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  • PHP API to trade products from eshop through REST/xml

    - by Donatas Veikutis
    I need algorithm, or PHP api example, or existing decision how to make system for trade big information for B2B xml with goods information. Now I try to use Slim framework to do that system. But for me need some documentation what architecture have to be in here. System requiments is simple: User have autentification username and password Then he can see which product groups assigned to it Then he can see all product with information (price, title, description, images, specifications etc.). Its will the easiest way to get a free php api for that I think, and try too edit some code. But I did not found anything.

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  • Countdown to Transit of Venus and a List of Feeds

    - by TATWORTH
    At http://www.space.com/14568-venus-transits-sun-2012-skywatching.html there is a countdown to the transit of Venus.NASA will providing a video feed from Mauna Kea of the event from http://venustransit.nasa.gov/2012/transit/webcast.php.The SLOOH space camera site will provide a feed at http://www.slooh.com/transit-of-venus/Astronomers Without Borders will provide a feed from Mount Wilson at http://www.astronomerswithoutborders.org/projects/transit-of-venus.htmlOther web camera feeds are at:http://www.skywatchersindia.com/http://venustransit.nasa.gov/transitofvenus/http://venustransit.nso.edu/http://www.transitofvenus.com.au/HOME.htmlhttp://www.exploratorium.edu/venus/http://www.bareket-astro.com/live-astronomical-web-cast/live-free-venus-transit-webcast-6-june-2012.htmlhttp://cas.appstate.edu/streams/2012/05/physics-and-astronomy-astrocamhttp://skycenter.arizona.edu/

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  • The Journey to the Mystical Forest [Wallpaper]

    - by Asian Angel
    MYSTICAL FOREST PATH [DesktopNexus] Latest Features How-To Geek ETC Macs Don’t Make You Creative! So Why Do Artists Really Love Apple? MacX DVD Ripper Pro is Free for How-To Geek Readers (Time Limited!) HTG Explains: What’s a Solid State Drive and What Do I Need to Know? How to Get Amazing Color from Photos in Photoshop, GIMP, and Paint.NET Learn To Adjust Contrast Like a Pro in Photoshop, GIMP, and Paint.NET Have You Ever Wondered How Your Operating System Got Its Name? Sync Blocker Stops iTunes from Automatically Syncing The Journey to the Mystical Forest [Wallpaper] Trace Your Browser’s Roots on the Browser Family Tree [Infographic] Save Files Directly from Your Browser to the Cloud in Chrome and Iron The Steve Jobs Chronicles – Charlie and the Apple Factory [Video] Google Chrome Updates; Faster, Cleaner Menus, Encrypted Password Syncing, and More

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  • How does timeseal work? [on hold]

    - by Simon Meyer
    I know the the fics (free internet chess server: www.freechess.org/) does use a program called timeseal to measure the time that a user needed to take a move. This timeseal is some time measurement on the client. Measuring on the client is much better and fairer than measuring the time on the server since you don't lose time just by having a bad connection. But since fics has a lot of interfaces to play on - what prevents rogue interfaces to say that they always only used 0.1 seconds for any move? Does anyone know how this is handled? Just a sidenote: i don't want to build a rogue interface, but i'm trying to build something similar that is measuing client side time but should not be easy to cheat on.

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  • Run your cpus fast but not hot

    - by John Paul Cook
    Paul Randall recently blogged about the importance of checking to make sure you are getting every bit of speed you should from your cpus. He recommended that people use CPU-Z , a free tool I recommend and have been using for many years. Power saving features in a cpu are great for laptops. Battery life is greatly extended when a processor isn't running to the max all of the time. But this isn't necessarily a good thing for a server. As Paul and others have pointed out, the processor might not get...(read more)

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  • Humble Indie Bundle V: Psychonauts, Superbrothers, and More at a Name Your Own Price

    - by Jason Fitzpatrick
    There’s a new Humble Indie with some fantastic DRM-free and cross-platform offerings and, most importantly, some fantastic games. Score a copy of Psychonauts for the best price in town! But seriously: if you’re looking to game on a budget this Humble Indie Bundle is an absolute gem. For a few bucks (that you can even opt to donate to charity) you can score five awesome games including Psychonauts. I enjoyed Psychonauts so much I’d happily pay the full original retail just to play it again. In addition, the full soundtracks for each game are included with your purchase. Hit up the link below for more information. Humble Indie Bundle V is available until 6PM EST, 6/14/2012. The Humble Indie Bundle V HTG Explains: Learn How Websites Are Tracking You Online Here’s How to Download Windows 8 Release Preview Right Now HTG Explains: Why Linux Doesn’t Need Defragmenting

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  • VBUG Spring Conference, 28th and 29th March in Reading

    - by Eric Nelson
    I presented at VBUG last year and can confirm that they put on a really good event. This year I stood aside for my “replacement” Steve Plank to work his magic. Worth checking out… VBUG SPRING CONFERENCE 28/29 March 2011 Wokefield Park, Mortimer, Reading RG7 3AH Day One (Mon 28 March): Developing SharePoint 2010 with Visual Studio 2010 - Dave McMahon Cache Out with Windows Server AppFabric – Phil Pursglove Extending your Corporate Network in to the Windows Azure Data Centre with Windows Azure Connect – Steve Plank Silverlight Development on Windows Phone 7 - Andy Wigley Day Two (Tues 29 March): Self Service BI for your users, but what does that mean for you? - Andrew Fryer Design Patterns – Compare and Contrast – Gary Short Projecting your corporate identity to the cloud – Steve Plank May the Silverlight 4 be with you – Richard Costall The Step up to ALM – an Introduction to Visual Studio 2010 TFS for the Visual Sourcesafe User - Richard Fennell For more information go to http://cms.vbug.net (It isn’t free but it is high quality)

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  • UppercuT v1.0 and 1.1&ndash;Linux (Mono), Multi-targeting, SemVer, Nitriq and Obfuscation, oh my!

    - by Robz / Fervent Coder
    Recently UppercuT (UC) quietly released version 1 (in August). I’m pretty happy with where we are, although I think it’s a few months later than I originally planned. I’m glad I held it back, it gave me some more time to think about some things a little more and also the opportunity to receive a patch for running builds with UC on Linux. We also released v1.1 very recently (December). UppercuT v1 Builds On Linux Perhaps the most significant changes to UC going v1 is that it now supports builds on Linux using Mono! This is thanks mostly to Svein Ackenhausen for the patches and working with me on getting it all working while not breaking the windows builds!  This means you can use mono on Windows or Linux. Notice the shell files to execute with Linux that come as part of UC now. Multi-Targeting Perhaps one of the hardest things to do that requires an automated build is multi-targeting. At v1 this is early, and possibly prone to some issues, but available.  We believe in making everything stupid simple, so it’s as simple as adding a comma to the microsoft.framework property. i.e. “net-3.5, net-4.0” to suddenly produce both framework builds. When you build, this is what you get (if you meet each framework’s requirements): At this time you have to let UC override the build location (as it does by default) or this will not work.  Semantic Versioning By now many of you have been using UppercuT for awhile and have watched how we have done versioning. Many of you who use git already know we put the revision hash in the informational/product version as the last octet. At v1, UppercuT has adopted the semantic versioning scheme. What does that mean? This is a short read, but a good one: http://SemVer.org SemVer (Semantic Versioning) is really using versioning what it was meant for. You have three octets. Major.Minor.Patch as in 1.1.0.  UC will use three different versioning concepts, one for the assembly version, one for the file version, and one for the product version. All versions - The first three octects of the version are owned by SemVer. Major.Minor.Patch i.e.: 1.1.0 Assembly Version - The assembly version would much closer follow SemVer. Last digit is always 0. Major.Minor.Patch.0 i.e: 1.1.0.0 File Version - The file version occupies the build number as the last digit. Major.Minor.Patch.Build i.e.: 1.1.0.2650 Product/Informational Version - The last octect of your product/informational version is the source control revision/hash. Major.Minor.Patch.RevisionOrHash i.e. (TFS/SVN): 1.1.0.235 i.e. (Git/HG): 1.1.0.a45ace4346adef0 SemVer is not on by default, the passive versioning scheme is still in effect. Notice that version.use_semanticversioning has been added to the UppercuT.config file (and version.patch in support of the third octet): Gems Support Gems support was added at v1. This will probably be deprecated as some point once there is an announced sunset for Nu v1. Application gems may keep it around since there is no alternative for that yet though (CoApp would be a possible replacement). Nitriq Support Nitriq is a code analysis tool like NDepend. It’s built by Mr. Jon von Gillern. It uses LINQ query language, so you can use a familiar idiom when analyzing your code base. It’s a pretty awesome tool that has a free version for those looking to do code analysis! To use Nitriq with UC, you are going to need the console edition.  To take advantage of Nitriq, you just need to update the location of Nitriq in the config: Then add the nitriq project files at the root of your source. Please refer to the Nitriq documentation on how these are created. UppercuT v1.1 Obfuscation One thing I started looking into was an easy way to obfuscate my code. I came across EazFuscator, which is both free and awesome. Plus the GUI for it is super simple to use. How do you make obfuscation even easier? Make it a convention and a configurable property in the UC config file! And the code gets obfuscated! Closing Definitely get out and look at the new release. It contains lots of chocolaty (sp?) goodness. And remember, the upgrade path is almost as simple as drag and drop!

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  • How to avoid getting carried away with details?

    - by gablin
    When I program, I often get too involved with details. There might be some little thing that doesn't do exactly what I want it to, or maybe there's some little feature I want to add. Either way, none are really essential to the application - it's just a minor niusance (if any). However, when trying to fix it, I may happen to spend way more time on it than I planned, and there are things much more important that I should be doing instead of dealing with this little detail. What can I do to avoid getting carried away with details, when there's more essential things that need doing? (I didn't know how to tag this question, so feel free to add whatever appropriate tags that are missing.)

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  • Wanting to learn .NET, can I benefit from the MS discounts?

    - by Chris
    I quit high-school a couple of years ago and now I'm studying to get my diploma at a special course the EU created for people in my situation. This course is basically identical to normal high-school the only difference being fewer hours due to the fact that a lot of us have jobs(not me). I would like to learn windows development and .NET and I've seen around that they offer students some great discounts and even some free tools such as Visual Studio and Windows 7. I'm learning Java on Ubuntu at the moment but I'd like to move to .NET but can't afford Windows or other MS-related tools since I don't have a job and no real income. Can someone in my situation benefit from their offers?

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  • Taking a Flying Leap

    - by Lance Shaw
    Yesterday, I went skydiving with three of my children.  It was thrilling, scary, invigorating and exciting. While there is obvious risk involved, the reward and feeling of success was well worth it. You might already be wondering what skydiving would have to with WebCenter, so let me explain. Implementing a skydiving program and becoming an instructor does not happen overnight.  It does not happen with the purchase of the needed technology. Not one of us would go out, buy a parachute, the harnesses, helmet and all the gear and be able to convince anyone that we are now ready to be a skydiving instructor. The fact is that obtaining the technology is merely a small piece of the overall process and so is the case with managing content in your company. You don't just buy the right software (Oracle WebCenter Content) and go to your boss and declare information management success. There is planning, research and effort that goes into deploying software of any kind and especially when it is as mission-critical to the success of your business as Enterprise Content Management. To become a certified skydiving instructor takes at least 3 years of commitment and often longer. In the United States, candidates must complete over 500 solo jumps of their own over a minimum of 36 months and then must complete additional rigorous training under observation.  When you consider the amount of time and effort involved, it's not unlike getting a college degree and anyone that has trusted their lives to one of these instructors will no doubt appreciate their dedication to the curriculum.  Implementing an ECM system won't take that long, but it certainly requires commitment, analysis and consideration. But guess what?  Humans are involved and that means that mistakes can happen and that rules change.  This struck me while reading an excellent post on darkreading.com by Glenn S. Phillips entitled "Mission Impossible: 4 Reasons Compliance is Impossible".  His over-arching point was that with information management and security, environments change and people are involved meaning the work is never done.  He stated that you can never claim your compliance efforts are complete because of the following reasons. People are involved.  And lets face it, some are more trustworthy than others. Change is Constant. There is always some new technology coming along that is disruptive. Consumer grade cloud file sharing and sync tools come to mind here. Compliance is interpreted, not defined.  Laws and the judges that read them are always on the move. Technology is a tool, not a complete solution. There is no magic pill. The skydiving analogy holds true here as well.  Ultimately, a single person packs your parachute.  For obvious reasons, you prefer that this person be trustworthy but there are no absolute guarantees of a 100% error-free scenario.  Weather and wind conditions are never a constant and the best-laid plans for a great day of skydiving are easily disrupted by forces outside of your control.  Rules and regulations vary by location and may be updated at any time and as I mentioned early on, even the best technology on its own will only get you started. The good news is that, like skydiving, with the right technology, the right planning, the right team and a proper understanding of the rules and regulations that govern your industry, your ECM deployment can be a great success.  Failure to plan for any of the 4 factors that Glenn outlined in his article will certainly put your deployment and maybe even your company at risk, so consider them carefully. As a final aside, for those of you who consider skydiving an incredibly dangerous and risky pastime, consider this comparative statistic.  In 2012, the U.S. Parachute Association recorded 19 fatal skydiving accidents in the U.S. out of roughly 3.1 million jumps.  That’s 0.006 fatalities per 1,000 jumps. By comparison, the U.S. National Highway Traffic Safety Administration reports that there were 34,080 deaths due to car accidents in 2012.  Based on the percentages, one could argue that it is safer to jump out of a plane than to drive to the airport where the skydiving will take place. While the way you manage, secure, classify, control, retain and dispose of company files may not carry as much risk as driving or skydiving, it certainly carries risk for the organization when not planned and deployed appropriately.  Consider all the factors involved in your organization as you make your content management plans.  For additional areas of consideration, be sure to download our free whitepaper on the topic entitled "The Top 10 Criteria for Choosing an ECM System" which is available for download here.

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  • C# Toolbox: Debug-able, Self-Installable Windows Service Template Redux

    - by James Michael Hare
    I had written a pair of posts before about creating a debug-able and self-installing windows service template in C#.  This is a template I began creating to ease creating windows services and to take some of the mundane tasks out of the coding effort.  The original posts were here: C# Windows Services (1 of 2) - Debug-able Windows Services C# Windows Services (2 of 2) - Self-Installing Windows Services But at the time, though I gave the code samples I didn't have a downloadable for of the template on the blog.  After getting many requests for the actual source, I zipped it up and am posting it with this blog entry.  Click on the link below to download the archive.  The password on the archive is, imaginatively enough, password.  Hope you enjoy and please feel free to comment and suggest changes! Debug-able, Self-Installing Windows Service Template download Enjoy! Tweet Technorati Tags: C#,Windows Service,Toolbox

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  • Windows Azure powers Father Christmas

    - by Eric Nelson
    Ok it doesn’t really but the Microsoft Partner Network folks have hit gold with this rather addictive chrimbo game. It is great fun to play yet has a little serious side as it “rewards” you with a Windows Azure related link after each level. Try it now! http://bit.ly/festivegame It is a Silverlight app which is: Related In the UK we are helping partners build applications for the Windows Azure Platform (and other technologies such as SQL Server 2008 R2) through Microsoft Platform Ready. Sign up for FREE to get access to some great benefits (more on that in a future post). It also really helps us better understand the demand out there which directly impacts how we will plan the next six months of activities around the Windows Azure Platform. P.S. I nearly forgot. Can I be the first (hopefully) to wish you Merry Christmas!

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  • Ubuntu keyboard shortcuts - two-part question

    - by Don
    Background: I come from a Windows background and just started dual-booting Ubuntu (my first Linux experience) about 4 days ago. So my systems are Windows 7/Ubuntu 12.04, and so far I'm loving Ubuntu. I am a dedicated mouse-abolitionist (trackpads are hell) and do most of my browsing and navigation with keyboard shortcuts. However, on switching to Ubuntu, a lot of my keyboard shortcuts are gone, and my productivity has resultantly taken a huge hit anytime I am using Ubuntu. Problem 1: My computer was designed to display on-screen notifications for a second when I hit caps-lock or num-lock, and there are no constant indicators of the lock status (LEDs, etc). In Ubuntu, the keys still worked, but the notifications were gone. Googling got me a tutorial on key-binding(Compiz) and scripts, so now I have capslock and numlock running this script: #!/bin/bash icon="/usr/share/icons/gnome/scalable/devices/keyboard.svg" case $1 in 'scrl') mask=3 key="Scroll" ;; 'num') mask=2 key="Num" ;; 'caps') mask=1 key="Caps" ;; esac value=$(xset q | grep "LED mask" | sed -r "s/.*LED mask:\s+[0-9a-fA-F]+([0-9a-fA-F]).*/\1/") if [ $(( 0x$value & 0x$mask )) == $mask ] then output="$key Lock" output2="On" else output="$key Lock" output2="Off" fi notify-send -i $icon "$output" "$output2" -t 1000 But, whether turning it off or on, the notifications always say that I have turned it on. Is there an easy fix for this, or an easier way to work it to get it do display the CORRECT notifications? Problem 2: I'm not sure if this is because of my keyboard or Ubuntu. In Windows, I use Chrome and use the ctrl+pgUp/pgDwn shortcuts quite a bit to switch between tabs. On my keyboard, I can enter pgUp and pgDwn by either disabling NumLock and hitting 9 or 3 respectively on the 10key. Alternately I can hold the fn key and hit up or down arrow. The first method is the one I very heavily relied upon, and it works in Firefox for Ubuntu, but not in Chrome nor in Chromium. The second method (ctrl + fn + up/down) works fine in Chrome. However, I'd dearly like to find a method to make the first method work. Any suggestions? Thanks in advance for your help. Update: @julien: I've checked the keyboard layout options - I didn't find anything that seemed useful for this goal. @Marty: The script runs once when the button is pressed. In Compiz, I've tied those two keys to the script, so when I press the button, it runs the script with the button pressed as a parameter. Update: @elmicha: Thanks. That one works a lot better, and it even pops an icon into the status bar when caps lock is on. There's still a very slight problem in that if I quickly tap the key twice, the image will show that it has been turned on and then turned off, and the notifaction will come and go from my status area, but the text of both notifications will be "Caps Lock on". Same with Num Lock. However, if the time between presses is long enough for the first notification to disappear, everything displays correctly. Given how quickly the notifications disappear, I don't expect this will pose too much of a problem for me.

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  • Motivating developers in a project perceived as **dull** ?

    - by Fanatic23
    As a manager, I can't always end up generating work that'd be cutting edge. Some of the projects do run on maintenance mode, and generate a healthy free cash flow for the company. As a developer what would it take for you to stick around in this project? I have been thinking of re-branding the work, but I could do with a lot of help here. Appreciate a single response per post. Please don't suggest an increased pay-packet, this creates more problems than it solves.

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  • SQLSat65, Great Perf Counters Poster from Quest

    - by merrillaldrich
    I was fortunate to be able to attend the Vancouver BC SQLSaturday this past weekend, and it was excellent! Great sessions, good facility, well attended. Nice work, and a huge thank you to the volunteers that made that happen. One side perk: I got a copy of this terrific performance counters poster from Quest, which you can download as a PDF for free. Very handy, especially as a teaching tool. I'm using it for my SCOM MP work. Check it out....(read more)

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  • Gilbane Conference San Francisco 2010

    I attended the Gilbane Conference San Francisco 2010 today and did a short presentation on: Open Source Tools That are Changing the Content Technology Landscape Open Source tools are dramatically changing our perceptions of software and how we invest in tools for content creation, management and delivery. Open source tools are created more cheaply by a broad team of developers, but also may require strong support organizations to make them work, so they are never free. This session will examine...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Why Choose Oracle University?

    - by Shen Chen
    Get Specialized Training & Certification from ExpertOracle Instructors - with a 100% Satisfaction Guarantee. 5 Reasons to Enroll in Oracle Certification or Training 1. Career Growth: our curriculum is developed to teach you skills that directly align with real-life IT jobs. 2. Salary Advancement: Certification magazine found that Oracle Certified Professionals earn higher salaries when compared to other DBA or Developer professionals. 3. Expert Instruction: learn Oracle from the same team involved in Oracle product development. 4. Flexible Learning Options: train from anywhere, at any time. Pick the format that matches your learning style & schedule. 5. 100 % Student Satisfaction Guarantee: if you’re not completely satisfied with your training or certification experience, you can re-take the same class for free.

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  • Why isn't Startup Disk Creator working in 12.04?

    - by Steve Kelem
    I'm trying to create a bootable USB stick (7.5G) for Ubuntu 12.04 (x86_64) from another Ubuntu 12.04 x86_64 PC. I downloaded the Ubuntu 12.04 LTS "Precise Pangolin" - Release amd64 (20120425). When I run Make Startup Disk, I selected the downloaded release. The drive shows up with a capacity of 7.5GB and a blank space under "Free Space". I have tried using the "Erase Disk" button, which seems to erase the disk. The problem is that the options below the "Disk to use" section are grayed out. The "Make Startup Disk" is colored dull orange, while the source disc image and device to use are bright orange. The "Make Startup Disk" button doesn't do anything when I click it. The only working buttons are "Other...", "Erase Disk", and "Close". Upon using Other button to select the ISO, it allows to select the ISO but it doesn't load and the "Source Disk Image" field remains empty.

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  • HTG Projects: How to Create Your Own Custom Papercraft Toy

    - by Eric Z Goodnight
    Graphics programs aren’t simply for just editing your photos—they can have whatever fun application you can think of. For a fun, geeky project, here’s a simple papercraft toy you can make with a printer and simple household tools Latest Features How-To Geek ETC How To Boot 10 Different Live CDs From 1 USB Flash Drive The 20 Best How-To Geek Linux Articles of 2010 The 50 Best How-To Geek Windows Articles of 2010 The 20 Best How-To Geek Explainer Topics for 2010 How to Disable Caps Lock Key in Windows 7 or Vista How to Use the Avira Rescue CD to Clean Your Infected PC The Deep – Awesome Use of Metal Objects as Deep Sea Creatures [Video] Convert or View Documents Online Easily with Zoho, No Account Required Build a Floor Scrubbing Robot out of Computer Fans and a Frisbee Serene Blue Windows Wallpaper for Your Desktop 2011 International Space Station Calendar Available for Download (Free) Ultimate Elimination – Lego Black Ops [Video]

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  • Blog not even ranking for exact title match, after domain has been dropped twice [on hold]

    - by Akshay Hallur
    Consider a blog, related to blogging and SEO. The domain has been dropped (expired) 2 times before acquisition. The current owner is the 3rd owner of the domain since 5 months. Blog posts are not ranking, even for exact titles. Google+ or other shares will show up instead of the content. Some blog posts are not even indexed. Let us TAKE that it gets around 7 organic visits / day. Dropped domain, less likely used for spam (WayBack machine (2 Reframed drops) 3 captures since 2004, Don't know whether there was Email spam) (But no manual actions in WMT, so no reconsideration request). What could be the reason for this? How can Google be told that ownership is changed and the domain is now spam-free? Would this domain be salvageble, or does this only change after relocating to another domain?

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  • Computer Networks UNISA - Chap 8 &ndash; Wireless Networking

    - by MarkPearl
    After reading this section you should be able to Explain how nodes exchange wireless signals Identify potential obstacles to successful transmission and their repercussions, such as interference and reflection Understand WLAN architecture Specify the characteristics of popular WLAN transmission methods including 802.11 a/b/g/n Install and configure wireless access points and their clients Describe wireless MAN and WAN technologies, including 802.16 and satellite communications The Wireless Spectrum All wireless signals are carried through the air by electromagnetic waves. The wireless spectrum is a continuum of the electromagnetic waves used for data and voice communication. The wireless spectrum falls between 9KHZ and 300 GHZ. Characteristics of Wireless Transmission Antennas Each type of wireless service requires an antenna specifically designed for that service. The service’s specification determine the antenna’s power output, frequency, and radiation pattern. A directional antenna issues wireless signals along a single direction. An omnidirectional antenna issues and receives wireless signals with equal strength and clarity in all directions The geographical area that an antenna or wireless system can reach is known as its range Signal Propagation LOS (line of sight) uses the least amount of energy and results in the reception of the clearest possible signal. When there is an obstacle in the way, the signal may… pass through the object or be obsrobed by the object or may be subject to reflection, diffraction or scattering. Reflection – waves encounter an object and bounces off it. Diffraction – signal splits into secondary waves when it encounters an obstruction Scattering – is the diffusion or the reflection in multiple different directions of a signal Signal Degradation Fading occurs as a signal hits various objects. Because of fading, the strength of the signal that reaches the receiver is lower than the transmitted signal strength. The further a signal moves from its source, the weaker it gets (this is called attenuation) Signals are also affected by noise – the electromagnetic interference) Interference can distort and weaken a wireless signal in the same way that noise distorts and weakens a wired signal. Frequency Ranges Older wireless devices used the 2.4 GHZ band to send and receive signals. This had 11 communication channels that are unlicensed. Newer wireless devices can also use the 5 GHZ band which has 24 unlicensed bands Narrowband, Broadband, and Spread Spectrum Signals Narrowband – a transmitter concentrates the signal energy at a single frequency or in a very small range of frequencies Broadband – uses a relatively wide band of the wireless spectrum and offers higher throughputs than narrowband technologies The use of multiple frequencies to transmit a signal is known as spread-spectrum technology. In other words a signal never stays continuously within one frequency range during its transmission. One specific implementation of spread spectrum is FHSS (frequency hoping spread spectrum). Another type is known as DSS (direct sequence spread spectrum) Fixed vs. Mobile Each type of wireless communication falls into one of two categories Fixed – the location of the transmitted and receiver do not move (results in energy saved because weaker signal strength is possible with directional antennas) Mobile – the location can change WLAN (Wireless LAN) Architecture There are two main types of arrangements Adhoc – data is sent directly between devices – good for small local devices Infrastructure mode – a wireless access point is placed centrally, that all devices connect with 802.11 WLANs The most popular wireless standards used on contemporary LANs are those developed by IEEE’s 802.11 committee. Over the years several distinct standards related to wireless networking have been released. Four of the best known standards are also referred to as Wi-Fi. They are…. 802.11b 802.11a 802.11g 802.11n These four standards share many characteristics. i.e. All 4 use half duplex signalling Follow the same access method Access Method 802.11 standards specify the use of CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance) to access a shared medium. Using CSMA/CA before a station begins to send data on an 802.11 network, it checks for existing wireless transmissions. If the source node detects no transmission activity on the network, it waits a brief period of time and then sends its transmission. If the source does detect activity, it waits a brief period of time before checking again. The destination node receives the transmission and, after verifying its accuracy, issues an acknowledgement (ACT) packet to the source. If the source receives the ACK it assumes the transmission was successful, – if it does not receive an ACK it assumes the transmission failed and sends it again. Association Two types of scanning… Active – station transmits a special frame, known as a prove, on all available channels within its frequency range. When an access point finds the probe frame, it issues a probe response. Passive – wireless station listens on all channels within its frequency range for a special signal, known as a beacon frame, issued from an access point – the beacon frame contains information necessary to connect to the point. Re-association occurs when a mobile user moves out of one access point’s range and into the range of another. Frames Read page 378 – 381 about frames and specific 802.11 protocols Bluetooth Networks Sony Ericson originally invented the Bluetooth technology in the early 1990s. In 1998 other manufacturers joined Ericsson in the Special Interest Group (SIG) whose aim was to refine and standardize the technology. Bluetooth was designed to be used on small networks composed of personal communications devices. It has become popular wireless technology for communicating among cellular telephones, phone headsets, etc. Wireless WANs and Internet Access Refer to pages 396 – 402 of the textbook for details.

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  • A Year of Tuesdays: T-SQL Tuesday Meta-Roundup

    - by Adam Machanic
    Just over a year ago I kicked off T-SQL Tuesday , "a recurring, revolving blog party." The idea was simple: Each month a blog will host the party, and about a week before the second Tuesday of the month a theme will be posted. Any blogger that wishes to participate is invited to write a post on the chosen topic. The event is called "T-SQL Tuesday", but any post that is related to both SQL Server and the theme is fair game . So feel free to post about SSIS, SSRS, Java integration, or whatever other...(read more)

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  • Yes, I did it - Skydiving in Mauritius

    Finally, I did it or better said we did it. Already back in November last year I saw the big billboard advertisement of Skydive Austral Mauritius near Caudan Waterfront in Port Louis and decided for myself that this is going to be the perfect birthday gift for my wife. Simply out of curiosity I would join her tandem jump with a second instructor. Due to her pregnancy of our son I had to be patient... But then finally, her birthday had arrived and on our midnight celebration session I showed her her netbook with the website preloaded. Actually, it was the "perfect" timing... Recovery from her cesarean is fine, local weather conditions are gorgious and the children were under surveillance of my mum - spending her annual holidays on the island. So, after late wake-up in the morning, we packed our stuff and off we went. According to Google Maps direction indication we had to drive for roughly 50km (only) but traffic here in Mauritius is always challenging. The dropzone is at the Zone Industrielle Mon Loisir Sugar Estate near Riviere du Rempart at the northern east coast. Anyways, we were not in a hurry and arrived there shortly after noon. The access road to the airfield are just small down-driven paths through sugar cane fields and according to our daughter "it's bumpy!". True true true... The facilities at Skydive Austral Mauritius are complete except for food. Enough space for parking, easy handling at the reception and a lot to see for the kids. There's even a big terrace with several sets of tables and chairs, small bar for soft drinks, strictly non-alcoholic. The team over there is all welcoming and warm-hearthy! Having the kids with us was no issue at all. Quite the opposite, our daugther was allowed to discover a lot of things than we adults did. Even visiting the small air plane was on the menu for her. Really great stuff! While waiting for our turn we enjoyed watching other people getting ready in the jump gear, taking off with the Cessna, and finally coming back down on the tandem parachute. Actually, the different expressions on their faces was one of the best parts while waiting. Great mental preparation as my wife was getting more anxious about her first jump... {loadposition content_adsense} First, we got some information about the procedures on the plane about how to get seated, tight up with our instructors and how to get ready for the jump off the plane as soon as we arrive the height of 10.000 ft. All well explained and easy to understand after all.Next, we met with our jumpers Chris and Lee aka "Rasta" to get dressed and ready for take-off. Those guys are really cool and relaxed for their job. From that point on, the DVD session / recording for my wife's birthday started and we really had a lot of fun... The difference between that small Cessna and a commercial flight with an Airbus or a Boeing is astronomic! The climb up to 10.000 ft took us roughly 25 minutes and we enjoyed the magnificent view over the turquoise lagunes near Poste de Flacq, Lafayette and Isle d'Ambre on the north-east coast. After flying through the clouds we sun-bathed and looked over "iced-sugar covered" Mauritius. You might have a look at the picture gallery of Skydive Mauritius for better imagination. The moment of truth, or better said, point of no return came after approximately 25 minutes. The door opens, moving into position on the side on top of the wheel and... out! Back flip and free fall! Slight turns and Wooooohooooo! through the clouds... It so amazing and breath-taking! So undescribable! You have to experience this yourself! Some seconds later the parachute opened and we glided smoothly with some turns and spins back down to the dropzone. The rest of the family could hear and see us soon and the landing was easy going. We never had any doubts or fear about our instructors. They did a great job and we are looking forward to book our next job. I might even consider to follow educational classes on skydiving and earn a license. By the way, feel free to get in touch with Skydive Austral Mauritius. Either via contact details on their website or tweeting a little bit with them. Follow the tweets of Chris and fellows on SkydiveAustral.

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  • Best Practices - Dynamic Reconfiguration

    - by jsavit
    This post is one of a series of "best practices" notes for Oracle VM Server for SPARC (formerly named Logical Domains) Overview of dynamic Reconfiguration Oracle VM Server for SPARC supports Dynamic Reconfiguration (DR), making it possible to add or remove resources to or from a domain (virtual machine) while it is running. This is extremely useful because resources can be shifted to or from virtual machines in response to load conditions without having to reboot or interrupt running applications. For example, if an application requires more CPU capacity, you can add CPUs to improve performance, and remove them when they are no longer needed. You can use even use Dynamic Resource Management (DRM) policies that automatically add and remove CPUs to domains based on load. How it works (in broad general terms) Dynamic Reconfiguration is done in coordination with Solaris, which recognises a hypervisor request to change its virtual machine configuration and responds appropriately. In essence, Solaris receives a message saying "you now have 16 more CPUs numbered 16 to 31" or "8GB more RAM starting at address X" or "here's a new network or disk device - have fun with it". These actions take very little time. Solaris then can start using the new resource. In the case of added CPUs, that means dispatching processes and potentially binding interrupts to the new CPUs. For memory, Solaris adds the new memory pages to its "free" list and starts using them. Comparable actions occur with network and disk devices: they are recognised by Solaris and then used. Removing is the reverse process: after receiving the DR message to free specific CPUs, Solaris unbinds interrupts assigned to the CPUs and stops dispatching process threads. That takes very little time. primary # ldm list NAME STATE FLAGS CONS VCPU MEMORY UTIL UPTIME primary active -n-cv- SP 16 4G 1.0% 6d 22h 29m ldom1 active -n---- 5000 16 8G 0.9% 6h 59m primary # ldm set-core 5 ldom1 primary # ldm list NAME STATE FLAGS CONS VCPU MEMORY UTIL UPTIME primary active -n-cv- SP 16 4G 0.2% 6d 22h 29m ldom1 active -n---- 5000 40 8G 0.1% 6h 59m primary # ldm set-core 2 ldom1 primary # ldm list NAME STATE FLAGS CONS VCPU MEMORY UTIL UPTIME primary active -n-cv- SP 16 4G 1.0% 6d 22h 29m ldom1 active -n---- 5000 16 8G 0.9% 6h 59m Memory pages are vacated by copying their contents to other memory locations and wiping them clean. Solaris may have to swap memory contents to disk if the remaining RAM isn't enough to hold all the contents. For this reason, deallocating memory can take longer on a loaded system. Even on a lightly loaded system it took several 7 or 8 seconds to switch the domain below between 8GB and 24GB of RAM. primary # ldm set-mem 24g ldom1 primary # ldm list NAME STATE FLAGS CONS VCPU MEMORY UTIL UPTIME primary active -n-cv- SP 16 4G 0.1% 6d 22h 36m ldom1 active -n---- 5000 16 24G 0.2% 7h 6m primary # ldm set-mem 8g ldom1 primary # ldm list NAME STATE FLAGS CONS VCPU MEMORY UTIL UPTIME primary active -n-cv- SP 16 4G 0.7% 6d 22h 37m ldom1 active -n---- 5000 16 8G 0.3% 7h 7m What if the device is in use? (this is the anecdote that inspired this blog post) If CPU or memory is being removed, releasing it pretty straightforward, using the method described above. The resources are released, and Solaris continues with less capacity. It's not as simple with a network or I/O device: you don't want to yank a device out from underneath an application that might be using it. In the following example, I've added a virtual network device to ldom1 and want to take it away, even though it's been plumbed. primary # ldm rm-vnet vnet19 ldom1 Guest LDom returned the following reason for failing the operation: Resource Information ---------------------------------------------------------- ----------------------- /devices/virtual-devices@100/channel-devices@200/network@1 Network interface net1 VIO operation failed because device is being used in LDom ldom1 Failed to remove VNET instance That's what I call a helpful error message - telling me exactly what was wrong. In this case the problem is easily solved. I know this NIC is seen in the guest as net1 so: ldom1 # ifconfig net1 down unplumb Now I can dispose of it, and even the virtual switch I had created for it: primary # ldm rm-vnet vnet19 ldom1 primary # ldm rm-vsw primary-vsw9 If I had to take away the device disruptively, I could have used ldm rm-vnet -f but that could disrupt whoever was using it. It's better if that can be avoided. Summary Oracle VM Server for SPARC provides dynamic reconfiguration, which lets you modify a guest domain's CPU, memory and I/O configuration on the fly without reboot. You can add and remove resources as needed, and even automate this for CPUs by setting up resource policies. Taking things away can be more complicated than giving, especially for devices like disks and networks that may contain application and system state or be involved in a transaction. LDoms and Solaris cooperative work together to coordinate resource allocation and de-allocation in a safe and effective way. For best practices, use dynamic reconfiguration to make the best use of your system's resources.

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