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  • Development process for an embedded project with significant hardware changes

    - by pierr
    I have a good idea about Agile development process but it seems it does not fit well with a embedded project with significant hardware changes. I will describe below what we are currently doing (Ad-hoc way, no defined process yet). The changes are divided into three categories and different processes are used for each of them: complete hardware change example : use a different video codec IP a) Study the new IP b) RTL/FPGA simulation c) Implement the legacy interface - go to b) d) Wait until hardware (tape out) is ready f) Test on the real hardware hardware improvement example : enhance the image display quality by improving the underlying algorithm a) RTL/FPGA simulation b) Wait until hardware and test on the hardware Minor change example : only change hardware register mapping a) Wait until hardware and test on the hardware The worry is it seems we don't have too much control and confidence about software maturity for the hardware changes as the bring-up schedule is always very tight and the customer desired a seamless change when updating to a new version of hardware. How did you manage this kind of hardware change? Did you solve that by a Hardware Abstraction Layer (HAL)? Did you have a automatic test for the HAL layer? How did you test when the hardware platform is not even ready? Do you have well-documented processes for this kind of change?

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  • Kruskal-Wallis test with details on pairwise comparisons

    - by dalloliogm
    The standard stats::kruskal.test module allows to calculate the kruskal-wallis test on a dataset: >>> data(diamonds) >>> kruskal.test.test(price~carat, data=diamonds) Kruskal-Wallis rank sum test data: price by carat by color Kruskal-Wallis chi-squared = 50570.15, df = 272, p-value < 2.2e-16 this is correct, it is giving me a probability that all the groups in the data have the same mean. However, I would like to have the details for each pair comparison, like if diamonds of colors D and E have the same mean price, as some other softwares do (SPSS) when you ask for a Kruskal test. I have found kruskalmc from the package pgirmess which allows me to do what I want to do: > kruskalmc(diamonds$price, diamonds$color) Multiple comparison test after Kruskal-Wallis p.value: 0.05 Comparisons obs.dif critical.dif difference D-E 571.7459 747.4962 FALSE D-F 2237.4309 751.5684 TRUE D-G 2643.1778 726.9854 TRUE D-H 4539.4392 774.4809 TRUE D-I 6002.6286 862.0150 TRUE D-J 8077.2871 1061.7451 TRUE E-F 2809.1767 680.4144 TRUE E-G 3214.9237 653.1587 TRUE E-H 5111.1851 705.6410 TRUE E-I 6574.3744 800.7362 TRUE E-J 8649.0330 1012.6260 TRUE F-G 405.7470 657.8152 FALSE F-H 2302.0083 709.9533 TRUE F-I 3765.1977 804.5390 TRUE F-J 5839.8562 1015.6357 TRUE G-H 1896.2614 683.8760 TRUE G-I 3359.4507 781.6237 TRUE G-J 5434.1093 997.5813 TRUE H-I 1463.1894 825.9834 TRUE H-J 3537.8479 1032.7058 TRUE I-J 2074.6585 1099.8776 TRUE However, this package only allows for one categoric variable (e.g. I can't study the prices clustered by color and by carat, as I can do with kruskal.test), and I don't know anything about the pgirmess package, whether it is maintained or not, or if it is tested. Can you recommend me a package to execute the Kruskal-Wallis test which returns details for every comparison? How would you handle the problem?

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  • [OffTopic] PhD is it worth it?

    - by Zenzen
    So I'll be graduating next year (hopefully) and lately I started thinking about getting a PhD in computer science (to be more precise I was thinking about something related to "distributed systems", don't have any specific topics yet in mind), but is it really worth it? A PhD course here lasts 4 years and is free IF you're doing the "normal one" (which means you have class from monday to friday) OR you have to pay if you want to study on the weekends. So I've been thinking about getting a normal full time job (as a JEE programmer) and doing my PhD during the weekends OR doing the normal PhD course (mon-fri) and getting a part time job as a software dev (the main reason I want a job is simple - I need to eat). That would give me practical working experience and theoretical knowledge+a PhD, but it would also mean working 7days a week from 9 to 5 for 4 years straight (sounds like an overkill). Is it, job wise, really worth getting a PhD? As an employer do you prefer people with PhDs or MScs? This might be kinda important - I'm not from the US or western europe, how are PhDs from other countries (I am graduating one of the best, if not the best, school in my country but it's still a central european country...) seen? Are they useless? I won't hide it - after graduation I am thinking about moving abroad.

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  • How did the Lunar Lander example make the image backgrounds transparent?

    - by user279112
    Hello. I'm trying to make a GUI program with the Android SDK, using their Lunar Lander example as a significant self-teaching tool in the process. I've noticed their sprites' images' backgrounds, which were at least usually pure white, did not show up in their program. I want to ask how they did that, since their site doesn't explain simple things very well. I've managed to pull that off before on another GUI SDK, wherein all I had to do was to call a function and pass it a few floats to define a certain color, and until my code told it to do otherwise, that function would make sure that that particular color in my sprites' images was totally transparent. However I've wrestled with the Lunar Lander example and getting my own program to show some custom graphics for a week or two now, and I haven't noticed any such function call in the Lunar Lander example. I tried to look for it, but I did not find anything. I've tried to Google some tutorial or other reference material, but what I've found so far is just straying off into unrelated areas and totally dodging this EXTREMELY important lesson on the SDK's basics. Any ideas? Thanks!

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  • Db4o Mvc Application Architecture

    - by Mac
    I am currently testing out Db4o for an asp.net MVC 2 application idea but there are a few things I'm not quite sure on the best way to proceed. I want my application to use guessable routes rather than Id's for referencing my entities but I also think I need Id's of some sort for update scenarios. so for example I want /country/usa instead of /country/1 I may want to change the key name though (not perhaps on a country but on other entities) so am thinking I need an Id to use as the reference to retrieve the object prior to updating it's fields. From other comments it seems like the UUID is a bit long to be using and would prefer to use my own id's anyway for clean separation of concerns. Looking at both the KandaAlpha project I wasn't too keen on some aspects of the design and prefer something more along the lines of S#arp architecture where they use things like the [domainsignature] and EntityWithTypedId, IEntityDuplicateChecker, IHasAssignedId, BaseObject and IValidatable in their entities to control insert/update behaviour which seems cleaner and more extensible, covers validation and is encapsulated well within the core and base repository classes. So would a port of S#arp architecture to Db4o make sense of am I still thinking rmdbs in an oodb world? Also is there a best practice for managing indexes (including Unique ones as above) in Db4o? Should they be model metadata based and loaded using DI in a bootstrapper for example or should they be more loaded more like Automapper.CreateMap? Its a bit of a rambling question I know but any thoughts, ideas or suggested reading material is greatly appreciated. Thanks Mac

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  • Odd Infragistics UltraComboEditor data binding non-bug

    - by Richard Dunlap
    Within an Infragistics 8.2 UltraComboEditor, we had the following properties set via C#: DataSource = dataSource; ValueMember = "Measure"; DisplayMember = "Name"; DataBindings.Add("Value", repository, "Measure"); DataBindings["Value"].DataSourceUpdateMode = DataSourceUpdateMode.OnPropertyChanged; where dataSource was an array of objects, each with a property Measure, and repository was an object with a property Measure. (Those strings are actually constructor parameters -- just using explicit strings to simplify the example.) In the course of some refactoring, the name of the property on the objects in the array was changed to BaseEnum (the objects are actually wrapped enumerations, for the curious), but the name of ValueMember above was not changed. And yet, the combo box binding continued to work through initial testing, beta testing, and even after release... until two customers emailed in noting that the combo box was no longer changing the underlying parameter. We were able to dig out the problem by careful study of the source code repository... despite being in the awkward position of not being able to replicate the buggy behavior internally. Two part question: What's happening under the hood that allowed the binding to continue to function, and/or what might be unique about those two users that caused the binding to (correctly) fail? (O/S version isn't alone the answer, and we get the unexpectedly functioning binding on machines that have never had a version of the software before, so we're not looking at rogue binaries). Are there tools that might have been able to warn us about the misbind, even if something was cleaning up behind?

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  • How to do SoapClient on php

    - by Jin Yong
    I'm new in soapclient, I have tried to do some study online and also tried coding on soap, but seem this is still not working to me, just wandering anyone here can point out and perhaps give me some example how can I actually use the soapclint to get the feedback from the following web server? POST /webservices/tempconvert.asmx HTTP/1.1 Host: www.w3schools.com Content-Type: text/xml; charset=utf-8 Content-Length: length SOAPAction: "http://tempuri.org/CelsiusToFahrenheit" <?xml version="1.0" encoding="utf-8"?> <soap:Envelope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/"> <soap:Body> <CelsiusToFahrenheit xmlns="http://tempuri.org/"> <Celsius>string</Celsius> </CelsiusToFahrenheit> </soap:Body> </soap:Envelope> HTTP/1.1 200 OK Content-Type: text/xml; charset=utf-8 Content-Length: length <?xml version="1.0" encoding="utf-8"?> <soap:Envelope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/"> <soap:Body> <CelsiusToFahrenheitResponse xmlns="http://tempuri.org/"> <CelsiusToFahrenheitResult>string</CelsiusToFahrenheitResult> </CelsiusToFahrenheitResponse> </soap:Body> </soap:Envelope> <?php $url = "http://www.w3schools.com/webservices/tempconvert.asmx?WSDL"; $client = new SoapClient($url); ?> What should I do for the next steps so that I can get the respond ??

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  • Command /Developer/usr/bin/dsymutil failed with exit code 10

    - by Evan Robinson
    I am getting the above error message randomly (so far as I can tell) on iPhone projects. Occasionally it will go away upon either: Clean Restart XCode Reboot Reinstall XCode But sometimes it won't. When it won't the only solution I have found is to take all the source material, import it into a new project, and then redo all the connections in IB. Then I'm good until it strikes again. Anybody have any suggestions? [update 20091030] I have tried building both debug and release versions, both full and lite versions. I've also tried switching the debug symbols from DWARF with external dSYM file to DWARF and to stabs. Clean builds in all formats make no differences. Permission repairs change nothing. Setting up a new user has no effect. Same error on the builds. Thanks for the suggestions! [Update 20091031] Here's an easier and (apparently) reliable workaround. It hinges upon the discovery that the problem is linked to a target not a project In the same project file, create a new target Option-Drag (copy) all the files from the BAD target 'Copy Bundle Resources' folder to the NEW target 'Copy Bundle Resources' folder Repeat (2) with 'Compile Sources' and 'Link Binary With Libraries' Duplicate the Info.plist file for the BAD target and name it correctly for the NEW target. Build the NEW target! [Update 20100222] Apparently an IDE bug, now apparently fixed, although Apple does not allow direct access to the original bug of a duplicate. I can no longer reproduce this behaviour, so hopefully it is dead, dead, dead.

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  • Putting a MovieMaterial behind a DAE model in Papervision3D

    - by didibus
    Hi, I'm doing a project using FLARManager augmented reality and the Papervision3D library. Unfortunately, Papervision is giving me a lot of problems. My scene3D contains a DAE model and a plane. The plane has a MovieMaterial and is playing a video through FLVPlayback. The DAE and the plane are both inside the same DisplayObject3D container. FLARManager transforms the container so that everything appears through the angle of the marker. My DAE model is a TV, the screen of the TV is transparent. I want to have my Plane inside of my DAE model, so that the Movie playing on the plane material appears to be what is playing on the TV. The problem is that, even if the plane has a lower Z index then the TV, it always appears in front of the TV. How do I have my plane and its MovieMaterial appear behind the TV, so that some of its corners are cut out by the TV and the part of the TV thats transparent let me see the Movie? If its impossible, anyone has an idea of how I could get the desired effect of having a movie play on the screen of my DAE tv model? Thank You.

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  • x86 opcode alignment references and guidelines

    - by mrjoltcola
    I'm generating some opcodes dynamically in a JIT compiler and I'm looking for guidelines for opcode alignment. 1) I've read comments that briefly "recommend" alignment by adding nops after calls 2) I've also read about using nop for optimizing sequences for parallelism. 3) I've read that alignment of ops is good for "cache" performance Usually these comments don't give any supporting references. Its one thing to read a blog or a comment that says, "its a good idea to do such and such", but its another to actually write a compiler that implements specific op sequences and realize most material online, especially blogs, are not useful for practical application. So I'm a believer in finding things out myself (disassembly, etc. to see what real world apps do). This is one case where I need some outside info. I notice compilers will usually start an odd byte instruction immediately after whatever previous instruction sequence there was. So the compiler is not taking any special care in most cases. I see "nop" here or there, but usually it seems nop is used sparingly, if at all. How critical is opcode alignment? Can you provide references for cases that I can actually use for implementation? Thanks.

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  • Double type returns -1.#IND/NaN error when calculating pi iteratively

    - by Draak
    I am working through a problem for my MCTS certification. The program has to calculate pi until the user presses a key, at which point the thread is aborted, the result returned to the main thread and printed in the console. Simple enough, right? This exercise is really meant to be about threading, but I'm running into another problem. The procedure that calculates pi returns -1.#IND. I've read some of the material on the web about this error, but I'm still not sure how to fix it. When I change double to Decimal type, I unsurprisingly get Overflow Exception very quickly. So, the question is how do I store the numbers correctly? Do I have to create a class to somehow store parts of the number when it gets too big to be contained in a Decimal? Class PiCalculator Dim a As Double = 1 Dim b As Double = 1 / Math.Sqrt(2) Dim t As Double = 1 / 4 Dim p As Double = 1 Dim pi As Double Dim callback As DelegateResult Sub New(ByVal _callback As DelegateResult) callback = _callback End Sub Sub Calculate() Try Do While True Dim a1 = (a + b) / 2 Dim b1 = Math.Sqrt(a * b) Dim t1 = t - p * (a - a1) ^ 2 Dim p1 = 2 * p a = a1 b = b1 t = t1 p = p1 pi = ((a + b) ^ 2) / (4 * t) Loop Catch ex As ThreadAbortException Finally callback(pi) End Try End Sub End Class

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  • Is there any better IDOMImplementation other than MSXML?

    - by Chau Chee Yang
    There are 3 IDOMImplementation available in Delphi: MSXML Xerces XML ADOM XML v4 MSXML is the default IDOMImplementation. My test is count the time need to load a 10MB xml file. I use a Delphi unit generated from a XSD using XML data binding to load the xml file. This unit has 3 common function: function Getmenubar(Doc: IXMLDocument): IXMLMenubarType; function Loadmenubar(const FileName: WideString): IXMLMenubarType; function Newmenubar: IXMLMenubarType; I learn from the web that some comment that MSXML's overhead is high that it doesn't perform if compare to other XML parser. However, my study shows that MSXML is the best among others. Xerces XML 2nd and ADOM XML v4 the worst: MSXML - 0.6410 seconds Xerces XML - 2.4220 seconds ADOM XML v4 - 67.50 seconds I also come across with OmniXML that claim to have much better performance compare to MSXML but I never success using it with the unit generated by XML data binding. Is there any other vendor that implement IDOMImplementation of Delphi that work much better than MSXML? I am using Delphi 2010 and Windows 7.

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  • latex list environment inside the tabular environment: extra line at top preventing alignment

    - by Usagi
    Hello good people of stackoverflow. I have a LaTeX question that is bugging me. I have been trying to get a list environment to appear correctly inside the tabular environment. So far I have gotten everything to my liking except one thing: the top of the list does not align with other entries in the table, in fact it looks like it adds one line above the list... I would like to have these lists at the top. This is what I have, a custom list environment: \newenvironment{flushemize}{ \begin{list}{$\bullet$} {\setlength{\itemsep}{1pt} \setlength{\parskip}{0pt} \setlength{\parsep}{0pt} \setlength{\partopsep}{0pt} \setlength{\topsep}{0pt} \setlength{\leftmargin}{12pt}}}{\end{list}} Renamed ragged right: \newcommand{\rr}{\raggedright} and here is my table: \begin{table}[H]\caption{Tank comparisons}\label{tab:tanks} \centering \rowcolors{2}{white}{tableShade} \begin{tabular}{p{1in}p{1.5in}p{1.5in}rr} \toprule {\bf Material} & {\bf Pros} & {\bf Cons} & {\bf Size} & {\bf Cost} \\ \midrule \rr Reinforced concrete &\rr \begin{flushemize}\item Strong \item Secure \end{flushemize}&\rr \begin{flushemize}\item Prone to leaks \item Relatively expensive to install \item Heavy \end{flushemize} & 100,000 gal & \$299,400 \\ \rr Steel & \begin{flushemize}\item Strong \item Secure \end{flushemize} & \begin{flushemize}\item Relatively expensive to install \item Heavy \item Require painting to prevent rusting \end{flushemize} & 100,000 gal & \$130,100 \\ \rr Polypropylene & \begin{flushemize}\item Easy to install \item Mobile \item Inexpensive \item Prefabricated \end{flushemize} & \begin{flushemize}\item Relatively insecure \item Max size available 10,000 gal \end{flushemize} & 10,000 gal & \$5,000 \\ \rr Wood & \begin{flushemize}\item Easy to install \item Mobile \item Cheap to install \end{flushemize} & \begin{flushemize}\item Prone to rot \item Must remain full once constructed \end{flushemize} & 100,000 gal & \$86,300\\ \bottomrule \end{tabular} \end{table} Thank you for any advice :)

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  • Best cubicle toys for programming

    - by dlamblin
    I need some employee/co-worker Christmas gift ideas. Do you have any good cubicle toys that help you to do any of: think about programming problems solve programming problems by representing common abstractions can be directly programmed can interface with a PC based IDE to be programmed. it may present problems that can be solved, to kick start problem solving. Disallowed items are: reference material in book, pamphlet, poster or cheat-sheet form, even if it has kick ass pop-cultural references. edibles. [discuss separately] things that need their own lab-space and/or extensive tools to be worked with. So yes, Lego Mindstorms come to mind, but they aren't cubicle toys because they cost more than cubicle toys would, and they have too many losable parts. comments on the answers so far: The 20 Questions game sounds quite neat as it could get you thinking; The bean balls could be used as tokens in a problem, so I can see that working. The magnetic toys like ball of whacks or the ball-and-stick ones present hands on fun of a structural nature... now can there be a similar hands on fun toy that aids in representing a solution to a problem? The Gui Mags clearly could, but they're quite utility oriented. The AVR Butterfly is less of a toy but definitely priced attractively, cheaper and more responsive than a basic stamp. I'm not going to pick an answer; there's several great suggestions here. Thank you.

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  • Implementing BindingList<T>

    - by EtherealMonkey
    I am trying to learn more about BindingList because I believe that it will help me with a project that I am working on. Currently, I have an object class (ScannedImage) that is a subtype of a class (HashedImage) that subtypes a native .Net object (Image). There is no reason why I couldn't move the two subtypes together. I am simply subtyping an object that I had previously constructed, but I will now be storing my ScannedImage object in an RDB (well, not technically - only the details and probably the thumbnail). Also, the object class has member types that are my own custom types (Keywords). I am using a custom datagridview to present these objects, but am handling all changes to the ScannedImage object with my own code. As you can probably imagine, I have quite a few events to handle that occur in these base types. So, if I changed my object to implement INotifyPropertyChanged, would the object collection (implementing BindingList) receive notifications of changes to the ScannedImage object? Also, if Keywords were to implement INotifyPropertyChanged, would changes be accessible to the BindingList through the ScannedImage object? Sorry if this seems rather newbish. I only recently discovered the BindingList and not having formal training in C# programming - am having a difficult time moving forward with this. Also, if anyone has any good reference material, I would be thankful for links. Obviously, I have perused the MSDN Library. I have found a few good links on the web, but it seems that a lot of people are now using WPF and ObservableCollection. My project is based on Winforms and .Net3.5 framework. TIA

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  • Code Golf: Quickly Build List of Keywords from Text, Including # of Instances

    - by Jonathan Sampson
    I've already worked out this solution for myself with PHP, but I'm curious how it could be done differently - better even. The two languages I'm primarily interested in are PHP and Javascript, but I'd be interested in seeing how quickly this could be done in any other major language today as well (mostly C#, Java, etc). Return only words with an occurrence greater than X Return only words with a length greater than Y Ignore common terms like "and, is, the, etc" Feel free to strip punctuation prior to processing (ie. "John's" becomes "John") Return results in a collection/array Extra Credit Keep Quoted Statements together, (ie. "They were 'too good to be true' apparently")Where 'too good to be true' would be the actual statement Extra-Extra Credit Can your script determine words that should be kept together based upon their frequency of being found together? This being done without knowing the words beforehand. Example: "The fruit fly is a great thing when it comes to medical research. Much study has been done on the fruit fly in the past, and has lead to many breakthroughs. In the future, the fruit fly will continue to be studied, but our methods may change." Clearly the word here is "fruit fly," which is easy for us to find. Can your search'n'scrape script determine this too? Source text: http://sampsonresume.com/labs/c.txt Answer Format It would be great to see the results of your code, output, in addition to how long the operation lasted.

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  • Frame Accurate Browser Launchable Video Player ... ?

    - by cliftonc
    I have a requirement where I need to enable playback (full screen) of a h.264 MPEG4 (thanks for the correction!) video from a local network, launchable from a browser link on a Windows workstation, and be frame accurate. By frame accurate I mean that I need to be able to scrub through the video in the same way you would with a vtr, stop at a frame, and then move backwards and forwards frame by frame (it is for a very specific compliance requirement where have to be able to check every frame if there is something that is potentially against broadcasting guidelines). The application itself is used to capture notes while viewing the material, so the end model is for a dual monitor workstation, with a web form in one, the video playing full screen in the second (no issue launching the video and manually having to move it to the second screen), and then the user controls the video via keyboard shortcuts or a jog shuttle. I have looked at QT, but the java bindings seem to be dead or nearly so, flash isn't frame accurate, VLC given its streaming heritage seems to be only able to move forward by a frame and not backwards, and all I have left are commercial offerings that in my experience are difficult and expensive to change. Any ideas of where I should look or alternative options? Any advice appreciated!

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  • Developmnet process for an embedded project with significant Hardware change

    - by pierr
    Hi, I have a good idea about Agile development process but it seems it does not fit well with a embedded project with significant hardware change. I will describe below what we are currently doing (Ad-hoc way , no defined process yet). The change are divided to three categories and different process are used for them : complete hardware change example : use a different video codec IP a) Study the new IP b) RTL/FPGA simulation c) Implement the leagcy interface - go to b) d) Wait until hardware (tape out) is ready f) Test on the real Hardware hardware improvement example : enhance the image display quaulity by improving the underlie algorithm a)RTL/FPGA simulation b)Wait until hardware and test on the hardware Mino change exmaple : only change hardware register mapping a)Wait until hardware and test on the hardware The worry is it seems we don't have too much control and confidence about software maturity for the hardware change as the bring up schedule is always very tight and the customer desired a seemless change when updating to a new version hardware. How did you manage this kind of hardware hardware change? Did you solve that by a Hardware Abstraction Layer (HAL)? Did you have a automatical test for the HAL layer? How did you test when the hardware platform is not even ready? Do you have well documented process for this kind of change? Thanks for your insight.

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  • Java: Handling cookies when logging in with POST

    - by Cris Carter
    I'm having quite some trouble logging in to any site in Java. I'm using the default URLconnection POST request, but I'm unsure how to handle the cookies properly. I tried this guide: http://www.hccp.org/java-net-cookie-how-to.html But couldn't get it working. I've been trying basically for days now, and I really need help if anyone wants to help me. I'll probably be told that it's messy and that I should use a custom library meant for this stuff. I tried downloading one, but wasn't sure how to get it set up and working. I've been trying various things for hours now, and it just won't work. I'd rather do this with a standard URLconnection, but if anyone can help me get another library working that's better for this, that would be great, too. I would really appreciate if someone could post a working source that I could study. What I need is: POST login data to site - Get and store the cookie from the site - use cookie with next URLconnection requests to get logged-in version of the site. Can anyone help me with this? Would be EXTREMELY appreciated. It really does mean a lot. If anyone wants to actually help me out live, please leave an instant-messenger address. Thank you a lot for your time.

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  • Help to understand the issue with protected method

    - by zeroed
    I'm reading Sybex Complete Java 2 Certification Study Guide April 2005 (ISBN0782144195). This book is for java developers who wants to pass java certification. After a chapter about access modifiers (along with other modifiers) I found the following question (#17): True or false: If class Y extends class X, the two classes are in different packages, and class X has a protected method called abby(), then any instance of Y may call the abby() method of any other instance of Y. This question confused me a little. As far as I know you can call protected method on any variable of the same class (or subclasses). You cannot call it on variables, that higher in the hierarchy than you (e.g. interfaces that you implement). For example, you cannot clone any object just because you inherit it. But the questions says nothing about variable type, only about instance type. I was confused a little and answered "true". The answer in the book is False. An object that inherits a protected method from a superclass in a different package may call that method on itself but not on other instances of the same class. There is nothing here about variable type, only about instance type. This is very strange, I do not understand it. Can anybody explain what is going on here?

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  • Game login authentication and security.

    - by Charles
    First off I will say I am completely new to security in coding. I am currently helping a friend develop a small game (in Python) which will have a login server. I don't have much knowledge regarding security, but I know many games do have issues with this. Everything from 3rd party applications (bots) to WPE packet manipulation. Considering how small this game will be and the limited user base, I doubt we will have serious issues, but would like to try our best to limit problems. I am not sure where to start or what methods I should use, or what's worth it. For example, sending data to the server such as login name and password. I was told his information should be encrypted when sending, so in-case someone was viewing it (with whatever means), that they couldn't get into the account. However, if someone is able to capture the encrypted string, wouldn't this string always work since it's decrypted server side? In other words, someone could just capture the packet, reuse it, and still gain access to the account? The main goal I am really looking for is to make sure the players are logging into the game with the client we provide, and to make sure it's 'secure' (broad, I know). I have looked around at different methods such as Public and Private Key encryption, which I am sure any hex editor could eventually find. There are many other methods that seem way over my head at the moment and leave the impression of overkill. I realize nothing is 100% secure. I am just looking for any input or reading material (links) to accomplish the main goal stated above. Would appreciate any help, thanks.

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  • Collaborative filtering in MySQL ?

    - by user281434
    Hi I'm trying to develop a site that recommends items(fx. books) to users based on their preferences. So far, I've read O'Reilly's "Collective Intelligence" and numerous other online articles. They all, however, seem to deal with single instances of recommendation, for example if you like book A then you might like book B. What I'm trying to do is to create a set of 'preference-nodes' for each user on my site. Let's say a user likes book A,B and C. Then, when they add book D, I don't want the system to recommend other books based solely other users experience with book D. I wan't the system to look up similar 'preference-nodes' and recommend books based on that. Here's an example of 4 nodes: User1: 'book A'->'book B'->'book C' User2: 'book A'->'book B'->'book C'->'book D' user3: 'book X'->'book Y'->'book C'->'book Z' user4: 'book W'->'book Q'->'book C'->'book Z' So a recommendation system, as described in the material I've read, would recommend book Z to User 1, because there are two people who recommends Z in conjuction with liking C (ie. Z weighs more than D), even though a user with a similar 'preference-node', User2, would be more qualified to recommend book D because he has a more similar interest-pattern. So does any of you have any experience with this sort of thing? Is there some things I should try to read or does there exist any open source systems for this? Thanks for your time! Small edit: I think last.fm's algorithm is doing exactly what I my system to do. Using the preference-trees of people to recommmend music more personally to people. Instead of just saying "you might like B because you liked A"

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  • Where does Tomcat append / to directory paths?

    - by Anonymouse
    Suppose my Tomcat webapps directory looks like this: webapps/ webapps/fooapp/ webapps/fooapp/WEB-INF/ webapps/fooapp/WEB-INF/web.xml webapps/fooapp/bardir/ When I make a GET request for /fooapp/bardir, Tomcat sees that webapps/fooapp/bardir is a directory and sends back a 302 to /fooapp/bardir/ (with a slash at the end). Here is my question: Where in the Tomcat source code does this take place? (I'm looking at 6.0.x but a correct answer for any version would be a great starting point.) The only reference material I can find on this subject is in the Catalina Functional Specifications which states, regarding the Default Servlet: On each HTTP GET request processed by this servlet, the following processing shall be performed: [...] If the requested resource is a directory: If the request path does not end with "/", redirect to a corresponding path with "/" appended so that relative references in welcome files are resolved correctly. However, this functionality does not appear to be in org.apache.catalina.servlets.DefaultServlet; or at least, it's not there exclusively: if I replace the default servlet in web.xml with a servlet whose servlet-class does not exist, directory paths still come back 302 to add the slash, while every other request comes back with an error as expected.

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  • Constructing human readable sentences based on a survey

    - by Joshua
    The following is a survey given to course attendees to assess an instructor at the end of the course. Communication Skills 1. The instructor communicated course material clearly and accurately. Yes No 2. The instructor explained course objectives and learning outcomes. Yes No 3. In the event of not understanding course materials the instructor was available outside of class. Yes No 4. Was instructor feedback and grading process clear and helpful? Yes No 5. Do you feel that your oral and written skills have improved while in this course? Yes No We would like to summarize each attendees selection based on the choices chosen by him. If the provided answers were [No, No, Yes, Yes, Yes]. Then we would summarize this as "The instructor was not able to summarize course objectives and learning outcomes clearly, but was available for usually helpful outside of class. The instructor feedback and grading process was clear and helpful and I feel that my oral and written skills have improved because of this course. Based on the selections chosen by the attendee the summary would be quite different. This leads to many answers based on the choices selected and the number of such questions in the survey. The questions are usually provided by the training organization. How do you come up with a generic solution so that this can be effectively translated into a human readable form. I am looking for tools or libraries (java based), suggestions which will help me create such human readable output. I would like to hide the complexity from the end users as much as possible.

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  • How to get raw jpeg data (but no metatags / proprietary markers)

    - by CoolAJ86
    I want to get raw jpeg data - no metadata. I'm very confused looking at the jpeg "standards". How correct is my understanding of the marker "tree"? 0xFFD8 - Identifies the file as an image 0xFFE? - EXIF, JFIF, SPIFF, ICC, etc 0x???? - the length of the tag 0xFFD8 - Start of Image 0xFFE0 - should follow SOI as per spec, but often preceded by comments ??? 0x???? - Matrices, tags, random data ??? There are never other markers in-between these markers? Or these include the matrices and such? 0xFFDA - Start of Stream - This is what I want, yes? 0xXXXX - length of stream 0xFFD9 - End of Stream (EOI) 0x???? - Comment tags, extra exif, jfif info??? 0xFFD9 - End of Image 0xFF00 - escaped 0xFF, not to be confused with a marker This has been my reading material: http://en.wikipedia.org/wiki/JPEG http://www.sno.phy.queensu.ca/~phil/exiftool/TagNames/JPEG.html http://www.media.mit.edu/pia/Research/deepview/exif.html http://www.faqs.org/faqs/jpeg-faq/part1/section-15.html

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