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  • Connect ViewModel and View using Unity

    - by brainbox
    In this post i want to describe the approach of connecting View and ViewModel which I'm using in my last project.The main idea is to do it during resolve inside of unity container. It can be achived using InjectionFactory introduced in Unity 2.0 public static class MVVMUnityExtensions{    public static void RegisterView<TView, TViewModel>(this IUnityContainer container) where TView : FrameworkElement    {        container.RegisterView<TView, TView, TViewModel>();    }    public static void RegisterView<TViewFrom, TViewTo, TViewModel>(this IUnityContainer container)        where TViewTo : FrameworkElement, TViewFrom    {        container.RegisterType<TViewFrom>(new InjectionFactory(            c =>            {                var model = c.Resolve<TViewModel>();                var view = Activator.CreateInstance<TViewTo>();                view.DataContext = model;                return view;            }         ));    }}}And here is the sample how it could be used:var unityContainer = new UnityContainer();unityContainer.RegisterView<IFooView, FooView, FooViewModel>();IFooView view = unityContainer.Resolve<IFooView>(); // view with injected viewmodel in its datacontextPlease tell me your prefered way to connect viewmodel and view.

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  • What is the data transfer speeds within the disk, to other devices?

    - by Kumar
    I use Debian 6 on a HP Elitbook 6930 with 2Gigs of RAM. I was copying two AVI files, 1.5 GB in total, and noticed that the data copying was done at the rate of 4MB/sec. When I copy same AVIs to my Western Digital Passport 25G USB plugin drive the data transfer speed is 11+MB/sec. This speed is different if I plugin the drive to different USB ports. Interestingly, at work I also downloaded a 16MB IE8 exe on my virtual xp, run inside Oracle Sun Virtual Box, and it was downloaded AND saved within a second. We have a high speed network at work. :-) Why and how this difference in data speeds is possible?

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  • Linux IPTables / routing issue

    - by Jon
    Hi all, EDIT 1/3/10 22:00 GMT - rewrote some of it after further investigation It has been a while since I looked at IPtables and I seem to be worse than before as I can not seem to get my webserver online. Below is my firewall rules on the gateway server that is running the dhcp server accessing the net. The webserver is inside my network on a static IP (192.168.0.98, default port). When I use Nmap or GRC.com I see that port 80 is open on the gateway server but when I browse to it, (via public URL. http://www.houseofhawkins.com) it always fails with a connection error, (nmap cannot connect and figure out what the web server is either). I can nmap the webserver and browse to it just fine via same IP inside my network. I believe it is my IPTable rules that are not letting it through. Internally I can route all my requests. Each machine can browse to the website and traffic works just fine. I can MSTSC / ssh to all the webservers internally and they inturn can connect to the web. IPTABLE: *EDIT - Added new firewall rules 2/3/10 * #!/bin/sh iptables="/sbin/iptables" modprobe="/sbin/modprobe" depmod="/sbin/depmod" EXTIF="eth2" INTIF="eth1" load () { $depmod -a $modprobe ip_tables $modprobe ip_conntrack $modprobe ip_conntrack_ftp $modprobe ip_conntrack_irc $modprobe iptable_nat $modprobe ip_nat_ftp echo "enable forwarding.." echo "1" > /proc/sys/net/ipv4/ip_forward echo "enable dynamic addr" echo "1" > /proc/sys/net/ipv4/ip_dynaddr # start firewall # default policies $iptables -P INPUT DROP $iptables -F INPUT $iptables -P OUTPUT DROP $iptables -F OUTPUT $iptables -P FORWARD DROP $iptables -F FORWARD $iptables -t nat -F #echo " Opening loopback interface for socket based services." $iptables -A INPUT -i lo -j ACCEPT $iptables -A OUTPUT -o lo -j ACCEPT #echo " Allow all connections OUT and only existing and related ones IN" $iptables -A INPUT -i $INTIF -j ACCEPT $iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT $iptables -A OUTPUT -o $EXTIF -j ACCEPT $iptables -A OUTPUT -m state --state ESTABLISHED,RELATED -j ACCEPT $iptables -A FORWARD -i $EXTIF -o $INTIF -m state --state ESTABLISHED,RELATED -j ACCEPT $iptables -A FORWARD -i $INTIF -o $EXTIF -j ACCEPT $iptables -A FORWARD -j LOG --log-level 7 --log-prefix "Dropped by firewall: " $iptables -A INPUT -j LOG --log-level 7 --log-prefix "Dropped by firewall: " $iptables -A OUTPUT -j LOG --log-level 7 --log-prefix "Dropped by firewall: " #echo " Enabling SNAT (MASQUERADE) functionality on $EXTIF" $iptables -t nat -A POSTROUTING -o $EXTIF -j MASQUERADE $iptables -A INPUT -i $INTIF -j ACCEPT $iptables -A OUTPUT -o $INTIF -j ACCEPT #echo " Allowing packets with ICMP data (i.e. ping)." $iptables -A INPUT -p icmp -j ACCEPT $iptables -A OUTPUT -p icmp -j ACCEPT $iptables -A INPUT -p udp -i $INTIF --dport 67 -m state --state NEW -j ACCEPT #echo " Port 137 is for NetBIOS." $iptables -A INPUT -i $INTIF -p udp --dport 137 -j ACCEPT $iptables -A OUTPUT -o $INTIF -p udp --dport 137 -j ACCEPT #echo " Opening port 53 for DNS queries." $iptables -A INPUT -p udp -i $EXTIF --sport 53 -j ACCEPT #echo " opening Apache webserver" $iptables -A PREROUTING -t nat -i $EXTIF -p tcp --dport 80 -j DNAT --to 192.168.0.96:80 $iptables -A FORWARD -p tcp -m state --state NEW -d 192.168.0.96 --dport 80 -j ACCEPT } flush () { echo "flushing rules..." $iptables -P FORWARD ACCEPT $iptables -F INPUT $iptables -P INPUT ACCEPT echo "rules flushed" } case "$1" in start|restart) flush load ;; stop) flush ;; *) echo "usage: start|stop|restart." ;; esac exit 0 route info: Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 5e0412a6.bb.sky * 255.255.255.255 UH 0 0 0 eth2 192.168.0.0 * 255.255.255.0 U 0 0 0 eth1 default 5e0412a6.bb.sky 0.0.0.0 UG 100 0 0 eth2 ifconfig: eth1 Link encap:Ethernet HWaddr 00:22:b0:cf:4a:1c inet addr:192.168.0.1 Bcast:192.168.0.255 Mask:255.255.255.0 inet6 addr: fe80::222:b0ff:fecf:4a1c/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:79023 errors:0 dropped:0 overruns:0 frame:0 TX packets:57786 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:11580918 (11.5 MB) TX bytes:22872030 (22.8 MB) Interrupt:17 Base address:0x2b00 eth2 Link encap:Ethernet HWaddr 00:0c:f1:7c:45:5b inet addr:94.4.18.166 Bcast:94.4.18.166 Mask:255.255.255.255 inet6 addr: fe80::20c:f1ff:fe7c:455b/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:57038 errors:0 dropped:0 overruns:0 frame:0 TX packets:34532 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:21631721 (21.6 MB) TX bytes:7685444 (7.6 MB) lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:16 errors:0 dropped:0 overruns:0 frame:0 TX packets:16 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:1517 (1.5 KB) TX bytes:1517 (1.5 KB) EDIT OK so as requested I will try and expand on my infrastructure: I previously had it setup with a Sky broadband modem router that did the DHCP and I used its web interface to port forward the web across to the web server. The network looked something like this: I have now replaced the sky modem with a dlink modem which gives the IP to the gateway server that now does the DHCP. It looks like: The internet connection is a standard broadband connection with a dynamic IP, (use zoneedit.com to keep it updated). I have tried it on each of the webservers(one Ubuntu Apache server and one WS2008 IIS7). I think there must also be an issue with my IPTable rules as it can route to my win7 box which has the default IIS7 page and that would not display when I forwarded all port 80 to it. I would be really grateful for any and all help with this. Thanks Jon

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  • CodePlex Daily Summary for Tuesday, May 04, 2010

    CodePlex Daily Summary for Tuesday, May 04, 2010New ProjectsAlbum photo de club - Club's Photos Album: Un album photos permettant d'afficher les photos et le détails des membres d'un club - Photo album allowing to view photos and details of the membersBlog.Net Blogging Components: Blog.Net server-side blogging components to add a blog to your current ASP.NET website.FilePirate - Really Advanced LAN File Sharing: Really Advanced, yet super easy, LAN Party File Sharing written using the .Net Framework and C#. Ditch DirectConnect or Windows File Sharing at y...Fisiogest: Programa de gestión de una clínica de fisioterapiaIdeaNMR: An online repository of NMR experiment automated setups with wiki type documentation library and client program providing automated experiment setu...Introducción a Unity: Código de ejemplo del uso de Unity en diferentes situaciones. - Registro de clases, instancias e interfaces. - Resolución de clases, instancias e...Iowa City .NET Developers: This is the project site for the Iowa City .NET Developers.isanywhere: A command line utility to see if one or more files (given a filemask) are to be found anywhere inside a specific directory, or elsewhere inside one...LczCode: lczLog4net udp logs viewer: UdpLogViewer is a .NET 4 WinForm application that receives udp messages from log4net and shows them in a grid. It is possible to filter them or sh...New Silverlight XPS Viewer (In Sl4): New Silverlight XPS viewer Novuz: Novuz is a usenet indexer and reporter. It's developed both in Visual Studio 2010 and MonoDevelop, one of the key features of Novuz is that it sho...PodSnatch: PodSnatch is a podcast client that makes it easy to download rss-enclosures. Multiple simultaneous downloads enabled by threading. GUI is built wi...Robot Shootans: A simple top down shooter game where the player has to kill robots running at them. Written in C++ using SDL with various extentionsSharePoint Rsync List: This program will syncronize files and directories from and unc/local/sharepoint to a SharePoint 2007 or 2010 server. Supports of to 2GB files and ...SignInAndStorageLib: SignInAndStorageLib makes properly handling both sign in and storage issues in Xbox 360 XBLIG XNA games simple. Written in C#, SignInAndStorageLib...SilverBBS: ANSI-style bbs experience delivered via Silverlight. Silverlight flip-down counter: A Silverlight widget that enables you to count down towards a preconfigured event on a configured date.SmartieFly: Smartie Fly is a quiz software program written in C# using Silverlight. It uses SQL Server as a backend database. VS2010 Framework Driven Testing: CodedUITests generate a lot of code, and they break on every change to the object under test. Goals: - write new tests manually, but with as litt...WMediaCatalog: Advanced multimedia cataloguer. Allows users to keep their musical collections well organized and provides flexible methods of filtering, serarching WPathFinder: A simple path management application for windows. Functionality includes: - Add/remove/change path entries easily. - Search for all instances of a...Yasminoku: Yasminoku is an open source "Sudoku" alike game totally written in DHTML (JavaScript, CSS and HTML) that uses mouse. Includes sudoku solver. This c...New ReleasesAlbum photo de club - Club's Photos Album: App - version 0.4: version 0.4 - Critère d'affichage des membres : nom, année, ville - Navigation entre les images d'un membres - Navigation entre les membres - Affi...Album photo de club - Club's Photos Album: Code - Version 0.4: Code source de la version 0.4BigDecimal: Concept Evaluation Release 2 (BigDecimals): This in the second updates release of BigDecimals. It has the four simple arithmetic rules Addition, Subtract, Multiple and Division.CBM-Command: 2010-05-03: New features in this build Keyboard Shortcuts Panel Swapping Panel Toggling On/Off Toggling 40/80 Columns Confirming Quit Confirming GO64...Directory Linker: Directory Linker 2: This release introduces Undo Support and Symbolic File Link support. More details can be found here http://www.humblecoder.co.uk/?p=141DotNetNuke Skins Pack: DotNetNuke 80 Skins Pack: This released is the first for DNN 4 & 5 with Skin Token Design (legacy skin support on DNN 4 & 5)DTLoggedExec: 1.0.0.0: -FIRST NON-BETA RELEASE! :) -Code cleaned up -Added SetPackageInfo method to ILogProvider interface to make easier future improvements -Deprecated...GenerateTypedBamApi: Version 2.1: Changes in this release: NEW: Support for Office Data Connectivity Components 2010 NEW: Include both x86 and x64 EXE's due to lack of support in ...HobbyBrew Mobile: Beta 1 Refresh: Risolto bug circa il salvataggio di ricette (veniva impostato scorrettamente che si trattava di Mash Design "infusione" se ri-aperte con hobbyBrew)...Home Access Plus+: v4.2: Version 4.2 Added Overrides into the Booking System Some slight CSS changes to the Help Desk Updated the config tool to work anywhere on the LA...Hubble.Net - Open source full-text search database: V0.8.3.0: V0.8.3.0 Show server version in about dialog. Fix a bug of deleting querycache files. V0.8.2.9 Change sql client to support userid and password Ch...IdeaNMR: IdeaNMR Client: This is a client program with an example package.kdar: KDAR 0.0.21: KDAR - Kernel Debugger Anti Rootkit - signature's bases updated - usability increased - NDIS6 MINIPORT_BLOCK checks addedLightWeight Application Server: 0.4.1: One step further to beta - yet another release for c# developers audience only. Changes: 1. API - added a LWAS.Infrastructure.Storage service to d...Log4net udp logs viewer: UdpLogViewer 1.0: First release of UdpLogViewer, version 1.0.MDownloader: MDownloader-0.15.11.58370: Fixed minor bugs.Metabolite Enterprise Libraries for EPiServer CMS using Page Type Builder: Metabolite Enterprise Libraries 1.2 Beta 2: This is the beta release of the Metabolite Enterprise Libraries 1.2 Beta 2 for use with EPiServer 6 and Page Type Builder 1.2 Beta 2.Microsoft Silverlight Analytics Framework: Version 1.4.3 Installer: Pre-release Installer for Visual Studio 2010 and Expression Blend 4 RCSupports both Silverlight 3 and Silverlight 4 Release NotesFixed null referen...MultipointTUIO: Multipoint SDK v1.5 Release: Rebuilt against v1.5 of the Microsoft Multipoint SDK, this mean Windows 7 support (and 64bit I think!)My Notepad: My Notepad: This is the status of My Notepad until now. This is many built in features but has to undergo a lot of modifications. The release does not include ...New Silverlight XPS Viewer (In Sl4): Silverlight XPS Viewer: Background: During my development last week I was working on a Silverlight based XPS viewer. During this viewer we came to a situation in which the...NSIS Autorun: NSIS Autorun 0.1.6: This release includes source code, executable binary, files and example materials.Open Diagram: Open Diagram 5.0 Beta May 2010: This is the first beta release of Open Diagram 5.0. Select Crainiate.Diagramming.Examples.Forms as the startup project to view the current Class D...Pocket Wiki: PC Wiki (zip) 1.0.1: PC Version of Pocket Wiki. Unzip and run. Requires .NET Framework 2.0Pocket Wiki: Pocket Wiki 1.0.1 (cab): Pocket Wiki cab installation - requires DotNet 2.0 or greater. Default wiki language is "slash" - a syntax I created that is easy to type on keyboa...Pocket Wiki: Pocket Wiki.sbp: Pocket Wiki Source Code (version .72) - Basic4PPCPublish to Photo Frame: 1.0.2.0: This version adds: add borders to portrait images, for photo frames that crop them incorrectly.Reflection Studio: Reflection Studio 0.1: First download release, it contains a lot of things but allways in beta version. Hope you will like the preview.SharePoint 2010 PowerShell Scripts & Utilities: PSSP2010 Utils 0.1: This is the initial release with SPInstallUtils.psm1 module. This module includes Get-SPPrerequisites and New-SPInstallPackage cmdlets. Refer to th...Silverlight 4.0 Popup Menu: Context Menu for Silverlight 4.0 v1.1 Beta: Multilevel menus are now supported. Added design time support for the PopupMenuItem elements. The project is now under Subversion.Silverlight flip-down counter: FlipDownCounter v1.0: The final release of the Silverlight flip-down counter. Please refer to the included readme file for information on how to use the counter.Stratosphere: Stratosphere 1.0.0.1: Moved scalable block file system implementation to Stratosphere.FileSystemSystem.AddIn Pipeline Builder: Pipeline Builder 1.2: Lots of improvements from the CTP, version 1.0: - Added dialogue for possible overwrite if the file has changed: possibility of ignoring changes (p...ThoughtWorks Cruise Notification Interceptor: 1.0.1: Fixed an issue with the regex that parses the incoming notification. This issue would send failure messages when the build was "fixed".ThreadSafeControls: ThreadSafeControls v0.1: This is the first binary release of the ThreadSafeControls library. I'll call it a pre-alpha release.TracerX Logger/Viewer for .NET: 4.0: View this CodeProject article for documentation on how to use the latest version of the Logger. About the DownloadsVersion: 4.0.1005.1163 Changese...VCC: Latest build, v2.1.30503.0: Automatic drop of latest buildVisual Studio DSite: Lottery Game (Visual C++ 2008): An advanced lottery game made in visual c 2008.VivoSocial: VivoSocial 7.1.3: Version 7.1.3 of VivoSocial has been released. If you experienced any issues with the previous version, please update your modules to the 7.1.3 rel...Xrns2XMod: Xrns2XMod 1.0: Features added Conversion of all possible convertible features between Renoise and MOD / XM. FlacBox lib updated (thanks to Yuri) NAudio lib in...Most Popular ProjectsRawrWBFS ManagerAJAX Control ToolkitMicrosoft SQL Server Product Samples: Databasepatterns & practices – Enterprise LibrarySilverlight ToolkitiTuner - The iTunes CompanionWindows Presentation Foundation (WPF)ASP.NETDotNetNuke® Community EditionMost Active ProjectsIonics Isapi Rewrite Filterpatterns & practices – Enterprise LibraryRawrHydroServer - CUAHSI Hydrologic Information System ServerAJAX Control Frameworkpatterns & practices: Azure Security GuidanceNB_Store - Free DotNetNuke Ecommerce Catalog ModuleBlogEngine.NETTinyProjectDambach Linear Algebra Framework

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  • Unable to use pbcopy while in tmux session

    - by user62139
    Running tmux 1.4 installed from ports on snow-leopard I am unable to use the built in OSX pbcopy command. Outside of tmux: > echo "abc" | pbcopy > echo pbpaste # or using ^v abc But inside of tmux: > echo "123" | pbcopy > echo pbpaste abc I've scoured the man page but can't find any options that might relate to this behaivor. I also can't understand why tmux would mess with shell redirection. Anybody have any clues?

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  • Reset DRAC/MC password on Dell BladeCentre 1855

    - by Farseeker
    I have a Dell Blade Centre 1855, and nobody knows what the root password for the DRAC/MC card in the blade chassis is (I tried root/calvin). I do not have IP access to the DRAC/MC, nor do I have physical access to the back of the blade centre to access the DRAC/MC module. I do have serial access (and can see the login prompt in hyperterm). I do have physical access to the FRONT of the chassis (the back of the cabinet is locked and lo-and-behold the key cannot be found). Does anyone know how to reset the password? Every piece of literature I find on the internet tells me I need to log in, or run racadm on the host machine (which I can't, because it's inside a blade chassis). If someone does know how to do it with physical access to the back of the bladecentre, please post it anyway, as I'm sure I'll get access to the back of the cabinet one day)

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  • What is ADO ?

    - by Aamir Hasan
    What is ADO? ADO is a Microsoft technologyADO stands for ActiveX Data ObjectsADO is a Microsoft Active-X componentADO is automatically installed with Microsoft IISADO is a programming interface to access data in a databaseAccessing a Database from an ASP Page The common way to access a database from inside an ASP page is to: Create an ADO connection to a databaseOpen the database connectionCreate an ADO recordsetOpen the recordsetExtract the data you need from the recordsetClose the recordsetClose the connectionExample  <%set conn=Server.CreateObject("ADODB.Connection")conn.Provider="Microsoft.Jet.OLEDB.4.0"conn.Open(Server.Mappath("/db/northwind.mdb"))set rs = Server.CreateObject("ADODB.recordset")rs.Open "Select * from Customers", conndo until rs.EOF    for each x in rs.Fields       Response.Write(x.name)       Response.Write(" = ")       Response.Write(x.value & "<br />")    next    Response.Write("<br />")    rs.MoveNextlooprs.closeconn.close%> 

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  • Welcome to the SOA &amp; E2.0 Partner Community Forum

    - by Jürgen Kress
    With more than 200 registrations the SOA & E2.0 Partner Community Forum is a huge success!   Conference program Is available online: http://tinyurl.com/soaforumagenda Agenda Tuesday March 15th 2011 12:15 Welcome & Introduction – Hans Blaas & Jürgen Kress, Oracle 12:30 Oracle Middleware Strategy and Information on Application Grid and Exalogic - Andrew Sutherland, Oracle 13:15 Managing Online Customer, Partner and Employee Engagement Oracle E2.0 Solutions - Andrew Gilboy, Oracle 14:00 Coffee Break 14:30 Partner SOA/ BPM Reference Case – Leon Smiers, Capgemini 15:15 Partner WebCenter/ UCM Reference Case – Vikram Setia, Infomentum 16.00 Break 16.30 SOA and BPM 11gR1 PS3 Update – David Shaffer 17:00 Why specialization is important for Partners – Nick Kritikos, Hans Blaas & Jürgen Kress 17:45 Social Event   Wednesday March 16th 2011 09.00 Welcome & Introduction Day II 09.15 Breakout sessions Round 1 SOA Suite 11g PS3 & OSB Importance of ADF & Jdeveloper SOA Security IDM WebCenter PS3, Whats New E2.0 Sales Plays 10.30 Break 10.45 Breakout sessions Round 2 WebCenter PS3, Whats New Applications Management Enterprise Manager and Amberpoint ADF/WebCenter 11g integration with BPM Suite 11g Importance of ADF & Jdeveloper JCAPS & OC4J migration opportunities for service business 12.00 Lunch 13.00 Breakout sessions Round 3 BPM 11g, Whats New Universal Content Management! 11g SOA Security IDM E2.0 Surrounding Products: ATG, Documaker, Primavera Middleware Industry Value Propositions & Sales Plays 14.30 Break 14.45 Fusion Applications, Rajan Krishnan, Oracle 15.30 SOA & E2.0 Summary & Closing, Hans Blaas & Jürgen Kress, Oracle 15.45 Finish & Departure 16:00 Bus departure   Capgemini Nederland BV Papendorpseweg 100 3500 GN Utrecht The Netherlands Tel: +31 30 689 00 00 For a detailed routedescription by car or public transport please visit: http://www.nl.capgemini.com/pdf/Papendorp_UK.pdf Hotel In case you have not booked your hotel yet, please make your own hotel reservation. You can book your hotel room at the 'Hotel Vianen' at a special rate, by using the Oracle booking code: DDG VIA-GF41422. One night package € 110,- for a single room, including breakfast. Kindly secure your hotel room as soon as possible. The number of rooms is limited! Hotel Vianen Prins Bernhardstraat 75 4132 XE Vianen [email protected] The Netherlands [email protected] Arrival on 14th of March and staying at Hotel Vianen. On 15th of March we have arranged a transfer from Hotel Vianen to the Capgemini Offices. The bus is parked in front of the hotel and will leave at 10.15AM (UTC/GMT+1). Logistics Pass with barcode At your arrival you will receive a pass with a barcode. This pass will give you access to the conference building and the different floors within the building. Please make sure to hand in your pass at the registration desk at the end of the day. Arrival by plane Transfer from Schiphol Airport to Capgemini on 15th of March will be arranged by Oracle. A hostess will be welcoming you at the Meeting Point at Schiphol Airport (this is a red and white large cubicle situated next to Delifrance) The buses will depart from Schiphol Airport at 09.00AM, 09.45AM and 10.30AM (UTC/GMT+1).     For future SOA Partner Community Forums  become a member for registration please visit www.oracle.com/goto/emea/soa (OPN account required) Blog Twitter LinkedIn Mix Forum Wiki Website Technorati Tags: SOA Partner Community Forum,Community,SOA Partner Community,Utrecht 03.2011,OPN,Oracle,Jürgen Kress

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  • Reverse proxy with SSL and IP passthrough?

    - by Paul
    Turns out that the IP of a much-needed new website is blocked from inside our organization's network for reasons that will take weeks to fix. In the meantime, could we set up a reverse proxy on an Internet-based server which will forward SSL traffic and perhaps client IPs to the external site? Load will be light. No need to terminate SSL on the proxy. We may be able to poison DNS so original URL can work. How do I learn if I need URL rewriting? Squid/apache/nginx/something else? Setup would be fastest on Win 2000, but other OSes are OK if that would help. Simple and quick are good since it's a temporary solution. Thanks for your thoughts!

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  • Segmentation Fault (11) with modwsgi on CentOS 5.7 when running pyramid app

    - by carbotex
    I'm getting Segmentation fault error when trying to access the "Hello World" pyramid app. This error only occurs when running against CentOS 5.7 setup, but no problem whatsoever when tested against OSX and Arch Linux. Could it be a CentOS specific issue? [error] [client 10.211.55.2] Premature end of script headers: pyramid.wsgi [notice] child pid 31212 exit signal Segmentation fault (11) I have tried to follow the troubleshooting guides posted here http://code.google.com/p/modwsgi/wiki/InstallationIssues which suggests that it might caused by missing Shared Library. A quick check reveals that shared library is not the issue. [centos57@localhost modules]$ ldd mod_wsgi.so linux-gate.so.1 => (0x00e6a000) libpython2.7.so.1.0 => /home/python/lib/libpython2.7.so.1.0 (0x0024c000) libpthread.so.0 => /lib/libpthread.so.0 (0x00da8000) libdl.so.2 => /lib/libdl.so.2 (0x00cd6000) libutil.so.1 => /lib/libutil.so.1 (0x00110000) libm.so.6 => /lib/libm.so.6 (0x0085c000) libc.so.6 => /lib/libc.so.6 (0x00682000) /lib/ld-linux.so.2 (0x0012b000) Then I found another clue that might be able to solve my problem. Unfortunately libexpat is not the source of the problem. http://code.google.com/p/modwsgi/wiki/IssuesWithExpatLibrary [centos57@localhost bin]$ ldd ~/httpd/bin/httpd | grep expat libexpat.so.1 => /usr/local/lib/libexpat.so.1 (0x00b00000) [centos57@localhost bin]$ strings /usr/local/lib/libexpat.so.1 | grep expat libexpat.so.1 expat_2.0.1 [centos57@localhost bin]$ python Python 2.7.2 (default, Nov 26 2011, 08:08:44) [GCC 4.1.2 20080704 (Red Hat 4.1.2-51)] on linux2 Type "help", "copyright", "credits" or "license" for more information. >>> import pyexpat >>> pyexpat.version_info (2, 0, 0) >>> I've been pulling my hair out trying to figure out what I'm missing in my setup. Why the problem only occurs with CentOS? Here is the detailed setup: Apache 2.2.19 Python 2.7.2 mod_wsgi-3.3 /home/httpd/conf/extra/pyramid.wsgi from pyramid.paster import get_app application = get_app('/home/homecamera/hcadmin/root/production.ini', 'main') /home/httpd/conf/extra/modwsgi.conf LoadModule wsgi_module modules/mod_wsgi.so WSGIScriptAlias /myapp /home/root/test.wsgi <Directory /home/root> WSGIProcessGroup pyramid Order allow,deny Allow from all </Directory> # Use only 1 Python sub-interpreter. Multiple sub-interpreters # play badly with C extensions. WSGIApplicationGroup %{GLOBAL} WSGIPassAuthorization On WSGIDaemonProcess pyramid user=daemon group=daemon processes=1 \ threads=4 \ python-path=/home/python/lib/python2.7/site-packages WSGIScriptAlias /hello /home/httpd/conf/extra/pyramid.wsgi <Directory /home/httpd/conf/extra> WSGIProcessGroup pyramid Order allow,deny Allow from all </Directory> Again this same setup works on OSX and Arch Linux but not on CentOS 5.7. Could someone out there point me to the right direction before I ran out of my hair. ==================================================================================== When apache started with gdb, I got a couple of warnings Reading symbols from /home/httpd/bin/httpd...done. Attaching to program: /home/httpd/bin/httpd, process 1821 warning: .dynamic section for "/lib/libcrypt.so.1" is not at the expected address warning: difference appears to be caused by prelink, adjusting expectations warning: .dynamic section for "/lib/libutil.so.1" is not at the expected address warning: difference appears to be caused by prelink, adjusting expectations gdb output. After hitting refresh button, to load pyramid. (gdb) cont Continuing. warning: .dynamic section for "/usr/lib/libgssapi_krb5.so.2" is not at the expected address warning: difference appears to be caused by prelink, adjusting expectations warning: .dynamic section for "/usr/lib/libkrb5.so.3" is not at the expected address warning: difference appears to be caused by prelink, adjusting expectations warning: .dynamic section for "/lib/libresolv.so.2" is not at the expected address warning: difference appears to be caused by prelink, adjusting expectations Program received signal SIGSEGV, Segmentation fault. [Switching to Thread 0x8edbb90 (LWP 1824)] 0x0814c120 in EVP_PKEY_CTX_dup () apache_error_log [info] mod_wsgi (pid=1821): Starting process 'pyramid' with threads=1. [info] mod_wsgi (pid=1821): Initializing Python. [info] mod_wsgi (pid=1821): Attach interpreter ''. [info] mod_wsgi (pid=1821): Create interpreter 'web.domain.com:20000|/hcadmin'. [info] [client 10.211.55.2] mod_wsgi (pid=1821, process='pyramid', application='web.domain.com:20000|/hcadmin'): Loading WSGI script '/home/httpd/conf/extra/pyramid.wsgi'. [error] hello 1

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  • Linux Mint 13 64bit Cinnamon and Oracle Virtualbox: 3d acceleration crash

    - by Stephen Swensen
    I've recently got an interest in Linux. After some research, it looks like Linux Mint 13 cinnamon is hot and I thought I'd try it out... I'm running Windows 7 64bit and have experience with Oracle Virtual Box. So I thought it would be a good idea to try out Linux Mint inside Virtual Box. I download Linux Mint 13 64bit Cinnamon and set it up in my VM player... Nothing special about my settings. Except Linux Mint 13 Cinnamon requires 3d acceleration, and when I enable that, it crashes whenever I open the Menu in the bottom left corner of the guest OS (and some other times too)... I've seen other mentions of this problem on the web, but no solutions. Is there a solution? If not, any suggestions short of installing the OS on a partition for trying out this OS (I'm not interested in the LIve mode either - I'd really like to get the full feel for it)?

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  • links for 2010-04-15

    - by Bob Rhubart
    e-Energy 2010 in Passau : Franz Haberhauer's Weblog Fresh off his participation in a panel at the 1st Int' Conf. on Energy-Efficient Computing and Networking at the University of Passau, Germany, Franz Haberhauer offers some background on the CoolThreads/Chip Mulitthreading Technology and its role in greener datacenters. (tags: oracle sun datacenter Mulitthreading) Oracle Enterprise Manager Grid Control: New Recommended Bundle Patch (APR 2010) - 9405592 for Patch Automation on EM 10.2.0.5 Notes and a short FAQ on the Recommended Bundle Patch 9405592 for Oracle Enterprise Manager Grid Control. (tags: architect entarch grid oracle otn) Vijaykumar Yenne: Customizing Spaces UI Vijaykumar Yyenne explains how to leverage the Extend Spaces Project on the Oracle Technology Network to customize Oracle WebCenter site templates. (tags: enterprise2.0 oracle otn webcenter) Knut Vatsendvik: Catch Me If You Can "Suppose you have a Proxy based Web Service using Oracle Service Bus. In a stage in the request pipeline, you are using a Publish action to publish the incoming message to a JMS queue using a Business Service. What if the outbound transport provider throws an exception (outside of your pipeline)? Is your pipeline able to catch the error with an error handler?" -- Knut Vatsendvik (tags: oracle otn soa esb weblogic architect) Pete Wang: Coherence Configuration For Multiple HA SOA Domains Quick tips from Pete Wang on the Oracle Coherence settings necessary for creating multiple SOA HA domains. (tags: architect coherence oracle otn soa) Warren Baird: New Walkthrough Capability in AutoVue 20 Warren Baird describes new features in Oracle AutoVue 20 that allow viewing a 3D model of a building from the inside. (tags: architect entarch oracle otn) Peter Wang: How to implement multi-source XSLT mapping in Oracle SOA Suite 11g BPEL In SOA 11g, you can create a XSLT mapper that uses multiple sources as the input. Pete Wang shows you how. (tags: oracle otn soa bpel architect)

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  • To have a long life with the battery it has to be separated from the Laptop after each use

    - by laptopo1 dsad
    To have a long life with the battery it has to be separated from the Laptop after each use Developing a Laptop and concern about it's battery life Don't be concerned follow this advice how to deal with your Laptop battery. A fresh power supply of your Laptop can be purchased in a very low charge condition, and must be fully charged before use. A different battery pack needs to be fully charged and fully discharged or cycled as much as five times to condition them into performing at full capacity. And also refer your manual instructions of one's Laptop for charging instructions. Inspiron 15z battery Tips: Unplug battery after use: To have a long life with the battery it has to be separated from the Laptop after each use. Clean battery contacts often: Clean your battery's metal contacts once in a month with a cloth moistened with rubbing alcohol. This prevents the transfer of power out of your battery additional efficient. Turn off the WiFi and Bluetooth, in any other case being used: Usually, we activate our WiFi or Bluetooth for whatever reason and tend to forget to Off it, that could spark a huge relieve your battery, Shut off right after the usage. Dell XPS L501x battery Dim notebook screen: When you're with your Laptop in Daytime, you will need for full brightness. But also in case of Night, just dim the screen reducing brightness, which will consume more charge once the brightness might be more and also It's essential on your eyes to determine lesser brighten screen inside nights. Dell Inspiron 17R battery Have hardly any Background programs: Letting more programs to own behind the screen could consume more Dell Inspiron N4010 battery charge hence have very few without background programs are Better. Make use of the Hard disk drive more than CD/DVD drive: Making use of disc drive instead your CD/DVD drive could consume less battery power. Latitude E5400 Battery

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  • DDD Melbourne -lessons leant

    - by Michael Freidgeim
    I've attended DDD Melbourne and want to list the interesting points, that I've leant and want to follow. To read more: * Moles-Mocking Isolation framework for .NET. Documentation is here.   (See also Mocking frameworks comparison created October 4, 2009 ) * WebFormsMVP * PluralSight   http://www.pluralsight-training.net/offers/default.aspx?cc=trial   * ELMAH: Error Logging Modules and Handlers *Rhino.Mocks   * VS UI Test Recorder -see posts Visual Studio 2010 Coded UI Test User Guide. Note that Microsoft Test Manager (MTM) toolis a separate application, that can be started from Program files/VS 2010 menu.It is not a menu inside Visual Studio.   * CodeContract- seems great in Debug. Will be good if in production  will be possible runtime configuration, ability to log instead of throw exception. Current recommendation to customize Debug.Assert is not trivial The programmer is free to use the customization provided by Debug.Assert using assert listeners to obtain whatever runtime behavior they desire (e.g., ignoring the error, logging it, or throwing an exception).   // Clears the existing list of assert listener (the default pop-up box) System.Diagnostics.Debug.Listeners.Clear(); // Install your own listener System.Diagnostics.Debug.Listeners.Add(MyTraceListener); Note that you can't catch specific ContractException, but can catch generic Exception(see How come you cannot catch Code Contract exceptions?)   Books recommended "Working effectively with legacy code" by Michael Feathers (corresponding article)   Fowler, Martin Refactoring: Improving the Design of Existing Code, slides http://jaoo.dk/jaoo1999/schedule/MartinFowlerRefractoring.pdf

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  • shared hosting: ssl domain receives all server's ssl requests, google gets it wrong

    - by pixeline
    This website is hosted on a shared server. I've recently had my hosting provider secure our website using SSL (https://domain.com instead of http://domain.com). Ever since then, all https requests sent to the server are redirected to my website. https://otherdomain.com leads to a warning, then, if you continue, to my website. Ok, my fault, i should have known SSL means 1 IP, otherwise, this thing can happen. But... Google Search results for my website's target keywords is now displaying these websites above my own, even though they have nothing even remotely related to the target keywords! already done: provide canonical url in the html page. told the problem to the server manager, who tells me it's normal but he'll look for a solution. This was one week ago, no answer since. I have no idea why Google is providing these https urls: i thought someone would have to submit them, or have them inside an html page in order for Google to actually index dummy https domains, but i see no reason why someone would do that. Any suggestion on how to solve this situation? Golive is in one week and SEO looks really bad because of that.

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  • Mac OS X - Force screen resolution

    - by wjlafrance
    Hello! I'm trying to use the lastest version of a certain development tool and it's sort of difficult to use on a 1200x800 display. Using VMWare Fusion, I can set the screen resolution inside a VM to 1900x1200 on my 13" MBP and it's still usable. Does anyone know of a way to force Mac OS X to scale it's resolution? I tried ScreenResX and it said the scaled resolution was "invalid" or something like that. I know that there are only a certain number of pixels on the screen. I'm only asking how to scale, not set a legit resolution. My current hack solution is to run Snow Leopard Server in a VM with resolution scaling.

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  • Can you use a USB hard drive in ESXI?

    - by semi
    I know that you can install ESXi 4.0 on a thumbdrive, but I was wondering if you could plug in an external harddrive to give extra storage to one of your VMs? We run a fileserver inside of ESXi that needs a space upgrade, but we're thinking of migrating to a different fileserver solution and would rather stick to external media to ease the later transition. edit: Ideally I'd like the drive to show up to the VM directly and not have ESXi control it, so that I could move it to a different machine and still have all of the data appear the same.

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  • bind (hardlink) one directory to many places

    - by PoltoS
    I need to "bind" one directory to many chrooted places. I know that I can do "mount -o bind", but this requires special processing on startup each time (run the mount). Is there a way to do it on the filesystem directly? My fs is ext4 and it seems not to support hardlinks to directories. Hardlinking all files inside is not an option too. Is thee a way to enable hardlinks to directories in ext4? Or any other options are avilable?

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  • Facebook: Hide Your Status Updates From Your Boss/Ex or Any Specific Friend

    - by Gopinath
    Sometime we want to hide our status updates from specific people who are already accepted as Friends in Facebook. Do you wonder why we need to accept someone as friend and then hide status updates from them? Well, may be you have to accept a friend request from your boss, but certainly love to hide status updates as well as other Facebook activities from him. Something similar goes with few annoying friends whom you cant’ de-friend but like to hide your updates. Thanks to Facebook for providing fine grain privacy options on controlling what we want to share and with whom we want to share. It’s very easy to block one or more specific friends from seeing your status updates. Here are the step by step instructions: 1. Login to Facebook and go to Privacy Settings Page. It shows a page something similar to what is shown in the below image. 2. Click on “Customize settings” link 3. Expand the privacy options available in the section Things I Share -> Posts by me. Choose Customise from the list of available options   4. Type the list of unwanted friend’s names in to input box of the section "Hide this from”. Here is a screen grab of couple of my friends whom I added for writing this post 5. Click the Save Settings button. That’s all. Facebook will ensure that these people will not see your status updates on their news feed. Enjoyed the Facebook Tip? Join Tech Dreams on Facebook to read all our blog posts on your Facebook’s news feed. Join us on Facebook to read all our stories right inside your Facebook news feed.

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  • When Your Boss Doesn't Want you to Succeed

    - by Phil Factor
    You're working hard to get an application finished. You are programming long into the evenings sometimes, and eating sandwiches at your desk instead of taking a lunch break. Then one day you glance up at the IT manager, serene in his mysterious round of meetings, and think 'Does he actually care whether this project succeeds or not?'. The question may seem absurd. Of course the project must succeed. The truth, as always, is often far more complex. Your manager may even be doing his best to make sure you don't succeed. Why? There have always been rich pickings for the unscrupulous in IT.  In extreme cases, where administrators struggle with scarcely-comprehended technical issues, huge sums of money can be lost and gained without any perceptible results. In a very few cases can fraud be proven: most of the time, the intricacies of the 'game' are such that one can do little more than harbor suspicion.  Where does over-enthusiastic salesmanship end and fraud begin? The Business of Information Technology provides rich opportunities for White-collar crime. The poor developer has his, or her, hands full with the task of wrestling with the sheer complexity of building an application. He, or she, has no time for following the complexities of the chicanery of the management that is directing affairs.  Most likely, the developers wouldn't even suspect that their company management had ulterior motives. I'll illustrate what I mean with an entirely fictional, hypothetical, example. The Opportunist and the Aged Charities often do good, unexciting work that is funded by the income from a bequest that dates back maybe hundreds of years.  In our example, it isn't exciting work, for it involves the welfare of elderly people who have fallen on hard times.  Volunteers visit, giving a smile and a chat, and check that they are all right, but are able to spend a little money on their discretion to ameliorate any pressing needs for these old folk.  The money is made to work very hard and the charity averts a great deal of suffering and eases the burden on the state. Daisy hears the garden gate creak as Mrs Rainer comes up the path. She looks forward to her twice-weekly visit from the nice lady from the trust. She always asked ‘is everything all right, Love’. Cheeky but nice. She likes her cheery manner. She seems interested in hearing her memories, and talking about her far-away family. She helps her with those chores in the house that she couldn’t manage and once even paid to fill the back-shed with coke, the other year. Nice, Mrs. Rainer is, she thought as she goes to open the door. The trustees are getting on in years themselves, and worry about the long-term future of the charity: is it relevant to modern society? Is it likely to attract a new generation of workers to take it on. They are instantly attracted by the arrival to the board of a smartly dressed University lecturer with the ear of the present Government. Alain 'Stalin' Jones is earnest, persuasive and energetic. The trustees welcome him to the board and quickly forgive his humorless political-correctness. He talks of 'diversity', 'relevance', 'social change', 'equality' and 'communities', but his eye is on that huge bequest. Alain first came to notice as a Trotskyite union official, who insinuated himself into one of the duller Trades Unions and turned it, through his passionate leadership, into a radical, headline-grabbing organization.  Middle age, and the rise of European federal socialism, had brought him quiet prosperity and charcoal suits, an ear in the current government, and a wide influence as a member of various Quangos (government bodies staffed by well-paid unelected courtiers).  He was employed as a 'consultant' by several organizations that relied on government contracts. After gaining the confidence of the trustees, and showing a surprising knowledge of mundane processes and the regulatory framework of charities, Alain launches his plan.  The trust will expand their work by means of a bold IT initiative that will coordinate the interventions of several 'caring agencies', and provide  emergency cover, a special Website so anxious relatives can see how their elderly charges are doing, and a vastly more efficient way of coordinating the work of the volunteer carers. It will also provide a special-purpose site that gives 'social networking' facilities, rather like Facebook, to the few elderly folk on the lists with access to the internet. The trustees perk up. Their own experience of the internet is restricted to the occasional scanning of railway timetables, but they can see that it is 'relevant'. In his next report to the other trustees, Alain proudly announces that all this glamorous and exciting technology can be paid for by a grant from the government. He admits darkly that he has influence. True to his word, the government promises a grant of a size that is an order of magnitude greater than any budget that the trustees had ever handled. There was the understandable proviso that the company that would actually do the IT work would have to be one of the government's preferred suppliers and the work would need to be tendered under EU competition rules. The only company that tenders, a multinational IT company with a long track record of government work, quotes ten million pounds for the work. A trustee questions the figure as it seems enormous for the reasonably trivial internet facilities being built, but the IT Salesmen dazzle them with presentations and three-letter acronyms until they subside into quiescent acceptance. After all, they can’t stay locked in the Twentieth century practices can they? The work is put in hand with a large project team, in a splendid glass building near west London. The trustees see rooms of programmers working diligently at screens, and who talk with enthusiasm of the project. Paul, the project manager, looked through his resource schedule with growing unease. His initial excitement at being given his first major project hadn’t lasted. He’d been allocated a lackluster team of developers whose skills didn’t seem right, and he was allowed only a couple of contractors to make good the deficit. Strangely, the presentation he’d given to his management, where he’d saved time and resources with a OTS solution to a great deal of the development work, and a sound conservative architecture, hadn’t gone down nearly as big as he’d hoped. He almost got the feeling they wanted a more radical and ambitious solution. The project starts slipping its dates. The costs build rapidly. There are certain uncomfortable extra charges that appear, such as the £600-a-day charge by the 'Business Manager' appointed to act as a point of liaison between the charity and the IT Company.  When he appeared, his face permanently split by a 'Mr Sincerity' smile, they'd thought he was provided at the cost of the IT Company. Derek, the DBA, didn’t have to go to the server room quite some much as he did: but It got him away from the poisonous despair of the development group. Wave after wave of events had conspired to delay the project.  Why the management had imposed hideous extra bureaucracy to cover ISO 9000 and 9001:2008 accreditation just as the project was struggling to get back on-schedule was  beyond belief.  Then  the Business manager was coming back with endless changes in scope, sorrowing saying that the Trustees were very insistent, though hopelessly out in touch with the reality of technical challenges. Suddenly, the costs mount to the point of consuming the government grant in its entirety. The project remains tantalizingly just out of reach. Alain Jones gives an emotional rallying speech at the trustees review meeting, urging them not to lose their nerve. Sadly, the trustees dip into the accumulated capital of the trust, the seed-corn of all their revenues, in order to save the IT project. A few months later it is all over. The IT project is never delivered, even though it had seemed so incredibly close.  With the trust's capital all gone, the activities it funded have to be terminated and the trust becomes just a shell. There aren't even the funds to mount a legal challenge against the IT company, even had the trust's solicitor advised such a foolish thing. Alain leaves as suddenly as he had arrived, only to pop up a few months later, bronzed and rested, at another charity. The IT workers who were permanent employees are dispersed to other projects, and the contractors leave to other contracts. Within months the entire project is but a vague memory. One or two developers remain  puzzled that their managers had been so obstructive when they should have welcomed progress toward completion of the project, but they put it down to incompetence and testosterone. Few suspected that they were actively preventing the project from getting finished. The relationships between the IT consultancy, and the government of the day are intricate, and made more complex by the Private Finance initiatives and political patronage.  The losers in this case were the taxpayers, and the beneficiaries of the trust, and, perhaps the soul of the original benefactor of the trust, whose bid to give his name some immortality had been scuppered by smooth-talking white-collar political apparatniks.  Even now, nobody is certain whether a crime was ever committed. The perfect heist, I guess. Where’s the victim? "I hear that Daisy’s cottage is up for sale. She’s had to go into a care home.  She didn’t want to at all, but then there is nobody to keep an eye on her since she had that minor stroke a while back.  A charity used to help out. The ‘social’ don’t have the funding, evidently for community care. Yes, her old cat was put down. There was a good clearout, and now the house is all scrubbed and cleared ready for sale. The skip was full of old photos and letters, memories. No room in her new ‘home’."

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  • OpenGL: Where shoud I place shaders?

    - by mivic
    I'm trying to learn OpenGL ES 2.0 and I'm wondering what is the most common practice to "manage" shaders. I'm asking this question because in the examples I've found (like the one included in the API Demo provided with the android sdk), I usually see everything inside the GLRenderer class and I'd rather separate things so I can have, for example, a GLImage object that I can reuse whenever I want to draw a textured quad (I'm focusing on 2D only at the moment), just like I had in my OpenGL ES 1.0 code. In almost every example I've found, shaders are just defined as class attributes. For example: public class Square { public final String vertexShader = "uniform mat4 uMVPMatrix;\n" + "attribute vec4 aPosition;\n" + "attribute vec4 aColor;\n" + "varying vec4 vColor;\n" + "void main() {\n" + " gl_Position = uMVPMatrix * aPosition;\n" + " vColor = aColor;\n" + "}\n"; public final String fragmentShader = "precision mediump float;\n" + "varying vec4 vColor;\n" + "void main() {\n" + " gl_FragColor = vColor;\n" + "}\n"; // ... } I apologize in advance if some of these questions are dumb, but I've never worked with shaders before. 1) Is the above code the common way to define shaders (public final class properties)? 2) Should I have a separate Shader class? 3) If shaders are defined outside the class that uses them, how would I know the names of their attributes (e.g. "aColor" in the following piece of code) so I can bind them? colorHandle = GLES20.glGetAttribLocation(program, "aColor");

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  • C#/.NET Little Wonders: The EventHandler and EventHandler&lt;TEventArgs&gt; delegates

    - by James Michael Hare
    Once again, in this series of posts I look at the parts of the .NET Framework that may seem trivial, but can help improve your code by making it easier to write and maintain. The index of all my past little wonders posts can be found here. In the last two weeks, we examined the Action family of delegates (and delegates in general), and the Func family of delegates and how they can be used to support generic, reusable algorithms and classes. So this week, we are going to look at a handy pair of delegates that can be used to eliminate the need for defining custom delegates when creating events: the EventHandler and EventHandler<TEventArgs> delegates. Events and delegates Before we begin, let’s quickly consider events in .NET.  According to the MSDN: An event in C# is a way for a class to provide notifications to clients of that class when some interesting thing happens to an object. So, basically, you can create an event in a type so that users of that type can subscribe to notifications of things of interest.  How is this different than some of the delegate programming that we talked about in the last two weeks?  Well, you can think of an event as a special access modifier on a delegate.  Some differences between the two are: Events are a special access case of delegates They behave much like delegates instances inside the type they are declared in, but outside of that type they can only be (un)subscribed to. Events can specify add/remove behavior explicitly If you want to do additional work when someone subscribes or unsubscribes to an event, you can specify the add and remove actions explicitly. Events have access modifiers, but these only specify the access level of those who can (un)subscribe A public event, for example, means anyone can (un)subscribe, but it does not mean that anyone can raise (invoke) the event directly.  Events can only be raised by the type that contains them In contrast, if a delegate is visible, it can be invoked outside of the object (not even in a sub-class!). Events tend to be for notifications only, and should be treated as optional Semantically speaking, events typically don’t perform work on the the class directly, but tend to just notify subscribers when something of note occurs. My basic rule-of-thumb is that if you are just wanting to notify any listeners (who may or may not care) that something has happened, use an event.  However, if you want the caller to provide some function to perform to direct the class about how it should perform work, make it a delegate. Declaring events using custom delegates To declare an event in a type, we simply use the event keyword and specify its delegate type.  For example, let’s say you wanted to create a new TimeOfDayTimer that triggers at a given time of the day (as opposed to on an interval).  We could write something like this: 1: public delegate void TimeOfDayHandler(object source, ElapsedEventArgs e); 2:  3: // A timer that will fire at time of day each day. 4: public class TimeOfDayTimer : IDisposable 5: { 6: // Event that is triggered at time of day. 7: public event TimeOfDayHandler Elapsed; 8:  9: // ... 10: } The first thing to note is that the event is a delegate type, which tells us what types of methods may subscribe to it.  The second thing to note is the signature of the event handler delegate, according to the MSDN: The standard signature of an event handler delegate defines a method that does not return a value, whose first parameter is of type Object and refers to the instance that raises the event, and whose second parameter is derived from type EventArgs and holds the event data. If the event does not generate event data, the second parameter is simply an instance of EventArgs. Otherwise, the second parameter is a custom type derived from EventArgs and supplies any fields or properties needed to hold the event data. So, in a nutshell, the event handler delegates should return void and take two parameters: An object reference to the object that raised the event. An EventArgs (or a subclass of EventArgs) reference to event specific information. Even if your event has no additional information to provide, you are still expected to provide an EventArgs instance.  In this case, feel free to pass the EventArgs.Empty singleton instead of creating new instances of EventArgs (to avoid generating unneeded memory garbage). The EventHandler delegate Because many events have no additional information to pass, and thus do not require custom EventArgs, the signature of the delegates for subscribing to these events is typically: 1: // always takes an object and an EventArgs reference 2: public delegate void EventHandler(object sender, EventArgs e) It would be insane to recreate this delegate for every class that had a basic event with no additional event data, so there already exists a delegate for you called EventHandler that has this very definition!  Feel free to use it to define any events which supply no additional event information: 1: public class Cache 2: { 3: // event that is raised whenever the cache performs a cleanup 4: public event EventHandler OnCleanup; 5:  6: // ... 7: } This will handle any event with the standard EventArgs (no additional information).  But what of events that do need to supply additional information?  Does that mean we’re out of luck for subclasses of EventArgs?  That’s where the generic for of EventHandler comes into play… The generic EventHandler<TEventArgs> delegate Starting with the introduction of generics in .NET 2.0, we have a generic delegate called EventHandler<TEventArgs>.  Its signature is as follows: 1: public delegate void EventHandler<TEventArgs>(object sender, TEventArgs e) 2: where TEventArgs : EventArgs This is similar to EventHandler except it has been made generic to support the more general case.  Thus, it will work for any delegate where the first argument is an object (the sender) and the second argument is a class derived from EventArgs (the event data). For example, let’s say we wanted to create a message receiver, and we wanted it to have a few events such as OnConnected that will tell us when a connection is established (probably with no additional information) and OnMessageReceived that will tell us when a new message arrives (probably with a string for the new message text). So for OnMessageReceived, our MessageReceivedEventArgs might look like this: 1: public sealed class MessageReceivedEventArgs : EventArgs 2: { 3: public string Message { get; set; } 4: } And since OnConnected needs no event argument type defined, our class might look something like this: 1: public class MessageReceiver 2: { 3: // event that is called when the receiver connects with sender 4: public event EventHandler OnConnected; 5:  6: // event that is called when a new message is received. 7: public event EventHandler<MessageReceivedEventArgs> OnMessageReceived; 8:  9: // ... 10: } Notice, nowhere did we have to define a delegate to fit our event definition, the EventHandler and generic EventHandler<TEventArgs> delegates fit almost anything we’d need to do with events. Sidebar: Thread-safety and raising an event When the time comes to raise an event, we should always check to make sure there are subscribers, and then only raise the event if anyone is subscribed.  This is important because if no one is subscribed to the event, then the instance will be null and we will get a NullReferenceException if we attempt to raise the event. 1: // This protects against NullReferenceException... or does it? 2: if (OnMessageReceived != null) 3: { 4: OnMessageReceived(this, new MessageReceivedEventArgs(aMessage)); 5: } The above code seems to handle the null reference if no one is subscribed, but there’s a problem if this is being used in multi-threaded environments.  For example, assume we have thread A which is about to raise the event, and it checks and clears the null check and is about to raise the event.  However, before it can do that thread B unsubscribes to the event, which sets the delegate to null.  Now, when thread A attempts to raise the event, this causes the NullReferenceException that we were hoping to avoid! To counter this, the simplest best-practice method is to copy the event (just a multicast delegate) to a temporary local variable just before we raise it.  Since we are inside the class where this event is being raised, we can copy it to a local variable like this, and it will protect us from multi-threading since multicast delegates are immutable and assignments are atomic: 1: // always make copy of the event multi-cast delegate before checking 2: // for null to avoid race-condition between the null-check and raising it. 3: var handler = OnMessageReceived; 4: 5: if (handler != null) 6: { 7: handler(this, new MessageReceivedEventArgs(aMessage)); 8: } The very slight trade-off is that it’s possible a class may get an event after it unsubscribes in a multi-threaded environment, but this is a small risk and classes should be prepared for this possibility anyway.  For a more detailed discussion on this, check out this excellent Eric Lippert blog post on Events and Races. Summary Generic delegates give us a lot of power to make generic algorithms and classes, and the EventHandler delegate family gives us the flexibility to create events easily, without needing to redefine delegates over and over.  Use them whenever you need to define events with or without specialized EventArgs.   Tweet Technorati Tags: .NET, C#, CSharp, Little Wonders, Generics, Delegates, EventHandler

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  • Trouble using remote desktop when connected via Cisco VPN

    - by Kyle B.
    I just setup my Cisco VPN and everything appears to be working fine. I opened the 'remote desktop' application and am unable to connect to my work desktop machine. When I disable Windows Firewall, I am able to connect, but not when Firewall is enabled. Is there a specific settings inside Windows 7 Firewall that should I be enabling or disabling for this to work without having to shut down the entire system? I can post this in superuser.com instead if you feel it belongs there, but posted here due to it being related to VPN and Firewall. Thanks, Kyle

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  • MySQL Federated Tables Escaped Table Names

    - by Gordon
    I am trying to use MySQL federated tables. The problem is that the documentation specified at http://dev.mysql.com/doc/refman/5.0/en/federated-use.html says that a federated table should be created using the following format for the CONNECTION parameter: scheme://user_name[:password]@host_name[:port_num]/db_name/tbl_name E.G. CONNECTION='mysql://username:password@hostname:port/database/tablename' CONNECTION='mysql://username@hostname/database/tablename' CONNECTION='mysql://username:password@hostname/database/tablename' The problem is that the table I am trying to connect to has non-standard characters in it and I cannot find the proper way to scape them in the connections tring. For example, a table named `Table (one)` . Which has the space and the parenthesis, requiring backticks surrounding it inside any SQL code. Anyone know the proper way to do this?

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  • Server Administration

    - by Kassem
    Hi everyone, My client asked me for a job description of a system administration because I might be assigned this position along with the other guy I'm working with. To be honest, I do not know much about a System Administrator's job but I'm willing to learn. Questions: What are the security requirements of a server? * What are the key responsibilities in a system admin's job description? What are some of the day to day tasks of a system admin? What is the average monthly salary of a system admin? Note: I will be working inside a Windows environment. But your replies do not necessarily need to be constricted to a Windows environment. (*) Other software I know will be required are: Windows Server 2008 IIS 7.0 MS SQL Server .NET 4.0 Runtime Let me know if there are other things I should be aware of as well. Thanks!

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