1. A system for providing message queues in a middleware machine environment, comprising: a middleware machine environment including one or more microprocessors; a first node and a second node operating in the middleware machine environment; a message receiver on the first node; a message sender on the second node; a shared memory created on the first node and associated with the message receiver, wherein the shared memory includes a heap data structure for storing messages, a first message queue including a first ring structure for storing metadata identifying addresses of messages within the heap data structure, and wherein the first node communicates the first ring structure to the second node and the second node is configured to create, in response to the communicated first ring structure, a second message queue including a second ring structure that shadows the first message queue and is associated with the message sender; wherein the message sender on the second node operates to allocate a portion of the heap data structure for writing a message directly into the heap data structure and maintain metadata in the first message queue identifying an address of the message within the heap data structure; and wherein the message sender is configured to use remote direct memory access (RDMA) for the writing of the message and for locking the first message queue during the writing of the message to prevent any other node from writing to the shared memory.