Let's say I have some internal business logic that determines what mailer needs to be sent.
The output of this business logic is a Hash in the following format -
{ mailer_class: SomeMailer, mailer_method: "foo_email" }
{ mailer_class: OtherMailer, mailer_method: "bar_email" }
# etc...
I need to call the appropriate mailer based on the info above so I try something like this with Sidekiq's built in delay -
data = { mailer_class: ..., mailer_method: "..." }
data[:mailer_class].delay.send(mailer[:method])
This results in Sidekiq queueing up the send method which will eventually be called on my mailer.
Functionally it might work correctly, because that class after all will receive the appropriate method. But it feels a bit dirty and it interrupts other processes that watch the sidekiq queue because they expect to see a mailer method name but find :send instead.
Is there a good way around this or am I stuck modifying the rest of my application logic to work with this?
Thanks!
Why not pass that Hash to a Sidekiq Worker which knows how to send emails with that class/method combo?
def perform(hash)
hash['mailer_class'].constantize.send(hash['mailer_method'])
end
Related
I am building a bot for for Facebook Messenger using Microsoft Bot Framework. I am planning to use CosmosDB for State Management and also as my backend data store. (I am not stuck to CosmosBD and can use any other store if needed)
I need to send daily/weekly proactive messages(push notifications) to users based on their time preference. I will capturing their time preference when they first interact with the bot.
What is the best way to deliver these notifications?
As I will be storing these preferences in CosmosDB, I am thinking using ComosDB trigger of creating an Azure Function and schedule it based on the user time preference. This Azure function will make a call to my webhook which will deliver these messages. If requried, I will change Function schedule when a user changes his/her preference.
My questions are:
Is this a good approach?
Are there any other alternatives (Notifications Hub?)
I should be able to set specific times for notifications (like at the top of the hour or something like that), does it make sense to schedule an Azure Function to run at these hours rather than creating a function based on user preference (I can actually combine these two approaches too)
Thank you in advance.
First, I don't think there's any "right" answer to be given here; it's going to depend a lot on your domain's specific needs. Scale is going to play a major factor in the design of this. Will you have 100 users? 10000 users? 1mil users? I'm going to assume you want to design for maximum scale up front, but it could be overkill.
First, based on what you've described, I don't think a CosmosDB trigger is necessarily the solution to your problem because that's only going to fire when the preference data is created/updated. I assume that, from that point forward, your function needs to continuously fire at the time slot they've opted into, correct?
So let's pretend you let people choose from the 24hrs in the day. A naïve approach would be to simply use a scheduled trigger that fires up every hour, queries the CosmosDB for all the documents where the preference is set to that particular hour and then begins sending out notifications from there. The problem is how you scale from there and deal with issues of idempotency in the face of failures.
First off, a timer trigger only ever spins up one instance. If you were to just go query the CosmosDB documents and start processing them one by one in the scope of that single trigger, you'd hit a ceiling relatively quickly on how many notifications you can scale to. Instead what you'd want to do is use that timer trigger to fan out the notifications to as many "worker" function instances as possible. The timer trigger can act as the orchestrator in the sense that it can own the query against the CosmosDB and then turn each document result it finds for that particular notification time window into a message that it places on a queue to be processed by a separate function which will scale out on its own.
There are actually a couple ways you can accomplish this with Azure Functions, it really depends on how early an adopter of technology you are comfortable with being.
The first is what I would call the "manual" way which would be done by simply using the existing Azure Storage Queue extension by taking an IAsyncCollector<YourNotificationWorkerMessage> as a parameter to the timer function that's bound to the worker queue and then pumping out the messages through that. Then you write a second companion function which uses a QueueTrigger, bind it to that same queue, and it will take care of processing each message. This second function is where you get the scaling, enabling process all of the queued messages as quickly as possible based on whatever scaling parameters you choose to configure. This is the "simplest" approach
The second approach would be to adopt the newer Durable Functions extension. With that model, you don't have to directly think about creating a worker queue. You simply kick off a new instance of your orchestrator function from the timer function and the orchestrator fans out the work by invoking N "concurrent" calls to an action for each notification. Now, it happens to distribute those calls using queues under the covers, but that's an implementation detail that you need no longer maintain yourself. Additionally, if the work of delivering the notification requires more involved work and/or retry logic, you might actually consider using a sub-orchestration instead of a simple action. Finally, another added benefit of this approach, is that you can "fan back in" to your main orchestrator function once all the notifications are delivered to do some follow up work... even if that's simply some kind of event logging that the notification cycle has completed for this hour.
Now, the challenge with either of these approach is actually dealing with failure in initially fetching the candidates for notification from CosmosDB, paging through the results and making sure you actually fan all of them out in an idempotent manner. You need to deal with possible hiccups as you page and you need to deal with the fact that your whole function could be torn down and you might have to restart. Perhaps on the initial run of the 8AM notifications you got through page 273 out of 371 pages and then you got hit with a complete network connectivity fail or the VM your function was running on suffered a power failure. You could resume, but you'd need to know that you left off on page 273 and that you actually processed the 27th record out of that page and start from there. Otherwise, you risk sending double notifications to your users. Maybe that's something you can accept, maybe it's not. Maybe you're ok with the 27 notifications on that page being duplicated as long as the first 272 pages aren't. Again, this is something you need to decide for your domain, but if you want to avoid this issue your orchestrator function will need to track its progress to ensure that it doesn't send out dupes. Again I would say Durable Functions has a leg up here as it comes with the ability to configure retries. Maintaining the state of a particular run is left up to the author in either approach though.
I use pro-active dialog extensively with botframwork and messenger without any issue. During your facebook approval process you simply need to inform them you will be sending notifications trough messenger with your bot. Usually if you use it to inform your user and stay away from promotional content you should be fine.
I also use azure function to trigger the pro-active dialog from a custom controller endpoint.
Bellow sample code for azure function:
public static void Run(TimerInfo notificationTrigger, TraceWriter log)
{
try
{
//Serialize request object
string timerInfo = JsonConvert.SerializeObject(notificationTrigger);
//Create a request for bot service with security token
HttpRequestMessage hrm = new HttpRequestMessage()
{
Method = HttpMethod.Post,
RequestUri = new Uri(NotificationEndPointUrl),
Content = new StringContent(timerInfo, Encoding.UTF8, "application/json")
};
hrm.Headers.Add("Authorization", NotificationApiKey);
log.Info(JsonConvert.SerializeObject(hrm));
//Call service
using (var client = new HttpClient())
{
Task task = client.SendAsync(hrm).ContinueWith((taskResponse) =>
{
HttpResponseMessage result = taskResponse.Result;
var jsonString = result.Content.ReadAsStringAsync();
jsonString.Wait();
if (result.StatusCode != System.Net.HttpStatusCode.OK)
{
//Throw what ever problem as an exception with details
throw new Exception($"AzureFunction - ERRROR - HTTP {result.StatusCode}");
}
});
task.Wait();
}
}
catch (Exception ex)
{
//TODO log
}
}
Bellow sample code for starting the pro-active dialog:
public static async Task Resume<T, R>(string resumptionCookie) where T : IDialog<R>, new()
{
//Deserialize reference to conversation
ConversationReference conversationReference = JsonConvert.DeserializeObject<ConversationReference>(resumptionCookie);
//Generate message from bot to user
var message = conversationReference.GetPostToBotMessage();
var builder = new ContainerBuilder();
using (var scope = DialogModule.BeginLifetimeScope(Conversation.Container, message))
{
//From a cold start the service is not yet authenticated with dev bot azure services
//We thus must trust endpoint url.
if (!MicrosoftAppCredentials.IsTrustedServiceUrl(message.ServiceUrl))
{
MicrosoftAppCredentials.TrustServiceUrl(message.ServiceUrl, DateTime.MaxValue);
}
var botData = scope.Resolve<IBotData>();
await botData.LoadAsync(CancellationToken.None);
//This is our dialog stack
var task = scope.Resolve<IDialogTask>();
T dialog = scope.Resolve<T>(); //Resolve the dialog using autofac
try
{
task.Call(dialog.Void<R, IMessageActivity>(), null);
await task.PollAsync(CancellationToken.None);
}
catch (Exception ex)
{
//TODO log
}
finally
{
//flush dialog stack
await botData.FlushAsync(CancellationToken.None);
}
}
}
Your dialog needs to be registered in autofac.
Your resumptionCookie needs to be saved in your db.
You might want to check FB policy regarding proactive messages
There’s a 24h limit but it might not be totally screwed in your case
https://developers.facebook.com/docs/messenger-platform/policy/policy-overview#standard_messaging
I have a ServiceWorker registered on my page and want to pass some data to it so it can be stored in an IndexedDB and used later for network requests (it's an access token).
Is the correct thing just to use network requests and catch them on the SW side using fetch, or is there something more clever?
Note for future readers wondering similar things to me:
Setting properties on the SW registration object, e.g. setting self.registration.foo to a function within the service worker and doing the following in the page:
navigator.serviceWorker.getRegistration().then(function(reg) { reg.foo; })
Results in TypeError: reg.foo is not a function. I presume this is something to do with the lifecycle of a ServiceWorker meaning you can't modify it and expect those modification to be accessible in the future, so any interface with a SW likely has to be postMessage style, so perhaps just using fetch is the best way to go...?
So it turns out that you can't actually call a method within a SW from your app (due to lifecycle issues), so you have to use a postMessage API to pass serialized JSON messages around (so no passing callbacks etc).
You can send a message to the controlling SW with the following app code:
navigator.serviceWorker.controller.postMessage({'hello': 'world'})
Combined with the following in the SW code:
self.addEventListener('message', function (evt) {
console.log('postMessage received', evt.data);
})
Which results in the following in my SW's console:
postMessage received Object {hello: "world"}
So by passing in a message (JS object) which indicates the function and arguments I want to call my event listener can receive it and call the right function in the SW. To return a result to the app code you will need to also pass a port of a MessageChannel in to the SW and then respond via postMessage, for example in the app you'd create and send over a MessageChannel with the data:
var messageChannel = new MessageChannel();
messageChannel.port1.onmessage = function(event) {
console.log(event.data);
};
// This sends the message data as well as transferring messageChannel.port2 to the service worker.
// The service worker can then use the transferred port to reply via postMessage(), which
// will in turn trigger the onmessage handler on messageChannel.port1.
// See https://html.spec.whatwg.org/multipage/workers.html#dom-worker-postmessage
navigator.serviceWorker.controller.postMessage(message, [messageChannel.port2]);
and then you can respond via it in your Service Worker within the message handler:
evt.ports[0].postMessage({'hello': 'world'});
To pass data to your service worker, the above mentioned is a good way. But in case, if someone is still having a hard time implementing that, there is an other hack around for that,
1 - append your data to get parameter while you load service-worker (for eg., from sw.js -> sw.js?a=x&b=y&c=z)
2- Now in service worker, fetch those data using self.self.location.search.
Note, this will be beneficial only if the data you pass do not change for a particular client very often, other wise it will keep changing the loading url of service worker for that particular client and every time the client reloads or revisits, new service worker is installed.
I Implemented a HttpListener to process SoapRequests. This works fine but I can't find a soloution for the problem, that some soap-requests take too much time, resulting in timeouts on client side.
How do I let the requesting client know, that his request is not a timeout?
I thought about sending "dummy"-information while the request gets processsed, but the HttpListener only seems to send the data when you Close the response-object, and this can be done only once, so this is not the right thing to do I suppose.
Soloution:
Thread alliveWorker = new Thread(() =>
{
try
{
while (context.Response.OutputStream.CanWrite)
{
context.Response.OutputStream.WriteByte((byte) ' ');
context.Response.OutputStream.Flush();
Thread.Sleep(5000);
}
}
finally
{
}
});
alliveWorker.Start();
doWork();
alliveWorker.Interrupt();
createTheRealResponse();
Sending dummy information is not a bad idea.
I think you need to call the Flush() method on the HttpListenerResponse's OutputStream property after writing the dummy data. You must also enable SendChunked property:
Try sending a dummy space at regular interval:
response.SendChunked = true;
response.OutputStream.WriteByte((byte)' ');
response.OutputStream.Flush();
I see two options - increase timeouts on client side or extend protocol with operation status requests from client for long running operations.
If you are using .net 4.5, take a look at the HttpListenerTimeoutManager Class, you can use this class as a base to implement custom timeout behaviour.
I have a jobque mechanism in ZF.
The jobque simlpy stores the the function call (Class, Method and params) and later executes it as CLI daemon. The daemon works, however at places the application looks for information from the request object, and when called from the CLI these places fail, or get no info.
I would like to store the original request object together with the job and when the job is processed set the request object back as if the job was done by the originall request, somethin along the line of the following pseudo code:
$ser_request = serialize(Zend_Controller_Front::getInstance ()->getRequest ());
-->save to db
-->retrive from db
$ZCF= new Zend_Controller_Front;
$ZCF::getInstance ()->setRequest (unserialize($ser_request))
The aim is to store and replay the jobs later withouth having to change the rest of the application.
Any suggestions how to do that?
I am not sure if this works, but here's an idea. Try to implement _sleep and _wakeup magic methods for the request object. Haven't tried it out, but maybe it's at least a starting solution.
I'm using the MVVM Light Toolkit. I could not find any Ctor of Messenger or Notification class to send a empty message.
ViewModel1:
private int _selectedWeeklyRotation;
public int SelectedWeeklyRotation
{
get { return _selectedWeeklyRotation; }
set
{
if(_selectedWeeklyRotation == value)
return;
_selectedWeeklyRotation = value;
this.OnPropertyChanged("SelectedWeeklyRotation");
if(value > 1)
Messenger.Default.Send();
}
}
ViewModel2:
Ctor:
Messenger.Default.Register(this, CreateAnotherTimeTable);
private void CreateAnotherTimeTable()
{
}
I just need to send a Notification to another ViewModel, no sending of data at all.
Is that possible with MVVM Light Toolkit library?
Unless I'm misunderstanding something, couldn't you accomplish this by creating and sending a custom "signal message" type via the Messenger?
public class WeeklyRotationSignal {}
Messenger.Default.Send(new WeeklyRotationSignal());
Then register to that in another view model:
Messenger.Default.Register<WeeklyRotationSignal>(this, msg => doWork);
You can try sending a simple message with a string tag and receive that message by matching the string tag. Something like this:
Sender portion of the code located possibly in something like ViewModel1.cs
Messenger.Default.Send<string>("Dummy text message", "String_ToHelpMatchTheMsg");
Receiving end portion of the code responding to that message above, possibly located in some other file, something like ViewModel2.cs
...
Messenger.Default.Register<string>(this, "String_ToHelpMatchTheMsg", executeThisFunction);
private void executeThisFunction(string strMsg)
{
//your code would go here to run upon receiving the message
// The following line will display: "Dummy text message"
System.Windows.Browser.HtmlPage.Window.Alert("msg passed: " + strMsg);
}
Please note that you dont have to do anything with the text message that is passed around with the messaging code above. Just one part of the code sending some ping to another part of the code to ask some other section to execute some code. The important string is the one where I used "String_ToHelpMatchTheMsg" because that is the key used to match the sender and the receiver. Almost like creating your own quasi-event, once the Send method runs, the Register method is notified and fire its own function to run also.
I used this with a Close button on a Child Window to close it. The Close button on the View of the Child Window binds to a relay command on its childWindowViewModel. That relay command has the code above to send a message to the ParentViewModel. The Register portion on the ParentViewModel responds to that message by firing a method that closes the ChildWindow which was initially instantied from that parentViewModel.
Once you get more familiar with messaging, there are more attributes that you will be able to use so that the receiver can call back the sender to give a status or some data back. Look for Delegates and lambda function to achieve this.
All this to avoid placing code in the code behind to close the child window! :-)
Use as you see fit.
Cheers.
Mario
There really isn't a way to accomplish this and in someways defies the point of the messenger class. I didn't want to write a your doing it wrong post, but I feel I am stuck. The way the messenger class works is that you have two parties that both subscribe to the same concept, its an observer model. Without that similar concept or message there really isn't a way to tie the two objects together. The generic message whether a simple string or custom message act as the meeting point of the Subscribing and Publishing classes.
If the ViewModel publishing knows the type of ViewModel its trying to Send to it could...
Messenger.Default.Send<Type>(typeof(ViewModelToSendTo);
This would act as a very simple interaction point, you also wouldn't have to create a custom class. Some purist may have an issue with this approach as it couples the publishing class to the subscriber.
I don't think that it is possible and frankly I don't see the point of having that kind of message. You could just as well send a string "SelectedWeeklyRotation". It seems strange to have an empty message that has some kind of meaning as you increase the number of broadcast messages - and receivers in your application.
In the version of MVVM Light that I'm using it is not even possible to send an empty message.
However I did see a method in the ViewModelBase that is :
// Update bindings and broadcast change using GalaSoft.MvvmLight.Messenging
RaisePropertyChanged(MyPropertyPropertyName, oldValue, value, true);
This might be of interest for you.