// Protocol Buffers - Google's data interchange format
// Copyright 2008 Google Inc. All rights reserved.
// http://code.google.com/p/protobuf/
//
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//
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package com.google.protobuf;
/**
* <p>An {@code RpcController} mediates a single method call. The primary
* purpose of the controller is to provide a way to manipulate settings
* specific to the RPC implementation and to find out about RPC-level errors.
*
* <p>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.
*
* <p>The methods provided by the {@code RpcController} interface are intended
* to be a "least common denominator" set of features which we expect all
* implementations to support. Specific implementations may provide more
* advanced features (e.g. deadline propagation).
*
* @author kenton@google.com Kenton Varda
*/
public interface RpcController {
// -----------------------------------------------------------------
// These calls may be made from the client side only. Their results
// are undefined on the server side (may throw RuntimeExceptions).
/**
* Resets the RpcController to its initial state so that it may be reused in
* a new call. This can be called from the client side only. It must not
* be called while an RPC is in progress.
*/
void reset();
/**
* After a call has finished, returns true if the call failed. The possible
* reasons for failure depend on the RPC implementation. {@code failed()}
* most only be called on the client side, and must not be called before a
* call has finished.
*/
boolean failed();
/**
* If {@code failed()} is {@code true}, returns a human-readable description
* of the error.
*/
String errorText();
/**
* Advises the RPC system that the caller desires that the RPC call be
* canceled. The RPC system may cancel it immediately, may wait awhile and
* then cancel it, or may not even cancel the call at all. If the call is
* canceled, the "done" callback will still be called and the RpcController
* will indicate that the call failed at that time.
*/
void startCancel();
// -----------------------------------------------------------------
// These calls may be made from the server side only. Their results
// are undefined on the client side (may throw RuntimeExceptions).
/**
* Causes {@code failed()} to return true on the client side. {@code reason}
* will be incorporated into the message returned by {@code errorText()}.
* If you find you need to return machine-readable information about
* failures, you should incorporate it into your response protocol buffer
* and should NOT call {@code setFailed()}.
*/
void setFailed(String reason);
/**
* If {@code true}, indicates that the client canceled the RPC, so the server
* may as well give up on replying to it. This method must be called on the
* server side only. The server should still call the final "done" callback.
*/
boolean isCanceled();
/**
* Asks that the given callback be called when the RPC is canceled. The
* parameter passed to the callback will always be {@code null}. The
* callback will always be called exactly once. If the RPC completes without
* being canceled, the callback will be called after completion. If the RPC
* has already been canceled when NotifyOnCancel() is called, the callback
* will be called immediately.
*
* <p>{@code notifyOnCancel()} must be called no more than once per request.
* It must be called on the server side only.
*/
void notifyOnCancel(RpcCallback<Object> callback);
}