Event-driven programming refers to the programming technique where the flow of the program is driven by recognition and handling of events such as mouse clicks, key presses, etc.
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How to create a timed-event architecture using a SQL database
The title of my question is general because I feel like this problem is of a general nature, but to set the stage I'm going to provide a specific example.
We use a homegrown workflow engine that is ...
1
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2answers
41 views
Proper event driven design when a consumer subscribes to many producers
I have a large number of instances of a class. Those instances can fire an event. The only important thing for that event is which instance fired it.
I have another instance of a class (and maybe in ...
0
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0answers
36 views
Sending events down a tunnel, and bubbling them back up
I am working on developing an HTML canvas application, where I need to be able to do my own UI event processing. That's where the stem of this question comes from, but I'd really like to understand ...
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1answer
27 views
How would you structure a flowchart/data flow diagram for an application that runs on a game engine?
I understand how you create flowcharts or data flow diagrams for simple linear based programming. But how do you design a flowchart for event based programming, like a game that runs on Unity3D? How ...
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1answer
59 views
Should I use a command or an event?
The difference between a command and an event in bus communication seems a little vague to me. I know that commands should be executed once only, while an event can be handled multiple times, but ...
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1answer
62 views
Can event emitters be functional?
For instance, array.map accepts a callback that returns a value.
const newArray = oldArray.map(item => doSomethingTo(item));
Promises also accept callbacks that return a value.
const ...
2
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0answers
31 views
Pattern matching events with arbitrary structure
My team implemented an alert broker system. The way it works is this:
Event sources generate events, with mostly arbitrary structure, and the broker listens to them.
Users go to the broker and use an ...
1
vote
1answer
59 views
What pattern should I set for handling event as working item?
I have this business event : "CustomerUpdated" published by my system.
I have many application listening to these events, and they do all king of action : sending email, updating the database, ...
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0answers
27 views
How to setup dependency injection framework in JavaScript
I'm creating a web page and would like to keep the UI and the JavaScript separate.
To accomplish that I'd like to add event listeners after the UI elements have been created. I don't know if this is ...
2
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1answer
49 views
ADO.NET - Is it better to handle a combo box or label event, and where should the data be sourced from?
Context
I recently wrote a final exam that required using a BindingSource object with ADO.NET to populate a number of combo box and label controls from which the user could perform basic business ...
53
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8answers
8k views
Are events only used for GUI programming?
Are events only used for GUI programming?
How do you handle in normal backend programming when something happens to this other thing?
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1answer
56 views
“An event can be made of two parts, the event header and the event body.” Is this about event or event notification?
From: https://en.wikipedia.org/wiki/Event-driven_architecture
Considering:
Events do not travel, they just occur.
Are the following statements valid?
Event channels are conduits in which events ...
4
votes
1answer
52 views
How to prevent endles event recursion when using event driven data view?
Consider that you have some graphical interface that represents some data structure. For example a text field:
This field is connected to the data structure through events. I tried to make diagram of ...
1
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1answer
117 views
In an event driven microservice environment, are domain events equal to topics?
A lot of messaging frameworks have the term "topic". In a ddd microservice architecture, do these topics always reflect the domain events?
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4answers
156 views
Callbacks without concurrency? [closed]
To sync on the terms I will first give my perspective on what a callback function in the simplest possible terms:
A callback function is a function that is executed as a response to a certain ...
3
votes
0answers
169 views
Event driven programming in Haskell
I'm new to Haskell, so this is more a high-level conceptual question. I've read this: https://wiki.haskell.org/Real_World_Applications/Event_Driven_Applications and it has this:
run :: Domain -> [...
6
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2answers
166 views
Ensure that callbacks registration and triggering don't cause infinite recursion
I just spent a long, miserable week debugging a stack-overflow in a C++/Qt application. The fundamental problem was that I had a function that accepted a callback, and in certain cases the callback ...
0
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0answers
35 views
Event dispatcher and state
I'm using an event emitter similar to Node's, with the following pseudo code:
event.on('onFuncBegin',(e)=>);
event.on('onFuncEnd',(e)=>);
let myFunc=()=>{
event.emit('onFuncBegin',...
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vote
3answers
219 views
Use case for async/await?
Background
Most of the applications that I write are hour long sequential tests for electronic equipment. The equipment under test has a specification that is a state-machine that looks like...
Get ...
1
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1answer
101 views
Eventing solutions for java legacy applications too old for real JMS queue/topic eventing?
What are some architectural solutions that can mimic eventing for systems (Java) that are too old to implement eventing solutions, such as conventional Queue/Topic based JMS messaging?
I have a ...
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0answers
91 views
What to use in case of waiting for something that is complete: delegates, events and/or thread
I try to give a concrete example.
Create a semaphore for a crossroads.
I have two semaphores. I have possibility to set a duration of semaphore 2 minutes, 5 minutes, 10m inutes etc.
When one ...
17
votes
4answers
2k views
Event-driven programming: when is it worth it?
Ok, I know the title of this question is almost identical to When should I use event based programming? but the answers of said question have not helped me in deciding whether I should use events in ...
1
vote
1answer
152 views
For Web front end, if there are 20 JavaScript files loading, how to track down the mouseover handler?
For Web front end programming, since any JavaScript can set up an event listener for "mouseover" or "mouseenter" for an element, if we are to track down what is the code that is responsible for making ...
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0answers
98 views
Using events and event subscribers to create windows in a desktop application
I should probably open this by saying I do mostly Web applications at work, which obviously have some major differences from typical desktop stuff.
I had a small Windows Forms program I'd made for ...
1
vote
1answer
120 views
“Who” should handle side tasks for events?
I'm currently on the process of creating a website/webapp.
My application is based on Node JS with the express framework.
My core backend concept consists of
routers: handle http request. Like [...
2
votes
1answer
162 views
Why does Node not support several event loops in one Process?
As the title says, why does Node not support several event loops in one Process? The idea, is that node spawns a user decided number of threads, which each have an event loop. When a new callback is ...
0
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2answers
84 views
What is the name for user-defined methods / functions that get called implicitly? [closed]
I want to mark such methods in my application code with a comment that highlights that these methods are expected to get called by the framework / compiler the application is written for, even if the ...
6
votes
4answers
654 views
Why use plus equals += for event registration?
In C#, you register an event like:
window.onClick += myHandler;
But why use this instead of a "register" method that takes your handler and registers it. E.g.:
window.registerOnClick(myHandler);
...
3
votes
0answers
83 views
Sharing identical events, with differing scopes, between client and server libraries, in a micro-service architecture
I have a shared user repository (id, name, e-mail, password, etc.) exposed as a REST service - and multiple independent web-sites accessing this REST service (from the back-end) as a means of sharing ...
8
votes
1answer
307 views
Is event sourcing only for when writes are rare?
I'm reading up on event sourcing and can't stop asking myself if it only makes sense in exotic situations where writes are very rare or military-grade auditing is required.
A non-exceptional system ...
1
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2answers
279 views
Persistence models for Event Sourcing
I am intrigued by the Event Sourcing pattern but am struggling to design an event sourcing model and put it in concrete form.
First off, I want to make sure that I understand the main use cases of ...
1
vote
1answer
161 views
Object Communication Design
Multiple top-level systems that communicate with each other via messages(events/commands).
The Main class of the program wraps around all the systems and has a message dispacher component wich ...
2
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1answer
88 views
Identity propagation using Azure service bus
We currently have a platform with a SOA architecture in which the user's identity is propagated from the web application via middle tier services (REST and SOAP) until we actually query our data ...
3
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0answers
159 views
Web framework architecture with non-blocking I/O
There's been a lot of news in the enterprise world lately, specially in the web, and I've decided to build a small web framework on top of Netty to learn more about asynchronous programming and event-...
0
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2answers
480 views
What's the simplest way to deal with events in C in this situation?
I'm writing a text-based game, in C. I want the game to handle NPCs movement and actions in the background, while the user is making his moves. I'd also use time-based events to tell the user when ...
1
vote
3answers
203 views
When is a event listener invoked during program execution?
I am using the Obervable-Observer Pattern.
MyClass extends Observable{
invokeListeners(){
doSomething;
setChanged();
notifyListeners();//This invokes onUpdate() in "implements ...
2
votes
3answers
310 views
Are imperative events an anti-pattern?
Are events which are intended to tell listeners to carry out explicit actions an anti-pattern?
Imagine a worker service which raises the event WorkStarted at its beginning and the event WorkFinised ...
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1answer
2k views
Should I use: One event multiple subscribers or multiple events multiple subscribers
I am writing a data acquisition application. I wondering whether I should use one event multiple subscribers or multiple events multiple subscribers. I am worried about performance. Also could I ...
0
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2answers
118 views
Receive events in an event-loop, single-threaded
Let's say I have a program which consists of a main event loop. The event loop should check for tasks and if one exists, it is to be processed. The user interface consists of a GUI with buttons, for ...
3
votes
1answer
166 views
Structure project based on platform or design?
I have a medium sized project (~10,000 lines) that runs on Windows and Linux. However it is only specific components of the program that are platform dependent and are located in a folder called ...
1
vote
2answers
360 views
Observer pattern without state change?
My question is whether there is a similar pattern to Observer that does not imply a state change in the observed object. The following is a concrete example:
I have a ConnectionFactory class which is ...
2
votes
1answer
103 views
What are the underlying patterns in systems allowing asynchronous operations?
Say I'm working with a system that allows async, nonblocking operations. If I queue up a set of those operations and specify their result buffer references:
nonblocking_write( message, write_buffer )...
1
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1answer
108 views
Event action abstraction and trigger control
I am thinking of abstracting Event action in order to make further alteration/implementation/maintenance easy since the project I am currently working on has volatile requirement. So I thought of the ...
31
votes
6answers
2k views
How to handle initial state in an event-driven architecture?
In an event-driven architecture each component only acts when an event is sent through the system.
Imagine a hypothetical car with a brake pedal and a brake light.
The brake light turns on when it ...
3
votes
1answer
459 views
Why do browsers clamp timeouts and intervals?
I've been working on some abstractions of setTimeout and setInterval in order to process large sets of data without blocking the event loop in the browser.
Upon this, I have discovered that browsers "...
4
votes
1answer
661 views
Are there any design pattern to data binding in event driven architecture?
I develop a browser based game with node.js in back and HTML5 canvas in front-end.
It use WebSockets for communication.
My plan is to generate business events in client side, e.g.: "finishJob".
...
53
votes
5answers
9k views
When should I use event-based programming?
I have been passing callbacks or just triggering the functions from other function in my programs to make things happen once tasks complete. When something finishes, I trigger the function directly:
...
1
vote
3answers
209 views
Event Driven Objects/Framework on the Web [closed]
I am a desktop developer moving to web development. The guys who I am working with use procedural PHP, and coming from an event driven, objectified perspective (using WPF and C#.Net) I am completely ...
3
votes
1answer
205 views
Compose nested EventEmitters elegantly
I am developing a server-side JavaScript tool, and trying to do so in a modular way.
I have a Parser class that is an EventEmitter - you call parse and it will eventually emit data and end events. It ...
5
votes
2answers
560 views
Should an event listener be called if attached after the event has already fired?
Should an event listener be called if it is attached after the event has already fired? What if the event will only be fired once?
The first example that comes to mind is the ready event in jQuery. ...
