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  • How to handle encryption key conflicts when synchronizing data?

    - by Rafael
    Assume that there is data that gets synchronized between several devices. The data is protected with a symmetric encryption algorithm and a key. The key is stored on each device and encrypted with a password. When a user changes the password only the key gets re-encrypted. Under normal circumstances, when there is a good network connection to other peers, the current key gets synchronized and all data on the new device gets encrypted with the same key. But how to handle situations where a new device doesn’t have a network connection and e.g. creates its own new, but incompatible key? How to keep the usability as high as possible under such circumstances? The application could detect that there is no network and hence refuse to start. That’s very bad usability in my opinion, because the application isn’t functional at all in this case. I don’t consider this a solution. The application could ignore the missing network connection and create a new key. But what to do when the application gains a network connection? There will be several incompatible keys and some parts of the underlying data could only be encrypted with one key and other parts with another key. The situation would get worse if there would be more keys than just two and the application would’ve to ask every time for a password when another object that should get decrypted with another key would be needed. It is very messy and time consuming to try to re-encrypt all data that is encrypted with another key with a main key. What should be the main key at all in this case? The oldest key? The key with the most encrypted objects? What if the key got synchronized but not all objects that got encrypted with this particular key? How should the user know for which particular password the application asks and why it takes probably very long to re-encrypt the data? It’s very hard to describe encryption “issues” to users. So far I didn’t find an acceptable solution, nor some kind of generic strategy. Do you have some hints about a concrete strategy or some books / papers that describe synchronization of symmetrically encrypted data with keys that could cause conflicts?

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  • Are there any concerns with using a static read-only unit of work so that it behaves like a cache?

    - by Rowan Freeman
    Related question: How do I cache data that rarely changes? I'm making an ASP.NET MVC4 application. On every request the security details about the user will need to be checked with the area/controller/action that they are accessing to see if they are allowed to view it. The security information is stored in the database. For example: User Permission UserPermission Action ActionPermission A "Permission" is a token that is applied to an MVC action to indicate that the token is required in order to access the action. Once a user is given the permission (via the UserPermission table) then they have the token and can therefore access the action. I've been looking in to how to cache this data (since it rarely changes) so that I'm only querying in-memory data and not hitting a database (which is a considerable performance hit at the moment). I've tried storing things in lists, using a caching provider but I either run in to problems or performance doesn't improve. One problem that I constantly run in to is that I'm using lazy loading and dynamic proxies with EntityFramework. This means that even if I ToList() everything and store them somewhere static, the relationships are never populated. For example, User.Permissions is an ICollection but it's always null. I don't want to Include() everything because I'm trying to keep things simple and generic (and easy to modify). One thing I know is that an EntityFramework DbContext is a unit of work that acts with 1st-level caching. That is, for the duration of the unit of work, everything that is accessed is cached in memory. I want to create a read-only DbContext that will exist indefinitely and will only be used to read about permission data. Upon testing this it worked perfectly; my page load times went from 200ms+ to 20ms. I can easily force the data to refresh at certain intervals or simply leave it to refresh when the application pool is recycled. Basically it will behave like a cache. Note that the rest of the application will interact with other contexts that exist per request as normal. Is there any disadvantage to this approach? Could I be doing something different?

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  • How to troubleshoot ethernet port on laptop

    - by Psallas Vassilios
    I have a problem with my wired connection. To be more specific, my laptop doesn't seems to recognize that I have plugged in an ethernet cable. I tried to download new drivers for my ethernet card, but I couldn't find any solutions. Maybe because I am new to Linux, so I'm not familiar with running commands in the terminal. OK I have typed the command and here are the results: 00:04.0 Ethernet controller [0200]: Silicon Integrated Systems [SiS] 191 Gigabit Ethernet Adapter [1039:0191] (rev 02) For the second reply I don't know if the following is what you asked me: ?Memory: 3.9 GiB ?Processor: Intel Core 2 Duo CPU P8800 @ 2.66GHz × 2 ?OS type: 32-bit My Ethernet connection had some problem on Windows too. I have changed recently my internet provider, and since then my ethernet cable is not recognized by the laptop. At that time I was still on Windows. I thought that with Ubuntu the problem would be solved, but unfortunately the problem still persists. If someone can help me to solve my problem I'll be thankful. Here are the results of the three first commands you told me to run: lsmod | grep sis190 sis190 22570 0 sudo modprobe sis190 ifconfig eth0 Link encap:Ethernet HWaddr 00:90:f5:90:81:7e UP BROADCAST MULTICAST MTU:1500 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:0 (0.0 B) TX bytes:0 (0.0 B) lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:185 errors:0 dropped:0 overruns:0 frame:0 TX packets:185 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:22672 (22.6 KB) TX bytes:22672 (22.6 KB) wlan0 Link encap:Ethernet HWaddr 00:25:d3:2c:3a:ae inet addr:192.168.1.72 Bcast:192.168.1.255 Mask:255.255.255.0 inet6 addr: fe80::225:d3ff:fe2c:3aae/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:260 errors:0 dropped:0 overruns:0 frame:0 TX packets:363 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:71992 (71.9 KB) TX bytes:52000 (52.0 KB) and the results of running the last two commands: dmesg | grep -e eth -e sis190 [ 0.816667] sis190: sis190 Gigabit Ethernet driver 1.4 loaded [ 0.816728] sis190 0000:00:04.0: setting latency timer to 64 [ 0.816751] sis190: 0000:00:04.0: Read MAC address from EEPROM [ 0.904032] sis190: 0000:00:04.0: Realtek PHY RTL8201 transceiver at address [ 1.416030] sis190: 0000:00:04.0: Using transceiver at address 1 as default [ 1.448235] sis190 0000:00:04.0: eth0: 0000:00:04.0: SiS 191 PCI Gigabit Ethernet adapter at f8410000 (IRQ: 19), 00:90:f5:90:81:7e [ 1.448238] sis190 0000:00:04.0: eth0: GMII mode. [ 1.448243] sis190 0000:00:04.0: eth0: Enabling Auto-negotiation [ 11.560907] IPv6: ADDRCONF(NETDEV_UP): eth0: link is not ready [ 16.372019] IPv6: ADDRCONF(NETDEV_UP): eth0: link is not ready [ 16.372265] IPv6: ADDRCONF(NETDEV_UP): eth0: link is not ready [ 26.424038] sis190 0000:00:04.0: eth0: auto-negotiating... nm-tool NetworkManager Tool State: connected (global) - Device: eth0 ----------------------------------------------------------------- Type: Wired Driver: sis190 State: unavailable Default: no HW Address: 00:90:F5:90:81:7E Capabilities: Carrier Detect: yes Wired Properties Carrier: off

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  • Am I deluding myself? Business analyst transition to programmer

    - by Ryan
    Current job: Working as the lead business analyst for a Big 4 firm, leading a team of developers and testers working on a large scale re-platforming project (4 onshore dev, 4 offshore devs, several onshore/offshore testers). Also work in a similar capacity on other smaller scale projects. Extent of my role: Gathering/writing out requirements, creating functional specifications, designing the UI (basically mapping out all front-end aspects of the system), working closely with devs to communicate/clarify requirements and come up with solutions when we hit roadblocks, writing test cases (and doing much of the testing), working with senior management and key stakeholders, managing beta testers, creating user guides and leading training sessions, providing key technical support. I also write quite a few macros in Excel using VBA (several of my macros are now used across the entire firm, so there are maybe around 1000 people using them) and use SQL on a daily basis, both on the SQL compact files the program relies on, our SQL Server data and any Access databases I create. The developers feel that I am quite good in this role because I understand a lot about programming, inherent system limitations, structure of the databases, etc so it's easier for me to communicate ideas and come up with suggestions when we face problems. What really interests me is developing software. I do a fair amount of programming in VBA and have been wanting to learn C# for awhile (the dev team uses C# - I review code occasionally for my own sake but have not had any practical experience using it). I'm interested in not just the business process but also the technical side of things, so the traditional BA role doesn't really whet my appetite for the kind of stuff I want to do. Right now I have a few small projects that managers have given me and I'm finding new ways to do them (like building custom Access applications), so there's a bit here and there to keep me interested. My question is this: what I would like to do is create custom Excel or Access applications for small businesses as a freelance business (working as a one-man shop; maybe having an occasional contractor depending on a project's complexity). This would obviously start out as a part-time venture while I have a day job, but eventually become a full-time job. Am I deluding myself to thinking I can go from BA/part-time VBA programmer to making a full-time go of a freelance business (where I would be starting out just writing custom Excel/Access apps in VBA)? Or is this type of thing not usually attempted until someone gains years of full-time programming experience? And is there even a market for these types of applications amongst small businesses (and maybe medium-sized) businesses?

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  • Got Samba, Got PyNeighbourhood but still no connection. What else do I need?

    - by Frank A
    I am sure I had already hit post before but then could only find it by backing through browser. Was it deleted? is the question too dumb, sorry that I do not know the right jargon just trying to get answers to my problem anyway have reworded stuff a bit This seems to be a number one requirement for lots of people and 2 months on from setting up my Ubuntu pc, I am still unable to get a lasting connection in either direction. Adding a windows pc to a network is so easy... just a few clicks and get on with using it all. Using all command approaches and modifying configuration files is hardly user friendly. Googling brings up thousands of solutions but mostly they are too techy or assume the user is fully aware of how to use Linux. I do realise that their must be a lot of flavours for connecting to networks. So far I have installed Samba and fiddled with its config file. The day I did all that it worked from XP to Ubuntu. When I came back two days later to transfer my data over it would not connect. Although the the share does show up in Windows (XP) My Network Places. Today I installed PyNeighbourhood and this shows the Ubuntu box and all of the shares I had created at some point on Ubuntu and it even shows this under the XP workgroup name. But instructions on setting the connection up seem to relate to an earlier version and nothing seems to work there either. (I unshared most of those test folders but they still show up her but that is another question. When I click on mount- I can only click on one on the Ubuntu machine, there is one with no name so I assume this to be my attempt to add one XP Shared drive using ipaddress, I get errors. (gksu:9767): Gtk-WARNING **: Unable to locate theme engine in module_path: "pixmap", (gksu:9767): Gtk-WARNING **: Unable to locate theme engine in module_path: "pixmap", (gksu:9767): Gtk-WARNING **: Unable to locate theme engine in module_path: "pixmap", (gksu:9767): Gtk-WARNING **: Unable to locate theme engine in module_path: "pixmap", mount error(6): No such device or address Refer to the mount.cifs(8) manual page (e.g. man mount.cifs) OK tried to find the manual referred to... only an old comment that manual would be produced for future versions. I saw in another thread that Winbind is needed as well or at least I assume as well? Totally lost again? Please help, what else needs to be installed to connect to win pcs on the network.

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  • Caching items in Orchard

    - by Bertrand Le Roy
    Orchard has its own caching API that while built on top of ASP.NET's caching feature adds a couple of interesting twists. In addition to its usual work, the Orchard cache API must transparently separate the cache entries by tenant but beyond that, it does offer a more modern API. Here's for example how I'm using the API in the new version of my Favicon module: _cacheManager.Get( "Vandelay.Favicon.Url", ctx => { ctx.Monitor(_signals.When("Vandelay.Favicon.Changed")); var faviconSettings = ...; return faviconSettings.FaviconUrl; }); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } There is no need for any code to test for the existence of the cache entry or to later fill that entry. Seriously, how many times have you written code like this: var faviconUrl = (string)cache["Vandelay.Favicon.Url"]; if (faviconUrl == null) { faviconUrl = ...; cache.Add("Vandelay.Favicon.Url", faviconUrl, ...); } Orchard's cache API takes that control flow and internalizes it into the API so that you never have to write it again. Notice how even casting the object from the cache is no longer necessary as the type can be inferred from the return type of the Lambda. The Lambda itself is of course only hit when the cache entry is not found. In addition to fetching the object we're looking for, it also sets up the dependencies to monitor. You can monitor anything that implements IVolatileToken. Here, we are monitoring a specific signal ("Vandelay.Favicon.Changed") that can be triggered by other parts of the application like so: _signals.Trigger("Vandelay.Favicon.Changed"); In other words, you don't explicitly expire the cache entry. Instead, something happens that triggers the expiration. Other implementations of IVolatileToken include absolute expiration or monitoring of the files under a virtual path, but you can also come up with your own.

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  • Suggestions for Summer Intern Application Assignments

    - by orangepips
    As part of our application process we want prospective college interns to complete an assignment on their own - either programming or analytical - to give us something tangible to evaluate such as code or a flowchart. I have two ideas for these assignments, one programming and one analytical, I am interested in gathering feedback about these. Programming Assignment Generate an a month's calendar for a given date. The first row should indicate the days of the week (e.g. Sunday - Saturday). Each subsequent row should contain a week's days. The date supplied should be highlighted (e.g. bolded). I am thinking we'll probably proscribe the output format even more strictly - probably down to what the HTML source should look like including CSS classes. Thinking is this forces answerers to actually do some work if they merely copy a solution from the internet. Analytical Assignment Diagram or describe in prose a system for managing a set of traffic lights for traffic at a four way intersection. Each direction (i.e. North, South, East and West) has two lanes (i.e. right and left). The left lane is turn only and has green arrow light to indicate right of way. The system is able to detect if lanes have cars in them and change the lights accordingly. I would expect a flow chart or some prose describing a finite state machine that deals with each contingency. This would hopefully provide some indication of the applicant's ability to reason through a logic problem of sorts and articulate an approach for solving. Areas Seeking Feedback Is it unreasonable to ask this of applicants? If not, is it better to request before or after a phone screen? Are these questions too hard or easy for a collegiate audience? Any suggestions for alternate questions? Do these seem like good tools for analyzing people who would part of a software development life cycle? Programming language suggestions - I'm thinking Java, Python and/or C# (we're actually a ColdFusion shop).

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  • Best Frameworks/libraries/engines for 2D multiplayer C# Webbased RPG

    - by Thirlan
    Title is a mouthful but important because I'm looking to meet a specific criteria and it's complex enough that I need a lot of help in finding what I'm looking for. I really want people's suggestions because I trust it a lot more than anything else, so I just need to clearly define what it is I want heh : P Game is a 2D RPG. Think of Secret of Mana. Game is online multiplayer, but not MMO sized. Game must be webbased! I'm looking to the future and want to hit as many platforms as possible. I'm leaning to Webgl because of this, but still looking around. Since the users are seeing the game through the webbrowser the front-end should be mainly responsible for drawing, taking input and some basic checking such as preliminary collision detection. This is important because it means the game engine is NOT on the client's machine. The server should be responsible for the game engine and all the calculations. This means the server is doing all the work and the client is mostly a dumb terminal. Server language is c# I'm looking for fast project execution so I want to use as many pre-existing tools as possible. This would make sense because I'm making a game here, not an engine. I'm not creating some new revolutionary graphics or pushing the physics engines to the next level. Preference for commercially supported tools. For game mechanics reasons and for reasons 4 and 5, don't think I can use existing 2D rpg engines. I've seen them out there and I fear that if I try and use them they will have too many restrictions, but will be happy to hear out suggestions. So all this means I need a game engine on the server, or maybe just a physics engine, and then I need another engine/library to draw everything that the server is sending to the client on the webbrowser. Maybe this is how 50% of games work on the web and there are plenty of frameworks that support this! I wouldn't actually don't know : ( but my gut is telling me that most webgames are single player and 90% of the game is running on the client. So... any suggestions?

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  • I need help installing Ubuntu 11.10 to multi-drive system

    - by CookyMonzta
    I have a machine with 3 hard drives; the primary, which is 750GB (drive 0), and 2 others, each of which is 640GB (drives 1 and 2). On the last screen before the actual installation begins, this is how my hard drive configuration looks: /dev/sda [DISK0, 750GB] /dev/sda1 ntfs 104MB [Win7 System Reserved] /dev/sda2 ntfs 499,997MB [Windows 7 Pro] free space 250,052MB [This space intended for Windows 8] /dev/sdb [DISK1, 640GB] /dev/sdb1 ntfs 400,085MB [Windows XP Pro] free space 240,049MB [This space intended for Ubuntu] /dev/sdc [DISK2, 640GB] [This drive intended for various backups] free space 160,033MB /dev/sdc5 ntfs 480,101MB [Acronis Secure Zone] As you can see, I have 3 drives, all SATA. I have Win7 on my first drive (0), WinXP on my second drive (1) and a secure zone for daily backups on my third drive (2). I want to put Ubuntu 11.10 Oneiric Ocelot on the drive that also has XP. I've already used 400GB for XP and I have 240GB remaining, for which, my intention was to create a 4GB swap file and use the rest for Ubuntu itself. This is what my second hard drive looked like, for my intended setup before installation: /dev/sdb /dev/sdb5 swap 4,095MB [Linux swap] /dev/sdb6 ext4 235,951MB [Ubuntu 11.10] Needless to say, this is only the second time I have attempted to install Linux. I managed to get 7.10 Gutsy Gibbon working on an old machine. I have two problems with this installation: Ubuntu asks for a location to install the boot loader (i.e., "Device for Boot Loader Installation"). I already have a boot loader; namely, Acronis OS Selector (from Acronis Disk Director 11). So I decided to put the Ubuntu boot loader in /dev/sdb6 (where I intend to install Ubuntu), to keep it from interfering with my Acronis OS Selector. Once I hit "Install now", I ended up with the following error: "No root file system is defined. Please correct this from the partitioning menu." What am I missing? Did I attempt to put the boot loader in the wrong place? I assume I did, because as I am writing this entry, I am looking at LinuxIdentity.com's Ubuntu 11.04 Natty Narwhal magazine, and I see a screenshot (Figure 7 on Page 13) that implies that the boot loader can be installed anywhere, including the first hard drive (in the MBR, which would obviously force me to reinstall the Acronis OS Selector) or even on a floppy. But why do I get an undefined root file system error? I thought /dev/sdb6 was the root file. Obviously I'm missing something in the installation procedure. Should I try installing it in Windows using the WUBI Installer? I assume that, if I attempt to install Ubuntu from WinXP (on the second drive), it will automatically install Ubuntu on the empty partition alongside XP. But will I have the option of creating a swap partition? And what if the WUBI Installer searches all of my drives and decides to install Ubuntu on my first drive's empty partition (which I have left empty for Win8 upon its release)?

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  • Traditional POS is Dead

    - by David Dorf
    Traditional POS is dead -- I've heard that one before. Here's an excerpt from Joe Skorupa's blog over at RIS where he relayed ten trends that were presented at NRF. 7. Mobile POS signals death of traditional POS. Shoppers don't love self-checkout, but they prefer it to long queues or dealing with associates. Fixed POS is expensive and bulky. Mobile POS frees floor space for other purposes and converts associates from being cashiers to being sales assistants that provide new levels of customer service and incremental basket sales. In addition to unplugging the POS, new alternatives are starting to take hold - thin client, POS as a service, and replacing POS software with e-commerce platforms. I'll grant that in some situations for some retailers there might be an opportunity to to ditch the traditional POS, but for the majority of retailers that's just not practical. Take it from a guy that had to wake up at 3am after every Thanksgiving to monitor POS systems across the US on Black Friday. If a retailer's website goes down on Black Friday, they will take a significant hit. If a retailer's chain-wide POS system goes down on Black Friday, that retailer will cease to exist. Mobile POS works great for Apple because the majority of purchases are one or two big-ticket items that don't involve cash. There's still a traditional POS in every store to fall back on (its just hidden). Try this at home: Choose your favorite e-commerce site and add an item to the cart while timing how long it takes. Now multiply that by 15 to represent the 15 items you might buy at store like Target. The user interface isn't optimized for bulk purchases, and that's how it should be. The webstore and POS are designed for different purposes. Self-checkout is a great addition to POS and so is mobile checkout. But they add capabilities to POS, not replace it. Centralized architectures, even those based in the cloud, are quite viable as long as there's resiliency in the registers. You cannot assume perfect access to the network, so a POS must always be able to sell regardless of connectivity. Clearly the different selling channels should be sharing common functionality. Things like calculating tax, accepting coupons, and processing electronic payments can be shared, usually through a service-oriented architecture. This lowers costs and providers greater consistency, both of which help retailers. On paper these technologies look really good and we should continue to push boundaries, but I'm not ready to call the patient dead just yet.

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  • Play the Microsoft Game “Are You Certifiable?”

    - by Mysticgeek
    Want to know if you have what it takes to be certified by Microsoft? Today we check out an enjoyable way to practice and test your IT knowledge of Microsoft products.  There are two modes, one where you log in with your Live account so you can save your progress, and play additional levels.   If you log in with your Live account, it’s obvious that Microsoft wants to sell you some certification courses, so just be aware of that. Or Guest Play where you can only play one episode and scores are not saved.   Playing the Game We’ll take a look at the Guest Play just so you get a sense of what the game is about. Enter in a username and pick an avatar… Then read the instructions…we won’t go over them all here, there are a lot of options and points are scored by correct answers, amount of time it takes to answer them, you get vouchers to play a question before answers are shown…etc. Once you start playing, you get certification questions, you can take as much time to read the question as you want, then hit the Answer button when you’re ready. Now you have four answers to choose from…notice the time clicking down, so you want to try to answer as quickly as possible. After selecting the answer, you’re told if it is correct or not, then given an answer explaination, along with your score. You can flag the topic so it comes up again, which is a good way to get repetition of various topics, which really helps when taking the cert tests. If you get an answer wrong, you still get an answer explanation which is cool, so you can learn and better understand the topic. Conclusion This game is definitely not for everyone, only those who are curious or want a fun way to practice for Microsoft certifications. If you are interested in a cert from Microsoft, it’s a fun way to practice up. Play Are You Certifiable? Similar Articles Productive Geek Tips Geek Fun: Play Alien Arena the Free FPS GameFriday Fun: Get Your Mario OnFriday Fun: Play Bubble QuodFriday Fun: 13 Days in HellFriday Fun: Open Doors TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips DVDFab 6 Revo Uninstaller Pro Registry Mechanic 9 for Windows PC Tools Internet Security Suite 2010 Download Free iPad Wallpapers at iPad Decor Get Your Delicious Bookmarks In Firefox’s Awesome Bar Manage Photos Across Different Social Sites With Dropico Test Drive Windows 7 Online Download Wallpapers From National Geographic Site Spyware Blaster v4.3

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  • So, I though I wanted to learn frontend/web development and break out of my comfort zone...

    - by ripper234
    I've been a backend developer for a long time, and I really swim in that field. C++/C#/Java, databases, NoSql, caching - I feel very much at ease around these platforms/concepts. In the past few years, I started to taste end-to-end web programming, and recently I decided to take a job offer in a front end team developing a large, complex product. I wanted to break out of my comfort zone and become more of an "all around developer". Problem is, I'm getting more and more convinced I don't like it. Things I like about backend programming, and missing in frontend stuff: More interesting problems - When I compare designing a server that handle massive data, to adding another form to a page or changing the validation logic, I find the former a lot more interesting. Refactoring refactoring refactoring - I am addicted to Visual Studio with Resharper, or IntelliJ. I feel very comfortable writing code as it goes without investing too much thought, because I know that with a few clicks I can refactor it into beautiful code. To my knowledge, this doesn't exist at all in javascript. Intellisense and navigation - I hate looking at a bunch of JS code without instantly being able to know what it does. In VS/IntelliJ I can summon the documentation, navigate to the code, climb up inheritance hiererchies ... life is sweet. Auto-completion - Just hit Ctrl-Space on an object to see what you can do with it. Easier to test - With almost any backend feature, I can use TDD to capture the requirements, see a bunch of failing tests, then implement, knowing that if the tests pass I did my job well. With frontend, while tests can help a bit, I find that most of the testing is still manual - fire up that browser and verify the site didn't break. I miss that feeling of "A green CI means everything is well with the world." Now, I've only seriously practiced frontend development for about two months now, so this might seem premature ... but I'm getting a nagging feeling that I should abandon this quest and return to my comfort zone, because, well, it's so comfy and fun. Another point worth mentioning in this context is that while I am learning some frontend tools, a lot of what I'm learning is our company's specific infrastructure, which I'm not sure will be very useful later on in my career. Any suggestions or tips? Do you think I should give frontend programming "a proper chance" of at least six to twelve months before calling it quits? Could all my pains be growing pains, and will they magically disappear as I get more experienced? Or is gaining this perspective is valuable enough, even if plan to do more "backend stuff" later on, that it's worth grinding my teeth and continuing with my learning?

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  • My First 5K, the recap.

    - by Chris Williams
    It was a nice day to be outside (and trust me, those aren't words you'll hear from me often.) I got to the site around 7:45, hit the pre-reg table and got my number along with a goody bag full of coupons for racing gear, a water bottle and a tshirt. Oh and a map. Stashed all that stuff in the jeep, emptied my pockets of everything but my iPhone and my jeep key, and proceeded to walk around for a bit as people started showing up and signing in. It was fairly breezy, and there was definitely a storm coming... but it was anyone's guess on when it would actually arrive. It was interesting to see everyone who was participating. If I had to guess, I would say the event was 60-70% women, with a pretty broad distribution of age... as young as 13 to well over 60 (in both genders.) I don't know exactly how many folks were there, but it was well over 300. Eventually it was time to kick things off, and everyone made their way to the start line. All of the 5k and 10k runners were mixed together, starting at the same time. All the walkers and the people with strollers or dogs were in the back. It was pretty chaotic at first, once things started, but it thinned out fairly quickly. The 10k people and the hardcore runners sped ahead of everyone else and the walkers gradually lagged behind. The 5K course was pretty nice, winding around a lake down in Eden Prairie. The 10K course overlapped most of ours, but branched off a couple times too. I didn't run the whole time, but I started the race running and I ended it running, and did a mix of walking and running along the way. I met my goals, which were a) don't ever stop and b) don't be last. The weather managed to hold out for the entire race. It never got too hot, there was a nice breeze and it was mostly overcast. Pretty much perfect in my book. About 20-30 minutes after I left, the rain came down pretty hard. I had a good time, and will most likely do more of them. We'll see.

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  • Oracle OpenWorld / JavaOne Where I'll Be

    - by Shay Shmeltzer
    It's that time of the year again when San Francisco get flooded with Oracle and Java geeks for the annual OpenWorld and JavaOne conferences. Here are some of the places where you'll be able to find me: Sunday has a bunch of great ADF content in the ADF Enterprise Methodology Group track - I'm not sure if I'll make it there but I'm sure those who will will get some serious knowledge transfer. I'm starting Monday at the Keynote for Developers (10:45 in Salon 8 at the Marriott) - that's a great place for ADF developers to start the official week with an overview of what's new and upcoming in the world of development with ADF. While I'm not presenting this session - Chris Tonas who leads the development tools org will -  a demo that I built will be shown. So I'll be sitting in the audience crossing my fingers praying for the demo gods (and the wifi connection to work). My presentation part of the week starts on Monday at 12:15 at Moscone South room 306 where I'll be presenting "CON3004 - Understanding Oracle ADF and Its Role in Oracle Fusion"  . A basic introduction to ADF, it's architecture, development experience and how it integrates and works with the rest of the Fusion Middleware components.  After the session between 2-4 I'll be at the JDeveloper demo booth in Moscone South to answer any questions people might have. Then at 6:15 together with Grant we'll host BOF4492 - How to Get Started with Oracle ADF where we'll try and explain some of the learning paths and resources that are available for people who want to start learning ADF. This is a birds-of-a-feather so we'll also love to hear ideas from the audience about what paths they took and what things work or need improvment. Tuesday is relatively a quite day for me with a shift at the Oracle ADF Essentials pod at JavaOne from 1:30-3:30. There are several very good ADF architecture and best practices sessions on that day - so I'll try and hit those. Wednesday starts with another shift at the JDeveloper booth at JavaOne. Then at 4:30, instead of doing what all the ADF developers should do and heading over to the ADF meetup at the OTN Lounge, I'll be heading over to JavaOne for my CON3770 - Oracle JDeveloper and Oracle ADF: What’s New session. It's been a couple of years since the last time JDeveloper or ADF got any airtime at JavaOne - so it will be a great opportunity to show those in the Java community with open minds our approach to Java development. Now that ADF Essentials offers a free way to develop with ADF on GlassFish, I hope we'll be getting more people from the core Java camp interested in what we have to offer. Thursday is another relaxed day for me - who knows maybe I'll even be able to catch a session or two on that day. If you want to learn more about the ADF related sessions at OOW check out our full list here.

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  • Simple thruster like behaviour when rotating sprite

    - by ensamgud
    I'm prototyping some 2D game concepts with XNA and have added some basic keyboard inputs to control a triangle sprite. When I press key up the sprite accelerates in it's current facing direction, when I release the key it brakes down. For rotation, when I press left/right keys I rotate the sprite. Currently the sprite immedately changes direction when I rotate it. What I want is for it to keep moving in the same direction when I rotate, until I hit key up, adding thrust in whatever direction the sprite is pointing at. This would simulate thrusters on a classic space shooter like Asteroids. I'm adding an image to describe the behaviour I'm after and some code samples of how I'm doing things at the moment. This is my player struct, holding information of the sprite. public struct PlayerData { public Vector2 Position; // where to draw the sprite public Vector2 Direction; // travel direction of sprite public float Angle; // rotation of sprite public float Velocity; public float Acceleration; public float Decelleration; public float RotationAcceleration; public float RotationDecceleration; public float TopSpeed; public float Scale; } This is how I'm currently handling thrusting / braking (when pressing/releasing key up) (simplified, removed some bounds checking etc): player.Velocity += player.Acceleration * 0.1f; player.Velocity -= player.Acceleration * 0.1f; And when I rotate the sprite left and right: player.Angle -= player.RotationAcceleration * 0.1f; player.Angle += player.RotationAcceleration * 0.1f; This runs in the update loop, keeps the direction updated and updates the position: Vector2 up = new Vector2(0f, -1f); Matrix rotMatrix = Matrix.CreateRotationZ(player.Angle); player.Direction = Vector2.Transform(up, rotMatrix); player.Direction *= player.Velocity; player.Position += player.Direction; I am following along various beginner tutorials and haven't found any describing this, but I have tried some on my own without success. Do I need to change my velocity and acceleration fields to Vectors instead of floats to accomplish this type of movement? I realise my Angle and the Direction vector is currently tied together and I need to disconnect these somehow to be able to rotate freely without changing the direction of the movement, but I can't quite figure out how to do this while keeping the acceleration/decceleration functional. Would appreciate an explanation rather than pure code samples. Thanks,

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  • Your Cinnamon Roll & Morning Coffee: Powered by Oracle Enterprise Manager

    - by Ruma Sanyal
    1024x768 Truth be told, as I was getting my morning coffee today, I was pondering the recent election results more than Oracle [there, I said it]. But then an email from Glen Hawkins from the Enterprise Management team hit my Inbox and I started viewing this video. It was about the world’s largest convenience store chain, 7-Eleven, focusing on creating the best Digital Guest Experience (DGE) for their customers. Turns out that Oracle Enterprise Manager (OEM) powers 7-Eleven’s DGE Middleware Platform as a Service solution that consists of Oracle SOA Suite, Exalogic, and Exadata. “We need to present a consistent view of 7-Eleven across all our endpoints: 10,000 stores & various digital entities like our websites and apps”, said Ronald Clanton, the DGE Program Director for 7-Eleven. As 7-Eleven was rolling out a loyalty program with mobile support across multiple geos, it had many complex business & technical requirements, including supporting a wide variety of different apps, 10M guests in NA alone, ability to support high speed transactions, and very aggressive timelines. A key requirement was shortening the cycle for provisioning new environments. Whereas with other vendors this would take a few weeks, Oracle consulting showed them how with OEM provisioning new environments would take half a day, which was quite impressive. 7-Eleven has started to roll out this new program and are delighted to report that some provisioning cycles are as low as 10 minutes which includes provisioning the full Oracle SOA suite, Exalogic and more. They are delighted with OEM’s reporting capabilities and customization thereof. Watch the video to see for yourself. Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman","serif";}

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  • Switch from back-end to front-end programming: I'm out of my comfort zone, should I switch back?

    - by ripper234
    I've been a backend developer for a long time, and I really swim in that field. C++/C#/Java, databases, NoSql, caching - I feel very much at ease around these platforms/concepts. In the past few years, I started to taste end-to-end web programming, and recently I decided to take a job offer in a front end team developing a large, complex product. I wanted to break out of my comfort zone and become more of an "all around developer". Problem is, I'm getting more and more convinced I don't like it. Things I like about backend programming, and missing in frontend stuff: More interesting problems - When I compare designing a server that handle massive data, to adding another form to a page or changing the validation logic, I find the former a lot more interesting. Refactoring refactoring refactoring - I am addicted to Visual Studio with Resharper, or IntelliJ. I feel very comfortable writing code as it goes without investing too much thought, because I know that with a few clicks I can refactor it into beautiful code. To my knowledge, this doesn't exist at all in javascript. Intellisense and navigation - I hate looking at a bunch of JS code without instantly being able to know what it does. In VS/IntelliJ I can summon the documentation, navigate to the code, climb up inheritance hiererchies ... life is sweet. Auto-completion - Just hit Ctrl-Space on an object to see what you can do with it. Easier to test - With almost any backend feature, I can use TDD to capture the requirements, see a bunch of failing tests, then implement, knowing that if the tests pass I did my job well. With frontend, while tests can help a bit, I find that most of the testing is still manual - fire up that browser and verify the site didn't break. I miss that feeling of "A green CI means everything is well with the world." Now, I've only seriously practiced frontend development for about two months now, so this might seem premature ... but I'm getting a nagging feeling that I should abandon this quest and return to my comfort zone, because, well, it's so comfy and fun. Another point worth mentioning in this context is that while I am learning some frontend tools, a lot of what I'm learning is our company's specific infrastructure, which I'm not sure will be very useful later on in my career. Any suggestions or tips? Do you think I should give frontend programming "a proper chance" of at least six to twelve months before calling it quits? Could all my pains be growing pains, and will they magically disappear as I get more experienced? Or is gaining this perspective is valuable enough, even if plan to do more "backend stuff" later on, that it's worth grinding my teeth and continuing with my learning?

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  • Block-level deduplicating filesystem

    - by James Haigh
    I'm looking for a deduplicating copy-on-write filesystem solution for general user data such as /home and backups of it. It should use online/inline/synchronous deduplication at the block-level using secure hashing (for negligible chance of collisions) such as SHA256 or TTH. Duplicate blocks need not even touch the disk. The idea is that I should be able to just copy /home/<user> to an external HDD with the same such filesystem to do a backup. Simple. No messing around with incremental backups where corruption to any of the snapshots will nearly always break all later snapshots, and no need to use a specific tool to delete or 'checkout' a snapshot. Everything should simply be done from the file browser without worry. Can you imagine how easy this would be? I'd never have to think twice about backing-up again! I don't mind a performance hit, reliability is the main concern. Although, with specific implementations of cp, mv and scp, and a file browser plugin, these operations would be very fast, especially when there is a lot of duplication as they would only need to transfer the absent blocks. Accidentally using conventional copy tools that do not integrate with the FS would merely take longer, waste some bandwidth when copying remotely and waste some CPU, as the duplicate data would be re-read, re-transferred and re-hashed (although nothing would be re-written), but would absolutely not corrupt anything. (Some filesharing software may also be able to benefit by integrating with the FS.) So what's the best way of doing this? I've looked at some options: lessfs - Looks unmaintained. Any good? [Opendedup/SDFS][3] - Java? Could I use this on Android?! What does [SDFS][4] stand for? [Btrfs][5] - Some patches floating around on mailing list archives, but no real support. [ZFS][6] - Hopefully they'll one day relicense under a true Free/Opensource GPL-compatible licence. Also, 2 years ago I had a go at an attempt in Python using Fuse at the file-level to be used over the top of a typical solid FS such as EXT4, but I found Fuse for Python underdocumented and didn't manage to implement all of the system calls. My first post here, so I can't post more than 2 links until I get over 10 rep: [3]: http://www.opendedup.org/ [4]: https://en.wikipedia.org/w/index.php?title=SDFS&action=edit&redlink=1 [5]: https://en.wikipedia.org/wiki/Btrfs#Features [6]: https://en.wikipedia.org/wiki/ZFS#Linux

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  • New computer hangs on shutdown/reboot, how to troubleshoot?

    - by Torben Gundtofte-Bruun
    My system is working perfectly but it freezes during shutdown/reboot/suspend/hibernate: All windows and the menu bar disappear but the desktop wallpaper remains. It doesn't even show the shutdown screen (the one with the animated dots) where I could hit ESC and watch the shutdown console text. The system is brand-new and fully updated using Update Manager. How can I determine what is causing the freeze? Is there a log I can investigate? How can I fix this? I see no obvious cause of the freeze. The only USB attachment is a mouse/keyboard; I don't have any external storage attached; and I don't have any programs running (the machine freezes even when doing shutdown right from the login screen). What I've tried so far: Based on other questions (this, this, and this) that suggest some ACPI settings, I've tried sudo shutdown -h now to see whether the shutdown console text display offers any hints, but the system doesn't even get that far - it still freezes while the screen shown the desktop background image, without any toolbars. Only sudo shutdown --force works, but that's not a solution. Editing the grub menu to add acpi=off to the kernel didn't help. I guess there's not much point in trying the other (lesser) ACPI suggestions? Adding noapic to the grub entry had no discernible effect. Adding nolapic instead did something (I had removed the quiet option) - the system managed to continue further with the shutdown, right until the line Checking for running unattended-upgrades: which were the last characters on the screen. I've also checked the system BIOS, especially regarding power options, but didn't see anything out of the ordinary. Switching the BIOS standby setting from S3 to S1 didn't help. The standby setting can't be disabled, and there are no other ACPI-related settings AFAIK. BIOS reset didn't help. Not surprised; hadn't changed anything. I tried going to a virtual console (CtrlAltF1) as suggested by djeikyb and from there did a shutdown -h now and it froze there too, after this console output. I didn't try killing processes one at a time because I'm still too newbie to figure out how to do that. Booting with kernel 2.6.35.22 rather than 2.6.35.25 didn't help. Disabling the Nvidia drivers didn't help. Booting from Live CD (USB stick in fact) didn't help; it freezes the same way. Booting from Live CD, with acpi=off noapic nolapic didn't help either. Neither did just nolapic. So evidently this is not some custom setting in my install, but some sort of basic issue. MemTest competed in 1 hour without errors.

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  • Inherit one instance variable from the global scope

    - by Julian
    I'm using Curses to create a command line GUI with Ruby. Everything's going well, but I have hit a slight snag. I don't think Curses knowledge (esoteric to be fair) is required to answer this question, just Ruby concepts such as objects and inheritance. I'm going to explain my problem now, but if I'm banging on, just look at the example below. Basically, every Window instance needs to have .close called on it in order to close it. Some Window instances have other Windows associated with it. When closing a Window instance, I want to be able to close all of the other Window instances associated with it at the same time. Because associated Windows are generated in a logical fashion, (I append the name with a number: instance_variable_set(self + integer, Window.new(10,10,10,10)) ), it's easy to target generated windows, because methods can anticipate what assosiated windows will be called, (I can recreate the instance variable name from scratch, and almost query it: instance_variable_get(self + integer). I have a delete method that handles this. If the delete method is just a normal, global method (called like this: delete_window(@win543) then everything works perfectly. However, if the delete method is an instance method, which it needs to be in-order to use the self keyword, it doesn't work for a very clear reason; it can 'query' the correct instance variable perfectly well (instance_variable_get(self + integer)), however, because it's an instance method, the global instances aren't scoped to it! Now, one way around this would obviously be to simply make a global method like this: delete_window(@win543). But I have attributes associated with my window instances, and it all works very elegantly. This is very simplified, but it literally translates the problem exactly: class Dog def speak woof end end def woof if @dog_generic == nil puts "@dog_generic isn't scoped when .woof is called from a class method!\n" else puts "@dog_generic is scoped when .woof is called from the global scope. See:\n" + @dog_generic end end @dog_generic = "Woof!" lassie = Dog.new lassie.speak #=> @dog_generic isn't scoped when .woof is called from an instance method!\n woof #=> @dog_generic is scoped when .woof is called from the global scope. See:\nWoof! TL/DR: I need lassie.speak to return this string: "@dog_generic is scoped when .woof is called from the global scope. See:\nWoof!" @dog_generic must remain as an insance variable. The use of Globals or Constants is not acceptable. Could woof inherit from the Global scope? Maybe some sort of keyword: def woof < global # This 'code' is just to conceptualise what I want to do, don't take offence! end Is there some way the .woof method could 'pull in' @dog_generic from the global scope? Will @dog_generic have to be passed in as a parameter?

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  • Dual booting windows 8/ubuntu 12.04. Grub doesn't appear and machine never boot in ubuntu

    - by black sensei
    i got a new ACER predator AG3620-UR308 which came with windows 8, so i wanted to run ubuntu 12.04.2 on it as a dual booting. To be honest, i've been doing dual booting for a while now so, i did the right thing. the box came with 2TB HDD. so i made 4 partitions with a raw partition just after the windows installation partition I always do manual installation so even if ubuntu didn't detect windows 8, it was ok for me. So i created swap area and finished the installation etc....Grub was install on the only drive there which is sda. After reboot, grub doesn't even come up.So it always boot in windows 8. I did repeat the installation process twice and yield same result. which is weird because this method always works for me so far.Even the laptop am using to write this post is a dual booting windows 7/ mint nadia installed the same way. Is there anything new in windows 8 that i didn't make provision for? Before starting the installation, all i read about was that , windows 8 should be installed first and ubuntu after. I went ahead and disable secure boot from the BIOS and enabled CSM (don't even know what it means) according to Acer custhelp site . I boot from USB and did fdisk -l bellow is the result: ubuntu@ubuntu:~$ sudo fdisk -l WARNING: GPT (GUID Partition Table) detected on '/dev/sda'! The util fdisk doesn't support GPT. Use GNU Parted. Disk /dev/sda: 2000.4 GB, 2000398934016 bytes 255 heads, 63 sectors/track, 243201 cylinders, total 3907029168 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 4096 bytes I/O size (minimum/optimal): 4096 bytes / 4096 bytes Disk identifier: 0x8c361cb5 Device Boot Start End Blocks Id System /dev/sda1 1 3907029167 1953514583+ ee GPT Partition 1 does not start on physical sector boundary. Disk /dev/sdb: 8178 MB, 8178892800 bytes 255 heads, 63 sectors/track, 994 cylinders, total 15974400 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x0006a87e Device Boot Start End Blocks Id System /dev/sdb1 * 2048 15972351 7985152 b W95 FAT32 ubuntu@ubuntu:~$ Can anybody shed some light? thank you in advance

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  • Why my collision detection is not accurate?

    - by optimisez
    After trying and trying, I still cannot understand why the leg of character exceeds the wall but no clipping issue when I hit the wall from below. How should I fix it to make him standstill on the wall? void initPlayer() { // Create texture. hr = D3DXCreateTextureFromFileEx(d3dDevice, "player.png", 169, 44, D3DX_DEFAULT, NULL, D3DFMT_A8R8G8B8, D3DPOOL_MANAGED, D3DX_DEFAULT, D3DX_DEFAULT, D3DCOLOR_XRGB(255, 255, 255), NULL, NULL, &player); playerRect.left = playerRect.top = 0; playerRect.right = 29; playerRect.bottom = 36; playerDest.X = 0; playerDest.Y = 564; playerDest.length = playerRect.right - playerRect.left; playerDest.height = playerRect.bottom - playerRect.top; } void initBox() { hr = D3DXCreateTextureFromFileEx(d3dDevice, "brock.png", 330, 132, D3DX_DEFAULT, NULL, D3DFMT_A8R8G8B8, D3DPOOL_MANAGED, D3DX_DEFAULT, D3DX_DEFAULT, D3DCOLOR_XRGB(255, 255, 255), NULL, NULL, &box); boxRect.left = 33; boxRect.top = 0; boxRect.right = 63; boxRect.bottom = 30; boxDest.X = boxDest.Y = 300; boxDest.length = boxRect.right - boxRect.left; boxDest.height = boxRect.bottom - boxRect.top; } bool spriteCollide(Entity player, Entity target) { float left1, left2; float right1, right2; float top1, top2; float bottom1, bottom2; left1 = player.X; left2 = target.X; right1 = player.X + player.length; right2 = target.X + target.length; top1 = player.Y; top2 = target.Y; bottom1 = player.Y + player.height; bottom2 = target.Y + target.height; if (bottom1 < top2) return false; if (top1 > bottom2) return false; if (right1 < left2) return false; if (left1 > right2) return false; return true; } void collideWithBox() { if ( spriteCollide(playerDest, boxDest) && keyArr[VK_UP]) //playerDest.Y += 50; playerDest.Y = boxDest.Y + boxDest.height; else if ( spriteCollide(playerDest, boxDest) && !keyArr[VK_UP]) playerDest.Y = boxDest.Y - boxDest.height; }

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  • Can't change color of sprites in unity

    - by Aceleeon
    I would like to create a script that targets a 2d sprite "enemy" and changes their color to red (slightly opaque red if possible) when you hit tab. I have this code from a 3d tutorial hoping the transition would work. But it does not. I only get the script to cycle the enemy tags but never changes the color of the sprite. I have the code below I'm very new to coding, and any help would be FANTASTIC! HELP! hahah. TL;DR Cant get 3d color targeting to work for 2D. Check out the c#code below using UnityEngine; using System.Collections; using System.Collections.Generic; public class Targetting : MonoBehaviour { public List targets; public Transform selectedTarget; private Transform myTransform; // Use this for initialization void Start () { targets = new List(); selectedTarget = null; myTransform = transform; AddAllEnemies(); } public void AddAllEnemies() { GameObject[] go = GameObject.FindGameObjectsWithTag("Enemy"); foreach(GameObject enemy in go) AddTarget(enemy.transform); } public void AddTarget(Transform enemy) { targets.Add(enemy); } private void SortTargetsByDistance() { targets.Sort(delegate(Transform t1,Transform t2) { return Vector3.Distance(t1.position, myTransform.position).CompareTo(Vector3.Distance(t2.position, myTransform.position)); }); } private void TargetEnemy() { if(selectedTarget == null) { SortTargetsByDistance(); selectedTarget = targets[0]; } else { int index = targets.IndexOf(selectedTarget); if(index < targets.Count -1) { index++; } else { index = 0; } selectedTarget = targets[index]; } } private void SelectTarget() { selectedTarget.GetComponent().color = Color.red; } private void DeselectTarget() { selectedTarget.GetComponent().color = Color.blue; selectedTarget = null; } // Update is called once per frame void Update() { if(Input.GetKeyDown(KeyCode.Tab)) { TargetEnemy(); } } }

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  • Java @Contented annotation to help reduce false sharing

    - by Dave
    See this posting by Aleksey Shipilev for details -- @Contended is something we've wanted for a long time. The JVM provides automatic layout and placement of fields. Usually it'll (a) sort fields by descending size to improve footprint, and (b) pack reference fields so the garbage collector can process a contiguous run of reference fields when tracing. @Contended gives the program a way to provide more explicit guidance with respect to concurrency and false sharing. Using this facility we can sequester hot frequently written shared fields away from other mostly read-only or cold fields. The simple rule is that read-sharing is cheap, and write-sharing is very expensive. We can also pack fields together that tend to be written together by the same thread at about the same time. More generally, we're trying to influence relative field placement to minimize coherency misses. Fields that are accessed closely together in time should be placed proximally in space to promote cache locality. That is, temporal locality should condition spatial locality. Fields accessed together in time should be nearby in space. That having been said, we have to be careful to avoid false sharing and excessive invalidation from coherence traffic. As such, we try to cluster or otherwise sequester fields that tend to written at approximately the same time by the same thread onto the same cache line. Note that there's a tension at play: if we try too hard to minimize single-threaded capacity misses then we can end up with excessive coherency misses running in a parallel environment. Theres no single optimal layout for both single-thread and multithreaded environments. And the ideal layout problem itself is NP-hard. Ideally, a JVM would employ hardware monitoring facilities to detect sharing behavior and change the layout on the fly. That's a bit difficult as we don't yet have the right plumbing to provide efficient and expedient information to the JVM. Hint: we need to disintermediate the OS and hypervisor. Another challenge is that raw field offsets are used in the unsafe facility, so we'd need to address that issue, possibly with an extra level of indirection. Finally, I'd like to be able to pack final fields together as well, as those are known to be read-only.

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  • SDL - Getting a single keypress event instead of a keystate?

    - by MrKatSwordfish
    Right now I'm working on a simple SDL project, but I've hit an issue when trying to get a single keypress event to skip past a splash screen. Right now, there are 4 start-up splash screens that I would like to be able to skip with a single keypress (of any key). My issue is that, as of now, if I hold down a key, it skips through each splash screen to the very last one immediately. The splash screens are stored as an array of SDL surfaces which are all loaded at the initialization of the state. I have an variable called currentSplashImage that controls which element of the array is being rendered on the screen. I've set it up so that whenever there's a SDL_KEYDOWN event, it triggers a single incrementation of the currentSplashImage variable. So, I'm really not sure why my code isn't working correctly. For some reason, when I hold down a button, it seems to be treating the held button as a new key press event every time it ticks through the code. Does anyone know how I can go about fixing this issue? [Here's a snippet of code that I've been using...] void SplashScreenState::handleEvents() { SDL_PollEvent( &localEvent ); if ( localEvent.type == SDL_KEYDOWN ) { if ( currentSplashImage < 3 && currentSplashImage >= 0) { currentSplashImage++; } } else if ( localEvent.type == SDL_QUIT ) { smgaEngine.setRunning(false); } } I should also mention that the SDL_Event 'localEvent' is part of the GameState parent class, while this event handling code is part of a SplashScreenState subclass. If anyone knows why this is happening, or if there is any way to improve my code, It'd be helpful to me! :D I'm still a very new programmer, trying to learn. UPDATE: I added a std::cout line to that the code runs multiple times with a single KEYDOWN event. I also tried disabling SDL_EnableKeyRepeat, but it didn't fix the issue. void SplashScreenState::handleEvents() { SDL_PollEvent( &localEvent ); if ( localEvent.type == SDL_KEYDOWN ) { if ( currentSplashImage < 3 && currentSplashImage >= 0) { currentSplashImage++; std::cout << "KEYDOWN.."; //<---- test cout line } } else if ( localEvent.type == SDL_QUIT ) { smgaEngine.setRunning(false); } } This prints out "KEYDOWN..KEYDOWN..KEYDOWN.." in the cout stream when a button is held.

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