Implement cache update policies through data tracking

Preparations

Create an AccessKey and obtain the AccessKey ID and AccessKey Secret. For more information, see create an AccessKey pair.

Procedure

This procedure uses IntelliJ IDEA (Community Edition 2018.1.4 Windows) as an example.

1. Download the SDK package (dts-subscribe-3.0.jar).
2. Add the dts-subscribe-3.0.jar to project dependencies.
   1. Open IntelliJ IDEA, click File > New > Project, and then follow the prompts to create a Maven project.
   2. Click File > Project Structure.
   3. Click Moduleson the left, and click > 1 JARs or directoriesOn the right side of the page.
   4. Follow the prompts to select the downloaded file: dts-subscribe-3.0.jar , and add it to the project dependency.
      
3. Perform the following steps to run the sample code of MongoDB or Redis Cache :
   • Run sample code of MongoDB cache
     1. Double-click to open the pom.xml file, add the following configuration to the file.

        <dependencies>
            <dependency>
                <groupId>com.vividsolutions
                <artifactId>jts</artifactId>
                <version>1.13</version>
            </dependency>
            <dependency>
                <groupId>org.mongodb
                <artifactId>mongo-java-driver</artifactId>
                <version>3.2.0</version>
            </dependency>
        </dependencies>

     2. Save the configurations and wait for the relevant dependency package to be loaded.
        Note We recommend that you enable the Maven dependency automatic update function of IntelliJ IDEA.
     3. Create a new Java Class file named DTSMySQL2Mongo in the project.
     4. Download the sample code of MongoDB cache.
     5. Copy and replace the content in the downloaded sample code to the DTSMySQL2Mongo file in the project.
     6. Set the parameters in the DTSMySQL2Mongo file of the project.

        Parameter	Description
        accessKey	The AccessKey ID and AccessKey Secret of your Alibaba cloud account. For more information, see preparation.
        accessSecret
        Subscription_Instance_ID	The ID of the change tracking instance. You can log in DTS console, click Change Tracking Tasks in the left-side navigation and find the target instance ID.
        mongUrl	The connection string and authentication database name of MongoDB database, the format is <connection address: <port>/<authentication database>, for example ds-bp********-pub.mongodb.rds.aliyuncs.com:3717/admin.
        mongUserName	The account of the MongoDB database. Note The database account must have the read and write permissions on the destination database. For example, the subscribed table is named testdata. After the program obtains the incremental change, it writes the data into the testdata database of the MongoDB database. Therefore, the database account must have the read and write permissions on the testdata database.
        mongUserPassword	The password of the database account.

     7. On the top of the IntelliJ IDEA page, click Run > Run to run the program.
   • Run the sample code for Redis Cache
     1. Double-click to open the pom.xml file, add the following configuration to the file.

        <dependencies>
            <dependency>
                <groupId>com.vividsolutions
                <artifactId>jts</artifactId>
                <version>1.13</version>
            </dependency>
            <dependency>
                <groupId>redis.clients
                <artifactId>jedis</artifactId>
                <version>2.7.2</version>
            </dependency>
        </dependencies>

     2. Save the configurations and wait for the relevant dependency package to be loaded.
        Note We recommend that you enable the Maven dependency automatic update function of IntelliJ IDEA.
     3. Create a new Java Class file named DTSMySQL2Redis in the project.
     4. Download the Redis Cache Sample code.
     5. Copy and replace the content in the downloaded sample code to the DTSMySQL2Redis file in the project.
     6. Set the parameters in the DTSMySQL2Redis file of the project.

        Parameter	Description
        accessKey	The AccessKey ID and AccessKey Secret of your Alibaba cloud account. For more information, see preparation.
        accessSecret
        Subscription_Instance_ID	The ID of the change tracking instance. You can log in DTS console, click Change Tracking Tasks in the left-side navigation and find the target instance ID.
        redisPassword	The password of the Redis database. Note If a password is set in the Redis database, you also need to modify the line 73 in the code formpool = new JedisPool(config, redisUrl, redisPort, 3000); to pool = new JedisPool(config, redisUrl, redisPort, 3000,redisPassword).
        redisPort	The service port of the Redis Database. The default port number is 6379.
        redisUrl	The endpoint (domain name or IP address) of the Redis database.

     7. On the top of the IntelliJ IDEA page, click Run > Run to run the program.
4. When the program runs, it changes the incremental data in the source database and writes the incremental data to the MongoDB or Redis database.