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readme.md

Java Samples for Azure Service Bus

This is the official set of Java samples for Azure Service Bus. The samples demonstrate basics such as sending and receiving operations in the "quick starts", and more advanced scenarios in the feature-oriented samples. All samples are simple command line applications with minimal extra ceremony.

The Java samples are split into two distinct sets. One set is built with the native Azure Service Bus SDK (azure-servicebus), the other set is built with the Apache Qpid JMS (Java Message Service) AMQP client.

Azure Service Bus API

The native Azure Service Bus SDK is fully supported by Microsoft (says: you can file service requests through the Azure portal to get immediate help) and it provides unfiltered and easy access to all Service Bus features.

Getting Started

  • Getting Started with Queues - The QueuesGettingStarted sample illustrates the basic send and receive gestures for interacting with a previously provisioned Service Bus Queue. Most other samples in this repository are derivatives of this basic sample.
  • Getting Started with Topics - The TopicsGettingStarted sample illustrates the basic gestures for sending messages into Topics and receiving them from Subscriptions.

Message Handling

  • Receive Loop - ReceiveLoop shows how to use an explicit receive loop with a queue instead of the recommended, callback-based OnMessage(Async) API used in the "getting started" sample.
  • Message Prefetching - The Prefetch sample shows the difference between having "prefetch" turned on or off for the receiver. Prefetch is a background receive operation that acquires messages into a buffer before the application itself calls Receive and therefore optimizes and often accelerates the message flow.
  • Duplicate Detection - The sample for DuplicateDetection illustrates how Service Bus suppresses the secound and all further messages sent with an identical MessageId when sent during a defined duplicate detection time window when the RequiresDuplicateDetection flag is turned on for a Queue or Topic.
  • Message Browsing - MessageBrowse shows how to enumerate all messages residing in a Queue or Subscription without receiving or locking them. This method also allows finding deferred and scheduled messages.
  • Auto Forward - AutoForward illustrates how and why to use automatic forwarding between entities in Service Bus.

Topics and Subscriptions

  • Topic Filters - The TopicFilters sample illustrates how to create and configure filters on Topic Subscriptions.

Partitioned Entities

  • Partitioned Queues - PartitionedQueues are largely identical in handling to "regular" Queues (and are the default option when creating new Queues via teh Azure Portal), but are more resilient against slowdowns in the backend storage system. This sample illustrates some special considerations to keep in mind for partitioned queues.

Error and Transaction Handling

  • Deadletter Queues - The DeadletterQueue sample shows how to use the deadletter queue for setting aside messages that cannot be processed, and how to receive from the deadletter queue to inspect, repair, and resubmit such messages.
  • Time To Live - The TimeToLive example shows the basic functionality of the TimeToLive option for messages as well as handling of the deadletter queue where messages can optionally be stored by the system as they expire.

Networking

  • Proxy Use - The QueuesWithProxy sample shows how to use the ProxySelector class to connect to Service Bus via a proxy as well as how to configure basic authentication with a proxy.

Apache Qpid JMS

The Qpid JMS client is a third party open source component managed by the Apache Qpid project. It is compatible with Service Bus via its AMQP 1.0 proptocol support and can be used as an "lowest common denominator" alternative when the JMS API has been chosen for an existing application that is being moved onto Azure Service Bus. Mind that JMS 2.0 gestures that change the namespace topology, like creating durable subscriptions or temporary queues, are not supported with Azure Service Bus via JMS at this time.

Getting Started

  • Getting Started with Queues - The JmsQueueQuickstart sample illustrates the basic send and receive gestures for interacting with a previously provisioned Service Bus Queue. Most other samples in this repository are derivatives of this basic sample.
  • Getting Started with Topics - The JmsTopicQuickstart sample illustrates the basic gestures for sending messages into Topics and receiving them from Subscriptions.

Setup

First, clone this git repository locally.

The samples require creating an Azure subscription if you don't have one. You also need
a Service Bus namespace, and a simple basic topology of a few exemplary queues, topics, and subscriptions. To set those up, with an Azure Service Bus "Standard" namespace, just click the button below and follow the further instructions on the Azure Portal:

The free Azure subscription offer includes a service credit that will take you very far with all your experiments. The prorated monthly base fee for Service Bus Standard includes a generous allocation of message operations, and you can even run a large Service Bus Premium namespace with 4 Messaging Units for several days.

You can also deploy the resource manager template from the command line:

Setup using the Azure CLI

With the Azure CLI, you first create a named resource group in an Azure region, selected by the --location argument, and then deploy the template into the resource group. The template file with the Service Bus topology for these samples is located in the scripts subdirectory. The namespace name argument becomes the leftmost portion of the fully qualifed domain name of your Service Bus namespace (e.g. {name}.servicebus.windows.net or {name}.servicebus.cloudapi.de) and must therefore be globally unique. There will be error feedback if you pick a name that already exists.

az group create --name {rg-name} --location "Central US"
az group deployment create --name {deployment-name} \
                           --resource-group {rg-name} \
                           --template-file scripts/azuredeploy.json \
                           --parameters serviceBusNamespaceName={service-bus-namespace-name}

Setup using PowerShell

The PowerShell setup is functionally equivalent. You first create a resource group and then deploy the resource manager template:

New-AzureRmResourceGroup -Name {rg-name} -Location "Central US"
New-AzureRmResourceGroupDeployment \
      -Name {deployment-name} \
      -ResourceGroupName {rg-name}
      -TemplateFile scripts/azuredeploy.json \
      -serviceBusNamespaceName {service-bus-namespace-name} 

Building and exploring the samples

All samples are individual Maven projects. JDK 1.8 or higher is required. There is a top-level Maven project umbrella that allows to build all samples in one go, but you can also build the projects singly. Each project yields a console application packaged into a JAR along with all required dependencies, so that you don't have to fiddle around with the Java classpath.

Exploring and running the samples

The samples are preconfigured for use with Visual Studio Code and the Red Hat Java language support and Java debugging extensions. You can either open the Java sample root directory or the individual sample directories.

All samples have similar command line usage and accept a Service Bus connection string via option -c {connection-string}, and the names of the Service Bus entities they interact with, e.g. -q {queue-name}.

To make running the samples straightforward, there are scripts for Bash (Azure CLI) and Powershell (Azure PS) in scripts that will obtain the namespace connection string from your current Azure subscription, assume the entity names configured in the deployed templates, and export those into environment variables, eliminating the need to pass those arguments on the command line.

The Bash script is scripts/setupenv.sh, the Powershell equivalent is scripts/setupenv.ps1. Either needs to be called with the name of the Resource Group and the Service Bus namespace name as ordinal arguments. The Bash version runs a (re-)deployment of the template to obtain the required keys. For parsing the returned JSON file, the Bash script relies on the ./jq package that can be installed with sudo apt install jq.

Run the Powershell script from the scripts directory with

./setupenv.ps1 {rg-name} {service-bus-namespace-name} 

Run the Bash script with

eval `./sampleenv.sh {rg-name} {service-bus-namespace-name}`

The scripts initialize the following environment variables:

  • SB_SAMPLES_CONNECTIONSTRING - Service Bus connection string
  • SB_SAMPLES_QUEUE - Default queue name
  • SB_SAMPLES_TOPIC - Default topic name
  • SB_SAMPLES_SUBSCRIPTION - Default subscription name

The samples build into the target folder of the respective sample subdirectory and can be run from there, using

java -jar {name]-jar-with-dependencies.jar 

Building all samples

To build all samples, run a Maven build from the samples root directory:

mvn -B package
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