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Quickstart: Cassandra API with Java - Azure Cosmos DB | Microsoft Docs
This quickstart shows how to use the Azure Cosmos DB Cassandra API to create a profile application with the Azure portal and Java
cosmos-db
mimig1
jhubbard
ef611081-0195-4ad8-9b54-b313588e5754
cosmos-db
quick start connect, mvc
data-services
na
na
article
11/15/2017
mimig

Quickstart: Build a Cassandra app with Java and Azure Cosmos DB

This quickstart shows how to use Java and the Azure Cosmos DB Cassandra API to build a profile app by cloning an example from GitHub. This quickstart also walks you through the creation of an Azure Cosmos DB account by using the web-based Azure portal.

Azure Cosmos DB is Microsoft's globally distributed multi-model database service. You can quickly create and query document, table, key-value, and graph databases, all of which benefit from the global distribution and horizontal scale capabilities at the core of Azure Cosmos DB.

Prerequisites

[!INCLUDE quickstarts-free-trial-note] Alternatively, you can Try Azure Cosmos DB for free without an Azure subscription, free of charge and commitments.

Access to the Azure Cosmos DB Cassandra API preview program. If you haven't applied for access yet, sign up now.

In addition:

  • Java Development Kit (JDK) 1.7+
    • On Ubuntu, run apt-get install default-jdk to install the JDK.
    • Be sure to set the JAVA_HOME environment variable to point to the folder where the JDK is installed.
  • Download and install a Maven binary archive
    • On Ubuntu, you can run apt-get install maven to install Maven.
  • Git
    • On Ubuntu, you can run sudo apt-get install git to install Git.

Create a database account

Before you can create a document database, you need to create a Cassandra account with Azure Cosmos DB.

[!INCLUDE cosmos-db-create-dbaccount-cassandra]

Clone the sample application

Now let's switch to working with code. Let's clone a Cassandra app from GitHub, set the connection string, and run it. You'll see how easy it is to work with data programmatically.

  1. Open a git terminal window, such as git bash, and use the cd command to change to a folder to install the sample app.

    cd "C:\git-samples"

  2. Run the following command to clone the sample repository. This command creates a copy of the sample app on your computer.

    git clone https://github.com/Azure-Samples/azure-cosmos-db-cassandra-java-getting-started.git

Review the code

This step is optional. If you're interested in learning how the database resources are created in the code, you can review the following snippets. Otherwise, you can skip ahead to Update your connection string. These snippets are all taken from the src/main/java/com/azure/cosmosdb/cassandra/util/CassandraUtils.java.

  • Cassandra host, port, user name, password, and SSL options are set. The connection string information comes from the connection string page in the Azure portal.

    cluster = Cluster.builder().addContactPoint(cassandraHost).withPort(cassandraPort).withCredentials(cassandraUsername, cassandraPassword).withSSL(sslOptions).build();

  • The cluster connects to the Azure Cosmos DB Cassandra API and returns a session to access.

    return cluster.connect();

The following snippets are from the src/main/java/com/azure/cosmosdb/cassandra/repository/UserRepository.java file.

  • Create a new keyspace.

    public void createKeyspace() {
    final String query = "CREATE KEYSPACE IF NOT EXISTS uprofile WITH replication = {'class': 'SimpleStrategy', 'replication_factor': '3' } ";
    session.execute(query);
    LOGGER.info("Created keyspace 'uprofile'");
}

  • Create a new table.

    public void createTable() {
     final String query = "CREATE TABLE IF NOT EXISTS uprofile.user (user_id int PRIMARY KEY, user_name text, user_bcity text)";
     session.execute(query);
     LOGGER.info("Created table 'user'");
}

  • Insert user entities using a prepared statement object.

    public PreparedStatement prepareInsertStatement() {
    final String insertStatement = "INSERT INTO  uprofile.user (user_id, user_name , user_bcity) VALUES (?,?,?)";
    return session.prepare(insertStatement);
}

public void insertUser(PreparedStatement statement, int id, String name, String city) {
    BoundStatement boundStatement = new BoundStatement(statement);
    session.execute(boundStatement.bind(id, name, city));
}

  • Query to get all user information.

    public void selectAllUsers() {
    final String query = "SELECT * FROM uprofile.user";
    List<Row> rows = session.execute(query).all();

    for (Row row : rows) {
        LOGGER.info("Obtained row: {} | {} | {} ", row.getInt("user_id"), row.getString("user_name"), row.getString("user_bcity"));
    }
}

  • Query to get a single user's information.

    public void selectUser(int id) {
    final String query = "SELECT * FROM uprofile.user where user_id = 3";
    Row row = session.execute(query).one();

    LOGGER.info("Obtained row: {} | {} | {} ", row.getInt("user_id"), row.getString("user_name"), row.getString("user_bcity"));
}

Update your connection string

Now go back to the Azure portal to get your connection string information and copy it into the app. This enables your app to communicate with your hosted database.

  1. In the Azure portal, click Connection String.

    View and copy a username from the Azure portal, Connection String page

  2. Use the Copy button button on the right side of the screen to copy the CONTACT POINT value.

  3. Open the config.properties file from C:\git-samples\azure-cosmosdb-cassandra-java-getting-started\java-examples\src\main\resources folder.

  4. Paste the CONTACT POINT value from the portal over <Cassandra endpoint host> on line 2.

    Line 2 of config.properties should now look similar to

    cassandra_host=cosmos-db-quickstarts.documents.azure.com

  5. Go back to portal and copy the USERNAME value. Past the USERNAME value from the portal over <cassandra endpoint username> on line 4.

    Line 4 of config.properties should now look similar to

    cassandra_username=cosmos-db-quickstart

  6. Go back to portal and copy the PASSWORD value. Paste the PASSWORD value from the portal over <cassandra endpoint password> on line 5.

    Line 5 of config.properties should now look similar to

    cassandra_password=2Ggkr662ifxz2Mg...==

  7. On line 6, if you want to use a specific SSL certificate, then replace <SSL key store file location> with the location of the SSL certificate. If a value is not provided, the JDK certificate installed at <JAVA_HOME>/jre/lib/security/cacerts is used.

  8. If you changed line 6 to use a specific SSL certificate, update line 7 to use the password for that certificate.

  9. Save the config.properties file.

Run the app

  1. In the git terminal window, cd to the azure-cosmosdb-cassandra-java-getting-started\java-examples folder.

    cd "C:\git-samples\azure-cosmosdb-cassandra-java-getting-started\java-examples"

  2. In the git terminal window, use the following command to generate the cosmosdb-cassandra-examples.jar file.

    mvn clean install

  3. In the git terminal window, run the following command to start the Java application.

    java -cp target/cosmosdb-cassandra-examples.jar com.azure.cosmosdb.cassandra.examples.UserProfile

    The terminal window displays notifications that the keyspace and table are created. It then selects and returns all users in the table and displays the output, and then selects a row by id and displays the value.

    Press CTRL + C to stop exection of the program and close the console window.

    You can now open Data Explorer in the Azure portal to see query, modify, and work with this new data.

    View the data in Data Explorer

Review SLAs in the Azure portal

[!INCLUDE cosmosdb-tutorial-review-slas]

Clean up resources

[!INCLUDE cosmosdb-delete-resource-group]

Next steps

In this quickstart, you've learned how to create an Azure Cosmos DB account, Cassandra database, and collection using the Data Explorer, and run an app to do the same thing programmatically. You can now import additional data into your Azure Cosmos DB collection.

[!div class="nextstepaction"] Import Cassandra data into Azure Cosmos DB