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What are your criteria for selection a (open source) library (or framework) for enterprise usage?
Some libraries are pretty small and can be easily checked for security flaws or tested for performance. But most libraries are too big to be reviewed before you can start to use them.
When I think of me selecting a library, most if the selection process is just gut feeling. When I try to be more specific, these are the first criteria which come to my mind:
How many developers are working on the project? My feeling is that more developers will find more bugs and security issues. In addition it will be harder to introduce security issues intentionally.
How good is the support? Compared to closed source libraries, I've got the feeling that the support of open source is often much better since you have a community around the globe which will be available whenever you need them.
How wide spread is the library? Are there any books about it on the market? Which other projects are using the library?
What are your criteria? Feel free to edit this note as community wiki.
For me, it depends on whether or not it is paid for or not. In your case, you give the impression you are looking at open source libraries.
In that specific case, I'll look at test coverage. Regardless of the number of contributors, if there aren't any unit tests that I can run myself (as well as enhance and test my use cases for if they fall outside the coverage of the unit tests provided), then that's a massive issue for me.
It's not that I don't appreciate the work that is done already in providing the library, but code in projects like this should have unit tests already with good coverage in order to gain traction.
If there are no libraries that have unit tests, then I would start searching for the library on search engines, actively seeking out negative replies. People who have negative feelings about the code and can crystalize the objective basis for those feelings in terms of how the code failed them will provide more valuable feedback than the masses that say "it works great".
Now for a commercial piece of code, it's completely different. At that point, I'd start looking at the company and it's support staff as a whole, and using that as a determination (as well as tests of your own to see if the library is right for you) as to whether or not to use that company's offering.
Quite often in open source libraries you cannot get reliable support. In such situations your best bet is to fix it yourself, which involves the following requirements.
You need to have the ability to read often messy and undocumented code.
The technical ability to ask the right questions from the right people -- i.e., these people aren't being paid to fix problems and they will only answer you if you make it easy enough for them.
Then you need the ability to fix the bug and get the patch accepted -- because if the patch isn't accepted .....
With this in mind I would be inclined to get a commercial library, or dual licensed library so that I could pay to get a competent engineer (motivated by the money I pay his company) to fix my problem.
There is what seems to be a plethora of version control systems. Therefore, to draw a bad conclusion, it must be easy to write one.
What are some issues that must be considered in order to write a simple file versioning system? (What are the minimum necessary functions?)
Is it a feasible task for one person?
A good place to learn about version control is Eric Sink's Weblog. His most recent article is Time and Space Tradeoffs in Version Control Storage, for one example.
Another good example is his series of articles Source Control HOWTO. Yes, it's all about how to use source control, but it has a lot of information about the decisions and tradeoffs developers have to make when designing the system. The best example of this is probably his article on Repositories, where he explains different methods of storing versions. I really learned a lot from this series.
How simple?
You could arguably write a version control system with a single-line shell script, upversion.sh:
cp $WORKING_COPY $REPO/$(date +"%s")
For large binary assets, that is basically all you need! It could be improved quite easily, say by making the version folders read-only, perhaps recording metadata with each version (you could have a text file at $REPO/$(date...).meta for example)
That sounds like a huge simplification, but it's not far of the asset-management-systems many film post-production facilities use (for example)
You really need to know what you wish to version, and why..
With large-binary assets (video, say), you need to focus on tools to visually compare versions. You also probably need to deal with dependancies ("I need image123.jpg and video321.avi to generate this image")
With code, you need to focus on things like making diff's between any two versions really easy. Also since edits to source-code are usually small (a few characters from a project with many thousands of lines), it would be horribly inefficient to copy the entire project for each version - so you only store the differences between each version (delta encoding).
To version a database, you probably want to store information on the schema, tracking new tables, or columns, or adjustments to existing ones (rather than calculating deltas of the database files, or making copies like the previous two systems)
There's no perfect way to version everything, you have to focus on doing one thing well.. Git is great for text, but not for binary files. Adobe Version Cue is great with binary files (images), but useless for text..
I suppose the things to consider can be summarised as..
What do you want to version?
Why can I not use (or extend/modify) an existing system?
How will I track differences between versions? (entire files? deltas?)
What other data do I need to attach to versions? (Author? Time-stamp? Dependancies?)
What tasks would a user commonly need to do (diff'ing? reverting specific files?)
Have a look in the question "core concepts" about (D)VCS.
In short, writing a VCS would involve making a decisions about each of these core concepts (Central vs. Distributed, linear vs. DAG, file centric vs. repository centric, ...)
Not a "quick" project, I believe ;)
If you're Linus Torvalds, you can write something like Git in a month.
But "a version control system" is such a vague and stretchable concept, that your question is really unanswerable.
I'd consider asking yourself what you want to achieve (learn about VCS, learn a language, ...) and then define some clear goal. It's good to have a project, but it's also good to have a reachable goal in a small amount of time. Small successes are good for your morale.
That IS really a bad conclusion. My personal opinion here is that the problem domain is so wide and generally hard that nobody has gotten it "right" yet, thus people try to solve it over and over again, from different angles and under different assumptions.That of course doesn't mean you shouldn't try. Just be warned that many smart people were there before you, so you should do your homework.
What could give you a good overview in a less technical manner is The Git Parable.
It is a nice abstraction on the principles of git, but it gives a very good understanding what a VCS should be able to perform. All things beyond this are rather "low-level" decisions.
A good delta algorithm, good compression and network efficiency.
A simple one is doable by one person for a learning opportunity. One issue you might consider is how to efficiently store plain text deltas. A very popular delta format is the one from RCS (used by many version control programs). You might want to study it to get ideas.
To write a proof of concept, you probably could pull it off, implementing or borrowing the tools Alan mentions.
IMHO, the most important aspect of a VCS is ease-of-use. This sounds like an odd statement, but when you think about it, hard drive space is one of the easiest IT commodities to scale horizontally, so bad compression or even real sloppy deltas are going to be tolerated. The main reason people demand improvement in versioning systems is to do common tasks more intuitively or to support more features that droves of people eventually demand but that weren't obvious before release. And since versioning tools tend to be monolithic and thoroughly integrated at a company, the cost to switch is high, and it may not be possible to support a new feature without breaking an existing repo.
The very minimal necessary prerequisite is an exhaustive and accurate test suite. Nobody (including you) will want to use your new system unless you can demonstrate that it works, reliably and completely error free.
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The organization that I currently work for seems to be heading in the direction of dictating to software developers which tools, languages, frameworks, etc. must be used. However, nobody has convinced me that this is a good thing. The main argument I have heard is that it will make training easier. But, after developing software for over 10 years, I've never relied on training to learn how to use an IDE, programming language, or anything else; so I just can't relate.
With the rapid speed at which technology evolves, and the s-l-o-w-n-e-s-s at which I know the standards will adapt, I am concerned that my customers will have requirements that I won't be able to easily implement or won't be able to implement as efficiently as I should. For example, if there is a UI requirement for an auto-complete feature in a web app, and no API has been approved for this yet, I would need to implement auto-complete myself as opposed to using one of the many APIs that provide it out of the box.
A more radical example is if my customers wanted to have Google Wave features. In that case I would want the flexibility of configuring my development environment (including the IDE) and selecting appropriate frameworks (ex: GWT) to use.
Please provide feedback on whether or not you think that software developer tools, languages, etc should be standardized and a few points to support your argument.
There is a lot of benefit for standardization. My organization has fairly set standards on what technology we will use. We realize strong benefits in the following areas ...
Hiring. It is easy to describe what technologies we are looking for and make sure our recruiters are looking for the right people.
License/Software costs. I can buy enterprise licenses easily. It gives me the opportunity to keep costs down by letting me spend more with a smaller number of vendors and thus get more leverage.
Consistency of delivery. Our teams have a very good idea of what projects will take to build, rollout and maintain because they have done it with success before (and they know the pitfalls too).
Agility. I can have one team take over for another or one individual take over for another more easily because of standardization.
Quality. We have peer reviews across teams as well as QA across teams.
Without a consistent use of a technology stack, tools, languages and frameworks, these types of benefits would be more difficult to realize. I am not closed off to new technologies, but there has to be a concrete reason beyond "what if I want to ..."
A major issue with standardization is that once standards are out there, they get stamped in concrete and are difficult to change. This is why our corporate IT environment is stuck on IE 6, and the best change control system we have access to is CVS. Given this situation, some developers break the rules, and some find jobs at more innovative companies.
You have a mixed bag here.
I wouldn't standardize on IDEs, because every developer works differently. Those who are insanely proficient in emacs may see their performance suffer if forced to use Visual Studio. I optimize my Visual Studio experience with a 30" monitor and find it incredibly productive.
However, standardizing on some tools, such as SCons or make or something to build products is perfectly reasonable.
Banning some libraries and having a process where new libraries are either approved or not is also very reasonable. I know lots of companies that ban boost, or JQuery, or ban open source libraries in general, etc. And they had good reasons for doing it. I know I got fairly upset when an intern incorporated some random "security" library he found on the internet without running it by anyone.
In the end every company is different. You have to be standardized enough to avoid serious complications and issues as people come and go, or as new products are formed and organizational structures change. But you have to be flexible enough to avoid re-inventing every wheel you need.
The important thing is to have clear reasons for adopting a certain tool or banning some other tool or library. You can't just have management dictate that thou shalt use this and not that without consulting the engineering team and making the decision for good reasons. And once decisions are made those reasons should be written down and clearly communicated.
And also, if, in the end, your favorite tool or library isn't adopted, please don't whine about it. Be adaptable and do your job, or find a new one that makes you happier.
I once worked for a manager who felt the need to innovate at every level of his software development operation. Every development tool had to be cutting edge (preferably in beta). Many of the tools he asked us to use didn't have good documentation, and training was not available. Ultimately, most of the technology we tried simply didn't work. We wasted a lot of time churning through new technologies, only to dump them when it became clear we couldn't make progress.
I tried to make the case that innovation is perfect in the area where your value proposition lies. Innovation can also be used judiciously where standard techniques fail. But for most mundane tasks, using tried-and-true tools and methods should be the default. Less risk, less cost, less management attention needed. So you can focus time and energy on the areas where innovation has the most benefit.
So I think standardization has an important role. But blindly saying everything must be standard is just as sure to fail as my manager who thought everything must be innovative.
The number one argument in favor of standardization is that it maximizes the ability of the organization as a whole to use a common body of knowledge. Don't know how custom web controls are built in ASP.NET/C#? Ask Bill down the hall who has the knowledge. If you use different tools, such organizational wisdom is cut off at the knees. While it is not good to be restricted to a least common denominator (and hopefully your management will realize this) you should not overlook the benefits of shared experience!
UPDATE: I do not agree that innovation and standardization are polar opposites. Indeed, would we have nearly the level of web innovation if we still had the mishmash of networking standards characteristic of the 1980s? No we would not. Of course, we might have more innovation on new low-level networking protocols but is that really worth it? In its place, we've had an explosion of creativity within the bounds of TCP/IP and the Web standards (http, html, etc.)
The trick is knowing how to standardize without using it as an argument for closing down all new exploration. For example, we use only ASP.NET/C#/SQL Server in my company but I'm perfectly open to the use of new tools within this framework (we recently adopted the DevExpress reporting package, for example, supplanting the earlier standard).
Standardization is a must for a productive development team. However that doesn't mean that you can't revist the standards from time to time to adjust them to new technologies and trends.
Whether you develop operations software for internal clients, or products for external clients, there is no compelling reason not to standardize. You certainly did not give one.
Had you seen how companies are struggling with holding heterogenous products together that have been maintained for 10 years or more, and are now a conglomerate of various technologies that developers at some point thought made sense, you would not have asked this question.
From the top of my head, I could name at least 2 well-known software companies that will be driven out of business because their cost of maintenance has become so high that they can no longer compete (but I won't).
I think the misconception here is that suppressing individualism would supress innovation. That is simply not true. It is poor technical leadership that suppresses innovation.
One unpleasant consequence of standardization is that it tends to stifle innovation.
Innovation is scary. It involves cost and risk.
Standardization is not scary. It reduces cost and risk in the short term. Until your competitors have created a game-changing innovation. Then standardization is very costly.
It depends on the organization I think. One like Microsoft, yes, there should be a bit of a standard. A small business with one IT department, no. A larger business with several offices around the world ... maybe.
it all depends :-P
Assuming the organization has a broad suite of enterprise applications to manage, I'd say no for the following reasons, though I may be taking the message of everything being the same a bit too literally:
Compromise on using best-of-breed for systems, e.g. if all the databases are to be MS-SQL then any Oracle DB solution is thrown out. This would also apply to the fact that everyone using an IDE has to use the same one whether they be doing Data Warehouse report development, web applications, console applications or winForms. I'm thinking of systems like ERP, CRM, SCM, CMS, SSO and various other TLAs, FLAs, and SLAs. (LA = Letter acronyms for a decoding hint if you need it)
Upgrading by committee is another interesting issue. Where if each team can choose their tools and have one person that decides it is to upgrade things, e.g. start using Visual Studio 2008 instead of Visual Studio 2005, now have to determine at what threshold is it worth it to upgrade everyone simultaneously which may be a big headache if there are more than a few developers. For example, over the past 10 years when would there be IDE changes, framework changes, etc.?
Exceptions to the standards. Could a contractor bring in something not used in the organization if they believe it helps them build better software, e.g. Resharper or other add-ons that some contractors believe are very worthwhile that the organization doesn't want to spend the money to get? What about legacy systems that may make the standard become a bit unwieldy, e.g. this was built in ASP.Net 1.1 and so everyone has to have VS 2003 installed even if most will never use it?
Just my thoughts on this.
There are several good reasons to standardize.
First, it allows the enterprise better organizational flexibility, if everybody is more or less familiar with the same things. It also allows people to help each other better. I can't help with problems in the ASP.NET stuff, and there's not all that many people who can help me on the C++ side.
Second, it reduces support problems and expenses. Oracle and SQL Server are both decent products, but using both for similar functions is only going to cause problems. Not to mention that I've been in shops using several widely different platforms to do similar things, and it wasn't fun.
Third, there are some things that just have to be standardized. We couldn't operate half with VS 2005 and VS 2008, since we keep project files under source control. We had to pick a time and convert over.
Fourth, in some businesses, it simplifies the regulatory problems. I don't know what business you're in. I work at a place where we can get away with making mistakes right now, but I've also contracted at a bank and a utility, where it's necessary to be able to show auditors that everything is going in a standard way.
Fifth, it can simplify procurement, if you're dealing with software that costs money.
This doesn't particularly limit us, since if there's something we need that isn't standardized on we just go ahead and get it or do it.
If you want to make a business case against standardization, you'll need to have a business-related argument. Your argument seems to be that you won't be able to implement features the user wants, and that is a consideration. Got another argument?
There's nothing wrong with standardizing on an IDE that is rich enough to be configured for individual developers.
However, do make sure that you don't prevent individual developers from using additional tools, as long as the tools are licensed and that the use of the tool by one developer doesn't require all other developers to use it.
For instance, I happen to use NORMA to help me design databases. The output is SQL Server DDL (or anything else I want). I can make the DDL part of the project without making my NORMA source part of it. Later developers do not need to use NORMA to work on the project.
On the other hand, if I decided to use the Configuration Section Designer to create configuration sections, then future developers would also have to use it. A decision would need to be made about whether to use that tool.
The company I work for uses C#, ASP.NET, JavaScript and generates HTML. The advantages over and above those mentioned above are that there is a perception of improved velocity for maintenance and adaptive changes. The disadvantages include generating some boredom for people who are technically savvy (geeky) and prefer to use a mix and match of languages, depending on what they fancy is better suited, or for 'performance reasons'.
Technical and personal supervision is always good to have when you are developing as fast as you can to meet tight deadlines and competing in a highly saturated market for web development.
Where I work, people don't like to write specs. (Boy, does anyone?) So they don't do it, unless forced by their bosses. If they are forced to write them, they make them as short as possible. (By the way, they also includes me.)
This results in specifications like
This software logs the time between event A and B to the event log
Name and path of parameter X are set in a configuration file in ini format.
The software is active without a user needing to log on to the computer (implementation as a Windows service)
This example is taken from a very small project, and it worked out pretty well, But I don't think that it will suffice for anything more complex. I did not specify OS/hardware requirements because this is in-house development and we have company or department standards covering those.
So my question is:
What do you consider the absolute minimum level of detail in a functional specification for any non-trivial software?
IMHO the important thing about Functional Specs (and all other formal methods/tools for software development and project planning (Yourdon, SSADM, PRINCE2, UML, etc) is that they encourage good practice by making you think along common lines.They don't guarantee success but they encourage success by formalising good practice
So the fact that FSs are created is a good thing, even if perhaps they could be better. Some planning and preparation is better than none at all - which is what a lot developers do.
What should ideally go into a FS? As much as is necessary and as little as possible. Just because some functional specs cover X, Y & Z doesn't mean yours should. If you become too prescriptive, you will add unnecessary bureaucracy to simpler projects; correspondingly, for complicated projects, a prescriptive approach might encourage the developer to stop short of the level of detail that they really ought to go to.
Joel on Software wrote a cracking article on specifications.
You can find it here
Specification Discussion
I'm at a point in my freelance career where I've developed several web applications for small to medium sized businesses that support things such as project management, booking/reservations, and email management.
I like the work but find that eventually my applications get to a point where the overhear for maintenance is very high. I look back at code I wrote 6 months ago and find I have to spend a while just relearning how I originally coded it before I can make a fix or feature additions. I do try to practice using frameworks (I've used Zend Framework before, and am considering Django for my next project)
What techniques or strategies do you use to plan out an application that is capable of handling a lot of users without breaking and still keeping the code clean enough to maintain easily?
If anyone has any books or articles they could recommend, that would be greatly appreciated as well.
Although there are certainly good articles on that topic, none of them is a substitute of real-world experience.
Maintainability is nothing you can plan straight ahead, except on very small projects. It is something you need to take care of during the whole project. In fact, creating loads of classes and infrastructure code in advance can produce code which is even harder to understand than naive spaghetti code.
So my advise is to clean up your existing projects, by continuously refactoring them. Look at the parts which were a pain to change, and strive for simpler solutions that are easier to understand and to adjust. If the code is even too bad for that, consider rewriting it from scratch.
Don't start new projects and expect them to succeed, just because your read some more articles or used a new framework. Instead, identify the failures of your existing projects and fix their specific problems. Whenever you need to change your code, ask yourself how to restructure it to support similar changes in the future. This is what you need to do anyway, because there will be similar changes in the future.
By doing those refactorings you'll stumble across various specific questions you can ask and read articles about. That way you'll learn more than by just asking general questions and reading general articles about maintenance and frameworks.
Start cleaning up your code today. Don't defer it to your future projects.
(The same is true for documentation. Everyone's first docs were very bad. After several months they turn out to be too verbose and filled with unimportant stuff. So complement the documentation with solutions to the problems you really had, because chances are good that next year you'll be confronted with a similar problem. Those experiences will improve your writing style more than any "how to write good" style guide.)
I'd honestly recommend looking at Martin Fowlers Patterns of Enterprise Application Architecture. It discusses a lot of ways to make your application more organized and maintainable. In addition, I would recommend using unit testing to give you better comprehension of your code. Kent Beck's book on Test Driven Development is a great resource for learning how to address change to your code through unit tests.
To improve the maintainability you could:
If you are the sole developer then adopt a coding style and stick to it. That will give you confidence later when navigating through your own code about things you could have possibly done and the things that you absolutely wouldn't. Being confident where to look and what to look for and what not to look for will save you a lot of time.
Always take time to bring documentation up to date. Include the task into development plan; include that time into the plan as part any of change or new feature.
Keep documentation balanced: some high level diagrams, meaningful comments. Best comments tell that cannot be read from the code itself. Like business reasons or "whys" behind certain chunks of code.
Include into the plan the effort to keep code structure, folder names, namespaces, object, variable and routine names up to date and reflective of what they actually do. This will go a long way in improving maintainability. Always call a spade "spade". Avoid large chunks of code, structure it by means available within your language of choice, give chunks meaningful names.
Low coupling and high coherency. Make sure you up to date with techniques of achieving these: design by contract, dependency injection, aspects, design patterns etc.
From task management point of view you should estimate more time and charge higher rate for non-continuous pieces of work. Do not hesitate to make customer aware that you need extra time to do small non-continuous changes spread over time as opposed to bigger continuous projects and ongoing maintenance since the administration and analysis overhead is greater (you need to manage and analyse each change including impact on the existing system separately). One benefit your customer is going to get is greater life expectancy of the system. The other is accurate documentation that will preserve their option to seek someone else's help should they decide to do so. Both protect customer investment and are strong selling points.
Use source control if you don't do that already
Keep a detailed log of everything done for the customer plus any important communication (a simple computer or paper based CMS). Refresh your memory before each assignment.
Keep a log of issues left open, ideas, suggestions per customer; again refresh your memory before beginning an assignment.
Plan ahead how the post-implementation support is going to be conducted, discuss with the customer. Make your systems are easy to maintain. Plan for parameterisation, monitoring tools, in-build sanity checks. Sell post-implementation support to customer as part of the initial contract.
Expand by hiring, even if you need someone just to provide that post-implementation support, do the admin bits.
Recommended reading:
"Code Complete" by Steve Mcconnell
Anything on design patterns are included into the list of recommended reading.
The most important advice I can give having helped grow an old web application into an extremely high available, high demand web application is to encapsulate everything. - in particular
Use good MVC principles and frameworks to separate your view layer from your business logic and data model.
Use a robust persistance layer to not couple your business logic to your data model
Plan for statelessness and asynchronous behaviour.
Here is an excellent article on how eBay tackles these problems
http://www.infoq.com/articles/ebay-scalability-best-practices
Use a framework / MVC system. The more organised and centralized your code is the better.
Try using Memcache. PHP has a built in extension for it, it takes about ten minutes to set up and another twenty to put in your application. You can cache whatever you want to it - I cache all my database records in it - for every application. It does wanders.
I would recommend using a source control system such as Subversion if you aren't already.
You should consider maybe using SharePoint. It's an environment that is already designed to do all you have mentioned, and has many other features you maybe haven't thought about (but maybe you will need in the future :-) )
Here's some information from the official site.
There are 2 different SharePoint environments you can use: Windows Sharepoint Services (WSS) or Microsoft Office Sharepoint Server (MOSS). WSS is free and ships with Windows Server 2003, while MOSS isn't free, but has much more features and covers almost all you enterprise's needs.