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  • Does CSS Positioning Affect SEO [duplicate]

    - by etangins
    This question is an exact duplicate of: Make Offscreen Sliding Content Without Hurting SEO [duplicate] If I positioned the very first content that appears in my code below the fold, would that content be given less weight and therefore be less effective with SEO? In addition, if I had a large image that took up most of the top of the screen and resulting in my content being below the fold or toward the bottom of the screen, would that content be given less weight? Note This is content that occurs early on in my code. I'm not talking about having a ton of content and if the content that occurs later would be given less weight, but if content that occurs early on put ends up below the fold would be given less weight.

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  • Pull network or power? (for contianing a rooted server)

    - by Aleksandr Levchuk
    When a server gets rooted (e.g. a situation like this), one of the first things that you may decide to do is containment. Some security specialists advise not to enter remediation immediately and to keep the server online until forensics are completed. Those advises are usually for APT. It's different if you have occasional Script kiddie breaches. However, you may decide to remediate (fix things) early and one of the steps in remediation is containment of the server. Quoting from Robert Moir's Answer - "disconnect the victim from its muggers". A server can be contained by pulling the network cable or the power cable. Which method is better? Taking into consideration the need for: Protecting victims from further damage Executing successful forensics (Possibly) Protecting valuable data on the server Edit: 5 assumptions Assuming: You detected early: 24 hours. You want to recover early: 3 days of 1 systems admin on the job (forensics and recovery). The server is not a Virtual Machine or a Container able to take a snapshot capturing the contents of the servers memory. You decide not to attempt prosecuting. You suspect that the attacker may be using some form of software (possibly sophisticated) and this software is still running on the server.

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  • Problem with Bibtex

    - by Tim
    Hi, I just wonder why this item not shown properly in bibliography? @misc{Nilsson96introductionto, author = {Nilsson, Nils J.}, citeulike-article-id = {6995464}, howpublished = {\url{http://robotics.stanford.edu/people/nilsson/mlbook.html}}, keywords = {*file-import-10-04-11}, posted-at = {2010-04-11 06:52:28}, priority = {2}, title = {Introduction to Machine Learning: An Early Draft of a Proposed Textbook.}, year = {1996} } [12] Nils J. Nilsson. Introduction to machine learn- ing: An early draft of a proposed textbook. http://robotics.stanford.edu/people/nilsson/mlbook.html, 1996. Thanks and regards!

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  • What are the DB smells?

    - by Jonas Byström
    We all know 'code smells', but what are the fundamental 'database smells'? I'm a DB n00b, but I'll give an example of something that I find fishy. It seems to me like when I have to join 6-8 tables together to optimize our loading that we have a DB smell? Or would that be a pretty 'normal' database layout? (Sure, early optimization is the root of all evil, but this seems to me like early pessimisation, not to mention the cumbersomeness?)

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  • K-nearest neighbour with closed-loop dimensions

    - by Tomas
    Hi, I've got a K-nearest neighbour problem where some of the dimensions are closed loops. For example one is 'time of day' and I'm matching for similarity so 'very early morning' is close to 'late evening', you can't just make it a linear scale from 'very early morning' at one end to 'late evening' at the other. How can I represent this in the data model? Is there an established way to handle this or a way to work around it?

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  • 202 blog articles

    - by mprove
    All my blog articles under blogs.oracle.com since August 2005: 202 blog articles Apr 2012 blogs.oracle.com design patch Mar 2012 Interaction 12 - Critique Mar 2012 Typing. Clicking. Dancing. Feb 2012 Desktop Mobility in Hospitals with Oracle VDI /video Feb 2012 Interaction 12 in Dublin - Highlights of Day 3 Feb 2012 Interaction 12 in Dublin - Highlights of Day 2 Feb 2012 Interaction 12 in Dublin - Highlights of Day 1 Feb 2012 Shit Interaction Designers Say Feb 2012 Tips'n'Tricks for WebCenter #3: How to display custom page titles in Spaces Jan 2012 Tips'n'Tricks for WebCenter #2: How to create an Admin menu in Spaces and save a lot of time Jan 2012 Tips'n'Tricks for WebCenter #1: How to apply custom resources in Spaces Jan 2012 Merry XMas and a Happy 2012! Dec 2011 One Year Oracle SocialChat - The Movie Nov 2011 Frank Ludolph's Last Working Day Nov 2011 Hans Rosling at TED Oct 2011 200 Countries x 200 Years Oct 2011 Blog Aggregation for Desktop Virtualization Oct 2011 Oracle VDI at OOW 2011 Sep 2011 Design for Conversations & Conversations for Design Sep 2011 All Oracle UX Blogs Aug 2011 Farewell Loriot Aug 2011 Oracle VDI 3.3 Overview Aug 2011 Sutherland's Closing Remarks at HyperKult Aug 2011 Surface and Subface Aug 2011 Back to Childhood in UI Design Jul 2011 The Art of Engineering and The Engineering of Art Jul 2011 Oracle VDI Seminar - June-30 Jun 2011 SGD White Paper May 2011 TEDxHamburg Live Feed May 2011 Oracle VDI in 3 Minutes May 2011 Space Ship Earth 2011 May 2011 blog moving times Apr 2011 Frozen tag cloud Apr 2011 Oracle: Hardware Software Complete in 1953 Apr 2011 Interaction Design with Wireframes Apr 2011 A guide to closing down a project Feb 2011 Oracle VDI 3.2.2 Jan 2011 free VDI charts Jan 2011 Sun Founders Panel 2006 Dec 2010 Sutherland on Leadership Dec 2010 SocialChat: Efficiency of E20 Dec 2010 ALWAYS ON Desktop Virtualization Nov 2010 12,000 Desktops at JavaOne Nov 2010 SocialChat on Sharing Best Practices Oct 2010 Globe of Visitors Oct 2010 SocialChat about the Next Big Thing Oct 2010 Oracle VDI UX Story - Wireframes Oct 2010 What's a PC anyway? Oct 2010 SocialChat on Getting Things Done Oct 2010 SocialChat on Infoglut Oct 2010 IT Twenty Twenty Oct 2010 Desktop Virtualization Webcasts from OOW Oct 2010 Oracle VDI 3.2 Overview Sep 2010 Blog Usability Top 7 Sep 2010 100 and counting Aug 2010 Oracle'izing the VDI Blogs Aug 2010 SocialChat on Apple Aug 2010 SocialChat on Video Conferencing Aug 2010 Oracle VDI 3.2 - Features and Screenshots Aug 2010 SocialChat: Don't stop making waves Aug 2010 SocialChat: Giving Back to the Community Aug 2010 SocialChat on Learning in Meetings Aug 2010 iPAD's Natural User Interface Jul 2010 Last day for Sun Microsystems GmbH Jun 2010 SirValUse Celebration Snippets Jun 2010 10 years SirValUse - Happy Birthday! Jun 2010 Wim on Virtualization May 2010 New Home for Oracle VDI Apr 2010 Renaissance Slide Sorter Comments Apr 2010 Unboxing Sun Ray 3 Plus Apr 2010 Desktop Virtualisierung mit Sun VDI 3.1 Apr 2010 Blog Relaunch Mar 2010 Social Messaging Slides from CeBIT Mar 2010 Social Messaging Talk at CeBIT Feb 2010 Welcome Oracle Jan 2010 My last presentation at Sun Jan 2010 Ivan Sutherland on Leadership Jan 2010 Learning French with Sun VDI Jan 2010 Learning Danish with Sun Ray Jan 2010 VDI workshop in Nieuwegein Jan 2010 Happy New Year 2010 Jan 2010 On Creating Slides Dec 2009 Best VDI Ever Nov 2009 How to store the Big Bang Nov 2009 Social Enterprise Tools. Beipiel Sun. Nov 2009 Nov-19 Nov 2009 PDF and ODF links on your blog Nov 2009 Q&A on VDI and MySQL Cluster Nov 2009 Zürich next week: Swiss Intranet Summit 09 Nov 2009 Designing for a Sustainable World - World Usabiltiy Day, Nov-12 Nov 2009 How to export a desktop from VDI 3 Nov 2009 Virtualisation Roadshow in the UK Nov 2009 Project Wonderland at EDUCAUSE 09 Nov 2009 VDI Roadshow in Dublin, Nov-26, 2009 Nov 2009 Sun VDI at EDUCAUSE 09 Nov 2009 Sun VDI 3.1 Architecture and New Features Oct 2009 VDI 3.1 is Early-Access Sep 2009 Virtualization for MySQL on VMware Sep 2009 Silpion & 13. Stock Sommerparty Sep 2009 Sun Ray and VMware View 3.1.1 2009-08-31 New Set of Sun Ray Status Icons 2009-08-25 Virtualizing the VDI Core? 2009-08-23 World Usability Day Hamburg 2009 - CfP 2009-07-16 Rising Sun 2009-07-15 featuring twittermeme 2009-06-19 ISC09 Student Party on June-20 /Hamburg 2009-06-18 Before and behind the curtain of JavaOne 2009-06-09 20k desktops at JavaOne 2009-06-01 sweet microblogging 2009-05-25 VDI 3 - Why you need 3 VDI hosts and what you can do about that? 2009-05-21 IA Konferenz 2009 2009-05-20 Sun VDI 3 UX Story - Power of the Web 2009-05-06 Planet of Sun and Oracle User Experience Design 2009-04-22 Sun VDI 3 UX Story - User Research 2009-04-08 Sun VDI 3 UX Story - Concept Workshops 2009-04-06 Localized documentation for Sun Ray Connector for VMware View Manager 1.1 2009-04-03 Sun VDI 3 Press Release 2009-03-25 Sun VDI 3 launches today! 2009-03-25 Sun Ray Connector for VMware View Manager 1.1 Update 2009-03-11 desktop virtualization wiki relaunch 2009-03-06 VDI 3 at CeBIT hall 6, booth E36 2009-03-02 Keyboard layout problems with Sun Ray Connector for VMware VDM 2009-02-23 wikis.sun.com tips & tricks 2009-02-23 Sun VDI 3 is in Early Access 2009-02-09 VirtualCenter unable to decrypt passwords 2009-02-02 Sun & VMware Desktop Training 2009-01-30 VDI at next09? 2009-01-16 Sun VDI: How to use virtual machines with multiple network adapters 2009-01-07 Sun Ray and VMware View 2009-01-07 Hamburg World Usability Day 2008 - Webcasts 2009-01-06 Sun Ray Connector for VMware VDM slides 2008-12-15 mother of all demos 2008-12-08 Build your own Thumper 2008-12-03 Troubleshooting Sun Ray Connector for VMware VDM 2008-12-02 My Roller Tag Cloud 2008-11-28 Sun Ray Connector: SSL connection to VDM 2008-11-25 Setting up SSL and Sun Ray Connector for VMware VDM 2008-11-13 Inspiration for Today and Tomorrow 2008-10-23 Sun Ray Connector for VMware VDM released 2008-10-14 From Sketchpad to ILoveSketch 2008-10-09 Desktop Virtualization on Xing 2008-10-06 User Experience Forum on Xing 2008-10-06 Sun Ray Connector for VMware VDM certified 2008-09-17 Virtual Clouds over Las Vegas 2008-09-14 Bill Verplank sketches metaphors 2008-09-04 End of Early Access - Sun Ray Connector for VMware 2008-08-27 Early Access: Sun Ray Connector for VMware Virtual Desktop Manager 2008-08-12 Sun Virtual Desktop Connector - Insides on Recycling Part 2 2008-07-20 Sun Virtual Desktop Connector - Insides on Recycling Part 3 2008-07-20 Sun Virtual Desktop Connector - Insides on Recycling 2008-07-20 lost in wiki space 2008-07-07 Evolution of the Desktop 2008-06-17 Virtual Desktop Webcast 2008-06-16 Woodstock 2008-06-16 What's a Desktop PC anyway? 2008-06-09 Virtual-T-Box 2008-06-05 Virtualization Glossary 2008-05-06 Five User Experience Principles 2008-04-25 Virtualization News Feed 2008-04-21 Acetylcholinesterase - Second Season 2008-04-18 Acetylcholinesterase - End of Signal 2007-12-31 Produkt-Management ist... 2007-10-22 Usability Verbände, Verteiler und Netzwerke. 2007-10-02 The Meaning is the Message 2007-09-28 Visualization Methods 2007-09-10 Inhouse und Open Source Projekte – Usability verankern und Synergien nutzen 2007-09-03 Der Schwabe Darth Vader entdeckt das Virale Marketing 2007-08-29 Dick Hardt 3.0 on Identity 2.0 2007-08-27 quality of written text depends on the tool 2007-07-27 podcasts for reboot9 2007-06-04 It is the user's itch that need to be scratched 2007-05-25 A duel at reboot9 2007-05-14 Taxonomien und Folksonomien - Tagging als neues HCI-Element 2007-05-10 Dueling Interaction Models of Personal-Computing and Web-Computing 2007-03-01 22.März: Weizenbaum. Rebel at Work. /Filmpremiere Hamburg 2007-02-25 Bruce Sterling at UbiComp 2006 /webcast 2006-11-12 FSOSS 2006 /webcasts 2006-11-10 Highway 101 2006-11-09 User Experience Roundtable Hamburg: EuroGEL 2006 2006-11-08 Douglas Adams' Hyperland (BBC 1990) 2006-10-08 Taxonomien und Folksonomien – Tagging als neues HCI-Element 2006-09-13 Usability im Unternehmen 2006-09-13 Doug does HyperScope 2006-08-26 TED Talks and TechTalks 2006-08-21 Kai Krause über seine Freundschaft zu Douglas Adams 2006-07-20 Rebel At Work: Film Portrait on Weizenbaum 2006-07-04 Gabriele Fischer, mp3 2006-06-07 Dick Hardt at ETech 06 2006-06-05 Weinberger: From Control to Conversation 2006-04-16 Eye Tracking at User Experience Roundtable Hamburg 2006-04-14 dropping knowledge 2006-04-09 GEL 2005 2006-03-13 slide photos of reboot7 2006-03-04 Dick Hardt on Identity 2.0 2006-02-28 User Experience Newsletter #13: Versioning 2006-02-03 Ester Dyson on Choice and Happyness 2006-02-02 Requirements-Engineering im Spannungsfeld von Individual- und Produktsoftware 2006-01-15 User Experience Newsletter #12: Intuition Quiz 2005-11-30 User Experience und Requirements-Engineering für Software-Projekte 2005-10-31 Ivan Sutherland on "Research and Fun" 2005-10-18 Ars Electronica / Mensch und Computer 2005 2005-09-14 60 Jahre nach Memex: Über die Unvereinbarkeit von Desktop- und Web-Paradigma 2005-08-31 reboot 7 2005-06-30

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  • TechEd 2010 Day One – How I Travel

    - by BuckWoody
    Normally when I blog on the first day of a conference, well, there hasn’t been a first day yet. So I talk about the value of a conference or some other facet. And normally in my (non-conference) blogs, I show you how I have learned to be a data professional – things I’ve learned how to do over the years. But in all that time, I don’t think I’ve ever talked about a big part of my job – traveling. I’ve traveled a lot throughout the years, when I’ve taught, gone to conferences, consulted and in my current role assisting Microsoft customers with large-scale database system designs.  So I’ll share a few thoughts about what I do. Keep in mind that I travel for short durations, just a day or so, and sometimes I travel internationally. For those I prepare differently – what I’m talking about here is what I do for a multi-day, same-country trip. Hopefully you find it useful. I’ll tag a few other travelers I know to add their thoughts.  Preparing for Travel   When I’m notified of a trip, I begin researching the location. I find the flights, hotel and (if I have to) a car to use while I’m away. We have an in-house system we use to book the travel, but when I travel not-for-Microsoft I use Expedia and Kayak to find what I need.  Traveling on Sunday and Friday is the worst. I have to do it sometimes (like this week) and it’s always a bad idea. But you can blunt the impact by booking as early as you can stand it. That means I have to be up super-early, but the flights are normally on time. I stay flexible, and always have a backup plan in case the flights are delayed or canceled.  For the hotel, I tend to go on the cheaper side, and I look for older hotels that have been renovated, or quirky ones. For instance, in Boise, ID recently I stayed at a 60’s-themed (think Mad-Men) hotel that was very cool. Always I go on the less expensive side – I find the “luxury” hotels nail me for Internet, food, everything. The cheaper places include all kinds of things, and even have breakfasts, shuttles and all kinds of things that start to add up. I even call ahead to make sure there’s an iron and ironing board available, since I’ll need those when I get there.  I find any way I can not to get a car. I use mass-transit wherever possible, and try to make friends and pay their gas to take me places. In a pinch, I’ll use a taxi. It ends up being cheaper, faster, and less stressful all around.  Packing  Over the years I’ve learned never to check luggage whenever I can. To do that, I lay out everything I want to take with me on the bed, and then try and make sure I’m really going to use it. I wear a dark wool set of pants, which I can clean and wear in hot and cold climates. I bring undies and socks of course, and for most places I have to wear “dress up” shirts. I bring at least two print T-Shirts in case I want to dress down for something while I’m gone, but I only bring one set of shoes. All the  clothes are rolled as tightly as possible as I learned in the military. Then I use those to cushion the electronics I take.  For toiletries I bring a shaver, toothpaste and toothbrush, D/O and a small brush. Everything else the hotel will provide.  For entertainment, I take a small Zune, a full PC-Headset (so I can make IP calls on the road) and my laptop. I don’t take books or anything else – everything is electronic. I use E-books (downloaded from our Library), Audio-Books (on the Zune) and I also bring along a Kaossilator (more here) to play music in the hotel room or even on the plane without being heard.  If I can, I pack into one roll-on bag. There’s not a lot better than this one, but I also have a Bag I was given as a prize for something or other here at Microsoft. Either way, I like something with less pockets and more big, open compartments. Everything gets rolled up and packed in, with all of the wires and charges in small bags my wife made for me. The laptop (and anything I don’t want gate-checked) goes on top or in an outside pouch so I can grab it quickly if I have to gate-check the bag. As much as I can, I try to go in one bag. When I can’t (like this week) I use this bag since it can expand, roll up, crush and even be put away later. It’s super-heavy canvas and worth the price. This allows me to not check a bag.  Journey Logistics The day of the trip, I have everything ready since I’m getting up early. I pack a few small snacks inside a plastic large-mouth water bottle, which protects the snacks and lets me get water in the terminal. I bring along those little powdered drink mixes to add to the water.  At the airport, I make a beeline for the power-outlets. I charge up my laptop and phone, and download all my e-mails so I can work on them off-line in the air. I don’t travel as often as I used to – just every month or so now, so I don’t have a membership to an airline club. If I travel much more, I’ll invest in one again – they are WELL worth the money, for the wifi, food and quiet if for nothing else.  I print out my logistics on paper and put that in my pocket – flight numbers, hotel addresses and phones for everything. That way if I have to make a change, I don’t have to boot up anything or even have power to be able to roll with the punches if things change.  Working While Away  While I’m away I realize I’m going to be swamped with things at the conference or with my clients. So I turn on Out-Of-Office notifications to let people know I won’t be as responsive, and I keep my Outlook calendar up to date so my co-workers know what I’m up to. I even update it with hotel and phone info in case they really need to reach me. I share my calendar with my wife so my family knows what I’m doing as well.  I check my e-mail during breaks, but I only respond to them in the evening or early morning at the hotel. I tweet during conferences. The point is to be as present as possible during the event or when I’m at the clients. Both deserve it.  So those are my initial thoughts. I’ll tag Brent Ozar, Brad McGeHee and Paul Randal, and they can tag whomever they wish. Share this post: email it! | bookmark it! | digg it! | reddit! | kick it! | live it!

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  • Rockmelt, the technology adoption model, and Facebook's spare internet

    - by Roger Hart
    Regardless of how good it is, you'd have to have a heart of stone not to make snide remarks about Rockmelt. After all, on the surface it looks a lot like some people spent two years building a browser instead of just bashing out a Chrome extension over a wet weekend. It probably does some more stuff. I don't know for sure because artificial scarcity is cool, apparently, so the "invitation" is still in the post*. I may in fact never know for sure, because I'm not wild about Facebook sign-in as a prerequisite for anything. From the video, and some initial reviews, my early reaction was: I have a browser, I have a Twitter client; what on earth is this for? The answer, of course, is "not me". Rockmelt is, in a way, quite audacious. Oh, sure, on launch day it's Bay Area bar-chat for the kids with no lenses in their retro specs and trousers that give you deep-vein thrombosis, but it's not really about them. Likewise,  Facebook just launched Google Wave, or something. And all the tech snobbery and scorn packed into describing it that way is irrelevant next to what they're doing with their platform. Here's something I drew in MS Paint** because I don't want to get sued: (see: The technology adoption lifecycle) A while ago in the Guardian, John Lanchester dusted off the idiom that "technology is stuff that doesn't work yet". The rest of the article would be quite interesting if it wasn't largely about MySpace, and he's sort of got a point. If you bolt on the sentiment that risk-averse businessmen like things that work, you've got the essence of Crossing the Chasm. Products for the mainstream market don't look much like technology. Think for  a second about early (1980s ish) hi-fi systems, with all the knobs and fiddly bits, their ostentatious technophile aesthetic. Then consider their sleeker and less (or at least less conspicuously) functional successors in the 1990s. The theory goes that innovators and early adopters like technology, it's a hobby in itself. The rest of the humans seem to like magic boxes with very few buttons that make stuff happen and never trouble them about why. Personally, I consider Apple's maddening insistence that iTunes is an acceptable way to move files around to be more or less morally unacceptable. Most people couldn't care less. Hence Rockmelt, and hence Facebook's continued growth. Rockmelt looks pointless to me, because I aggregate my social gubbins with Digsby, or use TweetDeck. But my use case is different and so are my enthusiasms. If I want to share photos, I'll use Flickr - but Facebook has photo sharing. If I want a short broadcast message, I'll use Twitter - Facebook has status updates. If I want to sell something with relatively little hassle, there's eBay - or Facebook marketplace. YouTube - check, FB Video. Email - messaging. Calendaring apps, yeah there are loads, or FB Events. What if I want to host a simple web page? Sure, they've got pages. Also Notes for blogging, and more games than I can count. This stuff is right there, where millions and millions of users are already, and for what they need it just works. It's not about me, because I'm not in the big juicy area under the curve. It's what 1990s portal sites could never have dreamed of achieving. Facebook is AOL on speed, crack, and some designer drugs it had specially imported from the future. It's a n00b-friendly gateway to the internet that just happens to serve up all the things you want to do online, right where you are. Oh, and everybody else is there too. The price of having all this and the social graph too is that you have all of this, and the social graph too. But plenty of folks have more incisive things to say than me about the whole privacy shebang, and it's not really what I'm talking about. Facebook is maintaining a vast, and fairly fully-featured training-wheels internet. And it makes up a large proportion of the online experience for a lot of people***. It's the entire web (2.0?) experience for the early and late majority. And sure, no individual bit of it is quite as slick or as fully-realised as something like Flickr (which wows me a bit every time I use it. Those guys are good at the web), but it doesn't have to be. It has to be unobtrusively good enough for the regular humans. It has to not feel like technology. This is what Rockmelt sort of is. You're online, you want something nebulously social, and you don't want to faff about with, say, Twitter clients. Wow! There it is on a really distracting sidebar, right in your browser. No effort! Yeah - fish nor fowl, much? It might work, I guess. There may be a demographic who want their social web experience more simply than tech tinkering, and who aren't just getting it from Facebook (or, for that matter, mobile devices). But I'd be surprised. Rockmelt feels like an attempt to grab a slice of Facebook-style "Look! It's right here, where you already are!", but it's still asking the mature market to install a new browser. Presumably this is where that Facebook sign-in predicate comes in handy, though it'll take some potent awareness marketing to make it fly. Meanwhile, Facebook quietly has the entire rest of the internet as a product management resource, and can continue to give most of the people most of what they want. Something that has not gone un-noticed in its potential to look a little sinister. But heck, they might even make Google Wave popular.     *This was true last week when I drafted this post. I got an invite subsequently, hence the screenshot. **MS Paint is no fun any more. It's actually good in Windows 7. Farewell ironically-shonky diagrams. *** It's also behind a single sign-in, lending a veneer of confidence, and partially solving the problem of usernames being crummy unique identifiers. I'll be blogging about that at some point.

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  • Premature-Optimization and Performance Anxiety

    - by James Michael Hare
    While writing my post analyzing the new .NET 4 ConcurrentDictionary class (here), I fell into one of the classic blunders that I myself always love to warn about.  After analyzing the differences of time between a Dictionary with locking versus the new ConcurrentDictionary class, I noted that the ConcurrentDictionary was faster with read-heavy multi-threaded operations.  Then, I made the classic blunder of thinking that because the original Dictionary with locking was faster for those write-heavy uses, it was the best choice for those types of tasks.  In short, I fell into the premature-optimization anti-pattern. Basically, the premature-optimization anti-pattern is when a developer is coding very early for a perceived (whether rightly-or-wrongly) performance gain and sacrificing good design and maintainability in the process.  At best, the performance gains are usually negligible and at worst, can either negatively impact performance, or can degrade maintainability so much that time to market suffers or the code becomes very fragile due to the complexity. Keep in mind the distinction above.  I'm not talking about valid performance decisions.  There are decisions one should make when designing and writing an application that are valid performance decisions.  Examples of this are knowing the best data structures for a given situation (Dictionary versus List, for example) and choosing performance algorithms (linear search vs. binary search).  But these in my mind are macro optimizations.  The error is not in deciding to use a better data structure or algorithm, the anti-pattern as stated above is when you attempt to over-optimize early on in such a way that it sacrifices maintainability. In my case, I was actually considering trading the safety and maintainability gains of the ConcurrentDictionary (no locking required) for a slight performance gain by using the Dictionary with locking.  This would have been a mistake as I would be trading maintainability (ConcurrentDictionary requires no locking which helps readability) and safety (ConcurrentDictionary is safe for iteration even while being modified and you don't risk the developer locking incorrectly) -- and I fell for it even when I knew to watch out for it.  I think in my case, and it may be true for others as well, a large part of it was due to the time I was trained as a developer.  I began college in in the 90s when C and C++ was king and hardware speed and memory were still relatively priceless commodities and not to be squandered.  In those days, using a long instead of a short could waste precious resources, and as such, we were taught to try to minimize space and favor performance.  This is why in many cases such early code-bases were very hard to maintain.  I don't know how many times I heard back then to avoid too many function calls because of the overhead -- and in fact just last year I heard a new hire in the company where I work declare that she didn't want to refactor a long method because of function call overhead.  Now back then, that may have been a valid concern, but with today's modern hardware even if you're calling a trivial method in an extremely tight loop (which chances are the JIT compiler would optimize anyway) the results of removing method calls to speed up performance are negligible for the great majority of applications.  Now, obviously, there are those coding applications where speed is absolutely king (for example drivers, computer games, operating systems) where such sacrifices may be made.  But I would strongly advice against such optimization because of it's cost.  Many folks that are performing an optimization think it's always a win-win.  That they're simply adding speed to the application, what could possibly be wrong with that?  What they don't realize is the cost of their choice.  For every piece of straight-forward code that you obfuscate with performance enhancements, you risk the introduction of bugs in the long term technical debt of the application.  It will become so fragile over time that maintenance will become a nightmare.  I've seen such applications in places I have worked.  There are times I've seen applications where the designer was so obsessed with performance that they even designed their own memory management system for their application to try to squeeze out every ounce of performance.  Unfortunately, the application stability often suffers as a result and it is very difficult for anyone other than the original designer to maintain. I've even seen this recently where I heard a C++ developer bemoaning that in VS2010 the iterators are about twice as slow as they used to be because Microsoft added range checking (probably as part of the 0x standard implementation).  To me this was almost a joke.  Twice as slow sounds bad, but it almost never as bad as you think -- especially if you're gaining safety.  The only time twice is really that much slower is when once was too slow to begin with.  Think about it.  2 minutes is slow as a response time because 1 minute is slow.  But if an iterator takes 1 microsecond to move one position and a new, safer iterator takes 2 microseconds, this is trivial!  The only way you'd ever really notice this would be in iterating a collection just for the sake of iterating (i.e. no other operations).  To my mind, the added safety makes the extra time worth it. Always favor safety and maintainability when you can.  I know it can be a hard habit to break, especially if you started out your career early or in a language such as C where they are very performance conscious.  But in reality, these type of micro-optimizations only end up hurting you in the long run. Remember the two laws of optimization.  I'm not sure where I first heard these, but they are so true: For beginners: Do not optimize. For experts: Do not optimize yet. This is so true.  If you're a beginner, resist the urge to optimize at all costs.  And if you are an expert, delay that decision.  As long as you have chosen the right data structures and algorithms for your task, your performance will probably be more than sufficient.  Chances are it will be network, database, or disk hits that will be your slow-down, not your code.  As they say, 98% of your code's bottleneck is in 2% of your code so premature-optimization may add maintenance and safety debt that won't have any measurable impact.  Instead, code for maintainability and safety, and then, and only then, when you find a true bottleneck, then you should go back and optimize further.

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  • St. Louis ALT.NET

    - by Brian Schroer
    I’m a huge fan of the St. Louis .NET User Group and a regular attendee of their meetings, but always wished there was a local group that discussed more advanced .NET topics. (That’s not a criticism of the group - I appreciate that they want to server developers with a broad range of skill levels). That’s why I was thrilled when Nicholas Cloud started a St. Louis ALT.NET group in 2010. Here’s the “about us” statement from the group’s web site: The ALT.NET community is a loosely coupled, highly cohesive group of like-minded individuals who believe that the best developers do not align themselves with platforms and languages, but with principles and ideas. In 2007, David Laribee created the term "ALT.NET" to explain this "alternative" view of the Microsoft development universe--a view that challenged the "Microsoft-only" approach to software development. He distilled his thoughts into four key developer characteristics which form the basis of the ALT.NET philosophy: You're the type of developer who uses what works while keeping an eye out for a better way. You reach outside the mainstream to adopt the best of any community: Open Source, Agile, Java, Ruby, etc. You're not content with the status quo. Things can always be better expressed, more elegant and simple, more mutable, higher quality, etc. You know tools are great, but they only take you so far. It's the principles and knowledge that really matter. The best tools are those that embed the knowledge and encourage the principles (e.g. Resharper.) The St. Louis ALT.NET meetup group is a place where .NET developers can learn, share, and critique approaches to software development on the .NET stack. We cater to the highest common denominator, not the lowest, and want to help all St. Louis .NET developers achieve a superior level of software craftsmanship. I don’t see a lot of ALT.NET talk in blogs these days. The movement was harmed early on by the negative attitudes of some of its early leaders, including jerk moves like the Entity Framework “vote of no confidence”, but I do see occasional mentions of local groups like the St. Louis one. I think ALT.NET has been successful at bringing some of its ideas into the .NET world, including heavily influencing ASP.NET MVC and raising the general level of software craftsmanship for developers working on the Microsoft stack. The ideas and ideals live on, they’re just not branded as “this is ALT.NET!” In the past 18 months, St. Louis ALT.NET meetups have discussed topics like: NHibernate F# and other functional languages AOP CoffeeScript “How Ruby Is Making Me a Stronger C# Developer” Using rake for builds CQRS .NET dynamic programming micro web frameworks – Nancy & Jessica Git ALT.NET doesn’t mean (to me, anyway) “alternatives to .NET”, but “alternatives for .NET”. We look at how things are done in Ruby and other languages/platforms, but always with the idea “What can I learn from this to take back to my “day job” with .NET?”. Meetings are held at 7PM on the fourth Wednesday of each month at the offices of Professional Employment Group. PEG is located at 999 Executive Parkway (Suite 100 – lower level) in Creve Coeur (South of Olive off of Mason Road - Here's a map). Food is not supplied (sorry if you’re a big fan of the Papa John’s Crust-Lovers’ Pizza that’s a staple of user group meetings), but attendees are encouraged to come early and bring/share beer, so that’s cool. Thanks to Nick for organizing, and to Professional Employment Group for lending their offices. Please visit the meetup site for more information.

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  • Oracle OpenWorld 2012: The Best Just Gets Better

    - by kellsey.ruppel
    For almost 30 years, Oracle OpenWorld has been the world's premier learning event for Oracle customers, developers, and partners. With more than 2,000 sessions providing best practices; demos; tips and tricks; and product insight from Oracle, customers, partners, and industry experts, Oracle OpenWorld provides more educational and networking opportunities than any other event in the world. 2011 Facts Attendees from 117 Countries Used Filtered Tap Water to Eliminate 22 Tons of Plastic Bottles Diverted Enough Trash to Fill 37 Dump Trucks 45,000+ Total Registered Attendees Oracle OpenWorld 2012: The Best Just Gets Better What's New? What's Different?  This year Oracle OpenWorld will include the Executive Edge @ OpenWorld (replacing Leaders Circle), the Customer Experience Summit @ OpenWorld, JavaOne, MySQL Connect, and the expanded Oracle PartnerNetwork Exchange @ OpenWorld. More than 50,000 customers and partners will attend OpenWorld to see Oracle's newest hardware and software products at work, and learn more about our server and storage, database, middleware, industry, and applications solutions.  New This Year: The Executive Edge @ Oracle OpenWorld (Oct 1 - 2) New at Oracle OpenWorld this year, the Executive Edge @ OpenWorld (replacing Leaders Circle) will bring together customer, partner and Oracle executives for two days of keynote presentations, summits targeted to customer industries and organizational roles, roundtable discussions, and great new networking opportunities. The Customer Experience Revolution Is Here!Customer Experience Summit @ Oracle OpenWorld (Oct 3 - 5) This dynamic new program offers more than 60 keynotes, roundtables and networking sessions exploring trends, innovations and best practices to help companies succeed with a customer experience-driven business strategy.  All Things Java -- JavaOne (Sep 30 - Oct 4) JavaOne is the world's most important event for the Java developer community. Technical sessions cover topics that span the breadth of the Java universe, with keynotes from the foremost Java visionaries and expert-led hands-on learning opportunities.  Are you innovating with Oracle Fusion Middleware?  If you are, then you need to know that the Call for Nominations for the 2012 Oracle Fusion Middleware Innovation Awards is open now through July 17, 2012. Jointly sponsored by Oracle, AUSOUG, IOUG, OAUG, ODTUG, QUEST, and UKOUG, the Oracle Fusion Middleware Innovation Awards honor organizations creatively using Oracle Fusion Middleware to deliver unique value to their enterprise.  Winning customers and partners will be hosted at Oracle OpenWorld 2012, where they can connect with Oracle executives, network with peers, and be featured in an upcoming edition of Oracle Magazine. Be sure to submit your WebCenter use case today! Oracle Music Festival his year, the first-ever Oracle Music Festival will debut, running from September 30 to October 4. In the tradition of great live music events like Coachella and SXSW, the streets of San Francisco—from 7:00 p.m. to 1:00 a.m. for five nights-into-days—will vibrate with the music of some of today’s hottest name acts, emerging and local bands, and scratching DJs. Outdoor venues and clubs near Moscone Center and the Zone (including 111 Minna, DNA, Mezzanine, Roe, Ruby Skye, Slim’s, the Taylor Street Café, Temple, Union Square, and Yerba Buena Gardens) will showcase acts that range from reggae to rock, punk to ska, R&B to country, indie to honky-tonk. After a full day of sessions and networking, you'll be primed for some late-night relaxation and rocking out at one or more of these sets.  Please note that with awesome acts, thousands of music devotees, and a limited number of venues each night, access to Festival events is on a first-come, first-served basis. Join us at the Oracle Music Festival--it's going to be epic! Save $500 on Registration with Early Bird Pricing Early Bird pricing ends July 13! Save up to $500 on registration fees by registering by Friday. Will you be attending Oracle OpenWorld 2012? We hope to see you there! Be sure to follow @oraclewebcenter on Twitter for more information and use hashtags #webcenter and #oow!

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  • 2014 Conferences - JFokus, JavaLand & GeeCon!

    - by Heather VanCura
    There has been a delay in publishing these past event summaries from early 2014--JFokus in February, JavaLand in March, and GeeCon in May. As we plan for Devoxx UK next week, I found these summaries that did not make it past 'draft' stage.  We had some great successes with the first three events of 2014, a Java developer conference trifecta! Participation topics included Java, the JCP program overall and the Adopt-a-JSR programs.   First up in February was JFokus in Stockholm. The energy and talent in Stockholm is amazing and the conference organizers do a stellar job running it and welcoming the speakers of this event.  I enjoyed the city walk and speaker dinner, as well as many opportunities to interact with conference speakers and attendees, both during and after the conference hours. Reza Rehman invited me to speak during his Java EE 7 lab session about the Adopt-a-JSR program, and I gave a quickie session on the JCP and Adopt-a-JSR.  There was also a late night Birds of a Feather (BoF) session held jointly with Cecelia Borg, Martijn Verburg and Reza Rehman.  This was an interactive conversation with a focus on the Java EE community survey results and encouraging more community participation and collaboration in Java development.  The Java 8 keynote by Georges Saab and Mark Reinhold was also very entertaining,  I was sorry to miss FOSDEM happening the previous weekend this year in Brussels, but I hope to attend in 2015.  Favorite take home gift -- Lambdas cap! In March, the inaugural version of the JavaLand conference happened inside Phantasialand, an amusement park in Germany. Markus Eisele suggested having an Early Adopters area at the conference, which I was keen to implement. In 2013 at Devoxx Belgium we held some activities in the Hackergaren area around Lambdas and Java EE 7, so this was a great opportunity to expand on a more interactive conference format and Andreas Badelt from the program committee helped in the planning for this area.  Daniel Bryant and Mani Sarkar from the London Java Community led some general Adopt-a-JSR discussions and AdoptOpen JDK activities.  JCP Spec Leads, Anatole Tresch from Credit Suisse, leading JSR 354, Money & Currency API, and Ed Burns from Oracle, leading JSR 344, JavaServer Faces 2.2, attended to engage with conference attendees on their JSRs.  Favorite - Stephen Chin's roller coaster video. In May, GeeCon in Krakow was anther awesome conference!  The conference organizers were warm and welcoming and I enjoyed time getting to know the other speakers at the event. There was a JCP and Adopt-a-JSR participation session as well as a moderated panel session on Early Adopters.  We had an amazing panel -- Daniel Bryant, Arun Gupta, Tomasz Borek , and Peter Lawrey. The panel discussed the Adopt-a-JSR and Adopt OpenJDK program, and how the participants work together to get involved and contribute to both the Java SE and Java EE platforms.  If was an interesting discussion and sparked some new ideas on how Java User Groups in Poland and around the world can contribute in a significant and meaningful way to create better and more practical Java standards today and in the future.  Favorite take home gift - GeeCon mug!   These were some of the highlights of the events--looking forward to Devoxx UK next week.  I will publish these details tomorrow!

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  • An Actionable Common Approach to Federal Enterprise Architecture

    - by TedMcLaughlan
    The recent “Common Approach to Federal Enterprise Architecture” (US Executive Office of the President, May 2 2012) is extremely timely and well-organized guidance for the Federal IT investment and deployment community, as useful for Federal Departments and Agencies as it is for their stakeholders and integration partners. The guidance not only helps IT Program Planners and Managers, but also informs and prepares constituents who may be the beneficiaries or otherwise impacted by the investment. The FEA Common Approach extends from and builds on the rapidly-maturing Federal Enterprise Architecture Framework (FEAF) and its associated artifacts and standards, already included to a large degree in the annual Federal Portfolio and Investment Management processes – for example the OMB’s Exhibit 300 (i.e. Business Case justification for IT investments).A very interesting element of this Approach includes the very necessary guidance for actually using an Enterprise Architecture (EA) and/or its collateral – good guidance for any organization charged with maintaining a broad portfolio of IT investments. The associated FEA Reference Models (i.e. the BRM, DRM, TRM, etc.) are very helpful frameworks for organizing, understanding, communicating and standardizing across agencies with respect to vocabularies, architecture patterns and technology standards. Determining when, how and to what level of detail to include these reference models in the typically long-running Federal IT acquisition cycles wasn’t always clear, however, particularly during the first interactions of a Program’s technical and functional leadership with the Mission owners and investment planners. This typically occurs as an agency begins the process of describing its strategy and business case for allocation of new Federal funding, reacting to things like new legislation or policy, real or anticipated mission challenges, or straightforward ROI opportunities (for example the introduction of new technologies that deliver significant cost-savings).The early artifacts (i.e. Resource Allocation Plans, Acquisition Plans, Exhibit 300’s or other Business Case materials, etc.) of the intersection between Mission owners, IT and Program Managers are far easier to understand and discuss, when the overlay of an evolved, actionable Enterprise Architecture (such as the FEA) is applied.  “Actionable” is the key word – too many Public Service entity EA’s (including the FEA) have for too long been used simply as a very highly-abstracted standards reference, duly maintained and nominally-enforced by an Enterprise or System Architect’s office. Refreshing elements of this recent FEA Common Approach include one of the first Federally-documented acknowledgements of the “Solution Architect” (the “Problem-Solving” role). This role collaborates with the Enterprise, System and Business Architecture communities primarily on completing actual “EA Roadmap” documents. These are roadmaps grounded in real cost, technical and functional details that are fully aligned with both contextual expectations (for example the new “Digital Government Strategy” and its required roadmap deliverables - and the rapidly increasing complexities of today’s more portable and transparent IT solutions.  We also expect some very critical synergies to develop in early IT investment cycles between this new breed of “Federal Enterprise Solution Architect” and the first waves of the newly-formal “Federal IT Program Manager” roles operating under more standardized “critical competency” expectations (including EA), likely already to be seriously influencing the quality annual CPIC (Capital Planning and Investment Control) processes.  Our Oracle Enterprise Strategy Team (EST) and associated Oracle Enterprise Architecture (OEA) practices are already engaged in promoting and leveraging the visibility of Enterprise Architecture as a key contributor to early IT investment validation, and we look forward in particular to seeing the real, citizen-centric benefits of this FEA Common Approach in particular surface across the entire Public Service CPIC domain - Federal, State, Local, Tribal and otherwise. Read more Enterprise Architecture blog posts for additional EA insight!

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  • Naming convention for non-virtual and abstract methods

    - by eagle
    I frequently find myself creating classes which use this form (A): abstract class Animal { public void Walk() { // TODO: do something before walking // custom logic implemented by each subclass WalkInternal(); // TODO: do something after walking } protected abstract void WalkInternal(); } class Dog : Animal { protected override void WalkInternal() { // TODO: walk with 4 legs } } class Bird : Animal { protected override void WalkInternal() { // TODO: walk with 2 legs } } Rather than this form (B): abstract class Animal { public abstract void Walk(); } class Dog : Animal { public override void Walk() { // TODO: do something before walking // custom logic implemented by each subclass // TODO: walk with 4 legs // TODO: do something after walking } } class Bird : Animal { public override void Walk() { // TODO: do something before walking // custom logic implemented by each subclass // TODO: walk with 2 legs // TODO: do something after walking } } As you can see, the nice thing about form A is that every time you implement a subclass, you don't need to remember to include the initialization and finalization logic. This is much less error prone than form B. What's a standard convention for naming these methods? I like naming the public method Walk since then I can call Dog.Walk() which looks better than something like Dog.WalkExternal(). However, I don't like my solution of adding the suffix "Internal" for the protected method. I'm looking for a more standardized name. Btw, is there a name for this design pattern?

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  • documenting class attributes

    - by intuited
    I'm writing a lightweight class whose attributes are intended to be publicly accessible, and only sometimes overridden in specific instantiations. There's no provision in the Python language for creating docstrings for class attributes, or any sort of attributes, for that matter. What is the accepted way, should there be one, to document these attributes? Currently I'm doing this sort of thing: class Albatross(object): """A bird with a flight speed exceeding that of an unladen swallow. Attributes: """ flight_speed = 691 __doc__ += """ flight_speed (691) The maximum speed that such a bird can attain. """ nesting_grounds = "Raymond Luxury-Yacht" __doc__ += """ nesting_grounds ("Raymond Luxury-Yacht") The locale where these birds congregate to reproduce. """ def __init__(**keyargs): """Initialize the Albatross from the keyword arguments.""" self.__dict__.update(keyargs) Although this style doesn't seem to be expressly forbidden in the docstring style guidelines, it's also not mentioned as an option. The advantage here is that it provides a way to document attributes alongside their definitions, while still creating a presentable class docstring, and avoiding having to write comments that reiterate the information from the docstring. I'm still kind of annoyed that I have to actually write the attributes twice; I'm considering using the string representations of the values in the docstring to at least avoid duplication of the default values. Is this a heinous breach of the ad hoc community conventions? Is it okay? Is there a better way? For example, it's possible to create a dictionary containing values and docstrings for the attributes and then add the contents to the class __dict__ and docstring towards the end of the class declaration; this would alleviate the need to type the attribute names and values twice. edit: this last idea is, I think, not actually possible, at least not without dynamically building the class from data, which seems like a really bad idea unless there's some other reason to do that. I'm pretty new to python and still working out the details of coding style, so unrelated critiques are also welcome.

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  • documenting class properties

    - by intuited
    I'm writing a lightweight class whose properties are intended to be publicly accessible, and only sometimes overridden in specific instantiations. There's no provision in the Python language for creating docstrings for class properties, or any sort of properties, for that matter. What is the accepted way, should there be one, to document these properties? Currently I'm doing this sort of thing: class Albatross(object): """A bird with a flight speed exceeding that of an unladen swallow. Properties: """ flight_speed = 691 __doc__ += """ flight_speed (691) The maximum speed that such a bird can attain """ nesting_grounds = "Throatwarbler Man Grove" __doc__ += """ nesting_grounds ("Throatwarbler Man Grove") The locale where these birds congregate to reproduce. """ def __init__(**keyargs): """Initialize the Albatross from the keyword arguments.""" self.__dict__.update(keyargs) Although this style doesn't seem to be expressly forbidden in the docstring style guidelines, it's also not mentioned as an option. The advantage here is that it provides a way to document properties alongside their definitions, while still creating a presentable class docstring, and avoiding having to write comments that reiterate the information from the docstring. I'm still kind of annoyed that I have to actually write the properties twice; I'm considering using the string representations of the values in the docstring to at least avoid duplication of the default values. Is this a heinous breach of the ad hoc community conventions? Is it okay? Is there a better way? For example, it's possible to create a dictionary containing values and docstrings for the properties and then add the contents to the class __dict__ and docstring towards the end of the class declaration; this would alleviate the need to type the property names and values twice. I'm pretty new to python and still working out the details of coding style, so unrelated critiques are also welcome.

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  • NSFetchedResultsController sections localized sorted

    - by Gerd
    How could I use the NSFetchedResultsController with translated sort key and sectionKeyPath? Problem: I have ID in the property "type" in the database like typeA, typeB, typeC,... and not the value directly because it should be localized. In English typeA=Bird, typeB=Cat, typeC=Dog in German it would be Vogel, Katze, Hund. With a NSFetchedResultController with sort key and sectionKeyPath on "type" I receive the order and sections - typeA - typeB - typeC Next I translate for display and everything is fine in English: - Bird - Cat - Dog Now I switch to German and receive a wrong sort order - Vogel - Katze - Hund because it still sorts by typeA, typeB, typeC So I'm looking for a way to localize the sort for the NSFetchedResultsController. I tried the transient property approach, but this doesn't work for the sort key because the sort key need to be in the entity. I have no other idea. But I can't believe that's not possible to use NSFetchedResultsController on a derived attribute required for localization? There are related discussions like http://stackoverflow.com/questions/1384345/using-custom-sections-with-nsfetchedresultscontroller but the difference is that the custom section names and the sort key have probably the same order. Not in my case and this is the main difference. At the end I would need a sort order for the necessary NSSortDescriptor on a derived attribute, I guess. This sort order has also to serve for the sectionKeyPath. Thanks for any hint.

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  • Array of Sentences?

    - by user1869915
    Javascript noob here.... I am trying to build a site that will help my kids read predefined sentences from a select group, then when a button is clicked it will display one of the sentences. Is an array the best option for this? For example, I have this array (below) and on the click of a button I would like one of these sentences to appear on the page. <script type="text/javascript"> Sentence = new Array() Sentence[0]='Can we go to the park.'; Sentence[1]='Where is the orange cat? Said the big black dog.'; Sentence[2]='We can make the bird fly away if we jump on something.' Sentence[3]='We can go down to the store with the dog. It is not too far away.' Sentence[4]='My big yellow cat ate the little black bird.' Sentence[5]='I like to read my book at school.' Sentence[6]='We are going to swim at the park.' </script> Again, is an array the best for this and how could I get the sentence to display? Ideally I would want the button to randomly select one of these sentences but just displaying one of them for now would help. Thanks

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  • Kernel Panic on VMware Workstation 7.1.3

    - by i.h4d35
    I've been trying to install either Arch Linux or Fedora 17 on VMWare Workstation (7.1.3). After I point to the right ISO image, I get the following error: Booting the kernel PANIC: early exception 0d rip:ffffffff81042dc4 error 0 cr2 0 I am trying to install it on a machine which has a 3rd generation i5 processor. After checking A VMWare panic early exception fix for ivy bridge i3, i5, i7, I tried to turn off the nosmep acpi. This is around, I get the same error but at a different address. Apparently, others have faced this issue before. Thanks in advance.

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  • apache mod_cache in v2.2 - enable cache based on url

    - by Janning
    We are using apache2.2 as a front-end server with application servers as reverse proxies behind apache. We are using mod_cache for some images and enabled it like this: <IfModule mod_disk_cache.c> CacheEnable disk / CacheRoot /var/cache/apache2/mod_disk_cache CacheIgnoreCacheControl On CacheMaxFileSize 2500000 CacheIgnoreURLSessionIdentifiers jsessionid CacheIgnoreHeaders Set-Cookie </IfModule> The image urls vary completely and have no common start pattern, but they all end in ".png". Thats why we used the root in CacheEnable / If not served from the cache, the request is forwarded to an application server via reverse proxy. So far so good, cache is working fine. But I really only need to cache all image request ending in ".png". My above configuration still works as my application server send an appropriate Cache-Control: no-cache header on the way back to apache. So most pages send a no-cache header back and they get not cached at all. My ".png" responses doesn't send a Cache-Control header so apache is only going to cache all urls with ".png". Fine. But when a new request enters apache, apache does not know that only .png requests should be considered, so every request is checking a file on disk (recorded with strace -e trace=file -p pid): [pid 19063] open("/var/cache/apache2/mod_disk_cache/zK/q8/Kd/g6OIv@woJRC_ba_A.header", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory) I don't want to have apache going to disk every request, as the majority of requests are not cached at all. And we have up to 10.000 request/s at peak time. Sometimes our read IO wait spikes. It is not getting really slow, but we try to tweak it for better performance. In apache 2.4 you can say: <LocationMatch .png$> CacheEnable disk </LocationMatch> This is not possible in 2.2 and as I see no backports for debian I am not going to upgrade. So I tried to tweak apache2.2 to follow my rules: <IfModule mod_disk_cache.c> SetEnvIf Request_URI "\.png$" image RequestHeader unset Cache-Control RequestHeader append Cache-Control no-cache env=!image CacheEnable disk / CacheRoot /var/cache/apache2/mod_disk_cache #CacheIgnoreCacheControl on CacheMaxFileSize 2500000 CacheIgnoreURLSessionIdentifiers jsessionid CacheIgnoreHeaders Set-Cookie </IfModule> The idea is to let apache decide to serve request from cache based on Cache-control header (CacheIgnoreCacheControl default to off). And before simply set a RequestHeader based on the request. If it is not an image request, set a Cache-control header, so it should bypass the cache at all. This does not work, I guess because of late processing of RequestHeader directive, see https://httpd.apache.org/docs/2.2/mod/mod_headers.html#early I can't add early processing as "early" keyword can't be used together with a conditional "env=!image" I can't change the url requesting the images and I know there are of course other solutions. But I am only interested in configuring apache2.2 to reach my goal. Does anybody has an idea how to achieve my goal?

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  • How do I execute a command before kickstart parses ks.cfg?

    - by Crazy Chenz
    How do I execute a command before kickstart parses ks.cfg? My specific problem is that I want to install redhat into a tmpfs by telling kickstart: part / --fstype ext3 --size 1000 --maxsize 4000 --ondisk loop1 I've tried doing: %pre #!/bin/sh mkdir /tmp-root mount -t tmpfs tmpfs /tmp-root dd if=/dev/zero of=/tmp-root/tmp-root.img bs=4096 count=1000000 losetup /dev/loop1 /tmp-root/tmp-root.img but that is not done early enough. Ugh! Update: I'm beginning to think it has nothing to do with being done early enough. I believe it has to do with anaconda and kudzu not thinking that a loopback device is a valid device. I'm not a python guy, so the idea of hacking up the kickstart code sucks! -Vinnie

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