Synchronous Query

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

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

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

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

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

// Issue request
Type type = service.GetRequired(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!");
// Create service
IService service = Services.Create(wakeupHandler, CachePolicies.Default);
// Create request
WakeUpRequest request = new WakeUpRequest();
// Invoke
service.TryInvoke(request);

struct WakeUpRequest { }

Asynchronous Query

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

// Issue request
Type? type = await service.GetAsync(request);

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

// Issue request
Type type = await service.GetRequiredAsync(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!");
// Create service
IService service = Services.Create(wakeupHandler, CachePolicies.Default);
// 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 ServiceEvent.BadQueryNoValue error code.

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

See Events for other error types.

Full Example

Full example

using System;
using System.Threading.Tasks;
using Avalanche.Service;
using Avalanche.Utilities;

public class service_query
{
    public async static Task Run()
    {
        {
            // <0>
            // Create service
            IService<TypeRequest, Type> service = Services.Create<TypeRequest, Type>(ServiceHandlers.Instance, CachePolicies.Default);
            // Create request
            TypeRequest request = new TypeRequest("System.String");
            // Issue request
            Type? type = service.Get(request);
            // </0>
        }

        {
            // <1>
            // Create service
            IService<TypeRequest, Type> service = Services.Create<TypeRequest, Type>(ServiceHandlers.Instance, CachePolicies.Default);
            // Create request
            TypeRequest request = new TypeRequest("System.String");
            // Issue request
            if (service.TryGet(request, out Type? type)) Console.WriteLine("Got type");
            // </1>
        }

        {
            // Create service
            IService<TypeRequest, Type> service = Services.Create<TypeRequest, Type>(ServiceHandlers.Instance, CachePolicies.Default);
            // Create request
            TypeRequest request = new TypeRequest("System.String");
            // <2>
            // Issue request
            Type type = service.GetRequired(request);
            // </2>
        }

        {
            // <3>
            // Handler
            Action<IQuery<WakeUpRequest, Avalanche.Void>> wakeupHandler = q => Console.WriteLine("Wake Up!");
            // Create service
            IService service = Services.Create(wakeupHandler, CachePolicies.Default);
            // Create request
            WakeUpRequest request = new WakeUpRequest();
            // Invoke
            service.TryInvoke(request);
            // </3>
        }

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

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

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

    // <3b>
    struct WakeUpRequest { }
    // </3b>

}