I am looking into Microsoft Orleans. I have setup a cluster in docker, tt is working perfectly. I am trying to read the documentation on message delivery, but I can't seem to find anything on retry. If I have a grain calling a grain, like this:
public class HelloGrain : Orleans.Grain, IHello
{
private readonly ILogger logger;
private IOtherGrain otherGrain;
public HelloGrain(ILogger<HelloGrain> logger)
{
this.logger = logger;
}
public override async Task OnActivateAsync()
{
otherGrain = GrainFactory.GetGrain(this.GetPrimaryKeyString());
await base.OnActivateAsync();
}
Task<string> IHello.SayHello(string greeting)
{
string otherGrainReturn = await this.otherGrain.MethodAsync();
return Task.FromResult($"\n Client said: '{greeting}', so HelloGrain says: Hello!");
}
}
Is the string otherGrainReturn = await this.otherGrain.MethodAsync(); getting retried, on failure, somehow? Is it only a timeout that decide when the call fails? Is this to be handled as a basic HTTP call, and should i therefore be retrying myself?
It could be awesome with som link to documentation that say something more on the subject (at-least-once retry etc).
You can see here that by design, Orleans doesn't have any kind of retry policy.
But you can add it by yourself with a simple try catch block (Or with a specific library like Polly).
Related
I am very new with orleans and trying to grasp everything with grains and so forth.
What i got is that in my startup.cs file i add the SignalR like this
public IServiceProvider ConfigureServices(IServiceCollection services)
{
Program.WriteConsole("Adding singletons");
services
.AddSingleton(achievementManager)
.AddMvc();
services.AddSingleton(SignalRClient);
return services.BuildServiceProvider();
}
So far everything is fine i can start my host/application and it connects to SignalR as it should. But what i cant wrap my head around is how do i get this down to my grain? if i had a controller i would simply send it down in the constructor on startup but how do i do this with a grain? Or can i even do it like this. Any guidance is appreciated.
In the grain then i want to do something like this
[StatelessWorker]
[Reentrant]
public class NotifierGrain : Grain, INotifierGrain
{
private HubConnection SignalRClient { get; }
public NotifierGrain(HubConnection signalRClient)
{
SignalRClient = signalRClient;
SignalRClient.SendAsync(Methods.RegisterService, Constants.ServiceName);
}
public Task NotifyClients(object message, MessageType type)
{
var registerUserNotification = (RegisterUserNotificationModel)message;
SignalRClient.SendAsync(Methods.RegisterUserToMultipleGroups, registerUserNotification.UserId, registerUserNotification.InfoIds);
}
return Task.CompletedTask;
}
Then i try to call the Notify method from another grain like this
var notifier = GrainFactory.GetGrain<INotifierGrain>(Constants.NotifierGrain);
await notifier.NotifyClients(notification, MessageType.RegisterUser);
But trying to do this ends up with an error like this
InvalidOperationException: Unable to resolve service for type 'Microsoft.AspNetCore.SignalR.Client.HubConnection' while attempting to activate 'User.Implementation.Grains.NotifierGrain'.
Orleans supports constructor injection, so you can inject the SignalRClient into your grain constructor. In your code you are already correctly registering the client using services.AddSingleton(SignalRClient), so I will focus on how to inject the type into your grain.
I do not know what the type the SignalR client object is, but in this example I assume that the type is "SignalRClient":
[StatelessWorker]
[Reentrant]
public class NotifierGrain : Grain, INotifierGrain
{
private readonly SignalRClient signalRClient;
public NotifierGrain(SignalRClient signalRClient)
{
this.signalRClient = signalRClient;
}
public async Task NotifyClients(object message, MessageType type)
{
var registerUserNotification = (RegisterUserNotificationModel)message;
await this.signalRClient.SendAsync(
MessageMethods.RegisterUserToMultipleGroups,
registerUserNotification.UserId,
registerUserNotification.infoIds);
}
}
Depends how you're thinking to use SignalR Server, if you're going to host your SignalR server with Microsoft Orleans for sure you need to have backplane to handle the Orleans cluster communications.
You can use SignalR Orleans which has everything done out of the box for you :)
Also if you need a reactive SignalR library for the frontend, you can use Sketch7 SignalR Client
PS I m one of the authors of both libraries.
With WebJobs 3.0, they propose to use the Dependency Injection via ConfigureServices()
However, the services added with AddScoped() are behaving the exact same way as AddSingleton(): they are configured for the lifetime of the WebJob. I would prefer to have it scoped per function call. How can we achieve this?
I tried to use my custom job activator and do something like this:
public T CreateInstance<T>()
{
using (var scope = _service.CreateScope())
{
var service = scope.ServiceProvider.GetService<T>();
return service;
}
}
However, this gives me the following error:
The operation cannot be completed because the DbContext has been disposed.
The initialization is disposed before any call is made. I can't find how to connect this scoping mechanism properly.
The goal is to do have scoped dependency per function. At the moment, this is the only work around found to fix this issue.
public async Task SendEmail(
[QueueTrigger("%AzureStorage:Queue:SendEmail%")] int emailId,
ILogger logger
)
{
// Ugly workaround that I have to insert in all my functions.
using (var scope = serviceProvider.CreateScope())
using (var myService = scope.ServiceProvider.GetService<IMyService>())
{
await myService.SendEmailAsync(emailId);
}
}
I'm publishing messages into RabbitMQ and I would like to track the errors when RabbitMQ is down, for this I added one RetryTemplate with the recovery callback, but the recovery callback only provides this method getLastThrowable() and I'm not sure how to provide the details of the messages that failed when RabbitMQ is down. (as per documentation "The RecoveryCallback is somewhat limited in that the retry context only contains the
lastThrowable field. For more sophisticated use cases, you should use an external
RetryTemplate so that you can convey additional information to the RecoveryCallback via
the context’s attributes") but I don't know how to do that, if anyone could help me with one example that will be awesome.
Rabbit Template
public RabbitTemplate rabbitMqTemplate(RecoveryCallback publisherRecoveryCallback) {
RabbitTemplate r = new RabbitTemplate(rabbitConnectionFactory);
r.setExchange(exchangeName);
r.setRoutingKey(routingKey);
r.setConnectionFactory(rabbitConnectionFactory);
r.setMessageConverter(jsonMessageConverter());
RetryTemplate retryTemplate = new RetryTemplate();
ExponentialBackOffPolicy backOffPolicy = new ExponentialBackOffPolicy();
backOffPolicy.setInitialInterval(500);
backOffPolicy.setMultiplier(10.0);
backOffPolicy.setMaxInterval(10000);
retryTemplate.setBackOffPolicy(backOffPolicy);
r.setRetryTemplate(retryTemplate);
r.setRecoveryCallback(publisherRecoveryCallback);
return r;
}
Recovery Callback
#Component
public class PublisherRecoveryCallback implements RecoveryCallback<AssortmentEvent> {
#Override
public AssortmentEvent recover(RetryContext context) throws Exception {
log.error("Error publising event",context.getLastThrowable());
//how to get message details here??
return null;
}
}
AMQP Outbound Adapter
return IntegrationFlows.from("eventsChannel")
.split()
.handle(Amqp.outboundAdapter(rabbitMqTemplate)
.exchangeName(exchangeName)
.confirmCorrelationExpression("payload")
.confirmAckChannel(ackChannel)
.confirmNackChannel(nackChannel)
)
.get();
The isn't possible because the function RabbitTemplate.execute() is already not aware about message you send, because it may be performed from any other method, where we might not have messages to deal:
return this.retryTemplate.execute(
(RetryCallback<T, Exception>) context -> RabbitTemplate.this.doExecute(action, connectionFactory),
(RecoveryCallback<T>) this.recoveryCallback);
What I suggest you to do is like storing message to the ThreadLocal before send and get it from there from your custom RecoveryCallback.
I am implementing Spring Integration for REST services. I am following XPadro's githib example - https://github.com/xpadro/spring-integration.
I have created simple read, write and update operations.
Examples taken from int-http-dsl project.
I want to implement spring-security with oath2. I am taking reference from http://docs.spring.io/spring-integration/reference/html/security.html.
I am not able to connect both together. Because below is how they map a request
#Bean
public IntegrationFlow httpGetFlow() {
return IntegrationFlows.from(httpGetGate()).channel("httpGetChannel").handle("personEndpoint", "get").get();
}
#Bean
public MessagingGatewaySupport httpGetGate() {
HttpRequestHandlingMessagingGateway handler = new HttpRequestHandlingMessagingGateway();
handler.setRequestMapping(createMapping(new HttpMethod[]{HttpMethod.GET}, "/persons/{personId}"));
handler.setPayloadExpression(parser().parseExpression("#pathVariables.personId"));
handler.setHeaderMapper(headerMapper());
return handler;
}
and below is how we can integrate security
#Bean
#SecuredChannel(interceptor = "channelSecurityInterceptor", sendAccess = "ROLE_ADMIN")
public SubscribableChannel adminChannel() {
return new DirectChannel();
}
I am not able to find a way to create channels in first example so how to integrate that.
Am I going right direction or getting it all wrong?
Is there any better tutorials to handle spring-integration (http) with spring-security (using oauth)?
Spring Integration Java DSL allows to use external #Beans for message channels from the flow definition. So, your httpGetChannel may be declared and used like:
#Bean
#SecuredChannel(interceptor = "channelSecurityInterceptor", sendAccess = "ROLE_ADMIN")
public SubscribableChannel httpGetChannel() {
return new DirectChannel();
}
#Bean
public IntegrationFlow httpGetFlow() {
return IntegrationFlows.from(httpGetGate())
.channel(httpGetChannel())
.handle("personEndpoint", "get")
.get();
}
Feel free to raise a GitHub issue to make in the Framework something more obvious directly from the DSL's .channel() definition: https://github.com/spring-projects/spring-integration-java-dsl/issues
Classic requirement of checking system state and notifying users. Specifically, I'll be hitting the database every x-amount of time, getting some data, then sending out email notifications based on the results. Heck, this service might not even send out an email, but create a notification record in the database.
Seems like with IOC and configuration there could be a generic windows service that manages all this, along with metrics and management, in a simple manner.
In the past I've done email notifications by:
1) Running scripts as cron (at on Windows) jobs
2) running custom executables as cron/at jobs
3) using something like SQLServer's DatabaseMail.
4) Custom NT Services that run all the time monitoring things.
Is there any open source projects that manages this? It's the type of code I've written many, many times in various platforms, but don't want to spend the few days doing it now.
The only thing I found so far was Quartz.Net
Thanks
I just create a Windows service and use the Reactive Extensions to schedule tasks. If you don't need as much flexibility as cron offers, this works fine. Here's an abstract hourly task runner. (uses log4net)
public abstract class HourlyTask : IWantToRunAtStartup
{
protected readonly ILog Log = LogManager.GetLogger(typeof (HourlyTask).FullName);
private IDisposable _Subscription;
private void ExecuteWithLog()
{
Log.Debug("Triggering " + GetType());
try
{
Execute();
}
catch (Exception exception)
{
Log.Error("Hourly execution failed", exception);
}
}
public abstract void Execute();
public void Run()
{
_Subscription = Observable
.Interval(TimeSpan.FromMinutes(1))
.Select(x => DateTime.Now.Hour)
.DistinctUntilChanged()
.Subscribe(i => ExecuteWithLog());
}
public void Stop()
{
if (_Subscription == null)
{
return;
}
_Subscription.Dispose();
}
}
Then in your start up method you can just resolve all IWantToRunAtStartup instances and call Run() on them.