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  • Dadaism and Agility

    - by alexhildyard
    We all have our little bugbears, and something that has given me particular pause over the years is the place of Agility in the software development life cycle. While I have seen it used successfully on both small and Enterprise-level projects, I have also seen many instances in which long-standing technical debt has also originated under its watch. Ironically the problem in such cases seems to me not that the practitioners in question have failed to follow due process (Test, Develop, Refactor -- a common "what" of Agile), but basically that they have missed the point (the "why" of Agile). It's probably a sign of my age that I'm much more interested in the "why" than the "what", since I feel that the latter falls out naturally from the former, but that this is not a reciprocal relationship.Consider Dadaism, precursor to the Surrealist movement in the early part of the twentieth century. Anyone could stand up and proclaim he or she was Dada; anyone could write cut-ups, or pull words out a hat, or produce gibberish on duelling typewriters under the inspiration of Dada. And all that took place at such performances was a manifestation of Dada, and all the artefacts that resulted were also Dada. Hence one commentator's engimatic observation that 'when one speaks of Dada, then one speaks of Dada. But when one does not speak of Dada, one still speaks of Dada.'What is Dada? Literally, Dada is what you say it is. But that's also missing the point. Dada is about erecting a framework within which utterances like this are valid; Dada is about preparing a stage for itself. Dadaism exemplifies the purity of a process-driven ideology -- in fact an ideology that is almost pure process, with nothing extraneous in the way of formal method, and while perhaps Agile delivery should not embrace the liberties of Dadaism too literally, some of the similarities nevertheless are salutary.Agile -- like Dada -- is an attitude; it is about *being* agile; it is not really about doing a specific set of things that are somehow *part* of being Agile. It is an abstract base rather than an implementation, a characteristic rather than a factor. It is the pragmatic response to the need for change in the face of partial information, ephemeral requirements and a healthy dose of systematic uncertainty. In practice this will usually mean repeatedly making the smallest useful changes to a system, recognising that systems evolve, and that all change carries risk. It will usually mean that instead of investing effort in future-proofing a system against a known technology roadmap, one instead invests one's energies in the daily repetition and incremental development of processes best designed to accommodate change quickly. But though it may mean these things in practice, it isn't actually *about* either of these things; it's about the mindset, the attitude that conceives of such responses as sensible solutions given the larger and ultimately unclassifiable thing that constitutes the development lifecycle of a specific project.

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  • How to refactor my design, if it seems to require multiple inheritance?

    - by Omega
    Recently I made a question about Java classes implementing methods from two sources (kinda like multiple inheritance). However, it was pointed out that this sort of need may be a sign of a design flaw. Hence, it is probably better to address my current design rather than trying to simulate multiple inheritance. Before tackling the actual problem, some background info about a particular mechanic in this framework: It is a simple game development framework. Several components allocate some memory (like pixel data), and it is necessary to get rid of it as soon as you don't need it. Sprites are an example of this. Anyway, I decided to implement something ala Manual-Reference-Counting from Objective-C. Certain classes, like Sprites, contain an internal counter, which is increased when you call retain(), and decreased on release(). Thus the Resource abstract class was created. Any subclass of this will obtain the retain() and release() implementations for free. When its count hits 0 (nobody is using this class), it will call the destroy() method. The subclass needs only to implement destroy(). This is because I don't want to rely on the Garbage Collector to get rid of unused pixel data. Game objects are all subclasses of the Node class - which is the main construction block, as it provides info such as position, size, rotation, etc. See, two classes are used often in my game. Sprites and Labels. Ah... but wait. Sprites contain pixel data, remember? And as such, they need to extend Resource. But this, of course, can't be done. Sprites ARE nodes, hence they must subclass Node. But heck, they are resources too. Why not making Resource an interface? Because I'd have to re-implement retain() and release(). I am avoiding this in virtue of not writing the same code over and over (remember that there are multiple classes that need this memory-management system). Why not composition? Because I'd still have to implement methods in Sprite (and similar classes) that essentially call the methods of Resource. I'd still be writing the same code over and over! What is your advice in this situation, then?

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  • Any ideas on reducing lag in terrain generation?

    - by l5p4ngl312
    Ok so here's the deal. I've written an isometric engine that generates terrain based on camera values using 2D perlin noise. I planned on doing 3D but first I need to work out the lag issues I'm having. I will try to explain how I am doing this so that maybe someone can spot where I am going wrong. I know it should not be this laggy. There is the abstract class Block which right now just contains render(). BlockGrass, etc. extend this class and each has code in the render function to create a textured quad at the given position. Then there is the class Chunk which has the function Generate() and setBlocksInArea(). Generate uses 2D perlin noise to make a height map and stores the heights in a 2D array. It stores the positions of each block it generates in blockarray[x][y][z]. The chunks are 8x8x128. In the main game class there is a 3D array called blocksInArea. The blocks in this array are what gets rendered. When a chunk generates, it adds its blocks to this array at the correct index. It is like this so chunks can be saved to the hard drive (even though they aren't yet) but there can still be optimization with the rendering that you wouldn't have if you rendered each chunk separately. Here's where the laggy part comes in: When the camera moves to a new chunk, a row of chunks generates on the end of the axis that the camera moved on. But it still has to move the other chunks up/down in the blocksInArea (render) array. It does this by calculating the new position in the array and doing the Chunk.setBlocksInArea(): for(int x = 0; x < 8; x++){ for(int y = 0; y < 8; y++){ nx = x+(coordX - camCoordX)*8 ny = y+(coordY - camCoordY)*8 for(int z = 0; z < height[x][y]; z++){ blockarray[x][y][z] = Game.blocksInArea[nx][ny][z]; } } } My reasoning was that this would be much faster than doing the perlin noise all over again, but there are still little spikes of lag when you move in between chunks. Edit: Would it be possible to create a 3 dimensional array list so that shifting of chunks within the array would not be neccessary?

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  • How to keep a data structure synchronized over a network?

    - by David Gouveia
    Context In the game I'm working on (a sort of a point and click graphic adventure), pretty much everything that happens in the game world is controlled by an action manager that is structured a bit like: So for instance if the result of examining an object should make the character say hello, walk a bit and then sit down, I simply spawn the following code: var actionGroup = actionManager.CreateGroup(); actionGroup.Add(new TalkAction("Guybrush", "Hello there!"); actionGroup.Add(new WalkAction("Guybrush", new Vector2(300, 300)); actionGroup.Add(new SetAnimationAction("Guybrush", "Sit")); This creates a new action group (an entire line in the image above) and adds it to the manager. All of the groups are executed in parallel, but actions within each group are chained together so that the second one only starts after the first one finishes. When the last action in a group finishes, the group is destroyed. Problem Now I need to replicate this information across a network, so that in a multiplayer session, all players see the same thing. Serializing the individual actions is not the problem. But I'm an absolute beginner when it comes to networking and I have a few questions. I think for the sake of simplicity in this discussion we can abstract the action manager component to being simply: var actionManager = new List<List<string>>(); How should I proceed to keep the contents of the above data structure syncronized between all players? Besides the core question, I'm also having a few other concerns related to it (i.e. all possible implications of the same problem above): If I use a server/client architecture (with one of the players acting as both a server and a client), and one of the clients has spawned a group of actions, should he add them directly to the manager, or only send a request to the server, which in turn will order every client to add that group? What about packet losses and the like? The game is deterministic, but I'm thinking that any discrepancy in the sequence of actions executed in a client could lead to inconsistent states of the world. How do I safeguard against that sort of problem? What if I add too many actions at once, won't that cause problems for the connection? Any way to alleviate that?

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  • Identifying which pattern fits better.

    - by Daniel Grillo
    I'm developing a software to program a device. I have some commands like Reset, Read_Version, Read_memory, Write_memory, Erase_memory. Reset and Read_Version are fixed. They don't need parameters. Read_memory and Erase_memory need the same parameters that are Length and Address. Write_memory needs Lenght, Address and Data. For each command, I have the same steps in sequence, that are something like this sendCommand, waitForResponse, treatResponse. I'm having difficulty to identify which pattern should I use. Factory, Template Method, Strategy or other pattern. Edit I'll try to explain better taking in count the given comments and answers. I've already done this software and now I'm trying to refactoring it. I'm trying to use patterns, even if it is not necessary because I'm taking advantage of this little software to learn about some patterns. Despite I think that one (or more) pattern fits here and it could improve my code. When I want to read version of the software of my device, I don't have to assembly the command with parameters. It is fixed. So I have to send it. After wait for response. If there is a response, treat (or parse) it and returns. To read a portion of the memory (maximum of 256 bytes), I have to assembly the command using the parameters Len and Address. So I have to send it. After wait for response. If there is a response, treat (or parse) it and returns. To write a portion in the memory (maximum of 256 bytes), I have to assembly the command using the parameters Len, Address and Data. So I have to send it. After wait for response. If there is a response, treat (or parse) it and returns. I think that I could use Template Method because I have almost the same algorithm for all. But the problem is some commands are fixes, others have 2 or 3 parameters. I think that parameters should be passed on the constructor of the class. But each class will have a constructor overriding the abstract class constructor. Is this a problem for the template method? Should I use other pattern?

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  • Feedback from SQLBits 8

    - by Peter Larsson
    This years SQLBits occurred in Brighton. Although I didn’t have the opportunity to attend the full conference, I did a presentation at Saturday. Getting to Brighton was easy. Drove to Copenhagen airport at 0415, flew 0605 and arrived at Gatwick 0735. Then I took the direct train to Brighton and showed up at 0830, just one hour before presenting. This was the easy part. Getting home was much worse. Presentation ended at 1030 and I had to rush to the train station to get back to London, change to tube for Heathrow. Made it at the gate just 15 seconds before closing. That included a half mile run in the airport… Anyway, yesterday I got the feedback for my presentation. It does look good, especially since English is not my first language. This is the first graph Seems to be just halfway between conference average and best session. I can live with that. Second graph shows more detail about attendees voting. It also look acceptable. A wider spread for the 9’s, but it is an inevitable effect from how attendees percept the session. I did get a lot of 8’s and the lower grades in an descending order. The two people voting 4 and 5 didn’t say why they voted this so I don’t know how to remedy this. Third graph is about each category of votes.   Again, I find this acceptable. The Session abstract and Speaker’s knowledge seems to follow attendees expectations compared to conference average. I seem to have met the attendees expectations (and some more) for the other four categories, also compared to conference average. Since this did encourage me, I believe I will present some more at future meetings. I do have a new presentation about something all developers are doing every day but they may not know it. I will also cover this new topic in the next Deep Dives II book. Stay tuned! //Peter

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  • The Internet Key Wave MW833UP is not recognized in Ubuntu

    - by gio900
    I can't use my Onda MW833UP... :( Any advice? Here is something that someone else may understand: ~$: lsb_release -a No LSB modules are available. Distributor ID: Ubuntu Description: Ubuntu 11.10 Release: 11.10 Codename: oneiric ~$: lsusb Bus 001 Device 005: ID 1ee8:0012 ~$: dmesg [ 22.709475] cdc_acm 1-1:1.0: ttyACM0: USB ACM device [ 22.714856] usbcore: registered new interface driver cdc_acm [ 22.714866] cdc_acm: USB Abstract Control Model driver for USB modems and ISDN adapters [ 23.520490] ieee80211 phy0: wl_ops_bss_info_changed: arp filtering: enabled true, count 1 (implement) [ 24.244530] usbcore: registered new interface driver usbserial [ 24.244575] USB Serial support registered for generic [ 24.244673] usbcore: registered new interface driver usbserial_generic [ 24.244681] usbserial: USB Serial Driver core [ 24.265879] USB Serial support registered for GSM modem (1-port) [ 24.285680] usbcore: registered new interface driver option [ 24.285691] option: v0.7.2:USB Driver for GSM modems [ 24.425878] EXT4-fs (sda9): re-mounted. Opts: errors=remount-ro,commit=600 [ 24.736540] EXT4-fs (sda8): re-mounted. Opts: commit=600 [ 35.705796] Easy slow down manager: checking for SABI support. [ 35.706002] Easy slow down manager: SABI is supported (f5189) [ 36.060099] usbcore: deregistering interface driver uvcvideo [ 139.508061] CE: hpet increased min_delta_ns to 20113 nsec [ 6798.378917] usb 1-1: USB disconnect, device number 5 [ 6809.108232] usb 1-1: new high speed USB device number 6 using ehci_hcd [ 6809.242692] scsi5 : usb-storage 1-1:1.0 [ 6810.241257] scsi 5:0:0:0: CD-ROM Onda Datacard CD-ROM 0001 PQ: 0 ANSI: 0 [ 6810.241841] scsi 5:0:0:1: Direct-Access Onda Storage 0001 PQ: 0 ANSI: 0 [ 6810.271410] sr0: scsi3-mmc drive: 0x/0x caddy [ 6810.272099] sr 5:0:0:0: Attached scsi CD-ROM sr0 [ 6810.272852] sr 5:0:0:0: Attached scsi generic sg1 type 5 [ 6810.279954] sd 5:0:0:1: [sdb] Attached SCSI removable disk [ 6810.281210] sd 5:0:0:1: Attached scsi generic sg2 type 0 [ 6810.380591] sr0: CDROM (ioctl) error, command: Xpwrite, Read disk info 51 00 00 00 00 00 00 00 02 00 [ 6810.380617] sr: Sense Key : Hardware Error [current] [ 6810.380625] sr: Add. Sense: No additional sense information [ 6810.613937] sr0: CDROM (ioctl) error, command: Xpwrite, Read disk info 51 00 00 00 00 00 00 00 02 00 [ 6810.613972] sr: Sense Key : Hardware Error [current] [ 6810.613984] sr: Add. Sense: No additional sense information [ 6810.673716] usb 1-1: USB disconnect, device number 6 [ 6815.572142] usb 1-1: new high speed USB device number 7 using ehci_hcd [ 6815.706828] cdc_acm 1-1:1.0: ttyACM0: USB ACM device The last 3 lines are where I inserted the Internet key, then reconnected it. usb-device T: Bus=01 Lev=01 Prnt=01 Port=00 Cnt=01 Dev#= 7 Spd=480 MxCh= 0 D: Ver= 2.00 Cls=ef(misc ) Sub=02 Prot=01 MxPS=64 #Cfgs= 1 P: Vendor=1ee8 ProdID=0012 Rev=00.01 S: Manufacturer=Onda S: Product=MW833UP S: SerialNumber=9230B35D870F9CB7AE684EACC5C12BE5EC33B26E C: #Ifs= 2 Cfg#= 1 Atr=a0 MxPwr=500mA I: If#= 0 Alt= 0 #EPs= 1 Cls=02(commc) Sub=02 Prot=01 Driver=cdc_acm I: If#= 1 Alt= 0 #EPs= 2 Cls=0a(data ) Sub=00 Prot=00 Driver=cdc_acm Then there is /dev/ttyACM0. When the key is connected to the USB port, everything that will meant...

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  • SQL Saturday 194 - Exeter

    - by Dave Ballantyne
    Many kudos goes to Jonathan and Annette Allen and the others on the team for confirming SQL Saturday 194 in Exeter on the 8th and 9th of March.  The event home page is here http://www.sqlsaturday.com/194/eventhome.aspx and I delighted that myself and Dave Morrison will be presenting a full day pre-con on the 8th on favourite subjects “TSQL and Internals”. Here is the full abstract : TSQL and internals - When faced with performance issues there are many lines of attack. Tuning the engine itself can get you so far, however for maximum effect you need to understand how the engine and how it translates SQL statements into performable actions. This is not a simple task, it is a massive task to deal with a multi-table join and the number of permutations can be immense. To back up this knowledge, we can create better performing TSQL and understand the impact that is has upon the engine and recognize the pitfalls and gotcha’s that exist in SQLServer. Ultimately, there is no ‘best way’ to perform a single task only many variations of ‘it depends’ , but now we can pick the most appropriate option for the required dataload. Over the years, there have been many myths and misconceptions have grown around the product, some have basis in older versions and some are just wrong. Continuing to build on the knowledge given so far these issue will be explored and broken down and proved or disproved. Finally we will look to the future and explore SQL Server 2012 and the new functionality that that brings and some of the common uses that we will be able to address. After completion of this days pre-con, attendees will have a more complete knowledge of execution plans, and how they relate to the physical and logical actions that SQLServer will be executing on their behalf. The attendees will also have a more rounded and fuller knowledge of TSQL and the implications of incorrectly defining a query. Dave is a fountain of knowledge on execution plans and optimizer internals and ,though i may flatter myself, I’m no shrinking violet when it comes to TSQL and such matters.  I hope that if you cant join us, then there are other pre-cons available from other experts in their fields that may ‘float you boat’ too.  The pre-con page is http://sqlsouthwest.co.uk/SQLSaturday_precon.htm Also, excitingly, this pre-con day is sponsored by Fusion-IO which is a great boon for the day. If you want a more of this then i am offering a 2 day TSQL course starting on the 19th of March. More details on this are available here

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  • RTS Game Style Application [closed]

    - by Daniel Wynand van Wyk
    My question may seem somewhat odd, but I hope that my specifications will clarify EXACTLY what it is that I am after. I need some help choosing the right tooling for a particular endeavour. My background is in desktop application development and large back-end systems. I have worked primarily on the Microsoft stack using C# and the .Net framework. My goal is to develop a 2D, RTS style, interactive office simulation. The simulation will model various office spaces, office equipment, employees and their interactions with one another. The idea is to abstract the concept of an office completely. Under the hood the application will do many things that are nothing like a game. This includes P2P networking, VPN tunnelling, streaming video, instant messaging, document collaboration, remote screen sharing, file-sharing, virus scanning, VOIP, document scanning, faxing, emailing, distributed computing, content management and much more! A somewhat similar thing has been attempted by IBM, where they created a virtual office in second life. If their attempt was a game, the game-play would be notably horrible, to say the least! The users/players will drive and control my application through the various objects modelled in the simulation. A single application capable of performing all of these various tasks would be a nightmare to navigate for even the most expert user. Using the concept of a game, I can easily separate functionality by assigning them to objects that relate 1-1 with their real world counter-parts. This can greatly simplify computing for novice users, with many added benefits in terms of visibility, transparency of process and centralized configuration. My hope is to make complex computing tasks accessible to all kinds of users and to greatly reduce the cognitive load associated with using the many different utilities and applications inside office settings. The complexity is therefore limited to the complexity of the space in which you find yourself. I want the application to target as many platforms as possible and run on computers that have no accelerated graphics capabilities. The simulation won't contain any of the fancy eye-candy you find in modern games, to the contrary, my "game" will purposefully be clean and simple. The closest thing I could imagine would be an old game like "Theme Hospital" or the first instalment of "The Sims". All the content will be pre-created and not user-generated like Second Life. New functionality will be added via a plugin system. Given my background and nature of my "game", I would like to spend most of my time writing code that does not have to do with the simulated office, as the "game" is really just a glorified application menu. I have done much reading about existing engines, frameworks and tools. I need the help of an experienced game developer who has tried and tested various products over the years who can guide me in the right direction given my very particular needs. I would appreciate any help I can get!

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  • Managing accounts on a private website for a real-life community

    - by Smudge
    I'm looking at setting-up a walled-in website for a real-life community of people, and I was wondering if anyone has any experience with managing member accounts for this kind of thing. Some conditions that must be met: This community has a set list of real-life members, each of whom would be eligible for one account on the website. We don't expect or require that they all sign-up. It is purely opt-in, but we anticipate that many of them would be interested in the services we are setting up. Some of the community members emails are known, but some of them have fallen off the grid over the years, so ideally there would be a way for them to get back in touch with us through the public-facing side of the site. (And we'd want to manually verify the identity of anyone who does so). Their names are known, and for similar projects in the past we have assigned usernames derived from their real-life names. This time, however, we are open to other approaches, such as letting them specify their own username or getting rid of usernames entirely. The specific web technology we will use (e.g. Drupal, Joomla, etc) is not really our concern right now -- I am more interested in how this can be approached in the abstract. Our database already includes the full member roster, so we can email many of them generated links to a page where they can create an account. (And internally we can require that these accounts be paired with a known member). Should we have them specify their own usernames, or are we fine letting them use their registered email address to log-in? Are there any paradigms for walled-in community portals that help address security issues if, for example, one of their email accounts is compromised? We don't anticipate attempted break-ins being much of a threat, because nothing about this community is high-profile, but we do want to address security concerns. In addition, we want to make the sign-up process as painless for the members as possible, especially given the fact that we can't just make sign-ups open to anyone. I'm interested to hear your thoughts and suggestions! Thanks!

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  • Defining a service layer: the text-based adventure

    - by Stacy Vicknair
    Applications these days have more options than ever for a user interface, and it’s only going to grow. A successful product might require native applications for mobile devices, a regular web implementation, or even a gaming console. These systems often will be centralized and data driven. The solution is one that’s fairly solitary, a service layer! Simply put, take what’s shared and put it behind a physical or abstract layer that defines the boundary between the specific user interface and the shared content.   I know, I know, none of this is complicated. But some times it can be difficult to discern what belongs on which side of the line. For instance, say we’re creating a service that will provide content for both an ASP.NET MVC application and a WP7 application. Although the content served to each application is the same, there are different paradigms and patterns for displaying that data in the different environments. In ASP.NET MVC, you may create a model specific to a page that combines necessary information. In the WP7 application you might require different sets of data that you will connect via MVVM with the view. The general rule of thumb is that any shared content, business rules, or data should exist separately. Any element that is specific to the current UI implementation should be included in a separate library or with the UI implementation itself. The WP7 application doesn’t need my MVC specific model classes. My MVC application doesn’t require those INotifyPropertyChanged viewmodels that the WP7 application depends on. In both cases, there should be additional processing done above the service layer to massage the data to the application’s specific needs.   Service-ocalypse: the text based adventure What helps me the most about deciding whether or not something belongs coupled to the UI implementation or in the shared implementation is thinking of the simplest implementation you could have: a console application. You might have played a game like Peasant’s Quest: The console app is the text based adventure game version of your application. If you’re service was consumed in its simplest form, you would simply have a console based API for it that issues requests. Maybe those requests aren’t SWIM TO BOAT, but they might be CREATE USER JOHN. If I issue a request, I expect that request to be issued to the service. If the service has any exceptions or issues with my input, that business logic should be encapsulated in that service, not implemented in the UI. The service layer should be your functional application in its entirety, and anything above that layer should only assist with the display of that information.

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  • How can I cleanly and elegantly handle data and dependancies between classes

    - by Neophyte
    I'm working on 2d topdown game in SFML 2, and need to find an elegant way in which everything will work and fit together. Allow me to explain. I have a number of classes that inherit from an abstract base that provides a draw method and an update method to all the classes. In the game loop, I call update and then draw on each class, I imagine this is a pretty common approach. I have classes for tiles, collisions, the player and a resource manager that contains all the tiles/images/textures. Due to the way input works in SFML I decided to have each class handle input (if required) in its update call. Up until now I have been passing in dependencies as needed, for example, in the player class when a movement key is pressed, I call a method on the collision class to check if the position the player wants to move to will be a collision, and only move the player if there is no collision. This works fine for the most part, but I believe it can be done better, I'm just not sure how. I now have more complex things I need to implement, eg: a player is able to walk up to an object on the ground, press a key to pick it up/loot it and it will then show up in inventory. This means that a few things need to happen: Check if the player is in range of a lootable item on keypress, else do not proceed. Find the item. Update the sprite texture on the item from its default texture to a "looted" texture. Update the collision for the item: it might have changed shape or been removed completely. Inventory needs to be updated with the added item. How do I make everything communicate? With my current system I will end up with my classes going out of scope, and method calls to each other all over the place. I could tie up all the classes in one big manager and give each one a reference to the parent manager class, but this seems only slightly better. Any help/advice would be greatly appreciated! If anything is unclear, I'm happy to expand on things.

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  • StringBuffer behavior in LWJGL

    - by Michael Oberlin
    Okay, I've been programming in Java for about ten years, but am entirely new to LWJGL. I have a specific problem whilst attempting to create a text console. I have built a class meant to abstract input polling to it, which (in theory) captures key presses from the Keyboard object and appends them to a StringBuilder/StringBuffer, then retrieves the completed string after receiving the ENTER key. The problem is, after I trigger the String return (currently with ESCAPE), and attempt to print it to System.out, I consistently get a blank line. I can get an appropriate string length, and I can even sample a single character out of it and get complete accuracy, but it never prints the actual string. I could swear that LWJGL slipped some kind of thread-safety trick in while I wasn't looking. Here's my code: static volatile StringBuffer command = new StringBuffer(); @Override public void chain(InputPoller poller) { this.chain = poller; } @Override public synchronized void poll() { //basic testing for modifier keys, to be used later on boolean shift = false, alt = false, control = false, superkey = false; if(Keyboard.isKeyDown(Keyboard.KEY_LSHIFT) || Keyboard.isKeyDown(Keyboard.KEY_RSHIFT)) shift = true; if(Keyboard.isKeyDown(Keyboard.KEY_LMENU) || Keyboard.isKeyDown(Keyboard.KEY_RMENU)) alt = true; if(Keyboard.isKeyDown(Keyboard.KEY_LCONTROL) || Keyboard.isKeyDown(Keyboard.KEY_RCONTROL)) control = true; if(Keyboard.isKeyDown(Keyboard.KEY_LMETA) || Keyboard.isKeyDown(Keyboard.KEY_RMETA)) superkey = true; while(Keyboard.next()) if(Keyboard.getEventKeyState()) { command.append(Keyboard.getEventCharacter()); } if (Framework.isConsoleEnabled() && Keyboard.isKeyDown(Keyboard.KEY_ESCAPE)) { System.out.println("Escape down"); System.out.println(command.length() + " characters polled"); //works System.out.println(command.toString().length()); //works System.out.println(command.toString().charAt(4)); //works System.out.println(command.toString().toCharArray()); //blank line! System.out.println(command.toString()); //blank line! Framework.disableConsole(); } //TODO: Add command construction and console management after that } } Maybe the answer's obvious and I'm just feeling tired, but I need to walk away from this for a while. If anyone sees the issue, please let me know. This machine is running the latest release of Java 7 on Ubuntu 12.04, Mate desktop environment. Many thanks.

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  • Understanding the levels of computing

    - by RParadox
    Sorry, for my confused question. I'm looking for some pointers. Up to now I have been working mostly with Java and Python on the application layer and I have only a vague understanding of operating systems and hardware. I want to understand much more about the lower levels of computing, but it gets really overwhelming somehow. At university I took a class about microprogramming, i.e. how processors get hard-wired to implement the ASM codes. Up to now I always thought I wouldn't get more done if learned more about the "low level". One question I have is: how is it even possible that hardware gets hidden almost completely from the developer? Is it accurate to say that the operating system is a software layer for the hardware? One small example: in programming I have never come across the need to understand what L2 or L3 Cache is. For the typical business application environment one almost never needs to understand assembler and the lower levels of computing, because nowadays there is a technology stack for almost anything. I guess the whole point of these lower levels is to provide an interface to higher levels. On the other hand I wonder how much influence the lower levels can have, for example this whole graphics computing thing. So, on the other hand, there is this theoretical computer science branch, which works on abstract computing models. However, I also rarely encountered situations, where I found it helpful thinking in the categories of complexity models, proof verification, etc. I sort of know, that there is a complexity class called NP, and that they are kind of impossible to solve for a big number of N. What I'm missing is a reference for a framework to think about these things. It seems to me, that there all kinds of different camps, who rarely interact. The last few weeks I have been reading about security issues. Here somehow, much of the different layers come together. Attacks and exploits almost always occur on the lower level, so in this case it is necessary to learn about the details of the OSI layers, the inner workings of an OS, etc.

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  • Should i continue my self-taught coding practice or learn how to do coding professionally?

    - by G1i1ch
    Lately I've been getting professional work, hanging out with other programmers, and making friends in the industry. The only thing is I'm 100% self-taught. It's caused my style to extremely deviate from the style of those that are properly trained. It's the techniques and organization of my code that's different. It's a mixture of several things I do. I tend to blend several programming paradigms together. Like Functional and OO. I lean to the Functional side more than OO, but I see the use of OO when something would make more sense as an abstract entity. Like a game object. Next I also go the simple route when doing something. When in contrast, it seems like sometimes the code I see from professional programmers is complicated for the sake of it! I use lots of closures. And lastly, I'm not the best commenter. I find it easier just to read through my code than reading the comment. And most cases I just end up reading the code even if there are comments. Plus I've been told that, because of how simply I write my code, it's very easy to read it. I hear professionally trained programmers go on and on about things like unit tests. Something I've never used before so I haven't even the faintest idea of what they are or how they work. Lots and lots of underscores "_", which aren't really my taste. Most of the techniques I use are straight from me, or a few books I've read. Don't know anything about MVC, I've heard a lot about it though with things like backbone.js. I think it's a way to organize an application. It just confuses me though because by now I've made my own organizational structures. It's a bit of a pain. I can't use template applications at all when learning something new like with Ubuntu's Quickly. I have trouble understanding code that I can tell is from someone trained. Complete OO programming really leaves a bad taste in my mouth, yet that seems to be what EVERYONE else is strictly using. It's left me not that confident in the look of my code, or wondering whether I'll cause sparks when joining a company or maybe contributing to open source projects. In fact I'm rather scared of the fact that people will eventually be checking out my code. Is this just something normal any programmer goes through or should I really look to change up my techniques?

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  • Is it reasonable to insist on reproducing every defect before diagnosing and fixing it?

    - by amphibient
    I work for a software product company. We have large enterprise customers who implement our product and we provide support to them. For example, if there is a defect, we provide patches, etc. In other words, It is a fairly typical setup. Recently, a ticket was issued and assigned to me regarding an exception that a customer found in a log file and that has to do with concurrent database access in a clustered implementation of our product. So the specific configuration of this customer may well be critical in the occurrence of this bug. All we got from the customer was their log file. The approach I proposed to my team was to attempt to reproduce the bug in a similar configuration setup as that of the customer and get a comparable log. However, they disagree with my approach saying that I should not need to reproduce the bug (as that is overly time-consuming and will require simulating a server cluster on VMs) and that I should simply "follow the code" to see where the thread- and/or transaction-unsafe code is and put the change working off of a simple local development, which is not a cluster implementation like the environment from which the occurrence of the bug originates. To me, working out of an abstract blueprint (program code) rather than a concrete, tangible, visible manifestation (runtime reproduction) seems like a difficult working environment (for a person of normal cognitive abilities and attention span), so I wanted to ask a general question: Is it reasonable to insist on reproducing every defect and debug it before diagnosing and fixing it? Or: If I am a senior developer, should I be able to read (multithreaded) code and create a mental picture of what it does in all use case scenarios rather than require to run the application, test different use case scenarios hands on, and step through the code line by line? Or am I a poor developer for demanding that kind of work environment? Is debugging for sissies? In my opinion, any fix submitted in response to an incident ticket should be tested in an environment simulated to be as close to the original environment as possible. How else can you know that it will really remedy the issue? It is like releasing a new model of a vehicle without crash testing it with a dummy to demonstrate that the air bags indeed work. Last but not least, if you agree with me: How should I talk with my team to convince them that my approach is reasonable, conservative and more bulletproof?

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  • Redesigning an Information System - Part 1

    - by dbradley
    Through the next few weeks or months I'd like to run a small series of articles sharing my experiences from the largest of the project I've worked on and explore some of the real-world problems I've come across and how we went about solving them. I'm afraid I can't give too many specifics on the project right now as it's not yet complete so you'll have to forgive me for being a little abstract in places! To start with I'm going to run through a little of the background of the problem and the motivations to re-design from scratch. Then I'll work through the approaches taken to understanding the requirements, designing, implementing, testing and migrating to the new system. Motivations for Re-designing a Large Information System The system is one that's been in place for a number of years and was originally designed to do a significantly different one to what it's now being used for. This is mainly due to the product maturing as well as client requirements changing. As with most information systems this one can be defined in four main areas of functionality: Input – adding information to the system Storage – persisting information in an efficient, searchable structure Output – delivering the information to the client Control – management of the process There can be a variety of reasons to re-design an existing system; a few of our own turned out to be factors such as: Overall system reliability System response time Failure isolation and recovery Maintainability of code and information General extensibility to solve future problem Separation of business and product concerns New or improved features The factor that started the thought process was the desire to improve the way in which information was entered into the system. However, this alone was not the entire reason for deciding to redesign. Business Drivers Typically all software engineers would always prefer to do a project from scratch themselves. It generally means you don't have to deal with problems created by predecessors and you can create your own absolutely perfect solution. However, the reality of working within a business is that the bottom line comes down to return on investment. For a medium sized business such as mine there must be actual value able to be delivered within a reasonable timeframe for any work to be started. As a result, any long term project will generally take a lot of effort and consideration to be approved by those in charge and therefore it might be better to break down the project into more manageable chunks which allow more frequent deliverables and also value within a shorter timeframe. As the only thing of concern was the methods for inputting information, this is where we started with requirements gathering and design. However knowing that there might be more to the problem and not limiting your design decisions before the requirements is key to finding the best solutions.

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  • Configuration management in support of scientific computing

    - by Sharpie
    For the past few years I have been involved with developing and maintaining a system for forecasting near-shore waves. Our team has just received a significant grant for further development and as a result we are taking the opportunity to refactor many components of the old system. We will also be receiving a new server to run the model and so I am taking this opportunity to consider how we set up the system. Basically, the steps that need to happen are: Some standard packages and libraries such as compilers and databases need to be downloaded and installed. Some custom scientific models need to be downloaded and compiled from source as they are not commonly provided as packages. New users need to be created to manage the databases and run the models. A suite of scripts that manage model-database interaction needs to be checked out from source code control and installed. Crontabs need to be set up to run the scripts at regular intervals in order to generate forecasts. I have been pondering applying tools such as Puppet, Capistrano or Fabric to automate the above steps. It seems perfectly possible to implement most of the above functionality except there are a couple usage cases that I am wondering about: During my preliminary research, I have found few examples and little discussion on how to use these systems to abstract and automate the process of building custom components from source. We may have to deploy on machines that are isolated from the Internet- i.e. all configuration and set up files will have to come in on a USB key that can be inserted into a terminal that can connect to the server that will run the models. I see this as an opportunity to learn a new tool that will help me automate my workflow, but I am unsure which tool I should start with. If any member of the community could suggest a tool that would support the above workflow and the issues specific to scientific computing, I would be very grateful. Our production server will be running Linux, but support for OS X would be a bonus as it would allow the development team to setup test installations outside of VirtualBox.

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  • Configuration management in support of scientific computing

    - by Sharpie
    For the past few years I have been involved with developing and maintaining a system for forecasting near-shore waves. Our team has just received a significant grant for further development and as a result we are taking the opportunity to refactor many components of the old system. We will also be receiving a new server to run the model and so I am taking this opportunity to consider how we set up the system. Basically, the steps that need to happen are: Some standard packages and libraries such as compilers and databases need to be downloaded and installed. Some custom scientific models need to be downloaded and compiled from source as they are not commonly provided as packages. New users need to be created to manage the databases and run the models. A suite of scripts that manage model-database interaction needs to be checked out from source code control and installed. Crontabs need to be set up to run the scripts at regular intervals in order to generate forecasts. I have been pondering applying tools such as Puppet, Capistrano or Fabric to automate the above steps. It seems perfectly possible to implement most of the above functionality except there are a couple usage cases that I am wondering about: During my preliminary research, I have found few examples and little discussion on how to use these systems to abstract and automate the process of building custom components from source. We may have to deploy on machines that are isolated from the Internet- i.e. all configuration and set up files will have to come in on a USB key that can be inserted into a terminal that can connect to the server that will run the models. I see this as an opportunity to learn a new tool that will help me automate my workflow, but I am unsure which tool I should start with. If any member of the community could suggest a tool that would support the above workflow and the issues specific to scientific computing, I would be very grateful. Our production server will be running Linux, but support for OS X would be a bonus as it would allow the development team to setup test installations outside of VirtualBox.

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  • sorry, the maximum allowed clients from your host (10) are already connected" FTP error

    - by Sejanus
    Hello, I keep getting the "sorry, the maximum allowed clients from your host (10) are already connected" error whenever I try to transfer a large number of files. At first I thought it's a filezilla bug, however I get the same error basically with every FTP client I've tried, including Total Commander under Wine. I do not get that error using Windows. I did try to limit maximum allowed connections for Filezilla, both in server settings and in global settings, it didnt change anything. I did try to switch between passive and active modes (not sure if it's related at all, just last desperate attempt), and it didnt change anything either. When I try to use native ftp client (not sure how is it called, the one in Places - Connect to a server) I get abstract "connection refused" error every time I transfer large number of files. Connection is refused for separate particular files, if I click "Ignore" each time the rest of files are transfered perfectly well, so I assume it's the very same error. Anything I could do? This really drives me mad, transfering large numbers of files is a part of my everyday job... P.S. and this happens with many different FTP servers. Also I dont get this error in Windows. So I assume it's not a server problem. P.P.S. I am aware of similar question here, the answer provided just didn't solve it to me.

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  • supervisord launches with wrong setuid

    - by friendzis
    I am trying to test a pilot system with nginx connecting to uwsgi served application controlled by supervisord running on ubuntu-server. Application is written in python with Flask in virtualenv, although I'm not sure if that is relevant. To test the system I have created a simple hello world with flask. I want nginx and uwsgi both to run as www-data user. If I launch uwsgi "manually" from root shell I can see uwsgi processes runing as appropriate user (www-data). Although, if I let supervisor launch the application something strange happens - uwsgi processes are runing under my user (friendzis). Consequently, socket file gets created under wrong user and nginx cannot communicate with my applicaion. note: the linux server runs as Hyper-V VM, under Windows Server 2008. Relevant configuration: [uwsgi] socket = /var/www/sockets/cowsay.sock chmod-socket = 666 abstract-socket = false master = true workers = 2 uid = www-data gid = www-data chdir = /var/www/cowsay/cowsay pp = /var/www/cowsay/cowsay pyhome = /var/www/cowsay module = cowsay callable = app supervisor [program:cowsay] command = /var/www/cowsay/bin/uwsgi -s /var/www/sockets/cowsay.sock -w cowsay:app directory = /var/www/cowsay/cowsay user = www-data autostart = true autorestart = true stdout_logfile = /var/www/cowsay/log/supervisor.log redirect_stderr = true stopsignal = QUIT I'm sure I'm missing some minor detail, but I'm unable to notice it. Would appreciate any suggestions.

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  • PHP-FPM issue on LEMP Stack and WordPress

    - by jw60660
    I'm very much a NGINX and Server Admin beginner. I used this tutorial to install NGINX / PHP / mySQL / WordPress: C3M Digital Tutorial In this tutorial the backend php-cgi setup is configured using fastcgi. php5-fpm was installed during this tutorial: apt-get install nginx-full php5-fpm php5 php5-mysql php5-apc php5-mysql php5-xsl php5-xmlrpc php5-sqlite php5-snmp php5-curl After reading that the NGINX configuration on the WordPress codec was more secure than most tutorials, I decided to use the codex configuration: WordPress NGINX configuration in Codex The Codex configuration uses php-fpm for backend php-cgi. When opening the browser I got a 502 Bad Gateway error. The error log was: "2012/06/10 21:18:27 [crit] 14009#0: *4 connect() to unix:/tmp/php-fpm.sock failed (2: No such file or directory) while connecting to upstream, client: 12.3.456.789, server: mywebsite.com, request: "GET / HTTP/1.1", upstream: "fastcgi://unix:/tmp/php-fpm.sock:", hos t: "mywebsite.com"" In the main NGINX configuration file supplied by the codex I noticed the line starting "server unix:" in the upstream php block which point to the empty directory: # Upstream to abstract backend connection(s) for PHP. upstream php { server unix:/tmp/php-fpm.sock; # server 127.0.0.1:9000; } I checked the folder at /tmp and it was empty. Seems I missed configuring php-fpm to play with NGINX. Can someone point me in the right direction? Much appreciated!

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  • Setting Up My Home Network

    - by Skizz
    I currently have five PCs at home, three running WinXP and two running Ubuntu. They are set up like this: ISP ----- Modem ---- Switch ---- Ubuntu1 -- B&W Printer | |--WinXP1 | |--WinXP2 Wireless |--Colour Printer | |---------Ubuntu2 |---------WinXP3 (laptop) The Ubuntu1 machine is set up as a PDC using Samba and runs fetchmail, procmail, dovecot to get my e-mail and allow me to access the e-mail via imap so I can read the e-mail on any PC. I'd like to set up the network like this: ISP ----- Modem ---- Ubuntu1 ---- Switch ------WinXP1 | | |--WinXP2 B&W Printer Wireless |--Colour Printer | |---------Ubuntu2 |---------WinXP3 (laptop) My questions are: How to configure Ubuntu1 to act as a firewall. How to configure Ubuntu1 to provide a consistant user authentication across the network, at the moment Samba provides roaming profiles for the XP machines but the Ubuntu2 machine has it's own user lists. I'd like to have a single authentication for both XP machines and linux machines so that users added to the server list will propagate to all PCs (i.e. new users can log on using any PC without modifying any of the client PCs). How to configure a linux client (Ubuntu2 above) to access files on the server (Ubuntu1), some of which are in user specific folders, effectively sharing /home/{user} per user (read and write access) and stuff like /home/media/photos with read access for everyone and limited write access. How to configure the XP machines (if it is different from a the Samba method). How to set up e-mail filtering. I'd like to have a whitelist/blacklist system for incoming e-mails for some of the e-mail accounts (mainly, my kids' accounts) with filtered e-mails being put into quaranteen until a sysadmin either adds the sender to a blacklist or whitelist. OK, that's a lot of stuff. For now, I don't want config files*, rather, what services / applications to use and how they interact. For example, LDAP could be used for authentication but what else would be useful to make the administration of the LDAP easier. Once I have a general idea for the overall configuration, I can ask other questions about the specifics. Skizz I have looked around for information, but most answers are usually in the form of abstract config files and lists of packages to install.

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  • Serve a specific set of error pages for different subdirectories

    - by navitronic
    I am currently trying to setup 2 different sets of Error documents for separate folders within a website. I have 2 folders within the root of a site: demo/ live/ Any requests that return 404's or 403's within the demo folder needs to load one set of pages for the Apache errordocuments, eg. ErrorDocument 404 /statuses/demo-404.html ErrorDocument 403 /statuses/demo-403.html And the live needs to go to similarly name files. ErrorDocument 404 /statuses/live-404.html ErrorDocument 403 /statuses/live-403.html So far I have tried placing an .htaccess file in both directories with the ErrorDocument directives setup pointing to the specific files, the 404 works fine and references the correct page. However, the 403s do not work and revert to the server default when trying to access forbidden folders within the demo directory, the logs indicate the following: [Wed Jun 16 04:47:44 2010] [crit] [client 115.64.131.144] (13)Permission denied: /home/abstract/public_html/demo/xxx/.htaccess pcfg_openfile: unable to check htaccess file, ensure it is readable Is this correct? Would apache revert to default because it is trying to look for the htaccess in a folder it doesn't have permission in? Why wouldn't it work it's way back through the folder tree? Can I make it do this?

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  • Restoring MBR, partition table, and boot sector of memory card without data loss ("USBC")

    - by Synetech
    Abstract I have a FAT32 memory card that when inserted into a computer causes Windows to prompt to format it. The card is definitely not supposed to be blank and has a bunch of files on it. Symptoms Using a hex-editor/disk-viewer, I examined the card and found that several sectors/clusters have been overwritten with something that has a signature of USBC at the start of the sector. Specifically, the master boot record (and partition table) is gone (hence Windows thinking the card is blank and needing to be formatted), as are the boot sectors (they have the USBC signature and a volume label of NO NAME and partition type of FAT32). Fortunately, it looks like both copies of the FAT are almost entirely intact (a few FAT entries at the start of a cluster here and there seem to be overwritten by USBC). The root directory is also nearly intact—I can see the volume label entry and subdirectory listings, but one sector is overwritten. (There are no more instances of USBC after the last one in the FAT2.) Hypothesis These observations seem to indicate some sort of virus that erases a few key filesystem structures, and then overwrites a few extra sectors here and there. Googling it seems to corroborate the idea of a virus, except that others report a file called USBC which does not apply here, and in fact, could not be possible since there is no filesystem to even see files. I cannot find any information about a virus with these symptoms, nor a removal tool. (I can't help but wonder if it is actually due to an autorun virus prevention tool.) Question I can likely fix the FAT corruption since they are mostly contiguous chains and maybe even the lost sector of the root directory, but does anyone know of a convenient way to restore or (re)create the MBR/partition table and boot sectors (without formatting or overwriting the data)?

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