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Connect to REST in a Spring Boot Application using CData JDBC REST Driver
Spring Boot is a framework that makes engineering Java web applications easier. It offers the ability to create standalone applications with minimal configuration. When paired with the CData JDBC driver for REST, Spring Boot can work with live REST data. This article shows how to configure data sources and retrieve data in your Java Spring Boot Application, using the CData JDBC Driver for REST.
With built-in optimized data processing, the CData JDBC Driver offers unmatched performance for interacting with live REST data. When you issue complex SQL queries to REST, the driver pushes supported SQL operations, like filters and aggregations, directly to REST and utilizes the embedded SQL engine to process unsupported operations client-side (often SQL functions and JOIN operations). Its built-in dynamic metadata querying allows you to work with and analyze REST data using native data types.
Creating the Spring Boot Project in Java
In an IDE (in this tutorial, we use IntelliJ), choose a Maven project: In the generated project, go to the pom.xml file, and add the required dependencies for Spring Boot:
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.7.2</version>
<relativePath/>
</parent>
<groupId>com.example</groupId>
<artifactId>demo</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>demo</name>
<description>Demo project for Spring Boot</description>
<properties>
<java.version>1.8</java.version>
</properties>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-install-plugin</artifactId>
<version>2.5.1</version>
<executions>
<execution>
<id>id.install-file</id>
<phase>clean</phase>
<goals>
<goal>install-file</goal>
</goals>
<configuration>
<file>C:\Program Files\CData[product_name] ####\lib\cdata.jdbc.rest.jar</file>
<groupId>org.cdata.connectors</groupId>
<artifactId>cdata-rest-connector</artifactId>
<version>23</version>
<packaging>jar</packaging>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-jdbc</artifactId>
<version>2.7.0</version>
</dependency>
<dependency>
<groupId>org.cdata.connectors</groupId>
<artifactId>cdata-rest-connector</artifactId>
<version>23</version>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<distributionManagement>
<repository>
<uniqueVersion>false</uniqueVersion>
<id>test</id>
<name>My Repository</name>
<url>scp://repo/maven2</url>
<layout>default</layout>
</repository>
</distributionManagement>
</project>
Note: The year (####) and the version number (as seen in the provided XML script) should be adjusted according to the current version of the CData JDBC driver being utilized.
Project Structure
In the java directory, create a new package. Usually the name of the package is the name of the groupId (com.example) followed by the artifactId (.MDS).
Mark the "java" directory as the "Sources Root" (denoted by a blue color). To do this, right-click the java directory and choose Mark Directory as -> Sources Root (As shown below). Additionally, mark the "resources" directory as the "Resources Root."
Store Database Connection Properties
Create an "application.properties" file to store the database connection properties. To do this, right-click on the "resources" folder, opt for New -> File, input the file name as "application.properties," and press Enter.
In the application.properties file, we set the configuration properties for the REST JDBC Driver, using the Class name and JDBC URL:
spring.datasource.driver=cdata.jdbc.rest.RESTDriver
spring.datasource.url=jdbc:rest:DataModel=Relational;URI=C:/people.xml;Format=XML;
Built-in Connection String Designer
For assistance in constructing the JDBC URL, use the connection string designer built into the REST JDBC Driver. Either double-click the JAR file or execute the jar file from the command-line.
java -jar cdata.jdbc.rest.jar
See the Getting Started chapter in the data provider documentation to authenticate to your data source: The data provider models REST APIs as bidirectional database tables and XML/JSON files as read-only views (local files, files stored on popular cloud services, and FTP servers). The major authentication schemes are supported, including HTTP Basic, Digest, NTLM, OAuth, and FTP. See the Getting Started chapter in the data provider documentation for authentication guides.
After setting the URI and providing any authentication values, set Format to "XML" or "JSON" and set DataModel to more closely match the data representation to the structure of your data.
The DataModel property is the controlling property over how your data is represented into tables and toggles the following basic configurations.
- Document (default): Model a top-level, document view of your REST data. The data provider returns nested elements as aggregates of data.
- FlattenedDocuments: Implicitly join nested documents and their parents into a single table.
- Relational: Return individual, related tables from hierarchical data. The tables contain a primary key and a foreign key that links to the parent document.
See the Modeling REST Data chapter for more information on configuring the relational representation. You will also find the sample data used in the following examples. The data includes entries for people, the cars they own, and various maintenance services performed on those cars.
After setting the properties in the application.properties file, we now configure them.
Data Source Configuration
First, we mark the REST data source as our primary data source. Then, we create a Data Source Bean.
Create a DriverManagerDataSource.java file and create a Bean within it, as shown below. If @Bean gives an error, Spring Boot may not have loaded properly. To fix this, go to File -> Invalidate Caches and restart. Additionally, make sure that Maven has added the Spring Boot dependencies.
To create a data source bean, we use the DriverManagerDataSource Class. This class allows us to set the properties of the data source. To create this Java class, right-click on "com.example.MDS" package, and choose New -> Java Class.
The following code shows the bean definition of our data source. Each driver should have a bean.
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.jdbc.DataSourceBuilder;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Primary;
import org.springframework.core.env.Environment;
import javax.sql.DataSource;
public class DriverManagerDataSource{
@Autowired
private static Environment env;
@Bean(name ="REST")
@Primary
public static DataSource RESTDataSource()
{
DataSourceBuilder<?> dataSourceBuilder = DataSourceBuilder.create();
dataSourceBuilder.driverClassName("cdata.jdbc.rest.RESTDriver");
dataSourceBuilder.url("jdbc:rest:DataModel=Relational;URI=C:/people.xml;Format=XML;");
return dataSourceBuilder.build();
}
//@Override
public void setEnvironment( final Environment environment) {
env=environment;
}
}
Next, move the REST jar file to the Documents folder (see path in command below) - The idea is to have a path without any spaces for the jar file. Then, click the Maven icon (top right corner of IntelliJ) and click "Execute Maven Goal." Now, run the following command:
mvn install:install-file "-Dfile=C:\Program Files\CData[product_name] ####\lib\cdata.jdbc.rest.jar" -DgroupId=org.cdata.connectors -DartifactId=cdata-rest-connector -Dversion=23 -Dpackaging=jar
Follow either of the given steps to run this command:
- The "-Dfile location" can be kept as the default installation path of the CData JDBC Driver. Make sure to keep the path in quotations in this case. Also, change the year and "Dversion" based on the current version of the driver being used.
- As mentioned earlier in the article, in case you relocate the
jar file to the Documents folder, make sure to modify the path in the provided command. In such instances, avoid enclosing the Dfile location in quotations and edit "Dversion" based on the current version of the driver being used.
After pressing enter, we see the following output:
Testing the Connection
The last step is testing the connection. Create a new Java class following the format
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration;
import java.sql.Connection;
import java.sql.SQLException;
import static com.example.demo.DriverManagerDataSources.RESTDataSource;
@SpringBootApplication(exclude = {DataSourceAutoConfiguration.class})
public class MDSApplication {
//remove the comment on the line below
public static void main (){
SpringApplication.run(DemoApplication.class, args);
Connection conn = RESTDataSource().getConnection();
System.out.println("Catalog: "+ conn.getCatalog());
}
}
The output generated should look like this:
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