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  • Exclusive use of a Jini server during long-running call

    - by Matthew Flint
    I'm trying to use Jini, in a "Masters/Workers" arrangement, but the Worker jobs may be long running. In addition, each worker needs to have exclusive access to a singleton resource on that machine. As it stands, if a Worker receives another request while a previous request is running, then the new request is accepted and executed in a second thread. Are there any best-practices to ensure that a Worker accepts no further jobs until the current job is complete? Things I've considered: synchronize the job on the server, with a lock on the singleton resource. This would work, but is far from ideal. A call from a Master would block until the current Worker thread completes, even if other Workers become free in the meantime unregister the Worker from the registry while the job is running, then re-register when it completes. Might work OK, but something doesn't smell right with this idea... Of course, I'm quite happy to be told that there are more appropriate technologies than Jini... but I wouldn't want anything too heavyweight, like rolling out EJB containers all over the place.

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  • Scalable Architecture for modern Web Development [on hold]

    - by Jhilke Dai
    I am doing research about Scalable architecture for Web Development, the research is solely to support Modern Web Development with flexible architecture which can scale up/down according to the needs without losing any core functionality. By Modern Web I mean to support all the Devices used to access websites, but the loading mechanism for all devices would be different. My quest of architecture is: For PC: Accessing web in PC is faster but it also depends on the Geo-location, so, the application would check by default the capacity of Internet/Browser and load the page according to it. For Mobile: Most of the mobile design these days either hide information or use different version of same application. eg: facebook uses m.facebook.com which is completely different than PC version. Hiding the things from Mobile using JavaScript or CSS is not a solution as it'll consume the bandwidth and make the application slow. So, my architecture research is about Serving one Application, which has different stack. When the application receives the request it'd send the Packaged Stack to the received request. This way the load time for end users would be faster and maintenance of application for developers would be easier. I am researching about for 4-tier(layered) architecture like: Presentation Layer Application Logic Layer -- The main Logic layer which stores the Presentation Stack Business Logic Layer Data Layer Main Question: Have you come across of similar architecture? If so, then can you list the links here, I'm very much interested to learn about those implementations specially in real world scenario. Have you thought about similar architectures and tried your own ideas, or if you have any ideas regarding this, then I urge to share. I am open to any discussions regarding this, so, please feel free to comment/answer.

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  • airplanes operating system and choice of programing language

    - by adhg
    I was wondring if anyone knows what is the operating system used in commercial airplanes (say Boeing or Airbus). Also, what is the (preferred) real-time programing language? I heard that Ada is used in Boeing, so my question is - why Ada? what are the criteria the Boeing-guys had to choose this language? (I guess Java wouldn't be a great choice if the exactly in lift off the garbage collector wakes up). Thanks!

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  • New Oracle Database Performance and Tuning Specialization version available to all partners!

    - by Catalin Teodor
    Any partner working with the Oracle database should take advantage of the new Oracle Database Performance and Tuning specialization version. Have partners review the criteria and see what’s new in this specialization solution update. Partners should plan to take the new version as the Oracle Database 11g Performance Tuning specialization becomes non-qualifying as of August 1, 2015.

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  • Multilevel Queue Scheduling (MQS) with Round Robin

    - by stackuser
    I'm trying to use MQS to create a Gantt chart of 5 processes (P1-P5) as well as their waiting, response, and turnaround times (and averages of those metrics) within a CPU task schedule. Here's the basic table of arrival times and bursts: Here's my actual work version after ticking off the finished processes. The time quantum for each time slice is (2 queues) TQ1=4 and TQ2=3. Note that I'm doing MQS and NOT MLFQ: It just doesn't feel like I'm doing MQS right here, I know this gets a little complex but maybe someone can point out where I'm going totally wrong.

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  • What are the safety benefits of a type system?

    - by vandros526
    In Javascript: The Good Parts by Douglas Crockford, he mentions in his inheritance chapter, "The other benefit of classical inheritance is that it includes the specification of a system of types. This mostly frees the programmer from having to write explicit casting operations, which is a very good thing because when casting, the safety benefits of a type system are lost." So first of all, what actually is safety? protection against data corruption, or hackers, or system malfunctions, etc? What are the safety benefits of a type system? What makes a type system different that allows it to provide these safety benefits?

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  • Why not have a High Level Language based OS? Are Low Level Languages more efficient?

    - by rtindru
    Without being presumptuous, I would like you to consider the possibility of this. Most OS today are based on pretty low level languages (mainly C/C++) Even the new ones such as Android uses JNI & underlying implementation is in C In fact, (this is a personal observation) many programs written in C run a lot faster than their high level counterparts (eg: Transmission (a bittorrent client on Ubuntu) is a whole lot faster than Vuze(Java) or Deluge(Python)). Even python compilers are written in C, although PyPy is an exception. So is there a particular reason for this? Why is it that all our so called "High Level Languages" with the great "OOP" concepts can't be used in making a solid OS? So I have 2 questions basically. Why are applications written in low level languages more efficient than their HLL counterparts? Do low level languages perform better for the simple reason that they are low level and are translated to machine code easier? Why do we not have a full fledged OS based entirely on a High Level Language?

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  • Recording Available: March 2012 Quarterly Customer Update Webcast

    - by John Klinke
    Missed the recent Quarterly Customer Update Webcast? We covered several topics including: * WebCenter 4 Pillars overview * Support Update * WebCenter Content 11gR1 Update * WebCenter Portal 11gR1 Update * Oracle Social Network Overview VIEW WEBCAST RECORDING: Access the March 2012 Webcast recording and presentation by going to: My Oracle Support Site Note: 568127.1 We'll announce the next Quarterly Customer Update Webcast here on the WebCenter Content Alerts blog.

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  • How can calculus and linear algebra be useful to a system programmer?

    - by Victor
    I found a website saying that calculus and linear algebra are necessary for System Programming. System Programming, as far as I know, is about osdev, drivers, utilities and so on. I just can't figure out how calculus and linear algebra can be helpful on that. I know that calculus has several applications in science, but in this particular field of programming I just can't imagine how calculus can be so important. The information was on this site: http://www.wikihow.com/Become-a-Programmer Edit: Some answers here are explaining about algorithm complexity and optimization. When I made this question I was trying to be more specific about the area of System's Programming. Algorithm complexity and optimization can be applied to any area of programming not just System's Programming. That may be why I wasn't able to came up with such thinking at the time of the question.

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  • File system implementation in MongoDB with GridFS

    - by Ralph
    I am working on two projects that will both implement a Webdav server backed by a MongoDB GridFS. In each case, there is the potential for the system to store tens of millions of files spread across thousands of hierarchical directories. I can come up with two different ways of storing the directory structure: As a "true" hierarchical file system, with directories containing the IDs (_id) of subdirectories and regular files. The paths will be separated by slashes (/) as in a POSIX-compliant file system. The path /a/b/c will be represented as a directory a containing a directory b containing a file c. As a flat file system, where file names include the slashes. The path /a/b/c will be stored as a single file with the name /a/b/c What are the advantages and disadvantages of each, with respect to a "real" folder-based file system?

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  • What features of old computers helped you learn to be a better programmer?

    - by David Cary
    What features of old computers helped you learn to be a better programmer -- but don't seem to be available on new computers? I imagine that, while educational, you are really glad some features are gone, such as programs ran so slowly that I could almost see each pixel being plotted, so I got a visceral feel for the effect of various optimizations. I imagine other features you may be a little nostalgic for, such as I could turn on the computer, and write a short program that printed "Hello, World" on the printer, before ever "booting" a "disk". (I'm hoping that this is constructive enough to avoid the fate of the " What have we lost from computers 20 years ago ?" question).

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  • Why is filesystem preferred for logs instead of RDBMS?

    - by Yasir
    Question should be clear from its title. For example Apache saves its access and error logs in files instead of RDBMS no matter on how large or small scale it is being utilized. For RDMS we just have to write SQL queries and it will do the work while for files we must decide a particular format and then write regex or may be parsers to manipulate them. And those might even fail in particular circumstances if great care was not paid. Yet everyone seems to prefer filesystem for maintaining the logs. I am not biased against any of these methods but I would like to know why it is practiced like this. Is it speed or maintainability or something else?

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  • Which language is more suitable heavy file tasks?

    - by All
    I need to write a script (based on basic functions) to process /image/audio/video files. The process is mainly filesystem tasks and converts. The database of files has been stored by mysql. The script is simple but cause heavy tasks on the system; for example renaming/converting/copying thousands of file in a run. The script does not read the content of files into memory, it just manage the commands for sub-processes. The main weight is on the communication with filesystem. The script will be used regularly for new files. My concern is about performance. I am thinking of Shell script a complied language like C Please advise which programming language is more suitable for this purpose and why? UPDATE: An example is to scan a folder for images, convert them with ImageMagick, move files to destination folder, get file info, then update the database. As you can see, the process has no room for optimization, and most of languages have similar APIs for popular programs like ImageMagick, MySQL, etc. Thus, it can be written in any language. I just wish to reduce resource usage by speeding up the long loop. NOTE: I know that questions about comparing languages are not favorable, but I really had problem to choose, because the problems can appear in action.

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  • SPARC at 25: Past, Present and Future

    - by kgee
    Join us online to celebrate a quarter-century of innovation. Watch Scott McNealy, Bill Joy, and Andy Bechtolsheim along with other significant SPARC contributors discuss the challenges and rewards of consistently redefining the limits of enterprise IT. Hear Mark Hurd and John Fowler talk about the aggressive plans for SPARC’s future. All of this was recently captured in video at the SPARC anniversary event held at the Computer History Museum in Mountain View, California. In addition to getting unique insights from the people behind 25 years of SPARC technology, you can access exclusive content and resources, read case studies and e-Books, view webcasts and infographics, and more. Be sure to take some time to rediscover why and how SPARC was developed, the considerable impact it had on the entire IT industry, and the continuing innovations coming in the future.http://www.oracle.com/go/?&Src=7618691&Act=721&pcode=WWMK12044691MPP051

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  • 8 Reasons to Attend Oracle OpenWorld 2012

    - by kgee
    Every year, the Oracle Hardware team recognizes the unique buzz that accompanies the season of OpenWorld. During the late nights kept possible by the grace of caffeine combined with the stress and eagerness for the event to run smoothly, we like to remind ourselves of why all our hard work is going to pay off. So, now that we've registered, here are some of our top reasons that we’re excited for Oracle OpenWorld 2012: The KeynotesJust to name a few...Larry Ellison, Mark Hurd, Thomas Kurian, John Fowler and many more are speaking live. We're expecting to walk away from the keynotes with a new frame of reference on a vast array of hot topics. NetworkingWhether it's through means of the OpenWorld Lounges, social media, or bars and cafes around Moscone Center, we'll be surrounded by people who are experts in the hardware field. Hardware SessionsThere are enough sessions to satisfy every Oracle hardware knowledge need. Hardware Experts in GeneralSo many experts that we wish we could be in two places at once sometimes. Pearl Jam & Kings of LeonRock out with these two legendary bands at the Oracle Appreciation Event! Oracle Music FestivalJoss Stone, Macy Gray, the Hives, and Jimmy Cliff will be welcome escapes at the end of each day at OpenWorld, and are just a couple more reasons these all nighters before OpenWorld are worth it. ORACLE TEAM USA and the America's Cup trophyAfter the sailors take on San Francisco Bay for Fleet Week, we’ll be soliciting them for autographs and taking pictures with them at OpenWorld. Location, Location, LocationThe Moscone Center is beautiful and in the best location in San Francisco. We know the OpenWorld hype will get to us sometimes, and it's nice to know that we have pretty much everything San Francisco has to offer at our finger tips. Why are you excited for #OOW? Tell us why!

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  • Session serialization in JavaEE environment

    - by Ionut
    Please consider the following scenario: We are working on a JavaEE project for which the scalability starts to become an issue. Up until now, we were able to scale up but this is no longer an option. Therefore we need to consider scaling out and preparing the App for a clustered environment. Our main concern right now is serializing the user sessions. Sadly, we did not consider from the beginning the issue and we are encountering the following excetion: java.io.WriteAbortedException: writing aborted; java.io.NotSerializableException: org.apache.catalina.session.StandardSessionFacade I did some research and this exception is thrown because there are objects stored on the session which does not implement the Serializable interface. Considering that all over the app there are quite a few custom objects which are stored on the session without implementing this interface, it would require a lot of tedious work and dedication to fix all these classes declaration. We will fix all this declarations but the main concern is that, in the future, there may be a developer which will add a non Serializable object on the session and break the session serialization & replication over multiple nodes. As a quick overview of the project, we are developing using a home grown framework based on Struts 1 with the Servlet 3.0 API. This means that at this point, we are using the standard session.getAttribute() and session.setAttribute() to work with the session and the session handling is scattered all over the code base. Besides updating the classes of the objects stored on session and making sure that they implement the Serializable interface, what other measures of precaution should we take in order to ensure a reliable Session replication capability on the Application layer? I know it is a little bit late to consider this but what would be the best practice in this case? Furthermore, are there any other issues we should consider regarding this transition? Thank you in advance!

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  • Open Grid Engine or Akka/Something more fault tolerant?

    - by Mike Lyons
    My use case is that I have a pipeline of independent, stand alone programs, that I want to execute in a certain order on specific pieces of data that our output from previous pipeline stages. The pipeline is entirely linear and doesn't do anything in terms of alternate paths through the pipe. I'm currently using SGE to do this and it works OK, however occasionally a job will overstep it's memory bounds, fail, and all jobs that require that output data will fail. The pipe needs to be restarted in that case, and it seems that whatever is providing the fault tolerance in akka might solve that for me?

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  • What is wrong with Unix/linux

    - by John Smith
    This is a genuine question motivated by Ideal Operating System When I moved from DOS to Linux in the late 90s it was an eye opener for me. Long file names, arbitrarily many extensions etc... Now I look at Linux and Unix and see all sorts of issues. Here are things I see which could be fixed. Too much depends on root, and rootly powers cannot be voluntarily delegated over several users. (I would love to give up my power to manager printers and delegate the job to another account) File permissions are very limited, and there is not much metadata to go with files. The "everything is a file" metaphor is not true, Plan 9 gets it right(er).

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  • what exactly is system programming?

    - by kentjh
    I have never understood what system programming meant. The usual definition given is "...doing something close to the Os or extending Os features...". Does using Windows API directly rather than some libraries to say do file i/o make it system programming? Was writing Android OS system programming? If I write something that would expose linux kernel through a console like app on Android am I doing system programming? If I am writing software to control a washing machine am I writing system programming? I am a beginner in programming and this is confusing me to no end. Please explain contrasting it with "application programming".

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  • Know Thy Operating System?

    - by AdityaGameProgrammer
    As developers how much time, or do you spend time, In learning the hidden features tricks of your operating system ? How important do you feel is this for productivity in day to day programming? tasks. What do you mean when you list knowledge of an OS in your resume? What are your favorite hidden -less known features For example: A common problem of How can i open the cmd window in a specific location a do it yourself solution in say xp and what to do if something breaks Are these something you look into as and when you find the need to do so?

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  • Finding duplicate files?

    - by ub3rst4r
    I am going to be developing a program that detects duplicate files and I was wondering what the best/fastest method would be to do this? I am more interested in what the best hash algorithm would be to do this? For example, I was thinking of having it get the hash of each files contents and then group the hashes that are the same. Also, should there be a limit set for what the maximum file size can be or is there a hash that is suitable for large files?

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  • *Hidden Features* in your operating system that increase productivity?

    - by AdityaGameProgrammer
    As developers how much time, or do you spend time, In learning the hidden features tricks of your operating system ? How important do you feel is this for productivity in day to day programming? tasks. What do you mean when you list knowledge of an OS in your resume? What are your most useful hidden -less known features For example: A common problem of How can i open the cmd window in a specific location a do it yourself solution in say xp and what to do if something breaks Or are these something you look into as and when you find the need to do so?

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  • Developing a computer system based on Nand2Tetris [on hold]

    - by Ryan
    I recently finished a book called Nand2Tetris (nand2tetris.org) where I built my own computer system from scratch with its own machine language, assembly code, and a high level language called Jack that's translated to Hack binary. However, I feel like the "computer" I built throughout the course of this book (called the Hack computer) is a bit too simple for various reasons: 1) There are only two registers (D and A), whereas most computers have much more 2) Peripheral devices like mouse and keyboard have to be directly implemented 3) Peripheral devices use a pre-planned shared memory map to communicate with the CPU instead of using interrupts (which aren't covered at all) 4) Jack (the high level language) code doesn't compile to Assembly code directly, instead it compiles to an intermediate language, which in turn gets translated to Assembly. 5) There is no ROM or permanent storage device, everything is stored in RAM 6) No support for colored monitor, networking or sound I would like to build a more complicated computer system now based on what I've learned from Nand2Tetris. Does anyone know of any good resources or books to get started on this? (BTW by computer system I mean software that can emulate the hardware of a virtual computer with its own unique instruction set)

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  • Is it safe to convert Windows file paths to Unix file paths with a simple replace?

    - by MxyL
    So for example say I had it so that all of my files will be transferred from a windows machine to a unix machine as such: C:\test\myFile.txt to {somewhere}/test/myFile.txt (drive letter is irrelevant at this point). Currently, our utility library that we wrote ourselves provides a method that does a simple replace of all back slashes with forward slashes: public String normalizePath(String path) { return path.replaceAll("\\", "/"); } Slashes are reserved and cannot be part of a file name, so the directory structure should be preserved. However, I'm not sure if there are other complications between windows and unix paths that I may need to worry about (eg: non-ascii names, etc)

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