com.google.protobuf.Service Maven / Gradle / Ivy
// Protocol Buffers - Google's data interchange format
// Copyright 2008 Google Inc. All rights reserved.
// https://developers.google.com/protocol-buffers/
//
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//
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package com.google.protobuf;
/**
* Abstract base interface for protocol-buffer-based RPC services. Services themselves are abstract
* classes (implemented either by servers or as stubs), but they subclass this base interface. The
* methods of this interface can be used to call the methods of the service without knowing its
* exact type at compile time (analogous to the Message interface).
*
* Starting with version 2.3.0, RPC implementations should not try to build on this, but should
* instead provide code generator plugins which generate code specific to the particular RPC
* implementation. This way the generated code can be more appropriate for the implementation in use
* and can avoid unnecessary layers of indirection.
*
* @author [email protected] Kenton Varda
*/
public interface Service {
/** Get the {@code ServiceDescriptor} describing this service and its methods. */
Descriptors.ServiceDescriptor getDescriptorForType();
/**
* Call a method of the service specified by MethodDescriptor. This is normally implemented as a
* simple {@code switch()} that calls the standard definitions of the service's methods.
*
*
Preconditions:
*
*
* - {@code method.getService() == getDescriptorForType()}
*
- {@code request} is of the exact same class as the object returned by {@code
* getRequestPrototype(method)}.
*
- {@code controller} is of the correct type for the RPC implementation being used by this
* Service. For stubs, the "correct type" depends on the RpcChannel which the stub is using.
* Server-side Service implementations are expected to accept whatever type of {@code
* RpcController} the server-side RPC implementation uses.
*
*
* Postconditions:
*
*
* - {@code done} will be called when the method is complete. This may be before {@code
* callMethod()} returns or it may be at some point in the future.
*
- The parameter to {@code done} is the response. It must be of the exact same type as would
* be returned by {@code getResponsePrototype(method)}.
*
- If the RPC failed, the parameter to {@code done} will be {@code null}. Further details
* about the failure can be found by querying {@code controller}.
*
*/
void callMethod(
Descriptors.MethodDescriptor method,
RpcController controller,
Message request,
RpcCallback done);
/**
* {@code callMethod()} requires that the request passed in is of a particular subclass of {@code
* Message}. {@code getRequestPrototype()} gets the default instances of this type for a given
* method. You can then call {@code Message.newBuilderForType()} on this instance to construct a
* builder to build an object which you can then pass to {@code callMethod()}.
*
* Example:
*
*
* MethodDescriptor method =
* service.getDescriptorForType().findMethodByName("Foo");
* Message request =
* stub.getRequestPrototype(method).newBuilderForType()
* .mergeFrom(input).build();
* service.callMethod(method, request, callback);
*
*/
Message getRequestPrototype(Descriptors.MethodDescriptor method);
/**
* Like {@code getRequestPrototype()}, but gets a prototype of the response message. {@code
* getResponsePrototype()} is generally not needed because the {@code Service} implementation
* constructs the response message itself, but it may be useful in some cases to know ahead of
* time what type of object will be returned.
*/
Message getResponsePrototype(Descriptors.MethodDescriptor method);
}