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I am trying to implement a cluster computing system using Java and the Windows OS. I'm looking for a solution that
is not too out of date
is reasonably easy to install and set up
has enough documentation to get started with the classes and methods without a previous knowledge of MPI
is at least somewhat user friendly
This might not be possible, but it would also be nice if it was somewhat close in usage to the Java Concurrent framework.
I initially learned a bit about the Java Concurrent package and was easily able to learn to write parallel programs on my local 8-core machine using the Runnable Interface and the ExecutorService, making all my classes threadsafe in the process. However, I have yet to find a standard mechanism to extend this programming framework to clusters.
I then learned of a GitHub project called Java-Interop-Library (https://github.com/MicrosoftHPC/Java-Interop-Library ) that could be used with Microsoft HPC Pack. I networked a few cloud computer via Amazon EC2 and installed the HPC Pack. The Java-Interop-Library was a nightmare to compile and set up. I had to manually edit several batch files and even some Java code to get it compiled. By the time I got most of it working (but not everything), I just started thinking that there had to be an easier way, and I started searching again.
My new search led me to MPJ-Express (http://mpj-express.org). I read through the documentation on the site, and it seems easy to set up. They even have documentation on how to integrate it with Eclipse and debug. But, I could never find any documentation on how the classes and methods are actually used (there's a simple hello world example, but it's not close to enough).
More searching led me to MPIJava, Hadoop, and GridGain. Having no experience with MPI or MPJ, and knowing that MPJ grew out of MPIJava, I started trying to find documentation for that instead. I found some docs, but some of it is quite old and I'm not really sure I'm on the right track. I saw the mention of GridGain on another StackOverflow post, and went to their website. They seem to have a cluster computing framework, and a simple posted example even uses what appear to be classes that use Runnable objects, which seemed attractive to me having had some experience with the Java Concurrent framework. I don't really know anything about Hadoop, other than that it might be a possibility.
I really just need some better direction on the best way to accomplish cluster computing i Java. I feel like I'm just spinning my wheels.
You can use MPJ Express and I assume that you have already given it a go and environment set up is done. MPJ Express can execute parallel Java applications on both multiocore mode and cluster mode. It must be mentioned there that the same application works for both modes without any modification so you have the option of developing and testing your application in multicore mode and when done it would seamly run cluster mode as well. Although It is not quite clear what you want to develop in the end but as far as its Java docs are concerned you can find them here: http://mpj-express.org/docs/javadocs/index.html. These are all the classes and methods that you need to develop any parallel java application.
Learning cluster Programming with MPJ Express is quite easy as you can access a comprehensive set of working examples. For this purpose unzip MPJ Express and explore test directory. It contains multiple test cases and working examples of parallel Java applications. You can have examples of point-to-point and collective communication in mpj-v0_xx/test/mpi/pt2pt and mpj-v0_xx/test/mpi/ccl respectively. You can develop any basic parallel application by just using point-to-point and collective communication methods. It would give you head start in learning cluster Programming using Java.
Let me know if you encounter any problem in setting up MPJ Express on cluster or executing examples provided in test directory. You can also post your queries on MPJ Express mailing list on following page: http://sourceforge.net/p/mpjexpress/mailman/?source=navbar
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Has anyone seen an example or done the following in Java:
http://duganchen.ca/single-page-web-app-architecture-done-right/
That is a design a single page web app that will work with Google SEO with out massive violation of DRY using Java technologies?
It doesn't seem terrible hard to do this on my own but I was curious (and lazy) to see if someone had already done it with either Spring or JAX-RS.
I have built quite a large "single-page" javascript website, that generats all HTML on the client. Server provides JSON only responses. I used Google Closure tools for the following reasons:
Google Closure Templates allows designing templates in high level templating language (named soy) which is compiled either to pure javascript functions to run on the client or java code to run on the server site.
Google Closure Compiler, which allows separating javascript code to modules and provides autmatic dependency injection for uncompiled mode. Good program structure and modularisation is necessary for any project exceeding simple html decoration. This is hard to achieve with frameworks like jQuery or dojo. In advanced compiled mode it transforms your javascript to shorter an more efficient equivalent, eliminates dead code and do dramatic reduction in size, which can shrink the original codebase to few % of the original size.
Google Stylesheets is meta css language which works great with closure compiler.
Google Closure Library is huge and well tested javascript library and with closure compiler, you only take what is needed.
To streamline the development, I'm using plovr, written by Michale Bolin, a former googler, one of the members of the original Closure Compiler Team.
I can recommend reading Michale's book: Closure, the Definitive Guide.
I must but warn, the initial leraning curve might be quite steep, but it is well worth the pain. Google used this tools to write almost all their web projects.
Just one more thing
If you feel really adventurous, and want to peep in to the future, I recomend upgrading the former strategy with Clojure/ClojureScript. For the start, watch this very persuasive talk of Rich Hickey and make sure to check Clojurescript one project.
I recommend AribaWEB for its advanced AJAX usage.
http://aribaweb.org/
Take a look to ItsNat, is a Java framework focused on Single Page Interface SEO compatible websites.
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I've been doing some research into taking my programming experience and moving into the java programming marketplace, due to a combination of personal interest and local market forces. As you can gather from the title, the vast majority of my experience has been in building web-based sites and applications, and I'd like to move as much of my previous experience as possible.
One thing that I've been unable to find a concrete answer for when should a website or web-based application designer look to going with a Java based solution, over other options currently on the market. What options would Java provide that would have a designer select Java as the basic coding language to base a project upon?
Thank you for any constructive replies that may arrive from this inquiry.
EDIT: I should have included the caveat of if other factors are equal, for example if hardware, software, developer skill in java is up to where they should be for such projects, and so forth.
The main factor is what your developers are adept in. If you've got a bunch of Java developers, go with Java.
Consider this also: Java tends to run on app servers where there is a persistent global program running, and separate threads/processes spawn off to service individual requests. However, if the main global VM croaks for some reason, your whole app can go down. The benefit of course is that you get application/system level resources that you can initialize and use continuously across all requests
Other environments like PHP basically tear down and rebuild the entire environment for each request. You can code in application level data persistence using a database, but you don't get it for free. On the other hand, if one php process croaks while processing app data, it won't kill the whole system , as the entire environment is just torn down/rebuilt for the next request.
Agreed with many of the previous posters, but one possible consideration is runtime speed.
If you are using a very basic LAMP stack server, running PHP4 or lower, Python or Perl, if you do not set pre-compilation, all of your scripts will have to be re-compiled at runtime. This can cause immense stress on the server for high intensity applications. If you're in the situation where you cannot enable pre-compiling for LAMP, but you can for Java (most Java servers require this), then this should be of concern. The disadvantage is that you may have to re-compile large chunks of your web application every time you edit it. I realize this is becoming less and less of an issue nowadays, but its something to check.
Be sure to include a learning curve in the development time if developers aren't familiar with the chosen language.
For the most part, the best technology is the one you are already using.
If you have coders that know java, have system administrators that can configure java apps and know what to do when a java app stops working, and project managers who know how to accurately schedule and plan a java deployment, you would need a very, very compelling reason to pick something else like .NET for a new project, even if .NET is "better" (whatever that means).
There are, of course, exceptions; if you're using something obsolete and/or is not going to be supported in the future (like classic ASP), or you have no legacy systems, then it's time to use something new.
I believe that the conventional wisdom on this subject is that Java is better suited to very large systems that need the discipline of static typing. Also, on very busy sites, Java can use less memory and run faster than most interpreters.
(Right out of the box, Java wants lots of memory. But on a busy system Java has only one copy of all running code.)
There are also certain prosaic reasons to stick with Java, for specific sites. They might need back-office integration or some other big piece of existing code.
I would use Java if there was a library or framework that provided specific features that no other language did (or not as well).
For example, if I had an in-house-built java library for running our Gruntmaster rock crusher, then it naturally would make sense to use Java to build an app that needed to control the Gruntmaster.
Some might say that whatever one's shop's official language is the language one should use--I disagree with that rule, as in my experience a good developer can learn any language.
There is no hard and fast rule otherwise; each language has its own strengths and weaknesses. The fact that you are asking this question about Java tells me that you are not as familiar with it.
I'd suggest you go ahead and build an app or three in Java -- then you'll know. :)
There is very little separation between the capabilities of the various technologies available today for web programming.
Java at one time was the default choice since it far surpassed the abilities of the competing technologies, but that is no longer true.
The Microsoft answer has matured rapidly; the days of classic ASP are far gone with .Net now providing all the abilities and ease of programming that Java has offered.
New languages such as PHP and Ruby have arrived or become much more mainstream, and are also valid choices based on your programming needs.
So as many others are saying it boils down to what language you or your developers are familiar with.
Another aspect to consider, is the ability to use a vast eco-system of open source libraries.
Languages like PHP, Perl or Ruby have such lib market places (almost) built in. .Net is rather closed in that sense. Java on the other hand has a a very large, enterprise grade eco-system of libraries to choose from and communities to learn from as well.
Practically I agree with the guys about leveraging existing human infrastructure.
Technologically, Java is quite good for non-standard web things - like heavy use of AJAX (GWT, DWR, Comet spring to mind), Mobile (where you generally need lots of session data and less front-end bling), really simple things that are going to be put under immense load (it will definitely trounce Apache mod_XXX every time, the only thing faster in wide-spread use is native code).
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We are currently researching ways of enhancing image quality prior to submission to OCR. The OCR engine we are currently utilizing is the Scansoft API from Nuance (v15). We were researching the Lead Tools but have since decided to look elsewhere. The licensing costs associated with Lead Tools is just too great. To start with we are looking for simple image enhancement features such as: deskewing, despeckling, line removal, punch hole removal, sharpening, etc. We are running a mix of .NET and Java software, but java solution would be preferred.
Kofax is good for pre-processing, but for the types of cleanup you are talking about may be overkill unless the images are really bad. Unless your specialty is in image processing, I'd recommend working with a provider that does the image cleanup and the OCR so you can focus on the value you actually add.
We license the OCR development kit from ABBYY (ABBY SDK) and have found it to be superb for both image processing and OCR. The API is quite extensive, and the sample apps, help and support have been beyond impressive. I definitely recommend taking a look.
Disclaimer: I work for Atalasoft
We have those functions and run-time royalty-free licensing for .NET.
http://www.atalasoft.com/products/dotimage/
We also have OCR components including a .NET wrapper for Abbyy, Tesseract and others and Searchable PDF generation (image on top of text in a PDF)
Not sure if this would be quite up to the standards that you guys would need, but perhaps you should look at some of the Paint.Net APIs. I don't know how easy it would be to extract their image processing algorithms for use in your project, but I believe they do some of the things you are looking for. Plus it is an open source project with an MIT License, so it should be pretty friendly for business use.
Research about KOFAX VRS at KOFAX.com
Maybe JMagick, it is an open source Java interface of ImageMagick. It is implemented in the form of a thin Java Native Interface (JNI) layer into the ImageMagick API. It's licensed under the LGPL so it shouldn't be a problem license wise.
http://sourceforge.net/projects/jmagick/
I would suggest Intel for its zero-cost runtime licensing.
Depends on the number and quality of the original images. Managed code and imaging tool kits will work but it's not always the best solution if you haved several million images to process. For small batches and tight budgets, I agree with the previous posters that projects like Aforge, Paint.NET, and other open source computer vision libraries will do the trick. Of course, you are on your own if the results are not improving... At least this let's you put everything you need under one application for a low cost.
If you are processing several hundred thousand images a month, then I would suggest you divide up the process into smaller workflow step and tweak each one until your cost per image gets as close to zero as you can. You will find that the OCR results rise quickly at first and then level off sooner than you expected. (I'm not a big fan of OCR but it has its place)
I use commercial Windows product from Recogniform to process and clean up the images prior to OCR in a batch mode using scripts adjusted for various kinds of images. If an image fails QC or is rejected by the OCR engine, it is "repaired" by hand using a custom .NET application built with Atalasoft's toolkit. Batch process everything and only touch what fails.
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We are developing an application that involves a lot of different tests where each test lead the users to a number of steps. We are thinking of using a state machine framework to capture the states/transitions out of the code. We are also thinking of using rule engine to supplement on the rules. Anyone has experience with any state machine framework that would work with JBoss and/or Java? Thanks in advance.
-nguyen
jbpm does this and integrates well with jboss. In my experience, it's pretty easy to use and is powerful.
You might want to look at StatefulJ. It is built off of Spring Data for Persistence support and the State Model itself is defined using Annotations. This approach makes it easier to set up and maintain vs. XML. Regarding rules - I've used Drools in the past and seems very well supported.
Disclaimer: I am the author of StatefulJ
if you are building some screen to screen transition - based system, then you should definately check out Spring WebFlow http://springframework.org/webflow
I have had very good experiences with using ragel to build easily maintainable state machines. The resulting java code is of very high quality. However, it is purely a state machine generator with no specific usage intended, so you might find other solutions that will more seamlessly work in a web related problem domain.
Maybe you can take a look at JBoss PVM. It is still in alpha, but can be used to model any type of state machine. We are also looking into it for gui transitions.
http://www.jboss.org/jbossjbpm/pvm
Try Activiti, seems a lot of people are using it.
http://activiti.org
For the rules engine part you could use Drools, of course.
Have a look at StateBuilderJava, a state machine code generator that transforms an XML description of a state machine into an extended version of the Java state pattern. It supports all UML semantics: state machine can be hierarchical, concurrent and asynchronous.
Each test scenario can be modelled with a state machine Xml description, the code generator writes the state pattern of your behalf, which is tedious and error prone if done by hand.
The other advantage is to visualize and edit the test scenario with a graphical tool.
This allows to quickly implement and document a set of test scenarios.
In the examples, a test suite of an XMPP client has be written to illustrate how state machine code generators can be used to write complex test scenarios easily and quickly.
Disclaimer: I'm the author of these software.
I've used activiti.
It is the best framework.
It is a light-weight workflow and Business Process Management (BPM) Platform.
Open Source and works on any Java Platform or cloud.
All one needs to have is the knowledge of BPMN , Maven , Spring and Activiti.
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I'm working on getting an Introduction to Groovy presentation ready for my local Java User's Group and I've pretty much got it together. What I'd like to see is what you all think I just have to cover.
Remember, this is an introductory presentation. Most of the people are experienced Java developers, but I'm pretty sure they have little to no Groovy knowledge. I won't poison the well by mentioning what I've already got down to cover as I want to see what the community has to offer.
What are the best things I can cover (in a 1 hour time frame) that will help me effectively communicate to these Java developers how useful Groovy could be to them?
p.s. I'll share my presentation here later for anyone interested.
as promised now that my presentation has been presented here it is
I don't know anything about groovy so in a sense I've qualified to answer this...
I would want you to:
Tell me why I would want to use Scripting (in general) as opposed to Java-- what does it let me do quicker (as in development time), what does it make more readable. Give tantalising examples of ways I can use chunks of scripting in my mostly Java app. You want to make this relevant to Java devs moreso than tech-junkies.
With that out of the way, why Groovy? Why not Ruby, Python or whatever (which are all runnable on the JVM).
Don't show me syntax that Java can already do (if statements, loops etc) or if you do make it quick. It's as boring as hell to watch someone walk through language syntax 101 for 20min.
For syntax that has a comparible feature in Java maybe show them side by side quickly.
For syntax that is not in Java (closures etc) you can talk to them in a bit more detail.
Remember those examples from the first point. Show me one, fully working (or at least looking like it is).
At the end have question time. That is crazy important, and with that comes a burden on you to be a psuedo-guru :P.
I'm not sure about how the Java6 scripting support works but I'm fairly sure it can be made secure. I remember something about defining the API the script can use before it's run.
If this is the case then an example you could show would be some thick-client application (e.g. a music player) where users can write their own scripts with an API you provide them in Groovy which allows them to script their app in interesting and secure ways (e.g. creating custom columns in the playlist)
I'd go for:
Closures
Duck typing
Builders (XML builder and slurper)
GStrings
Grails
I'd mention the following things in addition to what has already been stated:
GDK - extensions/additions to existing JDK classes
Interaction between Groovy and Java code (basically a non-issue)
Compiling Groovy code to Java .class files
XML parsing and mechanisms for accessing document content
One thing I like doing with Groovy is implementing an interface defined in Java as a map from method names to closures. It's a cool thing you can do with Groovy, but probably well beyond an introductory presentation though.
Include an example of how making Java code more groovy takes away soooo much code. Wait for them to pick their jaws up off of the floor before continuing. Scott Davis has a simple example at the beginning of Groovy Recipes that takes 35 lines of Java or 3 lines of Groovy.
You should definitely show them how to create a quick Grails application. Two domain classes that are related. Build a basic CRUD app. Explain that tables are being created behind the scenes using GORM(Hibernate). Then explain that you can create a war file and deploy it as you would any other Java war file. You can also add Grails/Groovy to an existing Java/JSP project so it doesn't require a huge commitment or paradigm change.
Groovy/Grails is simply Ruby/Rails for Java people. I'd cover the plugins for Netbeans/Eclipse too. Groovy/Grails are just now getting full support in the major IDE's.
Finally, if you can find a good diagram that shows how Grails is built on top of Spring, Hibernate, Quartz, Sitemesh and Groovy, I think people will understand that there is a treasure chest waiting to be unlocked.