piątek, 30 stycznia 2015

Practical Scrum Training (6) Discussion of Product Backlog (continued)

Let's consider the product backlog item related to the editing of data. Just this one more and then we'll jump straight into ordering the product backlog.

In order to correct the information about a person in the family tree as a family tree user, I want to be able to edit the data of a person I choose.

I didn't like this item from the start, because it seemed to me rather complicated to develop. When I think about it now, it doesn't seem that complicated. But for the purpose of training, I need to ask a question: can we do anything smaller, break it into smaller parts or do any other trick to achieve something similar quicker than if we were to develop it as is.

As always, there is something we can do. The aim here is correct data. If we add a new item that introduces deletion of people from the tree, it will be possible to delete a person with incorrect data and then add same person again, this time with good data. Maybe a little awkward to the user, but if we desperately wanted to deliver the "correction" functionality quickly, then maybe we could get away with this approach and deliver real editing functionality one iteration later.

But there's a catch: if we delete a person and add them again, then the "new" person will have a new, unique identifier and the identifier of the deleted person may be spread in several other records (children).

It may be a good point for the training to suggest the deceitful solution with deletions and see when the trainees are able to spot this problem. At planning? Maybe during the development? Maybe someone writing a test for it will be able to spot it quickest?

After thinking about all of this, I conclude that deletions are important (but are not good substitutes for editions) and they deserve to be a product backlog item on their own.

This is how I would order the product backlog item now:

  • In order to correct the information about a person in the family tree as a family tree user, I want to be able to edit the data of a person I choose
  • In order to make corrections in the family tree as a family tree user, I want to be able to delete a person from the tree
  • In order to add new people to the family tree efficienty as a family tree user, I want to be asked if I want to add another person right after I added the last one
  • In order for the family tree to be easier to read as a family tree user, I want the graphical representation of the tree to alternately use one of two different colors for each generation
  • In order for the family tree to be easier to read as a family tree user, I want the graphical representation of the tree to rotate colors of generations from a predefined set of colors
  • In order to maintain integrity of family tree data as a family tree user, I want the identifiers of the parents checked (natural numbers, identifiers are optional) and blocked from being entered if invalid
  • In order to maintain integrity of family tree data as a family tree user, I want the identifiers of the parents checked to be existing identifiers of people already existing in the tree and blocked from being entered if that is not the case
  • In order to disallow non-logical connections in the family tree as a family tree user, I want to be blocked from pointing a person as their own parent
  • In order to disallow non-logical connections in the family tree as a family tree user, I want to be blocked from pointing the same person as both mother and father of someone
  • In order to distinguish the gender of a person in the family tree as a family tree user, I want to be able to assign gender attribute to each person
  • In order to maintain the data about births and deaths in the family as a family tree user, I want to be able to assign birth and death dates to each person
Is this the only good order possible? Of course not. This is only how I see it and I did not consult this with anybody (customer, potential user). Also, once the items are estimated, the order of development may slightly change when the development team estimates what can be done in each iteration.

That's it. The next post will outline how I imagine the training should be conducted.

środa, 28 stycznia 2015

Practical Scrum Training (5) Discussion of Product Backlog (continued)

As promised in the previous post, we are going to discuss the product backlog item:
In order to secure integrity of family tree data as a family tree user, I want to have checks for all data I enter so that entering invalid data is not possible
Is this an easy one, or rather difficult and big? Maybe it's not super-difficult, but it is a large one, probably in the top three biggest items that we currently have in product backlog. How can we break it down?

First of all, let's realize which data needs to be checked. When adding a new person to the tree, we enter:
  • name and surname - these probably do not require any checks
  • mother and father IDs - definitely needs checking
Now, depending on the order of the product backlog, we may or may not have additional attributes that need checking. If we deliver an increment with birth and death dates and gender attributes available for the user before we deliver this item, then this will open a whole new set of checks and the item will be even larger. On the other hand, if we deliver this item first, then we will probably need to think of checks while doing the gender item or any other product backlog item that has to do with person attributes. Doing checks will then be an integral part of the items ordered later or it will be covered by a separate backlog item, to make product backlog items smaller. In this context, think about the product backlog item that adds the ability to edit person's data.

Let's leave the order of product backlog items aside for a while and consider the checking of the IDs of the parents. We could say: that must be a number - and just check if that's a number. This would be purely syntactical checking. But we could go further and check if an ID entered actually exists somewhere in the tree (that is, is a valid ID of a parent). We could even check if a person is ever added / editted as their own parent and disallow this situation. Or wait - we could also check that the IDs of the parents are not equal to each other, which would mean someone is trying to set the same person as mother and father. And all these possibilities are good cases to consider for checks, even assuming that we do not have gender attribute developed yet.

There is also one extra hint that I can give you: did you notice that this item contains the word all?
In order to secure integrity of family tree data as a family tree user, I want to have checks for all data I enter so that entering invalid data is not possible.

Beware of this word in any product backlog item you see. That means it is too general and it tries to embrace too many known and unknown things.

Product backlog items that use universal quantifiers (like "in all cases", "for every possible configuration", etc.) act like magnets and they attract newly identified scope, making the item difficult for the team to finish within a sprint. 

Even with the assumption that we have not developed anything prior to this product backlog item (no dates, gender, etc.), we could divide this item into several smaller ones:

In order to secure integrity of family tree data as a family tree user, I want to have checks for all data I enter so that entering invalid data is not possible.
can be refined into:
  • In order to maintain integrity of family tree data as a family tree user, I want the identifiers of the parents checked (natural numbers, identifiers are optional) and blocked from being entered if invalid
  • In order to maintain integrity of family tree data as a family tree user, I want the identifiers of the parents checked to be existing identifiers of people already existing in the tree and blocked from being entered if that is not the case
  • In order to disallow non-logical connections in the family tree as a family tree user, I want to be blocked from pointing a person as their own parent
  • In order to disallow non-logical connections in the family tree as a family tree user, I want to be blocked from pointing the same person as both mother and father of someone
Isn't that nice?

poniedziałek, 26 stycznia 2015

Practical Scrum Training (4) Discussion of Product Backlog

This post is a base for a discussion that could be held with a group of developers, facilitated by a trainer.

Let's look at our Product Backlog again and color the items that seem clear and straightforward green and those that require further discussion blue.
  • In order to add new people to the family tree efficienty as a family tree user, I want to be asked if I want to add another person right after I added the last one
  • In order for the family tree to be easier to read as a family tree user, I want the graphical representation of the tree to present each generation in a different color
  • In order to secure integrity of family tree data as a family tree user, I want to have checks for all data I enter so that entering invalid data is not possible
  • In order to correct the information about a person in the family tree as a family tree user, I want to be able to edit the data of a person I choose
  • In order to distinguish the gender of a person in the family tree as a family tree user, I want to be able to assign gender attribute to each person
  • In order to maintain the data about births and deaths in the family as a family tree user, I want to be able to assign birth and death dates to each person
This coloring does not mean that all the green items are absolutely clear about the details, for example, the last item does not say if birth date should be mandatory. Maybe yes, maybe no. Maybe the customer wants this to be mandatory and we will need to persuade them that optional is a better option for birth dates. That is all OK - it is not the point that all such details are known straight from item title. It is just first "C" in 3C: "Card, Conversation, Confirmation".

Let's talk about the second item from the list - tree coloring. Why is it blue? The basic idea is easy to get. The concept of what a generation is clear. Even if we do not have the algorithm to distinguish between generations, we would be able to manually color even a complex tree, were it printed on paper. I think the only thing that needs to be clarified is how many colors will do. Saying just "each in a different color" may be difficult or impossible to meet for very large trees. But maybe our program will never be used for trees larger than 4 or 5 generations. Or wait, maybe that's not good assumption. So if we may have a user that wants to maintain 12 generations, do we need 12 different colors? Will the user actually be able to distinguish between them then? Or maybe it will be all good if we just have 5 colors and use them one by one to color consecutive generations and simply switch from 5th to 1st color when we still have something to color? Yes, this last idea seems just fine, we may agree later if that's 5 or something else.

That much for clarification, but is there possibility to break this item into a couple of smaller ones? No, it is what it is, either we do coloring or not. Would it be easier though, if we started from just two colors? Well, yes, it could make things a little bit easier. If we were to use just two colors we could just say that whatever the color of parent nodes is, the color of all their children should be the other one. I think this would result in proper coloring of generations (that is, alternating between two colors) for any family tree. So, even for such seemingly undivisable product backlog item, we were able to break it into two that we can order one after another:
  • In order for the family tree to be easier to read as a family tree user, I want the graphical representation of the tree to alternately use one of two different colors for each generation
  • In order for the family tree to be easier to read as a family tree user, I want the graphical representation of the tree to rotate colors of generations from a predefined set of colors
In next post, we'll discuss the product backlog item that says about data checks.

niedziela, 25 stycznia 2015

Practical Scrum Training (3) Product Backlog

This post features the product backlog that will be used for the remaining parts of the training. It is deliberately not ordered and some of the items are written such that they can be good candidates for Product Backlog Refinement.
  • In order to add new people to the family tree efficienty as a family tree user, I want to be asked if I want to add another person right after I added the last one
  • In order for the family tree to be easier to read as a family tree user, I want the graphical representation of the tree to present each generation in a different color
  • In order to secure integrity of family tree data as a family tree user, I want to have checks for all data I enter so that entering invalid data is not possible
  • In order to correct the information about a person in the family tree as a family tree user, I want to be able to edit the data of a person I choose
  • In order to distinguish the gender of a person in the family tree as a family tree user, I want to be able to assign gender attribute to each person
  • In order to maintain the data about births and deaths in the family as a family tree user, I want to be able to assign birth and death dates to each person
Sit comfortably and think for a while about this Product Backlog. What would be the best order of the items, in your opinion? Do you see items that need refinement or spark questions about the details?

In next posts I will try to answer these questions as I see it.

piątek, 23 stycznia 2015

Practical Scrum Training (2) Basic functionality is ready

I completed what can be called a basic version of our family tree application. This is what the user can do with it:
  • add new people to the tree
  • print the tree in text mode
  • save the tree as png file
The program works from command line and can be started by typing:

$ python main.py

Prerequisities: there must be pydot and graphviz installed on the system to run the program.

The files:
The program has some shortcomings, for example it requires one to put the IDs of parents while adding a child, but in general it works fine. It can create a png picture like this one below.


This version is the baseline for the trainees to start. The backlog from which to work on extending the application will be published in next post.


sobota, 10 stycznia 2015

Practical Scrum Training (1) Outline of the application

Next several posts will be devoted to the Practical Scrum Training I decided to develop. The basic idea for the application that will serve as an example will be this:

A desktop application capable of maintaining and presenting a family tree. The basic version of it (that students will be provided with at the start of the training) will most likely allowed just for:
  • entering individuals and defining their relationships
  • presenting data (I'm not sure how, at the moment)
  • persistently storing the data so that it can be loaded at next start of the application
That's most likely all it will do. It will not be written with great care to the craftsmanship and that will be on purpose - it should be like any of these applications that you start working on when it has already been developed to some extent and your job is to extend it rather than develop it from scratch.

sobota, 3 stycznia 2015

Practical Scrum training for Developers - a proposal - your feedback is welcome!

I have an idea of developing a practical Scrum training targeted at Developers that would use hands-on programming examples.

Most of Scrum games that I know of or experienced are metaphores, like building objects with Lego blocks, not real software development. I'm not saying these examples are bad, but there is definitely something lacking in terms of what Developers may practise at a training session.

My objectives for the training are:
  • develop an application and a rough product backlog that could be then refined and implemented during the training session
  • focus on breaking large user stories into smaller and smaller ones
  • incorporate TDD as an XP practice
The training would be done using Python.

Now, I need your feedback: do you think you would sign-up for such a training, if I had one ready? Would you want me to run this training for you? Do you also think that's something that is missing from regular Scrum training offer?

Please use comments or contact me directly with the feedback.