GWT Async generation, turn off in some cases? - gwt

When using gwt-maven-plugin's generateAsync, is it possible to apply an annotation (or something) to an individual gwt-rpc service so that the corresponding async isn't auto-generated and can be written manually?
Alternatively, is there an annotation (or something) that makes the generated asyncs have the "Request" return type?

From the gwt-maven-plugin's documentation you need to adjust the servicePattern configuration property, or you can ask it to always generate methods returning Request.
Or, even better, don't use this goal!
(or only call it manually once in a while and copy the generated classes to your sources)

The GWT Generators will never create a class if one already exists with that name. This means you can ask GWT to compile and generate the code, then copy the classes into your sources and customize them, and later compiler runs will not attempt to generate sources.
This may have other side effects - if the proxy, typeserializer, or fieldserializer is prevented from being generated, then the RPC generators may assume that other dependencies have also all been correctly generated, so you may find yourself missing classes if you don't also copy those other classes. Likewise, of course any changes that require your serializers being modified or rebuilt will have to be done manually, such as changing a serializable type, or modifying a RPC method.
Your async interface can always declare a return type of Request or RequestBuilder instead of void. If you declare RequestBuilder, then the request will not be sent automatically, and you must call send(), whereas a Request returned means that the request has been sent.

Related

Microprofile Config: Dynamic ConfigSource values for faulttolerance metric tags

i'm currently working on a solution to setting metric tags for the microprofile fault-tolerance framework. We're using it together with metrics, but one cannot directly set tags via the fault-tolerance annotations.
So we came up with a workaround setting a ThreadLocal value via an Interceptor, which then is read by a custom ConfigSource. The ConfigSource checks for "mp.metrics.tags" and "MP_METRICS_TAGS" config keys in it's getValue(final String propertyName) method. This would basically work if the getValue would get called every time a fault-tolerance annotation is processed. But is seems like this is not the case and the invocations of the method happen randomly.
In my oppinion ConfigSources and their getValue(final String propertyName) should always get called as a developer might rely on config values which could change every second.
Any ideas why the config source is not called?
It looks like the custom ConfigSource does no longer get called when returning null multiple times or at least during the server startup phase. In the mentioned scenario this can be bypassed by returning an empty string. Then the ConfigSource also gets called for every getValue() method call at runtime.
The MicroProfile Config 1.4 specification indicates that no caching of a ConfigSource's value should occur, so if your MicroProfile Config Config implementation (you don't say which implementation it is) is caching the results of a call to ConfigSource#getValue() it is not compliant, as best as I can tell (the specification is flawed, not very rigorous, and its TCK is spotty but it certainly seems to be pretty clear on this issue).
(Do note that a given ConfigSource implementation may, of course, decide to return cached values from its getValue() method.)

What is the difference between BasicHttpRequest and HttpGet, HttpPost, etc in Apache HTTP Client 4.3 ?

I am creating HTTP request using Apache HTTP Client version 4.3.4. I see there are some classes like HttpGet,... and there is also a class BasicHttpRequest. I am not sure which one to use.
Whats the difference and which one should be used in which condition ?
BasicHttpRequest is provided by the core library. As its name suggests it is pretty basic: it enforces no particular method name or type, nor does it attempt to validate the request URI. The URI parameter can be any arbitrary garbage. HttpClient will dutifully transmit it to server as is, if it is unable to parse it to a valid URI.
HttpUriRequest variety on the other hand will enforce specific method type and will require a valid URI. Another important feature is that HttpUriRequest can be aborted at any point of their execution.
You should always be using classes that implement HttpUriRequest per default.
I was just browsing the 4.3.6 javadoc attempting to locate your BasicHttpRequest and was unable to find it. Do you have a reference to the javadoc of this class?
I would be under the impression that BasicHttpRequest would be a base class providing operations and attributes common to more than one HttpRequest. It may be extremely generic for extension purposes.
To the first part of your question, use HttpGet, HttpPost etc for their specific operations. If you only need to HTTP/GET information then use HttpGet, if you need to post a form or document body, then use HttpPost. If you are attempting to use things like the Head, Put, Delete method, then use the correspoding HttpXXX class.

Http DELETE with parameters using Jersey

I have code that contains several different DELETE methods, one of which takes a parameter, or at least ideally it would take a parameter. However when I make this request, either through CURL or through a web client, it doesn't work. The other DELETE requests function fine and I've hard-coded in the parameter that I want to pass just to see if the call works and it does. I've tried this with both PathParam and QueryParam and neither works. Here's how I'm using the PathParams, which I'm pretty sure is correct, QueryParams looks very similar so I don't want to post that too.
#DELETE
#Path("/byId/{id}")
public void deleteById(#PathParam("id") String id)
And then essentially the same thing for QueryParams but obviously the path is different
From what I understand a lot of RESTful APIs ignore any kind of request body with a DELETE request, or treat it as a PUT or POST. Is there any way around this? Basically I have a database that contains several objects and I need to delete one based on a unique identifier, to be passed in by the client. If there is no way around this is there some other way that I could do it?
Its possible that I'm missing something obvious here as I've only been using Jersey for a few weeks now and up to this point had never even heard of the concept of RESTful services.
You can send information to a RESTful service as either headers, path param, query param or message body.
If all the values go through as expected there is no problem with jax-rs/jersey. Now you need to debug the code and fix your implementation. jax-rs will only match a DELETE call with the DELETE http method you have implemented.
It is then your responsibility to actually perform a DELETE operation of the resource within the method. jax-rs or jersey is not going to complain if you do not DELETE or if you do some other action within the method.

xtext check annotation issue

I'm using the #Check annotation in order to validate my dsl. my dsl is for json.
at first the method was invoked for a specific object and once per change
but it suddenly doesn't work in the same way anymore (and i'm not sure what i've done that effected it)
the method signature is:
#Check
public void validateJson(ObjectValue object) {...}
now its entering this method for each node in the gui although i'm editing only one node
The validator works normally in this case. When Xtext re-parses your model, it cannot always avoid re-creating the EMF model that is validated in the Check expression - in other words, the model is practically re-created every time, thus warranting a full validation.
However, in some cases, it is possible that only a partial re-creation of the model is necessary - in these cases it is possible that not all elements are re-validated (however, I am not sure whether this optimization was included).

JAX-RS and unknown query parameters

I have a Java client that calls a RESTEasy (JAX-RS) Java server. It is possible that some of my users may have a newer version of the client than the server.
That client may call a resource on the server that contains query parameters that the server does not know about. Is it possible to detect this on the server side and return an error?
I understand that if the client calls a URL that has not been implemented yet on the server, the client will get a 404 error, but what happens if the client passes in a query parameter that is not implemented (e.g.: ?sort_by=last_name)?
Is it possible to detect this on the server side and return an error?
Yes, you can do it. I think the easiest way is to use #Context UriInfo. You can obtain all query parameters by calling getQueryParameters() method. So you know if there are any unknown parameters and you can return error.
but what happens if the client passes in a query parameter that is not implemented
If you implement no special support of handling "unknown" parameters, the resource will be called and the parameter will be silently ignored.
Personally I think that it's better to ignore the unknown parameters. If you just ignore them, it may help to make the API backward compatible.
You should definitely check out the JAX-RS filters (org.apache.cxf.jaxrs.ext.RequestHandler) to intercept, validate, manipulate request, e.g. for security or validatng query parameters.
If you declared all your parameters using annotations you can parse the web.xml file for the resource class names (see possible regex below) and use the full qualified class names to access the declared annotations for methods (like javax.ws.rs.GET) and method parameters (like javax.ws.rs.QueryParam) to scan all available web service resources - this way you don't have to manually add all resource classes to your filter.
Store this information in static variables so you just have to parse this stuff the first time you hit your filter.
In your filter you can access the org.apache.cxf.message.Message for the incoming request. The query string is easy to access - if you also want to validate form parameters and multipart names, you have to reas the message content and write it back to the message (this gets a bit nasty since you have to deal with multipart boundaries etc).
To 'index' the resources I just take the HTTP method and append the path (which is then used as key to access the declared parameters.
You can use the ServletContext to read the web.xml file. For extracting the resource classes this regex might be helpful
String webxml = readInputStreamAsString(context.getResourceAsStream("WEB-INF/web.xml"));
Pattern serviceClassesPattern = Pattern.compile("<param-name>jaxrs.serviceClasses</param-name>.*?<param-value>(.*?)</param-value>", Pattern.DOTALL | Pattern.MULTILINE);