Synchronous Query

.Get(Request, CancellationToken, IDictionary<string, object>) returns possible value. Null, if no handler produced a request.

// Create service
IService service = Services.Create(ServiceHandlers.Instance);
// Create request
TypeRequest request = new TypeRequest("System.String");
// Issue request
Type? type = service.Get<TypeRequest, Type>(request);

.TryGet(Request, out Response, CancellationToken, IDictionary<string, object>) returns true if value was completed.

// Create service
IService service = Services.Create(ServiceHandlers.Instance);
// Create request
TypeRequest request = new TypeRequest("System.String");
// Issue request
if (service.TryGet(request, out Type? type)) WriteLine(type);

.GetRequired(Request, CancellationToken, IDictionary<string, object>) is used when Completed result is expected.

// Create service
IService service = Services.Create(ServiceHandlers.Instance);
// Create request
TypeRequest request = new TypeRequest("System.String");
// Issue request
Type type = service.GetRequired<TypeRequest, Type>(request);

.Invoke(Request, CancellationToken, IDictionary<string, object>) calls a service without expecting a response value.

// Handler
Action<IQuery<WakeUpRequest, Avalanche.Void>> wakeupHandler = q => { Console.WriteLine("Wake Up!"); q.Response.SetCompleted(); };
// Create service
IService service = Services.Create(wakeupHandler);
// Create request
WakeUpRequest request = new WakeUpRequest();
// Issue request
service.Invoke(request);

struct WakeUpRequest { }

.TryInvoke(Request, CancellationToken, IDictionary<string, object>) tries to a service that might not me handled.

// Handler
Action<IQuery<WakeUpRequest, Avalanche.Void>> wakeupHandler = q => { Console.WriteLine("Wake Up!"); q.Response.SetCompleted(); };
// Create service
IService service = Services.Create(wakeupHandler);
// Create request
WakeUpRequest request = new WakeUpRequest();
// Invoke
bool ok = service.TryInvoke(request);

Asynchronous Query

.GetAsync(Request, CancellationToken, IDictionary<string, object>) and GetAsyncQuickAbort() executes query asynchronously.

// Create service
IService service = Services.Create(ServiceHandlers.Instance);
// Create request
TypeRequest request = new TypeRequest("System.String");
// Issue request
Type? type = await service.GetAsync<IRequest, Type>(request);

.GetRequiredAsync(Request, CancellationToken, IDictionary<string, object>) and GetRequiredAsyncQuickAbort() executes query asynchronously and expects a result.

// Create service
IService service = Services.Create(ServiceHandlers.Instance);
// Create request
TypeRequest request = new TypeRequest("System.String");
// Issue request
Type type = await service.GetRequiredAsync<IRequest, Type>(request);

.InvokeAsync(Request, CancellationToken, IDictionary<string, object>) and InvokeAsyncQuickAbort() calls a service without expecting a response value.

// Handler
Action<IQuery<WakeUpRequest, Avalanche.Void>> wakeupHandler = q => { Console.WriteLine("Wake Up!"); q.Response.SetCompleted(); };
// Create service
IService service = Services.Create(wakeupHandler);
// Create request
WakeUpRequest request = new WakeUpRequest();
// Invoke async
await service.InvokeAsync(request);

struct WakeUpRequest { }

Error Handling

If no handler produced a value and result was Required, then ServiceException is thrown with ServiceMessages.Instance.BadQueryNoValue error code.

// Create service
IService service = Services.Create(ServiceHandlers.Instance);
// Create request
TypeRequest request = new TypeRequest("System.NotFound");
// Issue request
try
{
    Type type = service.GetRequired<IRequest, Type>(request);
}
catch (Exception e) when (e.HResult == Services.MessageDescription.BadQueryNoValue.Code)
{
    WriteLine("No result, type not found.");
}

See ServiceMessages for other error messages.

Full Example

Full example

using System;
using System.Threading.Tasks;
using Avalanche.Service;
using static System.Console;

public class service_query
{
    public async static Task Run()
    {
        {
            // <01>
            // Create service
            IService service = Services.Create(ServiceHandlers.Instance);
            // Create request
            TypeRequest request = new TypeRequest("System.String");
            // Issue request
            Type? type = service.Get<TypeRequest, Type>(request);
            // </01>
        }
        {
            // <02>
            // Create service
            IService service = Services.Create(ServiceHandlers.Instance);
            // Create request
            TypeRequest request = new TypeRequest("System.String");
            // Issue request
            if (service.TryGet(request, out Type? type)) WriteLine(type);
            // </02>
        }
        {
            // <03>
            // Create service
            IService service = Services.Create(ServiceHandlers.Instance);
            // Create request
            TypeRequest request = new TypeRequest("System.String");
            // Issue request
            Type type = service.GetRequired<TypeRequest, Type>(request);
            // </03>
        }
        {
            // <04>
            // Handler
            Action<IQuery<WakeUpRequest, Avalanche.Void>> wakeupHandler = q => { Console.WriteLine("Wake Up!"); q.Response.SetCompleted(); };
            // Create service
            IService service = Services.Create(wakeupHandler);
            // Create request
            WakeUpRequest request = new WakeUpRequest();
            // Issue request
            service.Invoke(request);
            // </04>
        }
        {
            // <05>
            // Handler
            Action<IQuery<WakeUpRequest, Avalanche.Void>> wakeupHandler = q => { Console.WriteLine("Wake Up!"); q.Response.SetCompleted(); };
            // Create service
            IService service = Services.Create(wakeupHandler);
            // Create request
            WakeUpRequest request = new WakeUpRequest();
            // Invoke
            bool ok = service.TryInvoke(request);
            // </05>
        }

        {
            // <11>
            // Create service
            IService service = Services.Create(ServiceHandlers.Instance);
            // Create request
            TypeRequest request = new TypeRequest("System.String");
            // Issue request
            Type? type = await service.GetAsync<IRequest, Type>(request);
            // </11>
        }
        {
            // <12>
            // Create service
            IService service = Services.Create(ServiceHandlers.Instance);
            // Create request
            TypeRequest request = new TypeRequest("System.String");
            // Issue request
            Type type = await service.GetRequiredAsync<IRequest, Type>(request);
            // </12>
        }

        {
            // <13>
            // Handler
            Action<IQuery<WakeUpRequest, Avalanche.Void>> wakeupHandler = q => { Console.WriteLine("Wake Up!"); q.Response.SetCompleted(); };
            // Create service
            IService service = Services.Create(wakeupHandler);
            // Create request
            WakeUpRequest request = new WakeUpRequest();
            // Invoke async
            await service.InvokeAsync(request);
            // </13>
        }

        {
            // <20>
            // Create service
            IService service = Services.Create(ServiceHandlers.Instance);
            // Create request
            TypeRequest request = new TypeRequest("System.NotFound");
            // Issue request
            try
            {
                Type type = service.GetRequired<IRequest, Type>(request);
            }
            catch (Exception e) when (e.HResult == Services.MessageDescription.BadQueryNoValue.Code)
            {
                WriteLine("No result, type not found.");
            }
            // </20>
        }
    }

    // <99>
    struct WakeUpRequest { }
    // </99>

}