General Actions:
Last modified on September 17, 2012 18:04
Workflow for a save
During the execution of a save a number of discrete steps are followed. DevForce provides several points along the way where a developer can intervene and modify the execution path. This page describes this sequence of steps and the interception points.
| Component | Action |
|---|---|
| Client Tier Application Code | The client application adds, modifies and deletes any number of business objects on the client. The client application asks a EntityManager to save all pending changes. |
| Client Tier EntityManager | Makes a save list of all of the new, modified, and deleted entities in the EntityManager entity cache. Fires the Saving event, passing in the list of entities to be saved. The listener can add or remove entities from this list or cancel the save. For now, let's assume that application listener just okays the save. Transmits the list of entities to be saved to the EntityServer. |
| Middle Tier EntityServer | Server authenticates the user. Let's assume success. The EntityServer creates a new EntityServerSaveInterceptor or an instance of a developer customized subclass. In the EntityServerSaveInterceptor the AuthorizeSave method can be used to perform security checks; the ValidateSave method can be used to perform server-side validation. When the EntityServerInterceptor.ExecuteSave method is called, where DevForce performs a temporary id to permanant id conversion and then forwards the saves to the Entity Framework for execution. |
| Data Tier Data Source | Performs the persistence operations. If there are no failures, it commits them; if there is a single failure, it rolls them all back. |
| Middle Tier – EntityServer | If the transaction failed, returns to the EntityManager the identity of the culprit entity and the exception raised by the data source. The EntityManager stores this information in the SaveResult and returns to the client application. Workflow ends. Otherwise… The transaction succeeded. The EntityServer re-queries the database(s) for all of the inserted and modified entities that are sourced in databases, thus capturing the effects of triggers that fired during save. Converts the (potentially) revised data into entities and sends them to the client side EntityManager. The server’s local copy of the entities go out of scope and the garbage collector reclaims them. This enables the object server to stay stateless. |
| Client Tier EntityManager | Performs id fixup, converting temporary ids to permanent ids based on a mapping between the two generated by the EntityServer during the save and passed back to the client in the previous step. Replaces cached entities with updates from EntityServer. They are marked “unchanged” because they are now current. Raises the Saved event with list of saved inserted and modified entities. |
| Client Tier Application Code | The application resumes. |