Replication Constraints across Disparate PowerDesigner Model Object Types

[Former Member]

Working through PowerDesigner as a new user and have a question regarding Replication. I have observed that I'm unable to Replicate a Data Entity between a Conceptual Data Model (PowerDesigner) Object Type and a Logical Data Model Object Type. Are the Replication constraints documented anywhere in the PowerDesigner materials?

To frame the context of my questions, our work process is to first create a Conceptual Data Model during Business/Stakeholder Requirements gathering, then "promote" the Conceptual Data Model to a Logical Data Model for Functional Requirements gathering.

Thanks in advance, Mike

[GeorgeMcGeachie · Accepted solution]

When you replicate an object. the replica object must be the same object type as the original. Some CDM objects (such as entities, relationships, business rules and domains) may look the same as they do in the LDM, but they're not the same type of object.

To replicate objects between a CDM and a LDM, generate a LDM from the CDM. This will create, for example, an LDM entity for each of your CDM entities. If the CDM changes, generate again to the LDM in update mode.

Replication is not really for run-of-the-mill stuff like this .

[Former Member · Accepted solution]

George, thank you for the quick response, very much appreciated. The needed/required behavior for our work processes is to have a core collection of reusable entities that we can use to generate new Conceptual/Logical Data Models as new Projects are started. The second behavior we would like to have is when a Data Entity is updated, regardless of the Model in which it exists, we want those changes propagated to all users of that Data Entity.  Just trying to offer some context around the question and why we are looking to the Replication functionality as a solution.

[Former Member · Accepted solution]

Hi Mike,

George is right. You can either synchronize your CDM and LDM using Tools - Generate logical data model functionality (and this is on demand, not in real-time) or you can replicate objects to have real-time synchronization, but you can create replicas always between two (or inside one) model of THE SAME TYPE. So I see three possibilities for you:

1) Sacrifice your CDM model and start using one LDM model as your previous CDM and other LDM models can from now on contain your real-time synced replicas. The price you pay for this, is the fact, that you will loose all the CDM unique features (concept of data items for example).

2) You can develop some heavy automation using VBScript, that will propagate your changes from CDM to LDM models. You can attach it for example to the Validate event handler. But with my rich experience with these handlers, I really wouldn`t recommend it to you to use it that way.

3) Or you can accept the way of how it is supposed to be done in PD and use it that way, because there was a reason to do it that way (on demand, and not real-time). One of the reasons could possible be the fact, that CDM model is very often modified by different people, than LDM model(s) and nobody would like to have his model modified without knowing.

Regards,

Ondrej

[Former Member · Accepted solution]

My preference would be to use the tool as designed, we were thinking of using the Replication functionality for Entities that are used/re-used across multiple data realm/domain models. Does that make sense?

[Former Member · Accepted solution]

Reusing entities for different domains (BUT ON THE SAME MODEL LEVEL!) is quite common approach. I recommend using this so-called referential model, which stores the originals of these objects (entities in your case) and these referential objects are shared and reused to other "normal" models. And it is up to you, to decide, whether you will use shortcuts or replicas. The advantage of replicas is, that you can unsync only a few properties of this replicated object (for example Comment and Description) and all other properties are read-only and synchronized in real-time with the original object. The disadvantage is that replicated object consumes even a little more space than independent separate object.

For the real-time sync in both approaches (shortcuts and replicas) it is necessary, to have both models opened in one PowerDesigner instance.

This approach (with objects in referential model) is very common for Domains (objects in PD) at physical data model layer. And for LDM, you can use it for your entities.

Regards,

Ondrej