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  • Platformer Collision Error [closed]

    - by Connor
    I am currently working on a relatively simple platform game that has an odd bug.You start the game by falling onto the ground (you spawn a few blocks above the ground), but when you land your feet get stuck INSIDE the world and you can't move until you jump. Here's what I mean: The player's feet are a few pixels below the ground level. However, this problem only occurs in 3 places throughout the map and only in those 3 select places. I'm assuming that the problem lies within my collision detection code but I'm not entirely sure, as I don't get an error when it happens. public boolean isCollidingWithBlock(Point pt1, Point pt2) { //Checks x for(int x = (int) (this.x / Tile.tileSize); x < (int) (this.x / Tile.tileSize + 4); x++) { //Checks y for(int y = (int) (this.y / Tile.tileSize); y < (int) (this.y / Tile.tileSize + 4); y++) { if(x >= 0 && y >= 0 && x < Component.dungeon.block.length && y < Component.dungeon.block[0].length) { //If the block is not air if(Component.dungeon.block[x][y].id != Tile.air) { //If the player is in contact with point one or two on the block if(Component.dungeon.block[x][y].contains(pt1) || Component.dungeon.block[x][y].contains(pt2)) { //Checks for specific blocks if(Component.dungeon.block[x][y].id == Tile.portalBlock) { Component.isLevelDone = true; } if(Component.dungeon.block[x][y].id == Tile.spike) { Health.health -= 1; Component.isJumping = true; if(Health.health == 0) { Component.isDead = true; } } return true; } } } } } return false; } What I'm asking is how I would fix the problem. I've looked over my code for quite a while and I'm not sure what's wrong with it. Also, if there's a more efficient way to do my collision checking then please let me know! I hope that is enough information, if it's not just tell me what you need and I'll be sure to add it. Thank you! [EDIT] Jump code: if(!isJumping && !isCollidingWithBlock(new Point((int) x + 2, (int) (y + height)), new Point((int) (x + width + 2), (int) (y + height)))) { y += fallSpeed; //sY is the screen's Y. The game is a side-scroller Component.sY += fallSpeed; } else { if(Component.isJumping) { isJumping = true; } } if(isJumping) { if(!isCollidingWithBlock(new Point((int) x + 2, (int) y), new Point((int) (x + width + 2), (int) y))) { if(jumpCount >= jumpHeight) { isJumping = false; jumpCount = 0; } else { y -= jumpSpeed; Component.sY -= jumpSpeed; jumpCount += 1; } } else { isJumping = false; jumpCount = 0; } }

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  • Fans running very fast on MacBook Pro 8.1 ubuntu 12.04

    - by Tomasz Kacprzak
    I installed Ubuntu 12.04 on Macbook Pro 8.1 and one of the first things I noticed was that the fans were starting to spin very fast every few minutes for 10-30 sec and then going back to normal. That was happening even without any processor load, when completely idle. The fans were usually spinning at 4000 RPM and made much noise. The computer was not getting hotter than usual. When running OSX Lion there was no noise at all, fans almost all the time at 2000 RPM. I spent some time on it and found out that Precise uses a deamon to control the temperature, called macfanctld. You can use /etc/macfanctld.conf to set the configuration. I found out that the high fan speed is not due to the fact that the temperature is getting hot, but because there are two sensors which indicate wrong numbers (you can check that using 'sensors' command ): TW0P: +129.0°C TCTD: +256.0°C TCFC: +0.0°C TMBS: +0.0°C or setting the macfanctld log level to 2: Speed: 4992, *AVG: 56.9C, TC0P: 50.2C, TG0P: 51.5C, Sensors: TB0T:34 TB1T:34 TB2T:33 TC0C:58 TC0D:56 TC0E:59 TC0F:60 TC0P:50 TC1C:58 TC2C:58 TC3C:58 TC4C:57 TCFC:0 TCGC:57 TCSA:53 TCTD:256 TG0D:52 TG0P:52 THSP:42 TM0S:64 TMBS:0 TP0P:54 TPCD:60 TW0P:129 Th1H:51 Th2H:48 Tm0P:40 Ts0P:32 Ts0S:43 Moreover, TCTD was randomly jumping from temperatures of 0 to 256, so this may be the reason for unjustified random fan speeds. macfanctld is taking an average of the sensors including the values above, so the actual AVG temp used to control the fans is wrong, usually biased up, hence high RPM and noise. The workaround solution is to use an option in the macfanctld.conf which allows to ignore the malfunctioning sensors: exclude: 13 16 21 24 After reboot the reported temperatures are usually normal and the fans are working at reasonable speeds. I tested the response of the fans to heavy processor load by asking MATLAB to invert 10000x10000 matrix and the AVG temperature jumped to 63deg, and the fan to max 6200 RPM and then got it back to normal temperature. So I think it is safe so far. There is a expired bug about the failing sensor readings: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/955538 which may be good to open again. My question would be: does anyone know what the failing sensors do and if there is any danger in excluding them? Maybe some better solution to this problem?

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  • Crash when using datablocks

    - by scorcher24
    I have really throughly searched the net and could not find any solution for this so I ask for help here. Anyway, I have this datablock in datablocks.cs: datablock t2dSceneObjectDatablock(EnemyShipConfig) { canSaveDynamicFields = "1"; Layer = "3"; size = "64 64"; CollisionActiveSend = "1"; CollisionActiveReceive = "1"; CollisionCallback = true; CollisionLayers = "3"; CollisionDetectionMode = "POLYGON"; CollisionPolyList = "0.00 -0.791 0.756 0.751 -0.746 0.732"; UsesPhysics = "0"; Rotation = "-90"; WorldLimitMode = "KILL"; WorldLimitMax = "880 360"; WorldLimitMin = "-765 -436"; minFireRate = "2000"; maxFireRate = "1200"; laserSpeed = "800"; minSpeed = "100"; maxSpeed = "150"; }; This is an exact reproduction of an object that I have manually edited in the editor. So far, I just used clone() to get as many enemies as I need, while it was out of sight. It is a r-type style shooter, so I need a variable amount of enemies. Since clone() spams my log, I decided to use datablocks, since it is also more flexible. That's what I get when I use clone(): Con::execute - 0 has no namespace: onRemoveFromScene However, once spawning begins, my game freezes and crashes: function SpawnEnemy() { //%spawnedEnemy = EnemyShipMaster.clone(true); %spawnedEnemy = new t2dStaticSprite() { class = "EnemyShip"; sceneGraph = $global_sceneGraph; datablock = "EnemyShipConfig"; imageMap = "starshipImageMap"; layer = 3; }; %speed = getRandom(%spawnedEnemy.minSpeed, %spawnedEnemy.maxSpeed); %y = getRandom(-320, 320); // Set Properties %spawnedEnemy.setPositionX(700); %spawnedEnemy.setPositionY(%y); %spawnedEnemy.setVisible(true); %spawnedEnemy.setLinearVelocityX( -%speed ); %spawnedEnemy.setTimerOn( getRandom( %spawnedEnemy.maxFireRate, %spawnedEnemy.minFireRate ) ); } // Definition of $global_sceneGraph from game.cs: $global_sceneGraph = sceneWindow2D.loadLevel(%level); As I said, it works fine when I use clone() (which is commented out here), but my log gets spammed. I really hope someone can shed some light for me, this is driving me crazy.

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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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  • Sampling SQL server batch activity

    - by extended_events
    Recently I was troubleshooting a performance issue on an internal tracking workload and needed to collect some very low level events over a period of 3-4 hours.  During analysis of the data I found that a common pattern I was using was to find a batch with a duration that was longer than average and follow all the events it produced.  This pattern got me thinking that I was discarding a substantial amount of event data that had been collected, and that it would be great to be able to reduce the collection overhead on the server if I could still get all activity from some batches. In the past I’ve used a sampling technique based on the counter predicate to build a baseline of overall activity (see Mikes post here).  This isn’t exactly what I want though as there would certainly be events from a particular batch that wouldn’t pass the predicate.  What I need is a way to identify streams of work and select say one in ten of them to watch, and sql server provides just such a mechanism: session_id.  Session_id is a server assigned integer that is bound to a connection at login and lasts until logout.  So by combining the session_id predicate source and the divides_by_uint64 predicate comparator we can limit collection, and still get all the events in batches for investigation. CREATE EVENT SESSION session_10_percent ON SERVER ADD EVENT sqlserver.sql_statement_starting(     WHERE (package0.divides_by_uint64(sqlserver.session_id,10))), ADD EVENT sqlos.wait_info (        WHERE (package0.divides_by_uint64(sqlserver.session_id,10))), ADD EVENT sqlos.wait_info_external (        WHERE (package0.divides_by_uint64(sqlserver.session_id,10))), ADD EVENT sqlserver.sql_statement_completed(     WHERE (package0.divides_by_uint64(sqlserver.session_id,10))) ADD TARGET ring_buffer WITH (MAX_DISPATCH_LATENCY=30 SECONDS,TRACK_CAUSALITY=ON) GO   There we go; event collection is reduced while still providing enough information to find the root of the problem.  By the way the performance issue turned out to be an IO issue, and the session definition above was more than enough to show long waits on PAGEIOLATCH*.        

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  • RPi and Java Embedded GPIO: It all begins with hardware

    - by hinkmond
    So, you want to connect low-level peripherals (like blinky-blinky LEDs) to your Raspberry Pi and use Java Embedded technology to program it, do you? You sick foolish masochist. No, just kidding! That's awesome! You've come to the right place. I'll step you though it. And, as with many embedded projects, it all begins with hardware. So, the first thing to do is to get acquainted with the GPIO header on your RPi board. A "header" just means a thingy with a bunch of pins sticking up from it where you can connect wires. See the the red box outline in the photo. Now, there are many ways to connect to that header outlined by the red box in the photo (which the RPi folks call the P1 header). One way is to use a breakout kit like the one at Adafruit. But, we'll just use jumper wires in this example. So, to connect jumper wires to the header you need a map of where to connect which wire. That's why you need to study the pinout in the photo. That's your map for connecting wires. But, as with many things in life, it's not all that simple. RPi folks have made things a little tricky. There are two revisions of the P1 header pinout. One for older boards (RPi boards made before Sep 2012), which is called Revision 1. And, one for those fancy 512MB boards that were shipped after Sep 2012, which is called Revision 2. So, first make sure which board you have: either you have the Model A or B with 128MB or 256MB built before Sep 2012 and you need to look at the pinout for Rev. 1, or you have the Model B with 512MB and need to look at Rev. 2. That's all you need for now. More to come... Hinkmond

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  • Complete Beginner to Game Programming and Unreal Engine 4, Looking For Advice [on hold]

    - by onemic
    I am currently a 2nd year programming student(Just finished my first year so I will be starting my second year in September) and have mainly learned C and C++ in my classes. In terms of what I know of C++, I know about general inheritance, polymorphism, overloading operators, iterators, a little bit about templates(only class and function templates) etc. but not of the more advanced topics like linked lists and other sequential containers(containers in general I guess), enumerations, most of the standard library(other than like strings and vectors), and probably a bunch of other stuff I dont even know about yet. I subscribed to Unreal Engine 4 as I was very intrigued by their Unreal Tournament announcement earlier this month, especially after hearing that UE4 is going completely C++. Of course my end goal in doing this programming program is to eventually go into game/graphics programming. Since it's my summer off, I thought what better way then to actually apply some of my skills to a personal project so I actually have a firmer understanding of C++ past what my professors tell me. My questions are this: What would be the best way to start off making a small personal game in UE4 as a project for the summer? What should I be aiming for, especially for someone that is still learning C++? Should I focus on making a simple 2D game rather than a 3D one to get started? Seeing the Flappy Chicken showcase intrigued me because before I thought the UE engine was pretty much pigeonholed into being for FPS games What should my expectations be going into UE4 and a game engine for the first time?(UE4 will be my first foray into making a game) What can I expect to gain from making things in UE4, in terms of making games and in terms of further fleshing out my knowledge of C++? Would you recommend I start off 100% using C++ for scripting or using the visual blueprints? Since I'm not a designer, how would I be able to add objects and designs to my game? For someone at my level is retaining the UE4 subscription worth it or is it better to cancel and resub when I learn enough about UE4 and C++? Lastly is there anything to be gained in terms of knowledge/insight through me looking at the source code for UE4? I opened it in VS2013, but noticed that most of the files were C# files and not cpp's. Thanks in advance for taking the time to answer.

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  • Is this an effective monetization method for an Android game? [on hold]

    - by Matthew Page
    The short version: I plan to make an Android puzzle game where the user tries to get 3-6 numbers to their predetermined goal numbers. The free version of the app will have three predetermined levels (easy, medium, hard). The full version ($0.99, probably) will have a level generator where there will be unlimited easy, medium, or hard levels, as well as a custom difficulty option where users can set specific vales to the number of numbers to equate to their goal, the number of buttons to use, etc. Users will also have the option to get a one-time "hint" for a fee of $0.49, or unlimited hints for a one-time fee of $2.99. The long version: Mechanics of Game and Victory The application is a number puzzle. When the user begins a new game, depending on the input by the user, between 3 and 6 numbers show up on the top of the screen, and between 3 and 6 buttons show up on the bottom of the screen. The buttons all have two options: to increase every number the same way, or decrease every number the same way. The buttons either use addition / subtraction, multiplication / division, or exponents / roots, all depending on the number displayed on the button. Addition buttons are green, multiplication buttons are blue, and exponential buttons are red. The user wins when all of the numbers displayed on the screen equate to their goal number, displayed below each number. Monetization If the user is playing the full (priced) version of the app, upon the start of the game, the user will be confronted with a dialogue asking for the number of buttons and the number of numbers to equate in the game. Then, based on the user input, a random puzzle will be generated. If the user is playing the free version of the app, the user will be asked to either play an “easy”, “hard”, or “expert” puzzle. A pre-determined puzzle from each category will be used in the game. If the user has played that puzzle before, a dialogue will show saying this to the user and advertising the full version of the app. The full version of the app will also be advertised upon the successful or in successful completion of a puzzle. Upon exiting this advertisement, another full screen advertisement will appear from a third party. Also, the solution to the puzzle should be stored by the program, and if the user pays a small fee, he/she can see a hint to the solution to the program. In the free version of the app, the user may use their first hint for free. Also, the user can use unlimited hints for a slightly larger fee. Is this an effective monetization method?

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  • Why is Java the lingua franca at so many institutions?

    - by Billy ONeal
    EDIT: This question at first seems to be bashing Java, and I guess at this point it is a bit. However, the bigger point I am trying to make is why any one single language is chosen as the one end all be all solution to all problems. Java happens to be the one that's used so that's the one I had to beat on here, but I'm not intentionality ripping Java a new one :) I don't like Java in most academic settings. I'm not saying the language itself is bad -- it has several extremely desirable aspects, most importantly the ability to run without recompilation on most any platform. Nothing wrong with using the language for Your Next App ^TM. (Not something I would personally do, but that's more because I have less experience with it, rather than it's design being poor) I think it is a waste that high level CS courses are taught using Java as a language. Too many of my co-students cannot program worth a damn, because they don't know how to work in a non-garbage-collected world. They don't fundamentally understand the machines they are programming for. When someone can work outside of a garbage collected world, they can work inside of one, but not vice versa. GC is a tool, not a crutch. But the way it is used to teach computer science students is a as a crutch. Computer science should not teach an entire suite of courses tailored to a single language. Students leave with the idea that all good design is idiomatic Java design, and that Object Oriented Design is the ONE TRUE WAY THAT IS THE ONLY WAY THINGS CAN BE DONE. Other languages, at least one of them not being a garbage collected language, should be used in teaching, in order to give the graduate a better understanding of the machines. It is an embarrassment that somebody with a PHD in CS from a respected institution cannot program their way out of a paper bag. What's worse, is that when I talk to those CS professors who actually do understand how things operate, they share feelings like this, that we're doing a disservice to our students by doing everything in Java. (Note that the above would be the same if I replaced it with any other language, generally using a single language is the problem, not Java itself) In total, I feel I can no longer respect any kind of degree at all -- when I can't see those around me able to program their way out of fizzbuzz problems. Why/how did it get to be this way?

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  • Upgrades from Beta or CTP SQL Server Software is NOT Supported

    - by BuckWoody
    As of this writing, SQL Server 2008 R2 has released, and just like every release, I get e-mails and calls from folks with this question: “Can I upgrade from Customer Technical Preview (CTP) x or Beta #x or Release Candidate (RC) to the “Released to Manufacturing” (RTM) version?” No. Right up until the last minute, things are changing in the code – and you want that to happen. Our internal testing runs right up until the second we lock down for release, and we watch the CTP/RC/Beta reports to make sure there are no show-stoppers, and fix what we find. And it’s not just “big” changes you need to worry about – a simple change in one line of code can have a massive effect. I know, I know – you’ve possibly upgraded an RC or CTP to the RTM version and it worked “just fine”. But hear this tale: I’ve dealt with someone who faced this exact situation in SQL Server 2008. They upgraded (which is clearly prohibited in the documentation) from a CTP to the RTM version over a year ago. Everything was working fine. But then…one day they had an issue. Couldn’t fix it themselves, we took a look, days went by, and we finally had to call in the big guns for support. Turns out, the upgrade was the problem. So we had to come up with some elaborate schemes to get the system migrated over while they were in production. This was painful for everyone involved. So the answer is still no. Just don’t do it. There is one caveat to this story – if you are a “TAP” customer (you’ll know if you are), we help you move from the CTP products to RTM, but that’s a special case that we track carefully and send along special instructions and tools to help you along. That level of effort isn’t possible on a large scale, so it’s not just a magic tool that we run to upgrade from CTP to RTM. So again, unless you’re a TAP customer, it’s a no-no. Share this post: email it! | bookmark it! | digg it! | reddit! | kick it! | live it!

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  • Website directory structure regarding subdomains, www, and "global" content

    - by Pawnguy7
    I am trying to make a homemade HTTP server. It occurs to me, though, I never fully understood what you might call "relativity" among web pages. I have come across that www. is a subdomain, and I understand its original purpose. IT sounds like, in general, you would redirect (is that 301 or 302?) it to a... non-subdomain, sort of. As in, redirecting www.example.com to example.com. I am not entirely sure how to make this work when retrieving files for an HTTP server though. I would assume that example.com would be the root, and www manifests as a folder within it. I am unsure. There is also the question of multi-level subdomains, e.g. subdomain2.subdomain1.example.com. It seems to me they are structured "backwards", where you go from the root left in folder structure. In this situation, subdomain2 is a directory within subdomain1, which is a directory in the root. Finally, it occurs to me I might want a sort of global location. For example, maybe all subdomains still use an image as a logo. It makes more sense to me that there is one image, rather than each having a copy. In the same way, albiet more doubtfully, you might have global CSS (though that is a bit contrary to the idea of a subdomain in the first place), or a javascript that is commonly used. (more efficient than each having its copy and better for organization purposes). Finally, mabye you have a global 404 page. I think this might be the case where you have user-created subdomains (say bloggername.example.com), where example.com still has a default 404 when either a subdomain does not exist or page does not exists under a valid blogger. I am confused on what the directory structure for this should be. To summarize: Should and how it have a global files not in a subdirectory, how should www. be handled, (or how a now www or other subdomain should be handled), and the pattern for root/subdomain, as well as subdomain within subdomains (order-wise). Sorry this is multiple questions, but I feel at the root they are all related to the directory.

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  • Access Control Service v2: Registering Web Identities in your Applications [code]

    - by Your DisplayName here!
    You can download the full solution here. The relevant parts in the sample are: Configuration I use the standard WIF configuration with passive redirect. This kicks automatically in, whenever authorization fails in the application (e.g. when the user tries to get to an area the requires authentication or needs registration). Checking and transforming incoming claims In the claims authentication manager we have to deal with two situations. Users that are authenticated but not registered, and registered (and authenticated) users. Registered users will have claims that come from the application domain, the claims of unregistered users come directly from ACS and get passed through. In both case a claim for the unique user identifier will be generated. The high level logic is as follows: public override IClaimsPrincipal Authenticate( string resourceName, IClaimsPrincipal incomingPrincipal) {     // do nothing if anonymous request     if (!incomingPrincipal.Identity.IsAuthenticated)     {         return base.Authenticate(resourceName, incomingPrincipal);     } string uniqueId = GetUniqueId(incomingPrincipal);     // check if user is registered     RegisterModel data;     if (Repository.TryGetRegisteredUser(uniqueId, out data))     {         return CreateRegisteredUserPrincipal(uniqueId, data);     }     // authenticated by ACS, but not registered     // create unique id claim     incomingPrincipal.Identities[0].Claims.Add( new Claim(Constants.ClaimTypes.Id, uniqueId));     return incomingPrincipal; } User Registration The registration page is handled by a controller with the [Authorize] attribute. That means you need to authenticate before you can register (crazy eh? ;). The controller then fetches some claims from the identity provider (if available) to pre-fill form fields. After successful registration, the user is stored in the local data store and a new session token gets issued. This effectively replaces the ACS claims with application defined claims without requiring the user to re-signin. Authorization All pages that should be only reachable by registered users check for a special application defined claim that only registered users have. You can nicely wrap that in a custom attribute in MVC: [RegisteredUsersOnly] public ActionResult Registered() {     return View(); } HTH

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  • Fans running very fast on MacBook Pro 8.1

    - by Tomasz Kacprzak
    I installed Ubuntu 12.04 on Macbook Pro 8.1 and one of the first things I noticed was that the fans were starting to spin very fast every few minutes for 10-30 sec and then going back to normal. That was happening even without any processor load, when completely idle. The fans were usually spinning at 4000 RPM and made much noise. The computer was not getting hotter than usual. When running OSX Lion there was no noise at all, fans almost all the time at 2000 RPM. I spent some time on it and found out that Precise uses a deamon to control the temperature, called macfanctld. You can use /etc/macfanctld.conf to set the configuration. I found out that the high fan speed is not due to the fact that the temperature is getting hot, but because there are two sensors which indicate wrong numbers (you can check that using 'sensors' command ): TW0P: +129.0°C TCTD: +256.0°C TCFC: +0.0°C TMBS: +0.0°C or setting the macfanctld log level to 2: Speed: 4992, *AVG: 56.9C, TC0P: 50.2C, TG0P: 51.5C, Sensors: TB0T:34 TB1T:34 TB2T:33 TC0C:58 TC0D:56 TC0E:59 TC0F:60 TC0P:50 TC1C:58 TC2C:58 TC3C:58 TC4C:57 TCFC:0 TCGC:57 TCSA:53 TCTD:256 TG0D:52 TG0P:52 THSP:42 TM0S:64 TMBS:0 TP0P:54 TPCD:60 TW0P:129 Th1H:51 Th2H:48 Tm0P:40 Ts0P:32 Ts0S:43 Moreover, TCTD was randomly jumping from temperatures of 0 to 256, so this may be the reason for unjustified random fan speeds. macfanctld is taking an average of the sensors including the values above, so the actual AVG temp used to control the fans is wrong, usually biased up, hence high RPM and noise. The workaround solution is to use an option in the macfanctld.conf which allows to ignore the malfunctioning sensors: exclude: 13 16 21 24 After reboot the reported temperatures are usually normal and the fans are working at reasonable speeds. I tested the response of the fans to heavy processor load by asking MATLAB to invert 10000x10000 matrix and the AVG temperature jumped to 63deg, and the fan to max 6200 RPM and then got it back to normal temperature. So I think it is safe so far. There is a expired bug about the failing sensor readings: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/955538 which may be good to open again. My question would be: does anyone know what the failing sensors do and if there is any danger in excluding them? Maybe some better solution to this problem?

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  • How much am I worth hourly as a software/web developer? [closed]

    - by luckysmack
    I may be starting a new job very soon as a developer for both web and desktop software. The primary languages I will be using is ASP.NET with C# with some php for existing projects(I've already had one interview which went very well). The job deals primarily in advertising. But this is my first real job in the market, I have no degrees, but have some college time(~1yr). So I am primarily self taught. They are fully aware of my skill set and lack of degrees or certificates. I applied as an entry level developer. It will be a permanent and full time/hourly position, and not a per contract job. So since it my cherry job, im not really sure what to ask for. even though im self taught im pretty confident in my skills and know what im doing fairly well. I pick up on new concepts very well and find new things fairly easy to learn. Here is a very brief summary of my skills: PHP: ~2years C#/.NET: 2 months Python: Basics only. ~1 month OOP Familiarity: Great (1 year) MVC Familiarity: Great (1 year) PHP Frameworks used: CakePHP(6 months), Yii(3 months), Lithium(3 months) CMS Familiar with: Drupal(1.5 years), Wordpress(only basics) I also have ~2yrs experience in maintaining my own VPS server and the hassles all that entails (linux/debian) Pretty much all the above will be used at this job. Although I will be using C# a vast majority of the time. I only recently started learning it but am moving along fairly rapidly and its all going smooth as butter. So what have I built? I have one proprietary site built in drupal which is used an an order log for products, inventory, and their shipments. It is also able to process payments through paypal merchant services. I have worked on a handful of other small apps used here and there I'm not able to show but which worked fairly well (all in php using frameworks though). The business does fairly well and is far from a a typical corporate type environment. It is much closer to a small development studio. And it is based out of northern California. I don't know how/what more info I can give on them. I also want this to be able to be referenced by other people possibly so I am looking for general tips and ideas to get an answer as well. I had trouble finding a reasonable range on other websites which seemed to be either way to low, or showed what a veteran developer makes. I know this is a fairly subjective question, but it is difficult to get a reasonable answer or guesstimate anywhere else. Even if only a little bit help, its much appreciated. So as for the direct question, based on all this info (did I miss anything?), how much should I ask for hourly? How much am I worth as a software developer?

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  • Determining whether a visitor reached two different pages in one visit

    - by Shaun
    I have a funnel that I would like to track. Tracking this funnel won't work with the default "goal funnel" tracking in Google due to the fact that I am mixing events and pageviews. As such, I've created a series of reports: Visits to demo pages - An inclusion filter on "Page". Triggers an Event on these pages - An inclusion filter on "Page" and "Event Category". Does not bounce - An inclusion filter on "Page" and an exclusion filter on "Exit Page" for these same pages. Reach our storefront - ?? Purchase something - An inclusion filter on "Page" and a report that shows "Transactions". At a basic level, I need to track users who reached demo pages, then reached any page on our store. Intuitively, I created a segment, used two inclusive "Page" filters (one for the demo pages and one for any page in our store), and combined them with an "AND" operator. I thought this was working until I tried to do the same thing in a dashboard widget and on a custom report. When I tried the same thing in those areas, I got zero results. I figured this might be because widgets and custom report filters function differently from segment filters (the options are different for all of them), so I tried applying my "demo page && store page" segment to a report that gave me a general page list. All I saw was a list of the specific pages. I tried simplifying things by creating a custom report that showed all visits to store pages, then applied a segment that filtered for users who visited demo pages. This got me the same numbers as my "demo page && store page" segment, but showed a list of demo pages. This has led me to believe that the "demo page && store page segment" approach and the "demo segment && store report" functionally behave the same. However, this experience has left me questioning whether they're giving me what I want. Are these methods showing me all users who reached both sets of pages? Is there a better/easier/more standard way of doing this aside from looking at visitor flow reports? I'm trying to avoid a combination of custom variables/events and using the horizontal funnel approach since it would consume a large number of our limited goals and seems more complicated than is necessary for tracking this funnel.

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  • TechEd 2010 Day Three: The Database Designer (Isn't)

    - by BuckWoody
    Yesterday at TechEd 2010 here in New Orleans I worked the front-booth, answering general SQL Server questions for the masses. I was actually a little surprised to find most of the questions I got were from folks that wanted to know more about Stream Insight and Master Data Services. In past conferences I've been asked a lot of "free consulting" questions, about problems folks have had from older products. I don't mind that a bit - in fact, I'm always happy to help in any way I can. But this time people are really interested in the new features in the product, and I like that they are thinking ahead, not just having to solve problems in production. My presentation was on "Database Design in an Hour". We had the usual fun, and SideShow Bob made an appearance - I kid you not. The guy in the back of the room looked just like Sideshow Bob, so I quickly held a "bes thair" contest, and he won. Duing the presentation, I explain the tools you can use to design databases. I also explain that the "Database Designer" tool in SQL Server Management Studio (SSMS) isn't truly a desinger - it uses non-standard notation, doesn't have a meta-data dictionary, and worst of all, it works at the physical level. In other words, whatever you do in SSMS will automatically change the field/table/relationship structures in the database. We fixed this in SSMS 2008 and higher by adding an option to block that, but the tool is not a good design function nonetheless. To be fair, no one I know of at Microsoft recommends that it is - but I was shocked to hear so many developers in the room defending it as a good tool. I think the main issue for someone who doesn't have to work with Relational Systems a great deal is that it can be difficult to figure out Foreign Keys. The syntax makes them look "backwards", so it's just easier to grab a field and place it on the table you want to point to. There are options. You can download a couple of free tools (CA has a community edition of ER-WIN, Quest has one, and Embarcadero also has one) and if you design more than one or two databases a year, it may be worth buying a true design tool. For years I used Visio, but we changed it so that it doesn't forward-engineer (create the DDL) any more, so it isn't a true design tool either. So investigate those free and not-so-free tools. You'll find they help you in your job - but stay away from the Database Designer in SSMS. Or I'll send Sideshow Bob over there to straighten you out. Share this post: email it! | bookmark it! | digg it! | reddit! | kick it! | live it!

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  • Project Time Tracker

    - by Geertjan
    Based on yesterday's blog entry, let's do something semi useful and display, in the project popup, which is available when you right-click a project in the Projects window, the time since the last change was made anywhere in the project, i.e., we can listen recursively to any changes done within a project and then update the popup with the newly acquired information, dynamically: import java.awt.event.ActionEvent; import java.text.DateFormat; import java.text.SimpleDateFormat; import java.util.ArrayList; import java.util.Collection; import java.util.List; import javax.swing.AbstractAction; import org.netbeans.api.project.Project; import org.netbeans.api.project.ProjectUtils; import org.openide.awt.ActionID; import org.openide.awt.ActionReference; import org.openide.awt.ActionRegistration; import org.openide.awt.StatusDisplayer; import org.openide.filesystems.FileAttributeEvent; import org.openide.filesystems.FileChangeListener; import org.openide.filesystems.FileEvent; import org.openide.filesystems.FileRenameEvent; import org.openide.util.Lookup; import org.openide.util.LookupEvent; import org.openide.util.LookupListener; import org.openide.util.Utilities; import org.openide.util.WeakListeners; @ActionID( category = "Demo", id = "org.ptt.TrackProjectSelectionAction") @ActionRegistration( lazy = false, displayName = "NOT-USED") @ActionReference( path = "Projects/Actions", position = 0) public final class TrackProjectSelectionAction extends AbstractAction implements LookupListener, FileChangeListener { private Lookup.Result<Project> projects; private Project context; private Long startTime; private Long changedTime; private DateFormat formatter; private List<Project> timedProjects; public TrackProjectSelectionAction() { putValue("popupText", "Timer"); formatter = new SimpleDateFormat("HH:mm:ss"); timedProjects = new ArrayList<Project>(); projects = Utilities.actionsGlobalContext().lookupResult(Project.class); projects.addLookupListener( WeakListeners.create(LookupListener.class, this, projects)); resultChanged(new LookupEvent(projects)); } @Override public void resultChanged(LookupEvent le) { Collection<? extends Project> allProjects = projects.allInstances(); if (allProjects.size() == 1) { Project currentProject = allProjects.iterator().next(); if (!timedProjects.contains(currentProject)) { String currentProjectName = ProjectUtils.getInformation(currentProject).getDisplayName(); putValue("popupText", "Start Timer for Project: " + currentProjectName); StatusDisplayer.getDefault().setStatusText( "Current Project: " + currentProjectName); timedProjects.add(currentProject); context = currentProject; } } } @Override public void actionPerformed(ActionEvent e) { refresh(); } protected void refresh() { startTime = System.currentTimeMillis(); String formattedStartTime = formatter.format(startTime); putValue("popupText", "Timer started: " + formattedStartTime + " (" + ProjectUtils.getInformation(context).getDisplayName() + ")"); } @Override public void fileChanged(FileEvent fe) { changedTime = System.currentTimeMillis(); formatter = new SimpleDateFormat("mm:ss"); String formattedLapse = formatter.format(changedTime - startTime); putValue("popupText", "Time since last change: " + formattedLapse + " (" + ProjectUtils.getInformation(context).getDisplayName() + ")"); startTime = changedTime; } @Override public void fileFolderCreated(FileEvent fe) {} @Override public void fileDataCreated(FileEvent fe) {} @Override public void fileDeleted(FileEvent fe) {} @Override public void fileRenamed(FileRenameEvent fre) {} @Override public void fileAttributeChanged(FileAttributeEvent fae) {} } Some more work needs to be done to complete the above, i.e., for each project you somehow need to maintain the start time and last change and redisplay that whenever the user right-clicks the project.

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  • Is this a pattern? Should it be?

    - by Arkadiy
    The following is more of a statement than a question - it describes something that may be a pattern. The question is: is this a known pattern? Or, if it's not, should it be? I've had a situation where I had to iterate over two dissimilar multi-layer data structures and copy information from one to the other. Depending on particular use case, I had around eight different kinds of layers, combined in about eight different combinations: A-B-C B-C A-C D-E A-D-E and so on After a few unsuccessful attempts to factor out the repetition of per-layer iteration code, I realized that the key difficulty in this refactoring was the fact that the bottom level needed access to data gathered at higher levels. To explicitly accommodate this requirement, I introduced IterationContext class with a number of get() and set() methods for accumulating the necessary information. In the end, I had the following class structure: class Iterator { virtual void iterateOver(const Structure &dataStructure1, IterationContext &ctx) const = 0; }; class RecursingIterator : public Iterator { RecursingIterator(const Iterator &below); }; class IterateOverA : public RecursingIterator { virtual void iterateOver(const Structure &dataStructure1, IterationContext &ctx) const { // Iterate over members in dataStructure1 // locate corresponding item in dataStructure2 (passed via context) // and set it in the context // invoke the sub-iterator }; class IterateOverB : public RecursingIterator { virtual void iterateOver(const Structure &dataStructure1, IterationContext &ctx) const { // iterate over members dataStructure2 (form context) // set dataStructure2's item in the context // locate corresponding item in dataStructure2 (passed via context) // invoke the sub-iterator }; void main() { class FinalCopy : public Iterator { virtual void iterateOver(const Structure &dataStructure1, IterationContext &ctx) const { // copy data from structure 1 to structure 2 in the context, // using some data from higher levels as needed } } IterationContext ctx(dateStructure2); IterateOverA(IterateOverB(FinalCopy())).iterate(dataStructure1, ctx); } It so happens that dataStructure1 is a uniform data structure, similar to XML DOM in that respect, while dataStructure2 is a legacy data structure made of various structs and arrays. This allows me to pass dataStructure1 outside of the context for convenience. In general, either side of the iteration or both sides may be passed via context, as convenient. The key situation points are: complicated code that needs to be invoked in "layers", with multiple combinations of layer types possible at the bottom layer, the information from top layers needs to be visible. The key implementation points are: use of context class to access the data from all levels of iteration complicated iteration code encapsulated in implementation of pure virtual function two interfaces - one aware of underlying iterator, one not aware of it. use of const & to simplify the usage syntax.

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  • C# Dev Challenge Part 1 of n &ndash; Beginner Edition

    - by mbcrump
    I developed this challenge to test one’s knowledge of C Sharp. I am planning on creating several challenges with different skill sets, so don’t get mad if this challenge doesn’t well challenge you... I noticed that most people like short quizzes so this one only contains 5 questions. All of the challenges are clear and concise of what I am asking you to do. No smoke and mirrors here, meaning that none of the code has syntax errors. The purpose of this exercise is to test several OOP concepts and see how much of the C# language you really know. Question #1 – Lets start off Easy… Will the following code snippet compile successfully? What does this question test? - Can this compile without a namespace? Do you have to have an entry point of “static void Main()”? class Test { static int Main() { System.Console.WriteLine("Developer Challenge"); return 0; } } Answer (select text in box below): Yes, it will compile successfully. Question #2 – What is the value of the Console.WriteLine statements? What does this question test? – Do I understand reference types/value types? If a variable is declared with the @ symbol and its not a reserved keyword does the application compile successfully? using System; internal struct MyStruct { public int Value; } internal class MyClass { public int Value; } class Test { static void Main() { MyStruct @struct1 = new MyStruct(); MyStruct @struct2 = @struct1; @struct2.Value = 100; MyClass @ref1 = new MyClass(); MyClass @ref2 = @ref1; @ref2.Value = 100; Console.WriteLine("Value Type: {0} {1}", @struct1.Value, @struct2.Value); Console.WriteLine("Reference Type: {0} {1}", @ref1.Value, @ref2.Value); } } Answer (select text in box below): Value Type: 0 100 Reference Type: 100 100 Question #3 – What is the value of the Console.WriteLine statements? What does this question test? – Can 2 objects reference the same point in memory? using System; class Test { static void Main() { string s1 = "Testing2"; string t1 = s1; Console.WriteLine(s1 == t1); Console.WriteLine((object)s1 == (object)t1); } } Answer (select text in box below): True True Question #4 – What is the value of the Console.WriteLine statements? What does this question test? – How does the “Stack” work – LIFO or FIFO?   using System; using System.Collections; class Test { static void Main() { Stack a = new Stack(5); a.Push("1"); a.Push("2"); a.Push("3"); a.Push("4"); a.Push("5"); foreach (var o in a) { Console.WriteLine(o); } } } Answer (select text in box below): 5 4 3 2 1 Question #5 – What is the value of the Console.WriteLine statements? What does this question test? – Array and General Looping Knowledge. using System; namespace ConsoleApplication5 { class Program { static void Main(string[] args) { int[] J_LIST = new int[5] { 1, 2, 3, 4, 5 }; int K = 10; int L = 5; foreach (var J in J_LIST) { K = K - J; L = K + 2 * J; Console.WriteLine("J = {0, 5} K = {1, 5} L = {2, 5}", J, K, L); } Console.ReadLine(); } } } Answer (select text in box below): J = 1 K = 9 L = 11 J = 2 K = 7 L = 11 J = 3 K = 4 L = 10 J = 4 K = 0 L = 8 J = 5 K = -5 L = 5 Stay Tuned for more challenges!

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  • "Expecting A Different Result?" (2 of 3 in 'No Customer Left Behind' Series)

    - by Kathryn Perry
    A guest post by David Vap, Group Vice President, Oracle Applications Product Development Many companies already have some type of customer experience initiative in process or one that could be framed as such. The challenge is that the initiatives too often are started in a department silo, don't have the right level of executive sponsorship, or have been initiated without the necessary insight and strategic business alignment. You can't keep doing the same things, give it a customer experience name, and expect a different result. You can't continue to just compete on price or features - that is not sustainable in commoditized markets. And ultimately, investing in technology alone doesn't solve customer experience problems; it just adds to the complexity of them. You need a customer experience strategy and approach on how to execute a customer-centric worldview within your business. To develop this, you must take an outside in journey on how your customers are interacting with your business to establish a benchmark of your customers' experiences. Then you must get cross-functional alignment on what you are trying to achieve, near, mid, and long term. Your execution of that strategy should be based on a customer experience approach: Understand your customer: You need to capture the insights across interactions, channels (including social), and personas to better understand whom to serve, how to serve them, and when to serve them. Not all experiences or customers are equal, so leverage this insight to understand the strategic business objectives you need to address. Then determine which experiences can be improved immediately and which over time to get the result you need. Empower your ecosystem: You need to align your front-line employees with your strategy and give them the power, insight, and tools that allow them to cultivate a culture around strengthening the relationships with your customers. You also need to provide the transparency, access, and collaboration that enable your customers and partners to self serve and self solve and to share with ease. Adapt your business: You need to enable the discipline of agility within your organization and infrastructure so that you can innovate, tailor, and personalize experiences. This needs to be done both reactively from insight and proactively in real time so you can stay ahead of shifting market trends and evolving consumer behaviors. No longer will the old approaches provide the same returns. To compete, differentiate, and win in a world where the customer has the power, you must execute a strategy that is sure to deliver a better brand experience for your customers. Note: This is Part 2 in a three-part series. Part 1 is here. Stop back for Part 3 on November 28.

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  • Organization &amp; Architecture UNISA Studies &ndash; Chap 13

    - by MarkPearl
    Learning Outcomes Explain the advantages of using a large number of registers Discuss the way in which compilers optimize register usage Discuss the evolution of CISC machines Describe the characteristics of RISC architecture Discuss the RISC vs. CISC controversy Describe the way in which RISC and CISC design principles can be combined Instruction Execution Characteristics To understand the the line of reasoning of RISC advocates, we need a brief overview of instruction execution characteristics. These include… Operations Operands Procedure Calls These three sections can be studied in depth in the textbook at pages 503 - 505 A number of groups have come up with the conclusion that the attempt to make the instruction set architecture closer to HLLs (High Level Languages) is not the most effective design strategy. Rather HLL’s can be best supported by optimizing performance of the most time-consuming features of typical HLL programs. Generally 3 main characteristics came up to improve performance… Use a large number of registers or use a compiler to optimize register usage Careful attention needs to be paid to the design of instruction pipelines A simplified (reduced) instruction set is indicated The use of a large register optimization One of the most important design principles of RISC machines is the use of a large number of registers. The concept of register windows and the use of a large register file versus the use of cache memory are discussed. On the face of it, the use of a large set of registers should decrease the need to access memory. The design task is to organize the registers in such a fashion that this goal is realized. Read page 507 – 510 for a detailed explanation. Compiler-based register optimization   Reduced Instructions Set Architecture There are two advantages to smaller programs… Because the program takes up less memory, there is a savings in that resource (this was more compelling when memory was more expensive) Smaller programs should improve performance, and this will happen in two ways – fewer instructions means fewer instruction bytes to be fetched and in a paging environment smaller programs occupy fewer pages, reducing page faults. Certain characteristics are common to RISC processors… One instruction per cycle Register-to-register operations Simple addressing modes Simple instruction formats RISC vs. CISC After initial enthusiasm for RISC machines, there has been a growing realization that RISC designs may benefit from the inclusion of some CISC features CISC designs may benefit from the inclusion of some RISC features

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  • Finding Tools Guidance in OUM

    - by user716869
    OUM is not tool – specific. However, it does include tool guidance.  Tool guidance in OUM includes: a mention of a tool that could be used to complete a specific task(s) templates created with a specific tool example work products in a specific tool links to tool resources Tool Supplemental Guides So how do you find all this helpful tool information? Start at the lowest level first – the Task Overview.  Even though the task overviews are written tool-agnostic, they sometimes mention suggestions, or examples of a tool that might be used to complete the task.  More specific tool information can be found in the Task Overview, Templates and Tools section.  In some cases, the tool used to create the template (for example, Microsoft Word, Powerpoint, Project and Visio) is useful. The Templates and Tools section also provides more specific tool guidance, such as links to: White Papers Viewlets Example Work Products Additional Resources Tool Supplemental Guides If you’re more interested in seeing what tools might be helpful in general for your project or to see if there is any tool guidance for a specific tool that your project is committed to using, go to the Supplemental Guidance page in OUM.  This page is available from the Method Navigation pull down located in the header of almost every OUM page. When you open the Supplemental Guidance page, the first thing you see is a table index of everything that is included on the page.  At the top of the right column are all the Tool Supplemental Guides available in OUM.  Use the index to navigate to any of the guides. Next in the right column is Discipline/Industry/View Resources and Samples.  Use the index to navigate to any of these topics and see what’s available and more specifically, if there is any tool guidance available.  For example, if you navigate to the Cloud Resources, you will find a link to the IT Strategies from Oracle page that provides information for Cloud Practitioner Guides, Cloud Reference Architectures and Cloud White Papers, including the Cloud Candidate Selection Tool and Cloud Computing Maturity Model. The section for Method Tool and Technique Cross References can take you to the Task to Tool Cross Reference.  This page provides a task listing with possible helpful tools and links to more information regarding the tools.  By no means is this tool guidance all inclusive.  You can use other tools not mentioned in OUM to complete an OUM task. The Method Tool and Technique Cross References can also take you to the various Technique pages (Index and Cross References).  While techniques are not necessarily “tools,” they can certainly provide valuable assistance in completing tasks. In the Other Resources section of the Supplemental Guidance page, you find links to the viewlets and white papers that are included within OUM.

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  • Operation times out trying to SSH outside LAN i.e. from internet to LAN no connection is established

    - by Pelle L
    I run Ubuntu 12.04 and have no success connecting with SSH from "Internet". The router is a TL-MR3420 which is set up to forward requests to one of the NIC's on ubuntu machine (which has in total 3 NICs). I can SSH from a client on the "local" network/LAN. The forward mechanism in the router seems to work. If I stop SSH service on the Ubuntu machine and instead start one on the windows machine - it works like a charm. I do not use the Std port 22 but that shouldn't be an issue as far as I understand - sine it works on the same port on the win machine. Since my public IS isn't static I use a dynDNS service but as said earlier the same setup works from the win machine. The router is located on 192.168.0.1 The Ubuntu NICs has the following IP: eth2 192.168.0.100 , eth1 192.168.0.101 , eth0 192.168.0.102 and I have forwarded the "outside" request to 192.168.0.100 In regards for firewall settings on the Ubuntu machine I have disabled the ufw and the command ufw status give status: inactive. I don't now it this is relevant information but teh command iptables --list give: Chain INPUT (policy ACCEPT) target prot opt source destination Chain FORWARD (policy ACCEPT) target prot opt source destination Chain OUTPUT (policy ACCEPT) target prot opt source destination I have tried to catch traffic with help of wireshark (a tool I'm not too used to use) and it seems as a few (3?) "requests" actually reaches the NIC but ... nothing happens. The syslog does not show any entries during these attempts. Perhaps it could be some routing issues but I have reached my level of competence and are stuck ... all help and support to get this sorted out is much appreciated. I'm new to Linux so please do not assume I have a configuration that is correct - but as I wrote earlier - if the client that initiate SSH is on the LAN it all works. PS:I have also tried to get VPN (PPP) working from Internet with no success - once again VPN works on the windows machine ... so my best guess is that this is related to how the ubuntu machine handles (IP) traffic and not the TL-MR3420 router or other network issues.

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  • Are there any good Java/JVM libraries for my Expression Tree architecture?

    - by Snuggy
    My team and I are developing an enterprise-level application and I have devised an architecture for it that's best described as an "Expression Tree". The basic idea is that the leaf nodes of the tree are very simple expressions (perhaps simple values or strings). Nodes closer to the trunk will get more and more complex, taking the simpler nodes as their inputs and returning more complex results for their parents. Looking at it the other way, the application performs some task, and for this it creates a root expression. The root expression divides its input into smaller units and creates child expressions, which when evaluated it can use to build it's own result. The subdividing process continues until the simplest leaf nodes. There are two very important aspects of this architecture: It must be possible to manipulate nodes of the tree after it is built. The nodes may be given new input values to work with and any change in result for that node needs to be propagated back up the tree to the root node. The application must make best use of available processors and ultimately be scalable to other computers in a grid or in the cloud. Nodes in the tree will often be updating concurrently and notifying other interested nodes in the tree when they get a new value. Unfortunately, I'm not at liberty to discuss my actual application, but to aid understanding a little bit, you might imagine a kind of spreadsheet application being implemented with a similar architecture, where changes to cells in the table are propagated all over the place to other cells that need the result. The spreadsheet could get so massive that applying multi-core multi-computer distributed system to solve it would be of benefit. I've got my prototype "Expression Engine" working nicely on a single multi-core PC but I've started to run into a few concurrency issues (as expected because I haven't been taking too much care so far) so it's now time to start thinking about migrating the Engine to a more robust library, and that leads to a number of related questions: Is there any precedent for my "Expression Tree" architecture that I could research? What programming concepts should I consider. I realise this approach has many similarities to a functional programming style, and I'm already aware of the concepts of using futures and actors. Are there any others? Are there any languages or libraries that I should study? This question is inspired by my accidental discovery of Scala and the Akka library (which has good support for Actors, Futures, Distributed workloads etc.) and I'm wondering if there is anything else I should be looking at as well?

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  • is a factory pattern to prevent multuple instances for same object (instance that is Equal) good design?

    - by dsollen
    I have a number of objects storing state. There are essentially two types of fields. The ones that uniquly define what the object is (what node, what edge etc), and the oens that store state describing how these things are connected (this node is connected to these edges, this edge is part of these paths) etc. My model is updating the state variables using package methdos, so these objects all act as immutable to anyone not in Model scope. All Objects extend one base type. I've toyed with the idea of a Factory approch which accepts a Builder object and construct the applicable object. However, if an instance of the object already exists (ie would return true if I created the object defined by the builder and passed it to the equal method for the existing instance) the factory returns the current object instead of creating a new instance. Because the Equal method would only compare what uniquly defines the type of object (this is node A nto node B) but won't check the dynamic state stuff (node A is currently connected to nodes C and E) this would be a way of ensuring anyone that wants my Node A automatically knows it's state connections. More importantly it would prevent aliasing nightmares of someone trying to pass an instance of node A with different state then the node A in my model has. I've never heard of this pattern before, and it's a bit odd. I would have to do some overiding of serlization methods to make it work (ensure when I read in a serilized object I add it to my facotry list of known instances, and/or return an existing factory in it's place), as well as using a weakHashMap as if it was a weakHashSet to know rather an instance exists without worrying about a quasi-memory leak occuring. I don't know if this is too confusing or prone to it's own obscure bugs. One thing I know is that plugins interface with lowest level hardware. The plugins have to be able to return state taht is different then my memory; to tell my memory when it's own state is inconsistent. I believe this is possible despit their fetching objects that exist in my memory; we allow building of objects without checking their consistency with the model until the addToModel is called anyways; and the existing plugins design was written before all this extra state existed and worked fine without ever being aware of it. Should I just be using some other design to avoid this crazyness? (I have another question to that affect I'm posting).

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