ballerinax/asb Ballerina library

Overview

The Azure Service Bus is a fully managed enterprise message broker with message queues and publish-subscribe topics. It provides the capability to send and receive messages from Service Bus queues, topics, and subscriptions. The Azure Service Bus handles messages that include data representing any kind of information, including structured data encoded with common formats such as the following ones: JSON, XML, and Plain Text.

The Ballerina connector for Azure Service Bus allows you to connect to an Azure Service Bus via the Ballerina language.

This connector supports the following operations:

• Manage (Get/Create/Update/Delete/list) a queue, topic, subscription or rule.
• Send messages to a queue, topic, or subscription.
• Receive messages from a queue, topic, or subscription.

The Ballerina Azure Service Bus module utilizes Microsoft's Azure Service Bus JAVA SDK 7.13.1.

Setup guide

Before using this connector in your Ballerina application, complete the following:

Create a namespace in the Azure portal

To begin using Service Bus messaging in Azure, you must first create a namespace with a name that is unique across Azure. A namespace provides a scoping container for Service Bus resources within your application.

To create a namespace:

Step 1: Sign in to the Azure portal

If you don't have an Azure subscription, sign up for a free Azure account.

Step 2: Go to the Create Resource Service Bus menu

In the left navigation pane of the portal, select All services, select Integration from the list of categories, hover the mouse over Service Bus, and then select Create on the Service Bus tile.

Step 3: In the Basics tag of the Create namespace page, follow these steps:

1. For Subscription, choose an Azure subscription in which to create the namespace.

2. For Resource group, choose an existing resource group in which the namespace will live, or create a new one.

3. Enter a name for the namespace. The namespace name should adhere to the following naming conventions:

• The name must be unique across Azure. The system immediately checks to see if the name is available.
• The name length is at least 6 and at most 50 characters.
• The name can contain only letters, numbers, and hyphens “-“.
• The name must start with a letter and end with a letter or number.
• The name doesn't end with “-sb“ or “-mgmt“.

4. For Location, choose the region in which your namespace should be hosted.

5. For Pricing tier, select the pricing tier (Basic, Standard, or Premium) for the namespace. For this quickstart, select Standard.

Notice: If you want to use topics and subscriptions, choose either Standard or Premium. Topics/subscriptions aren't supported in the Basic pricing tier. If you selected the Premium pricing tier, specify the number of messaging units. The premium tier provides resource isolation at the CPU and memory level so that each workload runs in isolation. This resource container is called a messaging unit. A premium namespace has at least one messaging unit. You can select 1, 2, 4, 8, or 16 messaging units for each Service Bus Premium namespace. For more information, see Service Bus Premium Messaging.`

6. Select Review + create at the bottom of the page.

7. On the Review + create page, review settings, and select Create.

Obtain tokens for authentication

To send and receive messages from a Service Bus queue or topic, clients must use a token that is signed by a shared access key, which is part of a shared access policy. A shared access policy defines a set of permissions that can be assigned to one or more Service Bus entities (queues, topics, event hubs, or relays). A shared access policy can be assigned to more than one entity, and a single entity can have more than one shared access policy assigned to it.

To obtain a token following steps should be followed:

1. In the left navigation pane of the portal, select All services, select Integration from the list of categories, hover the mouse over Service Bus, and then select your namespace.

2. In the left navigation pane of the namespace page, select Shared access policies.

3. Click on the RootManageSharedAccessKey policy.

4. Copy the Primary Connection String value and save it in a secure location. This is the connection string that you use to authenticate with the Service Bus service.

Quickstart

To use the ASB connector in your Ballerina application, modify the .bal file as follows:

Step 1: Import connector

Import the ballerinax/asb module into the Ballerina project.

import ballerinax/asb;

Step 2: Create a new connector instance

Initialize an Admin Client

This can be done by providing a connection string.

configurable string connectionString = ?;
asb:AdminClient admin = check new (connectionString);

Initialize a Message Sender client

This can be done by providing a connection string with a queue or topic name.

configurable string connectionString = ?;

ASBServiceSenderConfig senderConfig = {
    connectionString: connectionString,
    entityType: QUEUE,
    topicOrQueueName: "myQueue"
};
asb:MessageSender sender = check new (senderConfig);

Initialize a Message Receiver client

This can be done by providing a connection string with a queue name, topic name, or subscription path.

Here, the Receive mode is optional. (Default: PEEKLOCK)

configurable string connectionString = ?;

ASBServiceReceiverConfig receiverConfig = {
    connectionString: connectionString,
    entityConfig: {
        queueName: "myQueue"
    },
    receiveMode: PEEK_LOCK
};
asb:MessageReceiver receiver = check new (receiverConfig);

Initialize a message listener

This can be done by providing a connection string with a queue name, topic name, or subscription path.

Here, the Receive mode is optional. (Default: PEEKLOCK)

configurable string connectionString = ?;

listener asb:Listener asbListener = check new (
    connectionString = connectionString,
    entityConfig = {
        queueName: "myQueue"
    }
);

Step 3: Invoke connector operation

Now you can use the remote operations available within the connector,

Create a queue in the Azure Service Bus

public function main() returns error? {
    asb:AdminClient admin = check new (adminConfig);

    check admin->createQueue("myQueue");

    check admin->close();
}

Send a message to the Azure Service Bus

public function main() returns error? {
    asb:MessageSender queueSender = check new (senderConfig);

    string stringContent = "This is My Message Body"; 
    byte[] byteContent = stringContent.toBytes();
    int timeToLive = 60; // In seconds

    asb:ApplicationProperties applicationProperties = {
        properties: {a: "propertyValue1", b: "propertyValue2"}
    };

    asb:Message message = {
        body: byteContent,
        contentType: asb:TEXT,
        timeToLive: timeToLive,
        applicationProperties: applicationProperties
    };

    check queueSender->send(message);

    check queueSender->close();
}

Receive a message from the Azure Service Bus

public function main() returns error? {
    asb:MessageReceiver queueReceiver = check new (receiverConfig);

    int serverWaitTime = 60; // In seconds

    asb:Message|asb:Error? messageReceived = queueReceiver->receive(serverWaitTime);

    if (messageReceived is asb:Message) {
        log:printInfo("Reading Received Message : " + messageReceived.toString());
    } else if (messageReceived is ()) {
        log:printError("No message in the queue.");
    } else {
        log:printError("Receiving message via Asb receiver connection failed.");
    }

    check queueReceiver->close();
}

Receive messages from Azure service bus using asb:Service

service asb:Service on asbListener {

    isolated remote function onMessage(asb:Message message) returns error? {
        log:printInfo("Reading Received Message : " + message.toString());
    }

    isolated remote function onError(asb:MessageRetrievalError 'error) returns error? {
        log:printError("Error occurred while receiving messages from ASB", 'error);
    }
}

Step 4: Run the Ballerina application

bal run

Examples

There are two sets of examples demonstrating the use of the Ballerina Azure Service Bus (ASB) Connector.

• Management Related Examples: These examples cover operations related to managing the Service Bus, such as managing queues, topics, subscriptions, and rules.

• Message Sending and Receiving Related Examples: This set includes examples for sending to and receiving messages from queues, topics, and subscriptions in the Service Bus.