AMQP with mTLS with AMQPNETLite

Posted by on February 12, 2025 No comments

Every now and then you are thrown into projects were you might not be the perfect pick from start. I seldom work with .NET and this project was just that 🙂 I was asked to create a small .NET proof-of-concept application in C# that fetches messages from a AMQP broker using mTLS authentication. I post the solution so it might benefit someone else (did not find much about this on Google)
Here is the result:

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01using Amqp;
02using Amqp.Sasl;
03using Microsoft.Extensions.Logging;
04 
05 
06namespace DotNETApps
07{
08    class Program
09    {
10        static async Task Main(string[] args)
11        {
12            using var loggerFactory = LoggerFactory.Create(builder =>
13            {
14                builder
15                    .AddConsole()
16                    .SetMinimumLevel(LogLevel.Debug);
17            });
18 
19            ILogger logger = loggerFactory.CreateLogger<Program>();
20 
21            logger.LogInformation("Application started.");
22 
23            Address address = new Address("amqps://mydomain:5671");
24 
25            var factory = new ConnectionFactory();
26            factory.SSL.ClientCertificates.Add(new
27                  System.Security.Cryptography.X509Certificates
28                         .X509Certificate2("c:\\myclientcert.pfx", "secret"));
29 
30            factory.SASL.Profile = SaslProfile.Anonymous;
31 
32            try {
33                logger.LogInformation("Connecting to broker...");
34                Connection connection = await factory.CreateAsync(address);
35                logger.LogInformation("Connected to broker.");
36 
37                Session session = new Session(connection);
38                ReceiverLink receiver =
39                         new ReceiverLink(session, "receiver-link", "MYQUEU");
40 
41                Console.WriteLine("Receiver connected to broker.");
42 
43                Message message = await Task.Run(() =>
44                          receiver.Receive(TimeSpan.FromMilliseconds(2000)));
45 
46                if (message == null)
47                {
48                    Console.WriteLine("No message received.");
49                    receiver.Close();
50                    session.Close();
51                    connection.Close();
52                    return;
53                }
54 
55                Console.WriteLine("Received " + message.Body);
56                receiver.Accept(message);
57 
58                receiver.Close();
59                session.Close();
60                connection.Close();
61            }
62            catch (Exception e)
63            {
64                logger.LogError(e, "An error while processing messages.");
65            }
66 
67            logger.LogInformation("Application ended.");
68        }
69    }
70}

Tested on Windows 10, AMQPNETLite v2.4.11, .NET 8.0 and Visual Studio Code 1.97.0

Apache Camel OpenAPI Contract-First Example in SpringBoot

Posted by on December 3, 2024 Comments Off on Apache Camel OpenAPI Contract-First Example in SpringBoot

Contract-First means what the name implies that we write the contract between client and server first and implement the code for it after. This is a good way to break up the task of creating an API in smaller parts which can be handled over multiple professions. For example, the OpenAPI specification can be created by an IT-architect and the implementation can be done by a programmer, and lastly the API documentation can be carried out by an communications expert.

In this article I’m going to build a simple OpenAPI implementation in Apache Camel and it’s rest-openapi component in a SpringBoot application.

1. We start with the API Specification:

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01openapi: 3.0.3
02info:
03  title: Basic API
04  version: "1.0"
05paths:
06  /test:
07    get:
08      operationId: test
09      responses:
10        200:
11          description: Default response
12  /user/{userId}:
13    get:
14      operationId: getUser
15      parameters:
16        - name: userId
17          in: path
18          required: true
19          schema:
20            type: string
21      responses:
22        200:
23          description: Default response

A few things to note here:
/test – this is the url that the client will use
operationId for the test endpoint – is the route that will receive the call from url above
/user/{userId} – url with parameter that the client will use
operationId – here the operationId does not match the url, which is fine. The call will go to the route direct:getUser with the userId in a header on the message seen below

2. Implementation of the Camel solution

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01package com.example.contract_first_example;
02 
03 
04import org.apache.camel.builder.RouteBuilder;
05import org.springframework.stereotype.Component;
06 
07 
08/**
09 * A Camel Java DSL Router for Contract First Example
10 */
11@Component
12public class MyApp extends RouteBuilder {
13    @Override
14    public void configure() throws Exception {
15        rest().openApi().specification("hello-rest-service.yaml");
16 
17        from("direct://hello")
18            .setBody().constant("Hello from Camel!");
19 
20        from("direct://getUser")
21            .process(exchange -> {
22                exchange.getMessage().setBody("Hello from user: "
23                             + exchange.getMessage().getHeader("userId"));
24            });
25    }
26}

3. Now the implementation is done and we move on to testing:

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1PS C:\Users\niklas> curl -XGET localhost:8080/hello
2Hello from Camel!
3PS C:\Users\niklas> curl -XGET localhost:8080/user/11
4Hello from user: 11

And that is all there is – pretty simple, like most things in the Camel world 😉

Tested on Java 17, OpenAPI 3.0, Apache Camel 4.9.0 and SpringBoot 3.3.4 in a Windows 10 environment

Example of the Builder Pattern in Java

Posted by on August 5, 2024 Comments Off on Example of the Builder Pattern in Java

A small example of the Builder Pattern in Java. We are going to build cars with different colors, brands and models 🙂

Car.java

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01public class Car {
02    private String brand;
03    private String color;
04    private String model;
05 
06    public String getBrand() {
07        return brand;
08    }
09    public void setBrand(String brand) {
10        this.brand = brand;
11    }
12    public String getColor() {
13        return color;
14    }
15    public void setColor(String color) {
16        this.color = color;
17    }
18    public String getModel() {
19        return model;
20    }
21    public void setModel(String model) {
22        this.model = model;
23    }
24}

CarBuilder.java

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01public class CarBuilder {
02    private Car car;
03     
04    private CarBuilder() {
05        car = new Car();
06    }
07    public static CarBuilder aCar() {
08        return new CarBuilder();
09    }
10    public CarBuilder withBrand(String brand) {
11        car.setBrand(brand);
12        return this;
13    }
14    public CarBuilder withColor(String color) {
15        car.setColor(color);
16        return this;
17    }
18    public CarBuilder withModel(String model) {
19        car.setModel(model);
20        return this;
21    }
22    public Car build() {
23        return car;
24    }
25}

With these two classes above we can now build some cars:
Main.java

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01public class Main {
02    public static void main(String[] args) {
03        Car myFirstCar = CarBuilder.aCar().withBrand("Volvo")
04                                          .withColor("Blue")
05                                          .withModel("XC90")
06                                          .build();
07 
08        Car mySecondCar = CarBuilder.aCar().withBrand("Skoda")
09                                           .withColor("Grey")
10                                           .withModel("130L")
11                                           .build();
12        System.out.println("My first car was a " + myFristCar.getBrand());
13        System.out.println("My second car was a " + mySecondCar.getBrand());
14    }
15}

Should print:

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1My first car was a Volvo
2My Second car was a Skoda

Tested on Ubuntu 20.04.4 LTS and Java 21