How to implement a dynamic list with a JSF 2.0 Composite Component?

I’d use a <h:dataTable> in a composite component with a backing UIComponent which you can bind by componentType attribute of the <composite:interface>. In the backing UIComponent you can then maintain the DataModel and define the actions.

dynamicFieldList.xhtml

<ui:composition
    xmlns:f="http://java.sun.com/jsf/core"
    xmlns:h="http://java.sun.com/jsf/html"
    xmlns:ui="http://java.sun.com/jsf/facelets"
    xmlns:cc="http://java.sun.com/jsf/composite"
>
    <cc:interface componentType="dynamicFieldList">
        <cc:attribute name="value" type="java.util.List" required="true" />
    </cc:interface>
    <cc:implementation>
        <h:dataTable id="table" binding="#{cc.table}" value="#{cc.attrs.value}" var="field">
            <h:column><h:outputLabel value="#{field.label}" /></h:column>
            <h:column><h:inputText value="#{field.value}" /></h:column>
            <h:column><h:commandButton value="remove" action="#{cc.remove}" /></h:column>
        </h:dataTable>
        <h:commandButton value="add" action="#{cc.add}" />
    </cc:implementation>
</ui:composition>

(the <h:inputText> can if necessary be your composite field component)

com.example.DynamicFieldList

@FacesComponent(value="dynamicFieldList") // To be specified in componentType attribute.
@SuppressWarnings({"rawtypes", "unchecked"}) // We don't care about the actual model item type anyway.
public class DynamicFieldList extends UINamingContainer {

    private UIData table;

    public void add() {
        ((List) getAttributes().get("value")).add(new Field("somelabel"));
    }

    public void remove() {
        ((List) getAttributes().get("value")).remove(table.getRowData());
    }

    public UIData getTable() {
        return table;
    }

    public void setTable(UIData table) {
        this.table = table;
    }

}

Use it as follows:

<h:form>
    <my:dynamicFieldList value="#{bean.fields}" />
</h:form>

with just this

@ManagedBean
@ViewScoped
public class Bean implements Serializable {

    private List<Field> fields;

    public Bean() {
        fields = new ArrayList<>();
    }

    public List<Field> getFields() {
        return fields;
    }

}

and

public class Field implements Serializable {

    private String label;
    private String value;

    public Field() {
        //
    }

    public Field(String label) {
        this.label = label;
    }

    public String getLabel() {
        return label;
    }

    public void setLabel(String label) {
        this.label = label;
    }

    public String getValue() {
        return value;
    }

    public void setValue(String value) {
        this.value = value;
    }

}