The KubeMQ SDK for NodeJS enables Node JS/Typescript developers to seamlessly communicate with the KubeMQ server, implementing various communication patterns such as Events, EventStore, Commands, Queries, and Queues.

Prerequisites

• Node.js (Ensure you have a recent version of Node.js installed)

• TypeScript Compiler

• KubeMQ server running locally or accessible over the network

Installation

The recommended way to use the SDK for Node in your project is to consume it from Node package manager.

npm install kubemq-js

Payload Details

• Metadata: The metadata allows us to pass additional information with the event. Can be in any form that can be presented as a string, i.e., struct, JSON, XML and many more.
• Body: The actual content of the event. Can be in any form that is serializable into a byte array, i.e., string, struct, JSON, XML, Collection, binary file and many more.
• ClientID: Displayed in logs, tracing, and KubeMQ dashboard(When using Events Store, it must be unique).
• Tags: Set of Key-value pair that help categorize the message

KubeMQ PubSub Client

For executing PubSub operation we have to create the instance of PubsubClient, its instance can be created with minimum two parameter address (KubeMQ server address) & clientId . With these two parameter plainText connections are established. The table below describes the Parameters available for establishing a connection.

PubSub Client Configuration

Name	Type	Description	Default Value	Mandatory
address	String	The address of the KubeMQ server.	None	Yes
clientId	String	The client ID used for authentication.	None	Yes
authToken	String	The authorization token for secure communication.	None	No
tls	boolean	Indicates if TLS (Transport Layer Security) is enabled.	None	No
tlsCertFile	String	The path to the TLS certificate file.	None	No (Yes if tls is true)
tlsKeyFile	String	The path to the TLS key file.	None	No (Yes if tls is true)
tlsCaCertFile	String	The path to the TLS CA cert file.	None	No (Yes if tls is true)
maxReceiveSize	int	The maximum size of the messages to receive (in bytes).	104857600 (100MB)	No
reconnectIntervalSeconds	int	The interval in seconds between reconnection attempts.	1	No

Pubsub Client connection establishment example code

1
2const  opts: Config = {
3	address:  'localhost:50000',
4	clientId:  Utils.uuid(),
5	reconnectIntervalSeconds:  1,
6};
7
8const  pubsubClient = new  PubsubClient(opts);
9

The example below demonstrates to construct PubSubClient with ssl and other configurations:

1
2const  config: Config = {
3
4	address:  'localhost:50000', // KubeMQ gRPC endpoint address
5	clientId:  'your-client-id', // Connection clientId
6	authToken:  'your-jwt-auth-token', // Optional JWT authorization token
7	tls:  true, // Indicates if TLS is enabled
8	tlsCertFile:  'path/to/tls-cert.pem', // Path to the TLS certificate file
9	tlsKeyFile:  'path/to/tls-key.pem', // Path to the TLS key file
10	tlsCaCertFile:  'path/to/tls-key.pem', // Path to the TLS key file
11	maxReceiveSize:  1024 * 1024 * 100, // Maximum size of the messages to receive (100MB)
12	reconnectIntervalSeconds:  1 // Interval in milliseconds between reconnect attempts (1 second)
13};
14

Ping To KubeMQ server

You can ping the server to check connection is established or not.

Request: NONE

Response: ServerInfo Interface Attributes

Name	Type	Description
host	String	The host of the server.
version	String	The version of the server.
serverStartTime	long	The start time of the server (in seconds).
serverUpTimeSeconds	long	The uptime of the server (in seconds).

1
2ServerInfo  pingResult = pubsubClient.ping();
3console.log('Ping Response: ' + pingResult);
4

Create Channel

PubSub CreateEventsChannel Example:

Request:

Name	Type	Description	Default Value	Mandatory
channelName	String	Channel name which you want to create	None	Yes

Response:

Name	Type	Description
void	Promise	Doesn't return a value upon completion

1
2async  function  createEventsChannel(channel: string) {
3return  pubsubClient.createEventsChannel(channel);
4}
5

PubSub Create Events Store Channel Example:

Request:

Name	Type	Description	Default Value	Mandatory
channelName	String	Channel name to which you want to create	None	Yes

Response:

Name	Type	Description
void	Promise	Doesn't return a value upon completion

---

1
2async  function  createEventsStoreChannel(channel: string) {
3return  pubsubClient.createEventsStoreChannel(channel);
4}
5

Delete Channel

PubSub DeleteEventsChannel Example:

Request:

Name	Type	Description	Default Value	Mandatory
channelName	String	Channel name which you want to delete	None	Yes

Response:

Name	Type	Description
void	Promise	Doesn't return a value upon completion

1
2async  function  deleteEventsChannel(channel: string) {
3return  pubsubClient.deleteEventsChannel(channel);
4}
5

PubSub Delete Events Store Channel Example:

Request:

Name	Type	Description	Default Value	Mandatory
channelName	String	Channel name to which you want to delete	None	Yes

Response:

Name	Type	Description
void	Promise	Doesn't return a value upon completion

1
2async  function  deleteEventsStoreChannel(channel: string) {
3return  pubsubClient.deleteEventsStoreChannel(channel);
4}
5

List Channels

PubSub ListEventsChannel Example:

Request:

Name	Type	Description	Default Value	Mandatory
search	String	Search query to filter channels (optional)	None	No

Response: PubSubChannel[] PubSubChannel interface Attributes

Name	Type	Description
name	String	The name of the Pub/Sub channel.
type	String	The type of the Pub/Sub channel.
lastActivity	long	The timestamp of the last activity on the channel, represented in milliseconds since epoch.
isActive	boolean	Indicates whether the channel is active or not.
incoming	PubSubStats	The statistics related to incoming messages for this channel.
outgoing	PubSubStats	The statistics related to outgoing messages for this channel.

1
2async  function  listEventsChannel(search: string) {
3	const  channels = await  pubsubClient.listEventsChannels(search);
4	console.log(channels);
5}
6

PubSub ListEventsStoreChannel Example:

Request:

Name	Type	Description	Default Value	Mandatory
search	String	Search query to filter channels (optional)	None	No

Response: PubSubChannel[] PubSubChannel interface Attributes

Name	Type	Description
name	String	The name of the Pub/Sub channel.
type	String	The type of the Pub/Sub channel.
lastActivity	long	The timestamp of the last activity on the channel, represented in milliseconds since epoch.
isActive	boolean	Indicates whether the channel is active or not.
incoming	PubSubStats	The statistics related to incoming messages for this channel.
outgoing	PubSubStats	The statistics related to outgoing messages for this channel.

1
2async  function  listEventsStoreChannel(search: string) {
3	const  channels = await  pubsubClient.listEventsStoreChannels(search);
4	console.log(channels);
5}
6

PubSub Send & Receive

PubSub SendEventMessage Example:

Request: EventMessage Interface Attributes

Name	Type	Description	Default Value	Mandatory
id	String	Unique identifier for the event message.	None	No
channel	String	The channel to which the event message is sent.	None	Yes
metadata	String	Metadata associated with the event message.	None	No
body	byte[]	Body of the event message in bytes.	Empty byte array	No
tags	Map<String, String>	Tags associated with the event message as key-value pairs.	Empty Map	No

Note:- metadata or body or tags any one is required

Response: NONE

1
2await  pubsubClient.sendEventsMessage({
3	id:  `234`,
4	channel: 'events.single',
5	body:  Utils.stringToBytes('event message'),
6});
7

PubSub SendEventStoreMessage Example:

Request: EventStoreMessage Class Attributes

Name	Type	Description	Default Value	Mandatory
id	String	Unique identifier for the event message.	None	No
channel	String	The channel to which the event message is sent.	None	Yes
metadata	String	Metadata associated with the event message.	None	No
body	byte[]	Body of the event message in bytes.	Empty byte array	No
tags	Map<String, String>	Tags associated with the event message as key-value pairs.	Empty Map	No

Note:- metadata or body or tags any one is required

Response: NONE

1
2await  pubsubClient.sendEventStoreMessage({
3	id:  '987',
4	channel: 'events_store.single',
5	body:  Utils.stringToBytes('event store message'),
6});
7

PubSub SubscribeEvents Example:

Request: EventsSubscription Class Attributes

Name	Type	Description	Default Value	Mandatory
channel	String	The channel to subscribe to.	None	Yes
group	String	The group to subscribe with.	None	No
onReceiveEventCallback	Consumer	Callback function to be called when an event message is received.	None	Yes
onErrorCallback	Consumer	Callback function to be called when an error occurs.	None	No

Response: NONE

Callback: EventMessageReceived class details

Name	Type	Description
id	String	The unique identifier of the message.
fromClientId	String	The ID of the client that sent the message.
timestamp	long	The timestamp when the message was received, in seconds.
channel	String	The channel to which the message belongs.
metadata	String	The metadata associated with the message.
body	byte[]	The body of the message.
sequence	long	The sequence number of the message.
tags	Map<String, String>	The tags associated with the message.

1async function subscribeToEvent() {  
2  //Subscribes to events from the specified channel and processes received events.  
3  const eventsSubscriptionRequest = new EventsSubscriptionRequest('events.A', '');  
4  
5  // Define the callback for receiving events  
6  eventsSubscriptionRequest.onReceiveEventCallback = (event: EventMessageReceived) => {  
7    console.log('SubscriberA received event:', {  
8      id: event.id,  
9      fromClientId: event.fromClientId,  
10      timestamp: event.timestamp,  
11      channel: event.channel,  
12      metadata: event.metadata,  
13      body: event.body,  
14      tags: event.tags,  
15    });  
16  };  
17  
18  // Define the callback for handling errors  
19  eventsSubscriptionRequest.onErrorCallback = (error: string) => {  
20    console.error('SubscriberA error:', error);  
21  };  
22  
23  pubsubClient  
24  .subscribeToEvents(eventsSubscriptionRequest)  
25    .then(() => {  
26      console.log('Subscription successful');  
27    })  
28    .catch((reason: any) => {  
29      console.error('Subscription failed:', reason);  
30    });  
31  
32}

PubSub SubscribeEventsStore Example:

Request: EventsStoreSubscription Interface Attributes

Name	Type	Description	Default Value	Mandatory
channel	String	The channel to subscribe to.	None	Yes
group	String	The group to subscribe with.	None	No
onReceiveEventCallback	Consumer	Callback function to be called when an event message is received.	None	Yes
onErrorCallback	Consumer	Callback function to be called when an error occurs.	None	No

Response: None

Callback: EventStoreMessageReceived class details

Name	Type	Description
id	String	The unique identifier of the message.
fromClientId	String	The ID of the client that sent the message.
timestamp	long	The timestamp when the message was received, in seconds.
channel	String	The channel to which the message belongs.
metadata	String	The metadata associated with the message.
body	byte[]	The body of the message.
sequence	long	The sequence number of the message.
tags	Map<String, String>	The tags associated with the message.

1async function subscribeToEventStore() {  
2  //Subscribes to events store messages from the specified channel with a specific configuration.  
3  const eventsSubscriptionRequest = new EventsStoreSubscriptionRequest('events_store.A', '');  
4  eventsSubscriptionRequest.eventsStoreType = EventStoreType.StartAtSequence;  
5  eventsSubscriptionRequest.eventsStoreSequenceValue=1;  
6  
7  // Define the callback for receiving events  
8  eventsSubscriptionRequest.onReceiveEventCallback = (event: EventStoreMessageReceived) => {  
9    console.log('SubscriberA received event:', {  
10      id: event.id,  
11      fromClientId: event.fromClientId,  
12      timestamp: event.timestamp,  
13      channel: event.channel,  
14      metadata: event.metadata,  
15      body: event.body,  
16      tags: event.tags,  
17      sequence: event.sequence,  
18    });  
19  };  
20  
21  // Define the callback for handling errors  
22  eventsSubscriptionRequest.onErrorCallback = (error: string) => {  
23    console.error('SubscriberA error:', error);  
24  };  
25  
26  pubsubClient  
27  .subscribeToEvents(eventsSubscriptionRequest)  
28    .then(() => {  
29      console.log('Events Subscription successful');  
30    })  
31    .catch((reason: any) => {  
32      console.error('Event Subscription failed:', reason);  
33    });  
34}

KubeMQ Queues Operations

The examples below demonstrate the usage of KubeMQ Queues client. The examples include creating, deleting, listing channels, and sending/receiving queues messages.

Construct the Queues Client

For executing Queues operation we have to create the instance of QueuesClient, its instance can be created with minimum two parameter address (KubeMQ server address) & clientId . With these two parameter plainText connections are established. The table below describes the Parameters available for establishing a connection.

QueuesClient Configuration

Name	Type	Description	Default Value	Mandatory
address	String	The address of the KubeMQ server.	None	Yes
clientId	String	The client ID used for authentication.	None	Yes
authToken	String	The authorization token for secure communication.	None	No
tls	boolean	Indicates if TLS (Transport Layer Security) is enabled.	None	No
tlsCertFile	String	The path to the TLS certificate file.	None	No (Yes if tls is true)
tlsKeyFile	String	The path to the TLS key file.	None	No (Yes if tls is true)
tlsCaCertFile	String	The path to the TLS CA cert file.	None	No (Yes if tls is true)
maxReceiveSize	int	The maximum size of the messages to receive (in bytes).	104857600 (100MB)	No
reconnectIntervalSeconds	int	The interval in seconds between reconnection attempts.	1	No

Queues Client establishing a connection example code

1
2const  opts: Config = {
3	address:  'localhost:50000',
4	clientId:  Utils.uuid(),
5};
6
7const  queuesClient = new  QueuesClient(opts);
8

The example below demonstrates to construct PubSubClient with ssl and other configurations:

1const  opts: Config = {
2	address:  'localhost:50000', // KubeMQ gRPC endpoint address
3	clientId:  'your-client-id', // Connection clientId
4	authToken:  'your-jwt-auth-token', // Optional JWT authorization token
5	tls:  true, // Indicates if TLS is enabled
6	tlsCertFile:  'path/to/tls-cert.pem', // Path to the TLS certificate file
7	tlsKeyFile:  'path/to/tls-key.pem', // Path to the TLS key file
8	tlsCaCertFile:  'path/to/tls-ca-cert.pem', // Path to the TLS CA cert file
9	maxReceiveSize:  1024 * 1024 * 100, // The Maximum size of the messages to receive (100MB)
10	reconnectIntervalSeconds:  1 // Interval in milliseconds between reconnect attempts (1 second)
11};
12
13const  queuesClient = new  QueuesClient(opts);

Ping To KubeMQ server

You can ping the server to check connection is established or not.

Request: NONE

Response: ServerInfo Class Attributes

Name	Type	Description
host	String	The host of the server.
version	String	The version of the server.
serverStartTime	long	The start time of the server (in seconds).
serverUpTimeSeconds	long	The uptime of the server (in seconds).

1
2const  pingResult = queuesClient.ping();
3console.log('Ping Response: ' + pingResult);
4

Create Channel

Queues CreateQueueChannel Example:

Request:

Name	Type	Description	Default Value	Mandatory
channelName	String	The name of the channel you want to create	None	Yes

Response:

Name	Type	Description
void	Promise	Doesn't return a value upon completion

1
2async  function  createQueueChannel(channel: string) {
3	return  queuesClient.createQueuesChannel(channel);
4}
5

Delete Channel

Queues DeleteQueueChannel Example:

Request:

Name	Type	Description	Default Value	Mandatory
channelName	String	The name of the channel you want to delete	None	Yes

Response:

Name	Type	Description
void	Promise	Doesn't return a value upon completion

1
2async  function  createQueueChannel(channel: string) {
3	return  queuesClient.deleteQueuesChannel(channel);
4}
5

List Channels

Queues listQueueChannels Example:

Request:

Name	Type	Description	Default Value	Mandatory
searchString	String	The channel name you want to search for	None	No

Response: QueuesChannel[] QueuesChannel interface Attributes

Name	Type	Description
name	String	The name of the queue channel.
type	String	The type of the queue channel.
lastActivity	long	The timestamp of the last activity in the queue channel.
isActive	boolean	Indicates whether the queue channel is currently active.
incoming	QueuesStats	The statistics for incoming messages in the queue channel.
outgoing	QueuesStats	The statistics for outgoing messages in the queue channel.

1
2async  function  listQueueChannels(search: string) {
3	const  channels = await  queuesClient.listQueuesChannel(search);
4	console.log(channels);
5}
6

Send & Receive Queue Messages

Queues SendSingleMessage Example:

Request: QueueMessage class attributes

Name	Type	Description	Default Value	Mandatory
id	String	The unique identifier for the message.	None	No
channel	String	The channel of the message.	None	Yes
metadata	String	The metadata associated with the message.	None	No
body	byte[]	The body of the message.	new byte[0]	No
tags	Map<String, String>	The tags associated with the message.	new HashMap<>()	No
delayInSeconds	int	The delay in seconds before the message becomes available in the queue.	None	No
expirationInSeconds	int	The expiration time in seconds for the message.	None	No
attemptsBeforeDeadLetterQueue	int	The number of receive attempts allowed before the message is moved to the dead letter queue.	None	No
deadLetterQueue	String	The dead letter queue where the message will be moved after reaching max receive attempts.	None	No

Response: QueueSendResult class attributes

Name	Type	Description
id	String	The unique identifier of the message.
sentAt	LocalDateTime	The timestamp when the message was sent.
expiredAt	LocalDateTime	The timestamp when the message will expire.
delayedTo	LocalDateTime	The timestamp when the message will be delivered.
isError	boolean	Indicates if there was an error while sending the message.
error	String	The error message if isError is true.

1
2await  queuesClient.sendQueuesMessage({
3	channel:  'queues.single',
4	body:  Utils.stringToBytes('queue message'),
5})
6.then((result) =>  console.log(result))
7.catch((reason) =>  console.error(reason));

Queues Pulls messages from a queue. Example:

Request: QueuesPullWaitingMessagesRequest class attributes

Name	Type	Description	Default Value	Mandatory
channel	String	The channel to poll messages from.	None	Yes
maxNumberOfMessages	int	The maximum number of messages to poll.	1	No
waitTimeoutSeconds	int	The wait timeout in seconds for polling messages.	60	No

Response: QueuesPullWaitingMessagesResponse class attributes

Name	Type	Description
id	String	The reference ID of the request.
messagesReceived	number	Number of valid messages received.
messages	QueueMessage[]	The list of received queue messages.
error	String	The error message, if any error occurred.
isError	boolean	Indicates if there was an error.
isPeek	boolean	Indicates if it is a peek or pull operation.
messagesExpired	number	Number of expired messages from the queue.

1
2await  queuesClient
3.pull({
4	channel:  'queues.peek',
5	maxNumberOfMessages:  10,
6	waitTimeoutSeconds:  10,
7})
8
9.then((response) => {
10	response.messages.forEach((msg) => {
11	console.log(msg);
12});
13})
14
15.catch((reason) => {
16	console.error(reason);
17});
18

Queues Get waiting messages from a queue Example:

Request: QueuesPullWaitngMessagesRequest class attributes

Name	Type	Description	Default Value	Mandatory
channel	String	The channel to poll messages from.	None	Yes
maxNumberOfMessages	int	The maximum number of messages to poll.	1	No
waitTimeoutSeconds	int	The wait timeout in seconds for polling messages.	60	No

Response: QueuesPullWaitingMessagesResponse class attributes

Name	Type	Description
id	String	The reference ID of the request.
messagesReceived	number	Number of valid messages received.
messages	QueueMessage[]	The list of received queue messages.
error	String	The error message, if any error occurred.
isError	boolean	Indicates if there was an error.
isPeek	boolean	Indicates if the operation is a peek or pull.
messagesExpired	number	Number of expired messages from the queue.

1
2await  queuesClient
3.waiting({
4	channel:  'queues.peek',
5	maxNumberOfMessages:  5,
6	waitTimeoutSeconds:  20,
7})
8
9.then((response) => {
10	response.messages.forEach((msg) => {
11	console.log(msg);
12});
13})
14.catch((reason) => {
15	console.error(reason);
16});
17

Poll Queue Messages

Receives messages from a Queue channel.

Request: QueuesPollRequest Class Attributes

Name	Type	Description	Default Value	Mandatory
channel	String	The channel to poll messages from.	None	Yes
pollMaxMessages	int	The maximum number of messages to poll.	1	No
pollWaitTimeoutInSeconds	int	The wait timeout in seconds for polling messages.	60	No
autoAckMessages	boolean	Indicates if messages should be auto-acknowledged.	false	No
visibilitySeconds	int	Add a visibility timeout feature for messages.	0	No

Response: QueuesMessagesPulledResponse Class Attributes

Name	Type	Description
id	String	The reference ID of the request.
messages	QueueMessageReceived[]	The list of received queue messages.
messagesReceived	number	Number of valid messages received.
messagesExpired	number	Number of messages expired.
isPeek	boolean	Indicates if the operation is a peek or pull.
error	String	The error message, if any error occurred.
isError	boolean	Indicates if there was an error.
visibilitySeconds	int	The visibility timeout for the message in seconds.
isAutoAcked	boolean	Indicates whether the message was auto-acknowledged.

Response: QueueMessageReceived class attributes

Here's the requested Markdown table for the QueueMessageReceived class:

Name	Type	Description
id	String	The unique identifier for the message.
channel	String	The channel from which the message was received.
metadata	String	Metadata associated with the message.
body	byte[]	The body of the message in byte array format.
fromClientId	String	The ID of the client that sent the message.
tags	Map<String, String>	Key-value pairs representing tags for the message.
timestamp	Instant	The timestamp when the message was created.
sequence	long	The sequence number of the message.
receiveCount	int	The number of times the message has been received.
isReRouted	boolean	Indicates whether the message was rerouted.
reRouteFromQueue	String	The name of the queue from which the message was rerouted.
expiredAt	Instant	The expiration time of the message, if applicable.
delayedTo	Instant	The time the message is delayed until, if applicable.
transactionId	String	The transaction ID associated with the message.
isTransactionCompleted	boolean	Indicates whether the transaction for the message is completed.
responseHandler	StreamObserver<QueuesDownstreamRequest>	The response handler for processing downstream requests.
receiverClientId	String	The ID of the client receiving the message.
visibilitySeconds	int	The visibility timeout for the message in seconds.
isAutoAcked	boolean	Indicates whether the message was auto-acknowledged.

Example

1async function main() {  
2  const opts: Config = {  
3    address: 'localhost:50000',  
4    clientId: 'kubeMQClientId-ts',  
5  };  
6  const queuesClient = new QueuesClient(opts);  
7  
8  // Receive with message visibility  
9  async function receiveWithVisibility(visibilitySeconds: number) {  
10    console.log("\n============================== Receive with Visibility =============================\n");  
11    try {  
12      const pollRequest = new QueuesPollRequest({  
13        channel: 'visibility_channel',  
14        pollMaxMessages: 1,  
15        pollWaitTimeoutInSeconds: 10,  
16        visibilitySeconds: visibilitySeconds,  
17        autoAckMessages: false,  
18      });  
19  
20      const pollResponse = await queuesClient.receiveQueuesMessages(pollRequest);  
21      console.log("Received Message Response:", pollResponse);  
22        
23      if (pollResponse.isError) {  
24        console.log("Error: " + pollResponse.error);  
25      } else {  
26        pollResponse.messages.forEach(async (msg) => {  
27          console.log(`Message ID: ${msg.id}, Message Body: ${Utils.bytesToString(msg.body)}`);  
28          try {  
29            await new Promise(resolve => setTimeout(resolve, 1000));  
30            await msg.ack();  
31            console.log("Acknowledged message");  
32          } catch (err) {  
33            console.error("Error acknowledging message:", err);  
34          }  
35        });  
36      }  
37    } catch (error) {  
38      console.error('Failed to receive queue messages:', error);  
39    }  
40  }  
41  
42  // Test visibility expiration  
43  async function receiveWithVisibilityExpired() {  
44    console.log("\n============================== Receive with Visibility Expired =============================\n");  
45    await receiveWithVisibility(2);  
46  }  
47  
48  // Test visibility extension  
49  async function receiveWithVisibilityExtension() {  
50    console.log("\n============================== Receive with Visibility Extension =============================\n");  
51    try {  
52      const pollRequest = new QueuesPollRequest({  
53        channel: 'visibility_channel',  
54        pollMaxMessages: 1,  
55        pollWaitTimeoutInSeconds: 10,  
56        visibilitySeconds: 3,  
57        autoAckMessages: false,  
58      });  
59  
60      const pollResponse = await queuesClient.receiveQueuesMessages(pollRequest);  
61      console.log("Received Message Response:", pollResponse);  
62  
63      if (pollResponse.isError) {  
64        console.log("Error: " + pollResponse.error);  
65      } else {  
66        pollResponse.messages.forEach(async (msg) => {  
67          console.log(`Message ID: ${msg.id}, Message Body: ${Utils.bytesToString(msg.body)}`);  
68          try {  
69            await new Promise(resolve => setTimeout(resolve, 1000));  
70            await msg.extendVisibilityTimer(3);  
71            await new Promise(resolve => setTimeout(resolve, 2000));  
72            await msg.ack();  
73            console.log("Acknowledged message after extending visibility");  
74          } catch (err) {  
75            console.error("Error during visibility extension:", err);  
76          }  
77        });  
78      }  
79    } catch (error) {  
80      console.error('Failed to receive queue messages:', error);  
81    }  
82  }  
83  
84  await receiveWithVisibilityExpired();  
85  await receiveWithVisibilityExtension();  
86}  
87  
88main();

This method allows you to receive messages from a specified Queue channel. You can configure the polling behavior, including the maximum number of messages to receive and the wait timeout. The response provides detailed information about the received messages and the transaction.

Message Handling Options:

1. Acknowledge (ack): Mark the message as processed and remove it from the queue.
2. Reject: Reject the message. It won't be requeued.
3. Requeue: Send the message back to the queue for later processing.

Choose the appropriate handling option based on your application's logic and requirements.

KubeMQ Command & Query Operations

Construct the CQClient

For executing command & query operation we have to create the instance of CQClient, its instance can be created with minimum two parameter address (KubeMQ server address) & clientId . With these two parameter plainText connections are established. The table below describes the Parameters available for establishing a connection.

CQClient Configuration

Name	Type	Description	Default Value	Mandatory
address	String	The address of the KubeMQ server.	None	Yes
clientId	String	The client ID used for authentication.	None	Yes
authToken	String	The authorization token for secure communication.	None	No
tls	boolean	Indicates if TLS (Transport Layer Security) is enabled.	None	No
tlsCertFile	String	The path to the TLS certificate file.	None	No (Yes if tls is true)
tlsKeyFile	String	The path to the TLS key file.	None	No (Yes if tls is true)
tlsCaCertFile	String	The path to the TLS CA cert file.	None	No (Yes if tls is true)
maxReceiveSize	int	The maximum size of the messages to receive (in bytes).	104857600 (100MB)	No
reconnectIntervalSeconds	int	The interval in seconds between reconnection attempts.	1	No

CQClient establishing a connection example code

1
2const  opts: Config = {
3
4    address:  'localhost:50000',
5    clientId:  Utils.uuid(),
6    reconnectIntervalSeconds:  1,
7};
8
9const  cqClient = new  CQClient(opts);
10

The example below demonstrates to construct CQClient with ssl and other configurations:

1
2const  config: Config = {
3
4    address:  'localhost:50000', // KubeMQ gRPC endpoint address
5    clientId:  'your-client-id', // Connection clientId
6    authToken:  'your-jwt-auth-token', // Optional JWT authorization token
7    tls:  true, // Indicates if TLS is enabled
8    tlsCertFile:  'path/to/tls-cert.pem', // Path to the TLS certificate file
9    tlsKeyFile:  'path/to/tls-key.pem', // Path to the TLS key file
10    tlsCaCertFile:  'path/to/tls-ca-cert.pem', // Path to the TLS CA cert file
11    maxReceiveSize:  1024 * 1024 * 100, // Maximum size of the messages to receive (100MB)
12    reconnectIntervalSeconds:  1, // Interval in milliseconds between reconnect attempts (1 second)
13};
14const  cqClient = new  CQClient(opts);
15

Ping To KubeMQ server

You can ping the server to check connection is established or not.

Request: NONE

Response: ServerInfo interface Attributes

Name	Type	Description
host	String	The host of the server.
version	String	The version of the server.
serverStartTime	long	The start time of the server (in seconds).
serverUpTimeSeconds	long	The uptime of the server (in seconds).

1
2const  pingResult = cqClient.ping();
3console.log('Ping Response: ' + pingResult);
4

Create Channel

Command CreateCommandsChannel Example:

Request:

Name	Type	Description	Default Value	Mandatory
channelName	String	Channel name which you want to create	None	Yes

Response:

Name	Type	Description
void	Promise	Doesn't return a value upon completion

1
2async  function  createCommandsChannel(channel: string) {
3    return  cqClient.createCommandsChannel(channel);
4}

Queries CreateQueriesChannel Example:

Request:

Name	Type	Description	Default Value	Mandatory
channelName	String	The name of the channel to create.	None	Yes

Response:

Name	Type	Description
void	Promise	Doesn't return a value upon completion

1
2async  function  createQueriesChannel(channel: string) {
3    return  cqClient.createQueriesChannel(channel);
4}
5

Delete Channel

Command DeleteCommandsChannel Example:

Request:

Name	Type	Description	Default Value	Mandatory
channelName	String	Channel name which you want to delete	None	Yes

Response:

Name	Type	Description
void	Promise	Doesn't return a value upon completion

1
2async  function  deleteCommandsChannel(channel: string) {
3    return  cqClient.deleteCommandsChannel(channel);
4}

Queries DeleteQueriesChannel Example:

Request:

Name	Type	Description	Default Value	Mandatory
channelName	String	The name of the channel to delete	None	Yes

Response:

Name	Type	Description
void	Promise	Doesn't return a value upon completion

1
2async  function  deleteQueriesChannel(channel: string) {
3    return  cqClient.deleteQueriesChannel(channel);
4}
5

List Channels

Command ListCommandsChannel Example:

Request:

Name	Type	Description	Default Value	Mandatory
searchString	String	The name of the channel to search for.	None	No

Response: CQChannel[] CQChannel interface attributes

Name	Type	Description
name	String	The name of the channel.
type	String	The type of the channel.
lastActivity	long	The timestamp of the last activity on the channel.
isActive	boolean	Indicates whether the channel is currently active.
incoming	CQStats	Statistics about incoming messages to the channel.
outgoing	CQStats	Statistics about outgoing messages from the channel.

1
2async  function  listCommandsChannels(search: string) {
3    const  channels = await  cqClient.listCommandsChannels(search);
4    console.log(channels);
5}
6

Queries ListQueriesChannel Example:

Request:

Name	Type	Description	Default Value	Mandatory
searchString	String	Channel name which you want to search	None	No

Response: List<CQChannel> CQChannel class attributes

Name	Type	Description
name	String	The name of the channel.
type	String	The type of the channel.
lastActivity	long	The timestamp of the last activity on the channel.
isActive	boolean	Indicates whether the channel is currently active.
incoming	CQStats	Statistics about incoming messages to the channel.
outgoing	CQStats	Statistics about outgoing messages from the channel.

1
2async  function  listQueriesChannels(search: string) {
3    const  channels = await  cqClient.listQueriesChannels(search);
4    console.log(channels);
5}
6

Send & Receive Command & Query Messages

Command SubscribeToCommandsChannel Example:

Request: CommandsSubscription Class Attributes

Name	Type	Description	Default Value	Mandatory
channel	String	The channel for the subscription.	None	Yes
group	String	The group associated with the subscription.	None	No
onReceiveCommandCallback	CommandsReceiveMessage	Callback function for receiving commands.	None	Yes

Response: None

Callback: CommandsReceiveMessage interface attributes

Name	Type	Description
commandReceived	CommandsReceiveMessage	The command message that was received.
clientId	String	The ID of the client that sent the command.
requestId	String	The ID of the request.
isExecuted	boolean	Indicates whether the command was executed.
timestamp	LocalDateTime	The timestamp of the response.
error	String	The error message if an error occurred.

1async function subscribeToCommands(channelName: string) {
2    //Subscribes to commands from the specified channel with a specific configuration.  
3    const commandSubscriptionRequest = new CommandsSubscriptionRequest(channelName, 'group1');
4
5    // Define the callback for receiving commandMessage  
6    commandSubscriptionRequest.onReceiveEventCallback = (commandMessage: CommandMessageReceived) => {
7        console.log('SubscriberA received commandMessage:', {
8            id: commandMessage.id,
9            fromClientId: commandMessage.fromClientId,
10            timestamp: commandMessage.timestamp,
11            channel: commandMessage.channel,
12            metadata: commandMessage.metadata,
13            body: commandMessage.body,
14            tags: commandMessage.tags,
15        });
16    };
17
18    // Define the callback for handling errors  
19    commandSubscriptionRequest.onErrorCallback = (error: string) => {
20        console.error('SubscriberA error:', error);
21    };
22
23    cqClient.subscribeToCommands(commandSubscriptionRequest)
24        .then(() => {
25            console.log('Command Subscription successful');
26        })
27        .catch((reason: any) => {
28            console.error('Command Subscription failed:', reason);
29        });
30}

Queries SubscribeToQueriesChannel Example:

Request: QueriesSubscriptionRequest Class Attributes

Name	Type	Description	Default Value	Mandatory
channel	String	The channel for the subscription.	None	Yes
group	String	The group associated with the subscription.	None	No
onReceiveQueriesCallback	QueriesReceiveMessage	Callback function for receiving queries.	None	Yes

Response: None

Callback: QueriesReceiveMessage interface attributes

Name	Type	Description
id	String	The ID of the request.
channel	String	Channel name from which the message was received.
metadata	String	Metadata of the message.
body	Uint8Array	The body of the response.
tags	Map<String, String>	Tags associated with the query message.
replyChannel	String	The reply channel for this message.

1async function subscribeToQueries(channelName: string) {
2
3    //Subscribes to queries from the specified channel with a specific configuration.  
4    const commandSubscriptionRequest = new CommandsSubscriptionRequest(channelName, 'group1');
5
6    // Define the callback for receiving queriesMessage  
7    commandSubscriptionRequest.onReceiveEventCallback = (commandMessage: CommandMessageReceived) => {
8        console.log('SubscriberA received event:', {
9            id: commandMessage.id,
10            fromClientId: commandMessage.fromClientId,
11            timestamp: commandMessage.timestamp,
12            channel: commandMessage.channel,
13            metadata: commandMessage.metadata,
14            body: commandMessage.body,
15            tags: commandMessage.tags,
16        });
17    };
18
19    // Define the callback for handling errors  
20    commandSubscriptionRequest.onErrorCallback = (error: string) => {
21        console.error('SubscriberA error:', error);
22    };
23
24    cqClient.subscribeToQueries(commandSubscriptionRequest)
25        .then(() => {
26            console.log('Queries Subscription successful');
27        })
28        .catch((reason: any) => {
29            console.error('Queries Subscription failed:', reason);
30        });
31}