Overview

THIS CHAPTER COVERS APPLICATION COMMUNICATIONS over a network, using DECnet. This chapter builds on the file operations discussed in Chapters 15 and 17.

OpenVMS systems are commonly configured into networks of computer systems that consist of machines running OpenVMS and various other operating systems. These systems and these networks use a variety of networking protocols, such as DECnet, the Open Systems Interconnect (OSI), and Internet Protocol (IP). And a OpenVMS Cluster is a form of a network, running a networking protocol known as system communications services (SCS).

DECnet Phase IV and DECnet-Plus are two of the networking packages commonly used on many OpenVMS systems, and on DIGITAL Unix and ULTRIX systems, as well as on various other systems. DECnet-Plus can operate over various transports, including DECnet Phase IV, OSI, and IP. For the purposes of this book, both DECnet packages are sufficiently similar and will be referred to collectively as DECnet. DECnet network terms are used throughout this book.

Computer systems configured in a network are refered to as host nodes. The networking software on these nodes provide a variety of services to users, such as network terminals, remote file access, and disk and tape access. These services are all based on software layered onto the basic interprocess communications services provided by the networking package. These services all require software running on each node. In DECnet terms, these network services are