Serializing process variables

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mariusz_cwikla

Hi,
I have a couple of questions regarding process variables storage, but the short one is: is there a way to create custom serializer for my process variables?

Let me provide some background:
- let's say that I use process variables as complex object, for example:

class Person implements Serializable{
  private String id, firstName, lastName;
  //setters & getters
}
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1. I know, that when I use such object then Activiti serializes it using Java Seralization mechanism[/li]
2. let's say that in some point in time a developer upgrades such object:
2.1 he may add new attribute to object
2.2 he may remove attribute
2.3 he may rename an attribute (since he make a typo a week ago)
3. application is already deployed in production
4. I know that process variables for such complex objects are stored as byte array in ACT_GE_BYTEARRAY  table. Is there a way to upgrade my objects in that table by some SQL scripts?

1. One idea would be to create a proxy object and store only an "id" attribute. Then create readObject/writeObject methods that serialize/deserialize only id attribute. Rest of the attributes would be delegated, for example:

class PersonDelegate{
   private Person realPerson;
   private String id;
   
   private void writeObject(java.io.ObjectOutputStream out) throws IOException{      
      out.writeBytes(id);
   }
   private void readObject(java.io.ObjectInputStream in) throws IOException, ClassNotFoundException{
      id = in.readLine();      
   }
   
   public String getFirstName(){
      loadPerson();
      return realPerson.getFirstName();
   }
   
   private void loadPerson(){
      if(realPerson==null)
         realPerson=use_my_service_to_load_person(id);
   }
}
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Then I store only id in Activiti tables and real objects are stored somewhere else where I can manage my structure modification.

2. In user guide I found following sentence: "Activiti supports complex Java objects to be stored as process variables like Serializable objects, JPA entities or whole XML documents as Strings."

How can I store complex process variables as XML documents?

3. Another option is to use JPA support mentioned in 2), but I also want to use OSGi. I've seen, that Activiti supports OSGi, but I only found following configuration from book "Activiti in Action"

  <bean id="configurationFactory" class="org.activiti.osgi.blueprint.ConfigurationFactory">
    <property name="dataSource" ref="dataSource" />
    <property name="databaseSchemaUpdate" value="true" />
  </bean>
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It does only contain configuration for dataSrouce, it does not contain configuration for JPA. It shouldn't be hard to add JPA to this configuration, but if anyone has already full configuration, I would be greatful I someone posts such configuration with JPA.
 
  So anyway, if I use JPA will I have my objects stored only in my tables instead of ACT_GE_BYTEARRAY as byte array?
 
Summary:
1. Is there a way to create custom serializer for my process variables?
2. How can I store complex process variables as XML documents?
3. If I use JPA will I have my process stored only in my tables instead of ACT_GE_BYTEARRAY as byte array?
4. Any other idea?
5. Can somebody provide me sample Blueprint configuration with JPA (regarding org.activiti.osgi.blueprint.ConfigurationFactory or some other classes).



Thanks in advance for any help.

jbarrez

wow, that's a lot of text 😉

1. Is there a way to create custom serializer for my process variables?

Yes, check the VariableTypes and the VariableType classes.
That's the way all variable serialization is implemented.

2. How can I store complex process variables as XML documents?

Then you'd need a custom serializer, indeed.

3. If I use JPA will I have my process stored only in my tables instead of ACT_GE_BYTEARRAY as byte array?

It will only store the primary key to your entity, nothing else.

4. Any other idea?

Nope 🙂

5. Can somebody provide me sample Blueprint configuration with JPA (regarding org.activiti.osgi.blueprint.ConfigurationFactory or some other classes).

Sorry, I'm no osgi user…