//restituisce la lista di utenti
@GET
@Path("/getlistanodi")
@Produces({"application/json", "application/xml"})
public Response getListaNodi() {

    return Response.ok(NodiEdge.getInstance()).build();
}

@Path("/add")
@POST
@Consumes({"application/json", "application/xml"})
public Response addNodo(Nodo u) {

    NodiEdge.getInstance().addNodo(u);
    return Response.ok().build();
}

@Path("/remove/{idnodo}")
@DELETE
@Produces({"application/json", "application/xml"})
public Response removeNodo(@PathParam("idnodo") String id) {

    NodiEdge.getInstance().removeNodo(id);
    return Response.ok().build();
}

<filter>
    <filter-name>UploadFilter</filter-name>
    <filter-class>com.sun.webui.jsf.util.UploadFilter</filter-class>
    <init-param>
        <param-name>maxSize</param-name>
        <param-value>-1</param-value>
    </init-param>
</filter>
<filter-mapping>
    <filter-name>UploadFilter</filter-name>
    <servlet-name>FacesServlet</servlet-name>
</filter-mapping>
<servlet>
    <servlet-name>FacesServlet</servlet-name>
    <servlet-class>javax.faces.webapp.FacesServlet</servlet-class>
    <load-on-startup>1</load-on-startup>
</servlet>
<servlet>
    <servlet-name>ThemeServlet</servlet-name>
    <servlet-class>com.sun.webui.theme.ThemeServlet</servlet-class>
    <load-on-startup>2</load-on-startup>
</servlet>
<servlet>
<servlet-name>DownloadServlet</servlet-name>
<servlet-class>org.glassfish.admingui.common.servlet.DownloadServlet</servlet-class>
<init-param>
    <param-name>ContentSources</param-name>
    <param-value>
            org.glassfish.admingui.common.servlet.LBConfigContentSource,
            org.glassfish.admingui.common.servlet.ClientStubsContentSource,
            org.glassfish.admingui.common.servlet.LogFilesContentSource
            org.glassfish.admingui.common.servlet.LogViewerContentSource
    </param-value>
</init-param>
<init-param>
    <param-name>contentSourceId</param-name>
    <param-value>LBConfig</param-value>
</init-param>
</servlet>
<servlet-mapping>
<servlet-name>DownloadServlet</servlet-name>
<url-pattern>/download/*</url-pattern>
</servlet-mapping>
<servlet-mapping>
    <servlet-name>FacesServlet</servlet-name>
    <url-pattern>/resource/*</url-pattern>
</servlet-mapping>
<servlet-mapping>
    <servlet-name>FacesServlet</servlet-name>
    <url-pattern>/html/*</url-pattern>
</servlet-mapping>
<servlet-mapping>
    <servlet-name>FacesServlet</servlet-name>
    <url-pattern>/faces/*</url-pattern>
</servlet-mapping>
<servlet-mapping>
    <servlet-name>FacesServlet</servlet-name>
    <url-pattern>*.jsf</url-pattern>
</servlet-mapping>
<servlet-mapping>
    <servlet-name>ThemeServlet</servlet-name>
    <url-pattern>/theme/*</url-pattern>
</servlet-mapping>
<session-config>
    <cookie-config>
        <http-only>true</http-only>
    </cookie-config>
</session-config>
<!-- following mapping added to avoid JSF warning. refer to GLASSFISH-19403 -->
<mime-mapping>
    <extension>jsp</extension>
    <mime-type>text/html</mime-type>
</mime-mapping>

<welcome-file-list>
    <welcome-file>/index.jsf</welcome-file>
</welcome-file-list>
<error-page>
    <exception-type>javax.faces.application.ViewExpiredException</exception-type>
    <location>/</location>
</error-page>

<login-config>
    <auth-method>FORM</auth-method>
    <realm-name>admin-realm</realm-name>
    <form-login-config>
        <form-login-page>/login.jsf</form-login-page>
        <form-error-page>/loginError.jsf</form-error-page>
    </form-login-config>
</login-config>
<security-role>
    <role-name>admin</role-name>
</security-role>

@XmlElement(name="nodi")
private List<Nodo> listaNodi;
private static NodiEdge instance;

private int distNodi;

public NodiEdge() {

    listaNodi = new ArrayList<Nodo>();
}

//singleton
public synchronized static NodiEdge getInstance(){

    if(instance==null)
        instance = new NodiEdge();
    return instance;
}

public synchronized List<Nodo> getListaNodi() {

    return new ArrayList<>(listaNodi);
}

public synchronized List<Nodo> addNodo(Nodo u)
{
    List<Nodo> copiaLista = getListaNodi();

    if (listaNodi.size()==0)
        listaNodi.add(u);
    else {
        for (Nodo n : copiaLista) {
            if (n.getID().toLowerCase().equals(u.getID().toLowerCase())) {
                System.err.println("Inserimento negato! Identificatore già esistente.");
                break;
            }
            else {
                distNodi = Math.abs((u.getX() - n.getX()) + (u.getY() - n.getY()));
                if (distNodi < 20) {
                    System.err.println("Inserimento negato! Posizione troppo vicina ad altri nodi.");
                    break;
                } else {
                    listaNodi.add(u);
                    System.out.println("ID nodo: " + n.getID() + ", indirizzo IP: " + n.getIPaddress() +
                            ", n° porta: " + n.getPNd());
                }
            }

        }

    }

    return copiaLista;


}

public synchronized void removeNodo(String id)
{
    List<Nodo> copiaLista = getListaNodi();

    if (listaNodi.size()==0)
        System.err.println("Operazione impossibile! Nessun nodo nella griglia");
    else {
        for (Nodo n : copiaLista) {
            if (!n.getID().toLowerCase().equals(id.toLowerCase()))
                System.err.println("Nodo non presente nella griglia.");
            else {
                listaNodi.remove(n);
                System.out.println("Nodo eliminato.");
                break;
            }

        }

    }