Questions tagged [command-message]
13 questions
16
votes
3 answers
In CQRS/ES, can a command create another command?
In CQRS/ES, a command is sent from the client to the server and routed to the appropriate command handler. That command handler loads an aggregate from its repository, and calls some method on it, and saves it back to the repository. Events are…
magnus
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14
votes
2 answers
How to determine if a message should be a command message or event message?
Two enterprise integration patterns are the command message and the event message. I am working on a system in which we use messaging not only for integration with other systems, but for internal communication between services. It's supposed to be…
Kazark
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11
votes
2 answers
Where should you validate the state of "other" aggregates?
Scenario:
A customer places an order, then, after receiving the
product, provides feedback on the order process.
Assume the following aggregate roots:
Customer
Order
Feedback
Here are the business rules:
A customer can only provide feedback on…
magnus
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3
votes
1 answer
Message Mapper Design Considerations
Long question context, skip to tl;dr for the meat of it.
I am designing an integration between two web applications, and have come to the conclusion that a message pattern would be an appropriate solution to the problem. The gist of the requirements…
Aj_76
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2
votes
1 answer
Passing Meta info from Command through Aggregate to Event
I have a CQRS system in development that passes the Command to a CommandHandler, which gets an Aggregate from a Repository, and calls a method with the properties of the Command (converted to ValueObjects).
The method then creates the Event…
designermonkey
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2
votes
2 answers
Building a string parser for user command and control?
My goal is to build a command parser that has basic syntax and multiple possible branches at each point. These commands come from users of the system and are text input (no GUI). The basic syntax is base_command [sub_command [optional_parameters]],…
Andy
- 123
- 6
1
vote
1 answer
How to implement format-complying logging system?
We have a system that generates lots of logs and we have to somehow maintain logging workflow in a project.
The 'strict' (let's assume it's strict) requirement is that there should be a document describing format for each message and each message…
user143982
1
vote
2 answers
Reading the result of your command with the Command Pattern
I am currently looking into developing a new system utilizing hexagonal architecture and the commandpattern facilitated by a commandbus like tactician (it's a PHP system).
Now I really like the idea of the commandpattern but what I don't get yet is…
Tim Strijdhorst
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1
vote
1 answer
Does my Remote Procedure and Event Protocol complete?
I recently wrote a protocol I call RPEP (https://github.com/Tixit/RPEP), partially in response to the unfortunately named WAMP protocol. I'm looking for feedback as to whether the protocol is specified completely enough.
In particular, I'm…
B T
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1
vote
1 answer
MVC Communication Pattern
This is kind of a follow up question to this https://stackoverflow.com/questions/23743285/model-view-controller-and-callbacks, but I wanted to post it separately, because its kind of a different topic.
I'm working on a multiplayer cardgame for the…
Kedu
- 113
- 2
0
votes
1 answer
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 that we don't control, we'll do a HTTP post and get…
floriank
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0
votes
2 answers
A command as the intended effect of POST versus as the side effect of PUT
The intended effect (semantics) of the POST method is resource specific, e.g. executing a command with arguments:
POST /command HTTP/1.1
{"parameter-1": "argument-1", "parameter-2": "argument-2"}
The intended effect (semantics) of the PUT method…
Géry Ogam
- 602
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0
votes
1 answer
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 be able to dispatch further…
TiMESPLiNTER
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