Questions tagged [event]

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How to implement event payload isolation in an event driven architecture?

I have an event, let's say order.placed The payload consists of some general information about the order and 3 confidential fields. For example part of the message should only be visible to consumer A,...
Kamil Latosinski's user avatar
1 vote
3 answers
77 views

Refactoring Controllers publishing different events with MediatR library

I have Controller that basically publishes different Event based on some input criteria, simplified version of the logic is here: [HttpPost] public async Task<ActionResult> Create(...
Velocoder's user avatar
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1 answer
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How do model a command that returns a result in an event storming?

I have a discussion with a colleague regarding how to model a command that immediately gets an answer to it's HTTP POST request back. In this specific case we do an API call to a 3rd party IDP API ...
floriank's user avatar
  • 471
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0 answers
124 views

Event sourcing, bulk update and storing multiple events vs one event with multiple ids

Event-sourcing often implies to have one row per aggregate id : event_id event_type entity_type entity_id event_data 102 OrderCreated Order 101 {...} 103 OrderUpdated Order 101 {...} This is ...
djflex68's user avatar
1 vote
1 answer
375 views

AWS multiple SQS queues on one bucket without fanout

I am coming into a project that uses an Amazon S3 Bucket for a process. For my application, I need to know (within a reasonable time - order of a few minutes, at most) whether a new file has beeen ...
SRNissen's user avatar
  • 161
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1 answer
335 views

Observer pattern using static events

I'm working on a game prototype: I have a Cell class which, given a mouse click on its collider, can raise an event that should be listened in two different modules: Camera and UI. The Observer ...
vandermies's user avatar
0 votes
1 answer
370 views

Ordering events across multiple topics in a distributed system

Our platform is growing in the number of events we're raising, and these different events are often related to one another: ProductCreated ProductUpdated ProductTakenOffSale ProductPutOnSale ...
FBryant87's user avatar
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2 answers
101 views

How to handle the consumption of multiple event types when timing is crucial?

I have a distributed platform which allows customers to make purchases, and the items which are purchased are stored in an inventory: Sales app -> PurchaseEvent -> Inventory app The Sales app ...
FBryant87's user avatar
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0 answers
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Kafka : Is sending some payload data (identifier) in headers considered a good practive?

I am wondering about some architectonical decisions in our system. There are situations where we are sending import business events through kafka which should be performed in every case. All the cases ...
Drake's user avatar
  • 1
3 votes
2 answers
197 views

How to propagate seldomly changing data in a distributed system

We store data – some kind of metadata like car manufacturers or types of computer parts – in one of our applications. This data changes rarely. Let's say it changes once every two weeks. This data is ...
Harold L. Brown's user avatar
0 votes
1 answer
161 views

Is this a good use of events?

At my company we are revising some backend architecture. I think I have identified a use case where event streaming (for example with Apache Kafka or RabbitMQ) makes sense. Because me (and everyone ...
Puck's user avatar
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2 votes
0 answers
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How to define the data model in an event-based infrastructure

After my team went all-out on the microservice paradigm with an emphasis on message passing, I'm having trouble defining and keeping track of all the events in the system. I've read some guides on the ...
Dzeri96's user avatar
  • 129
-2 votes
1 answer
193 views

How do I design an event bus to both publish and consume events to an external message broker

I have an application that needs to publish events to an event broker and consume events from the event broker. I want to do this with an event bus. This event bus should have one public method: ...
danjfoley's user avatar
1 vote
2 answers
625 views

How do event sourcing services recreate the state of an entity?

I'm reading about event sourcing and have a question regarding the recreation of an entity state. For a simple scenario, lets say we have Order events such as OrderCreated / OrderUpdated / ...
jhthewow's user avatar
2 votes
1 answer
4k views

Event bus vs PubSub

I have been using queues and PubSub patterns for years but never really came across the terminology "event bus". After some googling I didn't really find a clear distinction between "...
Frankster's user avatar
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3 answers
450 views

Should I send the current or previous state with my state changed event?

I have an event that is raised when my job objects change state (e.g. initializing, running, complete, etc). The event is to be invoked from my set method in the State property, but before I make it ...
Hazel へいぜる's user avatar
7 votes
3 answers
3k views

How do desktop applications get notified of events over the internet?

I would like to display something on my desktop by tapping a button on my mobile app. For example, there is a "show cat" button on my mobile app. When I tap that button, a new window should ...
LevelRin's user avatar
3 votes
4 answers
1k views

C# How to avoid memory leak in this case

I've got a Window, which gets a viewmodel instance injected into its constructor. The window sets its DataContext to that viewmodel. The viewmodel contains a command to "submit" the window ...
user2190492's user avatar
0 votes
2 answers
384 views

Scaled services and order of events sent as messages (using a broker)

How would you go about making sure that "events" sent as messages to any sort of broker (Kafka, RabbitMQ etc) from multiple instances of the same service (load balanced) are actually added ...
Inx51's user avatar
  • 273
0 votes
1 answer
81 views

Long-running jobs in an event-driven environment with constrained max-execution-duration

Hello we have an async event-driven system (kotlin, spring cloud stream, rabbitmq) where there might be an event FooPayloadArrived, published by an ingress rest-controller. Processing this ...
hotzen's user avatar
  • 115
-1 votes
2 answers
104 views

Applications interested to the same event and concurrency

I have an event pubblished in a bus(rabbit) and two application that are subscribed to this Event. public class CreationEvent { public int CreationEventID {get; set; } ... other properties } ...
user3401335's user avatar
-2 votes
1 answer
113 views

What is the proper diagram to describe an event subscriber final graph?

I'm working on a microservice application and I need to describe the complete execution graph of a specific event being published, where each node in the graph is a specific microservice subscription ...
underthevoid's user avatar
3 votes
3 answers
245 views

Coping with lack of infinite retention event broker in event driven architecture

I am reading “Building Event Driven Microservices”. It states a requirement of the event broker is: Infinite retention: Event streams must be able to retain events for an infinite period of time. ...
MattHH's user avatar
  • 119
0 votes
3 answers
311 views

Ingest data from our partener : API POST vs Event Driven Architecture

I am in the process of carrying out a software architecture for my client, in fact THE HISTORY OF THE REQUIREMENT : MY PARTNER SEND cvs files via MFT to MY CLIENT , many times a day . MY CLIENT has a ...
Benhassine Mohamed's user avatar
2 votes
1 answer
219 views

Eventing: Determine if Set of Messages has been Processed

Given a Set of messages sent to a Queue, what are good ways to determine all of the messages have been processed? Constraints: Large number of messages Other messages besides those in the Set will be ...
MattHH's user avatar
  • 119
7 votes
1 answer
1k views

How to represent a loop in Event Storming?

I recently ran an Event Storming session and a scenario came up where we needed to represent a loop within the process. The events and commands needed to happen iteratively until a condition is meant ...
secondbreakfast's user avatar
0 votes
1 answer
166 views

How to deal with massively concurrent events?

I got the following interview question: Say the company has this event, where we will create a button on a website and only the first ten clicks will be accepted and win a prize. Assume that there a ...
amazingsaluyot's user avatar
1 vote
1 answer
423 views

What are the best way to publish application event in a spring boot application?

My goal is to collect/publish different types of information from the application. We use Kafka for the event bus. Consider the following sample code. class UserService { public User ...
Muztaba Hasanat's user avatar
-1 votes
1 answer
109 views

How to subscribe to collection edits happening in a different thread?

I'll be using C# for my example since this is what I am using, but the problem is sort of generic. My app code takes a collection of Foos (externally populated and edited) to do some processing, and ...
Filippo Bannò's user avatar
0 votes
3 answers
1k views

How to handle data inconsistency in microservice architecture?

Let's assume we have two services - user and auth with a message broker in between. user service handles CRUD action on user entity and auth service handles authentication. When a user is created/...
CodeBreaker's user avatar
-4 votes
1 answer
570 views

How to create an Event-Driven Architecture with many external sources

I work for this Accounting company - as a Product Owner - that uses several external services (one for Contract management, another one for Accounting Demands management, a third one for Financial ...
Otto Neres's user avatar
0 votes
0 answers
96 views

Experiences with coarse grained and fine grained message designs in an ECST pattern

I am currently facing a dilemma in the design of a message oriented distributed system following an Event Carried State Transfer pattern. This is essentially a "near real time ETL" used to ...
allmhuran's user avatar
  • 316
2 votes
1 answer
113 views

Ops in event-driven paradigm

TL;DR event-driven system seems to focus on a highlevel view of the system ("error rate is 0.5%"). How are IT operations supposed to locate and remedy individual issues in such systems? In ...
Yuri's user avatar
  • 211
0 votes
0 answers
259 views

WPF MVVM EventAggregator Cons?

We have a wpf mvvm application with a lot of "panes". Just like the draggable panes in visual studio for example. All of these are individual usercontrols with their own viewmodels and im trying to ...
GradientJagger's user avatar
4 votes
1 answer
3k views

When to publish domain events when handling transactions in the application service

This is something that has been bothering me for quite some time, I tried different approaches over the past year but I always come back to reflect on this, so I'll throw myself out here ! So, first ...
TanguyB's user avatar
  • 467
0 votes
1 answer
646 views

Message bus: should an event handler trigger other commands?

Given I have a message bus that can handle commands and events. A command handler can dispatch an event. But should an event handler be able to dispatch another command? Or should event handlers only ...
TiMESPLiNTER's user avatar
-2 votes
2 answers
89 views

How to call the API once per event-message?

I have X number of servers in NLB listening to an event that gets published by a backend system. I am planning to develop a windows service that listens to the event and then calls an internal API. ...
user9969157's user avatar
0 votes
3 answers
289 views

How to implement a chain of events on a tree's CRUD operations?

I am working on a project in which I have a tree with 4 layers and the hierarchy is like this. Customer -> Site -> Location -> Guardroom In DB each entity has its own table and the child ...
Ricardo Duran's user avatar
3 votes
5 answers
2k views

How to resolve cyclic dependencies in Event-driven systems?

Consider two services (bounded contexts by DDD): Sales Billing Sales is responsible for creating orders and Billing for handling payments. Sales tracks orders and Billing holds payments: Sales ...
Barney's user avatar
  • 211
2 votes
1 answer
65 views

Remove unwanted parameter from event

I've run into a common annoyance where I'll have an event that sends a parameter, but some consumers of the event don't need the parameter at all. So I wrap it in another function that decouples the ...
Adam B's user avatar
  • 1,595
0 votes
1 answer
467 views

What are differences in application architecture in frontend and backend applications?

I'm pretty experienced with developing both frontend as well as backend applications, with a variety of programming languages and frameworks. I know the problem space and concepts involved in both ...
Sven's user avatar
  • 109
5 votes
2 answers
2k views

Handle failures in Event Driven Architecture

Suppose you have a bounded context with ~30 business events and, for simplicity sake, the same number of commands like ChangeUserEmailCommand -> UserEmailChangedEvent initiated from a web UI. ...
UserControl's user avatar
3 votes
2 answers
1k views

Aggregation and storage system design for user event processing?

I have a eCommerce like system which produces 5000 user events (of different kind like product search/product view/profile view) per second Now for reporting business users would like to view the ...
M Sach's user avatar
  • 267
2 votes
2 answers
762 views

Error handling in an event driven system

The context I have two components A & B, which communicate through events . Components B is responsible for long running background processes and it listens to the following event: ...
Cap Barracudas's user avatar
1 vote
2 answers
2k views

How to send queue messages to one queue in rabbitmq?

I want to use rabbitmq to share domains events between microservices. Due to the fact that queues are round-robin, I need to define one queue per event source and event consumer. For example, cars-ms ...
Sergio R.B.'s user avatar
-1 votes
2 answers
1k views

How to ensure persistence in an event-driven microservice architecture?

Right now we have a set of micro services with a client-facing gateway responsible for authentication and routing. MySQL database and RabbitMQ for the message queue. Internal services may queue up ...
Michael Yousef's user avatar
5 votes
3 answers
521 views

How to model User behaviour that can be shared between microservices in Event Driven architecture?

I have an Event Sourced system that has 3 micro services (simplified): User management - Registering a user, change password etc User account - manages debiting/crediting of the user account balance ...
Konrad Szczęśniak's user avatar
42 votes
10 answers
6k views

Applicability of Single Responsibility Principle

I recently came by a seemingly trivial architectural problem. I had a simple repository in my code that was called like this (code is in C#): var user = /* create user somehow */; _userRepository.Add(...
Andre Borges's user avatar
  • 1,534
2 votes
1 answer
54 views

Where does the responsibility for clearing higher-level caches lie in a pyrimidal calculation system with caching at multiple levels?

I'm working on system that analyses non-trivial amounts of data. The analysis is pyramidal, in that various combine to make intermediate values, which in turn combine with each other and more inputs ...
Oblivious Sage's user avatar
-3 votes
1 answer
155 views

How does event.target return the DOM object?

I read through documentation and searched on google, but couldn't find a specific answer. Currently, I have an object that subscribes to a click event. I am trying to understand how a view that ...
Caelan Dailey's user avatar