aeron-client/src/main/java/io/aeron/Publication.java
public final long offer(final DirectBuffer buffer, final int offset, final int length)
    {
        return offer(buffer, offset, length, null);
    }
public final long offer(final DirectBuffer buffer, final int offset, final int length)
    {
        return offer(buffer, offset, length, null);
    }
Non-blocking publish of a partial buffer containing a message.

@param buffer containing message.
@param offset offset in the buffer at which the encoded message begins.
@param length in bytes of the encoded message.
@return The new stream position, otherwise a negative error value of {@link #NOT_CONNECTED},
{@link #BACK_PRESSURED}, {@link #ADMIN_ACTION}, {@link #CLOSED}, or {@link #MAX_POSITION_EXCEEDED}.