I am using SimpleIOC from mvvm-light along with the ViewModelLocator class / pattern provided to provide ViewModels with the correct dependencies injected. The problem I have is that the dependency that is being injected in to my ViewModel is a WCF ClientBase instance that can "break" if it encounters a fault. One example would be if the service it is trying to connect to doesn't exist it will cause a fault. I don't know how to handle this properly. Once the ClientBase derived class is in a fault state it will no longer work. The ViewModelLocator keeps injecting this broken instance of my service proxy so even if this service becomes accessible the proxy will error out when used because it can't recover from a faulted state. How should I deal with this?
I was able to figure this one out on my own. The answer was to create a wrapper around the ClientBase proxy class so that when a call created a fault, the wrapper class could properly handle the exception yet still be ready to handle the next call.
Related
I found that Quarkus Server binds io.quarkus.grpc.runtime.supports.blocking.BlockingServerInterceptor for each gRPC service with the #Blocking annotation before it starts.
If some global interceptors (with #GlobalInterceptor) set the Context value will not work. The Context will still be empty in the actual rpc method handler.
Is it a normal phenomenon because Context should be placed after BlockingServerInterceptor's vert.x executeBlocking? There are some associated issues: https://github.com/quarkusio/quarkus/issues/14665, https://github.com/quarkusio/quarkus/issues/13959.
Finaly I replace the #GlobalInterceptor with #RegisterInterceptor(MyInterceptor.class) , everything is to be ok that seems to prove my point.
I don't particularly understand the technical details of it, and these are what I got from trying and Debug. I've been using Spring and Micronaut before.
In a console application I'm using masstransit to process messages coming from a rabbitMQ queue. Every message deals with a specific customer and contains a customterId (this could be in header or message, tbd).
I'm using standard Microsoft Dependency Injection and I have several services I wish to be scoped to this customer.
I can use IServiceProvider.CreateScope in the masstransit consumer. But I cannot seem to determine the proper way to set a specific "value" to a scope. Something that every scoped service provided can use to determine the customer for which the scope was defined. Something that the scoped service can use to determine the "context"
My feeling is that I am looking to define something like HttpContext (This off course is not available in console application).
Do I have to do this manually by setting properties on a scoped service on which all other (scoped) services have a dependency? That feels not very thread safe to me (what if a service is instantiated in a scope before I can set the customer property?).
I know this is a little open for a question here, yet maybe someone can still provide an answer?
I would provide code, but this more an architectural question and on internal the workings of MSDI.
MassTransit creates a scope for every consumer, so creating another scope is a bad idea. Any scoped dependencies will be resolved through the consumer's constructor automatically by the container.
This is a more general Spring question that isn't necessarily a Spring Social Facebook issue; however, I'm asking the question here because it is not clear to me how Spring is managing the Facebook reference that is passed into the controller constructor.
I'm running this in a Spring boot app, version 1.5.3.RELEASE.
I've googled around and have read many things about how scoped-proxies work and whether the Controller is a singleton and such; but something is still not clear to me with this particular use case. My concern is over whether or not two or more simultaneous request will cause one reference to interfere with the other. It seems to me that there will be a conflict regardless of the scoped-proxy solution. To address this concern, I injected a Facebook and ConnectionRepository object into the controller constructor wrapped in a Provider class.
#Inject
public CopyGroupController(
Provider<Facebook> facebook,
Provider<ConnectionRepository> connectionRepository) {
It appears to have injected meaningful data; but when attempting to run this code:
#PostConstruct
public void init() {
ConnectionRepository repo = connectionRepository.get();
this.userManager.createOrGetUser(
repo.findPrimaryConnection(Facebook.class));
}
This failure occurs:
java.lang.IllegalStateException: No thread-bound request found: Are you referring to request attributes outside of an actual web request, or processing a request outside of the originally receiving thread? If you are actually operating within a web request and still receive this message, your code is probably running outside of DispatcherServlet/DispatcherPortlet: In this case, use RequestContextListener or RequestContextFilter to expose the current request.
This creates more uncertainty because I thought the FacebookTemplate was being managed as a request or session scoped bean and that it would Inject as a Provider so the object would reside on ThreadLocale; so two or more concurrent requests will not conflict. Passing a request scoped bean in a controller singleton constructor doesn't make any sense to me either. So I'm puzzled as to why a user specific reference would even be passed into a constructor that should only be called once.
I've tried setting breakpoints in the constructor to verify whether or not there is a conflict; but The same error as above would occur. Could someone please explain to me whether or not this is an issue and if so; how is the best, most modern way to resolve it.
Any assistance would be greatly appreciated.
Thank you in advance.
You have to register a RequestContextListener
Here you can find the problem detail
And here you can get how to add in using spring boot
I want to know what will happen when there are no ejbs available in the pool and a client is trying to access a web service which uses the ejb.
We are receiving a NPE at the line where the ejb instance is used to call a method. Unfortunately I do not have access to the logs right now and I am trying to figure out what is wrong. So I am thinking in all possible ways and this question spawned in my head.
Can anyone please tell me?
What I think is, the web service will not be initialized until an ejb instance is available in the pool. So In this case the request will be queued and after sometime the client will receive a timeout error or appropriate message. Am I right?
P.S
BTW, if it makes any difference, I am injecting the ejb using #EJB annotation.
If you use a reference to a SLSB the initialization is just a proxy, no instance is needed.
At runtime the invocation try to get an instance from the pool, if there are all instances busy it will be blocked for a while (5sec by default) and throw an Exception in case of timeout, otherwise just continue.
If you get a NPE this seems to me a different issue where you can't get a reference.
A stateful bean is different, but I think you don't use that.
I think it should be the same no matter which container you use.
I have a class library project which i am referencing in my asp.net web forms project.
Whenever any exception happens, i want to log it. But, I am not doing any exception handling in any of the class library method. That is i have not used try-cath block in any of the methods in the class library.
Because, any excepyion that gets thrown from class library methods is caught in my presentation layer/business layer(wherever i call the functions of the class library) and proper logging is done here in the web forms project.
Is it correct to do this way.?
Its Ok to write that way, but in that case your Class Library will throw exception which system exception message, which might be sometime difficult to interpret and act accordingly.
Instead you can have Try-Catch-Finally block in class library, and Re-throw exception with user defined message to calling method, this will help in tracing issue.
Example :
Catch(FileNotFoundException Ex)
{
throw new ("File Not Found at XYZ Location, Please Check File Exist and retry ...")
}
Centralized Exception Logging:
There are multiple ways you can log error messages. One of the good way would be to use Enterprise Library Exception Block to Log error to file, which can be used in debugging issues.
This article can come handy for Enterprise Library:
http://msdn.microsoft.com/en-us/library/ff649140.aspx
You can log exception centrally to CSV, XML or even to windows Event Viewer.
Create Separate class / project to perform all exception logging in project.
Seems like a reasonable approach to me. Delegating the exception logging to the application keeps your class library abstract meaning it can be reused without having a dependency on the logging library/framework.
Logging should be the responsibility of the application, not the component. There may be some exceptional circumstances where trace-level debugging is required at component level, for those special cases having a log-enabled version of the lib that you could swap in might come in handy. However, I would argue that a properly tested component would reduce the need for that.