Is OO relevant in mobile application programming using J2ME? - java-me

Given that applications for mobile devices are expected to be small and simple,
often with heavy computation off-loaded to a web-service.
Is OO, over and above frameworks such as J2ME, relevant to mobile application programming ?
Would application specific frameworks, say for client specific customization, not be an avoidable overhead, particularly when an existing framework (J2ME) itself is already available?
Are there any J2ME frameworks available e.g. Struts etc?

Object Oriented programing, in and of itself, does not imply any specific overhead. It's merely a methodology. You can create programs which use an OO design methodology which are still fast and simple, just as you can create non-OO programs which are slow and kludgy.

Sure, use OO (it is Java after all), but you have to be a little bit more careful, as space and memory are limited for J2ME. A judicious uses of classes is good, but don't go overboard with those things that have classes that create factories that generate other things, etc... etc... That's actually something I like about J2ME: you can't go overboard with the "architecture astronaut" stuff.

Well J2ME is Java and therefore is OO. You can write code in a procedural way in OO land, but that isn't really the point now is it? If you don't want to do OO switch to Python.

As Mr. Knuth said it, "premature optimization is the root of all evil".
Similarly, just because you encounter a new platform, J2ME in this case, it makes no sense to forget everything about how to write good software and go back to the global-everything-procedural-everything-orgy.
Sure, use your brain, and don't do things that you wouldn't do on the desktop (e.g. java memleaks by spawning craploads of objects and forgetting to get rid of refs to them, or, just as bad, simply spawning loads of objects indiscriminately). Factories creating factories creating factories might however not be as stupid as it sounds, especially if the reason you're doing that is because it helps you write lots of unit tests. (And yes, do write unit tests on J2ME!)
And responding to David N. Welton a few answers up, "architecture astronaut", or over-engineering, doesn't have to ever happen if you go with the good old iterative approach -- don't make things more complex until it measurably simplifies your life.
So to sum up, my feeling is that everybody is just using the "memory and space constraints" on J2ME and Blackberry to toss the good sense out the window and write crappy, un-navigable software. I assure you that if you go the iterative way and test your app every so often you will notice when the performance becomes unsatisfactory and take appropriate measures at that point. And the chances are, the performance issue will be due to you doing something stupid and not due to the abstractions.
Disclaimer: if you ARE reading this from 1999, writing for CLDC 1.0 with 1KB of mem, or for a JavaCard, disregard all of the above. If however you're running on any feature-phone of today, you're in luck!

Related

Does this language have its niche | future?

I am working on a new language, targeted for web development, embeding into applications, distributed applications, high-reliability software (but this is for distant future).
Also, it's target to reduce development expenses in long term - more time to write safer code and less support later. And finally, it enforces many things that real teams have to enforce - like one crossplatform IDE, one codestyle, one web framework.
In short, the key syntax/language features are:
Open source, non-restrictive licensing. Surely crossplatform.
Tastes like C++ but simpler, Pythonic syntax with strict & static type checking. Easier to learn, no multiple inheritance and other things which nobody know anyway :-)
LLVM bytecode/compilation backend gives near-C speed.
Is has both garbage collection & explicit object destruction.
Real OS threads, native support of multicore computers. Multithreading is part of language, not a library.
Types have the same width on any platform. int(32), long(64) e.t.c
Built in post and preconditions, asserts, tiny unit tests. You write a method - you can write all these things in 1 place, so you have related things in one place. If you worry that your class sourcecode will be bloated with this - it's IDEs work to hide what you don't need now.
Java-like exception handling (i.e. you have to handle all exceptions)
I guess I'll leave web & cluster features for now...
What you think? Are there any existing similar languages which I missed?
To summarize: You language has no real selling points. It just does what a dozen other languages already did, with syntax and semantics just slightly off, depending on where the programmer comes from. This may be a good thing, as it makes the language easier to adapt, but you also have to convince people to trouble to switch. All this stuff has to be built and debugged and documented again, tools have to be programmed, people have to learn it and convince their pointy-haired bosses to use it, etc. "So it's language X with a few features from Y and nicer syntax? But it won't make my application's code 15% shorter and cleaner, it won't free me from boilerplate X, etc - and it won't work with my IDE." The last one is important. Tools matter. If there are no good tools for a language, few people will shy away, rightfully so.
And finally, it enforces many things that real teams have to enforce - like one crossplatform IDE, one codestyle, one web framework.
Sounds like a downside! How does the language "enforce one X"? How do you convince programmers this coding style is the one true style? Why shouldn't somebody go and replace the dog slow, hardly maintained, severly limited IDE you "enforce" with something better? How could one web framework possibly fit all applications? Programmers rarely like to be forced into X, and they are sometimes right.
Also, you language will have to talk to others. So you have ready-made standard solutions for multithreading and web development in mind? Maybe you should start with a FFI instead. Python can use extensions written in C or C++, use dynamic libraries through ctypes, and with Cython it's amazingly simple to wrap any given C library with a Python interface. Do you have any idea how many important libraries are written in C? Unless your language can use these, people can hardly get (real-world) stuff done with it. Just think of GUI. Most mayor GUI toolkits are C or C++. And Java has hundreds of libraries (the other JVM languages profit much from Java interop) for many many purposes.
Finally, on performance: LLVM can give you native code generation, which is a huge plus (performance-wise, but also because the result is standalone), but the LLVM optimizers are limited, too. Don't expect it to beat C. Especially not hand-tuned C compiled via icc on Intel CPUs ;)
"Are there any existing similar
languages which I missed?"
D? Compared to your features:
The compiler has a dual license - GPL and Artistic
See example code here.
LDC targets LLVM. Support for D version 2 is under development.
Built-in garbage collection or explicit memory management.
core.thread
Types
Unit tests / Pre and Post Contracts
try/catch/finally exception handling plus scope guarantees
Responding to a few of your points individually (I've omitted what I consider either unimportant or good):
targeted for web development
Most people use php. Not because it's the best language available, that's for sure.
embeding into applications
Lua.
distributed applications, high-reliability software (but this is for distant future).
Have you carefully studied Erlang, both its design and its reference implementation?
it enforces many things that real teams have to enforce - like one crossplatform IDE, one codestyle, one web framework.
If your language becomes successful, people will make other IDEs, other code styles, other web frameworks.
Multithreading is part of language, not a library.
Really good languages for multithreading forbid side effects inside threads. Yes, in practice that pretty much means Erlang only.
Types have the same width on any platform. int(32), long(64) e.t.c
Sigh... There's only one reasonable width for integers outside of machine-level languages like C: infinite.
Designing your own language will undoubtedly teach you someting. But designing a good language is like designing a good cryptosystem: lots of amateurs try, but it takes an expert to do it well.
I suggest you read some of Norman Ramsey's answers here on programming language design, starting with this thread.
Given your interest in distributed applications, knowing Erlang is a must. As for sequential programming, the minimum is one imperative language and one functional language (ideally both Lisp/Scheme and Haskell, but F# is a good start). I also recommend knowing at least one high-level language that doesn't have objects, just so you understand that not having objects can often make the programmer's life easier (because objects are complex).
As for what could drive other people to learn your language... Good tools/libraries/frameworks can't hurt (FORTRAN, php), and a big company setting the example can't hurt (Java, C#). Good design doesn't seem to be much of a factor (a ha-ha-only-serious joke has it that what makes a language successful is using {braces} to delimit blocks: C, C++, Java, C#, php)...
What you've given us is a list of features, with no coherent philosophy, or explanation as to how they will work together. None of the features are unique. At best, you're offering incremental improvements over what's already there. I'd expect there's already languages kicking around with what you've said, it's just that they're still fairly obscure, because they didn't make it.
Languages have inertia. People have to learn new languages, and sometimes new tools. They need incentive to do so, and 20% improvement in a few features doesn't cut it.
What you need, at a minimum, is a killer app and a form of elevator pitch. (The "elevator pitch" is what you tell the higher-ups about your project when you're in the elevator with them, in current US business parlance.) You need to have your language be obviously worth learning for some purpose, and you need to be able to tell people why it's worth learning before they think "just another language by somebody who wanted to write a language" and go away.
You need to form a language community. That community needs to have some localization at first: people who work in X big company, people who want to do Y, whatever. Decide on what that community is likely to be, and come up with one big reason to switch and some reasons to believe that your language can deliver what it promises.
No.
Every buzzword you have included in your feature list is an enormous amount of work to be spec'd, implemented, documented, and tested.
How many people will be actively developing the language? I guess the web is full of failed programming language projects. (Same is true for non-mainstream OSes)
Have a look at what .Net/Visual Studio or Java/Eclipse have accomplished. That's 1000s of years of specification, development, tests, documentation, feedback, bug fixes, service packs.
During my last job I heard about somebody who wrote his own programming framework, because it was "better". The resulting program code (both in the framework and in the applications) is certainly unmaintainable once the original programmer quits, or is "hit by a bus", as the saying goes.
As the list sounds like Java++ or Mono++, you'd probably be more successful in engaging in an existing project, even if it won't have your name tag on it.
Perhaps you missed one key term. Performance.
In any case, unless this new language has some really out-of-this-world features(ex: 100% increase in performance over other web development languages), I think it will be yet another fish in the pond.
Currently I'm responsible for maintaining a framework developed/owned by my company. It's a nightmare. Unless there is a mainstream community, working on this full time, it's really an elephant. I do not appreciate my company's decision to develop its own framework(because it's supposed to be "faster") day 'n night.
The language tastes good in my opinion, I don't want use java for a simple website but I would like to have types and things like that. ASP .NET is a problem because of licensing and I can't afford those licenses for a single website... Also features looks good
Remember a lot of operator overloading: I think is the biggest thing that PHP is actually missing. It allows classes to behave much more like basic types :)
When you have something to test I'll love to help you with it! Thanks
Well, if you have to reinvent the wheel, you can go for it :)
I am not going to give you any examples of languages or language features, but I will give you one advice instead:
Supporting framework is what is the most important thing. People will tend to love it or hate it, depending on how easy is to write good code that get job done. Therefore, please do usability test before releasing it. I mean ask several people how they will do certain task and create API accordingly. Then test beta API on other coders and listen carefully to their comments.
Regards and good luck :)
There's always space for another programming language. Apart from getting the design right, I think the biggest problem is coming across as just another wannabe language. So you may want to look at your marketing, you need a big sponsor who can integrate your language into their products, or you need to generate a buzz around it, easiest way is astroturfing. Good luck.
http://en.wikipedia.org/wiki/List_of_programming_languages
NB the names G and G++ aren't taken. Oh and watch out for the patent trolls.
Edit
Oops G / G++ are taken... still there are plenty more letters left.
This sounds more like a "systems" language rather than a "web development language". The major languages in this category (other than C++/C) are D and Go.
My advice to you would be to not start from scratch but examine the possibility of creating tools or libraries for those languages, and seeing just how far you can push them.

Why did you decide "against" using Erlang?

Locked. This question and its answers are locked because the question is off-topic but has historical significance. It is not currently accepting new answers or interactions.
Have you actually "tried" (means programmed in, not just read an article on it) Erlang and decided against it for a project? If so, why? Also, if you have opted to go back to your old language, or to use another functional language like F#, Haskell, Clojure, Scala, or something else then this counts too, and state why.
I returned to Haskell for my personal projects from Erlang for the simple virtue of Haskell's amazing type system. Erlang gives you a ton of tools to handle when things go wrong. Haskell gives you tools to keep you from going wrong in the first place.
When working in a language with a strong type system you are effectively proving free theorems about your code every time you compile.
You also get a bunch of overloading sugar from Haskell's typeclass machinery, but that is largely secondary to me -- even if it does allow me to express a number of abstractions that would be terribly verbose or non-idiomatic and unusable in Erlang (e.g. Haskell's category-extras).
I love Erlang, I love its channels and its effortless scalability. I turn to it when these are the things I need. Haskell isn't a panacea. I give up a better operational understanding of space consumption. I give up the magical one pass garbage collector. I give up OTP patterns and all that effortless scalability.
But its hard for me to give up the security blanket that, as is commonly said, in Haskell, if it typechecks, it is probably correct.
We use Haskell, OCaml and (now) F# so for us it has nothing to do with lack of C-like syntax. Rather we skip Erlang because:
It's dynamically typed (we're fans of Haskell's type system)
Doesn't provide a 'real' string type (I understand why, but it's annoying that this hasn't been corrected at the language level yet)
Tends to have poor (incomplete or unmaintained) database drivers
It isn't batteries included and doesn't appear to have a community working on correcting this. If it does, it isn't highly visible. Haskell at least has Hackage, and I'd guess that's what has us choosing that language over any other. In Windows environments F# is about to have the ultimate advantage here.
There are probably other reasons I can't think of right now, but these are the major points.
The best reason to avoid Erlang is when you cannot commit to the functional way of programming.
I read an anti-Erlang blog rant a few weeks ago, and one of the author's criticisms of Erlang is that he couldn't figure out how to make a function return a different value each time he called it with the same arguments. What he really hadn't figured out is that Erlang is that way on purpose. That's how Erlang manages to run so well on multiple processors without explicit locking. Purely functional programming is side-effect-free programming. You can arm-twist Erlang into working like our ranting blogger wanted, adding side effects, but in doing so you throw away the value Erlang offers.
Pure functional programming is not the only right way to program. Not everything needs to be mathematically rigorous. If you determine your application would be best written in a language that misuses the term "function", better cross Erlang off your list.
I have used Erlang in a few project already. I often use it for restful services. Where I don't use it however is for complex front end web applications where tools like Ruby on Rails are far better. But for the powerbroker behind the scenes I know of no better tool than Erlang.
I also use a few applications written in Erlang. I use CouchDB and RabbitMQ a bit and I have set up a few EJabberd servers. These applications are the most powerful, easiest and flexible tools in their field.
Not wanting to use Erlang because it does not use JVM is in my mind pretty silly. JVM is not some magical tool that is the best in doing everything in the world. In my mind the ability to choose from an arsenal of different tools and not being stuck in a single language or framework is what separates experts from code monkeys.
PS: After reading my comment back in context I noticed it looked like I was calling oxbow_lakes a code monkey. I really wasn't and apologize if he took it like that. I was generalizing about types of programmers and I would never call an individual such a negative name based on one comment by him. He is probably a good programmer even though I encourage him to not make the JVM some sort of a deal breaker.
Whilst I haven't, others on the internet have, e.g.
We investigated the relative merits of
C++ and Erlang in the implementation
of a parallel acoustic ray tracing
algorithm for the U.S. Navy. We found
a much smaller learning curve and
better debugging environment for
parallel Erlang than for
pthreads-based C++ programming. Our
C++ implementation outperformed the
Erlang program by at least 12x.
Attempts to use Erlang on the IBM Cell
BE microprocessor were frustrated by
Erlang's memory footprint. (Source)
And something closer to my heart, which I remember reading back in the aftermath of the ICFP contest:
The coding was very straightforward,
translating pseudocode into C++. I
could have used Java or C#, but I'm at
the point where programming at a high
level in C++ is just as easy, and I
wanted to retain the option of quickly
dropping down into some low-level
bit-twiddling if it came down to it.
Erlang is my other favorite language
for hacking around in, but was worried
about running into some performance
problem that I couldn't extricate
myself from. (Source)
For me, the fact that Erlang is dynamically typed is something that makes me wary. Although I do use dynamically typed languages because some of them are just so very problem-oriented (take Python, I solve a lot of problems with it), I wish they were statically typed instead.
That said, I actually intended to give Erlang a try for some time, and I’ve just started downloading the source. So your “question” achieved something after all. ;-)
I know Erlang since university, but have never used it in my own projects so far. Mainly because I'm mostly developing desktop applications, and Erlang is not a good language for making nice GUIs. But I will soon implement a server application, and I will give Erlang a try, because that's what it's good for. But I'm worring that I need more librarys, so maybe I'll try with Java instead.
A number of reasons:
Because it looks alien from anyone used to the C family of languages
Because I wanted to be able to run on the Java Virtual Machine to take advantage of tools I knew and understood (like JConsole) and the years of effort which have gone into JIT and GC.
Because I didn't want to have to rewrite all the (Java) libraries I've built up over the years.
Because I have no idea about the Erlang "ecosystem" (database access, configuration, build etc).
Basically I am familiar with Java, its platform and ecosystem and I have invested much effort into building stuff which runs on the JVM. It was easier by far to move to scala
I Decided against using Erlang for my project that was going to be run with a lot of shared data on a single multi-processor system and went with Clojure becuase Clojure really gets shared-memory-concurrency. When I have worked on distributed data storage systems Erlang was a great fit because Erlang really shines at distributed message passing systems. I compare the project to the best feature in the language and choose accordingly
Used it for a message gateway for a proprietary, multi-layered, binary protocol. OTP patterns for servers and relationships between services as well as binary pattern matching made the development process very easy. For such a use case I'd probably favor Erlang over other languages again.
The JVM is not a tool, it is a platform. Although I am all in favour of choosing the best tool for the job the platform is mostly already determined. Unless I am developing something standalone, from scratch and without the desire to reuse any existing code/library (three aspects that are unlikely in isolation already) I may be free to choose the platform.
I do use multiple tools and languages but I mainly targetg the JVM platform. That precludes Erlang for most if not all of my projects, as interesting as some of it concepts are.
Silvio
While I liked many design aspects of the Erlang runtime and the OTP platform, I found it to be a pretty annoying program language to develop in. The commas and periods are totally lame, and often require re-writing the last character of many lines of code just to change one line. Also, some operations that are simple in Ruby or Clojure are tedious in Erlang, for example string handling.
For distributed systems relying on a shared database the Mnesia system is really powerful and probably a good option, but I program in a language to learn and to have fun, and Erlang's annoying factor started to outweigh the fun factor once I had gotten past the basic bank account tutorials and started writing plugins for an XMPP server.
I love Erlang from the concurrency standpoint. Erlang really did concurrency right. I didn't end up using erlang primarily because of syntax.
I'm not a functional programmer by trade. I generally use C++, so I'm covet my ability to switch between styles (OOP, imperative, meta, etc). It felt like Erlang was forcing me to worship the sacred cow of immutable-data.
I love it's approach to concurrency, simple, beautiful, scalable, powerful. But the whole time I was programming in Erlang I kept thinking, man I'd much prefer a subset of Java that disallowed data sharing between thread and used Erlangs concurrency model. I though Java would have the best bet of restricting the language the feature set compatible with Erlang's processes and channels.
Just recently I found that the D Programing language offers Erlang style concurrency with familiar c style syntax and multi-paradigm language. I haven't tried anything massively concurrent with D yet, so I can't say if it's a perfect translation.
So professionally I use C++ but do my best to model massively concurrent applications as I would in Erlang. At some point I'd like to give D's concurrency tools a real test drive.
I am not going to even look at Erlang.
Two blog posts nailed it for me:
Erlang machinery walks the whole list to figure out whether they have a message to process, and the only way to get message means walking the whole list (I suspect that filtering messages by pid also involves walking the whole message list)
http://www.lshift.net/blog/2010/02/28/memory-matters-even-in-erlang
There are no miracles, indeed, Erlang does not provide too many services to deal with unavoidable overloads - e.g. it is still left to the application programmer to deal checking for available space in the message queue (supposedly by walking the queue to figure out the current length and I suppose there are no built-in mechanisms to ensure some fairness between senders).
erlang - how to limit message queue or emulate it?
Both (1) and (2) are way below naive on my book, and I am sure there are more software "gems" of similar nature sitting inside Erlang machinery.
So, no Erlang for me.
It seems that once you have to deal with a large system that requires high performance under overload C++ + Boost is still the only game in town.
I am going to look at D next.
I wanted to use Erlang for a project, because of it's amazing scalability with number of CPU'S. (We use other languages and occasionally hit the wall, leaving us with having to tweak the app)
The problem was that we must deliver our application on several platforms: Linux, Solaris and AIX, and unfortunately there is no Erlang install for AIX at the moment.
Being a small operation precludes the effort in porting and maintaining an AIX version of Erlang, and asking our customers to use Linux for part of our application is a no go.
I am still hoping that an AIX Erlang will arrive so we can use it.

Successful Non-programmer, 5GL, Visual, 0 Source Code or Similar Tools?

Can anyone give me an example of successful non-programmer, 5GL (not that I am sure what they are!), visual, 0 source code or similar tools that business users or analysts can use to create applications?
I don’t believe there are and I would like to be proven wrong.
At the company that I work at, we have developed in-house MVC that we use to develop web applications. It is basically a reduced state-machine written in XML (à la Spring WebFlow) for controller and a simple template based engine for presentation. Some of the benefits:
dynamic nature: no need to recompile to see the changes
reduced “semantic load”: basically, actions in controller know only “If”. Therefore, it is easy to train someone to develop apps.
The current trend in the company (or at least at management level) is to try to produce tools for the platform that require 0 source code, are visual etc. It has a good effect on clients (or at least at management level) since:
they can be convinced that this way they will need no programmers or at least will be able to hire end-of-the-lather programmers that cost much less than typical programmers.
It appears that there is a reduced risk involved, since the tool limits the implementer or user (just don’t use the word programmer!) in what he can do, so there is a less chance that he can introduce error
It appears to simplify the whole problem since there seems to be no programming involved (notoriously complex). Since applications load dynamically, there is less complexity then typically associated with J2EE lifecycle: compile, package, deploy etc.
I am personally skeptic that something like this can be achieved. Solution we have today has a number of problems:
Implementers write JavaScript code to enrich pages (could be solved by developing widgets). Albeit client-side, still a code that can become very complex and result in some difficult bugs.
There is already a visual tool, but implementers prefer editing XML since it is quicker and easier. For comparison, I guess not many use Eclipse Spring WebFlow plug-in to edit flow XML.
There is a very poor reuse in the solution (based on copy-paste of XML). This hampers productivity and some other aspects, like fostering business knowledge.
There have been numerous performance and other issues based on incorrect use of the tools. No matter how reduced the playfield, there is always space for error.
While the platform is probably more productive than Struts, I doubt it is more productive than today’s RAD web frameworks like RoR or Grails.
Verbosity
Historically, there have been numerous failures in this direction. The idea of programs written by non-programmers is old but AFAIK never successful. At certain level, anything but the power of source code becomes irreplaceable.
Today, there is a lot of talk about DSLs, but not as something that non-programmers should write, more like something they could read.
It seems to me that the direction company is taking in this respect is a dead-end. What do you think?
EDIT: It is worth noting (and that's where some of insipiration is coming from) that many big players are experimenting in that direction. See Microsoft Popfly, Google Sites, iRise, many Mashup solutions etc.
Yes, it's a dead end. The problem is simple: no matter how simple you make the expression of a solution, you still have to analyze and understand the problem to be solved. That's about 80-90% of how (most good) programmers spend their time, and it's the part that takes the real skill and thinking. Yes, once you've decided what to do, there's some skill involved in figuring out how to do that (in a programming language of your choice). In most cases, that's a small part of the problem, and the least open to things like schedule slippage, cost overrun or outright failure.
Most serious problems in software projects occur at a much earlier stage, in the part where you're simply trying to figure out what the system should do, what users must/should/may do which things, what problems the system will (and won't) attempt to solve, and so on. Those are the hard problems, and changing the environment to expressing the solution in some way other that source code will do precisely nothing to help any of those difficult problems.
For a more complete treatise on the subject, you might want to read No Silver Bullet - Essence and Accident in Software Engineering, by Frederick Brooks (Included in the 20th Anniversary Edition of The Mythical Man-Month). The entire paper is about essentially this question: how much of the effort involved in software engineering is essential, and how much is an accidental result of the tools, environments, programming languages, etc., that we use. His conclusion was that no technology was available that gave any reasonable hope of improving productivity by as much as one order of magnitude.
Not to question the decision to use 5GLs, etc, but programming is hard.
John Skeet - Programming is Hard
Coding Horror - Programming is Hard
5GLs have been considered a dead-end for a while now.
I'm thinking of the family of products that include Ms Access, Excel, Clarion for DOS, etc. Where you can make applications with 0 source code and no programmers. Not that they are capable of AI quality operations, but they can make very usable applications.
There will always be "real" languages to do the work, but we can drag and drop the workflow.
I'm using Apple's Automator which allows users to chain together "Actions" exposed by the various applications on their systems.
Actions have inputs and/or outputs, some have UI elements and basic logic can be applied to the chain.
The key difference between automator
and other visual environments is that
the actions use existing application
code and don't require any special
installation.
More Info > http://www.macosxautomation.com/automator/
I've used it to "automate" many batch processes and had really great results (surprises me every time). I've got it running builds and backups and whenever i need to process a mess of text files it comes through.
I would love to know whether iHook or Platypus (osx wrapper builders for shell scripts) could let me develop plugins in python ....
There is definitely room for more applications like this and for more support from OSX application developers but the idea is sound.
Until there's major support there aren't many "actions" available, but a quick check on my system just showed me an extra 30 that i didn't know i had.
PS. There was another app for OS-preX called "Filter Tops" which had a much more limited set of plugins.
How about Dabble DB?
Of course, just like MS Access and other non-programmer programming platforms, it has some necessary limitations in order that the user won't get him or herself stuck... as John pointed out programming is hard. But it does give the user a lot of power, and it seems that most applications that non-programmers want to build are database-type applications anyway.

Sample Problems for Multithreading Practice

I'm about to tackle what I see as a hard problem, I think. I need to multi-thread a pipeline of producers and consumers.
So I want to start small. What are some practice problems, in varying levels of difficulty, that would be good for multi-threading practice? (And not contrived, impractical examples you see in books not dedicated to concurrency).
What books or references would you recommend that focus on concurrency and give in-depth problems and cases?
(I'd rather not focus on the problem I want to solve. I just want to ask for good references and sample problems. This would be more useful to other users. I'm not stuck on the problem.)
The little book of semaphores is a good free book. The author takes a unique approach of first asking a problem and then presenting hints before answering. The problems increase in difficulty level gradually, and the book isn't written for any language in particular but covers general multithreading concepts.
If you have enough time to invest I would recommend the book "Concurrency: State Models & Java Programs, 2nd Edition" by Jeff Magee and Jeff Kramer, John Wiley&Sons 2006
You can ignore the Java part if you are using some other language
There's a language used to model processes and concurrent processes called FSP. It needs some time and energy to be invested in order to be proficient in the language. There's a tool (LTSA, both are free and supported by an Eclipse plugin or stand alone app) which verifies your models and make you pretty shure that your model is correct from the standpoint of concurrent execution.
Translating this models to your language constructs is then just a question of programming technique and few design patterns.
Most text book problems, like readers-writers, producers-consumers or dinning philosophers are all illustrations of the mutex. I would prefer to model a prototype which is a simplistic approximation the bigger problem and go ahead.
I have some times seen situations where dead-lock avoidance is what is needed and dead-lock prevention measures are being used. It is always a good idea to analyse if Banker's algorithm would suit the case or not.
Completely ignoring your request, I'll suggest that you should look at SEDA (staged event driven architecture) as a way to think about setting up a multi-threaded pipeline of producers and consumers.
I'm not sure what you are looking for. But in real world enterprise situation, we usually use some kind of messaging framework when doing producers consumers stuff. Tipically in Java, that's JMS. And you can use the excellent Spring Framework to help you along.
If you're working with Java at all (and possibly even if you're not), you should definitely read Java Concurrency In Practice.
To be honest, many real-world multithreading programs are not doing much more than reading/writing some value (whether string or int) -- circular buffers (as a network connection might need), readers/writers of log files, etc.
In fact, I'd say that if you implement (or find) a solid (and generic) circular buffer, and then run all thread-to-thread communication through those buffers as the only contact point, that'll cover a very large portion of any multithread syncing you might need to do. (Unless you're working in a buzzword-compliant environment, and need to tack "enterprise", "messaging", or whatever onto the buzzword list... or you're writing a database or operating system.)
(Note that "circular buffer" is a fairly C-centric term, being rooted in the relatively direct manipulation of a block of memory. Python's Queue class implements the same basic principle in a list-centric way, and I'm sure that numerous other languages have conceptually similar constructs under slightly different names...)

Have we given up on the idea of code reuse? [closed]

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A couple of years ago the media was rife with all sorts of articles on
how the idea of code reuse was a simple way to improve productivity
and code quality.
From the blogs and sites I check on a regular basis it seems as though
the idea of "code reuse" has gone out of fashion. Perhaps the 'code
reuse' advocates have all joined the SOA crowd instead? :-)
Interestingly enough, when you search for 'code reuse' in Google the
second result is titled:
"Internal Code Reuse Considered Dangerous"!
To me the idea of code reuse is just common sense, after all look at
the success of the apache commons project!
What I want to know is:
Do you or your company try and reuse code?
If so how and at what level, i.e. low level api, components or
shared business logic? How do you or your company reuse code?
Does it work?
Discuss?
I am fully aware that there are many open source libs available and that anyone who has used .NET or the Java has reused code in some form. That is common sense!
I was referring more to code reuse within an organizations rather than across a community via a shared lib etc.
I originally asked;
Do you or your company try and reuse code?
If so how and at what level, i.e. low level api, components or shared business logic? How do you or your company reuse code?
From where I sit I see very few example of companies trying to reuse code internally?
If you have a piece of code which could potentially be shared across a medium size organization how would you go about informing other members of the company that this lib/api/etc existed and could be of benefit?
The title of the article you are referring to is misleading, and is actually a very good read. Code reuse is very beneficial, but there are downsides with everything. Basically, if I remember correctly, the gist of the article is that you are sealing the code in a black box and not revisiting it, so as the original developers leave you lose the knowledge. While I see the point, I don't necessarily agree with it - at least not to a "sky is falling" regard.
We actually group code reuse into more than just reusable classes, we look at the entire enterprise. Things that are more like framework enhancement or address cross-cutting concerns are put into a development framework that all of our applications use (think things like pre- and post-validation, logging, etc.). We also have business logic that is applicable to more than one application, so those sort of things get moved to a BAL core that is accessible anywhere.
I think that the important thing is not to promote things for reuse if they are not going to really be reused. They should be well documented, so that new developers can have a resource to help them come up to speed, as well. Chances are, if the knowledge isn't shared, the code will eventually be reinvented somewhere else and will lead to duplication if you are not rigorous in documentation and knowledge sharing.
We reuse code - in fact, our developers specifically write code that can be reused in other projects. This has paid off quite nicely - we're able to start new projects quickly, and we iteratively harden our core libraries.
But one can't just write code and expect it to be re-used; code reuse requires communication among team members and other users so people know what code is available, and how to use it.
The following things are needed for code reuse to work effectively:
The code or library itself
Demand for the code across multiple projects or efforts
Communication of the code's features/capabilities
Instructions on how to use the code
A commitment to maintaining and improving the code over time
Code reuse is essential. I find that it also forces me to generalize as much as possible, also making code more adaptable to varying situations. Ideally, almost every lower level library you write should be able to adapt to a new set of requirements for a different application.
I think code reuse is being done through open source projects for the most part. Anything that can be reused or extended is being done via libraries. Java has an amazing number of open source libraries available for doing a large number of things. Compare that to C++, and how early on everything would have to be implemented from scratch using MFC or the Win32 API.
We reuse code.
On a small scale we try to avoid code duplication as much as posible. And we have a complete library with a lot of frequently used code.
Normally code is developed for one application. And if it is generic enough, it is promoted to the library. This works excelent.
The idea of code reuse is no longer a novel idea...hence the apparent lack of interest. But it is still very much a good idea. The entire .NET framework and the Java API are good examples of code reuse in action.
We have grown accustomed to developing OO libraries of code for our projects and reusing them in other projects. Its a part of the natural life cycle of an idea. It is hotly debated for a while and then everyone accepts and there is no reason for further discussion.
Of course we reuse code.
There are a near infinite amount of packages, libraries and shared objects available for all languages, with whole communities of developers behing them supporting and updating.
I think the lack of "media attention" is due to the fact that everyone is doing it, so it's no longer worth writing about. I don't hear as many people raising awareness of Object-Oriented Programming and Unit Testing as I used to either. Everyone is already aware of these concepts (whether they use them or not).
Level of media attention to an issue has little to do with its importance, whether we're talking software development or politics! It's important to avoid wasting development effort by reinventing (or re-maintaining!) the wheel, but this is so well-known by now that an editor probably isn't going to get excited by another article on the subject.
Rather than looking at the number of current articles and blog posts as a measure of importance (or urgency) look at the concepts and buzz-phrases that have become classics or entered the jargon (another form of reuse!) For example, Google for uses of the DRY acronym for good discussion on the many forms of redundancy that can be eliminated in software and development processes.
There's also a role for mature judgment regarding costs of reuse vs. where the benefits are achieved. Some writers advocate waiting to worry about reuse until a second or third use actually emerges, rather than spending effort to generalize bit of code the first time it is written.
My personal view, based on the practise in my company:
Do you or your company try and reuse code?
Obviously, if we have another piece of code that already fits our needs we will reuse it. We don't go out of our way to use square pegs in round holes though.
If so how and at what level, i.e. low level api, components or shared business logic? How do you or your company reuse code?
At every level. It is written into our coding standards that developers should always assume their code will be reused - even if in reality that is highly unlikely. See below
If your OO model is good, your API probably reflects your business domain, so reusable classes probably equates to reusable business logic without additional effort.
For actual reuse, one key point is knowing what code is already available. We resolve this by having everything documented in a central location. We just need a little discipline to ensure that the documentation is up-to-date and searchable in a meaningful way.
Does it work?
Yes, but not because of the potential or actual reuse! In reality, beyond a few core libraries and UI components, there isn't a large amount of reuse.
In my personal opinion, the real value is in making the code reusable. In doing so, aside from a hopefully cleaner API, the code will (a) be documented sufficiently for another developer to use it without trawling the source code, and (b) it will also be replaceable. These points are a great benefit to on-going software maintenance.
Do you or your company try and reuse code? If so how and at what
level, i.e. low level api, components or shared business logic? How do
you or your company reuse code?
I used to work in a codebase with uber code reuse, but it was difficult to maintain because the reused code was unstable. It was prone to design changes and deprecation in ways that cascaded to everything using it. Before that I worked in a codebase with no code reuse where the seniors actually encouraged copying and pasting as a way to reuse even application-specific code, so I got to see the two extremities and I have to say that one isn't necessarily much better than the other when taken to the extremes.
And I used to be an uber bottom-up kind of programmer. You ask me to build something specific and I end up building generalized tools. Then using those tools, I build more complex generalized tools, then start building DIP abstractions to express the design requirements for the lower-level tools, then I build even more complex tools and repeat, and at some point I start writing code that actually does what you want me to do. And as counter-productive as that sounded, I was pretty fast at it and could ship complex products in ways that really surprised people.
Problem was the maintenance over the months, years! After I built layers and layers of these generalized libraries and reused the hell out of them, each one wanted to serve a much greater purpose than what you asked me to do. Each layer wanted to solve the world's hunger needs. So each one was very ambitious: a math library that wants to be amazing and solve the world's hunger needs. Then something built on top of the math library like a geometry library that wants to be amazing and solve the world's hunger needs. You know something's wrong when you're trying to ship a product but your mind is mulling over how well your uber-generalized geometry library works for rendering and modeling when you're supposed to be working on animation because the animation code you're working on needs a few new geometry functions.
Balancing Everyone's Needs
I found in designing these uber-generalized libraries that I had to become obsessed with the needs of every single team member, and I had to learn how raytracing worked, how fluids dynamics worked, how the mesh engine worked, how inverse kinematics worked, how character animation worked, etc. etc. etc. I had to learn how to do pretty much everyone's job on the team because I was balancing all of their specific needs in the design of these uber generalized libraries I left behind while walking a tightrope balancing act of design compromises from all the code reuse (trying to make things better for Bob working on raytracing who is using one of the libraries but without hurting John too much who is working on physics who is also using it but without complicating the design of the library too much to make them both happy).
It got to a point where I was trying to parametrize bounding boxes with policy classes so that they could be stored either as center and half-size as one person wanted or min/max extents as someone else wanted, and the implementation was getting convoluted really fast trying to frantically keep up with everyone's needs.
Design By Committee
And because each layer was trying to serve such a wide range of needs (much wider than we actually needed), they found many reasons to require design changes, sometimes by committee-requested designs (which are usually kind of gross). And then those design changes would cascade upwards and affect all the higher-level code using it, and maintenance of such code started to become a real PITA.
I think you can potentially share more code in a like-minded team. Ours wasn't like-minded at all. These are not real names but I'd have Bill here who is a high-level GUI programmer and scripter who creates nice user-end designs but questionable code with lots of hacks, but it tends to be okay for that type of code. I got Bob here who is an old timer who has been programming since the punch card era who likes to write 10,000 line functions with gotos in them and still doesn't get the point of object-oriented programming. I got Joe here who is like a mathematical wizard but writes code no one else can understand and always make suggestions which are mathematically aligned but not necessarily so efficient from a computational standpoint. Then I got Mike here who is in outer space who wants us to port the software to iPhones and thinks we should all follow Apple's conventions and engineering standards.
Trying to satisfy everyone's needs here while coming up with a decent design was, probably in retrospect, impossible. And in everyone trying to share each other's code, I think we became counter-productive. Each person was competent in an area but trying to come up with designs and standards which everyone is happy with just lead to all kinds of instability and slowed everyone down.
Trade-Offs
So these days I've found the balance is to avoid code reuse for the lowest-level things. I use a top-down approach from the mid-level, perhaps (something not too far divorced from what you asked me to do), and build some independent library there which I can still do in a short amount of time, but the library doesn't intend to produce mini-libs that try to solve the world's hunger needs. Usually such libraries are a little more narrow in purpose than the lower-level ones (ex: a physics library as opposed to a generalized geometry-intersection library).
YMMV, but if there's anything I've learned over the years in the hardest ways possible, it's that there might be a balancing act and a point where we might want to deliberately avoid code reuse in a team setting at some granular level, abandoning some generality for the lowest-level code in favor of decoupling, having malleable code we can better shape to serve more specific rather than generalized needs, and so forth -- maybe even just letting everyone have a little more freedom to do things their own way. But of course all of this is with the aim of still producing a very reusable, generalized library, but the difference is that the library might not decompose into the teeniest generalized libraries, because I found that crossing a certain threshold and trying to make too many teeny, generalized libraries starts to actually become an extremely counter-productive endeavor in the long term -- not in the short term, but in the long run and broad scheme of things.
If you have a piece of code which could potentially be shared across a
medium size organization how would you go about informing other
members of the company that this lib/api/etc existed and could be of
benefit?
I actually am more reluctant these days and find it more forgivable if colleagues do some redundant work because I would want to make sure that code does something fairly useful and non-trivial and is also really well-tested and designed before I try to share it with people and accumulate a bunch of dependencies to it. The design should have very, very few reasons to require any changes from that point onwards if I share it with the rest of the team.
Otherwise it could cause more grief than it actually saves.
I used to be so intolerant of redundancy (in code or efforts) because it appeared to translate to a product that was very buggy and explosive in memory use. But I zoomed in too much on redundancy as the key problem, when really the real problem was poor quality, hastily-written code, and a lack of solid testing. Well-tested, reliable, efficient code wouldn't suffer that problem to nearly as great of a degree even if some people duplicate, say, some math functions here and there.
One of the common sense things to look at and remember that I didn't at the time is how we don't mind some redundancy when we use a very solid third party library. Chances are that you guys use a third party library or two that has some redundant work with what your team is doing. But we don't mind in those cases because the third party library is great and well-tested. I recommend applying that same mindset to your own internal code. The goal should be to create something awesome and well-tested, not to fuss over a little bit of redundancy here and there as I mistakenly did long ago.
So these days I've shifted my intolerance towards a lack of testing instead. Instead of getting upset over redundant efforts, I find it much more productive to get upset over other people's lack of unit and integration testing! :-D
While I think code reuse is valuable, I can see where this sentiment is rooted. I've worked on a lot of projects where much extra care was taken to create re-usable code that was then never reused. Of course reuse is much preferable to duplicate code, but I have seen a lot of very extenisve object models created with the goal of using the objects across the enterprise in multiple projects (kind of the way the same service in SOA can be used in different apps) but have never seen the objects actually used more than once. Maybe I just haven't been part of organizations taking good advantage of the principle of reuse.
The two software projects I've worked on have both been long term development. One is about 10 years old, the other has been around for over 30 years, rewritten in a couple versions of Fortran along the way. Both make extensive reuse of code, but both rely very little on external tools or code libraries. DRY is a big mantra on the newer project, which is in C++ and lends itself more easily to doing that in practice.
Maybe the better question is when do we NOT reuse code these days? We are either in a state on building using someone elses observed "best practices" or prediscovered "design patterns" or just actually building on legacy code, libraries, or copying.
It seems the degree to which code A is reused to make code B is often based around how much the ideas in code A taken to code B are abstracted into design patterns/idioms/books/fleeting thoughts/actual code/libraries. The hard part is in applying all those good ideas to your actual code.
Non-technical types get overzealous about the reuse thing. They don't understand why everything can't be copy-pasted. They don't understand why the greemelfarm needs a special adapter to communicate the same information that it used to to the old system to the new system, and that, unfortunately we can't change either due to a bazillion other reasons.
I think techies have been reusing from day 1 in the same way musicians have been reusing from day 1. Its an ongoing organic evolution and sythesis that will keep ongoing.
Code reuse is an extremely important issue - where code is not reused, projects take longer and are harder for new team members to get into.
However, writing reusable code takes longer.
Personally, I try to write all my code in a reusable way, this takes longer, but it results in the fact that most of my code has become official infrastructures in my organization and that new projects based on these infrastructures take significantly less time.
The danger in reusing code, is if the reused code is not written as an infrastructure - in a general and encapsulated manner with as few as possible assumptions and as much as possible documentation and unit testing, that the code can end up doing unexpected things.
Also, if bugs are found and fixed, or features added, these changes are rarely returned to the source code, resulting in different versions of the reused code, that no one knows of or understands.
The solution is:
1. To design and write the code with not only one project in mind, but to think of future requirements and try to make the design flexible enough to cover them with minimal code change.
2. To enclose the code within libraries that are to be used as-is and not modified within using projects.
3. To allow users to view and modify the code of of the library withing its solution (not within the using project's solution).
4. To design future projects to be based on the existing infrastructures, making changes to the infrastructures as necessary.
5. To charge maintaining the infrastructure to all projects, thus keeping the infrastructure funded.
Maven has solved code reuse. I'm completely serious.

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