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• Migrating SQL Server Databases – The DBA’s Checklist (Part 3)

  - by Sadequl Hussain

  Continuing from Part 2 of the Database Migration Checklist series: Step 10: Full-text catalogs and full-text indexing This is one area of SQL Server where people do not seem to take notice unless something goes wrong. Full-text functionality is a specialised area in database application development and is not usually implemented in your everyday OLTP systems. Nevertheless, if you are migrating a database that uses full-text indexing on one or more tables, you need to be aware a few points. First of all, SQL Server 2005 now allows full-text catalog files to be restored or attached along with the rest of the database. However, after migration, if you are unable to look at the properties of any full-text catalogs, you are probably better off dropping and recreating it. You may also get the following error messages along the way: Msg 9954, Level 16, State 2, Line 1 The Full-Text Service (msftesql) is disabled. The system administrator must enable this service. This basically means full text service is not running (disabled or stopped) in the destination instance. You will need to start it from the Configuration Manager. Similarly, if you get the following message, you will also need to drop and recreate the catalog and populate it. Msg 7624, Level 16, State 1, Line 1 Full-text catalog ‘catalog_name‘ is in an unusable state. Drop and re-create this full-text catalog. A full population of full-text indexes can be a time and resource intensive operation. Obviously you will want to schedule it for low usage hours if the database is restored in an existing production server. Also, bear in mind that any scheduled job that existed in the source server for populating the full text catalog (e.g. nightly process for incremental update) will need to be re-created in the destination. Step 11: Database collation considerations Another sticky area to consider during a migration is the collation setting. Ideally you would want to restore or attach the database in a SQL Server instance with the same collation. Although not used commonly, SQL Server allows you to change a database’s collation by using the ALTER DATABASE command: ALTER DATABASE database_name COLLATE collation_name You should not be using this command for no reason as it can get really dangerous.  When you change the database collation, it does not change the collation of the existing user table columns.  However the columns of every new table, every new UDT and subsequently created variables or parameters in code will use the new setting. The collation of every char, nchar, varchar, nvarchar, text or ntext field of the system tables will also be changed. Stored procedure and function parameters will be changed to the new collation and finally, every character-based system data type and user defined data types will also be affected. And the change may not be successful either if there are dependent objects involved. You may get one or multiple messages like the following: Cannot ALTER ‘object_name‘ because it is being referenced by object ‘dependent_object_name‘. That is why it is important to test and check for collation related issues. Collation also affects queries that use comparisons of character-based data.  If errors arise due to two sides of a comparison being in different collation orders, the COLLATE keyword can be used to cast one side to the same collation as the other. Continues…

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• Algorithm for querying linearly through a non-linear list of questions

  - by JoshLeaves

  For a multiplayers trivia game, I need to supply my users with a new quizz in a desired subject (Science, Maths, Litt. and such) at the start of every game. I've generated about 5K quizzes for each subject and filled my database with them. So my 'Quizzes' database looks like this: |ID |Subject |Question +-----+------------+---------------------------------- | 23 |Science | What's water? | 42 |Maths | What's 2+2? | 99 |Litt. | Who wrote "Pride and Prejudice"? | 123 |Litt. | Who wrote "On The Road"? | 146 |Maths | What's 2*2? | 599 |Science | You know what's cool? |1042 |Maths | What's the Fibonacci Sequence? |1056 |Maths | What's 42? And so on... (Much more detailed/complex but I'll keep the exemple simple) As you can see, due to technical constraints (MongoDB), my IDs are not linear but I can use them as an increasing suite. So far, my algorithm to ensure two users get a new quizz when they play together is the following: // Take the last played quizzes by P1 and P2 var q_one = player_one.getLastPlayedQuizz('Maths'); var q_two = player_two.getLastPlayedQuizz('Maths'); // If both of them never played in the subject, return first quizz in the list if ((q_one == NULL) && (q_two == NULL)) return QuizzDB.findOne({subject: 'Maths'}); // If one of them never played, play the next quizz for the other player // This quizz is found by asking for the first quizz in the desired subject where // the ID is greater than the last played quizz's ID (if the last played quizz ID // is 42, this will return 146 following the above example database) if (q_one == NULL) return QuizzDB.findOne({subject: 'Maths', ID > q_two}); if (q_two == NULL) return QuizzDB.findOne({subject: 'Maths', ID > q_one}); // And if both of them have a lastPlayedQuizz, we return the next quizz for the // player whose lastPlayedQuizz got the higher ID if (q_one > q_two) return QuizzDB.findOne({subject: 'Maths', ID > q_one}); else return QuizzDB.findOne({subject: 'Maths', ID > q_two}); Now here comes the real problem: Once I get to the end of my database (let's say, P1's last played quizz in 'Maths' is 1056, P2's is 146 and P3 is 1042), following my algorithm, P1's ID is the highest so I ask for the next question in 'Maths' where ID is superior to 1056. There is nothing, so I roll back to the beginning of my quizz list (with a random skipper to avoid having the first question always show up). P1 and P2's last played will then be 42 and they will start fresh from the beginning of the list. However, if P1 (42) plays against P3 (1042), the resulting ID will be 1056...which P1 already played two games ago. Basically, players who just "rolled back" to the beginning of the list will be brought back to the end of the list by players who still haven't rolled back. The rollback WILL happen in the end, but it'll take time and there'll be a "bottleneck" at the beginning and at the end. Thus my question: What would be the best algorith to avoid this bottleneck and ensure players don't get stuck endlessly on the same quizzes? Also bear in mind that I've got some technical constraints: I can't get a random question in a subject (ie: no "QuizzDB.findOne({subject: 'Maths'}).skip(random());"). It's cool to skip on one to twenty records, but the MongoDB documentation warns against skipping too many documents. I would like to avoid building an array of every quizz played by each player and find the next non-played in the database with a $nin. Thanks for your help

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• Ongoing confusion about ivars and properties in objective C

  - by Earl Grey

  After almost 8 months being in ios programming, I am again confused about the right approach. Maybe it is not the language but some OOP principle I am confused about. I don't know.. I was trying C# a few years back. There were fields (private variables, private data in an object), there were getters and setters (methods which exposed something to the world) ,and properties which was THE exposed thing. I liked the elegance of the solution, for example there could be a class that would have a property called DailyRevenue...a float...but there was no private variable called dailyRevenue, there was only a field - an array of single transaction revenues...and the getter for DailyRevenue property calculated the revenue transparently. If somehow the internals of daily revenue calculation would change, it would not affect somebody who consumed my DailyRevenue property in any way, since he would be shielded from getter implementation. I understood that sometimes there was , and sometimes there wasn't a 1-1 relationship between fields and properties. depending on the requirements. It seemed ok in my opinion. And that properties are THE way to acces the data in object. I know the difference betweeen private, protected, and public keyword. Now lets get to objectiveC. On what factor should I base my decision about making someting only an ivar or making it as a property? Is the mental model the same as I describe above? I know that ivars are "protected" by default, not "private" asi in c#..But thats ok I think, no big deal for my presnet level of understanding the whole ios development. The point is ivars are not accesible from outside (given i don't make them public..but i won't). The thing that clouds my clear understanding is that I can have IBOutlets from ivars. Why am I seeing internal object data in the UI? *Why is it ok?* On the other hand, if I make an IBOutlet from property, and I do not make it readonly, anybody can change it. Is this ok too? Let's say I have a ParseManager object. This object would use a built in Foundation framework class called NSXMLParser. Obviously my ParseManager will utilize this nsxmlparser's capabilities but will also do some additional work. Now my question is, who should initialize this NSXMLParser object and in which way should I make a reference to it from the ParseManager object, when there is a need to parse something. A) the ParseManager -1) in its default init method (possible here ivar - or - ivar+ppty) -2) with lazyloading in getter (required a ppty here) B) Some other object - who will pass a reference to NSXMLParser object to the ParseManager object. -1) in some custom initializer (initWithParser:(NSXMLPArser *) parser) when creating the ParseManager object.. A1 - the problem is, we create a parser and waste memory while it is not yet needed. However, we can be sure that all methods that are part ot ParserManager object, can use the ivar safely, since it exists. A2 - the problem is, the nsxmlparser is exposed to outside world, although it could be read only. Would we want a parser to be exposed in some scenario? B1 - this could maybe be useful when we would want to use more types of parsers..i dont know... I understand that architectural requirements and and language is not the same. But clearly the two are in relation. How to get out of that mess of my? Please bear with me, I wasn't able to come up with a single ultimate question. And secondly, it's better to not scare me with some superadvanced newspeak that talks about some crazy internals (what the compiler does) and edge cases.

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• Are there too many qualified software development engineers chasing too few jobs?

  - by T Gregory

  I am trying to write this question in a non-argumentative way, but it is quite emotionally charged for some, so please bear with me. In the U.S., we hear constantly from CEOs that they cannot find enough qualified software engineers. In fact, it is the position of the U.S. government that demand for software engineering talent outpaces supply. This position can be clearly seen in the granting of tens of thousands of H1B visas, but also in the following excerpt from the official 2010-11 Bureau of Labor Statistics Occupational Outlook Handbook: Employment of computer software engineers is expected to increase by 32 percent from 2008-2018, which is much faster than the average for all occupations. In addition, this occupation will see a large number of new jobs, with more than 295,000 created between 2008 and 2018. Demand for computer software engineers will increase as computer networking continues to grow. For example, expanding Internet technologies have spurred demand for computer software engineers who can develop Internet, intranet, and World Wide Web applications. Likewise, electronic data-processing systems in business, telecommunications, healthcare, government, and other settings continue to become more sophisticated and complex. Implementing, safeguarding, and updating computer systems and resolving problems will fuel the demand for growing numbers of systems software engineers. New growth areas will also continue to arise from rapidly evolving technologies. The increasing uses of the Internet, the proliferation of Web sites, and mobile technology such as the wireless Internet have created a demand for a wide variety of new products. As more software is offered over the Internet, and as businesses demand customized software to meet their specific needs, applications and systems software engineers will be needed in greater numbers. In addition, the growing use of handheld computers will create demand for new mobile applications and software systems. As these devices become a larger part of the business environment, it will be necessary to integrate current computer systems with this new, more mobile technology. However, from the the employee side of the equation, we often hear the opposite. Many of the stories of SDEs with graduate degrees and decades of experience on the unemployment line, or the big tech interview war stories, are anecdotal, for sure. But, there is one piece of data that is neither anecdotal nor transitory, and that is the aggregate decisions of millions of undergraduates of what degree to pursue. Here, a different picture emerges from the data, and that picture is not good for the software profession. According the most recent Taulbee Survey from Computer Research Association, undergrad degree production in CS and CE has fallen nearly 60% since 2004. (Undergrad enrollments have ticked up in the past two years, but only modestly). Here we see that a basic disconnect between what corporate CEOs and the US government are saying and what potential employees really think about job prospects in software engineering. So my questions are these. Who are we to believe? Is there an acute talent shortage, or is there a long-term structural oversupply in the SDE labor market? Can anyone provide reliable data on long-term unemployment among SDEs? How many are leaving the profession due to lack of work? Real data is most helpful. Thanks.

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• 5 Ways to Determine Mobile Location

  - by David Dorf

  In my previous post, I mentioned the importance of determining the location of a consumer using their mobile phone.  Retailers can track anonymous mobile phones to determine traffic patterns both inside and outside their stores.  And with consumers' permission, retailers can send location-aware offers to mobile phones; for example, a coupon for cereal as you walk down that aisle.  When paying with Square, your location is matched with the transaction.  So there are lots of reasons for retailers to want to know the location of their customers.  But how is it done? I thought I'd dive a little deeper on that topic and consider the approaches to determining location. 1. Tower Triangulation By comparing the relative signal strength from multiple antenna towers, a general location of a phone can be roughly determined to an accuracy of 200-1000 meters.  The more towers involved, the more accurate the location. 2. GPS Using Global Positioning Satellites is more accurate than using cell towers, but it takes longer to find the satellites, it uses more battery, and it won't well indoors.  For geo-fencing applications, like those provided by Placecast and Digby, cell towers are often used to determine if the consumer is nearing a "fence" then switches to GPS to determine the actual crossing of the fence. 3. WiFi Triangulation WiFi triangulation is usually more accurate than using towers just because there are so many more WiFi access points (i.e. radios in routers) around. The position of each WiFi AP needs to be recorded in a database and used in the calculations, which is what Skyhook has been doing since 2008.  Another advantage to this method is that works well indoors, although it usually requires additional WiFi beacons to get the accuracy down to 5-10 meters.  Companies like ZuluTime, Aisle411, and PointInside have been perfecting this approach for retailers like Meijer, Walgreens, and HomeDepot. Keep in mind that a mobile phone doesn't have to connect to the WiFi network in order for it to be located.  The WiFi radio in the phone only needs to be on.  Even when not connected, WiFi radios talk to each other to prepare for a possible connection. 4. Hybrid Approaches Naturally the most accurate approach is to combine the approaches described above.  The more available data points, the greater the accuracy.  Companies like ShopKick like to add in acoustic triangulation using the phone's microphone, and NearBuy can use video analytics to increase accuracy. 5. Magnetic Fields The latest approach, and this one is really new, takes a page from the animal kingdom.  As you've probably learned from guys like Marlin Perkins, some animals use the Earth's magnetic fields to navigate.  By recording magnetic variations within a store, then matching those readings with ones from a consumer's phone, location can be accurately determined.  At least that's the approach IndoorAtlas is taking, and the science seems to bear out.  It works well indoors, and doesn't require retailers to purchase any additional hardware.  Keep an eye on this one.

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• MPI Cluster Debugger launch integration in VS2010

  Let's assume that you have all the HPC bits installed and that you have existing MPI code (or you created a "Hello World" project using the MPI project template). Of course, you create a single MPI application and at runtime it will correspond to multiple processes (of the same app) launched on multiple nodes (i.e. machines) on the cluster. So how do you debug such a situation by simply hitting the familiar "F5" keystroke (i.e. Debug - Start Debugging)?WATCH IT INSTEAD OF READING ABOUT ITIf you can't bear to read through all the details below, just watch this 19-minute screencast explaining this VS2010 feature. Alternatively, or even additionally, keep on reading.REQUIREMENTWhen you debug an MPI application, you would want the copying of resources from your client machine (where Visual Studio is installed) to each compute node (where Windows HPC Server is installed) to take place automatically for you. 'Resources' in the previous sentence includes your application binary, plus any binary or data dependencies it may have, plus PDBs if needed, plus the debug CRT of the correct bitness, plus msvsmon for remote debugging to work. You would also want, after copying is complete, to have your app and msvsmon launched and attached so that you can hit breakpoints back in Visual Studio on your client machine. All these thing that you would want are delivered in VS2010.STEPS TO F51. In your MPI project where you have placed a breakpoint go to Project Properties - Configuration Properties - Debugging. Ensure the "Debugger to launch" combo box value is set to MPI Cluster Debugger.2. There are a whole bunch of properties here and typically you can ignore all of them except one: Run Environment. By default it is set to run 1 process on your local machine and if you change the number after that to, for example, 4 it will launch 4 processes of your app on your local machine.You want this to run on your cluster though, so go to the dropdown arrow at the end of the Run Environment cell and open it to expose the "Edit Hpc node" menu which opens the Node Selector dialog:In this dialog you can enter (or pick from a list) the cluster head node name and then the number of processes you want to execute on the cluster and then hit OK and… you are done.3. Press F5 and watch your breakpoint get hit (after giving it some time for copying, remote execution, attachment and symbol resolution to take place).GOING DEEPERIn the MPI Cluster Debugger project properties above, you can see many additional properties to the Run Environment. They are all optional, but you may want to understand them in order to fine tune your cluster debugging. Read all about each one of these on the MSDN page Configuration Properties for the MPI Cluster Debugger.In the Node Selector dialog above you can see more options than just the Head Node name and Number of Process to run. They should be self-explanatory but I also cover them in depth in my screencast showing you an example of why you would choose to schedule processes per core versus per node. You can also read about these options on MSDN as part of the page How to: Configure and Launch the MPI Cluster Debugger.To read through an example that touches on MPI project creation, project properties, node selector, and also usage of MPI with OpenMP plus MPI with PPL, read the MSDN page Walkthrough: Launching the MPI Cluster Debugger in Visual Studio 2010.Happy MPI debugging! Comments about this post welcome at the original blog.

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• From DBA to Data Analyst

  - by Denise McInerney

  Cross posted from the PASS Blog There is a lot changing in the data professional’s world these days. More data is being produced and stored. More enterprises are trying to use that data to improve their products and services and understand their customers better. More data platforms and tools seem to be crowding the market. For a traditional DBA this can be a confusing and perhaps unsettling time. It’s also a time that offers great opportunity for career growth. I speak from personal experience. We sometimes refer to the “accidental DBA”, the person who finds herself suddenly responsible for managing the database because she has some other technical skills. While it was not accidental, six months ago I was unexpectedly offered a chance to transition out of my DBA role and become a data analyst. I have since come to view this offer as a gift, though at the time I wasn’t quite sure what to do with it. Throughout my DBA career I’ve gotten support from my PASS friends and colleagues and they were the first ones I turned to for counsel about this new situation. Everyone was encouraging and I received two pieces of valuable advice: first, leverage what I already know about data and second, work to understand the business’ needs. Bringing the power of data to bear to solve business problems is really the heart of the job. The challenge is figuring out how to do that. PASS had been the source of much of my technical training as a DBA, so I naturally started there to begin my Business Intelligence education. Once again the Virtual Chapter webinars, local chapter meetings and SQL Saturdays have been invaluable. I work in a large company where we are fortunate to have some very talented data scientists and analysts. These colleagues have been generous with their time and advice. I also took a statistics class through Coursera where I got a refresher in statistics and an introduction to the R programming language. And that’s not the end of the free resources available to someone wanting to acquire new skills. There are many knowledgeable Business Intelligence and Analytics professionals who teach through their blogs. Every day I can learn something new from one of these experts. Sometimes we plan our next career move and sometimes it just happens. Either way a database professional who follows industry developments and acquires new skills will be better prepared when change comes. Take the opportunity to learn something about the changing data landscape and attend a Business Intelligence, Business Analytics or Big Data Virtual Chapter meeting. And if you are moving into this new world of data consider attending the PASS Business Analytics Conference in April where you can meet and learn from those who are already on that road. It’s been said that “the only thing constant is change.” That’s never been more true for the data professional than it is today. But if you are someone who loves data and grasps its potential you are in the right place at the right time.

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• MPI Cluster Debugger launch integration in VS2010

  Let's assume that you have all the HPC bits installed and that you have existing MPI code (or you created a "Hello World" project using the MPI project template). Of course, you create a single MPI application and at runtime it will correspond to multiple processes (of the same app) launched on multiple nodes (i.e. machines) on the cluster. So how do you debug such a situation by simply hitting the familiar "F5" keystroke (i.e. Debug - Start Debugging)?WATCH IT INSTEAD OF READING ABOUT ITIf you can't bear to read through all the details below, just watch this 19-minute screencast explaining this VS2010 feature. Alternatively, or even additionally, keep on reading.REQUIREMENTWhen you debug an MPI application, you would want the copying of resources from your client machine (where Visual Studio is installed) to each compute node (where Windows HPC Server is installed) to take place automatically for you. 'Resources' in the previous sentence includes your application binary, plus any binary or data dependencies it may have, plus PDBs if needed, plus the debug CRT of the correct bitness, plus msvsmon for remote debugging to work. You would also want, after copying is complete, to have your app and msvsmon launched and attached so that you can hit breakpoints back in Visual Studio on your client machine. All these thing that you would want are delivered in VS2010.STEPS TO F51. In your MPI project where you have placed a breakpoint go to Project Properties - Configuration Properties - Debugging. Ensure the "Debugger to launch" combo box value is set to MPI Cluster Debugger.2. There are a whole bunch of properties here and typically you can ignore all of them except one: Run Environment. By default it is set to run 1 process on your local machine and if you change the number after that to, for example, 4 it will launch 4 processes of your app on your local machine.You want this to run on your cluster though, so go to the dropdown arrow at the end of the Run Environment cell and open it to expose the "Edit Hpc node" menu which opens the Node Selector dialog:In this dialog you can enter (or pick from a list) the cluster head node name and then the number of processes you want to execute on the cluster and then hit OK and… you are done.3. Press F5 and watch your breakpoint get hit (after giving it some time for copying, remote execution, attachment and symbol resolution to take place).GOING DEEPERIn the MPI Cluster Debugger project properties above, you can see many additional properties to the Run Environment. They are all optional, but you may want to understand them in order to fine tune your cluster debugging. Read all about each one of these on the MSDN page Configuration Properties for the MPI Cluster Debugger.In the Node Selector dialog above you can see more options than just the Head Node name and Number of Process to run. They should be self-explanatory but I also cover them in depth in my screencast showing you an example of why you would choose to schedule processes per core versus per node. You can also read about these options on MSDN as part of the page How to: Configure and Launch the MPI Cluster Debugger.To read through an example that touches on MPI project creation, project properties, node selector, and also usage of MPI with OpenMP plus MPI with PPL, read the MSDN page Walkthrough: Launching the MPI Cluster Debugger in Visual Studio 2010.Happy MPI debugging! Comments about this post welcome at the original blog.

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• How to safely copy an object?

  - by Prog

  This question is going to be a little long. Please bear with me. Something that happened in a project of mine made me think about how to safely copy objects. I'll present the situation I had and then ask a question. There was a class SomeClass: class SomeClass{ Thing[] things; public SomeClass(Thing[] things){ this.things = things; } // irrelevant stuff omitted public SomeClass copy(){ return new SomeClass(things); } } There was another class Processor that takes SomeClass objects, copies them (via someClassInstance.copy()), manipulates the copy's state, and returns the copy. Here it is: class Processor{ public SomeClass processObject(SomeClass object){ SomeClass copy = object.copy(); manipulateTheCopy(copy); return copy; } // irrelevant stuff omitted } I ran this, and it had bugs. I looked into these bugs, and it turned out that the manipulations Processor does on copy actually affect not only the copy, but also the original SomeClass object that was passed into processObject. I found out that it was because the original and the copy shared state - because the original passed it's field things into the copy when creating it. This made me realize that copying objects is harder than simply instantiating them with the same fields as the original. For the two objects to be completely disconnected, without any shared state, each of the fields passed to the copy also has to be copied. And if that object contains other objects - they have to be copied too. And so on. So basically, in order to be able to actually copy an object, each class in the system must have a copy() method, that also invokes copy() on all of it's fields, and so on. So for example, for copy() in SomeClass to work, it needs to look like this: public SomeClass copy(){ Thing[] copyThings = new Thing[things.length]; for(int i=0; i<things.length; i++) copyThings[i] = things[i].copy(); return new SomeClass(copyThings); } And if Thing has object fields of it's own, than it's own copy() method must be appropriate: class Thing{ Apple apple; Pencil pencil; int number; public Thing(Apple apple, Pencil pencil, int number){ this.apple = apple; this.pencil = pencil; this.number = number; } public Thing copy(){ // 'number' is a primitve. return new Thing(apple.getCopy(), pencil.getCopy(), number); } } And so on. Of course, instead of all classes having a copy() method, the copying mechanism can happen in all of the getters and the constructors of classes (unless places where it isn't suitable, for example when the field points to an external object, not to an object that 'is part' of this object). Still, that means that in order to be able to safely copy an object - most classes would have to have copying mechanisms in their getters. My question is divided into two parts: How frequently do you need to get a copy of an object? Is this a regular issue? Is the technique described common and/or reasonable? Or is there a better way to make safe copies of objects? Or is there an easier way to safely copy objects, without them sharing any state?

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• Libgdx 2D Game, Random generated World of random size, how to get mouse coordinates?

  - by Solom

  I'm a noob and English is not my mothertongue, so please bear with me! I'm generating a map for a Sidescroller out of a 2D-array. That is, the array holds different values and I create blocks based on that value. Now, my problem is to match mouse coordinates on screen with the actual block the mouse is pointing at. public class GameScreen implements Screen { private static final int WIDTH = 100; private static final int HEIGHT = 70; private OrthographicCamera camera; private Rectangle glViewport; private Spritebatch spriteBatch; private Map map; private Block block; ... @Override public void show() { camera = new OrthographicCamera(WIDTH, HEIGHT); camera.position.set(WIDTH/2, HEIGHT/2, 0); glViewport = new Rectangle(0, 0, WIDTH, HEIGHT); map = new Map(16384, 256); map.printTileMap(); // Debugging only spriteBatch = new SpriteBatch(); } @Override public void render(float delta) { // Clear previous frame Gdx.gl.glClearColor(1, 1, 1, 1 ); Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT); GL30 gl = Gdx.graphics.getGL30(); // gl.glViewport((int) glViewport.x, (int) glViewport.y, (int) glViewport.width, (int) glViewport.height); spriteBatch.setProjectionMatrix(camera.combined); camera.update(); spriteBatch.begin(); // Draw Map this.drawMap(); // spriteBatch.flush(); spriteBatch.end(); } private void drawMap() { for(int a = 0; a < map.getHeight(); a++) { // Bounds check (y) if(camera.position.y + camera.viewportHeight < a)// || camera.position.y - camera.viewportHeight > a) break; for(int b = 0; b < map.getWidth(); b++) { // Bounds check (x) if(camera.position.x + camera.viewportWidth < b)// || camera.position.x > b) break; // Dynamic rendering via BlockManager int id = map.getTileMap()[a][b]; Block block = BlockManager.map.get(id); if(block != null) // Check if Air { block.setPosition(b, a); spriteBatch.draw(block.getTexture(), b, a, 1 ,1); } } } } As you can see, I don't use the viewport anywhere. Not sure if I need it somewhere down the road. So, the map is 16384 blocks wide. One block is 16 pixels in size. One of my naive approaches was this: if(Gdx.input.isButtonPressed(Input.Buttons.LEFT)) { Vector3 mousePos = new Vector3(); mousePos.set(Gdx.input.getX(), Gdx.input.getY(), 0); camera.unproject(mousePos); System.out.println(Math.round(mousePos.x)); // *16); // Debugging // TODO: round // map.getTileMap()[mousePos.x][mousePos.y] = 2; // Draw at mouse position } I confused myself somewhere down the road I fear. What I want to do is, update the "block" (or rather the information in the Map/2D-Array) so that in the next render() there is another block. Basically drawing on the spriteBatch g So if anyone could point me in the right direction this would be highly appreciated. Thanks!

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• Is this Hybrid of Interface / Composition kosher?

  - by paul

  I'm working on a project in which I'm considering using a hybrid of interfaces and composition as a single thing. What I mean by this is having a contain*ee* class be used as a front for functionality implemented in a contain*er* class, where the container exposes the containee as a public property. Example (pseudocode): class Visibility(lambda doShow, lambda doHide, lambda isVisible) public method Show() {...} public method Hide() {...} public property IsVisible public event Shown public event Hidden class SomeClassWithVisibility private member visibility = new Visibility(doShow, doHide, isVisible) public property Visibility with get() = visibility private method doShow() {...} private method doHide() {...} private method isVisible() {...} There are three reasons I'm considering this: The language in which I'm working (F#) has some annoyances w.r.t. implementing interfaces the way I need to (unless I'm missing something) and this will help avoid a lot of boilerplate code. The containee classes could really be considered properties of the container class(es); i.e. there seems to be a fairly strong has-a relationship. The containee classes will likely implement code which would have been pretty much the same when implemented in all the container classes, so why not do it once in one place? In the above example, this would include managing and emitting the Shown/Hidden events. Does anyone see any isseus with this Composiface/Intersition method, or know of a better way? EDIT 2012.07.26 - It seems a little background information is warranted: Where I work, we have a bunch of application front-ends that have limited access to system resources -- they need access to these resources to fully function. To remedy this we have a back-end application that can access the needed resources, with which the front-ends can communicate. (There is an API written for the front-ends for accessing back-end functionality as though it were part of the front-end.) The back-end program is out of date and its functionality is incomplete. It has made the transition from company to company a couple of times and we can't even compile it anymore. So I'm trying to rewrite it in my spare time. I'm trying to update things to make a nice(r) interface/API for the front-ends (while allowing for backwards compatibility with older front-ends), hopefully something full of OOPy goodness. The thing is, I don't want to write the front-end API after I've written pretty much the same code in F# for implementing the back-end; so, what I'm planning on doing is applying attributes to classes/methods/properties that I would like to have code for in the API then generate this code from the F# assembly using reflection. The method outlined in this question is a possible alternative I'm considering instead of implementing straight interfaces on the classes in F# because they're kind of a bear: In order to access something of an interface that has been implemented in a class, you have to explicitly cast an instance of that class to the interface type. This would make things painful when getting calls from the front-ends. If you don't want to have to do this, you have to call out all of the interface's methods/properties again in the class, outside of the interface implementation (which is separate from regular class members), and call the implementation's members. This is basically repeating the same code, which is what I'm trying to avoid!

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• Why Apple’s New SDK Limitation is So Offensive

  - by TStewartDev

  I am not an Apple fanboy, nor have I ever been. However, I have owned a Mac, an iPod, and an iPhone in my lifetime, and for more than a decade, I have defended Apple against the untruths that the haters so enjoy spewing. I encouraged my wife to buy a MacBook when she needed a new laptop two years ago, and I often recommend them to my friends and relatives. I have proudly and happily used my first generation iPhone for nearly three years. Now, for the first time in well over ten years, I find myself ready to swear off Apple and encourage everyone I know to do the same. I was disappointed when Apple wouldn't allow native apps, but I still bought the iPhone. I've stomached their ambiguous app approval process even though it's apparent that Steve may just reject your app because he doesn't like you or feels threatened by you (I'm still lamenting the rejection of the Google Voice app). But, as a developer, I can no longer tolerate Apple's terms and the kind of totalitarian control they indicate Apple wants. In case you are not already familiar, Apple has dictated in their OS 4.0 SDK license agreement (the now infamous Section 3.3.1) that all apps developed for the iPhone must be coded in C, C++, or Objective C, and moreover, that using any cross-compiling platforms is a violation of the agreement. For those of you who aren't developers, let me try to illustrate why this angers those of us who are. Imagine you're a professional writer. You've had articles published in some journals and magazines, and you've got a couple popular books out there, too. You've got an idea for a new book, and so you take it to your publisher. Your publisher agrees that it's a good idea. "But," says the publisher, "we want to hold our books to a tighter standard so that our readers get the experience we want them to have. Therefore, from now on, all our writers may only use words from this list of the 10,000 most common English words. Furthermore, if you cite any other works or quote anyone, they must comply with that same list, or you'll have to rewrite the entire work as well in case our readers want to look up your citation." What do you do? If your work is a children's book, this probably isn't a big deal to you. If it's an autobiography, textbook, or even a novel, though, you're going to have a lot of trouble describing your content with only common words. It's going to take you longer to complete your book, too, since you'll be looking up less common words frequently to see if you can use them. You could always go to another publisher, but this one has the best ability to distribute your book. The next largest distributor can only do a quarter as much. You could abandon the project altogether, but then everyone loses. Isn't this a silly scenario? Who would put such a limitation on writers? Yet this is very much what Apple is doing. They are using their dominant position in the market to coerce developers to write their apps exclusively for the iPhone OS by making it too expensive to write for multiple platforms. It is at least a threefold attack, striking at Adobe who is set to release a compiler that lets Flash source be compiled to iPhone binaries; striking at Google whose Android platform stands the best chance at the moment of providing serious competition to the iPhone; and reinforcing their own strong position by keeping popular apps exclusively to iPhone. And while developers are already very upset about this, the sad fact is that most of us will cave and give in to Apple because consumers don't know any better. They will continue to buy Apple's toy forcing developers to play Apple's maniacal game in order to make any money, at least until Steve Jobs decides he doesn't like them or he intends to release a competing application (bye-bye OpenFeint). Apple has been kept in check on the desktop front by a very dominant Microsoft, but I'm afraid that their success with iPods, iTunes, and iPhones has created a monster that we may have to bear until it is slain by an anti-trust suit or dies with the retirement of Steve Jobs.

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• PCI Encryption Key Management

  - by Unicorn Bob

  (Full disclosure: I'm already an active participant here and at StackOverflow, but for reasons that should hopefully be obvious, I'm choosing to ask this particular question anonymously). I currently work for a small software shop that produces software that's sold commercially to manage small- to mid-size business in a couple of fairly specialized industries. Because these industries are customer-facing, a large portion of the software is related to storing and managing customer information. In particular, the storage (and securing) of customer credit card information. With that, of course, comes PCI compliance. To make a long story short, I'm left with a couple of questions about why certain things were done the way they were, and I'm unfortunately without much of a resource at the moment. This is a very small shop (I report directly to the owner, as does the only other full-time employee), and the owner doesn't have an answer to these questions, and the previous developer is...err...unavailable. Issue 1: Periodic Re-encryption As of now, the software prompts the user to do a wholesale re-encryption of all of the sensitive information in the database (basically credit card numbers and user passwords) if either of these conditions is true: There are any NON-encrypted pieces of sensitive information in the database (added through a manual database statement instead of through the business object, for example). This should not happen during the ordinary use of the software. The current key has been in use for more than a particular period of time. I believe it's 12 months, but I'm not certain of that. The point here is that the key "expires". This is my first foray into commercial solution development that deals with PCI, so I am unfortunately uneducated on the practices involved. Is there some aspect of PCI compliance that mandates (or even just strongly recommends) periodic key updating? This isn't a huge issue for me other than I don't currently have a good explanation to give to end users if they ask why they are being prompted to run it. Question 1: Is the concept of key expiration standard, and, if so, is that simply industry-standard or an element of PCI? Issue 2: Key Storage Here's my real issue...the encryption key is stored in the database, just obfuscated. The key is padded on the left and right with a few garbage bytes and some bits are twiddled, but fundamentally there's nothing stopping an enterprising person from examining our (dotfuscated) code, determining the pattern used to turn the stored key into the real key, then using that key to run amok. This seems like a horrible practice to me, but I want to make sure that this isn't just one of those "grin and bear it" practices that people in this industry have taken to. I have developed an alternative approach that would prevent such an attack, but I'm just looking for a sanity check here. Question 2: Is this method of key storage--namely storing the key in the database using an obfuscation method that exists in client code--normal or crazy? Believe me, I know that free advice is worth every penny that I've paid for it, nobody here is an attorney (or at least isn't offering legal advice), caveat emptor, etc. etc., but I'm looking for any input that you all can provide. Thank you in advance!

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• DVD Drive Failing on Windows 7

  - by Seth Spearman

  Hello, I have x64 Windows 7 running on an ASUS M50VM. The DVD drive works completely unreliably if not at all. But the story is not that simple so bear with me...here are the gory details. When I first got the machine it came with Windows XP and I upgraded it to Windows Vista X64 and the DVD worked fine. When Windows 7 RC2 came out I tried it on a Virtual Machine and I liked it so much that I upgraded the machine to Win7 RC1. The DVD worked fine. Of course, RC1 was going to start spontaneously rebooting, so when Windows 7 was released I DID A CLEAN INSTALL of Windows 7. Just to clarify...by clean install I mean I did a FORMAT of the HARD DRIVE and INSTALLED it from scratch. EVER since then the DVD mostly doesn't work. I can sometime read from disk but that will often hang. (Please see my description below of HANG for details.) CD or DVD writes ALWAYS fail with a HANG (I have done a successful write only one time.) Here is what I mean by HANG... *Explorer Window is unresponsive. *Any software accessing the DVD drive is unresponsive. *The DVD tray will not eject. *Using a paper clip will eject but the disk is usually spinning real hard. *Attempting to shut down windows will fail. I have waited as long as ten minutes but the whole OS seems to hang. I do a hard shutdown. *Sometimes accessing the DVD (when it does not cause a HANG) will still fail and the device will actually seem to disappear from the system until I reboot. A couple of other things. It is NOT a hardware failure. It is the Windows OS. I know this because I swapped out my DVD drive with a friend with the same model...his machine is fine (he is still running Vista X64) and my machine still fails. For what it is worth. I swapped out my primary disk with the INTEL 160GB SSD. EDIT Here is what System Information shows about my DVD drive Drive D: Description CD-ROM Drive Media Loaded No Media Type DVD Writer Name HL-DT-ST DVDRAM GSA-T50N ATA Device Manufacturer (Standard CD-ROM drives) Status OK Transfer Rate -1.00 kbytes/sec SCSI Target ID 0 PNP Device ID IDE\CDROMHL-DT-ST_DVDRAM_GSA-T50N________________RR04____\5&2B5B7F1D&0&1.0.0 Driver c:\windows\system32\drivers\cdrom.sys (6.1.7600.16385, 144.00 KB (147,456 bytes), 7/13/2009 7:19 PM) Any ideas? HELP! Seth B Spearman

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• DVD Drive Failing on Windows 7

  - by Seth Spearman

  I have x64 Windows 7 running on an ASUS M50VM. The DVD drive works completely unreliably if not at all. But the story is not that simple so bear with me...here are the gory details. When I first got the machine it came with Windows XP and I upgraded it to Windows Vista X64 and the DVD worked fine. When Windows 7 RC2 came out I tried it on a Virtual Machine and I liked it so much that I upgraded the machine to Win7 RC1. The DVD worked fine. Of course, RC1 was going to start spontaneously rebooting, so when Windows 7 was released I DID A CLEAN INSTALL of Windows 7. Just to clarify...by clean install I mean I did a FORMAT of the HARD DRIVE and INSTALLED it from scratch. EVER since then the DVD mostly doesn't work. I can sometime read from disk but that will often hang. (Please see my description below of HANG for details.) CD or DVD writes ALWAYS fail with a HANG (I have done a successful write only one time.) Here is what I mean by HANG... *Explorer Window is unresponsive. *Any software accessing the DVD drive is unresponsive. *The DVD tray will not eject. *Using a paper clip will eject but the disk is usually spinning real hard. *Attempting to shut down windows will fail. I have waited as long as ten minutes but the whole OS seems to hang. I do a hard shutdown. *Sometimes accessing the DVD (when it does not cause a HANG) will still fail and the device will actually seem to disappear from the system until I reboot. A couple of other things. It is NOT a hardware failure. It is the Windows OS. I know this because I swapped out my DVD drive with a friend with the same model...his machine is fine (he is still running Vista X64) and my machine still fails. For what it is worth. I swapped out my primary disk with the INTEL 160GB SSD. EDIT Here is what System Information shows about my DVD drive Drive D: Description CD-ROM Drive Media Loaded No Media Type DVD Writer Name HL-DT-ST DVDRAM GSA-T50N ATA Device Manufacturer (Standard CD-ROM drives) Status OK Transfer Rate -1.00 kbytes/sec SCSI Target ID 0 PNP Device ID IDE\CDROMHL-DT-ST_DVDRAM_GSA-T50N________________RR04____\5&2B5B7F1D&0&1.0.0 Driver c:\windows\system32\drivers\cdrom.sys (6.1.7600.16385, 144.00 KB (147,456 bytes), 7/13/2009 7:19 PM) Any ideas? HELP! Seth B Spearman

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• Vagrant reporting VirtualBox guest additions out of date

  - by DTest

  Fairly new to Vagrant, so bear with me if I don't understand the process. I downloaded a CentOS box off http://www.vagrantbox.es/ Started it up running VirtualBox 4.2.4 and got this message: [default] The guest additions on this VM do not match the install version of VirtualBox! This may cause things such as forwarded ports, shared folders, and more to not work properly. If any of those things fail on this machine, please update the guest additions and repackage the box. Guest Additions Version: 4.0.8 VirtualBox Version: 4.2.4 So I used the vbguest plugin to update the guest additions, then repackaged the box as suggested. Having replaced the old box and loading it up I get the same message about guest additions being outdated, but vbguest reports that they are up to date (the automatic vbguest update is disabled in my Vagrantfile): Vagrant::Config.run do |config| config.vm.box = "centos56_64" config.vbguest.auto_update = false config.vbguest.no_remote = true end And the commands: dtest$ vagrant up [default] Importing base box 'centos56_64'... [default] The guest additions on this VM do not match the install version of VirtualBox! This may cause things such as forwarded ports, shared folders, and more to not work properly. If any of those things fail on this machine, please update the guest additions and repackage the box. Guest Additions Version: 4.0.8 VirtualBox Version: 4.2.4 [default] Matching MAC address for NAT networking... [default] Clearing any previously set forwarded ports... [default] Forwarding ports... [default] -- 22 => 2222 (adapter 1) [default] Creating shared folders metadata... [default] Clearing any previously set network interfaces... [default] Booting VM... [default] Waiting for VM to boot. This can take a few minutes. [default] VM booted and ready for use! [default] Mounting shared folders... [default] -- v-root: /vagrant dtest$ vagrant vbguest --no-install [default] Detected Virtualbox Guest Additions 4.2.4 --- OK. [default] Virtualbox Guest Additions on host: 4.2.4 - guest's version is 4.2.4 Since they appear to be updated after an install, I could ignore the message. But is it possible to get rid of it?

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• Windows cannot find the host name "download.microsoft.com" using DNS

  - by joedotnot

  When trying to download a file found on the Microsoft downloads center that starts with, for example, http://download.microsoft.com/download/6/8/7/(some_GUID)/(some_file_name.ext) i get a timeout with "Internet Explorer cannot display the webpage". More information says: Internet connectivity has been lost. The website is temporarily unavailable. The Domain Name Server (DNS) is not reachable. The Domain Name Server (DNS) does not have a listing for the website's domain. If this is an HTTPS (secure) address, click Tools, click Internet Options, click Advanced, and check to be sure the SSL and TLS protocols are enabled under the security section. Diagnose Connection problems says: Windows cannot find the host name "download.microsoft.com" using DNS Bear with me while i expand on the problem: It all started when i tried to download Windows XP mode for my Windows 7 machine. I went to the virtual PC site, then thru the motions of Windows Genuine Advantage which validated ok, but when it redirects to grab the file just times out with above error. (NB: i also tried with the latest Chrome and Firefox but no use due to the Genuine Advantage stuff, so i decided to stick with IE). I am behind an ADSL2+ modem router connecting via wireless (Win 7 Pro laptop); so i hop over to the desktop connected via ethernet (Vista Business), and same result; begin to think site download.microsoft.com site is down. So i give it a break an read up on EDNS, flushing the cache, hosts file, etc... Try again an hour later on the Win 7 machine, still no go; so i turn off the Win 7 (software) firewall, and lo and behold, i can connect and grab any files from download.microsoft.com; (...nice, so we have a Micro$0ft firewall preventing access to a Micro$0ft website, no wonder my auto-updates kept failing but that's another story). But i still am not happy that the desktop connected via ethernet still cannot get to download.microsoft.com, even though i turned off all firewalls, defenders, anti-virus, etc. What is so special / specific about the url download.microsoft.com, any other site is ok, including www.microsoft.com. Any networking guru know what's REALLY going on, and how can i get the desktop to connect? Ping download.microsoft.com - Ping request could not find host download.microsoft.com. Please check the name and try again. Ping google.com or even www.microsoft.com works gives me an IP address. NB: On the wireless laptop ping download.microsoft.com works, i get xxxx.ms.akamai.net [202.7.177.33].

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• How should I set up my Hyper-V server and network topology?

  - by Daniel Waechter

  This is my first time setting up either Hyper-V or Windows 2008, so please bear with me. I am setting up a pretty decent server running Windows Server 2008 R2 to be a remote (colocated) Hyper-V host. It will be hosting Linux and Windows VMs, initially for developers to use but eventually also to do some web hosting and other tasks. Currently I have two VMs, one Windows and one Ubuntu Linux, running pretty well, and I plan to clone them for future use. Right now I'm considering the best ways to configure developer and administrator access to the server once it is moved into the colocation facility, and I'm seeking advice on that. My thought is to set up a VPN for access to certain features of the VMs on the server, but I have a few different options for going about this: Connect the server to an existing hardware firewall (an old-ish Netscreen 5-GT) that can create a VPN and map external IPs to the VMs, which will have their own IPs exposed through the virtual interface. One problem with this choice is that I'm the only one trained on the Netscreen, and its interface is a bit baroque, so others may have difficulty maintaining it. Advantage is that I already know how to do it, and I know it will do what I need. Connect the server directly to the network and configure the Windows 2008 firewall to restrict access to the VMs and set up a VPN. I haven't done this before, so it will have a learning curve, but I'm willing to learn if this option is better long-term than the Netscreen. Another advantage is that I won't have to train anyone on the Netscreen interface. Still, I'm not certain if the capabilities of the Windows software firewall as far as creating VPNs, setting up rules for external access to certain ports on the IPs of Hyper-V servers, etc. Will it be sufficient for my needs and easy enough to set up / maintain? Anything else? What are the limitations of my approaches? What are the best practices / what has worked well for you? Remember that I need to set up developer access as well as consumer access to some services. Is a VPN even the right choice?

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• Rsync: windows 7, synology: login error and permission denied error

  - by loonboon

  Good day to all of you all, I'm running into strange/stupid errors, and I hope anybody would be so kind to help me out. I have to admit, I am by no means a guru, so please bear with me :-) Situation: -Synology NAS (runs Linux), and Windows 7 desktop (1 normal/restricted user Lisa and 1 admin user). - Data from W7 desktop to be rsynced to synology: /volume1/home/Lisa/Backup - Rsync command: c:\cygwin\bin\rsync -avz /cygdrive/e/Lisa/ [email protected]:/volume1/homes/Lisa/Backup - I've set up ssh per these two threads: a. http://www.cesareriva.com/archives/102 b. http://www.cesareriva.com/archives/112 Now the horrors begin: - root is allowed to run the rsync succesfully, however, he doesn't login automatically (so I can not use rsync in W7 batchscripts, which is of course required). - Lisa is allowed to login automatically but he can not succesfully finish the rsync command because of permission errors: rsync change dir /volume1/homes/Lisa/Backup failed: permissions denied. This happens for each and every file and subdir rsync tries to create. However, the main directory (Backup) is created. When I try to copy files from windows explorer to the directory 'Backup' using the very same user Lisa everything goes smoothly. So, obviously, there is a permission problem somewhere; either my rsync-command isn't correct, or the folder permissions for homes/Lisa aren't correct (but, then again, Windows 7 copies files to that folder without any problems, so that does make me believe the homes/Lisa-permissions don't appear to be the problem). I also tried adding: --chmod=Dugo+x --chmod=ugo+r which I found somewhere on the web, to the rsync-command, but this didn't solve any problem and gave the exact errors. Would anybody please please help me on how to fix this? I am utterly frustrated about this, because I have been trying for 1 month to get everything to work and it simply doesn't work. I bought the big Synology to end the horrors of 20 external USB-disks for once and for all (we have many pictures and home vids of our deceased dogs and want to watch these, the horrors being 'what material is on what disk'). I'll gladly return the favour of somebody helping me out by buying you a nice beer (paypal), if you could end my misery. I am not extremely skilled on Linux (not at all :-( ) so if you could give an extra word when possible so I understand what to do, I'd be very grateful. I really hope somebody can help me out, Thank you in advance, Lisa

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• Microsoft Office 2003 document (Excel and Word) intermitently, takes 30 seconds to load

  - by Julio Nobre

  I am trying to figure out why a simple .XLS EXCEL workbook is taking, randomly, 30 seconds to open. Before answering: Please, bear mind the following: Problem symptoms Hanging is intermitent and it takes exactly 30 seconds; During hanging there is no cpu or disk activity; It only happens during document load. Every runs smooth after that; Windows Explorer.exe hangs on folder, but all other folders, system and applications are still responsive; There are no consecutive hangings. I have to wait for while to reproduce this behaviour; All samples documents are located on a local drive (C:\BPI); The no document has has macros and have any addins usage; The problem does occurs on others files extensions like .PDF, for example; Office 2003 is being used for several years; The computer is running Windows XP; Computer has several network mapped drives, all addressed to main file server; Recently, main fileserver was replaced by Windows 2011 SBS Standard Edition What I have done so far I have traced machine Explorer.exe, using Process Monitor, added Duration column, and filtered by Duration 1. That's is how I found that hanging was taking exactly 30 seconds. For further information, please refer to Oliver Salzburg tutorial. Using Process Monitor, I have also figured out than five operations were taking most of sample collecting duration. Looking at sample image below, column Operation below you will notice that one single operation was taking 29 seconds; I have tried different documents (.xls and .doc), all of them smaller than 30 KB; I have, temporarily, removed all shortcuts on User Document's folder that were pointing to network drives or shares; I have runned CCleaner to fix registry issues; I made sure that there were no external links on tested workbook or word documents; I have reproduced this behaviour for hours; I have extensivelly researched for hours on the web; Process Monitor's collected and filtered data

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• Need advice on which PCI SATA Controller Card to Purchase

  - by Matt1776

  I have a major issue with the build of a machine I am trying to get up and running. My goal is to create a file server that will service the needs of my software development, personal media storage and streaming/media server needs, as well as provide a strong platform for backing up all this data in a routine, cron-job oriented German efficiency sort of way. The issue is a simple one - all my drives are SATA drives and my motherboard controller only contains 4 ports. Solving the issue has proven to be an unmitigated nightmare. I would like advice on the purchase of the following: 4 Port internal SATA / 2 Port external eSATA PCI SATA Controller Card that has the following features and/or advantages: It must function. If I plug it in and attach drives, I expect my system to still make it to the Operating System login screen. It must function on CentOS, and I mean it must function WELL and with MINIMAL hassle. If hassle is unavoidable, there shall be CLEAR CUT and EASY TO FOLLOW instructions on how to install drivers and other supporting software. I do not need nor want fakeRAID - I will be setting up any RAID configurations from within the operating system. Now, if I am able to find such a mythical device, I would be eternally grateful to whomever would be able to point me in the right direction, a direction which I assume will be paved with yellow bricks. I am prepared to pay a considerable sum of money (as SATA controller cards go) and so paying anywhere between 60 to 120 dollars will not be an issue whatsoever. Does such a magical device exist? The following link shows an "example" of the type of thing I am looking for, however, I have no way of verifying that once I plug this baby in that my system will still continue to function once I've attached the drives, or that once I've made it to the OS, I will be able to install whatever drivers or software programs I need to make it work with relative ease. It doesn't have to be dog-shit simple, but it cannot involve kernels or brain surgery. http://www.amazon.com/gp/product/B00552PLN4/ref=pd_lpo_k2_dp_sr_1?pf_rd_p=486539851&pf_rd_s=lpo-top-stripe-1&pf_rd_t=201&pf_rd_i=B003GSGMPU&pf_rd_m=ATVPDKIKX0DER&pf_rd_r=1HJG60XTZFJ48Z173HKY So does anyone have a suggestion regarding the subject I am asking about? PCI SATA Controller Cards? It would help if you've had experience with the component before - that is after all why I am asking here - for those who have had experience that I do not have. Bear in mind that this is for a home setup and that I do not have a company credit card. I have a budget with a 'relative' upper limit of about $150.00.

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• Nginx Proxying to Multiple IP Addresses for CMS' Website Preview

  - by Matthew Borgman

  First-time poster, so bear with me. I'm relatively new to Nginx, but have managed to figure out what I've needed... until now. Nginx v1.0.15 is proxying to PHP-FPM v.5.3.10, which is listening at http://127.0.0.1:9000. [Knock on wood] everything has been running smoothly in terms of hosting our CMS and many websites. Now, we've developed our CMS and configured Nginx such that each supported website has a preview URL (e.g. http://[WebsiteID].ourcms.com/) where the site can be, you guessed it, previewed in those situations where DNS doesn't yet resolve to our server, etc. Specifically, we use Nginx's Map module (http://wiki.nginx.org/HttpMapModule) and a regular expression in the server_name of the CMS' server{ } block to 1) lookup a website's primary domain name from its preview URL and then 2) forward the request to the "matched" primary domain. The corresponding Nginx configuration: map $host $h { 123.ourcms.com www.example1.com; 456.ourcms.com www.example2.com; 789.ourcms.com www.example3.com; } and server { listen [OurCMSIPAddress]:80; listen [OurCMSIPAddress]:443 ssl; root /var/www/ourcms.com; server_name ~^(.*)\.ourcms\.com$; ssl_certificate /etc/nginx/conf.d/ourcms.com.chained.crt; ssl_certificate_key /etc/nginx/conf.d/ourcms.com.key; location / { proxy_pass http://127.0.0.1/; proxy_set_header Host $h; proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for; } } (Note: I do realize that the regex in the server_name should be "tighter" for security reasons and match only the format of the website ID (i.e. a UUID in our case).) This configuration works for 99% of our sites... except those that have a dedicated IP address for an installed SSL certificate. A "502 Bad Gateway" is returned for these and I'm unsure as to why. This is how I think the current configuration works for any requests that match the regex (e.g. http://123.ourcms.com/): Nginx looks up the website's primary domain from the mapping, and as a result of the proxy_pass http://127.0.0.1 directive, passes the request back to Nginx itself, which since the proxied request has a hostname corresponding to the website's primary domain name, via the proxy_set_header Host $h directive, Nginx handles the request as if it was as direct request for that hostname. Please correct me if I'm wrong in this understanding. Should I be proxying to those website's dedicated IP addresses? I tried this, but it didn't seem to work? Is there a setting in the Proxy module that I'm missing? Thanks for the help. MB

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• Should use EXT4 or XFS to be able to 'sync'/backup to S3?

  - by Rafa

  It's my first message here, so bear with me... (I have already checked quite a few of the "Related Questions" suggested by the editor) Here's the setup, a brand new dedicated server (8GB RAM, some 140+ GB disk, Raid 1 via HW controller, 15000 RPM) it's a production web server (with MySQL in it, too, not just serving web requests); not a personal desktop computer or similar. Ubuntu Server 64bit 10.04 LTS We have an Amazon EC2+EBS setup with the EBS volume formatted as XFS for easily taking snapshots to S3, via AWS' console. We are now migrating to the dedicated server and I want to be able to backup our data to Amazon's S3. The main reason being the possibility of using the latest snapshot from an EC2 instance in case of hardware failure on the dedicated server. There are two approaches I am thinking of: do a "simple" file-based backup with rsync, dumping the database' and other files, and uploading to amazon via S3 API commands, or to an EC2 instance, or something. do a file-system "freeze" (using XFS) with the usual ebs/ec2 snapshot tool to take part of the file system, take a snapshot, and upload it to Amazon. Here's my question (or series of questions): Can I safely use XFS for the whole system as the main and only format on the dedicated server? If not, is it safe to use EXT4? Or should I use something else? would then be possible to make snapshots of the system to upload to Amazon? Is it possible/feasible/practical to do what I want to do, anyway? any recommendations? When searching around for S3/EBS/XFS, anything relevant to my problem is usually focused on taking snapshots of a XFS system that is already an EBS volume. My intention is to do it in a "real"/metal dedicated server. Update: I just saw this on Wikipedia: XFS does not provide direct support for snapshots, as it expects the snapshot process to be implemented by the volume manager. I had always assumed that I could choose 2 ways of doing snapshots: via LVM or via XFS (without LVM). After reading this, I realize these 2 options are more like it: With XFS: 1) do xfs_freeze; 2) copy the frozen files via, eg, rsync; 3) unfreeze xfs With LVM and XFS: 1) do xfs_freeze; 2) make a binary copy of the frozen fs via lvcreate and related commands; 3) unfreeze xfs; 4) somehow backup the LVM snapshot. Thanks a lot in advance, Let me know if I need to clarify something.

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• Educate me - should I buy these prebuilt NAS (which is better) or make my own?

  - by user29336

  I'm trying to learn as much as possible, and I think I've learned quite a bit so bear with me here under my confusion. I found a coupe NAS setups. I'm not sure if one is better than the other, other than the price being higher on some, and some coming with drives VS not. Let me list my setup so you can get an idea of what I want to provide: Macbook Pro Macbook Mini for Media streaming (so far) Windows 7 Gaming Computer Xbox 360 I'd like to provide a storage system for all these devices so they can access files very easily, I'd also like any of these devices to be able to stream media from this storage system. I'd like this storage system to be hassle free in terms of my confidence in the data integrity. If a drive fails, I want to know that I can replace the drive and all my files will still exist. I'd like to access this storage system OUTSIDE of my LAN. If I'm out on a job for work I'd like to go in, or be able to have people DL some files. This brings me to a question, is this what iSCSI is? I'd like this data system to be able to download torrents. I want to mount any drive on this storage system onto my OSX laptop as if it were a local drive attached. (Is this with iSCSI is?) I'd like this system to have a GOOD web based GUI. I don't want to install software to use it. I believe those are the most of my requirements. If I'm missing something that I have no knowledge about, can someone educate me? Here are the systems I found: $729ish on Newegg Lacie 5Big Network 2 (comes with 5TB of space. iSCSI / mac compatible, torrents, nice ui, + others?) Is this overpriced for what it provides? It almost seems like a great deal to me because of the 5TB of space it comes with vs the other NAS systems that don't come with storage but cost $600-700. Should I get a different NAS system? Netgear? Others? Do they have same features? Better? Is it better to buy your own disks? What about making my own? I'm tech savy all around. It seems cheaper to buy a premade one especially with the support/warranty it provides...

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• How to tune system settings for mongoDB on Linux?

  - by jsh

  Trying to squeeze a lot out of one question here -- please bear with me. Although the MongoDB man pages make several useful recommendations about system settings like ulimit (http://docs.mongodb.org/manual/reference/ulimit/), and other production factors (http://docs.mongodb.org/manual/administration/production-notes/) they seem mysteriously silent on things like virtual memory and swap settings. The closest we get to a hint is that "...the operating system’s virtual memory subsystem manages MongoDB’s memory..." (http://docs.mongodb.org/manual/faq/fundamentals/#does-mongodb-require-a-lot-of-ram). Running the same job - high writes and high reads on about 10,000,000 records in a single collection -- on my 4-processor, 4GB RAM macbook and an 8-core ubuntu box with 64GB RAM I saw dramatically WORSE read performance on the linux box with factory settings, and could hear the disk constantly spinning, indicating high I/O and presumably swapping. Yes, other things were happening on the box, but there was plenty of free RAM, disk space, etc.; furthermore, I did not see evidence that Mongo was expanding to take advantage of all that free RAM as it is touted to do. Linux box default settings were as follows: vm.swappiness =60 vm.dirty_background_ratio = 10 vm.dirty_ratio = 20 vm.dirty_expire_centisecs =3000 vm.dirty_writeback_centisecs=500 I hazarded some guesses looking at docs and blogs for other types of databases (Oracle, MYSQL, etc.), experimented, and adjusted as below. vm.swappiness=10 vm.dirty_background_ratio=5 vm.dirty_ratio=5 vm.dirty_writeback_centisecs=250 vm.dirty_expire_centisecs=500 I saw some immediate apparent improvements in read time. However, when I ran my test jobs again, read performance continued to be painfully sluggish during heavy writes. Then, I REBUILT the collection from an available data source - and suddenly I can read at 1ms or less per record WHILE doing the write job! So the question is really two-fold: 1) What are appropriate VM settings for MongoDB on Linux? 2) (bonus) Does Mongo do some checking or optimization with the OS while data is being built? In other words, if I have built a large data set with suboptimal VM or I/O settings, does Mongo make assumptions during the memory-mapping process that will fail to take advantage of optimizations down the road? Obviously I don't fully grok memory mapping under the hood (I was hoping I wouldn't have to). Any help appreciated...thanks! -j

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