I am refactoring my Flink Statefuns for embedded service deployment, but I cannot find the way to register statefun's ValueSpec in EmbeddedModule
When I was using remote http service deployment on k8s, I was building StatefulFunctionSpec with statefun's all value specs inside, and was registering it by StatefulFunctions.withStatefulFunction(spec):
Build static spec in MyStatefun:
static StatefulFunctionSpec SPEC = StatefulFunctionSpec.builder(MY_TYPE)
.withValueSpecs(MY_VALUE_SPEC)
.withSupplier(MyStatefun::new)
.build();
Register it in StatefulFunctions:
StatefulFunctions functions = new StatefulFunctions();
functions.withStatefulFunction(MyStatefun.SPEC);
And finally use functions.requestReplyHandler() as a handler in http server.
What's the way of doing that in EmbeddedModule?
In examples that I found so far, I only see that statefun is registered as this, but does this also register ValueSpecs?
binder.bindFunctionProvider(MyStatefun.FUNCTION_TYPE, x -> (StatefulFunction) new MyStatefun());
UPD. It seems that .bindFunctionProvider(...) cannot bind sdk.java.StatefulFunction, it can only bind sdk.StatefulFunction, which implements .invoke(sdk.Context, Object o) instead of .apply(sdk.java.Context, Message msg). And sdk.Context does not have .storage() method for accessing ValueSpecs.
UPD2. Found page about PersistedValue that could be used for state management and could possibly be the answer to my question: https://nightlies.apache.org/flink/flink-statefun-docs-master/docs/sdk/flink-datastream/
Related
Issue:
I am trying to update the GUI from a second thread.
Unfortunately the label stays the same. At first I thought there is an issue with the dispatcher but it works fine. It appears that the configuration is not threadsafe!
Code to reproduce:
I have a Settings File which is mainly used to keep variables persistent during application relaunches:
this is the Update code:
// get the amount of tickets created for me last week
int amountOftickets = JiraInterface.DayStatisticsGenerator.GetLastWeeksTicketAmount();
config.Default.Lastweekstickets = amountOftickets; // int == 12;
// Update GUI on GUI thread
mainWindow.Dispatcher.Invoke(() =>
{
mainWindow.SetIconsAccordingtoConfig();
mainWindow.NumberTicketsCreated.Content = config.Default.Lastweekstickets.ToString(); // int == 0!!
});
Does anyone have an Idea on how to shove the running configuration from the thread who updated it to the Gui thread?
After a quick look in the documentation, it seems that you have 2 options:
You can either use the Dispatcher.Invoke to set your config.Default
on GUI thread.
It seems that .NET Core and .NET Framework support synchronized SettingsBase which is what the Configs are ( https://learn.microsoft.com/en-us/dotnet/api/system.configuration.settingsbase.synchronized?view=netcore-3.0 )
EDIT 1:
Looking into the C# Properties more, it seems that if you look in your config file in Visual Studio under:
Properties -> Config.settings -> Config.Designer.cs
During the class initialization it seems that .NET Framework, already uses Synhronized property which should make the config thread safe
private static Config defaultInstance = ((Config)(global::System.Configuration.ApplicationSettingsBase.Synchronized(new Config())));
It could be that when you created this file, Synchronized wasn't used, so your config file isn't thread safe, especially if it was created in code and not designer/properties
From Microsoft Docs on SettingsBase Synchronized:
The indexer will get and set property data in a thread-safe manner if the IsSynchronized property is set to true. A SettingsBase instance by default is not thread-safe. However, you can call Synchronized passing in a SettingsBase instance to make the SettingsBase indexer operate in a thread-safe manner.
I am integrating Hystrix in an application. That application is already in production and we will be testing out hystrix integration work in sandbox before we will push it to production.
My question is that is there any way to turn on/off hystrix functionality using some configuration setting?
There is no single setting for this. You'll need to set multiple parameters to disable Hystrix.
See https://github.com/Netflix/Hystrix/wiki/Configuration for the configuration options:
hystrix.command.default.execution.isolation.strategy=SEMAPHORE
hystrix.command.default.execution.isolation.semaphore.maxConcurrentRequests=100000 # basically 'unlimited'
hystrix.command.default.execution.timeout.enabled=false
hystrix.command.default.circuitBreaker.enabled=false
hystrix.command.default.fallback.enabled=false
Please double check your version of Hystrix for the available parameters.
This is all what you need:
# Disable Circuit Breaker (Hystrix)
spring:
cloud:
circuit:
breaker:
enabled: false
hystrix:
command:
default:
circuitBreaker:
enabled: false
As ahus1 said, there is no single way to disable Hystrix entirely. To disable it in our application, we decided it was cleanest and safest to put a HystrixCommand in a wrapper class, and that wrapper class only exposed the parts of the HystrixCommand that we used (in our case, the execute() method). When constructing the wrapper class, we pass it a Callable that contains the code we want executed, and if Hystrix is disabled (according to our own config value), we simply call that Callable without ever creating a HystrixCommand. This avoids executing any Hystrix code whatsoever and makes it easier to say that Hystrix isn't affecting our application at all when it's disabled.
There are a couple of ways to achieve this-
Doing this for your every group including default. Although this will not disable hystrix(it will only keep the circuit closed all the time) but you will achieve the same result-
hystrix.command.{group-key}.circuitBreaker.forceClosed=false
If you are using java, you can create an around advice over #HystrixCommand annotation and bypass hystrix execution based upon a flag.
Java Code for #2-
#Pointcut("#annotation(com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand)")
public void hystrixCommandAnnotationPointcut() {
}
#Around("hystrixCommandAnnotationPointcut()")
public Object methodsAnnotatedWithHystrixCommand(final ProceedingJoinPoint joinPoint) throws Throwable {
Object result = null;
Method method = AopUtils.getMethodFromTarget(joinPoint);
if ((System.getProperty(enable.hystrix).equals("true")) {
result = joinPoint.proceed();
} else {
result = method.invoke(joinPoint.getTarget(), joinPoint.getArgs());
}
return result;
}
If your Project is spring Managed you can comment the bean definition of hystrixAspect in applicationContext.xml
Comment the following line
bean id="hystrixAspect"class="com.netflix.hystrix.contrib.javanica.aop.aspectj.HystrixCommandAspect"/>
This will remove Hystrix from your project.
I ran into this situation where I wanted to completely turnoff Hystrix using a single property (We use IBM uDeploy to manage dynamic properties). We are using javanica library built on top of Hystrix
Create a Configuration class which creates the HystrixCommandAspect
#Configuration
public class HystrixConfiguration{
#Bean(name = "hystrixCommandAspect")
#Conditional(HystrixEnableCondition.class)
public HystrixCommandAspect hystrixCommandAspect(){
return new HystrixCommandAspect()}
}
2. And the conditional class would be enabled based on a system property.
public class HystrixEnableCondition implements Condition{
#Override
public boolean matches(ConditionContext context, AnnotatedTypeMetadata metadata){
return
"YES".equalsIgnoreCase(
context.getEnvironment().getProperty("circuitBreaker.enabled")) ||
"YES".equalsIgnoreCase(
System.getProperty("circuitBreaker.enabled"));
}
}
setting
hystrix.command.default.execution.isolation.strategy=SEMAPHORE
is enough.
Additionally you may or should disable also the timeout threads
with hystrix.command.default.execution.timeout.enabled=false
I am trying to model an event-based gateway that waits for several messages, and optionally for a timer. Before using this in a real model I tried it in a unit test, and it seems in the camunda engine the condition is completely ignored. Now I'm wondering if this is supposed to be supported by bpmn, if not if there is an easy alternative way to model this.
The code for the unit test, based on the camunda-engine-unit-test project is as following:
Map<String, Object> variables = singletonMap("isTimerActive", (Object) false);
ProcessInstance pi = runtimeService.startProcessInstanceByKey("testProcess", variables);
assertFalse("Process instance should not be ended", pi.isEnded());
String id = pi.getProcessInstanceId();
Job timer = managementService.createJobQuery().processInstanceId(id).timers().active().singleResult();
assertNull(timer);
This is not allowed.
The outgoing Sequence Flows of the Event Gateway MUST NOT have a conditionExpression
BPMN 2.0 Specification Section 10.5.6, page 297
edit: source: http://www.omg.org/spec/BPMN/2.0/PDF
I am using Objectify for retrieving data From datastore in GWT,But i get the Following Error :
[ERROR] No source code is available for type
com.logins.entity.experts; did you forget to inherit a required
module?
I have Client->entity->Server and i did define the RPC properly with RemoteServicePath.
i intiaized the Rpc in client side
final findexpertAsync
finexp=(findexpertAsync)GWT.create(findexpert.class);
GWT compiler throws Error at the method i call,
finexp.expert(expnam, new AsyncCallback<ArrayList<experts>>()
Note:
1) findexpert and FindexpertAsync are the RPC interface which has a method for retriving data from datastore
2)com.logins.entity.experts:experts is a server class.
Any guesses where i am going wrong ?
All classes directly or indirectly referenced from the client must be part of the client source path. You can't access server-only code from GWT. In this case, class "experts" needs to be part of the GWT-compiled client code.
Also: You should capitalize Java class names.
In a WP7 Silverlight application with a WebBrowser control I want to use an own protocol like "myttp://" to deliver some local content. I can't use Navigate() to an IsolatedStrorage because some content will by created on demand. For the same reason NavigateToString() is also not usable for me.
I tried to register a WebRequestCreator descend for my MYTP protocol
myCreator = new MyRequestCreator();
WebRequest.RegisterPrefix("mytp://", myCreator);
but it isn't called from the browser control if I navigate to "mytp://test.html".
If I create a WebRequest via code
WebRequest request;
request = WebRequest.Create("mytp://test.html");`
everythings works fine.
Any suggestions what is wrong or how to do it?
The WebBrowser control will use the Windows Phone Internet Explorer Browser's HTTP stack to statisfy web requests. This HTTP stack is entirely separate from the Client HTTP stack being used by the application. Hence the browser does not see your protocol at all.
I agree with AnthonyWJones words, though I dont know, what exactly he meant by "Browser HTTP stack".
The standard Silverlight's "access to Browser's stack" (used to handle sessions etc) in form of System.Net.Browser.WebRequestCreator.BrowserHttp httprequest factory (versus the "normal/aside" System.Net.Browser.WebRequestCreator.ClientHttp factory) is actually available to the application code in WP7. It is hidden from the SDK, but available on the device and with small effort, the application can use it, for example, to have its emitted cookies in sync with the Browser's cache. For description, please see my humble other post
However, while using that factory and having all your session/cookies/userauth handling within those connections in sync with the WebBrowser, despite being very similar to the ClientHttp factory, you find (at least in 7.0 and 7.1 versions) that it is completely ignorant of any custom prefixes. Trying to open anything with this factory results in (WP7 v. Mango 7.1):
A first chance exception of type 'System.Net.ProtocolViolationException' occurred in System.Windows.dll
at System.Net.Browser.BrowserHttpWebRequest.InternalBeginGetRequestStream(AsyncCallback callback, Object state)
at System.Net.Browser.AsyncHelper.BeginOnUI(BeginMethod beginMethod, AsyncCallback callback, Object state)
at System.Net.Browser.BrowserHttpWebRequest.BeginGetRequestStream(AsyncCallback callback, Object state)
at MyApp.MyPage..ctor()
relevant code snippet of the MyPage:
public class WRC : IWebRequestCreate { public WebRequest Create(Uri uri) { return null;/*BREAKPOINT1*/ } }
WebRequest.RegisterPrefix("js://", new WRC()); // register the above handler
brwHttp = (IWebRequestCreate)typeof(System.Net.Browser.WebRequestCreator).GetProperty("BrowserHttp").GetValue(null, null);
var tmp = brwHttp.Create(new Uri("js://blah.blah.blah"));
var yyy = tmp.BeginGetResponse(callback, "wtf");
var response = tmp.EndGetResponse(yyy); /*BREAKPOINT2*/
var zzz = tmp.BeginGetRequestStream(callback, "wtf"); /*<---EXCEPTION*/
var stream = tmp.EndGetRequestStream(zzz); /*BREAKPOINT3*/
Execution results:
breakpoint1 never hit
breakpoint2 allows to see that "response" is NULL
breakpoint3 never hit due to the exception pasted above
My conclusion is, that the Silverlight Browser's stack is hardcoded to use some builtin set of prefixes, and all other prefixes are ignored/throw ProtocolViolation. My guess is, that in WP7 (7.0, 7.1) they are actually hardcoded to use http since my custom "js://" was passed to a BrowserHttpWebRequest.InternalBeginGetRequestStream as it's visible on the stacktrace :)
That confirms what Anthony had written - no way of having custom protocol handlers to work gracefully with the Silverlight's Browser Stack API.
However, I cannot agree with that the WebBrowser uses this connection factory. While is it true that the hidden factory is called BrowserHttp, and is true that it shares some per-user or per-session settings with the webbrowser, everything I try tens to indicate that the WebBrowser component uses yet completly other factory for its connections, and quite probably it is some native one. As an argument for that, I can only provide that I was able to successfully replace the original BrowserHttp factory with my simple custom implementation of it (both on the emulator and the phone), and with at least 6 webbrowsers in my current app, it wasn't used at all, not even once! (neither on the emulator, nor phone)