Planner-list predecessors for fixed date tasks

[pete davidson]

Hi all

Apologies for what's probably a newbie question.

I'm trying to use Planner to manage academic grant applications.  As such, there's a number of key tasks whose dates are externally set and non-negotiable (such as the date the grant must be submitted to the funding agency, or the date a letter of intent is due to the funding agency).  I've been 'locking' these dates by creating a milestone task (eg "Submit grant") with a schedule of 'on fixed date' on the required date. 

The problem I'm having is when I try and link these milestone tasks to the rest of the tasks in the project by setting a predecessor.  This produces the error "You cannot add a relationship to a task with a Must Start On constraint."  I've also tried using a one-day task instead of a milestone task, but get the same error.

Is there another approach to dealing with externally set fixed dates that I'm missing, or a way to set milestone tasks which allows linking to other tasks?

Any suggestions would be most welcome.

Regards

Pete

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[Alexandre Franke]

On Sun, Oct 25, 2009 at 5:42 AM, pete davidson <caitifty@...> wrote:
> Hi all

Hi,

> I'm trying to use Planner to manage academic grant applications.  As such,
> there's a number of key tasks whose dates are externally set and
> non-negotiable (such as the date the grant must be submitted to the funding
> agency, or the date a letter of intent is due to the funding agency).  I've
> been 'locking' these dates by creating a milestone task (eg "Submit grant")
> with a schedule of 'on fixed date' on the required date.
>
> The problem I'm having is when I try and link these milestone tasks to the
> rest of the tasks in the project by setting a predecessor.  This produces
> the error "You cannot add a relationship to a task with a Must Start On
> constraint."  I've also tried using a one-day task instead of a milestone
> task, but get the same error.

The problem here is with the meaning of the predecessor relationship.
If you set A as a predecessor of B, it means that you cannot start
working on B until A is done. So what would happen if you start A on
oct 26th, need 4 days to finish it and set B on oct 28th (fixed date)?
That wouldn't make any sense because you'd need to work on B but you
couldn't since A isn't done yet.

This has nothing to do with the fact that it's a milestone.

> Is there another approach to dealing with externally set fixed dates that
> I'm missing, or a way to set milestone tasks which allows linking to other
> tasks?

You can do it without the predecessor relationship, I think it's the
way that would make the most sense.

--
Alexandre Franke
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[Ricardo Fernandez-2]

Hello Pete,

I'm not sure to understand, but my comment could help.

if you have a "Deadline" task  for a part of your project (including, for exemple, task A)
 - you can set "Deadline" task as a fixed date milestone
 - of course you can't set any predecessor for this fixed date task
 - so you can't set A as predecessor (for example "end to start" link) for "Deadline" task, but...
 - you can set "Deadline" task as predecessor (same example ; "start to end" link) of A

limits for this example :
 - even if A is an "as soon as possible" task, it will be scheduled to "the last moment" before "Deadline". why ? we just wan't it to become a "not after" task.
 - you can't anticipate A setting it to fixed date (today for example). why ?
 - you can't set any other predecessor to A (a current task ending tomorrow, linked "end to start", for example), even if A has been scheduled on next year. why ?

I agree that external constraints are decisive in project scheduling and that Planner constraints rules are too much restrictive.
but it's not an easy problem, and coding realy accurate rules could be an infinite task.

so just try to use such links with parsimony

Regards,
Ricardo FERNANDEZ

---

De :  Alexandre Franke alexandre.franke@...

Envoyé :  25/10/2009 13:14:00 +0100

À :  planner planner-list@...

Objet :  Planner-list predecessors for fixed date tasks

On Sun, Oct 25, 2009 at 5:42 AM, pete davidson caitifty@... wrote:
  

Hi all
    

Hi,

  

I'm trying to use Planner to manage academic grant applications.  As such,
there's a number of key tasks whose dates are externally set and
non-negotiable (such as the date the grant must be submitted to the funding
agency, or the date a letter of intent is due to the funding agency).  I've
been 'locking' these dates by creating a milestone task (eg "Submit grant")
with a schedule of 'on fixed date' on the required date.

The problem I'm having is when I try and link these milestone tasks to the
rest of the tasks in the project by setting a predecessor.  This produces
the error "You cannot add a relationship to a task with a Must Start On
constraint."  I've also tried using a one-day task instead of a milestone
task, but get the same error.
    

The problem here is with the meaning of the predecessor relationship.
If you set A as a predecessor of B, it means that you cannot start
working on B until A is done. So what would happen if you start A on
oct 26th, need 4 days to finish it and set B on oct 28th (fixed date)?
That wouldn't make any sense because you'd need to work on B but you
couldn't since A isn't done yet.

This has nothing to do with the fact that it's a milestone.

  

Is there another approach to dealing with externally set fixed dates that
I'm missing, or a way to set milestone tasks which allows linking to other
tasks?
    

You can do it without the predecessor relationship, I think it's the
way that would make the most sense.

  

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Planner-list mailing list
Planner-list@...
http://mail.gnome.org/mailman/listinfo/planner-list

[Kurt Maute]

On Wed, 2009-10-28 at 23:08 +0100, Ricardo Fernandez wrote:

> Hello Pete,
>
> I'm not sure to understand, but my comment could help.
>
> if you have a "Deadline" task  for a part of your project (including,
> for exemple, task A)
>  - you can set "Deadline" task as a fixed date milestone
>  - of course you can't set any predecessor for this fixed date task
>  - so you can't set A as predecessor (for example "end to start" link)
> for "Deadline" task, but...
>  - you can set "Deadline" task as predecessor (same example ; "start
> to end" link) of A
>

Correct.  The way to set up this relationship is to edit your task A and
set up the deadline as a predecessor with a 'SF' relationship.  Task A
will then be scheduled so that it ends just prior to the deadline task.

> limits for this example :
>  - even if A is an "as soon as possible" task, it will be scheduled to
> "the last moment" before "Deadline". why ? we just wan't it to become
> a "not after" task.

ASAP just means that the task start date will float based on predecessor
relationships.  Planner schedules all tasks (without assigned resources)
assuming that a single resource will work at 100% capacity for the
duration, and sets the start and end dates accordingly.  If you want to
change the start date on a task with a 'SF' relationship, you should
assign a resource and adjust the resource units to something less than
100%.

>  - you can't anticipate A setting it to fixed date (today for
> example). why ?

see above

>  - you can't set any other predecessor to A (a current task ending
> tomorrow, linked "end to start", for example), even if A has been
> scheduled on next year. why ?
>
Well, if you've set the finish date for task A with a SF or FF
relationship, then we need to let the start date float in order for the
scheduling algorithm to work.

If you created a task B, you could set task A as a predecessor with a SF
or FF relationship.  In this way, you're essentially scheduling from the
deadline back to the present day.

> I agree that external constraints are decisive in project scheduling
> and that Planner constraints rules are too much restrictive.
> but it's not an easy problem, and coding realy accurate rules could be
> an infinite task.
>
> so just try to use such links with parsimony
>
> Regards,
> Ricardo FERNANDEZ
>
>
>
> ______________________________________________________________________
> De :  Alexandre Franke <alexandre.franke@...>
> Envoyé :  25/10/2009 13:14:00 +0100
> À :  planner <planner-list@...>
> Objet :  Planner-list predecessors for fixed date tasks
>
> > On Sun, Oct 25, 2009 at 5:42 AM, pete davidson <caitifty@...> wrote:
> >  
> > > Hi all
> > >    
> >
> > Hi,
> >
> >  
> > > I'm trying to use Planner to manage academic grant applications.  As such,
> > > there's a number of key tasks whose dates are externally set and
> > > non-negotiable (such as the date the grant must be submitted to the funding
> > > agency, or the date a letter of intent is due to the funding agency).  I've
> > > been 'locking' these dates by creating a milestone task (eg "Submit grant")
> > > with a schedule of 'on fixed date' on the required date.
> > >
> > > The problem I'm having is when I try and link these milestone tasks to the
> > > rest of the tasks in the project by setting a predecessor.  This produces
> > > the error "You cannot add a relationship to a task with a Must Start On
> > > constraint."  I've also tried using a one-day task instead of a milestone
> > > task, but get the same error.
> > >    
> >
> > The problem here is with the meaning of the predecessor relationship.
> > If you set A as a predecessor of B, it means that you cannot start
> > working on B until A is done. So what would happen if you start A on
> > oct 26th, need 4 days to finish it and set B on oct 28th (fixed date)?
> > That wouldn't make any sense because you'd need to work on B but you
> > couldn't since A isn't done yet.
> >
> > This has nothing to do with the fact that it's a milestone.
> >
> >  
> > > Is there another approach to dealing with externally set fixed dates that
> > > I'm missing, or a way to set milestone tasks which allows linking to other
> > > tasks?
> > >    
> >
> > You can do it without the predecessor relationship, I think it's the
> > way that would make the most sense.
> >
> >  
> _______________________________________________
> Planner-list mailing list
> Planner-list@...
> http://mail.gnome.org/mailman/listinfo/planner-list

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[Ricardo Fernandez-2]

Hello Kurt,

If you want to change the start date on a task with a 'SF' relationship, you should assign a resource and adjust the resource units to something less than 100%.

problem : using resources this way turns it to nothing more than an abstract parameter.

Well, if you've set the finish date for task A with a SF or FF relationship, then we need to let the start date float

That's precisely the question : the finish date for task A is then set and fixed. both start date and finish date for task A sould be floating
two rules can be imagined to define SF links :
 - end(A) < start(Deadline) ; that's the minimal constraint and so the more usefull (and generally the actual logical link).
 - end(A) = start(Deadline) ; that's the maximal constraint for an SF link, and the Planner's one. generally too restrictive.

the less restrictive is a tool, the more useful it is... and the more complex is the algorithm.


is there any way to centralize a collective analyze and specification for algorithm evolution ?
is there any conceptual documentation (exept code and its comments) for link rules and sheduling algorithm ?
I have no time (like everyone) but should be interessed (probably like some others) to contribute to a conceptual specification

Planner is no far away from being an excelent simple and intuitive tool but, to be honest, I'm not acheaving to use it efficiently at this time

Regards,
Ricardo FERNANDEZ

---

De :  Kurt Maute kurt@...

Envoyé :  29/10/2009 14:35:30 +0100

À :  Ricardo Fernandez ricardo.fernandez@...

Copie :  pete davidson caitifty@..., planner planner-list@...

Objet :  Planner-list predecessors for fixed date tasks

On Wed, 2009-10-28 at 23:08 +0100, Ricardo Fernandez wrote:
  

Hello Pete,

I'm not sure to understand, but my comment could help.

if you have a "Deadline" task  for a part of your project (including,
for exemple, task A)
 - you can set "Deadline" task as a fixed date milestone
 - of course you can't set any predecessor for this fixed date task
 - so you can't set A as predecessor (for example "end to start" link)
for "Deadline" task, but...
 - you can set "Deadline" task as predecessor (same example ; "start
to end" link) of A

    

Correct.  The way to set up this relationship is to edit your task A and
set up the deadline as a predecessor with a 'SF' relationship.  Task A
will then be scheduled so that it ends just prior to the deadline task.

  

limits for this example :
 - even if A is an "as soon as possible" task, it will be scheduled to
"the last moment" before "Deadline". why ? we just wan't it to become
a "not after" task.
    

ASAP just means that the task start date will float based on predecessor
relationships.  Planner schedules all tasks (without assigned resources)
assuming that a single resource will work at 100% capacity for the
duration, and sets the start and end dates accordingly.  If you want to
change the start date on a task with a 'SF' relationship, you should
assign a resource and adjust the resource units to something less than
100%.

  

 - you can't anticipate A setting it to fixed date (today for
example). why ?
    

see above

  

 - you can't set any other predecessor to A (a current task ending
tomorrow, linked "end to start", for example), even if A has been
scheduled on next year. why ?

    

Well, if you've set the finish date for task A with a SF or FF
relationship, then we need to let the start date float in order for the
scheduling algorithm to work.

If you created a task B, you could set task A as a predecessor with a SF
or FF relationship.  In this way, you're essentially scheduling from the
deadline back to the present day.

  

I agree that external constraints are decisive in project scheduling
and that Planner constraints rules are too much restrictive.
but it's not an easy problem, and coding realy accurate rules could be
an infinite task.

so just try to use such links with parsimony 

Regards,
Ricardo FERNANDEZ



______________________________________________________________________
De :  Alexandre Franke alexandre.franke@...
Envoyé :  25/10/2009 13:14:00 +0100
À :  planner planner-list@...
Objet :  Planner-list predecessors for fixed date tasks

    

On Sun, Oct 25, 2009 at 5:42 AM, pete davidson caitifty@... wrote:
  
      

Hi all
    
        

Hi,

  
      

I'm trying to use Planner to manage academic grant applications.  As such,
there's a number of key tasks whose dates are externally set and
non-negotiable (such as the date the grant must be submitted to the funding
agency, or the date a letter of intent is due to the funding agency).  I've
been 'locking' these dates by creating a milestone task (eg "Submit grant")
with a schedule of 'on fixed date' on the required date.

The problem I'm having is when I try and link these milestone tasks to the
rest of the tasks in the project by setting a predecessor.  This produces
the error "You cannot add a relationship to a task with a Must Start On
constraint."  I've also tried using a one-day task instead of a milestone
task, but get the same error.
    
        

The problem here is with the meaning of the predecessor relationship.
If you set A as a predecessor of B, it means that you cannot start
working on B until A is done. So what would happen if you start A on
oct 26th, need 4 days to finish it and set B on oct 28th (fixed date)?
That wouldn't make any sense because you'd need to work on B but you
couldn't since A isn't done yet.

This has nothing to do with the fact that it's a milestone.

  
      

Is there another approach to dealing with externally set fixed dates that
I'm missing, or a way to set milestone tasks which allows linking to other
tasks?
    
        

You can do it without the predecessor relationship, I think it's the
way that would make the most sense.

  
      

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Planner-list mailing list
Planner-list@...
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[Maurice van der Pot-2]

On Fri, Oct 30, 2009 at 01:14:35AM +0100, Ricardo Fernandez wrote:
> is there any way to centralize a collective analyze and specification
> for algorithm evolution ?
> is there any conceptual documentation (exept code and its comments) for
> link rules and sheduling algorithm ?
> I have no time (like everyone) but should be interessed (probably like
> some others) to contribute to a conceptual specification

The problem is not in coming up with an idea for scheduling, it is in
finding someone who is willing to work on it and stick with it.

When thinking about how scheduling should work it quickly pulls in many
many other things that ideal scheduling functionality requires, such as
split tasks. The bigger the ideas and requirements get, the more
motivation you need to actually take on the problem of implementation.

Additionally it is harder to motivate someone to implement other
people's requirements than it is to get them to implement their own.

In my opinion discussing requirements like this will go nowhere unless
the one starting the discussion is the one who plans to implement it.
Look through bugzilla for this feature, you'll see what I mean.

Regards,
Maurice.

--
Maurice van der Pot

Gentoo Linux Developer   griffon26@...    http://www.gentoo.org
Gnome Planner Developer  griffon26@...  http://live.gnome.org/Planner



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[Ricardo Fernandez-2]

---

De :  Maurice van der Pot griffon26@...

Envoyé :  30/10/2009 18:11:50 +0100

À :  planner-list@...

Objet :  Planner-list predecessors for fixed date tasks

On Fri, Oct 30, 2009 at 01:14:35AM +0100, Ricardo Fernandez wrote:
  

is there any way to centralize a collective analyze and specification 
for algorithm evolution ?
is there any conceptual documentation (exept code and its comments) for 
link rules and sheduling algorithm ?
I have no time (like everyone) but should be interessed (probably like 
some others) to contribute to a conceptual specification
    

The problem is not in coming up with an idea for scheduling, it is in
finding someone who is willing to work on it and stick with it.

When thinking about how scheduling should work it quickly pulls in many
many other things that ideal scheduling functionality requires, such as
split tasks.

I totally agree ; remember my sentense just before your extract :
" the less restrictive is a tool, the more useful it is... and the more complex is the algorithm."
and spliting tasks (for example) was to my mind an absolute necessity for schedulling taking ressources in account.

The bigger the ideas and requirements get, the more
motivation you need to actually take on the problem of implementation.
  

ok for 'big ideas'.
concerning requirements and precise specifications, instead, I thought it could help implementation as well as motivation.

Additionally it is harder to motivate someone to implement other
people's requirements than it is to get them to implement their own.

In my opinion discussing requirements like this will go nowhere unless
the one starting the discussion is the one who plans to implement it.
Look through bugzilla for this feature, you'll see what I mean.
  

that's done !
and that's precisely why I suggested another way of work.

in conclusion, I fear that those who hope Planner can become the accurate tool they need, there are two options :
 - discussion list ; a waste of time
 - waiting for developpers to find time and motivation...

Regards
Ricardo FERNANDEZ

Regards,
Maurice.

  

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