HP DCE/9000 Application Development Tools for HP-UX 11i Release Note

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HP DCE/9000 Version 1.8 Application Development Tools for HP-UX 11i Release Note
Developing DCE Applications with HP DCE/9000
information. Performance trade-offs in CDS's usage of memory, disk, cache, the network, and
time-outs are optimized to this very specialized purpose.
The generality of the application programming interfaces to CDS masks the specificity of this
purpose, and gives CDS the appearance of a general-purpose database system. It is not; the
optimizations of CDS for its low-volume and weakly-replicated storage, and for retrieval of
server bindings in a fairly static name space, are rarely optimal for other purposes. Moreover,
other uses of CDS directly compete and interfere with its use and availability as a critical core
component of the DCE system.
Application developers are frequently tempted to use CDS for the direct storage of
information other than server bindings. For example, the developer of a telephone number
directory service may consider using CDS to store the information directly. This is a bad idea,
as the volume of information could overwhelm the in-memory CDS data structures, and very
frequent read accesses could slow CDS performance and lock out DCE server lookup requests.
A much better strategy would be to implement a database server designed specifically for the
telephone number directory service, and then store the bindings of that server in CDS for
lookup by clients. In this way, other uses do not compromise CDS in its intended use as a
critical DCE component.
Cell Directory Service Programming Interfaces
The supported programming interfaces to CDS are the RPC Name Service Independent
(RPC_NS) interface and the X/Open Directory Service (XDS) interface. The RPC_NS function
call prototypes are in the include file /usr/include/dce/rpc.h. The XDS function call
prototypes are in the include file / usr/include/xds.h. The RPC_NS interface is the
procedural interface used by the core DCE components and most applications. The XDS
interface is an object-oriented interface appropriate for use with other X/Open standards such
as X.500. Both the RPC_NS and XDS interfaces support many common name space functions,
but lack administrative capabilities such as the ability to create and delete directories and
manage replication.
dcecp is the recommended tool for performing CDS administrative functions such as creating
and deleting directories and managing replication. dcecp can be called in a shell script, but is
not a programming interface.
CDS_DELAY_REPLICA_CREATE
When creating the directory and its readonly replica continuously (i.e., without any time gap),
the creation of replica is started before the creation of Master is completed. So an error
"requested entry does not exist" occurs. To avoid this export the environment variable
CDS_DELAY_REPLICA_CREATE which will delay the creation of the replica.
Usage of this environment variable:-
Run the command "export CDS_DELAY_REPLICA_CREATE=sometimestamp". Here the