Mythical Man-Month Analysis

--Originally published at That Class Blog

Well. What I’ve learned from this book, in fact, it’s stated from the start (I don’t remember at which point exactly, but I think it was in the beginning chapters); It’s that there isn’t a thing that causes problems and delays, there isn’t a specific thing that the book, the teacher or anybody else can tell you and warn you about at the moment when you become a software manager, or project owner, or developer.

Things just happen. A lot of them. At the start it’s just something simple, maybe something that no one thought that it could evolve to something else. Then another thing appears, now you notice but you don’t react immediately, and then another, and another, while the progress keeps getting slower and slower. And then the morale gets lower, and the performance too, and the client gets mad.

It’s a sad and stressful path. And there really isn’t something that you could know it will happen in every project. But you can try to prevent, everything, and make plans for every scenario if it comes to be, even if at the end the project goes very well.

And this is what the rest of the book is about. What is to really manage a software project and everything you can do when assuming such position. Either as a manager for the architects or a manager for the implementers, or general manager.

A basic concept for a good project to try to get to the end is communication. There is no chapter in the book where this capacity isn’t mentioned. It’s very important. At first level, there needs to be a very good communication between the architects and the implementers’ representatives. This is essential because the implementer will try to keep the architect from the skies and the architect can explain to the builders exactly what he wants. Then, problems will arise at the moment where an implementer has a doubt and doesn’t communicate it to an architect, and decides to just make assumptions. This only causes a slippery slope, where if this assumption causes a malfunction or a undesired quality of the project, a full redo must be done. Full communication should be present when talking to the clients, because after all, even if the architects are the ones who tell how they see the project, the client is the one who will have the final word. The don’t need to see the white box of things, only the black box, and if they don’t like it, everyone in the project is in problems.

Now, not every part of the communication has to verbal, in fact, it shouldn’t be. There is something important in writing things on paper. It will force the top-level architects, the implementers’ leaders and the implementers themselves to make micro-decisions at that moment. Sometimes just talking about it provides nothing useful (And if the person is like me, this happens a lot). Writing things out forces the author to state his ideas clearly. For the architects, it’s important to write on paper the specifications of the project. And those should take as many sheets of paper as necessary. Precision and lots of details are needed, even if the document becomes boring.

In the other hand, the main architect (Who is the main surgeon, as stated in the proposal for team organization in chapter 3) can’t deal with all the administrative work. Budgets, schedules, space allocation, and other organizational information should always be documented by the architect’s right hand. And why is this important? If most of the staff can work without knowing this information. Well, it’s important to not just tell on a daily basis what should the implementers do. They tend to feel more secure and have a better performance if they know the full work plan. Where are they working? How much time they have left? What is the course of action if some requirement isn’t meet on the schedule? It’s important the full staff is aware of all these questions and answers.

And finally, what should the base developer write? Like everyone else, everything. His doubts, his progress, the bugs he has found, the bugs he has solved and how were solved. This log will serve for the future because we can almost assume that those questions weren’t thought only by on developer, but by many of them, or almost everyone, especially if an architect hasn’t made a good job describing his design.

Who would have guessed that at the end, communication is the basis for a project not to fail, as it is to solve most or all of the problems in life? Always ask, never assume. Talk in the proper medium and style as corresponds to your position, talk with respect, but most importantly talk with precision and details. It will be easier for the other person to provide you with a solution to your problem, or answer your question.

Oh, and another thing I like a lot about the book is the proposal for team arrangement. Instead of having to deal with a lot of programmers that are currently working for the project (And them having to deal with each other, and a unique leader -you-), let’s have micro teams. Where each team will have a surgeon and a copilot, and they and only them will work directly with the code (In fact, the copilot can suggest changes and offers his opinion, but he doesn’t make any decision) and the rest of programmers can work on other things. There will be also a chief surgeon (Chief architect) who will coordinate with the rest of surgeons. This makes the work related to the chain of command easier. And also for each developer, because know their specific role in all the frame.

I must say that I was planning on giving an analysis per chapter, but time wasn’t enough. So I instead preferred to give this more general opinion of the book.

You can find some specific posts I did make here.

 


Mythical Man-Month Analysis

2 of Plato’s regimes – MMM Ch. 4

--Originally published at That Class Blog

Conceptual integrity is to maintain the good initial ideas, even if it implies not making that many features. This is better than having lots of uncoordinated ideas.

Likewise, functionality and simplicity. Which is better? There have been software projects that have an outstanding performance in one of both.  But we have to say that it’s a combination of simplicity and straightforwardness. Every part must use the same philosophies, same semantics and syntax and the, you have conceptual integrity.

And how, or more precisely, who will achieve that integrity? Either one mind (Surgical team), the equivalent to an aristocracy; or a handful of minds, with a division of architecture and implementation, the equivalent to a democracy.

And it’s no bad to desire a democracy, but it has several problems. The people in charge of the architecture should consider methods to implement their architecture; the implementers, when suggesting ideas must preserve the integrity of the architects.
That’s why at the end, the aristocracy (Surgical team) is better because as long as the design and implementation are clear in the surgeon’s mind, everything is ok. Or at least, an aristocracy of architects, who have a clear idea of how the system should behave, and they should decide how to maintain integrity, even if that means to leave the implementers with practically no voice, at the end, what must endure the most is the design, not the implementation.

2 of Plato’s regimes – MMM Ch. 4
Using CC (BY-SA). Published by Jocelyn Kinghorn. From https://www.flickr.com/photos/joceykinghorn/11487085615

 


2 of Plato’s regimes – MMM Ch. 4

The Surgical Team – MMM Ch. 3

--Originally published at That Class Blog

The dream: To develop a project with a small team you can know, and trust in their abilities. Forget the big teams, integrated by mediocre developers. In fact, by spending the double on a very good programmer, 10 times the performance could be expected. We can do this all by ourselves. Ah… The dream…

The reality: Big and complex problems need to be done and big teams are needed to do this.

How? Harlan Mills offers a solution. To make several teams, where only one member of each attacks the problem, and the rest only assist him in achieving maximum productivity. You keep a few number of people in the building design, but a lot of them in the actual construction. Just like a surgical team.

Here are the roles of this approach:

  • The surgeon: Define functional and performance specification. Designs, codes, tests the program and writes its documentation.
  • The copilot: Is a less-experienced surgeon. He advises the surgeon, and he can listen to him, or not. He knows the code perfectly but isn’t responsible for it.
  • The administrator: Even though the surgeon is the boss, he needs someone to be in charge of his administrative (Money, personnel, machines…) decisions. The administrator can serve 2 teams.
  • The editor: He writes the external and internal documentation. He reworks the draft of the surgeon.
  • Two secretaries: One for the administrator and the other one for the editor.
  • The program clerk:  He is in charge of the maintenance of the machine and user readable files.
  • The toolsmith: File, text and debugging services. Made fast and with quality
  • The tester: Design test cases and data.
  • The language lawyer: Master of the language selected for development. Can work with 2 or 3 surgeons.

Because the purpose of this team organization such that everyone is represented as just one, the surgeon. At the end, instead of organizing a 200 people team, you just have to deal with 20 surgeons.

The Surgical Team – MMM Ch. 3
Using CC (BY-NC-ND). Published by UCD School of Medicine in https://www.flickr.com/photos/76652722@N04/6878041625

The Surgical Team – MMM Ch. 3

Interpolación de Newton y Lagrange

--Originally published at That Class Blog

Antecedentes

Ambas interpolaciones son métodos que permiten la creación de un polinomio de n -1 grado, donde n es el número de datos que se poseen. Ambos métodos asumen que no existe ruido en sus mediciones de datos, es decir, que el polinomio generado por el método pasara por todas las coordenadas insertadas al método.

A menos que se conozca la función original (Lo cual es prácticamente imposible al aplicarlos en la vida real), no hay manera de calcular algún error.

Justificación y propósito

El propósito de ambos métodos es poder generar una función para la cual se puedan introducir todos los datos originales y obtener 0 error, pues la curva se va modelando punto a punto. Al obtener una función, se puede crear aproximaciones y estimaciones.
(En nuestros métodos, no proporcionamos al usuario la función, solamente el valor f(x) para la x deseada)

El método de Newton utiliza la formula de polinomios de Newton:

N(x)=[y_{0}]+[y_{0},y_{1}](x-x_{0})+cdots +[y_{0},ldots ,y_{k}](x-x_{0})(x-x_{1})cdots (x-x_{{k-1}}).
Donde las “y” entre corchetes se refieren al calculo de diferencias dividas, el cual es un algoritmo usado para computar tablas de funciones logarítmicas y trigonométricas, usando división recursiva.

El método de Larange obtiene una misma función, pero elimina por completo la necesidad de usar diferencias divididas:

L(x):=sum _{j=0}^{k}y_{j}ell _{j}(x)

donde

ell _{j}(x):=prod _{begin{smallmatrix}0leq mleq k\mneq jend{smallmatrix}}{frac {x-x_{m}}{x_{j}-x_{m}}}={frac {(x-x_{0})}{(x_{j}-x_{0})}}cdots {frac {(x-x_{j-1})}{(x_{j}-x_{j-1})}}{frac {(x-x_{j+1})}{(x_{j}-x_{j+1})}}cdots {frac {(x-x_{k})}{(x_{j}-x_{k})}},

Los polinomios de lagrange son más fáciles de computar, pues elimina la necesidad de recurrir a métodos de recursión,

Explicación gráfica de la interpolación

Diagrama de flujo

Newton

Interpolación de Newton y Lagrange

Lagrange

Interpolación de Newton y Lagrange

Código en C++

Ejemplos resueltos


Interpolación de Newton y Lagrange

Quality Meter: Ch. 9 SG

--Originally published at That Class Blog

Let’s do this fast folks, because this chapter was looooooooong.

So, first things first. What is quality? We have to thank McConnel for this simple definition: “the degree to which the software satisfies both stated and implied requirements”. Easy to understand. Perfect.

But why is this important? Because keeping defects controlled affects the development speed, cost and characteristics. A delivered low-quality software increases the cost of end-user support, among other things. McConnel emphasizes in remembering that the end-user tends to forget the delivery time of the software, but not if they liked using it. They forgive taking even taking more time than expected if they will enjoy using the software.

And how to keep the quality up at all times? Using the Quality Assurance Plan. The team must commit to the QA Plan. The activities of the QA must be planed and committed to writing, the QA must be established at least at the same time as the project requirements, a group that will take care of the quality must exist, with capable people, and finally, all the QA activities must be well funded.

And which activities conform the QA Plan?

  • Defect Tracking: Keep record of every defect that is found during development. The moment of detection, and the moment where the defect was resolved (And how). Its important to keep the information public, so the team can adjust the estimates, and see progress.
  • Unit Testing: Testing made by the developer who wrote the code. The unit can refer to any programming entity. It’s informal.
  • Source-Code Tracing: Carried out also by the person who wrote the code. Consist in going through the code, line-by-line, using a debugger.
  • Technical Reviews: This are reviews made by the peers of the code author. Usually are given by the full team, and the QA staff just makes sure this reviews are being carried out. Technical reviews have a pattern:
    • Notification and distribution: The code’s author notifies to the QA team that the work is ready to be reviewed. The material is distributed to the corresponding people.
    • Preparation: Reviewers review the work, using checklists of common errors. They schedule a review meeting.
    • Review meeting: Evaluate the work alongside the developers and a moderator. The main objective is to detect defects.
    • Review report: The results of the meeting are written to paper, committed, and added to the defect tracking.
    • Follow-up: The developer applies the changes, which are evaluated again, and if approved and passes the review, the material is added to the list of materials that have been successfully reviewed.
  • Integration Testing: Test the code developed with already tested code, which has been integrated to the complete system.
  • System Testing: Execute the complete software to find defects. This is by no means a complete way to find all of the defects.

Sometimes companies also use Beta Testing. Even if the book doesn’t recommend it as much as the other tactics (Which are internal), it might be helpful to consider using it, because of the great final-user feedback the developers might receive.

And that’s it. Let’s not stop the testing, until we run out of cake…

Quality Meter: Ch. 9 SG
Used under CC 2.0 (BY-SA). Published in: https://www.flickr.com/photos/chripell/3409348666

Quality Meter: Ch. 9 SG