Search Results

Search found 91614 results on 3665 pages for 'new developer'.

Page 213/3665 | < Previous Page | 209 210 211 212 213 214 215 216 217 218 219 220  | Next Page >

  • xslt: operations on new elements

    - by user1495523
    Could you please explain in case we could perform any operations on newly included elements using xsl? To explain using an example: if we have the following input file <?xml version="1.0" encoding="UTF-8"?> <top> <Results> <a>no</a> <b>10</b> <c>12</c> <d>9</d> </Results> <Results> <a>Yes</a> <b>8</b> <c>50</c> <d>12</d> </Results> </top> We need the final result as <?xml version="1.0" encoding="UTF-8"?> <top> <Results> <a>no</a> <b>10</b> <b_>10</b_> <c>12</c> <c_>12</c_> <d>9</d> <e_>11</e_> </Results> <Results> <a>Yes</a> <b>8</b> <b_>8</b_> <c>50</c> <c_>50</c_> <d>12</d> <e_>29</e_> </Results> </top> Where: b_ = b, c_ = c, & e_ = (b_ + c_)/2

    Read the article

  • Look up or insert new element to string list in Haskell

    - by nightscream
    So I want to have a function that takes a String and a list as an argument, and checks if that element is already on the list, if it is, returns the same list, if it isnt, adds it to the list and returns it, 'im a begginer with haskell so heres what I have tried with no sucess: check:: String ->[String] ->[String] check x [] = []++[x] check x (y:xs) | x==y = (y:xs) | otherwise = check x xs Can someone point me the way ? thks

    Read the article

  • HSDPA modem only working on certain USB ports

    - by nabulke
    Depending on which USB port I use to connect my HSDPA modem, the network manager will connect to the internet or not. I used to work (i.e. established a internet connection automatically) on all ports, but over time it simply stopped on some ports. lsusb output in all cases looks like that (Device ID varies depending on USB port): Bus 001 Device 009: ID 12d1:1003 Huawei Technologies Co., Ltd. E220 HSDPA Modem / E270 HSDPA/HSUPA Modem Any ideas what could cause this behaviour? What can I do to fix this? ADDED One additional information about the modem: if connected via USB it will be available as as harddrive AND as a HSDPA modem (kind of a duality...). In the error case, it will only be shown as a harddrive. ADDITIONAL INFO AS REQUESTED MODEM NOT WORKING Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 002 Device 002: ID 413c:8000 Dell Computer Corp. BC02 Bluetooth Adapter Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 001 Device 007: ID 12d1:1003 Huawei Technologies Co., Ltd. E220 HSDPA Modem / E270 HSDPA/HSUPA Modem Bus 001 Device 005: ID 046d:c00c Logitech, Inc. Optical Wheel Mouse Bus 001 Device 004: ID 05e3:0608 Genesys Logic, Inc. USB-2.0 4-Port HUB Bus 001 Device 003: ID 413c:0058 Dell Computer Corp. Port Replicator Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub laptop:~$ dmesg | grep 'usb' [ 0.225371] usbcore: registered new interface driver usbfs [ 0.225387] usbcore: registered new interface driver hub [ 0.225418] usbcore: registered new device driver usb [ 0.504291] usb usb1: configuration #1 chosen from 1 choice [ 0.504767] usb usb2: configuration #1 chosen from 1 choice [ 0.505046] usb usb3: configuration #1 chosen from 1 choice [ 0.505601] usb usb4: configuration #1 chosen from 1 choice [ 1.061064] usb 1-6: new high speed USB device using ehci_hcd and address 3 [ 1.192636] usb 1-6: configuration #1 chosen from 1 choice [ 1.447006] usb 2-2: new full speed USB device using uhci_hcd and address 2 [ 1.634908] usb 2-2: configuration #1 chosen from 1 choice [ 1.708164] usb 1-6.1: new high speed USB device using ehci_hcd and address 4 [ 1.801668] usb 1-6.1: configuration #1 chosen from 1 choice [ 2.076279] usb 1-6.1.1: new low speed USB device using ehci_hcd and address 5 [ 2.174932] usb 1-6.1.1: configuration #1 chosen from 1 choice [ 6.580315] usb 1-6.1.2: new high speed USB device using ehci_hcd and address6 [ 6.683479] usb 1-6.1.2: configuration #1 chosen from 1 choice [ 20.018671] usbcore: registered new interface driver btusb [ 20.131703] usbcore: registered new interface driver usb-storage [ 20.131988] usb-storage: device found at 6 [ 20.131991] usb-storage: waiting for device to settle before scanning [ 20.207981] usb 1-6.1.2: USB disconnect, address 6 [ 20.291499] usbcore: registered new interface driver hiddev [ 20.297052] input: Logitech USB Mouse as /devices/pci0000:00/0000:00:1d.7/usb1/1-6/1-6.1/1-6.1.1/1-6.1.1:1.0/input/input6 [ 20.297465] generic-usb 0003:046D:C00C.0001: input,hidraw0: USB HID v1.10 Mouse [Logitech USB Mouse] on usb-0000:00:1d.7-6.1.1/input0 [ 20.297534] usbcore: registered new interface driver usbhid [ 20.297803] usbhid: v2.6:USB HID core driver [ 26.552360] usb 1-6.1.2: new high speed USB device using ehci_hcd and address 7 [ 26.663506] usb 1-6.1.2: configuration #1 chosen from 1 choice [ 26.709628] usb-storage: device found at 7 [ 26.709631] usb-storage: waiting for device to settle before scanning [ 26.732387] usb-storage: device found at 7 [ 26.732390] usb-storage: waiting for device to settle before scanning [ 31.709568] usb-storage: device scan complete [ 31.733676] usb-storage: device scan complete MODEM WORKING Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 003 Device 002: ID 046d:c00c Logitech, Inc. Optical Wheel Mouse Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 002 Device 002: ID 413c:8000 Dell Computer Corp. BC02 Bluetooth Adapter Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 001 Device 004: ID 12d1:1003 Huawei Technologies Co., Ltd. E220 HSDPA Modem / E270 HSDPA/HSUPA Modem Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub dmesg | grep 'usb' [ 0.134811] usbcore: registered new interface driver usbfs [ 0.134826] usbcore: registered new interface driver hub [ 0.134858] usbcore: registered new device driver usb [ 0.360327] usb usb1: configuration #1 chosen from 1 choice [ 0.360783] usb usb2: configuration #1 chosen from 1 choice [ 0.361061] usb usb3: configuration #1 chosen from 1 choice [ 0.361611] usb usb4: configuration #1 chosen from 1 choice [ 1.144122] usb 2-2: new full speed USB device using uhci_hcd and address 2 [ 1.346896] usb 2-2: configuration #1 chosen from 1 choice [ 1.588072] usb 3-1: new low speed USB device using uhci_hcd and address 2 [ 1.761204] usb 3-1: configuration #1 chosen from 1 choice [ 5.972042] usb 1-1: new high speed USB device using ehci_hcd and address 4 [ 6.115438] usb 1-1: configuration #1 chosen from 1 choice [ 19.990565] usbcore: registered new interface driver usbserial [ 19.991429] usb-storage: device found at 4 [ 19.991432] usb-storage: waiting for device to settle before scanning [ 20.017260] usbcore: registered new interface driver usb-storage [ 20.017305] usbcore: registered new interface driver usbserial_generic [ 20.017308] usbserial: USB Serial Driver core [ 20.017817] usb-storage: device found at 4 [ 20.017820] usb-storage: waiting for device to settle before scanning [ 20.070796] usbcore: registered new interface driver btusb [ 20.229525] usb 1-1: GSM modem (1-port) converter now attached to ttyUSB0 [ 20.229776] usb 1-1: GSM modem (1-port) converter now attached to ttyUSB1 [ 20.229843] usbcore: registered new interface driver option [ 20.230396] usbcore: registered new interface driver hiddev [ 20.246280] input: Logitech USB Mouse as /devices/pci0000:00/0000:00:1d.1/usb3/3-1/3-1:1.0/input/input6 [ 20.246438] generic-usb 0003:046D:C00C.0001: input,hidraw0: USB HID v1.10 Mouse [Logitech USB Mouse] on usb-0000:00:1d.1-1/input0 [ 20.246479] usbcore: registered new interface driver usbhid [ 20.246483] usbhid: v2.6:USB HID core driver [ 25.436579] usb-storage: device scan complete [ 25.437674] usb-storage: device scan complete

    Read the article

  • Use the latest technology or use a mature technology as a developer?

    - by Ted Wong
    I would like to develop an application for a group of people to use. I have decided to develop using python, but I am thinking of using python 2.X or python 3.X. If I use python 2.X, I need to upgrade it for the future... But it is more mature, and has many tools and libraries. If I develop using 3.X, I don't need to think of future integration, but currenttly it doesn't have many libraries, even a python to executable is not ready for all platforms. Also, one of the considerations is that it is a brand new application, so I don't have the history burden to maintain the old libraries. Any recommendation on this dilemma? More information about this application: Native application Time for maintenance: 5 years+ Library/Tools must need: don't have idea, yet. Must need feature that in 2.X: Convert to an executable for both Windows and Mac OS X

    Read the article

  • How do I make sure the web developer I hire will not steal my idea?

    - by Greg McNulty
    So I have a great idea for a new website. However, not the time to develop it. I would like to hire a person or company to design it for me. What steps do I need to take, to protect my idea? Where and how do people protect website ideas in general? Also, how easy is it for someone to tweak the idea and make it legally heir own? Is a patent enough to protect such a thing, idea. Are there different levels or types of protection? Thank You.

    Read the article

  • How do I make sure the web developer I hire will not steal my idea?

    - by Greg McNulty
    So I have a great idea for a new website. However, not the time to develop it. I would like to hire a person or company to design it for me. What steps do I need to take, to protect my idea? Where and how do people protect website ideas in general? Also, how easy is it for someone to tweak the idea and make it legally heir own? Is a patent enough to protect such a thing, idea. Are there different levels or types of protection? Thank You.

    Read the article

  • Will Swift or any upcoming Apple developer tools be incompatible with .xibs? [on hold]

    - by user
    I'm still letting the sudden announcement of a language change (Swift) sink in, and I'm wondering if the upcoming platform changes will still be highly compatible with using .xibs for interface development. I've used Storyboards in multiple production projects but I don't feel very productive with them, and I get tired of managing multiple storyboards, links, and xib connections for complex views. I don't see why Swift and Xcode 6 wouldn't cooperate with Xibs indefinitely if it still allows @IBOutlets and @IBActions, but I have realized that Apple purposely shuns old methodologies for the sake of doing so. If there's any reasons to turn away from xibs in iOS8 besides the use-the-new-stuff conventional wisdom, I'd like to know before its too late.

    Read the article

  • Software developer needs Validation for VA Chap 31 to purchase Macbook Pro vs. PC [closed]

    - by David
    I am currently attending college with a path of software development and working towards my BS thanks to VA Chap 31. My old original Macbook Pro is near dead and no longer upgradable on the software or hardware side. The VA has offered to purchase a PC laptop for me (Because my syllabi says computer required), but I do not want to go backwards. I have a lot invested in OS X software and Mac peripherals, not to mention I prefer to program in an Apple environment. PC vs. Mac costs are so drastically different that I must validate my request for a new Macbook Pro. In my request to the VA, I stated the above and some other topics but they requested more validation. Can anyone recommend issues, reasons, etc. to help me validate this purchase by the VA for school? Thanks in advance for your help, David

    Read the article

  • What developer conferences are you going to this year?

    - by mbcrump
    This short list is what I consider to be the “cream-of-the-crop” in developer conferences. This is also a list of the conferences that I plan on attending in 2011. If you feel your conference is just as good, then shoot me an email at [michael[at]michaelcrump[dot]net, and if possible I will check it out.   In-Person Event Las Vegas on April 18th-22nd, 2011 Redmond on October 17th-21st, 2011 Orlando on December 5th-9th, 2011 Visual Studio Live – I attended this event in November of last year and blogged about my experience. I am also planning on going back to the Orlando session in December of this year. So what did I like the most about this event? Being able to interact one-on-one with a majority of the speakers. If you read my blog post then you will see a list of the speakers that I met up with. I also made a lot of great connections with other professional developers all over the world. They are having an event in Las Vegas on April 18th-22nd. I noticed at this event that they have added a new track on mobile. Being a big fan of mobile, I feel that this is a great move. They also have a great selection for Silverlight Developers including Billy Hollis and Rocky Lhotka. For the full lineup of conference tracks, sessions and speakers visit http://bit.ly/VSLiveTrks. If you are interested in this then you can register here by February 16th. I must add that you can save $300 bucks by getting the early-bird special.   Virtual Conference SSWUG (DBTechCon) - holds the largest virtual conference in the information technology industry. It is also special to me because they selected a majority of my Silverlight content for the April conference. No traveling fees and all of the sessions are recorded so you can watch them on-demand for $189 bucks (early-bird special). For the entire speaker list then click here. The session list has also been published. If you are interested in this then you can register here.   In-Person Event Knoxville, TN on June 3rd/4th 2011. Codestock.org – If you live in the South then you have heard of CodeStock. To my knowledge, they have only had 3 events so far and they were a huge success. It was such a success that after the last event, everyone was telling me how good it was and how much they enjoyed it. They currently have a call for speakers going on right now, so if you have sessions then be sure to submit yours. So, what makes them stand out? Well for starters Michael Neal (organizer) developed an open API so conference attendees could build their own apps for the sessions. They also encouraged their speakers to go to other sessions instead of stay in a “speaker-room”. Another cool feature is that they are uploading videos from the conference so everyone can benefit. They are currently looking for sponsorship, so help out if you can.   In-Person Event Redmond, WA on October 28/29 2011 *NOT 100% SURE AT THIS POINT* PDC 11 – OK, so the logo should be pdc11 but its not out yet. This event is located on Microsoft’s campus in Redmond, WA. It is probably one of the most well known conferences for developers to attend. One of the big perks from this event is that you typically come away with free stuff. In 2010 they gave away Windows 7 Phones. I remember years earlier they gave away laptops. This of course isn’t the only reason to go, you may get to tour the Microsoft campus. Since pdc is a huge event, you can view all the events for free. Mike Taulty created a nice Silverlight application that consumes the OData feed. You can download it here. If everything goes as planned, I will be at all of these events. If you plan on going then send me a tweet and we will do lunch or dinner. I love meeting new developers and talking .net.  Subscribe to my feed

    Read the article

  • How to repeat a POST request using Chrome's developer tools?

    - by Luke The Obscure
    Not sure if this is the right stack exchange to ask this, but here goes... I'm trying to wean myself off of Firebug, which has served me very well for a lot of years. One feature that seems to be missing in Chrome's dev tools is the ability to repeat an AJAX POST. In firebug I can right click on the request in the console and hit "Open in new tab" and the request is repeated exactly as it was originally sent. In Chrome, the same action just does a normal GET on the link, without any of the post data. Is there any way to repeat an AJAX POST in Chrome's dev tools?

    Read the article

  • What are the Starting Games I need to make?[Best steps for a beginner Game Developer?] [closed]

    - by Man With Steel Nerves...
    Possible Duplicate: What are good games to “earn your wings” with? Hai, I'm new to the genre "Creating Games".Previously i had done only porting.I need some suggestion's for making a game. What are the basic game logics i need to start with? - Should i write Tic-Tac-Toe game? - Actually this seem very basic to me. I'm totally confused on where to start with.I like to create big games but after starting i feel the game is too heavy to handle. Can any one list out the basic needs of a Game Play programmer? I don't mind using any platform (Flash,c++,objective-c) but i need to know what are the game logic's i need to know before i start a big game.

    Read the article

  • I'm a PeopleSoft Developer. Should I learn other languages (C# Java...)?

    - by PSDev
    I've been doing PeopleSoft development for 2 years. Recently, I want to relocate and find out there are not that many PeopleSoft development out there. 90% of the vacant positions are contract type of jobs. I'd rather get a full time permanent position. In PS, I do a lot of maintenance rather than new programming. It does get very boring. Also, I'm not sure if Oracle will one day pull off the plug for PS. What language is in most demand and also offers above average salary? Is it C#, Java, Python, Perl, ...? Thanks.

    Read the article

  • alot questings since i wanted to make a new SSB game or mario game(that use 3d models) [closed]

    - by user20465
    i have just started to study programming and i know already ppl will say why make a so big project like as a SSB game for a noob game development? cuz i always wanted a SSB engine like as Mugen is a fighter game engine but is not like as SSB´s gameplay + is not using 3d models too so i will call it SSBmugen(until i find a better title for it i got afew ideas for titles) also i wanted to make this game so it can use SSBbrawl files(models+animations mainly) the moveset+Stage coding files i wanted to redo cuz so anything can be possible like make a teleporter or a pipe teleporter(like as Super mario bros game) on a stag e or make some stuff there is impossible in SSBbrawl for moveset coding but is not in SSBmugen like make so a char. summon a Clone and the clone will do a attack and then is gone or some attacks/moves also i will make a moveset/stage Coding editor so it will be really easy to make moveset/stages coding for yours 3d models/animations moveset+stage Coding i mean: hitboxes/hurtboxes/moving Stuff/moving bones like cape or hair bones that is moving by wind effects or falling or other stuff like that/other stuff that needed to be coded i have planed to make a editor(for moveset/char. coding) or add the editor in brawlbox for my game so other ppl can easy make moveset/stages Coding to they´s models/animations so it will be easy so even kids can make a custom movesets/stages why using SSBbrawl files?: cuz ppl have made alot of models or textures/custom movesets/custom stages like goku/other anime/not brawl stuff for super smash bros brawl hacking(a.k.a modding) so ppl dont have to redo anything if they wanted to have the custom models or textures/custom movesets/custom stages from SSBbrawl to SSBmugen +there is the program named brawlbox that can open brawl files like model/animations and can edit models or animations and import models from 3ds max to be the right model format for SSBbrawl and i also wanted it so easy to add(a.k.a installer) Recolours or alt. models(like as oneslot doctor mario model over mario´s boneset) or textures/Movesets/new char. slots/new stages so easy so you only needing to download themplace them in right foldername them the right nameStart the gameRecolours or alt. models or textures/Movesets/new char. slots/new stages works an loading right so you wont needing to edit any files for add something so kids/not so smart ppl can easy use the mods other ppl is making/uploading for this game here is the file format i wanted to know if they can be readed/opened if making a game that use these files: .mld0(brawl model file) .chr0(model animation for moving/scale/rota the bones) .srt0(animations for texture like moving eyes or blinking) .vis0(Animations for get polygons to hide/show with visibilitybones on the model there is also some polygons there ) .brres(a file format where stuff like model files or textures or animations is inside) .pac(a file format where the .brres is inside to keep model+textures+model for the shadow in 1 file) .wav (for SoundFX effects or voices to char. or stages) i am sure that one is possible the .wav files is inside a other file format for brawl but that file can´t you add more .wav files inside only replace so i wanted the .wav files outside so its easy to add/replace/remove SoundFX effects or voices to char. or stages .brstm(brawl music file so the music is looped perfect so it loop in middel of the music and not start over again then the music is done) afew more file formats (mainly for the Graphics effects like fire/aura/hit effects if not needing to redo them)so only coding in the editor i will make is needed to be done for port a SSBB hack(a.k.a mod)(moveset/stage coding) to this game wanted the game to be able to load these files and load them right like if loading wait1.chr0(idle animation) it will also load at same time wait1.srt0/wait1.vis0 and all kinda of animations is inside the same .brres file i am needing since it to be able to load the file format i wanted cuz: -the animations can´t be converted to any other animation file format and i dont think ppl want to redo these animations(inc. me for Goku to SSBbrawl) -models can be converted but then they lose all the shader/materials stuff like a shine effect or lighting on the model -.brstm can be converted to .wav but then there will be no loop so i prefer it can load this file format too for the music to stage/menu -brawlbox is really easy to use for make animation for the char. and import models from 3ds max so even around "not too stupid" 10 year kids can make SSBB mods(not try to be rude but to say how easy it is) also i wanted the folder setup for characters/stages/moveset/other stuff to be like this: https://www.dropbox.com/s/2oolm5z5ri234tz/SSBmugen%20Folder%20setup.txt just uploaded a txt file since it is a wall of text and this post is already a wall of test so it easy to place stuff (if not i do a program for to that so it auto place the stuff on right place) not 100% sure what to use of game engine to make this possible but i got a dll file from that brawlbox program that can open/read/edit these file formats if that helps i also got open source of brawlbox i have kinda learned programming(since its kinda the same thing but still not 100% same) from Super smash bros modding/hacking like coding a moveset for the new animations/models + have readed alittle about it but i am soon starting for real to study it for ppl who is alittle confuse for what i am asking for here is the list: -what game engine should i use to make a SSB clone? but at same time to make all this stuff i just said possible so ppl can make they own mods and share them and use the already made mods from SSBbrawl? and easy to use aswell so noob programmors can use it? -where to learning programming on internet to be even more ready to make a game like this? and dont wanted to start in the small like making small boring 2d games that no one care about anyway ps. i am also planing a other project like as SSBmugen but it will be Super mario bros open (again tittle unsure but open means open source) i will make a Mario game engine that also use 3d models and can have 2d or 3d gameplay with any mario powerups/gameplay(from any mario platform games) there is ever made multiplayer like as in New super mario bros wii maybe multiplay over lan or online but for now over 1 PC also alittle planed for that to my SSBmugen a Level/world map editor for it too(easy to use so even kids can use it and make levels for it) so it just place the objects/enemies and options for them enemies since they are not 100% same AI in all mario game like to choose a goomba have AI from SM64 the Editor will be able to change the gameplay on a level while have a other gameplay on a other level like this: 1 level have Super mario bros 3 gameplay (then it will be a 3d model remake) a other level have super mario galaxy gameplay but in a Super mario 3d land level yet a other level have super mario 64 gameplay but with powerups from a other mario game like powerups from mario 3d land or can ride on Yoshi so you can easy remake your fav. level from a old mario game in this mario engine/editor or just make a custom one with yours fav. mario gameplay/powerups so it will be like turn off/on: walljump/triple jump/other kinda or jumps/2x punch and 1 kick+Air kick/SMG spin attack/Fludd/other stuff like that so you can make the gameplay from the first mario game to the newest or make custom gameplay on a level also the star(from 64/sunshine/galaxy) will be replaced with the flag from new super mario bros/mario 3d land since the game is not so much about getting stars its more about making/download the levels you wanted and share them to other ppl and play these level so after have killed like the boss from SM64 bomb omb field(if one have made that) you will get the flag instead of star since i wanted it to be simple to make levels in the editor to make the bosses/new enemies/new powerups/custom char. idk what to do to make that simple yet also thinking the mario game will use brawl files since it almost already got all needed animations/models for this since i dont wanted to redo animations/models and if needing more animations i can just make them easy in brawlbox since thats the program i am most used to make animations but that will be after my SSBmugen project if not this game will be easyer then SSBmugen to make since i am planing then 1 of them is done i use the that game as base to make the other (since both is kinda platfrom games and possible using same file format for both) also wanted to ask what is best to start with out of these 2 games? also will maybe make a DLC site(or ingame) for both of these games if they get done so it wont end up like as Mugen where you needing to look all over the internet to find the stuff you wanted but for my game all the mods for my game is on same place not sure about online mode for SSBmugen or super mario bros open but i can always add that then i get better at programming both games also need to have options on controls/if using joystick also that i have planed these game for a long time and got even more ideas for them but first i wanted to get them to work so i can add the other stuff later(like DLC or online mode or some other stuff later) right now i know 0,0001% to programming(in my option) maybe i know more then that since i have been study it alittle but i learning while making stuff like this that was also my plan for make these game learn while making them and get better to programming so again i say it i kinda dont want to hear dont do these projects cuz i already know it will be hard so dont wanted so much to heard stuff like: you can´t do it since you just started learning programming or this project will fail since somewhere i needing to get started with programming and this is where i want to start to make my dream games(possible other´s dream games too) and i dont think this project will fail if i work hard on it (as i possible will) and ppl will maybe help i think this was all my questing/ideas for now (sorry for it sounds more like ideas then questings) but i needing to say my ideas so you ppl can see what i needing to use for make this possible

    Read the article

  • Query optimization using composite indexes

    - by xmarch
    Many times, during the process of creating a new Coherence application, developers do not pay attention to the way cache queries are constructed; they only check that these queries comply with functional specs. Later, performance testing shows that these perform poorly and it is then when developers start working on improvements until the non-functional performance requirements are met. This post describes the optimization process of a real-life scenario, where using a composite attribute index has brought a radical improvement in query execution times.  The execution times went down from 4 seconds to 2 milliseconds! E-commerce solution based on Oracle ATG – Endeca In the context of a new e-commerce solution based on Oracle ATG – Endeca, Oracle Coherence has been used to calculate and store SKU prices. In this architecture, a Coherence cache stores the final SKU prices used for Endeca baseline indexing. Each SKU price is calculated from a base SKU price and a series of calculations based on information from corporate global discounts. Corporate global discounts information is stored in an auxiliary Coherence cache with over 800.000 entries. In particular, to obtain each price the process needs to execute six queries over the global discount cache. After the implementation was finished, we discovered that the most expensive steps in the price calculation discount process were the global discounts cache query. This query has 10 parameters and is executed 6 times for each SKU price calculation. The steps taken to optimise this query are described below; Starting point Initial query was: String filter = "levelId = :iLevelId AND  salesCompanyId = :iSalesCompanyId AND salesChannelId = :iSalesChannelId "+ "AND departmentId = :iDepartmentId AND familyId = :iFamilyId AND brand = :iBrand AND manufacturer = :iManufacturer "+ "AND areaId = :iAreaId AND endDate >=  :iEndDate AND startDate <= :iStartDate"; Map<String, Object> params = new HashMap<String, Object>(10); // Fill all parameters. params.put("iLevelId", xxxx); // Executing filter. Filter globalDiscountsFilter = QueryHelper.createFilter(filter, params); NamedCache globalDiscountsCache = CacheFactory.getCache(CacheConstants.GLOBAL_DISCOUNTS_CACHE_NAME); Set applicableDiscounts = globalDiscountsCache.entrySet(globalDiscountsFilter); With the small dataset used for development the cache queries performed very well. However, when carrying out performance testing with a real-world sample size of 800,000 entries, each query execution was taking more than 4 seconds. First round of optimizations The first optimisation step was the creation of separate Coherence index for each of the 10 attributes used by the filter. This avoided object deserialization while executing the query. Each index was created as follows: globalDiscountsCache.addIndex(new ReflectionExtractor("getXXX" ) , false, null); After adding these indexes the query execution time was reduced to between 450 ms and 1s. However, these execution times were still not good enough.  Second round of optimizations In this optimisation phase a Coherence query explain plan was used to identify how many entires each index reduced the results set by, along with the cost in ms of executing that part of the query. Though the explain plan showed that all the indexes for the query were being used, it also showed that the ordering of the query parameters was "sub-optimal".  Parameters associated to object attributes with high-cardinality should appear at the beginning of the filter, or more specifically, the attributes that filters out the highest of number records should be placed at the beginning. But examining corporate global discount data we realized that depending on the values of the parameters used in the query the “good” order for the attributes was different. In particular, if the attributes brand and family had specific values it was more optimal to have a different query changing the order of the attributes. Ultimately, we ended up with three different optimal variants of the query that were used in its relevant cases: String filter = "brand = :iBrand AND familyId = :iFamilyId AND departmentId = :iDepartmentId AND levelId = :iLevelId "+ "AND manufacturer = :iManufacturer AND endDate >= :iEndDate AND salesCompanyId = :iSalesCompanyId "+ "AND areaId = :iAreaId AND salesChannelId = :iSalesChannelId AND startDate <= :iStartDate"; String filter = "familyId = :iFamilyId AND departmentId = :iDepartmentId AND levelId = :iLevelId AND brand = :iBrand "+ "AND manufacturer = :iManufacturer AND endDate >=  :iEndDate AND salesCompanyId = :iSalesCompanyId "+ "AND areaId = :iAreaId  AND salesChannelId = :iSalesChannelId AND startDate <= :iStartDate"; String filter = "brand = :iBrand AND departmentId = :iDepartmentId AND familyId = :iFamilyId AND levelId = :iLevelId "+ "AND manufacturer = :iManufacturer AND endDate >= :iEndDate AND salesCompanyId = :iSalesCompanyId "+ "AND areaId = :iAreaId AND salesChannelId = :iSalesChannelId AND startDate <= :iStartDate"; Using the appropriate query depending on the value of brand and family parameters the query execution time dropped to between 100 ms and 150 ms. But these these execution times were still not good enough and the solution was cumbersome. Third and last round of optimizations The third and final optimization was to introduce a composite index. However, this did mean that it was not possible to use the Coherence Query Language (CohQL), as composite indexes are not currently supporte in CohQL. As the original query had 8 parameters using EqualsFilter, 1 using GreaterEqualsFilter and 1 using LessEqualsFilter, the composite index was built for the 8 attributes using EqualsFilter. The final query had an EqualsFilter for the multiple extractor, a GreaterEqualsFilter and a LessEqualsFilter for the 2 remaining attributes.  All individual indexes were dropped except the ones being used for LessEqualsFilter and GreaterEqualsFilter. We were now running in an scenario with an 8-attributes composite filter and 2 single attribute filters. The composite index created was as follows: ValueExtractor[] ve = { new ReflectionExtractor("getSalesChannelId" ), new ReflectionExtractor("getLevelId" ),    new ReflectionExtractor("getAreaId" ), new ReflectionExtractor("getDepartmentId" ),    new ReflectionExtractor("getFamilyId" ), new ReflectionExtractor("getManufacturer" ),    new ReflectionExtractor("getBrand" ), new ReflectionExtractor("getSalesCompanyId" )}; MultiExtractor me = new MultiExtractor(ve); NamedCache globalDiscountsCache = CacheFactory.getCache(CacheConstants.GLOBAL_DISCOUNTS_CACHE_NAME); globalDiscountsCache.addIndex(me, false, null); And the final query was: ValueExtractor[] ve = { new ReflectionExtractor("getSalesChannelId" ), new ReflectionExtractor("getLevelId" ),    new ReflectionExtractor("getAreaId" ), new ReflectionExtractor("getDepartmentId" ),    new ReflectionExtractor("getFamilyId" ), new ReflectionExtractor("getManufacturer" ),    new ReflectionExtractor("getBrand" ), new ReflectionExtractor("getSalesCompanyId" )}; MultiExtractor me = new MultiExtractor(ve); // Fill composite parameters.String SalesCompanyId = xxxx;...AndFilter composite = new AndFilter(new EqualsFilter(me,                   Arrays.asList(iSalesChannelId, iLevelId, iAreaId, iDepartmentId, iFamilyId, iManufacturer, iBrand, SalesCompanyId)),                                     new GreaterEqualsFilter(new ReflectionExtractor("getEndDate" ), iEndDate)); AndFilter finalFilter = new AndFilter(composite, new LessEqualsFilter(new ReflectionExtractor("getStartDate" ), iStartDate)); NamedCache globalDiscountsCache = CacheFactory.getCache(CacheConstants.GLOBAL_DISCOUNTS_CACHE_NAME); Set applicableDiscounts = globalDiscountsCache.entrySet(finalFilter);      Using this composite index the query improved dramatically and the execution time dropped to between 2 ms and  4 ms.  These execution times completely met the non-functional performance requirements . It should be noticed than when using the composite index the order of the attributes inside the ValueExtractor was not relevant.

    Read the article

  • Which code snipplets in PHP can create a input form, which creates a new set of data in my mysql dat

    - by smiyazaki
    I am using the Google Maps API with parts in javascript and others in PHP. <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> Google Maps AJAX + mySQL/PHP Example // var iconBlue = new GIcon(); iconBlue.image = 'icon.png'; iconBlue.shadow = ''; iconBlue.iconSize = new GSize(19, 19); iconBlue.shadowSize = new GSize(22, 20); iconBlue.iconAnchor = new GPoint(6, 20); iconBlue.infoWindowAnchor = new GPoint(5, 1); var iconRed = new GIcon(); iconRed.image = 'icon.png'; iconRed.shadow = ''; iconRed.iconSize = new GSize(19, 19); iconRed.shadowSize = new GSize(22, 20); iconRed.iconAnchor = new GPoint(6, 20); iconRed.infoWindowAnchor = new GPoint(5, 1); var customIcons = []; customIcons["restaurant"] = iconBlue; customIcons["bar"] = iconRed; function load() { if (GBrowserIsCompatible()) { var map = new GMap2(document.getElementById("map")); map.setMapType(G_SATELLITE_MAP); map.addControl(new GSmallMapControl()); map.addControl(new GMapTypeControl()); map.setCenter(new GLatLng(47.614495, -122.341861), 13); // Change this depending on the name of your PHP file GDownloadUrl("phpsqlajax_genxml.php", function(data) { var xml = GXml.parse(data); var markers = xml.documentElement.getElementsByTagName("marker"); for (var i = 0; i < markers.length; i++) { var name = markers[i].getAttribute("name"); var address = markers[i].getAttribute("address"); var type = markers[i].getAttribute("type"); var point = new GLatLng(parseFloat(markers[i].getAttribute("lat")), parseFloat(markers[i].getAttribute("lng"))); var marker = createMarker(point, name, address, type); map.addOverlay(marker); } }); } } function createMarker(point, name, address, type) { var marker = new GMarker(point, customIcons[type]); var html = "<b>" + name + "</b> <br/>" + address; GEvent.addListener(marker, 'click', function() { marker.openInfoWindowHtml(html); }); return marker; } //]]> (I suppose the php will be called by "GDownloadUrl("phpsqlajax_genxml.php", function(data) { ..." in the javascript part of the sourcecode of phpsqlajax_map.htm) Now I need another php file and the code snipplets for it, which creates an input form where I can add some new locations to the google map. Following code is used to create the xml file here: http://detektors.de/maptest/phpsqlajax_genxml.php The next step would be, trying to make an plugin for wordpress that I could easily post a blog entry with a new location on the same map, which displays already some other locations stored in the mysql database. thanks! <?php require("phpsqlajax_dbinfo.php"); function parseToXML($htmlStr) { $xmlStr=str_replace('<','<',$htmlStr); $xmlStr=str_replace('','>',$xmlStr); $xmlStr=str_replace('"','"',$xmlStr); $xmlStr=str_replace("'",''',$xmlStr); $xmlStr=str_replace("&",'&',$xmlStr); return $xmlStr; } // Opens a connection to a MySQL server $connection=mysql_connect ($host, $username, $password); if (!$connection) { die('Not connected : ' . mysql_error()); } // Set the active MySQL database $db_selected = mysql_select_db($database, $connection); if (!$db_selected) { die ('Can\'t use db : ' . mysql_error()); } // Select all the rows in the markers table $query = "SELECT * FROM markers WHERE 1"; $result = mysql_query($query); if (!$result) { die('Invalid query: ' . mysql_error()); } header("Content-type: text/xml"); // Start XML file, echo parent node echo ''; // Iterate through the rows, printing XML nodes for each while ($row = @mysql_fetch_assoc($result)){ // ADD TO XML DOCUMENT NODE echo ''; } // End XML file echo ''; ?

    Read the article

  • How to bind old user's SID to new user to remain NTFS file ownership and permissions after freshly reinstall of Windows?

    - by LiuYan ??
    Each time we reinstalled Windows, it will create a new SID for user even the username is as same as before. // example (not real SID format, just show the problem) user SID -------------------- liuyan S-old-501 // old SID before reinstall liuyan S-new-501 // new SID after reinstall The annoying problem after reinstall is NTFS file owership and permissions on hard drive disk are still associated with old user's SID. I want to keep the ownership and permission setting of NTFS files, then want to let the new user take the old user's SID, so that I can access files as before without permission problem. The cacls command line tool can't be used in such situation, because the file does belongs to new user, so it will failed with Access is denied error. and it can't change ownership. Even if I can change the owership via SubInACL tool, cacls can't remove the old user's permission because the old user does not exist on new installation, and can't copy the old user's permission to new user. So, can we simply bind old user's SID to new user on the freshly installed Windows ? Sample test batch @echo off REM Additional tools used in this script REM PsGetSid http://technet.microsoft.com/en-us/sysinternals/bb897417 REM SubInACL http://www.microsoft.com/en-us/download/details.aspx?id=23510 REM REM make sure these tools are added into PATH set account=MyUserAccount set password=long-password set dir=test set file=test.txt echo Creating user [%account%] with password [%password%]... pause net user %account% %password% /add psgetsid %account% echo Done ! echo Making directory [%dir%] ... pause mkdir %dir% dir %dir%* /q echo Done ! echo Changing permissions of directory [%dir%]: only [%account%] and [%UserDomain%\%UserName%] has full access permission... pause cacls %dir% /G %account%:F cacls %dir% /E /G %UserDomain%\%UserName%:F dir %dir%* /q cacls %dir% echo Done ! echo Changing ownership of directory [%dir%] to [%account%]... pause subinacl /file %dir% /setowner=%account% dir %dir%* /q echo Done ! echo RunAs [%account%] user to write a file [%file%] in directory [%dir%]... pause runas /noprofile /env /user:%account% "cmd /k echo some text %DATE% %TIME% > %dir%\%file%" dir %dir% /q echo Done ! echo Deleting and Recreating user [%account%] (reinstall simulation) ... pause net user %account% /delete net user %account% %password% /add psgetsid %account% echo Done ! %account% is recreated, it has a new SID now echo Now, use this "same" account [%account%] to access [%dir%], it will failed with "Access is denied" pause runas /noprofile /env /user:%account% "cmd /k cacls %dir%" REM runas /noprofile /env /user:%account% "cmd /k type %dir%\%file%" echo Done ! echo Changing ownership of directory [%dir%] to NEW [%account%]... pause subinacl /file %dir% /setowner=%account% dir %dir%* /q cacls %dir% echo Done ! As you can see, "Account Domain not found" is actually the OLD [%account%] user echo Deleting user [%account%] ... pause net user %account% /delete echo Done ! echo Deleting directory [%dir%]... pause rmdir %dir% /s /q echo Done !

    Read the article

  • How to grant secure access to an untrusted developer to an exisiting virtual host?

    - by Margaret Thorpe
    Our security policy does not permit ftpd on our servers. Our trusted developers use ftps to access our webservers and they have full access to the server. How do we grant limited access to a single untrusted developer for an existing virtual host. Ive configured rssh to only allow sftp to our untrusted developer, but we dont want him browsing around our other sites. I've investigated chroot, but it seems overly complex and more for restricting access to their home folders. I want to limit access to /srv/www/vhostx/ and below. Whats the best solution?

    Read the article

  • Where to download MS SQL Server 2005 Developer Edition?

    - by Mark
    Just got put in charge of a big web project. All I know is the web server is running MS SQL 2005, so I need something comparable to test locally. I figure developer edition is my best bet because it offers everything that the enterprise edition does, but is for development purposes only. But this page is pretty worthless http://www.microsoft.com/sqlserver/2005/en/us/developer.aspx Where do I actually download it? What about SQL 2005 Express? Would that meet my needs? I can't figure out all the differences between these stupid MS products.

    Read the article

  • EWS - How to search for items [message] between dates ?

    - by SomFred
    Hi, I am trying to search for message items between two dates from the inbox folder. I use the following restrictionType but it throws this error: firmt.RootFolder = null What am I doing wrong? There is some messages between the mentionned dates ;-) Thanks for your suggestions. using (ExchangeServiceBinding esb = new ExchangeServiceBinding()) { esb.Url = ConfigurationManager.AppSettings["ExchangeWebServicesURL"].ToString(); esb.RequestServerVersionValue = new RequestServerVersion(); esb.RequestServerVersionValue.Version = ExchangeVersionType.Exchange2007_SP1; esb.PreAuthenticate = true; esb.Credentials = new NetworkCredential(email, password); FindItemType findItemRequest = new FindItemType(); // paging IndexedPageViewType ipvt = new IndexedPageViewType(); ipvt.BasePoint = IndexBasePointType.Beginning; ipvt.MaxEntriesReturned = nombreMessage; ipvt.MaxEntriesReturnedSpecified = true; ipvt.Offset = offset; findItemRequest.Item = ipvt; // filter by dates AndType andType = new AndType(); List<SearchExpressionType> searchExps = new List<SearchExpressionType>(); RestrictionType restriction = new RestrictionType(); PathToUnindexedFieldType pteft = new PathToUnindexedFieldType { FieldURI = UnindexedFieldURIType.itemDateTimeSent }; IsGreaterThanOrEqualToType IsGreaterThanOrEqualTo = new IsGreaterThanOrEqualToType { Item = pteft, FieldURIOrConstant = new FieldURIOrConstantType { Item = new ConstantValueType { Value = DateTime.Today.AddDays(-6d).ToString() } } }; searchExps.Add(IsGreaterThanOrEqualTo); IsLessThanOrEqualToType IsLessThanOrEqualTo = new IsLessThanOrEqualToType { Item = pteft, FieldURIOrConstant = new FieldURIOrConstantType { Item = new ConstantValueType { Value = DateTime.Today.AddDays(1d).ToString() } } }; searchExps.Add(IsLessThanOrEqualTo); andType.Items = searchExps.ToArray(); restriction.Item = andType; findItemRequest.Restriction = restriction; //// Define the sort order of items. FieldOrderType[] fieldsOrder = new FieldOrderType[1]; fieldsOrder[0] = new FieldOrderType(); PathToUnindexedFieldType dateOrder = new PathToUnindexedFieldType { FieldURI = UnindexedFieldURIType.itemDateTimeReceived }; fieldsOrder[0].Item = dateOrder; fieldsOrder[0].Order = SortDirectionType.Descending; findItemRequest.SortOrder = fieldsOrder; findItemRequest.Traversal = ItemQueryTraversalType.Shallow; // define which item properties are returned in the response findItemRequest.ItemShape = new ItemResponseShapeType { BaseShape = DefaultShapeNamesType.IdOnly }; // identify which folder to search DistinguishedFolderIdType[] folderIDArray = new DistinguishedFolderIdType[1]; folderIDArray[0] = new DistinguishedFolderIdType { Id = DistinguishedFolderIdNameType.inbox }; // add folders to request findItemRequest.ParentFolderIds = folderIDArray; // find the messages FindItemResponseType findItemResponse = esb.FindItem(findItemRequest); //------------- ArrayOfResponseMessagesType responseMessages = findItemResponse.ResponseMessages; ResponseMessageType responseMessage = responseMessages.Items[0]; if (responseMessage is FindItemResponseMessageType) { FindItemResponseMessageType firmt = (responseMessage as FindItemResponseMessageType); *******FindItemParentType fipt = firmt.RootFolder;******** object obj = fipt.Item; // FindItem contains an array of items. ArrayOfRealItemsType realitems = (obj as ArrayOfRealItemsType); ItemType[] items = realitems.Items; // if no messages were found, then return null -- we're done if (items == null || items.Count() <= 0) return null; // FindItem never gets "all" the properties, so now that we've found them all, we need to get them all. BaseItemIdType[] itemIds = new BaseItemIdType[items.Count()]; for (int i = 0; i < items.Count(); i++) itemIds[i] = items[i].ItemId; GetItemType getItemType = new GetItemType { ItemIds = itemIds, ItemShape = new ItemResponseShapeType { BaseShape = DefaultShapeNamesType.AllProperties, BodyType = BodyTypeResponseType.Text, BodyTypeSpecified = true, AdditionalProperties = new BasePathToElementType[] { new PathToUnindexedFieldType { FieldURI = UnindexedFieldURIType.itemDateTimeSent }, new PathToUnindexedFieldType { FieldURI = UnindexedFieldURIType.messageFrom }, new PathToUnindexedFieldType { FieldURI = UnindexedFieldURIType.messageIsRead }, new PathToUnindexedFieldType { FieldURI = UnindexedFieldURIType.messageSender }, new PathToUnindexedFieldType { FieldURI = UnindexedFieldURIType.messageToRecipients }, new PathToUnindexedFieldType { FieldURI = UnindexedFieldURIType.messageCcRecipients }, new PathToUnindexedFieldType { FieldURI = UnindexedFieldURIType.messageBccRecipients } } } }; GetItemResponseType getItemResponse = esb.GetItem(getItemType); messages = ReadItems(getItemResponse, items.Count()); }

    Read the article

  • As a C# developer, would you learn Java to develop for Android or use MonoDroid instead?

    - by Dan Tao
    I'd consider myself pretty well versed in C#. It's my language of choice at the moment, and it's where basically all my professional experience lies. Still, I'm puzzled by the existence of the MonoDroid project. My understanding has always been that C# and Java are very close. Like, if you know one, you can learn the other really quickly. So, as I've considered developing my first Android app, I just assumed I would familiarize myself with Java enough to get started and then just sort of learn as I go. Wouldn't this make more sense than using MonoDroid, which is likely to be less feature-rich than the Java Android SDK, and requires learning its own API (albeit a .NET API) anyway? I just feel like it would be better to learn a new language (and an extremely popular one at that) and get some experience in it—when it's so close to what you already know anyway—rather than stick with a technology you're experienced with, without gaining any more valuable skills. Maybe I'm grossly misrepresenting the average potential MonoDroid user. Maybe it's more for people who are experienced in Java and .NET and just prefer .NET. Or maybe (in fact it's likely) there are other factors I just haven't considered. I'm just wondering, why would you use MonoDroid instead of just developing for Android using Java?

    Read the article

  • How can I convince my boss to invest into the developer environment?

    - by user95291
    Our boss said that developers should have fewer mistakes so the company would have money for displays, servers etc. An always mentioned example is a late firing of an underperforming colleague whose salary would have covered some of these expenses. On the other hand it happened a few times that it took a few days to free up some disk space on our servers since we can't get any more disk. The cost of mandays was definitely higher than the cost of a new HDD. Another example is that we use 14-15" notebooks for development and most of the developers get external displays after they spent one year at the company. The price of a 22-24" display is just a small fraction of a developers annual salary. Devs say that they like the company because of other reasons (high quality code, interesting projects etc.) but this kind of issues not just simply time-consuming but also demotivate them. In the point of view of the developers it seems that the boss always can find an issue in the past which they could have been done better so it's pointless to work better to get for a second display/HDD/whatever. How can I convince my boss to invest more into development environment? Is it possible to break this endless loop?

    Read the article

  • Why do memory-managed languages retain the `new` keyword?

    - by Channel72
    The new keyword in languages like Java, Javascript, and C# creates a new instance of a class. This syntax seems to have been inherited from C++, where new is used specifically to allocate a new instance of a class on the heap, and return a pointer to the new instance. In C++, this is not the only way to construct an object. You can also construct an object on the stack, without using new - and in fact, this way of constructing objects is much more common in C++. So, coming from a C++ background, the new keyword in languages like Java, Javascript, and C# seemed natural and obvious to me. Then I started to learn Python, which doesn't have the new keyword. In Python, an instance is constructed simply by calling the constructor, like: f = Foo() At first, this seemed a bit off to me, until it occurred to me that there's no reason for Python to have new, because everything is an object so there's no need to disambiguate between various constructor syntaxes. But then I thought - what's really the point of new in Java? Why should we say Object o = new Object();? Why not just Object o = Object();? In C++ there's definitely a need for new, since we need to distinguish between allocating on the heap and allocating on the stack, but in Java all objects are constructed on the heap, so why even have the new keyword? The same question could be asked for Javascript. In C#, which I'm much less familiar with, I think new may have some purpose in terms of distinguishing between object types and value types, but I'm not sure. Regardless, it seems to me that many languages which came after C++ simply "inherited" the new keyword - without really needing it. It's almost like a vestigial keyword. We don't seem to need it for any reason, and yet it's there. Question: Am I correct about this? Or is there some compelling reason that new needs to be in C++-inspired memory-managed languages like Java, Javascript and C#?

    Read the article

  • What technologies are needed to be a freelance web developer / designer targeting small businesses?

    - by Jason Wirth
    First off, I'm not looking for this answer: "learn PHP/MySQL, JQuery, HTML/CSS...." My background, I wear many hats, and do many things. Currently I manage investment accounts with a business partner who is also a friend. He happens to be attending business / law school perusing a joint JD and MBA. As a result, we're putting our into "coast", maintaining our current clients, but not acquiring more. Recently I've picked up some freelance graphic design / web development / online marketing side work (Photoshop, HTML/CSS, WordPress) through some personal networks. The work is enjoyable; now I'm thinking about expanding it into a larger business with these primary goals: augment my finances (I'm shooting for about $1,000-2,000 per mo.), learn new technologies, involve myself with meaningful work. As an entrepreneur I don't mind the aspects of running a business that hassle other freelancers... -- the marketing -- the billing -- etc. I'm considering targeting the small to middle market businesses and organizations where I can contribute in marketing, design, and development building projects from the ground up. Thus I'll have freedom to decide the specific technology (I won't have to work with an existing code base). What kinds of projects should I focus on? What technologies are a good fit for this style of work? For example: It might be fun to develop with Ruby on Rails. However, maybe a lot of projects would be rolling out e-commerce solutions. Thus, I should focus on PHP due to more shopping cart options, skipping ROR entirely.

    Read the article

  • How to edit item in a listbox shown from reading a .csv file?

    - by Shuvo
    I am working in a project where my application can open a .csv file and read data from it. The .csv file contains the latitude, longitude of places. The application reads data from the file shows it in a static map and display icon on the right places. The application can open multiple file at a time and it opens with a new tab every time. But I am having trouble in couple of cases When I am trying to add a new point to the .csv file opened. I am able to write new point on the same file instead adding a new point data to the existing its replacing others and writing the new point only. I cannot use selectedIndexChange event to perform edit option on the listbox and then save the file. Any direction would be great. using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Windows.Forms; using System.IO; namespace CourseworkExample { public partial class Form1 : Form { public GPSDataPoint gpsdp; List<GPSDataPoint> data; List<PictureBox> pictures; List<TabPage> tabs; public static int pn = 0; private TabPage currentComponent; private Bitmap bmp1; string[] symbols = { "hospital", "university" }; Image[] symbolImages; ListBox lb = new ListBox(); string name = ""; string path = ""; public Form1() { InitializeComponent(); data = new List<GPSDataPoint>(); pictures = new List<PictureBox>(); tabs = new List<TabPage>(); symbolImages = new Image[symbols.Length]; for (int i = 0; i < 2; i++) { string location = "data/" + symbols[i] + ".png"; symbolImages[i] = Image.FromFile(location); } } private void openToolStripMenuItem_Click(object sender, EventArgs e) { FileDialog ofd = new OpenFileDialog(); string filter = "CSV File (*.csv)|*.csv"; ofd.Filter = filter; DialogResult dr = ofd.ShowDialog(); if (dr.Equals(DialogResult.OK)) { int i = ofd.FileName.LastIndexOf("\\"); name = ofd.FileName; path = ofd.FileName; if (i > 0) { name = ofd.FileName.Substring(i + 1); path = ofd.FileName.Substring(0, i + 1); } TextReader input = new StreamReader(ofd.FileName); string mapName = input.ReadLine(); GPSDataPoint gpsD = new GPSDataPoint(); gpsD.setBounds(input.ReadLine()); string s; while ((s = input.ReadLine()) != null) { gpsD.addWaypoint(s); } input.Close(); TabPage tabPage = new TabPage(); tabPage.Location = new System.Drawing.Point(4, 22); tabPage.Name = "tabPage" + pn; lb.Width = 300; int selectedindex = lb.SelectedIndex; lb.Items.Add(mapName); lb.Items.Add("Bounds"); lb.Items.Add(gpsD.Bounds[0] + " " + gpsD.Bounds[1] + " " + gpsD.Bounds[2] + " " + gpsD.Bounds[3]); lb.Items.Add("Waypoint"); foreach (WayPoint wp in gpsD.DataList) { lb.Items.Add(wp.Name + " " + wp.Latitude + " " + wp.Longitude + " " + wp.Ele + " " + wp.Sym); } tabPage.Controls.Add(lb); pn++; tabPage.Padding = new System.Windows.Forms.Padding(3); tabPage.Size = new System.Drawing.Size(192, 74); tabPage.TabIndex = 0; tabPage.Text = name; tabPage.UseVisualStyleBackColor = true; tabs.Add(tabPage); tabControl1.Controls.Add(tabPage); tabPage = new TabPage(); tabPage.Location = new System.Drawing.Point(4, 22); tabPage.Name = "tabPage" + pn; pn++; tabPage.Padding = new System.Windows.Forms.Padding(3); tabPage.Size = new System.Drawing.Size(192, 74); tabPage.TabIndex = 0; tabPage.Text = mapName; string location = path + mapName; tabPage.UseVisualStyleBackColor = true; tabs.Add(tabPage); PictureBox pb = new PictureBox(); pb.Name = "pictureBox" + pn; pb.Image = Image.FromFile(location); tabControl2.Controls.Add(tabPage); pb.Width = pb.Image.Width; pb.Height = pb.Image.Height; tabPage.Controls.Add(pb); currentComponent = tabPage; tabPage.Width = pb.Width; tabPage.Height = pb.Height; pn++; tabControl2.Width = pb.Width; tabControl2.Height = pb.Height; bmp1 = (Bitmap)pb.Image; int lx, ly; float realWidth = gpsD.Bounds[1] - gpsD.Bounds[3]; float imageW = pb.Image.Width; float dx = imageW * (gpsD.Bounds[1] - gpsD.getWayPoint(0).Longitude) / realWidth; float realHeight = gpsD.Bounds[0] - gpsD.Bounds[2]; float imageH = pb.Image.Height; float dy = imageH * (gpsD.Bounds[0] - gpsD.getWayPoint(0).Latitude) / realHeight; lx = (int)dx; ly = (int)dy; using (Graphics g = Graphics.FromImage(bmp1)) { Rectangle rect = new Rectangle(lx, ly, 20, 20); if (gpsD.getWayPoint(0).Sym.Equals("")) { g.DrawRectangle(new Pen(Color.Red), rect); } else { if (gpsD.getWayPoint(0).Sym.Equals("hospital")) { g.DrawImage(symbolImages[0], rect); } else { if (gpsD.getWayPoint(0).Sym.Equals("university")) { g.DrawImage(symbolImages[1], rect); } } } } pb.Image = bmp1; pb.Invalidate(); } } private void openToolStripMenuItem_Click_1(object sender, EventArgs e) { FileDialog ofd = new OpenFileDialog(); string filter = "CSV File (*.csv)|*.csv"; ofd.Filter = filter; DialogResult dr = ofd.ShowDialog(); if (dr.Equals(DialogResult.OK)) { int i = ofd.FileName.LastIndexOf("\\"); name = ofd.FileName; path = ofd.FileName; if (i > 0) { name = ofd.FileName.Substring(i + 1); path = ofd.FileName.Substring(0, i + 1); } TextReader input = new StreamReader(ofd.FileName); string mapName = input.ReadLine(); GPSDataPoint gpsD = new GPSDataPoint(); gpsD.setBounds(input.ReadLine()); string s; while ((s = input.ReadLine()) != null) { gpsD.addWaypoint(s); } input.Close(); TabPage tabPage = new TabPage(); tabPage.Location = new System.Drawing.Point(4, 22); tabPage.Name = "tabPage" + pn; ListBox lb = new ListBox(); lb.Width = 300; lb.Items.Add(mapName); lb.Items.Add("Bounds"); lb.Items.Add(gpsD.Bounds[0] + " " + gpsD.Bounds[1] + " " + gpsD.Bounds[2] + " " + gpsD.Bounds[3]); lb.Items.Add("Waypoint"); foreach (WayPoint wp in gpsD.DataList) { lb.Items.Add(wp.Name + " " + wp.Latitude + " " + wp.Longitude + " " + wp.Ele + " " + wp.Sym); } tabPage.Controls.Add(lb); pn++; tabPage.Padding = new System.Windows.Forms.Padding(3); tabPage.Size = new System.Drawing.Size(192, 74); tabPage.TabIndex = 0; tabPage.Text = name; tabPage.UseVisualStyleBackColor = true; tabs.Add(tabPage); tabControl1.Controls.Add(tabPage); tabPage = new TabPage(); tabPage.Location = new System.Drawing.Point(4, 22); tabPage.Name = "tabPage" + pn; pn++; tabPage.Padding = new System.Windows.Forms.Padding(3); tabPage.Size = new System.Drawing.Size(192, 74); tabPage.TabIndex = 0; tabPage.Text = mapName; string location = path + mapName; tabPage.UseVisualStyleBackColor = true; tabs.Add(tabPage); PictureBox pb = new PictureBox(); pb.Name = "pictureBox" + pn; pb.Image = Image.FromFile(location); tabControl2.Controls.Add(tabPage); pb.Width = pb.Image.Width; pb.Height = pb.Image.Height; tabPage.Controls.Add(pb); currentComponent = tabPage; tabPage.Width = pb.Width; tabPage.Height = pb.Height; pn++; tabControl2.Width = pb.Width; tabControl2.Height = pb.Height; bmp1 = (Bitmap)pb.Image; int lx, ly; float realWidth = gpsD.Bounds[1] - gpsD.Bounds[3]; float imageW = pb.Image.Width; float dx = imageW * (gpsD.Bounds[1] - gpsD.getWayPoint(0).Longitude) / realWidth; float realHeight = gpsD.Bounds[0] - gpsD.Bounds[2]; float imageH = pb.Image.Height; float dy = imageH * (gpsD.Bounds[0] - gpsD.getWayPoint(0).Latitude) / realHeight; lx = (int)dx; ly = (int)dy; using (Graphics g = Graphics.FromImage(bmp1)) { Rectangle rect = new Rectangle(lx, ly, 20, 20); if (gpsD.getWayPoint(0).Sym.Equals("")) { g.DrawRectangle(new Pen(Color.Red), rect); } else { if (gpsD.getWayPoint(0).Sym.Equals("hospital")) { g.DrawImage(symbolImages[0], rect); } else { if (gpsD.getWayPoint(0).Sym.Equals("university")) { g.DrawImage(symbolImages[1], rect); } } } } pb.Image = bmp1; pb.Invalidate(); MessageBox.Show(data.ToString()); } } private void exitToolStripMenuItem_Click(object sender, EventArgs e) { this.Close(); } private void addBtn_Click(object sender, EventArgs e) { string wayName = nameTxtBox.Text; float wayLat = Convert.ToSingle(latTxtBox.Text); float wayLong = Convert.ToSingle(longTxtBox.Text); float wayEle = Convert.ToSingle(elevTxtBox.Text); WayPoint wp = new WayPoint(wayName, wayLat, wayLong, wayEle); GPSDataPoint gdp = new GPSDataPoint(); data = new List<GPSDataPoint>(); gdp.Add(wp); lb.Items.Add(wp.Name + " " + wp.Latitude + " " + wp.Longitude + " " + wp.Ele + " " + wp.Sym); lb.Refresh(); StreamWriter sr = new StreamWriter(name); sr.Write(lb); sr.Close(); DialogResult result = MessageBox.Show("Save in New File?","Save", MessageBoxButtons.YesNo); if (result == DialogResult.Yes) { SaveFileDialog saveDialog = new SaveFileDialog(); saveDialog.FileName = "default.csv"; DialogResult saveResult = saveDialog.ShowDialog(); if (saveResult == DialogResult.OK) { sr = new StreamWriter(saveDialog.FileName, true); sr.WriteLine(wayName + "," + wayLat + "," + wayLong + "," + wayEle); sr.Close(); } } else { // sr = new StreamWriter(name, true); // sr.WriteLine(wayName + "," + wayLat + "," + wayLong + "," + wayEle); sr.Close(); } MessageBox.Show(name + path); } } } GPSDataPoint.cs using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.IO; namespace CourseworkExample { public class GPSDataPoint { private float[] bounds; private List<WayPoint> dataList; public GPSDataPoint() { dataList = new List<WayPoint>(); } internal void setBounds(string p) { string[] b = p.Split(','); bounds = new float[b.Length]; for (int i = 0; i < b.Length; i++) { bounds[i] = Convert.ToSingle(b[i]); } } public float[] Bounds { get { return bounds; } } internal void addWaypoint(string s) { WayPoint wp = new WayPoint(s); dataList.Add(wp); } public WayPoint getWayPoint(int i) { if (i < dataList.Count) { return dataList[i]; } else return null; } public List<WayPoint> DataList { get { return dataList; } } internal void Add(WayPoint wp) { dataList.Add(wp); } } } WayPoint.cs using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace CourseworkExample { public class WayPoint { private string name; private float ele; private float latitude; private float longitude; private string sym; public WayPoint(string name, float latitude, float longitude, float elevation) { this.name = name; this.latitude = latitude; this.longitude = longitude; this.ele = elevation; } public WayPoint() { name = "no name"; ele = 3.5F; latitude = 3.5F; longitude = 0.0F; sym = "no symbol"; } public WayPoint(string s) { string[] bits = s.Split(','); name = bits[0]; longitude = Convert.ToSingle(bits[2]); latitude = Convert.ToSingle(bits[1]); if (bits.Length > 4) sym = bits[4]; else sym = ""; try { ele = Convert.ToSingle(bits[3]); } catch (Exception e) { ele = 0.0f; } } public float Longitude { get { return longitude; } set { longitude = value; } } public float Latitude { get { return latitude; } set { latitude = value; } } public float Ele { get { return ele; } set { ele = value; } } public string Name { get { return name; } set { name = value; } } public string Sym { get { return sym; } set { sym = value; } } } } .csv file data birthplace.png 51.483788,-0.351906,51.460745,-0.302982 Born Here,51.473805,-0.32532,-,hospital Danced here,51,483805,-0.32532,-,hospital

    Read the article

  • ASP.NET Web API Exception Handling

    - by Fredrik N
    When I talk about exceptions in my product team I often talk about two kind of exceptions, business and critical exceptions. Business exceptions are exceptions thrown based on “business rules”, for example if you aren’t allowed to do a purchase. Business exceptions in most case aren’t important to log into a log file, they can directly be shown to the user. An example of a business exception could be "DeniedToPurchaseException”, or some validation exceptions such as “FirstNameIsMissingException” etc. Critical Exceptions are all other kind of exceptions such as the SQL server is down etc. Those kind of exception message need to be logged and should not reach the user, because they can contain information that can be harmful if it reach out to wrong kind of users. I often distinguish business exceptions from critical exceptions by creating a base class called BusinessException, then in my error handling code I catch on the type BusinessException and all other exceptions will be handled as critical exceptions. This blog post will be about different ways to handle exceptions and how Business and Critical Exceptions could be handled. Web API and Exceptions the basics When an exception is thrown in a ApiController a response message will be returned with a status code set to 500 and a response formatted by the formatters based on the “Accept” or “Content-Type” HTTP header, for example JSON or XML. Here is an example:   public IEnumerable<string> Get() { throw new ApplicationException("Error!!!!!"); return new string[] { "value1", "value2" }; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } The response message will be: HTTP/1.1 500 Internal Server Error Content-Length: 860 Content-Type: application/json; charset=utf-8 { "ExceptionType":"System.ApplicationException","Message":"Error!!!!!","StackTrace":" at ..."} .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   The stack trace will be returned to the client, this is because of making it easier to debug. Be careful so you don’t leak out some sensitive information to the client. So as long as you are developing your API, this is not harmful. In a production environment it can be better to log exceptions and return a user friendly exception instead of the original exception. There is a specific exception shipped with ASP.NET Web API that will not use the formatters based on the “Accept” or “Content-Type” HTTP header, it is the exception is the HttpResponseException class. Here is an example where the HttpReponseExcetpion is used: // GET api/values [ExceptionHandling] public IEnumerable<string> Get() { throw new HttpResponseException(new HttpResponseMessage(HttpStatusCode.InternalServerError)); return new string[] { "value1", "value2" }; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } The response will not contain any content, only header information and the status code based on the HttpStatusCode passed as an argument to the HttpResponseMessage. Because the HttpResponsException takes a HttpResponseMessage as an argument, we can give the response a content: public IEnumerable<string> Get() { throw new HttpResponseException(new HttpResponseMessage(HttpStatusCode.InternalServerError) { Content = new StringContent("My Error Message"), ReasonPhrase = "Critical Exception" }); return new string[] { "value1", "value2" }; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   The code above will have the following response:   HTTP/1.1 500 Critical Exception Content-Length: 5 Content-Type: text/plain; charset=utf-8 My Error Message .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } The Content property of the HttpResponseMessage doesn’t need to be just plain text, it can also be other formats, for example JSON, XML etc. By using the HttpResponseException we can for example catch an exception and throw a user friendly exception instead: public IEnumerable<string> Get() { try { DoSomething(); return new string[] { "value1", "value2" }; } catch (Exception e) { throw new HttpResponseException(new HttpResponseMessage(HttpStatusCode.InternalServerError) { Content = new StringContent("An error occurred, please try again or contact the administrator."), ReasonPhrase = "Critical Exception" }); } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   Adding a try catch to every ApiController methods will only end in duplication of code, by using a custom ExceptionFilterAttribute or our own custom ApiController base class we can reduce code duplicationof code and also have a more general exception handler for our ApiControllers . By creating a custom ApiController’s and override the ExecuteAsync method, we can add a try catch around the base.ExecuteAsync method, but I prefer to skip the creation of a own custom ApiController, better to use a solution that require few files to be modified. The ExceptionFilterAttribute has a OnException method that we can override and add our exception handling. Here is an example: using System; using System.Diagnostics; using System.Net; using System.Net.Http; using System.Web.Http; using System.Web.Http.Filters; public class ExceptionHandlingAttribute : ExceptionFilterAttribute { public override void OnException(HttpActionExecutedContext context) { if (context.Exception is BusinessException) { throw new HttpResponseException(new HttpResponseMessage(HttpStatusCode.InternalServerError) { Content = new StringContent(context.Exception.Message), ReasonPhrase = "Exception" }); } //Log Critical errors Debug.WriteLine(context.Exception); throw new HttpResponseException(new HttpResponseMessage(HttpStatusCode.InternalServerError) { Content = new StringContent("An error occurred, please try again or contact the administrator."), ReasonPhrase = "Critical Exception" }); } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   Note: Something to have in mind is that the ExceptionFilterAttribute will be ignored if the ApiController action method throws a HttpResponseException. The code above will always make sure a HttpResponseExceptions will be returned, it will also make sure the critical exceptions will show a more user friendly message. The OnException method can also be used to log exceptions. By using a ExceptionFilterAttribute the Get() method in the previous example can now look like this: public IEnumerable<string> Get() { DoSomething(); return new string[] { "value1", "value2" }; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } To use the an ExceptionFilterAttribute, we can for example add the ExceptionFilterAttribute to our ApiControllers methods or to the ApiController class definition, or register it globally for all ApiControllers. You can read more about is here. Note: If something goes wrong in the ExceptionFilterAttribute and an exception is thrown that is not of type HttpResponseException, a formatted exception will be thrown with stack trace etc to the client. How about using a custom IHttpActionInvoker? We can create our own IHTTPActionInvoker and add Exception handling to the invoker. The IHttpActionInvoker will be used to invoke the ApiController’s ExecuteAsync method. Here is an example where the default IHttpActionInvoker, ApiControllerActionInvoker, is used to add exception handling: public class MyApiControllerActionInvoker : ApiControllerActionInvoker { public override Task<HttpResponseMessage> InvokeActionAsync(HttpActionContext actionContext, System.Threading.CancellationToken cancellationToken) { var result = base.InvokeActionAsync(actionContext, cancellationToken); if (result.Exception != null && result.Exception.GetBaseException() != null) { var baseException = result.Exception.GetBaseException(); if (baseException is BusinessException) { return Task.Run<HttpResponseMessage>(() => new HttpResponseMessage(HttpStatusCode.InternalServerError) { Content = new StringContent(baseException.Message), ReasonPhrase = "Error" }); } else { //Log critical error Debug.WriteLine(baseException); return Task.Run<HttpResponseMessage>(() => new HttpResponseMessage(HttpStatusCode.InternalServerError) { Content = new StringContent(baseException.Message), ReasonPhrase = "Critical Error" }); } } return result; } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } You can register the IHttpActionInvoker with your own IoC to resolve the MyApiContollerActionInvoker, or add it in the Global.asax: GlobalConfiguration.Configuration.Services.Remove(typeof(IHttpActionInvoker), GlobalConfiguration.Configuration.Services.GetActionInvoker()); GlobalConfiguration.Configuration.Services.Add(typeof(IHttpActionInvoker), new MyApiControllerActionInvoker()); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   How about using a Message Handler for Exception Handling? By creating a custom Message Handler, we can handle error after the ApiController and the ExceptionFilterAttribute is invoked and in that way create a global exception handler, BUT, the only thing we can take a look at is the HttpResponseMessage, we can’t add a try catch around the Message Handler’s SendAsync method. The last Message Handler that will be used in the Wep API pipe-line is the HttpControllerDispatcher and this Message Handler is added to the HttpServer in an early stage. The HttpControllerDispatcher will use the IHttpActionInvoker to invoke the ApiController method. The HttpControllerDipatcher has a try catch that will turn ALL exceptions into a HttpResponseMessage, so that is the reason why a try catch around the SendAsync in a custom Message Handler want help us. If we create our own Host for the Wep API we could create our own custom HttpControllerDispatcher and add or exception handler to that class, but that would be little tricky but is possible. We can in a Message Handler take a look at the HttpResponseMessage’s IsSuccessStatusCode property to see if the request has failed and if we throw the HttpResponseException in our ApiControllers, we could use the HttpResponseException and give it a Reason Phrase and use that to identify business exceptions or critical exceptions. I wouldn’t add an exception handler into a Message Handler, instead I should use the ExceptionFilterAttribute and register it globally for all ApiControllers. BUT, now to another interesting issue. What will happen if we have a Message Handler that throws an exception?  Those exceptions will not be catch and handled by the ExceptionFilterAttribute. I found a  bug in my previews blog post about “Log message Request and Response in ASP.NET WebAPI” in the MessageHandler I use to log incoming and outgoing messages. Here is the code from my blog before I fixed the bug:   public abstract class MessageHandler : DelegatingHandler { protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken) { var corrId = string.Format("{0}{1}", DateTime.Now.Ticks, Thread.CurrentThread.ManagedThreadId); var requestInfo = string.Format("{0} {1}", request.Method, request.RequestUri); var requestMessage = await request.Content.ReadAsByteArrayAsync(); await IncommingMessageAsync(corrId, requestInfo, requestMessage); var response = await base.SendAsync(request, cancellationToken); var responseMessage = await response.Content.ReadAsByteArrayAsync(); await OutgoingMessageAsync(corrId, requestInfo, responseMessage); return response; } protected abstract Task IncommingMessageAsync(string correlationId, string requestInfo, byte[] message); protected abstract Task OutgoingMessageAsync(string correlationId, string requestInfo, byte[] message); } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   If a ApiController throws a HttpResponseException, the Content property of the HttpResponseMessage from the SendAsync will be NULL. So a null reference exception is thrown within the MessageHandler. The yellow screen of death will be returned to the client, and the content is HTML and the Http status code is 500. The bug in the MessageHandler was solved by adding a check against the HttpResponseMessage’s IsSuccessStatusCode property: public abstract class MessageHandler : DelegatingHandler { protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken) { var corrId = string.Format("{0}{1}", DateTime.Now.Ticks, Thread.CurrentThread.ManagedThreadId); var requestInfo = string.Format("{0} {1}", request.Method, request.RequestUri); var requestMessage = await request.Content.ReadAsByteArrayAsync(); await IncommingMessageAsync(corrId, requestInfo, requestMessage); var response = await base.SendAsync(request, cancellationToken); byte[] responseMessage; if (response.IsSuccessStatusCode) responseMessage = await response.Content.ReadAsByteArrayAsync(); else responseMessage = Encoding.UTF8.GetBytes(response.ReasonPhrase); await OutgoingMessageAsync(corrId, requestInfo, responseMessage); return response; } protected abstract Task IncommingMessageAsync(string correlationId, string requestInfo, byte[] message); protected abstract Task OutgoingMessageAsync(string correlationId, string requestInfo, byte[] message); } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } If we don’t handle the exceptions that can occur in a custom Message Handler, we can have a hard time to find the problem causing the exception. The savior in this case is the Global.asax’s Application_Error: protected void Application_Error() { var exception = Server.GetLastError(); Debug.WriteLine(exception); } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } I would recommend you to add the Application_Error to the Global.asax and log all exceptions to make sure all kind of exception is handled. Summary There are different ways we could add Exception Handling to the Wep API, we can use a custom ApiController, ExceptionFilterAttribute, IHttpActionInvoker or Message Handler. The ExceptionFilterAttribute would be a good place to add a global exception handling, require very few modification, just register it globally for all ApiControllers, even the IHttpActionInvoker can be used to minimize the modifications of files. Adding the Application_Error to the global.asax is a good way to catch all unhandled exception that can occur, for example exception thrown in a Message Handler.   If you want to know when I have posted a blog post, you can follow me on twitter @fredrikn

    Read the article

< Previous Page | 209 210 211 212 213 214 215 216 217 218 219 220  | Next Page >