DMSContainer Documentation > Getting Started > Fundamentals Concepts > Working with class jobs

Working with class jobs

How to create a new Class JOB

In this section we are going to create a simple beeper JOB, then we’ll add a JSON-RPC interface and will test it with a python script.

Creating the JOB class

Create a new Delphi Package

New Delphi Package

Using the dcp files available in the <DMS_HOME>\SDK folder, add the following DCPs among the Requires packages section:
- dmsRT
- dmvcframeworkRT.dcp
- loggerproRT.dcp
- LockBoxDR
Open the project options and set the Package Output Directory to point to the folder jobspackage of your DMSContainer instance.

Project Options

Save the package as dms_job_beeper.dproj add a new unit called Jobs.Beeper.Job.pas.

Write the following code into the unit Jobs.Beeper.Job.pas

unit Jobs.Beeper.Job;

interface

uses DMSCommonsU, DMSCustomJob, DMSLoggingU;

type
    TBeepJob = class(TCustomJob)
    protected
        procedure DoExecute; override;
    end;

implementation

uses
    WinApi.Windows, System.SysUtils;

{ TBeepJob }

procedure TBeepJob.DoExecute;
begin
    Log.Info('Hello! I''m going to play something amazing!!', JobName);
    WinApi.Windows.Beep(440, 80);
end;

initialization

Randomize;
    TBeepJob.ClassName;

end.

Build the package and check that the file dms_job_beeper.bpl is present into the folder <DMS_HOME>\jobspackage

NOTE: At the startup DMSContainer loads all the packages inside the folder <DMS_HOME>\jobspackage whom name starts with dms_job_. Using a different name, the package will not be loaded.

Open the <DMS_HOME>\conf\jobsmanager.json file and add a new JSON object, as the last of the jobs array, to configure the new beeper job.

Now, your jobsmanager.json file should looks like the following

{
"jobs":[
    {
        "enabled": true,
        "jobname": "email",
        "schedule": "* * * * * *", 
        "jobtype":"class", 
        "jobclass":"Jobs.Email.Job.TJobEmail",
        "rpcclass":"Jobs.Email.RPC.TEmailRPC",
        "rpcuri":"/emailrpc"
    },
# other jobs here...	
    {
        "enabled": true,
        "jobname": "beeper",
        "schedule": "* * * * * *", 
        "jobtype":"class", 
        "jobclass":"Jobs.Beeper.Job.TBeepJob"
    }
]
}

Save the file and re/start your DMSContainer instance using the RUN_DEBUG.BAT batch file.
If the instance is running as console, you should ear a beep every minute. Moreover in the logs folder your should see a new log file named dms_00.beeper.log
Congratulations! Your first DMSContainer job is running!

If DMSContainer doesn’t start, check the main log file names dms_00.main.log

However, working without a debugger is not a viable solution nowadays, so let’s configure the Delphi IDE to help in the development of DMSContainer Jobs.

Configuring Delphi debugger

If while working with small package a debugger can be a nice addition but not a requirement, if the packages you are working on gets bigger, you definitively need a debugger. The Delphi debugger is one of the best on the market, so using DMSContainer you can use it and enjoy a pleasant development experience.

Follow these steps to instruct DMSContainer and Delphi to work nicely together.

Stop the DMSContainer service if running.
Open the Delphi IDE and open the dms_job_beeper.dproj project in the IDE.
Go to menu Project->Options and in the opening window, select the node Debugger.
In the field Host Application write the full path of the DMSContainerService.exe executable (default is <DMS_HOME>\DMSContainerService.exe).
In the field Parameters write /console.
Now, select the node Debugger->Environment Block and add the following variable in the box “User System Override”:
- Variable DMS_HOME with value C:\bitTimeProfessionals\DMSContainer_3_1_0 (or the folder where you decided to install DMSContainer).
Confirm your changes hitting “OK”
Run your project.
In this case, DMSContainer runs in debug mode (because of the switch `/console) so a console is showed and you can easily put your breakpoints in the BPL code as usual.
When you want to release the BPL containing your ClassJob, just run the DMSContainerService as usual from the Windows Service Console.

WARNING: If for some reason you want to run DMSContainer as console also outside the Delphi IDE, you can still use the /console switch opening a command prompt and issuing the following commands (remember to stop the DMSContainerService.exe from the Windows Services).

set DMS_HOME=C:\bitTimeProfessionals\DMSContainer_3_1_0
DMSContainerService.exe /console

If it works for you, you can also use the RUN_DEBUG.BAT file to run DMSContainer as console application in debug mode.

Adding a JSON-RPC interface to the beeper job

In this section we’ll add a JSON-RPC interface to the beeper job.

Stop the DMSContainer instance
Open the project dms_job_beeper.dproj (or create a new package following the instructions of the previous paragraphs)

Add a new unit called Jobs.Calculator.RPC.pas. The following code is a a simple, but working, RPC class which can be remotely accessed through the JSON-RPC interface

unit Jobs.Calculator.RPC;

interface

uses
    DMSCustomRPC;

type
    TCalculatorRPC = class(TCustomRPC)
    public
        function Sum(const A, B: Integer): Integer;
    end;

implementation

{ TCalculatorRPC }

function TCalculatorRPC.Sum(const A, B: Integer): Integer;
begin
    Result := A + B;
end;

end.

Build the package and check that the file dms_job_beeper.bpl is present into the folder <DMS_HOME>\jobpackages
Open the jobsmanager.json file and add a new JSON object to configure our new job.

Your jobsmanager.json file should looks like the following

{
"jobs":[
    {
        "enabled": true,
        "jobname": "email",
        "schedule": "* * * * * *", 
        "jobtype":"class", 
        "jobclass":"Jobs.Email.Job.TJobEmail",
        "rpcclass":"Jobs.Email.RPC.TEmailRPC",
        "rpcuri":"/emailrpc"
    },
    {
        "enabled": true,
        "jobname": "beeper",
        "schedule": "* * * * * *", 
        "jobtype":"class", 
        "jobclass":"Jobs.Beeper.Job.TBeepJob",
        "rpcclass":"Jobs.Calculator.RPC.TCalculatorRPC",
        "rpcuri":"/beeperrpc"
    }
]
}

Re/Start your DMSContainer instance.
Congratulations! Your first DMSContainer job with an RPC interface is running!

Now you first Class Job is up and running.. it’s time to test it!