foo-screen.xml

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<window xmlns="http://schemas.haulmont.com/cuba/window.xsd"
        caption="Custom datasource with paging"
        class="com.company.customdatasource.web.screens.FooScreen"
        messagesPack="com.company.customdatasource.web.screens">
    <dsContext>
        <collectionDatasource id="foosDs"
                              allowCommit="false"
                              class="com.company.customdatasource.entity.Foo"
                              datasourceClass="com.company.customdatasource.web.screens.customdatasources.FooCollectionDatasource"/>
    </dsContext>
    <layout>
        <table height="100%"
               width="100%">
            <columns>
                <column id="num"/>
                <column id="name"/>
            </columns>
            <rows datasource="foosDs"/>
            <rowsCount/>
        </table>
    </layout>
</window>