使用dynamodb的tomcat会话管理器

Question

I am trying to use tomcat session manger with dynamoDB.

I was taking reference from this aws guide http://docs.aws.amazon.com/sdk-for-java/v1/developer-guide/java-dg-tomcat-session-manager.html .

they have mentioned in the guide that we have to use

    <Context>
        <WatchedResource>WEB-INF/web.xml</WatchedResource>
        <Manager className="com.amazonaws.services.dynamodb.sessionmanager.DynamoDBSessionManager"
         awsAccessKey="myAccessKey"
         awsSecretKey="mySecretKey"
         createIfNotExist="true" />
    </Context>

so if i don't give any target region this by default will pick us-east-1(as its hardcoded in the .jar file mentioned in aws documention). and if i specify any region it will pick that region. but i have my application in multiple regions and want separate dynamo instances for each region. As for multiple regions session id's are not unique so i can't use the same dynamo instance for all the regions.

How it can be done, any help will be appreciated.

Answer 1

Its better you create multiple DyanoDB clients, one for each region. You should use some config/prop file, which contains the different aws access-key, secret and config and based on which you create the client at the application startups. And then use it according to your business logic.

For example :- I am using the ProfileCredentialsProvider and below config file in my application, Which uses multiple dynamoDB clients.

# AWS DynamoDB setting
mumDynamoDB:
  # profile name of aws IAM role which has access to dynamoDB
  profileName: mumdynamoDBdev
  region: ap-south-1 
OrgonDynamoDB:
  # profile name of aws IAM role which has access to dynamoDB
  profileName: OrgdynamoDBdev
  region: us-west-2

And below piece of code create clients based on region and profile.

public static DynamoDB getDocClient(String profileName, String region) {
        // http://docs.aws.amazon.com/sdk-for-java/v1/developer-guide/creating-clients.html new way of
        // creating all the aws clients.
        // thread safe impl
        AmazonDynamoDB amazonDynamoDBClient = AmazonDynamoDBClientBuilder.standard()
                .withRegion(region)
                .withCredentials(new ProfileCredentialsProvider(profileName)).build();
        docClient = new DynamoDB(amazonDynamoDBClient);

        return docClient;
    } 

Then in application, based on your requirement you can use appropriate client.