edit 2: Found the mistake. I tried to initialize the Shareable object in the constructor. At that time the client's register method is not yet called, so the JCRE doesn't have its AID. While my server's getShareableInterfaceObject(AID clientaid, byte parameter) method doesn't require the client's AID to be != null the JCRE probably does, since it calls this method for my client. I now initialize my Shareable object when I process my first APDU and it now works.
And btw, thank you owlstead for helping with formatting of my post. Definitely made it easier to read!
I'm new to Java Card development and I can't get my Shareable interface to work.
I have an interface class declaring a function my client applet wants to use. My server applet implements this class. My client applet looks up the AID and tries to acquire the interface by calling getAppletShareableInterface(). But this always returns null.
My server applet's getShareableInterface() consists of just return this;, so I guess the fault lies elsewhere. But I have no idea where.
I'm using the JCWDE and stepping through the code I see that my server applet calls register so the client applet should be able to find it. Can anyone give me some pointers what could be going wrong?
edit:
public interface IF extends Shareable {
public void method();
}
public class Server extends Applet implements IF {
public getShareableInterfaceObject {
return this;
}
}
public class Client extends Applet {
private Client() {
AID ServerAID = JCSystem.lookupAID(byteArrayAID, (short)0, (byte)byteArrayAID.length);
interface = (IF)JCSystem.getAppletShareableInterfaceObject(ServerAID, (byte)0x00);
}
public void process(APDU apdu) {
interface.method();
}
}
lookupAID returns the correct AID, but getAppletShareableInterfaceObject returns null as if the server applet didn't exist.
Found the mistake. I tried to initialize the Shareable object in the constructor. At that time the client's register method is not yet called, so the JCRE doesn't have its AID. While my server's getShareableInterfaceObject(AID clientaid, byte parameter) method doesn't require the client's AID to be != null the JCRE probably does, since it calls this method for my client. I now initialize my Shareable object when I process my first APDU and it now works.
Related
ConfigProperty.idPropertyMap is filled on the server side. (verified via log output)
Accessing it on the client side shows it's empty. :-( (verified via log output)
Is this some default behaviour? (I don't think so)
Is the problem maybe related to the inner class ConfigProperty.IdPropertyMap, java.util.HashMap usage, serialization or some field access modifier issue?
Thanks for your help
// the transfer object
public class ConfigProperty implements IsSerializable, Comparable {
...
static public class IdPropertyMap extends HashMap
implements IsSerializable
{
...
}
protected static IdPropertyMap idPropertyMap = new IdPropertyMap();
...
}
// the server service
public class ManagerServiceImpl extends RemoteServiceServlet implements
ManagerService
{
...
public IdPropertyMap getConfigProps(String timeToken)
throws ConfiguratorException
{
...
}
}
added from below after some good answers (thanks!):
answer bottom line: static field sync is not implemented/supported currently. someone/me would have to file a feature request
just my perspective (an fallen-in-love newby to GWT :-)):
I understand pretty good (not perfect! ;-)) the possible implications of "global" variable syncing (a dependency graph or usage of annotations could be useful).
But from a new (otherwise experienced Java EE/web) user it looks like this:
you create some myapp.shared.dto.MyClass class (dto = data transfer objects)
you add some static fields in it that just represent collections of those objects (and maybe some other DTOs)
you can also do this on the client side and all the other static methods work as well
only thing not working is synchronization (which is not sooo bad in the first place)
BUT: some provided annotation, let's say #Transfer static Collection<MyClass> myObjList; would be handy, since I seem to know the impact and benefits that this would bring.
In my case it's rather simple since the client is more static, but would like to have this data without explicitely implementing it if the GWT framework could do it.
static variables are purely class variable It has nothing to do with individual instances. serialization applies only to object.
So ,your are getting always empty a ConfigProperty.idPropertyMap
The idea of RPC is not that you can act as though the client and the server are exactly the same JVM, but that they can share the objects that you pass over the wire. To send a static field over the wire, from the server to the client, the object stored in that field must be returned from the RPC method.
Static properties are not serialized and sent over the wire, because they do not belong to a single object, but to the class itself.
public class MyData implements Serializable {
protected String name;//sent over the wire, each MyData has its own name
protected String key;
protected static String masterKey;//All objects on the server or client
// share this, it cannot be sent over RPC. Instead, another RPC method
// could access it
}
Note, however, that it will only be that one instance which will be shared - if something else on the server changes that field, all clients which have asked for a copy will need to be updated
I am trying to create a dynamic navigation class.
class myApp_Helper_Breadcrum{
protected $navigationArray=array();
private static $_instance = null;
public static function getInstance()
{
if (!isset(self::$_instance)) {
self::$_instance = new self();
}
return self::$_instance;
}
private function __construct() {
$this->navigationArray = array();
}
public function popin($popInElement){
array_push($this->navigationArray,$popInElement);
}
public function displayLinks()
{
//print array
}
}
In boostrap I did following
$nlinks=myApp_Helper_Breadcrum::getInstance();
Zend_Registry::set('nlinks',$nlinks);
Now in my controller I am calling as follow
$nlinks= Zend_Registry::get('nlinks');
$nlinks->popin('Home');
$nlinks->displayLinks();
The problem is, even if this class is singleton the constructor is called again and again which makes my array to initialize. what I am trying to achieve is to keep pushing the items in the navigation array as I navigate the site.
Any idea why it is like this in ZF?
PHP isn't running like Java would where you have a JVM to maintain the state of your classes. In Java you can have a singleton behave exactly as you describe, but in PHP all the classes are refreshed with each subsequent call to the web server. So your singleton will stay in place for the duration of that call to the server, but once the response is sent then you start over again on the next call.
If you want to maintain state through successive calls you need to use the $_SESSION to keep track of your state.
EDIT:
My answer above deals with PHP in general and not the Zend Framework specifically. See my comment below.
Try to define your component as below:
class MyApp_Helper_Breadcrum
{
private static $_instance = null; // use private here
public static function getInstance()
{
if (self::$_instance === null) { // use strictly equal to null
self::$_instance = new self();
}
return self::$_instance;
}
private function __construct() // use private here
{
// ...
}
// ...
}
I ran into the exact same problem.
The problem is that the persistence of your classes are on the request scope.
And with zend, you can even have multiple requests for a page load.
PHP is a shared nothing architecture; each
request starts in a new process, and at the end of the request, it's all
thrown away. Persisting across requests simply cannot happen -- unless
you do your own caching. You can serialize objects and restore them --
but pragmatically, in most cases you'll get very little benefit from
this (and often run into all sorts of issues, particularly when it comes
to resource handles).
You may want to use Zend_cache, for persistence
Even though this is old, I would like to add my 2 cent.
Zend DOES NOT create a singleton, that persists across multiple requests. Regardless of the interpretation of the ZF documentation, on each request, the whole stack is re-initialized.
This is where your problem comes from. Since bootstrapping is done on each request, each request also re-initializes your helper method. As far as I know, helpers in ZF 1.x CAN'T be singletons.
The only way I see this being implementes ar you want it to be, is using sessions.
After some debugging,I found "com.google.gwt.event.shared.UmbrellaException:One or
more exceptions caught, see full set in UmbrellaException#getCauses' when calling method: [nsIDOMEventListener::handleEvent]"(in web model) is caused by runtime null pointer.Question is why this kind of runtime null pointer exception didn't got thrown out under host model.Actually,blow code won't thrown out any exception and even got alert popup in my laptop(gwt 2.4+java 7 64bit+ubuntu 12.04 64bit+eclipse 3.7).Anybody knows how to enforce eclipse throw out exception whenever a runtime null on JavascriptObject pointer occurs.
public class GWTTest implements EntryPoint
{
public static class JsObj extends JavaScriptObject
{
protected JsObj()
{
}
public final native void setValue(String Value)/*-{
this.Value=Value;
alert(Value);
}-*/;
}
public void onModuleLoad()
{
JsObj jsObj = null;
jsObj.setValue("val");
}
}
The compiler performs a number of optimizations to transform GWT/Java into Javascript.
Types and methods are made final - this allows later steps to understand which methods need to be dispatched as normal, and which can be made static, just calling a single implementation.
Methods are made static, where possible, which allows methods to be inlined
Where possible and reasonable, methods are inlined
That said... When I compile your sample, the body of onModuleLoad() is optimized out to this:
null.nullMethod();
This is the GWT compiler's way of saying 'this will never work' - it notices that the value is always null, and so the method can't be invoked on it. But in Dev Mode, apparently the null object is left pointing at the window object in JavaScript. This is filed at http://code.google.com/p/google-web-toolkit/issues/detail?id=6625 in the GWT project.
If you need to make sure you don't act on a null, test for null before calling the method - it'll get optimized out if, in a test like yours, the value is always null. Runtime exceptions shouldn't be used for controlling code anyway, so you should never rely on a NullPointerException to do anything in your code.
I've try to expose to the client(gwt) an aspectJ method through gwt-rpc, but the gwt client can't find the method defined in an aspect. The class that i expose implements IsSerializable and only it's method are visible to the client interface...the method added by their aspect contrariwise no. How i can fix this? thanks in advice.
p.s. i post a little example for more clarity:
this is the class...
public class Example implements IsSerializable{
private String name;
public setName(String name){
this.name=name
}
}
and this is the aspect...
privileged aspect Example_x{
public int Example.getVersion() {
return this.version;
}
}
The Example.getVersion() method is unavailable on the client side.
TNX
This won't work, as GWT needs access to the source of any Java class that is exposed to the client side. This is necessary to compile them from Java to Javascript. If you modify your classes using AspectJ, the added methods will not be visible to the GWT compiler and therefore not to the client.
I'd say AspectJ is simply the wrong tool for this task. If you want to add some methods to existing classes you could write a (possibly generic) container class that contains an instance of Example as well as the version information from Example_x.
My GWT app has ten different kinds of entities. Right now I use plain old DTOs and transport them over GWT-RPC. This works well for cases like startup - I can pack them all into a single request.
I'm looking at switching to RequestFactory because there are many times throughout the lifetime of the app (30 minutes, on average) when I just have to update one type of entity, and the unifying/bandwidth-saving features of RequestFactory are appealing. BUT: I don't see a way to download all of my initialization data in a single request when the app loads. I don't want to have to make ten requests to fetch all of the init data for my ten entity types.
Is there a way to make a GeneralRequestContext, or something? I'd even be happy with a solution like:
public interface InitDataProxy extends EntityProxy
{
public UserProxy getInitUsers();
public OrganizationProxy getInitOrganizations();
...
}
public interface GeneralRequestContext extends RequestContext
{
Request<InitDataProxy> getInitData();
}
But this won't work because I don't want to have to actually back InitDataProxy with anything, I just want to use it to combine a bunch of different types of Proxies in a single request.
So: Is there a way to receive multiple, unrelated types of EntityProxy in a single request?
I would also be happy enough making a normal gwt-rpc request to go outside of RequestFactory for this data, but I don't want to have to implement duplicate DTOs to run next to RequestFactory's proxies, and write custom code to copy the DTOs into them!
The InitDataProxy could extend ValueProxy instead, which doesn't require that the object on the server have any kind of id or version semantics. The domain-side InitData type could be an interface, possibly implemented with an anonymous type.
interface InitData {
User getUser();
Organization getOrgatization();
}
class InitService {
static InitData makeInitData() {
return new InitData() { ..... };
}
}
#ProxyFor(InitData.class)
interface InitDataProxy extends ValueProxy {
UserProxy getUser();
OrganizationProxy getOrganization();
}
#Service(InitService.class)
interface Init extends RequestContext {
Request<InitDataProxy> makeInitData();
}