What needs to be done

This application stub works with sessions stored in relational storage and runs on multiple servers.

We've chosen Cassandra as a new session storage. However it doesn't provide such flexible API as SQL database. We've decided to sacrifice data efficiency and make more computation in Java, but use Cassandra's scalability and high-availability potential.

We need to test the new storage on applications servers one by one. To do so, we are going to deploy new code and start the application with a new parameter v2. Machines where we don't want to use new storage will be either kept as is or deployed with a new code and started with either no argument or a v1 version argument.

There is no prediction which machine will be started with new or old version. Machine can be also started with the new v2 version and then switched back to the old v1 version.

User must see no difference even though any of their request may end up on any server in any version.

Sample code is part of bigger application, so please do not change:

• com.netsuite.cassandra package, because it's a fake driver
• com.netsuite.sql.SQLTool class, because it's used elsewhere in the code
• com.netsuite.session.SessionService interface, because it's used elsewhere in the code

Functionality must be preserved (return only valid, max. 1 hour old session).

Example request flow

        1st request    +----+
    +--------------->  | v1 |
        Session 1      +----+

    --- SESSION 1 EXPIRES ---

        2nd request    +----+
    +--------------->  | v2 |
      New session #2   +----+
                       
        3rd request    +----+
    +--------------->  | v1 |
        session #2     +----+

User is authenticated in a second request, but 3rd request ends up on v1 server. User must be still logged in and must see no difference.

Final result

Session created in any version must be available on all servers including the ones where the new code haven't been released yet.

Setup

You can build a project with a ./gradlew build or ./gradlew.bat build.

We highly recommend Intellij IDEA Community edition (https://www.jetbrains.com/idea/download/). To generate idea project, execute ./gradlew.bat idea

How to execute

Execute current version: java -jar build/libs/ns_infra_test_dist.jar

Final implementation must be executed with java -jar build/libs/ns_infra_test_dist.jar v1 or java -jar build/libs/ns_infra_test_dist.jar v2 where v1 indicates usage of SQL, v2 indicates usage of Cassandra

There's no need to install anything except gradle dependencies. All interfaces have fake implementations.