Difference between managed bean and backing bean

I came across the terms "managed bean" and "backing bean" in several forums. Many people think both are the same. But, there seems to be a slight difference. Can any one help me to understand the exact difference between these two terms?

Solution 1:

Changing my initial answer - there is no meaningful difference between the two. The tutorial says that backing beans are later declared as managed beans. So, to summarize:

• a backing bean is the class out of context
• a managed bean is the backing bean whenever it is declared to be used with the JSF managed bean facility.

I've never actually used the term "backing bean", because I found no use to it. So you might be better off using only "managed bean". Note that in JSF 2.0 (and in CDI) you have @ManagedBean- so your bean is a managed bean.

BalusC suggested that "backing bean" is the definition, and "managed bean" is the instance. While this might have been the original idea of JSF creators, I don't think it is worth supporting it. CDI and spring for example don't have different term for "bean definition" and "bean instance".

The JSF 2.0 specification mentions the term "backing bean" only a few times, with no definition whatsoever. In addition to that it mentions "backing bean class", which might mean that "backing bean" != "backing bean class", which brings further confusion.

So to conclude - for me both are interchangeable, and I'd stick to only using "managed bean"

Solution 2:

What is Managed Bean?

JavaBean objects managed by a JSF implementation are called managed beans. A managed bean describes how a bean is created and managed. It has nothing to do with the bean's functionalities.

What is Backing Bean?

Backing beans are JavaBeans components associated with UI components used in a page. Backing-bean management separates the definition of UI component objects from objects that perform application-specific processing and hold data. The backing bean defines properties and handling-logics associated with the UI components used on the page. Each backing-bean property is bound to either a component instance or its value. Backing bean also defines a set of methods that perform functions for the component, such as validating the component's data, handling events that the component fires and performing processing associated with navigation when the component activates.

What are the differences between a Backing Bean and Managed Bean?

Backing Beans are merely a convention, a subtype of JSF Managed Beans which have a very particular purpose. There is nothing special in a Backing Bean that makes it different from any other managed bean apart from its usage.

MB : Managed Bean ; BB : Backing Bean

1) BB: A backing bean is any bean that is referenced by a form.

MB: A managed bean is a backing bean that has been registered with JSF (in faces-config.xml) and it automatically created (and optionally initialized) by JSF when it is needed.

The advantage of managed beans is that the JSF framework will automatically create these beans, optionally initialize them with parameters you specify in faces-config.xml.

2) BB: Backing Beans should be defined only in the request scope

MB: The managed beans that are created by JSF can be stored within the request, session, or application scopes .

Backing Beans should be defined in the request scope, exist in a one-to-one relationship with a particular page and hold all of the page specific event handling code. In a real-world scenario, several pages may need to share the same backing bean behind the scenes. A backing bean not only contains view data, but also behavior related to that data.

Solution 3:

Backing Bean is any bean that is bound with JSF UI. while Managed bean is any bean

Solution 4:

Simply put,

You as developer do:

@ManagedBean(name="managedBean")
@RequestScoped
public class BackingBean {
    // ...
}

JSF as bean management framework does under the covers:

BackingBean managedBean = new BackingBean();
externalContext.getRequestMap().put("managedBean", managedBean);

So, the backing bean is the concrete class which is developed by you and usually tied to the view, and the managed bean is the concrete instance, which is under the covers created and put in the desired scope by the bean management framework on demand, and available by #{managedBean} in EL. You never need to create and put it in the scope yourself. If you did so then there's no means of a framework-managed bean.

CDI @Named and Spring @Component do essentially the same thing as JSF @ManagedBean.

To learn more about how bean management frameworks like JSF, CDI and Spring find and create their managed beans, the following troubleshooter should provide in depth insight: Identifying and solving javax.el.PropertyNotFoundException: Target Unreachable.

See also:

• What components are MVC in JSF MVC framework?
• JSF Controller, Service and DAO
• JSF managed bean naming conventions