Chapter 5 - Software Structure 
Confidential and Proprietary Information of ZTE CORPORATION  49 
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.