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Microservice using ASP.NET Core

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10 Feb 2019CPOL
This article on microservices focused on what microservices are and their advantages over monolithic services architecture.
This article on microservices focused on what microservices are and their advantages over monolithic services architecture. The article describes how to develop a microservice using ASP.NET Core and run it via IIS and Docker container. It will demonstrate how to create a Product microservice using ASP.NET Core step by step with the help of pictures, go over Entity Framework Core Migrations, and running Run the Product Microservice (via IIS Express).

The term microservices portrays a software development style that has grown from contemporary trends to set up practices that are meant to increase the speed and efficiency of developing and managing software solutions at scale. Microservices is more about applying a certain number of principles and architectural patterns than it is about architecture. Each microservice lives independently, but on the other hand, also all rely on each other. All microservices in a project get deployed in production at their own pace, on-premise, on the cloud, independently, living side by side.

Microservices Architecture

The following picture from Microsoft Docs shows the microservices architecture style.

Image 1

There are various components in a microservices architecture apart from the microservices themselves.

Management. Maintains the nodes for the service.

Identity Provider. Manages the identity information and provides authentication services within a distributed network.

Service Discovery. Keeps track of services and service addresses and endpoints.

API Gateway. Serves as client’s entry point. The single point of contact from the client which, in turn, returns responses from underlying microservices and sometimes an aggregated response from multiple underlying microservices.

CDN. A content delivery network to serve static resources. For example, pages and web content in a distributed network.

Static Content The static resources like pages and web content.

Microservices are deployed independently with their own database per service so the underlying microservices look as shown in the following picture:

Image 2

Monolithic vs Microservices Architecture

Monolithic applications are more of a single complete package, having all the related needed components and services encapsulated in one package.

The following is the diagrammatic representation of monolithic architecture whether packaged completely or service based.

Image 3

A microservice is an approach to create small services, each running in their own space that can communicate via messaging. These are independent services directly calling their own database.

The following is the diagrammatic representation of microservices architecture.

Image 4

In monolithic architecture, the database remains the same for all the functionalities even if an approach of service-oriented architecture is followed, whereas in microservices each service will have their own database.

Docker Containers and Docker installation

Containers like Docker (and others) slice the operating system resources. For example, the network stack, processes namespace, file system hierarchy and the storage stack. Docker is more like virtualizing the operating system. Learn more about Docker here. Open this URL and click on Download from Docker hub. Once downloaded, login to the Docker and follow instructions to install Docker for Windows.

Microservice using ASP.NET Core

This section will demonstrate how to create a Product microservice using ASP.NET Core step by step with the help of pictures. The service will be built using ASP.NET Core 2.1 and Visual Studio 2017. ASP.NET Core comes integrated with VS 2017. This service will have its own dbcontext and database with an isolated repository so that the service can be deployed independently.

Image 5

Creating an Asp.NET Core Application Solution

  1. Open the Visual Studio and add a new project.

    Image 6

  2. Choose the application as ASP.NET Core Web Application and give it a meaningful name.

    Image 7

  3. Next, choose API as the type of the project and make sure that "Enable Docker Support" option is selected and that the OS type is set as Linux.

    Image 8

  4. The solution will look as shown below:

    Image 9

Adding Models

  1. Add a new folder named "Model" to the project.

    Image 10

  2. In the Models folder, add a class named Product.

    Image 11

  3. Add a few properties like Id, Name, Description, Price to the Product class. The product should also be of some kind and for that, a category model is defined and a CategoryId property is added to the product model.

    Image 12

  4. Similarly, add Category model.

    Image 13

Enabling EF Core

Though .NET Core API project has inbuilt support for EF Core and all the related dependencies are downloaded at the time of project creation and compilation that could be found under SDK section in the project as shown below.

Image 14

Microsoft.EntityFrameworkCore.SqlServer (2.1.1) should be the package inside the downloaded SDK’s. If it is not present, it could be explicitly added to the project via Nuget Packages.

Adding EF Core DbContext

A database context is needed so that the models could interact with the database.

  1. Add a new folder named DBContexts to the project.

    Image 15

  2. Add a new class named ProductContext which includes the DbSet properties for Products and Categories. OnModelCreating is a method via which the master data could be seeded to the database. So add the OnModelCreating method and add some sample categories that will be added to the database (initially, into the category table) when the database is created.

    Image 16

    ProductContext code:

    using Microsoft.EntityFrameworkCore;
    using ProductMicroservice.Models;
    
    namespace ProductMicroservice.DBContexts
    {
      public class ProductContext : DbContext
      {
        public ProductContext(DbContextOptions<ProductContext> options) : base(options)
        {
        }
        public DbSet<Product> Products { get; set; }
        public DbSet<Category> Categories { get; set; }
    
        protected override void OnModelCreating(ModelBuilder modelBuilder)
        {
          modelBuilder.Entity<Category>().HasData(
              new Category
              {
                Id = 1,
                Name = "Electronics",
                Description = "Electronic Items",
              },
              new Category
              {
                Id = 2,
                Name = "Clothes",
                Description = "Dresses",
              },
              new Category
              {
                Id = 3,
                Name = "Grocery",
                Description = "Grocery Items",
              }
          );
        }
    
      }
    }
  3. Add a connection string in the appsettings.json file.

    Image 17

    Open the Startup.cs file to add the SQL Server DB provider for EF Core. Add the code services.AddDbContext<ProductContext>(o => o.UseSqlServer(Configuration.GetConnectionString("ProductDB"))); under ConfigureServices method. Note that in the GetConnectionString method the name of the key of the connection string is passed that was added in the appsettings file.

    Image 18

Adding Repository

Repository works as a micro component of microservice that encapsulates the data access layer and helps in data persistence and testability as well.

  1. Add a new folder named Repository in the project and add an Interface name IProductRepository in that folder. Add the methods in the interface that performs CRUD operations for Product microservices.

    Image 19

  2. Add a new concrete class named ProductRepository in the same Repository folder that implements IProductRepository. All these methods need implementation.

    Image 20

  3. Add the implementation for the methods via accessing context methods.

    ProductRepository.cs:

    using Microsoft.EntityFrameworkCore;
    using ProductMicroservice.DBContexts;
    using ProductMicroservice.Models;
    using System;
    using System.Collections.Generic;
    using System.Linq;
    
    namespace ProductMicroservice.Repository
    {
      public class ProductRepository: IProductRepository
      {
        private readonly ProductContext _dbContext;
    
        public ProductRepository(ProductContext dbContext)
        {
          _dbContext = dbContext;
        }
        public void DeleteProduct(int productId)
        {
          var product = _dbContext.Products.Find(productId);
          _dbContext.Products.Remove(product);
          Save();
        }
    
        public Product GetProductByID(int productId)
        {
          return _dbContext.Products.Find(productId);
        }
    
        public IEnumerable<Product> GetProducts()
        {
          return _dbContext.Products.ToList();
        }
    
        public void InsertProduct(Product product)
        {
          _dbContext.Add(product);
          Save();    }
    
        public void Save()
        {
          _dbContext.SaveChanges();
        }
    
        public void UpdateProduct(Product product)
        {
          _dbContext.Entry(product).State = EntityState.Modified;
          Save();
        }
      }
    }
  4. Open the Startup class in the project and add the code as services.AddTransient<IProductRepository, ProductRepository>(); inside the ConfigureServices method so that the repository’s dependency is resolved at run time when needed.

    Image 21

Adding Controller

The microservice should have an endpoint for which a controller is needed, which exposes the HTTP methods to the client as endpoints of the service methods.

  1. Right click on the Controllers folder and add a new Controller as shown below:

    Image 22

  2. Select the option "API Controller with read/write actions" to add the controller.

    Image 23

  3. Give the name of the controller as ProductController.

    Image 24

  4. A ProductController class will be added in the Controllers folder with default read/write actions that will be replaced later with product read/write actions. HTTP methods are created acting as an endpoint of the service.

    Image 25

  5. ValuesController can be deleted as it is not needed.

    Image 26

  6. Add implementation to the methods by calling the repository methods as shown below. The basic implementation is shown here for the sake of understanding the concept. The methods could be attribute routed and could be decorated with more annotations as needed.

ProductController.cs:

using Microsoft.AspNetCore.Mvc;
using ProductMicroservice.Models;
using ProductMicroservice.Repository;
using System;
using System.Collections.Generic;
using System.Transactions;

namespace ProductMicroservice.Controllers
{
  [Route("api/[controller]")]
  [ApiController]
  public class ProductController : ControllerBase
  {

    private readonly IProductRepository _productRepository;

    public ProductController(IProductRepository productRepository)
    {
      _productRepository = productRepository;
    }
    
    [HttpGet]
    public IActionResult Get()
    {
      var products = _productRepository.GetProducts();
      return new OkObjectResult(products);
    }

    [HttpGet("{id}", Name = "Get")]
    public IActionResult Get(int id)
    {
      var product = _productRepository.GetProductByID(id);
      return new OkObjectResult(product);
    }

    [HttpPost]
    public IActionResult Post([FromBody] Product product)
    {
      using (var scope = new TransactionScope())
      {
        _productRepository.InsertProduct(product);
        scope.Complete();
        return CreatedAtAction(nameof(Get), new { id = product.Id }, product);
      }
    }

    [HttpPut]
    public IActionResult Put([FromBody] Product product)
    {
      if (product != null)
      {
        using (var scope = new TransactionScope())
        {
          _productRepository.UpdateProduct(product);
          scope.Complete();
          return new OkResult();
        }
      }
      return new NoContentResult();
    }

    [HttpDelete("{id}")]
    public IActionResult Delete(int id)
    {
      _productRepository.DeleteProduct(id);
      return new OkResult();
    }
  }
}

Entity Framework Core Migrations

Migrations allow us to provide code to change the database from one version to another.

  1. Open Package Manager Console.

    Image 27

  2. To enable the migration, type the command Add-Migration and give that a meaningful name like InitialCreate and press enter.

    Image 28

  3. Once the command is executed, if we look at our solution now, we see there's a new Migrations folder. And it contains two files. One, a snapshot of our current context model. Feel free to check the files. The files are very much self-explanatory.

    Image 29

  4. To ensure that migrations are applied to the database there's another command for that. It's called the update-database command. If executed, the migrations will be applied to the current database.

    Image 30

  5. Check the SQL Server Management Studio to verify if the database got created.

    Image 31

  6. When the data of the Categories table is viewed, the default master data of the three categories is shown.

Image 32

Run the Product Microservice

The service could be run via IIS Express. For example, Visual Studio default or via Docker container as well.

Via IIS Express

Choose IIS Express in Visual Studio as shown below and press F5, or click the IIS Express button itself.

Image 33

The application will be up once the browser page is launched. Since it has nothing to show, it will be blank, but the service could be tested via any API testing client. Here Postman is used to testing the service endpoints. Keep it opened and the application running.

Image 34

Install Postman if it is not on the machine and launch it.

Image 35

POST

To test the POST method (i.e. creating a new resource), select the method as POST in postman and provide the endpoint (i.e. https://localhost:44312/api/product). Then in the Body section, add JSON that has similar properties of the Product model as shown below and click on Send.

Image 36

The response is returned with the Id of the product as well.

Image 37

The "Post" method of the controller is responsible to create a resource in the database and send the response.

The line return CreatedAtAction(nameof(Get), new { id = product.Id }, product); returns the location of the created resource that could be checked in the Location attribute in the response under the Headers tab.

Image 38

Perform a select query on the product table and an added row as shown for the newly created product.

Image 39

Create one more product in a similar way.

Image 40

GET

Perform a GET request now with the same address and two records are shown as a JSON result response.

Image 41

DELETE

Perform the delete request by selecting DELETE as the verb and appending id as 1 (if the product with id 1 needs to be deleted) and press Send.

Image 42

In the database, one record with Id 1 gets deleted.

Image 43

PUT

PUT verb is responsible for updating the resource. Select the PUT verb, provide the API address, and in the Body section provide details which the product needs to be updated in JSON format. For example, update the product with Id 2 and update its name, description, and price from Samsung to iPhone specific. Press Send.

Image 44

Check the database to see the updated product.

Image 45

Via Docker Containers

Running the service could be done via Docker commands to be run in a Docker command prompt and using Visual Studio as well. Since we added the Docker support, it is easy to run the service in a Docker container using Visual Studio.

  1. Add a container orchestrator support in the solution as shown below:

    Image 46

  2. This will ask for the orchestrator. Select Docker Compose and press OK.

    Image 47

    Once added to the solution, the solution will look like the image below having docker-compose with dockerignore and docker-compose.yml and its override file.

    Image 48

    As soon as the solution is saved, it builds the project under the container and creates a Docker image. All the commands execution can be seen in the output window when the solution is saved.

  3. Open the command prompt in admin mode and navigate to the same folder where the project files are.

    Image 49

  4. Run the command docker images to see all the created images. We see that productmicroserviceimage is the latest one.

    Image 50

  5. Now run the application with Docker as an option as shown below:

    Image 51

  6. Now, run the command docker ps to see the running containers. It shows the container is running on 32773:80 port.

    Image 52

  7. Since the container is in running state, it is good to test the service now running under the container. To test the service, replace "values" with "product" in the address as shown below. Ideally, it should get the product details. But it gives an exception as shown below:

    Image 53

  8. Running the same thing under IIS Express works fine i.e. on port 44312. Replace "values" with the product to get the product details.

    Image 54

  9. Since in IIS Express the application runs fine and not in Docker container, and the error clearly shows that something is wrong with SQL Server in that it does not understand our Docker container (or it is not running under our Docker container). In this scenario, the Docker container is running as a separate machine inside the host computer. So, to connect to the SQL database in the host machine, remote connections to SQL need to be enabled. We can fix this.
  10. Open the SQL Server Configuration Manager. Now select Protocols for MSSQLSERVER and get the IPAll port number under TCP/IP section.

    Image 55

    Image 56

    Image 57

    Image 58

  11. The connection string mentioned in the appsettings.json file points to the data source as local, which the Docker container does not understand. It needs a proper IP addresses with port and SQL authentication. So, provide the relevant details i.e. Data Source as IP address, port number and SQL authentication details as shown below:

    Image 59

  12. Now run the application again with Docker as an option as we did earlier.

    Image 60

    This time the response is received.

  13. Test the same in the Postman.

    Image 61

  14. Test again with IIS Express URL.

    Image 62

This proves that the microservice is running on two endpoints and on two operating systems independently locally deployed.

Conclusion

A microservice is a service built around a specific business capability, which can be independently deployed and is called bounded context. This article on microservices focused on what microservices are and their advantages over monolithic services architecture. The article describes how to develop a microservice using ASP.NET Core and run it via IIS and Docker container. Likewise, the service can have multiple images and can be run on multiple containers at the same point of time.

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

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About the Author

Akhil Mittal
Architect https://codeteddy.com/
India India
Akhil Mittal is an Ex-Microsoft MVP(Most Valuable Professional), C# Corner MVP, Codeproject MVP, a blogger, author and likes to write/read technical articles. Akhil has an experience of around 12 years in developing, designing, architecting enterprises level applications primarily in Microsoft Technologies. Akhil enjoys working on technologies like MVC, Web API, Entity Framework, Angular, C# and BlockChain. Akhil is an MCP( Microsoft Certified Professional) in Web Applications (MCTS-70-528, MCTS-70-515) and .Net Framework 2.0 (MCTS-70-536). Visit Akhil Mittal’s personal blog CodeTeddy for some good and informative articles.
LinkedIn: https://www.linkedin.com/in/akhilmittal/
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Comments and Discussions

 
Questionfor docker Pin
Igor Sevriuk19-May-20 1:50
professionalIgor Sevriuk19-May-20 1:50 
QuestionHow can we call it a microservice example? Pin
Abdul Sami, PMP21-Mar-20 8:07
MemberAbdul Sami, PMP21-Mar-20 8:07 
QuestionService running in docker in local machine Pin
dheeraj marwaha2-Mar-20 3:18
Memberdheeraj marwaha2-Mar-20 3:18 
QuestionIn Microservice Do you add multiple service in same project? Pin
Muhammad N@beel19-Feb-20 2:35
professionalMuhammad N@beel19-Feb-20 2:35 
GeneralMy vote of 4 Pin
DL00110-Feb-20 3:16
MemberDL00110-Feb-20 3:16 
Question.Net Core 3.0 - Failed to bind to address http://localhost:9003. Source=Microsoft.AspNetCore.Server.Kestrel.Core Pin
sencsk18-Jan-20 18:18
Membersencsk18-Jan-20 18:18 
GeneralMy vote of 5 Pin
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professionalIndigo Dragon14-Jan-20 4:08 
GeneralMy vote of 5 Pin
jee1026-Oct-19 7:51
Memberjee1026-Oct-19 7:51 
GeneralRe: My vote of 5 Pin
Akhil Mittal 14-Nov-19 1:21
mva Akhil Mittal 14-Nov-19 1:21 
PraiseMy vote of 5 Pin
Hello Sunny24-Oct-19 18:31
MemberHello Sunny24-Oct-19 18:31 
GeneralRe: My vote of 5 Pin
Akhil Mittal 14-Nov-19 1:21
mva Akhil Mittal 14-Nov-19 1:21 
GeneralThanks for sharing Pin
Alireza_136222-Sep-19 3:33
MemberAlireza_136222-Sep-19 3:33 
GeneralRe: Thanks for sharing Pin
Akhil Mittal 14-Nov-19 1:21
mva Akhil Mittal 14-Nov-19 1:21 
GeneralMy vote of 5 Pin
VaDaGan20-Sep-19 3:35
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GeneralRe: My vote of 5 Pin
Akhil Mittal 14-Nov-19 1:20
mva Akhil Mittal 14-Nov-19 1:20 
SuggestionNote Pin
lnhoa2-Jul-19 20:22
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QuestionSample not about MicroServices Pin
Holms23-May-19 19:53
professionalHolms23-May-19 19:53 
AnswerRe: Sample not about MicroServices Pin
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MemberMember 1447426023-Jul-19 0:18 
QuestionVery nice! Pin
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MemberMember 954700613-May-19 1:08 
QuestionHave my 5 Pin
Alejandro Gaio24-Apr-19 2:43
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AnswerRe: Have my 5 Pin
Akhil Mittal 26-Apr-19 4:34
mva Akhil Mittal 26-Apr-19 4:34 
QuestionNeed more Info Pin
Kaps_10-Apr-19 10:48
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AnswerRe: Need more Info Pin
Akhil Mittal 26-Apr-19 4:35
mva Akhil Mittal 26-Apr-19 4:35 
GeneralMy vote of 5 Pin
udeep kansal5-Apr-19 0:56
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GeneralRe: My vote of 5 Pin
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mva Akhil Mittal 26-Apr-19 4:34 

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Posted 10 Feb 2019

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