I've been following this tutorial and have reached the point where I am able to receive push notifications (only working with android for now). My code is almost identical to the tutorial's. I'm now looking to expand the functionality. In the tutorial, when the app receives a RemoteMessage object, it parses out the "action" value from the data. It then passes that string to the NotificationActionService which triggers an action.
public override void OnMessageReceived(RemoteMessage message)
{
if (message.Data.TryGetValue("action", out var messageAction))
NotificationActionService.TriggerAction(messageAction);
}
The downside to this is that the only information it passes to the rest of the program is the name of the action. I want to add additional information. I would usually just add another parameter to the TriggerAction method, but the implementation of INotificationActionService is pretty involved. I'm wondering if its like that for a reason, or if I can just process my message in the OnMessageReceived. What makes me hesitant to change this is that the this action string is also pulled from the Intent on start up, and I'm not sure if if this will break it. I'm not entirely sure how android intents work, but both the RemoteMessage and the Intent would require this extra data inside the dictionary.
So, what is the best way to modify this tutorial to allow extra context to be passed in the push notification?
This is a good question - and realistically there isn't really one answer. Basically, all Android applications are going to be a collection of Activities and Services. You can think of them like independent threads that the OS is aware of and can help manage. Intents are a standardized way to communicate between these threads using a small set of types that are safe to serialize, so the OS can make stronger guarantees about the how and when it'll be delivered. There's a lot of documentation, and a whole world of different ways to architect your application with these. Each approach will have pros and cons, with some options being way too sophisticated for some applications, and others way too simple.
The Xamarin sample you're referencing keeps two separate threads: one for receiving remote notifications and one for rendering notifications. In principle, a developer may do this to allow notifications to be rendered in response to a message from a remote service OR in response to events local to the phone. For instance, my banking app alerts me that I'm being logged-out after 15 minutes of inactivity, and also when new tax documents are available. The first scenario is best served locally, where a notification will be rendered because a timer reached 15 minutes without being reset. The second scenario is better served by a remote notification so the app doesn't need to poll for new documents.
Bottom line - the sample app may be using an approach that introduces more overhead than your scenario calls for. For others it will be too simple. Choose what is right for your application.
Related
Intro
Hey, my question is kind of hard to explain so I apologize in advance.
Question
I'm trying to implement microservices for our ecommerce and I'm having issues on how to respond to a request when the actual logic and data needs to be determined by other ( 2-3 ) services.
In order to make it easier to understand, I'll give an example.
Lets say User A is trying to buy a product. after clicking on "check out" button these steps should happen.
Flow
Request comes in:
Ecommerce service:
Check if product has enough quantity in inventory.
Publish an event indicating a new order has been created. order:created
Anti Fraud service:
Receives order:created and checks whether the user is a fraud or not
Publishes an event indicating the check was successful. check:succeed
Payment Service:
Receives check:succeed and creates a url to the gateway.
Sends the gateway url to the user. (( this is where the question arises ))
Since all of these steps are asynchronous, how do I respond to the request?
Possible Solution
After the user has requested to checkout, the ecommerce service creates an order and responds immediately with the orderId of newly created order, on client-side the user has to request periodically and check whether the status of order is PENDING PAYMENT, in order to achieve this, the payment service needs to publish payment:created after the order has been approved by the system and then ecommerce service can update the order.
My solution works, but I'm really new to microservices and I want to ask from experts like you on how to implement this in a better way.
I really appreciate if you read this far, Thank you for your time.
your flow is a synchronous process. you need a result from previous step so it has to go step by step.
point of system view:
what matters here is: "how to handle steps?". which reminds me SAGA design pattern (specially when you need a rollback handling) but in general there are two types (choreography and orchestration). The choreography describes the interactions between multiple services, where as orchestration represents control from one party's perspective.
for simplicity you can implement the command pattern or use EAI(Enterprise Application Integration) tools like Apache camel to handle message between endpoints according to the flow.
if you have a lots of visitors it's also better to use a queue between endpoints whether with an orchestrator or without.
point of user view:
when a user click to checkout their cart. they don't expect many of steps or to do more than just wait. as keeping the connection open for response is not a good idea maybe a loader and a periodically ajax call behind it is quite enough while there are other solutions like push notification (then you can consider on fire and forget mechanism).
Your workflow for handling a request as it is defined is totally synchronous. Each step depends on the previous step, and cannot start until it finishes. However, second step does not seem to need data from the first step, so actually they could be executed in parallel.
so, what can be done is start both of them:
Check if product has enough quantity in inventory.
Checks whether the user is a fraud or not
then
wait for response and if both are ok, then creates a url to the gateway. and sends it to the user.
You can create a camel route or any other tool that implements EIP to achieve the functionality
Scenario:
I have a call being made to a WCF service which will take several minutes to get a response.
Initially the call was being made with an action which was on the ViewModel which then saved an updated version of an object to a Repository and then the Repository would pass the object to the service layer to be sent to a web service.
Once done the service layer would return the response to the repository and then to the ViewModel which would then raise a dialogue to the user giving them a series of options.
Issue:
The user can goto other views in the app while they are waiting which would destroy the ViewModel which then the user would not get the message alerting them..
So in a nut shell, I need to keep whatever function receives the response from the repository in memory until its completed.
To get around this I moved the dialogue and function into the repository as this is a singleton so will stay in memory but that defeats Single Responsibility as the repositories should only be responsible for the providing of data not carrying out business logic.
I have looked into raising this through messaging centre instead but I believe that this will keep ViewModel in memory and the user could make this request a few times resulting in the messaging center being called with each request.
Does anyone have a best practise for handling this scenario or any documentation they could refer me to?
Thanks for your help in advance :)
In this case you should take a look at background task. It lives outside the lifecycle of mobile app. If your process is taking several minutes it's almost impossible to relay on app itself as user can terminate it or put it to sleep anytime, and you are not able to prevent it.
I need to notify a backend server about Skype for Business call events. Calling the backend is not the problem, but listening to call events is. I thought about watching and parsing skype log files, but there seems to be no call information in the log files... And it would be an ugly solution anyway.
Is it possible to somehow listen to SfB call events and trigger custom actions?
I know there are various SfB SDKs, but none of them seem to offer a way to listen to these events...
I would like to be able to do something like this (pseudo code, I don't really care what language is used, but would prefer JavaScript):
skype.onCallIncoming(callInfo => {
console.log(callInfo.user + ' is calling');
// my custom action
});
skype.onCallAccepted(callInfo => {
console.log('The call was accepted');
// my custom action
});
skype.onCallEnded(callInfo => {
console.log('The call was ended');
// my custom action
});
SfB does not provide any live "call events" that you can use in ANY SDK.
For live "calls", the best you can do (with little effort) is to subscribe to a users presence and hook off the "on a call" (on-the-phone) activity token busy status (this presence state is not guaranteed to be correct). The problem with this is you can't really get "all" call events for everyone, since you can only subscribe to endpoints that you know about. There are also problems with working with large scale subscriptions. This can be done with most of the SDK's for Skype include UCWA.
Another option is to use the CDR database, although that is not for "live" calls and the CDR database needs to be enabled for the site. Once enabled you can just use SQL queries again the DB for historical call data.
If you really need large scale call monitoring, then the only option is to create a SIP proxy application that runs on the FE machines and translates "sip" messages into call events. This is a lot of work, it seems simple to do but gets very difficult very fast. This will give you "live" call events but will take someone a long long time to get it right and you have to have a deep understanding of SIP.
If you are talking about just your local Skype desktop client calls ONLY (windows client only), you can use the client SDK to hook into the local client and you can track the call events that way.
Hey in my team's slack (messaging system for those who don't know) we have an automatic response, so that when anyone says "trump", slackbot automatically responds with "the wall just got ten feet higher". Now I want to make a counter that essentially allows slackbot to state "the wall just got ten feet higher, wall height:(have a updated value according to number of times "trump" has been stated)" So basically I want a way to have a value that updates the wall height but I am lost on how to do that within slackbot. Any help is much appreciated, thanks to all!
The default features provided by Slackbot only allows it to respond to keywords, but not much more. So to provide that additional feature you would need to develop a custom bot.
For your use case I would recommend building a so called internal integration for Slack using the Events API.
Internal integration allows you to add custom functions for your Slack team only (as opposed to a full fledged Slack app, that could also be installed and used for other Slack teams).
The Events API allows you to set up a bot that listens to messages and can react to keywords like "trump".
An alternative approach to the events API would be the outgoing webhook. However this function is now deprecated and should no longer be used. Also it only works with public channels.
To set this up you will need to develop a small webservice (e.g. in PHP) that listens on a webserver for requests from the events API, keeps count of how many times the keyword has been invoked in the past and sends an appropriate message back to your Slack team every time the keyword is used.
I can recommend reading the excellent official Slack API documentation if you want to learn more.
If you are familiar with PHP this can be done easily using the Slackbot Framework. It supports Events API allowing you to listen to messages in channels or direct messages (depending on the permission scopes of your APP). So all the conversations on Slack can be sent to your server and you can search for the specific keyword in every message. Then send back an appropriate message to Slack. In summary, the first step is to create an APP for your slack team at https://api.slack.com/apps?new_app=1. Next step is to install the Slackbot Framework which is explained here. Hope this is helpful.
That can also be done by integrating custom slack bot using Django. You'll have to subscribe events and based on events, Slack will send conversation message to the given url, and based on the event, you can write your logic to increase count and post message back to slack work space.
Been moving into some task oriented UI as a part of my CQRS implementation.
The problem is I have come across the need to update additional properties in my UI as a result of a change made by an initial command sent from the same UI.
My case is different but here's an example...
eg. CommandA Add item to cart resulted in the following events (which all need to be reflected on the UI)
change to store inventory
add item to shopping cart
change total with sales tax
What's the best way to handle this without baking my business logic into my UI?
return a list of resulting events that were performed as a result to the initial command?
return a DTO that reflects changes
other ideas?
I haven't completed it yet, but my idea is to use a Hub from the SignalR framework and subscribe to events and act on them. As long as you can correlate user guids with the connected user guids in SignalR, you can send updates to the correct client and even detect if they still are there.
SignalR isn't that mature yet but the tests I have done works pretty good.
I use it with Knockoutjs and I just update my view models and call functions.
Do those events really need to be reflected in the UI? Consider Amazon, who display "you just added foo to your cart", but don't show any of those other details. That might save you from the problem by redefining it away.
Otherwise, why are you afraid of business logic in the "UI" - specifically, why not include some components from the service that owns each part of that system in your client, and give them the responsibility of doing whatever local updates are appropriate?
In other words, having part of the logic from your sales tax service running in the UI is fine. You (obviously) don't trust it with the billing calculations for tax, but you can totally trust it to do the right thing for the client.
The other advantage of that model is that you get instant feedback for the user, or at least the option of showing instant feedback, without baking more business process knowledge into the client.
For example, recalculating shipping takes time to do - if your client shows a spinner over that, something needs to know to trigger that showing up, right?
If your UI knows that, it has embedded business process around the process. On the other hand, if you have code that is part of the "shipping" service, you can change what response occurs in the client by changing only the one service...