I'm working on a GWT project and I find it very tedious to have to add a function to my servlet, then copy and paste the function signature into my Service interface, then copy and paste it into my ServiceAsync interface and change the return parameter to be a callback. Is there a tool or a setting where I can just add public methods to my class and they can get copied into the other interfaces? Even if its not automatic it would be nice to be able to select specific methods and have them copied automatically.
I'm using eclipse and ideally it would update my interface each time I save implementation since thats when it checks my code and complains that my changes break the interface.
If you add the method to your *Service interface, then Eclipse can auto-generate the method ("Add unimplemented methods...") in your *ServiceImpl servlet, which you can then just fill in. Also, if you've got the Google Eclipse plugin installed, it will underline the new method in your *Service interface and complain that it's not in the *ServiceAsync. It might have a CTRL + 1 option to generate it in that interface as well.
You don't really need a tool. Just factor out the many RPC methods by just one method that takes a Request/Response. all you need to do is create subclasses of Request/Response and you don't need to think about adding new methods in the 2 interfaces.
You can use Google Guice on the server side to map the incomming request to a class handling the call... or you could use a visitor approach to forward the incoming request to the code handling the request (without resorting on a big instanceof construct).
Instantiations WindowBuilder GWT Designer does exactly what you are looking for.
The RemoteService Wizard will create all three files at the same time as well as keep them in sync as you make changes.
http://www.instantiations.com/windowbuilder/gwtdesigner/index.html
FWIW - I am only a user/purchaser of this product. I am not employed or in any other way related to Instantiations.
Related
I try to create the entity like this:
DatastoreService ds = DatastoreServiceFactory.getDatastoreService();
Entity stock = new Entity("Stock", 1);
stock.setProperty("Stock", "FCB");
ds.put(stock);
but keep getting the error:
No source code is available for type com.google.appengine.api.datastore.DatastoreService; did you forget to inherit a required module?
The error means just what it says, the GWT compiler needs access to the Java source it compiles to Javascript, and obviously DatastoreService is not something that should exist on the frontend - so you have an architecture issue here.
You'll need to write a proxy that can call a server component (Which in turns calls the DatastoreService) and returns DTOs/value objects (that you define and thus have the source for).
Cheers,
No source code is available
GWT transliterate Java to Javascript, reading it's source code and there a limited language support.
What you're trying to achieve is a Server only operation and you're adding this operation within the client code, which will run on a browser. Neither GAE allow this or GWT has the source of these classes nor capability to do so.
Solution
You need to create a request to your server that will access the DatastoreService , the return the output to the client code.
Below a example of a properly architect GWT web application:
I have an Eclipse RAP 2.3 application with two entry points, say /first and /second.
In the GUI of the first entry point, there is a button with which I would like to open the second entry point in a new browser tab. The event handler of that button is currently
UrlLauncher launcher = RWT.getClient().getService( UrlLauncher.class );
launcher.openURL( "/second");
This already doesn't work when the application is deployed as myapp.war in a Tomcat web server (should then be /myapp/second).
My questions:
What's the best way to determine the URL to open within the event handler?
Do I have to fetch the HttpServletRequest, get the context path and so some string manipulation?
Is it actually safe to call RWT.getRequest() at this point?
Update
According to Rüdiger's comment I can acquire the context path in two different ways.
The first approach is
RWT.getRequest().getContextPath();
where RWT.getRequest() is documented with
This method is not recommended
Secondly, I could obtain it with
ApplicationContextImpl ac = (ApplicationContextImpl) RWT.getApplicationContext();
String contextPath = ac.getServletContext().getContextPath();
where the IDE displays the warning
Discouraged access: The type ApplicationContextImpl is not accessible due to restriction on required library ...\org.eclipse.rap.rwt_2.3.2.20150128-1013.jar
Despite the warning, it still works when deploying a WAR file with OSGi bundles to Tomcat.
So, in both cases there is some kind of warning, which makes the solutions look rather like workarounds.
Using RWT.getRequest() is not recommended because usually RWT would shield you from the lower-level servlet API and certain direct interactions with the request could even interfere with RWTs life cycle and yield funny responses.
While in your case it would be safe to access the ServletContext via RWT.getRequest(), I recommend to use
RWT.getUISession( display ).getHttpSession().getServletContext();
to access the servlet context.
The second approach accesses internal classes that aren't part of the public API and therefore shouldn't be use. The accessed classes may change or be (re)moved in the future without further notice and break your application.
I'm using ASP.Net MVC 4 RTM Web API. I have a controller action with a parameter that I'd like to populate via custom model binding. To achieve this, I created a class that derives from System.Web.Http.Controllers.HttpParameterBinding that sets the value of this parameter. I then created an attribute class that derives from System.Web.Http.ParameterBindingAttribute which I use to decorate the parameter on my controller action.
This is all working great, my HttpParameterBinding class is populating the action parameter correctly. The problem I have is that my custom parameter binding class has a dependency that I'd like resolved via my IoC container (Unity). Is there a way to override how Web API creates HttpParameterBinding instances so that I can build up my custom binding class dependency from Unity? I was able to do something similar for a filter attribute by creating a custom filter provider that uses Unity's BuildUp method to populate dependencies, however I'm not seeing anything similar for Web API's HttpParameterBindings.
In general: to use IoC / Unity in the Web API you need to set it up seperately.
Try downloading the nuget package Unity.WebApi and see if that helps!
Take a look at this article: Parameter Binding in WebAPI
It walks through a couple different options from Converters to Binders to BinderProviders. It sounds like you may be able to write a custom ModelBinderProvider which knows how to provide your dependency. If that isn't high enough in the chain you can look at replacing the default IActionValueBinder service. It's a DefaultActionValueBinder instance, which you can extend or simply re-implement.
I also highly recommend downloading the WebAPI source code, as it's been an incredible help for these issues as I've run into them. Here's the WebAPI source code. I recommend downloading it so you can open it in VS for easy navigation.
Feel free to check out FlitBit too (It's very modular, don't let the number of packages scare you off)! I'm working on a WebAPI package for supporting FlitBit, specifically FlitBit.IoC and FlitBit.Dto. I'll add an update if I work out my IoC issue, since it's very similar to yours.
I am able to Mole WebRequest.CreateUri so that I can replace the hostname of the request with another. However, I would like to Mole Dns.GetAddrInfo instead so that I can keep the hostname the same, but make it so that the hostname resolves to another IP address.
In this way, I do not have to edit my hosts file for example as this is a less flexible approach.
Any advice?
Thank you.
Edit
I've uploaded a sample Visual Studio 2010 sln to the problem here:
When opening the sln,
Click on the "Create Virtual Directory" button in the Service project properties' Web tab.
Rebuild the solution
Add the following entry to c:\windows\system32\drivers\etc\hosts:
127.0.0.1 www.productionserver.com
Run the TestMethod1 unit test in the Tests project.
The unit tests should succeed.
Remove the entry from the hosts file and re-run the unit test.
It should fail.
I have looked at the implementation of System.ServiceModel.ClientBase<TChannel> using a decompiler and noticed that it eventually calls System.Net.Dns.GetAddrInfo to resolve the hostname to an IP address.
I am hoping this sln is simple enough to update and send back (or just comment what needs to be done and\or changed) so I can simply see what is required to solve the problem.
Thank you.
Edit 2
It seems this is not currently possible with Moles.
The System.Net stack generally can not be moled, as much of he functionality are outside the control of the managed code.
Instead, create an interface and stub in your production code. Use the interface with dependency injection, to pass the stub to the target code. This stub simply calls the System.Net methods you wish to intercept, during testing.
Moles will automatically generate a Stub type, from the interface. Simply instantiate the stub type, detour the desired methods/properties/events of the stub, and then pass the Stub type to the method being tested.
Using stubs and dependency injection works wherever Mole types can not be created.
I'm learning GWT and have started to get the hang of it. I'm at the point where my code is getting to be a spaghetti mess so I'm going back and factoring reasonable bits of it out as Composites. The first problem I ran into was that my tool support failed to give the new Composite class an initWidget() method. It did include a default constructor.
For the time being, I've simply filled in my overridden initWidget() method with a call to super(initWidget(w)) My project compiles and runs as expected, though I feel as though I must be missing something.
What should I keep in mind when overriding init and what if anything do i need to place in the constructor. Is there anything else that I need to know or does it just boil down to regular old Java after this?
Clarification - It has occurred to me that there are probably different answers to this question depending on whether you intend to release said Composite classes as part of a library or simply part of your stand-alone app. I in particular have no intention at this time of developing externally useful components (mainly because I'm so green in this particular technology.)
Thanks!
I'm not sure if I understand what you are trying to do. But for all the Composite's I've written I've never overridden the initWidget method. Because Composite itself doesn't need to be initialized with a constructor, i.e. no need to call super() my constructors of widgets extending composite look something like:
public mywidget() {
SomePanel p = new SomePanel();
....
initWidget(p);
}
As a best practice, imo, only the widget extending Composite should call it's 'own' initWidget.
"GWT Conference: Best Practices for Building Libraries" gives a couple of tips. You should also look at the source of GWT and at the source of one of the libraries for GWT (like gwt-ext)
[EDIT] I just saw another option: suco. From the description:
A micro library that helps to maintain your GWT client code clean and modular.