OSF DCE Application Development Guide--Core Components

OSF DCE Application Development Guide—Core Components
data for all servers on the host, and a database of endpoints (server addresses)
through which running servers can be contacted. Some of the functions that you can
remotely perform include starting and stopping servers.
• Application Message Service
This service provides a convenient way to manage readable character strings of
information that are usually displayed to application users. The service uses message
catalogs to maintain message text and explanations separate from the program so that
language, cultural, or other site-specific issues are easily managed for applications.
The message text can also be in memory during program execution for more efficient
programs.
• Serviceability
Serviceability is another kind of message text service with functionality beyond just
the display of general-purpose text. Serviceability is typically used for message text
about a server’s activity. Messages can be displayed through standard output or
standard error, or they can be routed to log files. The serviceability facility maintains
message text in catalogs (or memory) just as the application message service does;
but, in addition to the text and its explanation, additional attributes specify
subcomponents (program modules), message severity, the action users or programs
should take, and the debug level.
• Backing Store Database Service
You use a backing store to maintain typed data between invocations of applications.
For example, you could store application-specific configuration data in a backing
store, and then, when the application restarts, it could read the previous configuration
from the backing store. Data is stored and retreived by a Universal Unique Identifier
(UUID) or character string key, and each record (or data item) may have a standard
header if you wish.
As DCE has developed and improved, useful facilities such as serviceability have been
added to make DCE easier and more useful. For example, serviceability makes a
distributed application much easier to develop. With it, you can log and distinguish
debug messages from complex applications involving multiple clients, servers, and
threads. Although the major components are required to make DCE work, this kind of
facility is not required.
Some solutions developed to implement a major component’s feature can also prove
useful to your applications. For example, the security component must have a way to
maintain access control lists (ACLs). While the backing store was developed to handle
this kind of task, you can use this facility to store your own application-specific data
across invocations.
This first part of the
describes how you might put these useful facilities to work in your applications.
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