Create a Data Access Object for Cosmos DB Data using JDBI

JDBI is a SQL convenience library for Java that exposes two different style APIs, a fluent style and a SQL object style. The CData JDBC Driver for Cosmos DB integrates connectivity to live Cosmos DB data in Java applications. By pairing these technologies, you gain simple, programmatic access to Cosmos DB data. This article explains how to build a basic Data Access Object (DAO) and the accompanying code to read and write Cosmos DB data.

Create a DAO for the Cosmos DB Customers Entity

The interface below declares the desired behavior for the SQL object to create a single method for each SQL statement to be implemented.

public interface MyCustomersDAO {
 //insert new data into Cosmos DB
 @SqlUpdate("INSERT INTO Customers (Name, CompanyName) values (:name, :companyName)")
 void insert(@Bind("name") String name, @Bind("companyName") String companyName);

 //request specific data from Cosmos DB (String type is used for simplicity)
 @SqlQuery("SELECT CompanyName FROM Customers WHERE Name = :name")
 String findCompanyNameByName(@Bind("name") String name);

 /*
 * close with no args is used to close the connection
 */
 void close();
}

Open a Connection to Cosmos DB

Collect the necessary connection properties and construct the appropriate JDBC URL for connecting to Cosmos DB.

To obtain the connection string needed to connect to a Cosmos DB account using the SQL API, log in to the Azure Portal, select Azure Cosmos DB, and select your account. In the Settings section, click Connection String and set the following values:

• AccountEndpoint: The Cosmos DB account URL from the Keys blade of the Cosmos DB account
• AccountKey: In the Azure portal, navigate to the Cosmos DB service and select your Azure Cosmos DB account. From the resource menu, go to the Keys page. Find the PRIMARY KEY value and set AccountKey to this value.

Built-in Connection String Designer

For assistance in constructing the JDBC URL, use the connection string designer built into the Cosmos DB JDBC Driver. Either double-click the JAR file or execute the jar file from the command-line.

java -jar cdata.jdbc.cosmosdb.jar

Fill in the connection properties and copy the connection string to the clipboard.

A connection string for Cosmos DB will typically look like the following:

jdbc:cosmosdb:AccountEndpoint=myAccountEndpoint;AccountKey=myAccountKey;

Use the configured JDBC URL to obtain an instance of the DAO interface. The particular method shown below will open a handle bound to the instance, so the instance needs to be closed explicitly to release the handle and the bound JDBC connection.

DBI dbi = new DBI("jdbc:cosmosdb:AccountEndpoint=myAccountEndpoint;AccountKey=myAccountKey;");
MyCustomersDAO dao = dbi.open(MyCustomersDAO.class);

//do stuff with the DAO

dao.close();

Read Cosmos DB Data

With the connection open to Cosmos DB, simply call the previously defined method to retrieve data from the Customers entity in Cosmos DB.

//disply the result of our 'find' method
String companyName = dao.findCompanyNameByName("Morris Park Bake Shop");
System.out.println(companyName);

Write Cosmos DB Data

It is also simple to write data to Cosmos DB, using the previously defined method.

//add a new entry to the Customers entity
dao.insert(newName, newCompanyName);

Since the JDBI library is able to work with JDBC connections, you can easily produce a SQL Object API for Cosmos DB by integrating with the CData JDBC Driver for Cosmos DB. Download a free trial and work with live Cosmos DB data in custom Java applications today.