public CustomerCommands(EventStreamCollection <Customer> eventStreamManagersCollection, CustomerQueries customerQueries)
{
managers = eventStreamManagersCollection;
queries = customerQueries;
}
static async Task Main(string[] args)
{
Console.WriteLine("\nEventStreamDotNet demo\n");
// The library can optionally be configured with any implementation of the
// standard Microsoft ILoggerFactory to enable debug-level log output from
// the library. Here we're using Serilog but Microsoft's own basic logger
// or other libraries like NLog could be used. Debug logging can generate
// significant amounts of log output, only enable it in the library if you
// absolutely need it.
var loggerFactory = new LoggerFactory()
.AddSerilog(new LoggerConfiguration()
.MinimumLevel.Verbose()
.WriteTo.Console()
.CreateLogger());
try
{
// Populate the EventStreamDotNet configuration classes from appsettings.json. This could
// also populate any application-specific configuration systems using the same process.
AppConfig.LoadConfiguration();
Console.WriteLine($"Database: {AppConfig.Get.EventStreamDotNet.Database.ConnectionString}");
Console.WriteLine($"Log Table: {AppConfig.Get.EventStreamDotNet.Database.EventTableName}");
Console.WriteLine($"Snapshot Table: {AppConfig.Get.EventStreamDotNet.Database.SnapshotTableName}");
// Optionally reset the database
Console.Write("\nDelete all records from the demo database (Y/N)? ");
var key = Console.ReadKey(true);
if (key.Key.Equals(ConsoleKey.Y))
{
Console.WriteLine("YES\n");
await ResetDatabase();
}
else
{
Console.WriteLine("NO\n");
}
// The demo will use the library's collection class to interact with the event stream. Declare
// it now because we'll obtain it differently depending on whether we use dependency injection.
EventStreamCollection <Customer> customerManagers;
// Optionally use dependency injection.
Console.Write("Use dependency injection (Y/N)? ");
key = Console.ReadKey(true);
// Using dependency injection
if (key.Key.Equals(ConsoleKey.Y))
{
Console.WriteLine("YES\n");
// Configure and register the library services
var services = new ServiceCollection();
services.AddEventStreamDotNet(
loggerFactory: loggerFactory,
domainModelConfigs: cfg =>
{
cfg.AddConfiguration <Customer>(AppConfig.Get.EventStreamDotNet);
},
domainEventHandlers: cfg =>
{
cfg.RegisterDomainEventHandler <Customer, CustomerEventHandler>();
},
projectionHandlers: cfg =>
{
cfg.RegisterProjectionHandler <Customer, CustomerProjectionHandler>();
});
// Register the domain model's event stream collection for DI
services.AddSingleton <EventStreamCollection <Customer> >();
// Create the DI service provider.
var serviceProvider = services.BuildServiceProvider();
// Because we're doing a simple console demo, only the library is using DI to
// resolve references; we'll go ahead and do it the "anti-pattern" way for brevity.
// However, this does actually use DI, the EventStreamCollection constructor has a
// dependency on the three library services registered above, and of course, the
// collection itself was just registered above as a singleton service.
customerManagers = serviceProvider.GetService <EventStreamCollection <Customer> >();
}
// Not using dependency injection
else
{
Console.WriteLine("NO\n");
// Configure the library services
var eventServices = new DirectDependencyServiceHost(
loggerFactory: loggerFactory,
domainModelConfigs: cfg =>
{
cfg.AddConfiguration <Customer>(AppConfig.Get.EventStreamDotNet);
},
domainEventHandlers: cfg =>
{
cfg.RegisterDomainEventHandler <Customer, CustomerEventHandler>();
},
projectionHandlers: cfg =>
{
cfg.RegisterProjectionHandler <Customer, CustomerProjectionHandler>();
});
// Create the event stream collection.
customerManagers = new EventStreamCollection <Customer>(eventServices);
}
// The rest of the demo works the same way with or without the use of dependency injection.
// This is just one possible usage pattern. The thinking here is that a CQRS service will
// execute commands against a collection of event streams tied to the same domain model, and
// will execute queries against snapshots and projections for that domain model. Probably a
// production app would not start a CQRS query service with the EventStreamDotNet configuration,
// however (it does not, for example, specify projection table names, which might even be stored
// into a completely separate database for performance reasons).
var customerQueries = new CustomerQueries(customerManagers);
var customerCommands = new CustomerCommands(customerManagers, customerQueries);
var customerId = "12345678";
// This is a simple select against the event stream to check whether the ID has ever been used.
var customerExists = await customerQueries.CustomerExists(customerId);
Console.WriteLine($"Customer id {customerId} exists? {customerExists.Output}");
// When queries and commands succeed, the response is usually an updated snapshot of the dmain data.
APIResult <Customer> result;
// Create or read the customer record
if (!customerExists.Output)
{
var residence = new Address
{
Street = "10 Main St.",
City = "Anytown",
StateOrProvince = "TX",
PostalCode = "90210",
Country = "USA"
};
var person = new Person
{
FullName = "John Doe",
FirstName = "John",
LastName = "Doe",
Residence = residence,
TaxId = "555-55-1234",
DateOfBirth = DateTimeOffset.Parse("05/01/1960")
};
Console.WriteLine("Creating new customer.");
result = await customerCommands.NewCustomer(customerId, person, residence);
if (!result.Success)
{
throw new Exception($"Failed to create new customer: {result.Message}");
}
}
else
{
Console.WriteLine("Retrieving customer.");
result = await customerQueries.FindCustomer(customerId);
if (!result.Success)
{
throw new Exception($"Failed to retrieve customer snapshot: {result.Message}");
}
}
// Add or remove a spouse
var customer = result.Output;
if (customer.Spouse == null)
{
var spouse = new Person
{
FullName = "Jane Doe",
FirstName = "Jane",
LastName = "Doe",
Residence = customer.PrimaryAccountHolder.Residence,
TaxId = "333-99-4321",
DateOfBirth = DateTimeOffset.Parse("11/01/1960")
};
Console.WriteLine("Adding spouse (yay).");
result = await customerCommands.UpdateSpouse(customerId, spouse);
if (!result.Success)
{
throw new Exception($"Failed to add spouse: {result.Message}");
}
}
else
{
Console.WriteLine("Removing spouse (boo).");
result = await customerCommands.UpdateSpouse(customerId, null);
if (!result.Success)
{
throw new Exception($"Failed to remove spouse: {result.Message}");
}
}
}
catch (Exception ex)
{
Console.WriteLine($"\nException caught in Program.Main:\n{ex.Message}");
if (ex.InnerException != null)
{
Console.WriteLine(ex.InnerException.Message);
}
}
finally
{
// Purge any pending log entries and dispose.
Log.CloseAndFlush();
}
if (!Debugger.IsAttached)
{
Console.WriteLine("\n\nPress any key to exit...");
Console.ReadKey(true);
}
}