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Reactive view models for data changes
Install-Package Joker.MVVM
Plumbing code for OData web services. Support for batching and end points. Please help out the community by sharing your suggestions and code improvements:
Redis TableDependency status notifier Sql server data changes refresher via Redis with End to end reconnections
If sharing increases coupling, should we share at all? Is it time for decoupling?
I don't think so.
Please use data streaming and process it with the help of reactive programming and event driven paradigms.
https://www.nuget.org/packages/SqlTableDependency.Extensions/
Install-Package SqlTableDependency.Extensions
or
dotnet add package SqlTableDependency.Extensions --version 3.0.0
Following package is based on christiandelbianco's SqlTableDependency: https://github.com/christiandelbianco/monitor-table-change-with-sqltabledependency
SqlTableDependency.Extension.SqlTableDependencyProvider provides periodic reconnections in case of any error, like lost connection etc.
Currently there are 3 LifetimeScopes:
In case that the connection is lost, database objects will be deleted after timeout period or during disposal. During all reconnections the database objects are newly (re)created.
In case that the connection is lost, database objects will be deleted only after timeout period. After reconnection the database objects are recreated in case that the conversation handle does not exist anymore. Otherwise the database objects are preserved and reused. If the application was closed the conversation will not continue after app restart. You shouldn't lost data changes within the timeout period. The messages will be delivered after the reconnection.
In case that the connection is lost, database objects will be deleted only after timeout period. After reconnection the database objects are recreated only in case, that the conversation handle does not exist anymore. Otherwise the database objects are preserved and reused. If the application was closed and the conversation was not cleaned it will be reused after app restarts. You shouldn't lost data changes within the timeout period. The messages will be delivered after the reconnection.
MS SQL Server 2017
docker run --name sql -e "ACCEPT_EULA=Y" -e "SA_PASSWORD=<YourNewStrong@Passw0rd>" -p 1401:1433 -d mcr.microsoft.com/mssql/server:2017-latest
Redis latest
docker run --name redis-server -p 6379:6379 -d redis
Package Manager Console (Default project => Examples\Samples.Data):
Update-Database -ConnectionString "Server=127.0.0.1,1401;User Id = SA;Password=<YourNewStrong@Passw0rd>;Initial Catalog = Test;" -ConnectionProviderName "System.Data.SqlClient" -ProjectName Sample.Data -verbose
Enable Service Broker in MS SQL SERVER
ALTER DATABASE [DatabaseName]
SET ENABLE_BROKER WITH ROLLBACK IMMEDIATE;// C#
public class Product
{
public int Id { get; set; }
public string Name { get; set; }
}
using SqlTableDependency.Extensions;
using SqlTableDependency.Extensions.Enums;
internal class ProductsSqlTableDependencyProvider : SqlTableDependencyProvider<Product>
{
private readonly ILogger logger;
internal ProductsSqlTableDependencyProvider(ConnectionStringSettings connectionStringSettings, IScheduler scheduler, ILogger logger)
: base(connectionStringSettings, scheduler, LifetimeScope.UniqueScope)
{
this.logger = logger ?? throw new ArgumentNullException(nameof(logger));
}
internal ProductsSqlTableDependencyProvider(string connectionString, IScheduler scheduler, ILogger logger)
: base(connectionString, scheduler, LifetimeScope.UniqueScope)
{
this.logger = logger ?? throw new ArgumentNullException(nameof(logger));
}
protected override ModelToTableMapper<Product> OnInitializeMapper(ModelToTableMapper<Product> modelToTableMapper)
{
modelToTableMapper.AddMapping(c => c.Id, nameof(Product.Id));
return modelToTableMapper;
}
protected override void OnInserted(Product product)
{
base.OnInserted(product);
logger.Trace("Entity was added");
LogChangeInfo(product);
}
protected override void OnUpdated(Product product, Product oldValues)
{
base.OnUpdated(entity, oldValues);
logger.Trace("Entity was modified");
LogChangeInfo(product);
}
protected override void OnDeleted(Product product)
{
base.OnDeleted(product);
logger.Trace("Entity was deleted");
LogChangeInfo(product);
}
private void LogChangeInfo(Product product)
{
Console.WriteLine(Environment.NewLine);
Console.WriteLine("Id: " + product.Id);
Console.WriteLine("Name: " + product.Name);
Console.WriteLine("#####");
Console.WriteLine(Environment.NewLine);
}
protected override void OnError(Exception exception)
{
logSource.Error(exception);
}
}//Program.cs
using System.Configuration;
using System.Reactive.Concurrency;
namespace SqlTableDependency.Extensions.Sample
{
class Program
{
static void Main(string[] args)
{
var connectionString = ConfigurationManager.ConnectionStrings["FargoEntities"].ConnectionString;
using var productsProvider = new ProductsSqlTableDependencyProvider(connectionString, ThreadPoolScheduler.Instance, new ConsoleLogger());
productsProvider.SubscribeToEntityChanges();
Console.ReadKey();
}
}
}SqlServer PubSub notifications via Redis and SqlTableDependencyProvider extension
Install-Package Joker.Redis
Download and run redis-server (https://redis.io/download) or use Docker (see above).
Server side:
public class ProductSqlTableDependencyRedisProvider : SqlTableDependencyRedisProvider<Product>
{
public ProductSqlTableDependencyRedisProvider(ISqlTableDependencyProvider<Product> sqlTableDependencyProvider, IRedisPublisher redisPublisher)
: base(sqlTableDependencyProvider, redisPublisher)
{
}
}string redisUrl = ConfigurationManager.AppSettings["RedisUrl"]; //localhost
var redisPublisher = new RedisPublisher(redisUrl);
await redisPublisher.PublishAsync("messages", "hello");
using var productsProvider = new ProductsSqlTableDependencyProvider(connectionString, ThreadPoolScheduler.Instance, new ConsoleLogger());
using var productSqlTableDependencyRedisProvider = new ProductSqlTableDependencyRedisProvider(productsProvider, redisPublisher, ThreadPoolScheduler.Instance)
.StartPublishing();Client side:
private static async Task<RedisSubscriber> CreateRedisSubscriber(string redisUrl)
{
var redisSubscriber = new RedisSubscriber(redisUrl);
await redisSubscriber.Subscribe(channelMessage => { Console.WriteLine($"OnNext({channelMessage.Message})"); },
"messages");
await redisSubscriber.Subscribe(channelMessage =>
{
var recordChange = JsonConvert.DeserializeObject<RecordChangedNotification<Product>>(channelMessage.Message);
Console.WriteLine($"OnNext Product changed({recordChange.ChangeType})");
Console.WriteLine($"OnNext Product changed({recordChange.Entity.Id})");
}, nameof(Product) + "-Changes");
await redisSubscriber.Subscribe(channelMessage =>
{
var tableDependencyStatus = JsonConvert.DeserializeObject<TableDependencyStatus>(channelMessage.Message);
Console.WriteLine($"OnNext tableDependencyStatus changed({tableDependencyStatus})");
}, nameof(Product) + "-Status");
redisSubscriber.WhenIsConnectedChanges.Subscribe(c => Console.WriteLine($"REDIS is connected: {c}"));
return redisSubscriber;
} private static void CreateReactiveProductsViewModel()
{
var reactiveData = new ReactiveData<Product>();
var redisUrl = ConfigurationManager.AppSettings["RedisUrl"];
using var entitiesSubscriber = new DomainEntitiesSubscriber<Product>(new RedisSubscriber(redisUrl), reactiveData);
string connectionString = ConfigurationManager.ConnectionStrings["FargoEntities"].ConnectionString;
var reactiveProductsViewModel = new ReactiveProductsViewModel(new SampleDbContext(connectionString),
reactiveData, new WpfSchedulersFactory());
reactiveProductsViewModel.SubscribeToDataChanges();
reactiveProductsViewModel.Dispose();
}