Building Workflow Driven .NET Applications With Elsa 2 - Part 2

appsettings.json

{
  "Logging": {
    "LogLevel": {
      "Default": "Warning",
      "Microsoft": "Warning",
      "Microsoft.Hosting.Lifetime": "Information"
    }
  },
  "AllowedHosts": "*",
  "ConnectionStrings": {
    "Sqlite": "Data Source=elsa.sqlite.db;Cache=Shared;"
  },
  "Hangfire": {
    "SchedulePollingInterval": "00:00:10",
    "WorkerCount": 1 
  },
  "Elsa": {
    "Server": {
      "BaseUrl": "http://localhost:5000",
      "BasePath": "/workflows"
    },
    "Smtp": {
      "Host": "localhost",
      "Port": 2525,
      "DefaultSender": "[email protected]"
    }
  }
}

Startup.cs

using DocumentManagement.Workflows.Extensions;
using Elsa.Activities.Email.Options;
using Elsa.Activities.Http.Options;
using Elsa.Persistence.EntityFramework.Sqlite;
using Elsa.Server.Hangfire.Extensions;
using Hangfire;
using Hangfire.SQLite;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using NodaTime;
using NodaTime.Serialization.JsonNet;

namespace DocumentManagement.Web
{
    public class Startup
    {
        public Startup(IConfiguration configuration, IWebHostEnvironment environment)
        {
            Configuration = configuration;
            Environment = environment;
        }

        private IConfiguration Configuration { get; }
        private IWebHostEnvironment Environment { get; }

        public void ConfigureServices(IServiceCollection services)
        {
            var dbConnectionString = Configuration.GetConnectionString("Sqlite");

            // Razor Pages (for UI).
            services.AddRazorPages();

            // Hangfire (for background tasks).
            AddHangfire(services, dbConnectionString);

            // Elsa (workflows engine).
            AddWorkflowServices(services, dbConnectionString);

            // Allow arbitrary client browser apps to access the API for demo purposes only.
            // In a production environment, make sure to allow only origins you trust.
            services.AddCors(cors => cors.AddDefaultPolicy(policy => policy.AllowAnyHeader().AllowAnyMethod().AllowAnyOrigin().WithExposedHeaders("Content-Disposition")));
        }

        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }
            else
            {
                app.UseExceptionHandler("/Error");
                app.UseHsts();
            }

            app
                .UseStaticFiles()
                .UseCors()
                .UseRouting()
                .UseHttpActivities() // Install middleware for triggering HTTP Endpoint activities. 
                .UseEndpoints(endpoints =>
                {
                    endpoints.MapRazorPages();
                    endpoints.MapControllers(); // Elsa API Endpoints are implemented as ASP.NET API controllers.
                });
        }

        private void AddHangfire(IServiceCollection services, string dbConnectionString)
        {
            services
                .AddHangfire(config => config
                    // Use same SQLite database as Elsa for storing jobs. 
                    .UseSQLiteStorage(dbConnectionString)
                    .UseSimpleAssemblyNameTypeSerializer()

                    // Elsa uses NodaTime primitives, so Hangfire needs to be able to serialize them.
                    .UseRecommendedSerializerSettings(settings => settings.ConfigureForNodaTime(DateTimeZoneProviders.Tzdb)))
                .AddHangfireServer((sp, options) =>
                {
                    // Bind settings from configuration.
                    Configuration.GetSection("Hangfire").Bind(options);

                    // Configure queues for Elsa workflow dispatchers.
                    options.ConfigureForElsaDispatchers(sp);
                });
        }

        private void AddWorkflowServices(IServiceCollection services, string dbConnectionString)
        {
            services.AddWorkflowServices(dbContext => dbContext.UseSqlite(dbConnectionString));

            // Configure SMTP.
            services.Configure<SmtpOptions>(options => Configuration.GetSection("Elsa:Smtp").Bind(options));

            // Configure HTTP activities.
            services.Configure<HttpActivityOptions>(options => Configuration.GetSection("Elsa:Server").Bind(options));

            // Elsa API (to allow Elsa Dashboard to connect for checking workflow instances).
            services.AddElsaApiEndpoints();
        }
    }
}

Workflows-Extensions-ServiceCollectionExtensions.cs

using System;
using Elsa.Persistence.EntityFramework.Core.Extensions;
using Elsa.Server.Hangfire.Extensions;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.DependencyInjection;

namespace DocumentManagement.Workflows.Extensions
{
    public static class ServiceCollectionExtensions
    {
        public static IServiceCollection AddWorkflowServices(this IServiceCollection services, Action<DbContextOptionsBuilder> configureDb)
        {
            return services.AddElsa(configureDb);
        }

        private static IServiceCollection AddElsa(this IServiceCollection services, Action<DbContextOptionsBuilder> configureDb)
        {
            services
                .AddElsa(elsa => elsa

                    // Use EF Core's SQLite provider to store workflow instances and bookmarks.
                    .UseEntityFrameworkPersistence(configureDb)
                    
                    // Ue Console activities for testing & demo purposes.
                    .AddConsoleActivities()

                    // Use Hangfire to dispatch workflows from.
                    .UseHangfireDispatchers()

                    // Configure Email activities.
                    .AddEmailActivities()

                    // Configure HTTP activities.
                    .AddHttpActivities()
                );
            
            return services;
        }
    }
}