how to determine modification date on element level

[nnako]

Hi,

modification dates can be read from the file system. But the granularity is very low, as it would not be possible to determine when a certain element within the file was actually changed.

BACKGROUND

In some of our projects, people tend to use different sources to modify project management data (some edit the gantt diagram, directly and others update the respective element within a derived list). Although this is “bad practice”, these people can not be stopped from doing so. This leads to an uncertainty concerning the actuality of an element within the GanttProject editor. If GanttProject had a way to track and show the modification date of each single element, conflicts could be solved much easier.

QUESTION

Would it be possible to provide a modification date attribute for each diagram element? In the same way as a task’s id, uid, name, start, … attributes are set behind the scenes? Every time a user changes an element, the modification date (or modification date and time) attribute would have to be updated.

[nnako]

After some months of silence, I am convinced that this functionality does not exist, yet. Is there a way to point me to a portion of code within the code base where I could start thinking about an implementation?

[dbarashev]

@nnako Frankly speaking, I don't quite understand the request.

We can add a modification timestamp to every task, but that timestamp will make sense only if tasks are modified via GanttProject, which is not the case, as far as I understand from your text.

Even if we think that those who edit a project using some other tools will set the timestamps as well, it is not clear what you are going to do with the concurrent edits, when one user updates the project via GanttProject while another updates it using some other tool. Different wall-time timestamps don't mean that those users are aware of each other's edits (there is no happens-before relationship between the edits, speaking in more scientific terms).

Wall time on different computers may be quite different, even when converted to the same time zone, such as UTC, but that's probably not a significant issue.

I also don't understand who is supposed to read the timestamp: is it a human or some program code?

All this said, if you want GanttProject to just write a task modification timestamp in UTC timezone, you need to look at Task interface and TaskImpl implementation, and a family of classes that write and read the data from XML (TaskSaver and TaskLoader)

[nnako]

Hi @dbarashev

I don't quite understand the request.

Let me explain my usecase.

During the last couple of years, I developed a task management application that automatically creates files which can be read in and displayed by your GanttProject task editor application. Within those .gan files, I have collected task representations from various different task management systems like Jira, GitLab, ... even from Excel sheets. A last modification date is stored together with an appropriate "token" at the bottom of each task description attribute. Currently, this created .gan file can be read by GanttProject and serve for project managers to get an overview about projects and dependencies within those projects (that is obviously the original idea of using gantt diagrams). Nothing special, so far.

Now, inside GanttProject, I want to be able to change any of these tasks (i.e. the organizational aspects like due dates, durations, ...) directly or as a result of actions performed within GanttProject (e.g. changing the end date of a connected task might change the start date of another task, as well). As the actual change date is not automatically put into the description attribute of the changed task, I would not be able to evaluate the change in the required way. So, after saving back into the .gan file, I want to identify those changes and possibly re-synchronize them with their original source.

In detail, while analyzing the changes, I want to

• compare the contents of each task element from the .gan file with the respective contents from that other source system
• when detecting changes, I want to use the task's last modification date to identify how and what to synchronize

And, yes, concurrent edit of identical / copied tasks in different systems is a challenge. I was thinking of clear role definitions (project managers might change due dates of all tasks, ... while persons responsible for particular tasks might only change technical content of their own tasks). Or something similar. Sure, time differences on different computers might create further conflicts in case of actual changes induced by the GanttProject user.

What do you think?

Thanks for the pointers.