org.apache.ignite.services

Interface ServiceCallInterceptor

All Superinterfaces:

Serializable

public interface ServiceCallInterceptor
extends Serializable

Service call interceptor.

Allows the user to intercept the call to any service method except lifecycle methods (init(), execute() and cancel()).

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 service configuration. Each interceptor invokes the next interceptor in the chain using a delegated call, the last interceptor will call the service method.

Usage example:

 ServiceCallInterceptor security = (mtd, args, ctx, svcCall) -> {
     if (!CustomSecurityProvider.get().access(mtd, ctx.currentCallContext().attribute("sessionId")))
         throw new SecurityException("Method invocation is not permitted");

     // Execute remaining interceptors and service method.
     return svcCall.call();
 };

 ServiceCallInterceptor audit = (mtd, args, ctx, svcCall) -> {
     String sessionId = ctx.currentCallContext().attribute("sessionId");
     AuditProvider prov = AuditProvider.get();

     // Record an event before execution of the method.
     prov.recordStartEvent(ctx.name(), mtd, sessionId);

     try {
         // Execute service method.
         return svcCall.call();
     }
     catch (Exception e) {
         // Record error.
         prov.recordError(ctx.name(), mtd, sessionId), e.getMessage());

         // Re-throw exception to initiator.
         throw e;
     }
     finally {
         // Record finish event after execution of the service method.
         prov.recordFinishEvent(ctx.name(), mtd, sessionId);
     }
 }

 ServiceConfiguration svcCfg = new ServiceConfiguration()
     .setName("service")
     .setService(new MyServiceImpl())
     .setMaxPerNodeCount(1)
     .setInterceptors(audit, security);

 // Deploy service.
 ignite.services().deploy(svcCfg);

 // Set context parameters for the service proxy.
 ServiceCallContext callCtx = ServiceCallContext.builder().put("sessionId", sessionId).build();

 // Make a service proxy with the call context to define the "sessionId" attribute.
 MyService proxy = ignite.services().serviceProxy("service", MyService.class, false, callCtx, 0);

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

See Also:

ServiceCallContext, ServiceContext

Method Summary

Modifier and Type	Method and Description
Object	invoke(String mtd, Object[] args, ServiceContext ctx, Callable<Object> next) Intercepts delegated service call.

Method Detail

invoke

Object invoke(String mtd,
              Object[] args,
              ServiceContext ctx,
              Callable<Object> next)
       throws Exception

Intercepts delegated service call.

Parameters:

mtd - Method name.

args - Method arguments.

ctx - Service context.

next - Delegated call to a service method and/or interceptor in the chain.

Returns:

Service call result.

Throws:

Exception