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  • Is the Cloud ready for an Enterprise Java web application? Seeking a JEE hosting advice.

    - by Jakub Holý
    Greetings to all the smart people around here! I'd like to ask whether it is feasible or a good idea at all to deploy a Java enterprise web application to a Cloud such as Amazon EC2. More exactly, I'm looking for infrastructure options for an application that shall handle few hundred users with long but neither CPU nor memory intensive sessions. I'm considering dedicated servers, virtual private servers (VPSs) and EC2. I've noticed that there is a project called JBoss Cloud so people are working on enabling such a deployment, on the other hand it doesn't seem to be mature yet and I'm not sure that the cloud is ready for this kind of applications, which differs from the typical cloud-based applications like Twitter. Would you recommend to deploy it to the cloud? What are the pros and cons? The application is a Java EE 5 web application whose main function is to enable users to compose their own customized Product by combining the available Parts. It uses stateless and stateful session beans and JPA for persistence of entities to a RDBMS and fetches information about Parts from the company's inventory system via a web service. Aside of external users it's used also by few internal ones, who are authenticated against the company's LDAP. The application should handle around 300-400 concurrent users building their product and should be reasonably scalable and available though these qualities are only of a medium importance at this stage. I've proposed an architecture consisting of a firewall (FW) and load balancer supporting sticky sessions and https (in the Cloud this would be replaced with EC2's Elastic Load Balancing service and FW on the app. servers, in a physical architecture the load-balancer would be a HW), then two physical clustered application servers combined with web servers (so that if one fails, a user doesn't loose his/her long built product) and finally a database server. The DB server would need a slave backup instance that can replace the master instance if it fails. This should provide reasonable availability and fault tolerance and provide good scalability as long as a single RDBMS can keep with the load, which should be OK for quite a while because most of the operations are done in the memory using a stateful bean and only occasionally stored or retrieved from the DB and the amount of data is low too. A problematic part could be the dependency on the remote inventory system webservice but with good caching of its outputs in the application it should be OK too. Unfortunately I've only vague idea of the system resources (memory size, number and speed of CPUs/cores) that such an "average Java EE application" for few hundred users needs. My rough and mostly unfounded estimate based on actual Amazon offerings is that 1.7GB and a single, 2-core "modern CPU" with speed around 2.5GHz (the High-CPU Medium Instance) should be sufficient for any of the two application servers (since we can handle higher load by provisioning more of them). Alternatively I would consider using the Large instance (64b, 7.5GB RAM, 2 cores at 1GHz) So my question is whether such a deployment to the cloud is technically and financially feasible or whether dedicated/VPS servers would be a better option and whether there are some real-world experiences with something similar. Thank you very much! /Jakub Holy PS: I've found the JBoss EAP in a Cloud Case Study that shows that it is possible to deploy a real-world Java EE application to the EC2 cloud but unfortunately there're no details regarding topology, instance types, or anything :-(

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  • Can I legally publish my Fortran 90 wrappers to nVidias CUFFT library (from CUDA SDK)?

    - by Jakub Narebski
    From a legal standpoint (licensing issues), can I legally in agreement with license publish Fortran 90 wrappers (bindings) to CUFFT library from nVidia CUDA Toolkit, under some open source license (either CC0 i.e. public domain, or some kind of permissive license like BSD). nVidia provides only C bindings with their CUDA SDK. Header files contain the following text: /* * Copyright 1993-2011 NVIDIA Corporation. All rights reserved. * * NOTICE TO LICENSEE: * * This source code and/or documentation ("Licensed Deliverables") are * subject to NVIDIA intellectual property rights under U.S. and * international Copyright laws. * * These Licensed Deliverables contained herein is PROPRIETARY and * CONFIDENTIAL to NVIDIA and is being provided under the terms and * conditions of a form of NVIDIA software license agreement by and * between NVIDIA and Licensee ("License Agreement") or electronically * accepted by Licensee. Notwithstanding any terms or conditions to * the contrary in the License Agreement, reproduction or disclosure * of the Licensed Deliverables to any third party without the express * written consent of NVIDIA is prohibited. The License.txt file includes the following fragment Source Code: Developer shall have the right to modify and create derivative works with the Source Code. Developer shall own any derivative works ("Derivatives") it creates to the Source Code, provided that Developer uses the Materials in accordance with the terms and conditions of this Agreement. Developer may distribute the Derivatives, provided that all NVIDIA copyright notices and trademarks are propagated and used properly and the Derivatives include the following statement: "This software contains source code provided by NVIDIA Corporation."

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  • Jersey 1.8 is released

    - by Jakub Podlesak
    On the last Friday, we have released the 1.8 version of Jersey, the open source, production quality, reference implementation of JAX-RS. The JAX-RS 1.1 specification is available at the JCP web site and also available in non-normative HTML here. For an overview of JAX-RS features read the Jersey user guide. To get started with Jersey read the getting started section of that guide. To understand more about what Jersey depends on read the dependencies section of that guide. See change log here. This, 1.8, version of Jersey is going to be integrated into GlassFish 3.1.1 and contains bug fixes mainly. The most important fix from this perspective is included in the JAX-RS/EJB integration layer. It is now possible to implement JAX-RS resources as EJB Session beans, which implement local and/or remote interfaces. This functionality was broken in previous releases. Another great addition should come into the client space, where Pavel has already done some preparation in the client API (including some breaking changes there) for the non-blocking asynchronous client feature. The implementation is already part of the experimental Jersey space and should be included as part of the stable Jersey bits in some of the coming releases. For feedback send email to: [email protected] (archived here) or log bugs/features here.

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  • Is there a ways to see granular per-visit data in Google Analytics?

    - by jakub.g
    I've started using Google Analytics very recently and I'm a bit lost with the sea of options (have been using Sitemeter before for some time). I've clicked through the service a lot but couldn't find what I'm accustomed to. I can see multitude of aggregated statistics in GA like: charts of browser share lists of country share lists of most visited URLs within the page and so on, but I would actually like to analyze each of the visits themselves. Something like: User X, France, Chrome, 7 pageviews between 18:01 and 18:15, entered on a.htm and exited on b.htm User Y, UK, Firefox, 1 pageview at 18:20, entered on c.htm Is there an easy way to see the reports in this way (perhaps by clicking a link to a separate page to see that particular session's stats)? How to navigate there if so?

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  • Jersey 2.0 Integrated into GlassFish 4.0

    - by Jakub Podlesak
    The latest promoted build of GlassFish 4.0 (glassfish-4.0-b43.zip) now contains upgraded Jersey version, 2.0-m05. Users are getting an early access to the implementation of some parts of the JAX-RS 2.0 API Early Draft Review 3. The appropriate JAX-RS bundle, version 2.0-m09 , gets bundled into GlassFish 4.0 as well. What should work The simple answer is: all the basic stuff. We have particularly tested the following two examples: simple hello world webapp multipart webapp Both above linked archives contain adjusted projects, so that resulting war files do not bundle any Jersey dependencies. Both also use Jersey 2 specific Servlet class, org.glassfish.jersey.servlet.ServletContainer, for deployment. See Martin's blog post on how to package war applications capable of running with both Jersey 1 and Jersey 2 ServletContainer classes. What has not been covered yet The main areas, which have not been touched yet in Jersey 2 are: EJB integration CDI integration Validation These are also the areas where we are going to spend the most of our cycles in the coming month.

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  • Are any Zotac Zboxs suitable as HTPC / media centres?

    - by Jakub
    Are any Zotac Zboxes suitable as HTPC / media centres? I'm after a fanless HTPC client in the living room to work with my MythTV server in my home office. I like the small compact form factor of the Zbox but what little I could find by Googling didn't clearly recommend any particular models for Ubuntu / MythTV / XBMC. Can anyone recommend any models that work with little hassle? Or, if there aren't any, are there other more Linux-friendly small format fanless PCs I should be looking at instead?

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  • When do you use float and when do you use double

    - by Jakub Zaverka
    Frequently in my programming experience I need to make a decision whether I should use float or double for my real numbers. Sometimes I go for float, sometimes I go for double, but really this feels more subjective. If I would be confronted to defend my decision, I would probably not give sound reasons. When do you use float and when do you use double? Do you always use double, only when memory constraints are present you go for float? Or you use always float unless the precision requirement requires you to use double? Are there some substantial differences regarding computational complexity of basic arithemtics between float and double? What are the pros and cons of using float or double? And have you even used long double?

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  • What makes it hard to protect from hacks/bots in BF3 and Quake Live?

    - by Jakub P.
    After playing these games, asking other players/admins, and reading online I am led to believe that Quake Live and Battlefield 3 are frequented by bots and there are plenty of hacks of various kinds. I'm confused how this is possible, or even easy seeing how many players have access to these kinds of "tools" (sic). Isn't it possible for the game authors to digitally sign the game executables so that when they run, the server can ensure only the allowed client is sending commands, thus preventing any kind of abuse? I.e. every player command would be signed by a private key, or symmetrically encrypted (not sure which would make more sense). I understand that players can look at the running executable's behavior (memory etc.), but if games are apparently so easy to hack, shouldn't most apps be hacked as well (e.g. Skype, all DRM running on Windows etc.)?

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  • How to measure disk performance?

    - by Jakub Šturc
    I am going to "fix" a friend's computer this weekend. By the symptoms he describes it looks like he has a disk performance problem with his 5400 rpm disk. I want to be sure that disk is the problem so I want to "scientificaly" measure the performance. Which tools do you recommend me for this job? Is there any standard set of numbers I can compare the result of measurement with?

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  • What is the solid Windows Server 2008 VPS hosting (preferably) in Europe?

    - by Jakub Šturc
    I am looking for Windows Server 2008 VPS hosting to host a few sites/apps with special needs. I spend few hours googling but I am not satisfied with the result. I looks to me that this business is full of crap. Two thirds of the reviews seems to be faked and advertised offers is unavailable or contains some hidden fee. So my question is which VPS hosting with Windows Server 2008 do you recommend? I slightly prefer data center in Europe and euro payment it isn't deal breaker. Note: I didn't made question community wiki because I am interested in answers from users with some reputation and I want to preserve theirs answers.

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  • Is the Cloud ready for an Enterprise Java web application? Seeking a JEE hosting advice.

    - by Jakub Holý
    Greetings to all the smart people around here! I'd like to ask whether it is feasible or a good idea at all to deploy a Java enterprise web application to a Cloud such as Amazon EC2. More exactly, I'm looking for infrastructure options for an application that shall handle few hundred users with long but neither CPU nor memory intensive sessions. I'm considering dedicated servers, virtual private servers (VPSs) and EC2. I've noticed that there is a project called JBoss Cloud so people are working on enabling such a deployment, on the other hand it doesn't seem to be mature yet and I'm not sure that the cloud is ready for this kind of applications, which differs from the typical cloud-based applications like Twitter. Would you recommend to deploy it to the cloud? What are the pros and cons? The application is a Java EE 5 web application whose main function is to enable users to compose their own customized Product by combining the available Parts. It uses stateless and stateful session beans and JPA for persistence of entities to a RDBMS and fetches information about Parts from the company's inventory system via a web service. Aside of external users it's used also by few internal ones, who are authenticated against the company's LDAP. The application should handle around 300-400 concurrent users building their product and should be reasonably scalable and available though these qualities are only of a medium importance at this stage. I've proposed an architecture consisting of a firewall (FW) and load balancer supporting sticky sessions and https (in the Cloud this would be replaced with EC2's Elastic Load Balancing service and FW on the app. servers, in a physical architecture the load-balancer would be a HW), then two physical clustered application servers combined with web servers (so that if one fails, a user doesn't loose his/her long built product) and finally a database server. The DB server would need a slave backup instance that can replace the master instance if it fails. This should provide reasonable availability and fault tolerance and provide good scalability as long as a single RDBMS can keep with the load, which should be OK for quite a while because most of the operations are done in the memory using a stateful bean and only occasionally stored or retrieved from the DB and the amount of data is low too. A problematic part could be the dependency on the remote inventory system webservice but with good caching of its outputs in the application it should be OK too. Unfortunately I've only vague idea of the system resources (memory size, number and speed of CPUs/cores) that such an "average Java EE application" for few hundred users needs. My rough and mostly unfounded estimate based on actual Amazon offerings is that 1.7GB and a single, 2-core "modern CPU" with speed around 2.5GHz (the High-CPU Medium Instance) should be sufficient for any of the two application servers (since we can handle higher load by provisioning more of them). Alternatively I would consider using the Large instance (64b, 7.5GB RAM, 2 cores at 1GHz) So my question is whether such a deployment to the cloud is technically and financially feasible or whether dedicated/VPS servers would be a better option and whether there are some real-world experiences with something similar. Thank you very much! /Jakub Holy PS: I've found the JBoss EAP in a Cloud Case Study that shows that it is possible to deploy a real-world Java EE application to the EC2 cloud but unfortunately there're no details regarding topology, instance types, or anything :-(

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  • Do fluent interfaces violate the Law of Demeter?

    - by Jakub Šturc
    The wikipedia article about Law of Demeter says: The law can be stated simply as "use only one dot". However a simple example of a fluent interface may look like this: static void Main(string[] args) { new ZRLabs.Yael.Pipeline("cat.jpg") .Rotate(90) .Watermark("Monkey") .RoundCorners(100, Color.Bisque) .Save("test.png"); } So does this goes together?

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  • Is Stopwatch really broken?

    - by Jakub Šturc
    At MSDN page for Stopwatch class I discovered link to interesting article which makes following statement about Stopwatch: However there are some serious issues: This can be unreliable on a PC with multiple processors. Due to a bug in the BIOS, Start() and Stop() must be executed on the same processor to get a correct result. This is unreliable on processors that do not have a constant clock speed (most processors can reduce the clock speed to conserve energy). This is explained in detail here. I am little confused. I've seen tons of examples of using Stopwatch and nobody mention this drawbacks. How serious is this? Should I avoid using Stopwatch?

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  • What's the false operator in C# good for?

    - by Jakub Šturc
    There are two weird operators in C#: the true operator the false operator If I understand this right these operators can be used in types which I want to use instead of a boolean expression and where I don't want to provide an implicit conversion to bool. Let's say I have a following class: public class MyType { public readonly int Value; public MyType(int value) { Value = value; } public static bool operator true (MyType mt) { return mt.Value > 0; } public static bool operator false (MyType mt) { return mt.Value < 0; } } So I can write the following code: MyType mTrue = new MyType(100); MyType mFalse = new MyType(-100); MyType mDontKnow = new MyType(0); if (mTrue) { // Do something. } while (mFalse) { // Do something else. } do { // Another code comes here. } while (mDontKnow) However for all the examples above only the true operator is executed. So what's the false operator in C# good for? Note: More examples can be found here, here and here.

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  • What are differences between AssemblyVersion, AssemblyFileVersion and AssemblyInformationalVersion?

    - by Jakub Šturc
    There are three assembly version attributes. What are differences? Is it ok if I use AssemblyVersion and ignore the rest? MSDN says: AssemblyVersion: Specifies the version of the assembly being attributed. AssemblyFileVersion: Instructs a compiler to use a specific version number for the Win32 file version resource. The Win32 file version is not required to be the same as the assembly's version number. AssemblyInformationalVersion: Defines additional version information for an assembly manifest. This is follow up to What are the best practices for using Assembly Attributes?

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  • Hidden Features of C#?

    - by Serhat Özgel
    This came to my mind after I learned the following from this question: where T : struct We, C# developers, all know the basics of C#. I mean declarations, conditionals, loops, operators, etc. Some of us even mastered the stuff like Generics, anonymous types, lambdas, linq, ... But what are the most hidden features or tricks of C# that even C# fans, addicts, experts barely know? Here are the revealed features so far: Keywords yield by Michael Stum var by Michael Stum using() statement by kokos readonly by kokos as by Mike Stone as / is by Ed Swangren as / is (improved) by Rocketpants default by deathofrats global:: by pzycoman using() blocks by AlexCuse volatile by Jakub Šturc extern alias by Jakub Šturc Attributes DefaultValueAttribute by Michael Stum ObsoleteAttribute by DannySmurf DebuggerDisplayAttribute by Stu DebuggerBrowsable and DebuggerStepThrough by bdukes ThreadStaticAttribute by marxidad FlagsAttribute by Martin Clarke ConditionalAttribute by AndrewBurns Syntax ?? operator by kokos number flaggings by Nick Berardi where T:new by Lars Mæhlum implicit generics by Keith one-parameter lambdas by Keith auto properties by Keith namespace aliases by Keith verbatim string literals with @ by Patrick enum values by lfoust @variablenames by marxidad event operators by marxidad format string brackets by Portman property accessor accessibility modifiers by xanadont ternary operator (?:) by JasonS checked and unchecked operators by Binoj Antony implicit and explicit operators by Flory Language Features Nullable types by Brad Barker Currying by Brian Leahy anonymous types by Keith __makeref __reftype __refvalue by Judah Himango object initializers by lomaxx format strings by David in Dakota Extension Methods by marxidad partial methods by Jon Erickson preprocessor directives by John Asbeck DEBUG pre-processor directive by Robert Durgin operator overloading by SefBkn type inferrence by chakrit boolean operators taken to next level by Rob Gough pass value-type variable as interface without boxing by Roman Boiko programmatically determine declared variable type by Roman Boiko Static Constructors by Chris Easier-on-the-eyes / condensed ORM-mapping using LINQ by roosteronacid Visual Studio Features select block of text in editor by Himadri snippets by DannySmurf Framework TransactionScope by KiwiBastard DependantTransaction by KiwiBastard Nullable<T> by IainMH Mutex by Diago System.IO.Path by ageektrapped WeakReference by Juan Manuel Methods and Properties String.IsNullOrEmpty() method by KiwiBastard List.ForEach() method by KiwiBastard BeginInvoke(), EndInvoke() methods by Will Dean Nullable<T>.HasValue and Nullable<T>.Value properties by Rismo GetValueOrDefault method by John Sheehan Tips & Tricks nice method for event handlers by Andreas H.R. Nilsson uppercase comparisons by John access anonymous types without reflection by dp a quick way to lazily instantiate collection properties by Will JavaScript-like anonymous inline-functions by roosteronacid Other netmodules by kokos LINQBridge by Duncan Smart Parallel Extensions by Joel Coehoorn

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  • How to secure JBoss application server using SELinux

    - by Jakub Elias
    I want to secure RedHat 5.4 application server by SELinux (targeted policy) and have several questions 1, where can i get SELinux sources (/etc/selinux//src/policy/)There seems to be no such package on install cd .. 2, how to restrict user rights (for example user jboss could not modify /etc/my.cnf) 3, how to configure JBoss application server to work under SELinux Although i read many documents from NSA the whole topic is still not clear for me.What i want is to basically protect filesystem in case one account is broken.I cannot find any materials about securing jboss server using either chroot jail, ACLs or SELinux ....

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  • What external comment system to use for Jekyll powered blog?

    - by Jakub Narebski
    What external comment system (i.e. something like Disqus or perhaps even Hacker News / YCombinator) would you recommend for Jekyll-powered blog (in this case: blog on GitHub Pages), or in more generic term for blog aware static site generator powered blog (which includes beside Jekyll also for example ikiwiki or xfire's growl)? Because a blog without comments is not a blog :-).

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  • Linux LiveCD (or LiveUSB) with custom xorg.conf

    - by Jakub Narebski
    Is there some Live Linux distribution (on CD, DVD or USB), which allow one to use specific xorg.conf file, i.e. specific X11 configuration? The problem I am trying to solve is to find Linux Live distribution for web browsing which would work well with NEC LCD 22WV monitor. It is supposedly DDCCCI capable, but X.Org X Window System autoconfiguration fails to detect proper modeline, and uses fallback 800x600 screen resolution, instead of preferred screen resolution of 1680x1050.

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  • Force dual-mono audio (L+L or R+R) in Youtube video playback for one-channel audio movies

    - by jakub.g
    Occasionally, I find Youtube videos that have only one audio channel (only left or only right); example video (left channel only). This is quite annoying, especially with headphones on, as I hear sound in one ear, and no sound in the other. So, I want to be able to easily force dual mono (Left+Left or Right+Right) when I find that kind of video, and switch to normal stereo after I finish watching it. I have my headphones plugged well / I don't create audio/video - I want it for real-time playback only, In Windows audio config, setting balance 100% to Left / Right doesn't help (I have either still only left when moved to left, and no sound at all when moved to right), I've checked all the configurations in Control Panel > Sounds and Audio Devices > Audio > Sound Playback > Advanced like suggested in this post, in conjunction with moving balance left/right, and it doesn't seem to have any impact on actual sound I hear in headphones, No need to mix L with R, I just want L+L or R+R, I prefer software solutions to buying a stereo-to-mono adapter, Free solutions please, no $$$ ones, neither trials etc., In Control Panel > Realtek HD Sound Effect Manager I can turn on various mumbo-jumbo effects like: Concert Hall / Hangar / Bathroom / whatever environment (and in fact it makes the sound appear in two ears, but well, it's ridiculous to do this;), but there is no Dual Mono option. Finally, I know I can force L+L or R+R in VLC Player which supports Youtube (well, a little hack is needed, because Youtube internals change from time to time) but it is not very convenient to launch VLC just to play Youtube video - I want to keep it in the browser, I use Firefox generally (but well, if I don't find easier way, I will launch it in VLC).

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  • Apache Unclean shutdown of previous apache run

    - by Jakub Arnold
    I'm having problem with running Apache2.2 on my Vista machine. When I clean install Apache it works just fine, but after I installed PHP, I'm getting this error message in logs. [Fri Oct 23 21:29:02 2009] [warn] pid file C:/Dev/Apache2.2/logs/httpd.pid overwritten -- Unclean shutdown of previous Apache run? Apache service was stopped when installing PHP. I did only one shutdown before instalation via Apache Service Monitor. Deleting httpd.pid and starting again doesn't help. I even tried to lookup process with PID in that file, but there is no such process.

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  • Options to optimize lotus notes 8.5.X

    - by Jakub
    Has anyone found actually useful optimization methods for the bulky, fat, eclipse giant, nuissance that is Lotus Notes 8.5? I want it to be fast, and not eat up system resources like crazy while I run it ALL day (as it is my company's corporate mail / cal / scheduling solution). I've tried various hacks for the JVM heap size (if I recall correctly). None really bring a performance improvement. I have a dual core cpu, if that helps (I tried going the route of optimizing JAVA for 2 cores in hopes it would work, but seen no speed improvement). Notes is just sooo bloated, anyone have any suggestions to optimize/mod this thing so it is more responsive and less of a resource hog. Note: I don't want to switch to the web version, or the standard stripped down versions, I am aware of those, I just cannot since we don't run those internally for the company.

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