Sunday, October 26, 2008

The Ultimate Continuous Integration Tool

Warning: this entry is out there. I can not be blamed for wasting your brain cycles. However, by taking things to the extreme, some value may be gained.

I'd like to continuously integrate all the code I write, and I want this to happen very continuously. And that would happen if my code is integrated on every key stroke.
My IDE, the build machine (CI server), and the source control system will be very smart. Every time I type key on the keyboard, they will mark a revision of the full code base and start running the build. Let's call this code revision a candidate revision (CR). The build, of course, includes compiling the code, running all unit tests, perhaps even functional tests, and whatever else we want to include. If the build passes, the CR is automatically checked into source control. If the build doesn't pass, then the whole thread is ignored. Obviously, since I won't stop pounding on the keyboard, the very powerful build machine will be running multiple builds at the same time. After all, the computers are not yet that advanced, that we should expect the build machine to be able to run builds instantly. Oh well.
At the same time, the system will be doing the reverse: It will be continuously merging all successful revisions from source control (SC) into my local code base, since everyone else is so productively writing code at the same time as I am.
How could this work? Well, my IDE will be so well integrated with the super powerful CI server. The CI server will be the single authority deciding whether a build is passing, and thus would be checked into source control. The CI server will be running many builds at the same time, but will act as if all the changes occurred sequentially.
The CI server will be receiving a stream of candidate revisions (ok, just deltas) from multiple developer machines. It always starts from a successful source code revision (CR0). Based on the order a candidate revision (CR1) is received, it will run the build and determine if it should be checked into SC. At the same time, the CI server is also processing other candidate revisions (CR2, 3, ...) from myself and other developers. The CI server will be running multiple builds at the same time: a duild for CR1, another for CR2 (on top of CR1), another for CR2 on top of CR0, in case CR1 fails, and so on.

Here is a diagram of the process:

This would be really nice. Don't you think?

Sunday, October 19, 2008

ssh connection with public/private key pair not working on Leopard?

Solution: try passing the private key file to the ssh command using -i:

ssh -i identity_file user@server

The problem
I tried setting up a DSA public/private key pair on Leopard. but I didn't accept the default private key file name. Leopard didn't prompt me for the passphrase, and instead was prompted for the normal username/password.

Project Development Knowledge: Sharing and Enduring

The previous entry introduced the problem. The following is a discussion around practices that can help address it.


Daily standup meetings [1], aka daily scrums, are a great way for the team to share information about the current tasks being implemented by different team members. It's a quick forum, at the end of which, each team member will have basic knowledge of what other team members are up to. This can be very effective in eliminating duplicate efforts, as well as helping team members relate to other work affecting their own. Team members who notice the potential for cooperation and knowledge sharing during the standup, should get together after the meeting to carry on with further, more detailed examination of their work.

Pair programming

Controversial as it may be, this practice is very effective in achieving higher team productivity through continuous knowledge sharing. The risk of the knowledge leaving the team is greatly reduced. And if we enhance this practice by frequent pair rotation, it's even more effective, as it spreads more knowledge throughout the development team, and it encourages cross-pollination of ideas.


Having to communicate information to other team members highlights a hand-off transition, that is better avoided. It's much better if all the team is there, witnessing and participating firsthand the effort underway, rather than being communicated what happened. Colocation of the team, or as much of the team as possible, is very effective at eliminating that need. And when information is communicated within a co-located team, it's at least an order of magnitude more effective, efficient, and complete, compared to other means.

Code reviews

When a pair spends a day modeling a piece of functionality, or refactoring a key part of the system, they are likely to want to tell other team members about it. Invariably, everyone in the team is interested to know what others are doing, and how certain problems are being addressed. While pair rotation helps here, getting the whole team to participate in a code review session can achieve some of this benefit to a wider audience. It's also a great forum for seeking guidance, sharing opinions, and exploring novel ways to address issues.


Automating a certain task is an excellent way of sharing how it's done. Automation enables other team members to achieve the task, as well as serve as a documentation on how to accomplish it. For example, instead of me asking you how you query for the balance sheet, I can either use an automated script to get the information, or I could learn from the script how it can be done.

Self documenting, readable code

Code can be considered a misnomer in this regard. We'd like to have code that does not require deciphering. We'd like to be able to know what the code is doing, and how it's done, clearly, with minimal effort. Herein lies an argument against clever programming techniques, that make it harder to reveal intent and side effects. Use code reviews to highlight less than obvious techniques, and have the team workout what it's most comfortable with. For example, if multiple team members are having issues with a piece of code that uses reflection, consider first informing more members how the piece works, and if necessary, consider an alternative implementation. Enabling higher team effectiveness is valued higher than programming cleverness.

Good check-in comments

These can go a long way in telling the story of project development. A check-in delta tells you what changed. The comment tells you why. When a developer has to go through source code history to understand the rationale behind a certain change or design decision, these comments can be very helpful in that regard. Try to be helpful to the consumer of the comment. For example, instead of typing "implemented story #123", provide more information: "Story #123: added capability to classes x and y to access context z to achieve a and b."


Project wikis have been around for while. Dare I say that they are the norm these days? Wikis are an excellent source of day-to-day knowledge needed by the team. For example, database connection information, URLs to local servers and useful documentation, pointers to tools, project and domain specific acronyms, etc. They are also useful in documenting repetitive development tasks, that are yet to be, or are difficult to automate.
One particular use that I wish to highlight is documenting errors that are encountered during development, whether or not they are corrected. For example, if while starting a server we notice that we are getting an exception, we should start by documenting this fact. We then add the solution once we figure it out. Certain problems have the tendency to re-occur, while some are unlikely to occur once fixed. Nonetheless, a similar issue might arise and the fix may prove useful beyond the original use.

A searchable, archived email list

I have not seen this one on many projects. However, a sizable portion of the project information is exchanged using emails. For example, feature discussions between developers and BAs, the resolution of design issues, technical announcements, in the form of the introduction of a new build tools or code libraries, and project course-changing decisions, to name a few. An automatically archived project specific email list that is searchable can be very valuable for future development. Using this knowledge base can aid in understanding why things came to be the way they are.

This list isn't exhaustive, and each one deserves its own discussion. I meant to hint and introduce. None of these practices preclude another, and you can attempt all of them.
A bit of warning though: do not over do any of these, and keep the practices light. After all, we are after agility. Don't let these, or any other practices slow down the gemba.

As usual, I welcome, and appreciate, the reader's feedback.


Saturday, October 11, 2008

Keeping Project Development Knowledge: The Problem

This is a two part entry. This entry is an introduction to the problems caused by the loss of development knowledge, that face project teams. The second part will examine various practices and techniques that can be used to tackle these problems.

By project development knowledge, I'm referring to the multitude of information required, and acquired, by the development team, that pertain to the project. This includes technical knowledge, concerning languages and tools, as well as development methodology, processes, business domain, etc.

Is there a problem? To help answer this question, consider the following events:
  • A long time team member is leaving the team.
  • An issue is identified with the software that the team is building. However, we know we've encountered this problem before. If only we can remember how we solved it.
  • A new team member is joining the team, and he's started asking questions about the project, or is encountering some issues setting up his environment, and we have to rely on memory or some veteran team members to answer these questions.
  • A BA notices that he is being asked the same question more than once by different team members.
  • The tech lead is noticing that the team members are not following coding standards, time and again.
  • Two team members are working separately on fixing the same problem.
  • A new team member is brought to take care of a code module, that no other team member knows about. For example, when code is inherited from another software company after their contract has ended, a team member is replacing another who was working alone on a piece of code, or when a certain area of the code has been dormant for a long time, that now requires changes.

These events represent times where project information is missed. This can be attributed to the following reasons:
  • Information leaves the team, along with parting team members.
  • Information is forgotten, thus, it needs to be reproduced.
  • The information exists, but is not readily accessible; the information is not easily communicated.
  • The information exists, but we don't know that.

How do we tackle these problems? The next entry will discuss some approaches that can help address some of these problems.