A day with .Net

My day to day experince in .net

Pushing your local docker image to Azure Container Registry

Posted by vivekcek on March 18, 2018

In the last post, i wrote about how can we create and run Docker image locally.

Docker Hello World with ASP.NET Core

Today, i will show you how can we push this local Docker image to Azure Container Registry.Azure Container Registry is a private Docker Registry like Docker Hub, to which we can store our docker images.The Docker images stored in this registry can be deployed to a kubernetes cluster easily.

So what are the tools we required.

1. Docker CE.
2. Azure CLI.
3. Azure Subscription.

I am planning to use the Docker image created in the last post. So refer that post to create a docker image.
Before starting make sure Docker is running in your PC with admin privilege.

1. First go to Azure Portal.

2. Search for Azure Container Registry.

3. Create a container registry.Note down the name of the registry (Ex:vivekcek).

4. Once the registry is created, from the Acess Key tab note down the login server name (ex:vivekcek.azurecr.io).

5. Now open the command prompt as Administartor(Azure CLI must be installed).

6. Issue below command to login(Docker must be running for login).

az acr login --name vivekcek

7.Now list the available images in your docker.

docker ps

8. Now tag myapp image.

docker tag myapp vivekcek.azurecr.io/myapp:v1

9. Now push the taged myapp image.

docker push vivekcek.azurecr.io/myapp

10. Now in azure portal under Repository tab see your image.

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Posted in Azure, Docker | Tagged: | Leave a Comment »

Docker Hello World with ASP.NET Core

Posted by vivekcek on March 3, 2018

I follow this rule “Never apply a technology in a project for the purpose of learning/using it”.
The above rule is applicable for Docker also, Use it if you are planning something big and have budget to rewrite after 3 years.
Sometimes you can keep things simple,thus by save money and time.

Anyway come back to my Docker journey.

1. I had to install a 64 bit version of Windows 10 and Visual Studio 2017.
2. Downloaded and installed Docker CE.
3. During the first start Docker enabled Hyper-V, that’s great.
4. Then i got an error message “You don’t have enough memory to start Docker”.
5. Go to Docker Settings from task-bar quick launch icon. Then reduced memory size to 1500mb.

6. You have to start Docker as Administrator.
7. Once your Docker is running, Open a Command Prompt as Administrator.
8. First i switched to my drive D and created a folder “myapp”.
9. Now issue below command to create an empty Asp.net core app.

dotnet new  web

10.Now issue dotnet run to run your app.

dotnet run

11.Check whetaher your app is running at http://localhost:5000
12. Now publish you app.

dotnet publish -c Release

13.Now inside this folder “bin\Release\netcoreapp2.0\publish”, Create a file named Dockerfile.
14.You can use notepad for that.
15. Place the below text inside your Dockerfile.

FROM microsoft/aspnetcore
WORKDIR /app
COPY . .
EXPOSE 80
ENTRYPOINT ["dotnet", "myapp.dll"]

16.Now build your Docker image using the build command.

docker build . -t myapp -f ./Dockerfile.txt

17.Once building finished check your docker images by this command.

docker images

18. Now run your Docker app.

docker run -p 8000:80 myapp

19. Your app will be running at port 8000

Posted in Docker | Tagged: , , | Leave a Comment »

Micro Services Architecture – Design Authentication with Identity Server SQL Server and ASP.NET Core Part-3.

Posted by vivekcek on January 27, 2018

This is the continuation from my previous two post. Have a look at those below.

Micro Services Architecture – Design Authentication with Identity Server SQL Server and ASP.NET Core Part-1

Micro Services Architecture – Design Authentication with Identity Server SQL Server and ASP.NET Core Part-2

Today we will move our users from IdentityServer’s in-memory to SQL Server.

So first of all we need to install below nuget packages. Please note this is applicable for ASP.NET Core 1.1 version only.

1.Install IdentityServer4.EntityFramework nuget 1.x version. Use the latest one.

2.Add Microsoft.EntityFrameworkCore.SqlServer. Use the latest 1.x version.

3.Add Microsoft.EntityFrameworkCore.Design. Use the latest 1.x version.

4.Now edit the project and add below tag.

 <ItemGroup>
    <DotNetCliToolReference Include="Microsoft.EntityFrameworkCore.Tools.DotNet" Version="1.1.5" />
  </ItemGroup>

5.Now got to your solution directory and check whether Entity Framework is correctly installed. Use the “dotnet ef” command.

6.Create a database named “IdentityServices” in SQL Server.

7.Update your Config.cs as below.

using IdentityServer4.Models;
using IdentityServer4.Test;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;

namespace IdentityServices
{
    public class Config
    {

        public static IEnumerable<ApiResource> GetApiResources()
        {
            return new List<ApiResource>
            {
                new ApiResource("api1", "My API")
            };
        }

        public static IEnumerable<Client> GetClients()
        {
            return new List<Client>
            {
              
                new Client
                {
                    ClientId = "client",
                    AllowedGrantTypes = GrantTypes.ResourceOwnerPassword,

                    ClientSecrets =
                    {
                        new Secret("secret".Sha256())
                    },
                    AllowedScopes = { "api1" }
                }
            };
        }
    

    }
  
}

8.Add a class named User.

using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Linq;
using System.Threading.Tasks;

namespace IdentityServices
{
    public class User
    {
        [Key]
        public string Id { get; set; }
        public string Email { get; set; }
        public bool Active { get; set; }
        public string Password { get; set; }
    }
}

9.Now add a DbContext class name “ApplicationDbContext”.

using Microsoft.EntityFrameworkCore;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;

namespace IdentityServices
{
    public class ApplicationDbContext : DbContext
    {
        public ApplicationDbContext(DbContextOptions<ApplicationDbContext> options) : base(options) { }

        public DbSet<User> Users { get; set; }
    }
}

10.Now add a class named DataAcess.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using IdentityServer4.Models;
using IdentityServer4.Validation;
using System.Security.Claims;

using IdentityModel;
using IdentityServer4.Extensions;

using IdentityServer4.Services;

namespace IdentityServices
{
    public interface IAuthRepository
    {
        User GetUserById(string id);
        User GetUserByUsername(string username);
        bool ValidatePassword(string username, string plainTextPassword);
    }

    public class AuthRepository : IAuthRepository
    {
        private ApplicationDbContext db;

        public AuthRepository(ApplicationDbContext context)
        {
            db = context;
        }

        public User GetUserById(string id)
        {
            var user = db.Users.Where(u => u.Id == id).FirstOrDefault();
            return user;
        }

        public User GetUserByUsername(string username)
        {
            var user = db.Users.Where(u => String.Equals(u.Email, username)).FirstOrDefault();
            return user;
        }


        public bool ValidatePassword(string username, string plainTextPassword)
        {
            var user = db.Users.Where(u => String.Equals(u.Email, username)).FirstOrDefault();
            if (user == null) return false;
            if (String.Equals(plainTextPassword, user.Password)) return true;
            return false;
        }
    }

    public class ResourceOwnerPasswordValidator : IResourceOwnerPasswordValidator
    {
        IAuthRepository _rep;

        public ResourceOwnerPasswordValidator(IAuthRepository rep)
        {
            this._rep = rep;
        }

        public Task ValidateAsync(ResourceOwnerPasswordValidationContext context)
        {
            if (_rep.ValidatePassword(context.UserName, context.Password))
            {
                context.Result = new GrantValidationResult(_rep.GetUserByUsername(context.UserName).Id, "password", null, "local", null);
                return Task.FromResult(context.Result);
            }
            context.Result = new GrantValidationResult(TokenRequestErrors.InvalidGrant, "The username and password do not match", null);
            return Task.FromResult(context.Result);
        }
    }

    public class ProfileService : IProfileService
    {
        private IAuthRepository _repository;

        public ProfileService(IAuthRepository rep)
        {
            this._repository = rep;
        }

        public Task GetProfileDataAsync(ProfileDataRequestContext context)
        {
            try
            {
                var subjectId = context.Subject.GetSubjectId();
                var user = _repository.GetUserById(subjectId);

                var claims = new List<Claim>
            {
                new Claim(JwtClaimTypes.Subject, user.Id.ToString()),
				//add as many claims as you want!new Claim(JwtClaimTypes.Email, user.Email),new Claim(JwtClaimTypes.EmailVerified, "true", ClaimValueTypes.Boolean)
			};

                context.IssuedClaims = claims;
                return Task.FromResult(0);
            }
            catch (Exception x)
            {
                return Task.FromResult(0);
            }
        }

        public Task IsActiveAsync(IsActiveContext context)
        {
            var user = _repository.GetUserById(context.Subject.GetSubjectId());
            context.IsActive = (user != null) && user.Active;
            return Task.FromResult(0);
        }
    }
}

11.Now update your Startup.cs.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
using System.Reflection;
using Microsoft.EntityFrameworkCore;
using IdentityServer4.EntityFramework.Mappers;
using IdentityServer4.EntityFramework.DbContexts;
using IdentityServer4.Validation;
using IdentityServer4.Services;

namespace IdentityServices
{
    public class Startup
    {
        // This method gets called by the runtime. Use this method to add services to the container.
        // For more information on how to configure your application, visit https://go.microsoft.com/fwlink/?LinkID=398940
        const string connectionString = @"Data Source=.;database=IdentityServices;uid=sa;pwd=password;";
        string migrationsAssembly = typeof(Startup).GetTypeInfo().Assembly.GetName().Name;
        public void ConfigureServices(IServiceCollection services)
        {

            services.AddTransient<IResourceOwnerPasswordValidator, ResourceOwnerPasswordValidator>()
            .AddTransient<IProfileService, ProfileService>()
            .AddTransient<IAuthRepository, AuthRepository>();

            services.AddDbContext<ApplicationDbContext>(options =>
                            options.UseSqlServer(connectionString)
                    );

            services.AddIdentityServer()
            .AddDeveloperSigningCredential()
            .AddInMemoryApiResources(Config.GetApiResources())
            .AddInMemoryClients(Config.GetClients())
            .AddConfigurationStore(builder =>
             builder.UseSqlServer(connectionString, options =>
            options.MigrationsAssembly(migrationsAssembly)))
            .AddOperationalStore(builder =>
            builder.UseSqlServer(connectionString, options =>
            options.MigrationsAssembly(migrationsAssembly)));
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
        {
            InitializeDatabase(app);

            loggerFactory.AddConsole();

            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }


            app.UseIdentityServer();
        }

        private void InitializeDatabase(IApplicationBuilder app)
        {
            using (var serviceScope = app.ApplicationServices.GetService<IServiceScopeFactory>().CreateScope())
            {
                serviceScope.ServiceProvider.GetRequiredService<PersistedGrantDbContext>().Database.Migrate();
                serviceScope.ServiceProvider.GetRequiredService<ApplicationDbContext>().Database.Migrate();
                var context = serviceScope.ServiceProvider.GetRequiredService<ConfigurationDbContext>();
                context.Database.Migrate();
                if (!context.Clients.Any())
                {
                    foreach (var client in Config.GetClients())
                    {
                        context.Clients.Add(client.ToEntity());
                    }
                    context.SaveChanges();
                }

                //if (!context.IdentityResources.Any())
                //{
                //    foreach (var resource in Config.GetIdentityResources())
                //    {
                //        context.IdentityResources.Add(resource.ToEntity());
                //    }
                //    context.SaveChanges();
                //}

                if (!context.ApiResources.Any())
                {
                    foreach (var resource in Config.GetApiResources())
                    {
                        context.ApiResources.Add(resource.ToEntity());
                    }
                    context.SaveChanges();
                }
            }
        }
    }
}

12.Now run these migrations, one by one.

dotnet ef migrations add InitialIdentityServerPersistedGrantDbMigration -c PersistedGrantDbContext -o Data/Migrations/IdentityServer/PersistedGrantDb
dotnet ef migrations add InitialIdentityServerConfigurationDbMigration -c ConfigurationDbContext -o Data/Migrations/IdentityServer/ConfigurationDb
dotnet ef migrations add InitialIdentityServerApplicationDbMigration -c ApplicationDbContext -o Data/Migrations/IdentityServer/ApplicationDb

13.Now run the IdentityService application and check your database.

14.Add a user to your table User.

15.Now check with Postman.

Posted in Microservices | Tagged: , , , , , | Leave a Comment »

Build and deploy ASP.NET application to Azure via GitHub and Bamboo Server (CI\CD)

Posted by vivekcek on January 26, 2018

Bamboo Server is the choice of professional teams for continuous integration, deployment, and delivery.

In this post I will explain, How to configure Bamboo to build and deploy to Azure from GitHub repository.

1.This is how my git repo looks like.

2.When you clone this looks like as below. You can see my solution is actually inside a folder named “AzureSite”. When we configure our paths we need to consider this.

3.Now open your Bamboo Server, and create build plan. Fill the Project and build plan name section and “Link repository to new build plan.

4.Now in the Configure task section. First set your Source Code Checkout Task. Select the repository we connected in the previous step.

5.Now create a Script task to restore our nuget packages. Use the below script.

"C:\Program Files (x86)\NuGet\nuget.exe" restore "${bamboo.build.working.directory}\AzureSite\AzureSite.sln"

6.Now Add an MsBuild task as below.

7.Now create and Run the plan.

8.Now create an Artifacts for deployment. Please check the share checkbox.

9.Now create a deployment project.

10.Now create an environment.
11.Now Configure Artifact download task. Select the artifacts we create in step 8.

12.Now from azure download your publisher profile and import to your project.
13.Now add an MsBuild task for deploy. Use the below options

/p:Configuration=Debug /p:DeployOnBuild=True /p:PublishProfile="DeployToAzure" /p:ProfileTransformWebConfigEnabled=False /p:Password=PassworddFromDownloaded /p:AllowUntrustedCertificate=true

Posted in CI/CD Bamboo | Tagged: , , , , | Leave a Comment »

Micro Services Architecture – Design Authentication with IdentityServer4, SQL Server and ASP.NET Core Part-2

Posted by vivekcek on January 20, 2018

This is the continuation of my first post about “Setting up IdentityServer4 for token based authentication in Microservices architecture”

Please read the first part.
Micro Services Architecture – Design Authentication with IdentityServer4, SQL Server and ASP.NET Core Part-1

In this part we will create a Web Api. To access this Web Api first we need to get a valid token from our Identity Server. After getting the token we can call the Web Api.

Please note that we are using ASP.NET Core 1.1. The steps to do the same in ASP.NET Core 2.0 is little bit different.

1.Create a Web Api project named Protected Api.

2.Select Web Api template.

3.Now add nuget package named “IdentityServer4.AccessTokenValidation”.

4.Now update your Configure method in Startup.cs

 public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
        {
            app.UseIdentityServerAuthentication(new IdentityServerAuthenticationOptions
            {
                Authority = "http://localhost:5000",
                RequireHttpsMetadata = false,

                ApiName = "api1"
            });

            app.UseMvc();
        }

5.Now create a controller as below with Authorize attribute.

 [Route("api/[controller]")]
    public class ValuesController : Controller
    {
        [Authorize]
        [HttpGet]
        public IActionResult Get()
        {
            return new JsonResult(User.Identity.IsAuthenticated);
        }

    }

6.Now first start our IdentityService. Then get a token as explained in the Part 1.
7.Now use that token with Postman to call our protected Api.

Posted in Microservices | Tagged: , , , | Leave a Comment »

Micro Services Architecture – Design Authentication with IdentityServer4, SQL Server and ASP.NET Core Part-1

Posted by vivekcek on January 20, 2018

Micro Services architecture is one of the hot topic in developer community.

I recommend micro services architecture if you face the below scenarios.

1. Use it when you are going to build next Amazon, Facebook, Uber etc.
2. You need to build a large system with a set of people with different technology stack.
3. You are building for high availability and fault tolerance.
4. You want to reduce the time to market.

To succeed with this architecture. You need below thing

1. A team of good architects who understand the architecture and business domain very well.
2. Everyday refine the architecture, if you find any flaws.
3. Should be able to define the boundaries of each micro services.
4. First day onward design the architecture for availability, Security, resilience.
5. Agile is good but execute it with creative people, who know how to execute it better.

In micro services architecture the first thing we can do is design our authentication system.

Here I am going to setup a Token Based authentication system with Identity Server 4. This is how it looks.

These are my Tools.

1.Visual Studio 2017(15.0)
2.ASP.NET Core 1.1
3.SQL Server 2014
4.Post Man

Please note that the steps will be different for ASP.NET Core 2.0.

1.Create an ASP.NET Core 1.1 project.

2.Select empty template.

3.Now add the IdentityServer 4 nuget package (We are using 1.5.2 version , 1.x versions are for ASP.NET Core 1.1).

4.We want our users to be signed with Username and Password.
5.Now add a class named Config.cs in your solution and paste below code.

using IdentityServer4.Models;
using IdentityServer4.Test;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;

namespace IdentityServices
{
    public class Config
    {

        public static IEnumerable<ApiResource> GetApiResources()
        {
            return new List<ApiResource>
            {
                new ApiResource("api1", "My API")
            };
        }

        public static IEnumerable<Client> GetClients()
        {
            return new List<Client>
            {
              
                new Client
                {
                    ClientId = "client",
                    AllowedGrantTypes = GrantTypes.ResourceOwnerPassword,

                    ClientSecrets =
                    {
                        new Secret("secret".Sha256())
                    },
                    AllowedScopes = { "api1" }
                }
            };
        }


        public static List<TestUser> GetUsers()
        {
            return new List<TestUser>
            {
                new TestUser
                {
                    SubjectId = "1",
                    Username = "vivek",
                    Password = "password"
                }
               
            };
        }

    }

   
}

6.Now update your Startup.cs as below.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;

namespace IdentityServices
{
    public class Startup
    {
        
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddIdentityServer()
                .AddTemporarySigningCredential()
                .AddInMemoryApiResources(Config.GetApiResources())
                .AddInMemoryClients(Config.GetClients())
                .AddTestUsers(Config.GetUsers());
        }

       
        public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
        {

            loggerFactory.AddConsole();

            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }

            app.UseIdentityServer();

        }
    }
}

7.Now open your project properties and in Debug tab change profile from IISExpress to your project, then update you app url to http://localhost:5000/

8.Now run the app. Select IdentityServices.

9.The app will run as a console application.

10.Now open post man and try this.

In the next post we will move the users to SQL Server.

Posted in Microservices | Tagged: , , | Leave a Comment »

Resilient HTTP call with retry and exponential back-off – Micro-services architecture.

Posted by vivekcek on January 11, 2018

During the designing of a microservice architecture based application, i came across a scenario in which i need to make sure the http call to other services need to retry for ensuring resilence.

The approach i tried is retry the http call when request exception occur. And each retry is performed after a particular time interwell, which is exponenetial in nature.

To implement this i used a nuget package named polly.

This is the Resilient HTTP class we wrote, You can use an interface and dependency injection for productions app.

public interface IHttpClient
{
Task<string> GetStringAsync(string uri, string authorizationToken = null,
string authorizationMethod = "Bearer");
Task<HttpResponseMessage> PostAsync<T>(string uri, T item,
string authorizationToken = null, string requestId = null,
string authorizationMethod = "Bearer");
Task<HttpResponseMessage> DeleteAsync(string uri,
string authorizationToken = null, string requestId = null,
string authorizationMethod = "Bearer");
}
public class ResilientHttpClient : IHttpClient
{
private HttpClient _client;
private PolicyWrap _policyWrapper;
private ILogger<ResilientHttpClient> _logger;
public ResilientHttpClient(Policy[] policies,
ILogger<ResilientHttpClient> logger)
{
_client = new HttpClient();
_logger = logger;
// Add Policies to be applied
_policyWrapper = Policy.WrapAsync(policies);
}
private Task<T> HttpInvoker<T>(Func<Task<T>> action)
{
// Executes the action applying all
// the policies defined in the wrapper
return _policyWrapper.ExecuteAsync(() => action());
}
public Task<string> GetStringAsync(string uri,
string authorizationToken = null,
string authorizationMethod = "Bearer")
{
return HttpInvoker(async () =>
{
var requestMessage = new HttpRequestMessage(HttpMethod.Get, uri);
var response = await _client.SendAsync(requestMessage);
return await response.Content.ReadAsStringAsync();
});
}
}

Now in your WebApi’s Startup.cs write below code.

// Startup.cs class
if (Configuration.GetValue<string>("UseResilientHttp") == bool.TrueString)
{
services.AddTransient<IResilientHttpClientFactory,
ResilientHttpClientFactory>();
services.AddSingleton<IHttpClient,
ResilientHttpClient>(sp =>
sp.GetService<IResilientHttpClientFactory>().
CreateResilientHttpClient());
}
else
{
services.AddSingleton<IHttpClient, StandardHttpClient>();
}

public ResilientHttpClient CreateResilientHttpClient()
=> new ResilientHttpClient(CreatePolicies(), _logger);
// Other code
private Policy[] CreatePolicies()
=> new Policy[]
{
Policy.Handle<HttpRequestException>()
.WaitAndRetryAsync(
// number of retries
6,
// exponential backoff
retryAttempt => TimeSpan.FromSeconds(Math.Pow(2, retryAttempt)),
// on retry
(exception, timeSpan, retryCount, context) =>
{
var msg = $"Retry {retryCount} implemented with Pollys
RetryPolicy " +
$"of {context.PolicyKey} " +
$"at {context.ExecutionKey}, " +
$"due to: {exception}.";
_logger.LogWarning(msg);
_logger.LogDebug(msg);
}),
}

Posted in Microservices | Leave a Comment »

Location Permission in Android Version 6 (android 6.0 marshmallow) With API Level 23

Posted by vivekcek on January 2, 2018

I was developing an android taxi app with gps location. Initially i targeted the app for API level 26 and later i decided for API level 23. In the app i need to get location permission at run time. I placed required attributes in android manifest as below.

 <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
 <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
 <uses-permission android:name="android.permission.INTERNET" />
 <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />

Then i asked for permission using the code below. Unfortunately after deploying the app in a marshmallow, the app never asked for permission. Then i went to App manager and gave permission manually.

  if (ActivityCompat.checkSelfPermission(this, android.Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, android.Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {

            return;
        }

After some research i learn that to get run-time location permission in marshmallow, you have to try below steps in your Activity.

1. Override below method.

final int LOCATION_REQUEST_CODE = 1;
    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        switch (requestCode) {
            case LOCATION_REQUEST_CODE: {
                if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                    mapFragment.getMapAsync(this);
                } else {
                    Toast.makeText(getApplicationContext(), "Please provide the permission", Toast.LENGTH_LONG).show();
                }
                break;
            }
        }
    }

2. Request permission using below code.

if (ActivityCompat.checkSelfPermission(this, android.Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, android.Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
            ActivityCompat.requestPermissions(DriverMapActivity.this, new String[]{android.Manifest.permission.ACCESS_FINE_LOCATION}, LOCATION_REQUEST_CODE);
        }else{
            mapFragment.getMapAsync(this);
        }

Posted in Android c# | Tagged: , , , , | Leave a Comment »

Communication between Angular 4 components through RxJs and Observables

Posted by vivekcek on September 27, 2017

Hi Guys this is a quick post about how we can implement communication between Angular 4 components via RxJs and Observable. This example can be done with other component communication mechanisms like @Input() and Services.

But observable based communication will be useful in large Angular 4 applications.
I am not going to explain the concept in detail. Please google it.

Back to our example.

I have two nested components, AppComponent and HelloCoponent. AppCoponent is the parent/root.
AppComponent display a list of dynamically created items. There is a button inside HelloComponent, When clicking on it new items are added and these new items are reflected in AppComponent.

Have a look at the structure.

Have a look at the code.

AppComponent

import { Component,OnInit} from '@angular/core';
import {MessageService} from './message.service'
import {Subscription} from 'rxjs/Subscription'
@Component({
  selector: 'my-app',
  templateUrl: './app.component.html',
  styleUrls: [ './app.component.css' ]
})
export class AppComponent implements OnInit  {
  
  names:string[];

  constructor(private msgServce:MessageService){

  }

  ngOnInit():void{
    this.msgServce.msgPublisher$.subscribe(data=>{this.names=data.names;
    //this.changeDetectorRef.detectChanges();
    
    });
  }
}

AppComponent.html

<hello ></hello>
<ul>
       <li *ngFor="let name of names">
          {{name}}
       </li>
</ul>

HelloCoponent

import { Component, Input } from '@angular/core';
import {MessageService} from './message.service'
@Component({
  selector: 'hello',
  template: `<button (click)="onAdd()">Add</button>`,
  styles: [`h1 { font-family: Lato; }`]
})
export class HelloComponent  {
  constructor(private msgService:MessageService){

  }

  onAdd(){
    this.msgService.addName("Test");
  }
}

MessageService

import {Injectable} from '@angular/core'
import {Subject} from 'rxjs/Subject'

@Injectable()
export class MessageService{
  constructor(){}
  names:string[]=[];
  private messageSource=new Subject<any>();
  msgPublisher$=this.messageSource.asObservable();

  addName(name:string){
    this.names.push(name)
    this.messageSource.next({names:this.names})
  }
}

Posted in Angular2 | Tagged: , | Leave a Comment »

Predicting linear regression with Tensorflow and Azure Machine Learning Studio (Comparison ,Gradient descent)

Posted by vivekcek on September 20, 2017

In this post I am trying to evaluate the prediction done by Tensorflow and Azure Machine Learning Studio.
I am using a dataset obtained from Courseera machine learning tutorial. I will provide the dataset at the end of this post.
Here is the predicted value I got from Tensorflow and Azure Machine Learning for the input “8.5172”

Azure

Tensorflow

I used linear regression with Gradient descent optimizer, and below are the values used for epoch and learning rate in Tensorflow and azure ML.
Epoch=1000
Learning rate=0.01

Azure Model and Algorithm settings are given below

Tensorflow code is given below.

import matplotlib.pyplot as plt
import pandas as pd
import tensorflow as tf

# Parameters
display_step = 50
learning_rate = 0.01
training_epochs = 1000

data = pd.read_csv('ex1data1.txt', names=['population', 'profit'])

X_data = data[['population']]
Y_data = data[['profit']]

n_samples = X_data.shape[0]  # Number of rows

# tf Graph Input
X = tf.placeholder('float', shape=X_data.shape)
Y = tf.placeholder('float', shape=Y_data.shape)

# Set model weights
W = tf.Variable(tf.zeros([1, 1]), name='weight')
b = tf.Variable(tf.zeros(1), name='bias')

# Construct a linear model
pred = tf.add(tf.multiply(X, W), b)

# Mean squared error
# cost = tf.reduce_sum(tf.pow(pred-Y, 2))/(2*n_samples)
cost = tf.reduce_mean(tf.square(pred-Y)) / 2.0

# Gradient descent
# may try other optimizers like AdadeltaOptimizer, AdagradOptimizer, AdamOptimizer, FtrlOptimizer or RMSPropOptimizer
optimizer = tf.train.GradientDescentOptimizer(learning_rate).minimize(cost)

# Initializing the variables
init = tf.global_variables_initializer()

# Launch the graph
with tf.Session() as sess:
    sess.run(init)
    cost_value, w_value, b_value = (0.0, 0.0, 0.0)
    for epoch in range(training_epochs):
        # Fit all training data
        _, cost_value, w_value, b_value = sess.run((optimizer, cost, W, b), feed_dict={X: X_data, Y: Y_data})

        # Display logs per epoch step
        if (epoch+1) % display_step == 0:
            print('Epoch:', '%04d' % (epoch+1), 'cost=', '{:.9f}'.format(cost_value), \
                'W=', w_value, 'b=', b_value)

    print ('Optimization Finished!')
    print ('Training cost=', cost_value, 'W=', w_value, 'b=', b_value, '\n')
    print('Evaluation')
    print(w_value*8.5172+b_value)
    # Graphic display
    plt.plot(X_data, Y_data, 'ro', label='Original data')
    plt.plot(X_data, w_value * X_data + b_value, label='Fitted line')
    plt.legend()
    plt.show()

Please use below dataset.

6.1101,17.592
5.5277,9.1302
8.5186,13.662
7.0032,11.854
5.8598,6.8233
8.3829,11.886
7.4764,4.3483
8.5781,12
6.4862,6.5987
5.0546,3.8166
5.7107,3.2522
14.164,15.505
5.734,3.1551
8.4084,7.2258
5.6407,0.71618
5.3794,3.5129
6.3654,5.3048
5.1301,0.56077
6.4296,3.6518
7.0708,5.3893
6.1891,3.1386
20.27,21.767
5.4901,4.263
6.3261,5.1875
5.5649,3.0825
18.945,22.638
12.828,13.501
10.957,7.0467
13.176,14.692
22.203,24.147
5.2524,-1.22
6.5894,5.9966
9.2482,12.134
5.8918,1.8495
8.2111,6.5426
7.9334,4.5623
8.0959,4.1164
5.6063,3.3928
12.836,10.117
6.3534,5.4974
5.4069,0.55657
6.8825,3.9115
11.708,5.3854
5.7737,2.4406
7.8247,6.7318
7.0931,1.0463
5.0702,5.1337
5.8014,1.844
11.7,8.0043
5.5416,1.0179
7.5402,6.7504
5.3077,1.8396
7.4239,4.2885
7.6031,4.9981
6.3328,1.4233
6.3589,-1.4211
6.2742,2.4756
5.6397,4.6042
9.3102,3.9624
9.4536,5.4141
8.8254,5.1694
5.1793,-0.74279
21.279,17.929
14.908,12.054
18.959,17.054
7.2182,4.8852
8.2951,5.7442
10.236,7.7754
5.4994,1.0173
20.341,20.992
10.136,6.6799
7.3345,4.0259
6.0062,1.2784
7.2259,3.3411
5.0269,-2.6807
6.5479,0.29678
7.5386,3.8845
5.0365,5.7014
10.274,6.7526
5.1077,2.0576
5.7292,0.47953
5.1884,0.20421
6.3557,0.67861
9.7687,7.5435
6.5159,5.3436
8.5172,4.2415
9.1802,6.7981
6.002,0.92695
5.5204,0.152
5.0594,2.8214
5.7077,1.8451
7.6366,4.2959
5.8707,7.2029
5.3054,1.9869
8.2934,0.14454
13.394,9.0551
5.4369,0.61705

Posted in Azure, Machine Learning, Tensorflow | Tagged: , | Leave a Comment »