I have my service declared this way:
public interface BlogQueryService extends Service {
public ServiceCall<String, Source<String, ?>> tick(int interval);
public ServiceCall<String, Source<String, ?>> tock();
public ServiceCall<NotUsed, Source<PostSummary, ?>> newPosts();
public ServiceCall<String, Source<PostSummary, ?>> getPostSummaries();
@Override
default Descriptor descriptor() {
return named("blog-query").with(
//pathCall("/api/bloggie/tick/:interval", this::tick),
pathCall("/api/bloggie/tock", tock())
//pathCall("/api/bloggie/newPosts", this::newPosts),
//pathCall("/api/bloggie/postSummaries", this::getPostSummaries)
).withAutoAcl(true);
}
}
The tick works. The tock doesn't.
When I invoke it using websocket client (to ws://localhost:9000/api/bloggie/tock ) , I got "undefined" as response, indicating no mapping found for that URL.
After some experimentings, found out why: tick works because it has url param (the :interval). Tick doesn't work because it doesn't have url param. Seriously pathCall requires you to have param in your URL? So I checked the API of Service: http://www.lagomframework.com/documentation/1.0.x/api/java/com/lightbend/lagom/javadsl/api/Service.html
There are several overloaded declarations of pathCall. Apparently the tick uses this one:
static <Request,Response,A> Descriptor.Call<Request,Response> pathCall(String pathPattern, akka.japi.function.Function<A,ServiceCall<Request,Response>> methodRef)
So from the signature, yes it requires the method to take a parameter. So, if the method (such is tock) doesn't take a param, the binding will fail at runtime. So I guess I need to use this one instead:
static <Request,Response> Descriptor.Call<Request,Response> pathCall(String pathPattern, akka.japi.function.Creator<ServiceCall<Request,Response>> methodRef)
The problem is... I don't know how. I haven't seen any example of the use of akka.japi.function.Creator in pathCall.
I tried this:
default Descriptor descriptor() {
return named("blog-query").with(
pathCall("/api/bloggie/tick/:interval", this::tick),
pathCall("/api/bloggie/tock", new Creator<ServiceCall<String, Source<String, ?>>> () {
public ServiceCall<String, Source<String, ?>> create() {
return tock();
}
})
//pathCall("/api/bloggie/newPosts", this::newPosts),
//pathCall("/api/bloggie/postSummaries", this::getPostSummaries)
).withAutoAcl(true);
}
It compiles. But it throws an error at runtime:
com.google.inject.CreationException: Unable to create injector, see the following errors:
1) Error in custom provider, java.lang.IllegalStateException: Unable to resolve method for service call with ID PathCallId{pathPattern='/api/bloggie/tock'}. Ensure that the you have passed a method reference (ie, this::someMethod). Passing anything else, for example lambdas, anonymous classes or actual implementation classes, is forbidden in declaring a service descriptor.
at com.lightbend.lagom.javadsl.server.ServiceGuiceSupport.bindServices(ServiceGuiceSupport.java:43) (via modules: com.google.inject.util.Modules$OverrideModule -> sample.bloggie.impl.BlogServiceModule)
while locating com.lightbend.lagom.internal.server.ResolvedServices
Thanks in advance!
I just did some experiments... All compiled, but none of them works....
namedCall("/api/bloggie/tock", this::tock)
Result: Compile success. Runtime: path unknown (no binding (?)).
Then I tried
pathCall("/api/bloggie/tock", () -> this.tock())
Result: exception.
com.google.inject.CreationException: Unable to create injector, see the following errors:
1) Error in custom provider, scala.MatchError: Request (of class sun.reflect.generics.reflectiveObjects.TypeVariableImpl)
at com.lightbend.lagom.javadsl.server.ServiceGuiceSupport.bindServices(ServiceGuiceSupport.java:43) (via modules: com.google.inject.util.Modules$OverrideModule -> sample.bloggie.impl.BlogServiceModule)
while locating com.lightbend.lagom.internal.server.ResolvedServices
for parameter 1 at com.lightbend.lagom.internal.server.ServiceRegistrationModule$RegisterWithServiceRegistry.<init>(ServiceRegistrationModule.scala:55)
at com.lightbend.lagom.internal.server.ServiceRegistrationModule.bindings(ServiceRegistrationModule.scala:29):
Binding(class com.lightbend.lagom.internal.server.ServiceRegistrationModule$RegisterWithServiceRegistry to self eagerly) (via modules: com.google.inject.util.Modules$OverrideModule -> play.api.inject.guice.GuiceableModuleConversions$$anon$1)
while locating com.lightbend.lagom.internal.server.ServiceRegistrationModule$RegisterWithServiceRegistry
Then I tried:
public ServiceCall<NotUsed, Source<String, ?>> tock(Void x);
Result: exception
com.google.inject.CreationException: Unable to create injector, see the following errors:
1) Error in custom provider, java.lang.IllegalArgumentException: Don't know how to serialize ID class java.lang.Void
at com.lightbend.lagom.javadsl.server.ServiceGuiceSupport.bindServices(ServiceGuiceSupport.java:43) (via modules: com.google.inject.util.Modules$OverrideModule -> sample.bloggie.impl.BlogServiceModule)
Update: "Solved" (partially). Figured out that this one works:
pathCall("/tock", this::tock)
I can open it using this URL: ws://localhost:9000/tock
So..., I can't have nicely structured URL for those functions that returns stream, when those functions need no param? At least for now (?).
UPDATE: seems like this problem is happening not only with pathCall. I encountered the same problem with rest call. This one doesn't work (no binding):
public ServiceCall<NotUsed, PSequence<PostSummary>> getPostSummaries();
...
restCall(Method.GET, "/api/bloggie/postSummaries", this::getPostSummaries)
This one works:
public ServiceCall<NotUsed, PSequence<PostSummary>> getPostSummaries();
...
restCall(Method.GET, "/postSummaries", this::getPostSummaries)
Thanks!
