Subscribe with synchronous pull

  []( 
 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 
 (); 
 } 
 

  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 
 ; 
  
 } 
 } 
 

  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 
 } 
 

  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 
 
 ()); 
  
 } 
  
 } 
 } 
 

  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); 
 } 
 } 
 

  # 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