akkadotnet/akka.net

Port of Akka actors for .NET

Arsene

@Tochemey

@stijnherreman Since you are using Actor if it is possible simply use the synchronous version of your function call.

@stijnherreman Also if you can explain in details what you want to do I can be of a help.

Stijn Herreman

@stijnherreman

@Tochemey no sync versions available unfortunately. The IClient implementation code is generated by a third-party tool, from an OpenAPI (Swagger) spec.

Arsene

@Tochemey

@stijnherreman Okay

Stijn Herreman

@stijnherreman

I was reading http://gigi.nullneuron.net/gigilabs/asynchronous-and-concurrent-processing-in-akka-net-actors/ (and the previous article), about using ReceiveAsync or using PipeTo.

Arsene

@Tochemey

@stijnherreman That is cool

Stijn Herreman

@stijnherreman

Basically, the actor is responsible for retrieving a REST resource and supplying it back to whoever asked for it. But it should only ever retrieve the resource once, and then respond with the cached resource.

Arsene

@Tochemey

@stijnherreman From the Rest API controller use Ask<> to send the message to the Actor.

Stijn Herreman

@stijnherreman

@Tochemey ok, I'll take a look at that. I had previously read that Ask<> should be avoided, but to be honest I haven't taken a proper look at it yet.

Thank you :)

Arsene

@Tochemey

Then within the Actor where you are doing async stuff use:

CheckAsync().ContinueWith(task =>
                                {
                                    var response = task.Result;
                                    return response;
                                },
                                TaskContinuationOptions.AttachedToParent &
                                TaskContinuationOptions.ExecuteSynchronously).PipeTo(
                                closure);

@stijnherreman I have a production app using Rest API and Akka.NET

@stijnherreman CheckAsync() is a function that is running asynchronously.

@stijnherreman Please read this article: https://github.com/petabridge/akkadotnet-code-samples/tree/master/PipeTo

@stijnherreman closure = Sender

Stijn Herreman

@stijnherreman

I'll read the article, it looks like a good resource.

Arsene

@Tochemey

@stijnherreman http://bartoszsypytkowski.com/dont-ask-tell-2/

@stijnherreman These articles have helped to be grounded in the Ask/PipeTo pattern

Arjen Smits

@Danthar

@stijnherreman avoid ask if you can. In your scenario. Why not use the Become feature.

So you receive a request for your REST data. You detect that you dont have it in cache

Arsene

@Tochemey

@Danthar from REST API controller I think Ask is the best bet.

Arjen Smits

@Danthar

then perform your async -> pipeto stuff. At the end, switch behaviors with the Become feature

where you wait for your response message

and stash everything else

once you receive your response message

unstash all. And serve all the other stuff from your cache

that way you dont have to block your actor's execution. And you are sure you only pay the hit once

From your REST API Controller, ask is the only way to do request -> response style communication with an actor. So yes. Then you should use Ask

But then your communicating from outside your actor system. So you don't have much options there :)

Stijn Herreman

@stijnherreman

@Danthar thank you for the insight, it sounds like a viable path. I'll try out some things tomorrow, end of the (work) day for me here.

Jack Wild

@jackowild

Hi all, just submitted a PR to upgrade the Akka.Persistence.MongoDB plugin to 1.3.1. If somebody could review this it would be much appreciated.

Here's the link: AkkaNetContrib/Akka.Persistence.MongoDB#30

Michel van den Berg

@promontis

I'm having trouble to inject a specific HOCON config for my cluster-sharding section into my persistence plugin. When I look at other implementations of persistence plugins, I see two flavors: a constructor with and without a config parameter. Eg. SqliteJournal (https://github.com/akkadotnet/akka.net/blob/1595e1e832fb42b4a70a4ebf0b3dc52b87b40a96/src/contrib/persistence/Akka.Persistence.Sqlite/Journal/SqliteJournal.cs) has public SqliteJournal(Config journalConfig), whereas other persistence plugins do not provide the Config parameter. What's the deal with the Config parameter? Will the cluster sharding plugin inject the current config into the persistence plugin via that ctor?

Arjen Smits

@Danthar

@promontis check out the cluster sharding settings

it uses a journal-plugin-id and snapshot-plugin-id setting which contains the absolute path to the journal or snapshot plugin config entity

if you dont define that it uses the system default (whatever you have defined)

So in short cluster sharding does not initialise the persistence plugin. Its reponsible for doing that itself. In short through its respective hocon config or manually before you intialise the cluster sharding system

The Config parameter is there to allow you to manually provide override configs or a while config yourself.

If you dont define anything it will fallback to whatever is in the hocon config

And its also used for testing :P

@jackowild we probably already seen your PR come up. but I forwarded your request internally as well. Can't make any promises as to when someone will get around to it though.

Michel van den Berg

@promontis

@Danthar but how does the cluster sharding plugin tell the persistence plugin which config to use? I mean, if I look at the persistence plugins they all know how to persist to a journal using the default journal config (eg. akka.persistence.journal.sql-server). They do not check the config for the cluster setting, so how does the cluster sharding persistence config (as configured via the journal-plugin-id, as you said) flow to the persistence plugin?

For example, this plugin (https://github.com/alexvaluyskiy/Akka.Persistence.Azure/blob/dev/src/Akka.Persistence.AzureTable/AzureTablePersistence.cs#L85) always uses the same config section 'akka.persistence.journal.azure-table' for its persistence. It seems not able to get a different config for eg cluster sharding. This means both normal actor state and cluster sharding state will end up in the same table (as configured by that one config section)

with the sql-server persistence plugin it seems to work when I configure it like this (https://github.com/promontis/stylister.sample/blob/master/Liking/Stylister.Liking.Downloader/settings.hocon), but I don't get how the akka.persistence.journal.sharding config section is passed to the sql-server persistence plugin

Arjen Smits

@Danthar

eh. I dont understand your question. Because you answered it yourself already ?

Michel van den Berg

@promontis

haha

Arjen Smits

@Danthar

Wellicht PM even snel ?

Michel van den Berg

@promontis

sure :)

Jack Wild

@jackowild

thanks @Danthar , I'm not sure how the build/CI process works so will need some help with that when one of you gets round to it :+1:

Michal Dabrowski

@defrag2_twitter

Hey guys, question: whenever using a supervising actor for persistent actor (in case where they cannot really be
created or recreated on demand), is the approach of creating actors while replaying event mentioned in "akka in action"
book (https://github.com/RayRoestenburg/akka-in-action/blob/master/chapter-persistence/src/main/scala/aia/persistence/ShoppersSingleton.scala#L71)
the best way to go? Or some streaming from some other source would be more applicable?

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