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  • Wordpress theme usage rights with GPLv2

    - by user3177012
    I've been searching for a great looking wordpress theme to use on a small magazine website idea that I had and I've just found one that would be ideal, with lots of blank spaces specifically designed for adverts - But then when I came to download it there was a notice: License: GPLv2 or later. Type: Non-Commercial Does this mean that you can use the theme but not use the advert space? What are the limitations?

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  • Creating a User-Friendly Website

    There are many people out there that would love to create their own website. Many of them are put off because they do not know how to design one. If you decide that you are going to pay for someone to design your ideal website, it is important to find out if the designer is reputable or not.

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  • New Exadata e-book!

    - by Javier Puerta
    Use this new e-book with your customers to learn why Oracle Exadata is the right choice for all database applications and deployments, including private cloud. Oracle Exadata is an engineered system ideal for consolidating databases and accelerating data warehousing performance. This new e-book provides access to a variety of materials including articles, white papers, workbooks, webcasts, and videos to help you achieve your goals

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  • Laptops with easy heat sink service?

    - by Niten
    Can you recommend a current laptop model with easy heat sink access – or better yet, a removable air intake filter – making it easy to periodically clean out the dust and lint that always packs up in these things? Every laptop I've owned has eventually overheated on account of a clogged heat sink. (I suppose it doesn't help that I have a cat who loves to hang out where I'm working, or that my laptop is almost always running.) One of the things I really love about my current system, a Dell Inspiron 1420n, is how easy it is to service its cooling system: whenever I notice the fan starting to work harder and the CPU temperature climbing higher than it should be, I merely have to unscrew a single panel from the bottom of the machine, clean out the heat sink, and then I'm good for another few months. Which current models of the "business laptop" variety offer similar easy cooling system service? I'm looking for something roughly along the lines of: 14- or 15-inch display Nehalem-based CPU Solid construction – magnesium chassis or better (like the Inspiron) TPM (for BitLocker) ideal, but not mandatory Docking adapter ideal, but not mandatory Good battery life For example, the ThinkPad T410 would have been my top choice, but it seems like it would be a serious chore to service its heat sink. For the current MacBook Pros it looks downright impossible. No matter how nice the laptop is in other respects, it'll be of no use to me when it's overheating. So, any suggestions? Thanks in advance... (I'm constantly surprised that customers and manufacturers don't pay more attention to this feature, at least in the business laptop subcategory. In the last couple months I've fixed two friends' laptops which were also overheating due to clogged cooling systems; clearly I'm not the only one affected by this.)

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  • Create Windows AMI with instance storage

    - by Jonathan Oliver
    I have a business use case and workflow where local/instance/ephemeral storage for an EC2 instance is ideal. Unfortunately I'm coupled to a Windows platform for this particular task and the EC2 Windows offering appears to have some deficiencies related to AMI creation. In essence, I'm trying to figure out if there's a way to attach local instance storage to a Windows EC2 instance using the typical command line interface (because the Amazon Website GUI doesn't support it) and then to somehow create an AMI based upon that. I've tried creating a snapshot and then creating a Windows AMI based upon the snapshot, but of course the docs say this is unsupported and makes an unbootable AMI. In short, here's what I'm trying to do: Be able to run a Windows instance (EBS/S3 instance doesn't matter) Attach local instance storage as drive D: Persist that configuration as an AMI such that I can start lots of them as necessary from either the GUI, command line, or REST API. Be able to take a launched instance, update software, shutdown, and create another AMI based upon that. Wash, rinse, repeat. One other potential option which isn't horrible, but isn't ideal is to create an AMI which has 2 EBS volumes already attached (system+apps and data). Essentially, every time I startup an instance based upon the AMI it'll create 2 new EBS volumes of pre-determined size. I'm trying to avoid that scenario if possible.

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  • Limiting interface bandwidth with tc under Linux

    - by Matt
    I have a linux router which has a 10GBe interface on the outside and bonded Gigabit ethernet interfaces on the inside. We have currently budget for 2GBit/s. If we exceed that rate by more than 5% average for a month then we'll be charged for the whole 10Gbit/s capacity. Quite a step up in dollar terms. So, I want to limit this to 2GBit/s on 10GBe interface. TBF filter might be ideal, but this comment is of concern. On all platforms except for Alpha, it is able to shape up to 1mbit/s of normal traffic with ideal minimal burstiness, sending out data exactly at the configured rates. Should I be using TBF or some other filter to apply this rate to the interface and how would I do it. I don't understand the example given here: Traffic Control HOWTO In particular "Example 9. Creating a 256kbit/s TBF" tc qdisc add dev eth0 handle 1:0 root dsmark indices 1 default_index 0 tc qdisc add dev eth0 handle 2:0 parent 1:0 tbf burst 20480 limit 20480 mtu 1514 rate 32000bps How is the 256K bit/s rate calculated? In this example, 32000bps = 32k bytes per second. Since tc uses bps = bytes per second. I guess burst and limit come into play but how would you go about choosing sensible numbers to reach the desired rate? This is not a mistake. I tested this and it gave a rate close to 256K but not exactly that.

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  • Should I partition a 1TB Hard Disk whose primary use is media storage?

    - by Senthil
    I am going to get a 1TB hard disk. I will be storing 1080p or 720p movies, high-bitrate music and pictures in it. I use my PC 90% of the time only to play/listen/see those. I am running out of space in my current HD so I am getting another one. My specs are 2.7GHz Dual Core, 512MB GeForce 9400GT, 2GB DDR2 RAM and all the proper matroska codecs/players. I guess that is enough to play 1080p movies withough a glitch, given an ideal hard disk. I've read about proper partitioning giving performance improvement etc.. I don't want my hard disk to be the bottleneck. Can someone tell me whether I should partition my 1TB hard disk into many drives? If I should, what is the ideal size of each partition? Smooth playing of movies is very important to me. Once I start filling up the disk, there is no turning back. So I want to get it right before I start. Thanks.

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  • Streaming music throughout the house on a budget?

    - by greggannicott
    I was wondering whether anyone knew of a way to stream music throughout a house on a budget? I want to avoid spending any money on this (eg. I don't want to buy a d-link style device). It would be ideal if I could use my existing hardware and some open source software. I have three old(ish) PCs knocking around. I'm happy to stick either Windows or Linux on them. They can all be hooked up to speakers. The ideal solution would result in: the same audio being heard from every device (eg. when you hear a beat on one device, you'd hear it at the exact same time on another (so you don't get any echo)) I'd be able to control the source application (eg. the songs lined up) with my iPhone. I realise I'm being cheeky with those two wishes - but you never know your luck. Am I asking for too much, or is there a piece of software/protocol out there with this purpose in mind? I've been searching for sometime now, but haven't had any joy. Thanks in advance.

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  • sys.dm_exec_query_stats interaction with recompilation

    - by Sam Saffron
    We use sys.dm_exec_query_stats to track down slow queries and queries that are IO offenders. This works great, we get a lot of very insightful stats. It is clear this is not as accurate as running a profiler trace, as you have no idea when SQL Server will decide to chuck out a an execution plan. We have quite a few queries where the wrong execution plan is cached. For example queries like the following: SELECT TOP 30 a.Id FROM Posts a JOIN Posts q ON q.Id = a.ParentId JOIN PostTags pt ON q.Id = pt.PostId WHERE a.PostTypeId = 2 AND a.DeletionDate IS NULL AND a.CommunityOwnedDate IS NULL AND a.CreationDate @date AND LEN(a.Body) 300 AND pt.Tag = @tag AND a.Score 0 ORDER BY a.Score DESC The problem is that the ideal plan really depends on the date selected (screenshot of ideal plan): However if the wrong plan is cached, it totally chokes when the date range is big: (notice the big fat lines) To overcome this we were recommended to use either OPTION (OPTIMIZE FOR UNKNOWN) or OPTION (RECOMPILE) OPTIMIZE FOR UNKNOWN results in a slightly better plan, which is far from optimal. Executions are tracked in sys.dm_exec_query_stats. RECOMPILE results in the best plan being chosen, however no execution counts and stats are tracked in sys.dm_exec_query_stats. Is there another DMV we could use to track stats on queries with OPTION (RECOMPILE)? Is this behavior by-design? Is there another way we can for recompilation while keeping stats tracked in sys.dm_exec_query_stats? Note: the framework will always execute parameterized queries using sp_executesql

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  • How to delete a podcast from an iPod and not have it reappear after syncing with iTunes?

    - by Mike
    Hi everyone, Say I have subscribe to a single podcast and I have Episode 1 and Episode 2 on my iPod. Each episode is 30 minutes long. I listen to the entirety of Episode 1 and just the first 15 minutes of Episode 2. I delete Episode 1 using my iPod's menu. Say Episode 3 has just come out. I want to be able to sync with iTunes, and after doing so, have just Episodes 2 and 3 on my iPod (with Episode 2 "half listened to"). How can I do this? Ideal state... Episode 1 = deleted Episode 2 = 15 minutes played already Episode 3 = unplayed I've found that if I set the Sync Podcast option in iTunes to "all new", I get: "All new" Episode 1 = not on the iPod Episode 2 = not on the iPod Episode 3 = unplayed and if I set the Sync Podcast option in iTunes to "all unplayed" "All unplayed" Episode 1 = unplayed Episode 2 = 15 minutes played already Episode 3 = unplayedv neither option does what I want. Is there an option to get my "ideal state"?

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  • How to inhibit suspend temporarily?

    - by Zorn
    I have searched around a bit for this and can't seem to find anything helpful. I have my PC running Ubuntu 12.10 set up to suspend after 30 minutes of inactivity. I don't want to change that, it works great most of the time. What I do want to do is disable the automatic suspend if a particular application is running. How can I do this? The closest thing I've found so far is to add a shell script in /usr/lib/pm-utils/sleep.d which checks if the application is running and returns 1 to indicate that suspend should be prevented. But it looks like the system then gives up on suspending automatically, instead of trying again after another 30 minutes. (As far as I can tell, if I move the mouse, that restarts the timer again.) It's quite likely the application will finish after a couple of hours, and I'd rather my PC then suspended automatically if I'm not using it at that point. (So I don't want to add a call to pm-suspend when the application finishes.) Is this possible? Any advice would be appreciated. Cheers. EDIT: As I noted in one of the comments below, what I actually wanted was to inhibit suspend when my PC was serving files over NFS; I just wanted to focus on the "suspend" part of the question because I already had an idea how to solve the NFS part. Using the 'xdotool' idea given in one of the answers, I have come up with the following script which I run from cron every few minutes. It's not ideal because it stops the screensaver kicking in as well, but it does work. I need to have a look at why 'caffeine' doesn't correctly re-enable suspend later on, then I could probably do better. Anyway, this does seem to work, so I'm including it here in case anyone else is interested. #!/bin/bash # If the output of this function changes between two successive runs of this # script, we inhibit auto-suspend. function check_activity() { /usr/sbin/nfsstat --server --list } # Prevent the automatic suspend from kicking in. function inhibit_suspend() { # Slightly jiggle the mouse pointer about; we do a small step and # reverse step to try to stop this being annoying to anyone using the # PC. TODO: This isn't ideal, apart from being a bit hacky it stops # the screensaver kicking in as well, when all we want is to stop # the PC suspending. Can 'caffeine' help? export DISPLAY=:0.0 xdotool mousemove_relative --sync -- 1 1 xdotool mousemove_relative --sync -- -1 -1 } LOG="$HOME/log/nfs-suspend-blocker.log" ACTIVITYFILE1="$HOME/tmp/nfs-suspend-blocker.current" ACTIVITYFILE2="$HOME/tmp/nfs-suspend-blocker.previous" echo "Started run at $(date)" >> "$LOG" if [ ! -f "$ACTIVITYFILE1" ]; then check_activity > "$ACTIVITYFILE1" exit 0; fi /bin/mv "$ACTIVITYFILE1" "$ACTIVITYFILE2" check_activity > "$ACTIVITYFILE1" if cmp --quiet "$ACTIVITYFILE1" "$ACTIVITYFILE2"; then echo "No activity detected since last run" >> "$LOG" else echo "Activity detected since last run; inhibiting suspend" >> "$LOG" inhibit_suspend fi

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  • SQL SERVER – Shard No More – An Innovative Look at Distributed Peer-to-peer SQL Database

    - by pinaldave
    There is no doubt that SQL databases play an important role in modern applications. In an ideal world, a single database can handle hundreds of incoming connections from multiple clients and scale to accommodate the related transactions. However the world is not ideal and databases are often a cause of major headaches when applications need to scale to accommodate more connections, transactions, or both. In order to overcome scaling issues, application developers often resort to administrative acrobatics, also known as database sharding. Sharding helps to improve application performance and throughput by splitting the database into two or more shards. Unfortunately, this practice also requires application developers to code transactional consistency into their applications. Getting transactional consistency across multiple SQL database shards can prove to be very difficult. Sharding requires developers to think about things like rollbacks, constraints, and referential integrity across tables within their applications when these types of concerns are best handled by the database. It also makes other common operations such as joins, searches, and memory management very difficult. In short, the very solution implemented to overcome throughput issues becomes a bottleneck in and of itself. What if database sharding was no longer required to scale your application? Let me explain. For the past several months I have been following and writing about NuoDB, a hot new SQL database technology out of Cambridge, MA. NuoDB is officially out of beta and they have recently released their first release candidate so I decided to dig into the database in a little more detail. Their architecture is very interesting and exciting because it completely eliminates the need to shard a database to achieve higher throughput. Each NuoDB database consists of at least three or more processes that enable a single database to run across multiple hosts. These processes include a Broker, a Transaction Engine and a Storage Manager.  Brokers are responsible for connecting client applications to Transaction Engines and maintain a global view of the network to keep track of the multiple Transaction Engines available at any time. Transaction Engines are in-memory processes that client applications connect to for processing SQL transactions. Storage Managers are responsible for persisting data to disk and serving up records to the Transaction Managers if they don’t exist in memory. The secret to NuoDB’s approach to solving the sharding problem is that it is a truly distributed, peer-to-peer, SQL database. Each of its processes can be deployed across multiple hosts. When client applications need to connect to a Transaction Engine, the Broker will automatically route the request to the most available process. Since multiple Transaction Engines and Storage Managers running across multiple host machines represent a single logical database, you never have to resort to sharding to get the throughput your application requires. NuoDB is a new pioneer in the SQL database world. They are making database scalability simple by eliminating the need for acrobatics such as sharding, and they are also making general administration of the database simpler as well.  Their distributed database appears to you as a user like a single SQL Server database.  With their RC1 release they have also provided a web based administrative console that they call NuoConsole. This tool makes it extremely easy to deploy and manage NuoDB processes across one or multiple hosts with the click of a mouse button. See for yourself by downloading NuoDB here. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: CodeProject, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQLServer, T SQL, Technology Tagged: NuoDB

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  • Do you want to be an ALM Consultant?

    - by Martin Hinshelwood
    Northwest Cadence is looking for our next great consultant! At Northwest Cadence, we have created a work environment that emphasizes excellence, integrity, and out-of-the-box thinking.  Our customers have high expectations (rightfully so) and we wouldn’t have it any other way!   Northwest Cadence has some of the most exciting customers I have ever worked with and even though I have only been here just over a month I have already: Provided training/consulting for 3 government departments Created and taught courseware for delivering Scrum to teams within a high profile multinational company Started presenting Microsoft's ALM Engagement Program  So if you are interested in helping companies build better software more efficiently, then.. Enquire at [email protected] Application Lifecycle Management (ALM) Consultant An ALM Consultant with a minimum of 8 years of relevant experience with Application Lifecycle Management, Visual Studio (including Visual Studio Team System) and software design is needed. Must provide thought leadership on best practices for enterprise architecture, understand the Microsoft technology solution stack, and have a thorough understanding of enterprise application integration. The ALM Practice Lead will play a central role in designing and implementing the overall ALM Practice strategy, including creating, updating, and delivering ALM courseware and consultancy engagements. This person will also provide project support, deliverables, and quality solutions on Visual Studio Team System that exceed client expectations. Engagements will vary and will involve providing expert training, consulting, mentoring, formulating technical strategies and policies and acting as a “trusted advisor” to customers and internal teams. Sound sense of business and technical strategy required. Strong interpersonal skills as well as solid strategic thinking are key. The ideal candidate will be capable of envisioning the solution based on the early client requirements, communicating the vision to both technical and business stakeholders, leading teams through implementation, as well as training, mentoring, and hands-on software development. The ideal candidate will demonstrate successful use of both agile and formal software development methods, enterprise application patterns, and effective leadership on prior projects. Job Requirements Minimum Education: Bachelor’s Degree (computer science, engineering, or math preferred). Locale / Travel: The Practice Lead position requires estimated 50% travel, most of which will be in the Continental US (a valid national Passport must be maintained).  This is a full time position and will be based in the Kirkland office. Preferred Education: Master’s Degree in Information Technology or Software Engineering; Premium Microsoft Certifications on .NET (MCSD) or MCPD or relevant experience; Microsoft Certified Trainer (MCT) or relevant experience. Minimum Experience and Skills: 7+ years experience with business information systems integration or custom business application design and development in a professional technology consulting, corporate MIS or software development environment. Essential Duties & Responsibilities: Provide training, consulting, and mentoring to organizations on topics that include Visual Studio Team System and ALM. Create content, including labs and demonstrations, to be delivered as training classes by Northwest Cadence employees. Lead development teams through the complete ALM and/or Visual Studio Team System solution. Be able to communicate in detail how a solution will integrate into the larger technical problem space for large, complex enterprises. Define technical solution requirements. Provide guidance to the customer and project team with respect to technical feasibility, complexity, and level of effort required to deliver a custom solution. Ensure that the solution is designed, developed and deployed in accordance with the agreed upon development work plan. Create and deliver weekly status reports of training and/or consulting progress. Engagement Responsibilities: · Provide a strong desire to provide thought leadership related to technology and to help grow the business. · Work effectively and professionally with employees at all levels of a customer’s organization. · Have strong verbal and written communication skills. · Have effective presentation, organizational and planning skills. · Have effective interpersonal skills and ability to work in a team environment. Enquire at [email protected]

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  • How can I best implement 'cache until further notice' with memcache in multiple tiers?

    - by ajreal
    the term "client" used here is not referring to client's browser, but client server Before cache workflow 1. client make a HTTP request --> 2. server process --> 3. store parsed results into memcache for next use (cache indefinitely) --> 4. return results to client --> 5. client get the result, store into client's local memcache with TTL After cache workflow 1. another client make a HTTP request --> 2. memcache found return memcache results to client --> 3. client get the result, store into client's local memcache with TTL TTL = time to live Is possible for me to know when the data was updated, and to expire relevant memcache(s) accordingly. However, the pitfalls on client site cache TTL Any data update before the TTL is not pick-up by client memcache. In reverse manner, where there is no update, client memcache still expire after the TTL First request (or concurrent requests) after cache TTL will get throttle as it need to repeat the "Before cache workflow" In the event where client require several HTTP requests on a single web page, it could be very bad in performance. Ideal solution should be client to cache indefinitely until further notice. Here are the three proposals about futher notice Proposal 1 : Make use on HTTP header (current implementation) 1. client sent HTTP request last modified time header 2. server check if last data modified time=last cache time return status 304 3. client based on header to decide further processing GOOD? ---- - save some parsing for client - lesser data transfer BAD? ---- - fire a HTTP request is still slow - server end still need to process lots of requests Proposal 2 : Consistently issue a HTTP request to check all data group last modified time 1. client fire a HTTP request 2. server to return last modified time for all data group 3. client compare local last cache time with the result 4. if data group last cache time < server last modified time then request again for that data group only GOOD? ---- - only fetch what is no up-to-date - less requests for server BAD? ---- - every web page require a HTTP request Proposal 3 : Tell client when new data is available (Push) 1. when server end notice there is a change on a data group 2. notify clients on the changes 3. help clients to fetch again data 4. then reset client local memcache after data is parsed GOOD? ---- - let the cache act/behave like a true cache BAD? ---- - encourage race condition My preference is on proposal 3, and something like Gearman could be ideal Where there is a change, Gearman server to sent the task to multiple clients (workers). Am I crazy? (I know my first question is a bit crazy)

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  • The long road to bug-free software

    - by Tony Davis
    The past decade has seen a burgeoning interest in functional programming languages such as Haskell or, in the Microsoft world, F#. Though still on the periphery of mainstream programming, functional programming concepts are gradually seeping into the imperative C# language (for example, Lambda expressions have their root in functional programming). One of the more interesting concepts from functional programming languages is the use of formal methods, the lofty ideal behind which is bug-free software. The idea is that we write a specification that describes exactly how our function (say) should behave. We then prove that our function conforms to it, and in doing so have proved beyond any doubt that it is free from bugs. All programmers already use one form of specification, specifically their programming language's type system. If a value has a specific type then, in a type-safe language, the compiler guarantees that value cannot be an instance of a different type. Many extensions to existing type systems, such as generics in Java and .NET, extend the range of programs that can be type-checked. Unfortunately, type systems can only prevent some bugs. To take a classic problem of retrieving an index value from an array, since the type system doesn't specify the length of the array, the compiler has no way of knowing that a request for the "value of index 4" from an array of only two elements is "unsafe". We restore safety via exception handling, but the ideal type system will prevent us from doing anything that is unsafe in the first place and this is where we start to borrow ideas from a language such as Haskell, with its concept of "dependent types". If the type of an array includes its length, we can ensure that any index accesses into the array are valid. The problem is that we now need to carry around the length of arrays and the values of indices throughout our code so that it can be type-checked. In general, writing the specification to prove a positive property, even for a problem very amenable to specification, such as a simple sorting algorithm, turns out to be very hard and the specification will be different for every program. Extend this to writing a specification for, say, Microsoft Word and we can see that the specification would end up being no simpler, and therefore no less buggy, than the implementation. Fortunately, it is easier to write a specification that proves that a program doesn't have certain, specific and undesirable properties, such as infinite loops or accesses to the wrong bit of memory. If we can write the specifications to prove that a program is immune to such problems, we could reuse them in many places. The problem is the lack of specification "provers" that can do this without a lot of manual intervention (i.e. hints from the programmer). All this might feel a very long way off, but computing power and our understanding of the theory of "provers" advances quickly, and Microsoft is doing some of it already. Via their Terminator research project they have started to prove that their device drivers will always terminate, and in so doing have suddenly eliminated a vast range of possible bugs. This is a huge step forward from saying, "we've tested it lots and it seems fine". What do you think? What might be good targets for specification and verification? SQL could be one: the cost of a bug in SQL Server is quite high given how many important systems rely on it, so there's a good incentive to eliminate bugs, even at high initial cost. [Many thanks to Mike Williamson for guidance and useful conversations during the writing of this piece] Cheers, Tony.

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  • The long road to bug-free software

    - by Tony Davis
    The past decade has seen a burgeoning interest in functional programming languages such as Haskell or, in the Microsoft world, F#. Though still on the periphery of mainstream programming, functional programming concepts are gradually seeping into the imperative C# language (for example, Lambda expressions have their root in functional programming). One of the more interesting concepts from functional programming languages is the use of formal methods, the lofty ideal behind which is bug-free software. The idea is that we write a specification that describes exactly how our function (say) should behave. We then prove that our function conforms to it, and in doing so have proved beyond any doubt that it is free from bugs. All programmers already use one form of specification, specifically their programming language's type system. If a value has a specific type then, in a type-safe language, the compiler guarantees that value cannot be an instance of a different type. Many extensions to existing type systems, such as generics in Java and .NET, extend the range of programs that can be type-checked. Unfortunately, type systems can only prevent some bugs. To take a classic problem of retrieving an index value from an array, since the type system doesn't specify the length of the array, the compiler has no way of knowing that a request for the "value of index 4" from an array of only two elements is "unsafe". We restore safety via exception handling, but the ideal type system will prevent us from doing anything that is unsafe in the first place and this is where we start to borrow ideas from a language such as Haskell, with its concept of "dependent types". If the type of an array includes its length, we can ensure that any index accesses into the array are valid. The problem is that we now need to carry around the length of arrays and the values of indices throughout our code so that it can be type-checked. In general, writing the specification to prove a positive property, even for a problem very amenable to specification, such as a simple sorting algorithm, turns out to be very hard and the specification will be different for every program. Extend this to writing a specification for, say, Microsoft Word and we can see that the specification would end up being no simpler, and therefore no less buggy, than the implementation. Fortunately, it is easier to write a specification that proves that a program doesn't have certain, specific and undesirable properties, such as infinite loops or accesses to the wrong bit of memory. If we can write the specifications to prove that a program is immune to such problems, we could reuse them in many places. The problem is the lack of specification "provers" that can do this without a lot of manual intervention (i.e. hints from the programmer). All this might feel a very long way off, but computing power and our understanding of the theory of "provers" advances quickly, and Microsoft is doing some of it already. Via their Terminator research project they have started to prove that their device drivers will always terminate, and in so doing have suddenly eliminated a vast range of possible bugs. This is a huge step forward from saying, "we've tested it lots and it seems fine". What do you think? What might be good targets for specification and verification? SQL could be one: the cost of a bug in SQL Server is quite high given how many important systems rely on it, so there's a good incentive to eliminate bugs, even at high initial cost. [Many thanks to Mike Williamson for guidance and useful conversations during the writing of this piece] Cheers, Tony.

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  • c# Named Pipe Asynchronous Peeking

    - by KJ Tsanaktsidis
    Hey all, I need to find a way to be notified when a System.IO.Pipe.NamedPipeServerStream opened in asynchronous mode has more data available for reading on it- a WaitHandle would be ideal. I cannot simply use BeginRead() to obtain such a handle because it's possible that i might be signaled by another thread which wants to write to the pipe- so I have to release the lock on the pipe and wait for the write to be complete, and NamedPipeServerStream doesnt have a CancelAsync method. I also tried calling BeginRead(), then calling the win32 function CancelIO on the pipe if the thread gets signaled, but I don't think this is an ideal solution because if CancelIO is called just as data is arriving and being processed, it will be dropped- I still wish to keep this data, but process it at a later time, after the write. I suspect the win32 function PeekNamedPipe might be useful but i'd like to avoid having to continuously poll for new data with it. In the likley event that the above text is a bit unclear, here's roughly what i'd like to be able to do... NamedPipeServerStream pipe; ManualResetEvent WriteFlag; //initialise pipe lock (pipe) { //I wish this method existed WaitHandle NewDataHandle = pipe.GetDataAvailableWaithandle(); Waithandle[] BreakConditions = new Waithandle[2]; BreakConditions[0] = NewDataHandle; BreakConditions[1] = WriteFlag; int breakcode = WaitHandle.WaitAny(BreakConditions); switch (breakcode) { case 0: //do a read on the pipe break; case 1: //break so that we release the lock on the pipe break; } }

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  • Finding most efficient transmission size in varying network latency scenarios

    - by rwmnau
    I'm building a .NET remoting client/server that will be transmitting thousands of files, of varying sizes (everything from a few bytes to hundreds of MB), and I'm curious about a general method for finding the appropriate transmission size. As I see it, there's the following tradeoff: Serialize entire file into a transmission object and transmit at once, regardless of size. This would be the fastest, but a failure during tranmission requires that the whole file be re-transmitted. If the file size is larger than something small (like 4KB), break it into 4KB chunks and transmit those, re-assembling on the server. In addition to the complexity of this, it's slower because of continued round-trips and acknowledgements, though a failure of any one piece doesn't waste much time. The ideal transmission method (when taking into account negotiation latency vs. failure rate) is somewhere in between, and I'm wondering about how to find out the best size for that particular client. Do I have some dynamic tuning step in my transmission that looks at the current bytes/second average, and then raises the transmission size until the speed starts to drop (failures overwhelm negotiation cost)? Or is there some other method for determining ideal transmission size? The application will be multi-threaded, so number of threads also factors in to the calculation. I'm not looking for a formula (though I'll take one if you've got it), but just what to consider as I create this process.

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  • How do I achieve a 'select or insert' task using LINQ to EF?

    - by ProfK
    I have an import process with regions, locations, and shifts, where a Shift object has a Location property, and a Location object has a Region property. If a region name does not exist, I create the region, and like wise a location. I thought I could neatly encapsulate the 'Select if exists, or create' logic into helper classes for Region and Location, but if I use local data contexts in these classes I run into attach and detach overheads that become unpleasent. If I include a data context dependency in these classes, my encapsulation feels broken. What is the ideal method for achieving this, or where is the ideal place to place this functionality? In my example I have leaned heavily on the foreign key crutch provided with .NET 4.0, and simply avoided using entities in favour of direct foreign key values, but this is starting to smell. Example: public partial class ActivationLocation { public static int GetOrCreate(int regionId, string name) { using (var ents = new PvmmsEntities()) { var loc = ents.ActivationLocations.FirstOrDefault(x => x.RegionId == regionId && x.Name == name); if (loc == null) { loc = new ActivationLocation {RegionId = regionId, Name = name}; ents.AddToActivationLocations(loc); ents.SaveChanges(SaveOptions.AcceptAllChangesAfterSave); } return loc.LocationId; } } }

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  • Building Web Application project using MSBuild from command line on 64-bit: missing targets file

    - by James Allen
    Building a solution containing a web application project using MSBuild from powershell like this: msbuild "/p:OutDir=$build_dir\" $solution_file Works fine for me on 32-bit, but on a 64-bit machine I am running into this error: error MSB4019: The imported project "C:\Program Files\MSBuild\Microsoft\VisualStudio\v9.0\WebApplications\Microsoft.WebApplication.targets" was not found. Confirm that the path in the declaration is correct, and that the file exists on disk. I am using Visual Studio 2008 and powershell v2. The problem has already been documented here and here. Basically on 64-bit install of VS, the Microsoft.WebApplication.targets needed by MSBuild is in the Program Files(x86) dir, not the Program Files dir, but MSBuild doesn't recognise this and so looks in the wrong place. The two solutions are not ideal: Manually copy the file on 64-bit from Program Files(x86) to Program Files. This is a poor solution - every dev will have to do this manually. Manually edit the csproj file so MSBuild looks in the right place. Again not ideal: I would rather not have to get everyone on 64bit to manually edit csproj files on every new project. e.g. <Import Project="$(MSBuildExtensionsPathx86)\$(WebAppTargetsSuffix)" Condition="Exists('$(MSBuildExtensionsPathx86)\$(WebAppTargetsSuffix)')" /> Ideally I want a way to tell MSBuild to import the target file form the right place from the command line but I can't work out how to do that. Any solutions?

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  • Extending ASP.NET role providers

    - by Quick Joe Smith
    Because the RoleProvider interface seems to treat roles as nothing more than simple strings, I'm wondering if there is any non-hacky way to apply an optional value for a role on a per-user basis. Our current login management system implements roles as key-value pairs, where the value part is optional and usually used to clarify or limit the permissions granted by a role. For example, a role 'editor' might contain a user 'barry', but for 'barry' it will have an optional value 'raptors', which the system would interpret to mean that Barry can only edit articles filed under the 'raptors' category. I have seen elsewhere a suggestion to simply create additional delimited roles, such as 'editor.raptors' or somesuch. That's not really going to be ideal because it would bloat the number of roles greatly, and I can tell it's going to be a very hard sell to replace our current implementation (which is also very less than ideal, but has the advantage of being custom made to work with our user database). I can tell already that the concatenation method mentioned above is going to involve a lot of tedious string-splitting and partial matching. Is there a better way?

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  • How to set default date in date_select helper in Rails

    - by brad
    I'm trying to set up a date of birth helper in my Rails app (2.3.5). At present it is like so. <%= f.date_select :date_of_birth, :start_year => Time.now.year - 110, :end_year => Time.now.year %> This generates a perfectly functional set of date fields that work just fine but.... They default to today's date which is not ideal for a date of birth field (I'm not sure what is but unless you're running a neonatal unit today's date seems less than ideal). I want it to read Jan 1 2010 instead (or 2011 or whatever year it happens to be). Using the :default option has proven unsuccessful. I've tried many possibilities including; <%= f.date_select :date_of_birth, :default => {:year => Time.now.year, :month => 'Jan', :day => 1}, :start_year => Time.now.year - 110, :end_year => Time.now.year %> and <%= f.date_select :date_of_birth, :default => Time.local(2010,'Jan',1), :start_year => Time.now.year - 110, :end_year => Time.now.year %> None of this changes the behaviour of the first example. Does the default option actually work as described? It seems that this should be a fairly straightforward thing to do. Ta.

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  • How would I go about sharing variables in a class with Lua?

    - by Nicholas Flynt
    I'm fairly new to Lua, I've been working on trying to implement Lua scripting for logic in a Game Engine I'm putting together. I've had no trouble so far getting Lua up and running through the engine, and I'm able to call Lua functions from C and C functions from Lua. The way the engine works now, each Object class contains a set of variables that the engine can quickly iterate over to draw or process for physics. While game objects all need to access and manipulate these variables in order for the Game Engine itself to see any changes, they are free to create their own variables, a Lua is exceedingly flexible about this so I don't forsee any issues. Anyway, currently the Game Engine side of things are sitting in C land, and I really want them to stay there for performance reasons. So in an ideal world, when spawning a new game object, I'd need to be able to give Lua read/write access to this standard set of variables as part of the Lua object's base class, which its game logic could then proceed to run wild with. So far, I'm keeping two separate tables of objects in place-- Lua spawns a new game object which adds itself to a numerically indexed global table of objects, and then proceeds to call a C++ function, which creates a new GameObject class and registers the Lua index (an int) with the class. So far so good, C++ functions can now see the Lua object and easily perform operations or call functions in Lua land using dostring. What I need to do now is take the C++ variables, part of the GameObject class, and expose them to Lua, and this is where google is failing me. I've encountered a very nice method here which details the process using tags, but I've read that this method is deprecated in favor of metatables. What is the ideal way to accomplish this? Is it worth the hassle of learning how to pass class definitions around using libBind or some equivalent method, or is there a simple way I can just register each variable (once, at spawn time) with the global lua object? What's the "current" best way to do this, as of Lua 5.1.4?

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  • [UNIX] Sort lines of massive file by number of words on line (ideally in parallel)

    - by conradlee
    I am working on a community detection algorithm for analyzing social network data from Facebook. The first task, detecting all cliques in the graph, can be done efficiently in parallel, and leaves me with an output like this: 17118 17136 17392 17064 17093 17376 17118 17136 17356 17318 12345 17118 17136 17356 17283 17007 17059 17116 Each of these lines represents a unique clique (a collection of node ids), and I want to sort these lines in descending order by the number of ids per line. In the case of the example above, here's what the output should look like: 17118 17136 17356 17318 12345 17118 17136 17356 17283 17118 17136 17392 17064 17093 17376 17007 17059 17116 (Ties---i.e., lines with the same number of ids---can be sorted arbitrarily.) What is the most efficient way of sorting these lines. Keep the following points in mind: The file I want to sort could be larger than the physical memory of the machine Most of the machines that I'm running this on have several processors, so a parallel solution would be ideal An ideal solution would just be a shell script (probably using sort), but I'm open to simple solutions in python or perl (or any language, as long as it makes the task simple) This task is in some sense very easy---I'm not just looking for any old solution, but rather for a simple and above all efficient solution

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