Introduction
This example configures a job chain with jobs that use a special monitor to read parameters from job chain parameter files. The parameters in these files can reference other (global) parameters.
Downloads
- configuration.zip - configuration files
Instructions
- Unzip all files into the
./config
folder of your JobScheduler installation. Open
config/scheduler.xml
and add the following lines right before the<security>
element:<params> <param name="global_configuration_params" value="config/scheduler_global_vars.xml"/> </params>
- Restart the JobScheduler
- Open the JobScheduler Operating Center, JOC, in your browser using http://scheduler_host:scheduler_port
- Open the JOB CHAINS tab and enable "Show orders".
- Find the job chain
samples/configuration/chain_a
. - Find the order
my_order
, open the order menu and choose "Show log".
A window will open showing the log of the order. As the order isn't running yet, the window will show nothing more than information about the configuration file, the next start time of this order and its initial state. Leave the window open and move it to a place where you can see it along with the main browser window.
- Start the order by choosing "Start order now" from the Order menu.
- Watch the log grow in the other window
The order will run through both steps of the job chain. In each step the order parameters will be logged by the job. The parameters param1 - param4 should be shown in the log with the following values:
State:first param1=10 param2=abc param3=foo param4=abc---def
and
State:second param1=10 param2=xyz param4=xyz---def
Nothing special so far. The next section explains how these resulting parameters were configured.
How it works
The job chain chain_a
is very simple. It consists of two steps, "first" and "second". Both steps use the same job readparam
. The readparam
job is a small JavaScript job which reads all order parameters and logs them on info
-level.
The Java monitor implementation
The sos.scheduler.managed.configuration.ConfigurationOrderMonitor
is configured as a monitor for the job. This is a special pre/post-execution script which is included in the JobScheduler distribution. It can be used for all jobs.
In the JobScheduler Object Editor, JOE, the monitor implementation is called under JobScheduler Objects.Jobs.Jobname.Pre-/Post-Processing as a Java configuration_monitor. The monitor reads special job chain parameter files which set parameters for a job chain and are able to configure each node of a job chain individually. These parameter files are named by default according to the pattern myJobChain.config.xml
.
The following screen-shot shows the job chain node parameters for the example:
Note:
This flexible use of parameters cannot be achieved using normal order parameters. It could be achieved by using job parameters, but if the same job is used at multiple steps in a job chain or in different job chains you would have to define multiple instances of that job, although it is the same job implementation.
(For example, if a job chain consists of three steps:
- 1.transfer file by FTP to host a,
- 2.transfer file by FTP to host b,
- 3.delete file.
You could use the same job for steps 1 and two, but you would need different parameters.) So, in this example we use the same job twice, but as you have seen from the log, with different parameters.
The example in detail:
When using hot folders, the configuration monitor looks for the job chain parameter file in the current hot folder and expects the name job_chain_name.config.xml. So in this case, the name of the job chain parameter file is chain_a.config.xml
.
chain_a.config.xml
has three <params>
elements:
- The first one is a child of the
<order>
element. It configures parameters for all steps of the job chain. That's why the log showsparam1
as10
in both steps. - The second
<params>
element is a child of<process state="first">
. It configures parameters for the first node (called "first") of the job chain. It sets two additional parametersparam3
andparam4
.param4
uses a special${paramname}
-syntax to reference other parameters. It referencesparam2
which was set in the first params element. As you see in the log, this part is later resolved toabc
. - The third is the
global_test_var
parameter that is a variable defined inconfig/scheduler_global_vars.xml
.
By configuring the global scheduler variableglobal_configuration_params
inscheduler.xml
to point to that file (scheduler_global_vars.xml
), we tell the configuration monitor to always read that file and process it's parameters. Inconfig/scheduler_global_vars.xml
the value forglobal_test_var
is set todef
, so the reference inparam4
is resolved to that value.
Note that:
- The second
<params>
element is a child of<process state="second">
. It configures parameters for the second node (called "second") of the job chain. It overwrites theparam2
parameter and sets it toxyz
.param3
is not set at all, thus it doesn't appear in the log for statesecond
. param4
is defined in the same way as in statefirst
, but this time the resulting value is different becauseparam2
has been overwritten for this state.
In job chain parameter files the ${paramname}
-syntax can be used to reference
- order parameters
- order parameters defined in the job chain parameter file
- global scheduler variables
- environment variables
Further References
Job Chain and Job Chain Node Parameters
- How to define and reference Job Chain Node parameters
- How to define job chain node parameters for orders
- How to dynamically use node parameters and internal parameter substitution