Server-Side Trigger for Storages

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With JVx, the business logic can be developed in either the database or the middle tier. For the development of the business logic entirely in the middle tier, so-called server-side triggers are required. These triggers work just like the DataBook events at the client.

For example, a server-side trigger is called when a new record was inserted, modified, or deleted.


We use a RemoteDataBook at the client for the creation of user accounts. A user is defined by username, password, first name, and last name. The password, however, has to be encrypted before it is stored in the database.

We define the storage:

public DBStorage getUsers() throws Exception
   DBStorage users = (DBStorage)get("users");
   if (users == null)
      users = new DBStorage();
      users.eventBeforeInsert().addListener(this, "doEncryptPwd");
      users.eventBeforeUpdate().addListener(this, "doEncryptPwd");
      put("users", users);
   return users;

and the trigger to insert and update:

public void doEncryptPwd(StorageEvent pEvent) throws Exception
   IBean bn = pEvent.getNew();
   String sNew = (String)bn.get("PASSWORD");
   String sOld;
   IBean bnOld = pEvent.getOld();
   if (bnOld != null)
      sOld = (String)bnOld.get("PASSWORD");
      sOld = null;
   if (!CommonUtil.equals(sOld, sNew))
      bn.put("PASSWORD", AbstractSecurityManager.getEncryptedPassword(
                         SessionContext.getCurrentSessionConfig(), sNew));

In our example, we use IBean to access the properties. The event also allows the use of POJOs, as shown in the following example:

public void doEncryptPwd(StorageEvent pEvent)
    User user = pEvent.getNew(User.class);     


Any POJO can be used. The implemented mechanism attempts to align the properties via the database´s column identifiers. In our previous example, we could also use an Address POJO, as long as it contains the relevant properties. Only feasible properties are aligned.

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