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  • Does *every* project benefit from written specifications?

    - by nikie
    I know this is holy war territory, so please read the question to the end before answering. There are many cases where written specifications make a lot of sense. For example, if you're a contractor and you want to get paid, you need written specs. If you're working in a team with 20 persons, you need written specs. If you're writing a programming language compiler or interpreter (and it's not perl), you'll usually write a formal specification. I don't doubt that there are many more cases where written specifications are a really good idea. I just think that there are cases where there's so little benefit in written specs, that it doesn't outweigh the costs of writing and maintaining them. EDIT: The close votes say that "it is difficult to say what is asked here", so let me clarify: The usefulness of written, detailed specifications is often claimed like a dogma. (If you want examples, look at the comments.) But I don't see the use of them for the kind of development I'm doing. So what is asked here is: How would written specifications help me? Background information: I work for a small company that's developing vertical market software. If our product is easier to use and has better performance than the competition, it sells. If it's harder to use, even if it behaves 100% as the specification says, it doesn't sell. So there are no "external forces" for having written specs. The advantage would have to be somewhere in the development process. Now, I can see how frozen specifications would make a developer's life easier. But we'll never have frozen specs. If we see in the middle of development that feature X is not intuitive to use the way it's specified, then we can only choose between changing the specification or developing a product that won't sell. You'll probably ask by now: How do you know when you're done? Well, we're continually improving our product. The competition does the same. So (hopefully) we're never done. We keep improving the software, and when we reach a point when the benefits of the improvements we've added since the last release outweigh the costs of an update, we create a new release that is then tested, localized, documented and deployed. This also means that there's rarely any schedule pressure. Nobody has to do overtime to make a deadline. If the feature isn't done by the time we want to release the next version, it'll simply go into the next version. The next question might be: How do your developers know what they're supposed to implement? The answer is: They have a lot of domain knowledge. They know the customers business well enough, so a high-level description of the feature (or even just the problem that the customer needs solved) is enough to implement it. If it's not clear, the developer creates a few fake screens to get feedback from marketing/management or customers, but this is nowhere near the level of detail of actual specifications. This might be inefficient for larger teams, but for a small team with low turnover it works quite well. It has the additional benefit that the developer in question often comes up with a better solution than the person writing the specs might have. This question is already getting very long, but let me address one last point: Testing. Like I said in the beginning, if our software behaves 100% like the spec says, it still can be crap. In fact, if it's so unintuitive that you need a spec to know how to test it, it probably is crap. It makes sense to have fixed, written tests for some core functionality and for regression bugs, but again, this is nowhere near a full written spec of how the software should behave when. The main test is: hand the software to a user who doesn't know it yet and tell him to use the new feature X. If she can figure out how to use it and it works, it works.

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  • Cannot get ATI Drivers installed

    - by bittoast67
    I am trying to install the Catalyst driver. The best I can get is a strange resolution problem and firefox acts all wonkt. The worst I have gotten is low graphics mode in which I just reinstall Ubuntu. I have a HP Pavilion Dv7 laptop. With Radeon 3200 HD. I plan to try again with a fresh install of Ubuntu 12.4.3 as I have heard its the most compatible. This is what I have done: I have tried just the easy way of going to synaptic and installing the drivers that way. the fglrx package (not the fglrx update). And if memory serves I think that boots me into low graphics mode. So, fresh install of Ubuntu and tried again. I have done everything a couple times from this site (http://wiki.cchtml.com/index.php/Ubuntu_Precise_Installation_Guide) following every instruction to a T. That gets me something, such as a lowered fan speed and a much cooler computer, but I also lose most of my resolution. And displays says its the best resolution I can get. I also have a very screwy firefox. Using this method I can see AMD Catalyst Control Center in my dash (two of them really one administrator and one not) but when I try to open it it says no amd driver detected. So again, ubuntu reinstall. I have tried the GUI method from the Legacy driver I got from AMD's site. It runs through smoothly and at the very end after I exit the installer it gives me an error. I have also tried various other methods using terminal, as well as various different drivers (the one from the amd's site and the one suggested in the above link for my graphics card) both to no avail. When I try the method in the link on number 2, and I get the super low res and screwy fire fox. I type in, fglrxinfo ,and get a badrequest error. I have yet to type in fglrxinfo and get anything like what I am supposed to. UPDATE: I am now currently reinstalling Ubuntu 12.4. I tried the above mentioned link - thank you very much!- just to see on the previously failed driver attempt by following the purge commands. And to no avail when typing fglrxinfo I still get the badrequest thing. I will update again after a try with a true fresh install. Thanks again!! UPDATE: Alright everyone. Still no go. I have done everything word per word in the provided tutorial. I have rebooted my computer again to a fucked up resolution and this is what I get when typing fglrxinfo: $ fglrxinfo X Error of failed request: BadRequest (invalid request code or no such operation) Major opcode of failed request: 153 (GLX) Minor opcode of failed request: 19 (X_GLXQueryServerString) Serial number of failed request: 12 Current serial number in output stream: 12 I would like to add that when installing this file: fglrx_8.970-0ubuntu1_amd64.deb I got this: Building initial module for 3.8.0-29-generic Error! Bad return status for module build on kernel: 3.8.0-29-generic (x86_64) Consult /var/lib/dkms/fglrx/8.970/build/make.log for more information. update-initramfs: deferring update (trigger activated) Processing triggers for ureadahead ... Processing triggers for bamfdaemon ... Rebuilding /usr/share/applications/bamf.index... Processing triggers for initramfs-tools ... update-initramfs: Generating /boot/initrd.img-3.8.0-29-generic Processing triggers for libc-bin ... ldconfig deferred processing now taking place Any ideas? Anyone? I cant for the life of me figure out what I am doing wrong.

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  • College Ratings via the Federal Government

    - by user9147039
    A few weeks back you might remember news about a higher education rating system proposal from the Obama administration. As I've discussed previously, political and stakeholder pressures to improve outcomes and increase transparency are stronger than ever before. The executive branch proposal is intended to make progress in this area. Quoting from the proposal itself, "The ratings will be based upon such measures as: Access, such as percentage of students receiving Pell grants; Affordability, such as average tuition, scholarships, and loan debt; and Outcomes, such as graduation and transfer rates, graduate earnings, and advanced degrees of college graduates.” This is going to be quite complex, to say the least. Most notably, higher ed is not monolithic. From community and other 2-year colleges, to small private 4-year, to professional schools, to large public research institutions…the many walks of higher ed life are, well, many. Designing a ratings system that doesn't wind up with lots of unintended consequences and collateral damage will be difficult. At best you would end up potentially tarnishing the reputation of certain institutions that were actually performing well against the metrics and outcome measures that make sense in their "context" of education. At worst you could spend a lot of time and resources designing a system that would lose credibility with its "customers". A lot of institutions I work with already have in place systems like the one described above. They are tracking completion rates, completion timeframes, transfers to other institutions, job placement, and salary information. As I talk to these institutions there are several constants worth noting: • Deciding on which metrics to measure is complicated. While employment and salary data are relatively easy to track, qualitative measures are more difficult. How do you quantify the benefit to someone who studies in one field that may not compensate him or her as well as another field but that provides huge personal fulfillment and reward is a difficult measure to quantify? • The data is available but the systems to transform the data into actual information that can be used in meaningful ways are not. Too often in higher ed information is siloed. As such, much of the data that need to be a part of a comprehensive system sit in multiple organizations, oftentimes outside the reach of core IT. • Politics and culture are big barriers. One of the areas that my team and I spend a lot of time talking about with higher ed institutions all over the world is the imperative to optimize for student success. This, like the tracking of the students’ achievement after graduation, requires a level or organizational capacity that does not currently exist. The primary barrier is the culture of "data islands" in higher ed, and the need for leadership to drive out the divisions between departments, schools, colleges, etc. and institute academy-wide analytics and data stewardship initiatives that will enable student success. • Data quality is a very big issue. So many disparate systems exist (some on premise, some "in the cloud") that keep data about "persons" using different means to identify them. Establishing a single source of truth about an individual and his or her data is difficult without some type of data quality policy and tools. Good tools actually exist but are seldom leveraged. Don't misunderstand - I think it's a great idea to drive additional transparency and accountability into the system of higher education. And not just at home, but globally. Students and parents need access to key data to make informed, responsible choices. The tools exist to not only enable this kind of information to be shared but to capture the very metrics stakeholders care most about and in a way that makes sense in the context of a given institution's "place" in the overall higher ed panoply.

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  • Application Logging needs work

    Application Logging Application logging is the act of logging events that occur within an application much like how a court report documents what happens in court case. Application logs can be useful for several reasons, but the most common use for logs is to recreate steps to find the root cause of applications errors. Other uses can include the detection of Fraud, verification of user activity, or provide audits on user/data interactions. “Logs can contain different kinds of data. The selection of the data used is normally affected by the motivation leading to the logging. “ (OWASP, 2009) OWASP also stats that logging include applicable debugging information like the event date time, responsible process, and a description of the event. “There are many reasons why a logging system is a necessary part of delivering a distributed application. One of the most important is the ability to track exactly how many users are using the application during different time periods.” (Hatton, 2000) Hatton also states that application logging helps system designers determine whether parts of an application aren't being used as designed. He implies that low usage can be used to identify if users like or do not like aspects of a system based on user usage of the application. This enables application designers to extract why users don't like aspects of an application so that changes can be made to increase its usefulness and effectiveness. “Logging memory usage can also assist you in tuning up the internals of your application. If you're experiencing a randomly occurring problem, being able to match activities performed with the memory status at the time may enable you to discover the cause of the problem. It also gives you a good indication of the health of the distributed server machine at the time any activity is performed. “ (Hatton, 2000) Commonly Logged Application Events (Defined by OWASP) Access of Data Creation of Data Modification of Data in any form Administrative Functions  Configuration Changes Debugging Information(Application Events)  Authorization Attempts  Data Deletion Network Communication  Authentication Events  Errors/Exceptions Application Error Logging The functionality associated with application error logging is actually the combination of proper error handling and applications logging.  If we look back at Figure 4 and Figure 5, these code examples allow developers to handle various types of errors that occur within the life cycle of an application’s execution. Application logging can be applied within the Catch section of the TryCatch statement allowing for the errors to be logged when they occur. By placing the logging within the Catch section specific error details can be accessed that help identify the source of the error, the path to the error, what caused the error and definition of the error that occurred. This can then be logged and reviewed at a later date in order recreate the error that was received based data found in the application log. By allowing applications to log errors developers IT staff can use them to recreate errors that are encountered by end-users or other dependent systems.

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  • Delegates: A Practical Understanding

    - by samerpaul
    It's been a while since I have written on this blog, and I'm planning on reviving it this summer, since I have more time to do so again.I've also recently started working on the iPhone platform, so I haven't been as busy in .NET as before.In either case, today's blog post applies to both C# and Objective-C, because it's more about a practical understanding of delegates than it is about code. When I was learning coding, I felt like delegates was one of the hardest things to conceptually understand, and a lot of books don't really do a good job (in my opinion) of explaining it. So here's my stab at it.A Real Life Example of DelegatesLet's say there are three of you. You, your friend, and your brother. You're each in a different room in your house so you can't hear each other, even if you shout. 1)You are playing a computer game2) Friend is building a puzzle3) Brother is nappingNow, you three are going to stay in your room but you want to be informed if anything interesting is happening to the one of you. Let's say you (playing the computer game) want to know when your brother wakes up.You could keep walking to the room, checking to see if he's napping, and then walking back to your room. But that would waste a lot of time / resources, and what if you miss when he's awake before he goes back to sleep? That would be bad.Instead, you hand him a 2-way radio that works between your room and his room. And you inform him that when he wakes up, he should press a button on the radio and say "I'm awake". You are going to be listening to that radio, waiting for him to say he's awake. This, in essence, is how a delegate works.You're creating an "object" (the radio) that allows you to listen in on an event you specify. You don't want him to send any other messages to you right now, except when he wakes up. And you want to know immediately when he does, so you can go over to his room and say hi. (the methods that are called when a delegate event fires). You're also currently specifying that only you are listening on his radio.Let's say you want your friend to come into the room at the same time as you, and do something else entirely, like fluff your brother's pillow. You will then give him an identical radio, that also hooks into your brother's radio, and inform him to wait and listen for the "i'm awake" signal.Then, when your brother wakes up, he says "I'm awake!" and both you and your friend walk into the room. You say hi, and your friend fluffs the pillow, then you both exit.Later, if you decide you don't care to say hi anymore, you turn off your radio. Now, you have no idea when your brother is awake or not, because you aren't listening anymore.So again, you are each classes in this example, and each of you have your own methods. You're playing a computer game (PlayComputerGame()), your friend is building a puzzle (BuildPuzzle()) and your brother is napping (Napping()). You create a delegate (ImAwake) that you set your brother to do, when he wakes up. You listen in on that delegate (giving yourself a radio and turning it on), and when you receive the message, you fire a new method called SayHi()). Your friend is also wired up to the same delegate (using an identical radio) and fires the method FluffPillow().Hopefully this makes sense, and helps shed some light on how delegates operate. Let me know! Feel free to drop me a line at Twitter (preferred method of contact) here: samerabousalbi

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  • Getting 2D Platformer entity collision Response Correct (side-to-side + jumping/landing on heads)

    - by jbrennan
    I've been working on a 2D (tile based) 2D platformer for iOS and I've got basic entity collision detection working, but there's just something not right about it and I can't quite figure out how to solve it. There are 2 forms of collision between player entities as I can tell, either the two players (human controlled) are hitting each other side-to-side (i. e. pushing against one another), or one player has jumped on the head of the other player (naturally, if I wanted to expand this to player vs enemy, the effects would be different, but the types of collisions would be identical, just the reaction should be a little different). In my code I believe I've got the side-to-side code working: If two entities press against one another, then they are both moved back on either side of the intersection rectangle so that they are just pushing on each other. I also have the "landed on the other player's head" part working. The real problem is, if the two players are currently pushing up against each other, and one player jumps, then at one point as they're jumping, the height-difference threshold that counts as a "land on head" is passed and then it registers as a jump. As a life-long player of 2D Mario Bros style games, this feels incorrect to me, but I can't quite figure out how to solve it. My code: (it's really Objective-C but I've put it in pseudo C-style code just to be simpler for non ObjC readers) void checkCollisions() { // For each entity in the scene, compare it with all other entities (but not with one it's already compared against) for (int i = 0; i < _allGameObjects.count(); i++) { // GameObject is an Entity GEGameObject *firstGameObject = _allGameObjects.objectAtIndex(i); // Don't check against yourself or any previous entity for (int j = i+1; j < _allGameObjects.count(); j++) { GEGameObject *secondGameObject = _allGameObjects.objectAtIndex(j); // Get the collision bounds for both entities, then see if they intersect // CGRect is a C-struct with an origin Point (x, y) and a Size (w, h) CGRect firstRect = firstGameObject.collisionBounds(); CGRect secondRect = secondGameObject.collisionBounds(); // Collision of any sort if (CGRectIntersectsRect(firstRect, secondRect)) { //////////////////////////////// // // // Check for jumping first (???) // // //////////////////////////////// if (firstRect.origin.y > (secondRect.origin.y + (secondRect.size.height * 0.7))) { // the top entity could be pretty far down/in to the bottom entity.... firstGameObject.didLandOnEntity(secondGameObject); } else if (secondRect.origin.y > (firstRect.origin.y + (firstRect.size.height * 0.7))) { // second entity was actually on top.... secondGameObject.didLandOnEntity.(firstGameObject); } else if (firstRect.origin.x > secondRect.origin.x && firstRect.origin.x < (secondRect.origin.x + secondRect.size.width)) { // Hit from the RIGHT CGRect intersection = CGRectIntersection(firstRect, secondRect); // The NUDGE just offsets either object back to the left or right // After the nudging, they are exactly pressing against each other with no intersection firstGameObject.nudgeToRightOfIntersection(intersection); secondGameObject.nudgeToLeftOfIntersection(intersection); } else if ((firstRect.origin.x + firstRect.size.width) > secondRect.origin.x) { // hit from the LEFT CGRect intersection = CGRectIntersection(firstRect, secondRect); secondGameObject.nudgeToRightOfIntersection(intersection); firstGameObject.nudgeToLeftOfIntersection(intersection); } } } } } I think my collision detection code is pretty close, but obviously I'm doing something a little wrong. I really think it's to do with the way my jumps are checked (I wanted to make sure that a jump could happen from an angle (instead of if the falling player had been at a right angle to the player below). Can someone please help me here? I haven't been able to find many resources on how to do this properly (and thinking like a game developer is new for me). Thanks in advance!

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  • Rethinking Oracle Optimizer Statistics for P6 Part 2

    - by Brian Diehl
    In the previous post (Part 1), I tried to draw some key insights about the relationship between P6 and Oracle Optimizer Statistics.  The first is that average cardinality has the greatest impact on query optimization and that the particular queries generated by P6 are more likely to use this average during calculations. The second is that these are statistics that are unlikely to change greatly over the life of the application. Ultimately, our goal is to get the best query optimization possible.  Or is it? Stability No application administrator wants to get the call at 9am that their application users cannot get there work done because everything is running slow. This is a possibility with a regularly scheduled nightly collection of statistics. It may not just be slow performance, but a complete loss of service because one or more queries are optimized poorly. Ideally, this should not be the case. The database optimizer should make better decisions with more up-to-date data. Better statistics may give incremental performance benefit. However, this benefit must be balanced against the potential cost of system down time.  It is stability that we ultimately desire and not absolute optimal performance. We do want the benefit from more accurate statistics and better query plans, but not at the risk of an unusable system. As a result, I've developed the following methodology around managing database statistics for the P6 database.  1. No Automatic Re-Gathering - The daily, weekly, or other interval of statistic gathering is unlikely to be beneficial. Quite the opposite. It is more likely to cause problems. 2. Smart Re-Gathering - The time to collect statistics is when things have changed significantly. For a new installation of P6, this is happening more often because the data is growing from a few rows to thousands and more. But for a mature system, the data is not changing significantly from week-to-week. There are times to collect statistics: New releases of the application Changes in the underlying hardware or software versions (ex. new Oracle RDBMS version) When additional user groups are added. The new groups may use the software in significantly different ways. After significant changes in the data. This may be monthly, quarterly or yearly.  3. Always Test - If you take away one thing from this post, it would be to always have a plan to test after changing statistics. In reality, statistics can be collected as often as you desire provided there are tests in place to verify that performance is the same or better. These might be automated tests or simply a manual script of application functions. 4. Have a Way Out - Never change the statistics without a way to return to the previous set. Think of the statistics as one part of the overall application code that also includes the source code--both application and RDBMS. It would be foolish to change to the new code without a way to get back to the previous version. In the final post, I will talk about the actual script I created for P6 PMDB and possible future direction for managing query performance. 

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  • Webcast On-Demand: Building Java EE Apps That Scale

    - by jeckels
    With some awesome work by one of our architects, Randy Stafford, we recently completed a webcast on scaling Java EE apps efficiently. Did you miss it? No problem. We have a replay available on-demand for you. Just hit the '+' sign drop-down for access.Topics include: Domain object caching Service response caching Session state caching JSR-107 HotCache and more! Further, we had several interesting questions asked by our audience, and we thought we'd share a sampling of those here for you - just in case you had the same queries yourself. Enjoy! What is the largest Coherence deployment out there? We have seen deployments with over 500 JVMs in the Coherence cluster, and deployments with over 1000 JVMs using the Coherence jar file, in one system. On the management side there is an ecosystem of monitoring tools from Oracle and third parties with dashboards graphing values from Coherence's JMX instrumentation. For lifecycle management we have seen a lot of custom scripting over the years, but we've also integrated closely with WebLogic to leverage its management ecosystem for deploying Coherence-based applications and managing process life cycles. That integration introduces a new Java EE archive type, the Grid Archive or GAR, which embeds in an EAR and can be seen by a WAR in WebLogic. That integration also doesn't require any extra WebLogic licensing if Coherence is licensed. How is Coherence different from a NoSQL Database like MongoDB? Coherence can be considered a NoSQL technology. It pre-dates the NoSQL movement, having been first released in 2001 whereas the term "NoSQL" was coined in 2009. Coherence has a key-value data model primarily but can also be used for document data models. Coherence manages data in memory currently, though disk persistence is in a future release currently in beta testing. Where the data is managed yields a few differences from the most well-known NoSQL products: access latency is faster with Coherence, though well-known NoSQL databases can manage more data. Coherence also has features that well-known NoSQL database lack, such as grid computing, eventing, and data source integration. Finally Coherence has had 15 years of maturation and hardening from usage in mission-critical systems across a variety of industries, particularly financial services. Can I use Coherence for local caching? Yes, you get additional features beyond just a java.util.Map: you get expiration capabilities, size-limitation capabilities, eventing capabilites, etc. Are there APIs available for GoldenGate HotCache? It's mostly a black box. You configure it, and it just puts objects into your caches. However you can treat it as a glass box, and use Coherence event interceptors to enhance its behavior - and there are use cases for that. Are Coherence caches updated transactionally? Coherence provides several mechanisms for concurrency control. If a project insists on full-blown JTA / XA distributed transactions, Coherence caches can participate as resources. But nobody does that because it's a performance and scalability anti-pattern. At finer granularity, Coherence guarantees strict ordering of all operations (reads and writes) against a single cache key if the operations are done using Coherence's "EntryProcessor" feature. And Coherence has a unique feature called "partition-level transactions" which guarantees atomic writes of multiple cache entries (even in different caches) without requiring JTA / XA distributed transaction semantics.

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  • Compress/Decompress NSString in objective-c (iphone) using GZIP or deflate

    - by Steven
    Hi, I have a web-service running on Windows Azure which returns JSON that I consume in my iPhone app. Unfortunately, Windows Azure doesn't seem to support the compression of dynamic responses yet (long story) so I decided to get around it by returning an uncompressed JSON package, which contains a compressed (using GZIP) string. e.g {"Error":null,"IsCompressed":true,"Success":true,"Value":"vWsAAB+LCAAAAAAAB..etc.."} ... where value is the compressed string of a complex object represented in JSON. This was really easy to implement on the server, but for the life of me I can't figure out how to decompress a gzipped NSString into an uncompressed NSString, all the examples I can find for zlib etc are dealing with files etc. Can anyone give me any clues on how to do this? (I'd also be happy for a solution that used deflate as I could change the server-side implementation to use deflate too). Thanks!! Steven Edit 1: Aaah, I see that ASIHTTPRequest is using the following function in it's source code: //uncompress gzipped data with zlib + (NSData *)uncompressZippedData:(NSData*)compressedData; ... and I'm aware that I can convert NSString to NSData, so I'll see if this leads me anywhere!

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  • Tutorials and libraries for OpenGL-ES games on Android

    - by user197141
    What tutorials and libraries are available which can help beginners to develop 2D and 3D games on Android using OpenGL-ES? I'm looking for tutorials which can help me learn OpenGL-ES, and I'm looking for OpenGL-ES libraries which can make life easier for beginners in OpenGL-ES. Since Android is still small, I guess it may be help-full to read iPhone OpenGL-ES tutorials as well, as I suppose the OpenGL-ES functionality is much the same. I have found the following useful information which I would have liked to share: Android tutorials: Basic tutorial covering polygons, no textures anddev forum with some tutorials Other Android OpenGL-ES information: Google IO lecture regarding games, not much OpenGLES The The Khronos Reference Manual is also relevant to have, but its not exactly the best place to start. iPhone OpenGL-ES tutorials (where the OpenGl-ES information is probably useful): http://web.me.com/smaurice/AppleCoder/iPhone_OpenGL/Archive.html http://iphonedevelopment.blogspot.com/2009/05/opengl-es-from-ground-up-table-of.html As for libraries which a beginner might use to get a simpler hands-on experience with OpenGL-ES, I have only found Rokon, which is recently started, thus has many holes and bugs. And it's gnuGPL licensed (at the moment) which means it cannot be used, if we wish to sell our games. What else is out there?

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  • iPhone Inspiration Stories...

    - by Luis Tovar
    So we have all heard of these overnight millionaires in the app store. We know it would be great, but somewhat unlikely to do ourselves. What I do know is, that learning and developing for the iPhone can sometimes be overwhelming. I continue to push on and learn more and more, even when my brain just cant take anymore I turn my mac on and read up on how to do new and different things I haven't done yet in my app yet. I would like to see a few post's of a common day developer's story and how their life has improved now that they are sitting up on the golden pedestal of an iphone developer. I look at these Dice.com jobs on think how nice it would be to be making that kind of money offered for an experienced iphone developer. Im on my way... and while I'm on that road i'd like to look over and see your story... Please include how you got into iPhone development and any apps you have out there and your success with them. Care to share?

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  • winforms databinding best practices

    - by Kaiser Soze
    Demands / problems: I would like to bind multiple properties of an entity to controls in a form. Some of which are read only from time to time (according to business logic). When using an entity that implements INotifyPropertyChanged as the DataSource, every change notification refreshes all the controls bound to that data source (easy to verify - just bind two properties to two controls and invoke a change notification on one of them, you will see that both properties are hit and reevaluated). There should be user friendly error notifications (the entity implements IDataErrorInfo). (probably using ErrorProvider) Using the entity as the DataSource of the controls leads to performance issues and makes life harder when its time for a control to be read only. I thought of creating some kind of wrapper that holds the entity and a specific property so that each control would be bound to a different DataSource. Moreover, that wrapper could hold the ReadOnly indicator for that property so the control would be bound directly to that value. The wrapper could look like this: interface IPropertyWrapper : INotifyPropertyChanged, IDataErrorInfo { object Value { get; set; } bool IsReadOnly { get; } } But this means also a different ErrorProvider for each property (property wrapper) I feel like I'm trying to reinvent the wheel... What is the 'proper' way of handling complex binding demands like these? Thanks ahead.

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  • Adding array of images to Firebase using AngularFire

    - by user2833143
    I'm trying to allow users to upload images and then store the images, base64 encoded, in firebase. I'm trying to make my firebase structured as follows: |--Feed |----Feed Item |------username |------epic |---------name,etc. |------images |---------image1, image 2, etc. However, I can't get the remote data in firebase to mirror the local data in the client. When I print the array of images to the console in the client, it shows that the uploaded images have been added to the array of images...but these images never make it to firebase. I've tried doing this multiple ways to no avail. I tried using implicit syncing, explicit syncing, and a mixture of both. I can;t for the life of me figure out why this isn;t working and I'm getting pretty frustrated. Here's my code: $scope.complete = function(epicName){ for (var i = 0; i < $scope.activeEpics.length; i++){ if($scope.activeEpics[i].id === epicName){ var epicToAdd = $scope.activeEpics[i]; } } var epicToAddToFeed = {epic: epicToAdd, username: $scope.currUser.username, userImage: $scope.currUser.image, props:0, images:['empty']}; //connect to feed data var feedUrl = "https://epicly.firebaseio.com/feed"; $scope.feed = angularFireCollection(new Firebase(feedUrl)); //add epic var added = $scope.feed.add(epicToAddToFeed).name(); //connect to added epic in firebase var addedUrl = "https://epicly.firebaseio.com/feed/" + added; var addedRef = new Firebase(addedUrl); angularFire(addedRef, $scope, 'added').then(function(){ // for each image uploaded, add image to the added epic's array of images for (var i = 0, f; f = $scope.files[i]; i++) { var reader = new FileReader(); reader.onload = (function(theFile) { return function(e) { var filePayload = e.target.result; $scope.added.images.push(filePayload); }; })(f); reader.readAsDataURL(f); } }); } EDIT: Figured it out, had to connect to "https://epicly.firebaseio.com/feed/" + added + "/images"

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  • How do I filter out NaN FLOAT values in Teradata SQL?

    - by Paul Hooper
    With the Teradata database, it is possible to load values of NaN, -Inf, and +Inf into FLOAT columns through Java. Unfortunately, once those values get into the tables, they make life difficult when writing SQL that needs to filter them out. There is no IsNaN() function, nor can you "CAST ('NaN' as FLOAT)" and use an equality comparison. What I would like to do is, SELECT SUM(VAL**2) FROM DTM WHERE NOT ABS(VAL) > 1e+21 AND NOT VAL = CAST ('NaN' AS FLOAT) but that fails with error 2620, "The format or data contains a bad character.", specifically on the CAST. I've tried simply "... AND NOT VAL = 'NaN'", which also fails for a similar reason (3535, "A character string failed conversion to a numeric value."). I cannot seem to figure out how to represent NaN within the SQL statement. Even if I could represent NaN successfully in an SQL statement, I would be concerned that the comparison would fail. According to the IEEE 754 spec, NaN = NaN should evaluate to false. What I really seem to need is an IsNaN() function. Yet that function does not seem to exist.

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  • Algorithm design, "randomising" timetable schedule in Python although open to other languages.

    - by S1syphus
    Before I start I should add I am a musician and not a native programmer, this was undertook to make my life easier. Here is the situation, at work I'm given a new csv file each which contains a list of sound files, their length, and the minimum total amount of time they must be played. I create a playlist of exactly 60 minutes, from this excel file. Each sample played the by the minimum number of instances, but spread out from each other; so there will never be a period where for where one sound is played twice in a row or in close proximity to itself. Secondly, if the minimum instances of each song has been used, and there is still time with in the 60 min, it needs to fill the remaining time using sounds till 60 minutes is reached, while adhering to above. The smallest duration possible is 15 seconds, and then multiples of 15 seconds. Here is what I came up with in python and the problems I'm having with it, and as one user said its buggy due to the random library used in it. So I'm guessing a total rethink is on the table, here is where I need your help. Whats is the best way to solve the issue, I have had a brief look at things like knapsack and bin packing algorithms, while both are relevant neither are appropriate and maybe a bit beyond me.

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  • NSString variable out of scope in sub-class (iPhone/Obj-C)

    - by Rich
    I am following along with an example in a book with the code exactly as it is in the example code as well as from the book, and I'm getting an error at runtime. I'll try to describe the life cycle of this variable as good as I can. I have a controller class with a nested array that is populated with string literals (NSArray of NSArrays, the nested NSArrays initialized with arrayWithObjects: where the objects are all string literals - @"some string"). I access these strings with a helper method added via a category on NSArray (to pull strings out of a nested array). My controller gets a reference to this string and assigns it to a NSString property on a child controller using dot notation. The code looks like this (nestedObjectAtIndexPath is my helper method): NSString *rowKey = [rowKeys nestedObjectAtIndexPath:indexPath]; controller.keypath = rowKey; keypath is a synthesized nonatomic, retain property defined in a based class. When I hit a breakpoint in the controller at the above code, the NSString's value is as expected. When I hit the next breakpoint inside the child controller, the object id of the keypath property is the same as before, but instead of showing me the value of the NSString, XCode says that the variable is "out of scope" which is also the error I see in the console. This also happens in another sub-class of the same parent. I tried googling, and I saw slightly similar cases where people were suggesting this had to do with retain counts. I was under the impression that by using dot notation on a synthesized property, my class would be using an "auto generated accessor" that would be increasing my retain count for me so that I wouldn't have this problem. Could there be any implications because I'm accessing it in a sub-class and the prop is defined in the parent? I don't see anything in the book's errata about this, but the book is relatively new (Apress - More iPhone 3 Dev). I also have double checked that my code matches the example 100 times.

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  • Autofac WCF integration + sessions

    - by Michael Sagalovich
    I am having an ASP.NET MVC 3 application that collaborates with a WCF service, which is hosted using Autofac host factory. Here are some code samples: .svc file: <%@ ServiceHost Language="C#" Debug="true" Service="MyNamespace.IMyContract, MyAssembly" Factory="Autofac.Integration.Wcf.AutofacServiceHostFactory, Autofac.Integration.Wcf" %> Global.asax of the WCF service project: protected void Application_Start(object sender, EventArgs e) { ContainerBuilder builder = new ContainerBuilder(); //Here I perform all registrations, including implementation of IMyContract AutofacServiceHostFactory.Container = builder.Build(); } Client proxy class constructor (MVC side): ContainerBuilder builder = new ContainerBuilder(); builder.Register(c => new ChannelFactory<IMyContract>( new BasicHttpBinding(), new EndpointAddress(Settings.Default.Url_MyService))) .SingleInstance(); builder.Register(c => c.Resolve<ChannelFactory<IMyContract>>().CreateChannel()) .UseWcfSafeRelease(); _container = builder.Build(); This works fine until I want WCF service to allow or require sessions ([ServiceContract(SessionMode = SessionMode.Allowed)], or [ServiceContract(SessionMode = SessionMode.Required)]) and to share one session with the MVC side. I changed the binding to WSHttpBinding on the MVC side, but I am having different exceptions depending on how I tune it. I also tried changing AutofacServiceHostFactory to AutofacWebServiceHostFactory, with no result. I am not using config file as I am mainly experimenting, not developing real-life application, but I need to study the case. But if you think I can achieve what I need only with config files, then OK, I'll use them. I will provide exception details for each combination of settings if required, I'm omitting them not to make the post too large. Any ideas on what I can do?

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  • Top-Rated JavaScript Blogs

    - by Andreas Grech
    I am currently trying to find some blogs that talk (almost solely) on the JavaScript Language, and this is due to the fact that most of the time, bloggers with real life experience at work or at home development can explain more clearly and concisely certain quirks and hidden features than most 'Official Language Specifications' Below find a list of blogs that are JavaScript based (will update the list as more answers flow in): DHTML Kitchen, by Garrett Smith Robert's Talk, by Robert Nyman EJohn, by John Resig (of jQuery) Crockford's JavaScript Page, by Douglas Crockford Dean.edwards.name, by Dean Edwards Ajaxian, by various (@Martin) The JavaScript Weblog, by various SitePoint's JavaScript and CSS Page, by various AjaxBlog, by various Eric Lippert's Blog, by Eric Lippert (talks about JScript and JScript.Net) Web Bug Track, by various (@scunliffe) The Strange Zen Of JavaScript , by Scott Andrew Alex Russell (of Dojo) (@Eran Galperin) Ariel Flesler (@Eran Galperin) Nihilogic, by Jacob Seidelin (@llimllib) Peter's Blog, by Peter Michaux (@Borgar) Flagrant Badassery, by Steve Levithan (@Borgar) ./with Imagination, by Dustin Diaz (@Borgar) HedgerWow (@Borgar) Dreaming in Javascript, by Nosredna spudly.shuoink.com, by Stephen Sorensen Yahoo! User Interface Blog, by various (@Borgar) remy sharp's b:log, by Remy Sharp (@Borgar) JScript Blog, by the JScript Team (@Borgar) Dmitry Baranovskiy’s Web Log, by Dmitry Baranovskiy James Padolsey's Blog (@Kenny Eliasson) Perfection Kills; Exploring JavaScript by example, by Juriy Zaytsev DailyJS (@Ric) NCZOnline (@Kenny Eliasson), by Nicholas C. Zakas Which top-rated blogs am I currently missing from the above list, that you think should be imperative to any JavaScript developer to read (and follow) concurrently?

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  • Autonumber with Entity Framework

    - by dcompiled
    I want to loop through a collection of objects and add them all to a table. The destination table has an auto-increment field. If I add a single object there is no problem. If I add two objects both with the primary key of zero, the entity framework fails. I can manually specify primary keys but the whole point of trying the EF was to make life easier not more complicated. Here is the code and the exception received follows. foreach (Contact contact in contacts) { Instructor instructor = InstructorFromContact(contact); context.AddToInstructors(instructor); } try { context.SaveChanges(); } catch (Exception ex) { Console.WriteLine(ex.ToString()); } System.InvalidOperationException: The changes to the database were committed successfully, but an error occurred while updating the object context. The ObjectContext might be in an inconsistent state. Inner exception message: AcceptChanges cannot continue because the object's key values conflict with another object in the ObjectStateManager. Make sure that the key values are unique before calling AcceptChanges. at System.Data.Objects.ObjectContext.SaveChanges(SaveOptions options) at System.Data.Objects.ObjectContext.SaveChanges() at DataMigration.Program.CopyInstructors() in C:\Projects\DataMigration\Program.cs:line 52

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  • Problem with ScriptManager.RegisterStartupScript in WebControl nested in UpdatePanel

    - by Chris
    Hello, I am having what I believe should be a fairly simple problem, but for the life of me I cannot see my problem. The problem is related to ScriptManager.RegisterStartupScript, something I have used many times before. The scenario I have is that I have a custom web control that has been inserted into a page. The control (and one or two others) are nested inside an UpdatePanel. They are inserted onto the page onto a PlaceHolder: <asp:UpdatePanel ID="pnlAjax" runat="server"> <ContentTemplate> <asp:PlaceHolder ID="placeholder" runat="server"> </asp:PlaceHolder> ... protected override void OnInit(EventArgs e){ placeholder.Controls.Add(Factory.CreateControl()); base.OnInit(e); } This is the only update panel on the page. The control requires some initial javascript be run for it to work correctly. The control calls: ScriptManager.RegisterStartupScript(this, GetType(), Guid.NewGuid().ToString(), script, true); and I have also tried: ScriptManager.RegisterStartupScript(Page, Page.GetType(), Guid.NewGuid().ToString(), script, true); The problem is that the script runs correctly when the page is first displayed, but does not re-run after a partial postback. I have tried the following: Calling RegisterStartupScript from CreateChildControls Calling RegisterStartupScript from OnLoad / OnPreRender Using different combinations of parameters for the first two parameters (in the example above the Control is Page and Type is GetType(), but I have tried using the control itself, etc). I have tried using persistent and new ids (not that I believe this should have a major impact either way). I have used a few breakpoints and so have verified that the Register line is being called correctly. The only thing I have not tried is using the UpdatePanel itself as the Control and Type, as I do not believe the control should be aware of the update panel (and in any case there does not seem to be a good way of getting the update panel?). Can anyone see what I might be doing wrong in the above? Thanks :)

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  • How to analyze 'dbcc memorystatus' result in SQL Server 2008

    - by envykok
    Currently i am facing a sql memory pressure issue. i have run 'dbcc memorystatus', here is part of my result: Memory Manager KB VM Reserved 23617160 VM Committed 14818444 Locked Pages Allocated 0 Reserved Memory 1024 Reserved Memory In Use 0 Memory node Id = 0 KB VM Reserved 23613512 VM Committed 14814908 Locked Pages Allocated 0 MultiPage Allocator 387400 SinglePage Allocator 3265000 MEMORYCLERK_SQLBUFFERPOOL (node 0) KB VM Reserved 16809984 VM Committed 14184208 Locked Pages Allocated 0 SM Reserved 0 SM Committed 0 SinglePage Allocator 0 MultiPage Allocator 408 MEMORYCLERK_SQLCLR (node 0) KB VM Reserved 6311612 VM Committed 141616 Locked Pages Allocated 0 SM Reserved 0 SM Committed 0 SinglePage Allocator 1456 MultiPage Allocator 20144 CACHESTORE_SQLCP (node 0) KB VM Reserved 0 VM Committed 0 Locked Pages Allocated 0 SM Reserved 0 SM Committed 0 SinglePage Allocator 3101784 MultiPage Allocator 300328 Buffer Pool Value Committed 1742946 Target 1742946 Database 1333883 Dirty 940 In IO 1 Latched 18 Free 89 Stolen 408974 Reserved 2080 Visible 1742946 Stolen Potential 1579938 Limiting Factor 13 Last OOM Factor 0 Page Life Expectancy 5463 Process/System Counts Value Available Physical Memory 258572288 Available Virtual Memory 8771398631424 Available Paging File 16030617600 Working Set 15225597952 Percent of Committed Memory in WS 100 Page Faults 305556823 System physical memory high 1 System physical memory low 0 Process physical memory low 0 Process virtual memory low 0 Procedure Cache Value TotalProcs 11382 TotalPages 430160 InUsePages 28 Can you lead me to analyze this result ? Is it a lot execute plan have been cached causing the memory issue or other reasons?

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  • Grep failing with Emacs (windows), and GnuWin32 Grep

    - by Andy
    Hi, I've downloaded and installed the GnuWin32 tools, and added the grep executables to the Emacs bin. I've also, for what its worth, added the GnuWin32 bin folder to my Path variable. Problem is though, when I try and run with suggested grep commands, I always get: Grep exited abnormally with code 53 at Wed Feb 24 17:16:12 For the life of me, I can't find any reference to error code 53 anywhere! :( I've tried the exact examples on a number of websites for example, when I enter: M-x grep <ret> It comes up with Run grep (like this): grep -n Which is fine, but I have no idea of what parameters it expects. I've tried some in some tuorials, but I get error code 53 again! One of the things I've tried is straight from the emacs wiki (http://www.emacswiki.org/emacs/GrepMode#toc2) (maybe not for the windows version though?) and it says to try this command: M-x grep -n -e setq ~/.emacs Which I've tried and I get: -*- mode: grep; default-directory: "c:/[My Directory]/" -*- Grep started at Wed Feb 24 17:30:47 grep -n -e setq ~/.emacs NUL Grep exited abnormally with code 53 at Wed Feb 24 17:30:47 So frustrating as this is meant to be a powerful feature of Emacs and I'm really trying to learn it as I've heard good things about it! Any help would be appreciated! :) Andy UPDATE From the suggestion below, I've tried it via command line and it seems to work fine, perhaps there some config I'm UPDATE I've found the command M-x Occur which seems to do much the same as I would image grep does. Are there many extra benefits to using grep over occur if I can't get this working?

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  • Flex DataGrid with ComboBox itemRenderer

    - by Jamie Love
    Hi there, I'm going spare trying to figure out the "correct" way to embed a ComboBox inside a Flex (3.4) DataGrid. By Rights (e.g. according to this page http://blog.flexmonkeypatches.com/2008/02/18/simple-datagrid-combobox-as-item-editor-example/) it should be easy, but I can't for the life of me make this work. The difference I have to the example linked above is that my display value (what the user sees) is different to the id value I want to select on and store in my data provider. So what I have is: <mx:DataGridColumn headerText="Type" width="200" dataField="TransactionTypeID" editorDataField="value" textAlign="center" editable="true" rendererIsEditor="true"> <mx:itemRenderer> <mx:Component> <mx:ComboBox dataProvider="{parentDocument.transactionTypesData}"/> </mx:Component> </mx:itemRenderer> </mx:DataGridColumn> Where transactionTypesData has both 'data' and 'label' fields (as per what the ComboBox - why on earth it doesn't provide both a labelField and idField I'll never know). Anyway, the above MXML code doesn't work in two ways: The combo box does not show up with any selected item. After selecting an item, it does not store back that selected item to the datastore. So, has anyone got a similar situation working?

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  • iPod/iPhone OpenGL ES UIView flashes when updating

    - by Dave Viner
    I have a simple iPhone application which uses OpenGL ES (v1) to draw a line based on the touches of the user. In the XCode Simulator, the code works perfectly. However, when I install the app onto an iPod or iPhone, the OpenGL ES view "flashes" when drawing the line. If I disable the line drawing, the flash disappears. By "flash", I mean that the background image (which is an OpenGL texture) disappears momentarily, and then reappears. It appears as if the entire scene is completely erased and redrawn. The code which handles the line drawing is the following: renderLineFromPoint:(CGPoint)start toPoint:(CGPoint)end { static GLfloat* vertexBuffer = NULL; static NSUInteger vertexMax = 64; NSUInteger vertexCount = 0, count, i; //Allocate vertex array buffer if(vertexBuffer == NULL) vertexBuffer = malloc(vertexMax * 2 * sizeof(GLfloat)); //Add points to the buffer so there are drawing points every X pixels count = MAX(ceilf(sqrtf((end.x - start.x) * (end.x - start.x) + (end.y - start.y) * (end.y - start.y)) / kBrushPixelStep), 1); for(i = 0; i < count; ++i) { if(vertexCount == vertexMax) { vertexMax = 2 * vertexMax; vertexBuffer = realloc(vertexBuffer, vertexMax * 2 * sizeof(GLfloat)); } vertexBuffer[2 * vertexCount + 0] = start.x + (end.x - start.x) * ((GLfloat)i / (GLfloat)count); vertexBuffer[2 * vertexCount + 1] = start.y + (end.y - start.y) * ((GLfloat)i / (GLfloat)count); vertexCount += 1; } //Render the vertex array glVertexPointer(2, GL_FLOAT, 0, vertexBuffer); glDrawArrays(GL_POINTS, 0, vertexCount); //Display the buffer [context presentRenderbuffer:GL_RENDERBUFFER_OES]; } (This function is based on the function of the same name from the GLPaint sample application.) For the life of me, I can not figure out why this causes the screen to flash. The line is drawn properly (both in the Simulator and in the iPod). But, the flash makes it unusable. Anyone have ideas on how to prevent the "flash"?

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  • Posting a JSON array to webservice in Android

    - by Sam
    I am having some problems with what should be a rather simple task. I simply need a JSON array with a single JSON object within it to be posted to my webservice. The entire URL request needs to be formatted like this: http://www.myserver.com/myservice.php?location_data=[{"key1":"val1","key2":"val2"....}] I cannot for the life of me figure out how to append the 'location_data' bit using HttpPost. Here is a code snippet to demonstrate the HTTP connection method I am using: HttpClient hClient = new DefaultHttpClient(); HttpPost hPost = new HttpPost(url); try { hPost.setEntity(new StringEntity(string)); hPost.setHeader("Accept", "application/json"); hPost.setHeader("Content-type", "application/json"); //execute request HttpResponse response = (HttpResponse) hClient.execute(hPost); HttpEntity entity = response.getEntity(); I don't have any syntax errors, and my code is accessing the server fine, just not in the exact format the server needs. Any help on how to format my request to look like how I need it would be greatly appreciated!

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