The five components of fundamental distributed services are:
Remote Procedure Call. As a fundamental building block of DCE, the Remote Procedure Call (RPC) provides a basic and standardized method to communicate between a client and server. This enables programmers to develop distributed applications as easily as traditional, single-system programs, since functions developed on one machine can be moved to remote ones and accessed over the network. By being network- and protocol-independent -- masking the differences between data representations on different machines -- RPCs allow programs to work easily across heterogeneous networks.
Directory Service. The directory service gives each server, file, disk, or other network resource a unique name, ensuring that users can access them without knowing, for example, a network address.
Time Service. To help keep applications from stepping on each other, DCE provides a time service that regulates the system clocks in a network -- providing applications a single-time reference for scheduling activities and determining sequences of events.
Security Service. Since the biggest concern about distributed environments is unauthorized access, DCE implements a security service based on Kerberos, a sophisticated security system, developed at the Massachusetts Institute of Technology. DCE lets individual machines maintain their own security. But when users want to access the network, DCE's security service steps in to detect message corruption, ensure the privacy of confidential information, validate user identities, and determine access privileges.
Threads Service. A vital tool for dealing with multiple clients in client/server environments, threads service supports concurrent programming, allowing an application to process concurrent activities. This means, for example, that a machine can simultaneously process user input at the same time it communicates with a remote file server.
The key component of DCE's data-sharing services is its distributed file system, which makes remote file access as easy as local file access. It also allows files to be centrally managed and controlled without giving up the performance of local access.
The Open Software Foundation (OSF) plans to release an upgrade called DCE 1.1. Key enhancements include an improved administration function, which makes it easier to configure or administer a cell from a single session, and to provide better control over what services are running, from a host. Another administrative enhancement includes on-demand start-up of the DCE servers, remote access to information on different devices throughout the network, and improved RPC security.
Other improvements affect security and "internationalization." The new security features -- called GSSAPI for Generic Security Service Application Program Interface -- allow non-RPC applications operating in a DCE environment to use a DCE authentication protocol, increasing security across more of the network. Internationalization permits the use of kanji and other multibyte characters, and code set interoperability between clients and servers.
"Our plans for DCE 1.2 include features -- such as more automated information collection, improved scalability, and performance -- that will help simplify the tasks of system administrators," says Kathryn DeNitto, DCE technology manager at OSF.