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Posted to commits@pulsar.apache.org by rx...@apache.org on 2020/04/18 12:13:15 UTC
[pulsar] branch master updated: [Docs] Update native go client docs
for Pulsar (#6747)
This is an automated email from the ASF dual-hosted git repository.
rxl pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/pulsar.git
The following commit(s) were added to refs/heads/master by this push:
new d78b7fb [Docs] Update native go client docs for Pulsar (#6747)
d78b7fb is described below
commit d78b7fb06fba6fe763e4d37ad32537abc44f6672
Author: 冉小龙 <rx...@apache.org>
AuthorDate: Sat Apr 18 20:13:01 2020 +0800
[Docs] Update native go client docs for Pulsar (#6747)
* Update native go client docs for Pulsar
Signed-off-by: xiaolong.ran <rx...@apache.org>
* Add CGo(deprecated) docs to repo
Signed-off-by: xiaolong.ran <rx...@apache.org>
---
...ent-libraries-go.md => client-libraries-cgo.md} | 7 +-
site2/docs/client-libraries-go.md | 668 +++++++++++++--------
2 files changed, 417 insertions(+), 258 deletions(-)
diff --git a/site2/docs/client-libraries-go.md b/site2/docs/client-libraries-cgo.md
similarity index 99%
copy from site2/docs/client-libraries-go.md
copy to site2/docs/client-libraries-cgo.md
index bdeb032..24f4e2a 100644
--- a/site2/docs/client-libraries-go.md
+++ b/site2/docs/client-libraries-cgo.md
@@ -1,7 +1,7 @@
---
-id: client-libraries-go
-title: Pulsar Go client
-sidebar_label: Go
+id: client-libraries-cgo
+title: Pulsar CGo client
+sidebar_label: CGo(deprecated)
---
You can use Pulsar Go client to create Pulsar [producers](#producers), [consumers](#consumers), and [readers](#readers) in Go (aka Golang).
@@ -18,7 +18,6 @@ Currently, the following Go clients are maintained in two repositories.
> #### API docs available as well
> For standard API docs, consult the [Godoc](https://godoc.org/github.com/apache/pulsar/pulsar-client-go/pulsar).
-
## Installation
### Requirements
diff --git a/site2/docs/client-libraries-go.md b/site2/docs/client-libraries-go.md
index bdeb032..90cd346 100644
--- a/site2/docs/client-libraries-go.md
+++ b/site2/docs/client-libraries-go.md
@@ -4,49 +4,28 @@ title: Pulsar Go client
sidebar_label: Go
---
-You can use Pulsar Go client to create Pulsar [producers](#producers), [consumers](#consumers), and [readers](#readers) in Go (aka Golang).
+> Tips: Currently, the CGo client will be deprecated, if you want to know more about the CGo client, please refer to [CGo client docs](client-libraries-cgo.md)
-All the methods in [producers](#producers), [consumers](#consumers), and [readers](#readers) of a Go client are thread-safe.
-
-Currently, the following Go clients are maintained in two repositories.
-
-| Language | Project | Maintainer | License | Description |
-|----------|---------|------------|---------|-------------|
-| CGo | [pulsar-client-go](https://github.com/apache/pulsar/tree/master/pulsar-client-go) | [Apache Pulsar](https://github.com/apache/pulsar) | [](https://opensource.org/licenses/Apache-2.0) | CGo client that depends on C++ client library |
-| Go | [pulsar-client-go](https://github.com/apache/pulsar-client-go) | [Apache Pulsar](https://github.com/apache/pulsar) | [](https://opensource.org/licenses/Apache-2.0) | A native golang client |
+You can use Pulsar [Go client](https://github.com/apache/pulsar-client-go) to create Pulsar [producers](#producers), [consumers](#consumers), and [readers](#readers) in Go (aka Golang).
> #### API docs available as well
-> For standard API docs, consult the [Godoc](https://godoc.org/github.com/apache/pulsar/pulsar-client-go/pulsar).
+> For standard API docs, consult the [Godoc](https://godoc.org/github.com/apache/pulsar-client-go/pulsar).
## Installation
-### Requirements
-
-Pulsar Go client library is based on the C++ client library. Follow
-the instructions for [C++ library](client-libraries-cpp.md) for installing the binaries through [RPM](client-libraries-cpp.md#rpm), [Deb](client-libraries-cpp.md#deb) or [Homebrew packages](client-libraries-cpp.md#macos).
-
### Install go package
-> #### Compatibility Warning
-> The version number of the Go client **must match** the version number of the Pulsar C++ client library.
-
-You can install the `pulsar` library locally using `go get`. Note that `go get` doesn't support fetching a specific tag - it will always pull in master's version of the Go client. You'll need a C++ client library that matches master.
+You can install the `pulsar` library locally using `go get`.
```bash
-$ go get -u github.com/apache/pulsar/pulsar-client-go/pulsar
-```
-
-Or you can use [dep](https://github.com/golang/dep) for managing the dependencies.
-
-```bash
-$ dep ensure -add github.com/apache/pulsar/pulsar-client-go/pulsar@v{{pulsar:version}}
+$ go get -u "github.com/apache/pulsar-client-go/pulsar"
```
Once installed locally, you can import it into your project:
```go
-import "github.com/apache/pulsar/pulsar-client-go/pulsar"
+import "github.com/apache/pulsar-client-go/pulsar"
```
## Connection URLs
@@ -78,39 +57,37 @@ In order to interact with Pulsar, you'll first need a `Client` object. You can c
```go
import (
- "log"
- "runtime"
+ "log"
+ "time"
- "github.com/apache/pulsar/pulsar-client-go/pulsar"
+ "github.com/apache/pulsar-client-go/pulsar"
)
func main() {
- client, err := pulsar.NewClient(pulsar.ClientOptions{
- URL: "pulsar://localhost:6650",
- OperationTimeoutSeconds: 5,
- MessageListenerThreads: runtime.NumCPU(),
- })
-
- if err != nil {
- log.Fatalf("Could not instantiate Pulsar client: %v", err)
- }
+ client, err := pulsar.NewClient(pulsar.ClientOptions{
+ URL: "pulsar://localhost:6650",
+ OperationTimeout: 30 * time.Second,
+ ConnectionTimeout: 30 * time.Second,
+ })
+ if err != nil {
+ log.Fatalf("Could not instantiate Pulsar client: %v", err)
+ }
+
+ defer client.Close()
}
```
The following configurable parameters are available for Pulsar clients:
-Parameter | Description | Default
-:---------|:------------|:-------
-`URL` | The connection URL for the Pulsar cluster. See [above](#urls) for more info |
-`IOThreads` | The number of threads to use for handling connections to Pulsar [brokers](reference-terminology.md#broker) | 1
-`OperationTimeoutSeconds` | The timeout for some Go client operations (creating producers, subscribing to and unsubscribing from [topics](reference-terminology.md#topic)). Retries will occur until this threshold is reached, at which point the operation will fail. | 30
-`MessageListenerThreads` | The number of threads used by message listeners ([consumers](#consumers) and [readers](#readers)) | 1
-`ConcurrentLookupRequests` | The number of concurrent lookup requests that can be sent on each broker connection. Setting a maximum helps to keep from overloading brokers. You should set values over the default of 5000 only if the client needs to produce and/or subscribe to thousands of Pulsar topics. | 5000
-`Logger` | A custom logger implementation for the client (as a function that takes a log level, file path, line number, and message). All info, warn, and error messages will be routed to this function. | `nil`
-`TLSTrustCertsFilePath` | The file path for the trusted TLS certificate |
-`TLSAllowInsecureConnection` | Whether the client accepts untrusted TLS certificates from the broker | `false`
-`Authentication` | Configure the authentication provider. (default: no authentication). Example: `Authentication: NewAuthenticationTLS("my-cert.pem", "my-key.pem")` | `nil`
-`StatsIntervalInSeconds` | The interval (in seconds) at which client stats are published | 60
+ Name | Description | Default
+| :-------- | :---------- |:---------- |
+| URL | Configure the service URL for the Pulsar service. This parameter is required | |
+| ConnectionTimeout | Timeout for the establishment of a TCP connection | 30s |
+| OperationTimeout| Set the operation timeout. Producer-create, subscribe and unsubscribe operations will be retried until this interval, after which the operation will be marked as failed| 30s|
+| Authentication | Configure the authentication provider. Example: `Authentication: NewAuthenticationTLS("my-cert.pem", "my-key.pem")` | no authentication |
+| TLSTrustCertsFilePath | Set the path to the trusted TLS certificate file | |
+| TLSAllowInsecureConnection | Configure whether the Pulsar client accept untrusted TLS certificate from broker | false |
+| TLSValidateHostname | Configure whether the Pulsar client verify the validity of the host name from broker | false |
## Producers
@@ -118,28 +95,21 @@ Pulsar producers publish messages to Pulsar topics. You can [configure](#produce
```go
producer, err := client.CreateProducer(pulsar.ProducerOptions{
- Topic: "my-topic",
+ Topic: "my-topic",
})
-if err != nil {
- log.Fatalf("Could not instantiate Pulsar producer: %v", err)
-}
+_, err = producer.Send(context.Background(), &pulsar.ProducerMessage{
+ Payload: []byte("hello"),
+})
defer producer.Close()
-msg := pulsar.ProducerMessage{
- Payload: []byte("Hello, Pulsar"),
-}
-
-if err := producer.Send(context.Background(), msg); err != nil {
- log.Fatalf("Producer could not send message: %v", err)
+if err != nil {
+ fmt.Println("Failed to publish message", err)
}
+fmt.Println("Published message")
```
-> #### Blocking operation
-> When you create a new Pulsar producer, the operation will block (waiting on a go channel) until either a producer is successfully created or an error is thrown.
-
-
### Producer operations
Pulsar Go producers have the following methods available:
@@ -148,124 +118,154 @@ Method | Description | Return type
:------|:------------|:-----------
`Topic()` | Fetches the producer's [topic](reference-terminology.md#topic)| `string`
`Name()` | Fetches the producer's name | `string`
-`Send(context.Context, ProducerMessage)` | Publishes a [message](#messages) to the producer's topic. This call will block until the message is successfully acknowledged by the Pulsar broker, or an error will be thrown if the timeout set using the `SendTimeout` in the producer's [configuration](#producer-configuration) is exceeded. | `error`
-`SendAndGetMsgID(context.Context, ProducerMessage)`| Send a message, this call will be blocking until is successfully acknowledged by the Pulsar broker. | (MessageID, error)
-`SendAsync(context.Context, ProducerMessage, func(ProducerMessage, error))` | Publishes a [message](#messages) to the producer's topic asynchronously. The third argument is a callback function that specifies what happens either when the message is acknowledged or an error is thrown. |
-`SendAndGetMsgIDAsync(context.Context, ProducerMessage, func(MessageID, error))`| Send a message in asynchronous mode. The callback will report back the message being published and the eventual error in publishing |
+`Send(context.Context, *ProducerMessage)` | Publishes a [message](#messages) to the producer's topic. This call will block until the message is successfully acknowledged by the Pulsar broker, or an error will be thrown if the timeout set using the `SendTimeout` in the producer's [configuration](#producer-configuration) is exceeded. | (MessageID, error)
+`SendAsync(context.Context, *ProducerMessage, func(MessageID, *ProducerMessage, error))`| Send a message, this call will be blocking until is successfully acknowledged by the Pulsar broker. |
`LastSequenceID()` | Get the last sequence id that was published by this producer. his represent either the automatically assigned or custom sequence id (set on the ProducerMessage) that was published and acknowledged by the broker. | int64
`Flush()`| Flush all the messages buffered in the client and wait until all messages have been successfully persisted. | error
-`Close()` | Closes the producer and releases all resources allocated to it. If `Close()` is called then no more messages will be accepted from the publisher. This method will block until all pending publish requests have been persisted by Pulsar. If an error is thrown, no pending writes will be retried. | `error`
-`Schema()` | | Schema
+`Close()` | Closes the producer and releases all resources allocated to it. If `Close()` is called then no more messages will be accepted from the publisher. This method will block until all pending publish requests have been persisted by Pulsar. If an error is thrown, no pending writes will be retried. |
-Here's a more involved example usage of a producer:
+### Producer Example
+
+#### How to use message router in producer
```go
-import (
- "context"
- "fmt"
- "log"
+client, err := NewClient(ClientOptions{
+ URL: serviceURL,
+})
- "github.com/apache/pulsar/pulsar-client-go/pulsar"
-)
+if err != nil {
+ log.Fatal(err)
+}
+defer client.Close()
-func main() {
- // Instantiate a Pulsar client
- client, err := pulsar.NewClient(pulsar.ClientOptions{
- URL: "pulsar://localhost:6650",
- })
+// Only subscribe on the specific partition
+consumer, err := client.Subscribe(ConsumerOptions{
+ Topic: "my-partitioned-topic-partition-2",
+ SubscriptionName: "my-sub",
+})
- if err != nil { log.Fatal(err) }
+if err != nil {
+ log.Fatal(err)
+}
+defer consumer.Close()
- // Use the client to instantiate a producer
- producer, err := client.CreateProducer(pulsar.ProducerOptions{
- Topic: "my-topic",
- })
+producer, err := client.CreateProducer(ProducerOptions{
+ Topic: "my-partitioned-topic",
+ MessageRouter: func(msg *ProducerMessage, tm TopicMetadata) int {
+ fmt.Println("Routing message ", msg, " -- Partitions: ", tm.NumPartitions())
+ return 2
+ },
+})
- if err != nil { log.Fatal(err) }
+if err != nil {
+ log.Fatal(err)
+}
+defer producer.Close()
+```
- ctx := context.Background()
+#### How to use delay relative in producer
- // Send 10 messages synchronously and 10 messages asynchronously
- for i := 0; i < 10; i++ {
- // Create a message
- msg := pulsar.ProducerMessage{
- Payload: []byte(fmt.Sprintf("message-%d", i)),
- }
+```go
+client, err := NewClient(ClientOptions{
+ URL: "pulsar://localhost:6650",
+})
+if err != nil {
+ log.Fatal(err)
+}
+defer client.Close()
- // Attempt to send the message
- if err := producer.Send(ctx, msg); err != nil {
- log.Fatal(err)
- }
+topicName := newTopicName()
+producer, err := client.CreateProducer(ProducerOptions{
+ Topic: topicName,
+})
+if err != nil {
+ log.Fatal(err)
+}
+defer producer.Close()
- // Create a different message to send asynchronously
- asyncMsg := pulsar.ProducerMessage{
- Payload: []byte(fmt.Sprintf("async-message-%d", i)),
- }
+consumer, err := client.Subscribe(ConsumerOptions{
+ Topic: topicName,
+ SubscriptionName: "subName",
+ Type: Shared,
+})
+if err != nil {
+ log.Fatal(err)
+}
+defer consumer.Close()
- // Attempt to send the message asynchronously and handle the response
- producer.SendAsync(ctx, asyncMsg, func(msg pulsar.ProducerMessage, err error) {
- if err != nil { log.Fatal(err) }
+ID, err := producer.Send(context.Background(), &ProducerMessage{
+ Payload: []byte(fmt.Sprintf("test")),
+ DeliverAfter: 3 * time.Second,
+})
+if err != nil {
+ log.Fatal(err)
+}
+fmt.Println(ID)
- fmt.Printf("the %s successfully published", string(msg.Payload))
- })
- }
+ctx, canc := context.WithTimeout(context.Background(), 1*time.Second)
+msg, err := consumer.Receive(ctx)
+if err != nil {
+ log.Fatal(err)
}
+fmt.Println(msg.Payload())
+canc()
+
+ctx, canc = context.WithTimeout(context.Background(), 5*time.Second)
+msg, err = consumer.Receive(ctx)
+if err != nil {
+ log.Fatal(err)
+}
+fmt.Println(msg.Payload())
+canc()
```
+
### Producer configuration
-Parameter | Description | Default
-:---------|:------------|:-------
-`Topic` | The Pulsar [topic](reference-terminology.md#topic) to which the producer will publish messages |
-`Name` | A name for the producer. If you don't explicitly assign a name, Pulsar will automatically generate a globally unique name that you can access later using the `Name()` method. If you choose to explicitly assign a name, it will need to be unique across *all* Pulsar clusters, otherwise the creation operation will throw an error. |
-`Properties`| Attach a set of application defined properties to the producer. This properties will be visible in the topic stats |
-`SendTimeout` | When publishing a message to a topic, the producer will wait for an acknowledgment from the responsible Pulsar [broker](reference-terminology.md#broker). If a message is not acknowledged within the threshold set by this parameter, an error will be thrown. If you set `SendTimeout` to -1, the timeout will be set to infinity (and thus removed). Removing the send timeout is recommended when using Pulsar's [message de-duplication](cookbooks-deduplication.md) feature. | 30 seconds
-`MaxPendingMessages` | The maximum size of the queue holding pending messages (i.e. messages waiting to receive an acknowledgment from the [broker](reference-terminology.md#broker)). By default, when the queue is full all calls to the `Send` and `SendAsync` methods will fail *unless* `BlockIfQueueFull` is set to `true`. |
-`MaxPendingMessagesAcrossPartitions` | Set the number of max pending messages across all the partitions. This setting will be used to lower the max pending messages for each partition `MaxPendingMessages(int)`, if the total exceeds the configured value.|
-`BlockIfQueueFull` | If set to `true`, the producer's `Send` and `SendAsync` methods will block when the outgoing message queue is full rather than failing and throwing an error (the size of that queue is dictated by the `MaxPendingMessages` parameter); if set to `false` (the default), `Send` and `SendAsync` operations will fail and throw a `ProducerQueueIsFullError` when the queue is full. | `false`
-`MessageRoutingMode` | The message routing logic (for producers on [partitioned topics](concepts-architecture-overview.md#partitioned-topics)). This logic is applied only when no key is set on messages. The available options are: round robin (`pulsar.RoundRobinDistribution`, the default), publishing all messages to a single partition (`pulsar.UseSinglePartition`), or a custom partitioning scheme (`pulsar.CustomPartition`). | `pulsar.RoundRobinDistribution`
-`HashingScheme` | The hashing function that determines the partition on which a particular message is published (partitioned topics only). The available options are: `pulsar.JavaStringHash` (the equivalent of `String.hashCode()` in Java), `pulsar.Murmur3_32Hash` (applies the [Murmur3](https://en.wikipedia.org/wiki/MurmurHash) hashing function), or `pulsar.BoostHash` (applies the hashing function from C++'s [Boost](https://www.boost.org/doc/libs/1_62_0/doc/html/hash.html) library) | `puls [...]
-`CompressionType` | The message data compression type used by the producer. The available options are [`LZ4`](https://github.com/lz4/lz4), [`ZLIB`](https://zlib.net/), [`ZSTD`](https://facebook.github.io/zstd/) and [`SNAPPY`](https://google.github.io/snappy/). | No compression
-`MessageRouter` | By default, Pulsar uses a round-robin routing scheme for [partitioned topics](cookbooks-partitioned.md). The `MessageRouter` parameter enables you to specify custom routing logic via a function that takes the Pulsar message and topic metadata as an argument and returns an integer (where the ), i.e. a function signature of `func(Message, TopicMetadata) int`. |
-`Batching` | Control whether automatic batching of messages is enabled for the producer. | false
-`BatchingMaxPublishDelay` | Set the time period within which the messages sent will be batched (default: 10ms) if batch messages are enabled. If set to a non zero value, messages will be queued until this time interval or until | 10ms
-`BatchingMaxMessages` | Set the maximum number of messages permitted in a batch. (default: 1000) If set to a value greater than 1, messages will be queued until this threshold is reached or batch interval has elapsed | 1000
+ Name | Description | Default
+| :-------- | :---------- |:---------- |
+| Topic | Topic specify the topic this consumer will subscribe to. This argument is required when constructing the reader. | |
+| Name | Name specify a name for the producer. If not assigned, the system will generate a globally unique name which can be access with Producer.ProducerName(). | |
+| Properties | Properties attach a set of application defined properties to the producer This properties will be visible in the topic stats | |
+| MaxPendingMessages| MaxPendingMessages set the max size of the queue holding the messages pending to receive an acknowledgment from the broker. | |
+| HashingScheme | HashingScheme change the `HashingScheme` used to chose the partition on where to publish a particular message. | JavaStringHash |
+| CompressionType | CompressionType set the compression type for the producer. | not compressed |
+| MessageRouter | MessageRouter set a custom message routing policy by passing an implementation of MessageRouter | |
+| DisableBatching | DisableBatching control whether automatic batching of messages is enabled for the producer. | false |
+| BatchingMaxPublishDelay | BatchingMaxPublishDelay set the time period within which the messages sent will be batched | 10ms |
+| BatchingMaxMessages | BatchingMaxMessages set the maximum number of messages permitted in a batch. | 1000 |
## Consumers
Pulsar consumers subscribe to one or more Pulsar topics and listen for incoming messages produced on that topic/those topics. You can [configure](#consumer-configuration) Go consumers using a `ConsumerOptions` object. Here's a basic example that uses channels:
```go
-msgChannel := make(chan pulsar.ConsumerMessage)
-
-consumerOpts := pulsar.ConsumerOptions{
- Topic: "my-topic",
- SubscriptionName: "my-subscription-1",
- Type: pulsar.Exclusive,
- MessageChannel: msgChannel,
-}
-
-consumer, err := client.Subscribe(consumerOpts)
-
+consumer, err := client.Subscribe(pulsar.ConsumerOptions{
+ Topic: "topic-1",
+ SubscriptionName: "my-sub",
+ Type: pulsar.Shared,
+})
if err != nil {
- log.Fatalf("Could not establish subscription: %v", err)
+ log.Fatal(err)
}
-
defer consumer.Close()
-for cm := range msgChannel {
- msg := cm.Message
+for i := 0; i < 10; i++ {
+ msg, err := consumer.Receive(context.Background())
+ if err != nil {
+ log.Fatal(err)
+ }
- fmt.Printf("Message ID: %s", msg.ID())
- fmt.Printf("Message value: %s", string(msg.Payload()))
+ fmt.Printf("Received message msgId: %#v -- content: '%s'\n",
+ msg.ID(), string(msg.Payload()))
- consumer.Ack(msg)
+ consumer.Ack(msg)
}
-```
-
-> #### Blocking operation
-> When you create a new Pulsar consumer, the operation will block (on a go channel) until either a producer is successfully created or an error is thrown.
+if err := consumer.Unsubscribe(); err != nil {
+ log.Fatal(err)
+}
+```
### Consumer operations
@@ -273,90 +273,178 @@ Pulsar Go consumers have the following methods available:
Method | Description | Return type
:------|:------------|:-----------
-`Topic()` | Returns the consumer's [topic](reference-terminology.md#topic) | `string`
`Subscription()` | Returns the consumer's subscription name | `string`
`Unsubcribe()` | Unsubscribes the consumer from the assigned topic. Throws an error if the unsubscribe operation is somehow unsuccessful. | `error`
`Receive(context.Context)` | Receives a single message from the topic. This method blocks until a message is available. | `(Message, error)`
-`Ack(Message)` | [Acknowledges](reference-terminology.md#acknowledgment-ack) a message to the Pulsar [broker](reference-terminology.md#broker) | `error`
-`AckID(MessageID)` | [Acknowledges](reference-terminology.md#acknowledgment-ack) a message to the Pulsar [broker](reference-terminology.md#broker) by message ID | `error`
-`AckCumulative(Message)` | [Acknowledges](reference-terminology.md#acknowledgment-ack) *all* the messages in the stream, up to and including the specified message. The `AckCumulative` method will block until the ack has been sent to the broker. After that, the messages will *not* be redelivered to the consumer. Cumulative acking can only be used with a [shared](concepts-messaging.md#shared) subscription type. | `error`
-`AckCumulativeID(MessageID)` |Ack the reception of all the messages in the stream up to (and including) the provided message. This method will block until the acknowledge has been sent to the broker. After that, the messages will not be re-delivered to this consumer. | error
-`Nack(Message)` | Acknowledge the failure to process a single message. | `error`
-`NackID(MessageID)` | Acknowledge the failure to process a single message. | `error`
-`Close()` | Closes the consumer, disabling its ability to receive messages from the broker | `error`
-`RedeliverUnackedMessages()` | Redelivers *all* unacknowledged messages on the topic. In [failover](concepts-messaging.md#failover) mode, this request is ignored if the consumer isn't active on the specified topic; in [shared](concepts-messaging.md#shared) mode, redelivered messages are distributed across all consumers connected to the topic. **Note**: this is a *non-blocking* operation that doesn't throw an error. |
-`Seek(msgID MessageID)` | Reset the subscription associated with this consumer to a specific message id. The message id can either be a specific message or represent the first or last messages in the topic. | error
+`Ack(Message)` | [Acknowledges](reference-terminology.md#acknowledgment-ack) a message to the Pulsar [broker](reference-terminology.md#broker) |
+`AckID(MessageID)` | [Acknowledges](reference-terminology.md#acknowledgment-ack) a message to the Pulsar [broker](reference-terminology.md#broker) by message ID |
+`Nack(Message)` | Acknowledge the failure to process a single message. |
+`NackID(MessageID)` | Acknowledge the failure to process a single message. |
+`Seek(msgID MessageID)` | Reset the subscription associated with this consumer to a specific message id. The message id can either be a specific message or represent the first or last messages in the topic. | `error`
+`SeekByTime(time time.Time)` | Reset the subscription associated with this consumer to a specific message publish time. | `error`
+`Close()` | Closes the consumer, disabling its ability to receive messages from the broker |
+
+### Receive example
+
+#### How to use regx consumer
+
+```go
+client, err := pulsar.NewClient(pulsar.ClientOptions{
+ URL: "pulsar://localhost:6650",
+})
+
+defer client.Close()
+
+p, err := client.CreateProducer(ProducerOptions{
+ Topic: topicInRegex,
+ DisableBatching: true,
+})
+if err != nil {
+ log.Fatal(err)
+}
+defer p.Close()
-#### Receive example
+topicsPattern := fmt.Sprintf("persistent://%s/foo.*", namespace)
+opts := ConsumerOptions{
+ TopicsPattern: topicsPattern,
+ SubscriptionName: "regex-sub",
+}
+consumer, err := client.Subscribe(opts)
+if err != nil {
+ log.Fatal(err)
+}
+defer consumer.Close()
+```
+
+#### How to use multi topics Consumer
+
+```go
+func newTopicName() string {
+ return fmt.Sprintf("my-topic-%v", time.Now().Nanosecond())
+}
+
+
+topic1 := "topic-1"
+topic2 := "topic-2"
+
+client, err := NewClient(ClientOptions{
+ URL: "pulsar://localhost:6650",
+})
+if err != nil {
+ log.Fatal(err)
+}
+topics := []string{topic1, topic2}
+consumer, err := client.Subscribe(ConsumerOptions{
+ Topics: topics,
+ SubscriptionName: "multi-topic-sub",
+})
+if err != nil {
+ log.Fatal(err)
+}
+defer consumer.Close()
+```
-Here's an example usage of a Go consumer that uses the `Receive()` method to process incoming messages:
+#### How to use consumer listener
```go
import (
- "context"
- "log"
+ "fmt"
+ "log"
- "github.com/apache/pulsar/pulsar-client-go/pulsar"
+ "github.com/apache/pulsar-client-go/pulsar"
)
func main() {
- // Instantiate a Pulsar client
- client, err := pulsar.NewClient(pulsar.ClientOptions{
- URL: "pulsar://localhost:6650",
- })
+ client, err := pulsar.NewClient(pulsar.ClientOptions{URL: "pulsar://localhost:6650"})
+ if err != nil {
+ log.Fatal(err)
+ }
- if err != nil { log.Fatal(err) }
+ defer client.Close()
- // Use the client object to instantiate a consumer
- consumer, err := client.Subscribe(pulsar.ConsumerOptions{
- Topic: "my-golang-topic",
- SubscriptionName: "sub-1",
- Type: pulsar.Exclusive,
- })
+ channel := make(chan pulsar.ConsumerMessage, 100)
- if err != nil { log.Fatal(err) }
+ options := pulsar.ConsumerOptions{
+ Topic: "topic-1",
+ SubscriptionName: "my-subscription",
+ Type: pulsar.Shared,
+ }
- defer consumer.Close()
+ options.MessageChannel = channel
- ctx := context.Background()
+ consumer, err := client.Subscribe(options)
+ if err != nil {
+ log.Fatal(err)
+ }
- // Listen indefinitely on the topic
- for {
- msg, err := consumer.Receive(ctx)
- if err != nil { log.Fatal(err) }
+ defer consumer.Close()
- // Do something with the message
- err = processMessage(msg)
+ // Receive messages from channel. The channel returns a struct which contains message and the consumer from where
+ // the message was received. It's not necessary here since we have 1 single consumer, but the channel could be
+ // shared across multiple consumers as well
+ for cm := range channel {
+ msg := cm.Message
+ fmt.Printf("Received message msgId: %v -- content: '%s'\n",
+ msg.ID(), string(msg.Payload()))
- if err == nil {
- // Message processed successfully
- consumer.Ack(msg)
- } else {
- // Failed to process messages
- consumer.Nack(msg)
- }
- }
+ consumer.Ack(msg)
+ }
}
```
+#### How to use consumer receive timeout
+
+```go
+client, err := NewClient(ClientOptions{
+ URL: "pulsar://localhost:6650",
+})
+if err != nil {
+ log.Fatal(err)
+}
+defer client.Close()
+
+topic := "test-topic-with-no-messages"
+ctx, cancel := context.WithTimeout(context.Background(), 500*time.Millisecond)
+defer cancel()
+
+// create consumer
+consumer, err := client.Subscribe(ConsumerOptions{
+ Topic: topic,
+ SubscriptionName: "my-sub1",
+ Type: Shared,
+})
+if err != nil {
+ log.Fatal(err)
+}
+defer consumer.Close()
+
+msg, err := consumer.Receive(ctx)
+fmt.Println(msg.Payload())
+if err != nil {
+ log.Fatal(err)
+}
+```
+
+
### Consumer configuration
-Parameter | Description | Default
-:---------|:------------|:-------
-`Topic` | The Pulsar [topic](reference-terminology.md#topic) on which the consumer will establish a subscription and listen for messages |
-`Topics` | Specify a list of topics this consumer will subscribe on. Either a topic, a list of topics or a topics pattern are required when subscribing |
-`TopicsPattern` | Specify a regular expression to subscribe to multiple topics under the same namespace. Either a topic, a list of topics or a topics pattern are required when subscribing |
-`SubscriptionName` | The subscription name for this consumer |
-`Properties` | Attach a set of application defined properties to the consumer. This properties will be visible in the topic stats|
-`Name` | The name of the consumer |
-`AckTimeout` | Set the timeout for unacked messages | 0
-`NackRedeliveryDelay` | The delay after which to redeliver the messages that failed to be processed. Default is 1min. (See `Consumer.Nack()`) | 1 minute
-`Type` | Available options are `Exclusive`, `Shared`, and `Failover` | `Exclusive`
-`SubscriptionInitPos` | InitialPosition at which the cursor will be set when subscribe | Latest
-`MessageChannel` | The Go channel used by the consumer. Messages that arrive from the Pulsar topic(s) will be passed to this channel. |
-`ReceiverQueueSize` | Sets the size of the consumer's receiver queue, i.e. the number of messages that can be accumulated by the consumer before the application calls `Receive`. A value higher than the default of 1000 could increase consumer throughput, though at the expense of more memory utilization. | 1000
-`MaxTotalReceiverQueueSizeAcrossPartitions` |Set the max total receiver queue size across partitions. This setting will be used to reduce the receiver queue size for individual partitions if the total exceeds this value | 50000
-`ReadCompacted` | If enabled, the consumer will read messages from the compacted topic rather than reading the full message backlog of the topic. This means that, if the topic has been compacted, the consumer will only see the latest value for each key in the topic, up until the point in the topic message backlog that has been compacted. Beyond that point, the messages will be sent as normal. |
+ Name | Description | Default
+| :-------- | :---------- |:---------- |
+| Topic | Topic specify the topic this consumer will subscribe to. This argument is required when constructing the reader. | |
+| Topics | Specify a list of topics this consumer will subscribe on. Either a topic, a list of topics or a topics pattern are required when subscribing| |
+| TopicsPattern | Specify a regular expression to subscribe to multiple topics under the same namespace. Either a topic, a list of topics or a topics pattern are required when subscribing | |
+| AutoDiscoveryPeriod | Specify the interval in which to poll for new partitions or new topics if using a TopicsPattern. | |
+| SubscriptionName | Specify the subscription name for this consumer. This argument is required when subscribing | |
+| Name | Set the consumer name | |
+| Properties | Properties attach a set of application defined properties to the producer This properties will be visible in the topic stats | |
+| Type | Select the subscription type to be used when subscribing to the topic. | Exclusive |
+| SubscriptionInitialPosition | InitialPosition at which the cursor will be set when subscribe | Latest |
+| DLQ | Configuration for Dead Letter Queue consumer policy. | no DLQ |
+| MessageChannel | Sets a `MessageChannel` for the consumer. When a message is received, it will be pushed to the channel for consumption | |
+| ReceiverQueueSize | Sets the size of the consumer receive queue. | 1000|
+| NackRedeliveryDelay | The delay after which to redeliver the messages that failed to be processed | 1min |
+| ReadCompacted | If enabled, the consumer will read messages from the compacted topic rather than reading the full message backlog of the topic | false |
+| ReplicateSubscriptionState | Mark the subscription as replicated to keep it in sync across clusters | false |
## Readers
@@ -364,15 +452,15 @@ Pulsar readers process messages from Pulsar topics. Readers are different from c
```go
reader, err := client.CreateReader(pulsar.ReaderOptions{
- Topic: "my-golang-topic",
- StartMessageId: pulsar.LatestMessage,
+ Topic: "topic-1",
+ StartMessageID: pulsar.EarliestMessageID(),
})
+if err != nil {
+ log.Fatal(err)
+}
+defer reader.Close()
```
-> #### Blocking operation
-> When you create a new Pulsar reader, the operation will block (on a go channel) until either a reader is successfully created or an error is thrown.
-
-
### Reader operations
Pulsar Go readers have the following methods available:
@@ -384,70 +472,141 @@ Method | Description | Return type
`HasNext()` | Check if there is any message available to read from the current position| (bool, error)
`Close()` | Closes the reader, disabling its ability to receive messages from the broker | `error`
-#### "Next" example
+### Reader example
+
+#### How to use reader to read 'next' message
Here's an example usage of a Go reader that uses the `Next()` method to process incoming messages:
```go
import (
- "context"
- "log"
+ "context"
+ "fmt"
+ "log"
- "github.com/apache/pulsar/pulsar-client-go/pulsar"
+ "github.com/apache/pulsar-client-go/pulsar"
)
func main() {
- // Instantiate a Pulsar client
- client, err := pulsar.NewClient(pulsar.ClientOptions{
- URL: "pulsar://localhost:6650",
- })
+ client, err := pulsar.NewClient(pulsar.ClientOptions{URL: "pulsar://localhost:6650"})
+ if err != nil {
+ log.Fatal(err)
+ }
+
+ defer client.Close()
+
+ reader, err := client.CreateReader(pulsar.ReaderOptions{
+ Topic: "topic-1",
+ StartMessageID: pulsar.EarliestMessageID(),
+ })
+ if err != nil {
+ log.Fatal(err)
+ }
+ defer reader.Close()
+
+ for reader.HasNext() {
+ msg, err := reader.Next(context.Background())
+ if err != nil {
+ log.Fatal(err)
+ }
+
+ fmt.Printf("Received message msgId: %#v -- content: '%s'\n",
+ msg.ID(), string(msg.Payload()))
+ }
+}
+```
- if err != nil { log.Fatalf("Could not create client: %v", err) }
+In the example above, the reader begins reading from the earliest available message (specified by `pulsar.EarliestMessage`). The reader can also begin reading from the latest message (`pulsar.LatestMessage`) or some other message ID specified by bytes using the `DeserializeMessageID` function, which takes a byte array and returns a `MessageID` object. Here's an example:
- // Use the client to instantiate a reader
- reader, err := client.CreateReader(pulsar.ReaderOptions{
- Topic: "my-golang-topic",
- StartMessageID: pulsar.EarliestMessage,
- })
+```go
+lastSavedId := // Read last saved message id from external store as byte[]
- if err != nil { log.Fatalf("Could not create reader: %v", err) }
+reader, err := client.CreateReader(pulsar.ReaderOptions{
+ Topic: "my-golang-topic",
+ StartMessageID: pulsar.DeserializeMessageID(lastSavedId),
+})
+```
- defer reader.Close()
+#### How to use reader to read specific message
- ctx := context.Background()
+```go
+client, err := NewClient(ClientOptions{
+ URL: lookupURL,
+})
- // Listen on the topic for incoming messages
- for {
- msg, err := reader.Next(ctx)
- if err != nil { log.Fatalf("Error reading from topic: %v", err) }
+if err != nil {
+ log.Fatal(err)
+}
+defer client.Close()
- // Process the message
- }
+topic := "topic-1"
+ctx := context.Background()
+
+// create producer
+producer, err := client.CreateProducer(ProducerOptions{
+ Topic: topic,
+ DisableBatching: true,
+})
+if err != nil {
+ log.Fatal(err)
}
-```
+defer producer.Close()
-In the example above, the reader begins reading from the earliest available message (specified by `pulsar.EarliestMessage`). The reader can also begin reading from the latest message (`pulsar.LatestMessage`) or some other message ID specified by bytes using the `DeserializeMessageID` function, which takes a byte array and returns a `MessageID` object. Here's an example:
+// send 10 messages
+msgIDs := [10]MessageID{}
+for i := 0; i < 10; i++ {
+ msgID, err := producer.Send(ctx, &ProducerMessage{
+ Payload: []byte(fmt.Sprintf("hello-%d", i)),
+ })
+ assert.NoError(t, err)
+ assert.NotNil(t, msgID)
+ msgIDs[i] = msgID
+}
-```go
-lastSavedId := // Read last saved message id from external store as byte[]
+// create reader on 5th message (not included)
+reader, err := client.CreateReader(ReaderOptions{
+ Topic: topic,
+ StartMessageID: msgIDs[4],
+})
-reader, err := client.CreateReader(pulsar.ReaderOptions{
- Topic: "my-golang-topic",
- StartMessageID: DeserializeMessageID(lastSavedId),
+if err != nil {
+ log.Fatal(err)
+}
+defer reader.Close()
+
+// receive the remaining 5 messages
+for i := 5; i < 10; i++ {
+ msg, err := reader.Next(context.Background())
+ if err != nil {
+ log.Fatal(err)
+}
+
+// create reader on 5th message (included)
+readerInclusive, err := client.CreateReader(ReaderOptions{
+ Topic: topic,
+ StartMessageID: msgIDs[4],
+ StartMessageIDInclusive: true,
})
+
+if err != nil {
+ log.Fatal(err)
+}
+defer readerInclusive.Close()
```
### Reader configuration
-Parameter | Description | Default
-:---------|:------------|:-------
-`Topic` | The Pulsar [topic](reference-terminology.md#topic) on which the reader will establish a subscription and listen for messages
-`Name` | The name of the reader
-`StartMessageID` | THe initial reader position, i.e. the message at which the reader begins processing messages. The options are `pulsar.EarliestMessage` (the earliest available message on the topic), `pulsar.LatestMessage` (the latest available message on the topic), or a `MessageID` object for a position that isn't earliest or latest. |
-`MessageChannel` | The Go channel used by the reader. Messages that arrive from the Pulsar topic(s) will be passed to this channel. |
-`ReceiverQueueSize` | Sets the size of the reader's receiver queue, i.e. the number of messages that can be accumulated by the reader before the application calls `Next`. A value higher than the default of 1000 could increase reader throughput, though at the expense of more memory utilization. | 1000
-`SubscriptionRolePrefix` | The subscription role prefix. | `reader`
-`ReadCompacted` | If enabled, the reader will read messages from the compacted topic rather than reading the full message backlog of the topic. This means that, if the topic has been compacted, the reader will only see the latest value for each key in the topic, up until the point in the topic message backlog that has been compacted. Beyond that point, the messages will be sent as normal.|
+ Name | Description | Default
+| :-------- | :---------- |:---------- |
+| Topic | Topic specify the topic this consumer will subscribe to. This argument is required when constructing the reader. | |
+| Name | Name set the reader name. | |
+| Properties | Attach a set of application defined properties to the reader. This properties will be visible in the topic stats | |
+| StartMessageID | StartMessageID initial reader positioning is done by specifying a message id. | |
+| StartMessageIDInclusive | If true, the reader will start at the `StartMessageID`, included. Default is `false` and the reader will start from the "next" message | false |
+| MessageChannel | MessageChannel sets a `MessageChannel` for the consumer When a message is received, it will be pushed to the channel for consumption| |
+| ReceiverQueueSize | ReceiverQueueSize sets the size of the consumer receive queue. | 1000 |
+| SubscriptionRolePrefix| SubscriptionRolePrefix set the subscription role prefix. | “reader” |
+| ReadCompacted | If enabled, the reader will read messages from the compacted topic rather than reading the full message backlog of the topic. ReadCompacted can only be enabled when reading from a persistent topic. | false|
## Messages
@@ -464,7 +623,7 @@ msg := pulsar.ProducerMessage{
ReplicationClusters: []string{"cluster1", "cluster3"},
}
-if err := producer.send(msg); err != nil {
+if _, err := producer.send(msg); err != nil {
log.Fatalf("Could not publish message due to: %v", err)
}
```
@@ -474,12 +633,13 @@ The following methods parameters are available for `ProducerMessage` objects:
Parameter | Description
:---------|:-----------
`Payload` | The actual data payload of the message
-`Value` | Value and payload is mutually exclusive, `Value interface{}` for schema message.
`Key` | The optional key associated with the message (particularly useful for things like topic compaction)
`Properties` | A key-value map (both keys and values must be strings) for any application-specific metadata attached to the message
`EventTime` | The timestamp associated with the message
`ReplicationClusters` | The clusters to which this message will be replicated. Pulsar brokers handle message replication automatically; you should only change this setting if you want to override the broker default.
`SequenceID` | Set the sequence id to assign to the current message
+`DeliverAfter` | Request to deliver the message only after the specified relative delay
+`DeliverAt` | Deliver the message only at or after the specified absolute timestamp
## TLS encryption and authentication