About Eugene Fedorenko
Within passivation/activation cycle of application modules the framework passivates and activates view objects as well. Usually the framework saves information about VO’s state, current row, bind variables values and such. But not the data. The VO’s query is going to be re-executed and the data is going to be re-fetched after activation of the view object. In most cases the query execution is not performed during or right after the activation phase, but is deferred until the view object is really used. This behavior is quite logical. Let’s assume that our application consists of several pages representing data of different view objects. If we send requests to the server from the same page we are going to get VOs executed that are used on that page only. All other view objects, used on other pages, are going to be passivated and activated as well. But they are not going to be re-executed until we ask the framework to do that by navigating to the particular page. And that’s cool! It means that we don’t perform unnecessary query executions and we don’t waste our memory. But there are some cases when the framework performs VO’s query execution during the activation phase not bothering whether we really use the VO.
One of these cases is about using of transient VO’s attributes. The common recommendation is to not passivate such attributes. But sometimes transient attributes are used to store some custom data and passivation/activation mechanism is used as a convenient way to save this data and keep it alive. Be careful with this approach. If any values of transient attributes are passivated, then the framework will execute the query during the activation of the view object.
Source : http://www.javacodegeeks.com/2013/07/passivation-and-activation-of-view-objects-with-transient-attributes.html
