Using Non Serializable objects in Activiti BPMN

Question

I want to use Activiti BPMN process for some database update task. My process is as follows.

Start Event-> Service Task 1 -> Service Task 2 -> Service Task 3 -> End Event

In the service implementation class of Service task 1 : I created a java.sql.Connection for MySQL database. I need to pass the same Connection object to the Service Task 2 and Service Task 3. Basically those two classes will do some insertions for the database using the same Connection object.

I tried as follows (dbConn is the the Class which contains java.sql.Connection type dbConnection)

execution.setVariable("DBConn",dbConn);

But it gives an exception since the connection object is not serializable.

"org.activiti.engine.ActivitiException: Couldn't serialize value"

So what is the best way to pass such non serializable variables between service tasks of a process? Or is there any way to define such common objects to multiple Service Tasks in one place and use them within service Tasks ( Something like global variables for the process)

Is there any particular reason why you want to pass the same connection object ? — Younes Regaieg
I want to use that same connection for insertion tasks in Service task 2 and Service Task 3. The DB connection is created with setAutoCommit(false). So after the execution of Service task 3 I want to commit the transaction — Anupama Pathirage
What would happen if -for some unexpected reason- the server craches and you had to restart it ? — Younes Regaieg
Well that will be a problem. Can you please let me know any other way to handle DB transactions using activiti. Basically I want to create a series of DB updates and commit the transaction at the end if all transactions are successull or else roll back the all the transactions. — Anupama Pathirage

Anupama Anupama · Accepted Answer · 2016-03-28T09:47:03

You can use Thradlocal in Java to pass connection object to different service tasks.

For example use a Base class like below and extend each service task from that. Then you can set the dbConnection and use whenever required by using get method.

public class BaseServiceTask
{
    public static final ThreadLocal<Connection> localConnectionContext = new ThreadLocal<Connection>();

    public static void initDBConnector(Connection dbConn)
    {
        localConnectionContext.set(dbConn);
    }

    public static Connection getDBConnector()
    {
        return localConnectionContext.get();
    }
}

Notice :
This approach assumes all service tasks are executed in the same thread, which is the case for this particular question, but once you include some user task / timer (or any asynchronous logic) this is not a viable solution anymore !

Using Non Serializable objects in Activiti BPMN

2 Answers