How to use Spring Data API for Apache Cassandra with Azure Cosmos DB for Apache Cassandra

Article
10/12/2022

APPLIES TO: Cassandra

This article demonstrates creating a sample application that uses Spring Data to store and retrieve information using the Azure Cosmos DB for Apache Cassandra.

Prerequisites

The following prerequisites are required in order to complete the steps in this article:

An Azure subscription; if you don't already have an Azure subscription, you can activate your MSDN subscriber benefits or sign up for a free Azure account.
A supported Java Development Kit (JDK). For more information about the JDKs available for use when developing on Azure, see Java support on Azure and Azure Stack.
Apache Maven, version 3.0 or later.
Curl or similar HTTP utility to test functionality.
A Git client.

Note

The samples mentioned below implement custom extensions for a better experience when using Azure Cosmos DB for Apache Cassandra. They include custom retry and load balancing policies, as well as implementing recommended connection settings. For a more extensive exploration of how the custom policies are used, see Java samples for version 3 and version 4.

Create an Azure Cosmos DB for Apache Cassandra account

From the Azure portal menu or the Home page, select Create a resource.
On the New page, search for and select Azure Cosmos DB.
On the Azure Cosmos DB page, select Create.
On the API page, select Create under the Cassandra section.

The API determines the type of account to create. Azure Cosmos DB provides five APIs: NoSQL for document databases, Gremlin for graph databases, MongoDB for document databases, Azure Table, and Cassandra. You must create a separate account for each API.

Select Cassandra, because in this quickstart you are creating a table that works with the API for Cassandra.

Learn more about the API for Cassandra.

In the Create Azure Cosmos DB Account page, enter the basic settings for the new Azure Cosmos DB account.

Setting	Value	Description
Subscription	Your subscription	Select the Azure subscription that you want to use for this Azure Cosmos DB account.
Resource Group	Create new Then enter the same name as Account Name	Select Create new. Then enter a new resource group name for your account. For simplicity, use the same name as your Azure Cosmos DB account name.
Account Name	Enter a unique name	Enter a unique name to identify your Azure Cosmos DB account. Your account URI will be cassandra.cosmos.azure.com appended to your unique account name. The account name can use only lowercase letters, numbers, and hyphens (-), and must be between 3 and 31 characters long.
Location	The region closest to your users	Select a geographic location to host your Azure Cosmos DB account. Use the location that is closest to your users to give them the fastest access to the data.
Capacity mode	Provisioned throughput or Serverless	Select Provisioned throughput to create an account in provisioned throughput mode. Select Serverless to create an account in serverless mode.
Apply Azure Cosmos DB free tier discount	Apply or Do not apply	With Azure Cosmos DB free tier, you will get the first 1000 RU/s and 25 GB of storage for free in an account. Learn more about free tier.
Limit total account throughput	Select to limit throughput of the account	This is useful if you want to limit the total throughput of the account to a specific value.

Note

You can have up to one free tier Azure Cosmos DB account per Azure subscription and must opt-in when creating the account. If you do not see the option to apply the free tier discount, this means another account in the subscription has already been enabled with free tier.

The new account page for Azure Cosmos DB for Apache Cassandra

In the Global Distribution tab, configure the following details. You can leave the default values for the purpose of this quickstart:

Setting	Value	Description
Geo-Redundancy	Disable	Enable or disable global distribution on your account by pairing your region with a pair region. You can add more regions to your account later.
Multi-region Writes	Disable	Multi-region writes capability allows you to take advantage of the provisioned throughput for your databases and containers across the globe.
Availability Zones	Disable	Availability Zones are isolated locations within an Azure region. Each zone is made up of one or more datacenters equipped with independent power, cooling, and networking.

Note

The following options are not available if you select Serverless as the Capacity mode:

Apply Free Tier Discount
Geo-redundancy
Multi-region Writes

Optionally you can configure additional details in the following tabs:
- Networking - Configure access from a virtual network.
- Backup Policy - Configure either periodic or continuous backup policy.
- Encryption - Use either service-managed key or a customer-managed key.
- Tags - Tags are name/value pairs that enable you to categorize resources and view consolidated billing by applying the same tag to multiple resources and resource groups.
Select Review + create.
Review the account settings, and then select Create. It takes a few minutes to create the account. Wait for the portal page to display Your deployment is complete.
Select Go to resource to go to the Azure Cosmos DB account page.

Configure the sample application

The following procedure configures the test application.

Open a command shell and clone either of the following examples:

For Java version 3 driver and corresponding Spring version:
```
git clone https://github.com/Azure-Samples/spring-data-cassandra-on-azure-extension-v3.git
```
For Java version 4 driver and corresponding Spring version:
```
git clone https://github.com/Azure-Samples/spring-data-cassandra-on-azure-extension-v4.git
```
Note

Although the usage described below is identical for both Java version 3 and version 4 samples above, the way in which they have been implemented in order to include custom retry and load balancing policies is different. We recommend reviewing the code to understand how to implement custom policies if you are making changes to an existing Spring Java application.
Locate the application.properties file in the resources directory of the sample project, or create the file if it does not already exist.

Open the application.properties file in a text editor, and add or configure the following lines in the file, and replace the sample values with the appropriate values from earlier:

spring.data.cassandra.contact-points=<Account Name>.cassandra.cosmos.azure.com
spring.data.cassandra.port=10350
spring.data.cassandra.username=<Account Name>
spring.data.cassandra.password=********

Where:

Parameter	Description
`spring.data.cassandra.contact-points`	Specifies the Contact Point from earlier in this article.
`spring.data.cassandra.port`	Specifies the Port from earlier in this article.
`spring.data.cassandra.username`	Specifies your Username from earlier in this article.
`spring.data.cassandra.password`	Specifies your Primary Password from earlier in this article.

Save and close the application.properties file.

Package and test the sample application

Browse to the directory that contains the .pom file to build and test the application.

Build the sample application with Maven; for example:
```
mvn clean package
```

Start the sample application; for example:

java -jar target/spring-data-cassandra-on-azure-0.1.0-SNAPSHOT.jar

Create new records using curl from a command prompt like the following examples:

curl -s -d "{\"name\":\"dog\",\"species\":\"canine\"}" -H "Content-Type: application/json" -X POST http://localhost:8080/pets

curl -s -d "{\"name\":\"cat\",\"species\":\"feline\"}" -H "Content-Type: application/json" -X POST http://localhost:8080/pets

Your application should return values like the following:

Added Pet{id=60fa8cb0-0423-11e9-9a70-39311962166b, name='dog', species='canine'}.

Added Pet{id=72c1c9e0-0423-11e9-9a70-39311962166b, name='cat', species='feline'}.

Retrieve all of the existing records using curl from a command prompt like the following examples:

curl -s http://localhost:8080/pets

Your application should return values like the following:

[{"id":"60fa8cb0-0423-11e9-9a70-39311962166b","name":"dog","species":"canine"},{"id":"72c1c9e0-0423-11e9-9a70-39311962166b","name":"cat","species":"feline"}]

Clean up resources

When you're done with your app and Azure Cosmos DB account, you can delete the Azure resources you created so you don't incur more charges. To delete the resources:

In the Azure portal Search bar, search for and select Resource groups.
From the list, select the resource group you created for this quickstart.
On the resource group Overview page, select Delete resource group.
In the next window, enter the name of the resource group to delete, and then select Delete.