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3. caller service call - dapr

2022-06-23 08:40:00 【MASA team】

Preface

In the last article, we talked about using HttpClient Method call , So if we need to change to pass dapr Implement service calls , What do we need to do ？

Caller.Dapr introduction

If our project originally used Caller.HttpClient, Now I want to use Caller.Dapr, So what do we need to do ？

reform Caller The service call - HttpClient The server in , Make the server support dapr call
Adjust the client code , Enable client support through dapr To achieve service invocation , And meet the requirements of HttpClient Call the same result

preparation

install .Net 6.0

establish ASP.NET Core Blank solutions Assignment03
take Assignment02 Under folder Assignment.Server Copied to the Assignment03 Under folder , Then the project Assignment.Server Add to solution Assignment03 in

Choose Assignment.Server And install Masa.Utils.Development.Dapr.AspNetCore

dotnet add package Masa.Utils.Development.Dapr.AspNetCore --version 0.4.0-rc1

modify Assignment.Server Under the project of Program.cs
```
// Ignore namespace references 

var builder = WebApplication.CreateBuilder(args);

//  add to DaprStarter, Used to start the server dapr sidecar, Transform the server support dapr Call focus （ It is recommended to use in the development environment , Online environment use k8s Deploy ）
builder.Services.AddDaprStarter(option =>
{
    option.AppId = "Assignment-Server";
    option.DaprGrpcPort = 7007;
    option.DaprHttpPort = 7008;
    option.AppIdSuffix = string.Empty;
});

var app = builder.Build();
///  Ignore routing, etc 
```
Q: What is? DaprStarter？ Why use DaprStarter？
A: DaprStarter yes Masa The team developed it to manage Dapr sidecar My bag , Can help us in the development environment is very simple to use dapr sidecar
Q: Why specify AppId、DaprGrpcPort、DaprHttpPort Etc ？
A: The client call needs to get Dapr Of AppId、 Set up DaprGrpcPort、DaprHttpPort Because the client demo project does not use dapr sidecar, If the client project also uses dapr sidecar, You may not specify here DaprGrpcPort、DaprHttpPort, For more information, please refer to [ article ](https://www.cnblogs. com/zhenlei520/p/16157625.html)
establish ASP.NET Core Empty item Assignment.Client.DaprClientWeb As a client and install Masa.Utils.Caller.DaprClient
```
dotnet add package Masa.Utils.Caller.DaprClient --version 0.4.0-rc1
```

modify Assignment.Client.DaprClientWeb Under the project of Program.cs

using Masa.Utils.Caller.Core;
using Masa.Utils.Caller.DaprClient;
using Microsoft.AspNetCore.Mvc;

var builder = WebApplication.CreateBuilder(args);
builder.Services.AddCaller(option =>
{
    //  Be careful :  And Caller.HttpClient comparison , What needs to be revised 
    options.UseDapr(masaDaprClientBuilder =>
    {
        masaDaprClientBuilder.Name = "userCaller"; //  At present Caller Another name for ( There is only one Caller You may not fill in ),Name Can't repeat 
        masaDaprClientBuilder.IsDefault = true; //  default Caller Support Injection ICallerProvider obtain （ There is only one Caller No assignment is required ）
        masaDaprClientBuilder.AppId = "Assignment-Server";// Set up current caller Next Dapr Of AppId
    });
});
var app = builder.Build();

app.MapGet("/", () => "Hello HttpClientWeb.V1!");

app.MapGet("/Test/User/Get", async ([FromServices] ICallerProvider callerProvider) =>
{
    var user = await callerProvider.GetAsync<object, UserDto>("User", new { id = new Random().Next(1, 10) });
    return $" User information obtained successfully ： The user name is called ：{user!.Name}";
});

app.MapGet("/Test/User/Add", async ([FromServices] ICallerProvider callerProvider) =>
{
    var dateTimeOffset = new DateTimeOffset(DateTime.UtcNow);
    string timeSpan = dateTimeOffset.ToUnixTimeSeconds().ToString();
    var userName = "ss_" + timeSpan; // Simulate a user name 
    string? response = await callerProvider.PostAsync<object, string>("User", new { Name = userName });
    return $" User creation succeeded , The user name is called ：{response}";
});

app.Run();

public class UserDto
{
    public int Id { get; set; }

    public string Name { get; set; } = default!;
}

Compare with Assignment.Client.HttpClientWeb,Assignment.Client.DaprClientWeb Just changed Program.cs, take UseHttpClient Change it to UseDapr, The rest of the code does not need to be modified

Add environment variables DAPR_GRPC_PORT, The value is 7007、DAPR_HTTP_PORT, The value is 7008
Q: Why add environment variables ？
A: Because the current client is not using dapr sidecar, If the current client also uses dapr sidecar, No environment variables can be added here

Now? Caller Of HttpClient Version can be used , To start, respectively, Assignment.Server、Assignment.Client.DaprClientWeb service , Browser access http://localhost:5042/Test/User/Get、http://localhost:5042/Test/User/Add, Respectively output the corresponding prompt of successful acquisition of user information and successful creation of user , It proves that the call was successful

DaprClient Best practices

Assignment.Client.DaprClientWeb It's easy to write , Its usage and Assignment.Client.HttpClientWeb Almost the same , And Caller.HttpClient similar ,DaprClient We recommend the following wording :

establish ASP.NET Core Empty item Assignment.Client.DaprClientWeb.V2 As caller V2 edition
Choose Assignment.Client.DaprClientWeb.V2 And install Masa.Utils.Caller.DaprClient
```
dotnet add package Masa.Utils.Caller.DaprClient --version 0.4.0-rc1
```

Add the class ServerCallerBase ( Corresponding to the server service )

using Masa.Utils.Caller.DaprClient;

namespace Assignment.Client.DaprClientWeb.V2;

/// <summary>
///  Be careful ：ServerCallerBase It's an abstract class （ Abstract classes will not be DI register ）,  And use Caller.HttpClient comparison , What needs to be modified is that the inherited base class is changed to DaprCallerBase
/// </summary>
public abstract class ServerCallerBase : DaprCallerBase
{
    protected override string AppId { get; set; } = "Assignment-Server";// Set up current Caller The requested server-side project is required Dapr Of AppId

    public ServerCallerBase(IServiceProvider serviceProvider) : base(serviceProvider)
    {
    }
}

Add the class UserCaller.cs

namespace Assignment.Client.DaprClientWeb.V2;

public class UserCaller : ServerCallerBase
{
    public UserCaller(IServiceProvider serviceProvider) : base(serviceProvider)
    {
    }

    /// <summary>
    ///  Call the service to get user information 
    /// </summary>
    /// <param name="id"> user id</param>
    /// <returns></returns>
    public Task<UserDto?> GetUserAsync(int id)
        => CallerProvider.GetAsync<object, UserDto>("User", new { id = id });

    /// <summary>
    ///  Call the service to add users 
    /// </summary>
    /// <param name="userName"></param>
    /// <returns></returns>
    public Task<string?> AddUserAsync(string userName)
        => CallerProvider.PostAsync<object, string>("User", new { Name = userName });
}

public class UserDto
{
    public int Id { get; set; }

    public string Name { get; set; } = default!;
}

Add environment variables DAPR_GRPC_PORT, The value is 7007、DAPR_HTTP_PORT, The value is 7008

Last , To start, respectively, Assignment.Server、Assignment.Client.DaprClientWeb.V2 service , Browser access http://localhost:5102/Test/User/Get、http://localhost:5102/Test/User/Add, Respectively output the corresponding prompt of successful acquisition of user information and successful creation of user , It proves that the call was successful

common problem

We will encounter various problems in development , Here are some problems encountered in our project ：

One project in the same k8s The cluster deploys two sets of environments , Why is there code call confusion （ The development environment calls the online environment ）？
```
 Lies in the same K8s Under Cluster ,dapr Network the service , And think of them as the same service (AppId Consistent service ).
```

How to solve the same problem k8s The problem of call confusion in the cluster ？

 There are two solutions ：
1.  Deploy services in different environments on different platforms K8s colony 
2.  Adjust the corresponding service according to the environment dapr sidecar Configuration of , Its `AppId` Naming rules ：`AppId`-` Environment name `. Modify customization Caller The rules of ：

public abstract class CustomizeDaprCallerBase : DaprCallerBase
{
    protected CustomizeDaprCallerBase(IServiceProvider serviceProvider) : base(serviceProvider)
    {
        var hostEnvironment = serviceProvider.GetRequiredService<IWebHostEnvironment>();
        if (!hostEnvironment.IsDevelopment() || hostEnvironment.IsStaging())
            AppId = AppId + "-" + hostEnvironment.EnvironmentName;
    }
}

How to modify and support customization Header？

 at present Caller.Dapr Customization is not supported Header, At present, you can only use `SendAsync` To customize Header, However, this function has been used in 0.5.0 In the development plan of , stay 0.5.0 China will support

summary

Use Masa Provided Caller service , The project that helps us is not used in the early stage Dapr In the case of..., use Caller.HttpClient Buffer , When the time comes , Just change the corresponding CallerBase that will do , Other code basically doesn't need to be adjusted , Reduced our development costs , And different Caller You can still flexibly adjust the timeout 、Header Etc , also Caller Exception handling is provided by default , When the call goes wrong , Will automatically throw an exception , So that we can concentrate more on our business .

But at the moment, Caller There are still shortcomings , at present Caller.Dapr The version is not perfect for request header processing , besides , Currently not supported Content-Type For the wrong Json type , This function will be displayed in 0.5.0 Supported and improved in version