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  • Do you employ any tools for managing technical debt?

    - by Phil.Wheeler
    The site I work with on a day-to-day basis has its share of shortcomings and we often make design decisions to "get us by right now" with the intention of fixing those up later. I've found that making the time to actually go back and fix them, let alone remembering what the full list of to-do items is can be challenging at best. Can you recommend any tools, resources or tricks that help you effectively manage your technical debt?

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  • An Alphabet of Eponymous Aphorisms, Programming Paradigms, Software Sayings, Annoying Alliteration

    - by Brian Schroer
    Malcolm Anderson blogged about “Einstein’s Razor” yesterday, which reminded me of my favorite software development “law”, the name of which I can never remember. It took much Wikipedia-ing to find it (Hofstadter’s Law – see below), but along the way I compiled the following list: Amara’s Law: We tend to overestimate the effect of a technology in the short run and underestimate the effect in the long run. Brook’s Law: Adding manpower to a late software project makes it later. Clarke’s Third Law: Any sufficiently advanced technology is indistinguishable from magic. Law of Demeter: Each unit should only talk to its friends; don't talk to strangers. Einstein’s Razor: “Make things as simple as possible, but not simpler” is the popular paraphrase, but what he actually said was “It can scarcely be denied that the supreme goal of all theory is to make the irreducible basic elements as simple and as few as possible without having to surrender the adequate representation of a single datum of experience”, an overly complicated quote which is an obvious violation of Einstein’s Razor. (You can tell by looking at a picture of Einstein that the dude was hardly an expert on razors or other grooming apparati.) Finagle's Law of Dynamic Negatives: Anything that can go wrong, will—at the worst possible moment. - O'Toole's Corollary: The perversity of the Universe tends towards a maximum. Greenspun's Tenth Rule: Any sufficiently complicated C or Fortran program contains an ad hoc, informally-specified, bug-ridden, slow implementation of half of Common Lisp. (Morris’s Corollary: “…including Common Lisp”) Hofstadter's Law: It always takes longer than you expect, even when you take into account Hofstadter's Law. Issawi’s Omelet Analogy: One cannot make an omelet without breaking eggs - but it is amazing how many eggs one can break without making a decent omelet. Jackson’s Rules of Optimization: Rule 1: Don't do it. Rule 2 (for experts only): Don't do it yet. Kaner’s Caveat: A program which perfectly meets a lousy specification is a lousy program. Liskov Substitution Principle (paraphrased): Functions that use pointers or references to base classes must be able to use objects of derived classes without knowing it Mason’s Maxim: Since human beings themselves are not fully debugged yet, there will be bugs in your code no matter what you do. Nils-Peter Nelson’s Nil I/O Rule: The fastest I/O is no I/O.    Occam's Razor: The simplest explanation is usually the correct one. Parkinson’s Law: Work expands so as to fill the time available for its completion. Quentin Tarantino’s Pie Principle: “…you want to go home have a drink and go and eat pie and talk about it.” (OK, he was talking about movies, not software, but I couldn’t find a “Q” quote about software. And wouldn’t it be cool to write a program so great that the users want to eat pie and talk about it?) Raymond’s Rule: Computer science education cannot make anybody an expert programmer any more than studying brushes and pigment can make somebody an expert painter.  Sowa's Law of Standards: Whenever a major organization develops a new system as an official standard for X, the primary result is the widespread adoption of some simpler system as a de facto standard for X. Turing’s Tenet: We shall do a much better programming job, provided we approach the task with a full appreciation of its tremendous difficulty, provided that we respect the intrinsic limitations of the human mind and approach the task as very humble programmers.  Udi Dahan’s Race Condition Rule: If you think you have a race condition, you don’t understand the domain well enough. These rules didn’t exist in the age of paper, there is no reason for them to exist in the age of computers. When you have race conditions, go back to the business and find out actual rules. Van Vleck’s Kvetching: We know about as much about software quality problems as they knew about the Black Plague in the 1600s. We've seen the victims' agonies and helped burn the corpses. We don't know what causes it; we don't really know if there is only one disease. We just suffer -- and keep pouring our sewage into our water supply. Wheeler’s Law: All problems in computer science can be solved by another level of indirection... Except for the problem of too many layers of indirection. Wheeler also said “Compatibility means deliberately repeating other people's mistakes.”. The Wrong Road Rule of Mr. X (anonymous): No matter how far down the wrong road you've gone, turn back. Yourdon’s Rule of Two Feet: If you think your management doesn't know what it's doing or that your organisation turns out low-quality software crap that embarrasses you, then leave. Zawinski's Law of Software Envelopment: Every program attempts to expand until it can read mail. Zawinski is also responsible for “Some people, when confronted with a problem, think 'I know, I'll use regular expressions.' Now they have two problems.” He once commented about X Windows widget toolkits: “Using these toolkits is like trying to make a bookshelf out of mashed potatoes.”

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  • 'Getting Started with Oracle Data Integrator 11g: A Hands-On Tutorial' book is now available

    - by Julien Testut
    We are pleased to announce the availability of the first book on Oracle Data Integrator published by Packt Publishing:  Getting Started with Oracle Data Integrator 11g – A Hands-On Tutorial Authors: Peter C. Boyd-Bowman, Christophe Dupupet, Denis Gray, David Hecksel,  Julien Testut, Bernard Wheeler. Congratulations to everyone who contributed to this book! You can get more information about 'Getting Started with Oracle Data Integrator 11g – A Hands-On Tutorial' including the table of contents and a sample chapter at http://www.packtpub.com/oracle-data-integrator-11g-getting-started/book. The book is available on Amazon.com, Amazon.co.uk, Barnes & Noble and Safari Books Online.

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  • How can I make my FireFox Browser AddOn Backwards Compatible?

    - by bwheeler96
    I'm making a firefox browser add-on, and I just got all of the code working fine, but it will only install in FireFox 16, and I want it to be compatible at least from 10+, has anyone dealt with this issue? I have my package.json pointing to my install.rdf, and my install.rdf clearly states target applications. Is there any additional setup I need? here is my package.json { "name": "firefox-ext", "license": "MPL 2.0", "author": "", "version": "0.1", "fullName": "firefox-ext", "id": "jid1-AMCw25iQJof53w", "description": "a basic add-on" } and here is my install.rdf. <?xml version="1.0"?> <RDF xmlns="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:em="http://www.mozilla.org/2004/em-rdf#"> <Description about="urn:mozilla:install-manifest"> <em:id>jid1-AMCw25iQJof53w</em:id> <em:name>Generic App</em:name> <em:version>1.0</em:version> <em:type>2</em:type> <em:creator>Brian Wheeler</em:creator> <em:description>Good Stuff</em:description> <em:targetApplication> <Description> <em:id>{ec8030f7-c20a-464f-9b0e-13a3a9e97384}</em:id> <em:minVersion>1.0</em:minVersion> <em:maxVersion>19.0</em:maxVersion> </Description> </em:targetApplication> </Description> </RDF> I'm using the CFX CLI Tools to make this, so everything has been built and tested with cfx init, cfx run, and cfx xpi I just can't figure out compatibility with anything other than 16. Also, major bonus points if someone could explain the advantages of a rapid release cycle, because it really seems to have shot 3rd party Mozilla developers in the foot in terms of software compatibility. Thanks, -Brian

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  • What are most demanded web-development languages today for startups?

    - by Liston Catch
    What technologies are in demand nowaydas for web-development for web-startups? For frontend its all clear: HTML5, JS, AJAX, JQuery. But what about backend? What languages (and frameworks) should I consider using? I am not asking "which language is best", I just need a list of modern languages and frameworks (and not Pascal, Delphi or Basic) which are demanded and well-payed. UPD: I totally decline the "it's all about logic, not about language. language is just a tool" concept. While THEORETICALLY it's true, in reality the time you need to study required frameworks is counted by months, so language DOES matter indeed. That's why I made this topic UPD 2: Mason Wheeler, so you seriously advice me to go for Delphi? You think its DEMANDED nowadays? Or you just tell me an exception which only confirms the rule? It's like "one guy won 100,000,000$ in lottery. Just for you to know that lottery is not a bad way to earn money."

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  • Building The Right SharePoint Team For Your Organization

    - by Mark Rackley
    I see the question posted fairly often asking what kind SharePoint team an organization should have. How many people do I need? What roles do I need to fill? What is best for my organization? Well, just like every other answer in SharePoint, the correct answer is “it depends”. Do you ever get sick of hearing that??? I know I do… So, let me give you my thoughts and opinions based upon my experience and what I’ve seen and let you come to your own conclusions. What are the possible SharePoint roles? I guess the first thing you need to understand are the different roles that exist in SharePoint (and their are LOTS). Remember, SharePoint is a massive beast and you will NOT find one person who can do it all. If you are hoping to find that person you will be sorely disappointed. For the most part this is true in SharePoint 2007 and 2010. However, generally things are improved in 2010 and easier for junior individuals to grasp. SharePoint Administrator The absolutely positively only role that you should not be without no matter the size of your organization or SharePoint deployment is a SharePoint administrator. These guys are essential to keeping things running and figuring out what’s wrong when things aren’t running well. These unsung heroes do more before 10 am than I do all day. The bad thing is, when these guys are awesome, you don’t even know they exist because everything is running so smoothly. You should definitely invest some time and money here to make sure you have some competent if not rockstar help. You need an admin who truly loves SharePoint and will go that extra mile when necessary. Let me give you a real world example of what I’m talking about: We have a rockstar admin… and I’m sure she’s sick of my throwing her name around so she’ll just have to live with remaining anonymous in this post… sorry Lori… Anyway! A couple of weeks ago our Server teams came to us and said Hi Lori, I’m finalizing the MOSS servers and doing updates that require a restart; can I restart them? Seems like a harmless request from your server team does it not? Sure, go ahead and apply the patches and reboot during our scheduled maintenance window. No problem? right? Sounded fair to me… but no…. not to our fearless SharePoint admin… I need a complete list of patches that will be applied. There is an update that is out there that will break SharePoint… KB973917 is the patch that has been shown to cause issues. What? You mean Microsoft released a patch that would actually adversely affect SharePoint? If we did NOT have a rockstar admin, our server team would have applied these patches and then when some problem occurred in SharePoint we’d have to go through the fun task of tracking down exactly what caused the issue and resolve it. How much time would that have taken? If you have a junior SharePoint admin or an admin who’s not out there staying on top of what’s going on you could have spent days tracking down something so simple as applying a patch you should not have applied. I will even go as far to say the only SharePoint rockstar you NEED in your organization is a SharePoint admin. You can always outsource really complicated development projects or bring in a rockstar contractor every now and then to make sure you aren’t way off track in other areas. For your day-to-day sanity and to keep SharePoint running smoothly, you need an awesome Admin. Some rockstars in this category are: Ben Curry, Mike Watson, Joel Oleson, Todd Klindt, Shane Young, John Ferringer, Sean McDonough, and of course Lori Gowin. SharePoint Developer Another essential role for your SharePoint deployment is a SharePoint developer. Things do start to get a little hazy here and there are many flavors of “developers”. Are you writing custom code? using SharePoint Designer? What about SharePoint Branding?  Are all of these considered developers? I would say yes. Are they interchangeable? I’d say no. Development in SharePoint is such a large beast in itself. I would say that it’s not so large that you can’t know it all well, but it is so large that there are many people who specialize in one particular category. If you are lucky enough to have someone on staff who knows it all well, you better make sure they are well taken care of because those guys are ready-made to move over to a consulting role and charge you 3 times what you are probably paying them. :) Some of the all-around rockstars are Eric Shupps, Andrew Connell (go Razorbacks), Rob Foster, Paul Schaeflein, and Todd Bleeker SharePoint Power User/No-Code Solutions Developer These SharePoint Swiss Army Knives are essential for quick wins in your organization. These people can twist the out-of-the-box functionality to make it do things you would not even imagine. Give these guys SharePoint Designer, jQuery, InfoPath, and a little time and they will create views, dashboards, and KPI’s that will blow your mind away and give your execs the “wow” they are looking for. Not only can they deliver that wow factor, but they can mashup, merge, and really help make your SharePoint application usable and deliver an overall better user experience. Before you hand off a project to your SharePoint Custom Code developer, let one of these rockstars look at it and show you what they can do (in probably less time). I would say the second most important role you can fill in your organization is one of these guys. Rockstars in this category are Christina Wheeler, Laura Rogers, Jennifer Mason, and Mark Miller SharePoint Developer – Custom Code If you want to really integrate SharePoint into your legacy systems, or really twist it and make it bend to your will, you are going to have to open up Visual Studio and write some custom code.  Remember, SharePoint is essentially just a big, huge, ginormous .NET application, so you CAN write code to make it do ANYTHING, but do you really want to spend the time and effort to do so? At some point with every other form of SharePoint development you are going to run into SOME limitation (SPD Workflows is the big one that comes to mind). If you truly want to knock down all the walls then custom development is the way to go. PLEASE keep in mind when you are looking for a custom code developer that a .NET developer does NOT equal a SharePoint developer. Just SOME of the things these guys write are: Custom Workflows Custom Web Parts Web Service functionality Import data from legacy systems Export data to legacy systems Custom Actions Event Receivers Service Applications (2010) These guys are also the ones generally responsible for packaging everything up into solution packages (you are doing that, right?). Rockstars in this category are Phil Wicklund, Christina Wheeler, Geoff Varosky, and Brian Jackett. SharePoint Branding “But it LOOKS like SharePoint!” Somebody call the WAAAAAAAAAAAAHMbulance…   Themes, Master Pages, Page Layouts, Zones, and over 2000 styles in CSS.. these guys not only have to be comfortable with all of SharePoint’s quirks and pain points when branding, but they have to know it TWICE for publishing and non-publishing sites.  Not only that, but these guys really need to have an eye for graphic design and be able to translate the ramblings of business into something visually stunning. They also have to be comfortable with XSLT, XML, and be able to hand off what they do to your custom developers for them to package as solutions (which you are doing, right?). These rockstars include Heater Waterman, Cathy Dew, and Marcy Kellar SharePoint Architect SharePoint Architects are generally SharePoint Admins or Developers who have moved into more of a BA role? Is that fair to say? These guys really have a grasp and understanding for what SharePoint IS and what it can do. These guys help you structure your farms to meet your needs and help you design your applications the correct way. It’s always a good idea to bring in a rockstar SharePoint Architect to do a sanity check and make sure you aren’t doing anything stupid.  Most organizations probably do not have a rockstar architect on staff. These guys are generally brought in at the deployment of a farm, upgrade of a farm, or for large development projects. I personally also find architects very useful for sitting down with the business to translate their needs into what SharePoint can do. A good architect will be able to pick out what can be done out-of-the-box and what has to be custom built and hand those requirements to the development Staff. Architects can generally fill in as an admin or a developer when needed. Some rockstar architects are Rick Taylor, Dan Usher, Bill English, Spence Harbar, Neil Hodgkins, Eric Harlan, and Bjørn Furuknap. Other Roles / Specialties On top of all these other roles you also get these people who specialize in things like Reporting, BDC (BCS in 2010), Search, Performance, Security, Project Management, etc... etc... etc... Again, most organizations will not have one of these gurus on staff, they’ll just pay out the nose for them when they need them. :) SharePoint End User Everyone else in your organization that touches SharePoint falls into this category. What they actually DO in SharePoint is determined by your governance and what permissions you give these guys. Hopefully you have these guys on a fairly short leash and are NOT giving them access to tools like SharePoint Designer. Sadly end users are the ones who truly make your deployment a success by using it, but are also your biggest enemy in breaking it.  :)  We love you guys… really!!! Okay, all that’s fine and dandy, but what should MY SharePoint team look like? It depends! Okay… Are you just doing out of the box team sites with no custom development? Then you are probably fine with a great Admin team and a great No-Code Solution Development team. How many people do you need? Depends on how busy you can keep them. Sorry, can’t answer the question about numbers without knowing your specific needs. I can just tell you who you MIGHT need and what they will do for you. I’ll leave you with what my ideal SharePoint Team would look like for a particular scenario: Farm / Organization Structure Dev, QA, and 2 Production Farms. 5000 – 10000 Users Custom Development and Integration with legacy systems Team Sites, My Sites, Intranet, Document libraries and overall company collaboration Team Rockstar SharePoint Administrator 2-3 junior SharePoint Administrators SharePoint Architect / Lead Developer 2 Power User / No-Code Solution Developers 2-3 Custom Code developers Branding expert With a team of that size and skill set, they should be able to keep a substantial SharePoint deployment running smoothly and meet your business needs. This does NOT mean that you would not need to bring in contract help from time to time when you need an uber specialist in one area. Also, this team assumes there will be ongoing development for the life of your SharePoint farm. If you are just going to be doing sporadic custom development, it might make sense to partner with an awesome firm that specializes in that sort of work (I can give you the name of a couple if you are interested).  Again though, the size of your team depends on the number of requests you are receiving and how much active deployment you are doing. So, don’t bring in a team that looks like this and then yell at me because they are sitting around with nothing to do or are so overwhelmed that nothing is getting done. I do URGE you to take the proper time to asses your needs and determine what team is BEST for your organization. Also, PLEASE PLEASE PLEASE do not skimp on the talent. When it comes to SharePoint you really do get what you pay for when it comes to employees, contractors, and software.  SharePoint can become absolutely critical to your business and because you skimped on hiring a developer he created a web part that brings down the farm because he doesn’t know what he’s doing, or you hire an admin who thinks it’s fine to stick everything in the same Content Database and then can’t figure out why people are complaining. SharePoint can be an enormous blessing to an organization or it’s biggest curse. Spend the time and money to do it right, or be prepared to spending even more time and money later to fix it.

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  • Informal Interviews: Just Relax (or Should I?)

    - by david.talamelli
    I was in our St Kilda Rd office last week and had the chance to meet up with Dan and David from GradConnection. I love what these guys are doing, their business has been around for two years and I really like how they have taken their own experiences from University found a niche in their market and have chased it. These guys are always networking. Whenever they come to Melbourne they send me a tweet to catch up, even though we often miss each other they are persistent. It sounds like their business is going from strength to strength and I have to think that success comes from their hard work and enthusiasm for their business. Anyway, before my meeting with ProGrad I noticed a tweet from Kevin Wheeler who was saying it was his last day in Melbourne - I sent him a message and we met up that afternoon for a coffee (I am getting to the point I promise). On my way back to the office after my meeting I was on a tram and was sitting beside a lady who was talking to her friend on her mobile. She had just come back from an interview and was telling her friend how laid back the meeting was and how she wasn't too sure of the next steps of the process as it was a really informal meeting. The recurring theme from this phone call was that 1) her and the interviewer got along really well and had a lot in common 2) the meeting was very informal and relaxed. I wasn't at the interview so I cannot say for certain, but in my experience regardless of the type of interview that is happening whether it is a relaxed interview at a coffee shop or a behavioural interview in an office setting one thing is consistent: the employer is assessing your ability to perform the role and fit into the company. Different interviewers I find have different interviewing styles. For example some interviewers may create a very relaxed environment in the thinking this will draw out less practiced answers and give a more realistic view of the person and their abilities while other interviewers may put the candidate "under the pump" to see how they react in a stressful situation. There are as many interviewing styles as there are interviewers. I think candidates regardless of the type of interview need to be professional and honest in both their skills/experiences, abilities and career plans (if you know what they are). Even though an interview may be informal, you shouldn't slip into complacency. You should not forget the end goal of the interview which is to get a job. Business happens outside of the office walls and while you may meet someone for a coffee it is still a business meeting no matter how relaxed the setting. You don't need to be stick in the mud and not let your personality shine through, but that first impression you make may play a big part in how far in the interview process you go. This article was originally posted on David Talamelli's Blog - David's Journal on Tap

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  • Problems starting autossh on boot [ubuntu]

    - by Ken
    I'm trying to automatically start an SSH tunnel to my server on boot from a ubuntu box. I have an ubuntu box that's mounted on an 18-wheeler and is networked behind an air card. The box hosts a mysql database that i'm trying to have replicated when the aircard is connected. As I can never be sure of my IP and how many or which routers I'm behind I'm connected to my replication server with an SSH tunnel. I got that working using the following command: ssh -R 3307:localhost:3307 [email protected] Now I'd like that to start whenever the box is, and be alive all the time, so I installed auto-ssh and setup this little script: ID=xkenneth HOST=erdosmiller.com AUTOSSH_POLL=15 AUTOSSH_PORT=20000 AUTOSSH_GATETIME=30 AUTOSSH_DEBUG=yes AUTOSSH_PATH=/usr/bin/ssh export AUTOSSH_POLL AUTOSSH_DEBUG AUTOSSH_PATH AUTOSSH_GATETIME AUTOSSH_PORT autossh -2 -fN -M 20000 -R 3307:localhost:3306 ${ID}@${HOST} I've tried putting this scrip in /etc/init.d/ and using a post-up command in /etc/network/interfaces as well as putting it in /etc/network/if-up.d/. In both situations the script starts on boot, but the tunnel doesn't appear to be correctly established. The script works when run manually.

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  • Filtering documents against a dictionary key in MongoDB

    - by Thomas
    I have a collection of articles in MongoDB that has the following structure: { 'category': 'Legislature', 'updated': datetime.datetime(2010, 3, 19, 15, 32, 22, 107000), 'byline': None, 'tags': { 'party': ['Peter Hoekstra', 'Virg Bernero', 'Alma Smith', 'Mike Bouchard', 'Tom George', 'Rick Snyder'], 'geography': ['Michigan', 'United States', 'North America'] }, 'headline': '2 Mich. gubernatorial candidates speak to students', 'text': [ 'BEVERLY HILLS, Mich. (AP) \u2014 Two Democratic and Republican gubernatorial candidates found common ground while speaking to private school students in suburban Detroit', "Democratic House Speaker state Rep. Andy Dillon and Republican U.S. Rep. Pete Hoekstra said Friday a more business-friendly government can help reduce Michigan's nation-leading unemployment rate.", "The candidates were invited to Detroit Country Day Upper School in Beverly Hills to offer ideas for Michigan's future.", 'Besides Dillon, the Democratic field includes Lansing Mayor Virg Bernero and state Rep. Alma Wheeler Smith. Other Republicans running are Oakland County Sheriff Mike Bouchard, Attorney General Mike Cox, state Sen. Tom George and Ann Arbor business leader Rick Snyder.', 'Former Republican U.S. Rep. Joe Schwarz is considering running as an independent.' ], 'dateline': 'BEVERLY HILLS, Mich.', 'published': datetime.datetime(2010, 3, 19, 8, 0, 31), 'keywords': "Governor's Race", '_id': ObjectId('4ba39721e0e16cb25fadbb40'), 'article_id': 'urn:publicid:ap.org:0611e36fb084458aa620c0187999db7e', 'slug': "BC-MI--Governor's Race,2nd Ld-Writethr" } If I wanted to write a query that looked for all articles that had at least 1 geography tag, how would I do that? I have tried writing db.articles.find( {'tags': 'geography'} ), but that doesn't appear to work. I've also thought about changing the search parameter to 'tags.geography', but am having a devil of a time figuring out what the search predicate would be.

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  • How To Configure Remote Desktop To Hyper-V Guest Virtual Machines

    - by Brian Jackett
    Configuring Remote Desktop (RDP) from a host Hyper-V machine to a guest virtual machine can be tricky, so this post is dedicated to the issues and resolution steps I went through to allow RDP.  Cutting to the point, below are the things to look for followed by some explanation about my scenario if you care to read.  This is not an exhaustive list of what is required, just the items that were causing problems for my particular scenario. Requirements Allow Remote Desktop Connections in guest OS. The network adapter type must allow communication with host machine (e.g. use an “Internal” virtual adapter.) If running Server 2008 R2 on guest, network discovery mode must be turned on. If running Server 2008 R2 on guest, the services supporting network discovery mode must be running: - DNS Client - Function Discovery Resource Publication - SSDP Discovery - UPnP Device Host My Environment     A quick word about my environment.  I am running Windows Server 2008 R2 with Hyper V on my laptop and numerous guest VMs running Windows Server 2003 R2 or Windows Server 2008 R2.  I run a domain controller VM and then 1 or 2 SharePoint servers depending on my work needs.  I’ve found this setup to work well except when it comes to the display window for my VMs. The Issue     Ever since I began running Hyper-V I haven’t been able to RDP to my guest VMs which means the resolution for my connection windows ha been limited to what the native Hyper-V connections allow.  During personal use I can put the resolution up to 1152 x 864, but during presentations I am usually limited to a measly 800 x 600.  That is until today when I decided to fully investigate why I couldn’t connect via RDP.     First a thank you to John Ross (@johnrossjr), Christina Wheeler (@cwheeler76) and Clayton Cobb (@warrtalon) for various suggestions while I was researching tonight.  As it turns out I had not 1, not 2, but 3 items preventing me from using RDP.  Let’s dig into the requirements above. Allow RDP Connection     This item I had previously taken care of, but it bears repeating because by default Windows Server 2008 R2 does not allow RDP connections.  Change the setting from “Don’t allow…” to whichever “Allow connections…” setting suits your needs.  I chose the less secure option as this is just my dev laptop. Network Adapter Type     When I originally configured my VMs I configured each to use 2 network adapters: one using the physical ethernet adapter for internet use and a virtual private adapter for communication between the VMs.  The connection for the ethernet adapter is an "”External” adapter and thus doesn’t connect between the host and guest.  The virtual private adapter allowed communication ONLY between the VMs and not to my host.  There is a third option “Internal” which allows communication between VMs as well as to the host.  After finding out this distinction I promptly created an Internal network adapter and assigned that to my VMs. Turn On Network Discovery     Seems like a pretty common sense thing, but in order to allow remote desktop connections the target computer must able to be found by the source computer (explained here.)  One of the settings that controls if a computer can be found on the network is aptly named Network Discovery.  By default Windows Server 2008 R2 turns Network Discovery off for security purposes.  To enable it open up the Network and Sharing Center.  Click “Change Advanced Sharing Settings” on the left.  On the following screen select “Turn on network discovery” for the currently used profile and click Save Settings.  You may notice though that your selection to turn on network discovery doesn’t save.  If this is the case then you most likely don’t have the supporting services running (as was my case.) Network Discovery Supporting Services     There are a total of 4 services (listed again below) that need to be running before you can turn on network discovery (explained here.)  The below images highlight these services.  In my guest VM I found that I had DNS Client already running while the other 3 were disabled.  I set them all to enabled and started the ones that were stopped.  After this change I returned to the Sharing settings screen and found that Network Discovery was turned on.  I’m not sure whether this was picking up my attempt to turn it on previously or if starting those services turned it on.  Either way the end result was a success. - DNS Client - Function Discovery Resource Publication - SSDP Discovery - UPnP Device Host Before and After Results     The first image is the smaller square shaped viewing window used by the Hyper-V native connection.  The second is the full-screen RDP connection in all its widescreen glory. Conclusion     Over the past few months I’ve found Hyper-V to be very useful for virtualizing my development environments, but I’ve also had a steep learning curve to get various items configured just right.  Allowing RDP connections to guest VMs was one area that I hadn’t been able to get right for the longest time.  Now that I resolved these issues I hope that others can avoid the pitfalls that I ran into.  If you know of any other items I left off feel free to let me know.        -Frog Out   Links Turning on Network Discovery http://sqlblog.com/blogs/john_paul_cook/archive/2009/08/15/remote-desktop-connection-on-windows-server-2008-r2.aspx Services required for Network Discovery http://social.technet.microsoft.com/Forums/en-US/winservergen/thread/2e1fea01-3f2b-4c46-a631-a8db34ed4f84

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  • .NET vs Windows 8

    - by Simon Cooper
    So, day 1 of DevWeek. Lots and lots of Windows 8 and WinRT, as you would expect. The keynote had some actual content in it, fleshed out some of the details of how your apps linked into the Metro infrastructure, and confirmed that there would indeed be an enterprise version of the app store available for Metro apps.) However, that's, not what I want to focus this post on. What I do want to focus on is this: Windows 8 does not make .NET developers obsolete. Phew! .NET in the New Ecosystem In all the hype around Windows 8 the past few months, a lot of developers have got the impression that .NET has been sidelined in Windows 8; C++ and COM is back in vogue, and HTML5 + JavaScript is the New Way of writing applications. You know .NET? It's yesterday's tech. Enter the 21st Century and write <div>! However, after speaking to people at the conference, and after a couple of talks by Dave Wheeler on the innards of WinRT and how .NET interacts with it, my views on the coming operating system have changed somewhat. To summarize what I've picked up, in no particular order (none of this is official, just my sense of what's been said by various people): Metro apps do not replace desktop apps. That is, Windows 8 fully supports .NET desktop applications written for every other previous version of Windows, and will continue to do so in the forseeable future. There are some apps that simply do not fit into Metro. They do not fit into the touch-based paradigm, and never will. Traditional desktop support is not going away anytime soon. The reason Silverlight has been hidden in all the Metro hype is that Metro is essentially based on Silverlight design principles. Silverlight developers will have a much easier time writing Metro apps than desktop developers, as they would already be used to all the principles of sandboxing and separation introduced with Silverlight. It's desktop developers who are going to have to adapt how they work. .NET + XAML is equal to HTML5 + JS in importance. Although the underlying WinRT system is built on C++ & COM, most application development will be done either using .NET or HTML5. Both systems have their own wrapper around the underlying WinRT infrastructure, hiding the implementation details. The CLR is unchanged; it's still the .NET 4 CLR, running IL in .NET assemblies. The thing that changes between desktop and Metro is the class libraries, which have more in common with the Silverlight libraries than the desktop libraries. In Metro, although all the types look and behave the same to callers, some of the core BCL types are now wrappers around their WinRT equivalents. These wrappers are then enhanced using standard .NET types and code to produce the Metro .NET class libraries. You can't simply port a desktop app into Metro. The underlying file IO, network, timing and database access is either completely different or simply missing. Similarly, although the UI is programmed using XAML, the behaviour of the Metro XAML is different to WPF or Silverlight XAML. Furthermore, the new design principles and touch-based interface for Metro applications demand a completely new UI. You will be able to re-use sections of your app encapsulating pure program logic, but everything else will need to be written from scratch. Microsoft has taken the opportunity to remove a whole raft of types and methods from the Metro framework that are obsolete (non-generic collections) or break the sandbox (synchronous APIs); if you use these, you will have to rewrite to use the alternatives, if they exist at all, to move your apps to Metro. If you want to write public WinRT components in .NET, there are some quite strict rules you have to adhere to. But the compilers know about these rules; you can write them in C# or VB, and the compilers will tell you when you do something that isn't allowed and deal with the translation to WinRT metadata rather than .NET assemblies. It is possible to write a class library that can be used in Metro and desktop applications. However, you need to be very careful not to use types that are available in one but not the other. One can imagine developers writing their own abstraction around file IO and UIs (MVVM anyone?) that can be implemented differently in Metro and desktop, but look the same within your shared library. So, if you're a .NET developer, you have a lot less to worry about. .NET is a viable platform on Metro, and traditional desktop apps are not going away. You don't have to learn HTML5 and JavaScript if you don't want to. Hurray!

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  • CLSF & CLK 2013 Trip Report by Jeff Liu

    - by jamesmorris
    This is a contributed post from Jeff Liu, lead XFS developer for the Oracle mainline Linux kernel team. Recently, I attended both the China Linux Storage and Filesystem workshop (CLSF), and the China Linux Kernel conference (CLK), which were held in Shanghai. Here are the highlights for both events. CLSF - 17th October XFS update (led by Jeff Liu) XFS keeps rapid progress with a lot of changes, especially focused on the infrastructure/performance improvements as well as  new feature development.  This can be reflected with a sample statistics among XFS/Ext4+JBD2/Btrfs via: # git diff --stat --minimal -C -M v3.7..v3.12-rc4 -- fs/xfs|fs/ext4+fs/jbd2|fs/btrfs XFS: 141 files changed, 27598 insertions(+), 19113 deletions(-) Ext4+JBD2: 39 files changed, 10487 insertions(+), 5454 deletions(-) Btrfs: 70 files changed, 19875 insertions(+), 8130 deletions(-) What made up those changes in XFS? Self-describing metadata(CRC32c). This is a new feature and it contributed about 70% code changes, it can be enabled via `mkfs.xfs -m crc=1 /dev/xxx` for v5 superblock. Transaction log space reservation improvements. With this change, we can calculate the log space reservation at mount time rather than runtime to reduce the the CPU overhead. User namespace support. So both XFS and USERNS can be enabled on kernel configuration begin from Linux 3.10. Thanks Dwight Engen's efforts for this thing. Split project/group quota inodes. Originally, project quota can not be enabled with group quota at the same time because they were share the same quota file inode, now it works but only for v5 super block. i.e, CRC enabled. CONFIG_XFS_WARN, an new lightweight runtime debugger which can be deployed in production environment. Readahead log object recovery, this change can speed up the log replay progress significantly. Speculative preallocation inode tracking, clearing and throttling. The main purpose is to deal with inodes with post-EOF space due to speculative preallocation, support improved quota management to free up a significant amount of unwritten space when at or near EDQUOT. It support backgroup scanning which occurs on a longish interval(5 mins by default, tunable), and on-demand scanning/trimming via ioctl(2). Bitter arguments ensued from this session, especially for the comparison between Ext4 and Btrfs in different areas, I have to spent a whole morning of the 1st day answering those questions. We basically agreed on XFS is the best choice in Linux nowadays because: Stable, XFS has a good record in stability in the past 10 years. Fengguang Wu who lead the 0-day kernel test project also said that he has observed less error than other filesystems in the past 1+ years, I own it to the XFS upstream code reviewer, they always performing serious code review as well as testing. Good performance for large/small files, XFS does not works very well for small files has already been an old story for years. Best choice (maybe) for distributed PB filesystems. e.g, Ceph recommends delopy OSD daemon on XFS because Ext4 has limited xattr size. Best choice for large storage (>16TB). Ext4 does not support a single file more than around 15.95TB. Scalability, any objection to XFS is best in this point? :) XFS is better to deal with transaction concurrency than Ext4, why? The maximum size of the log in XFS is 2038MB compare to 128MB in Ext4. Misc. Ext4 is widely used and it has been proved fast/stable in various loads and scenarios, XFS just need more customers, and Btrfs is still on the road to be a manhood. Ceph Introduction (Led by Li Wang) This a hot topic.  Li gave us a nice introduction about the design as well as their current works. Actually, Ceph client has been included in Linux kernel since 2.6.34 and supported by Openstack since Folsom but it seems that it has not yet been widely deployment in production environment. Their major work is focus on the inline data support to separate the metadata and data storage, reduce the file access time, i.e, a file access need communication twice, fetch the metadata from MDS and then get data from OSD, and also, the small file access is limited by the network latency. The solution is, for the small files they would like to store the data at metadata so that when accessing a small file, the metadata server can push both metadata and data to the client at the same time. In this way, they can reduce the overhead of calculating the data offset and save the communication to OSD. For this feature, they have only run some small scale testing but really saw noticeable improvements. Test environment: Intel 2 CPU 12 Core, 64GB RAM, Ubuntu 12.04, Ceph 0.56.6 with 200GB SATA disk, 15 OSD, 1 MDS, 1 MON. The sequence read performance for 1K size files improved about 50%. I have asked Li and Zheng Yan (the core developer of Ceph, who also worked on Btrfs) whether Ceph is really stable and can be deployed at production environment for large scale PB level storage, but they can not give a positive answer, looks Ceph even does not spread over Dreamhost (subject to confirmation). From Li, they only deployed Ceph for a small scale storage(32 nodes) although they'd like to try 6000 nodes in the future. Improve Linux swap for Flash storage (led by Shaohua Li) Because of high density, low power and low price, flash storage (SSD) is a good candidate to partially replace DRAM. A quick answer for this is using SSD as swap. But Linux swap is designed for slow hard disk storage, so there are a lot of challenges to efficiently use SSD for swap. SWAPOUT swap_map scan swap_map is the in-memory data structure to track swap disk usage, but it is a slow linear scan. It will become a bottleneck while finding many adjacent pages in the use of SSD. Shaohua Li have changed it to a cluster(128K) list, resulting in O(1) algorithm. However, this apporoach needs restrictive cluster alignment and only enabled for SSD. IO pattern In most cases, the swap io is in interleaved pattern because of mutiple reclaimers or a free cluster is shared by all reclaimers. Even though block layer can merge interleaved IO to some extent, but we cannot count on it completely. Hence the per-cpu cluster is added base on the previous change, it can help reclaimer do sequential IO and the block layer will be easier to merge IO. TLB flush: If we're reclaiming one active page, we should first move the page from active lru list to inactive lru list, and then reclaim the page from inactive lru to swap it out. During the process, we need to clear PTE twice: first is 'A'(ACCESS) bit, second is 'P'(PRESENT) bit. Processors need to send lots of ipi which make the TLB flush really expensive. Some works have been done to improve this, including rework smp_call_functiom_many() or remove the first TLB flush in x86, but there still have some arguments here and only parts of works have been pushed to mainline. SWAPIN: Page fault does iodepth=1 sync io, but it's a little waste if only issue a page size's IO. The obvious solution is doing swap readahead. But the current in-kernel swap readahead is arbitary(always 8 pages), and it always doesn't perform well for both random and sequential access workload. Shaohua introduced a new flag for madvise(MADV_WILLNEED) to do swap prefetch, so the changes happen in userspace API and leave the in-kernel readahead unchanged(but I think some improvement can also be done here). SWAP discard As we know, discard is important for SSD write throughout, but the current swap discard implementation is synchronous. He changed it to async discard which allow discard and write run in the same time. Meanwhile, the unit of discard is also optimized to cluster. Misc: lock contention For many concurrent swapout and swapin , the lock contention such as anon_vma or swap_lock is high, so he changed the swap_lock to a per-swap lock. But there still have some lock contention in very high speed SSD because of swapcache address_space lock. Zproject (led by Bob Liu) Bob gave us a very nice introduction about the current memory compression status. Now there are 3 projects(zswap/zram/zcache) which all aim at smooth swap IO storm and promote performance, but they all have their own pros and cons. ZSWAP It is implemented based on frontswap API and it uses a dynamic allocater named Zbud to allocate free pages. Zbud means pairs of zpages are "buddied" and it can only store at most two compressed pages in one page frame, so the max compress ratio is 50%. Each page frame is lru-linked and can do shink in memory pressure. If the compressed memory pool reach its limitation, shink or reclaim happens. It decompress the page frame into two new allocated pages and then write them to real swap device, but it can fail when allocating the two pages. ZRAM Acts as a compressed ramdisk and used as swap device, and it use zsmalloc as its allocator which has high density but may have fragmentation issues. Besides, page reclaim is hard since it will need more pages to uncompress and free just one page. ZRAM is preferred by embedded system which may not have any real swap device. Now both ZRAM and ZSWAP are in driver/staging tree, and in the mm community there are some disscussions of merging ZRAM into ZSWAP or viceversa, but no agreement yet. ZCACHE Handles file page compression but it is removed out of staging recently. From industry (led by Tang Jie, LSI) An LSI engineer introduced several new produces to us. The first is raid5/6 cards that it use full stripe writes to improve performance. The 2nd one he introduced is SandForce flash controller, who can understand data file types (data entropy) to reduce write amplification (WA) for nearly all writes. It's called DuraWrite and typical WA is 0.5. What's more, if enable its Dynamic Logical Capacity function module, the controller can do data compression which is transparent to upper layer. LSI testing shows that with this virtual capacity enables 1x TB drive can support up to 2x TB capacity, but the application must monitor free flash space to maintain optimal performance and to guard against free flash space exhaustion. He said the most useful application is for datebase. Another thing I think it's worth to mention is that a NV-DRAM memory in NMR/Raptor which is directly exposed to host system. Applications can directly access the NV-DRAM via a memory address - using standard system call mmap(). He said that it is very useful for database logging now. This kind of NVM produces are beginning to appear in recent years, and it is said that Samsung is building a research center in China for related produces. IMHO, NVM will bring an effect to current os layer especially on file system, e.g. its journaling may need to redesign to fully utilize these nonvolatile memory. OCFS2 (led by Canquan Shen) Without a doubt, HuaWei is the biggest contributor to OCFS2 in the past two years. They have posted 46 upstream patches and 39 patches have been merged. Their current project is based on 32/64 nodes cluster, but they also tried 128 nodes at the experimental stage. The major work they are working is to support ATS (atomic test and set), it can be works with DLM at the same time. Looks this idea is inspired by the vmware VMFS locking, i.e, http://blogs.vmware.com/vsphere/2012/05/vmfs-locking-uncovered.html CLK - 18th October 2013 Improving Linux Development with Better Tools (Andi Kleen) This talk focused on how to find/solve bugs along with the Linux complexity growing. Generally, we can do this with the following kind of tools: Static code checkers tools. e.g, sparse, smatch, coccinelle, clang checker, checkpatch, gcc -W/LTO, stanse. This can help check a lot of things, simple mistakes, complex problems, but the challenges are: some are very slow, false positives, may need a concentrated effort to get false positives down. Especially, no static checker I found can follow indirect calls (“OO in C”, common in kernel): struct foo_ops { int (*do_foo)(struct foo *obj); } foo->do_foo(foo); Dynamic runtime checkers, e.g, thread checkers, kmemcheck, lockdep. Ideally all kernel code would come with a test suite, then someone could run all the dynamic checkers. Fuzzers/test suites. e.g, Trinity is a great tool, it finds many bugs, but needs manual model for each syscall. Modern fuzzers around using automatic feedback, but notfor kernel yet: http://taviso.decsystem.org/making_software_dumber.pdf Debuggers/Tracers to understand code, e.g, ftrace, can dump on events/oops/custom triggers, but still too much overhead in many cases to run always during debug. Tools to read/understand source, e.g, grep/cscope work great for many cases, but do not understand indirect pointers (OO in C model used in kernel), give us all “do_foo” instances: struct foo_ops { int (*do_foo)(struct foo *obj); } = { .do_foo = my_foo }; foo>do_foo(foo); That would be great to have a cscope like tool that understands this based on types/initializers XFS: The High Performance Enterprise File System (Jeff Liu) [slides] I gave a talk for introducing the disk layout, unique features, as well as the recent changes.   The slides include some charts to reflect the performances between XFS/Btrfs/Ext4 for small files. About a dozen users raised their hands when I asking who has experienced with XFS. I remembered that when I asked the same question in LinuxCon/Japan, only 3 people raised their hands, but they are Chris Mason, Ric Wheeler, and another attendee. The attendee questions were mainly focused on stability, and comparison with other file systems. Linux Containers (Feng Gao) The speaker introduced us that the purpose for those kind of namespaces, include mount/UTS/IPC/Network/Pid/User, as well as the system API/ABI. For the userspace tools, He mainly focus on the Libvirt LXC rather than us(LXC). Libvirt LXC is another userspace container management tool, implemented as one type of libvirt driver, it can manage containers, create namespace, create private filesystem layout for container, Create devices for container and setup resources controller via cgroup. In this talk, Feng also mentioned another two possible new namespaces in the future, the 1st is the audit, but not sure if it should be assigned to user namespace or not. Another is about syslog, but the question is do we really need it? In-memory Compression (Bob Liu) Same as CLSF, a nice introduction that I have already mentioned above. Misc There were some other talks related to ACPI based memory hotplug, smart wake-affinity in scheduler etc., but my head is not big enough to record all those things. -- Jeff Liu

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