Howto fire event to refresh view

<Alloy>
    <Collection src="collection1"></Collection>
    <Collection src="collection2"></Collection>
        <TabGroup>
        <Tab title="Tab1" id="tab1">
            <Window title="Tab 1">
                <TableView
                    dataCollection="collection1"
                    onDragEnd="refreshcollection1">
                    <TableViewRow onClick="openChildView">
                        <Label>{testDataField}</Label>
                    </TableViewRow>
                </TableView>
            </Window>
        </Tab>
        <Tab title="Tab 2" icon="KS_nav_views.png">
            <Window title="Tab 2">
                <Label>I am Window 2</Label>
            </Window>
        </Tab>
    </TabGroup>
</Alloy>

function refreshcollection1(){
    Alloy.Collections.refreshcollection1.getDateFromWebserviceIntoSQLite();
}

How can I fire an event will refresh the TableView ? I assume it is necessary to do this, because getDateFromWebserviceIntoSQLite() is an extended method within the collection. But I don't know how to fire the right event.

Hopefully I get help and the question is done right. I also helped others based on my skills. (finding out how to get help)