Liferay DXP implements several communication mechanisms across apps including those specified by the JSR-286 standard: public render parameters and events. Public render parameters are easy to use and can be quite powerful. Some Liferay apps provide a configuration UI to help you get the most out of this communication mechanism. To access this UI, open your application’s configuration window by clicking on the Options icon () and selecting Configuration. Then click on the Communication tab.
The screenshot above is for the Wiki application, which has six public render
For each of these parameters, you can configure the app to ignore the values
coming from other apps to read the value from another parameter.
Why might it be useful to ignore the values for certain parameters that come from other apps? Consider a common use case for the Wiki application. The Wiki app is often used along with the Tags Navigation app so that when a user clicks on a tag of the latter, the Wiki app shows a list of pages with that tag. In some cases, an administrator may want the Wiki app to always show the front page independently of any tag navigation done through other apps. This can be achieved by checking the Ignore checkbox so that the values of the parameter coming from those other apps are ignored.
Reading the value of a parameter from another app is an advanced but very powerful option that allows apps to communicate with each other even if their developers didn’t intend them to. For example, imagine that the Wiki application is being used to publish information about certain countries. Imagine further that there’s another app that allows browsing countries for administrative reasons. The second app has a public render parameter called country with the name of the country. You’d like the Wiki to show the information from the country that’s selected in the administration app. This can be achieved by setting the value of the title parameter of the Wiki app to be read from the country parameter of the administration app. Cool, isn’t it?