Interface IServiceCallInterceptor

Represents service call interceptor.

Allows the user to intercept the call to any service method except lifecycle methods (Init(IServiceContext), Execute(IServiceContext) and Cancel(IServiceContext)).

A typical use of an interceptor is a middleware logic that applies to all custom methods in a service.

The user can specify multiple interceptors in the ServiceConfiguration. Each interceptor invokes the next interceptor in the chain using a delegated call, the last interceptor will call the service method.

class Security : IServiceCallInterceptor
{
  public object Invoke(string mtd, object[] args, IServiceContext ctx, Func<object> next)
  {
    if (!CustomSecurityProvider.Instance().Access(ctx.CurrentCallContext.GetAttribute("sessionId")))
      throw new SecurityException();

    // Execute remaining interceptors and service method.
    return next.Invoke();
  }
}

class Audit : IServiceCallInterceptor
{
  public object Invoke(string mtd, object[] args, IServiceContext ctx, Func<object> next)
  {
    var sessionId = ctx.CurrentCallContext.GetAttribute("sessionId");
    var audit = AuditProvider.Instance();

    audit.RecordEvent("start", mtd, sessionId);

    try
    {
      // Execute service method.
      return next.Invoke();
    }
    catch (Exception e)
    {
      // Record error.
      audit.RecordEvent("error", mtd, "id=" + sessionId + ", err=" + e.Message);

      // Re-throw exception to initiator.
      throw;
    }
    finally
    {
      // Record finish event after execution of the service method.
      audit.RecordEvent("finish", mtd, sessionId);
    }
  }
}

...

var svcCfg = new ServiceConfiguration()
{
  Name = "service",
  Service = new MyService(),
  MaxPerNodeCount = 1,
  Interceptors = new List<IServiceCallInterceptor> { new Audit(), new Security() }
};

// Deploy service.
ignite.GetServices().Deploy(svcCfg);

// Set context parameters for the service proxy.
var callCtx = new ServiceCallContextBuilder().Set("sessionId", sessionId).Build();

// Make service proxy with caller context to define sessionId attribute.
var proxy = ignite.GetServices().GetServiceProxy<IMyService>("service", false, callCtx);

// Service method call will be intercepted.
proxy.PlaceOrder(order1);
proxy.PlaceOrder(order2);

Namespace: Apache.Ignite.Core.Services

Assembly: Apache.Ignite.Core.dll

Syntax

public interface IServiceCallInterceptor

Methods

Invoke(String, Object[], IServiceContext, Func<Object>)

Intercepts delegated service call.

Declaration

object Invoke(string mtd, object[] args, IServiceContext ctx, Func<object> next)

Parameters

Type	Name	Description
System.String	mtd	Method name.
System.Object[]	args	Method arguments.
IServiceContext	ctx	Service context.
Func<System.Object>	next	Delegated call to a service method and/or interceptor in the chain.

Returns

Type	Description
System.Object	Service call result.

See Also

IServiceCallContext

IServiceContext