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I've decided to get some experience working on some project this summer.
Due to local demand on market I would prefer to learn Java (Standard and Enterprise Editions).
But I can't even to conjecture what kind of project to do. Recently I had some ideas about C. With C I could to contribute to huge Linux projects. I don't mean that my work will be surely commited. I could get the code and practice with it. But C it's not right thing to get good job in my area. In case of JavaSE there is a chance to develop some desktop applications. But thinking about JavaEE I get stuck. I'll be very thankful for answers.
CodingBat.com will give you good core Java practice.
Project Euler is still the best for all around practice. You can use whatever language you'd like to solve the problems there.
For actual projects, I almost always start on something easy like a Twitter client. It gets you exposure to all the basics along with UI and network communication. You can work up from there. Just don't start with something so overwhelming that you can't figure it out and want to give up. That's not going to get you anywhere.
The best advice is: work on a project that you have personal interest in. Something based on your hobbies, maybe.
If that doesn't work, make a blogging / CMS engine. Or an online photo album. Or an eStore. The world doesn't really need another of any of these things, but it will give you some good practical experience with JavaEE.
Another benefit of "re-inventing the wheel" (for learning) is that you have probably already used systems like these described above, and you have a good idea of how it can work, and maybe you have your own ideas of how it could work better. That can make requirements much simpler, and also will give you a sort of benchmark so you can see how close you can come to building a tool like the "real" ones out there. And if yours is really great, well, maybe release it and see what happens. ;)
There are many Java-based projects on SourceForge. Tinker with one you find interesting.
I've implemented either a betting pool or a Baccarat game in almost every language I've
learned.
This type of software covers:
Dates and times, with calculations
Currency types and things that can be converted to and from currency.
A discrete set of rules that is easy to test
States, transition between states and multiple entities responsible for state transition
Multiple users with different views of the same model End conditions
Multiple player blackjack and poker would work also.
One caveat is that in my day job I work on financial systems and there is a huge overlap
between things to consider when writing a multiplayer game of chance and a trading system.
build an address book. the concept is simple, so you're not stuck on "what" to write. You can focus on learning your chosen language. You get experience in working with a database, java ( insert any language here), and UI design.
when you decide to learn another language you can create the same thing. Since the database has been created already, you can focus on the language itself.
the concept of inputting data, storing data, and retrieving data is central to a lot of applications.
Have a look around http://openhatch.org/ for a project that sounds interesting.
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As many of us do, I have lots of software ideas, a couple of really good ones, and not enough time to do everything. (I am a developer, but only one). I would like to open source some software and ideas in progress but also retain direction and vision of the project. Up until now I've only worked in non-free-as-in-beer software and it escapes me how open source could meet my need for control of it.
Let me be clear I don't intend to commercialize open-sourced projects for money. That much I know. I just want to have control of my vision which I start.
To control my own open source project I would need to manage it by providing guidance but that facet escapes me also, about how to manage something that's effectively free.
Am I barking up the wrong tree?
I've gone through this cycle myself, and can tell you you're way out in front of the horse with the cart. Not to sound harsh, but there's a frame of reference you should definitely gain.
First, "control my own open source project" -- is conflicting. Open Source involves giving something away, in this case to a community. So, thinking about control and ownership of something you've given away is a mental hurdle you need to cross.
Second, you need someone other than yourself willing to participate in your project. Without them, you won't have anyone to divert any direction and vision you might have.
Third, control in terms of project guidance is earned in any open source projects with any sort of following. It doesn't matter if you're the original developer with the initial idea; if the community is willing to follow your guidance, they will. If not, they'll simply not participate.
Enough soapbox. In terms of project management, divide the role into two functions:
1) Getting developers involved, taking on tasks, code reviews, guidance and direction, etc. Trust me, this is as much a sales job as it is credibility-based. Top-down, hierarchical, seniority-based I-was-here-first type of expectations is a sure-fire way to drive volunteers away from your project.
2) Repository logistics. In the end, you can control who are/are-not committers, their permissions, etc. If you do #1 well enough, this will take care of itself.
As a last bit of commentary, open source projects are not easy to get off the ground. There are more projects than people willing to put forth the amount of sustained effort necessary to give your project legs.
Good luck!
Well, Captain Bligh, it all depends on how you hand out commit permission, now, doesn't it? If you make the source open, but tightly control commits, then the vision is all yours. Assuming, of course, that you can find anyone else who cares enough to submit patches for your review and evaluation.
Linus Torvalds had a great speech on google talk about how he is using (among other topics) git to avoid having to include all code from the open source community! It is deffently worth checking out!
You probably can't have your cake and eat it too. If you open your source under a "real" open source license, then anyone who wants to would be able to start their own project. You could maintain control of the "real" project. Then it is a matter of waiting and seeing which version users like better, and which version attracts most of the community. You will always have control of "your" branch of the project. What you must accept is that someone else may become more successful with your original code than you are, and thus also have control.
In general, there are more ideas out there than there are developers waiting to work on them. So your real problem will likely be getting anyone to care about your project enough to contribute patches, let alone care enough to usurp control.
Even if you make the source available in a repository for anyone to grab, you still maintain control over the repository: you decide who has access, you decide which patches are committed (or at least, you decide who gets to decide which patches are committed).
However, this doesn't stop people forking your project and taking their forks in a different direction. There aren't any easy ways to prevent that: some people are ornery and will fork every project they touch, while other people might just have a different idea about how your code could be useful.
The best way to minimise forks is to be engaged with the community: be involved in discussions on the direction of the project, accept patches that add features that people want (while maintaining your own coding style and standards of course). If it's easier for people to work with the community and you than it would be to maintain their own fork, most people won't bother forking.
Of course, this means you've ceded some control to the community, because if you stubbornly refuse to give them what they want they're going to make a fork..
Sounds like the missing ingredient is some enthusiastic developers who love your ideas and are prepared to work for free.
I don't think they just pop out of the internet; you will need to go find them.
And once you find them, you need to keep them interested, which may well mean giving up some or all of that control...
Ask yourself what is your goal here–to deliver a software innovation to the world, or to have a pet project?
Well it just depends on what kind of project you are opensourcing.
Are you opensourcing one tightly defined core functionality in a small library, like a Ruby Gem, or a PHP PEAR Package, or are you looking to create the next Wordpress where millions of users have an opinion?
I would suggest starting small. Use something that you've written before, and can be used by others:
A jQuery plugin.
A Wordpress Plugin.
A PHP PEAR Package or a proposal to the Zend Framework.
A Ruby Gem that creates a behavior that can be used in Rails.
A module, or add on to some open source CMS.
Create a specific functionality that you want. Put it somewhere that other users can fork or branch your code, but don't let them merge back to the main branch or trunk of your code.
That way people can work with your code, but ultimately, you have control of what goes back into the official project.
Basically, you can't.
You can't prevent someone else fork your code and start a new project.
At most what you can do is to pick a license that says the source code can't be used to the same product ( I don't know which license is this, but it exists )
And secondly, what you can do is to have a very good control of existing base and a list a features you want to include.
If your project is forked, your new features will make less attractive the other.
Finally, your project will be forked if you don't work on it and leave it die. Otherwise nobody will come and fork your project when you're doing all the hard work right?
Here's a couple of interesting videos on the subject:
http://www.youtube.com/watch?v=-F-3E8pyjFo
http://www.youtube.com/watch?v=0SARbwvhupQ
If it's open source, at the end of the day you cannot control it - anyone will be free to fork it and go on their own sweet way. The way to prevent this happening is to be a "benevolent tyrant" and take on board other people's views on the project's direction. This assumes anyone else is interested in what you are doing, of course.
I think I'm in somewhat of a unique situation: I have a decent amount of coding experience in C/C++ in a Linux environment. However, I don't really have "project experience." For example, I'm familiar with the concept of version control, but I've never used any. Or, i've never worked on a project with more than a half dozen source files.
So, where I am now is that I'm working on this project with a large amount of code already existing. I have to write all my code in a windows environment using Visual Studio 2008 (Visual C++ to be specific) So I have a few questions:
How do integrate the already existing code into VC++? I'm using tortoise SVN and I have all the code on my machine...
Does anyone have any general advice on moving from small projects to larger projects?
Any help/advice would be greatly appreciated
Some of the keys to coming to grips with a large codebase:
Learn the ins and outs of source control. For now, start with just learning how all the SVN commands work. SVNBook is a good resource for this. Use VisualSVN or a similar plugin to interact with your repository within your IDE (Tortoise is still useful when you want to interact from elsewhere). Down the road, you'll want to become intimately familiar with branching and merging (and the tools for doing so quickly and correctly), and perhaps learn a DVCS (distributed version control system) like Git or Mercurial. This will at the very least expand your mind a bit, and likely teach you some lessons that will be useful even in projects where you use more traditional (centralized) version control.
Learn how to quickly look for things, find the declarations of unfamiliar classes and variables, and trace the execution of the larger application. There are lots of approaches for this, and you'll likely use most of them at one point or another, but some of them are your IDE's built-in features (most of them are quite robust in this regard, you should be able to right-click on a class name and find its declaration easily), grep and the like (ack is a variant that is very suitable for code spelunking), and CTAGS if you swing that (C/C++) way.
Learn the basics of unit testing, maybe even try out a framework like NUnit. Personally I'm not big into unit tests, but I recognize their utility and many swear by them, so don't knock it 'til you've tried it, at least.
Even if you're a flawless programmer with a robust battery of unit tests, large codebases demand a higher level of debugging skill, due to the inherent complexity of the problems that crop up. Whether it's learning how to write concise, descriptive debug printf()-like statements, becoming more familiar with your debugger, or even learning the ins and outs of your language (e.g. the corner cases of the type system/object model) can be helpful in unwinding these complex issues.
Unfortunately, I haven't used Visual Studio, but I think getting to know your IDE's project import/migration flow will be instructive too. Maybe somebody else will chime in with more concrete advice on that front. The process can be onerous, especially if you had a non-standard custom build system before and you want everything to be done The One True Visual Studio Way henceforth, but the tools for automatic dependence extraction from code are getting better and better.
The ideas already given are very good. But you also might want to read Mike Gunderloy's Coder to Developer. From your description of your current experience, I think you'll find it useful. Also read The Pragmatic Programmer; I keep it in my office by my desk, and often find myself loaning it to younger developers.
Just dive in. Hopefully whoever has been working on this project so far organized the code into logical groups (namespaces, class hierarchies, folders).
I'll also second Matt J on learning how to use the IDE: I'm not familiar with Visual Studio specifically, but there should be contextual menu items when you click on a class or method to take you to the place where it was declared, and from there to the classes it was derived from.
Get version control set up first though: you'll feel more comfortable poking around once you learn how to "revert" ;)
I have been using VisualSVN for quite a while without problems. It integrates perfectly with vs2008. As for moving on to large projects, a great way to see how things are done is to download the source of a decent size existing project and see how it was put together. After you've got a good idea of how things are structured, the best thing you can do for yourself is to write code. Brainstorm a project and go at it. Depending on how you feel about your outcome after completion, you could use it as part of your portfolio as well.
Unit tests. Use them or you'll regret it.
Get to know Visual Studio well, if you live in it, you really have to know it well.
AnkSVN is a free plug-in for Visual Studio 2008, and it works very well.
Also, Refactor for C++ is another free plug-in and one of the only ways to get refactoring support in Visual C++.
Also, you will soon learn that on large projects, 80% of your time is going to be spent doing code maintenance, so do yourself a favour and make your code a place in which you want to live, not a place of terror that you shrink back from. Clean code, the occasional comment, and unit tests will go a long way to making you want to get up and go to work in the morning, rather than dreading that you have to work on that monstrosity where anytime you touch anything it breaks.
I want to allow the user to resize columns in an HTML table, using the same method as you would in Excel. Drag the space between columns and size.
I did some research on this last year, and found a few hacks and kludges. Most were pretty bad, and I didn't find anything really good. Now, it looks like I need to implement this functionality, and want to do it right, so before I start this again, I just thought I'd ask if anybody else has done this, and how they did it.
I believe I've seen a FogBugz demo video where they had this implemented. So I know it can be done well.
BTW-I'd prefer not to use any open source frameworks, since my client may sell this app in the future.
I've built a html grid myself in the past and having done so my best advice would be: use someone else's.
I've looked at this jquery grid control in the past but have never got around to trying it out:
http://www.trirand.com/blog/
Google Docs spreadsheet application does what you are looking for. That may be worth looking at, but their code is very dense.
The extjs framework provides the functionality you need. I can not tell (I am no lawyer) whether their license is suitable for your customer or not. However, it appears possible for you to purchase a license from them which allows you to not have to publish your customers code as open source. This may suffice.
I would suggest that you develop your application using extjs in parallel with investigating the license. if the licensing suits your customer, you're done, and you win by using a stable and high-quality platform. If your can't make the license work for your customer, then you have to port to something else, but at least you will already have a high quality first prototype to work from, so the effort to produce the product will be less. And meanwhile you have a very nice prototype while refining the interface
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Joining an existing team with a large codebase already in place can be daunting. What's the best approach;
Broad; try to get a general overview of how everything links together, from the code
Narrow; focus on small sections of code at a time, understanding how they work fully
Pick a feature to develop and learn as you go along
Try to gain insight from class diagrams and uml, if available (and up to date)
Something else entirely?
I'm working on what is currently an approx 20k line C++ app & library (Edit: small in the grand scheme of things!). In industry I imagine you'd get an introduction by an experienced programmer. However if this is not the case, what can you do to start adding value as quickly as possible?
--
Summary of answers:
Step through code in debug mode to see how it works
Pair up with someone more familiar with the code base than you, taking turns to be the person coding and the person watching/discussing. Rotate partners amongst team members so knowledge gets spread around.
Write unit tests. Start with an assertion of how you think code will work. If it turns out as you expected, you've probably understood the code. If not, you've got a puzzle to solve and or an enquiry to make. (Thanks Donal, this is a great answer)
Go through existing unit tests for functional code, in a similar fashion to above
Read UML, Doxygen generated class diagrams and other documentation to get a broad feel of the code.
Make small edits or bug fixes, then gradually build up
Keep notes, and don't jump in and start developing; it's more valuable to spend time understanding than to generate messy or inappropriate code.
this post is a partial duplicate of the-best-way-to-familiarize-yourself-with-an-inherited-codebase
Start with some small task if possible, debug the code around your problem.
Stepping through code in debug mode is the easiest way to learn how something works.
Another option is to write tests for the features you're interested in. Setting up the test harness is a good way of establishing what dependencies the system has and where its state resides. Each test starts with an assertion about the way you think the system should work. If it turns out to work that way, you've achieved something and you've got some working sample code to reproduce it. If it doesn't work that way, you've got a puzzle to solve and a line of enquiry to follow.
One thing that I usually suggest to people that has not yet been mentioned is that it is important to become a competent user of the existing code base before you can be a developer. When new developers come into our large software project, I suggest that they spend time becoming expert users before diving in trying to work on the code.
Maybe that's obvious, but I have seen a lot of people try to jump into the code too quickly because they are eager to start making progress.
This is quite dependent on what sort of learner and what sort of programmer you are, but:
Broad first - you need an idea of scope and size. This might include skimming docs/uml if they're good. If it's a long term project and you're going to need a full understanding of everything, I might actually read the docs properly. Again, if they're good.
Narrow - pick something manageable and try to understand it. Get a "taste" for the code.
Pick a feature - possibly a different one to the one you just looked at if you're feeling confident, and start making some small changes.
Iterate - assess how well things have gone and see if you could benefit from repeating an early step in more depth.
Pairing with strict rotation.
If possible, while going through the documentation/codebase, try to employ pairing with strict rotation. Meaning, two of you sit together for a fixed period of time (say, a 2 hour session), then you switch pairs, one person will continue working on that task while the other moves to another task with another partner.
In pairs you'll both pick up a piece of knowledge, which can then be fed to other members of the team when the rotation occurs. What's good about this also, is that when a new pair is brought together, the one who worked on the task (in this case, investigating the code) can then summarise and explain the concepts in a more easily understood way. As time progresses everyone should be at a similar level of understanding, and hopefully avoid the "Oh, only John knows that bit of the code" syndrome.
From what I can tell about your scenario, you have a good number for this (3 pairs), however, if you're distributed, or not working to the same timescale, it's unlikely to be possible.
I would suggest running Doxygen on it to get an up-to-date class diagram, then going broad-in for a while. This gives you a quickie big picture that you can use as you get up close and dirty with the code.
I agree that it depends entirely on what type of learner you are. Having said that, I've been at two companies which had very large code-bases to begin with. Typically, I work like this:
If possible, before looking at any of the functional code, I go through unit tests that are already written. These can generally help out quite a lot. If they aren't available, then I do the following.
First, I largely ignore implementation and look only at header files, or just the class interfaces. I try to get an idea of what the purpose of each class is. Second, I go one level deep into the implementation starting with what seems to be the area of most importance. This is hard to gauge, so occasionally I just start at the top and work my way down in the file list. I call this breadth-first learning. After this initial step, I generally go depth-wise through the rest of the code. The initial breadth-first look helps to solidify/fix any ideas I got from the interface level, and then the depth-wise look shows me the patterns that have been used to implement the system, as well as the different design ideas. By depth-first, I mean you basically step through the program using the debugger, stepping into each function to see how it works, and so on. This obviously isn't possible with really large systems, but 20k LOC is not that many. :)
Work with another programmer who is more familiar with the system to develop a new feature or to fix a bug. This is the method that I've seen work out the best.
I think you need to tie this to a particular task. When you have time on your hands, go for whichever approach you are in the mood for.
When you have something that needs to get done, give yourself a narrow focus and get it done.
Get the team to put you on bug fixing for two weeks (if you have two weeks). They'll be happy to get someone to take responsibility for that, and by the end of the period you will have spent so much time problem-solving with the library that you'll probably know it pretty well.
If it has unit tests (I'm betting it doesn't). Start small and make sure the unit tests don't fail. If you stare at the entire codebase at once your eyes will glaze over and you will feel overwhelmed.
If there are no unit tests, you need to focus on the feature that you want. Run the app and look at the results of things that your feature should affect. Then start looking through the code trying to figure out how the app creates the things you want to change. Finally change it and check that the results come out the way you want.
You mentioned it is an app and a library. First change the app and stick to using the library as a user. Then after you learn the library it will be easier to change.
From a top down approach, the app probably has a main loop or a main gui that controls all the action. It is worth understanding the main control flow of the application. It is worth reading the code to give yourself a broad overview of the main flow of the app. If it is a GUI app, creating a paper that shows which screens there are and how to get from one screen to another. If it is a command line app, how the processing is done.
Even in companies it is not unusual to have this approach. Often no one fully understands how an application works. And people don't have time to show you around. They prefer specific questions about specific things so you have to dig in and experiment on your own. Then once you get your specific question you can try to isolate the source of knowledge for that piece of the application and ask it.
Start by understanding the 'problem domain' (is it a payroll system? inventory? real time control or whatever). If you don't understand the jargon the users use, you'll never understand the code.
Then look at the object model; there might already be a diagram or you might have to reverse engineer one (either manually or using a tool as suggested by Doug). At this stage you could also investigate the database (if any), if should follow the object model but it may not, and that's important to know.
Have a look at the change history or bug database, if there's an area that comes up a lot, look into that bit first. This doesn't mean that it's badly written, but that it's the bit everyone uses.
Lastly, keep some notes (I prefer a wiki).
The existing guys can use it to sanity check your assumptions and help you out.
You will need to refer back to it later.
The next new guy on the team will really thank you.
I had a similar situation. I'd say you go like this:
If its a database driven application, start from the database and try to make sense of each table, its fields and then its relation to the other tables.
Once fine with the underlying store, move up to the ORM layer. Those table must have some kind of representation in code.
Once done with that then move on to how and where from these objects are coming from. Interface? what interface? Any validations? What preprocessing takes place on them before they go to the datastore?
This would familiarize you better with the system. Remember that trying to write or understand unit tests is only possible when you know very well what is being tested and why it needs to be tested in only that way.
And in case of a large application that is not driven towards databases, I'd recommend an other approach:
What the main goal of the system?
What are the major components of the system then to solve this problem?
What interactions each of the component has among them? Make a graph that depicts component dependencies. Ask someone already working on it. These componentns must be exchanging something among each other so try to figure out those as well (like IO might be returning File object back to GUI and like)
Once comfortable to this, dive into component that is least dependent among others. Now study how that component is further divided into classes and how they interact wtih each other. This way you've got a hang of a single component in total
Move to the next least dependent component
To the very end, move to the core component that typically would have dependencies on many of the other components which you've already tackled
While looking at the core component, you might be referring back to the components you examined earlier, so dont worry keep working hard!
For the first strategy:
Take the example of this stackoverflow site for instance. Examine the datastore, what is being stored, how being stored, what representations those items have in the code, how an where those are presented on the UI. Where from do they come and what processing takes place on them once they're going back to the datastore.
For the second one
Take the example of a word processor for example. What components are there? IO, UI, Page and like. How these are interacting with each other? Move along as you learn further.
Be relaxed. Written code is someone's mindset, froze logic and thinking style and it would take time to read that mind.
First, if you have team members available who have experience with the code you should arrange for them to do an overview of the code with you. Each team member should provide you with information on their area of expertise. It is usually valuable to get multiple people explaining things, because some will be better at explaining than others and some will have a better understanding than others.
Then, you need to start reading the code for a while without any pressure (a couple of days or a week if your boss will provide that). It often helps to compile/build the project yourself and be able to run the project in debug mode so you can step through the code. Then, start getting your feet wet, fixing small bugs and making small enhancements. You will hopefully soon be ready for a medium-sized project, and later, a big project. Continue to lean on your team-mates as you go - often you can find one in particular who is willing to mentor you.
Don't be too hard on yourself if you struggle - that's normal. It can take a long time, maybe years, to understand a large code base. Actually, it's often the case that even after years there are still some parts of the code that are still a bit scary and opaque. When you get downtime between projects you can dig in to those areas and you'll often find that after a few tries you can figure even those parts out.
Good luck!
You may want to consider looking at source code reverse engineering tools. There are two tools that I know of:
SWAG Kit (Linux only) link
Bauhaus academic commercial
Both tools offer similar feature sets that include static analysis that produces graphs of the relations between modules in the software.
This mostly consists of call graphs and type/class decencies. Viewing this information should give you a good picture of how the parts of the code relate to one another. Using this information, you can dig into the actual source for the parts that you are most interested in and that you need to understand/modify first.
I find that just jumping in to code can be a a bit overwhelming. Try to read as much documentation on the design as possible. This will hopefully explain the purpose and structure of each component. Its best if an existing developer can take you through it but that isn't always possible.
Once you are comfortable with the high level structure of the code, try to fix a bug or two. this will help you get to grips with the actual code.
I like all the answers that say you should use a tool like Doxygen to get a class diagram, and first try to understand the big picture. I totally agree with this.
That said, this largely depends on how well factored the code is to begin with. If its a gigantic mess, it's going to be hard to learn. If its clean, and organized properly, it shouldn't be that bad.
See this answer on how to use test coverage tools to locate the code for a feature of interest, without knowing anything about where that feature is, or how it is spread across many modules.
(shameless marketing ahead)
You should check out nWire. It is an Eclipse plugin for navigating and visualizing large codebases. Many of our customers use it to break-in new developers by printing out visualizations of the major flows.