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  • Find original owning process of a Linux socket

    - by Rob H
    In Linux and other UNIX-like operating systems, it is possible for two (or more) processes to share an Internet socket. Assuming there is no parent-child relationship between the processes, is there any way to tell what process originally created a socket? Clarification: I need to determine this from "outside" the processes using the /proc filesystem or similar. I can't modify the code of the processes. I can already tell what processes are sharing sockets by reading /proc/<pid>/fd, but that doesn't tell me what process originally created them.

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  • Serializing to JSON in jQuery

    - by Herb Caudill
    I know how to serialize an object to JSON in ASP.NET Ajax, but I'm trying to do things on the client in a less Microsoft-specific way. I'm using jQuery. Is there a "standard" way to do this? My specific situation: I have an array defined something like this: var countries = new Array(); countries[0] = 'ga'; countries[1] = 'cd'; ... and I need to turn this into a string to pass to $.ajax() like this: $.ajax({ type: "POST", url: "Concessions.aspx/GetConcessions", data: "{'countries':['ga','cd']}", ... Edit (clarification) I realize there are a number of JSON libraries out there, but I'd like to avoid introducing a new dependency (if I'm going to do that, I might as well use ASP.NET Ajax's built-in JSON serializer).

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  • Changing class of h2 inside specific div

    - by user1985060
    I want to make it so that everytime you click on an 'h2' tag, the 'input' inside gets selected and the 'h2' tag changes background, but if another 'h2' tag is clicked, the current highlight and 'input' selection changes accordingly. problem is that I have 3 different that do the same and with my code all the 3 forms are affected rather one. How do i limit my changes to only be contained to that form. Here is some code for clarification ' <form> ... <h2 onclick="document.getElementById(1001).checked='True' $('h2').removeClass('selected'); $(this).addClass('selected'); "> CONTENT <input type="radio" name="radio" id="1001" value="1001" /> </h2> ... </form>

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  • SQL SERVER – WRITELOG – Wait Type – Day 17 of 28

    - by pinaldave
    WRITELOG is one of the most interesting wait types. So far we have seen a lot of different wait types, but this log type is associated with log file which makes it interesting to deal with. From Book On-Line: WRITELOG Occurs while waiting for a log flush to complete. Common operations that cause log flushes are checkpoints and transaction commits. WRITELOG Explanation: This wait type is usually seen in the heavy transactional database. When data is modified, it is written both on the log cache and buffer cache. This wait type occurs when data in the log cache is flushing to the disk. During this time, the session has to wait due to WRITELOG. I have recently seen this wait type’s persistence at my client’s place, where one of the long-running transactions was stopped by the user causing it to roll back. In the future, I will see if I could re-create this situation once again on my machine to validate the relation. Reducing WRITELOG wait: There are several suggestions to reduce this wait stats: Move Transaction Log to Separate Disk from mdf and other files. Avoid cursor-like coding methodology and frequent committing of statements. Find the most active file based on IO stall time based on the script written over here. You can also use fn_virtualfilestats to find IO-related issues using the script mentioned over here. Check the IO-related counters (PhysicalDisk:Avg.Disk Queue Length, PhysicalDisk:Disk Read Bytes/sec and PhysicalDisk :Disk Write Bytes/sec) for additional details. Read about them over here. There are two excellent resources by Paul Randal, I suggest you understand the subject from those videos. The links to videos are here and here. Note: The information presented here is from my experience and there is no way that I claim it to be accurate. I suggest reading Book OnLine for further clarification. All the discussion of Wait Stats in this blog is generic and varies from system to system. It is recommended that you test this on a development server before implementing it to a production server. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQL Wait Stats, SQL Wait Types, T SQL, Technology

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  • SQL SERVER – FT_IFTS_SCHEDULER_IDLE_WAIT – Full Text – Wait Type – Day 13 of 28

    - by pinaldave
    In the last few days during this series, I got many question about this Wait type. It would be great if you read my original related wait stats query in the first post because I have filtered it out in WHERE clause. However, I still get questions about this being one of the most wait types they encounter. The truth is, this is a background task processing and it really does not matter and it should be filtered out. There are many new Wait types related to Full Text Search that are introduced in SQL Server 2008. If you run the following query, you will be able to find them in the list. Currently there is not enough information for all of them available on BOL or any other place. But don’t worry; I will write an in-depth article when I learn more about them. SELECT * FROM sys.dm_os_wait_stats WHERE wait_type LIKE 'FT_%' The result set will contain following rows. FT_RESTART_CRAWL FT_METADATA_MUTEX FT_IFTSHC_MUTEX FT_IFTSISM_MUTEX FT_IFTS_RWLOCK FT_COMPROWSET_RWLOCK FT_MASTER_MERGE FT_IFTS_SCHEDULER_IDLE_WAIT We have understood so far that there is not much information available. But the problem is when you have this Wait type, what should you do?  The answer is to filter them out for the moment (i.e, do not pay attention on them) and focus on other pressing issues in wait stats or performance tuning. Here are two of my informal suggestions, which are totally independent from wait stats: Turn off the Full Text Search service in your system if you are  not necessarily using it on your server. Learn proper Full Text Search methodology. You can get Michael Coles’ book: Pro Full-Text Search in SQL Server 2008. Now I invite you to speak out your suggestions or any input regarding Full Text-related best practices and wait stats issue. Please leave a comment. Note: The information presented here is from my experience and there is no way that I claim it to be accurate. I suggest reading Book OnLine for further clarification. All the discussions of Wait Stats in this blog are generic and vary from system to system. It is recommended that you test this on a development server before implementing it to a production server. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQL Wait Stats, SQL Wait Types, T SQL, Technology

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  • SQL SERVER – LOGBUFFER – Wait Type – Day 18 of 28

    - by pinaldave
    At first, I was not planning to write about this wait type. The reason was simple- I have faced this only once in my lifetime so far maybe because it is one of the top 5 wait types. I am not sure if it is a common wait type or not, but in the samples I had it really looks rare to me. From Book On-Line: LOGBUFFER Occurs when a task is waiting for space in the log buffer to store a log record. Consistently high values may indicate that the log devices cannot keep up with the amount of log being generated by the server. LOGBUFFER Explanation: The book online definition of the LOGBUFFER seems to be very accurate. On the system where I faced this wait type, the log file (LDF) was put on the local disk, and the data files (MDF, NDF) were put on SanDrives. My client then was not familiar about how the file distribution was supposed to be. Once we moved the LDF to a faster drive, this wait type disappeared. Reducing LOGBUFFER wait: There are several suggestions to reduce this wait stats: Move Transaction Log to Separate Disk from mdf and other files. (Make sure your drive where your LDF is has no IO bottleneck issues). Avoid cursor-like coding methodology and frequent commit statements. Find the most-active file based on IO stall time, as shown in the script written over here. You can also use fn_virtualfilestats to find IO-related issues using the script mentioned over here. Check the IO-related counters (PhysicalDisk:Avg.Disk Queue Length, PhysicalDisk:Disk Read Bytes/sec and PhysicalDisk :Disk Write Bytes/sec) for additional details. Read about them over here. If you have noticed, my suggestions for reducing the LOGBUFFER is very similar to WRITELOG. Although the procedures on reducing them are alike, I am not suggesting that LOGBUFFER and WRITELOG are same wait types. From the definition of the two, you will find their difference. However, they are both related to LOG and both of them can severely degrade the performance. Note: The information presented here is from my experience and there is no way that I claim it to be accurate. I suggest reading Book OnLine for further clarification. All the discussion of Wait Stats in this blog is generic and varies from system to system. It is recommended that you test this on a development server before implementing it to a production server. Reference: Pinal Dave (http://blog.SQLAuthority.com)   Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQL Wait Stats, SQL Wait Types, T SQL, Technology

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  • How to bill a client for frequently-interrupted time

    - by Greg
    I find that when I'm working on hourly-billable projects (in particular, those that are research/design/architecture-oriented as opposed to straight coding) that I'm easily distracted by any number of things (email, grab a drink (loss of focus, but nature happens), link off the webpage I was reading, wandering mind (easy when the job calls for a lot of thinking), etc.) This results in very fragmented time, far too incremental IMO to accurately track with a timeclock, and some time very gray. I frequently end up billing for only some fraction of the elapsed time I spent in order to feel fair, but sometimes it takes a really long time to put in an 8-hour day. By contrast, when I've worked for salary I've not worried about whether I'm actively working at any given minute, I just get the job done, and I've never had anything but stellar reviews/feedback from past salaried employers, so I think I get the job done well. I personally believe in an 80/20 cycle: I get 80% of my work done during an inspired 20% of my time. But I have to screw around the other 80% of the time in order to get that first 20%. So the question: what billing/time-tracking policy can I adopt in order to be fair to my hourly customers without having to write off my own less-productive 80% that a salaried employer is willing to overlook in light of the complete package? Note: This question is not about how to be more productive or focused. It's about how to work around whatever salient limitations that I have in a way that's both fair to me and to my customers. Update: A little clarification (to pre-emptively stop some righteous indignation): I currently have a half dozen different project/client groups. It's not a great situation and I'm working at reducing it down to two, but that's my current reality. It's very easy to get off on a thread related to a different project than the one I'm clocking, and I'm not always conscious of it at the time. [I did not intend the question to mean that I was off playing games or making personal calls, etc., and have adjusted wording above to be clearer. Most of the time. I am only human, and sometimes the mind does force you to take a break! :-)]

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  • SQL SERVER – OLEDB – Link Server – Wait Type – Day 23 of 28

    - by pinaldave
    When I decided to start writing about this wait type, the very first question that came to my mind was, “What does ‘OLEDB’ stand for?” A quick search on Wikipedia tells me that OLEDB means Object Linking and Embedding Database. (How many of you knew this?) Anyway, I found it very interesting that this wait type was in one of the top 10 wait types in many of the systems I have come across in my performance tuning experience. Books On-Line: ????OLEDB occurs when SQL Server calls the SQL Server Native Client OLE DB Provider. This wait type is not used for synchronization. Instead, it indicates the duration of calls to the OLE DB provider. OLEDB Explanation: This wait type primarily happens when Link Server or Remove Query has been executed. The most common case wherein this wait type is visible is during the execution of Linked Server. When SQL Server is retrieving data from the remote server, it uses OLEDB API to retrieve the data. It is possible that the remote system is not quick enough or the connection between them is not fast enough, leading SQL Server to wait for the result’s return from the remote (or external) server. This is the time OLEDB wait type occurs. Reducing OLEDB wait: Check the Link Server configuration. Checking Disk-Related Perfmon Counters Average Disk sec/Read (Consistent higher value than 4-8 millisecond is not good) Average Disk sec/Write (Consistent higher value than 4-8 millisecond is not good) Average Disk Read/Write Queue Length (Consistent higher value than benchmark is not good) At this point in time, I am not able to think of any more ways on reducing this wait type. Do you have any opinion about this subject? Please share it here and I will share your comment with the rest of the Community, and of course, with due credit unto you. Please read all the post in the Wait Types and Queue series. Note: The information presented here is from my experience and there is no way that I claim it to be accurate. I suggest reading Book OnLine for further clarification. All the discussion of Wait Stats in this blog is generic and varies from system to system. It is recommended that you test this on a development server before implementing it to a production server. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQL Wait Stats, SQL Wait Types, T SQL, Technology

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  • Why no more macro languages?

    - by Muhammad Alkarouri
    In this answer to a previous question of mine about scripting languages suitability as shells, DigitalRoss identifies the difference between the macro languages and the "parsed typed" languages in terms of string treatment as the main reason that scripting languages are not suitable for shell purposes. Macro languages include nroff and m4 for example. What are the design decisions (or compromises) needed to create a macro programming language? And why are most of the mainstream languages parsed rather than macro? This very similar question (and the accepted answer) covers fairly well why the parsed typed languages, take C for example, suffer from the use of macros. I believe my question here covers different grounds: Macro languages or those working on a textual level are not wholly failures. Arguably, they include bash, Tcl and other shell languages. And they work in a specific niche such as shells as explained in my links above. Even m4 had a fairly long time of success, and some of the web template languages can be regarded as macro languages. It is quite possible that macros and parsed typing do not go well together and that is why macros "break" common languages. In the answer to the linked question, a macro like #define TWO 1+1 would have been covered by the common rules of the language rather than conflicting with those of the host language. And issues like "macros are not typed" and "code doesn't compile" are not relevant in the context of a language designed as untyped and interpreted with little concern for efficiency. The question about the design decisions needed to create a macro language pertain to a hobby project which I am currently working on on designing a new shell. Taking the previous question in context would clarify the difference between adding macros to a parsed language and my objective. I hope the clarification shows that the question linked doesn't cover this question, which is two parts: If I want to create a macro language (for a shell or a web template, for example), what limitations and compromises (and guidelines, if exist) need to be done? (Probably answerable by a link or reference) Why have no macro languages succeed in becoming mainstream except in particular niches? What makes typed languages successful in large programming, while "stringly-typed" languages succeed in shells and one-liner like environments?

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  • Will polishing my current project be a better learning experience than starting a new one?

    - by Alejandro Cámara
    I started programming many years ago. Now I'm trying to make games. I have read many recommendations to start cloning some well known games like galaga, tetris, arkanoid, etc. I have also read that I should go for the whole game (including menus, sound, score, etc.). Yesterday I finished the first complete version of my arkanoid clone. But it is far from over. I can still work on it for months (I program as a hobby in my free time) implementing a screen resolution switcher, remap of the control keys, power-ups falling from broken bricks, and a huge etc. But I do not want to be forever learning how to clone ONE game. I have the urge to get to the next clone in order to apply some design ideas I have come upon while developing this arkanoid clone (at the same time I am reading the GoF book and much source code from Ludum Dare 21 game contest). So the question is: Should I keep improving the arkanoid clone until it has all the features the original game had? or should I move to the next clone (there are almost infinite games to clone) and start mending the things I did wrong with the previous clone? This can be a very subjective question, so please restrain the answers to the most effective way to learn how to make my own games (not cloning someone ideas). Thank you! CLARIFICATION In order to clarify what I have implemented I make this list: Features implemented: Bouncing capabilities (the ball bounces on walls, on bricks, and on the bar). Sounds when bouncing on bricks and the bar, and when the player wins or loses. Basic title menu (new game and exit only). Also in-game menu and win/lose menus. Only three levels, but the map system is so easy I do not think it will teach me much (am I wrong?). Features not-implemented: Power-ups when breaking the bricks. Complex bricks (with more than one "hit point" and invincible). Better graphics (I am not really good at it). Programming polishing (use more intensively the design patterns). Here's a link to its (minimal) webpage: http://blog.acamara.es/piperine/ I kind of feel ashamed to show it, so please do not hit me too hard :-) My question was related to the not-implemented features. I wondered what was the fastest (optimal) path to learn. 1) implement the not-implemented features in this project which is getting big, or 2) make a new game which probably will teach me those lessons and new ones. ANSWER I choose @ashes999 answer because, in my case, I think I should polish more and try to "ship" the game. I think all the other answers are also important to bear in mind, so if you came here having the same question, before taking a rush decision read all the discussion. Thank you all!

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  • Windows Phone 7 Development Updates &ndash; March 8th 2011

    - by Nikita Polyakov
    Here are the latest update from the Windows Phone 7 Developer Worlds that went live this month. Here are some of the latest numbers: Windows Phone Marketplace currently offers more than 9,000 quality apps and games and enjoys a base of over 32,000 registered developers, delivering an average of 100 new apps every day. There have been over 1 million downloads of the developers tools for Windows Phone 7. Trial version help you sell more Trials result in higher sales by the numbers: Users like trials  - paid apps with trial functionality are downloaded 70 times more than paid apps that don’t Nearly 1 out of 10 trial apps downloaded convert to a purchase and generate 10 times more revenue on average than paid apps that don’t include trial functionality. Trial downloads convert to paid downloads quickly. More than half of trial downloads that convert to a sale do so within the 1st 24 hours of trial download, and mostly within 2 hours of trial download. Microsoft Ad Control is gaining traction By the numbers - ad supported Windows Phone 7 apps are: Roughly ¼ of all registered U.S. WP7 developers have downloaded the free Ad SDK for Silverlight and XNA Of ad funded apps, over 95 percent use the free Microsoft Advertising Ad Control Monthly impressions from our Ad Exchange has continued to grow by double digits – impressions increased by 376 percent since January Ad Control, the first wave of “How Do I” videos are now available on MSDN: Create an Ad in a Windows Phone 7 XNA Game App Register Ad-Enabled Windows Phone 7 Apps Measure Ad Performance of Windows Phone 7 Apps Boarder International App submission for Free Apps through Yalla Apps As of today you can start submitting your free applications in developer markets that are currently not covered by Microsoft. To submit your Free application if you DO NOT belong to one of the Marketplace supported countries, go to: Yalla Apps Marketplace Policy Updates: Free App Marketplace Submission upped to 100 and other news Microsoft has been revisiting a few of our Marketplace policies based on feedback from developers to reduce friction and cost, word for word: 1. We have raised the limit on the number of certifications that can be performed for FREE apps at no cost to the registered developer from five to 100. This was a common request from developers which we are glad to implement after building alternate methods to ensure that users can find and download high quality apps. 2. We have converted policy 5.6 - related to the inclusion of contact information for support - from a mandatory to an optional policy. This is still a strongly recommended best practice, but we recognized and responded to developer feedback that this policy was creating excessive drag on the certification process for developers without commensurate user benefit for all apps. 3. We also understand the desire for clarification with regard to our policy on applications distributed under open source licenses.  The Marketplace Application Provider Agreement (APA) already permits applications under the BSD, MIT, Apache Software License 2.0 and Microsoft Public License.  We plan to update the APA shortly to clarify that we also permit applications under the Eclipse Public License, the Mozilla Public License and other, similar licenses and we continue to explore the possibility of accommodating additional OSS licenses. Enjoy and happy coding! Official Blog Post for reference.

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  • Understanding clojure keywords

    - by tjb1982
    I'm taking my first steps with Clojure. Otherwise, I'm somewhat competent with JavaScript, Python, Java, and a little C. I was reading this artical that describes destructuring vectors and maps. E.g. => (def point [0 0]) => (let [[x y] point] => (println "the coordinates are:" x y)) the coordinates are: 0 0 but I'm having a difficult time understanding keywords. At first glance, they seem really simple, as they just evaluate to themselves: => :test :test But they seem to be used is so many different ways and I don't understand how to think about them. E.g., you can also do stuff like this: => (defn full-name [& {first :first last :last}] => (println first last)) => (full-name :first "Tom" :last "Brennan") Tom Brennan nil This doesn't seem intuitive to me. I would have guessed the arguments should have been something more like: (full-name {:first "Tom" :last "Brennan"}) because it looks like in the function definition that you're saying "no required arguments, but a variable number of arguments comes in the form of a single map". But it seems more like you're saying "no required arguments, but a variable number of arguments comes which should be a list of alternating keywords and values... ?" I'm not really sure how to wrap my brain around this. Also, things like this confuse me too: => (def population {:humans 5 :zombies 1000}) => (:zombies population) 1000 => (population :zombies) 1000 How do maps and keywords suddenly become functions? If I could get some clarification on the use of keywords in these two examples, that would be really helpful. Update I've also seen http://stackoverflow.com/questions/3337888/clojure-named-arguments and while the accepted answer is a great demonstration of how to use keywords with destructuring and named arguments, I'm really looking more for understanding how to think about them--why the language is designed this way and how I can best internalize their use.

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  • Speaker Notes...

    - by wulfers
    At a .Net User Group meeting this week, I experienced two poorly prepared speakers floundering through presentations….  As a Lead Technologist at the company I work for, I have experience training technical staff and also giving presentations at code camps.  Here are a few guidelines for aspiring speakers you might find helpful…   1.       Do not stand in front of your audience and read your slides.  This is  offensive to your audience and not what they came for...  Your slides are there to reinforce the information you are presenting and to give the audience a little clarification on some terms you may use and as a visual aid for some complicated issues. 2.       Have someone review your presentation (slides, notes, …) who speaks the language you will be presenting in fluently.  Also record at least ten minutes of your presentation and have that same person review that.  One of the speakers this week used the word “Basically” fifty times in less than thirty minutes…  I started to flinch every time he used the term. 3.       Be Prepared  -  before the presentation begins.  Don’t make any last minute changes to your presentation or demo code the night before.  Don’t patch your laptop or demo servers the night before.  If possible create a virtual image that you only use for presentations and use that (refreshed before every presentation). 4.       Know the level of expertise of your audience.  Speaking above or below their abilities will make or break your presentation. 5.       Deliver what you promise. The presentation this week was supposed to be on BDD (Behavior Driven Develpment).  The presenter completely ran off track and 90% of the discussion was how his team mistakenly used TDD (Test Driven Development), and was unhappy with the results.  Based on his loss of focus we only heard a rushed 10 minute presentation on DBB which was a disservice to the audience. 6.       Practice your presentation with your own small team before you try this on a room full of people you don’t know.  A side benefit of doing this with your own team is that you can get candid feedback from your team and also get kudos for training your own team.  I find I can also turn my presentations into technical white papers and get a third benefit from the work I’ve put into a presentation. 7.       Sharpen your own saw.  Pick a topic that is fairly current.  Something you would like to learn about and would benefit your current career path. 8.       Have fun doing it.

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  • Pixels - A cry for some insight

    - by CarrotFile
    I'm pretty new to web developing and I'd love some clarification. Although reading more than one book on the topic, I cannot seem to wrap my head around the pixel concept. I encounter problems with this issue when trying to use CSS and pixel units for design that fits different screen sizes. To my understanding a pixel is the most basic unit used by a monitor in order to compose an image on the screen. So if me resolution is 800 by 600, everything on my screen is rendered using those 800*600 basic building blocks. If I were to enlarge my screen resolution, 3 things would accrue: A. The basic image building block(the pixel) would shrink in size B. The pixels would move close together C. Well, more pixels would now be available All these combined lead to a sharper(depending on the viewing distance) and more detail enabling image. Well so far so good. Here is were I start getting lost: To my knowledge a pixel is not a physical, real object. Monitors are not embedded with a few thousand pixels. I am drawn to this conclusion because anyone can change his screen's resolution, making a pixel on his screen bigger or smaller, and adding or subtracting the amount of total pixels on screen. Adding to that, I have herd that different monitors have different pixel densities. For example Apple's retina monitors. Taking all of the above as my knowledge base, These are my questions: If a pixel has no real world constant size, what does comparing different pixel densities matter? Each screen company can define it's own pixel concept and declare the higher density. What does a bigger pixel density mean? Say we take two screens with the same physical dimensions, but with a different pixel density, am I to assert that the main difference would be the larger density screen being able to display a higher max resolution? Or am I to assert that given the same resolution on both monitors, the higher density one would display a sharper, smaller image? If a pixel is not a fixed size within one monitor, is it a fixed size between the same resolution on two different monitors? For example, would two different monitors, set to the same resolution, be comprised of same size, same quantity pixels? I'd love some help (:

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  • What does path finding in internet routing do and how is it different from A*?

    - by alan2here
    Note: If you don't understand this question then feel free to ask clarification in the comments instead of voting down, it might be that this question needs some more work at the moment. I've been directed here from the Stack Excange chat room Root Access because my question didn't fit on Super User. In many aspects path finding algorithms like A star are very similar to internet routing. For example: A node in an A* path finding system can search for a path though edges between other nodes. A router that's part of the internet can search for a route though cables between other routers. In the case of A*, open and closed lists are kept by the system as a whole, sepratly from any individual node as well as each node being able to temporarily store a state involving several numbers. Routers on the internet seem to have remarkable properties, as I understand it: They are very performant. New nodes can be added at any time that use a free address from a finite (not tree like) address space. It's real routing, like A*, there's never any doubling back for example. Similar IP addresses don't have to be geographically nearby. The network reacts quickly to changes to the networks shape, for example if a line is down. Routers share information and it takes time for new IP's to be registered everywhere, but presumably every router doesn't have to store a list of all the addresses each of it's directions leads most directly to. I'm looking for a basic, general, high level description of the algorithms workings from the point of view of an individual router. Does anyone have one? I presume public internet routers don't use A* as the overheads would be to large, and scale to poorly. I also presume there is a single method worldwide because it seems as if must involve a lot of transferring data to update and communicate a reasonable amount of state between neighboring routers. For example, perhaps the amount of data that needs to be stored in each router scales logarithmically with the number of routers that exist worldwide, the detail and reliability of the routing is reduced over increasing distances, there is increasing backtracking involved in parts of the network that are less geographically uniform or maybe each router really does perform an A* style search, temporarily maintaining open and closed lists when a packet arrives.

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  • Why can't Java/C# implement RAII?

    - by mike30
    Question: Why can't Java/C# implement RAII? Clarification: I am aware the garbage collector is not deterministic. So with the current language features it is not possible for an object's Dispose() method to be called automatically on scope exit. But could such a deterministic feature be added? My understanding: I feel an implementation of RAII must satisfy two requirements: 1. The lifetime of a resource must be bound to a scope. 2. Implicit. The freeing of the resource must happen without an explicit statement by the programmer. Analogous to a garbage collector freeing memory without an explicit statement. The "implicitness" only needs to occur at point of use of the class. The class library creator must of course explicitly implement a destructor or Dispose() method. Java/C# satisfy point 1. In C# a resource implementing IDisposable can be bound to a "using" scope: void test() { using(Resource r = new Resource()) { r.foo(); }//resource released on scope exit } This does not satisfy point 2. The programmer must explicitly tie the object to a special "using" scope. Programmers can (and do) forget to explicitly tie the resource to a scope, creating a leak. In fact the "using" blocks are converted to try-finally-dispose() code by the compiler. It has the same explicit nature of the try-finally-dispose() pattern. Without an implicit release, the hook to a scope is syntactic sugar. void test() { //Programmer forgot (or was not aware of the need) to explicitly //bind Resource to a scope. Resource r = new Resource(); r.foo(); }//resource leaked!!! I think it is worth creating a language feature in Java/C# allowing special objects that are hooked to the stack via a smart-pointer. The feature would allow you to flag a class as scope-bound, so that it always is created with a hook to the stack. There could be a options for different for different types of smart pointers. class Resource - ScopeBound { /* class details */ void Dispose() { //free resource } } void test() { //class Resource was flagged as ScopeBound so the tie to the stack is implicit. Resource r = new Resource(); //r is a smart-pointer r.foo(); }//resource released on scope exit. I think implicitness is "worth it". Just as the implicitness of garbage collection is "worth it". Explicit using blocks are refreshing on the eyes, but offer no semantic advantage over try-finally-dispose(). Is it impractical to implement such a feature into the Java/C# languages? Could it be introduced without breaking old code?

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  • External DNS and IIS Webserver requirement for Outlook Anywhere 2007 ?

    - by Albert Widjaja
    Hi, I just would like some clarification about which External hostname / DNS entries that I need to publish in my external facing DNS server to enable Outlook Anywhere on my Exchange Server 2007 for external user: ExCAS01.domain.com - Exchange CAS A Record Autodiscover.domain.com - Autodiscover CNAME to the CAS Server above _autodiscover._tcp.domain.com - SRV type record and do I have to expect anything by typing this address in bowser "https://autodiscover.domain.com/AutoDiscover/AutoDiscover.xml" ? because i get request time out at the moment. here are the error log from https://testexchangeconnectivity.com: Host Excas01.domain.com couldn't be resolved in DNS Exception details: Message: The requested name is valid, but no data of the requested type was found Type: System.Net.Sockets.SocketException Stack trace: at System.Net.Dns.GetAddrInfo(String name) at System.Net.Dns.InternalGetHostByName(String hostName, Boolean includeIPv6) at System.Net.Dns.GetHostAddresses(String hostNameOrAddress) at Microsoft.Exchange.Tools.ExRca.Tests.ResolveHostTest.PerformTestReally() Host autodiscover.domain.com couldn't be resolved in DNS Exception details: Message: The requested name is valid, but no data of the requested type was found Type: System.Net.Sockets.SocketException Stack trace: at System.Net.Dns.GetAddrInfo(String name) at System.Net.Dns.InternalGetHostByName(String hostName, Boolean includeIPv6) at System.Net.Dns.GetHostAddresses(String hostNameOrAddress) at Microsoft.Exchange.Tools.ExRca.Tests.ResolveHostTest.PerformTestReally() Attempting to locate SRV record _autodiscover._tcp.domain.com in DNS. The Autodiscover SRV record wasn't found in DNS.

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  • Prohibit installers from modifying Windows Firewall rules

    - by Sysadmin
    Some application installers tamper with the Windows Firewall rules. I would like to prohibit such automated modifications of the Windows Firewall rules on Windows 7 machines (which use the Windows 7 version of Windows Firewall). Is there some setting that would accomplish this, or would it be necessary to resort to hooking the Windows Firewall API? I would like to prevent these modifications from being made at all, rather than backing up the firewall rules before the installation and restoring them afterward. A TechNet article indicates that there is no way to prevent installers from accessing the Windows Firewall API, but that article pertains to the Windows XP version of Windows Firewall. The Windows 7 version of Windows Firewall is newer and much-improved over the Windows XP incarnation, so it is unclear whether that advice is still pertinent. A similar SuperUser question had received a couple of responses, but neither response answered the question, likely because they misunderstood that question due to the way it was worded. I hope that I have explained this problem clearly. Don't hesitate to ask if you need any clarification.

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  • WSS 3.0 Backup/Restore Root Site Collection to Sub-Site of New Site Collection

    - by bfrancis
    Our intranet was originally setup to be at the root of its site collection. We are trying to change this so that our new internet site will live in the root and the intranet will be a sub-site. At this point I have created a new web application and site collection to house the internet and intranet. I used the 'stsadm -o backup' command to create a backup of our current intranet. I then ran the 'stsadm -o restore' command to restore the intranet site collection to wss/sites/intranet. This seems to have worked as I am able to access the intranet from this location. The issue I now seem to have is that images, sub-sites, etc. are all making reference as if the intranet is still the root site. So for example a link to a sub-site is pointing to wss/department/technology/default.aspx and it needs to point to wss/sites/intranet/department/technology/default.aspx. I am looking for help and/or clarification on two things: 1. Am I approaching the migration of a root site collection to a sub-site the best way? 2. How would I go about updating the link references so that they are based on the intranet now being a sub-site instead of the root site?

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  • Monitor Exchange Email Address and run scripts

    - by WernerCD
    Okay... Not sure how "out there" this thought is... Right now to send a pager message (aka text message), a user logs into our AS400... logs into the program... enters user name and message and hit's F10 to send. With a little looking, it seems that you can run remote commands to the AS400 via FTP. So I'm working on building a script (batch or otherwise) that, given two parameters (user, message), will FTP into the AS400 and run a remote command: c:\>ftp server user: admin password: ***** ftp> quote rcmd SNDPGRMSG TOPGR(JDOE) MSG('This is a Test') ftp> quit So... what I want to do is setup an email account on our Exchange server Monitor the account for incoming mail upon receipt of incoming mail, parse it... say for example subject is defined as "Recipient" and email text is defined as "Pager message" run a batch that uses the above mentioned TOPGR and MSG as parameters... via FTP to the AS400 mark email as "read" The main thing I'm not sure about is monitoring an exchange account and running a script on incoming emails. I'm sure what I want to do is possible... but where would I start? EDIT: Clarification The main reasons for using this four part system are logging (messages sent via this are logged and reported by the AS400 program) and the existing scheduler for redirecting pages (For example, the weekly on-call person = TOPGR(oncall) gets updated by the AS400 program). I'm also trying to remove duplicate work. If I can get this setup working, I can redirect pages from OTHER systems into this one. I then don't have to update 2, soon to be 3, systems with current phone numbers, carriers, on-call schedules, etc. System #2 and #3 can just "email" [email protected].

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  • How can I get MySQL 5.5 to log warnings to one of the log files?

    - by Wodin
    I have found various things that say that you can log warnings to the MySQL error log, but I have not been able to actually make it happen. I do have the error log working, and MySQL prints stuff to it on startup and shutdown and occasionally at other times, but if I e.g. SELECT CAST('123' AS DATE); and then SHOW WARNINGS; I can see the warning, but it does not show up in any logs. I've also tried enabling the general log and the slow query log, but these don't show the warnings either. I've tried with log_warnings = 1 and log_warnings = 2, but still no warnings are logged. What am I doing wrong? mysql> show variables like '%error%'; +--------------------+--------------------------+ | Variable_name | Value | +--------------------+--------------------------+ | error_count | 0 | | log_error | /var/log/mysql/mysql.err | | max_connect_errors | 10 | | max_error_count | 1024 | | slave_skip_errors | OFF | +--------------------+--------------------------+ mysql> show variables like '%warn%'; +---------------+-------+ | Variable_name | Value | +---------------+-------+ | log_warnings | 1 | | sql_warnings | OFF | | warning_count | 0 | +---------------+-------+ 3 rows in set (0.06 sec) mysql> show variables like '%log%'; +-----------------------------------------+-------------------------------+ | Variable_name | Value | +-----------------------------------------+-------------------------------+ ... | general_log | ON | | general_log_file | /var/log/mysql/general.log | ... | log | ON | ... | log_error | /var/log/mysql/mysql.err | | log_output | FILE | | log_queries_not_using_indexes | ON | ... | log_warnings | 1 | ... | slow_query_log | ON | | slow_query_log_file | /var/log/mysql/mysql-slow.log | ... +-----------------------------------------+-------------------------------+ Edit: mysql> show global status like 'Aborted%'; +------------------+-------+ | Variable_name | Value | +------------------+-------+ | Aborted_clients | 24 | | Aborted_connects | 15 | +------------------+-------+ 2 rows in set (0.08 sec) Edit: Clarification: I do get [Warning] Aborted connection 1 to db... and [Warning] Access denied for user... messages logged, but not the warnings that you can see via SHOW WARNINGS after e.g. inserting something or running LOAD DATA INFILE... which is what I'm looking for.

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  • Run script before shutdown/restart

    - by dtbarne
    I'd like to run a PHP script when an instance is told to shutdown, but of course before it actually finishes shutting down. My particular script is just looking to push some log files from the local partition to a another server. I've got the gist of how this process works, but I need some clarification. How I understand it. Please correct me if I'm wrong. Create an executable script in /etc/init.d (lets call it /etc/init.d/push-logs) Create a symlink to /etc/init.d/push-logs from /etc/rc0.d (shutdown) and /etc/rc6.d (reboot). The name should be KXXpush-logs Here's my questions: Of course - am I understanding correctly? For #2 above - it sounds like the lower the XX the better - is there too low a number I can use? Does it matter if it shares a number with another script? Does the script in /etc/init.d/push-logs HAVE to follow the standard init.d template (supporting start/stop, etc. commands)? This doesn't really apply to my use case. If possible I just want the script to be the following: #!/bin/sh # # Run PHP file prior to shutdown # /usr/bin/php /path/to/php_file.php

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  • Setting a time limit for a transaction in MySQL/InnoDB

    - by Trevor Burnham
    This sprang from this related question, where I wanted to know how to force two transactions to occur sequentially in a trivial case (where both are operating on only a single row). I got an answer—use SELECT ... FOR UPDATE as the first line of both transactions—but this leads to a problem: If the first transaction is never committed or rolled back, then the second transaction will be blocked indefinitely. The innodb_lock_wait_timeout variable sets the number of seconds after which the client trying to make the second transaction would be told "Sorry, try again"... but as far as I can tell, they'd be trying again until the next server reboot. So: Surely there must be a way to force a ROLLBACK if a transaction is taking forever? Must I resort to using a daemon to kill such transactions, and if so, what would such a daemon look like? If a connection is killed by wait_timeout or interactive_timeout mid-transaction, is the transaction rolled back? Is there a way to test this from the console? Clarification: innodb_lock_wait_timeout sets the number of seconds that a transaction will wait for a lock to be released before giving up; what I want is a way of forcing a lock to be released. Update: Here's a simple example that demonstrates why innodb_lock_wait_timeout is not sufficient to ensure that the second transaction is not blocked by the first: START TRANSACTION; SELECT SLEEP(55); COMMIT; With the default setting of innodb_lock_wait_timeout = 50, this transaction completes without errors after 55 seconds. And if you add an UPDATE before the SLEEP line, then initiate a second transaction from another client that tries to SELECT ... FOR UPDATE the same row, it's the second transaction that times out, not the one that fell asleep. What I'm looking for is a way to force an end to this transaction's restful slumber.

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  • Copying symbolic links and filenames with special characters to NAS

    - by Mr E
    I have a new Western Digital My Book Live NAS. I am trying to copy files from an old drive to the NAS. I'm using Ubuntu 12.04 and I've mounted the drive by browsing the network in Nautilus and choosing a shared folder configured on the NAS. The shared folder is then automatically mounted at .gvfs/files on mybooklive. There are two problems so far: File names and directory names containing certain characters (e.g. : or |). Attempting to copy these results in the error message: cp: cannot stat `/path/to/destination.filename': Invalid argument Symbolic links. In Nautilus I get the error message: Symlinks not supported by backend My questions are: Can I connect to the NAS or configure the NAS so that I can copy my files without this problem? (In case it matters, I don't need Windows compatibility.) If not, what can I do to identify all the problem files? Can I do anything to automatically fix my filenames Please let me know if any of this needs clarification. I'm not too familiar with all of this so I may have left out some useful information.

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  • Are HDMI to VGA Adapters Really Device-Specific?

    - by allquixotic
    There are a lot of devices on the market right now (especially mobile devices) with a Micro-HDMI or Mini-HDMI port and no VGA or D-Sub output. Most manufacturers of said devices sell a cable that looks something like this: I have yet to find a cable like this that claims to work on a wide array of devices. In general, these cables claim to work with one specific device only. The way these cables work, I think, is that analog VGA signals are sent from the HDMI port on the device. This should work for devices that have special hardware on the motherboard/GPU capable of driving this. Is it the case that these cables have to be custom designed for each device? Or, is it rather that any device which possesses this special "signaling of analog VGA over the HDMI port" can be made to work with a cable that is physically compatible (i.e. the HDMI end plugs into the device and the VGA end accepts a VGA monitor cable)? Note that I am not looking for a product recommendation, just a conceptual clarification on what exactly these devices are doing. Also, a few remarks: The cables like the one depicted here are not digital to analog converters. I know about these: they are expensive, and they are the ONLY solution if your device only outputs a digital signal and is incapable of driving analog VGA over the HDMI port. The cables like the one depicted here are not straight crossover cables from VGA to HDMI, either. The crossover cables are designed to send a digital HDMI signal over the VGA port's wires; that is, the wire protocol is HDMI (digital) but the physical pinout is the same as VGA, even though nothing analog is happening. Once again, this is not the behavior that, I believe, the devices which I'm talking about in this question are doing. The cabling and devices that this question is about transmit the analog VGA data over the HDMI port (the HDMI port is in the device outputting the data, and the VGA side is the monitor/projector).

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