Implications of Mutual Dependencies
Mutual dependencies among DCE technology components result in restrictions in areas such as the startup of a cell. For example, since the security service depends on CDS to find the location of a security server, and CDS depends on the security service to verify the authenticity of a CDS server, how can a DCE system ever get started? This section identifies the implications of mutual dependencies in the areas of DCE system startup, porting and testing of DCE, and planning for DCE configuration.
· Implications for startup
Mutual dependencies in DCE technologies dictate the order in which some steps must be taken in bringing up a DCE client machine, a DCE
server machine, and a DCE cell. In particular, a DCE cell's servers must be started up in a particular order. The security server is started first, since its dependency on CDS can be circumvented
through the use of a local file to find security servers. Then the CDS server is started. For information on starting up DCE, see the OSF DCE Administration Guide - Introduction.
· Implications for porting and testing
The interdependencies among DCE technologies constrain the order in which technologies can be ported. DCE Threads can be
ported first, since other technologies use it, and it has no dependencies. Many of the other technologies have mutual dependencies, however. To resolve this, a porting effort can proceed by first
porting the libraries of all the components, and then going on to port and test the servers. GDS can be ported independently, since it has no dependencies on other DCE components. For information
on porting DCE technologies, see the OSF DCE Testing Guide.
· Implications for configuration
DCE technology interdependencies also have implications for configuration. The servers that other servers depend on are the
servers that are the highest priority for replication, in environments where high availability is important. This means that CDS and security servers should be replicated since other DCE servers
depend on them in order to operate. Among the various DFS servers, the fileset location server is the highest priority for replication. For information on DCE configuration, see the
OSF DCE Administration Guide - Introduction.
· Implications for application programmers
Since DCE RPC is integrated with DCE Threads, programmers writing RPC-based applications need to be aware of the
implications of using multiple threads of control. See the OSF DCE Application Development Guide - Introduction and Style Guide and
OSF DCE Application Development Guide - Core Components
for information about programming with threads.