Overview of cooperative portlets

Cooperative portlets subscribe to a model for declaring, publishing, and sharing information with each other using the WebSphere Portal property broker. Portlets subscribe to the broker by publishing typed data items, or properties, that they can share, either as a provider or as a recipient. These portlets may be developed and deployed separately or together and can exchange information and react in a coordinated manner, thus improving the end-user experience. Conversely, as portlets are removed, the remaining portlets will still be able to function correctly and in a coordinated manner. The property broker is used to facilitate development of portlets that may be dynamically integrated, without requiring previous coordination at development time.

The portlet that provides a property is called the source portlet.
The properties that the source portlet publishes are called output properties.
The portlet that receives a property is called the target portlet.
The properties that are received by the target are called input properties.

Action processing in target portlets often does not need to distinguish between an action initiated within its own portlet area and an action initiated by the transfer of a portlet property value. Each action is also associated with a single input parameter and zero or more output parameters. Each parameter is associated with exactly one property. A parameter provides additional information about how the property value is transferred to or from the action. Parameters associated with input properties are called input parameters, while those associated with output properties are called output parameters.

At runtime, the property broker matches the data type of output properties from a source portlet with the data type of input properties from one or more target portlets. If a match is determined, the portlets are capable of sharing the property. The actual transfer of the property can be initiated by one of the following methods:

All portlets
- Using the Customizing pages, a user can create a persistent connection between two portlets, called a wire. This allows portlets to exchange properties.
- The source IBM portlet can do a programmatic publish of properties to the broker when it determines that property values have changed. Such property values are transferred to the target(s) only if wires have been created. While only IBM portlets have a programmatic API for publishing, both standard and IBM portlets can make new property values available to the broker as a side-effect of actions.
IBM portlets only
- A user launches a Click-to-Action event from an icon on the source portlet. The icon presents a pop-up menu containing the list of targets for the action. After the user selects a specific target, the property broker delivers the data to the target in the form of the corresponding portlet action. Using the Click-to-Action delivery method, users can transfer data with a simple click from a source portlet to one or more target portlets, causing the target to react to the action and display a new view with the results. Such transfer is performed without requiring the targets to be wired to the source. The user can also broadcast the property to all portlets that have declared an action associated with a matching input property.
- Depending on the browser, a user can hold either CTRL or ALT while clicking a Click-to-Action icon action and chooses to have the action selection(s) from the menu saved persistently. This results in the property associated with the icon being wired to the target action(s). If a wire is present the next time the user clicks on the icon, no selection menu is shown. Instead the wired action(s) are automatically fired. Subsequent updates to that property are transferred without further deliberate user choice.
  Wires can also be created using the Customizing pages.

Note: Currently, a standard portlet cannot be wired to an IBM portlet. Wires can only be created between portlets using the same standard. For example, standard portlets can only be wired to other standard portlets.

Cooperative portlets can be source portlets, target portlets, or both.

Source portlets identify to the property broker properties which they are able to share with other portlets.
Target portlets identify to the property broker actions which are able to process properties contributed by other portlets.

Overview of cooperative portlets

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