android – 3-tier architecture diagram for e-commerce mobile application

I am working on a 3-tier architecture diagram for an e-commerce mobile application, mainly an Android application.

Since I come from a strong technical background with little to no experience in design or documentation, I am not sure if the diagram and explanation includes all that it should and if it is structured properly with components positioned in their right layer.

This is what I came up with after some knowledge gathering and research:

enter image description here

Presentation Layer:

Components – Screens,Forms, Buttons, Notifications etc..

Presentation Logic – UI specific for different screen sizes, form factors, language and region specific UI/Theme etc..

User Interactions – Text input, buttons click, permissions, enable GPS etc..


Business Layer:

Application Facade – Rest APIs, database APIs

Components – ViewModels that do the validation, helper classes to parse and cleanup the data

Entities – Data models like User, Product, Order, PaymentDetails etc..

Workflow – Data flow between the Entities, like adding a product to cart, checking out a cart etc..


Data Access Layer:

Local Database – SQLite to show data when the application is not connected to internet

Persistent Storage – File storage for any image caching, User preferences etc..

Server Database – Remote database and file system which is used by the Rest APIs


Common:

Security – Secure communication between the layers like database encryption, secure payment, HTTPS protocol etc..

Operational Management – Logging Analytics, crash reports etc..

Communication – Interfaces to update the UI, sync the database, send/receive notifications etc..


I would like to know if I am missing anything fundamental or if there are any structural flaws in the diagram. Thanks!

database design – ERD Help: While Designing a ER Diagram for a basic Car Rental system, Is the reservation entity weak? are all the relationships to this entity weak?

I am trying to design an ER diagram with the following conditions.

Entities and attributes:

CUSTOMER: The CUSTOMER entity holds all information about the customer. It must store customer name, customer ID, phone and physical address.

VEHICLE: The vehicle entity holds all about the car. It must store license plate, vehicle name, model number, vehicle type (SUV, Sedan, Minivan, etc.) and locations at which the vehicle is available.

LOCATION: The LOCATION entity holds all information about the physical address where the cars are available. It must store the location ID and physical address.

RESERVATION: The RESERVATION entity stores all the information about the reservation made by the customer. It must store details like reservation ID, customer ID, license plate, location ID, pickup date and return date.

Relationships:

Each customer might have zero or many reservations, but each reservation must have been made by one and only one customer.
• Each location may have zero or more reservations and each reservation must have one and only one location.
Each reservation must contain one and only one vehicle.
Each customer must have one and only one vehicle and each vehicle should be given to one and only one customer

Notes:
Please identify the primary and foreign keys in the entities.
Show associative entities where applicable.
Differentiate strong and weak relationships in the ER diagram using the appropriate representation.

Can someone please guide me here on creating this ERD

visualization – How can I change the Mathematica programming for creating a Venn Diagram?

I am working on using Venn diagram to explain logic and logical connections between sets. After coming upon these answers: Create a Venn Diagram,
How to plot Venn diagrams with Mathematica?,
which I found very helpful I was wondering if there is a way to convert the statement All Bananas are Tasty. (All Bananas are elements of Tasty or Bananas $iff$ Tasty) and All Apples are Tasty (Apples $iff$ Tasty) into a Venn diagram with three circles labeled?

The difference between this question and the questions above is I am wondering how to label an area of the Venn diagram, as well as how to instead of using $A_1$ and $A_2$ as values as explained in this good well-explained answer https://mathematica.stackexchange.com/a/2557/76873 by user https://mathematica.stackexchange.com/users/495/fjra use the values Bananas, Apples, and Tasty.

I am also wondering if there is a way to color the Venn diagram, possibly using PlotStyle or a graphics primitive?

boolean computation – How can I change the coding for creating a Venn Diagram?

I am working on using Venn diagram to explain logic and logical connections between sets. After coming upon these answers: Create a Venn Diagram,
How to plot Venn diagrams with Mathematica?,
which I found very helpful I was wondering if there is a way to convert the statement All Bananas are Tasty. (All Bananas are elements of Tasty or Bananas $iff$ Tasty) and All Apples are Tasty (Apples $iff$ Tasty) into a Venn diagram with three circles labeled?

The difference between this question and the questions above is I am wondering how to label an area of the Venn diagram, as well as how to instead of using $A_1$ and $A_2$ as values as explained in this answer https://mathematica.stackexchange.com/a/2557/76873 by user https://mathematica.stackexchange.com/users/495/fjra use the values Bananas, Apples, and Tasty.

I am also wondering if there is a way to color the Venn diagram, possibly using PlotStyle or a graphics primitive?

Class diagram of an Hotel Management System

I am given the following system description :

Consider a hotel
management system to manage a group of 5-stars hotels. If this system is modelled using OOP methodology, and the classes are identified as Hotel, Trip, Room, VIP Room, Regular Room, Suite, Customer, Payment, Cash_Payment, Credit_Debit_Payment, Reservation.

Now I need to draw its UML class diagram, here is my solution :
enter image description here

I have related the customer class indirectly with the Hotel using the reservation class which is related to the Room class and Trip class and both of them are related to the Hotel class is this a valid solution ?. Also, did I miss any composition or Aggregation relationships? Finally, are these multiplicities right? I am just participating in some problems for class diagrams to understand it, so please help me.

algorithms – Transition from Delaunay triangulation to Voronoi diagram

In mathematics and computational geometry, a Delaunay triangulation for a given set P of discrete points in a plane is a triangulation DT(P) such that no point in P is inside the circumcircle of any triangle in DT(P).

A Voronoi diagram is a kind of tesselation that divided the medium into polygons in 2D and polyhedrons in 3D.

I have Delaunay triangulation of a three-dimensional space. For the transition from Delaunay to Voronoi, firstly center of circumsphere of Delaunay tetrahedron is found (vertice) then edges linked to this center are determined. Founded edges are formed polyhedron faces.

I want to know: is there any algorithm that finds polyhedron faces from edges?

I will appreciate any comments that give me a little help and forgive me for writing shortcomings.

uml – Activity Diagram Feedback

I need some consultation on the correctness of the activity diagram, that I have created for the following scene:

I have one dictionary structure, that I want to compare to other dictionaries. for the explanation I want to name it as sentences. So, I am comparing one sentence to other multiple sentences by iterating through them. I am counting the words that match, as bestCount.

Now at first, the very first sentence will be counted as bestDict. then go to the second sentence, and if the bestCount is greater than the previous one, then count the second sentence as bestDict and if not don’t change the bestDict, which means the first sentence should be our bestCount.

In case, if there are multiple sentences, which have the same bestCount, for example if our second sentence was selected as bestDict, where bestCount is 5, and our third dictionary also has, 5 bestCount, then I compare the size of these two sentences and select the bestDict, which has the smallest size.

I am doing this for each one till the end. I have created the following diagram, and need some consultation, regarding the correctness of it, to what I have told in the scene.

Thank You.

enter image description here

design – What is a good way to understand the relationship between a UML class diagram and an implementation?

At my uni the software design teachers like to ask questions about UML diagrams, such as this:

In the following class diagram, can class Bar’s bar() operation modify Bar’s b attribute? Can it modify class Foo’s a attribute?

UML class diagram

Now as far as I know, static operations may only modify a class’s static attributes. Bar’s b is not static. Does this also apply to other classes’ attributes, such as Foo’s a?

But still, how about this?

class Bar {

        public static void bar()
        {
                var bar = new Bar();
                bar.b = something;
        }

}

It seems possible to implement bar() so that in its body it instantiates a Bar object and then modify its non-static attribute. The same could be done with instantiating a Foo and modifying its a.


I know I should differentiate between an example Java implementation and the ‘abstract’ UML diagram, but I can’t help but think of what makes sense and can be implemented while looking at these diagrams.

So what is an intuitive way to think about this? Is there anything that ‘prevents’ me from implementing the code I provided in the diagram?

design – What kind of UML diagram should I make for a large project

My colleagues and I are somewhat in a predicament.
We are interns and trying to figure out what kind of UML diagram we should use to properly display our big and complex project. The project is made in C++, Py, Bash, Java.

The project contains 3 lesser projects

  • A project which lets microcomputers receive radio data and execute said data upon receiving the radio transmissions
  • A project which facilitates the other two lesser projects with the radio data
  • A project which displays the received coordinates from the radio data in an external program

One colleague of mine already made a component diagram for his part. Its expected that all of us eventually make a shared diagram which displays the entire concept…
This is pretty hard for us to wrap our heads around. The project is going fine but documenting it is something else entirely. Hence our question regarding which UML diagram to use!

Thank you for your time and happy holidays!

beginner – Where I can make an ERD, RDM diagrams. Is there any software or website from which I can make a database using the ERD/RDM diagram file?

I am new to PHP, SQL, etc. I am making a school management system website and database. I don’t know where I saw somewhere that we can make databases by just exporting the ERD/RDM diagram in the .sql format but I don’t know how and where.
I want guidance so that I can make my project immediately.
I didn’t code anything since I’m confused.
If anyone of you suggests some improvement in the diagram, please mention it, it will be appreciated!

create database school_management_system;
create table students;
insert into students;

School Management system