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• openvpn WARNING: No server certificate verification method has been enabled

  - by tmedtcom

  I tried to install openvpn on debian squeez (server) and connect from my fedora 17 as (client). Here is my configuration: server configuration ###cat server.conf # Serveur TCP ** proto tcp** port 1194 dev tun # Cles et certificats ca /etc/openvpn/easy-rsa/keys/ca.crt cert /etc/openvpn/easy-rsa/keys/server.crt key /etc/openvpn/easy-rsa/keys/server.key dh /etc/openvpn/easy-rsa/keys/dh1024.pem # Reseau #Adresse virtuel du reseau vpn server 192.170.70.0 255.255.255.0 #Cette ligne ajoute sur le client la route du reseau vers le serveur push "route 192.168.1.0 255.255.255.0" #Creer une route du server vers l'interface tun. #route 192.170.70.0 255.255.255.0 # Securite keepalive 10 120 #type d'encryptage des données **cipher AES-128-CBC** #activation de la compression comp-lzo #nombre maximum de clients autorisés max-clients 10 #pas d'utilisateur et groupe particuliers pour l'utilisation du VPN user nobody group nogroup #pour rendre la connexion persistante persist-key persist-tun #Log d'etat d'OpenVPN status /var/log/openvpn-status.log #logs openvpnlog /var/log/openvpn.log log-append /var/log/openvpn.log #niveau de verbosité verb 5 ###cat client.conf # Client client dev tun [COLOR="Red"]proto tcp-client[/COLOR] remote <my server wan IP> 1194 resolv-retry infinite **cipher AES-128-CBC** # Cles ca ca.crt cert client.crt key client.key # Securite nobind persist-key persist-tun comp-lzo verb 3 Message from the host client (fedora 17) in the log file / var / log / messages: Dec 6 21:56:00 GlobalTIC NetworkManager[691]: <info> Starting VPN service 'openvpn'... Dec 6 21:56:00 GlobalTIC NetworkManager[691]: <info> VPN service 'openvpn' started (org.freedesktop.NetworkManager.openvpn), PID 7470 Dec 6 21:56:00 GlobalTIC NetworkManager[691]: <info> VPN service 'openvpn' appeared; activating connections Dec 6 21:56:00 GlobalTIC NetworkManager[691]: <info> VPN plugin state changed: starting (3) Dec 6 21:56:01 GlobalTIC NetworkManager[691]: <info> VPN connection 'Connexion VPN 1' (Connect) reply received. Dec 6 21:56:01 GlobalTIC nm-openvpn[7472]: OpenVPN 2.2.2 x86_64-redhat-linux-gnu [SSL] [LZO2] [EPOLL] [PKCS11] [eurephia] built on Sep 5 2012 Dec 6 21:56:01 GlobalTIC nm-openvpn[7472]:[COLOR="Red"][U][B] WARNING: No server certificate verification method has been enabled.[/B][/U][/COLOR] See http://openvpn.net/howto.html#mitm for more info. Dec 6 21:56:01 GlobalTIC nm-openvpn[7472]: NOTE: the current --script-security setting may allow this configuration to call user-defined scripts Dec 6 21:56:01 GlobalTIC nm-openvpn[7472]:[COLOR="Red"] WARNING: file '/home/login/client/client.key' is group or others accessible[/COLOR] Dec 6 21:56:01 GlobalTIC nm-openvpn[7472]: UDPv4 link local: [undef] Dec 6 21:56:01 GlobalTIC nm-openvpn[7472]: UDPv4 link remote: [COLOR="Red"]<my server wan IP>[/COLOR]:1194 Dec 6 21:56:01 GlobalTIC nm-openvpn[7472]: [COLOR="Red"]read UDPv4 [ECONNREFUSED]: Connection refused (code=111)[/COLOR] Dec 6 21:56:03 GlobalTIC nm-openvpn[7472]: [COLOR="Red"]read UDPv4[/COLOR] [ECONNREFUSED]: Connection refused (code=111) Dec 6 21:56:07 GlobalTIC nm-openvpn[7472]: read UDPv4 [ECONNREFUSED]: Connection refused (code=111) Dec 6 21:56:15 GlobalTIC nm-openvpn[7472]: read UDPv4 [ECONNREFUSED]: Connection refused (code=111) Dec 6 21:56:31 GlobalTIC nm-openvpn[7472]: read UDPv4 [ECONNREFUSED]: Connection refused (code=111) Dec 6 21:56:41 GlobalTIC NetworkManager[691]: <warn> VPN connection 'Connexion VPN 1' (IP Conf[/CODE] ifconfig on server host(debian): ifconfig eth0 Link encap:Ethernet HWaddr 08:00:27:16:21:ac inet addr:192.168.1.6 Bcast:192.168.1.255 Mask:255.255.255.0 inet6 addr: fe80::a00:27ff:fe16:21ac/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:9059 errors:0 dropped:0 overruns:0 frame:0 TX packets:5660 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:919427 (897.8 KiB) TX bytes:1273891 (1.2 MiB) tun0 Link encap:UNSPEC HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00 inet addr:192.170.70.1 P-t-P:192.170.70.2 Mask:255.255.255.255 UP POINTOPOINT RUNNING NOARP MULTICAST MTU:1500 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:100 RX bytes:0 (0.0 B) TX bytes:0 (0.0 B) ifconfig on the client host (fedora 17) as0t0: flags=4305<UP,POINTOPOINT,RUNNING,NOARP,MULTICAST> mtu 1500 inet 5.5.0.1 netmask 255.255.252.0 destination 5.5.0.1 unspec 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00 txqueuelen 200 (UNSPEC) RX packets 0 bytes 0 (0.0 B) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 2 bytes 321 (321.0 B) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 as0t1: flags=4305<UP,POINTOPOINT,RUNNING,NOARP,MULTICAST> mtu 1500 inet 5.5.4.1 netmask 255.255.252.0 destination 5.5.4.1 unspec 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00 txqueuelen 200 (UNSPEC) RX packets 0 bytes 0 (0.0 B) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 2 bytes 321 (321.0 B) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 as0t2: flags=4305<UP,POINTOPOINT,RUNNING,NOARP,MULTICAST> mtu 1500 inet 5.5.8.1 netmask 255.255.252.0 destination 5.5.8.1 unspec 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00 txqueuelen 200 (UNSPEC) RX packets 0 bytes 0 (0.0 B) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 2 bytes 321 (321.0 B) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 as0t3: flags=4305<UP,POINTOPOINT,RUNNING,NOARP,MULTICAST> mtu 1500 inet 5.5.12.1 netmask 255.255.252.0 destination 5.5.12.1 unspec 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00 txqueuelen 200 (UNSPEC) RX packets 0 bytes 0 (0.0 B) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 2 bytes 321 (321.0 B) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 **p255p1**: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 inet 192.168.1.2 netmask 255.255.255.0 broadcast 192.168.1.255 inet6 fe80::21d:baff:fe20:b7e6 prefixlen 64 scopeid 0x20<link> ether 00:1d:ba:20:b7:e6 txqueuelen 1000 (Ethernet) RX packets 4842070 bytes 3579798184 (3.3 GiB) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 3996158 bytes 2436442882 (2.2 GiB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 device interrupt 16 p255p1 is label for eth0 interface and on the server : root@hoteserver:/etc/openvpn# tree . +-- client ¦** +-- ca.crt ¦** +-- client.conf ¦** +-- client.crt ¦** +-- client.csr ¦** +-- client.key ¦** +-- client.ovpn ¦* ¦** +-- easy-rsa ¦** +-- build-ca ¦** +-- build-dh ¦** +-- build-inter ¦** +-- build-key ¦** +-- build-key-pass ¦** +-- build-key-pkcs12 ¦** +-- build-key-server ¦** +-- build-req ¦** +-- build-req-pass ¦** +-- clean-all ¦** +-- inherit-inter ¦** +-- keys ¦** ¦** +-- 01.pem ¦** ¦** +-- 02.pem ¦** ¦** +-- ca.crt ¦** ¦** +-- ca.key ¦** ¦** +-- client.crt ¦** ¦** +-- client.csr ¦** ¦** +-- client.key ¦** ¦** +-- dh1024.pem ¦** ¦** +-- index.txt ¦** ¦** +-- index.txt.attr ¦** ¦** +-- index.txt.attr.old ¦** ¦** +-- index.txt.old ¦** ¦** +-- serial ¦** ¦** +-- serial.old ¦** ¦** +-- server.crt ¦** ¦** +-- server.csr ¦** ¦** +-- server.key ¦** +-- list-crl ¦** +-- Makefile ¦** +-- openssl-0.9.6.cnf.gz ¦** +-- openssl.cnf ¦** +-- pkitool ¦** +-- README.gz ¦** +-- revoke-full ¦** +-- sign-req ¦** +-- vars ¦** +-- whichopensslcnf +-- openvpn.log +-- openvpn-status.log +-- server.conf +-- update-resolv-conf on the client: [login@hoteclient openvpn]$ tree . |-- easy-rsa | |-- 1.0 | | |-- build-ca | | |-- build-dh | | |-- build-inter | | |-- build-key | | |-- build-key-pass | | |-- build-key-pkcs12 | | |-- build-key-server | | |-- build-req | | |-- build-req-pass | | |-- clean-all | | |-- list-crl | | |-- make-crl | | |-- openssl.cnf | | |-- README | | |-- revoke-crt | | |-- revoke-full | | |-- sign-req | | `-- vars | `-- 2.0 | |-- build-ca | |-- build-dh | |-- build-inter | |-- build-key | |-- build-key-pass | |-- build-key-pkcs12 | |-- build-key-server | |-- build-req | |-- build-req-pass | |-- clean-all | |-- inherit-inter | |-- keys [error opening dir] | |-- list-crl | |-- Makefile | |-- openssl-0.9.6.cnf | |-- openssl-0.9.8.cnf | |-- openssl-1.0.0.cnf | |-- pkitool | |-- README | |-- revoke-full | |-- sign-req | |-- vars | `-- whichopensslcnf |-- keys -> ./easy-rsa/2.0/keys/ `-- server.conf the problem source is cipher AES-128-CBC ,proto tcp-client or UDP or the interface p255p1 on fedora17 or file authentification ta.key is not found ????

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• The Complete List of iPad Tips, Tricks, and Tutorials

  - by Ross

  The Apple iPad is the latest new toy, and we’ve put together a comprehensive list of every tip, trick, and tutorial that we could find to help you get the most out of it—and we’re even giving one away to one lucky reader. So read on! Note: We’ll be keeping this page updated as we find more great articles, so you should bookmark this page for future reference. Want Your Own iPad? How-To Geek is Giving One Away! All you have to do to enter is become a fan of our Facebook page, and we’ll pick a random fan to win the prize. Win an iPad on the How-To Geek Facebook Fan Page Disable the “clicking sound” on the iPad Keyboard Does the clicking sound when you tap the iPad keyboard bother you? Thankfully it’s easy to disable with a couple of taps. How to disable the “clicking sound” on your iPad’s keyboard Enable and add bookmarks to the Safari Bookmarks Bar on your iPad By default, Safari doesn’t display the Bookmarks Bar. This tip shows you how to change that. How to enable and add bookmarks to the Safari Bookmarks Bar on your iPad Clear the Cache, History and Cookies in Safari for the iPad You’re probably used to clearing this kind of data right from within the browser. Not so with Safari on the iPad – but here’s how you can. How to clear the cache, history and cookies in Safari for iPad How to add more Apps to your iPad Dock The iPad has four icons in its ‘dock’. Did you know it can hold 6? How to add more Apps to your iPad Dock Convert PDF files to ePub files to read on your iPad with iBooks ePub is the format that iBooks are in. So for those of you with large eBook collections in PDF, here’s how you convert them to read in iBooks. How to convert PDF files to ePub files to read on your iPad with iBooks How to force your iPad to restart Has an app caused your iPad to freeze up, and you can’t escape? This tip shows you how to force your iPad to restart. How to force your iPad to restart How to export Keynote for iPad presentations to your Mac or PC Exporting Keynote presentations from your iPad to your Mac or PC isn’t as straight forward as you might have expected. This tutorial shows you how. How to export Keynote for iPad presentations to your Mac or PC How to import presentations to Keynote on your iPad Having trouble getting your presentations onto your iPad? How to import presentations to Keynote on your iPad How to import documents to Pages on your iPad This guide shows you how to transfer documents (MS Word or Pages) from your Mac/PC to your iPad. How to import documents to Pages on your iPad How to insert photos in a Pages document using iPad and share it as a PDF Want to spice up that doc with a picture you just took? This tutorial will show you how – and how to export that document as a PDF. How to insert photos in a Pages document using iPad and share it as a PDF How to lock your iPad If you have kids or co-workers/friends who think it’s funny to mess with your iPad – lock it. How to lock your iPad How to remove the “Sent from my iPad” signature from outgoing email on your iPad Does everyone need to know you just sent that email from your iPad? Probably not. This guide shows you how to remove the “Sent from my iPad” signature and replace it with your own (or none). How to remove the “Sent from my iPad” signature from outgoing email on your iPad How To Sync Multiple Calendars to the iPad With Google Sync This tutorial will show you a workaround on how to sync multiple calendars on your iPad using Google Sync. How to Sync Multiple Calendars to the iPad With Google Sync How to determine the MAC address of your iPad If your network restricts connections via MAC address – this guide will show you how to determine what yours is. How to determine the MAC address of your iPad How to take a screenshot of your iPad Do you need to take a screenshot of your iPad? This quick tip shows you how to do just that. How to take a screenshot of your iPad How to delete apps from your iPod Touch, iPhone or iPad Anyone who had an iPod Touch or iPhone before they had an iPad won’t need this tutorial. But if you’re new to the experience, this one will help. How to delete apps from your iPod Touch, iPhone or iPad How to determine the iPad ECID on Windows and Mac iPadintosh shows us how to determine the iPad’s ECID code – something you’ll want to have come Jailbreak time. How to grab the iPad ECID in Windows or OS X iPad Apps: Twitter and social networking essentials Enggadget has you covered with reviews of the first slew of iPad specific Twitter and other social networking apps. iPad Apps: Twitter and social networking essentials What does your website look like on an iPad? iPad Peek is a web based tool that allows you to enter any given URL, and it will display that page the same way Safari on the iPad does. Great for web site owners who don’t have access to an iPad. iPadPeek Stream Music and Videos to your iPad Gizmodo reviews the iPad app StreamToMe, which allows you to stream media from your Mac to your iPad across your local network. Their feelings in a nutshell – worth the $3, but not perfect. Review: StreamToMe for the iPad Apple iPad : Change links in Google Reader to point to full HTML webpage How to change links in Safari for iPad so that Google Reader points to a full HTML webpage How to connect an iPad to your existing wireless keyboard This video will show you how to connect your iPad to a wireless keyboard if you’re having any problems – and from the sound of things, quite a few folks are. via TUAW How to get started with the iPad Mashable has a very entry-level guide that will help you set up your iPad for the first time. Mashable’s Guide to Setting up the iPad Essential iPad Apps Downloadsquad gives mini-reviews to 8 iPad apps that you should install as soon as you get your iPad. iPad App Buyers Guide: Essential Apps you should get on day one Videos: The Official iPad Guided Tours From none other than Apple! Great getting started videos for all the included iPad apps. The Official iPad Guided Tours The Official iPad Manual When you buy an iPad, you don’t get a manual. But that’s not to say there isn’t one. Apple provides a 150 guide for your iPad in PDF format. The Official iPad Manual (pdf) How to print from your iPad Sure, it’s actually just an App (PrintCentral – $9.99 USD), but as of right now, it’s the only way. PrintCentral How to make your own iPad Wallpaper A perfectly detailed tutorial on how to make your own wallpaper for your iPad. The author also provides a really nice sample wallpaper, published under the Attribution-Noncommercial 2.0 Generic license. How to make your own iPad Wallpaper Got any more tips? Share them in the comments, and we’ll update the post with the links, or just the tip itself. Similar Articles Productive Geek Tips Want an iPad? How-To Geek is Giving One Away!Why Wait? Amazing New Add-on Turns Your iPhone into an iPad! [Comic]Clear the Auto-Complete Email Address Cache in OutlookAsk the Readers: Share Your Tips for Defeating Viruses and MalwareStupid Geek Tricks: Tile or Cascade Multiple Windows in Windows 7 TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips DVDFab 6 Revo Uninstaller Pro Registry Mechanic 9 for Windows PC Tools Internet Security Suite 2010 Are You Blocked On Gtalk? Find out Discover Latest Android Apps On AppBrain The Ultimate Guide For YouTube Lovers Will it Blend? iPad Edition Penolo Lets You Share Sketches On Twitter Visit Woolyss.com for Old School Games, Music and Videos

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• Developer’s Life – Attitude and Communication – They Can Cause Problems – Notes from the Field #027

  - by Pinal Dave

  [Note from Pinal]: This is a 27th episode of Notes from the Field series. The biggest challenge for anyone is to understand human nature. We human have so many things on our mind at any moment of time. There are cases when what we say is not what we mean and there are cases where what we mean we do not say. We do say and things as per our mood and our agenda in mind. Sometimes there are incidents when our attitude creates confusion in the communication and we end up creating a situation which is absolutely not warranted. In this episode of the Notes from the Field series database expert Mike Walsh explains a very crucial issue we face in our career, which is not technical but more to relate to human nature. Read on this may be the best blog post you might read in recent times. In this week’s note from the field, I’m taking a slight departure from technical knowledge and concepts explained. We’ll be back to it next week, I’m sure. Pinal wanted us to explain some of the issues we bump into and how we see some of our customers arrive at problem situations and how we have helped get them back on the right track. Often it is a technical problem we are officially solving – but in a lot of cases as a consultant, we are really helping fix some communication difficulties. This is a technical blog post and not an “advice column” in a newspaper – but the longer I am a consultant, the more years I add to my experience in technology the more I learn that the vast majority of the problems we encounter have “soft skills” included in the chain of causes for the issue we are helping overcome. This is not going to be exhaustive but I hope that sharing four pieces of advice inspired by real issues starts a process of searching for places where we can be the cause of these challenges and look at fixing them in ourselves. Or perhaps we can begin looking at resolving them in teams that we manage. I’ll share three statements that I’ve either heard, read or said and talk about some of the communication or attitude challenges highlighted by the statement. 1 – “But that’s the SAN Administrator’s responsibility…” I heard that early on in my consulting career when talking with a customer who had serious corruption and no good recent backups – potentially no good backups at all. The statement doesn’t have to be this one exactly, but the attitude here is an attitude of “my job stops here, and I don’t care about the intent or principle of why I’m here.” It’s also a situation of having the attitude that as long as there is someone else to blame, I’m fine…  You see in this case, the DBA had a suspicion that the backups were not being handled right.  They were the DBA and they knew that they had responsibility to ensure SQL backups were good to go – it’s a basic requirement of a production DBA. In my “As A DBA Where Do I start?!” presentation, I argue that is job #1 of a DBA. But in this case, the thought was that there was someone else to blame. Rather than create extra work and take on responsibility it was decided to just let it be another team’s responsibility. This failed the company, the company’s customers and no one won. As technologists – we should strive to go the extra mile. If there is a lack of clarity around roles and responsibilities and we know it – we should push to get it resolved. Especially as the DBAs who should act as the advocates of the data contained in the databases we are responsible for. 2 – “We’ve always done it this way, it’s never caused a problem before!” Complacency. I have to say that many failures I’ve been paid good money to help recover from would have not happened had it been for an attitude of complacency. If any thoughts like this have entered your mind about your situation you may be suffering from it. If, while reading this, you get this sinking feeling in your stomach about that one thing you know should be fixed but haven’t done it.. Why don’t you stop and go fix it then come back.. “We should have better backups, but we’re on a SAN so we should be fine really.” “Technically speaking that could happen, but what are the chances?” “We’ll just clean that up as a fast follow” ..and so on. In the age of tightening IT budgets, increased expectations of up time, availability and performance there is no room for complacency. Our customers and business units expect – no demand – the best. Complacency says “we will give you second best or hopefully good enough and we accept the risk and know this may hurt us later. Sometimes an organization will opt for “good enough” and I agree with the concept that at times the perfect can be the enemy of the good. But when we make those decisions in a vacuum and are not reporting them up and discussing them as an organization that is different. That is us unilaterally choosing to do something less than the best and purposefully playing a game of chance. 3 – “This device must accept interference from other devices but not create any” I’ve paraphrased this one – but it’s something the Federal Communications Commission – a federal agency in the United States that regulates electronic communication – requires of all manufacturers of any device that could cause or receive interference electronically. I blogged in depth about this here (http://www.straightpathsql.com/archives/2011/07/relationship-advice-from-the-fcc/) so I won’t go into much detail other than to say this… If we all operated more on the premise that we should do our best to not be the cause of conflict, and to be less easily offended and less upset when we perceive offense life would be easier in many areas! This doesn’t always cause the issues we are called in to help out. Not directly. But where we see it is in unhealthy relationships between the various technology teams at a client. We’ll see teams hoarding knowledge, not sharing well with others and almost working against other teams instead of working with them. If you trace these problems back far enough it often stems from someone or some group of people violating this principle from the FCC. To Sum It Up Technology problems are easy to solve. At Linchpin People we help many customers get past the toughest technological challenge – and at the end of the day it is really just a repeatable process of pattern based troubleshooting, logical thinking and starting at the beginning and carefully stepping through to the end. It’s easy at the end of the day. The tough part of what we do as consultants is the people skills. Being able to help get teams working together, being able to help teams take responsibility, to improve team to team communication? That is the difficult part, and we get to use the soft skills on every engagement. Work on professional development (http://professionaldevelopment.sqlpass.org/) and see continuing improvement here, not just with technology. I can teach just about anyone how to be an excellent DBA and performance tuner, but some of these soft skills are much more difficult to teach. If you want to get started with performance analytics and triage of virtualized SQL Servers with the help of experts, read more over at Fix Your SQL Server. Reference: Pinal Dave (http://blog.sqlauthority.com)Filed under: Notes from the Field, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL

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• How to change Matlab program for solving equation with finite element method?

  - by DSblizzard

  I don't know is this question more related to mathematics or programming and I'm absolute newbie in Matlab. Program FEM_50 applies the finite element method to Laplace's equation -Uxx(x, y) - Uyy(x, y) = F(x, y) in Omega. How to change it to apply FEM to equation -Uxx(x, y) - Uyy(x, y) + U(x, y) = F(x, y)? At this page: http://sc.fsu.edu/~burkardt/m_src/fem_50/fem_50.html additional code files in case you need them. function fem_50 ( ) %% FEM_50 applies the finite element method to Laplace's equation. % % Discussion: % % FEM_50 is a set of MATLAB routines to apply the finite % element method to solving Laplace's equation in an arbitrary % region, using about 50 lines of MATLAB code. % % FEM_50 is partly a demonstration, to show how little it % takes to implement the finite element method (at least using % every possible MATLAB shortcut.) The user supplies datafiles % that specify the geometry of the region and its arrangement % into triangular and quadrilateral elements, and the location % and type of the boundary conditions, which can be any mixture % of Neumann and Dirichlet. % % The unknown state variable U(x,y) is assumed to satisfy % Laplace's equation: % -Uxx(x,y) - Uyy(x,y) = F(x,y) in Omega % with Dirichlet boundary conditions % U(x,y) = U_D(x,y) on Gamma_D % and Neumann boundary conditions on the outward normal derivative: % Un(x,y) = G(x,y) on Gamma_N % If Gamma designates the boundary of the region Omega, % then we presume that % Gamma = Gamma_D + Gamma_N % but the user is free to determine which boundary conditions to % apply. Note, however, that the problem will generally be singular % unless at least one Dirichlet boundary condition is specified. % % The code uses piecewise linear basis functions for triangular elements, % and piecewise isoparametric bilinear basis functions for quadrilateral % elements. % % The user is required to supply a number of data files and MATLAB % functions that specify the location of nodes, the grouping of nodes % into elements, the location and value of boundary conditions, and % the right hand side function in Laplace's equation. Note that the % fact that the geometry is completely up to the user means that % just about any two dimensional region can be handled, with arbitrary % shape, including holes and islands. % clear % % Read the nodal coordinate data file. % load coordinates.dat; % % Read the triangular element data file. % load elements3.dat; % % Read the quadrilateral element data file. % load elements4.dat; % % Read the Neumann boundary condition data file. % I THINK the purpose of the EVAL command is to create an empty NEUMANN array % if no Neumann file is found. % eval ( 'load neumann.dat;', 'neumann=[];' ); % % Read the Dirichlet boundary condition data file. % load dirichlet.dat; A = sparse ( size(coordinates,1), size(coordinates,1) ); b = sparse ( size(coordinates,1), 1 ); % % Assembly. % for j = 1 : size(elements3,1) A(elements3(j,:),elements3(j,:)) = A(elements3(j,:),elements3(j,:)) ... + stima3(coordinates(elements3(j,:),:)); end for j = 1 : size(elements4,1) A(elements4(j,:),elements4(j,:)) = A(elements4(j,:),elements4(j,:)) ... + stima4(coordinates(elements4(j,:),:)); end % % Volume Forces. % for j = 1 : size(elements3,1) b(elements3(j,:)) = b(elements3(j,:)) ... + det( [1,1,1; coordinates(elements3(j,:),:)'] ) * ... f(sum(coordinates(elements3(j,:),:))/3)/6; end for j = 1 : size(elements4,1) b(elements4(j,:)) = b(elements4(j,:)) ... + det([1,1,1; coordinates(elements4(j,1:3),:)'] ) * ... f(sum(coordinates(elements4(j,:),:))/4)/4; end % % Neumann conditions. % if ( ~isempty(neumann) ) for j = 1 : size(neumann,1) b(neumann(j,:)) = b(neumann(j,:)) + ... norm(coordinates(neumann(j,1),:) - coordinates(neumann(j,2),:)) * ... g(sum(coordinates(neumann(j,:),:))/2)/2; end end % % Determine which nodes are associated with Dirichlet conditions. % Assign the corresponding entries of U, and adjust the right hand side. % u = sparse ( size(coordinates,1), 1 ); BoundNodes = unique ( dirichlet ); u(BoundNodes) = u_d ( coordinates(BoundNodes,:) ); b = b - A * u; % % Compute the solution by solving A * U = B for the remaining unknown values of U. % FreeNodes = setdiff ( 1:size(coordinates,1), BoundNodes ); u(FreeNodes) = A(FreeNodes,FreeNodes) \ b(FreeNodes); % % Graphic representation. % show ( elements3, elements4, coordinates, full ( u ) ); return end

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• SQL SERVER – Faster SQL Server Databases and Applications – Power and Control with SafePeak Caching Options

  - by Pinal Dave

  Update: This blog post is written based on the SafePeak, which is available for free download. Today, I’d like to examine more closely one of my preferred technologies for accelerating SQL Server databases, SafePeak. Safepeak’s software provides a variety of advanced data caching options, techniques and tools to accelerate the performance and scalability of SQL Server databases and applications. I’d like to look more closely at some of these options, as some of these capabilities could help you address lagging database and performance on your systems. To better understand the available options, it is best to start by understanding the difference between the usual “Basic Caching” vs. SafePeak’s “Dynamic Caching”. Basic Caching Basic Caching (or the stale and static cache) is an ability to put the results from a query into cache for a certain period of time. It is based on TTL, or Time-to-live, and is designed to stay in cache no matter what happens to the data. For example, although the actual data can be modified due to DML commands (update/insert/delete), the cache will still hold the same obsolete query data. Meaning that with the Basic Caching is really static / stale cache.  As you can tell, this approach has its limitations. Dynamic Caching Dynamic Caching (or the non-stale cache) is an ability to put the results from a query into cache while maintaining the cache transaction awareness looking for possible data modifications. The modifications can come as a result of: DML commands (update/insert/delete), indirect modifications due to triggers on other tables, executions of stored procedures with internal DML commands complex cases of stored procedures with multiple levels of internal stored procedures logic. When data modification commands arrive, the caching system identifies the related cache items and evicts them from cache immediately. In the dynamic caching option the TTL setting still exists, although its importance is reduced, since the main factor for cache invalidation (or cache eviction) become the actual data updates commands. Now that we have a basic understanding of the differences between “basic” and “dynamic” caching, let’s dive in deeper. SafePeak: A comprehensive and versatile caching platform SafePeak comes with a wide range of caching options. Some of SafePeak’s caching options are automated, while others require manual configuration. Together they provide a complete solution for IT and Data managers to reach excellent performance acceleration and application scalability for  a wide range of business cases and applications. Automated caching of SQL Queries: Fully/semi-automated caching of all “read” SQL queries, containing any types of data, including Blobs, XMLs, Texts as well as all other standard data types. SafePeak automatically analyzes the incoming queries, categorizes them into SQL Patterns, identifying directly and indirectly accessed tables, views, functions and stored procedures; Automated caching of Stored Procedures: Fully or semi-automated caching of all read” stored procedures, including procedures with complex sub-procedure logic as well as procedures with complex dynamic SQL code. All procedures are analyzed in advance by SafePeak’s  Metadata-Learning process, their SQL schemas are parsed – resulting with a full understanding of the underlying code, objects dependencies (tables, views, functions, sub-procedures) enabling automated or semi-automated (manually review and activate by a mouse-click) cache activation, with full understanding of the transaction logic for cache real-time invalidation; Transaction aware cache: Automated cache awareness for SQL transactions (SQL and in-procs); Dynamic SQL Caching: Procedures with dynamic SQL are pre-parsed, enabling easy cache configuration, eliminating SQL Server load for parsing time and delivering high response time value even in most complicated use-cases; Fully Automated Caching: SQL Patterns (including SQL queries and stored procedures) that are categorized by SafePeak as “read and deterministic” are automatically activated for caching; Semi-Automated Caching: SQL Patterns categorized as “Read and Non deterministic” are patterns of SQL queries and stored procedures that contain reference to non-deterministic functions, like getdate(). Such SQL Patterns are reviewed by the SafePeak administrator and in usually most of them are activated manually for caching (point and click activation); Fully Dynamic Caching: Automated detection of all dependent tables in each SQL Pattern, with automated real-time eviction of the relevant cache items in the event of “write” commands (a DML or a stored procedure) to one of relevant tables. A default setting; Semi Dynamic Caching: A manual cache configuration option enabling reducing the sensitivity of specific SQL Patterns to “write” commands to certain tables/views. An optimization technique relevant for cases when the query data is either known to be static (like archive order details), or when the application sensitivity to fresh data is not critical and can be stale for short period of time (gaining better performance and reduced load); Scheduled Cache Eviction: A manual cache configuration option enabling scheduling SQL Pattern cache eviction based on certain time(s) during a day. A very useful optimization technique when (for example) certain SQL Patterns can be cached but are time sensitive. Example: “select customers that today is their birthday”, an SQL with getdate() function, which can and should be cached, but the data stays relevant only until 00:00 (midnight); Parsing Exceptions Management: Stored procedures that were not fully parsed by SafePeak (due to too complex dynamic SQL or unfamiliar syntax), are signed as “Dynamic Objects” with highest transaction safety settings (such as: Full global cache eviction, DDL Check = lock cache and check for schema changes, and more). The SafePeak solution points the user to the Dynamic Objects that are important for cache effectiveness, provides easy configuration interface, allowing you to improve cache hits and reduce cache global evictions. Usually this is the first configuration in a deployment; Overriding Settings of Stored Procedures: Override the settings of stored procedures (or other object types) for cache optimization. For example, in case a stored procedure SP1 has an “insert” into table T1, it will not be allowed to be cached. However, it is possible that T1 is just a “logging or instrumentation” table left by developers. By overriding the settings a user can allow caching of the problematic stored procedure; Advanced Cache Warm-Up: Creating an XML-based list of queries and stored procedure (with lists of parameters) for periodically automated pre-fetching and caching. An advanced tool allowing you to handle more rare but very performance sensitive queries pre-fetch them into cache allowing high performance for users’ data access; Configuration Driven by Deep SQL Analytics: All SQL queries are continuously logged and analyzed, providing users with deep SQL Analytics and Performance Monitoring. Reduce troubleshooting from days to minutes with database objects and SQL Patterns heat-map. The performance driven configuration helps you to focus on the most important settings that bring you the highest performance gains. Use of SafePeak SQL Analytics allows continuous performance monitoring and analysis, easy identification of bottlenecks of both real-time and historical data; Cloud Ready: Available for instant deployment on Amazon Web Services (AWS). As you can see, there are many options to configure SafePeak’s SQL Server database and application acceleration caching technology to best fit a lot of situations. If you’re not familiar with their technology, they offer free-trial software you can download that comes with a free “help session” to help get you started. You can access the free trial here. Also, SafePeak is available to use on Amazon Cloud. Reference: Pinal Dave (http://blog.sqlauthority.com)Filed under: PostADay, SQL, SQL Authority, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, T SQL

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• SQL SERVER – Core Concepts – Elasticity, Scalability and ACID Properties – Exploring NuoDB an Elastically Scalable Database System

  - by pinaldave

  I have been recently exploring Elasticity and Scalability attributes of databases. You can see that in my earlier blog posts about NuoDB where I wanted to look at Elasticity and Scalability concepts. The concepts are very interesting, and intriguing as well. I have discussed these concepts with my friend Joyti M and together we have come up with this interesting read. The goal of this article is to answer following simple questions What is Elasticity? What is Scalability? How ACID properties vary from NOSQL Concepts? What are the prevailing problems in the current database system architectures? Why is NuoDB  an innovative and welcome change in database paradigm? Elasticity This word’s original form is used in many different ways and honestly it does do a decent job in holding things together over the years as a person grows and contracts. Within the tech world, and specifically related to software systems (database, application servers), it has come to mean a few things - allow stretching of resources without reaching the breaking point (on demand). What are resources in this context? Resources are the usual suspects – RAM/CPU/IO/Bandwidth in the form of a container (a process or bunch of processes combined as modules). When it is about increasing resources the simplest idea which comes to mind is the addition of another container. Another container means adding a brand new physical node. When it is about adding a new node there are two questions which comes to mind. 1) Can we add another node to our software system? 2) If yes, does adding new node cause downtime for the system? Let us assume we have added new node, let us see what the new needs of the system are when a new node is added. Balancing incoming requests to multiple nodes Synchronization of a shared state across multiple nodes Identification of “downstate” and resolution action to bring it to “upstate” Well, adding a new node has its advantages as well. Here are few of the positive points Throughput can increase nearly horizontally across the node throughout the system Response times of application will increase as in-between layer interactions will be improved Now, Let us put the above concepts in the perspective of a Database. When we mention the term “running out of resources” or “application is bound to resources” the resources can be CPU, Memory or Bandwidth. The regular approach to “gain scalability” in the database is to look around for bottlenecks and increase the bottlenecked resource. When we have memory as a bottleneck we look at the data buffers, locks, query plans or indexes. After a point even this is not enough as there needs to be an efficient way of managing such large workload on a “single machine” across memory and CPU bound (right kind of scheduling)  workload. We next move on to either read/write separation of the workload or functionality-based sharing so that we still have control of the individual. But this requires lots of planning and change in client systems in terms of knowing where to go/update/read and for reporting applications to “aggregate the data” in an intelligent way. What we ideally need is an intelligent layer which allows us to do these things without us getting into managing, monitoring and distributing the workload. Scalability In the context of database/applications, scalability means three main things Ability to handle normal loads without pressure E.g. X users at the Y utilization of resources (CPU, Memory, Bandwidth) on the Z kind of hardware (4 processor, 32 GB machine with 15000 RPM SATA drives and 1 GHz Network switch) with T throughput Ability to scale up to expected peak load which is greater than normal load with acceptable response times Ability to provide acceptable response times across the system E.g. Response time in S milliseconds (or agreed upon unit of measure) – 90% of the time The Issue – Need of Scale In normal cases one can plan for the load testing to test out normal, peak, and stress scenarios to ensure specific hardware meets the needs. With help from Hardware and Software partners and best practices, bottlenecks can be identified and requisite resources added to the system. Unfortunately this vertical scale is expensive and difficult to achieve and most of the operational people need the ability to scale horizontally. This helps in getting better throughput as there are physical limits in terms of adding resources (Memory, CPU, Bandwidth and Storage) indefinitely. Today we have different options to achieve scalability: Read & Write Separation The idea here is to do actual writes to one store and configure slaves receiving the latest data with acceptable delays. Slaves can be used for balancing out reads. We can also explore functional separation or sharing as well. We can separate data operations by a specific identifier (e.g. region, year, month) and consolidate it for reporting purposes. For functional separation the major disadvantage is when schema changes or workload pattern changes. As the requirement grows one still needs to deal with scale need in manual ways by providing an abstraction in the middle tier code. Using NOSQL solutions The idea is to flatten out the structures in general to keep all values which are retrieved together at the same store and provide flexible schema. The issue with the stores is that they are compromising on mostly consistency (no ACID guarantees) and one has to use NON-SQL dialect to work with the store. The other major issue is about education with NOSQL solutions. Would one really want to make these compromises on the ability to connect and retrieve in simple SQL manner and learn other skill sets? Or for that matter give up on ACID guarantee and start dealing with consistency issues? Hybrid Deployment – Mac, Linux, Cloud, and Windows One of the challenges today that we see across On-premise vs Cloud infrastructure is a difference in abilities. Take for example SQL Azure – it is wonderful in its concepts of throttling (as it is shared deployment) of resources and ability to scale using federation. However, the same abilities are not available on premise. This is not a mistake, mind you – but a compromise of the sweet spot of workloads, customer requirements and operational SLAs which can be supported by the team. In today’s world it is imperative that databases are available across operating systems – which are a commodity and used by developers of all hues. An Ideal Database Ability List A system which allows a linear scale of the system (increase in throughput with reasonable response time) with the addition of resources A system which does not compromise on the ACID guarantees and require developers to learn new paradigms A system which does not force fit a new way interacting with database by learning Non-SQL dialect A system which does not force fit its mechanisms for providing availability across its various modules. Well NuoDB is the first database which has all of the above abilities and much more. In future articles I will cover my hands-on experience with it. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology Tagged: NuoDB

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• How to get full control of umask/PAM/permissions?

  - by plua

  OUR SITUATION Several people from our company log in to a server and upload files. They all need to be able to upload and overwrite the same files. They have different usernames, but are all part of the same group. However, this is an internet server, so the "other" users should have (in general) just read-only access. So what I want to have is these standard permissions: files: 664 directories: 771 My goal is that all users do not need to worry about permissions. The server should be configured in such a way that these permissions apply to all files and directories, newly created, copied, or over-written. Only when we need some special permissions we'd manually change this. We upload files to the server by SFTP-ing in Nautilus, by mounting the server using sshfs and accessing it in Nautilus as if it were a local folder, and by SCP-ing in the command line. That basically covers our situation and what we aim to do. Now, I have read many things about the beautiful umask functionality. From what I understand umask (together with PAM) should allow me to do exactly what I want: set standard permissions for new files and directories. However, after many many hours of reading and trial-and-error, I still do not get this to work. I get many unexpected results. I really like to get a solid grasp of umask and have many question unanswered. I will post these questions below, together with my findings and an explanation of my trials that led to these questions. Given that many things appear to go wrong, I think that I am doing several things wrong. So therefore, there are many questions. NOTE: I am using Ubuntu 9.10 and therefore can not change the sshd_config to set the umask for the SFTP server. Installed SSH OpenSSH_5.1p1 Debian-6ubuntu2 < required OpenSSH 5.4p1. So here go the questions. 1. DO I NEED TO RESTART FOR PAM CHANGS TO TAKE EFFECT? Let's start with this. There were so many files involved and I was unable to figure out what does and what does not affect things, also because I did not know whether or not I have to restart the whole system for PAM changes to take effect. I did do so after not seeing the expected results, but is this really necessary? Or can I just log out from the server and log back in, and should new PAM policies be effective? Or is there some 'PAM' program to reload? 2. IS THERE ONE SINGLE FILE TO CHANGE THAT AFFECTS ALL USERS FOR ALL SESSIONS? So I ended up changing MANY files, as I read MANY different things. I ended up setting the umask in the following files: ~/.profile -> umask=0002 ~/.bashrc -> umask=0002 /etc/profile -> umask=0002 /etc/pam.d/common-session -> umask=0002 /etc/pam.d/sshd -> umask=0002 /etc/pam.d/login -> umask=0002 I want this change to apply to all users, so some sort of system-wide change would be best. Can it be achieved? 3. AFTER ALL, THIS UMASK THING, DOES IT WORK? So after changing umask to 0002 at every possible place, I run tests. ------------SCP----------- TEST 1: scp testfile (which has 777 permissions for testing purposes) server:/home/ testfile 100% 4 0.0KB/s 00:00 Let's check permissions: user@server:/home$ ls -l total 4 -rwx--x--x 1 user uploaders 4 2011-02-05 17:59 testfile (711) ---------SSH------------ TEST 2: ssh server user@server:/home$ touch anotherfile user@server:/home$ ls -l total 4 -rw-rw-r-- 1 user uploaders 0 2011-02-05 18:03 anotherfile (664) --------SFTP----------- Nautilus: sftp://server/home/ Copy and paste newfile from client to server (777 on client) TEST 3: user@server:/home$ ls -l total 4 -rwxrwxrwx 1 user uploaders 3 2011-02-05 18:05 newfile (777) Create a new file through Nautilus. Check file permissions in terminal: TEST 4: user@server:/home$ ls -l total 4 -rw------- 1 user uploaders 0 2011-02-05 18:06 newfile (600) I mean... WHAT just happened here?! We should get 644 every single time. Instead I get 711, 777, 600, and then once 644. And the 644 is only achieved when creating a new, blank file through SSH, which is the least probable scenario. So I am asking, does umask/pam work after all? 4. SO WHAT DOES IT MEAN TO UMASK SSHFS? Sometimes we mount a server locally, using sshfs. Very useful. But again, we have permissions issues. Here is how we mount: sshfs -o idmap=user -o umask=0113 user@server:/home/ /mnt NOTE: we use umask = 113 because apparently, sshfs starts from 777 instead of 666, so with 113 we get 664 which is the desired file permission. But what now happens is that we see all files and directories as if they are 664. We browse in Nautilus to /mnt and: Right click - New File (newfile) --- TEST 5 Right click - New Folder (newfolder) --- TEST 6 Copy and paste a 777 file from our local client --- TEST 7 So let's check on the command line: user@client:/mnt$ ls -l total 8 -rw-rw-r-- 1 user 1007 3 Feb 5 18:05 copyfile (664) -rw-rw-r-- 1 user 1007 0 Feb 5 18:15 newfile (664) drw-rw-r-- 1 user 1007 4096 Feb 5 18:15 newfolder (664) But hey, let's check this same folder on the server-side: user@server:/home$ ls -l total 8 -rwxrwxrwx 1 user uploaders 3 2011-02-05 18:05 copyfile (777) -rw------- 1 user uploaders 0 2011-02-05 18:15 newfile (600) drwx--x--x 2 user uploaders 4096 2011-02-05 18:15 newfolder (711) What?! The REAL file permissions are very different from what we see in Nautilus. So does this umask on sshfs just create a 'filter' that shows unreal file permissions? And I tried to open a file from another user but the same group that had real 600 permissions but 644 'fake' permissions, and I could still not read this, so what good is this filter?? 5. UMASK IS ALL ABOUT FILES. BUT WHAT ABOUT DIRECTORIES? From my tests I can see that the umask that is being applied also somehow influences the directory permissions. However, I want my files to be 664 (002) and my directories to be 771 (006). So is it possible to have a different umask for directories? 6. PERHAPS UMASK/PAM IS REALLY COOL, BUT UBUNTU IS JUST BUGGY? On the one hand, I have read topics of people that have had success with PAM/UMASK and Ubuntu. On the other hand, I have found many older and newer bugs regarding umask/PAM/fuse on Ubuntu: https://bugs.launchpad.net/ubuntu/+source/gdm/+bug/241198 https://bugs.launchpad.net/ubuntu/+source/fuse/+bug/239792 https://bugs.launchpad.net/ubuntu/+source/pam/+bug/253096 https://bugs.launchpad.net/ubuntu/+source/sudo/+bug/549172 http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=314796 So I do not know what to believe anymore. Should I just give up? Would ACL solve all my problems? Or do I have again problems using Ubuntu? One word of caution with backups using tar. Red Hat /Centos distributions support acls in the tar program but Ubuntu does not support acls when backing up. This means that all acls will be lost when you create a backup. I am very willing to upgrade to Ubuntu 10.04 if that would solve my problems too, but first I want to understand what is happening.

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• Cost Comparison Hard Disk Drive to Solid State Drive on Price per Gigabyte - dispelling a myth!

  - by tonyrogerson

  It is often said that Hard Disk Drive storage is significantly cheaper per GiByte than Solid State Devices – this is wholly inaccurate within the database space. People need to look at the cost of the complete solution and not just a single component part in isolation to what is really required to meet the business requirement. Buying a single Hitachi Ultrastar 600GB 3.5” SAS 15Krpm hard disk drive will cost approximately £239.60 (http://scan.co.uk, 22nd March 2012) compared to an OCZ 600GB Z-Drive R4 CM84 PCIe costing £2,316.54 (http://scan.co.uk, 22nd March 2012); I’ve not included FusionIO ioDrive because there is no public pricing available for it – something I never understand and personally when companies do this I immediately think what are they hiding, luckily in FusionIO’s case the product is proven though is expensive compared to OCZ enterprise offerings. On the face of it the single 15Krpm hard disk has a price per GB of £0.39, the SSD £3.86; this is what you will see in the press and this is what sales people will use in comparing the two technologies – do not be fooled by this bullshit people! What is the requirement? The requirement is the database will have a static size of 400GB kept static through archiving so growth and trim will balance the database size, the client requires resilience, there will be several hundred call centre staff querying the database where queries will read a small amount of data but there will be no hot spot in the data so the randomness will come across the entire 400GB of the database, estimates predict that the IOps required will be approximately 4,000IOps at peak times, because it’s a call centre system the IO latency is important and must remain below 5ms per IO. The balance between read and write is 70% read, 30% write. The requirement is now defined and we have three of the most important pieces of the puzzle – space required, estimated IOps and maximum latency per IO. Something to consider with regard SQL Server; write activity requires synchronous IO to the storage media specifically the transaction log; that means the write thread will wait until the IO is completed and hardened off until the thread can continue execution, the requirement has stated that 30% of the system activity will be write so we can expect a high amount of synchronous activity. The hardware solution needs to be defined; two possible solutions: hard disk or solid state based; the real question now is how many hard disks are required to achieve the IO throughput, the latency and resilience, ditto for the solid state. Hard Drive solution On a test on an HP DL380, P410i controller using IOMeter against a single 15Krpm 146GB SAS drive, the throughput given on a transfer size of 8KiB against a 40GiB file on a freshly formatted disk where the partition is the only partition on the disk thus the 40GiB file is on the outer edge of the drive so more sectors can be read before head movement is required: For 100% sequential IO at a queue depth of 16 with 8 worker threads 43,537 IOps at an average latency of 2.93ms (340 MiB/s), for 100% random IO at the same queue depth and worker threads 3,733 IOps at an average latency of 34.06ms (34 MiB/s). The same test was done on the same disk but the test file was 130GiB: For 100% sequential IO at a queue depth of 16 with 8 worker threads 43,537 IOps at an average latency of 2.93ms (340 MiB/s), for 100% random IO at the same queue depth and worker threads 528 IOps at an average latency of 217.49ms (4 MiB/s). From the result it is clear random performance gets worse as the disk fills up – I’m currently writing an article on short stroking which will cover this in detail. Given the work load is random in nature looking at the random performance of the single drive when only 40 GiB of the 146 GB is used gives near the IOps required but the latency is way out. Luckily I have tested 6 x 15Krpm 146GB SAS 15Krpm drives in a RAID 0 using the same test methodology, for the same test above on a 130 GiB for each drive added the performance boost is near linear, for each drive added throughput goes up by 5 MiB/sec, IOps by 700 IOps and latency reducing nearly 50% per drive added (172 ms, 94 ms, 65 ms, 47 ms, 37 ms, 30 ms). This is because the same 130GiB is spread out more as you add drives 130 / 1, 130 / 2, 130 / 3 etc. so implicit short stroking is occurring because there is less file on each drive so less head movement required. The best latency is still 30 ms but we have the IOps required now, but that’s on a 130GiB file and not the 400GiB we need. Some reality check here: a) the drive randomness is more likely to be 50/50 and not a full 100% but the above has highlighted the effect randomness has on the drive and the more a drive fills with data the worse the effect. For argument sake let us assume that for the given workload we need 8 disks to do the job, for resilience reasons we will need 16 because we need to RAID 1+0 them in order to get the throughput and the resilience, RAID 5 would degrade performance. Cost for hard drives: 16 x £239.60 = £3,833.60 For the hard drives we will need disk controllers and a separate external disk array because the likelihood is that the server itself won’t take the drives, a quick spec off DELL for a PowerVault MD1220 which gives the dual pathing with 16 disks 146GB 15Krpm 2.5” disks is priced at £7,438.00, note its probably more once we had two controller cards to sit in the server in, racking etc. Minimum cost taking the DELL quote as an example is therefore: {Cost of Hardware} / {Storage Required} £7,438.60 / 400 = £18.595 per GB £18.59 per GiB is a far cry from the £0.39 we had been told by the salesman and the myth. Yes, the storage array is composed of 16 x 146 disks in RAID 10 (therefore 8 usable) giving an effective usable storage availability of 1168GB but the actual storage requirement is only 400 and the extra disks have had to be purchased to get the  IOps up. Solid State Drive solution A single card significantly exceeds the IOps and latency required, for resilience two will be required. ( £2,316.54 * 2 ) / 400 = £11.58 per GB With the SSD solution only two PCIe sockets are required, no external disk units, no additional controllers, no redundant controllers etc. Conclusion I hope by showing you an example that the myth that hard disk drives are cheaper per GiB than Solid State has now been dispelled - £11.58 per GB for SSD compared to £18.59 for Hard Disk. I’ve not even touched on the running costs, compare the costs of running 18 hard disks, that’s a lot of heat and power compared to two PCIe cards!Just a quick note: I've left a fair amount of information out due to this being a blog! If in doubt, email me :)I'll also deal with the myth that SSD's wear out at a later date as well - that's just way over done still, yes, 5 years ago, but now - no.

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• Error 324 (net::ERR_EMPTY_RESPONSE): Unknown error.

  - by Kp

  I get the following error in Chrome every time I try to run my script on a Linux server: Error 324 (net::ERR_EMPTY_RESPONSE): Unknown error. In Firefox it just shows a blank white page. Whenever I run it on my local test server (IIS on Windows 7) it runs exactly the way it should with no errors. I am pretty sure that it is a problem with the imap_open function. error_reporting(E_ALL); echo "test"; // enter gmail username below e.g.-- $m_username = "yourusername"; $m_username = "username"; // enter gmail password below e.g.-- $m_password = "yourpword"; $m_password = "password"; // Enter the mail server to connect to $server = '{imap.gmail.com:993/imap/ssl/novalidate-cert}INBOX'; // enter the number of unread messages you want to display from mailbox or //enter 0 to display all unread messages e.g.-- $m_acs = 0; $m_acs = 10; // How far back in time do you want to search for unread messages - one month = 0 , two weeks = 1, one week = 2, three days = 3, // one day = 4, six hours = 5 or one hour = 6 e.g.-- $m_t = 6; $m_t = 2; //-----------Nothing More to edit below //open mailbox $m_mail = imap_open ($server, $m_username . "@gmail.com", $m_password) // or throw an error or die("ERROR: " . imap_last_error()); // unix time gone by $m_gunixtp = array(2592000, 1209600, 604800, 259200, 86400, 21600, 3600); // Date to start search $m_gdmy = date('d-M-Y', time() - $m_gunixtp[$m_t]); //search mailbox for unread messages since $m_t date $m_search=imap_search ($m_mail, 'ALL'); // Order results starting from newest message rsort($m_search); //if m_acs 0 then limit results if($m_acs 0){ array_splice($m_search, $m_acs); } $read = $_GET[read]; if ($read) { function get_mime_type(&$structure) { $primary_mime_type = array("TEXT", "MULTIPART","MESSAGE", "APPLICATION", "AUDIO","IMAGE", "VIDEO", "OTHER"); if($structure-subtype) { return $primary_mime_type[(int) $structure-type] . '/' .$structure-subtype; } return "TEXT/PLAIN"; } function get_part($stream, $msg_number, $mime_type, $structure = false,$part_number = false) { if(!$structure) { $structure = imap_fetchstructure($stream, $msg_number); } if($structure) { if($mime_type == get_mime_type($structure)) { if(!$part_number) { $part_number = "1"; } $text = imap_fetchbody($stream, $msg_number, $part_number); if($structure->encoding == 3) { return imap_base64($text); } else if($structure->encoding == 4) { return imap_qprint($text); } else { return $text; } } if($structure->type == 1) /* multipart */ { while(list($index, $sub_structure) = each($structure->parts)) { if($part_number) { $prefix = $part_number . '.'; } $data = get_part($stream, $msg_number, $mime_type, $sub_structure,$prefix . ($index + 1)); if($data) { return $data; } } // END OF WHILE } // END OF MULTIPART } // END OF STRUTURE return false; } // END OF FUNCTION // GET TEXT BODY $dataTxt = get_part($m_mail, $read, "TEXT/PLAIN"); // GET HTML BODY $dataHtml = get_part($m_mail, $read, "TEXT/HTML"); if ($dataHtml != "") { $msgBody = $dataHtml; $mailformat = "html"; } else { $msgBody = ereg_replace("\n","",$dataTxt); $mailformat = "text"; } if ($mailformat == "text") { echo "<html><head><title>Messagebody</title></head><body bgcolor=\"white\">$msgBody</body></html>"; } else { echo $msgBody; // It contains all HTML HEADER tags so we don't have to make them. } exit; } //loop it foreach ($m_search as $what_ever) { //get imap header info for obj thang $obj_thang = imap_headerinfo($m_mail, $what_ever); //get body info for obj thang $obj_thangs = imap_body($m_mail, $what_ever); //Then spit it out below.........if you dont swallow echo "Message ID# " . $what_ever . " Date: " . date("F j, Y, g:i a", $obj_thang-udate) . " From: " . $obj_thang-fromaddress . " To: " . $obj_thang-toaddress . " Subject: " . $obj_thang-Subject . " "; } echo "" . $m_empty . ""; //close mailbox imap_close($m_mail); ?

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• The remote server returned an error: (400) Bad Request - uploading less 2MB file size?

  - by fiberOptics

  The file succeed to upload when it is 2KB or lower in size. The main reason why I use streaming is to be able to upload file up to at least 1 GB. But when I try to upload file with less 1MB size, I get bad request. It is my first time to deal with downloading and uploading process, so I can't easily find the cause of error. Testing part: private void button24_Click(object sender, EventArgs e) { try { OpenFileDialog openfile = new OpenFileDialog(); if (openfile.ShowDialog() == System.Windows.Forms.DialogResult.OK) { string port = "3445"; byte[] fileStream; using (FileStream fs = new FileStream(openfile.FileName, FileMode.Open, FileAccess.Read, FileShare.Read)) { fileStream = new byte[fs.Length]; fs.Read(fileStream, 0, (int)fs.Length); fs.Close(); fs.Dispose(); } string baseAddress = "http://localhost:" + port + "/File/AddStream?fileID=9"; HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(baseAddress); request.Method = "POST"; request.ContentType = "text/plain"; //request.ContentType = "application/octet-stream"; Stream serverStream = request.GetRequestStream(); serverStream.Write(fileStream, 0, fileStream.Length); serverStream.Close(); using (HttpWebResponse response = request.GetResponse() as HttpWebResponse) { int statusCode = (int)response.StatusCode; StreamReader reader = new StreamReader(response.GetResponseStream()); } } } catch (Exception ex) { MessageBox.Show(ex.Message); } } Service: [WebInvoke(UriTemplate = "AddStream?fileID={fileID}", Method = "POST", BodyStyle = WebMessageBodyStyle.Bare)] public bool AddStream(long fileID, System.IO.Stream fileStream) { ClasslLogic.FileComponent svc = new ClasslLogic.FileComponent(); return svc.AddStream(fileID, fileStream); } Server code for streaming: namespace ClasslLogic { public class StreamObject : IStreamObject { public bool UploadFile(string filename, Stream fileStream) { try { FileStream fileToupload = new FileStream(filename, FileMode.Create); byte[] bytearray = new byte[10000]; int bytesRead, totalBytesRead = 0; do { bytesRead = fileStream.Read(bytearray, 0, bytearray.Length); totalBytesRead += bytesRead; } while (bytesRead > 0); fileToupload.Write(bytearray, 0, bytearray.Length); fileToupload.Close(); fileToupload.Dispose(); } catch (Exception ex) { throw new Exception(ex.Message); } return true; } } } Web config: <system.serviceModel> <bindings> <basicHttpBinding> <binding> <readerQuotas maxDepth="32" maxStringContentLength="8192" maxArrayLength="2097152" maxBytesPerRead="4096" maxNameTableCharCount="2097152" /> <security mode="None" /> </binding> <binding name="ClassLogicBasicTransfer" closeTimeout="00:05:00" openTimeout="00:05:00" receiveTimeout="00:15:00" sendTimeout="00:01:00" allowCookies="false" bypassProxyOnLocal="false" hostNameComparisonMode="StrongWildcard" maxBufferPoolSize="67108864" maxReceivedMessageSize="67108864" messageEncoding="Mtom" textEncoding="utf-8" useDefaultWebProxy="true"> <readerQuotas maxDepth="32" maxStringContentLength="8192" maxArrayLength="67108864" maxBytesPerRead="4096" maxNameTableCharCount="67108864" /> <security mode="None"> <transport clientCredentialType="None" proxyCredentialType="None" realm="" /> <message clientCredentialType="UserName" algorithmSuite="Default" /> </security> </binding> <binding name="BaseLogicWSHTTP"> <security mode="None" /> </binding> <binding name="BaseLogicWSHTTPSec" /> </basicHttpBinding> </bindings> <behaviors> <serviceBehaviors> <behavior> <!-- To avoid disclosing metadata information, set the value below to false and remove the metadata endpoint above before deployment --> <serviceMetadata httpGetEnabled="true" /> <!-- To receive exception details in faults for debugging purposes, set the value below to true. Set to false before deployment to avoid disclosing exception information --> <serviceDebug includeExceptionDetailInFaults="true" /> </behavior> </serviceBehaviors> </behaviors> <serviceHostingEnvironment multipleSiteBindingsEnabled="true" aspNetCompatibilityEnabled="true" /> </system.serviceModel> I'm not sure if this affects the streaming function, because I'm using WCF4.0 rest template which config is dependent in Global.asax. One more thing is this, whether I run the service and passing a stream or not, the created file always contain this thing. How could I remove the "NUL" data? Thanks in advance. Edit public bool UploadFile(string filename, Stream fileStream) { try { FileStream fileToupload = new FileStream(filename, FileMode.Create); byte[] bytearray = new byte[10000]; int bytesRead, totalBytesRead = 0; do { bytesRead = fileStream.Read(bytearray, totalBytesRead, bytearray.Length - totalBytesRead); totalBytesRead += bytesRead; } while (bytesRead > 0); fileToupload.Write(bytearray, 0, totalBytesRead); fileToupload.Close(); fileToupload.Dispose(); } catch (Exception ex) { throw new Exception(ex.Message); } return true; }

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• NUMA-aware placement of communication variables

  - by Dave

  For classic NUMA-aware programming I'm typically most concerned about simple cold, capacity and compulsory misses and whether we can satisfy the miss by locally connected memory or whether we have to pull the line from its home node over the coherent interconnect -- we'd like to minimize channel contention and conserve interconnect bandwidth. That is, for this style of programming we're quite aware of where memory is homed relative to the threads that will be accessing it. Ideally, a page is collocated on the node with the thread that's expected to most frequently access the page, as simple misses on the page can be satisfied without resorting to transferring the line over the interconnect. The default "first touch" NUMA page placement policy tends to work reasonable well in this regard. When a virtual page is first accessed, the operating system will attempt to provision and map that virtual page to a physical page allocated from the node where the accessing thread is running. It's worth noting that the node-level memory interleaving granularity is usually a multiple of the page size, so we can say that a given page P resides on some node N. That is, the memory underlying a page resides on just one node. But when thinking about accesses to heavily-written communication variables we normally consider what caches the lines underlying such variables might be resident in, and in what states. We want to minimize coherence misses and cache probe activity and interconnect traffic in general. I don't usually give much thought to the location of the home NUMA node underlying such highly shared variables. On a SPARC T5440, for instance, which consists of 4 T2+ processors connected by a central coherence hub, the home node and placement of heavily accessed communication variables has very little impact on performance. The variables are frequently accessed so likely in M-state in some cache, and the location of the home node is of little consequence because a requester can use cache-to-cache transfers to get the line. Or at least that's what I thought. Recently, though, I was exploring a simple shared memory point-to-point communication model where a client writes a request into a request mailbox and then busy-waits on a response variable. It's a simple example of delegation based on message passing. The server polls the request mailbox, and having fetched a new request value, performs some operation and then writes a reply value into the response variable. As noted above, on a T5440 performance is insensitive to the placement of the communication variables -- the request and response mailbox words. But on a Sun/Oracle X4800 I noticed that was not the case and that NUMA placement of the communication variables was actually quite important. For background an X4800 system consists of 8 Intel X7560 Xeons . Each package (socket) has 8 cores with 2 contexts per core, so the system is 8x8x2. Each package is also a NUMA node and has locally attached memory. Every package has 3 point-to-point QPI links for cache coherence, and the system is configured with a twisted ladder "mobius" topology. The cache coherence fabric is glueless -- there's not central arbiter or coherence hub. The maximum distance between any two nodes is just 2 hops over the QPI links. For any given node, 3 other nodes are 1 hop distant and the remaining 4 nodes are 2 hops distant. Using a single request (client) thread and a single response (server) thread, a benchmark harness explored all permutations of NUMA placement for the two threads and the two communication variables, measuring the average round-trip-time and throughput rate between the client and server. In this benchmark the server simply acts as a simple transponder, writing the request value plus 1 back into the reply field, so there's no particular computation phase and we're only measuring communication overheads. In addition to varying the placement of communication variables over pairs of nodes, we also explored variations where both variables were placed on one page (and thus on one node) -- either on the same cache line or different cache lines -- while varying the node where the variables reside along with the placement of the threads. The key observation was that if the client and server threads were on different nodes, then the best placement of variables was to have the request variable (written by the client and read by the server) reside on the same node as the client thread, and to place the response variable (written by the server and read by the client) on the same node as the server. That is, if you have a variable that's to be written by one thread and read by another, it should be homed with the writer thread. For our simple client-server model that means using split request and response communication variables with unidirectional message flow on a given page. This can yield up to twice the throughput of less favorable placement strategies. Our X4800 uses the QPI 1.0 protocol with source-based snooping. Briefly, when node A needs to probe a cache line it fires off snoop requests to all the nodes in the system. Those recipients then forward their response not to the original requester, but to the home node H of the cache line. H waits for and collects the responses, adjudicates and resolves conflicts and ensures memory-model ordering, and then sends a definitive reply back to the original requester A. If some node B needed to transfer the line to A, it will do so by cache-to-cache transfer and let H know about the disposition of the cache line. A needs to wait for the authoritative response from H. So if a thread on node A wants to write a value to be read by a thread on node B, the latency is dependent on the distances between A, B, and H. We observe the best performance when the written-to variable is co-homed with the writer A. That is, we want H and A to be the same node, as the writer doesn't need the home to respond over the QPI link, as the writer and the home reside on the very same node. With architecturally informed placement of communication variables we eliminate at least one QPI hop from the critical path. Newer Intel processors use the QPI 1.1 coherence protocol with home-based snooping. As noted above, under source-snooping a requester broadcasts snoop requests to all nodes. Those nodes send their response to the home node of the location, which provides memory ordering, reconciles conflicts, etc., and then posts a definitive reply to the requester. In home-based snooping the snoop probe goes directly to the home node and are not broadcast. The home node can consult snoop filters -- if present -- and send out requests to retrieve the line if necessary. The 3rd party owner of the line, if any, can respond either to the home or the original requester (or even to both) according to the protocol policies. There are myriad variations that have been implemented, and unfortunately vendor terminology doesn't always agree between vendors or with the academic taxonomy papers. The key is that home-snooping enables the use of a snoop filter to reduce interconnect traffic. And while home-snooping might have a longer critical path (latency) than source-based snooping, it also may require fewer messages and less overall bandwidth. It'll be interesting to reprise these experiments on a platform with home-based snooping. While collecting data I also noticed that there are placement concerns even in the seemingly trivial case when both threads and both variables reside on a single node. Internally, the cores on each X7560 package are connected by an internal ring. (Actually there are multiple contra-rotating rings). And the last-level on-chip cache (LLC) is partitioned in banks or slices, which with each slice being associated with a core on the ring topology. A hardware hash function associates each physical address with a specific home bank. Thus we face distance and topology concerns even for intra-package communications, although the latencies are not nearly the magnitude we see inter-package. I've not seen such communication distance artifacts on the T2+, where the cache banks are connected to the cores via a high-speed crossbar instead of a ring -- communication latencies seem more regular.

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• Completing install of ruby 1.9.3 with Ruby for for Mac OS X 10.7.5 Leopard, Xcode 4.5.2 -- problems with rvm pkg install openssl

  - by user1848361

  First, many thanks in advance for any help. I'm a complete novice with programming and I'm trying to get started with this Ruby on Rails tutorial (http://ruby.railstutorial.org/ruby-on-rails-tutorial-book?version=3.2) I have been trying figure this out for about 7 hours now and since I don't have any hair left to pull out I'm turning to these hallowed pages. I have searched for solutions here again and again. System: Mac OS X 10.7.5 Leopard, Xcode 4.5.2 I installed homebrew and have updated it multiple times I used homebrew to install rvm and have updated it multiple times I installed git The standard ruby on the system (checking with $ ruby -v) is 1.8.7 My problem is that every time I try to use rvm to install a new version of Ruby ($ rvm install 1.9.3) I get the following error: Ruby (and needed base gems) for your selection will be installed shortly. Before it happens, please read and execute the instructions below. Please use a separate terminal to execute any additional commands. Notes for Mac OS X 10.7.5, Xcode 4.5.2. For JRuby: Install the JDK. See http://developer.apple.com/java/download/ # Current Java version "1.6.0_26" For IronRuby: Install Mono >= 2.6 For Ruby 1.9.3: Install libksba # If using Homebrew, 'brew install libksba' For Opal: Install Nodejs with NPM. See http://nodejs.org/download/ To use an RVM installed Ruby as default, instead of the system ruby: rvm install 1.8.7 # installs patch 357: closest supported version rvm system ; rvm gemset export system.gems ; rvm 1.8.7 ; rvm gemset import system.gems # migrate your gems rvm alias create default 1.8.7 And reopen your terminal windows. Xcode and gcc: : I have performed $ brew install libksba and when I try to do it again it tells me that libksba is installed already. When I type "$ rvm requirements" I get: Notes for Mac OS X 10.7.5, Xcode 4.5.2. For JRuby: Install the JDK. See http://developer.apple.com/java/download/ # Current Java version "1.6.0_26" For IronRuby: Install Mono >= 2.6 For Ruby 1.9.3: Install libksba # If using Homebrew, 'brew install libksba' For Opal: Install Nodejs with NPM. See http://nodejs.org/download/ To use an RVM installed Ruby as default, instead of the system ruby: rvm install 1.8.7 # installs patch 357: closest supported version rvm system ; rvm gemset export system.gems ; rvm 1.8.7 ; rvm gemset import system.gems # migrate your gems rvm alias create default 1.8.7 And reopen your terminal windows. Xcode and gcc: Right now Ruby requires gcc to compile, but Xcode 4.2 and later no longer ship with gcc. Instead they ship with llvm-gcc (to which gcc is a symlink) and clang, neither of which are supported for building Ruby. Xcode 4.1 was the last version to ship gcc, which was /usr/bin/gcc-4.2. Xcode 4.1 and earlier: - Ruby will build fine. Xcode 4.2 and later (including Command Line Tools for Xcode): - If you have gcc-4.2 (and friends) from an earlier Xcode version, Ruby will build fine. - If you don't have gcc-4.2, you have two options to get it: * Install apple-gcc42 from Homebrew * Install osx-gcc-installer Homebrew: If you are using Homebrew, you can install the apple-gcc42 and required libraries from homebrew/dupes: brew update brew tap homebrew/dupes brew install autoconf automake apple-gcc42 rvm pkg install openssl Xcode 4.2+ install or/and Command Line Tools for Xcode is required to provide make and other tools. osx-gcc-installer: If you don't use Homebrew, you can download and install osx-gcc-installer: https://github.com/kennethreitz/osx-gcc-installer. Warning: Installing osx-gcc-installer on top of a recent Xcode is known to cause problems, so you must uninstall Xcode before installing osx-gcc-installer. Afterwards you may install Xcode 4.2+ or Command Line Tools for Xcode if you desire. ** NOTE: Currently, Node.js is having issues building with osx-gcc-installer. The only fix is to install Xcode over osx-gcc-installer. So I assume I have to do something with brew update brew tap homebrew/dupes brew install autoconf automake apple-gcc42 rvm pkg install openssl Everything seemed to work fine until "$ rvm pkg install openssl", which returns: Fetching openssl-1.0.1c.tar.gz to /Users/thierinvestmentservices/.rvm/archives Extracting openssl to /Users/thierinvestmentservices/.rvm/src/openssl-1.0.1c Configuring openssl in /Users/thierinvestmentservices/.rvm/src/openssl-1.0.1c. Compiling openssl in /Users/thierinvestmentservices/.rvm/src/openssl-1.0.1c. Error running 'make', please read /Users/thierinvestmentservices/.rvm/log/openssl/make.log Please note that it's required to reinstall all rubies: rvm reinstall all --force Updating openssl certificates Error running 'update_openssl_certs', please read /Users/thierinvestmentservices/.rvm/log/openssl.certs.log Johns-MacBook-Pro:~ thierinvestmentservices$ rvm pkg install openssl Fetching openssl-1.0.1c.tar.gz to /Users/thierinvestmentservices/.rvm/archives Extracting openssl to /Users/thierinvestmentservices/.rvm/src/openssl-1.0.1c Configuring openssl in /Users/thierinvestmentservices/.rvm/src/openssl-1.0.1c. Compiling openssl in /Users/thierinvestmentservices/.rvm/src/openssl-1.0.1c. Error running 'make', please read /Users/thierinvestmentservices/.rvm/log/openssl/make.log Please note that it's required to reinstall all rubies: rvm reinstall all --force Updating openssl certificates Error running 'update_openssl_certs', please read /Users/thierinvestmentservices/.rvm/log/openssl.certs.log make.log reads "[2012-11-23 13:15:28] make /Users/thierinvestmentservices/.rvm/scripts/functions/utility: line 116: make: command not found" and openssl.certs.log reads "[2012-11-23 14:04:04] update_openssl_certs update_openssl_certs () { ( chpwd_functions="" builtin cd $rvm_usr_path/ssl && command curl -O http://curl.haxx.se/ca/cacert.pem && mv cacert.pem cert.pem ) } current path: /Users/thierinvestmentservices command(1): update_openssl_certs /Users/thierinvestmentservices/.rvm/scripts/functions/pkg: line 205: cd: /Users/thierinvestmentservices/.rvm/usr/ssl: No such file or directory" At this point the letters might as well be wingdings I have no idea what is going on. I have tried to install rvm make with something I saw on one forum post but I got a bunch of warnings. If anyone has any suggestions I would be deeply grateful, I am completely in over my head,

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• Super constructor must be a first statement in Java constructor [closed]

  - by Val

  I know the answer: "we need rules to prevent shooting into your own foot". Ok, I make millions of programming mistakes every day. To be prevented, we need one simple rule: prohibit all JLS and do not use Java. If we explain everything by "not shooting your foot", this is reasonable. But there is not much reason is such reason. When I programmed in Delphy, I always wanted the compiler to check me if I read uninitializable. I have discovered myself that is is stupid to read uncertain variable because it leads unpredictable result and is errorenous obviously. By just looking at the code I could see if there is an error. I wished if compiler could do this job. It is also a reliable signal of programming error if function does not return any value. But I never wanted it do enforce me the super constructor first. Why? You say that constructors just initialize fields. Super fields are derived; extra fields are introduced. From the goal point of view, it does not matter in which order you initialize the variables. I have studied parallel architectures and can say that all the fields can even be assigned in parallel... What? Do you want to use the unitialized fields? Stupid people always want to take away our freedoms and break the JLS rules the God gives to us! Please, policeman, take away that person! Where do I say so? I'm just saying only about initializing/assigning, not using the fields. Java compiler already defends me from the mistake of accessing notinitialized. Some cases sneak but this example shows how this stupid rule does not save us from the read-accessing incompletely initialized in construction: public class BadSuper { String field; public String toString() { return "field = " + field; } public BadSuper(String val) { field = val; // yea, superfirst does not protect from accessing // inconstructed subclass fields. Subclass constr // must be called before super()! System.err.println(this); } } public class BadPost extends BadSuper { Object o; public BadPost(Object o) { super("str"); this. o = o; } public String toString() { // superconstructor will boom here, because o is not initialized! return super.toString() + ", obj = " + o.toString(); } public static void main(String[] args) { new BadSuper("test 1"); new BadPost(new Object()); } } It shows that actually, subfields have to be inilialized before the supreclass! Meantime, java requirement "saves" us from writing specializing the class by specializing what the super constructor argument is, public class MyKryo extends Kryo { class MyClassResolver extends DefaultClassResolver { public Registration register(Registration registration) { System.out.println(MyKryo.this.getDepth()); return super.register(registration); } } MyKryo() { // cannot instantiate MyClassResolver in super super(new MyClassResolver(), new MapReferenceResolver()); } } Try to make it compilable. It is always pain. Especially, when you cannot assign the argument later. Initialization order is not important for initialization in general. I could understand that you should not use super methods before initializing super. But, the requirement for super to be the first statement is different. It only saves you from the code that does useful things simply. I do not see how this adds safety. Actually, safety is degraded because we need to use ugly workarounds. Doing post-initialization, outside the constructors also degrades safety (otherwise, why do we need constructors?) and defeats the java final safety reenforcer. To conclude Reading not initialized is a bug. Initialization order is not important from the computer science point of view. Doing initalization or computations in different order is not a bug. Reenforcing read-access to not initialized is good but compilers fail to detect all such bugs Making super the first does not solve the problem as it "Prevents" shooting into right things but not into the foot It requires to invent workarounds, where, because of complexity of analysis, it is easier to shoot into the foot doing post-initialization outside the constructors degrades safety (otherwise, why do we need constructors?) and that degrade safety by defeating final access modifier When there was java forum alive, java bigots attecked me for these thoughts. Particularly, they dislaked that fields can be initialized in parallel, saying that natural development ensures correctness. When I replied that you could use an advanced engineering to create a human right away, without "developing" any ape first, and it still be an ape, they stopped to listen me. Cos modern technology cannot afford it. Ok, Take something simpler. How do you produce a Renault? Should you construct an Automobile first? No, you start by producing a Renault and, once completed, you'll see that this is an automobile. So, the requirement to produce fields in "natural order" is unnatural. In case of alarmclock or armchair, which are still chair and clock, you may need first develop the base (clock and chair) and then add extra. So, I can have examples where superfields must be initialized first and, oppositely, when they need to be initialized later. The order does not exist in advance. So, the compiler cannot be aware of the proper order. Only programmer/constructor knows is. Compiler should not take more responsibility and enforce the wrong order onto programmer. Saying that I cannot initialize some fields because I did not ininialized the others is like "you cannot initialize the thing because it is not initialized". This is a kind of argument we have. So, to conclude once more, the feature that "protects" me from doing things in simple and right way in order to enforce something that does not add noticeably to the bug elimination at that is a strongly negative thing and it pisses me off, altogether with the all the arguments to support it I've seen so far. It is "a conceptual question about software development" Should there be the requirement to call super() first or not. I do not know. If you do or have an idea, you have place to answer. I think that I have provided enough arguments against this feature. Lets appreciate the ones who benefit form it. Let it just be something more than simple abstract and stupid "write your own language" or "protection" kind of argument. Why do we need it in the language that I am going to develop?

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• Passing a parameter so that it cannot be changed – C#

  - by nmarun

  I read this requirement of not allowing a user to change the value of a property passed as a parameter to a method. In C++, as far as I could recall (it’s been over 10 yrs, so I had to refresh memory), you can pass ‘const’ to a function parameter and this ensures that the parameter cannot be changed inside the scope of the function. There’s no such direct way of doing this in C#, but that does not mean it cannot be done!! Ok, so this ‘not-so-direct’ technique depends on the type of the parameter – a simple property or a collection. Parameter as a simple property: This is quite easy (and you might have guessed it already). Bulent Ozkir clearly explains how this can be done here. Parameter as a collection property: Obviously the above does not work if the parameter is a collection of some type. Let’s dig-in. Suppose I need to create a collection of type KeyTitle as defined below. 1: public class KeyTitle 2: { 3: public int Key { get; set; } 4: public string Title { get; set; } 5: } My class is declared as below: 1: public class Class1 2: { 3: public Class1() 4: { 5: MyKeyTitleList = new List<KeyTitle>(); 6: } 7: 8: public List<KeyTitle> MyKeyTitleList { get; set; } 9: public ReadOnlyCollection<KeyTitle> ReadonlyKeyTitleCollection 10: { 11: // .AsReadOnly creates a ReadOnlyCollection<> type 12: get { return MyKeyTitleList.AsReadOnly(); } 13: } 14: } See the .AsReadOnly() method used in the second property? As MSDN says it: “Returns a read-only IList<T> wrapper for the current collection.” Knowing this, I can implement my code as: 1: public static void Main() 2: { 3: Class1 class1 = new Class1(); 4: class1.MyKeyTitleList.Add(new KeyTitle { Key = 1, Title = "abc" }); 5: class1.MyKeyTitleList.Add(new KeyTitle { Key = 2, Title = "def" }); 6: class1.MyKeyTitleList.Add(new KeyTitle { Key = 3, Title = "ghi" }); 7: class1.MyKeyTitleList.Add(new KeyTitle { Key = 4, Title = "jkl" }); 8:  9: TryToModifyCollection(class1.MyKeyTitleList.AsReadOnly()); 10:  11: Console.ReadLine(); 12: } 13:  14: private static void TryToModifyCollection(ReadOnlyCollection<KeyTitle> readOnlyCollection) 15: { 16: // can only read 17: for (int i = 0; i < readOnlyCollection.Count; i++) 18: { 19: Console.WriteLine("{0} - {1}", readOnlyCollection[i].Key, readOnlyCollection[i].Title); 20: } 21: // Add() - not allowed 22: // even the indexer does not have a setter 23: } The output is as expected: The below image shows two things. In the first line, I’ve tried to access an element in my read-only collection through an indexer. It shows that the ReadOnlyCollection<> does not have a setter on the indexer. The second line tells that there’s no ‘Add()’ method for this type of collection. The capture below shows there’s no ‘Remove()’ method either, there-by eliminating all ways of modifying a collection. Mission accomplished… right? Now, even if you have a collection of different type, all you need to do is to somehow cast (used loosely) it to a List<> and then do a .AsReadOnly() to get a ReadOnlyCollection of your custom collection type. As an example, if you have an IDictionary<int, string>, you can create a List<T> of this type with a wrapper class (KeyTitle in our case). 1: public IDictionary<int, string> MyDictionary { get; set; } 2:  3: public ReadOnlyCollection<KeyTitle> ReadonlyDictionary 4: { 5: get 6: { 7: return (from item in MyDictionary 8: select new KeyTitle 9: { 10: Key = item.Key, 11: Title = item.Value, 12: }).ToList().AsReadOnly(); 13: } 14: } Cool huh? Just one thing you need to know about the .AsReadOnly() method is that the only way to modify your ReadOnlyCollection<> is to modify the original collection. So doing: 1: public static void Main() 2: { 3: Class1 class1 = new Class1(); 4: class1.MyKeyTitleList.Add(new KeyTitle { Key = 1, Title = "abc" }); 5: class1.MyKeyTitleList.Add(new KeyTitle { Key = 2, Title = "def" }); 6: class1.MyKeyTitleList.Add(new KeyTitle { Key = 3, Title = "ghi" }); 7: class1.MyKeyTitleList.Add(new KeyTitle { Key = 4, Title = "jkl" }); 8: TryToModifyCollection(class1.MyKeyTitleList.AsReadOnly()); 9:  10: Console.WriteLine(); 11:  12: class1.MyKeyTitleList.Add(new KeyTitle { Key = 5, Title = "mno" }); 13: class1.MyKeyTitleList[2] = new KeyTitle{Key = 3, Title = "GHI"}; 14: TryToModifyCollection(class1.MyKeyTitleList.AsReadOnly()); 15:  16: Console.ReadLine(); 17: } Gives me the output of: See that the second element’s Title is changed to upper-case and the fifth element also gets displayed even though we’re still looping through the same ReadOnlyCollection<KeyTitle>. Verdict: Now you know of a way to implement ‘Method(const param1)’ in your code!

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• I asked this yesterday, after the input given I'm still having trouble implementing..

  - by Josh

  I'm not sure how to fix this or what I did wrong, but whenever I enter in a value it just closes out the run prompt. So, seems I do have a problem somewhere in my coding. Whenever I run the program and input a variable, it always returns the same answer.."The content at location 76 is 0." On that note, someone told me that "I don't know, but I suspect that Program A incorrectly has a fixed address being branched to on instructions 10 and 11." - mctylr but I'm not sure how to fix that.. I'm trying to figure out how to incorporate this idea from R Samuel Klatchko.. I'm still not sure what I'm missing but I can't get it to work.. const int OP_LOAD = 3; const int OP_STORE = 4; const int OP_ADD = 5; ... const int OP_LOCATION_MULTIPLIER = 100; mem[0] = OP_LOAD * OP_LOCATION_MULTIPLIER + ...; mem[1] = OP_ADD * OP_LOCATION_MULTIPLIER + ...; operand = memory[ j ] % OP_LOCATION_MULTIPLIER; operation = memory[ j ] / OP_LOCATION_MULTIPLIER; I'm new to programming, I'm not the best, so I'm going for simplicity. Also this is an SML program. Anyway, this IS a homework assignment and I'm wanting a good grade on this. So I was looking for input and making sure this program will do what I'm hoping they are looking for. Anyway, here are the instructions: Write SML (Simpletron Machine language) programs to accomplish each of the following task: A) Use a sentinel-controlled loop to read positive number s and compute and print their sum. Terminate input when a neg number is entered. B) Use a counter-controlled loop to read seven numbers, some positive and some negative, and compute + print the avg. C) Read a series of numbers, and determine and print the largest number. The first number read indicates how many numbers should be processed. Without further a due, here is my program. All together. int main() { const int READ = 10; const int WRITE = 11; const int LOAD = 20; const int STORE = 21; const int ADD = 30; const int SUBTRACT = 31; const int DIVIDE = 32; const int MULTIPLY = 33; const int BRANCH = 40; const int BRANCHNEG = 41; const int BRANCHZERO = 41; const int HALT = 43; int mem[100] = {0}; //Making it 100, since simpletron contains a 100 word mem. int operation; //taking the rest of these variables straight out of the book seeing as how they were italisized. int operand; int accum = 0; // the special register is starting at 0 int j; // This is for part a, it will take in positive variables in a sent-controlled loop and compute + print their sum. Variables from example in text. memory [0] = 1010; memory [01] = 2009; memory [02] = 3008; memory [03] = 2109; memory [04] = 1109; memory [05] = 4300; memory [06] = 1009; j = 0; //Makes the variable j start at 0. while ( true ) { operand = memory[ j ]%100; // Finds the op codes from the limit on the memory (100) operation = memory[ j ]/100; //using a switch loop to set up the loops for the cases switch ( operation ){ case 10: //reads a variable into a word from loc. Enter in -1 to exit cout <<"\n Input a positive variable: "; cin >> memory[ operand ]; break; case 11: // takes a word from location cout << "\n\nThe content at location " << operand << "is " << memory[operand]; break; case 20:// loads accum = memory[ operand ]; break; case 21: //stores memory[ operand ] = accum; break; case 30: //adds accum += mem[operand]; break; case 31: // subtracts accum-= memory[ operand ]; break; case 32: //divides accum /=(memory[ operand ]); break; case 33: // multiplies accum*= memory [ operand ]; break; case 40: // Branches to location j = -1; break; case 41: //branches if acc. is < 0 if (accum < 0) j = 5; break; case 42: //branches if acc = 0 if (accum == 0) j = 5; break; case 43: // Program ends exit(0); break; } j++; } return 0; }

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• Organization &amp; Architecture UNISA Studies &ndash; Chap 4

  - by MarkPearl

  Learning Outcomes Explain the characteristics of memory systems Describe the memory hierarchy Discuss cache memory principles Discuss issues relevant to cache design Describe the cache organization of the Pentium Computer Memory Systems There are key characteristics of memory… Location – internal or external Capacity – expressed in terms of bytes Unit of Transfer – the number of bits read out of or written into memory at a time Access Method – sequential, direct, random or associative From a users perspective the two most important characteristics of memory are… Capacity Performance – access time, memory cycle time, transfer rate The trade off for memory happens along three axis… Faster access time, greater cost per bit Greater capacity, smaller cost per bit Greater capacity, slower access time This leads to people using a tiered approach in their use of memory   As one goes down the hierarchy, the following occurs… Decreasing cost per bit Increasing capacity Increasing access time Decreasing frequency of access of the memory by the processor The use of two levels of memory to reduce average access time works in principle, but only if conditions 1 to 4 apply. A variety of technologies exist that allow us to accomplish this. Thus it is possible to organize data across the hierarchy such that the percentage of accesses to each successively lower level is substantially less than that of the level above. A portion of main memory can be used as a buffer to hold data temporarily that is to be read out to disk. This is sometimes referred to as a disk cache and improves performance in two ways… Disk writes are clustered. Instead of many small transfers of data, we have a few large transfers of data. This improves disk performance and minimizes processor involvement. Some data designed for write-out may be referenced by a program before the next dump to disk. In that case the data is retrieved rapidly from the software cache rather than slowly from disk. Cache Memory Principles Cache memory is substantially faster than main memory. A caching system works as follows.. When a processor attempts to read a word of memory, a check is made to see if this in in cache memory… If it is, the data is supplied, If it is not in the cache, a block of main memory, consisting of a fixed number of words is loaded to the cache. Because of the phenomenon of locality of references, when a block of data is fetched into the cache, it is likely that there will be future references to that same memory location or to other words in the block. Elements of Cache Design While there are a large number of cache implementations, there are a few basic design elements that serve to classify and differentiate cache architectures… Cache Addresses Cache Size Mapping Function Replacement Algorithm Write Policy Line Size Number of Caches Cache Addresses Almost all non-embedded processors support virtual memory. Virtual memory in essence allows a program to address memory from a logical point of view without needing to worry about the amount of physical memory available. When virtual addresses are used the designer may choose to place the cache between the MMU (memory management unit) and the processor or between the MMU and main memory. The disadvantage of virtual memory is that most virtual memory systems supply each application with the same virtual memory address space (each application sees virtual memory starting at memory address 0), which means the cache memory must be completely flushed with each application context switch or extra bits must be added to each line of the cache to identify which virtual address space the address refers to. Cache Size We would like the size of the cache to be small enough so that the overall average cost per bit is close to that of main memory alone and large enough so that the overall average access time is close to that of the cache alone. Also, larger caches are slightly slower than smaller ones. Mapping Function Because there are fewer cache lines than main memory blocks, an algorithm is needed for mapping main memory blocks into cache lines. The choice of mapping function dictates how the cache is organized. Three techniques can be used… Direct – simplest technique, maps each block of main memory into only one possible cache line Associative – Each main memory block to be loaded into any line of the cache Set Associative – exhibits the strengths of both the direct and associative approaches while reducing their disadvantages For detailed explanations of each approach – read the text book (page 148 – 154) Replacement Algorithm For associative and set associating mapping a replacement algorithm is needed to determine which of the existing blocks in the cache must be replaced by a new block. There are four common approaches… LRU (Least recently used) FIFO (First in first out) LFU (Least frequently used) Random selection Write Policy When a block resident in the cache is to be replaced, there are two cases to consider If no writes to that block have happened in the cache – discard it If a write has occurred, a process needs to be initiated where the changes in the cache are propagated back to the main memory. There are several approaches to achieve this including… Write Through – all writes to the cache are done to the main memory as well at the point of the change Write Back – when a block is replaced, all dirty bits are written back to main memory The problem is complicated when we have multiple caches, there are techniques to accommodate for this but I have not summarized them. Line Size When a block of data is retrieved and placed in the cache, not only the desired word but also some number of adjacent words are retrieved. As the block size increases from very small to larger sizes, the hit ratio will at first increase because of the principle of locality, which states that the data in the vicinity of a referenced word are likely to be referenced in the near future. As the block size increases, more useful data are brought into cache. The hit ratio will begin to decrease as the block becomes even bigger and the probability of using the newly fetched information becomes less than the probability of using the newly fetched information that has to be replaced. Two specific effects come into play… Larger blocks reduce the number of blocks that fit into a cache. Because each block fetch overwrites older cache contents, a small number of blocks results in data being overwritten shortly after they are fetched. As a block becomes larger, each additional word is farther from the requested word and therefore less likely to be needed in the near future. The relationship between block size and hit ratio is complex, and no set approach is judged to be the best in all circumstances.   Pentium 4 and ARM cache organizations The processor core consists of four major components: Fetch/decode unit – fetches program instruction in order from the L2 cache, decodes these into a series of micro-operations, and stores the results in the L2 instruction cache Out-of-order execution logic – Schedules execution of the micro-operations subject to data dependencies and resource availability – thus micro-operations may be scheduled for execution in a different order than they were fetched from the instruction stream. As time permits, this unit schedules speculative execution of micro-operations that may be required in the future Execution units – These units execute micro-operations, fetching the required data from the L1 data cache and temporarily storing results in registers Memory subsystem – This unit includes the L2 and L3 caches and the system bus, which is used to access main memory when the L1 and L2 caches have a cache miss and to access the system I/O resources

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• SimpleXMLElement empty object

  - by Mike

  Hi, I am trying to parse an xml file using XmlReader but although I am getting a return from the xml file for the (commission) node for some reason I am getting an empty SimpleXMLElement Object returned as well. I don't know if its something to do with while loop,switch or something I missed in the parse setup. This is the xml file I am trying to read from, as you can see there is only 1 result returned: <?xml version="1.0" encoding="UTF-8"?> <cj-api> <commissions total-matched="1"> <commission> <action-status> new </action-status> <action-type> lead </action-type> <aid> 10730981 </aid> <commission-id> 1021015513 </commission-id> <country> </country> <event-date> 2010-05-08T08:08:55-0700 </event-date> <locking-date> 2010-06-10 </locking-date> <order-id> 345007 </order-id> <original> true </original> <original-action-id> 787692438 </original-action-id> <posting-date> 2010-05-08T10:01:22-0700 </posting-date> <website-id> 3201921 </website-id> <cid> 2815954 </cid> <advertiser-name> SPS EurosportBET </advertiser-name> <commission-amount> 0 </commission-amount> <order-discount> 0 </order-discount> <sid> 0 </sid> <sale-amount> 0 </sale-amount> </commission> </commissions> </cj-api> This is my parser: <?php // read $response (xml feed) $file = "datafeed.xml"; $xml = new XMLReader; $xml->open($file); // loop to read in data while ($xml->read()) { switch ($xml->name) { // find the parent node for each commission payment case 'commission': // initalise xml parser $dom = new DomDocument(); $dom_node = $xml ->expand(); $element = $dom->appendChild($dom_node); $dom_string = $dom->saveXML($element); $commission = new SimpleXMLElement($dom_string); // read in data $action_status = $commission->{'action-status'}; $action_type = $commission->{'action-type'}; $aid = $commission->{'aid'}; $commission_id = $commission->{'commission-id'}; $country = $commission->{'country'}; $event_date = $commission->{'event-date'}; $locking_date = $commission->{'locking-date'}; $order_id = $commission->{'order-id'}; $original = $commission->{'original'}; $original_action_id = $commission->{'original_action-id'}; $posting_date = $commission->{'posting-date'}; $website_id = $commission->{'website-id'}; $cid = $commission->{'cid'}; $advertiser_name = $commission->{'advertiser-name'}; $commission_amount = $commission->{'commission-amount'}; $order_discount = $commission->{'order-discount'}; $sid = $commission->{'sid'}; $sale_amount = $commission->{'sale-amount'}; print_r($aid); break; } } ?> The result is : SimpleXMLElement Object ( [0] => 10730981 ) SimpleXMLElement Object ( ) Why is it returning the second object: SimpleXMLElement Object ( ) and what do I need to do correct it? Thanks.

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• Silverlight Cream for April 29, 2010 -- #851

  - by Dave Campbell

  In this Issue: Carlos Figueira(-2-), Subodh Pushpak, Gergely Orosz, John Papa, Mike Snow(-2-), Rishi, Tim Heuer, Stefan Olson, and David Anson. Shoutouts: Josh Holmes blogged about a cool app the City of Miami has up: Miami 311: Built on Windows Azure Gergely Orosz reports on the state of a bug he found pre SL4: Silverlight 4 still displays large elements incorrectly Laura Foy and Charlie Kindel discuss WP7 on Channel 9: Windows Phone 7 Developer Tools Refresh Announced Charlie Kindel has an announcement, good instructions, and what's new notes on the Windows Phone Developer Tools CTP Refresh! Tim Heuer mentioned the workaround for this in his post (below), but I thought you might like to read Brandon Watson's debrief of what it's all about: Signed Assemblies Bug in the Windows Phone Tools CTP Refresh Laurent Bugnion posted about interrelations between versions of Blend and WP7 code... read it closely: Be careful when installing the Blend Windows Phone 7 Add-In From SilverlightCream.com: Consuming REST/POX services in Silverlight 4 Carlos Figueira has a pair of posts up about consuming services in Silverlight 4. This first one is about consuming REST/POX services. He provides a Service Contract that can be used with either and the full project code is available as well. Consuming REST/JSON services in Silverlight 4 In the second post, Carlos Figueira provides the code to allow WCF and Silverlight 4 to consume strongly-typed REST/JSON... and again, all the code is available. Silverlight and WCF caching Subodh Pushpak has a post up discussing caching in WCF, and has code demonstrating turning caching on at run-time. Detecting Silverlight Version Installed Gergely Orosz said it right when he said "Detecting the Silverlight version installed on a client machine isn’t entirely straightforward." ... and after reading this post, if you take the link to his ScottLogic blog, you'll get a full break-out of how it's done. Silverlight TV 22: Tim Heuer on Extending the SMF It's Thursday, and that means Silverlight TV! ... this week, John Papa has on Tim Heuer who has always been out there pushing media... and he's talking about SMF or Silverlight Media Framework for the uninitiated, and also extending it. Silverlight Tip of the Day #7 – Localized Resources Mike Snow has Tip Number 7 up and it's about localization... good end-to-end discussion and demonstration. Just thought I should use that to prove to my daughter that the tatoo she had put on the back of her neck actually reads "Eat More Broccoli" :) Silverlight Tip of the Day #8 – Detecting Alt, Shift, Control, Window & Apple Keys Combinations I just realized Mike Snow's site logo reads "Silverlight Tips of the Day" (bolding mine) ... that answers why I'm seeing more than one -- sorry Mike, couldn't pass it up :) ... Mike's second tip today and number 8 in the series is on detecting all the mouse button and ctl/alt/shift combinations in Silverlight. nRoute: More Wholesomeness, with SL 4 and .NET 4.0 Rishi has a post up announcing a new nRoute release for Silverlight 4 and .NET 4.0 He's tweaked the code to take advantages of enhancements in the new platforms, so check it out. Windows Phone 7 Developer Tools April 2010 Refresh Booya... Tim Heuer announced the release of the next drop in the WP7 tools ... dang wish I was at home today :) ... be sure to read the post for info such as the notes about Authenticode Assemblies and the release notes. Updates to Silverlight Multi-binding support Stefan Olson points up a SL4 change to Multi-binding support that he had previously blogged about. He shows the previous non-working example, and what you have to do to make it work now. Using XAML to create a custom wallpaper image for your mobile device David Anson has a solution for those pesky lost devices, and let me go on the record right now saying if anyone finds a WP7 phone laying around, just call me, it's mine :) [think that'd work??] ... ok, David's solution is a WPF app "MobileDeviceHomeScreenMaker" that you get the info set and it produces a png you then put on your device. But seriously about that lost phone... Stay in the 'Light! Twitter SilverlightNews | Twitter WynApse | WynApse.com | Tagged Posts | SilverlightCream Join me @ SilverlightCream | Phoenix Silverlight User Group Technorati Tags: Silverlight    Silverlight 3    Silverlight 4    Windows Phone MIX10

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• Social Media Talk: Facebook, Really?? How Has It Become This Popular??

  - by david.talamelli

  If you have read some of my previous posts over the past few years either here or on my personal blog David's Journal on Tap you will know I am a Social Media enthusiast. I use various social media sites everday in both my work and personal life. I was surprised to read today on Mashable.com that Facebook now Commands 41% of Social Media Trafic. When I think of the Social Media sites I use most, the sites that jump into my mind first are LinkedIn, Blogging and Twitter. I do use Facebook in both work and in my personal life but on the list of sites I use it probably ranks closer to the bottom of the list rather than the top. I know Facebook is engrained in everything these days - but really I am not a huge Facebook fan - and I am finding that over the past 3-6 months my interest in Facebook is going down rather than up. From a work perspective - SM sites let me connect with candidates and communities and they help me talk about the things that I am doing here at Oracle. From a personal perspective SM sites let me keep in touch with friends and family both here and overseas in a really simple and easy way. Sites like LinkedIn give me a great way to proactively talk to both active and passive candidates. Twitter is fantastic to keep in touch with industry trends and keep up to date on the latest trending topics as well as follow conversations about whatever keyword you want to follow. Blogging lets me share my thoughts and ideas with others and while FB does have some great benefits I don't think the benefits outweigh the negatives of using FB. I use TweetDeck to keep track of my twitter feeds, the latest LinkedIn updates and Facebook updates. Tweetdeck is a great tool as it consolidates these 3 SM sites for me and I can quickly scan to see the latest news on any of them. From what I have seen from Facebook it looks like 70%-80% of people are using FB to grow their farm on farmville, start a mafia war on mafiawars or read their horoscope, check their love percentage, etc...... In between all these "updates" every now and again you do see a real update from someone who actually has something to say but there is so much "white noise" on FB from all the games and apps that is hard to see the real messages from all the 'games' information. I don't like having to scroll through what seems likes pages of farmville updates only to get one real piece of information. For me this is where FB's value really drops off. While I use SM everyday I try to use SM effectively. Sifting through so much noise is not effective and really I am not all that interested in Farmville, MafiaWars or any similar game/app. But what about Groups and Facebook Ads?? Groups are ok, but I am not sure I would call them SM game changers - yes there is a group for everything out there, but a group whether it is on FB or not is only as good as the community that supports and participates in it. Many of the Groups on FB (and elsewhere) are set up and never used or promoted by the moderator. I have heard that FB ads do have an impact, and I have not really looked at them - the question of cost jumps and return on investment comes to my mind though. FB does have some benefits, it is a great way to keep in touch with people and a great way to talk to others. I think it would have been interesting to see a different statistic measuring how effective that 41% of Social Media Traffic via FB really is or is it just a case of more people jumping online to play games. To me FB does not equal SM effectiveness, at the moment it is a tool that I sometimes need to use as opposed to want to use. This article was originally posted on David Talamelli's Blog - David's Journal on Tap

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• SQL SERVER – What is a Technology Evangelist?

  - by pinaldave

  When you hear that someone is an “evangelist” the first thing that might pop into your mind is the Christian church.  In fact, the term did come from Christianity, and basically means someone who spreads the news about their faith.  In the technology world, the same definition is true. Technology evangelists are individuals who, professionally or in their spare time, spread the news about the latest new products.  Sounds like a salesperson, right?  No they are absolutely different. Salespeople also keep up to date with a large number of people, and like to convince others to buy their product – and some will go to any lengths to sell!  An evangelist, on the other hand, is brutally honest about the product, even if sometimes it means not making a sale.  An evangelist is out there to tell the TRUTH.  A salesperson needs to make sales. An Evangelist offers a Solution independent of Technology used – a Salesperson offers Particular Technology. With this definition in mind, you can probably think of a few technology evangelists you already know.  Maybe it’s a relative or a neighbor, someone who loves keeping up with the latest trends and is always willing to tell you about them if you ask even the simplest question.  And, in fact, they probably are evangelists and don’t even know it.  For a long time, the work of technology evangelism was in the hands of community and community technology leaders. Luckily now various organizations have understood the importance of the community and helping community to reach their goals. This has lead them to create role of “Technology Evangelists”. Let me talk about one of the most famous Evangelist of the SQL Server technology. Technology Evangelist only belongs to technology and above any country, race, location or any other thing. They are dedicated to the technology. Vinod Kumar is such a man, who have given a lot to community. For years he was a Technology Evangelist for Microsoft, and maintained a blog that was dedicated to spreading his enthusiasm for his favorite products.  He is one of the most respected Evangelists in the field, and has done a lot of work to define the job for other professionals. Vinod’s career has since progressed to the Microsoft Technology Center (read his post), but he is continuing to be a strong presence in the evangelism community.  I have a lot of respect for Vinod.  He has done a lot for the community and technology evangelism.  Everybody has dream to serve community the way he does, and he is a great role model for evangelists everywhere. On his blog, Vinod created one of the best descriptions of a Technology Evangelist.  It defined the position and also made the distinction between evangelist and salesperson extremely clear.  I will include the highlights of that list here, because no one can say it better than Vinod: Bundle of energy – Passion is their middle name Wonderful Story tellers Empathy, Trust, Loyalty, Openness, Accessibility and Warmth Technology Enthusiast – Doers Love people, people and more people – Community oriented Unique Style and Leadership qualities !!! Self-Confident, Self-Motivated but a student (To read the full list, see: Evangelism Beyond Borders with Evangelists) His blog is a must-read for anyone interested in technology evangelism as a career or simply a hobby.  His advice about how to gain an audience and become a trusted advisor is the best in the business. I think there is an evangelist in everyone. I, too, consider myself a technology evangelist.  Regular readers of this blog will recognize that I am dedicated to bringing information to the masses, and that I pride myself on being both brutally and honest and giving every product fair consideration. I think there is no better way of saying following subject. “Once an Evangelist – Always an Evangelist!” Reference: Pinal Dave (http://blog.SQLAuthority.com)     Filed under: About Me, Database, MVP, Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQLAuthority News, T SQL, Technology Tagged: Evangelist

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• What makes them click ?

  - by Piet

  The other day (well, actually some weeks ago while relaxing at the beach in Kos) I read ‘Neuro Web Design - What makes them click?’ by Susan Weinschenk. (http://neurowebbook.com) The book is a fast and easy read (no unnecessary filler) and a good introduction on how your site’s visitors can be steered in the direction you want them to go. The Obvious The book handles some of the more known/proven techniques, like for example that ratings/testimonials of other people can help sell your product or service. Another well known technique it talks about is inducing a sense of scarcity/urgency in the visitor. Only 2 seats left! Buy now and get 33% off! It’s not because these are known techniques that they stop working. Luckily 2/3rd of the book handles less obvious techniques, otherwise it wouldn’t be worth buying. The Not So Obvious A less known influencing technique is reciprocity. And then I’m not talking about swapping links with another website, but the fact that someone is more likely to do something for you after you did something for them first. The book cites some studies (I always love the facts and figures) and gives some actual examples of how to implement this in your site’s design, which is less obvious when you think about it. Want to know more ? Buy the book! Other interesting sources For a more general introduction to the same principles, I’d suggest ‘Yes! 50 Secrets from the Science of Persuasion’. ‘Yes!…’ cites some of the same studies (it seems there’s a rather limited pool of studies covering this subject), but of course doesn’t show how to implement these techniques in your site’s design. I read ‘Yes!…’ last year, making ‘Neuro Web Design’ just a little bit less interesting. !!!Always make sure you’re able to measure your changes. If you haven’t yet, check out the advanced segmentation in Google Analytics (don’t be afraid because it says ‘beta’, it works just fine) and Google Website Optimizer. Worth Buying? Can I recommend it ? Sure, why not. I think it can be useful for anyone who ever had to think about the design or content of a site. You don’t have to be a marketing guy to want a site you’re involved with to be successful. The content/filler ratio is excellent too: you don’t need to wade through dozens of pages to filter out the interesting bits. (unlike ‘The Design of Sites’, which contains too much useless info and because it’s in dead-tree format, you can’t google it) If you like it, you might also check out ‘Yes! 50 Secrets from the Science of Persuasion’. Tip for people living in Europe: check Amazon UK for your book buying needs. Because of the low UK Pound exchange rate, it’s usually considerably cheaper and faster to get a book delivered to your doorstep by Amazon UK compared to having to order it at the local book store or web-shop.

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• How do you install a USB CD Rom drive?

  - by Matt Allen

  Hello, I recently purchased a USB CD ROM drive, but I don't know how to get it to work with my computer which runs Ubuntu 10.04. http://www.amazon.com/gp/product/B00303H908/ref=oss_product When I issue the lsusb command, it shows up as: Bus 002 Device 016: ID 05e3:0701 Genesys Logic, Inc. USB 2.0 IDE Adapter The computer doesn't recognize it automatically. How can I get this drive to show up as an actual drive on my computer? If this particular drive can't handle Linux, can you recommended one which can and provide a link to it so I can purchase it? Thanks! Update: I was asked by Scaine to run a command and report back with the output: joe@joe-laptop:~$ tail -f /var/log/kern.log Dec 29 12:51:35 joe-laptop kernel: [103190.551437] sr 7:0:0:0: [sr1] Add. Sense: Illegal mode for this track Dec 29 12:51:35 joe-laptop kernel: [103190.551446] sr 7:0:0:0: [sr1] CDB: Read(10): 28 00 00 00 00 00 00 00 02 00 Dec 29 12:51:35 joe-laptop kernel: [103190.551463] end_request: I/O error, dev sr1, sector 0 Dec 29 12:51:35 joe-laptop kernel: [103190.877542] sr 7:0:0:0: [sr1] Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE Dec 29 12:51:35 joe-laptop kernel: [103190.877551] sr 7:0:0:0: [sr1] Sense Key : Illegal Request [current] Dec 29 12:51:35 joe-laptop kernel: [103190.877559] Info fld=0x0, ILI Dec 29 12:51:35 joe-laptop kernel: [103190.877562] sr 7:0:0:0: [sr1] Add. Sense: Illegal mode for this track Dec 29 12:51:35 joe-laptop kernel: [103190.877572] sr 7:0:0:0: [sr1] CDB: Read(10): 28 00 00 00 00 00 00 00 02 00 Dec 29 12:51:35 joe-laptop kernel: [103190.877588] end_request: I/O error, dev sr1, sector 0 Dec 29 13:08:46 joe-laptop kernel: [104221.558911] usb 2-2.2: USB disconnect, address 16 Then when I plugged the drive back into the computer, I got: Dec 29 13:10:29 joe-laptop kernel: [104324.668320] usb 2-2.2: new high speed USB device using ehci_hcd and address 17 Dec 29 13:10:29 joe-laptop kernel: [104324.761702] usb 2-2.2: configuration #1 chosen from 1 choice Dec 29 13:10:29 joe-laptop kernel: [104324.762700] scsi8 : SCSI emulation for USB Mass Storage devices Dec 29 13:10:29 joe-laptop kernel: [104324.762935] usb-storage: device found at 17 Dec 29 13:10:29 joe-laptop kernel: [104324.762938] usb-storage: waiting for device to settle before scanning Dec 29 13:10:34 joe-laptop kernel: [104329.760521] usb-storage: device scan complete Dec 29 13:10:34 joe-laptop kernel: [104329.761344] scsi 8:0:0:0: CD-ROM TEAC CD-224E 1.7A PQ: 0 ANSI: 0 CCS Dec 29 13:10:34 joe-laptop kernel: [104329.767425] sr1: scsi3-mmc drive: 24x/24x cd/rw xa/form2 cdda tray Dec 29 13:10:34 joe-laptop kernel: [104329.767612] sr 8:0:0:0: Attached scsi CD-ROM sr1 Dec 29 13:10:34 joe-laptop kernel: [104329.767720] sr 8:0:0:0: Attached scsi generic sg2 type 5 Dec 29 13:10:34 joe-laptop kernel: [104330.141060] sr 8:0:0:0: [sr1] Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE Dec 29 13:10:34 joe-laptop kernel: [104330.141069] sr 8:0:0:0: [sr1] Sense Key : Illegal Request [current] Dec 29 13:10:34 joe-laptop kernel: [104330.141077] Info fld=0x0, ILI Dec 29 13:10:34 joe-laptop kernel: [104330.141081] sr 8:0:0:0: [sr1] Add. Sense: Illegal mode for this track Dec 29 13:10:34 joe-laptop kernel: [104330.141090] sr 8:0:0:0: [sr1] CDB: Read(10): 28 00 00 00 00 00 00 00 02 00 Dec 29 13:10:34 joe-laptop kernel: [104330.141106] end_request: I/O error, dev sr1, sector 0 Dec 29 13:10:34 joe-laptop kernel: [104330.141113] __ratelimit: 18 callbacks suppressed There was more output than this (the number of lines started growing after the drive was plugged back in, and kept growing), but this is the first few lines.

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• Do We Indeed Have a Future? George Takei on Star Wars.

  - by Bil Simser

  George Takei (rhymes with Okay), probably best known for playing Hikaru Sulu on the original Star Trek, has always had deep concerns for the present and the future. Whether on Earth or among the stars, he has the welfare of humanity very much at heart. I was digging through my old copies of Famous Monsters of Filmland, a great publication on monster and films that I grew up with, and came across this. This was his reaction to STAR WARS from issue 139 of Famous Monsters of Filmland and was written June 6, 1977. It is reprinted here without permission but I hope since the message is still valid to this day and has never been reprinted anywhere, nobody will mind me sharing it. STAR WARS is the most pre-posterously diverting galactic escape and at the same time the most hideously credible portent of the future yet.While I thrilled to the exploits that reminded me of the heroics of Errol Flynn as Robin Hood, Burt Lancaster as the Crimson Pirate and Buster Crabbe as Flash Gordon, I was at the same time aghast at the phantasmagoric violence technology can place at our disposal. STAR WARS raised in my mind the question - do we indeed have a future?It seems to me what George Lucas has done is to masterfully guide us on a journey through space and time and bring us back face to face with today's reality. STAR WARS is more than science fiction, I think it is science fictitious reality.Just yesterday, June 7, 1977, I read that the United States will embark on the production of a neutron bomb - a bomb that will kill people on a gigantic scale but will not destroy buildings. A few days before that, I read that the Pentagon is fearful that the Soviets may have developed a warhead that could neutralize ours that have a capacity for that irrational concept overkill to the nth power. Already, it seems we have the technology to realize the awesome special effects simulations that we saw in the film.The political scene of STAR WARS is that of government by force and power, of revolutions based on some unfathomable grievance, survival through a combination of cunning and luck and success by the harnessing of technology -  a picture not very much at variance from the political headlines that we read today.And most of all, look at the people; both the heroes in the film and the reaction of the audience. First, the heroes; Luke Skywalker is a pretty but easily led youth. Without any real philosophy to guide him, he easily falls under the influence of a mystical old man believed previously to be an eccentric hermit. Recognize a 1960's hippie or a 1970's moonie? Han Solo has a philosophy coupled with courage and skill. His philosophy is money. His proficiency comes for a price - the highest. Solo is a thoroughly avaricious mercenary. And the Princess, a decisive, strong, self-confident and chilly woman. The audience cheered when she wielded a gun. In all three, I missed qualities that could be called humane - love, kindness, yes, I missed sensuality. I also missed a sense of ideals and faith. In this regard the machines seemed more human. They demonstrated real affection for each other and an occasional poutiness. They exhibited a sense of fidelity and constancy. The machines were humanized and the humans conversely seemed mechanical.As a member of the audience, I was swept up by the sheer romantic escapsim of it all. The deering-dos, the rope swing escape across the pit, the ray gun battles and especially the swash buckle with the ray swords. Great fun!But I just hope that we weren't too intoxicated by the escapism to be able to focus on the recognizable. I hope the beauty of the effects didn't narcotize our sensitivity to violence. I hope the people see through the fantastically well done futuristic mirrors to the disquieting reflection of our own society. I hope they enjoy STAR WARS without being "purely entertained".

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• Book Review: Programming Windows Identity Foundation

  - by DigiMortal

  Programming Windows Identity Foundation by Vittorio Bertocci is right now the only serious book about Windows Identity Foundation available. I started using Windows Identity Foundation when I made my first experiments on Windows Azure AppFabric Access Control Service. I wanted to generalize the way how people authenticate theirselves to my systems and AppFabric ACS seemed to me like good point where to start. My first steps trying to get things work opened the door to whole new authentication world for me. As I went through different blog postings and articles to get more information I discovered that the thing I am trying to use is the one I am looking for. As best security API for .NET was found I wanted to know more about it and this is how I found Programming Windows Identity Foundation. What’s inside? Programming WIF focuses on architecture, design and implementation of WIF. I think Vittorio is very good at teaching people because you find no too complex topics from the book. You learn more and more as you read and as a good thing you will find that you can also try out your new knowledge on WIF immediately. After giving good overview about WIF author moves on and introduces how to use WIF in ASP.NET applications. You will get complete picture how WIF integrates to ASP.NET request processing pipeline and how you can control the process by yourself. There are two chapters about ASP.NET. First one is more like introduction and the second one goes deeper and deeper until you have very good idea about how to use ASP.NET and WIF together, what issues you may face and how you can configure and extend WIF. Other two chapters cover using WIF with Windows Communication Foundation (WCF) band   Windows Azure. WCF chapter expects that you know WCF very well. This is not introductory chapter for beginners, this is heavy reading if you are not familiar with WCF. The chapter about Windows Azure describes how to use WIF in cloud applications. Last chapter talks about some future developments of WIF and describer some problems and their solutions. Most interesting part of this chapter is section about Silverlight. Who should read this book? Programming WIF is targeted to developers. It does not matter if you are beginner or old bullet-proof professional – every developer should be able to be read this book with no difficulties. I don’t recommend this book to administrators and project managers because they find almost nothing that is related to their work. I strongly recommend this book to all developers who are interested in modern authentication methods on Microsoft platform. The book is written so well that I almost forgot all things around me when I was reading the book. All additional tools you need are free. There is also Azure AppFabric ACS test version available and you can try it out for free. Table of contents Foreword Acknowledgments Introduction Part I Windows Identity Foundation for Everybody 1 Claims-Based Identity 2 Core ASP.NET Programming Part II Windows Identity Foundation for Identity Developers 3 WIF Processing Pipeline in ASP.NET 4 Advanced ASP.NET Programming 5 WIF and WCF 6 WIF and Windows Azure 7 The Road Ahead Index

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• It’s the thought that counts…

  - by Tony Davis

  I recently finished editing a book called Tribal SQL, and it was a fantastic experience. It’s a community-sourced book written by first-timers. Fifteen previously unpublished authors contributed one chapter each, with the seemingly simple remit to write about “what makes them passionate about working with SQL Server, something that all SQL Server DBAs and developers really need to know”. Sure, some of the writing skills were a bit rusty as one would expect from busy people, but the ideas and energy were sheer nectar. Any seasoned editor can deal easily with the problem of fixing the output of untrained writers. We can handle with the occasional technical error too, which is why we have technical reviewers. The editor’s real job is to hone the clarity and flow of ideas, making the author’s knowledge and experience accessible to as many others as possible. What the writer needs to bring, on the other hand, is enthusiasm, attention to detail, common sense, and a sense of the person behind the writing. If any of these are missing, no editor can fix it. We can see these essential characteristics in many of the more seasoned and widely-published writers about SQL. To illustrate what I mean by enthusiasm, or passion, take a look at the work of Laerte Junior or Fabiano Amorim. Both authors have English as a second language, but their energy, enthusiasm, sheer immersion in a technology and thirst to know more, drives them, with a little editorial help, to produce articles of far more practical value than one can find in the “manuals”. There’s the attention to detail of the likes of Jonathan Kehayias, or Paul Randal. Read their work and one begins to understand the knowledge coupled with incredible rigor, the willingness to bend and test every piece of advice offered to make sure it’s correct, that marks out the very best technical writing. There’s the common sense of someone like Louis Davidson. All writers, including Louis, like to stretch the grey matter of their readers, but some of the most valuable writing is that which takes a complicated idea, or distils years of experience, and expresses it in a way that sounds like simple common sense. There’s personality and humor. Contrary to what you may have been told, they can and do mix well with technical writing, as long as they don’t become a distraction. Read someone like Rodney Landrum, or Phil Factor, for numerous examples of articles that teach hard technical lessons but also make you smile at least twice along the way. Writing well is not easy and it takes a certain bravery to expose your ideas and knowledge for dissection by others, but it doesn’t mean that writing should be the preserve only of those trained in the art, or best left to the MVPs. I believe that Tribal SQL is testament to the fact that if you have passion for what you do, and really know your topic then, with a little editorial help, you can write, and people will learn from what you have to say. You can read a sample chapter, by Mark Rasmussen, in this issue of Simple-Talk and I hope you’ll consider checking out the book (if you needed any further encouragement, it’s also for a good cause, Computers4Africa). Cheers, Tony  

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