oneway interface

Oneway interfaces

In early betas, the Android IPC was strictly synchronous. This means that service invocations had to wait for the return value of the remote method to arrive back to the caller. This is generally an advantage because the caller can be sure that the called service received the invocation by the time the remote method returns. In some cases, however, this causes the caller to wait unnecessarily. If synchronicity is not required and the method has no return value, oneway AIDL interfaces may be used.

Oneway methods are specified by addind the oneway keyword to the AIDL interface definition.

package com.elfylin; 
oneway interface IMyServiceOneway { 
    String getValue();
}

package com.elfylin;
public interface IMyServiceOneway extends android.os.IInterface
{
    /** Local-side IPC implementation stub class. */
    public static abstract class Stub extends android.os.Binder implements com.elfylin.IMyServiceOneway
    {
        private static final java.lang.String DESCRIPTOR = "com.elfylin.IMyServiceOneway";
        /** Construct the stub at attach it to the interface. */
        public Stub()
        {
            this.attachInterface(this, DESCRIPTOR);
        }
        /**
         * Cast an IBinder object into an com.elfylin.IMyServiceOneway interface,
         * generating a proxy if needed.
         */
        public static com.elfylin.IMyServiceOneway asInterface(android.os.IBinder obj)
        {
            if ((obj==null)) {
            return null;
            }
            android.os.IInterface iin = (android.os.IInterface)obj.queryLocalInterface(DESCRIPTOR);
            if (((iin!=null)&&(iin instanceof com.elfylin.IMyServiceOneway))) {
                return ((com.elfylin.IMyServiceOneway)iin);
            }
            return new com.elfylin.IMyServiceOneway.Stub.Proxy(obj);
        }
        public android.os.IBinder asBinder()
        {
            return this;
        }
        @Override public boolean onTransact(int code, android.os.Parcel data, android.os.Parcel reply, int flags) throws android.os.RemoteException
        {
            switch (code)
            {
                case INTERFACE_TRANSACTION:
                {
                    reply.writeString(DESCRIPTOR);
                    return true;
                }
                case TRANSACTION_getValue:
                {
                    data.enforceInterface(DESCRIPTOR);
                    java.lang.String _result = this.getValue();
                    reply.writeString(_result);
                    return true;
                }
            }
            return super.onTransact(code, data, reply, flags);
        }
        private static class Proxy implements com.elfylin.IMyServiceOneway
        {
            private android.os.IBinder mRemote;
            Proxy(android.os.IBinder remote)
            {
                mRemote = remote;
            }
            public android.os.IBinder asBinder()
            {
                return mRemote;
            }
            public java.lang.String getInterfaceDescriptor()
            {
                return DESCRIPTOR;
            }
            public java.lang.String getValue() throws android.os.RemoteException
            {
                android.os.Parcel _data = android.os.Parcel.obtain();
                java.lang.String _result;
                try {
                    _data.writeInterfaceToken(DESCRIPTOR);
                    mRemote.transact(Stub.TRANSACTION_getValue, _data, null, android.os.IBinder.FLAG_ONEWAY);
                }
                finally {
                    _data.recycle();
                }
                return _result;
            }
        }
        static final int TRANSACTION_getValue = (android.os.IBinder.FIRST_CALL_TRANSACTION + 0);
    }
    public java.lang.String getValue() throws android.os.RemoteException;
}

                try {  
                    _data.writeInterfaceToken(DESCRIPTOR);  
                    mRemote.transact(Stub.TRANSACTION_getValue, _data, _reply, 0);  
                    _reply.readException();  
                    _result = _reply.readString();
}

difference from no oneway