IS IT POSSIBLE TO HANDLE p:ajax event IN WEBFLOW OR IT'S IMPOSSIBLE AT ALL

Can someone to answer how to handle p:ajax event in webflow?!

I have in my page

Code:

<p:tabView id="tabView" var="category" value="#{showcaseBean.categories}">

When I'm clicking every tab the next tab with related goods to this category should appear.
So I have to catch

Code:

<p:ajax event=”tabChange” listener=”#{showcaseBean.onChange}” />

in my showcaseBean and fetch the related goods from database like

Code:

ShowcaseService.getGoodsByCategory(Category category) {}

This ShowcaseService can work with database only through flow.xml file (because transaction is bound to flow).
So I cannot make something like

Code:

(inside ShowcaseBean) ShowcaseService showcaseService = new ShowcaseService(); showcaseService.getGoodsByCategory(Category category)

Instead of it I have to reflect this fetching in flow.xml like

Code:

<transition on="changeTab"> <evaluate expression="showcaseService.getGoodsByCategory(showcaseBean.selectedCategory)" /> </transition>

But examples (that I have seen) show the handling only JSF action (in flow.xml ) like

Code:

<transition on="cancelBooking"> <evaluate expression="bookingService.cancelBooking(bookings.selectedRow)" /> </transition>

where cancelBooking taken from

Code:

<p:commandButton id="cancel" value="Cancel" action="cancelBooking"/>

So how can I reflect ”tabChange” event

Code:

<p:ajax event=”tabChange” listener=”#{showcaseBean.onChange}” />

in flow.xml to invoke method getGoodsByCategory of ShowcaseService?

It's strange if webflow works with action events only!