Web Based Job Scheduler

• Download source code - 441 KB

Introduction

There are many ways to schedule a task on a web server. For example, you can use Windows Task Scheduler and SQL Server Agent. This application is unique in that you can:

• schedule jobs using a web browser
• extend the scheduling application to include your own features

Using the Code

This application has three components:

• A Windows Service that will run a job (DOS command text)
• A Web Application that will let you schedule a job
• MS SQL Server database Stored Procedure to get the list of jobs that need to run

Job and schedule information are stored in a MS SQL Server database. The web application lets you create a job with a private or a shared schedule. A shared schedule makes scheduling jobs more manageable. The scheduler supports seven schedule types:

Each schedule type supports a time window with a start and end time.

Below is the Entity Relationship Diagram for the database:

The Windows Service has a timer that fires every minute. The event calls the GetJobsToRun Stored Procedure that lists the jobs that need to run. As each job runs, LastStatus and LastRunTime are updated. Also, the JobHistory table keeps the history of every time a job runs.

Below is the code for the GetJobsToRun Stored Procedure:

CREATE PROCEDURE GetJobsToRun
AS

SELECT    JobId, JobType, JobName, CommandText
FROM    Job
WHERE    JobId in (

SELECT    j.JobId
FROM    Schedule s 
    INNER JOIN Job j ON s.ScheduleId = j.ScheduleId
WHERE    s.ScheduleType = 'Hourly'
    and GetDate() between DATEADD(Hour, s.StartHour, 
        DATEADD(minute, s.StartMin, s.StartDate)) 
        and Coalesce(s.EndDate,'12/12/2078') 
    and (j.LastRunTime is null 
        or DATEDIFF(minute, j.LastRunTime, GetDate()) >= 
        (EveryHour*60) + EveryMinute)

UNION

SELECT    j.JobId
FROM    Schedule s 
    INNER JOIN Job j ON s.ScheduleId = j.ScheduleId
WHERE    s.ScheduleType = 'Daily'
    and GetDate() between s.StartDate and Coalesce(s.EndDate,'12/12/2078') 
    and (j.LastRunTime is null or 
        DATEDIFF(Day, j.LastRunTime, GetDate()) > s.RepeatDays)
    and (s.StartHour*60) + s.StartMin = 
        (DatePart(hour,GetDate())*60) + DatePart(minute,GetDate())

UNION

SELECT    j.JobId
FROM    Schedule s 
    INNER JOIN Job j ON s.ScheduleId = j.ScheduleId
    INNER JOIN ScheduleWeek w ON w.ScheduleId = j.ScheduleId
WHERE    s.ScheduleType = 'Weekly'
    and GetDate() between s.StartDate and Coalesce(s.EndDate,'12/12/2078') 
    and DATEPART (weekday , GetDate()) = w.WeekDayId
    and ((s.StartHour*60) + s.StartMin) <= 
        (DatePart(hour,GetDate())*60) + DatePart(minute,GetDate()) 
    and (j.LastRunTime is null 
        or DATEDIFF(Day, j.LastRunTime, GetDate()) > 0) 

UNION

SELECT    j.JobId
FROM    Schedule s 
    INNER JOIN Job j ON s.ScheduleId = j.ScheduleId
    INNER JOIN ScheduleWeek w ON w.ScheduleId = j.ScheduleId
WHERE    s.ScheduleType = 'WeeklySkip'
    and GetDate() between s.StartDate and Coalesce(s.EndDate,'12/12/2078') 
    and DATEPART (weekday , GetDate()) = w.WeekDayId
    and DATEDIFF(week, j.LastRunTime, GetDate()) >= s.RepeatWeeks 
    and ((s.StartHour*60) + s.StartMin) <= 
        (DatePart(hour,GetDate())*60) + DatePart(minute,GetDate()) 
    and (j.LastRunTime is null 
        or DATEDIFF(Day, j.LastRunTime, GetDate()) > 0) 

UNION

SELECT    j.JobId
FROM    Schedule s 
    INNER JOIN Job j ON s.ScheduleId = j.ScheduleId
    INNER JOIN ScheduleWeek w ON w.ScheduleId = j.ScheduleId
    INNER JOIN ScheduleMonth m ON m.ScheduleId = j.ScheduleId
WHERE    s.ScheduleType = 'WeekNumber'
    and GetDate() between s.StartDate and Coalesce(s.EndDate,'12/12/2078') 
    and w.WeekDayId = DATEPART (weekday , GetDate())
    and m.MonthId = DATEPART (month , GetDate())
    and s.WeekOfMonth = 
        (datepart(ww,GetDate())) + 1 - 
        datepart(ww,dateadd(dd,-(datepart(dd,GetDate())-1),GetDate()))
    and ((s.StartHour*60) + s.StartMin) <= 
        (DatePart(hour,GetDate())*60) + DatePart(minute,GetDate()) 
    and (j.LastRunTime is null 
        or DATEDIFF(Day, j.LastRunTime, GetDate()) > 0)

UNION

SELECT    j.JobId
FROM    Schedule s 
    INNER JOIN Job j ON s.ScheduleId = j.ScheduleId
    INNER JOIN ScheduleMonth m ON m.ScheduleId = j.ScheduleId
    INNER JOIN ScheduleDay d ON d.ScheduleId = j.ScheduleId
WHERE    s.ScheduleType = 'Calendar'
    and GetDate() between s.StartDate and Coalesce(s.EndDate,'12/12/2078') 
    and DATEPART (month , GetDate()) = m.MonthId
    and (DATEPART (day , GetDate()) = d.DayId
        or (d.DayId = 32 and 
        DAY(DATEADD(d, -DAY(DATEADD(m,1,GetDate())),DATEADD(m,1,GetDate()))) 
            = DATEPART(day ,GetDate()))
        )
    and ((s.StartHour*60) + s.StartMin) <= 
        (DatePart(hour,GetDate())*60) + DatePart(minute,GetDate()) 
    and (j.LastRunTime is null or DATEDIFF(Day, j.LastRunTime, GetDate()) > 0) 

UNION

SELECT    j.JobId
FROM    Schedule s 
    INNER JOIN Job j ON s.ScheduleId = j.ScheduleId
WHERE    s.ScheduleType = 'Once'
    and GetDate() between s.StartDate and Coalesce(s.EndDate,'12/12/2078') 
    and ((s.StartHour*60) + s.StartMin) <= 
        (DatePart(hour,GetDate())*60) + DatePart(minute,GetDate()) 
    and (j.LastRunTime is null) -- run once

)

Below is the code for the RunDosCommand function:

Function RunDosCommand(ByVal sCommandText As String, _
    Optional ByVal iTimeOutSec As Integer = 1) As String

    Dim iPos As Integer = sCommandText.IndexOf(" ")
    Dim sFileName As String
    Dim sArguments As String = ""

    If iPos = -1 Then
        sFileName = sCommandText
    Else
        sFileName = sCommandText.Substring(0, iPos)
        sArguments = sCommandText.Substring(iPos + 1)
    End If

    Dim sRet As String
    Dim oProcess As Process = New Process

    oProcess.StartInfo.UseShellExecute = False
    oProcess.StartInfo.RedirectStandardOutput = True
    oProcess.StartInfo.FileName = sFileName
    oProcess.StartInfo.Arguments = sArguments
    oProcess.StartInfo.WindowStyle = ProcessWindowStyle.Hidden
    oProcess.StartInfo.CreateNoWindow = True
    oProcess.Start()

    oProcess.WaitForExit(1000 * iTimeOutSec)
    If Not oProcess.HasExited Then
        oProcess.Kill()
        Return "Timeout"
    End If

    sRet = oProcess.StandardOutput.ReadToEnd()

    If oProcess.ExitCode <> 0 And sRet = "" Then
        sRet = "ExitCode: " & oProcess.ExitCode
    End If

    oProcess.Close()

    Return sRet
End Function

A free third-party calendar component is used from dynarch.com.

Deployment

Here are the steps to deploy this application:

1. Connect to SQL Server and create a database called JobScheduler.
2. Add a user to the database that would have write access.
3. Open the SQL folder. Run ScheduleSchema.sql against your database.
4. Run GetJobsToRun.sql against your database.
5. Copy the WebScheduler folder to C:\Inetpub\wwwroot\ and make it a virtual directory.
6. Double click on the C:\Inetpub\wwwroot\WebScheduler\connect.udl file and point it to the JobScheduler database. Test the connection and click OK.
7. Copy the WinJobService folder to your programs folder.
8. Double click on the <Programs Folder>\WinJobService\connect.udl file and point it to the JobScheduler database. Test the connection and click OK. (You can also copy the file you made in step #6 to this location.)
9. Open the WinJobService (WinJobService\WinJobService.sln) project in Microsoft Visual Studio .NET 2003 and compile it.
10. Register the server by running the Service registration script: WinJobService\bin\Install.vbs. You can uninstall the service later by running Uninstall.vbs.