task/activity precedences/dependencies

Question

i am looking for some .net based library/piece of code to implement task/activity scheduling like microsoft project scheduling in following cases...

1. Finish to Start
2. Finish to Finish
3. Start to Finish
4. Start to Start

please refer to understand in which context i am talking about... About linking tasks @ http://office.microsoft.com/en-us/project-help/link-tasks-within-your-project-HA010364282.aspx?CTT=1

Answer 1

You can write a Windows Service, if you want to make scheduling applications,tasks,activities

Answer 2

You are talking about CPM - Critical Path Method.

Eval each Condition Type (Finish to Start , ....) is a simple Select - Case .

You need eval early Dates then later dates. This determines the Critical Path.

If your algoritm includes ASAP - ALAP for some tasks, you can eval Scheduled Dates aditional pass.

I use Recursive algorhitm for each Pass (Early Dates, Latest Dates ...). This discover Condition Loop and Show them (Task1 -> Task2 -> Task1).

The most compless task for CPM is the calendar management. Nothe that the function

Date1 = Calendar.Eval_DateFinish(Start, Duration)

Becomes a Function based on Resources calendar Intervals.

Here my Function for Ealy Dates.

Private Sub cpm_fmte(ByVal n As Int32)
    Dim a = Actividades(n), fi, f As FechaCpm, ncit As Integer = 0
    fi.value = Integer.MinValue
    Dim cal As Calend = a.Cal, dur As Integer = a.dur
    sw(n) = 255 : RaBucle.Add(a) 'Marco la actividad para detectar bucle condicionantes  

    For Each c In a.Predecesoras   '/* calcular predecesoras */                                
        If c._Act >= nHitos Then
           If c._Act < nTResumen Then Continue For
           Select Case sw(c._Act)
               Case 0 : cpm_fmte(c._Act)
               Case 255 : ShowBucle(c._Act) : Throw New Exception("Cpm_ftme: Error - Bucle Condicionantes")
              'case Else - 1 - Ya calculada anteriormente
           End Select
        End If

        Dim Pred = Actividades(c._Act)
        Select Case c.Tipo
            Case "D"c : f.value = Pred.ffmte.value + c.Demora
            Case "I"c : f.value = Pred.fimte.value + c.Demora : ncit += 1
            Case "T"c : f = cal.Calc_Fi(Pred.ffmte + c.Demora, dur) : ncit += 1
            Case Else : Throw New Exception(String.Format("Error condic.: {0} {1} {2} {3} {4}", _
                              a.Id, c.Tipo, Pred.Id, c.Demora))
        End Select
        If f > fi Then fi = f
    Next
    RaBucle.Count -= 1

    If fi.value = Integer.MinValue Then fi = Proyecto.Actprj.FechaPrj
    If dur > 0 Then fi = cal.Fecha_Jla_Av(fi)
    a.fimte.value = fi.value : a.ffmte = cal.Calc_Ff(fi, dur)
    a.Fip = a.fimte : a.Ffp = a.ffmte
    If a.ffmte.value > Fmax.value Then mfmax.value = a.ffmte.value
    If a.fimte.value < Fmin.value Then mFmin.value = a.fimte.value

    sw(n) = 1 'Actividad calculada
End Sub

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Notes. I'am Spanish then :

• Fmte -> Early Dates (Fechas más Tempranas), Fmta -> Latest Dates, Fp - Schedulded.
• Fi -> Start Date (Fecha Inicio), FF - > Finish Date (Fecha Fín)
• Actividades - Tasks
• "D"c -> (Finish - start), "Después",
• "I"c -> (Start - Start) "Inician..."
• "T"c -> (Finish - Finish) "Terminan ..."
• Never used Start - Finish condition.

I use FechaCpm type (structure) that evals as Int32 type (FechaCpm.Value) and interprets as minute time interval unit.

You can get more code for CPM on SourceForge, but I never find any code on Net. You can see "Open WorkBench" - Java or "Planner" - C++.

My code is CPM based, most Planification programs are resources based supporting CPM. I use only one resource (Human resource) then Calendar is a Task property.