Questions tagged [design-patterns]
A design pattern is a general reusable solution to a commonly occurring problem in software design.
258
questions with no upvoted or accepted answers
6
votes
2answers
1k views
Loose Coupling Presenter to View in MVP
We work in a Java shop here and our web application uses an implementation of the MVP architectural pattern. Our manager comes from a .NET world, where he has been exposed to the MVVM design pattern. ...
4
votes
0answers
94 views
Global variables and common block management in Fortran
Background
The high level overview of my situation is described here. I am breaking it apart into smaller, specific questions, such as this one, regarding extensive use of global variables in a ...
4
votes
0answers
115 views
Best design pattern/approach for a Factory which needs multiple types of input
I want to develop a Factory of INotifications.
public interface INotification
{
string Text { get; }
string UserId { get; }
NotificationType NotificationType { get; }
}
The problem is, ...
4
votes
1answer
627 views
Handling common code among presenters
I'm facing some issues related to code duplication when following MVP architectural pattern in an Android project that I'm working with.
My project structure is separated by packages: data, domain, ...
4
votes
1answer
253 views
How to set up a sql database to cater for user records, group records and default records?
Outline
I have an application that loads data from a database. I'm not talking about client data here though, I'm talking about application configuration. The database will therefore come with some ...
4
votes
0answers
6k views
Assembler vs Entity Translator and Entities vs DTO
I was hoping that someone could explain the exact difference between an Assembler and Entity Translator.
Martin Fowler describes the Assembler as a sort of Mapper(?) which converts DTOs into Domain ...
4
votes
0answers
455 views
Separate settings and implementation class hierarchies
We use XML serialization to store class settings. Each setting-class has (but doesn't reference) corresponding implementation-class. Therefore we can easily make a "settings dll" without any ...
4
votes
0answers
130 views
Environment that enables variable constraint checking and creation
Currently, I'm working on a system that enables users to add Tag's to available TagTypes on specific pages. For instance, we would have a TagType called "Installer" and the user wants his name ...
4
votes
1answer
6k views
Unit Of Work with multiple database context
I have created an application (net core 2 & ef core) with Unit Of Work and Generic repository pattern. I used to have one database context but due to some business logic I had to create a second ...
4
votes
3answers
409 views
Pattern for endpoint that routes requests?
I am building a service that will push notifications to many other services. It has a couple of different notification types that each consumer may care about, but likely will not care about all of ...
3
votes
1answer
50 views
Need technical advice about passing data through UINavigationController
First of all a small introduction, im relatively new to Swift and to programming in general, been doing it for the last year and loving every and each new thing of this vast world.
My post is about ...
3
votes
2answers
177 views
Do I use Repository or Service Object to Perform Logging?
I'm working in Java Spring, and I have typical service and repository layers. The repository grabs a JSON; passes it along to the service; service maps the repository response to a DTO.
I also need ...
3
votes
1answer
372 views
Is Enum Polymorphism bad for DAO Methods?
I have been going back and forth in a discussion about polymorphic enums to call different DAO methods depending on enum entry, and I haven't been able to get a common agreement on this subject.
Lets ...
3
votes
0answers
85 views
How should domain model entities expose information about the current state of their properties?
I'm new to DDD, so please bear with me.
I am trying to design a domain model around an extremely large and complex existing system, where most of the current "domain" logic is either in the UI or in ...
3
votes
0answers
128 views
Should I use gRpc in my business layer?
I'm moving from REST APIs to gRpc but having a hard time figuring out how to structure my logic.
The basic layout of my solution is having a business layer/API and a few different front-ends (Windows ...
3
votes
0answers
129 views
Data processing pipeline design for processing data
I have a use case for which I need to build a data processing pipeline
Customer contact leads data coming from different data sources like csv, data base, api has to be first mapped to a universal ...
3
votes
0answers
96 views
Python3: How to change the design of a class hierarchy to improve access to objects there buried?
I asked this question already at stackoverflow together with a serialization related part and at codereview for the design part only. Since the design related part receives no answers or comments on ...
3
votes
0answers
62 views
How does “redux” decouple the different components so they can be tested separately in unit tests?
In the past we saw a big move from traditional MVC to MVVM for user interfaces:
One of the primary motivations for MVVM is that the view and viemmodel are competely indepedently of each other and ...
3
votes
0answers
74 views
Memento and releasing resources
Let's suppose we have a class whose state has to be saved and later restored, and we resorted to the Memento pattern for that.
What if the state includes resources that have to be explicitly ...
3
votes
1answer
284 views
Designing a flexible search API response
Quick Summary
I'm building a search micro-service that will allow searching across different types of resources in a particular system (e.g. blog posts, users etc.). The API that will be exposed will ...
3
votes
0answers
44 views
Parse track meet output file result
I am building out a parser for a well-known track & field meet management software output file (sample output).
I can parse this manually, and put items into my object model (overview below), but ...
3
votes
1answer
723 views
Balance between aggregate boundaries and domain consistency in DDD
Designing an Aggregate and choosing an Aggregate Root getting tricky for me all the time especially when it comes to ensuring right transactional contexts and consistency constraints so I'm wondering ...
3
votes
0answers
372 views
How to separate data layer from business layer?
My current .NET project looks like below:
Solution (.sln)
--BusinessProject A (.proj)
--BusinessProject B (.proj)
--DataLayer (.proj)
--A separate project calling ExternalService 1 (folder)
--A ...
3
votes
0answers
420 views
Fetch data in parent vs fetching data in child
I know that I want to develop a React App like so:
<PhotoPage>
<FeedFilter/>
<PhotoFeed/>
</PhotoPage>
Without using Redux, I know that I need to fetch a dataset of ...
3
votes
0answers
83 views
Nested containers with subclasses
I have nested containers A and B. The attributes are there to show that classes have some other members. One of my functions f takes another container of such containers (let's say vector again).
...
3
votes
0answers
346 views
Perfect video processing pipeline?
I'm working on a modular video processing pipeline. It's currently presented as a tree of modules. Each module has a set of "results" and can dynamically request data results from other modules. Each ...
3
votes
0answers
1k views
Dependency Injection and class Inheritance
The project I am working on for about a year now was used to create a new mysqli connection to the database each time there was a Query to the database. In order to quickfix this problem at places ...
3
votes
0answers
557 views
Two-way adapters
In GoF there is a two way adapter concept:
A potential problem with adapters is that they aren't transparent to
all clients. An adapted object no longer conforms to the Adaptee
interface, so ...
3
votes
0answers
298 views
Anemic Domain Model Developer thinking about a rich domain model
Martin Fowler talks about the Domain Model where the Business Logic Layer contains classes that contain state and behaviour. As far as I am concerned this means:
1) Controller calls a class in the ...
3
votes
0answers
429 views
Mocking third party web service
I am working on a project to create a wrapper library which will be used to interact with a web service provided by the client's IT team. The reason for this library is that we interact with this ...
3
votes
0answers
1k views
Multiple inheritance in ASP.NET MVC Controller
In one case BaseWizardController should implement background functionality of BaseController->BaseConsumerController, in other case it should implement only BaseController.
Any ideas how can I do ...
3
votes
0answers
597 views
Building a generalized notification system: passive vs. active
Recently, I've tried my hand at building a notification system, but I quickly found that notifications are tricky things, especially in the context of building a general model. The diversity of what ...
3
votes
0answers
67 views
Should my application call statsd directly or should I call statsd based off logs?
I'm planning on incrementing counters in statsd based of various events within my application. I have logging in place for these events. So, from my viewpoint I have two options:
Update the ...
3
votes
0answers
585 views
Hierarchical ViewModels and tracking IsDirty/PropertyChanged events
I have a set of ViewModels depicted like in the below picture.
And, I have a couple of commands AcceptCommand, CancelCommand in the Top Level View Model that are bound to Apply, Cancel buttons ...
3
votes
0answers
884 views
ZeroMQ and Majordomo protocol
I am learning ZeroMQ and came across the Majordomo Protocol. I am wondering if I'm understanding this correctly, is the use case the same as.. for example.. the Microsoft Azure AppFabric service? ...
3
votes
0answers
516 views
How can I put multiple hierarchical forms in a single web page and avoid making it a mess?
We are a group of developers working on a web application that accepts forms filled and sent by our users and present it in an overall view. Our main form view looks like this:
There are multiple ...
3
votes
0answers
89 views
Pattern for data types that are related yet fundamentally different in utility
Background
I'm currently working on a codebase for what is to become a forthcoming website's content "engine", where it will take in different types of standardized data (implemented with XML), parse ...
3
votes
0answers
35 views
PaypalCheckout object is composed of PaypalQuery objects. Hide PaypalQuery objects to users of PaypalCheckout?
I have a PaypalCheckout object that handles the checkout process: from initiating API calls, to providing an interface for front-end code (e.g. View/Controller).
The PaypalCheckout object handles: ...
3
votes
0answers
219 views
Looking for design pattern to represent shared state in music sequencer
I like to give lots of context, but also to state the basic question up top as concisely as possible. Feel free to read a little or a lot.
I'm working on a music sequencer, and have been happy so far ...
3
votes
1answer
128 views
How to model workflows
I'm building a helpdesk-type system, where there are:
Customer - can submit/resubmit tickets;
Manager - can review submitted tickets, assign to developers (one ticket to multiple developers), review ...
3
votes
1answer
184 views
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 ...
2
votes
0answers
85 views
Efficient BACnet device polling strategy
Example BACnet network:
Some help is needed to solve a problem around architecting an efficient method of polling BACnet devices across multiple networks (i.e. MS/TP networks) where client software ...
2
votes
2answers
38 views
Beyond configuration, allowing for flexibility on a per service call basis type of pattern
Say you have a ecommerce app, and have an API call to create an order.
OrderService.create(...);
Order creation is a complicated process, many things will happen as a result of this call:
shopping ...
2
votes
2answers
272 views
destroy object once it won't be used anymore in flyweight pattern
I want to use flyweight pattern to return the same instance of my object each time.
public class ThingFactory {
private static final HashMap<UUID, Thing> things = new HashMap<>();
...
2
votes
0answers
76 views
Design Pattern to unify similar generated classes
I have a project where I work with generated classes for some web interfaces. Some of these classes are (almost) identical and most of the functionality I need them for only use the identical parts. ...
2
votes
0answers
104 views
Third-party API wrapper in Java: how to design
Suppose, there's a site that provides an API, such as this:
Users post questions, answers on that site
You can make GET and
POST calls
There are two types of authentication: weak (only gives
read ...
2
votes
0answers
53 views
How to join two sets of 6 tables and select the list into another set of 6 tables
A1
|__A2
|__A3
|__A4
|__A5
B1
|__B2
|__B3
|__B4
|__B5
C1
|__C2
|__C3
|__C4
|__C5
Given a list of A and a list of B, we want to "join" ...
2
votes
1answer
126 views
Dynamic Object Abilities When Saving State
I have n classes that extends from a State class, the purpose of the State class is to manage the state of the extended classes. For each class we need to save it in the database, remove it and select ...
2
votes
1answer
395 views
Managing heterogeneous data
The underlying problem is one I seem to run into a lot. You have a collection of objects with some things in common, but other information about the objects may apply to some of them but not to others....
2
votes
0answers
78 views
Coupling form fields to functionality: using a Command Bus?
I built an app where the app owner can build custom forms for each of his clients. The forms have default fields like "name" and "message" as well as custom fields for each client requirement, like "...
