Coral: cron portable design
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CRON - Portable Design Running scripts as a service is easy to implement using Rozanski's utility see the following page srvStart utility tutorial for details. Uniform Server has this utility integrated into Coral’s control architecture allowing portable Cron to run as a service. For anyone wanting to modify or understand how it has been implemented the following describe its operation and design.
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Portable Cron
Portable Cron consists of an infinite program loop. It periodically checks an external file to determine when to exit. This concept is important when running the script as a service.
Service files
Cron service files are contained in folder UniServer\uni_con\cron_service and perform the following function:
Utility program files:
- logger.dll - Service utility
- srvstart.dll - Service utility program functions
- srvstart.exe - Service utility program
- srvstart.ini - Service utility configuration file
Individual service control:
- z_install.bat - Install a named service
- start_automatic.vbs - Starts service and changes service run status to Automatic
- z_service_start.bat - Starts service independently of changing run status.
- z_service_stop.bat - Stop service
- z_uninstall_service.bat - Remove service
Combined service control:
- install_start_service.bat - Uses the above to install and start cron service
- stop_uninstall_service.bat - Uses the above to stop and remove service.
Following provides details for each control file.
File description and function
For clarity only pertinent information is included (files title block has been removed)
srvstart.ini
This file allows you to specify any number of services to run. Each service is specified in a block starting with a unique name enclosed in square brackets. Uniform Server Cron requires a single block as shown below:
[US_CronS1] startup=C:\UniServer\uni_con\cron\start_cron.bat startup_dir=C:\UniServer\uni_con\cron shutdown=C:\UniServer\uni_con\cron\stop_cron.bat auto_restart=y restart_interval=30 |
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shutdown When the service control manger (SCM) receives a net stop message it runs the script (stop_cron.bat) defined by shutdown.
Script stop_cron.bat runs script stop_cron.vbs which sets cron status to stop in configuration file config_tracker.ini this signals portable Cron to stop. The batch file start_cron.bat then closes informing SCM service has stopped.
z_install.bat
The service utility installs a named service (US_CronS1) using the install command. It uses a configuration "-c" file defined with an absolute path to prevent any ambiguity. Configuration file used is srvstart.ini
rem ### working directory current folder pushd %~dp0 srvstart.exe install US_CronS1 -c C:\UniServer\uni_con\cron_service\srvstart.ini : pause rem ### restore original working directory popd
Note 1: The above installs the service as a manual service. After re-starting your PC you must manually start the service next script changes service state to automatic.
Note 2:
- pushd %~dp0 - Saves current working directory and change working directory to batch file location.
- popd - Restores original working directory
This allows a batch file to be run from any location without worrying about current working directory
Note 3: The pause command is used to pause a batch file. It allows any errors to be seen, waits for a user to press any key. It is used only for testing hence is disabled by commenting it out using a colon ":"
start_automatic.vbs
The service utility installs a service as a manual service this state requires changing to automatic allowing the service script to run when the PC is restarted. The following script starts the service and changes state to automatic.
Set objWMIService = GetObject("winmgmts:\\.\root\cimv2")
Set colRunningServices = objWMIService.ExecQuery ("Select * from Win32_Service")
For Each objService in colRunningServices
If objService.DisplayName = "US_CronS1" Then
'If objService.State = "Running" Then
' MsgBox "Is Running"
'End If
If objService.State= "Stopped" Then
errReturn = objService.StartService() 'Start service
errReturn = objService.Change( , , , , "Automatic") 'Change state
End If
End If
Next
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Create a Windows Management Instrumentation (WMI)object.
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The above script is run after installing a service.
z_service_start.bat
This script is provided for testing. It starts a service that has been installed with a manual status.
rem ### working directory current folder pushd %~dp0 net start US_CronS1 :pause rem ### restore original working directory popd |
The script uses the standard net start command to start a named (US_CronS1) service. |
z_service_stop.bat
This script stops a named service.
rem ### working directory current folder pushd %~dp0 net stop US_CronS1 :pause rem ### restore original working directory popd |
The script uses the standard net stop command to stop a named (US_CronS1) service. |
z_uninstall_service.bat
The service utility uninstalls a named service (US_CronS1) using the uninstall command.
rem ### working directory current folder pushd %~dp0 srvstart.exe remove US_CronS1 :pause rem ### restore original working directory popd |
To use this script service must first be stopped. |
install_start_service.bat
This script combines above scripts (z_install.bat and start_automatic.vbs) into a single script, which is used by Coral’s control interface.
rem ### working directory current folder pushd %~dp0 :Install srvice call z_install.bat :Change to automatic and start service call start_automatic.vbs : pause rem ### restore original working directory popd |
Call Runs and waits for a script to complete before continuing |
stop_uninstall_service.bat
This script combines above scripts (z_service_stop.bat and z_uninstall_service.bat) into a single script, which is used by Coral’s control interface.
rem ### working directory current folder pushd %~dp0 :Stop service call z_service_stop.bat :Uninstall service call z_uninstall_service.bat : pause rem ### restore original working directory popd
Server relocation
Relocating the servers all absolute paths are re-written the following files are changed accordingly:
- srvstart.ini
- z_install.bat
Multi-Servers
Running multi-servers requires unique service names hence these files are changed accordingly:
- srvstart.ini
- z_install.bat
- start_automatic.vbs
- z_service_start.bat
- z_service_stop.bat
- z_uninstall_service.bat
Where to next
CRON - SrvStart utility tutorial