Remote
Procedure Call FAQ's
Remote
Procedure Call FAQ's
The best test as to "standards compliance" is whether or not the technology is fully documented and published. RPC/XDR is formally documented under the Internet standards RFC's 1014 and 1057 which are freely obtained from numerous FTP sites.
No, there are no other similar products that are true Open Systems standards compliant. Some vendors claim that their product is a "standard" simply because they declare it to be a standard, or because it enjoys an installed user base.
Actually, no it is not. ONC RPC/XDR was originally devised by Sun Microsystems better than ten years ago as an integral part of their Open Network Computing (ONC) strategy. The technology is both technically and commercially mature, been widely adopted across a wide variety of platforms over the years.
To facilitate this wide adoption, Sun actually placed the source code in the public domain, allowing vendors to port the product to numerous other platforms and operating systems.
Implementations of RPC are available for such diverse operating systems and environments as UNIX, DOS, Windows, Windows NT, MacOS, OS/2, VMS, VM, MVS, and others. Better than 120 companies offer products based on this technology.
A guide to ONC products and applications is published by Sun Microsystems and is available from them.
RPC is typically employed in any environment where a distributed application is required.
For our purposes, the term "distributed application" can be defined to mean any application where a portion of it resides on one computer while the remainder of the application resides on at least one (and perhaps more than one) other computer.
Note that the client/server model fits this definition quite nicely as the client and server are both viewed as being part of the same distributed application. However, RPC allows the model to be taken even further because the portions of the distributed application may in fact act on a peer to peer basis.
In a client/server relationship, one application component is always required to act as a client, while another component is always constrained to the role of being the server.
In a peer to peer relationship, any application component may act as a client, as a server, or act as both a client and a server depending upon application requirements.
The peer to peer relationship is particularly useful in the Tandem environment for handling what is known as unsolicited messages. Also, note that client/server is simply a subset of the peer to peer paradigm.
Parallel RPC allows for RPC servers running under the Guardian operating system to be "parallel servers". The concept is roughly analogous to that of a Pathway server class, where multiple copies of the same server are run in parallel across multiple CPU's.
The RPC Port Mapper process assigns incoming requests to different copies of the server allowing distribution of the transaction workload across many CPU's.
RPC/XDR is comprised of two distinct parts.
The first of these is RPC (Remote Procedure Call) which deals with the questions of how a remote procedure is called, how parameters are passed, and how the flow of control is coordinated.
The second portion is XDR (eXternal Data Representation) which deals with the question of how to correctly pass data and data structures between machines of varying types.
RPC is an ideal tool for building a high performance application involving a Tandem Guardian system.
It was designed from its very inception to be used in conjunction with the TCP/IP protocol stack. As a result, it does not require the overhead associated with other products which were design for asynchronous (serial) point to point connections and later retrofitted for TCP/IP.
One comparison showed RPC to be an order of magnitude faster than the retrofitted product.
A product demonstration at your site can be easily arranged.