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  • Agile Testing Days 2012 – Day 1 – The birth of the #unicorn…

    - by Chris George
    Still riding the high from the tutorial day, I arrived at the conference venue eager to get cracking with the days talks. The opening Keynote was “Disciplined Agile Delivery: The Foundation for Scaling Agile” presented by Scott Ambler. The general ideas behind the methodology such as not re-inventing the wheel, and being goal driven, not prescriptive in how you work certainly struck chords with how we are trying to work in my team. Scott made some interesting observations about how scrum is quite prescriptive and is this really agile? I agreed with quite a few of his points on how what works for one team may not work for another. How a team works should be driven by context and reflection, not process and prescription. However was somewhat dubious about some of the statistics he rolled out towards the end. However, out of this keynote was born something that was to transcend this one presentation. During the talk, Scott mentioned on more than one occasion “In the real world”, and at one point made reference to people living in the land of unicorns and rainbows. The challenge was then laid down on twitter for all speakers to include a unicorn in their presentations… and for the most part this happened! It became an identity for this years conference, and I’m sure something that any attendee will always associate with Agile Testing Days 2012! Following this keynote, I attended “Going agile with Automated GUI Testing – Some personal insights” by Jan Zdunek from codecentric on the vendor track. My speciality is test automation, and in particular GUI testing, so this drew me to this talk more than the others. Thankfully, it was made clear from the very start that this was not peddling any particular product (even though it was on the vendor track), and Jan faithfully stuck to that. Most of the content was not new to me, but it was really comforting to hear someone else with very similar experiences to my own. In particular, things like how GUI testing is hard and is not a silver bullet; how record & replay is NOT a good thing to do (which drew a somewhat inflammatory tweet from an automation company when I tweeted that!). Something that I have started hearing around the place, and has certainly been murmuring at work is to push more of the automation coding onto the developers. After all they are the coding experts. I agree with this to a degree, but I personally enjoy coding and find it very rewarding doing so, therefore I’d be reluctant to give it up. I think there are some better alternatives such as pairing with a developer. Lastly, Jan mentioned, almost in passing, that we should consider virtualisation for gui testing for covering configuration combinations. On my project we’ve been running our win32/.NET GUI tests in cloud virtualisation for a couple of years now… I really should write about that! After lunch the second keynote of the day was by Lisa Crispin and Janet Gregory,”Myths about Agile Testing, De-Bunked”. It started off well… with the two ladies donning Medusa style head bands whilst they disbanding several myths about agile testing! I got the impression that it was perhaps not as slick as they would have liked, but then Janet was suffering with a very sore throat so kept losing her voice. Nevertheless, the presentation was captivating, and they debunked several myths such as : “Testing is dead”, “Testers must write code”, “Agile teams always deliver faster”. I didn’t take many notes for this because it was being recorded, but unfortunately the recordings have not been posted yet so I’ll write more about this when they are. The TestLab was held during a somewhat free for all time during most of the afternoon. It looked intriguing and proved to be one of the surprising experiences of the conference for me. Run by James Lyndsay and Bart Knaack, it consisted of a number of ‘stations’ that offered different testing problems. I opted for testing a mathematical drawing app call Geogebra, the task being to pair up and exploratory test it. After an allotted time, we discussed issues we’d found and decided if we wanted to continue ‘playing’ to which we all agreed! It was fun! The last track talk of the day was “Developers Exploratory Testing – Raising the bar” by Sigge Birgisson. One of the teams at Red Gate have tried Dev or Team exploratory testing a couple of times, and I was really interested to go to the presentation that prompted that. I was not disappointed! Sigge gave a first class presentation, and not only explained what DET was all about, but also how to go about implementing it. Little tips like calling it a ‘workshop’ rather than ‘testing’ I can really see working! Monday evening saw the presentation of the award for the Most Influential Agile Testing Professional Person go to a much deserved Lisa Crispin. The evening was great, with acrobatics, magic and music. My Takeaway Triple from Day 1:  Some of the cool stuff that was suggested in the GUI Testing talk, we are already doing. I should write about that! Testing is not dead! Perhaps testing will become more of a skill than a specific role, but it is certainly not dead. Team/Developer exploratory testing… seems like a no-brainer assuming you have a team who is willing.  Day 2 – Coming soon…

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  • Oracle Fusion Applications User Experience Design Patterns: Feeling the Love after Launch

    - by mvaughan
    By Misha Vaughan, Oracle Applications User ExperienceIn the first video by the Oracle Applications User Experience team on the Oracle Partner Network, Vice President Jeremy Ashley said that Oracle is looking to expand the ecosystem of support for Oracle’s applications customers as they begin to assess their investment and adoption of Oracle Fusion Applications. Oracle has made a massive investment to maintain the benefits of the Fusion Applications User Experience. This summer, the Applications User Experience team released the Oracle Fusion Applications user experience design patterns.Design patterns help create consistent experiences across devices.The launch has been very well received:Angelo Santagata, Senior Principal Technologist and Fusion Middleware evangelist for Oracle,  wrote this to the system integrator community: “The web site is the result of many years of Oracle R&D into user interface design for Fusion Applications and features a really cool web app which allows you to visualise the UI components in action.”  Grant Ronald, Director of Product Management, Application Development Framework (ADF) said: “It’s a science I don't understand, but now I don't have to ... Now you can learn from the UX experience of Fusion Applications.”Frank Nimphius, Senior Principal Product Manager, Oracle (ADF) wrote about the launch of the design patterns for the ADF Code Corner, and Jürgen Kress, Senior Manager EMEA Alliances & Channels for Fusion MiddleWare and Service Oriented Architecture, (SOA), shared the news with his Partner Community. Oracle Twitter followers also helped spread the message about the design patterns launch: ?@bex – Brian Huff, founder and Chief Software Architect for Bezzotech, and Oracle ACE Director:“Nifty! The Oracle Fusion UX team just released new ADF design patterns.”@maiko_rocha, Maiko Rocha, Oracle Consulting Solutions Architect and Oracle FMW engineer: “Haven't seen any other vendor offer such comprehensive UX Design Patterns catalog for free!”@zirous_chad, Chad Thompson, Senior Solutions Architect for Zirous, Inc. and ADF Developer:Wow - @ultan and company did a great job with the Fusion UX PatternsWhat is a user experience design pattern?A user experience design pattern is a re-usable, usability tested functional blueprint for a particular user experience.  Some examples are guided processes, shopping carts, and search and search results.  Ultan O’Broin discusses the top design patterns every developer should know.The patterns that were just released are based on thousands of hours of end-user field studies, state-of-the-art user interface assessments, and usability testing.  To be clear, these are functional design patterns, not technical design patterns that developers may be used to working with.  Because we know there is a gap, we are putting together some training that will help close that gap.Who should care?This is an offering targeted primarily at Application Development Framework (ADF) developers. If you are faced with the following questions regarding Fusion Applications, you will want to know and learn more:•    How do I build something that looks like Fusion Applications?•    How do I build a next-generation application?•    How do I extend a Fusion Application and maintain the user experience?•    I don’t want to re-invent the wheel on the user interface, so where do I start?•    I need to build something that will eventually co-exist with Fusion Applications. How do I do that?These questions are relevant to partners with an ADF competency, individual practitioners, or small consultancies with an ADF specialization, and customers who are trying to shift their IT staff over to supporting Fusion Applications.Where you can find out more?OnlineOur Fusion User Experience design patterns maven is Ultan O’Broin. The Oracle Partner Network is helping our team bring this first e-seminar to you in order to go into a more detail on what this means and how to take advantage of it:? Webinar: Build a Better User Experience with Oracle: Oracle Fusion Applications Functional Design PatternsSept 20, 2012 , 10:30am-11:30am PacificDial-In:  1. 877-664-9137 / Passcode 102546?International:  706-634-9619  http://www.intercall.com/national/oracleuniversity/gdnam.htmlAccess the Live Event Or Via Webconference Access http://ouweb.webex.com  ?and enter this session number: 598036234At a Usergroup eventThe Fusion User Experience Advocates (FXA) are also going to be getting some deep-dive training on this content and can share it with local user groups.At OpenWorld Ultan O’Broin               Chris MuirIf you will be at OpenWorld this year, our own Ultan O’Broin will be visiting the ADF demopod to say hello, thanks to Shay Shmeltzer, Senior Group Manager for ADF outbound communication and at the OTN lounge: Monday 10-10:45, Tuesday 2:15-2:45, Wednesday 2:15-3:30 ?  Oracle JDeveloper and Oracle ADF,  Moscone South, Right - S-207? “ADF Meet and Greett”, OTN Lounge, Wednesday 4:30 And I cannot talk about OpenWorld and ADF without mentioning Chris Muir’s ADF EMG event: the Year After the Year Of the ADF Developer – Sunday, Sept 30 of OpenWorld. Chris has played host to Ultan and the Applications user experience message for his online community and is now a seasoned UX expert.Expect to see additional announcements about expanded and training on similar topics in the future.

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  • Mouse takes a while to start working after boot

    - by warkior
    I just recently installed Ubuntu 12.04 (64 bit) and a number of my USB devices have stopped working. At least, they don't work for the first 3-5 minutes. I have two mice (one wireless, one wired) and a camera, which seem to take Ubuntu 3-5 minutes to recognize after booting up. Eventually, they do start to work, but it takes ages! lsusb results: (when the mice are working...) $ lsusb Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 005 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 006 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 007 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 003 Device 002: ID 046d:c512 Logitech, Inc. LX-700 Cordless Desktop Receiver Bus 003 Device 003: ID 03f0:3f11 Hewlett-Packard PSC-1315/PSC-1317 Bus 006 Device 002: ID 046d:c00c Logitech, Inc. Optical Wheel Mouse Bus 006 Device 003: ID 046d:c52b Logitech, Inc. Unifying Receiver syslog entries for what seems (to my very untrained eye) to be the problem: Oct 12 20:12:51 REMOVED-GA-MA785GM-US2H kernel: [ 17.420117] usb 2-3: device descriptor read/64, error -110 Oct 12 20:12:57 REMOVED-GA-MA785GM-US2H goa[1879]: goa-daemon version 3.4.0 starting [main.c:112, main()] Oct 12 20:13:06 REMOVED-GA-MA785GM-US2H kernel: [ 32.636107] usb 2-3: device descriptor read/64, error -110 Oct 12 20:13:06 REMOVED-GA-MA785GM-US2H kernel: [ 32.852122] usb 2-3: new high-speed USB device number 3 using ehci_hcd Oct 12 20:13:21 REMOVED-GA-MA785GM-US2H kernel: [ 47.964131] usb 2-3: device descriptor read/64, error -110 Oct 12 20:13:37 REMOVED-GA-MA785GM-US2H kernel: [ 63.180115] usb 2-3: device descriptor read/64, error -110 Oct 12 20:13:37 REMOVED-GA-MA785GM-US2H kernel: [ 63.396126] usb 2-3: new high-speed USB device number 4 using ehci_hcd Oct 12 20:13:47 REMOVED-GA-MA785GM-US2H kernel: [ 73.804158] usb 2-3: device not accepting address 4, error -110 Oct 12 20:13:47 REMOVED-GA-MA785GM-US2H kernel: [ 73.916190] usb 2-3: new high-speed USB device number 5 using ehci_hcd Oct 12 20:13:58 REMOVED-GA-MA785GM-US2H kernel: [ 84.324160] usb 2-3: device not accepting address 5, error -110 Oct 12 20:13:58 REMOVED-GA-MA785GM-US2H kernel: [ 84.324197] hub 2-0:1.0: unable to enumerate USB device on port 3 Oct 12 20:13:58 REMOVED-GA-MA785GM-US2H udev-configure-printer: failed to claim interface Oct 12 20:13:58 REMOVED-GA-MA785GM-US2H udev-configure-printer: Failed to get parent Oct 12 20:13:58 REMOVED-GA-MA785GM-US2H udev-configure-printer: device devpath is /devices/pci0000:00/0000:00:12.0/usb3/3-3 Oct 12 20:13:58 REMOVED-GA-MA785GM-US2H udev-configure-printer: MFG:hp MDL:psc 1310 series SERN:CN47CB60BJO2 serial:CN47CB60BJO2 Oct 12 20:13:58 REMOVED-GA-MA785GM-US2H kernel: [ 84.768132] usb 5-3: new full-speed USB device number 2 using ohci_hcd Oct 12 20:14:01 REMOVED-GA-MA785GM-US2H udev-configure-printer: no corresponding CUPS device found Oct 12 20:14:13 REMOVED-GA-MA785GM-US2H kernel: [ 99.904185] usb 5-3: device descriptor read/64, error -110 Oct 12 20:14:29 REMOVED-GA-MA785GM-US2H kernel: [ 115.144188] usb 5-3: device descriptor read/64, error -110 Oct 12 20:14:29 REMOVED-GA-MA785GM-US2H kernel: [ 115.384178] usb 5-3: new full-speed USB device number 3 using ohci_hcd Oct 12 20:14:44 REMOVED-GA-MA785GM-US2H kernel: [ 130.520196] usb 5-3: device descriptor read/64, error -110 Oct 12 20:14:59 REMOVED-GA-MA785GM-US2H kernel: [ 145.760179] usb 5-3: device descriptor read/64, error -110 Oct 12 20:14:59 REMOVED-GA-MA785GM-US2H kernel: [ 146.000173] usb 5-3: new full-speed USB device number 4 using ohci_hcd Oct 12 20:15:10 REMOVED-GA-MA785GM-US2H kernel: [ 156.408168] usb 5-3: device not accepting address 4, error -110 Oct 12 20:15:10 REMOVED-GA-MA785GM-US2H kernel: [ 156.544188] usb 5-3: new full-speed USB device number 5 using ohci_hcd Oct 12 20:15:20 REMOVED-GA-MA785GM-US2H kernel: [ 166.952181] usb 5-3: device not accepting address 5, error -110 Oct 12 20:15:20 REMOVED-GA-MA785GM-US2H kernel: [ 166.952215] hub 5-0:1.0: unable to enumerate USB device on port 3 Oct 12 20:15:21 REMOVED-GA-MA785GM-US2H kernel: [ 167.216164] usb 6-2: new low-speed USB device number 2 using ohci_hcd Oct 12 20:15:21 REMOVED-GA-MA785GM-US2H mtp-probe: checking bus 6, device 2: "/sys/devices/pci0000:00/0000:00:13.1/usb6/6-2" Oct 12 20:15:21 REMOVED-GA-MA785GM-US2H mtp-probe: bus: 6, device: 2 was not an MTP device Oct 12 20:15:21 REMOVED-GA-MA785GM-US2H kernel: [ 167.396138] input: Logitech USB Mouse as /devices/pci0000:00/0000:00:13.1/usb6/6-2/6-2:1.0/input/input16 Oct 12 20:15:21 REMOVED-GA-MA785GM-US2H kernel: [ 167.396442] generic-usb 0003:046D:C00C.0003: input,hidraw2: USB HID v1.10 Mouse [Logitech USB Mouse] on usb-0000:00:13.1-2/input0 Oct 12 20:15:21 REMOVED-GA-MA785GM-US2H kernel: [ 167.660187] usb 6-3: new full-speed USB device number 3 using ohci_hcd Oct 12 20:15:21 REMOVED-GA-MA785GM-US2H mtp-probe: checking bus 6, device 3: "/sys/devices/pci0000:00/0000:00:13.1/usb6/6-3" Oct 12 20:15:21 REMOVED-GA-MA785GM-US2H mtp-probe: bus: 6, device: 3 was not an MTP device Oct 12 20:15:21 REMOVED-GA-MA785GM-US2H kernel: [ 167.859045] logitech-djreceiver 0003:046D:C52B.0006: hiddev0,hidraw3: USB HID v1.11 Device [Logitech USB Receiver] on usb-0000:00:13.1-3/input2 Oct 12 20:15:21 REMOVED-GA-MA785GM-US2H kernel: [ 167.865086] input: Logitech Unifying Device. Wireless PID:400a as /devices/pci0000:00/0000:00:13.1/usb6/6-3/6-3:1.2/0003:046D:C52B.0006/input/input17 Oct 12 20:15:21 REMOVED-GA-MA785GM-US2H kernel: [ 167.865291] logitech-djdevice 0003:046D:C52B.0007: input,hidraw4: USB HID v1.11 Mouse [Logitech Unifying Device. Wireless PID:400a] on usb-0000:00:13.1-3:1 Oct 12 20:15:24 REMOVED-GA-MA785GM-US2H colord: io/hpmud/musb.c 139: unable get_string_descriptor -1: Operation not permitted Oct 12 20:15:24 REMOVED-GA-MA785GM-US2H colord: io/hpmud/musb.c 2040: invalid product id string ret=-1 Oct 12 20:15:24 REMOVED-GA-MA785GM-US2H colord: io/hpmud/musb.c 139: unable get_string_descriptor -1: Operation not permitted Oct 12 20:15:24 REMOVED-GA-MA785GM-US2H colord: io/hpmud/musb.c 2045: invalid serial id string ret=-1 Oct 12 20:15:24 REMOVED-GA-MA785GM-US2H colord: io/hpmud/musb.c 139: unable get_string_descriptor -1: Operation not permitted Oct 12 20:15:24 REMOVED-GA-MA785GM-US2H colord: io/hpmud/musb.c 2050: invalid manufacturer string ret=-1

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  • Silverlight Cream Monday WP7 App Review # 2

    - by Dave Campbell
    Today's Review (alphabetic order): GooNews, Grocery Shopping List, Need for Speed, SurfCube, and United Nations News. I'm a day late if these are going to be 'Monday' posts, but there are lots of apps, lots of goodness, and lots of email, so I might try to do 2 a week, we'll see. So once again I've got a small review of 5 apps that are either on my phone or have been. Disclaimers at the end. In this Issue:   GooNews is a very cool app from Shawn Wildermuth (AgiliTrain). I don't know if he uses this as a demo during his instruction, but it definitely serves a purpose... wanna pick up the top news items from Google on a never-ending basis? ... this is it. You can add your own keyword searches, and send stories to InstaPaper or share via email. I like this because it brings me the news quickly and updated, and works great. GooNews is by AgiliTrain and is Free This was a request by the author, and actually surprised me. I'm a big one for lists, but I would have just done a OneNote list to SkyDrive and to my phone. This app is a lot more than that, but will take you some setup to make it be 'yours'. For obvious reasons, there are no unit prices on things, so you have to set that up to get some idea of the cost of what you're shopping for. But if you do that, you'll get a nice total. Lots of thought went into the various categories and you can add your own. There's a bit of animation on the category selection that's nice. He seems to have covered all the bases necessary to use this, even shopping 'plans' that can be saved, and emailing of lists. As I said, I'm more of a raw list person, but if you take the time to set this up, it should work very nicely for you. Grocery Shopping List is by Grocery Shopper and is $0.99 ($1.99 after Feb 1) with a free trial. This was my 2nd commercial game I bought, and the one I've played the most. I ran the trial, thought it worked great, and bought it. I've had a lot of fun with this... there's no gas pedal.. your foot is in the carbeurator from the GO!, and unless you wanna tap the screen and brake like a little girl, just hang onto the steering wheel (the phone), and guide your way through. Hours of fun and challenges here. I like this because it's got some challenge to it, and the cars seem to be very realistic in their reactions. Need for Speed Undercover is by Electronic Arts is $4.99 and has a free trial. SurfCube Browser is another app by the folks that did the GuitarTuner I reviewed on Monday. You have to see SurfCube to believe it. You've probably seen the YouTube video, if not check SilverlightCream number 1017. The app works very solid, and just as the video demonstrates. I downloaded and tried this, and it immediately did 2 things: bought it, and pinned it to my start page. I like this because it's fun to work with, and it works great as a browser. I'm about *this* close to replacing the IE tile on my front page with SurfCube. SurfCube Browser is by Kinabalu Innovation Limited and is $1.99 and has a free trial. Coming in with another News app is United Nations News by Justin Angel. This is definitely a news aggregator for 'grown ups'... news, photos, videos, and radio broadcsts from the international community all in one very slick app. This is an amazingly well thought-out and complete app. Even better yet, Justin has the code on CodePlex. A very well-done International news aggregator. United Nations News is by Justin Angel and is Free. A few disclaimers: Feel free to write me about your app and tell me about it. While it would be very cool to receive a whole bunch of xap files to review, at this point, for technical reasons, I'm unable to side-load my device. Since I plan on only doing this one day a week (twice if I find time), and only 5, I may never get caught up, so if you send me some info, be patient. Re: games ... remember I'm old... I'm from the era of Colossal Cave and Zork. Duke-Nukem 2D and Captain Comic were awesome. I don't own an XBOX or any other game system, so take game reviews from my perspective -- who knows, it may be refreshing :) I won't pay for an app or game just to try it. If you expect me to test-drive your app, it's going to have to have a Free Trial. I'm still playing with the format, comments are welcome. I decided I should alphabetize the list today... so there's no order implied Let me know what you think of the idea of doing reviews, or the layout/whatever, and Stay in the 'Light! Twitter SilverlightNews | Twitter WynApse | WynApse.com | Tagged Posts | SilverlightCream Join me @ SilverlightCream | Phoenix Silverlight User Group Technorati Tags: Silverlight    Silverlight 3    Silverlight 4    Windows Phone MIX10

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  • Windows for IoT, continued

    - by Valter Minute
    Originally posted on: http://geekswithblogs.net/WindowsEmbeddedCookbook/archive/2014/08/05/windows-for-iot-continued.aspxI received many interesting feedbacks on my previous blog post and I tried to find some time to do some additional tests. Bert Kleinschmidt pointed out that pins 2,3 and 10 of the Galileo are connected directly to the SOC, while pin 13, the one used for the sample sketch is controlled via an I2C I/O expander. I changed my code to use pin 2 instead of 13 (just changing the variable assignment at the beginning of the code) and latency was greatly reduced. Now each pulse lasts for 1.44ms, 44% more than the expected time, but ways better that the result we got using pin 13. I also used SetThreadPriority to increase the priority of the thread that was running the sketch to THREAD_PRIORITY_HIGHEST but that didn't change the results. When I was using the I2C-controlled pin I tried the same and the timings got ways worse (increasing more than 10 times) and so I did not commented on that part, wanting to investigate the issua a bit more in detail. It seems that increasing the priority of the application thread impacts negatively the I2C communication. I tried to use also the Linux-based implementation (using a different Galileo board since the one provided by MS seems to use a different firmware) and the results of running the sample blink sketch modified to use pin 2 and blink the led for 1ms are similar to those we got on the same board running Windows. Here the difference between expected time and measured time is worse, getting around 3.2ms instead of 1 (320% compared to 150% using Windows but far from the 100.1% we got with the 8-bit Arduino). Both systems were not under load during the test, maybe loading some applications that use part of the CPU time would make those timings even less reliable, but I think that those numbers are enough to draw some conclusions. It may not be worth running a full OS if what you need is Arduino compatibility. The Arduino UNO is probably the best Arduino you can find to perform this kind of development. The Galileo running the Linux-based stack or running Windows for IoT is targeted to be a platform for "Internet of Things" devices, whatever that means. At the moment I don't see the "I" part of IoT. We have low level interfaces (SPI, I2C, the GPIO pins) that can be used to connect sensors but the support for connectivity is limited and the amount of work required to deliver some data to the cloud (using a secure HTTP request or a message queuing system like APMQS or MQTT) is still big and the rich OS underneath seems to not provide any help doing that.Why should I use sockets and can't access all the high level connectivity features we have on "full" Windows?I know that it's possible to use some third party libraries, try to build them using the Windows For IoT SDK etc. but this means re-inventing the wheel every time and can also lead to some IP concerns if used for products meant to be closed-source. I hope that MS and Intel (and others) will focus less on the "coolness" of running (some) Arduino sketches and more on providing a better platform to people that really want to design devices that leverage internet connectivity and the cloud processing power to deliver better products and services. Providing a reliable set of connectivity services would be a great start. Providing support for .NET would be even better, leaving native code available for hardware access etc. I know that those components may require additional storage and memory etc. So making the OS componentizable (or, at least, provide a way to install additional components) would be a great way to let developers pick the parts of the system they need to develop their solution, knowing that they will integrate well together. I can understand that the Arduino and Raspberry Pi* success may have attracted the attention of marketing departments worldwide and almost any new development board those days is promoted as "XXX response to Arduino" or "YYYY alternative to Raspberry Pi", but this is misleading and prevents companies from focusing on how to deliver good products and how to integrate "IoT" features with their existing offer to provide, at the end, a better product or service to their customers. Marketing is important, but can't decide the key features of a product (the OS) that is going to be used to develop full products for end customers integrating it with hardware and application software. I really like the "hackable" nature of open-source devices and like to see that companies are getting more and more open in releasing information, providing "hackable" devices and supporting developers with documentation, good samples etc. On the other side being able to run a sketch designed for an 8 bit microcontroller on a full-featured application processor may sound cool and an easy upgrade path for people that just experimented with sensors etc. on Arduino but it's not, in my humble opinion, the main path to follow for people who want to deliver real products.   *Shameless self-promotion: if you are looking for a good book in Italian about the Raspberry Pi , try mine: http://www.amazon.it/Raspberry-Pi-alluso-Digital-LifeStyle-ebook/dp/B00GYY3OKO

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  • Yes, I did it - Skydiving in Mauritius

    Finally, I did it or better said we did it. Already back in November last year I saw the big billboard advertisement of Skydive Austral Mauritius near Caudan Waterfront in Port Louis and decided for myself that this is going to be the perfect birthday gift for my wife. Simply out of curiosity I would join her tandem jump with a second instructor. Due to her pregnancy of our son I had to be patient... But then finally, her birthday had arrived and on our midnight celebration session I showed her her netbook with the website preloaded. Actually, it was the "perfect" timing... Recovery from her cesarean is fine, local weather conditions are gorgious and the children were under surveillance of my mum - spending her annual holidays on the island. So, after late wake-up in the morning, we packed our stuff and off we went. According to Google Maps direction indication we had to drive for roughly 50km (only) but traffic here in Mauritius is always challenging. The dropzone is at the Zone Industrielle Mon Loisir Sugar Estate near Riviere du Rempart at the northern east coast. Anyways, we were not in a hurry and arrived there shortly after noon. The access road to the airfield are just small down-driven paths through sugar cane fields and according to our daughter "it's bumpy!". True true true... The facilities at Skydive Austral Mauritius are complete except for food. Enough space for parking, easy handling at the reception and a lot to see for the kids. There's even a big terrace with several sets of tables and chairs, small bar for soft drinks, strictly non-alcoholic. The team over there is all welcoming and warm-hearthy! Having the kids with us was no issue at all. Quite the opposite, our daugther was allowed to discover a lot of things than we adults did. Even visiting the small air plane was on the menu for her. Really great stuff! While waiting for our turn we enjoyed watching other people getting ready in the jump gear, taking off with the Cessna, and finally coming back down on the tandem parachute. Actually, the different expressions on their faces was one of the best parts while waiting. Great mental preparation as my wife was getting more anxious about her first jump... {loadposition content_adsense} First, we got some information about the procedures on the plane about how to get seated, tight up with our instructors and how to get ready for the jump off the plane as soon as we arrive the height of 10.000 ft. All well explained and easy to understand after all.Next, we met with our jumpers Chris and Lee aka "Rasta" to get dressed and ready for take-off. Those guys are really cool and relaxed for their job. From that point on, the DVD session / recording for my wife's birthday started and we really had a lot of fun... The difference between that small Cessna and a commercial flight with an Airbus or a Boeing is astronomic! The climb up to 10.000 ft took us roughly 25 minutes and we enjoyed the magnificent view over the turquoise lagunes near Poste de Flacq, Lafayette and Isle d'Ambre on the north-east coast. After flying through the clouds we sun-bathed and looked over "iced-sugar covered" Mauritius. You might have a look at the picture gallery of Skydive Mauritius for better imagination. The moment of truth, or better said, point of no return came after approximately 25 minutes. The door opens, moving into position on the side on top of the wheel and... out! Back flip and free fall! Slight turns and Wooooohooooo! through the clouds... It so amazing and breath-taking! So undescribable! You have to experience this yourself! Some seconds later the parachute opened and we glided smoothly with some turns and spins back down to the dropzone. The rest of the family could hear and see us soon and the landing was easy going. We never had any doubts or fear about our instructors. They did a great job and we are looking forward to book our next job. I might even consider to follow educational classes on skydiving and earn a license. By the way, feel free to get in touch with Skydive Austral Mauritius. Either via contact details on their website or tweeting a little bit with them. Follow the tweets of Chris and fellows on SkydiveAustral.

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  • How do I cleanly design a central render/animation loop?

    - by mtoast
    I'm learning some graphics programming, and am in the midst of my first such project of any substance. But, I am really struggling at the moment with how to architect it cleanly. Let me explain. To display complicated graphics in my current language of choice (JavaScript -- have you heard of it?), you have to draw graphical content onto a <canvas> element. And to do animation, you must clear the <canvas> after every frame (unless you want previous graphics to remain). Thus, most canvas-related JavaScript demos I've seen have a function like this: function render() { clearCanvas(); // draw stuff here requestAnimationFrame(render); } render, as you may surmise, encapsulates the drawing of a single frame. What a single frame contains at a specific point in time, well... that is determined by the program state. So, in order for my program to do its thing, I just need to look at the state, and decide what to render. Right? Right. But that is more complicated than it seems. My program is called "Critter Clicker". In my program, you see several cute critters bouncing around the screen. Clicking on one of them agitates it, making it bounce around even more. There is also a start screen, which says "Click to start!" prior to the critters being displayed. Here are a few of the objects I'm working with in my program: StartScreenView // represents the start screen CritterTubView // represents the area in which the critters live CritterList // a collection of all the critters Critter // a single critter model CritterView // view of a single critter Nothing too egregious with this, I think. Yet, when I set out to flesh out my render function, I get stuck, because everything I write seems utterly ugly and reminiscent of a certain popular Italian dish. Here are a couple of approaches I've attempted, with my internal thought process included, and unrelated bits excluded for clarity. Approach 1: "It's conditions all the way down" // "I'll just write the program as I think it, one frame at a time." if (assetsLoaded) { if (userClickedToStart) { if (critterTubDisplayed) { if (crittersDisplayed) { forEach(crittersList, function(c) { if (c.wasClickedRecently) { c.getAgitated(); } }); } else { displayCritters(); } } else { displayCritterTub(); } } else { displayStartScreen(); } } That's a very much simplified example. Yet even with only a fraction of all the rendering conditions visible, render is already starting to get out of hand. So, I dispense with that and try another idea: Approach 2: Under the Rug // "Each view object shall be responsible for its own rendering. // "I'll pass each object the program state, and each can render itself." startScreen.render(state); critterTub.render(state); critterList.render(state); In this setup, I've essentially just pushed those crazy nested conditions to a deeper level in the code, hiding them from view. In other words, startScreen.render would check state to see if it needed actually to be drawn or not, and take the correct action. But this seems more like it only solves a code-aesthetic problem. The third and final approach I'm considering that I'll share is the idea that I could invent my own "wheel" to take care of this. I'm envisioning a function that takes a data structure that defines what should happen at any given point in the render call -- revealing the conditions and dependencies as a kind of tree. Approach 3: Mad Scientist renderTree({ phases: ['startScreen', 'critterTub', 'endCredits'], dependencies: { startScreen: ['assetsLoaded'], critterTub: ['startScreenClicked'], critterList ['critterTubDisplayed'] // etc. }, exclusions: { startScreen: ['startScreenClicked'], // etc. } }); That seems kind of cool. I'm not exactly sure how it would actually work, but I can see it being a rather nifty way to express things, especially if I flex some of JavaScript's events. In any case, I'm a little bit stumped because I don't see an obvious way to do this. If you couldn't tell, I'm coming to this from the web development world, and finding that doing animation is a bit more exotic than arranging an MVC application for handling simple requests - responses. What is the clean, established solution to this common-I-would-think problem?

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  • C#/.NET Little Wonders: Getting Caller Information

    - by James Michael Hare
    Originally posted on: http://geekswithblogs.net/BlackRabbitCoder/archive/2013/07/25/c.net-little-wonders-getting-caller-information.aspx Once again, in this series of posts I look at the parts of the .NET Framework that may seem trivial, but can help improve your code by making it easier to write and maintain. The index of all my past little wonders posts can be found here. There are times when it is desirable to know who called the method or property you are currently executing.  Some applications of this could include logging libraries, or possibly even something more advanced that may server up different objects depending on who called the method. In the past, we mostly relied on the System.Diagnostics namespace and its classes such as StackTrace and StackFrame to see who our caller was, but now in C# 5, we can also get much of this data at compile-time. Determining the caller using the stack One of the ways of doing this is to examine the call stack.  The classes that allow you to examine the call stack have been around for a long time and can give you a very deep view of the calling chain all the way back to the beginning for the thread that has called you. You can get caller information by either instantiating the StackTrace class (which will give you the complete stack trace, much like you see when an exception is generated), or by using StackFrame which gets a single frame of the stack trace.  Both involve examining the call stack, which is a non-trivial task, so care should be done not to do this in a performance-intensive situation. For our simple example let's say we are going to recreate the wheel and construct our own logging framework.  Perhaps we wish to create a simple method Log which will log the string-ified form of an object and some information about the caller.  We could easily do this as follows: 1: static void Log(object message) 2: { 3: // frame 1, true for source info 4: StackFrame frame = new StackFrame(1, true); 5: var method = frame.GetMethod(); 6: var fileName = frame.GetFileName(); 7: var lineNumber = frame.GetFileLineNumber(); 8: 9: // we'll just use a simple Console write for now 10: Console.WriteLine("{0}({1}):{2} - {3}", 11: fileName, lineNumber, method.Name, message); 12: } So, what we are doing here is grabbing the 2nd stack frame (the 1st is our current method) using a 2nd argument of true to specify we want source information (if available) and then taking the information from the frame.  This works fine, and if we tested it out by calling from a file such as this: 1: // File c:\projects\test\CallerInfo\CallerInfo.cs 2:  3: public class CallerInfo 4: { 5: Log("Hello Logger!"); 6: } We'd see this: 1: c:\projects\test\CallerInfo\CallerInfo.cs(5):Main - Hello Logger! This works well, and in fact CallStack and StackFrame are still the best ways to examine deeper into the call stack.  But if you only want to get information on the caller of your method, there is another option… Determining the caller at compile-time In C# 5 (.NET 4.5) they added some attributes that can be supplied to optional parameters on a method to receive caller information.  These attributes can only be applied to methods with optional parameters with explicit defaults.  Then, as the compiler determines who is calling your method with these attributes, it will fill in the values at compile-time. These are the currently supported attributes available in the  System.Runtime.CompilerServices namespace": CallerFilePathAttribute – The path and name of the file that is calling your method. CallerLineNumberAttribute – The line number in the file where your method is being called. CallerMemberName – The member that is calling your method. So let’s take a look at how our Log method would look using these attributes instead: 1: static int Log(object message, 2: [CallerMemberName] string memberName = "", 3: [CallerFilePath] string fileName = "", 4: [CallerLineNumber] int lineNumber = 0) 5: { 6: // we'll just use a simple Console write for now 7: Console.WriteLine("{0}({1}):{2} - {3}", 8: fileName, lineNumber, memberName, message); 9: } Again, calling this from our sample Main would give us the same result: 1: c:\projects\test\CallerInfo\CallerInfo.cs(5):Main - Hello Logger! However, though this seems the same, there are a few key differences. First of all, there are only 3 supported attributes (at this time) that give you the file path, line number, and calling member.  Thus, it does not give you as rich of detail as a StackFrame (which can give you the calling type as well and deeper frames, for example).  Also, these are supported through optional parameters, which means we could call our new Log method like this: 1: // They're defaults, why not fill 'em in 2: Log("My message.", "Some member", "Some file", -13); In addition, since these attributes require optional parameters, they cannot be used in properties, only in methods. These caveats aside, they do let you get similar information inside of methods at a much greater speed!  How much greater?  Well lets crank through 1,000,000 iterations of each.  instead of logging to console, I’ll return the formatted string length of each.  Doing this, we get: 1: Time for 1,000,000 iterations with StackTrace: 5096 ms 2: Time for 1,000,000 iterations with Attributes: 196 ms So you see, using the attributes is much, much faster!  Nearly 25x faster in fact.  Summary There are a few ways to get caller information for a method.  The StackFrame allows you to get a comprehensive set of information spanning the whole call stack, but at a heavier cost.  On the other hand, the attributes allow you to quickly get at caller information baked in at compile-time, but to do so you need to create optional parameters in your methods to support it. Technorati Tags: Little Wonders,CSharp,C#,.NET,StackFrame,CallStack,CallerFilePathAttribute,CallerLineNumberAttribute,CallerMemberName

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  • PanelGridLayout - A Layout Revolution

    - by Duncan Mills
    With the most recent 11.1.2 patchset (11.1.2.3) there has been a lot of excitement around ADF Essentials (and rightly so), however, in all the fuss I didn't want an even more significant change to get missed - yes you read that correctly, a more significant change! I'm talking about the new panelGridLayout component, I can confidently say that this one of the most revolutionary components that we've introduced in 11g, even though it sounds rather boring. To be totally accurate, panelGrid was introduced in 11.1.2.2 but without any presence in the component palette or other design time support, so it was largely missed unless you read the release notes. However in this latest patchset it's finally front and center. Its time to explore - we (really) need to talk about layout.  Let's face it,with ADF Faces rich client, layout is a rather arcane pursuit, once you are a layout master, all bow before you, but it's more of an art than a science, and it is often, in fact, way too difficult to achieve what should (apparently) be a pretty simple. Here's a great example, it's a homework assignment I set for folks I'm teaching this stuff to:  The requirements for this layout are: The header is 80px high, the footer is 30px. These are both fixed.  The first section of the header containing the logo is 180px wide The logo is centered within the top left hand corner of the header  The title text is start aligned in the center zone of the header and will wrap if the browser window is narrowed. It should be aligned in the center of the vertical space  The about link is anchored to the right hand side of the browser with a 20px gap and again is center aligned vertically. It will move as the browser window is reduced in width. The footer has a right aligned copyright statement, again middle aligned within a 30px high footer region and with a 20px buffer to the right hand edge. It will move as the browser window is reduced in width. All remaining space is given to a central zone, which, in this case contains a panelSplitter. Expect that at some point in time you'll need a separate messages line in the center of the footer.  In the homework assigment I set I also stipulate that no inlineStyles can be used to control alignment or margins and no use of other taglibs (e.g. JSF HTML or Trinidad HTML). So, if we take this purist approach, that basic page layout (in my stock solution) requires 3 panelStretchLayouts, 5 panelGroupLayouts and 4 spacers - not including the spacer I use for the logo and the contents of the central zone splitter - phew! The point is that even a seemingly simple layout needs a bit of thinking about, particulatly when you consider strechting and browser re-size behavior. In fact, this little sample actually teaches you much of what you need to know to become vaguely competant at layouts in the framework. The underlying result of "the way things are" is that most of us reach for panelStretchLayout before even finishing the first sip of coffee as we embark on a new page design. In fact most pages you will see in any moderately complex ADF page will basically be nested panelStretchLayouts and panelGroupLayouts, sometimes many, many levels deep. So this is a problem, we've known this for some time and now we have a good solution. (I should point out that the oft-used Trinidad trh tags are not a particularly good solution as you're tie-ing yourself to an HTML table based layout in that case with a host of attendent issues in resize and bi-di behavior, but I digress.) So, tadaaa, I give to you panelGridLayout. PanelGrid, as the name suggests takes a grid like (dare I say slightly gridbag-like) approach to layout, dividing your layout into rows and colums with margins, sizing, stretch behaviour, colspans and rowspans all rolled in, all without the use of inlineStyle. As such, it provides for a much more powerful and consise way of defining a layout such as the one above that is actually simpler and much more logical to design. The basic building blocks are the panelGridLayout itself, gridRow and gridCell. Your content sits inside the cells inside the rows, all helpfully allowing both streching, valign and halign definitions without the need to nest further panelGroupLayouts. So much simpler!  If I break down the homework example above my nested comglomorate of 12 containers and spacers can be condensed down into a single panelGrid with 3 rows and 5 cell definitions (39 lines of source reduced to 24 in the case of the sample). What's more, the actual runtime representation in the browser DOM is much, much simpler, and clean, with basically one DIV per cell (Note that just because the panelGridLayout semantics looks like an HTML table does not mean that it's rendered that way!) . Another hidden benefit is the runtime cost. Because we can use a single layout to achieve much more complex geometries the client side layout code inside the browser is having to work a lot less. This will be a real benefit if your application needs to run on lower powered clients such as netbooks or tablets. So, it's time, if you're on 11.1.2.2 or above, to smile warmly at your panelStretchLayouts, wrap the blanket around it's knees and wheel it off to the Sunset Retirement Home for a well deserved rest. There's a new kid on the block and it wants to be your friend. 

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  • Optimizing a thread safe Java NIO / Serialization / FIFO Queue [migrated]

    - by trialcodr
    I've written a thread safe, persistent FIFO for Serializable items. The reason for reinventing the wheel is that we simply can't afford any third party dependencies in this project and want to keep this really simple. The problem is it isn't fast enough. Most of it is undoubtedly due to reading and writing directly to disk but I think we should be able to squeeze a bit more out of it anyway. Any ideas on how to improve the performance of the 'take'- and 'add'-methods? /** * <code>DiskQueue</code> Persistent, thread safe FIFO queue for * <code>Serializable</code> items. */ public class DiskQueue<ItemT extends Serializable> { public static final int EMPTY_OFFS = -1; public static final int LONG_SIZE = 8; public static final int HEADER_SIZE = LONG_SIZE * 2; private InputStream inputStream; private OutputStream outputStream; private RandomAccessFile file; private FileChannel channel; private long offs = EMPTY_OFFS; private long size = 0; public DiskQueue(String filename) { try { boolean fileExists = new File(filename).exists(); file = new RandomAccessFile(filename, "rwd"); if (fileExists) { size = file.readLong(); offs = file.readLong(); } else { file.writeLong(size); file.writeLong(offs); } } catch (FileNotFoundException e) { throw new RuntimeException(e); } catch (IOException e) { throw new RuntimeException(e); } channel = file.getChannel(); inputStream = Channels.newInputStream(channel); outputStream = Channels.newOutputStream(channel); } /** * Add item to end of queue. */ public void add(ItemT item) { try { synchronized (this) { channel.position(channel.size()); ObjectOutputStream s = new ObjectOutputStream(outputStream); s.writeObject(item); s.flush(); size++; file.seek(0); file.writeLong(size); if (offs == EMPTY_OFFS) { offs = HEADER_SIZE; file.writeLong(offs); } notify(); } } catch (IOException e) { throw new RuntimeException(e); } } /** * Clears overhead by moving the remaining items up and shortening the file. */ public synchronized void defrag() { if (offs > HEADER_SIZE && size > 0) { try { long totalBytes = channel.size() - offs; ByteBuffer buffer = ByteBuffer.allocateDirect((int) totalBytes); channel.position(offs); for (int bytes = 0; bytes < totalBytes;) { int res = channel.read(buffer); if (res == -1) { throw new IOException("Failed to read data into buffer"); } bytes += res; } channel.position(HEADER_SIZE); buffer.flip(); for (int bytes = 0; bytes < totalBytes;) { int res = channel.write(buffer); if (res == -1) { throw new IOException("Failed to write buffer to file"); } bytes += res; } offs = HEADER_SIZE; file.seek(LONG_SIZE); file.writeLong(offs); file.setLength(HEADER_SIZE + totalBytes); } catch (IOException e) { throw new RuntimeException(e); } } } /** * Returns the queue overhead in bytes. */ public synchronized long overhead() { return (offs == EMPTY_OFFS) ? 0 : offs - HEADER_SIZE; } /** * Returns the first item in the queue, blocks if queue is empty. */ public ItemT peek() throws InterruptedException { block(); synchronized (this) { if (offs != EMPTY_OFFS) { return readItem(); } } return peek(); } /** * Returns the number of remaining items in queue. */ public synchronized long size() { return size; } /** * Removes and returns the first item in the queue, blocks if queue is empty. */ public ItemT take() throws InterruptedException { block(); try { synchronized (this) { if (offs != EMPTY_OFFS) { ItemT result = readItem(); size--; offs = channel.position(); file.seek(0); if (offs == channel.size()) { truncate(); } file.writeLong(size); file.writeLong(offs); return result; } } return take(); } catch (IOException e) { throw new RuntimeException(e); } } /** * Throw away all items and reset the file. */ public synchronized void truncate() { try { offs = EMPTY_OFFS; file.setLength(HEADER_SIZE); size = 0; } catch (IOException e) { throw new RuntimeException(e); } } /** * Block until an item is available. */ protected void block() throws InterruptedException { while (offs == EMPTY_OFFS) { try { synchronized (this) { wait(); file.seek(LONG_SIZE); offs = file.readLong(); } } catch (IOException e) { throw new RuntimeException(e); } } } /** * Read and return item. */ @SuppressWarnings("unchecked") protected ItemT readItem() { try { channel.position(offs); return (ItemT) new ObjectInputStream(inputStream).readObject(); } catch (ClassNotFoundException e) { throw new RuntimeException(e); } catch (IOException e) { throw new RuntimeException(e); } } }

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  • Increasing efficiency of N-Body gravity simulation

    - by Postman
    I'm making a space exploration type game, it will have many planets and other objects that will all have realistic gravity. I currently have a system in place that works, but if the number of planets goes above 70, the FPS decreases an practically exponential rates. I'm making it in C# and XNA. My guess is that I should be able to do gravity calculations between 100 objects without this kind of strain, so clearly my method is not as efficient as it should be. I have two files, Gravity.cs and EntityEngine.cs. Gravity manages JUST the gravity calculations, EntityEngine creates an instance of Gravity and runs it, along with other entity related methods. EntityEngine.cs public void Update() { foreach (KeyValuePair<string, Entity> e in Entities) { e.Value.Update(); } gravity.Update(); } (Only relevant piece of code from EntityEngine, self explanatory. When an instance of Gravity is made in entityEngine, it passes itself (this) into it, so that gravity can have access to entityEngine.Entities (a dictionary of all planet objects)) Gravity.cs namespace ExplorationEngine { public class Gravity { private EntityEngine entityEngine; private Vector2 Force; private Vector2 VecForce; private float distance; private float mult; public Gravity(EntityEngine e) { entityEngine = e; } public void Update() { //First loop foreach (KeyValuePair<string, Entity> e in entityEngine.Entities) { //Reset the force vector Force = new Vector2(); //Second loop foreach (KeyValuePair<string, Entity> e2 in entityEngine.Entities) { //Make sure the second value is not the current value from the first loop if (e2.Value != e.Value ) { //Find the distance between the two objects. Because Fg = G * ((M1 * M2) / r^2), using Vector2.Distance() and then squaring it //is pointless and inefficient because distance uses a sqrt, squaring the result simple cancels that sqrt. distance = Vector2.DistanceSquared(e2.Value.Position, e.Value.Position); //This makes sure that two planets do not attract eachother if they are touching, completely unnecessary when I add collision, //For now it just makes it so that the planets are not glitchy, performance is not significantly improved by removing this IF if (Math.Sqrt(distance) > (e.Value.Texture.Width / 2 + e2.Value.Texture.Width / 2)) { //Calculate the magnitude of Fg (I'm using my own gravitational constant (G) for the sake of time (I know it's 1 at the moment, but I've been changing it) mult = 1.0f * ((e.Value.Mass * e2.Value.Mass) / distance); //Calculate the direction of the force, simply subtracting the positions and normalizing works, this fixes diagonal vectors //from having a larger value, and basically makes VecForce a direction. VecForce = e2.Value.Position - e.Value.Position; VecForce.Normalize(); //Add the vector for each planet in the second loop to a force var. Force = Vector2.Add(Force, VecForce * mult); //I have tried Force += VecForce * mult, and have not noticed much of an increase in speed. } } } //Add that force to the first loop's planet's position (later on I'll instead add to acceleration, to account for inertia) e.Value.Position += Force; } } } } I have used various tips (about gravity optimizing, not threading) from THIS question (that I made yesterday). I've made this gravity method (Gravity.Update) as efficient as I know how to make it. This O(N^2) algorithm still seems to be eating up all of my CPU power though. Here is a LINK (google drive, go to File download, keep .Exe with the content folder, you will need XNA Framework 4.0 Redist. if you don't already have it) to the current version of my game. Left click makes a planet, right click removes the last planet. Mouse moves the camera, scroll wheel zooms in and out. Watch the FPS and Planet Count to see what I mean about performance issues past 70 planets. (ALL 70 planets must be moving, I've had 100 stationary planets and only 5 or so moving ones while still having 300 fps, the issue arises when 70+ are moving around) After 70 planets are made, performance tanks exponentially. With < 70 planets, I get 330 fps (I have it capped at 300). At 90 planets, the FPS is about 2, more than that and it sticks around at 0 FPS. Strangely enough, when all planets are stationary, the FPS climbs back up to around 300, but as soon as something moves, it goes right back down to what it was, I have no systems in place to make this happen, it just does. I considered multithreading, but that previous question I asked taught me a thing or two, and I see now that that's not a viable option. I've also thought maybe I could do the calculations on my GPU instead, though I don't think it should be necessary. I also do not know how to do this, it is not a simple concept and I want to avoid it unless someone knows a really noob friendly simple way to do it that will work for an n-body gravity calculation. (I have an NVidia gtx 660) Lastly I've considered using a quadtree type system. (Barnes Hut simulation) I've been told (in the previous question) that this is a good method that is commonly used, and it seems logical and straightforward, however the implementation is way over my head and I haven't found a good tutorial for C# yet that explains it in a way I can understand, or uses code I can eventually figure out. So my question is this: How can I make my gravity method more efficient, allowing me to use more than 100 objects (I can render 1000 planets with constant 300+ FPS without gravity calculations), and if I can't do much to improve performance (including some kind of quadtree system), could I use my GPU to do the calculations?

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  • Is it feasible and useful to auto-generate some code of unit tests?

    - by skiwi
    Earlier today I have come up with an idea, based upon a particular real use case, which I would want to have checked for feasability and usefulness. This question will feature a fair chunk of Java code, but can be applied to all languages running inside a VM, and maybe even outside. While there is real code, it uses nothing language-specific, so please read it mostly as pseudo code. The idea Make unit testing less cumbersome by adding in some ways to autogenerate code based on human interaction with the codebase. I understand this goes against the principle of TDD, but I don't think anyone ever proved that doing TDD is better over first creating code and then immediatly therafter the tests. This may even be adapted to be fit into TDD, but that is not my current goal. To show how it is intended to be used, I'll copy one of my classes here, for which I need to make unit tests. public class PutMonsterOnFieldAction implements PlayerAction { private final int handCardIndex; private final int fieldMonsterIndex; public PutMonsterOnFieldAction(final int handCardIndex, final int fieldMonsterIndex) { this.handCardIndex = Arguments.requirePositiveOrZero(handCardIndex, "handCardIndex"); this.fieldMonsterIndex = Arguments.requirePositiveOrZero(fieldMonsterIndex, "fieldCardIndex"); } @Override public boolean isActionAllowed(final Player player) { Objects.requireNonNull(player, "player"); Hand hand = player.getHand(); Field field = player.getField(); if (handCardIndex >= hand.getCapacity()) { return false; } if (fieldMonsterIndex >= field.getMonsterCapacity()) { return false; } if (field.hasMonster(fieldMonsterIndex)) { return false; } if (!(hand.get(handCardIndex) instanceof MonsterCard)) { return false; } return true; } @Override public void performAction(final Player player) { Objects.requireNonNull(player); if (!isActionAllowed(player)) { throw new PlayerActionNotAllowedException(); } Hand hand = player.getHand(); Field field = player.getField(); field.setMonster(fieldMonsterIndex, (MonsterCard)hand.play(handCardIndex)); } } We can observe the need for the following tests: Constructor test with valid input Constructor test with invalid inputs isActionAllowed test with valid input isActionAllowed test with invalid inputs performAction test with valid input performAction test with invalid inputs My idea mainly focuses on the isActionAllowed test with invalid inputs. Writing these tests is not fun, you need to ensure a number of conditions and you check whether it really returns false, this can be extended to performAction, where an exception needs to be thrown in that case. The goal of my idea is to generate those tests, by indicating (through GUI of IDE hopefully) that you want to generate tests based on a specific branch. The implementation by example User clicks on "Generate code for branch if (handCardIndex >= hand.getCapacity())". Now the tool needs to find a case where that holds. (I haven't added the relevant code as that may clutter the post ultimately) To invalidate the branch, the tool needs to find a handCardIndex and hand.getCapacity() such that the condition >= holds. It needs to construct a Player with a Hand that has a capacity of at least 1. It notices that the capacity private int of Hand needs to be at least 1. It searches for ways to set it to 1. Fortunately it finds a constructor that takes the capacity as an argument. It uses 1 for this. Some more work needs to be done to succesfully construct a Player instance, involving the creation of objects that have constraints that can be seen by inspecting the source code. It has found the hand with the least capacity possible and is able to construct it. Now to invalidate the test it will need to set handCardIndex = 1. It constructs the test and asserts it to be false (the returned value of the branch) What does the tool need to work? In order to function properly, it will need the ability to scan through all source code (including JDK code) to figure out all constraints. Optionally this could be done through the javadoc, but that is not always used to indicate all constraints. It could also do some trial and error, but it pretty much stops if you cannot attach source code to compiled classes. Then it needs some basic knowledge of what the primitive types are, including arrays. And it needs to be able to construct some form of "modification trees". The tool knows that it needs to change a certain variable to a different value in order to get the correct testcase. Hence it will need to list all possible ways to change it, without using reflection obviously. What this tool will not replace is the need to create tailored unit tests that tests all kinds of conditions when a certain method actually works. It is purely to be used to test methods when they invalidate constraints. My questions: Is creating such a tool feasible? Would it ever work, or are there some obvious problems? Would such a tool be useful? Is it even useful to automatically generate these testcases at all? Could it be extended to do even more useful things? Does, by chance, such a project already exist and would I be reinventing the wheel? If not proven useful, but still possible to make such thing, I will still consider it for fun. If it's considered useful, then I might make an open source project for it depending on the time. For people searching more background information about the used Player and Hand classes in my example, please refer to this repository. At the time of writing the PutMonsterOnFieldAction has not been uploaded to the repo yet, but this will be done once I'm done with the unit tests.

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  • Does .NET have a built in IEnumerable for multiple collections?

    - by Bryce Wagner
    I need an easy way to iterate over multiple collections without actually merging them, and I couldn't find anything built into .NET that looks like it does that. It feels like this should be a somewhat common situation. I don't want to reinvent the wheel. Is there anything built in that does something like this: public class MultiCollectionEnumerable<T> : IEnumerable<T> { private MultiCollectionEnumerator<T> enumerator; public MultiCollectionEnumerable(params IEnumerable<T>[] collections) { enumerator = new MultiCollectionEnumerator<T>(collections); } public IEnumerator<T> GetEnumerator() { enumerator.Reset(); return enumerator; } IEnumerator IEnumerable.GetEnumerator() { enumerator.Reset(); return enumerator; } private class MultiCollectionEnumerator<T> : IEnumerator<T> { private IEnumerable<T>[] collections; private int currentIndex; private IEnumerator<T> currentEnumerator; public MultiCollectionEnumerator(IEnumerable<T>[] collections) { this.collections = collections; this.currentIndex = -1; } public T Current { get { if (currentEnumerator != null) return currentEnumerator.Current; else return default(T); } } public void Dispose() { if (currentEnumerator != null) currentEnumerator.Dispose(); } object IEnumerator.Current { get { return Current; } } public bool MoveNext() { if (currentIndex >= collections.Length) return false; if (currentIndex < 0) { currentIndex = 0; if (collections.Length > 0) currentEnumerator = collections[0].GetEnumerator(); else return false; } while (!currentEnumerator.MoveNext()) { currentEnumerator.Dispose(); currentEnumerator = null; currentIndex++; if (currentIndex >= collections.Length) return false; currentEnumerator = collections[currentIndex].GetEnumerator(); } return true; } public void Reset() { if (currentEnumerator != null) { currentEnumerator.Dispose(); currentEnumerator = null; } this.currentIndex = -1; } } }

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  • Does my fat-client application belong in the MVC pattern?

    - by boatingcow
    The web-based application I’m currently working on is growing arms and legs! It’s basically an administration system which helps users to keep track of bookings, user accounts, invoicing etc. It can also be accessed via a couple of different websites using a fairly crude API. The fat-client design loosely follows the MVC pattern (or perhaps MVP) with a php/MySQL backend, Front Controller, several dissimilar Page Controllers, a liberal smattering of object-oriented and procedural Models, a confusing bunch of Views and templates, some JavaScripts, CSS files and Flash objects. The programmer in me is a big fan of the principle of “Separation of Concerns” and on that note, I’m currently trying to figure out the best way to separate and combine the various concerns as the project grows and more people contribute to it. The problem we’re facing is that although JavaScript (or Flash with ActionScript) is normally written with the template, hence part of the View and decoupled from the Controller and Model, we find that it actually encompasses the entire MVC pattern... Swap an image with an onmouseover event - that’s Behaviour. Render a datagrid - we’re manipulating the View. Send the result of reordering a list via AJAX - now we’re in Control. Check a form field to see if an email address is in a valid format - we’re consulting the Model. Is it wise to let the database people write up the validation Model with jQuery? Can the php programmers write the necessary Control structures in JavaScript? Can the web designers really write a functional AJAX form for their View? Should there be a JavaScript overlord for every project? If the MVC pattern could be applied to the people instead of the code, we would end up with this: Model - the database boffins - “SELECT * FROM mind WHERE interested IS NULL” Control - pesky programmers - “class Something extends NothingAbstractClass{…}” View - traditionally the domain of the graphic/web designer - “” …and a new layer: Behaviour - interaction and feedback designer - “CSS3 is the new black…” So, we’re refactoring and I’d like to stick to best practice design, but I’m not sure how to proceed. I don’t want to reinvent the wheel, so would anyone have any hints or tips as to what pattern I should be looking at or any code samples from someone who’s already done the dirty work? As the programmer guy, how can I rewrite the app for backend and front end whilst keeping the two separate? And before you ask, yes I’ve looked at Zend, CodeIgnitor, Symfony, etc., and no, they don’t seem to cross the boundary between server logic and client logic!

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  • KISS: Simple C# application which communicates with a RESTful web service.

    - by Workshop Alex
    Following the KISS principle, I suddenly realised the following: In .NET, you can use the Entity Model Framework to wrap around a database. This model can be exposed as a web service through WCF. This web service would have a very standardized definition. A client application could be created which could consume any such RESTful web service. I don't want to re-invent the wheel and it wouldn't surprise me if someone has already done this, so my question is simple: Has anyone already created a simple (desktop, not web) client application that can consume a RESTful service that's based on the Entity Framework and which will allow the user to read and write data directly to this service? Otherwise, I'll just have to "invent" this myself. :-)Problem is, the database layer and RESTful service is already finished. The RESTful service will only stay in the project during it's development phase, since we can use the database-layer assembly directly from the web applications that are build around it. When the web application is deployed, the RESTful services are just kept out of the deployment. But the database has a lot of data to manage over nearly 50 tables. When developing against a local database, we can have straight access to the database so I wouldn't need this tool for this. When it's deployed, the web application would be the only way to access the data so I could not use this tool. But we're also having a test phase where the database is stored on another system outside the local domain and this database is not available for developers. Only administrators have direct access to this database, making tests a bit more complex. However, through the RESTful service, I can still access the data directly. Thus, when some test goes wrong, I can repair the data through this connection or just create a copy of the data for tests on my local system. There's plenty of other functionality and it's even possible to just open the URL to a table service straight in Excel or XMLSpy to see the contents. But when I want to write something back, I have to write special code to do just that. A generic tool that would allow me to access the data and modify it would be easier. Since it's a generic setup around the ADO.NET Data services, this should be reasonable easy too. Thus, I can do it but hoped someone else has already done something similar. But it appears that there's no such tool made yet...

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  • How to store wiki sites (vcs)

    - by Eugen
    Hello, as a personal project I am trying to write a wiki with the help of django. I'm a beginner when it comes to web development. I am at the (early) point where I need to decide how to store the wiki sites. I have three approaches in mind and would like to know your suggestion. Flat files I considered a flat file approach with a version control system like git or mercurial. Firstly, I would have some example wikis to look at like http://hatta.sheep.art.pl/. Secondly, the vcs would probably deal with editing conflicts and keeping the edit history, so I would not have to reinvent the wheel. And thirdly, I could probably easily clone the wiki repository, so I (or for that matter others) can have an offline copy of the wiki. On the other hand, as far as I know, I can not use django models with flat files. Then, if I wanted to add fields to a wiki site, like a category, I would need to somehow keep a reference to that flat file in order to associate the fields in the database with the flat file. Besides, I don't know if it is a good idea to have all the wiki sites in one repository. I imagine it is more natural to have kind of like a repository per wiki site resp. file. Last but not least, I'm not sure, but I think using flat files would limit my deploying capabilities because web hosts maybe don't allow creating files (I'm thinking, for example, of Google App Engine) Storing in a database By storing the wiki sites in the database I can utilize django models and associate arbitrary fields with the wiki site. I probably would also have an easier life deploying the wiki. But I would not get vcs features like history and conflict resolving per se. I searched for django-extensions to help me and I found django-reversion. However, I do not fully understand if it fit my needs. Does it track model changes like for example if I change the django model file, or does it track the content of the models (which would fit my need). Plus, I do not see if django reversion would help me with edit conflicts. Storing a vcs repository in a database field This would be my ideal solution. It would combine the advantages of both previous approaches without the disadvantages. That is; I would have vcs features but I would save the wiki sites in a database. The problem is: I have no idea how feasible that is. I just imagine saving a wiki site/source together with a git/mercurial repository in a database field. Yet, I somehow doubt database fields work like that. So, I'm open for any other approaches but this is what I came up with. Also, if you're interested, you can find the crappy early test I'm working on here http://github.com/eugenkiss/instantwiki-test

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  • Find location using only distance and range?

    - by pinnacler
    Triangulation works by checking your angle to three KNOWN targets. "I know the that's the Lighthouse of Alexandria, it's located here (X,Y) on a map, and it's to my right at 90 degrees." Repeat 2 more times for different targets and angles. Trilateration works by checking your distance from three KNOWN targets. "I know the that's the Lighthouse of Alexandria, it's located here (X,Y) on a map, and I'm 100 meters away from that." Repeat 2 more times for different targets and ranges. But both of those methods rely on knowing WHAT you're looking at. Say you're in a forest and you can't differentiate between trees, but you know where key trees are. These trees have been hand picked as "landmarks." You have a robot moving through that forest slowly. Do you know of any ways to determine location based solely off of angle and range, exploiting geometry between landmarks? Note, you will see other trees as well, so you won't know which trees are key trees. Ignore the fact that a target may be occluded. Our pre-algorithm takes care of that. 1) If this exists, what's it called? I can't find anything. 2) What do you think the odds are of having two identical location 'hits?' I imagine it's fairly rare. 3) If there are two identical location 'hits,' how can I determine my exact location after I move the robot next. (I assume the chances of having 2 occurrences of EXACT angles in a row, after I reposition the robot, would be statistically impossible, barring a forest growing in rows like corn). Would I just calculate the position again and hope for the best? Or would I somehow incorporate my previous position estimate into my next guess? If this exists, I'd like to read about it, and if not, develop it as a side project. I just don't have time to reinvent the wheel right now, nor have the time to implement this from scratch. So if it doesn't exist, I'll have to figure out another way to localize the robot since that's not the aim of this research, if it does, lets hope it's semi-easy.

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  • Reliable and fast way to convert a zillion ODT files in PDF?

    - by Marco Mariani
    I need to pre-produce a million or two PDF files from a simple template (a few pages and tables) with embedded fonts. Usually, I would stay low level in a case like this, and compose everything with a library like ReportLab, but I joined late in the project. Currently, I have a template.odt and use markers in the content.xml files to fill with data from a DB. I can smoothly create the ODT files, they always look rigth. For the ODT to PDF conversion, I'm using openoffice in server mode (and PyODConverter w/ named pipe), but it's not very reliable: in a batch of documents, there is eventually a point after which all the processed files are converted into garbage (wrong fonts and letters sprawled all over the page). Problem is not predictably reproducible (does not depend on the data), happens in OOo 2.3 and 3.2, in Ubuntu, XP, Server 2003 and Windows 7. My Heisenbug detector is ticking. I tried to reduce the size of batches and restarting OOo after each one; still, a small percentage of the documents are messed up. Of course I'll write about this on the Ooo mailing lists, but in the meanwhile, I have a delivery and lost too much time already. Where do I go? Completely avoid the ODT format and go for another template system. Suggestions? Anything that takes a few seconds to run is way too slow. OOo takes around a second and it sums to 15 days of processing time. I had to write a program for clustering the jobs over several clients. Keep the format but go for another tool/program for the conversion. Which one? There are many apps in the shareware or commercial repositories for windows, but trying each one is a daunting task. Some are too slow, some cannot be run in batch without buying it first, some cannot work from command line, etc. Open source tools tend not to reinvent the wheel and often depend on openoffice. Converting to an intermediate .DOC format could help to avoid the OOo bug, but it would double the processing time and complicate a task that is already too hairy. Try to produce the PDFs twice and compare them, discarding the whole batch if there's something wrong. Although the documents look equal, I know of no way to compare the binary content. Restart OOo after processing each document. it would take a lot more time to produce them it would lower the percentage of the wrong files, and make it very hard to identify them. Go for ReportLab and recreate the pages programmatically. This is the approach I'm going to try in a few minutes. Learn to properly format bulleted lists Thanks a lot.

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  • random, Graphics point ,searching- algorithm, via dual for loop set

    - by LoneXcoder
    hello and thanks for joining me in my journey to the custom made algorithm for "guess where the pixel is" this for Loop set (over Point.X, Point.Y), is formed in consecutive/linear form: //Original\initial Location Point initPoint = new Point(150, 100); // No' of pixels to search left off X , and above Y int preXsrchDepth, preYsrchDepth; // No' of pixels to search to the right of X, And Above Y int postXsrchDepth, postYsrchDepth; preXsrchDepth = 10; // will start search at 10 pixels to the left from original X preYsrchDepth = 10; // will start search at 10 pixels above the original Y postXsrchDepth = 10; // will stop search at 10 pixels to the right from X postYsrchDepth = 10; // will stop search at 10 pixels below Y int StopXsearch = initPoint.X + postXsrchDepth; //stops X Loop itarations at initial pointX + depth requested to serch right of it int StopYsearch = initPoint.Y + postYsrchDepth; //stops Y Loop itarations at initial pointY + depth requested below original location int CountDownX, CountDownY; // Optional not requierd for loop but will reports the count down how many iterations left (unless break; triggerd ..uppon success) Point SearchFromPoint = Point.Empty; //the point will be used for (int StartX = initPoint.X - preXsrchDepth; StartX < StopXsearch; StartX++) { SearchFromPoint.X = StartX; for (int StartY = initPoint.Y - preYsrchDepth; StartY < StpY; StartY++) { CountDownX = (initPoint.X - StartX); CountDownY=(initPoint.Y - StartY); SearchFromPoint.Y = StartY; if (SearchSuccess) { same = true; AAdToAppLog("Search Report For: " + imgName + "Search Completed Successfully On Try " + CountDownX + ":" + CountDownY); break; } } } <-10 ---- -5--- -1 X +1--- +5---- +10 what i would like to do is try a way of instead is have a little more clever approach <+8---+5-- -8 -5 -- +2 +10 X -2 - -10 -8-- -6 ---1- -3 | +8 | -10 Y +1 -6 | | +9 .... I do know there's a wheel already invented in this field (even a full-trailer truck amount of wheels (: ) but as a new programmer, I really wanted to start of with a simple way and also related to my field of interest in my project. can anybody show an idea of his, he learnt along the way to Professionalism in algorithm /programming having tests to do on few approaches (kind'a random cleverness...) will absolutely make the day and perhaps help some others viewing this page in the future to come it will be much easier for me to understand if you could use as much as possible similar naming to variables i used or implenet your code example ...it will be Greatly appreciated if used with my code sample, unless my metod is a realy flavorless. p.s i think that(atleast as human being) the tricky part is when throwing inconsecutive numbers you loose track of what you didn't yet use, how do u take care of this too . thanks allot in advance looking forward to your participation !

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  • YASR - Yet another search and replace question

    - by petronius31
    Environment: asp.net c# openxml Ok, so I've been reading a ton of snippets and trying to recreate the wheel, but I'm hoping that somone can help me get to my desination faster. I have multiple documents that I need to merge together... check... I'm able to do that with openxml sdk. Birds are singing, sun is shining so far. Now that I have the document the way I want it, I need to search and replace text and/or content controls. I've tried using my own text - {replace this} but when I look at the xml (rename docx to zip and view the file), the { is nowhere near the text. So I either need to know how to protect that within the doucment so they don't diverge or I need to find another way to search and replace. I'm able to search/replace if it is an xml file, but then I'm back to not being able to combine the doucments easily. Code below... and as I mentioned... document merge works fine... just need to replace stuff. protected void exeProcessTheDoc(object sender, EventArgs e) { string doc1 = Server.MapPath("~/Templates/doc1.docx"); string doc2 = Server.MapPath("~/Templates/doc2.docx"); string final_doc = Server.MapPath("~/Templates/extFinal.docx"); File.Delete(final_doc); File.Copy(doc1, final_doc); using (WordprocessingDocument myDoc = WordprocessingDocument.Open(final_doc, true)) { string altChunkId = "AltChunkId2"; MainDocumentPart mainPart = myDoc.MainDocumentPart; AlternativeFormatImportPart chunk = mainPart.AddAlternativeFormatImportPart( AlternativeFormatImportPartType.WordprocessingML, altChunkId); using (FileStream fileStream = File.Open(doc2, FileMode.Open)) chunk.FeedData(fileStream); AltChunk altChunk = new AltChunk(); altChunk.Id = altChunkId; mainPart.Document.Body.InsertAfter(altChunk, mainPart.Document.Body.Elements<Paragraph>().Last()); mainPart.Document.Save(); } exeSearchReplace(final_doc); } protected void exeSearchReplace(string document) { using (WordprocessingDocument wordDoc = WordprocessingDocument.Open(document, true)) { string docText = null; using (StreamReader sr = new StreamReader(wordDoc.MainDocumentPart. GetStream())) { docText = sr.ReadToEnd(); } Regex regexText = new Regex("acvtClientName"); docText = regexText.Replace(docText, "Hi Everyone!"); using (StreamWriter sw = new StreamWriter(wordDoc.MainDocumentPart.GetStream(FileMode.Create))) { sw.Write(docText); } } } } }

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  • Find location using only distance and bearing?

    - by pinnacler
    Triangulation works by checking your angle to three KNOWN targets. "I know the that's the Lighthouse of Alexandria, it's located here (X,Y) on a map, and it's to my right at 90 degrees." Repeat 2 more times for different targets and angles. Trilateration works by checking your distance from three KNOWN targets. "I know the that's the Lighthouse of Alexandria, it's located here (X,Y) on a map, and I'm 100 meters away from that." Repeat 2 more times for different targets and ranges. But both of those methods rely on knowing WHAT you're looking at. Say you're in a forest and you can't differentiate between trees, but you know where key trees are. These trees have been hand picked as "landmarks." You have a robot moving through that forest slowly. Do you know of any ways to determine location based solely off of angle and range, exploiting geometry between landmarks? Note, you will see other trees as well, so you won't know which trees are key trees. Ignore the fact that a target may be occluded. Our pre-algorithm takes care of that. 1) If this exists, what's it called? I can't find anything. 2) What do you think the odds are of having two identical location 'hits?' I imagine it's fairly rare. 3) If there are two identical location 'hits,' how can I determine my exact location after I move the robot next. (I assume the chances of having 2 occurrences of EXACT angles in a row, after I reposition the robot, would be statistically impossible, barring a forest growing in rows like corn). Would I just calculate the position again and hope for the best? Or would I somehow incorporate my previous position estimate into my next guess? If this exists, I'd like to read about it, and if not, develop it as a side project. I just don't have time to reinvent the wheel right now, nor have the time to implement this from scratch. So if it doesn't exist, I'll have to figure out another way to localize the robot since that's not the aim of this research, if it does, lets hope it's semi-easy.

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  • Available Coroutine Libraries in Java

    - by JUST MY correct OPINION
    I would like to do some stuff in Java that would be clearer if written using concurrent routines, but for which full-on threads are serious overkill. The answer, of course, is the use of coroutines, but there doesn't appear to be any coroutine support in the standard Java libraries and a quick Google on it brings up tantalising hints here or there, but nothing substantial. Here's what I've found so far: JSIM has a coroutine class, but it looks pretty heavyweight and conflates, seemingly, with threads at points. The point of this is to reduce the complexity of full-on threading, not to add to it. Further I'm not sure that the class can be extracted from the library and used independently. Xalan has a coroutine set class that does coroutine-like stuff, but again it's dubious if this can be meaningfully extracted from the overall library. It also looks like it's implemented as a tightly-controlled form of thread pool, not as actual coroutines. There's a Google Code project which looks like what I'm after, but if anything it looks more heavyweight than using threads would be. I'm basically nervous of something that requires software to dynamically change the JVM bytecode at runtime to do its work. This looks like overkill and like something that will cause more problems than coroutines would solve. Further it looks like it doesn't implement the whole coroutine concept. By my glance-over it gives a yield feature that just returns to the invoker. Proper coroutines allow yields to transfer control to any known coroutine directly. Basically this library, heavyweight and scary as it is, only gives you support for iterators, not fully-general coroutines. The promisingly-named Coroutine for Java fails because it's a platform-specific (obviously using JNI) solution. And that's about all I've found. I know about the native JVM support for coroutines in the Da Vinci Machine and I also know about the JNI continuations trick for doing this. These are not really good solutions for me, however, as I would not necessarily have control over which VM or platform my code would run on. (Indeed any bytecode manipulation system would suffer similar problems -- it would be best were this pure Java if possible. Runtime bytecode manipulation would restrict me from using this on Android, for example.) So does anybody have any pointers? Is this even possible? If not, will it be possible in Java 7? Edited to add: Just to ensure that confusion is contained, this is a related question to my other one, but not the same. This one is looking for an existing implementation in a bid to avoid reinventing the wheel unnecessarily. The other one is a question relating to how one would go about implementing coroutines in Java should this question prove unanswerable. The intent is to keep different questions on different threads.

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  • Web Services Primer for a WinForms Developer?

    - by Unicorns
    I've been writing client/server applications with Winforms for about six years now, but I have yet to venture into the web space (neither ASP.NET nor web services). Given the direction that the job market has been heading for some time and the fact that I have a basic curiosity, I'd like to get involved with writing web services, but I don't know where to start. I've read about various options (XML/SOAP vs. JSON, REST vs...well, actually I don't know what it's called, etc.), but I'm not sure what sort of criteria are in play when making the determination to use one or the other. Obviously, I'd like to leverage the tools that I have (Visual Studio, the .NET framework, etc.) without hamstringing myself into only targeting a particular audience (i.e. writing the service in such a way as to make it difficult to consume from a Windows Mobile/Android/iPhone client, for example). For the record, my plan--for now--is to use WCF for my web service development, but I'm open to using another .NET approach if that's advisable. I realize that this question is pretty open-ended so it may get closed, but here are some things I'm wondering: What are some things to consider when choosing the type of web service (REST, etc.) I intend to write? Is it possible (and, if so, feasible) to move from one approach to another? Can web services be written in an event-driven way? As I said I'm a Winforms developer, so I'm used to objects raising events for me to react to. For instance, if I have two clients connected to my service, is there a way for me to "push" information to one of them as a result of an action by the other? If this is possible, is this advisable or am I just not thinking about it correctly? What authentication mechanisms seem to work best for public-facing services? What about if I plan to have different types of OS'es and clients connecting to the service? Is there a generally accepted platform-agnostic approach? In the line of authentication, is this something that I should be doing myself (authenticating an managing sessions, etc.) or is this something should be handled at the framework level and I just define exactly how it should work? If that's the case, how do I tell who the requester has authenticated themselves as? I started writing an authentication mechanism (simple username/password combinations stored in the database and a corresponding session table with a GUID key) within my service and just requiring that key to be passed with every operation (other than logging in, of course), but I want to make sure that I'm not reinventing the wheel here. However, I also don't want to clutter up the server with a bunch of machine user accounts just to use Basic authentication. I'm also under the impression that Digest (and of course Windows) authentication requires a machine (or AD) user account.

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  • Strange behaviour when posting CGEvent to PSN

    - by Ben Packard
    If I set up a loop that posts some keyboard events to a PSN, I find that it works fine except for when first launched. The event only seems to post when i do something with the mouse manually - even just moving it slightly. Here's the details, if they help. An external application has a list box of text lines, which I am reading by posting copy commands (and checking the pasteboard). Unfortunately this is my only way to get this text. Sometimes, the application pulls focus away from the list, which I can detect. When this happens, the most reliable way to return focus is by sending a mouse event to click on a text field directly above the list, then send a 'tab' keyboard event to shift the focus onto the list. So at launch, the loop runs fine, scrolling down the list and copying the text. When focus is shifted away, its is detected fine, and the events are sent to move focus back to the list. But nothing seems to happen. The loop continues detecting that focus has changed, but the events only work once I move the mouse. Or even just use the scroll wheel. Strange. Once this has happened the first time, it works fine - each time focus moves, the PSN events switch it back without me having to do anything at all. Here's the code that runs in the loop - verified as working: //copy to pasteboard - CMD-V e3 = CGEventCreateKeyboardEvent(NULL, (CGKeyCode)8, true); CGEventSetFlags(e3, kCGEventFlagMaskCommand); CGEventPostToPSN(&psn, e3); CFRelease(e3); e4 = CGEventCreateKeyboardEvent(NULL, (CGKeyCode)8, false); CGEventPostToPSN(&psn, e4); CFRelease(e4); //move cursor down e1 = CGEventCreateKeyboardEvent(NULL, (CGKeyCode)125, true); CGEventPostToPSN(&psn, e1); CFRelease(e1); e2 = CGEventCreateKeyboardEvent(NULL, (CGKeyCode)125, false); CGEventPostToPSN(&psn, e2); CFRelease(e2); And here's where I switch focus, also working (except when first required): //click in text input box - point is derived earlier e6 = CGEventCreateMouseEvent(NULL, kCGEventLeftMouseDown, point, 0); CGEventPostToPSN(&psn, e6); CFRelease(e6); e7 = CGEventCreateMouseEvent(NULL, kCGEventLeftMouseUp, point, 0); CGEventPostToPSN(&psn, e7); CFRelease(e7); //press tab key to move to chat log table CGEventRef e = CGEventCreateKeyboardEvent(NULL, (CGKeyCode)48, true); //CGEventPost(kCGSessionEventTap, e); CGEventPostToPSN(&psn, e); CFRelease(e); CGEventRef e11 = CGEventCreateKeyboardEvent(NULL, (CGKeyCode)48, false); CGEventPostToPSN(&psn, e11); CFRelease(e11);

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  • Design Technique: How to design a complex system for processing orders, products and units.

    - by Shyam
    Hi, Programming is fun: I learned that by trying out simple challenges, reading up some books and following some tutorials. I am able to grasp the concepts of writing with OO (I do so in Ruby), and write a bit of code myself. What bugs me though is that I feel re-inventing the wheel: I haven't followed an education or found a book (a free one that is) that explains me the why's instead of the how's, and I've learned from the A-team that it is the plan that makes it come together. So, armed with my nuby Ruby skills, I decided I wanted to program a virtual store. I figured out the following: My virtual Store will have: Products and Services Inventories Orders and Shipping Customers Now this isn't complex at all. With the help of some cool tools (CMapTools), I drew out some concepts, but quickly enough (thanks to my inferior experience in designing), my design started to bite me. My very first product-line were virtual "laptops". So, I created a class (Ruby): class Product attr_accessor :name, :price def initialize(name, price) @name = name @price = price end end which can be instantiated by doing (IRb) x = Product.new("Banana Pro", 250) Since I want my virtual customers to be able to purchase more than one product, or various types, I figured out I needed some kind of "Order" mechanism. class Order def initialize(order_no) @order_no = order_no @line_items = [] end def add_product(myproduct) @line_items << myproduct end def show_order() puts @order_no @line_items.each do |x| puts x.name.to_s + "\t" + x.price.to_s end end end that can be instantiated by doing (IRb) z = Order.new(1234) z.add_product(x) z.show_order Splendid, I have now a very simple ordering system that allows me to add products to an order. But, here comes my real question. What if I have three models of my product (economy, business, showoff)? Or have my products be composed out of separate units (bigger screen, nicer keyboard, different OS)? Surely I could make them three separate products, or add complexity to my product class, but I am looking for are best practices to design a flexible product object that can be used in the real world, to facilitate a complex system. My apologies if my grammar and my spelling are with error, as english is not my first language and I took the time to check as far I could understand and translate properly! Thank you for your answers, comments and feedback!

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