Service Bus topics and subscriptions in Azure - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a Service Bus topic using Azure CLI.

Azure

az servicebus topic create --resource-group myResourceGroup --namespace-name myNamespace --name [1]

Drag options to blanks, or click blank then click option'

AmySubscription

BmyQueue

CmyTopic

DmyNamespace

Attempts:

3 left

💡 Hint

Common Mistakes

Using subscription or namespace names instead of the topic name.

Confusing topic with queue names.

The topic name is required to create a Service Bus topic. Here, myTopic is the correct name for the topic.

2fill in blank

medium

Complete the code to create a subscription for a Service Bus topic.

Azure

az servicebus topic subscription create --resource-group myResourceGroup --namespace-name myNamespace --topic-name myTopic --name [1]

Drag options to blanks, or click blank then click option'

AmySubscription

BmyQueue

CmyTopic

DmyNamespace

Attempts:

3 left

💡 Hint

Common Mistakes

Using topic or namespace names instead of subscription name.

Confusing subscription with queue or topic names.

The subscription name is required to create a subscription under a topic. Here, mySubscription is the correct subscription name.

3fill in blank

hard

Fix the error in the code to send a message to a Service Bus topic using Azure SDK for Python.

Azure

from azure.servicebus import ServiceBusClient, ServiceBusMessage

connection_str = 'Endpoint=sb://myNamespace.servicebus.windows.net/;SharedAccessKeyName=RootManageSharedAccessKey;SharedAccessKey=key'

with ServiceBusClient.from_connection_string(connection_str) as client:
    sender = client.get_topic_sender(topic_name=[1])
    message = ServiceBusMessage('Hello World')
    sender.send_messages(message)

Drag options to blanks, or click blank then click option'

A'mySubscription'

B'myTopic'

C'myQueue'

D'myNamespace'

Attempts:

3 left

💡 Hint

Common Mistakes

Passing subscription or queue names instead of topic name.

Not using quotes around the topic name string.

The get_topic_sender method requires the topic name as a string. Here, 'myTopic' is the correct topic name to send messages to.

4fill in blank

hard

Fill both blanks to create a subscription with a filter rule to only receive messages with label 'important'.

Azure

az servicebus topic subscription rule create --resource-group myResourceGroup --namespace-name myNamespace --topic-name myTopic --subscription-name mySubscription --name [1] --filter-sql-expression [2]

Drag options to blanks, or click blank then click option'

AImportantRule

B'sys.Label = ''important'''

C'sys.Label = important'

DDefaultRule

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect quotes in the filter expression.

Using default rule name when a custom name is expected.

The rule name can be any valid string, here ImportantRule is used. The filter expression must be a valid SQL expression as a string, so 'sys.Label = ''important''' is correct with proper quotes.

5fill in blank

hard

Fill all three blanks to receive messages from a subscription using Azure SDK for Python and complete the message processing.

Azure

from azure.servicebus import ServiceBusClient

connection_str = 'Endpoint=sb://myNamespace.servicebus.windows.net/;SharedAccessKeyName=RootManageSharedAccessKey;SharedAccessKey=key'

with ServiceBusClient.from_connection_string(connection_str) as client:
    receiver = client.get_subscription_receiver(topic_name=[1], subscription_name=[2])
    with receiver:
        messages = receiver.receive_messages(max_message_count=1, max_wait_time=5)
        for msg in messages:
            print(msg.body.decode())
            receiver.[3](msg)

Drag options to blanks, or click blank then click option'

A'myTopic'

B'mySubscription'

Ccomplete_message

Dabandon_message

Attempts:

3 left

💡 Hint

Common Mistakes

Using queue or namespace names instead of topic or subscription names.

Calling wrong method to complete message processing.

The get_subscription_receiver method requires the topic and subscription names as strings. After processing, complete_message is called to mark the message as processed.

Practice

1. What is the main purpose of an Azure Service Bus topic?

easy

A. To send messages to multiple receivers using subscriptions

B. To store data permanently like a database

C. To host web applications

D. To manage virtual machines

Solution

1. Step 1: Understand the role of a Service Bus topic

   A Service Bus topic acts as a message distributor that sends messages to multiple receivers.

2. Step 2: Compare other options

   Options B, C, and D describe unrelated Azure services or functions.

3. Final Answer:

   To send messages to multiple receivers using subscriptions -> Option A

4. Quick Check:

   Service Bus topic = message distribution [OK]

Hint: Topics distribute messages to many receivers via subscriptions [OK]

Common Mistakes:

• Confusing topics with queues
• Thinking topics store data permanently
• Mixing topics with compute services

2. Which of the following is the correct way to create a subscription under a topic using Azure CLI?

easy

A. az servicebus topic create --resource-group MyGroup --namespace-name MyNamespace --subscription-name MySubscription --name MyTopic

B. az servicebus subscription create --resource-group MyGroup --namespace-name MyNamespace --topic-name MyTopic --name MySubscription

C. az servicebus topic subscription create --resource-group MyGroup --namespace-name MyNamespace --topic-name MyTopic --name MySubscription

D. az servicebus create subscription --resource-group MyGroup --namespace-name MyNamespace --topic MyTopic --subscription MySubscription

Solution

1. Step 1: Identify the correct Azure CLI command structure

   The correct command to create a subscription under a topic is 'az servicebus subscription create' with required parameters.

2. Step 2: Check parameters and order

   az servicebus subscription create --resource-group MyGroup --namespace-name MyNamespace --topic-name MyTopic --name MySubscription uses the correct command and parameters: resource group, namespace, topic name, and subscription name.

3. Final Answer:

   az servicebus subscription create --resource-group MyGroup --namespace-name MyNamespace --topic-name MyTopic --name MySubscription -> Option B

4. Quick Check:

   Correct CLI syntax = az servicebus subscription create --resource-group MyGroup --namespace-name MyNamespace --topic-name MyTopic --name MySubscription [OK]

Hint: Use 'az servicebus subscription create' to add subscriptions [OK]

Common Mistakes:

• Using 'az servicebus topic create' for subscriptions
• Using invalid 'az servicebus topic subscription create'
• Incorrect command verbs or missing flags

3. Given the following code snippet, what will be the output?

from azure.servicebus import ServiceBusClient
connection_str = "Endpoint=sb://example.servicebus.windows.net/;SharedAccessKeyName=RootManageSharedAccessKey;SharedAccessKey=key"
topic_name = "mytopic"
subscription_name = "mysubscription"

with ServiceBusClient.from_connection_string(connection_str) as client:
    receiver = client.get_subscription_receiver(topic_name, subscription_name)
    with receiver:
        messages = receiver.receive_messages(max_message_count=2, max_wait_time=5)
        print(len(list(messages)))

medium

A. 2

B. The code will not compile

C. An exception is raised due to missing message processing

D. 0

Solution

1. Step 1: Understand message receiving behavior

   The code tries to receive up to 2 messages with a 5-second wait. If no messages are available, it returns an empty list.

2. Step 2: Analyze message processing

   Since no messages are explicitly sent before receiving, the list will be empty, so len(messages) is 0.

3. Final Answer:

   0 -> Option D

4. Quick Check:

   Receive without sent messages = 0 [OK]

Hint: Receiving messages without sending returns empty list [OK]

Common Mistakes:

• Assuming messages exist without sending
• Expecting exceptions for no messages
• Confusing receive_messages with peek_messages

4. You have created a subscription but messages are not being received. Which of the following is the most likely cause?

medium

A. The subscription filter is set to exclude all messages

B. The topic does not exist

C. The subscription name is too long

D. The Service Bus namespace is in a different region

Solution

1. Step 1: Check subscription filters

   If a subscription filter excludes all messages, no messages will be received even if the topic and subscription exist.

2. Step 2: Evaluate other options

   The topic does not exist would prevent subscription creation; The subscription name is too long would cause an error; The Service Bus namespace is in a different region does not block message reception.

3. Final Answer:

   The subscription filter is set to exclude all messages -> Option A

4. Quick Check:

   Filter excluding messages = no messages received [OK]

Hint: Check subscription filters if no messages arrive [OK]

Common Mistakes:

• Ignoring filters when troubleshooting
• Assuming region mismatch blocks messages
• Overlooking subscription existence

5. You want to ensure high availability and ordered message processing in your Service Bus topic subscriptions. Which configuration should you apply?

hard

A. Use multiple topics instead of subscriptions

B. Disable partitioning and use duplicate detection only

C. Enable partitioning on the topic and use sessions on subscriptions

D. Enable auto-delete on subscriptions after 1 hour

Solution

1. Step 1: Understand partitioning and sessions

   Partitioning improves availability by spreading messages across nodes. Sessions enable ordered processing by grouping related messages.

2. Step 2: Evaluate other options

   Disabling partitioning reduces availability; multiple topics don't guarantee order; auto-delete removes subscriptions prematurely.

3. Final Answer:

   Enable partitioning on the topic and use sessions on subscriptions -> Option C

4. Quick Check:

   Partitioning + sessions = high availability + order [OK]

Hint: Use partitioning for availability and sessions for order [OK]

Common Mistakes:

• Confusing duplicate detection with ordering
• Thinking multiple topics replace subscriptions
• Setting auto-delete too aggressively