batch processing - Page 124

PreparedStatement and 'null' value in WHERE clause

- by bond

I am using PrepareStatement and BatchUpdate for executimg a UPDATE query. In for loop I create a Batch. At end of loop I execute batch. Above logic works fine if SQL query used in PrepareStatement does not have null values in WHERE claues. Update Statement fails if there is null value in WHERE clasue. My code looks something like this, connection = getConnection(); PreparedStatement ps = connection.prepareStatement("UPDATE TEST_TABLE SET Col1 = true WHERE Col2 = ? AND Col3 = ?") for (Data aa : InComingData) { if(null == aa.getCol2()) { ps.setNull(1, java.sql.Types.INTEGER); } else { ps.setInteger(1,aa.getCol2()) } if(null == aa.getCol3()) { ps.setNull(2, java.sql.Types.INTEGER); } else { ps.setInteger(2,aa.getCol3()) } ps.addBatch(); } ps.executeBatch(); connection.commit(); Any help would be appreciated.

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Excel isn't reading sql exported csv properly

- by mhopkins321

I have a batch file that calls sqlcmd to run a command and then export the data as a csv. When viewed in a cell the trasancted date for example shows 35:30.0 but if you click on it the formula bar shows 1/1/1900 2:45:00 PM. I need the full timestamp to show in the cell. Any ideas? The batch file is the following sqlcmd -S server -U username -P password -d database -i "D:\path\sqlScript.sql" -s "," > D:\path\report.csv -I -W -k 1 The script is the following. Now I currently have them cast as varchars, but that's simply because i've tried to change it a bit. Varchar doesn't work either. SET NOCOUNT ON; select top(10)BO.Status, cast(tradeDate AS varchar) AS Trade_Date, CAST(closingTime AS varchar) AS Closing_Time, CAST(openingTime AS varchar) AS openingTime FROM GIANT COMPLICATED JOINS OF ALL SORTS OF TABLES

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Non-blocking service to receive messages on port via UDP

- by stUrb

I want to build a service on my Linux VPS which listens to a certain UDP port and does something with the (text)message which is captured. This processing consists of appending the message to a locally stored txt-file and send it as http, with a post variable to another server. I've looked into Nginx but as far is can see this server can only be bound to receive http packets. Although it is asynchronous. What is the best way to achieve this listening-service on linux? And which has the capabilities to do the above mentioned processing?

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Has Javascript developed beyond what it was originally designed to do?

- by Elliot Bonneville

I've been talking with a friend about the purpose of Javascript, when and how it should be used, etc. He quoted that: JavaScript was designed to add interactivity to HTML pages [...] JavaScript gives HTML designers a programming tool HTML authors are normally not programmers, but JavaScript is a scripting language with a very simple syntax! Almost anyone can put small "snippets" of code into their HTML pages JavaScript can react to events A JavaScript can be set to execute when something happens, like when a page has finished loading or when a user clicks on an HTML element JavaScript can read and write HTML elements A JavaScript can read and change the content of an HTML element JavaScript can be used to validate data A JavaScript can be used to validate form data before it is submitted to a server. This saves the server from extra processing JavaScript can be used to detect the visitor's browser - A JavaScript can be used to detect the visitor's browser, and - depending on the browser - load another page specifically designed for that browser. JavaScript can be used to create cookies - A JavaScript can be used to store and retrieve information on the visitor's computer. However, it seems like Javascript's getting used to do a lot more than these days. My friend also advocates against using Javascript's OOP functionality, claiming that "you shouldn't be processing data, merely validating." Is Javascript really limited to validating data and making flashy graphics on a web page? He goes on to claim "you shouldn't be attempting to access databases through javascript" and also says " in general you don't want to be doing your heavy lifting in javascript". I can't say I agree with his opinion, but I'd like to get some more input on this. So, my question: Has Javascript evolved from the definition above to something more powerful, has the way we use it changed, or am I just plain wrong? While I realize this is a subjective question, I can't find any more information on it, so a few links would be good, if nothing else. I'm not looking for a debate, just an answer.

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Quantal: Broken apt-index, cant fix dependencies

- by arcyqwerty

I can't seem to add/remove/update packages Ubuntu software update has a notice about partial upgrades but fails Seems to be similar to this problem $ sudo apt-get update Ign http://archive.ubuntu.com quantal InRelease Ign http://security.ubuntu.com precise-security InRelease Ign http://us.archive.ubuntu.com precise InRelease Ign http://extras.ubuntu.com precise InRelease Ign http://us.archive.ubuntu.com precise-updates InRelease Ign http://us.archive.ubuntu.com precise-backports InRelease Ign http://ppa.launchpad.net precise InRelease Ign http://archive.canonical.com precise InRelease Ign http://ppa.launchpad.net precise InRelease Ign http://ppa.launchpad.net precise InRelease Hit http://archive.ubuntu.com quantal Release.gpg Get:1 http://security.ubuntu.com precise-security Release.gpg [198 B] Hit http://extras.ubuntu.com precise Release.gpg Get:2 http://us.archive.ubuntu.com precise Release.gpg [198 B] Get:3 http://us.archive.ubuntu.com precise-updates Release.gpg [198 B] Hit http://archive.canonical.com precise Release.gpg Hit http://ppa.launchpad.net precise Release.gpg Hit http://ppa.launchpad.net precise Release.gpg Hit http://archive.ubuntu.com quantal Release Get:4 http://security.ubuntu.com precise-security Release [49.6 kB] Get:5 http://us.archive.ubuntu.com precise-backports Release.gpg [198 B] Get:6 http://us.archive.ubuntu.com precise Release [49.6 kB] Hit http://extras.ubuntu.com precise Release Hit http://archive.canonical.com precise Release Hit http://ppa.launchpad.net precise Release.gpg Hit http://ppa.launchpad.net precise Release Hit http://archive.ubuntu.com quantal/main amd64 Packages Hit http://extras.ubuntu.com precise/main Sources Hit http://archive.canonical.com precise/partner Sources Hit http://ppa.launchpad.net precise Release Hit http://ppa.launchpad.net precise Release Get:7 http://us.archive.ubuntu.com precise-updates Release [49.6 kB] Hit http://extras.ubuntu.com precise/main amd64 Packages Hit http://extras.ubuntu.com precise/main i386 Packages Hit http://archive.ubuntu.com quantal/main i386 Packages Hit http://archive.ubuntu.com quantal/main Translation-en Hit http://archive.canonical.com precise/partner amd64 Packages Hit http://archive.canonical.com precise/partner i386 Packages Hit http://ppa.launchpad.net precise/main Sources Hit http://ppa.launchpad.net precise/main amd64 Packages Hit http://ppa.launchpad.net precise/main i386 Packages Get:8 http://us.archive.ubuntu.com precise-backports Release [49.6 kB] Hit http://ppa.launchpad.net precise/main Sources Get:9 http://security.ubuntu.com precise-security/main Sources [22.5 kB] Hit http://ppa.launchpad.net precise/main amd64 Packages Hit http://ppa.launchpad.net precise/main i386 Packages Hit http://ppa.launchpad.net precise/main Sources Hit http://ppa.launchpad.net precise/main amd64 Packages Hit http://ppa.launchpad.net precise/main i386 Packages Get:10 http://us.archive.ubuntu.com precise/main Sources [934 kB] Get:11 http://security.ubuntu.com precise-security/restricted Sources [14 B] Get:12 http://security.ubuntu.com precise-security/universe Sources [7,832 B] Ign http://archive.ubuntu.com quantal/main Translation-en_US Get:13 http://security.ubuntu.com precise-security/multiverse Sources [713 B] Get:14 http://security.ubuntu.com precise-security/main amd64 Packages [67.8 kB] Ign http://archive.canonical.com precise/partner Translation-en_US Get:15 http://security.ubuntu.com precise-security/restricted amd64 Packages [14 B] Get:16 http://security.ubuntu.com precise-security/universe amd64 Packages [18.8 kB] Ign http://extras.ubuntu.com precise/main Translation-en_US Ign http://archive.canonical.com precise/partner Translation-en Get:17 http://security.ubuntu.com precise-security/multiverse amd64 Packages [1,155 B] Get:18 http://security.ubuntu.com precise-security/main i386 Packages [70.2 kB] Ign http://extras.ubuntu.com precise/main Translation-en Ign http://ppa.launchpad.net precise/main Translation-en_US Get:19 http://security.ubuntu.com precise-security/restricted i386 Packages [14 B] Get:20 http://security.ubuntu.com precise-security/universe i386 Packages [19.0 kB] Get:21 http://security.ubuntu.com precise-security/multiverse i386 Packages [1,394 B] Ign http://ppa.launchpad.net precise/main Translation-en Hit http://security.ubuntu.com precise-security/main Translation-en Hit http://security.ubuntu.com precise-security/multiverse Translation-en Hit http://security.ubuntu.com precise-security/restricted Translation-en Ign http://ppa.launchpad.net precise/main Translation-en_US Ign http://ppa.launchpad.net precise/main Translation-en Ign http://ppa.launchpad.net precise/main Translation-en_US Ign http://ppa.launchpad.net precise/main Translation-en Hit http://security.ubuntu.com precise-security/universe Translation-en Ign http://security.ubuntu.com precise-security/main Translation-en_US Ign http://security.ubuntu.com precise-security/multiverse Translation-en_US Ign http://security.ubuntu.com precise-security/restricted Translation-en_US Ign http://security.ubuntu.com precise-security/universe Translation-en_US Get:22 http://us.archive.ubuntu.com precise/restricted Sources [5,470 B] Get:23 http://us.archive.ubuntu.com precise/universe Sources [5,019 kB] Get:24 http://us.archive.ubuntu.com precise/multiverse Sources [155 kB] Get:25 http://us.archive.ubuntu.com precise/main amd64 Packages [1,273 kB] Get:26 http://us.archive.ubuntu.com precise/restricted amd64 Packages [8,452 B] Get:27 http://us.archive.ubuntu.com precise/universe amd64 Packages [4,786 kB] Get:28 http://us.archive.ubuntu.com precise/multiverse amd64 Packages [119 kB] Get:29 http://us.archive.ubuntu.com precise/main i386 Packages [1,274 kB] Get:30 http://us.archive.ubuntu.com precise/restricted i386 Packages [8,431 B] Get:31 http://us.archive.ubuntu.com precise/universe i386 Packages [4,796 kB] Get:32 http://us.archive.ubuntu.com precise/multiverse i386 Packages [121 kB] Hit http://us.archive.ubuntu.com precise/main Translation-en Hit http://us.archive.ubuntu.com precise/multiverse Translation-en Hit http://us.archive.ubuntu.com precise/restricted Translation-en Hit http://us.archive.ubuntu.com precise/universe Translation-en Get:33 http://us.archive.ubuntu.com precise-updates/main Sources [124 kB] Get:34 http://us.archive.ubuntu.com precise-updates/restricted Sources [1,379 B] Get:35 http://us.archive.ubuntu.com precise-updates/universe Sources [30.9 kB] Get:36 http://us.archive.ubuntu.com precise-updates/multiverse Sources [1,058 B] Get:37 http://us.archive.ubuntu.com precise-updates/main amd64 Packages [311 kB] Get:38 http://us.archive.ubuntu.com precise-updates/restricted amd64 Packages [2,417 B] Get:39 http://us.archive.ubuntu.com precise-updates/universe amd64 Packages [85.4 kB] Get:40 http://us.archive.ubuntu.com precise-updates/multiverse amd64 Packages [1,829 B] Get:41 http://us.archive.ubuntu.com precise-updates/main i386 Packages [314 kB] Get:42 http://us.archive.ubuntu.com precise-updates/restricted i386 Packages [2,439 B] Get:43 http://us.archive.ubuntu.com precise-updates/universe i386 Packages [85.9 kB] Get:44 http://us.archive.ubuntu.com precise-updates/multiverse i386 Packages [2,047 B] Hit http://us.archive.ubuntu.com precise-updates/main Translation-en Hit http://us.archive.ubuntu.com precise-updates/multiverse Translation-en Hit http://us.archive.ubuntu.com precise-updates/restricted Translation-en Hit http://us.archive.ubuntu.com precise-updates/universe Translation-en Get:45 http://us.archive.ubuntu.com precise-backports/main Sources [1,845 B] Get:46 http://us.archive.ubuntu.com precise-backports/restricted Sources [14 B] Get:47 http://us.archive.ubuntu.com precise-backports/universe Sources [11.1 kB] Get:48 http://us.archive.ubuntu.com precise-backports/multiverse Sources [1,383 B] Get:49 http://us.archive.ubuntu.com precise-backports/main amd64 Packages [1,271 B] Get:50 http://us.archive.ubuntu.com precise-backports/restricted amd64 Packages [14 B] Get:51 http://us.archive.ubuntu.com precise-backports/universe amd64 Packages [9,701 B] Get:52 http://us.archive.ubuntu.com precise-backports/multiverse amd64 Packages [996 B] Get:53 http://us.archive.ubuntu.com precise-backports/main i386 Packages [1,271 B] Get:54 http://us.archive.ubuntu.com precise-backports/restricted i386 Packages [14 B] Get:55 http://us.archive.ubuntu.com precise-backports/universe i386 Packages [9,703 B] Get:56 http://us.archive.ubuntu.com precise-backports/multiverse i386 Packages [999 B] Hit http://us.archive.ubuntu.com precise-backports/main Translation-en Hit http://us.archive.ubuntu.com precise-backports/multiverse Translation-en Hit http://us.archive.ubuntu.com precise-backports/restricted Translation-en Hit http://us.archive.ubuntu.com precise-backports/universe Translation-en Ign http://us.archive.ubuntu.com precise/main Translation-en_US Ign http://us.archive.ubuntu.com precise/multiverse Translation-en_US Ign http://us.archive.ubuntu.com precise/restricted Translation-en_US Ign http://us.archive.ubuntu.com precise/universe Translation-en_US Ign http://us.archive.ubuntu.com precise-updates/main Translation-en_US Ign http://us.archive.ubuntu.com precise-updates/multiverse Translation-en_US Ign http://us.archive.ubuntu.com precise-updates/restricted Translation-en_US Ign http://us.archive.ubuntu.com precise-updates/universe Translation-en_US Ign http://us.archive.ubuntu.com precise-backports/main Translation-en_US Ign http://us.archive.ubuntu.com precise-backports/multiverse Translation-en_US Ign http://us.archive.ubuntu.com precise-backports/restricted Translation-en_US Ign http://us.archive.ubuntu.com precise-backports/universe Translation-en_US Fetched 19.9 MB in 34s (571 kB/s) Reading package lists... Done $ sudo apt-get upgrade Reading package lists... Done Building dependency tree Reading state information... Done You might want to run 'apt-get -f install' to correct these. The following packages have unmet dependencies: netbase : Breaks: ifupdown (< 0.7) Breaks: ifupdown:i386 (< 0.7) E: Unmet dependencies. Try using -f. $ sudo apt-get -f install Reading package lists... Done Building dependency tree Reading state information... Done Correcting dependencies... Done The following packages were automatically installed and are no longer required: dh-apparmor html2text libmail-sendmail-perl libsys-hostname-long-perl Use 'apt-get autoremove' to remove them. The following extra packages will be installed: ifupdown Suggested packages: rdnssd The following packages will be upgraded: ifupdown 1 upgraded, 0 newly installed, 0 to remove and 1179 not upgraded. 85 not fully installed or removed. Need to get 0 B/54.1 kB of archives. After this operation, 19.5 kB of additional disk space will be used. Do you want to continue [Y/n]? (Reading database ... 222498 files and directories currently installed.) Preparing to replace ifupdown 0.7~beta2ubuntu8 (using .../ifupdown_0.7.1ubuntu1_amd64.deb) ... Unpacking replacement ifupdown ... dpkg: error processing /var/cache/apt/archives/ifupdown_0.7.1ubuntu1_amd64.deb (--unpack): trying to overwrite '/etc/init.d/networking', which is also in package netbase 5.0ubuntu1 Processing triggers for man-db ... Processing triggers for ureadahead ... Errors were encountered while processing: /var/cache/apt/archives/ifupdown_0.7.1ubuntu1_amd64.deb E: Sub-process /usr/bin/dpkg returned an error code (1) cat /etc/apt/sources.list # deb cdrom:[Ubuntu 12.04 LTS _Precise Pangolin_ - Release amd64 (20120425)]/ dists/precise/main/binary-i386/ # deb cdrom:[Ubuntu 12.04 LTS _Precise Pangolin_ - Release amd64 (20120425)]/ dists/precise/restricted/binary-i386/ # deb cdrom:[Ubuntu 12.04 LTS _Precise Pangolin_ - Release amd64 (20120425)]/ precise main restricted # See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to # newer versions of the distribution. deb http://us.archive.ubuntu.com/ubuntu/ precise main restricted deb-src http://us.archive.ubuntu.com/ubuntu/ precise main restricted ## Major bug fix updates produced after the final release of the ## distribution. deb http://us.archive.ubuntu.com/ubuntu/ precise-updates main restricted deb-src http://us.archive.ubuntu.com/ubuntu/ precise-updates main restricted ## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu ## team. Also, please note that software in universe WILL NOT receive any ## review or updates from the Ubuntu security team. deb http://us.archive.ubuntu.com/ubuntu/ precise universe deb-src http://us.archive.ubuntu.com/ubuntu/ precise universe deb http://us.archive.ubuntu.com/ubuntu/ precise-updates universe deb-src http://us.archive.ubuntu.com/ubuntu/ precise-updates universe ## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu ## team, and may not be under a free licence. Please satisfy yourself as to ## your rights to use the software. Also, please note that software in ## multiverse WILL NOT receive any review or updates from the Ubuntu ## security team. deb http://us.archive.ubuntu.com/ubuntu/ precise multiverse deb-src http://us.archive.ubuntu.com/ubuntu/ precise multiverse deb http://us.archive.ubuntu.com/ubuntu/ precise-updates multiverse deb-src http://us.archive.ubuntu.com/ubuntu/ precise-updates multiverse ## N.B. software from this repository may not have been tested as ## extensively as that contained in the main release, although it includes ## newer versions of some applications which may provide useful features. ## Also, please note that software in backports WILL NOT receive any review ## or updates from the Ubuntu security team. deb http://us.archive.ubuntu.com/ubuntu/ precise-backports main restricted universe multiverse deb-src http://us.archive.ubuntu.com/ubuntu/ precise-backports main restricted universe multiverse deb http://security.ubuntu.com/ubuntu precise-security main restricted deb-src http://security.ubuntu.com/ubuntu precise-security main restricted deb http://security.ubuntu.com/ubuntu precise-security universe deb-src http://security.ubuntu.com/ubuntu precise-security universe deb http://security.ubuntu.com/ubuntu precise-security multiverse deb-src http://security.ubuntu.com/ubuntu precise-security multiverse ## Uncomment the following two lines to add software from Canonical's ## 'partner' repository. ## This software is not part of Ubuntu, but is offered by Canonical and the ## respective vendors as a service to Ubuntu users. deb http://archive.canonical.com/ubuntu precise partner deb-src http://archive.canonical.com/ubuntu precise partner ## This software is not part of Ubuntu, but is offered by third-party ## developers who want to ship their latest software. deb http://extras.ubuntu.com/ubuntu precise main deb-src http://extras.ubuntu.com/ubuntu precise main deb http://archive.ubuntu.com/ubuntu/ quantal main

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Postgresql fails to start on Ubuntu 10.04.4 LTS

- by cancerballs

I installed postgresql 9.2 from add-apt-repository ppa:pitti/postgresql using apt-get install postgresql-9.2 At the end of the install and every time I try to launch postgresql by using the following command /etc/init.d/postgresql start or service postgresql start I get this error: Error: could not exec /usr/lib/postgresql/9.2/bin/pg_ctl /usr/lib/postgresql/9.2/bin/pg_ctl start -D /var/lib/postgresql/9.2/main -l /var/log/postgresql/postgresql-9.2-main.log -s -o -c config_file="/etc/postgresql/9.2/main/postgresql.conf" : [fail] invoke-rc.d: initscript postgresql, action "start" failed. dpkg: error processing postgresql-9.2 (--configure): subprocess installed post-installation script returned error exit status 1 Errors were encountered while processing: postgresql-9.2 E: Sub-process /usr/bin/dpkg returned an error code (1) I have tried everything found here: How to thoroughly purge and reinstall postgresql on ubuntu and here: Eliminating non working postgresql installations on ubuntu 10-04 and starting af. I have also done dpkg -P --force-remove-reinstreq postgresql-client-9.2 in my attempt to remove everything postgres related from my server. After removing postgresql I have used dpkg --get-selections | grep postg To be sure there is nothing left and I can do a clean install. I have also made sure that the files and folders mentioned in the error message have the right permissions. The /var/log/postgresql/postgresql-9.2-main.log file is empty. I have tried installing every postgresql version from 8.3 to 9.2 and I get the same error on every time. I once managed to compile postgresql from the source provided on their website but then I encountered weird errors with psycopg2 so I figured I'd install postgresql this way and avoid those errors. Also when I type apt-get install postgresql it by default tries to install the 8.3 version even when I can find the package by typing apt-get install postgresql-9.2.

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Parallelism in .NET – Introduction

- by Reed

Parallel programming is something that every professional developer should understand, but is rarely discussed or taught in detail in a formal manner. Software users are no longer content with applications that lock up the user interface regularly, or take large amounts of time to process data unnecessarily. Modern development requires the use of parallelism. There is no longer any excuses for us as developers. Learning to write parallel software is challenging. It requires more than reading that one chapter on parallelism in our programming language book of choice… Today’s systems are no longer getting faster with each generation; in many cases, newer computers are actually slower than previous generation systems. Modern hardware is shifting towards conservation of power, with processing scalability coming from having multiple computer cores, not faster and faster CPUs. Our CPU frequencies no longer double on a regular basis, but Moore’s Law is still holding strong. Now, however, instead of scaling transistors in order to make processors faster, hardware manufacturers are scaling the transistors in order to add more discrete hardware processing threads to the system. This changes how we should think about software. In order to take advantage of modern systems, we need to redesign and rewrite our algorithms to work in parallel. As with any design domain, it helps tremendously to have a common language, as well as a common set of patterns and tools. For .NET developers, this is an exciting time for parallel programming. Version 4 of the .NET Framework is adding the Task Parallel Library. This has been back-ported to .NET 3.5sp1 as part of the Reactive Extensions for .NET, and is available for use today in both .NET 3.5 and .NET 4.0 beta. In order to fully utilize the Task Parallel Library and parallelism, both in .NET 4 and previous versions, we need to understand the proper terminology. For this series, I will provide an introduction to some of the basic concepts in parallelism, and relate them to the tools available in .NET.

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Errors Code: /var/cache/apt/archives/linux-image-3.8.0-19-generic_3.8.0-19.30~precise1_amd64.deb

- by user286682

$ sudo apt-get dist-upgrade Reading package lists... Done Building dependency tree Reading state information... Done Calculating upgrade... Done The following packages will be upgraded: linux-image-3.8.0-19-generic 1 upgraded, 0 newly installed, 0 to remove and 0 not upgraded. 6 not fully installed or removed. Need to get 0 B/47.8 MB of archives. After this operation, 142 MB of additional disk space will be used. Do you want to continue [Y/n]? y (Reading database ... 164064 files and directories currently installed.) Preparing to replace linux-image-3.8.0-19-generic 3.8.0-19.29 (using .../linux-image-3.8.0-19-generic_3.8.0-19.30~precise1_amd64.deb) ... Done. Unpacking replacement linux-image-3.8.0-19-generic ... dpkg: error processing /var/cache/apt/archives/linux-image-3.8.0-19-generic_3.8.0-19.30~precise1_amd64.deb (--unpack): trying to overwrite '/lib/modules/3.8.0-19-generic/kernel/arch/x86/kvm/kvm-intel.ko', which is also in package linux-image-extra-3.8.0-19-generic 3.8.0-19.29 dpkg-deb: error: subprocess paste was killed by signal (Broken pipe) Examining /etc/kernel/postrm.d . run-parts: executing /etc/kernel/postrm.d/initramfs-tools 3.8.0-19-generic /boot/vmlinuz-3.8.0-19-generic run-parts: executing /etc/kernel/postrm.d/zz-update-grub 3.8.0-19-generic /boot/vmlinuz-3.8.0-19-generic Errors were encountered while processing: /var/cache/apt/archives/linux-image-3.8.0-19-generic_3.8.0-19.30~precise1_amd64.deb E: Sub-process /usr/bin/dpkg returned an error code (1) How can I get this update to work?

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Java installation problem

- by Zxy

I cannot install java on my ubuntu 12.04: zero@ghostrider:~$ sudo apt-get purge openjdk* [sudo] password for zero: Reading package lists... Done Building dependency tree Reading state information... Done Note, selecting 'openjdk-6-demo' for regex 'openjdk*' Note, selecting 'openjdk-7-jre-headless' for regex 'openjdk*' Note, selecting 'uwsgi-plugin-jwsgi-openjdk-6' for regex 'openjdk*' Note, selecting 'openjdk-jre' for regex 'openjdk*' Note, selecting 'openjdk-7-source' for regex 'openjdk*' Note, selecting 'openjdk-6-dbg' for regex 'openjdk*' Note, selecting 'openjdk7-jdk' for regex 'openjdk*' Note, selecting 'openjdk-6-doc' for regex 'openjdk*' Note, selecting 'openjdk-7-jre-zero' for regex 'openjdk*' Note, selecting 'openjdk-7-demo' for regex 'openjdk*' Note, selecting 'openjdk-6-jre-headless' for regex 'openjdk*' Note, selecting 'openjdk-6-jdk' for regex 'openjdk*' Note, selecting 'openjdk-6-jre' for regex 'openjdk*' Note, selecting 'openjdk-6-jre-lib' for regex 'openjdk*' Note, selecting 'openjdk-6-jre-zero' for regex 'openjdk*' Note, selecting 'openjdk-7-dbg' for regex 'openjdk*' Note, selecting 'openjdk-7-doc' for regex 'openjdk*' Note, selecting 'openjdk-7-jdk' for regex 'openjdk*' Note, selecting 'openjdk-7-jre' for regex 'openjdk*' Note, selecting 'openjdk-6-source' for regex 'openjdk*' Note, selecting 'openjdk-7-jre-lib' for regex 'openjdk*' Note, selecting 'uwsgi-plugin-jvm-openjdk-6' for regex 'openjdk*' Package uwsgi-plugin-jvm-openjdk-6 is not installed, so not removed Package uwsgi-plugin-jwsgi-openjdk-6 is not installed, so not removed Package openjdk-6-dbg is not installed, so not removed Package openjdk-6-demo is not installed, so not removed Package openjdk-6-doc is not installed, so not removed Package openjdk-6-jdk is not installed, so not removed Package openjdk-6-jre is not installed, so not removed Package openjdk-6-jre-headless is not installed, so not removed Package openjdk-6-jre-lib is not installed, so not removed Package openjdk-6-source is not installed, so not removed Package openjdk-6-jre-zero is not installed, so not removed Package openjdk-7-dbg is not installed, so not removed Package openjdk-7-demo is not installed, so not removed Package openjdk-7-doc is not installed, so not removed Package openjdk-7-jdk is not installed, so not removed Package openjdk-7-jre is not installed, so not removed Package openjdk-7-jre-headless is not installed, so not removed Package openjdk-7-jre-lib is not installed, so not removed Package openjdk-7-jre-zero is not installed, so not removed Package openjdk-7-source is not installed, so not removed 0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded. 1 not fully installed or removed. After this operation, 0 B of additional disk space will be used. Setting up oracle-java7-installer (7u3-0~eugenesan~precise4) ... Downloading... --2012-06-11 23:56:42-- http://download.oracle.com/otn-pub/java/jdk/7u3-b04/jdk- 7u3-linux-i586.tar.gz Resolving download.oracle.com (download.oracle.com)... 64.209.77.18 Connecting to download.oracle.com (download.oracle.com)|64.209.77.18|:80... connected. HTTP request sent, awaiting response... 302 Moved Temporarily Location: https://edelivery.oracle.com/otn-pub/java/jdk/7u3-b04/jdk-7u3-linux-i586.tar.gz [following] --2012-06-11 23:56:42-- https://edelivery.oracle.com/otn-pub/java/jdk/7u3-b04/jdk-7u3-linux-i586.tar.gz Resolving edelivery.oracle.com (edelivery.oracle.com)... 95.101.122.174 Connecting to edelivery.oracle.com (edelivery.oracle.com)|95.101.122.174|:443... connected. HTTP request sent, awaiting response... 302 Moved Temporarily Location: http://download.oracle.com/errors/download-fail-1505220.html [following] --2012-06-11 23:56:44-- http://download.oracle.com/errors/download-fail-1505220.html Connecting to download.oracle.com (download.oracle.com)|64.209.77.18|:80... connected. HTTP request sent, awaiting response... 200 OK Length: 5307 (5.2K) [text/html] Saving to: `./jdk-7u3-linux-i586.tar.gz' 0K ..... 100% 1007K=0.005s 2012-06-11 23:56:44 (1007 KB/s) - `./jdk-7u3-linux-i586.tar.gz' saved [5307/5307] Download done. sha256sum mismatch jdk-7u3-linux-i586.tar.gz Oracle JDK 7 is NOT installed. dpkg: error processing oracle-java7-installer (--configure): subprocess installed post-installation script returned error exit status 1 No apport report written because MaxReports is reached already Errors were encountered while processing: oracle-java7-installer E: Sub-process /usr/bin/dpkg returned an error code (1) zero@ghostrider:~$ sudo add-apt-repository ppa:eugenesan/java You are about to add the following PPA to your system: More info: https://launchpad.net/~eugenesan/+archive/java Press [ENTER] to continue or ctrl-c to cancel adding it Executing: gpg --ignore-time-conflict --no-options --no-default-keyring --secret- keyring /tmp/tmp.uGcZHfsoNF --trustdb-name /etc/apt/trustdb.gpg --keyring /etc/apt/trusted.gpg --primary-keyring /etc/apt/trusted.gpg --keyserver hkp://keyserver.ubuntu.com:80/ --recv 4346FBB158F4022C896164EEE61380B28313A596 gpg: requesting key 8313A596 from hkp server keyserver.ubuntu.com gpg: key 8313A596: "Launchpad synergy+" not changed gpg: Total number processed: 1 gpg: unchanged: 1 zero@ghostrider:~$ sudo apt-get update Ign http://tr.archive.ubuntu.com precise InRelease Ign http://tr.archive.ubuntu.com precise-updates InRelease Ign http://tr.archive.ubuntu.com precise-backports InRelease Hit http://tr.archive.ubuntu.com precise Release.gpg Hit http://tr.archive.ubuntu.com precise-updates Release.gpg Hit http://tr.archive.ubuntu.com precise-backports Release.gpg Hit http://tr.archive.ubuntu.com precise Release Ign http://extras.ubuntu.com precise InRelease Ign http://security.ubuntu.com precise-security InRelease Hit http://tr.archive.ubuntu.com precise-updates Release Ign http://ppa.launchpad.net precise InRelease Hit http://tr.archive.ubuntu.com precise-backports Release Hit http://tr.archive.ubuntu.com precise/main Sources Hit http://tr.archive.ubuntu.com precise/restricted Sources Hit http://tr.archive.ubuntu.com precise/universe Sources Hit http://tr.archive.ubuntu.com precise/multiverse Sources Hit http://tr.archive.ubuntu.com precise/main i386 Packages Hit http://tr.archive.ubuntu.com precise/restricted i386 Packages Hit http://tr.archive.ubuntu.com precise/universe i386 Packages Hit http://extras.ubuntu.com precise Release.gpg Hit http://ppa.launchpad.net precise Release.gpg Hit http://security.ubuntu.com precise-security Release.gpg Hit http://tr.archive.ubuntu.com precise/multiverse i386 Packages Hit http://tr.archive.ubuntu.com precise/main TranslationIndex Hit http://tr.archive.ubuntu.com precise/multiverse TranslationIndex Hit http://tr.archive.ubuntu.com precise/restricted TranslationIndex Hit http://tr.archive.ubuntu.com precise/universe TranslationIndex Hit http://tr.archive.ubuntu.com precise-updates/main Sources Hit http://tr.archive.ubuntu.com precise-updates/restricted Sources Hit http://tr.archive.ubuntu.com precise-updates/universe Sources Hit http://tr.archive.ubuntu.com precise-updates/multiverse Sources Hit http://tr.archive.ubuntu.com precise-updates/main i386 Packages Hit http://extras.ubuntu.com precise Release Hit http://ppa.launchpad.net precise Release Hit http://security.ubuntu.com precise-security Release Hit http://tr.archive.ubuntu.com precise-updates/restricted i386 Packages Hit http://tr.archive.ubuntu.com precise-updates/universe i386 Packages Hit http://tr.archive.ubuntu.com precise-updates/multiverse i386 Packages Hit http://tr.archive.ubuntu.com precise-updates/main TranslationIndex Hit http://tr.archive.ubuntu.com precise-updates/multiverse TranslationIndex Hit http://tr.archive.ubuntu.com precise-updates/restricted TranslationIndex Hit http://tr.archive.ubuntu.com precise-updates/universe TranslationIndex Hit http://tr.archive.ubuntu.com precise-backports/main Sources Hit http://tr.archive.ubuntu.com precise-backports/restricted Sources Hit http://tr.archive.ubuntu.com precise-backports/universe Sources Hit http://tr.archive.ubuntu.com precise-backports/multiverse Sources Hit http://tr.archive.ubuntu.com precise-backports/main i386 Packages Hit http://tr.archive.ubuntu.com precise-backports/restricted i386 Packages Hit http://tr.archive.ubuntu.com precise-backports/universe i386 Packages Hit http://tr.archive.ubuntu.com precise-backports/multiverse i386 Packages Hit http://tr.archive.ubuntu.com precise-backports/main TranslationIndex Hit http://extras.ubuntu.com precise/main Sources Hit http://ppa.launchpad.net precise/main Sources Hit http://security.ubuntu.com precise-security/main Sources Hit http://tr.archive.ubuntu.com precise-backports/multiverse TranslationIndex Hit http://tr.archive.ubuntu.com precise-backports/restricted TranslationIndex Hit http://tr.archive.ubuntu.com precise-backports/universe TranslationIndex Hit http://tr.archive.ubuntu.com precise/main Translation-en Hit http://tr.archive.ubuntu.com precise/multiverse Translation-en Hit http://extras.ubuntu.com precise/main i386 Packages Ign http://extras.ubuntu.com precise/main TranslationIndex Hit http://tr.archive.ubuntu.com precise/restricted Translation-en Hit http://tr.archive.ubuntu.com precise/universe Translation-en Hit http://tr.archive.ubuntu.com precise-updates/main Translation-en Hit http://tr.archive.ubuntu.com precise-updates/multiverse Translation-en Hit http://tr.archive.ubuntu.com precise-updates/restricted Translation-en Hit http://ppa.launchpad.net precise/main i386 Packages Ign http://ppa.launchpad.net precise/main TranslationIndex Hit http://security.ubuntu.com precise-security/restricted Sources Hit http://security.ubuntu.com precise-security/universe Sources Hit http://security.ubuntu.com precise-security/multiverse Sources Hit http://security.ubuntu.com precise-security/main i386 Packages Hit http://security.ubuntu.com precise-security/restricted i386 Packages Hit http://tr.archive.ubuntu.com precise-updates/universe Translation-en Hit http://tr.archive.ubuntu.com precise-backports/main Translation-en Hit http://tr.archive.ubuntu.com precise-backports/multiverse Translation-en Hit http://tr.archive.ubuntu.com precise-backports/restricted Translation-en Hit http://tr.archive.ubuntu.com precise-backports/universe Translation-en Hit http://security.ubuntu.com precise-security/universe i386 Packages Hit http://security.ubuntu.com precise-security/multiverse i386 Packages Hit http://security.ubuntu.com precise-security/main TranslationIndex Hit http://security.ubuntu.com precise-security/multiverse TranslationIndex Hit http://security.ubuntu.com precise-security/restricted TranslationIndex Hit http://security.ubuntu.com precise-security/universe TranslationIndex Hit http://security.ubuntu.com precise-security/main Translation-en Hit http://security.ubuntu.com precise-security/multiverse Translation-en Hit http://security.ubuntu.com precise-security/restricted Translation-en Hit http://security.ubuntu.com precise-security/universe Translation-en Ign http://ppa.launchpad.net precise/main Translation-en_US Ign http://extras.ubuntu.com precise/main Translation-en_US Ign http://ppa.launchpad.net precise/main Translation-en Ign http://extras.ubuntu.com precise/main Translation-en Reading package lists... Done zero@ghostrider:~$ sudo apt-get install oracle-java7-installer Reading package lists... Done Building dependency tree Reading state information... Done oracle-java7-installer is already the newest version. 0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded. 1 not fully installed or removed. After this operation, 0 B of additional disk space will be used. Do you want to continue [Y/n]? Y Setting up oracle-java7-installer (7u3-0~eugenesan~precise4) ... Downloading... --2012-06-11 23:57:11-- http://download.oracle.com/otn-pub/java/jdk/7u3-b04/jdk- 7u3-linux-i586.tar.gz Resolving download.oracle.com (download.oracle.com)... 64.209.77.18 Connecting to download.oracle.com (download.oracle.com)|64.209.77.18|:80... connected. HTTP request sent, awaiting response... 302 Moved Temporarily Location: https://edelivery.oracle.com/otn-pub/java/jdk/7u3-b04/jdk-7u3-linux-i586.tar.gz [following] --2012-06-11 23:57:11-- https://edelivery.oracle.com/otn-pub/java/jdk/7u3-b04/jdk-7u3-linux-i586.tar.gz Resolving edelivery.oracle.com (edelivery.oracle.com)... 95.101.122.174 Connecting to edelivery.oracle.com (edelivery.oracle.com)|95.101.122.174|:443... connected. HTTP request sent, awaiting response... 302 Moved Temporarily Location: http://download.oracle.com/errors/download-fail-1505220.html [following] --2012-06-11 23:57:12-- http://download.oracle.com/errors/download-fail-1505220.html Connecting to download.oracle.com (download.oracle.com)|64.209.77.18|:80... connected. HTTP request sent, awaiting response... 200 OK Length: 5307 (5.2K) [text/html] Saving to: `./jdk-7u3-linux-i586.tar.gz' 0K ..... 100% 976K=0.005s 2012-06-11 23:57:12 (976 KB/s) - `./jdk-7u3-linux-i586.tar.gz' saved [5307/5307] Download done. sha256sum mismatch jdk-7u3-linux-i586.tar.gz Oracle JDK 7 is NOT installed. dpkg: error processing oracle-java7-installer (--configure): subprocess installed post-installation script returned error exit status 1 No apport report written because MaxReports is reached already Errors were encountered while processing: oracle-java7-installer E: Sub-process /usr/bin/dpkg returned an error code (1) zero@ghostrider:~$

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dpkg error : old pre-removal script returned error exit status 102

- by Siva Prasad Varma

I am unable to install or remove a package on my Ubuntu 10.04 due to the following error. $ sudo apt-get autoremove Password: Reading package lists... Done Building dependency tree Reading state information... Done The following packages will be REMOVED: busybox 0 upgraded, 0 newly installed, 1 to remove and 9 not upgraded. 1 not fully installed or removed. Need to get 0B/212kB of archives. After this operation, 627kB disk space will be freed. Do you want to continue [Y/n]? y Selecting previously deselected package nscd. (Reading database ... 235651 files and directories currently installed.) Preparing to replace nscd 2.11.1-0ubuntu7.8 (using .../nscd_2.11.1-0ubuntu7.8_amd64.deb) ... invoke-rc.d: not a symlink: /etc/rc2.d/S76nscd dpkg: warning: old pre-removal script returned error exit status 102 dpkg - trying script from the new package instead ... invoke-rc.d: not a symlink: /etc/rc2.d/S76nscd dpkg: error processing /var/cache/apt/archives/nscd_2.11.1-0ubuntu7.8_amd64.deb (--unpack): subprocess new pre-removal script returned error exit status 102 update-rc.d: warning: /etc/rc2.d/S76nscd is not a symbolic link invoke-rc.d: not a symlink: /etc/rc2.d/S76nscd dpkg: error while cleaning up: subprocess installed post-installation script returned error exit status 102 Errors were encountered while processing: /var/cache/apt/archives/nscd_2.11.1-0ubuntu7.8_amd64.deb E: Sub-process /usr/bin/dpkg returned an error code (1) What should I do to resolve this error. I have tried sudo dpkg --remove --force-remove-reinstreq nscd but it did not work.

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Can't install TeamViewer on Ubuntu 12.04

- by Roel

I have a Dell Inspiron 6400 laptop. I was a Windows user but I want to start using Ubuntu from now on. Everything goes well except installation of the teamviewer. I have downloaded the file from the official website. There, it says that just double click on the *.deb file and it will install it automatically. Well, it gives an error: Failed to remove essential system package, You requested to remove a package which is an essential part of your system. Then I tried the second way of installation, which is on the terminal. I types as suggested: sudo dpkg -i teamviewer_linux.deb. It started installing but later on failed. HEre is the copy of the screen. Preparing to replace teamviewer7:i386 7.0.9377 (using teamviewer_linux.deb) ... Unpacking replacement teamviewer7:i386 ... dpkg: dependency problems prevent configuration of teamviewer7:i386: teamviewer7:i386 depends on bash (>= 3.0). teamviewer7:i386 depends on libc6 (>= 2.7). teamviewer7:i386 depends on libasound2. teamviewer7:i386 depends on zlib1g. teamviewer7:i386 depends on libxext6. dpkg: error processing teamviewer7:i386 (--install): dependency problems - leaving unconfigured Errors were encountered while processing: teamviewer7:i386 I have already checked these dependent files in Synaptic and they are all installed. What am I doing wrong?

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Ground Control by David Baum

- by JuergenKress

As cloud computing moves out of the early-adopter phase, organizations are carefully evaluating how to get to the cloud. They are examining standard methods for developing, integrating, deploying, and scaling their cloud applications, and after weighing their choices, they are choosing to develop and deploy cloud applications based on Oracle Cloud Application Foundation, part of Oracle Fusion Middleware. Oracle WebLogic Server is the flagship software product of Oracle Cloud Application Foundation. Oracle WebLogic Server is optimized to run on Oracle Exalogic Elastic Cloud, the integrated hardware and software platform for the Oracle Cloud Application Foundation family. Many companies, including Reliance Commercial Finance, are adopting this middleware infrastructure to enable private cloud computing and its convenient, on-demand access to a shared pool of configurable computing resources. “Cloud computing has become an extremely critical design factor for us,” says Shashi Kumar Ravulapaty, senior vice president and chief technology officer at Reliance Commercial Finance. “It’s one of our main focus areas. Oracle Exalogic, especially in combination with Oracle WebLogic, is a perfect fit for rapidly provisioning capacity in a private cloud infrastructure.” Reliance Commercial Finance provides loans to tens of thousands of customers throughout India. With more than 1,500 employees accessing the company’s core business applications every day, the company was having trouble processing more than 6,000 daily transactions with its legacy infrastructure, especially at the end of each month when hundreds of concurrent users need to access the company’s loan processing and approval applications. Read the complete article here. WebLogic Partner Community For regular information become a member in the WebLogic Partner Community please visit: http://www.oracle.com/partners/goto/wls-emea ( OPN account required). If you need support with your account please contact the Oracle Partner Business Center. Blog Twitter LinkedIn Mix Forum Wiki Technorati Tags: WebLogic,WebLogic Community,Oracle,OPN,Jürgen Kress

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Refactor This (Ugly Code)!

- by Alois Kraus

Ayende has put on his blog some ugly code to refactor. First and foremost it is nearly impossible to reason about other peoples code without knowing the driving forces behind the current code. It is certainly possible to make it much cleaner when potential sources of errors cannot happen in the first place due to good design. I can see what the intention of the code is but I do not know about every brittle detail if I am allowed to reorder things here and there to simplify things. So I decided to make it much simpler by identifying the different responsibilities of the methods and encapsulate it in different classes. The code we need to refactor seems to deal with a handler after a message has been sent to a message queue. The handler does complete the current transaction if there is any and does handle any errors happening there. If during the the completion of the transaction errors occur the transaction is at least disposed. We can enter the handler already in a faulty state where we try to deliver the complete event in any case and signal a failure event and try to resend the message again to the queue if it was not inside a transaction. All is decorated with many try/catch blocks, duplicated code and some state variables to route the program flow. It is hard to understand and difficult to reason about. In other words: This code is a mess and could be written by me if I was under pressure. Here comes to code we want to refactor: private void HandleMessageCompletion( Message message, TransactionScope tx, OpenedQueue messageQueue, Exception exception, Action<CurrentMessageInformation, Exception> messageCompleted, Action<CurrentMessageInformation> beforeTransactionCommit) { var txDisposed = false; if (exception == null) { try { if (tx != null) { if (beforeTransactionCommit != null) beforeTransactionCommit(currentMessageInformation); tx.Complete(); tx.Dispose(); txDisposed = true; } try { if (messageCompleted != null) messageCompleted(currentMessageInformation, exception); } catch (Exception e) { Trace.TraceError("An error occured when raising the MessageCompleted event, the error will NOT affect the message processing"+ e); } return; } catch (Exception e) { Trace.TraceWarning("Failed to complete transaction, moving to error mode"+ e); exception = e; } } try { if (txDisposed == false && tx != null) { Trace.TraceWarning("Disposing transaction in error mode"); tx.Dispose(); } } catch (Exception e) { Trace.TraceWarning("Failed to dispose of transaction in error mode."+ e); } if (message == null) return; try { if (messageCompleted != null) messageCompleted(currentMessageInformation, exception); } catch (Exception e) { Trace.TraceError("An error occured when raising the MessageCompleted event, the error will NOT affect the message processing"+ e); } try { var copy = MessageProcessingFailure; if (copy != null) copy(currentMessageInformation, exception); } catch (Exception moduleException) { Trace.TraceError("Module failed to process message failure: " + exception.Message+ moduleException); } if (messageQueue.IsTransactional == false)// put the item back in the queue { messageQueue.Send(message); } } You can see quite some processing and handling going on there. Yes this looks like real world code one did put together to make things work and he does not trust his callbacks. I guess these are event handlers which are optional and the delegates were extracted from an event to call them back later when necessary. Lets see what the author of this code did intend: private void HandleMessageCompletion( TransactionHandler transactionHandler, MessageCompletionHandler handler, CurrentMessageInformation messageInfo, ErrorCollector errors ) { // commit current pending transaction transactionHandler.CallHandlerAndCommit(messageInfo, errors); // We have an error for a null message do not send completion event if (messageInfo.CurrentMessage == null) return; // Send completion event in any case regardless of errors handler.OnMessageCompleted(messageInfo, errors); // put message back if queue is not transactional transactionHandler.ResendMessageOnError(messageInfo.CurrentMessage, errors); } I did not bother to write the intention here again since the code should be pretty self explaining by now. I have used comments to explain the still nontrivial procedure step by step revealing the real intention about all this complex program flow. The original complexity of the problem domain does not go away but by applying the techniques of SRP (Single Responsibility Principle) and some functional style but we can abstract the necessary complexity away in useful abstractions which make it much easier to reason about it. Since most of the method seems to deal with errors I thought it was a good idea to encapsulate the error state of our current message in an ErrorCollector object which stores all exceptions in a list along with a description what the error all was about in the exception itself. We can log it later or not depending on the log level or whatever. It is really just a simple list that encapsulates the current error state. class ErrorCollector { List<Exception> _Errors = new List<Exception>(); public void Add(Exception ex, string description) { ex.Data["Description"] = description; _Errors.Add(ex); } public Exception Last { get { return _Errors.LastOrDefault(); } } public bool HasError { get { return _Errors.Count > 0; } } } Since the error state is global we have two choices to store a reference in the other helper objects (TransactionHandler and MessageCompletionHandler)or pass it to the method calls when necessary. I did chose the latter one because a second argument does not hurt and makes it easier to reason about the overall state while the helper objects remain stateless and immutable which makes the helper objects much easier to understand and as a bonus thread safe as well. This does not mean that the stored member variables are stateless or thread safe as well but at least our helper classes are it. Most of the complexity is located the transaction handling I consider as a separate responsibility that I delegate to the TransactionHandler which does nothing if there is no transaction or Call the Before Commit Handler Commit Transaction Dispose Transaction if commit did throw In fact it has a second responsibility to resend the message if the transaction did fail. I did see a good fit there since it deals with transaction failures. class TransactionHandler { TransactionScope _Tx; Action<CurrentMessageInformation> _BeforeCommit; OpenedQueue _MessageQueue; public TransactionHandler(TransactionScope tx, Action<CurrentMessageInformation> beforeCommit, OpenedQueue messageQueue) { _Tx = tx; _BeforeCommit = beforeCommit; _MessageQueue = messageQueue; } public void CallHandlerAndCommit(CurrentMessageInformation currentMessageInfo, ErrorCollector errors) { if (_Tx != null && !errors.HasError) { try { if (_BeforeCommit != null) { _BeforeCommit(currentMessageInfo); } _Tx.Complete(); _Tx.Dispose(); } catch (Exception ex) { errors.Add(ex, "Failed to complete transaction, moving to error mode"); Trace.TraceWarning("Disposing transaction in error mode"); try { _Tx.Dispose(); } catch (Exception ex2) { errors.Add(ex2, "Failed to dispose of transaction in error mode."); } } } } public void ResendMessageOnError(Message message, ErrorCollector errors) { if (errors.HasError && !_MessageQueue.IsTransactional) { _MessageQueue.Send(message); } } } If we need to change the handling in the future we have a much easier time to reason about our application flow than before. After we did complete our transaction and called our callback we can call the completion handler which is the main purpose of the HandleMessageCompletion method after all. The responsiblity o the MessageCompletionHandler is to call the completion callback and the failure callback when some error has occurred. class MessageCompletionHandler { Action<CurrentMessageInformation, Exception> _MessageCompletedHandler; Action<CurrentMessageInformation, Exception> _MessageProcessingFailure; public MessageCompletionHandler(Action<CurrentMessageInformation, Exception> messageCompletedHandler, Action<CurrentMessageInformation, Exception> messageProcessingFailure) { _MessageCompletedHandler = messageCompletedHandler; _MessageProcessingFailure = messageProcessingFailure; } public void OnMessageCompleted(CurrentMessageInformation currentMessageInfo, ErrorCollector errors) { try { if (_MessageCompletedHandler != null) { _MessageCompletedHandler(currentMessageInfo, errors.Last); } } catch (Exception ex) { errors.Add(ex, "An error occured when raising the MessageCompleted event, the error will NOT affect the message processing"); } if (errors.HasError) { SignalFailedMessage(currentMessageInfo, errors); } } void SignalFailedMessage(CurrentMessageInformation currentMessageInfo, ErrorCollector errors) { try { if (_MessageProcessingFailure != null) _MessageProcessingFailure(currentMessageInfo, errors.Last); } catch (Exception moduleException) { errors.Add(moduleException, "Module failed to process message failure"); } } } If for some reason I did screw up the logic and we need to call the completion handler from our Transaction handler we can simple add to the CallHandlerAndCommit method a third argument to the MessageCompletionHandler and we are fine again. If the logic becomes even more complex and we need to ensure that the completed event is triggered only once we have now one place the completion handler to capture the state. During this refactoring I simple put things together that belong together and came up with useful abstractions. If you look at the original argument list of the HandleMessageCompletion method I have put many things together: Original Arguments New Arguments Encapsulate Message message CurrentMessageInformation messageInfo Message message TransactionScope tx Action<CurrentMessageInformation> beforeTransactionCommit OpenedQueue messageQueue TransactionHandler transactionHandler TransactionScope tx OpenedQueue messageQueue Action<CurrentMessageInformation> beforeTransactionCommit Exception exception, ErrorCollector errors Action<CurrentMessageInformation, Exception> messageCompleted MessageCompletionHandler handler Action<CurrentMessageInformation, Exception> messageCompleted Action<CurrentMessageInformation, Exception> messageProcessingFailure The reason is simple: Put the things that have relationships together and you will find nearly automatically useful abstractions. I hope this makes sense to you. If you see a way to make it even more simple you can show Ayende your improved version as well.

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ubuntu one not syncing

- by Martin

I am really starting to despair as I have been trying ubuntu one for several months, trying it on several machines, and it has caused me loads of different issues wasting me a lot of time. It is not straight forward to use, it should be a piece of software that runs in background and users should not think about checking all the time if it is really doing it's job. Of course I have been searching around this website and other forums but couldn't find an answer to my situation. Yesterday I had several problems with the client not syncing and using a lot of the machine's RAM, up and CPU. I had to reboot on several occasions and leave the office's PC on overnight in order to sync a few files of not more than a few MB. Today I am experiencing another problem: I have decided to do a test putting a small file in my ubuntu one shared folder. Ubuntu one is not detecting it (now already more than an hour), therefore not uploading it to the server. martin@ubuntu-desktop:~$ u1sdtool --status State: QUEUE_MANAGER connection: With User With Network description: processing the commands pool is_connected: True is_error: False is_online: True queues: IDLE and martin@ubuntu-desktop:~$ u1sdtool --current-transfers Current uploads: 0 Current downloads: 0 I am running Ubuntu 11.04 64 with all recent updates. On my other machine the transfer of files seems to be completely frozen, with around 10 files in the queue but no transfer whatsoever. Another curious issue is on my Ubuntu 10.10 laptop where ubuntu one seems to have completly disappeared from Nautilus context menu, folder/file sync status icons missing. I have therefore been forced to upgrade to 11.04 on this machine. Anyway, now I would like to solve the ** processing the commands pool ** issue and make sure the client

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Pass Extra Parameters to JavaScript Callback Function

- by BRADINO

Here is a simple example of a function that takes a callback function as a parameter. query.send(handleQueryResponse); function handleQueryResponse(response){ alert('Processing...'); } If you wanted to pass extra variables to the callback function, you can do it like this. var param1 = 'something'; var param2 ='something else'; query.send(function(response) { handleQueryResponse(response, param1, param2) }); function handleQueryResponse(response,param1,param2){ alert('Processing...'); alert(param1); alert(param2); }

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I can't upgrade 13.10 because of broken pipe

- by user212179

I try upgrading and this is what I get: christopher@chris-computer:~$ sudo apt-get upgrade [sudo] password for christopher: Reading package lists... Done Building dependency tree Reading state information... Done The following packages will be upgraded: librhythmbox-core7 1 upgraded, 0 newly installed, 0 to remove and 0 not upgraded. Need to get 0 B/809 kB of archives. After this operation, 39.9 kB of additional disk space will be used. Do you want to continue [Y/n]? y (Reading database ... 170617 files and directories currently installed.) Preparing to replace librhythmbox-core7 2.99.1-0ubuntu1 (using .../librhythmbox-core7_3.0.1-0~13.10~ppa1_i386.deb) ... Unpacking replacement librhythmbox-core7 ... dpkg: error processing /var/cache/apt/archives/librhythmbox-core7_3.0.1-0~13.10~ppa1_i386.deb (--unpack): trying to overwrite '/usr/lib/librhythmbox-core.so.8.0.0', which is also in package librhythmbox-core8 3.0.1-1ubuntu2~ppa0 No apport report written because MaxReports is reached already dpkg-deb: error: subprocess paste was killed by signal (Broken pipe) Errors were encountered while processing: /var/cache/apt/archives/librhythmbox-core7_3.0.1-0~13.10~ppa1_i386.deb E: Sub-process /usr/bin/dpkg returned an error code (1)

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Site too large to officially use Google Analytics?

- by Jeff Atwood

We just got this email from the Google Analytics team: We love that you love our product and use it as much as you do. We have observed however, that a website you are tracking with Google Analytics is sending over 1 million hits per day to Google Analytics servers. This is well above the "5 million pageviews per month per account" limit specified in the Google Analytics Terms of Service. Processing this amount of data multiple times a day takes up valuable resources that enable us to continue to develop the product for all Google Analytics users. Processing this amount of data multiple times a day takes up valuable resources that enable us to continue to develop the product for all Google Analytics users. As such, starting August 23rd, 2010, the metrics in your reports will be updated once a day, as opposed to multiple times during the course of the day. You will continue to receive all the reports and features in Google Analytics as usual. The only change will be that data for a given day will appear the following day. We trust you understand the reasons for this change. I totally respect this decision, and I think it's very generous to not kick us out. But how do we do this the right way -- what's the official, blessed Google way to use Google Analytics if you're a "whale" website with lots of hits per day? Or, are there other analytics services that would be more appropriate for very large websites?

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dpkg E: Sub-process /usr/bin/dpkg returned an error

- by user81269

I decided to shift around my partitions on my hard drive for a fresh install of Kubuntu. I booted my Ubuntu 10.10 live disc, shifted everything around and attempted to install grub and it didn't work, so I burnt an Ubuntu 12.04 disc and installed it. I got the computer working and wanted to install some packages, but didn't have an internet connection at the time. So (I know this was stupid) I got some debs from previous versions of Ubuntu, as I needed my music, and the other install took a long of time to boot. Once I got my internet connection back, everything worked ok, for a little while. Then I stumbled upon this problem after removing ten broken packages using synaptic: drhax@Spamotard:~$ sudo apt-get install -f Reading package lists... Done Building dependency tree Reading state information... Done The following packages will be REMOVED: libgtk2.0-cil 0 upgraded, 0 newly installed, 1 to remove and 417 not upgraded. 1 not fully installed or removed. After this operation, 2,638 kB disk space will be freed. Do you want to continue [Y/n]? y (Reading database ... 103052 files and directories currently installed.) Removing libgtk2.0-cil ... E: File does not exist: /usr/share/cli-common/packages.d/policy.2.6.gtk-dotnet.installcligac dpkg: error processing libgtk2.0-cil (--remove): subprocess installed post-removal script returned error exit status 1 Errors were encountered while processing: libgtk2.0-cil E: Sub-process /usr/bin/dpkg returned an error code (1) Help would be appreciated. This is my first post, but I do know fair bit about Ubuntu, so feel free to point out any stupid mistakes I have made.

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xVelocity engines compared: VertiPaq vs ColumnStore #ssas #vertipaq #xvelocity #sql #tabular

- by Marco Russo (SQLBI)

During the last months I and Alberto worked in several projects using Analysis Services Tabular and we had to face real world issues, such as complex queries, large data volume, frequent data updates and so on. Sometime we faced the challenge of comparing Tabular performance with SQL Server. It seemed a non-sense, because even if the same core xVelocity technology is implemented in both products (SQL Server 2012 uses ColumnStore indexes, whereas Analysis Services 2012 uses VertiPaq), we initially assumed that the better optimization for the in-memory engine used by Analysis Services would have been always better than SQL Server. However, we discovered several important things: Processing time might be different and having data on SQL Server could make ColumnStore way faster for processing. Partitioning in SQL Server might be much more effective for query performance than Analysis Services. A single query can scale easily on more processor on SQL Server, whereas in Analysis Services the formula engine is single-threaded and could be a bottleneck for certain queries. In case of a large workload with many concurrent users, storage engine cache in Analysis Services could be a big advantage over SQL Server, especially for scalability As you can see, these considerations are not always obvious and you might be tempted to make other assumptions based on these information. Well, don’t do that. Before anything else, read the whitepaper VertiPaq vs ColumnStore Comparison written by Alberto Ferrari. Then, measure your workload. Finally, make some conclusion. But don’t make too many assumptions. You might be wrong, as we did at the beginning of this journey.

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PARTNER WEBCAST (June 4): Enhance Customer experience with Nimble Storage SmartStack for Oracle with Cisco

- by Zeynep Koch

Live Webcast: Enhance Customer experience with Nimble Storage SmartStack for Oracle with Cisco A webcast for resellers who sell Oracle workloads to customers Wednesday, June 4, 2014, 8:00 AM PDT /11 AM EDT Register today Nimble Storage SmartStack™ for Oracle provides pre-validated reference architecture that speed deployments and minimize risk. IT and Oracle administrators and architects realize the importance of underlying Operating System, Virtualization software, and Storage in maintaining services levels and staying in budget. In this webinar, you will learn how Nimble Storage SmartStack for Oracle provides a converged infrastructure for Oracle database online transaction processing (OLTP) and online analytical processing (OLAP) environments with Oracle Linux and Oracle VM. SmartStack delivers the performance and reliability needed for deploying Oracle on a single symmetric multiprocessing (SMP) server or if you are running Oracle Real Application Clusters (RAC) on multiple nodes. Nimble Storage SmartStack for Oracle with Cisco can help you provide: Improved Oracle performance Stress-free data protection and DR of your Oracle database Higher availability and uptime Accelerate Oracle development and improve testing All for dramatically less than what you’re paying now Presenters: Doan Nguyen, Senior Principal Product Marketing Director, Oracle Vanessa Scott , Business Development Manager, Cisco Ibrahim “Ibby” Rahmani, Product and Solutions Marketing, Nimble Storage Join this event to learn from our Nimble Storage and Oracle experts on how to optimize your customers' Oracle environments. Register today to learn more!

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PARTNER WEBCAST (June 4): Enhance Customer experience with Nimble Storage SmartStack for Oracle with Cisco

- by Zeynep Koch

Live Webcast: Enhance Customer experience with Nimble Storage SmartStack for Oracle with Cisco A webcast for resellers who sell Oracle workloads to customers Wednesday, June 4, 2014, 8:00 AM PDT /11 AM EDT Register today Nimble Storage SmartStack™ for Oracle provides pre-validated reference architecture that speed deployments and minimize risk. IT and Oracle administrators and architects realize the importance of underlying Operating System, Virtualization software, and Storage in maintaining services levels and staying in budget. In this webinar, you will learn how Nimble Storage SmartStack for Oracle provides a converged infrastructure for Oracle database online transaction processing (OLTP) and online analytical processing (OLAP) environments with Oracle Linux and Oracle VM. SmartStack delivers the performance and reliability needed for deploying Oracle on a single symmetric multiprocessing (SMP) server or if you are running Oracle Real Application Clusters (RAC) on multiple nodes. Nimble Storage SmartStack for Oracle with Cisco can help you provide: Improved Oracle performance Stress-free data protection and DR of your Oracle database Higher availability and uptime Accelerate Oracle development and improve testing All for dramatically less than what you’re paying now Presenters: Doan Nguyen, Senior Principal Product Marketing Director, Oracle Vanessa Scott , Business Development Manager, Cisco Ibrahim “Ibby” Rahmani, Product and Solutions Marketing, Nimble Storage Join this event to learn from our Nimble Storage and Oracle experts on how to optimize your customers' Oracle environments. Register today to learn more!

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You Need BRM When You have EBS – and Even When You Don’t!

- by bwalstra

Here is a list of criteria to test your business-systems (Oracle E-Business Suite, EBS) or otherwise to support your lines of digital business - if you score low, you need Oracle Billing and Revenue Management (BRM). Functions Scalability High Availability (99.999%) Performance Extensibility (e.g. APIs, Tools) Upgradability Maintenance Security Standards Compliance Regulatory Compliance (e.g. SOX) User Experience Implementation Complexity Features Customer Management Real-Time Service Authorization Pricing/Promotions Flexibility Subscriptions Usage Rating and Pricing Real-Time Balance Mgmt. Non-Currency Resources Billing & Invoicing A/R & G/L Payments & Collections Revenue Assurance Integration with Key Enterprise Applications Reporting Business Intelligence Order & Service Mgmt (OSM) Siebel CRM E-Business Suite On-/Off-line Mediation Payment Processing Taxation Royalties & Settlements Operations Management Disaster Recovery Overall Evaluation Implementation Configuration Extensibility Maintenance Upgradability Functional Richness Feature Richness Usability OOB Integrations Operations Management Leveraging Oracle Technology Overall Fit for Purpose You need Oracle BRM: Built for high-volume transaction processing Monetizes any service or event based on any metric Supports high-volume usage rating, pricing and promotions Provides real-time charging, service authorization and balance management Supports any account structure (e.g. corporate hierarchies etc.) Scales from low volumes to extremely high volumes of transactions (e.g. billions of trxn per hour) Exposes every single function via APIs (e.g. Java, C/C++, PERL, COM, Web Services, JCA) Immediate Business Benefits of BRM: Improved business agility and performance Supports the flexibility, innovation, and customer-centricity required for current and future business models Faster time to market for new products and services Supports 360 view of the customer in real-time – products can be launched to targeted customers at a record-breaking pace Streamlined deployment and operation Productized integrations, standards-based APIs, and OOB enablement lower deployment and maintenance costs Extensible and scalable solution Minimizes risk – initial phase deployed rapidly; solution extended and scaled seamlessly per business requirements Key Considerations Productized integration with key Oracle applications Lower integration risks and cost Efficient order-to-cash process Engineered solution – certification on Exa platform Exadata tested at PayPal in the re-platforming project Optimal performance of Oracle assets on Oracle hardware Productized solution in Rapid Offer Design and Order Delivery Fast offer design and implementation Significantly shorter order cycle time Productized integration with Oracle Enterprise Manager Visibility to system operability for optimal up time

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How do you deal with translating theory into practice?

- by Mr. Shickadance

Hello all! Being a computer scientist in a research field I am often tasked with working alongside professionals outside of the software domain (think math people, electrical engineer etc), and then translating their theories and ideas into real-world implementations. I often find it difficult when they present a theoretical problem which appears to be somewhat disconnected from reality. I am not saying that the theory is bogus, only that it is difficult to translate into real-world situations. For example, recently I have been working with software defined radios. We are exploring many different areas, but often the math specialists in my group would present a problem which is heavily grounded in theory (signal processing, physics, whatever). I often struggle at times where it is hard to draw direct parallels between the theory and the real-world implementation that I need to develop. Say we are working on an energy detector, the theory person in my group would say "you need to measure the noise variance with no signal present." This leads me to think "how the hell do I isolate noise from a signal in reality?" There are many examples, but I hope you see where I am going. So, my question is how does one deal with implementation of theoretical concepts when the theory seems detached from reality? Or at least when the connections are not so clear. Or perhaps, the person with the 'theory' may be ignorant of real restrictions? Note: I found this to be a hard question to ask - hopefully you are following me. If you have suggestions on how I could improve it, by all means let me know! Thanks for looking! EDIT: To be a bit more clear, I understand in situations like this that I must learn that specific domain myself to an extent (i.e. signal processing), but I am more concerned with when those theoretical concepts do not appear to be as grounded in practice as one would like.

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Architecting Python application consisting of many small scripts

- by Duke Dougal

I am building an application which, at the moment, consists of many small Python scripts. Each Python script processes items from one Amazon SQS queue. Emails come into an initial queue and are processed by a script and typically the script will do a small unit of processing (for example, parse email and store some database fields), then an item will be placed on the next queue for further processing, until eventually the email has finished going through the various scripts and queues. What I like about this approach is that it is very loosely coupled. However, I'm not sure how I should implement live. Should I make each script a daemon which is constantly polling it's inbound queue for things to do? Or should there be some overarching orchestration program or process? Or maybe I should not have lots of small Python scripts but one large application? Specific questions: How should I run each of these scripts - as a daemon with some sort or restart monitor to restart them in case they stop for any reason? If yes, should I have some program which orchestrates this? Or is the idea of many small script not a good one, would it make more sense to have a larger python program which contains all the functionality and does all the queue polling and execution of functionality for each queue? What is the current preferred approach to daemonising Python scripts? Broadly I would welcome any comments or opinions on any aspect of this. thanks

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Organizations & Architecture UNISA Studies – Chap 7

- by MarkPearl

Learning Outcomes Name different device categories Discuss the functions and structure of I/.O modules Describe the principles of Programmed I/O Describe the principles of Interrupt-driven I/O Describe the principles of DMA Discuss the evolution characteristic of I/O channels Describe different types of I/O interface Explain the principles of point-to-point and multipoint configurations Discuss the way in which a FireWire serial bus functions Discuss the principles of InfiniBand architecture External Devices An external device attaches to the computer by a link to an I/O module. The link is used to exchange control, status, and data between the I/O module and the external device. External devices can be classified into 3 categories… Human readable – e.g. video display Machine readable – e.g. magnetic disk Communications – e.g. wifi card I/O Modules An I/O module has two major functions… Interface to the processor and memory via the system bus or central switch Interface to one or more peripheral devices by tailored data links Module Functions The major functions or requirements for an I/O module fall into the following categories… Control and timing Processor communication Device communication Data buffering Error detection I/O function includes a control and timing requirement, to coordinate the flow of traffic between internal resources and external devices. Processor communication involves the following… Command decoding Data Status reporting Address recognition The I/O device must be able to perform device communication. This communication involves commands, status information, and data. An essential task of an I/O module is data buffering due to the relative slow speeds of most external devices. An I/O module is often responsible for error detection and for subsequently reporting errors to the processor. I/O Module Structure An I/O module functions to allow the processor to view a wide range of devices in a simple minded way. The I/O module may hide the details of timing, formats, and the electro mechanics of an external device so that the processor can function in terms of simple reads and write commands. An I/O channel/processor is an I/O module that takes on most of the detailed processing burden, presenting a high-level interface to the processor. There are 3 techniques are possible for I/O operations Programmed I/O Interrupt[t I/O DMA Access Programmed I/O When a processor is executing a program and encounters an instruction relating to I/O it executes that instruction by issuing a command to the appropriate I/O module. With programmed I/O, the I/O module will perform the requested action and then set the appropriate bits in the I/O status register. The I/O module takes no further actions to alert the processor. I/O Commands To execute an I/O related instruction, the processor issues an address, specifying the particular I/O module and external device, and an I/O command. There are four types of I/O commands that an I/O module may receive when it is addressed by a processor… Control – used to activate a peripheral and tell it what to do Test – Used to test various status conditions associated with an I/O module and its peripherals Read – Causes the I/O module to obtain an item of data from the peripheral and place it in an internal buffer Write – Causes the I/O module to take an item of data form the data bus and subsequently transmit that data item to the peripheral The main disadvantage of this technique is it is a time consuming process that keeps the processor busy needlessly I/O Instructions With programmed I/O there is a close correspondence between the I/O related instructions that the processor fetches from memory and the I/O commands that the processor issues to an I/O module to execute the instructions. Typically there will be many I/O devices connected through I/O modules to the system – each device is given a unique identifier or address – when the processor issues an I/O command, the command contains the address of the address of the desired device, thus each I/O module must interpret the address lines to determine if the command is for itself. When the processor, main memory and I/O share a common bus, two modes of addressing are possible… Memory mapped I/O Isolated I/O (for a detailed explanation read page 245 of book) The advantage of memory mapped I/O over isolated I/O is that it has a large repertoire of instructions that can be used, allowing more efficient programming. The disadvantage of memory mapped I/O over isolated I/O is that valuable memory address space is sued up. Interrupts driven I/O Interrupt driven I/O works as follows… The processor issues an I/O command to a module and then goes on to do some other useful work The I/O module will then interrupts the processor to request service when is is ready to exchange data with the processor The processor then executes the data transfer and then resumes its former processing Interrupt Processing The occurrence of an interrupt triggers a number of events, both in the processor hardware and in software. When an I/O device completes an I/O operations the following sequence of hardware events occurs… The device issues an interrupt signal to the processor The processor finishes execution of the current instruction before responding to the interrupt The processor tests for an interrupt – determines that there is one – and sends an acknowledgement signal to the device that issues the interrupt. The acknowledgement allows the device to remove its interrupt signal The processor now needs to prepare to transfer control to the interrupt routine. To begin, it needs to save information needed to resume the current program at the point of interrupt. The minimum information required is the status of the processor and the location of the next instruction to be executed. The processor now loads the program counter with the entry location of the interrupt-handling program that will respond to this interrupt. It also saves the values of the process registers because the Interrupt operation may modify these The interrupt handler processes the interrupt – this includes examination of status information relating to the I/O operation or other event that caused an interrupt When interrupt processing is complete, the saved register values are retrieved from the stack and restored to the registers Finally, the PSW and program counter values from the stack are restored. Design Issues Two design issues arise in implementing interrupt I/O Because there will be multiple I/O modules, how does the processor determine which device issued the interrupt? If multiple interrupts have occurred, how does the processor decide which one to process? Addressing device recognition, 4 general categories of techniques are in common use… Multiple interrupt lines Software poll Daisy chain Bus arbitration For a detailed explanation of these approaches read page 250 of the textbook. Interrupt driven I/O while more efficient than simple programmed I/O still requires the active intervention of the processor to transfer data between memory and an I/O module, and any data transfer must traverse a path through the processor. Thus is suffers from two inherent drawbacks… The I/O transfer rate is limited by the speed with which the processor can test and service a device The processor is tied up in managing an I/O transfer; a number of instructions must be executed for each I/O transfer Direct Memory Access When large volumes of data are to be moved, an efficient technique is direct memory access (DMA) DMA Function DMA involves an additional module on the system bus. The DMA module is capable of mimicking the processor and taking over control of the system from the processor. It needs to do this to transfer data to and from memory over the system bus. DMA must the bus only when the processor does not need it, or it must force the processor to suspend operation temporarily (most common – referred to as cycle stealing). When the processor wishes to read or write a block of data, it issues a command to the DMA module by sending to the DMA module the following information… Whether a read or write is requested using the read or write control line between the processor and the DMA module The address of the I/O device involved, communicated on the data lines The starting location in memory to read from or write to, communicated on the data lines and stored by the DMA module in its address register The number of words to be read or written, communicated via the data lines and stored in the data count register The processor then continues with other work, it delegates the I/O operation to the DMA module which transfers the entire block of data, one word at a time, directly to or from memory without going through the processor. When the transfer is complete, the DMA module sends an interrupt signal to the processor, this the processor is involved only at the beginning and end of the transfer. I/O Channels and Processors Characteristics of I/O Channels As one proceeds along the evolutionary path, more and more of the I/O function is performed without CPU involvement. The I/O channel represents an extension of the DMA concept. An I/O channel ahs the ability to execute I/O instructions, which gives it complete control over I/O operations. In a computer system with such devices, the CPU does not execute I/O instructions – such instructions are stored in main memory to be executed by a special purpose processor in the I/O channel itself. Two types of I/O channels are common A selector channel controls multiple high-speed devices. A multiplexor channel can handle I/O with multiple characters as fast as possible to multiple devices. The external interface: FireWire and InfiniBand Types of Interfaces One major characteristic of the interface is whether it is serial or parallel parallel interface – there are multiple lines connecting the I/O module and the peripheral, and multiple bits are transferred simultaneously serial interface – there is only one line used to transmit data, and bits must be transmitted one at a time With new generation serial interfaces, parallel interfaces are becoming less common. In either case, the I/O module must engage in a dialogue with the peripheral. In general terms the dialog may look as follows… The I/O module sends a control signal requesting permission to send data The peripheral acknowledges the request The I/O module transfers data The peripheral acknowledges receipt of data For a detailed explanation of FireWire and InfiniBand technology read page 264 – 270 of the textbook

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