client libraries . For more information, see the Pub/Sub Node.js API reference documentation .

To authenticate to Pub/Sub, set up Application Default Credentials. For more information, see Set up authentication for a local development environment .

  /** 
 * TODO(developer): Uncomment these variables before running the sample. 
 */ 
 // 
  
 const 
  
 projectId 
  
 = 
  
 'YOUR_PROJECT_ID' 
 ; 
 // 
  
 const 
  
 subscriptionNameOrId 
  
 = 
  
 'YOUR_SUBSCRIPTION_NAME_OR_ID' 
 ; 
 // 
  
 Imports 
  
 the 
  
 Google 
  
 Cloud 
  
 client 
  
 library 
 . 
  
 v1 
  
 is 
  
 for 
  
 the 
  
 lower 
  
 level 
 // 
  
 proto 
  
 access 
 . 
 const 
  
 { 
 v1 
 } 
  
 = 
  
 require 
 ( 
 '@google-cloud/pubsub' 
 ); 
 // 
  
 Creates 
  
 a 
  
 client 
 ; 
  
 cache 
  
 this 
  
 for 
  
 further 
  
 use 
 . 
 const 
  
 subClient 
  
 = 
  
 new 
  
 v1 
 . 
 SubscriberClient 
 (); 
 async 
  
 function 
  
 synchronousPull 
 ( 
 projectId 
 , 
  
 subscriptionNameOrId 
 ) 
  
 { 
  
 // 
  
 The 
  
 low 
  
 level 
  
 API 
  
 client 
  
 requires 
  
 a 
  
 name 
  
 only 
 . 
  
 const 
  
 formattedSubscription 
  
 = 
  
 subscriptionNameOrId 
 . 
 indexOf 
 ( 
 '/' 
 ) 
  
> = 
  
 0 
  
 ? 
  
 subscriptionNameOrId 
  
 : 
  
 subClient 
 . 
 subscriptionPath 
 ( 
 projectId 
 , 
  
 subscriptionNameOrId 
 ); 
  
 // 
  
 The 
  
 maximum 
  
 number 
  
 of 
  
 messages 
  
 returned 
  
 for 
  
 this 
  
 request 
 . 
  
 // 
  
 Pub 
 / 
 Sub 
  
 may 
  
 return 
  
 fewer 
  
 than 
  
 the 
  
 number 
  
 specified 
 . 
  
 const 
  
 request 
  
 = 
  
 { 
  
 subscription 
 : 
  
 formattedSubscription 
 , 
  
 maxMessages 
 : 
  
 10 
 , 
  
 } 
 ; 
  
 // 
  
 The 
  
 subscriber 
  
 pulls 
  
 a 
  
 specified 
  
 number 
  
 of 
  
 messages 
 . 
  
 const 
  
 [ 
 response 
 ] 
  
 = 
  
 await 
  
 subClient 
 . 
 pull 
 ( 
 request 
 ); 
  
 // 
  
 Process 
  
 the 
  
 messages 
 . 
  
 const 
  
 ackIds 
  
 = 
  
 [] 
 ; 
  
 for 
  
 ( 
 const 
  
 message 
  
 of 
  
 response 
 . 
 receivedMessages 
  
 || 
  
 [] 
 ) 
  
 { 
  
 console 
 . 
 log 
 ( 
 ` 
 Received 
  
 message 
 : 
  
 ${ 
 message 
 . 
 message 
 . 
 data 
 }` 
 ); 
  
 if 
  
 ( 
 message 
 . 
 ackId 
 ) 
  
 { 
  
 ackIds 
 . 
 push 
 ( 
 message 
 . 
 ackId 
 ); 
  
 } 
  
 } 
  
 if 
  
 ( 
 ackIds 
 . 
 length 
  
 !== 
  
 0 
 ) 
  
 { 
  
 // 
  
 Acknowledge 
  
 all 
  
 of 
  
 the 
  
 messages 
 . 
  
 You 
  
 could 
  
 also 
  
 acknowledge 
  
 // 
  
 these 
  
 individually 
 , 
  
 but 
  
 this 
  
 is 
  
 more 
  
 efficient 
 . 
  
 const 
  
 ackRequest 
  
 = 
  
 { 
  
 subscription 
 : 
  
 formattedSubscription 
 , 
  
 ackIds 
 : 
  
 ackIds 
 , 
  
 } 
 ; 
  
 await 
  
 subClient 
 . 
 acknowledge 
 ( 
 ackRequest 
 ); 
  
 } 
  
 console 
 . 
 log 
 ( 
 'Done.' 
 ); 
 }

Node.js

Before trying this sample, follow the Node.js setup instructions in the Pub/Sub quickstart using client libraries . For more information, see the Pub/Sub Node.js API reference documentation .

To authenticate to Pub/Sub, set up Application Default Credentials. For more information, see Set up authentication for a local development environment .

  /** 
 * 
 TODO 
 ( 
 developer 
 ): 
 Uncomment 
 these 
 variables 
 before 
 running 
 the 
 sample 
 . 
 */ 
 // 
 const 
 projectId 
 = 
 'YOUR_PROJECT_ID' 
 ; 
 // 
 const 
 subscriptionNameOrId 
 = 
 'YOUR_SUBSCRIPTION_NAME_OR_ID' 
 ; 
 // 
 Imports 
 the 
 Google 
 Cloud 
 client 
 library 
 . 
 v1 
 is 
 for 
 the 
 lower 
 level 
 // 
 proto 
 access 
 . 
 import 
  
 { 
 v1 
 } 
 from 
  
 '@google-cloud/pubsub' 
 ; 
 // 
 Creates 
 a 
 client 
 ; 
 cache 
 this 
 for 
 further 
 use 
 . 
 const 
 subClient 
 = 
 new 
 v1 
 . 
 SubscriberClient 
 (); 
 async 
 function 
 synchronousPull 
 ( 
 projectId 
 : 
 string 
 , 
 subscriptionNameOrId 
 : 
 string 
 , 
 ) 
 { 
 // 
 The 
 low 
 level 
 API 
 client 
 requires 
 a 
 name 
 only 
 . 
 const 
 formattedSubscription 
 = 
 subscriptionNameOrId 
 . 
 indexOf 
 ( 
 '/' 
 ) 
> = 
 0 
 ? 
 subscriptionNameOrId 
 : 
 subClient 
 . 
 subscriptionPath 
 ( 
 projectId 
 , 
 subscriptionNameOrId 
 ); 
 // 
 The 
 maximum 
 number 
 of 
 messages 
 returned 
 for 
 this 
 request 
 . 
 // 
 Pub 
 / 
 Sub 
 may 
 return 
 fewer 
 than 
 the 
 number 
 specified 
 . 
 const 
 request 
 = 
 { 
 subscription 
 : 
 formattedSubscription 
 , 
 maxMessages 
 : 
 10 
 , 
 }; 
 // 
 The 
 subscriber 
 pulls 
 a 
 specified 
 number 
 of 
 messages 
 . 
 const 
 [ 
 response 
 ] 
 = 
 await 
 subClient 
 . 
 pull 
 ( 
 request 
 ); 
 // 
 Process 
 the 
 messages 
 . 
 const 
 ackIds 
 : 
 string 
 [] 
 = 
 []; 
 for 
 ( 
 const 
 message 
 of 
 response 
 . 
 receivedMessages 
 ?? 
 []) 
 { 
 console 
 . 
 log 
 ( 
 ` 
 Received 
 message 
 : 
 $ 
 { 
 message 
 . 
 message 
 ? 
 . 
 data 
 } 
 ` 
 ); 
 if 
 ( 
 message 
 . 
 ackId 
 ) 
 { 
 ackIds 
 . 
 push 
 ( 
 message 
 . 
 ackId 
 ); 
 } 
 } 
 if 
 ( 
 ackIds 
 . 
 length 
 !== 
 0 
 ) 
 { 
 // 
 Acknowledge 
 all 
 of 
 the 
 messages 
 . 
 You 
 could 
 also 
 acknowledge 
 // 
 these 
 individually 
 , 
 but 
 this 
 is 
 more 
 efficient 
 . 
 const 
 ackRequest 
 = 
 { 
 subscription 
 : 
 formattedSubscription 
 , 
 ackIds 
 : 
 ackIds 
 , 
 }; 
 await 
 subClient 
 . 
 acknowledge 
 ( 
 ackRequest 
 ); 
 } 
 console 
 . 
 log 
 ( 
 'Done.' 
 ); 
 }

PHP

Before trying this sample, follow the PHP setup instructions in the Pub/Sub quickstart using client libraries . For more information, see the Pub/Sub PHP API reference documentation .

To authenticate to Pub/Sub, set up Application Default Credentials. For more information, see Set up authentication for a local development environment .

  use Google\Cloud\PubSub\PubSubClient; 
 /** 
 * Pulls all Pub/Sub messages for a subscription. 
 * 
 * @param string $projectId  The Google project ID. 
 * @param string $subscriptionName  The Pub/Sub subscription name. 
 */ 
 function pull_messages($projectId, $subscriptionName) 
 { 
 $pubsub = new PubSubClient([ 
 'projectId' => $projectId, 
 ]); 
 $subscription = $pubsub->subscription($subscriptionName); 
 foreach ($subscription->pull() as $message) { 
 printf('Message: %s' . PHP_EOL, $message->data()); 
 // Acknowledge the Pub/Sub message has been received, so it will not be pulled multiple times. 
 $subscription->acknowledge($message); 
 } 
 }

Python

Before trying this sample, follow the Python setup instructions in the Pub/Sub quickstart using client libraries . For more information, see the Pub/Sub Python API reference documentation .

To authenticate to Pub/Sub, set up Application Default Credentials. For more information, see Set up authentication for a local development environment .

  from 
  
 google.api_core 
  
 import 
  retry 
 
 from 
  
 google.cloud 
  
 import 
 pubsub_v1 
 # TODO(developer) 
 # project_id = "your-project-id" 
 # subscription_id = "your-subscription-id" 
 subscriber 
 = 
 pubsub_v1 
 . 
  SubscriberClient 
 
 () 
 subscription_path 
 = 
 subscriber 
 . 
 subscription_path 
 ( 
 project_id 
 , 
 subscription_id 
 ) 
 NUM_MESSAGES 
 = 
 3 
 # Wrap the subscriber in a 'with' block to automatically call close() to 
 # close the underlying gRPC channel when done. 
 with 
 subscriber 
 : 
 # The subscriber pulls a specific number of messages. The actual 
 # number of messages pulled may be smaller than max_messages. 
 response 
 = 
 subscriber 
 . 
  pull 
 
 ( 
 request 
 = 
 { 
 "subscription" 
 : 
 subscription_path 
 , 
 "max_messages" 
 : 
 NUM_MESSAGES 
 }, 
 retry 
 = 
  retry 
 
 . 
 Retry 
 ( 
 deadline 
 = 
 300 
 ), 
 ) 
 if 
 len 
 ( 
 response 
 . 
 received_messages 
 ) 
 == 
 0 
 : 
 return 
 ack_ids 
 = 
 [] 
 for 
 received_message 
 in 
 response 
 . 
 received_messages 
 : 
 print 
 ( 
 f 
 "Received: 
 { 
 received_message 
 . 
 message 
 . 
  data 
 
 } 
 ." 
 ) 
 ack_ids 
 . 
 append 
 ( 
 received_message 
 . 
  ack_id 
 
 ) 
 # Acknowledges the received messages so they will not be sent again. 
 subscriber 
 . 
  acknowledge 
 
 ( 
 request 
 = 
 { 
 "subscription" 
 : 
 subscription_path 
 , 
 "ack_ids" 
 : 
 ack_ids 
 } 
 ) 
 print 
 ( 
 f 
 "Received and acknowledged 
 { 
 len 
 ( 
 response 
 . 
 received_messages 
 ) 
 } 
 messages from 
 { 
 subscription_path 
 } 
 ." 
 )

Ruby

Before trying this sample, follow the Ruby setup instructions in the Pub/Sub quickstart using client libraries . For more information, see the Pub/Sub Ruby API reference documentation .

To authenticate to Pub/Sub, set up Application Default Credentials. For more information, see Set up authentication for a local development environment .

  # subscription_id = "your-subscription-id" 
 pubsub 
  
 = 
  
 Google 
 :: 
 Cloud 
 :: 
  PubSub 
 
 . 
  new 
 
 subscriber 
  
 = 
  
 pubsub 
 . 
  subscriber 
 
  
 subscription_id 
 subscriber 
 . 
 pull 
 ( 
 immediate 
 : 
  
 false 
 ) 
 . 
 each 
  
 do 
  
 | 
 message 
 | 
  
 puts 
  
 "Message pulled: 
 #{ 
 message 
 . 
 data 
 } 
 " 
  
 message 
 . 
  acknowledge! 
 
 end

What's next

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Explore further

Code sample

C++

C#

Go

Java

Node.js

Node.js

PHP

Python

Ruby

What's next

Subscribe with synchronous pull