Zte zxmsg 5200, Technical Manual

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Chapter 5 - Software Structure
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interference. This is a problem of data integrity and consistency in a
shared system.
Some concurrent control mechanisms will be used to solve this
problem. The mechanisms will execute a transaction without
interference from other transactions and eliminate inconsistent data
caused by concurrent transactions. The traditional concurrent control
mechanisms are divided into two kinds: Lock method and Timestamp
method, which are not used in the ZXMSG 5200 system because the
lock method needs additional overhead to test the dead lock and the
lock method will affect efficiency since transactions need be rolled
back, .
The ZXMSG 5200 system uses two methods to solve the concurrency
problem:
Providing synchronous or asynchronous messages only with an
access interface for processes with higher priority, which can
ensure time-series data access;
Requiring processes which access to the database in a synchronous
invocation mode with priorities not higher than data processes.
Since only the operating system process has a priority higher than the
database and the access to the operating system is not frequent
comparatively, the two methods will not affect the system functions.
Service process most frequently accessing the database can adopt the
synchronous invocation mode.
3. Integrity and consistency of modifying database data
The man-machine command sub-module can guarantee ZXMSG 5200
data’s integrity and consistency. The O&M terminal usually sends
commands. The man-machine command sub-module analyzes and
explains these commands to determine data validity; and then the
sub-module operate the database according to the commands. If the
operation fails, the data before the operation will be recovered.
Operation Support System
The system consists of process dispatch, communication, file operation,
version control, diagnosis and test, active/standby control, system
monitoring and alarm. The supporting/monitoring system is also called R
system for short. Figure 15 shows the internal functional sub-modules.