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  • Git workflow for two tight-knit projects

    - by Pioul
    Two very similar projects I'm maintaining an online Markdown editor using Git as RCS (and accessorily made available on GitHub). From this web app, I've created a Chrome app: the code is the same, aside from some Chrome technicalities. I care about open sourcing these two projects. Still, the Chrome app's code being the same as the web app's except for some dull details, I've first chosen to (1) not publish the Chrome app on GitHub, and (2) not use Git to manage its code. Instead, I would manually review the web app's commits, then replicate the few changes in the Chrome app. … slightly drifting apart However, I've decided to add a feature to the Chrome app only. So, even though both codebases will remain broadly similar, they'll be diverging enough to make me reconsider the rationale behind my initial decision to not version control nor share the Chrome app's source code. Since I'm now willing to use Git to version control both apps, and that I want to share both of them on GitHub, how should I go about it? Should I use two different repositories, or one repo with two long-running branches? What would be the pros and cons of each approach in that context? What would be the easiest/fastest way to regularly "import" commits from the web app to the Chrome app, since the web app is going to remain the master branch? Is cherry-picking the only solution?

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  • Integrating external computer into a domain - some recommendations please

    - by TomTom
    Given: * A multi loation company. Every office has local routers that connect to a central VPN capable rouer in a data center. All fine so far. We now need to move a computer off site into a hosting center across the globe, to get it closer to some supplier computers we work for. it will run limited logic but latency is important, and our latency so far is too large. This computer will be in a data center and does no require incoming connections except for adminsitrative purposes, although it needs outgoing connetions. I have no real chance to put one of my VPN routers there, sadly - otherwise I would have no problem. Usage of RRAs is not recommended (we had various probblems there over time). I could deal with it. The computer MUSt integrate into the corporate structure via VPN and join the domain and be fully "tracked" (controlled for performance). What is the best suggestion? So far it looks like my best bets woudl be to log in via RRAS and deal with whatever issues arise there plus uise the local firewall the limit incoming connections to this computer to what is needed (which runs down to an emergency RDP connection allowance). Anyone a better idea?

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  • how to throttle http requests on a linux machine?

    - by hooraygradschool
    EDIT: here is the summery: i need to reduce max connections preferably system wide on Ubuntu 11.04 but at least within Google Chrome. i do not need or want to throttle bandwidth, Verizon seems to only care about the number of connections so that is all i want to change. also, i don't want to use firefox unless i have to, i have three other machines all using chrome and synced and i just prefer it over firefox. i use tethering for my home internet connection via my verizon cell phone. without paying for it. this works just fine for streaming netflix via my nintendo wii and pretty much every other conceivable use ive had for it. except, during heavy usage with multiple tabs open on my laptop, the network connection on my phone will just turn off, then on again, then off, but it never fully connects. i think, based on this and other questions that this is caused by verizon getting too many http requests from my phone. is there some software, script, setting or otherwise that would allow me to throttle my requests to say, 5 or 10 or whatever it turns out is 1 less than verizon is looking for, so that my cell's network connection is not lost? i would far prefer a slow down rather than complete shut off of my internet connection. i am almost certain is from quantity of requests and not related to data, because, as i mentioned, netflix will run all day without a hitch, and that uses more data than anything else i would be doing. if i had a router i am pretty sure there are settings i could easily change to only allow so many requests at a time ... but in this case, my phone is my router, so no settings. im using ubuntu 11.04 on my netbook with an htc incredible on verizon (not that the phone details are relevant) i have been trying to figure this out for quite some time, currently the only fix is ensure that all requests are stopped and then sometimes it works again, other times i have to manually turn my 3g service off and then back on. thank you so much for any assistance!

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  • Changing the name of a binary packaged application and its evoking command

    - by jerkstore
    I have taken the source code of a large project, App A, and made many modifications to it to produce my version, App B. Both App A and App B compile cleanly on Debian and Red Hat and now I would like to build binary packages for both platforms. The last modification I need to make is ensuring App B can be installed alongside App A without any interference. I should be able to evoke both application-a and application-b in the terminal and have both be listed as separate software in whatever desktop environment is present. The projects have a debian/ folder (containing rules, control, etc.) and an rpm/ folder containing a SPEC file. Currently, building and installing the .rpm and .deb packages works except that App B is recognized as App A and therefore does not meet the aforementioned requirements. ldd shows the programs have the same exact dependencies and I am not able to pursue static linking of libraries. What modifications do I need to make to my project to achieve the desired outcome? Please be specific as I do not have much experience with the packaging process.

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  • how to remove location block from $uri in nginx configuration?

    - by Jason
    I have a rewrite in my ngix conf file that works properly except it seems to include the location block as part of the $uri variable. I only want the path after the location block. My current config code is: location /cargo { try_files $uri $uri/ /cargo/index.php?_REWRITE_COMMAND=$uri&args; } Using an example url of http://localhost/cargo/testpage the redirect works, however the value of the "_REWRITE_COMMAND" parameter received by my php file is "/cargo/testpage". I need to strip off the location block and just have "testpage" as the $uri I am pretty sure there is a regex syntax to split the $uri and assign it to a new variable using $1 $2 etc, but I can't find any example to do just a variable assignment using a regex that is not part of a rewrite statement. I've been looking and trying for hours and I just can't seem to get past this last step. I also know I could just strip this out on the application code, but the reason I want to try to fix it in the nginx conf is for compatibility reasons as it also runs on Apache. I also should say that I have figured out a really hacky way to do it, but it involves an "if" statement to check for file existance and the documentation specifically says not to do it that way. -- UPDATE: ANSWERED BY theuni: The regex goes in the location block definition. one note of caution is that php handler location needs to be ABOVE this location, otherwise you will get a server error because it goes into an infinite redirect loop location ~ ^/cargo/(.*) { try_files $1 /cargo/$1/ /cargo/index.php?_REWRITE_COMMAND=$1&args; }

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  • Windows user moving to Ubuntu 12.04. Where are the system tools, or equivalents?

    - by Big Endian
    I am a Windows user who has begun experimenting with Ubuntu. Ubuntu seems great, but for all the things it seems like I CAN'T do. How do I get to advanced administration stuff, like the list of drivers, all of the installed software, and something equivalent to Windows' Device Manager. I always heard that Linux was supposed to be very raw, and you had to have lots of computer experience to make it work. This seems just the opposite. Ubuntu seems very modern and user friendly, better in some regards than any operating system I have seen. Unfortunately, I can't find any of the guts of this system beneath all of the user friendly frosting... gunk... crap... stuff. I'm reminded more and more of an Apple computer (except Linux is more affordable :). So how do I peel back this layer and start using the computer? A solution other than installing Gnome 3 would be appreciated.

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  • Fedora 13 becomes unresponsive when too many applications running.

    - by user61766
    I am using Fedora 13 64bit on Dell Vostro full 4GB RAM system with default Gnome GUI. This is very annoying problem that I don't how to fix except by rebooting the whole PC. When I have too many applications running ( like browser windows), the system start acting sluggish. The fist symptoms appear in Eclipse IDE which becomes so terrible it just becomes frozen for sometime one whole minute after I try to edit something in the editor. Then Firefox seems like it has crashed. Google Chrome becomes very unresponsive as well. All GUI applications including File manager becomes unresponsive. When I check System Monitor, the CPU is still around 20% and memory is at 80% but the system seems getting fried up. This progressively becomes worse until I soft reboot it or if I dont do it evetually the whole system is fried, no response to any keyboard key or mouse and I have to hit the hardware turn off button. I regularly yum update the system but this makes no difference. Please don't tell not to run too many applications because I need those for my work. I thought Linux is well designed Operating System but I am very disappointed so far. Can some one here help ?

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  • Is there a way to measure wifi traffic on a network from a client?

    - by millimoose
    Is there some way (preferrably one that comes with an existing tool) to measure the traffic going through the whole WiFi network from a computer connected to it? (That is, not from the AP or something between the modem and AP.) My situation is this: a few months back, the internet connection at my parent's place got really sluggish and laggy. (Lag spikes that cause page loads to time out etc, connections plain getting lost and dropping packets forever.) It's impossible to get mom's husband to do anything about this because he brushes this off with something like "just tell your sister to turn off torrents". Unfortunately the WiFi router's firmware doesn't do traffic logging. I'm not going to risk bricking it to put WRT on it; nor am I keen on rewiring the network to add a proxy to analyse the traffic. (I'm one of those people that make computers break just by looking at them, except machines I own.) I'd like to be able to find out roughly how much data is going over the air here while all the LAN wires are out of the router, all the computers accused of torrenting are off, etc. The idea is to either show that: Even if everything but my macbook is turned off, something is congesting the network. The husband is a systems developer and has a whole lot of mysterious hardware that's not to be touched around, one of them might be culprit. There is barely any traffic on the network, but the internet is still sluggish. Meaning this is likely a problem the ISP should solve. (Some hardware of theirs being glitchy, someone on an aggregated line hogging it constantly...) The network is encrypted, but I can temporarily set it to open for the sake of finding this out. So, in conclusion? Can this be done? Or is there some alternative way I could try to diagnose the problem?

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  • Can't login to Windows server 2008 (as any user, not even locally, not in safe mode but I have right credentials)

    - by Saix
    Just from nowhere I can't login to my Windows server 2008 machine. All the services like FTP server or webserver (which I'm actually not using, just remote desktop and FTP) are running. Whatever credentials I try (even/especialy administrator), it always says Unknown Username or bad password. I have already tried hard turn off/on and safe mode without luck. Also I already tried type in login name as SERVER NAME\user or Workgroup\user (every case sensitive scenario), still says I have wrong login. Usually we are using remote desktop to access the machine but local access over KVM doesn't work either. Now I'm lock out of any control or any way to do something. There's just logon screen preceding by ctrl+alt+del to login alert. Without me able to login I can't actually try to fix anything. Can't find much more on Internet except the SERVER NAME\user thing. Reinstall would be the last resort but I can't let things this way for much longer anyway. This server is vital. If it would be any help, I think automatic Windows updates are turned off and there were no updates or newly installed software for last couple years and just few soft restarts, non of them recently. It happened during it's runtime while all other services were still up and running, so this couldn't be just some Windows nasty screw up during boot or something. What could have possibly changed? What are my options now?

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  • ASP.NET. MVC2. Entity Framework. Cannot pass primary key value back from view to [HttpPost]

    - by Paul Connolly
    I pass a ViewModel (which contains a "Person" object) from the "EditPerson" controller action into the view. When posted back from the view, the ActionResult receives all of the Person properties except the ID (which it says is zero instead of say its real integer) Can anyone tell me why? The controllers look like this: public ActionResult EditPerson(int personID) { var personToEdit = repository.GetPerson(personID); FormationViewModel vm = new FormationViewModel(); vm.Person = personToEdit; return View(vm); } [HttpPost] public ActionResult EditPerson(FormationViewModel model) <<Passes in all properties except ID { // Persistence code } The View looks like this: <%@ Page Title="" Language="C#" MasterPageFile="~/Views/Shared/Site.Master" Inherits="System.Web.Mvc.ViewPage<Afp.Models.Formation.FormationViewModel>" %> <% using (Html.BeginForm()) {% <%= Html.ValidationSummary(true) % <fieldset> <legend>Fields</legend> <div class="editor-label"> <%= Html.LabelFor(model => model.Person.Title) %> </div> <div class="editor-field"> <%= Html.TextBoxFor(model => model.Person.Title) %> <%= Html.ValidationMessageFor(model => model.Person.Title) %> </div> <div class="editor-label"> <%= Html.LabelFor(model => model.Person.Forename)%> </div> <div class="editor-field"> <%= Html.TextBoxFor(model => model.Person.Forename)%> <%= Html.ValidationMessageFor(model => model.Person.Forename)%> </div> <div class="editor-label"> <%= Html.LabelFor(model => model.Person.Surname)%> </div> <div class="editor-field"> <%= Html.TextBoxFor(model => model.Person.Surname)%> <%= Html.ValidationMessageFor(model => model.Person.Surname)%> </div> <div class="editor-label"> <%= Html.LabelFor(model => model.DOB) %> </div> <div class="editor-field"> <%= Html.TextBoxFor(model => model.DOB, String.Format("{0:g}", Model.DOB)) <%= Html.ValidationMessageFor(model => model.DOB) %> </div>--%> <div class="editor-label"> <%= Html.LabelFor(model => model.Person.Nationality)%> </div> <div class="editor-field"> <%= Html.TextBoxFor(model => model.Person.Nationality)%> <%= Html.ValidationMessageFor(model => model.Person.Nationality)%> </div> <div class="editor-label"> <%= Html.LabelFor(model => model.Person.Occupation)%> </div> <div class="editor-field"> <%= Html.TextBoxFor(model => model.Person.Occupation)%> <%= Html.ValidationMessageFor(model => model.Person.Occupation)%> </div> <div class="editor-label"> <%= Html.LabelFor(model => model.Person.CountryOfResidence)%> </div> <div class="editor-field"> <%= Html.TextBoxFor(model => model.Person.CountryOfResidence)%> <%= Html.ValidationMessageFor(model => model.Person.CountryOfResidence)%> </div> <div class="editor-label"> <%= Html.LabelFor(model => model.Person.PreviousNameForename)%> </div> <div class="editor-field"> <%= Html.TextBoxFor(model => model.Person.PreviousNameForename)%> <%= Html.ValidationMessageFor(model => model.Person.PreviousNameForename)%> </div> <div class="editor-label"> <%= Html.LabelFor(model => model.Person.PreviousSurname)%> </div> <div class="editor-field"> <%= Html.TextBoxFor(model => model.Person.PreviousSurname)%> <%= Html.ValidationMessageFor(model => model.Person.PreviousSurname)%> </div> <div class="editor-label"> <%= Html.LabelFor(model => model.Person.Email)%> </div> <div class="editor-field"> <%= Html.TextBoxFor(model => model.Person.Email)%> <%= Html.ValidationMessageFor(model => model.Person.Email)%> </div> <p> <input type="submit" value="Save" /> </p> </fieldset> <% } % And the Person class looks like: [MetadataType(typeof(Person_Validation))] public partial class Person { public Person() { } } [Bind(Exclude = "ID")] public class Person_Validation { public int ID { get; private set; } public string Title { get; set; } public string Forename { get; set; } public string Surname { get; set; } public System.DateTime DOB { get; set; } public string Nationality { get; set; } public string Occupation { get; set; } public string CountryOfResidence { get; set; } public string PreviousNameForename { get; set; } public string PreviousSurname { get; set; } public string Email { get; set; } } And ViewModel: public class FormationViewModel { public Company Company { get; set; } public Address RegisteredAddress { get; set; } public Person Person { get; set; } public PersonType PersonType { get; set; } public int CurrentStep { get; set; } } }

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  • Generating moderately interesting images

    - by Williham Totland
    Abstract: Can you propose a mathematical-ish algorithm over a plane of pixels that will generate a moderately interesting image, preferably one that on the whole resembles something? The story thus far: Once upon a time I decided in an effort to reduce cycle waste on my (admittedly too) numerous computers, and set out to generate images in a moderately interesting fashion; using a PRNG and some clever math to create images that would, on the whole, resemble something. Or at least, that was the plan. As it turns out, clever math requires being a clever mathematician; this I am not. At some length I arrived at a method that preferred straight lines (as these are generally the components of which our world is made), perhaps too strongly. The result is mildly interesting; resembling, perhaps, city grids as such: Now for the question proper: Given the source code of this little program; can you improve upon it and propose a method that gives somewhat more interesting results? (e.g. not city grids, but perhaps faces, animals, geography, what have you) This is also meant as a sort of challenge; I suppose and as such I've set down some completely arbitrary and equally optional rules: The comments in the code says it all really. Suggestions and "solutions" should edit the algorithm itself, not the surrounding framework, except as for to fix errors that prevents the sample from compiling. The code should compile cleanly with a standard issue C compiler. (If the example provided doesn't, oops! Tell me, and I'll fix. :) The method should, though again, this is optional, not need to elicit help from your friendly neighborhood math library. Solutions should probably be deliverable by simply yanking out whatever is between the snip lines (the ones that say you should not edit above and below, respectively), with a statement to the effect of what you need to add to the preamble in particular. The code requires a C compiler and libpng to build; I'm not entirely confident that the MinGW compiler provides the necessities, but I would be surprised if it didn't. For Debian you'll want the libpng-dev package, and for Mac OS X you'll want the XCode tools.. The source code can be downloaded here. Warning: Massive code splurge incoming! // compile with gcc -o imggen -lpng imggen.c // optionally with -DITERATIONS=x, where x is an appropriate integer // If you're on a Mac or using MinGW, you may have to fiddle with the linker flags to find the library and includes. #include <stdio.h> #include <stdlib.h> #include <png.h> #ifdef ITERATIONS #define REPEAT #endif // ITERATIONS // YOU MAY CHANGE THE FOLLOWING DEFINES #define WIDTH 320 #define HEIGHT 240 // YOU MAY REPLACE THE FOLLOWING DEFINES AS APPROPRIATE #define INK 16384 void writePNG (png_bytepp imageBuffer, png_uint_32 width, png_uint_32 height, int iteration) { char *fname; asprintf(&fname, "out.%d.png", iteration); FILE *fp = fopen(fname, "wb"); if (!fp) return; png_structp png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL); png_infop info_ptr = png_create_info_struct(png_ptr); png_init_io(png_ptr, fp); png_set_filter(png_ptr, PNG_FILTER_TYPE_DEFAULT, PNG_FILTER_NONE); png_set_compression_level(png_ptr, Z_BEST_COMPRESSION); png_set_IHDR(png_ptr, info_ptr, width, height, 8, PNG_COLOR_TYPE_GRAY, PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT); png_set_rows(png_ptr, info_ptr, imageBuffer); png_set_invert_mono(png_ptr); /// YOU MAY COMMENT OUT THIS LINE png_write_png(png_ptr, info_ptr, PNG_TRANSFORM_IDENTITY, NULL); png_destroy_write_struct(&png_ptr, &info_ptr); fclose(fp); free(fname); } int main (int argc, const char * argv[]) { png_uint_32 height = HEIGHT, width = WIDTH; int iteration = 1; #ifdef REPEAT for (iteration = 1; iteration <= ITERATIONS; iteration++) { #endif // REPEAT png_bytepp imageBuffer = malloc(sizeof(png_bytep) * height); for (png_uint_32 i = 0; i < height; i++) { imageBuffer[i] = malloc(sizeof(png_byte) * width); for (png_uint_32 j = 0; j < width; j++) { imageBuffer[i][j] = 0; } } /// CUT ACROSS THE DASHED LINES /// ------------------------------------------- /// NO EDITING ABOVE THIS LINE; EXCEPT AS NOTED int ink = INK; int x = rand() % width, y = rand() % height; int xdir = (rand() % 2)?1:-1; int ydir = (rand() % 2)?1:-1; while (ink) { imageBuffer[y][x] = 255; --ink; xdir += (rand() % 2)?(1):(-1); ydir += (rand() % 2)?(1):(-1); if (ydir > 0) { ++y; } else if (ydir < 0) { --y; } if (xdir > 0) { ++x; } else if (xdir < 0) { --x; } if (x == -1 || y == -1 || x == width || y == height || x == y && x == 0) { x = rand() % width; y = rand() % height; xdir = (rand() % 2)?1:-1; ydir = (rand() % 2)?1:-1; } } /// NO EDITING BELOW THIS LINE /// ------------------------------------------- writePNG(imageBuffer, width, height, iteration); for (png_uint_32 i = 0; i < height; i++) { free(imageBuffer[i]); } free(imageBuffer); #ifdef REPEAT } #endif // REPEAT return 0; } Note: While this question doesn't strictly speaking seem "answerable" as such; I still believe that it can give rise to some manner of "right" answer. Maybe. Happy hunting.

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  • Handling TclErrors in Python

    - by anteater7171
    In the following code I'll get the following error if I right click the window that pops up. Then go down to the very bottom entry widget then delete it's contents. It seems to be giving me a TclError. How do I go about handeling such an error? The Error Exception in Tkinter callback Traceback (most recent call last): File "C:\Python26\Lib\lib-tk\Tkinter.py", line 1410, in __call__ return self.func(*args) File "C:\Python26\CPUDEMO.py", line 503, in I TL.sclS.set(S1) File "C:\Python26\Lib\lib-tk\Tkinter.py", line 2765, in set self.tk.call(self._w, 'set', value) TclError: expected floating-point number but got "" The Code #F #PIthon.py # Import/Setup import Tkinter import psutil,time import re from PIL import Image, ImageTk from time import sleep class simpleapp_tk(Tkinter.Tk): def __init__(self,parent): Tkinter.Tk.__init__(self,parent) self.parent = parent self.initialize() def initialize(self): Widgets self.menu = Tkinter.Menu(self, tearoff = 0 ) M = [ "Options...", "Exit"] self.selectedM = Tkinter.StringVar() self.menu.add_radiobutton( label = 'Hide', variable = self.selectedM, command = self.E ) self.menu.add_radiobutton( label = 'Bump', variable = self.selectedM, command = self.E ) self.menu.add_separator() self.menu.add_radiobutton( label = 'Options...', variable = self.selectedM, command = self.E ) self.menu.add_separator() self.menu.add_radiobutton( label = 'Exit', variable = self.selectedM, command = self.E ) self.frame1 = Tkinter.Frame(self,bg='grey15',relief='ridge',borderwidth=4,width=185, height=39) self.frame1.grid() self.frame1.grid_propagate(0) self.frame1.bind( "<Button-3><ButtonRelease-3>", self.D ) self.frame1.bind( "<Button-2><ButtonRelease-2>", self.C ) self.frame1.bind( "<Double-Button-1>", self.C ) self.labelVariable = Tkinter.StringVar() self.label = Tkinter.Label(self.frame1,textvariable=self.labelVariable,fg="lightgreen",bg="grey15",borderwidth=1,font=('arial', 10, 'bold')) self.label.grid(column=1,row=0,columnspan=1,sticky='nsew') self.label.bind( "<Button-3><ButtonRelease-3>", self.D ) self.label.bind( "<Button-2><ButtonRelease-2>", self.C ) self.label.bind( "<Double-Button-1>", self.C ) self.F() self.overrideredirect(1) self.wm_attributes("-topmost", 1) global TL1 TL1 = Tkinter.Toplevel(self) TL1.wm_geometry("+0+5000") TL1.overrideredirect(1) TL1.button = Tkinter.Button(TL1,text="? CPU",fg="lightgreen",bg="grey15",activeforeground="lightgreen", activebackground='grey15',borderwidth=4,font=('Arial', 8, 'bold'),command=self.J) TL1.button.pack(ipadx=1) Events def Reset(self): self.label.configure(font=('arial', 10, 'bold'),fg='Lightgreen',bg='grey15',borderwidth=0) self.labela.configure(font=('arial', 8, 'bold'),fg='Lightgreen',bg='grey15',borderwidth=0) self.frame1.configure(bg='grey15',relief='ridge',borderwidth=4,width=224, height=50) self.label.pack(ipadx=38) def helpmenu(self): t2 = Tkinter.Toplevel(self) Tkinter.Label(t2, text='This is a help menu', anchor="w",justify="left",fg="darkgreen",bg="grey90",relief="ridge",borderwidth=5,font=('Arial', 10)).pack(fill='both', expand=1) t2.resizable(False,False) t2.title('Help') menu = Tkinter.Menu(self) t2.config(menu=menu) filemenu = Tkinter.Menu(menu) menu.add_cascade(label="| Exit |", menu=filemenu) filemenu.add_command(label="Exit", command=t2.destroy) def aboutmenu(self): t1 = Tkinter.Toplevel(self) Tkinter.Label(t1, text=' About:\n\n CPU Usage v1.0\n\n Publisher: Drew French\n Date: 05/09/10\n Email: [email protected] \n\n\n\n\n\n\n Written in Python 2.6.4', anchor="w",justify="left",fg="darkgreen",bg="grey90",relief="sunken",borderwidth=5,font=('Arial', 10)).pack(fill='both', expand=1) t1.resizable(False,False) t1.title('About') menu = Tkinter.Menu(self) t1.config(menu=menu) filemenu = Tkinter.Menu(menu) menu.add_cascade(label="| Exit |", menu=filemenu) filemenu.add_command(label="Exit", command=t1.destroy) def A (self,event): TL.entryVariable1.set(TL.sclY.get()) TL.entryVariable2.set(TL.sclX.get()) Y = TL.sclY.get() X = TL.sclX.get() self.wm_geometry("+" + str(X) + "+" + str(Y)) def B(self,event): Y1 = TL.entryVariable1.get() X1 = TL.entryVariable2.get() self.wm_geometry("+" + str(X1) + "+" + str(Y1)) TL.sclY.set(Y1) TL.sclX.set(X1) def C(self,event): s = self.wm_geometry() geomPatt = re.compile(r"(\d+)?x?(\d+)?([+-])(\d+)([+-])(\d+)") m = geomPatt.search(s) X3 = m.group(4) Y3 = m.group(6) M = int(Y3) - 150 P = M + 150 while Y3 > M: sleep(0.0009) Y3 = int(Y3) - 1 self.update_idletasks() self.wm_geometry("+" + str(X3) + "+" + str(Y3)) sleep(2.00) while Y3 < P: sleep(0.0009) Y3 = int(Y3) + 1 self.update_idletasks() self.wm_geometry("+" + str(X3) + "+" + str(Y3)) def D(self, event=None): self.menu.post( event.x_root, event.y_root ) def E(self): if self.selectedM.get() =='Options...': Setup global TL TL = Tkinter.Toplevel(self) menu = Tkinter.Menu(TL) TL.config(menu=menu) filemenu = Tkinter.Menu(menu) menu.add_cascade(label="| Menu |", menu=filemenu) filemenu.add_command(label="Instruction Manual...", command=self.helpmenu) filemenu.add_command(label="About...", command=self.aboutmenu) filemenu.add_separator() filemenu.add_command(label="Exit Options", command=TL.destroy) filemenu.add_command(label="Exit", command=self.destroy) helpmenu = Tkinter.Menu(menu) menu.add_cascade(label="| Help |", menu=helpmenu) helpmenu.add_command(label="Instruction Manual...", command=self.helpmenu) helpmenu.add_separator() helpmenu.add_command(label="Quick Help...", command=self.helpmenu) Title TL.label5 = Tkinter.Label(TL,text="CPU Usage: Options",anchor="center",fg="black",bg="lightgreen",relief="ridge",borderwidth=5,font=('Arial', 18, 'bold')) TL.label5.pack(padx=15,ipadx=5) X Y scale TL.separator = Tkinter.Frame(TL,height=7, bd=1, relief='ridge', bg='grey95') TL.separator.pack(pady=5,padx=5) # TL.sclX = Tkinter.Scale(TL.separator, from_=0, to=1500, orient='horizontal', resolution=1, command=self.A) TL.sclX.grid(column=1,row=0,ipadx=27, sticky='w') TL.label1 = Tkinter.Label(TL.separator,text="X",anchor="s",fg="black",bg="grey95",font=('Arial', 8 ,'bold')) TL.label1.grid(column=0,row=0, pady=1, sticky='S') TL.sclY = Tkinter.Scale(TL.separator, from_=0, to=1500, resolution=1, command=self.A) TL.sclY.grid(column=2,row=1,rowspan=2,sticky='e', padx=4) TL.label3 = Tkinter.Label(TL.separator,text="Y",fg="black",bg="grey95",font=('Arial', 8 ,'bold')) TL.label3.grid(column=2,row=0, padx=10, sticky='e') TL.entryVariable2 = Tkinter.StringVar() TL.entry2 = Tkinter.Entry(TL.separator,textvariable=TL.entryVariable2, fg="grey15",bg="grey90",relief="sunken",insertbackground="black",borderwidth=5,font=('Arial', 10)) TL.entry2.grid(column=1,row=1,ipadx=20, pady=10,sticky='EW') TL.entry2.bind("<Return>", self.B) TL.label2 = Tkinter.Label(TL.separator,text="X:",fg="black",bg="grey95",font=('Arial', 8 ,'bold')) TL.label2.grid(column=0,row=1, ipadx=4, sticky='W') TL.entryVariable1 = Tkinter.StringVar() TL.entry1 = Tkinter.Entry(TL.separator,textvariable=TL.entryVariable1, fg="grey15",bg="grey90",relief="sunken",insertbackground="black",borderwidth=5,font=('Arial', 10)) TL.entry1.grid(column=1,row=2,sticky='EW') TL.entry1.bind("<Return>", self.B) TL.label4 = Tkinter.Label(TL.separator,text="Y:", anchor="center",fg="black",bg="grey95",font=('Arial', 8 ,'bold')) TL.label4.grid(column=0,row=2, ipadx=4, sticky='W') TL.label7 = Tkinter.Label(TL.separator,text="Text Colour:",fg="black",bg="grey95",font=('Arial', 8 ,'bold')) TL.label7.grid(column=1,row=3,stick="W",ipady=10) TL.selectedP = Tkinter.StringVar() TL.opt1 = Tkinter.OptionMenu(TL.separator, TL.selectedP,'Normal', 'White','Black', 'Blue', 'Steel Blue','Green','Light Green','Yellow','Orange' ,'Red',command=self.G) TL.opt1.config(fg="black",bg="grey90",activebackground="grey90",activeforeground="black", anchor="center",relief="raised",direction='right',font=('Arial', 10)) TL.opt1.grid(column=1,row=4,sticky='EW',padx=20,ipadx=20) TL.selectedP.set('Normal') TL.label7 = Tkinter.Label(TL.separator,text="Refresh Rate:",fg="black",bg="grey95",font=('Arial', 8 ,'bold')) TL.label7.grid(column=1,row=5,stick="W",ipady=10) TL.sclS = Tkinter.Scale(TL.separator, from_=10, to=2000, orient='horizontal', resolution=10, command=self.H) TL.sclS.grid(column=1,row=6,ipadx=27, sticky='w') TL.sclS.set(650) TL.entryVariableS = Tkinter.StringVar() TL.entryS = Tkinter.Entry(TL.separator,textvariable=TL.entryVariableS, fg="grey15",bg="grey90",relief="sunken",insertbackground="black",borderwidth=5,font=('Arial', 10)) TL.entryS.grid(column=1,row=7,ipadx=20, pady=10,sticky='EW') TL.entryS.bind("<Return>", self.I) TL.entryVariableS.set(650) # TL.resizable(False,False) TL.title('Options') geomPatt = re.compile(r"(\d+)?x?(\d+)?([+-])(\d+)([+-])(\d+)") s = self.wm_geometry() m = geomPatt.search(s) X = m.group(4) Y = m.group(6) TL.sclY.set(Y) TL.sclX.set(X) if self.selectedM.get() == 'Exit': self.destroy() if self.selectedM.get() == 'Bump': s = self.wm_geometry() geomPatt = re.compile(r"(\d+)?x?(\d+)?([+-])(\d+)([+-])(\d+)") m = geomPatt.search(s) X3 = m.group(4) Y3 = m.group(6) M = int(Y3) - 150 P = M + 150 while Y3 > M: sleep(0.0009) Y3 = int(Y3) - 1 self.update_idletasks() self.wm_geometry("+" + str(X3) + "+" + str(Y3)) sleep(2.00) while Y3 < P: sleep(0.0009) Y3 = int(Y3) + 1 self.update_idletasks() self.wm_geometry("+" + str(X3) + "+" + str(Y3)) if self.selectedM.get() == 'Hide': s = self.wm_geometry() geomPatt = re.compile(r"(\d+)?x?(\d+)?([+-])(\d+)([+-])(\d+)") m = geomPatt.search(s) X3 = m.group(4) Y3 = m.group(6) M = int(Y3) + 5000 self.update_idletasks() self.wm_geometry("+" + str(X3) + "+" + str(M)) TL1.wm_geometry("+0+190") def F (self): G = round(psutil.cpu_percent(), 1) G1 = str(G) + '%' self.labelVariable.set(G1) try: S2 = TL.entryVariableS.get() except ValueError, e: S2 = 650 except NameError: S2 = 650 self.after(int(S2), self.F) def G (self,event): if TL.selectedP.get() =='Normal': self.label.config( fg = 'lightgreen' ) TL1.button.config( fg = 'lightgreen',activeforeground='lightgreen') if TL.selectedP.get() =='Red': self.label.config( fg = 'red' ) TL1.button.config( fg = 'red',activeforeground='red') if TL.selectedP.get() =='Orange': self.label.config( fg = 'orange') TL1.button.config( fg = 'orange',activeforeground='orange') if TL.selectedP.get() =='Yellow': self.label.config( fg = 'yellow') TL1.button.config( fg = 'yellow',activeforeground='yellow') if TL.selectedP.get() =='Light Green': self.label.config( fg = 'lightgreen' ) TL1.button.config( fg = 'lightgreen',activeforeground='lightgreen') if TL.selectedP.get() =='Normal': self.label.config( fg = 'lightgreen' ) TL1.button.config( fg = 'lightgreen',activeforeground='lightgreen') if TL.selectedP.get() =='Steel Blue': self.label.config( fg = 'steelblue1' ) TL1.button.config( fg = 'steelblue1',activeforeground='steelblue1') if TL.selectedP.get() =='Blue': self.label.config( fg = 'blue') TL1.button.config( fg = 'blue',activeforeground='blue') if TL.selectedP.get() =='Green': self.label.config( fg = 'darkgreen' ) TL1.button.config( fg = 'darkgreen',activeforeground='darkgreen') if TL.selectedP.get() =='White': self.label.config( fg = 'white' ) TL1.button.config( fg = 'white',activeforeground='white') if TL.selectedP.get() =='Black': self.label.config( fg = 'black') TL1.button.config( fg = 'black',activeforeground='black') def H (self,event): TL.entryVariableS.set(TL.sclS.get()) S = TL.sclS.get() def I (self,event): S1 = TL.entryVariableS.get() TL.sclS.set(S1) TL.sclS.set(TL.sclS.get()) S1 = TL.entryVariableS.get() TL.sclS.set(S1) def J (self): s = self.wm_geometry() geomPatt = re.compile(r"(\d+)?x?(\d+)?([+-])(\d+)([+-])(\d+)") m = geomPatt.search(s) X3 = m.group(4) Y3 = m.group(6) M = int(Y3) - 5000 self.update_idletasks() self.wm_geometry("+" + str(X3) + "+" + str(M)) TL1.wm_geometry("+0+5000") Loop if name == "main": app = simpleapp_tk(None) app.mainloop()

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  • Would anyone tell me how to fetch the media:thumb element's attribute from a json feed?

    - by ash
    I made a yahoo pipe that pulls up the atoms as json format; however, I can fetch and display all the elements in my html page except for the element's attribute. Would anyone tell me how to fetch the media:thumb element's attribute from a json feed? I am pasting the html page's code with javascript. If you save the html page and then view it in browser, you will see that all the necessary elements get output at html page except for the media:thumb as I cannot display the attribute of media:thumb when the feed is formatted as json. I am also pasting the some portion of the json feed so that you can have an idea what i am talking about. Please tell me how to retrieve attribute from media:thumb element of a json feed by using plain javascript but no server side code or javascript library. Thank you. function getFeed(feed){ var newScript = document.createElement('script'); newScript.type = 'text/javascript'; newScript.src = 'http://pipes.yahoo.com/pipes/pipe.run?_id=40616620df99780bceb3fe923cecd216&_render=json&_callback=piper'; document.getElementsByTagName("head")[0].appendChild(newScript); } function piper(feed){ var tmp=''; for (var i=0; i'; tmp+=feed.value.items[i].title+''; tmp+=feed.value.items[i].author.name+''; tmp+=feed.value.items[i].published+''; if (feed.value.items[i].description) { tmp+=feed.value.items[i].description+''; } tmp+='<hr>'; } document.getElementById('rssLayer').innerHTML=tmp; } </script> bchnbc .............................................................. Some portion of the json feed that gets generated by yahoo pipe .............................................................. piper({"count":2,"value":{"title":"myPipe","description":"Pipes Output","link":"http:\/\/pipes.yahoo.com\/pipes\/pipe.info?_id=f7f4175d493cf1171aecbd3268fea5ee","pubDate":"Fri, 02 Apr 2010 17:59:22 -0700","generator":"http:\/\/pipes.yahoo.com\/pipes\/","callback":"piper", "items": [{ "rights":"Attribution - Noncommercial - No Derivative Works", "link":"http:\/\/vodo.net\/mixtape1", "y:id":{"value":null,"permalink":"true"}, "content":{"content":"We're proud to be releasing this first VODO MIXTAPE. Actual tape might be a thing of the past, but before P2P, mixtapes were the most popular way of sharing popular culture the world had known -- and once called the 'most widely practiced American art form'. We want to resuscitate the spirit of the mixtape for this VODO MIXTAPE series: compilations of our favourite shorts, the weird, the wild and the wonky, all brought together in a temporary and uncomfortable company.","type":"text"}, "author": {"name":"Various"}, "description":"We're proud to be releasing this first VODO MIXTAPE. Actual tape might be a thing of the past, but before P2P, mixtapes were the most popular way of sharing popular culture the world had known -- and once called the 'most widely practiced American art form'. We want to resuscitate the spirit of the mixtape for this VODO MIXTAPE series: compilations of our favourite shorts, the weird, the wild and the wonky, all brought together in a temporary and uncomfortable company.", "media:thumbnail": { "url":"http:\/\/vodo.net\/\/thumbnails\/Mixtape1.jpg" }, "published":"2010-03-08-09:20:20 PM", "format": { "audio_bitrate":null, "width":"608", "xmlns":"http:\/\/xmlns.transmission.cc\/FileFormat", "channels":"2", "samplerate":"44100.0", "duration":"3092.36", "height":"352", "size":"733925376.0", "framerate":"25.0", "audio_codec":"mp3", "video_bitrate":"1898.0", "video_codec":"XVID", "pixel_aspect_ratio":"16:9" }, "y:title":"Mixtape #1: VODO's favourite short films", "title":"Mixtape #1: VODO's favourite short films", "id":null, "pubDate":"2010-03-08-09:20:20 PM", "y:published":{"hour":"3","timezone":"UTC","second":"0","month":"4","minute":"10","utime":"1270264200","day":"3","day_of_week":"6","year":"2010" }}, {"rights":"Attribution - Noncommercial - No Derivative Works","link":"http:\/\/vodo.net\/gilbert","y:id":{"value":"cd6584e06ea4ce7fcd34172f4bbd919e295f8680","permalink":"true"},"content":{"content":"A documentary short about Gilbert, the Beacon Hill \"town crier.\" For the last 9 years, since losing his job and becoming homeless, Gilbert has delivered the weather, sports, and breaking headlines from his spot on the Boston Common. Music (used with permission) in this piece is called \"Blue Bicycle\" by Dusseldorf-based pianist \/ composer Volker Bertelmann also known as Hauschka. Artistic Statement: This is the first in a series of profiles of people who I think are interesting, and who I see on almost a daily basis. I don't want to limit the series to people who live \"on the fringe,\" but it would be appropriate to say that most of the people I interview are eclectic, eccentric, and just a little bit unique. The art is in the viewing - but I hope to turn my lens on individuals that don't always color in the lines, whether they can help it or not.","type":"text"},"author":{"name":"Nathaniel Hansen"},"description":"A documentary short about Gilbert, the Beacon Hill \"town crier.\" For the last 9 years, since losing his job and becoming homeless, Gilbert has delivered the weather, sports, and breaking headlines from his spot on the Boston Common. Music (used with permission) in this piece is called \"Blue Bicycle\" by Dusseldorf-based pianist \/ composer Volker Bertelmann also known as Hauschka. Artistic Statement: This is the first in a series of profiles of people who I think are interesting, and who I see on almost a daily basis. I don't want to limit the series to people who live \"on the fringe,\" but it would be appropriate to say that most of the people I interview are eclectic, eccentric, and just a little bit unique. The art is in the viewing - but I hope to turn my lens on individuals that don't always color in the lines, whether they can help it or not.","media:thumbnail":{"url":"http:\/\/vodo.net\/\/thumbnails\/gilbert.jpeg"},"published":"2010-03-03-10:37:05 AM","format":{"audio_bitrate":null,"width":"624","xmlns":"http:\/\/xmlns.transmission.cc\/FileFormat","channels":"2","samplerate":null,"duration":"373.673","height":"352","size":"123321266.0","framerate":null,"audio_codec":"mp3","video_bitrate":null,"video_codec":"XVID","pixel_aspect_ratio":"16:9"},"y:title":"Gilbert","title":"Gilbert","id":"cd6584e06ea4ce7fcd34172f4bbd919e295f8680","pubDate":"2010-03-03-10:37:05 AM","y:published":{"hour":"3","timezone":"UTC","second":"0","month":"4","minute":"10","utime":"1270264200","day":"3","day_of_week":"6","year":"2010" }} ] }})

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  • Using the West Wind Web Toolkit to set up AJAX and REST Services

    - by Rick Strahl
    I frequently get questions about which option to use for creating AJAX and REST backends for ASP.NET applications. There are many solutions out there to do this actually, but when I have a choice - not surprisingly - I fall back to my own tools in the West Wind West Wind Web Toolkit. I've talked a bunch about the 'in-the-box' solutions in the past so for a change in this post I'll talk about the tools that I use in my own and customer applications to handle AJAX and REST based access to service resources using the West Wind West Wind Web Toolkit. Let me preface this by saying that I like things to be easy. Yes flexible is very important as well but not at the expense of over-complexity. The goal I've had with my tools is make it drop dead easy, with good performance while providing the core features that I'm after, which are: Easy AJAX/JSON Callbacks Ability to return any kind of non JSON content (string, stream, byte[], images) Ability to work with both XML and JSON interchangeably for input/output Access endpoints via POST data, RPC JSON calls, GET QueryString values or Routing interface Easy to use generic JavaScript client to make RPC calls (same syntax, just what you need) Ability to create clean URLS with Routing Ability to use standard ASP.NET HTTP Stack for HTTP semantics It's all about options! In this post I'll demonstrate most of these features (except XML) in a few simple and short samples which you can download. So let's take a look and see how you can build an AJAX callback solution with the West Wind Web Toolkit. Installing the Toolkit Assemblies The easiest and leanest way of using the Toolkit in your Web project is to grab it via NuGet: West Wind Web and AJAX Utilities (Westwind.Web) and drop it into the project by right clicking in your Project and choosing Manage NuGet Packages from anywhere in the Project.   When done you end up with your project looking like this: What just happened? Nuget added two assemblies - Westwind.Web and Westwind.Utilities and the client ww.jquery.js library. It also added a couple of references into web.config: The default namespaces so they can be accessed in pages/views and a ScriptCompressionModule that the toolkit optionally uses to compress script resources served from within the assembly (namely ww.jquery.js and optionally jquery.js). Creating a new Service The West Wind Web Toolkit supports several ways of creating and accessing AJAX services, but for this post I'll stick to the lower level approach that works from any plain HTML page or of course MVC, WebForms, WebPages. There's also a WebForms specific control that makes this even easier but I'll leave that for another post. So, to create a new standalone AJAX/REST service we can create a new HttpHandler in the new project either as a pure class based handler or as a generic .ASHX handler. Both work equally well, but generic handlers don't require any web.config configuration so I'll use that here. In the root of the project add a Generic Handler. I'm going to call this one StockService.ashx. Once the handler has been created, edit the code and remove all of the handler body code. Then change the base class to CallbackHandler and add methods that have a [CallbackMethod] attribute. Here's the modified base handler implementation now looks like with an added HelloWorld method: using System; using Westwind.Web; namespace WestWindWebAjax { /// <summary> /// Handler implements CallbackHandler to provide REST/AJAX services /// </summary> public class SampleService : CallbackHandler { [CallbackMethod] public string HelloWorld(string name) { return "Hello " + name + ". Time is: " + DateTime.Now.ToString(); } } } Notice that the class inherits from CallbackHandler and that the HelloWorld service method is marked up with [CallbackMethod]. We're done here. Services Urlbased Syntax Once you compile, the 'service' is live can respond to requests. All CallbackHandlers support input in GET and POST formats, and can return results as JSON or XML. To check our fancy HelloWorld method we can now access the service like this: http://localhost/WestWindWebAjax/StockService.ashx?Method=HelloWorld&name=Rick which produces a default JSON response - in this case a string (wrapped in quotes as it's JSON): (note by default JSON will be downloaded by most browsers not displayed - various options are available to view JSON right in the browser) If I want to return the same data as XML I can tack on a &format=xml at the end of the querystring which produces: <string>Hello Rick. Time is: 11/1/2011 12:11:13 PM</string> Cleaner URLs with Routing Syntax If you want cleaner URLs for each operation you can also configure custom routes on a per URL basis similar to the way that WCF REST does. To do this you need to add a new RouteHandler to your application's startup code in global.asax.cs one for each CallbackHandler based service you create: protected void Application_Start(object sender, EventArgs e) { CallbackHandlerRouteHandler.RegisterRoutes<StockService>(RouteTable.Routes); } With this code in place you can now add RouteUrl properties to any of your service methods. For the HelloWorld method that doesn't make a ton of sense but here is what a routed clean URL might look like in definition: [CallbackMethod(RouteUrl="stocks/HelloWorld/{name}")] public string HelloWorld(string name) { return "Hello " + name + ". Time is: " + DateTime.Now.ToString(); } The same URL I previously used now becomes a bit shorter and more readable with: http://localhost/WestWindWebAjax/HelloWorld/Rick It's an easy way to create cleaner URLs and still get the same functionality. Calling the Service with $.getJSON() Since the result produced is JSON you can now easily consume this data using jQuery's getJSON method. First we need a couple of scripts - jquery.js and ww.jquery.js in the page: <!DOCTYPE html> <html> <head> <link href="Css/Westwind.css" rel="stylesheet" type="text/css" /> <script src="scripts/jquery.min.js" type="text/javascript"></script> <script src="scripts/ww.jquery.min.js" type="text/javascript"></script> </head> <body> Next let's add a small HelloWorld example form (what else) that has a single textbox to type a name, a button and a div tag to receive the result: <fieldset> <legend>Hello World</legend> Please enter a name: <input type="text" name="txtHello" id="txtHello" value="" /> <input type="button" id="btnSayHello" value="Say Hello (POST)" /> <input type="button" id="btnSayHelloGet" value="Say Hello (GET)" /> <div id="divHelloMessage" class="errordisplay" style="display:none;width: 450px;" > </div> </fieldset> Then to call the HelloWorld method a little jQuery is used to hook the document startup and the button click followed by the $.getJSON call to retrieve the data from the server. <script type="text/javascript"> $(document).ready(function () { $("#btnSayHelloGet").click(function () { $.getJSON("SampleService.ashx", { Method: "HelloWorld", name: $("#txtHello").val() }, function (result) { $("#divHelloMessage") .text(result) .fadeIn(1000); }); });</script> .getJSON() expects a full URL to the endpoint of our service, which is the ASHX file. We can either provide a full URL (SampleService.ashx?Method=HelloWorld&name=Rick) or we can just provide the base URL and an object that encodes the query string parameters for us using an object map that has a property that matches each parameter for the server method. We can also use the clean URL routing syntax, but using the object parameter encoding actually is safer as the parameters will get properly encoded by jQuery. The result returned is whatever the result on the server method is - in this case a string. The string is applied to the divHelloMessage element and we're done. Obviously this is a trivial example, but it demonstrates the basics of getting a JSON response back to the browser. AJAX Post Syntax - using ajaxCallMethod() The previous example allows you basic control over the data that you send to the server via querystring parameters. This works OK for simple values like short strings, numbers and boolean values, but doesn't really work if you need to pass something more complex like an object or an array back up to the server. To handle traditional RPC type messaging where the idea is to map server side functions and results to a client side invokation, POST operations can be used. The easiest way to use this functionality is to use ww.jquery.js and the ajaxCallMethod() function. ww.jquery wraps jQuery's AJAX functions and knows implicitly how to call a CallbackServer method with parameters and parse the result. Let's look at another simple example that posts a simple value but returns something more interesting. Let's start with the service method: [CallbackMethod(RouteUrl="stocks/{symbol}")] public StockQuote GetStockQuote(string symbol) { Response.Cache.SetExpires(DateTime.UtcNow.Add(new TimeSpan(0, 2, 0))); StockServer server = new StockServer(); var quote = server.GetStockQuote(symbol); if (quote == null) throw new ApplicationException("Invalid Symbol passed."); return quote; } This sample utilizes a small StockServer helper class (included in the sample) that downloads a stock quote from Yahoo's financial site via plain HTTP GET requests and formats it into a StockQuote object. Lets create a small HTML block that lets us query for the quote and display it: <fieldset> <legend>Single Stock Quote</legend> Please enter a stock symbol: <input type="text" name="txtSymbol" id="txtSymbol" value="msft" /> <input type="button" id="btnStockQuote" value="Get Quote" /> <div id="divStockDisplay" class="errordisplay" style="display:none; width: 450px;"> <div class="label-left">Company:</div> <div id="stockCompany"></div> <div class="label-left">Last Price:</div> <div id="stockLastPrice"></div> <div class="label-left">Quote Time:</div> <div id="stockQuoteTime"></div> </div> </fieldset> The final result looks something like this:   Let's hook up the button handler to fire the request and fill in the data as shown: $("#btnStockQuote").click(function () { ajaxCallMethod("SampleService.ashx", "GetStockQuote", [$("#txtSymbol").val()], function (quote) { $("#divStockDisplay").show().fadeIn(1000); $("#stockCompany").text(quote.Company + " (" + quote.Symbol + ")"); $("#stockLastPrice").text(quote.LastPrice); $("#stockQuoteTime").text(quote.LastQuoteTime.formatDate("MMM dd, HH:mm EST")); }, onPageError); }); So we point at SampleService.ashx and the GetStockQuote method, passing a single parameter of the input symbol value. Then there are two handlers for success and failure callbacks.  The success handler is the interesting part - it receives the stock quote as a result and assigns its values to various 'holes' in the stock display elements. The data that comes back over the wire is JSON and it looks like this: { "Symbol":"MSFT", "Company":"Microsoft Corpora", "OpenPrice":26.11, "LastPrice":26.01, "NetChange":0.02, "LastQuoteTime":"2011-11-03T02:00:00Z", "LastQuoteTimeString":"Nov. 11, 2011 4:20pm" } which is an object representation of the data. JavaScript can evaluate this JSON string back into an object easily and that's the reslut that gets passed to the success function. The quote data is then applied to existing page content by manually selecting items and applying them. There are other ways to do this more elegantly like using templates, but here we're only interested in seeing how the data is returned. The data in the object is typed - LastPrice is a number and QuoteTime is a date. Note about the date value: JavaScript doesn't have a date literal although the JSON embedded ISO string format used above  ("2011-11-03T02:00:00Z") is becoming fairly standard for JSON serializers. However, JSON parsers don't deserialize dates by default and return them by string. This is why the StockQuote actually returns a string value of LastQuoteTimeString for the same date. ajaxMethodCallback always converts dates properly into 'real' dates and the example above uses the real date value along with a .formatDate() data extension (also in ww.jquery.js) to display the raw date properly. Errors and Exceptions So what happens if your code fails? For example if I pass an invalid stock symbol to the GetStockQuote() method you notice that the code does this: if (quote == null) throw new ApplicationException("Invalid Symbol passed."); CallbackHandler automatically pushes the exception message back to the client so it's easy to pick up the error message. Regardless of what kind of error occurs: Server side, client side, protocol errors - any error will fire the failure handler with an error object parameter. The error is returned to the client via a JSON response in the error callback. In the previous examples I called onPageError which is a generic routine in ww.jquery that displays a status message on the bottom of the screen. But of course you can also take over the error handling yourself: $("#btnStockQuote").click(function () { ajaxCallMethod("SampleService.ashx", "GetStockQuote", [$("#txtSymbol").val()], function (quote) { $("#divStockDisplay").fadeIn(1000); $("#stockCompany").text(quote.Company + " (" + quote.Symbol + ")"); $("#stockLastPrice").text(quote.LastPrice); $("#stockQuoteTime").text(quote.LastQuoteTime.formatDate("MMM dd, hh:mmt")); }, function (error, xhr) { $("#divErrorDisplay").text(error.message).fadeIn(1000); }); }); The error object has a isCallbackError, message and  stackTrace properties, the latter of which is only populated when running in Debug mode, and this object is returned for all errors: Client side, transport and server side errors. Regardless of which type of error you get the same object passed (as well as the XHR instance optionally) which makes for a consistent error retrieval mechanism. Specifying HttpVerbs You can also specify HTTP Verbs that are allowed using the AllowedHttpVerbs option on the CallbackMethod attribute: [CallbackMethod(AllowedHttpVerbs=HttpVerbs.GET | HttpVerbs.POST)] public string HelloWorld(string name) { … } If you're building REST style API's this might be useful to force certain request semantics onto the client calling. For the above if call with a non-allowed HttpVerb the request returns a 405 error response along with a JSON (or XML) error object result. The default behavior is to allow all verbs access (HttpVerbs.All). Passing in object Parameters Up to now the parameters I passed were very simple. But what if you need to send something more complex like an object or an array? Let's look at another example now that passes an object from the client to the server. Keeping with the Stock theme here lets add a method called BuyOrder that lets us buy some shares for a stock. Consider the following service method that receives an StockBuyOrder object as a parameter: [CallbackMethod] public string BuyStock(StockBuyOrder buyOrder) { var server = new StockServer(); var quote = server.GetStockQuote(buyOrder.Symbol); if (quote == null) throw new ApplicationException("Invalid or missing stock symbol."); return string.Format("You're buying {0} shares of {1} ({2}) stock at {3} for a total of {4} on {5}.", buyOrder.Quantity, quote.Company, quote.Symbol, quote.LastPrice.ToString("c"), (quote.LastPrice * buyOrder.Quantity).ToString("c"), buyOrder.BuyOn.ToString("MMM d")); } public class StockBuyOrder { public string Symbol { get; set; } public int Quantity { get; set; } public DateTime BuyOn { get; set; } public StockBuyOrder() { BuyOn = DateTime.Now; } } This is a contrived do-nothing example that simply echoes back what was passed in, but it demonstrates how you can pass complex data to a callback method. On the client side we now have a very simple form that captures the three values on a form: <fieldset> <legend>Post a Stock Buy Order</legend> Enter a symbol: <input type="text" name="txtBuySymbol" id="txtBuySymbol" value="GLD" />&nbsp;&nbsp; Qty: <input type="text" name="txtBuyQty" id="txtBuyQty" value="10" style="width: 50px" />&nbsp;&nbsp; Buy on: <input type="text" name="txtBuyOn" id="txtBuyOn" value="<%= DateTime.Now.ToString("d") %>" style="width: 70px;" /> <input type="button" id="btnBuyStock" value="Buy Stock" /> <div id="divStockBuyMessage" class="errordisplay" style="display:none"></div> </fieldset> The completed form and demo then looks something like this:   The client side code that picks up the input values and assigns them to object properties and sends the AJAX request looks like this: $("#btnBuyStock").click(function () { // create an object map that matches StockBuyOrder signature var buyOrder = { Symbol: $("#txtBuySymbol").val(), Quantity: $("#txtBuyQty").val() * 1, // number Entered: new Date() } ajaxCallMethod("SampleService.ashx", "BuyStock", [buyOrder], function (result) { $("#divStockBuyMessage").text(result).fadeIn(1000); }, onPageError); }); The code creates an object and attaches the properties that match the server side object passed to the BuyStock method. Each property that you want to update needs to be included and the type must match (ie. string, number, date in this case). Any missing properties will not be set but also not cause any errors. Pass POST data instead of Objects In the last example I collected a bunch of values from form variables and stuffed them into object variables in JavaScript code. While that works, often times this isn't really helping - I end up converting my types on the client and then doing another conversion on the server. If lots of input controls are on a page and you just want to pick up the values on the server via plain POST variables - that can be done too - and it makes sense especially if you're creating and filling the client side object only to push data to the server. Let's add another method to the server that once again lets us buy a stock. But this time let's not accept a parameter but rather send POST data to the server. Here's the server method receiving POST data: [CallbackMethod] public string BuyStockPost() { StockBuyOrder buyOrder = new StockBuyOrder(); buyOrder.Symbol = Request.Form["txtBuySymbol"]; ; int qty; int.TryParse(Request.Form["txtBuyQuantity"], out qty); buyOrder.Quantity = qty; DateTime time; DateTime.TryParse(Request.Form["txtBuyBuyOn"], out time); buyOrder.BuyOn = time; // Or easier way yet //FormVariableBinder.Unbind(buyOrder,null,"txtBuy"); var server = new StockServer(); var quote = server.GetStockQuote(buyOrder.Symbol); if (quote == null) throw new ApplicationException("Invalid or missing stock symbol."); return string.Format("You're buying {0} shares of {1} ({2}) stock at {3} for a total of {4} on {5}.", buyOrder.Quantity, quote.Company, quote.Symbol, quote.LastPrice.ToString("c"), (quote.LastPrice * buyOrder.Quantity).ToString("c"), buyOrder.BuyOn.ToString("MMM d")); } Clearly we've made this server method take more code than it did with the object parameter. We've basically moved the parameter assignment logic from the client to the server. As a result the client code to call this method is now a bit shorter since there's no client side shuffling of values from the controls to an object. $("#btnBuyStockPost").click(function () { ajaxCallMethod("SampleService.ashx", "BuyStockPost", [], // Note: No parameters - function (result) { $("#divStockBuyMessage").text(result).fadeIn(1000); }, onPageError, // Force all page Form Variables to be posted { postbackMode: "Post" }); }); The client simply calls the BuyStockQuote method and pushes all the form variables from the page up to the server which parses them instead. The feature that makes this work is one of the options you can pass to the ajaxCallMethod() function: { postbackMode: "Post" }); which directs the function to include form variable POST data when making the service call. Other options include PostNoViewState (for WebForms to strip out WebForms crap vars), PostParametersOnly (default), None. If you pass parameters those are always posted to the server except when None is set. The above code can be simplified a bit by using the FormVariableBinder helper, which can unbind form variables directly into an object: FormVariableBinder.Unbind(buyOrder,null,"txtBuy"); which replaces the manual Request.Form[] reading code. It receives the object to unbind into, a string of properties to skip, and an optional prefix which is stripped off form variables to match property names. The component is similar to the MVC model binder but it's independent of MVC. Returning non-JSON Data CallbackHandler also supports returning non-JSON/XML data via special return types. You can return raw non-JSON encoded strings like this: [CallbackMethod(ReturnAsRawString=true,ContentType="text/plain")] public string HelloWorldNoJSON(string name) { return "Hello " + name + ". Time is: " + DateTime.Now.ToString(); } Calling this method results in just a plain string - no JSON encoding with quotes around the result. This can be useful if your server handling code needs to return a string or HTML result that doesn't fit well for a page or other UI component. Any string output can be returned. You can also return binary data. Stream, byte[] and Bitmap/Image results are automatically streamed back to the client. Notice that you should set the ContentType of the request either on the CallbackMethod attribute or using Response.ContentType. This ensures the Web Server knows how to display your binary response. Using a stream response makes it possible to return any of data. Streamed data can be pretty handy to return bitmap data from a method. The following is a method that returns a stock history graph for a particular stock over a provided number of years: [CallbackMethod(ContentType="image/png",RouteUrl="stocks/history/graph/{symbol}/{years}")] public Stream GetStockHistoryGraph(string symbol, int years = 2,int width = 500, int height=350) { if (width == 0) width = 500; if (height == 0) height = 350; StockServer server = new StockServer(); return server.GetStockHistoryGraph(symbol,"Stock History for " + symbol,width,height,years); } I can now hook this up into the JavaScript code when I get a stock quote. At the end of the process I can assign the URL to the service that returns the image into the src property and so force the image to display. Here's the changed code: $("#btnStockQuote").click(function () { var symbol = $("#txtSymbol").val(); ajaxCallMethod("SampleService.ashx", "GetStockQuote", [symbol], function (quote) { $("#divStockDisplay").fadeIn(1000); $("#stockCompany").text(quote.Company + " (" + quote.Symbol + ")"); $("#stockLastPrice").text(quote.LastPrice); $("#stockQuoteTime").text(quote.LastQuoteTime.formatDate("MMM dd, hh:mmt")); // display a stock chart $("#imgStockHistory").attr("src", "stocks/history/graph/" + symbol + "/2"); },onPageError); }); The resulting output then looks like this: The charting code uses the new ASP.NET 4.0 Chart components via code to display a bar chart of the 2 year stock data as part of the StockServer class which you can find in the sample download. The ability to return arbitrary data from a service is useful as you can see - in this case the chart is clearly associated with the service and it's nice that the graph generation can happen off a handler rather than through a page. Images are common resources, but output can also be PDF reports, zip files for downloads etc. which is becoming increasingly more common to be returned from REST endpoints and other applications. Why reinvent? Obviously the examples I've shown here are pretty basic in terms of functionality. But I hope they demonstrate the core features of AJAX callbacks that you need to work through in most applications which is simple: return data, send back data and potentially retrieve data in various formats. While there are other solutions when it comes down to making AJAX callbacks and servicing REST like requests, I like the flexibility my home grown solution provides. Simply put it's still the easiest solution that I've found that addresses my common use cases: AJAX JSON RPC style callbacks Url based access XML and JSON Output from single method endpoint XML and JSON POST support, querystring input, routing parameter mapping UrlEncoded POST data support on callbacks Ability to return stream/raw string data Essentially ability to return ANYTHING from Service and pass anything All these features are available in various solutions but not together in one place. I've been using this code base for over 4 years now in a number of projects both for myself and commercial work and it's served me extremely well. Besides the AJAX functionality CallbackHandler provides, it's also an easy way to create any kind of output endpoint I need to create. Need to create a few simple routines that spit back some data, but don't want to create a Page or View or full blown handler for it? Create a CallbackHandler and add a method or multiple methods and you have your generic endpoints.  It's a quick and easy way to add small code pieces that are pretty efficient as they're running through a pretty small handler implementation. I can have this up and running in a couple of minutes literally without any setup and returning just about any kind of data. Resources Download the Sample NuGet: Westwind Web and AJAX Utilities (Westwind.Web) ajaxCallMethod() Documentation Using the AjaxMethodCallback WebForms Control West Wind Web Toolkit Home Page West Wind Web Toolkit Source Code © Rick Strahl, West Wind Technologies, 2005-2011Posted in ASP.NET  jQuery  AJAX   Tweet (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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  • New features of C# 4.0

    This article covers New features of C# 4.0. Article has been divided into below sections. Introduction. Dynamic Lookup. Named and Optional Arguments. Features for COM interop. Variance. Relationship with Visual Basic. Resources. Other interested readings… 22 New Features of Visual Studio 2008 for .NET Professionals 50 New Features of SQL Server 2008 IIS 7.0 New features Introduction It is now close to a year since Microsoft Visual C# 3.0 shipped as part of Visual Studio 2008. In the VS Managed Languages team we are hard at work on creating the next version of the language (with the unsurprising working title of C# 4.0), and this document is a first public description of the planned language features as we currently see them. Please be advised that all this is in early stages of production and is subject to change. Part of the reason for sharing our plans in public so early is precisely to get the kind of feedback that will cause us to improve the final product before it rolls out. Simultaneously with the publication of this whitepaper, a first public CTP (community technology preview) of Visual Studio 2010 is going out as a Virtual PC image for everyone to try. Please use it to play and experiment with the features, and let us know of any thoughts you have. We ask for your understanding and patience working with very early bits, where especially new or newly implemented features do not have the quality or stability of a final product. The aim of the CTP is not to give you a productive work environment but to give you the best possible impression of what we are working on for the next release. The CTP contains a number of walkthroughs, some of which highlight the new language features of C# 4.0. Those are excellent for getting a hands-on guided tour through the details of some common scenarios for the features. You may consider this whitepaper a companion document to these walkthroughs, complementing them with a focus on the overall language features and how they work, as opposed to the specifics of the concrete scenarios. C# 4.0 The major theme for C# 4.0 is dynamic programming. Increasingly, objects are “dynamic” in the sense that their structure and behavior is not captured by a static type, or at least not one that the compiler knows about when compiling your program. Some examples include a. objects from dynamic programming languages, such as Python or Ruby b. COM objects accessed through IDispatch c. ordinary .NET types accessed through reflection d. objects with changing structure, such as HTML DOM objects While C# remains a statically typed language, we aim to vastly improve the interaction with such objects. A secondary theme is co-evolution with Visual Basic. Going forward we will aim to maintain the individual character of each language, but at the same time important new features should be introduced in both languages at the same time. They should be differentiated more by style and feel than by feature set. The new features in C# 4.0 fall into four groups: Dynamic lookup Dynamic lookup allows you to write method, operator and indexer calls, property and field accesses, and even object invocations which bypass the C# static type checking and instead gets resolved at runtime. Named and optional parameters Parameters in C# can now be specified as optional by providing a default value for them in a member declaration. When the member is invoked, optional arguments can be omitted. Furthermore, any argument can be passed by parameter name instead of position. COM specific interop features Dynamic lookup as well as named and optional parameters both help making programming against COM less painful than today. On top of that, however, we are adding a number of other small features that further improve the interop experience. Variance It used to be that an IEnumerable<string> wasn’t an IEnumerable<object>. Now it is – C# embraces type safe “co-and contravariance” and common BCL types are updated to take advantage of that. Dynamic Lookup Dynamic lookup allows you a unified approach to invoking things dynamically. With dynamic lookup, when you have an object in your hand you do not need to worry about whether it comes from COM, IronPython, the HTML DOM or reflection; you just apply operations to it and leave it to the runtime to figure out what exactly those operations mean for that particular object. This affords you enormous flexibility, and can greatly simplify your code, but it does come with a significant drawback: Static typing is not maintained for these operations. A dynamic object is assumed at compile time to support any operation, and only at runtime will you get an error if it wasn’t so. Oftentimes this will be no loss, because the object wouldn’t have a static type anyway, in other cases it is a tradeoff between brevity and safety. In order to facilitate this tradeoff, it is a design goal of C# to allow you to opt in or opt out of dynamic behavior on every single call. The dynamic type C# 4.0 introduces a new static type called dynamic. When you have an object of type dynamic you can “do things to it” that are resolved only at runtime: dynamic d = GetDynamicObject(…); d.M(7); The C# compiler allows you to call a method with any name and any arguments on d because it is of type dynamic. At runtime the actual object that d refers to will be examined to determine what it means to “call M with an int” on it. The type dynamic can be thought of as a special version of the type object, which signals that the object can be used dynamically. It is easy to opt in or out of dynamic behavior: any object can be implicitly converted to dynamic, “suspending belief” until runtime. Conversely, there is an “assignment conversion” from dynamic to any other type, which allows implicit conversion in assignment-like constructs: dynamic d = 7; // implicit conversion int i = d; // assignment conversion Dynamic operations Not only method calls, but also field and property accesses, indexer and operator calls and even delegate invocations can be dispatched dynamically: dynamic d = GetDynamicObject(…); d.M(7); // calling methods d.f = d.P; // getting and settings fields and properties d[“one”] = d[“two”]; // getting and setting thorugh indexers int i = d + 3; // calling operators string s = d(5,7); // invoking as a delegate The role of the C# compiler here is simply to package up the necessary information about “what is being done to d”, so that the runtime can pick it up and determine what the exact meaning of it is given an actual object d. Think of it as deferring part of the compiler’s job to runtime. The result of any dynamic operation is itself of type dynamic. Runtime lookup At runtime a dynamic operation is dispatched according to the nature of its target object d: COM objects If d is a COM object, the operation is dispatched dynamically through COM IDispatch. This allows calling to COM types that don’t have a Primary Interop Assembly (PIA), and relying on COM features that don’t have a counterpart in C#, such as indexed properties and default properties. Dynamic objects If d implements the interface IDynamicObject d itself is asked to perform the operation. Thus by implementing IDynamicObject a type can completely redefine the meaning of dynamic operations. This is used intensively by dynamic languages such as IronPython and IronRuby to implement their own dynamic object models. It will also be used by APIs, e.g. by the HTML DOM to allow direct access to the object’s properties using property syntax. Plain objects Otherwise d is a standard .NET object, and the operation will be dispatched using reflection on its type and a C# “runtime binder” which implements C#’s lookup and overload resolution semantics at runtime. This is essentially a part of the C# compiler running as a runtime component to “finish the work” on dynamic operations that was deferred by the static compiler. Example Assume the following code: dynamic d1 = new Foo(); dynamic d2 = new Bar(); string s; d1.M(s, d2, 3, null); Because the receiver of the call to M is dynamic, the C# compiler does not try to resolve the meaning of the call. Instead it stashes away information for the runtime about the call. This information (often referred to as the “payload”) is essentially equivalent to: “Perform an instance method call of M with the following arguments: 1. a string 2. a dynamic 3. a literal int 3 4. a literal object null” At runtime, assume that the actual type Foo of d1 is not a COM type and does not implement IDynamicObject. In this case the C# runtime binder picks up to finish the overload resolution job based on runtime type information, proceeding as follows: 1. Reflection is used to obtain the actual runtime types of the two objects, d1 and d2, that did not have a static type (or rather had the static type dynamic). The result is Foo for d1 and Bar for d2. 2. Method lookup and overload resolution is performed on the type Foo with the call M(string,Bar,3,null) using ordinary C# semantics. 3. If the method is found it is invoked; otherwise a runtime exception is thrown. Overload resolution with dynamic arguments Even if the receiver of a method call is of a static type, overload resolution can still happen at runtime. This can happen if one or more of the arguments have the type dynamic: Foo foo = new Foo(); dynamic d = new Bar(); var result = foo.M(d); The C# runtime binder will choose between the statically known overloads of M on Foo, based on the runtime type of d, namely Bar. The result is again of type dynamic. The Dynamic Language Runtime An important component in the underlying implementation of dynamic lookup is the Dynamic Language Runtime (DLR), which is a new API in .NET 4.0. The DLR provides most of the infrastructure behind not only C# dynamic lookup but also the implementation of several dynamic programming languages on .NET, such as IronPython and IronRuby. Through this common infrastructure a high degree of interoperability is ensured, but just as importantly the DLR provides excellent caching mechanisms which serve to greatly enhance the efficiency of runtime dispatch. To the user of dynamic lookup in C#, the DLR is invisible except for the improved efficiency. However, if you want to implement your own dynamically dispatched objects, the IDynamicObject interface allows you to interoperate with the DLR and plug in your own behavior. This is a rather advanced task, which requires you to understand a good deal more about the inner workings of the DLR. For API writers, however, it can definitely be worth the trouble in order to vastly improve the usability of e.g. a library representing an inherently dynamic domain. Open issues There are a few limitations and things that might work differently than you would expect. · The DLR allows objects to be created from objects that represent classes. However, the current implementation of C# doesn’t have syntax to support this. · Dynamic lookup will not be able to find extension methods. Whether extension methods apply or not depends on the static context of the call (i.e. which using clauses occur), and this context information is not currently kept as part of the payload. · Anonymous functions (i.e. lambda expressions) cannot appear as arguments to a dynamic method call. The compiler cannot bind (i.e. “understand”) an anonymous function without knowing what type it is converted to. One consequence of these limitations is that you cannot easily use LINQ queries over dynamic objects: dynamic collection = …; var result = collection.Select(e => e + 5); If the Select method is an extension method, dynamic lookup will not find it. Even if it is an instance method, the above does not compile, because a lambda expression cannot be passed as an argument to a dynamic operation. There are no plans to address these limitations in C# 4.0. Named and Optional Arguments Named and optional parameters are really two distinct features, but are often useful together. Optional parameters allow you to omit arguments to member invocations, whereas named arguments is a way to provide an argument using the name of the corresponding parameter instead of relying on its position in the parameter list. Some APIs, most notably COM interfaces such as the Office automation APIs, are written specifically with named and optional parameters in mind. Up until now it has been very painful to call into these APIs from C#, with sometimes as many as thirty arguments having to be explicitly passed, most of which have reasonable default values and could be omitted. Even in APIs for .NET however you sometimes find yourself compelled to write many overloads of a method with different combinations of parameters, in order to provide maximum usability to the callers. Optional parameters are a useful alternative for these situations. Optional parameters A parameter is declared optional simply by providing a default value for it: public void M(int x, int y = 5, int z = 7); Here y and z are optional parameters and can be omitted in calls: M(1, 2, 3); // ordinary call of M M(1, 2); // omitting z – equivalent to M(1, 2, 7) M(1); // omitting both y and z – equivalent to M(1, 5, 7) Named and optional arguments C# 4.0 does not permit you to omit arguments between commas as in M(1,,3). This could lead to highly unreadable comma-counting code. Instead any argument can be passed by name. Thus if you want to omit only y from a call of M you can write: M(1, z: 3); // passing z by name or M(x: 1, z: 3); // passing both x and z by name or even M(z: 3, x: 1); // reversing the order of arguments All forms are equivalent, except that arguments are always evaluated in the order they appear, so in the last example the 3 is evaluated before the 1. Optional and named arguments can be used not only with methods but also with indexers and constructors. Overload resolution Named and optional arguments affect overload resolution, but the changes are relatively simple: A signature is applicable if all its parameters are either optional or have exactly one corresponding argument (by name or position) in the call which is convertible to the parameter type. Betterness rules on conversions are only applied for arguments that are explicitly given – omitted optional arguments are ignored for betterness purposes. If two signatures are equally good, one that does not omit optional parameters is preferred. M(string s, int i = 1); M(object o); M(int i, string s = “Hello”); M(int i); M(5); Given these overloads, we can see the working of the rules above. M(string,int) is not applicable because 5 doesn’t convert to string. M(int,string) is applicable because its second parameter is optional, and so, obviously are M(object) and M(int). M(int,string) and M(int) are both better than M(object) because the conversion from 5 to int is better than the conversion from 5 to object. Finally M(int) is better than M(int,string) because no optional arguments are omitted. Thus the method that gets called is M(int). Features for COM interop Dynamic lookup as well as named and optional parameters greatly improve the experience of interoperating with COM APIs such as the Office Automation APIs. In order to remove even more of the speed bumps, a couple of small COM-specific features are also added to C# 4.0. Dynamic import Many COM methods accept and return variant types, which are represented in the PIAs as object. In the vast majority of cases, a programmer calling these methods already knows the static type of a returned object from context, but explicitly has to perform a cast on the returned value to make use of that knowledge. These casts are so common that they constitute a major nuisance. In order to facilitate a smoother experience, you can now choose to import these COM APIs in such a way that variants are instead represented using the type dynamic. In other words, from your point of view, COM signatures now have occurrences of dynamic instead of object in them. This means that you can easily access members directly off a returned object, or you can assign it to a strongly typed local variable without having to cast. To illustrate, you can now say excel.Cells[1, 1].Value = "Hello"; instead of ((Excel.Range)excel.Cells[1, 1]).Value2 = "Hello"; and Excel.Range range = excel.Cells[1, 1]; instead of Excel.Range range = (Excel.Range)excel.Cells[1, 1]; Compiling without PIAs Primary Interop Assemblies are large .NET assemblies generated from COM interfaces to facilitate strongly typed interoperability. They provide great support at design time, where your experience of the interop is as good as if the types where really defined in .NET. However, at runtime these large assemblies can easily bloat your program, and also cause versioning issues because they are distributed independently of your application. The no-PIA feature allows you to continue to use PIAs at design time without having them around at runtime. Instead, the C# compiler will bake the small part of the PIA that a program actually uses directly into its assembly. At runtime the PIA does not have to be loaded. Omitting ref Because of a different programming model, many COM APIs contain a lot of reference parameters. Contrary to refs in C#, these are typically not meant to mutate a passed-in argument for the subsequent benefit of the caller, but are simply another way of passing value parameters. It therefore seems unreasonable that a C# programmer should have to create temporary variables for all such ref parameters and pass these by reference. Instead, specifically for COM methods, the C# compiler will allow you to pass arguments by value to such a method, and will automatically generate temporary variables to hold the passed-in values, subsequently discarding these when the call returns. In this way the caller sees value semantics, and will not experience any side effects, but the called method still gets a reference. Open issues A few COM interface features still are not surfaced in C#. Most notably these include indexed properties and default properties. As mentioned above these will be respected if you access COM dynamically, but statically typed C# code will still not recognize them. There are currently no plans to address these remaining speed bumps in C# 4.0. Variance An aspect of generics that often comes across as surprising is that the following is illegal: IList<string> strings = new List<string>(); IList<object> objects = strings; The second assignment is disallowed because strings does not have the same element type as objects. There is a perfectly good reason for this. If it were allowed you could write: objects[0] = 5; string s = strings[0]; Allowing an int to be inserted into a list of strings and subsequently extracted as a string. This would be a breach of type safety. However, there are certain interfaces where the above cannot occur, notably where there is no way to insert an object into the collection. Such an interface is IEnumerable<T>. If instead you say: IEnumerable<object> objects = strings; There is no way we can put the wrong kind of thing into strings through objects, because objects doesn’t have a method that takes an element in. Variance is about allowing assignments such as this in cases where it is safe. The result is that a lot of situations that were previously surprising now just work. Covariance In .NET 4.0 the IEnumerable<T> interface will be declared in the following way: public interface IEnumerable<out T> : IEnumerable { IEnumerator<T> GetEnumerator(); } public interface IEnumerator<out T> : IEnumerator { bool MoveNext(); T Current { get; } } The “out” in these declarations signifies that the T can only occur in output position in the interface – the compiler will complain otherwise. In return for this restriction, the interface becomes “covariant” in T, which means that an IEnumerable<A> is considered an IEnumerable<B> if A has a reference conversion to B. As a result, any sequence of strings is also e.g. a sequence of objects. This is useful e.g. in many LINQ methods. Using the declarations above: var result = strings.Union(objects); // succeeds with an IEnumerable<object> This would previously have been disallowed, and you would have had to to some cumbersome wrapping to get the two sequences to have the same element type. Contravariance Type parameters can also have an “in” modifier, restricting them to occur only in input positions. An example is IComparer<T>: public interface IComparer<in T> { public int Compare(T left, T right); } The somewhat baffling result is that an IComparer<object> can in fact be considered an IComparer<string>! It makes sense when you think about it: If a comparer can compare any two objects, it can certainly also compare two strings. This property is referred to as contravariance. A generic type can have both in and out modifiers on its type parameters, as is the case with the Func<…> delegate types: public delegate TResult Func<in TArg, out TResult>(TArg arg); Obviously the argument only ever comes in, and the result only ever comes out. Therefore a Func<object,string> can in fact be used as a Func<string,object>. Limitations Variant type parameters can only be declared on interfaces and delegate types, due to a restriction in the CLR. Variance only applies when there is a reference conversion between the type arguments. For instance, an IEnumerable<int> is not an IEnumerable<object> because the conversion from int to object is a boxing conversion, not a reference conversion. Also please note that the CTP does not contain the new versions of the .NET types mentioned above. In order to experiment with variance you have to declare your own variant interfaces and delegate types. COM Example Here is a larger Office automation example that shows many of the new C# features in action. using System; using System.Diagnostics; using System.Linq; using Excel = Microsoft.Office.Interop.Excel; using Word = Microsoft.Office.Interop.Word; class Program { static void Main(string[] args) { var excel = new Excel.Application(); excel.Visible = true; excel.Workbooks.Add(); // optional arguments omitted excel.Cells[1, 1].Value = "Process Name"; // no casts; Value dynamically excel.Cells[1, 2].Value = "Memory Usage"; // accessed var processes = Process.GetProcesses() .OrderByDescending(p =&gt; p.WorkingSet) .Take(10); int i = 2; foreach (var p in processes) { excel.Cells[i, 1].Value = p.ProcessName; // no casts excel.Cells[i, 2].Value = p.WorkingSet; // no casts i++; } Excel.Range range = excel.Cells[1, 1]; // no casts Excel.Chart chart = excel.ActiveWorkbook.Charts. Add(After: excel.ActiveSheet); // named and optional arguments chart.ChartWizard( Source: range.CurrentRegion, Title: "Memory Usage in " + Environment.MachineName); //named+optional chart.ChartStyle = 45; chart.CopyPicture(Excel.XlPictureAppearance.xlScreen, Excel.XlCopyPictureFormat.xlBitmap, Excel.XlPictureAppearance.xlScreen); var word = new Word.Application(); word.Visible = true; word.Documents.Add(); // optional arguments word.Selection.Paste(); } } The code is much more terse and readable than the C# 3.0 counterpart. Note especially how the Value property is accessed dynamically. This is actually an indexed property, i.e. a property that takes an argument; something which C# does not understand. However the argument is optional. Since the access is dynamic, it goes through the runtime COM binder which knows to substitute the default value and call the indexed property. Thus, dynamic COM allows you to avoid accesses to the puzzling Value2 property of Excel ranges. Relationship with Visual Basic A number of the features introduced to C# 4.0 already exist or will be introduced in some form or other in Visual Basic: · Late binding in VB is similar in many ways to dynamic lookup in C#, and can be expected to make more use of the DLR in the future, leading to further parity with C#. · Named and optional arguments have been part of Visual Basic for a long time, and the C# version of the feature is explicitly engineered with maximal VB interoperability in mind. · NoPIA and variance are both being introduced to VB and C# at the same time. VB in turn is adding a number of features that have hitherto been a mainstay of C#. As a result future versions of C# and VB will have much better feature parity, for the benefit of everyone. Resources All available resources concerning C# 4.0 can be accessed through the C# Dev Center. Specifically, this white paper and other resources can be found at the Code Gallery site. Enjoy! span.fullpost {display:none;}

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  • Linux router: ping doesn't route back

    - by El Barto
    I have a Debian box which I'm trying to set up as a router and an Ubuntu box which I'm using as a client. My problem is that when the Ubuntu client tries to ping a server on the Internet, all the packets are lost (though, as you can see below, they seem to go to the server and back without problem). I'm doing this in the Ubuntu Box: # ping -I eth1 my.remote-server.com PING my.remote-server.com (X.X.X.X) from 10.1.1.12 eth1: 56(84) bytes of data. ^C --- my.remote-server.com ping statistics --- 13 packets transmitted, 0 received, 100% packet loss, time 12094ms (I changed the name and IP of the remote server for privacy). From the Debian Router I see this: # tcpdump -i eth1 -qtln icmp tcpdump: verbose output suppressed, use -v or -vv for full protocol decode listening on eth1, link-type EN10MB (Ethernet), capture size 65535 bytes IP X.X.X.X > 10.1.1.12: ICMP echo reply, id 305, seq 7, length 64 IP 10.1.1.12 > X.X.X.X: ICMP echo request, id 305, seq 8, length 64 IP X.X.X.X > 10.1.1.12: ICMP echo reply, id 305, seq 8, length 64 IP 10.1.1.12 > X.X.X.X: ICMP echo request, id 305, seq 9, length 64 IP X.X.X.X > 10.1.1.12: ICMP echo reply, id 305, seq 9, length 64 IP 10.1.1.12 > X.X.X.X: ICMP echo request, id 305, seq 10, length 64 IP X.X.X.X > 10.1.1.12: ICMP echo reply, id 305, seq 10, length 64 IP 10.1.1.12 > X.X.X.X: ICMP echo request, id 305, seq 11, length 64 IP X.X.X.X > 10.1.1.12: ICMP echo reply, id 305, seq 11, length 64 ^C 9 packets captured 9 packets received by filter 0 packets dropped by kernel # tcpdump -i eth2 -qtln icmp tcpdump: verbose output suppressed, use -v or -vv for full protocol decode listening on eth2, link-type EN10MB (Ethernet), capture size 65535 bytes IP 192.168.1.10 > X.X.X.X: ICMP echo request, id 360, seq 213, length 64 IP X.X.X.X > 192.168.1.10: ICMP echo reply, id 360, seq 213, length 64 IP 192.168.1.10 > X.X.X.X: ICMP echo request, id 360, seq 214, length 64 IP X.X.X.X > 192.168.1.10: ICMP echo reply, id 360, seq 214, length 64 IP 192.168.1.10 > X.X.X.X: ICMP echo request, id 360, seq 215, length 64 IP X.X.X.X > 192.168.1.10: ICMP echo reply, id 360, seq 215, length 64 IP 192.168.1.10 > X.X.X.X: ICMP echo request, id 360, seq 216, length 64 IP X.X.X.X > 192.168.1.10: ICMP echo reply, id 360, seq 216, length 64 IP 192.168.1.10 > X.X.X.X: ICMP echo request, id 360, seq 217, length 64 IP X.X.X.X > 192.168.1.10: ICMP echo reply, id 360, seq 217, length 64 ^C 10 packets captured 10 packets received by filter 0 packets dropped by kernel And at the remote server I see this: # tcpdump -i eth0 -qtln icmp tcpdump: verbose output suppressed, use -v or -vv for full protocol decode listening on eth0, link-type EN10MB (Ethernet), capture size 96 bytes IP Y.Y.Y.Y > X.X.X.X: ICMP echo request, id 360, seq 1, length 64 IP X.X.X.X > Y.Y.Y.Y: ICMP echo reply, id 360, seq 1, length 64 IP Y.Y.Y.Y > X.X.X.X: ICMP echo request, id 360, seq 2, length 64 IP X.X.X.X > Y.Y.Y.Y: ICMP echo reply, id 360, seq 2, length 64 IP Y.Y.Y.Y > X.X.X.X: ICMP echo request, id 360, seq 3, length 64 IP X.X.X.X > Y.Y.Y.Y: ICMP echo reply, id 360, seq 3, length 64 IP Y.Y.Y.Y > X.X.X.X: ICMP echo request, id 360, seq 4, length 64 IP X.X.X.X > Y.Y.Y.Y: ICMP echo reply, id 360, seq 4, length 64 IP Y.Y.Y.Y > X.X.X.X: ICMP echo request, id 360, seq 5, length 64 IP X.X.X.X > Y.Y.Y.Y: ICMP echo reply, id 360, seq 5, length 64 IP Y.Y.Y.Y > X.X.X.X: ICMP echo request, id 360, seq 6, length 64 IP X.X.X.X > Y.Y.Y.Y: ICMP echo reply, id 360, seq 6, length 64 IP Y.Y.Y.Y > X.X.X.X: ICMP echo request, id 360, seq 7, length 64 IP X.X.X.X > Y.Y.Y.Y: ICMP echo reply, id 360, seq 7, length 64 IP Y.Y.Y.Y > X.X.X.X: ICMP echo request, id 360, seq 8, length 64 IP X.X.X.X > Y.Y.Y.Y: ICMP echo reply, id 360, seq 8, length 64 IP Y.Y.Y.Y > X.X.X.X: ICMP echo request, id 360, seq 9, length 64 IP X.X.X.X > Y.Y.Y.Y: ICMP echo reply, id 360, seq 9, length 64 18 packets captured 228 packets received by filter 92 packets dropped by kernel Here "X.X.X.X" is my remote server's IP and "Y.Y.Y.Y" is my local network's public IP. So, what I understand is that the ping packets are coming out of the Ubuntu box (10.1.1.12), to the router (10.1.1.1), from there to the next router (192.168.1.1) and reaching the remote server (X.X.X.X). Then they come back all the way to the Debian router, but they never reach the Ubuntu box back. What am I missing? Here's the Debian router setup: # ifconfig eth1 Link encap:Ethernet HWaddr 94:0c:6d:82:0d:98 inet addr:10.1.1.1 Bcast:10.1.1.255 Mask:255.255.255.0 inet6 addr: fe80::960c:6dff:fe82:d98/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:105761 errors:0 dropped:0 overruns:0 frame:0 TX packets:48944 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:40298768 (38.4 MiB) TX bytes:44831595 (42.7 MiB) Interrupt:19 Base address:0x6000 eth2 Link encap:Ethernet HWaddr 6c:f0:49:a4:47:38 inet addr:192.168.1.10 Bcast:192.168.1.255 Mask:255.255.255.0 inet6 addr: fe80::6ef0:49ff:fea4:4738/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:38335992 errors:0 dropped:0 overruns:0 frame:0 TX packets:37097705 errors:0 dropped:0 overruns:0 carrier:1 collisions:0 txqueuelen:1000 RX bytes:4260680226 (3.9 GiB) TX bytes:3759806551 (3.5 GiB) Interrupt:27 eth3 Link encap:Ethernet HWaddr 94:0c:6d:82:c8:72 UP BROADCAST MULTICAST MTU:1500 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:0 (0.0 B) TX bytes:0 (0.0 B) Interrupt:20 Base address:0x2000 lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:3408 errors:0 dropped:0 overruns:0 frame:0 TX packets:3408 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:358445 (350.0 KiB) TX bytes:358445 (350.0 KiB) tun0 Link encap:UNSPEC HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00 inet addr:10.8.0.1 P-t-P:10.8.0.2 Mask:255.255.255.255 UP POINTOPOINT RUNNING NOARP MULTICAST MTU:1500 Metric:1 RX packets:2767779 errors:0 dropped:0 overruns:0 frame:0 TX packets:1569477 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:100 RX bytes:3609469393 (3.3 GiB) TX bytes:96113978 (91.6 MiB) # route -n Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 10.8.0.2 0.0.0.0 255.255.255.255 UH 0 0 0 tun0 127.0.0.1 0.0.0.0 255.255.255.255 UH 0 0 0 lo 10.8.0.0 10.8.0.2 255.255.255.0 UG 0 0 0 tun0 192.168.1.0 0.0.0.0 255.255.255.0 U 1 0 0 eth2 10.1.1.0 0.0.0.0 255.255.255.0 U 0 0 0 eth1 0.0.0.0 192.168.1.1 0.0.0.0 UG 0 0 0 eth2 # arp -n # Note: Here I have changed all the different MACs except the ones corresponding to the Ubuntu box (on 10.1.1.12 and 192.168.1.12) Address HWtype HWaddress Flags Mask Iface 192.168.1.118 ether NN:NN:NN:NN:NN:NN C eth2 192.168.1.72 ether NN:NN:NN:NN:NN:NN C eth2 192.168.1.94 ether NN:NN:NN:NN:NN:NN C eth2 192.168.1.102 ether NN:NN:NN:NN:NN:NN C eth2 10.1.1.12 ether 00:1e:67:15:2b:f0 C eth1 192.168.1.86 ether NN:NN:NN:NN:NN:NN C eth2 192.168.1.2 ether NN:NN:NN:NN:NN:NN C eth2 192.168.1.61 ether NN:NN:NN:NN:NN:NN C eth2 192.168.1.64 ether NN:NN:NN:NN:NN:NN C eth2 192.168.1.116 ether NN:NN:NN:NN:NN:NN C eth2 192.168.1.91 ether NN:NN:NN:NN:NN:NN C eth2 192.168.1.52 ether NN:NN:NN:NN:NN:NN C eth2 192.168.1.93 ether NN:NN:NN:NN:NN:NN C eth2 192.168.1.87 ether NN:NN:NN:NN:NN:NN C eth2 192.168.1.92 ether NN:NN:NN:NN:NN:NN C eth2 192.168.1.100 ether NN:NN:NN:NN:NN:NN C eth2 192.168.1.40 ether NN:NN:NN:NN:NN:NN C eth2 192.168.1.53 ether NN:NN:NN:NN:NN:NN C eth2 192.168.1.1 ether NN:NN:NN:NN:NN:NN C eth2 192.168.1.83 ether NN:NN:NN:NN:NN:NN C eth2 192.168.1.89 ether NN:NN:NN:NN:NN:NN C eth2 192.168.1.12 ether 00:1e:67:15:2b:f1 C eth2 192.168.1.77 ether NN:NN:NN:NN:NN:NN C eth2 192.168.1.66 ether NN:NN:NN:NN:NN:NN C eth2 192.168.1.90 ether NN:NN:NN:NN:NN:NN C eth2 192.168.1.65 ether NN:NN:NN:NN:NN:NN C eth2 192.168.1.41 ether NN:NN:NN:NN:NN:NN C eth2 192.168.1.78 ether NN:NN:NN:NN:NN:NN C eth2 192.168.1.123 ether NN:NN:NN:NN:NN:NN C eth2 # iptables -L -n Chain INPUT (policy ACCEPT) target prot opt source destination Chain FORWARD (policy ACCEPT) target prot opt source destination Chain OUTPUT (policy ACCEPT) target prot opt source destination # iptables -L -n -t nat Chain PREROUTING (policy ACCEPT) target prot opt source destination Chain POSTROUTING (policy ACCEPT) target prot opt source destination MASQUERADE all -- 10.1.1.0/24 !10.1.1.0/24 MASQUERADE all -- !10.1.1.0/24 10.1.1.0/24 Chain OUTPUT (policy ACCEPT) target prot opt source destination And here's the Ubuntu box: # ifconfig eth0 Link encap:Ethernet HWaddr 00:1e:67:15:2b:f1 inet addr:192.168.1.12 Bcast:192.168.1.255 Mask:255.255.255.0 inet6 addr: fe80::21e:67ff:fe15:2bf1/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:28785139 errors:0 dropped:0 overruns:0 frame:0 TX packets:19050735 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:32068182803 (32.0 GB) TX bytes:6061333280 (6.0 GB) Interrupt:16 Memory:b1a00000-b1a20000 eth1 Link encap:Ethernet HWaddr 00:1e:67:15:2b:f0 inet addr:10.1.1.12 Bcast:10.1.1.255 Mask:255.255.255.0 inet6 addr: fe80::21e:67ff:fe15:2bf0/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:285086 errors:0 dropped:0 overruns:0 frame:0 TX packets:12719 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:30817249 (30.8 MB) TX bytes:2153228 (2.1 MB) Interrupt:16 Memory:b1900000-b1920000 lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:86048 errors:0 dropped:0 overruns:0 frame:0 TX packets:86048 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:11426538 (11.4 MB) TX bytes:11426538 (11.4 MB) # route -n Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 0.0.0.0 192.168.1.1 0.0.0.0 UG 0 0 0 eth0 0.0.0.0 10.1.1.1 0.0.0.0 UG 100 0 0 eth1 10.1.1.0 0.0.0.0 255.255.255.0 U 0 0 0 eth1 10.8.0.0 192.168.1.10 255.255.255.0 UG 0 0 0 eth0 169.254.0.0 0.0.0.0 255.255.0.0 U 1000 0 0 eth0 192.168.1.0 0.0.0.0 255.255.255.0 U 1 0 0 eth0 # arp -n # Note: Here I have changed all the different MACs except the ones corresponding to the Debian box (on 10.1.1.1 and 192.168.1.10) Address HWtype HWaddress Flags Mask Iface 192.168.1.70 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.90 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.97 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.103 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.13 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.120 (incomplete) eth0 192.168.1.111 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.118 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.51 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.102 (incomplete) eth0 192.168.1.64 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.52 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.74 (incomplete) eth0 192.168.1.94 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.121 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.72 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.87 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.91 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.71 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.78 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.83 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.88 (incomplete) eth0 192.168.1.82 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.98 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.100 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.93 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.73 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.11 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.85 (incomplete) eth0 192.168.1.112 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.89 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.65 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.81 ether NN:NN:NN:NN:NN:NN C eth0 10.1.1.1 ether 94:0c:6d:82:0d:98 C eth1 192.168.1.53 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.116 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.61 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.10 ether 6c:f0:49:a4:47:38 C eth0 192.168.1.86 (incomplete) eth0 192.168.1.119 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.66 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.1 ether NN:NN:NN:NN:NN:NN C eth0 192.168.1.1 ether NN:NN:NN:NN:NN:NN C eth1 192.168.1.92 ether NN:NN:NN:NN:NN:NN C eth0 # iptables -L -n Chain INPUT (policy ACCEPT) target prot opt source destination Chain FORWARD (policy ACCEPT) target prot opt source destination Chain OUTPUT (policy ACCEPT) target prot opt source destination # iptables -L -n -t nat Chain PREROUTING (policy ACCEPT) target prot opt source destination Chain INPUT (policy ACCEPT) target prot opt source destination Chain OUTPUT (policy ACCEPT) target prot opt source destination Chain POSTROUTING (policy ACCEPT) target prot opt source destination Edit: Following Patrick's suggestion, I did a tcpdump con the Ubuntu box and I see this: # tcpdump -i eth1 -qtln icmp tcpdump: verbose output suppressed, use -v or -vv for full protocol decode listening on eth1, link-type EN10MB (Ethernet), capture size 65535 bytes IP 10.1.1.12 > X.X.X.X: ICMP echo request, id 21967, seq 1, length 64 IP X.X.X.X > 10.1.1.12: ICMP echo reply, id 21967, seq 1, length 64 IP 10.1.1.12 > X.X.X.X: ICMP echo request, id 21967, seq 2, length 64 IP X.X.X.X > 10.1.1.12: ICMP echo reply, id 21967, seq 2, length 64 IP 10.1.1.12 > X.X.X.X: ICMP echo request, id 21967, seq 3, length 64 IP X.X.X.X > 10.1.1.12: ICMP echo reply, id 21967, seq 3, length 64 IP 10.1.1.12 > X.X.X.X: ICMP echo request, id 21967, seq 4, length 64 IP X.X.X.X > 10.1.1.12: ICMP echo reply, id 21967, seq 4, length 64 IP 10.1.1.12 > X.X.X.X: ICMP echo request, id 21967, seq 5, length 64 IP X.X.X.X > 10.1.1.12: ICMP echo reply, id 21967, seq 5, length 64 IP 10.1.1.12 > X.X.X.X: ICMP echo request, id 21967, seq 6, length 64 IP X.X.X.X > 10.1.1.12: ICMP echo reply, id 21967, seq 6, length 64 ^C 12 packets captured 12 packets received by filter 0 packets dropped by kernel So the question is: if all packets seem to be coming and going, why does ping report 100% packet loss?

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  • trying to use mod_proxy with httpd and tomcat

    - by techsjs2012
    I been trying to use mod_proxy with httpd and tomcat... I have on VirtualBox running Scientific Linux which has httpd and tomcat 6 on it.. I made two nodes of tomcat6. I followed this guide like 10 times and still cant get the 2nd node of tomcat working.. http://www.richardnichols.net/2010/08/5-minute-guide-clustering-apache-tomcat/ Here is the lines from my http.conf file <Proxy balancer://testcluster stickysession=JSESSIONID> BalancerMember ajp://127.0.0.1:8009 min=10 max=100 route=node1 loadfactor=1 BalancerMember ajp://127.0.0.1:8109 min=10 max=100 route=node2 loadfactor=1 </Proxy> ProxyPass /examples balancer://testcluster/examples <Location /balancer-manager> SetHandler balancer-manager AuthType Basic AuthName "Balancer Manager" AuthUserFile "/etc/httpd/conf/.htpasswd" Require valid-user </Location> Now here is my server.xml from node1 <?xml version='1.0' encoding='utf-8'?> <!-- Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements. See the NOTICE file distributed with this work for additional information regarding copyright ownership. The ASF licenses this file to You under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License. --> <!-- Note: A "Server" is not itself a "Container", so you may not define subcomponents such as "Valves" at this level. Documentation at /docs/config/server.html --> <Server port="8005" shutdown="SHUTDOWN"> <!--APR library loader. Documentation at /docs/apr.html --> <Listener className="org.apache.catalina.core.AprLifecycleListener" SSLEngine="on" /> <!--Initialize Jasper prior to webapps are loaded. Documentation at /docs/jasper-howto.html --> <Listener className="org.apache.catalina.core.JasperListener" /> <!-- Prevent memory leaks due to use of particular java/javax APIs--> <Listener className="org.apache.catalina.core.JreMemoryLeakPreventionListener" /> <!-- JMX Support for the Tomcat server. Documentation at /docs/non-existent.html --> <Listener className="org.apache.catalina.mbeans.ServerLifecycleListener" /> <Listener className="org.apache.catalina.mbeans.GlobalResourcesLifecycleListener" /> <!-- Global JNDI resources Documentation at /docs/jndi-resources-howto.html --> <GlobalNamingResources> <!-- Editable user database that can also be used by UserDatabaseRealm to authenticate users --> <Resource name="UserDatabase" auth="Container" type="org.apache.catalina.UserDatabase" description="User database that can be updated and saved" factory="org.apache.catalina.users.MemoryUserDatabaseFactory" pathname="conf/tomcat-users.xml" /> </GlobalNamingResources> <!-- A "Service" is a collection of one or more "Connectors" that share a single "Container" Note: A "Service" is not itself a "Container", so you may not define subcomponents such as "Valves" at this level. Documentation at /docs/config/service.html --> <Service name="Catalina"> <!--The connectors can use a shared executor, you can define one or more named thread pools--> <!-- <Executor name="tomcatThreadPool" namePrefix="catalina-exec-" maxThreads="150" minSpareThreads="4"/> --> <!-- A "Connector" represents an endpoint by which requests are received and responses are returned. Documentation at : Java HTTP Connector: /docs/config/http.html (blocking & non-blocking) Java AJP Connector: /docs/config/ajp.html APR (HTTP/AJP) Connector: /docs/apr.html Define a non-SSL HTTP/1.1 Connector on port 8080 <Connector port="8080" protocol="HTTP/1.1" connectionTimeout="20000" redirectPort="8443" /> --> <!-- A "Connector" using the shared thread pool--> <!-- <Connector executor="tomcatThreadPool" port="8080" protocol="HTTP/1.1" connectionTimeout="20000" redirectPort="8443" /> --> <!-- Define a SSL HTTP/1.1 Connector on port 8443 This connector uses the JSSE configuration, when using APR, the connector should be using the OpenSSL style configuration described in the APR documentation --> <!-- <Connector port="8443" protocol="HTTP/1.1" SSLEnabled="true" maxThreads="150" scheme="https" secure="true" clientAuth="false" sslProtocol="TLS" /> --> <!-- Define an AJP 1.3 Connector on port 8009 --> <Connector port="8009" protocol="AJP/1.3" redirectPort="8443" /> <!-- An Engine represents the entry point (within Catalina) that processes every request. The Engine implementation for Tomcat stand alone analyzes the HTTP headers included with the request, and passes them on to the appropriate Host (virtual host). Documentation at /docs/config/engine.html --> <!-- You should set jvmRoute to support load-balancing via AJP ie : <Engine name="Catalina" defaultHost="localhost" jvmRoute="jvm1"> --> <Engine name="Catalina" defaultHost="localhost" jvmRoute="node1"> <!--For clustering, please take a look at documentation at: /docs/cluster-howto.html (simple how to) /docs/config/cluster.html (reference documentation) --> <!-- <Cluster className="org.apache.catalina.ha.tcp.SimpleTcpCluster"/> --> <!-- The request dumper valve dumps useful debugging information about the request and response data received and sent by Tomcat. Documentation at: /docs/config/valve.html --> <!-- <Valve className="org.apache.catalina.valves.RequestDumperValve"/> --> <!-- This Realm uses the UserDatabase configured in the global JNDI resources under the key "UserDatabase". Any edits that are performed against this UserDatabase are immediately available for use by the Realm. --> <Realm className="org.apache.catalina.realm.UserDatabaseRealm" resourceName="UserDatabase"/> <!-- Define the default virtual host Note: XML Schema validation will not work with Xerces 2.2. --> <Host name="localhost" appBase="webapps" unpackWARs="true" autoDeploy="true" xmlValidation="false" xmlNamespaceAware="false"> <!-- SingleSignOn valve, share authentication between web applications Documentation at: /docs/config/valve.html --> <!-- <Valve className="org.apache.catalina.authenticator.SingleSignOn" /> --> <!-- Access log processes all example. Documentation at: /docs/config/valve.html --> <!-- <Valve className="org.apache.catalina.valves.AccessLogValve" directory="logs" prefix="localhost_access_log." suffix=".txt" pattern="common" resolveHosts="false"/> --> </Host> </Engine> </Service> </Server> now here is the server.xml file from node2 <?xml version='1.0' encoding='utf-8'?> <!-- Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements. See the NOTICE file distributed with this work for additional information regarding copyright ownership. The ASF licenses this file to You under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License. --> <!-- Note: A "Server" is not itself a "Container", so you may not define subcomponents such as "Valves" at this level. Documentation at /docs/config/server.html --> <Server port="8105" shutdown="SHUTDOWN"> <!--APR library loader. Documentation at /docs/apr.html --> <Listener className="org.apache.catalina.core.AprLifecycleListener" SSLEngine="on" /> <!--Initialize Jasper prior to webapps are loaded. Documentation at /docs/jasper-howto.html --> <Listener className="org.apache.catalina.core.JasperListener" /> <!-- Prevent memory leaks due to use of particular java/javax APIs--> <Listener className="org.apache.catalina.core.JreMemoryLeakPreventionListener" /> <!-- JMX Support for the Tomcat server. Documentation at /docs/non-existent.html --> <Listener className="org.apache.catalina.mbeans.ServerLifecycleListener" /> <Listener className="org.apache.catalina.mbeans.GlobalResourcesLifecycleListener" /> <!-- Global JNDI resources Documentation at /docs/jndi-resources-howto.html --> <GlobalNamingResources> <!-- Editable user database that can also be used by UserDatabaseRealm to authenticate users --> <Resource name="UserDatabase" auth="Container" type="org.apache.catalina.UserDatabase" description="User database that can be updated and saved" factory="org.apache.catalina.users.MemoryUserDatabaseFactory" pathname="conf/tomcat-users.xml" /> </GlobalNamingResources> <!-- A "Service" is a collection of one or more "Connectors" that share a single "Container" Note: A "Service" is not itself a "Container", so you may not define subcomponents such as "Valves" at this level. Documentation at /docs/config/service.html --> <Service name="Catalina"> <!--The connectors can use a shared executor, you can define one or more named thread pools--> <!-- <Executor name="tomcatThreadPool" namePrefix="catalina-exec-" maxThreads="150" minSpareThreads="4"/> --> <!-- A "Connector" represents an endpoint by which requests are received and responses are returned. Documentation at : Java HTTP Connector: /docs/config/http.html (blocking & non-blocking) Java AJP Connector: /docs/config/ajp.html APR (HTTP/AJP) Connector: /docs/apr.html Define a non-SSL HTTP/1.1 Connector on port 8080 <Connector port="8080" protocol="HTTP/1.1" connectionTimeout="20000" redirectPort="8443" /> --> <!-- A "Connector" using the shared thread pool--> <!-- <Connector executor="tomcatThreadPool" port="8080" protocol="HTTP/1.1" connectionTimeout="20000" redirectPort="8443" /> --> <!-- Define a SSL HTTP/1.1 Connector on port 8443 This connector uses the JSSE configuration, when using APR, the connector should be using the OpenSSL style configuration described in the APR documentation --> <!-- <Connector port="8443" protocol="HTTP/1.1" SSLEnabled="true" maxThreads="150" scheme="https" secure="true" clientAuth="false" sslProtocol="TLS" /> --> <!-- Define an AJP 1.3 Connector on port 8009 --> <Connector port="8109" protocol="AJP/1.3" redirectPort="8443" /> <!-- An Engine represents the entry point (within Catalina) that processes every request. The Engine implementation for Tomcat stand alone analyzes the HTTP headers included with the request, and passes them on to the appropriate Host (virtual host). Documentation at /docs/config/engine.html --> <!-- You should set jvmRoute to support load-balancing via AJP ie : <Engine name="Catalina" defaultHost="localhost" jvmRoute="jvm1"> --> <Engine name="Catalina" defaultHost="localhost" jvmRoute="node2"> <!--For clustering, please take a look at documentation at: /docs/cluster-howto.html (simple how to) /docs/config/cluster.html (reference documentation) --> <!-- <Cluster className="org.apache.catalina.ha.tcp.SimpleTcpCluster"/> --> <!-- The request dumper valve dumps useful debugging information about the request and response data received and sent by Tomcat. Documentation at: /docs/config/valve.html --> <!-- <Valve className="org.apache.catalina.valves.RequestDumperValve"/> --> <!-- This Realm uses the UserDatabase configured in the global JNDI resources under the key "UserDatabase". Any edits that are performed against this UserDatabase are immediately available for use by the Realm. --> <Realm className="org.apache.catalina.realm.UserDatabaseRealm" resourceName="UserDatabase"/> <!-- Define the default virtual host Note: XML Schema validation will not work with Xerces 2.2. --> <Host name="localhost" appBase="webapps" unpackWARs="true" autoDeploy="true" xmlValidation="false" xmlNamespaceAware="false"> <!-- SingleSignOn valve, share authentication between web applications Documentation at: /docs/config/valve.html --> <!-- <Valve className="org.apache.catalina.authenticator.SingleSignOn" /> --> <!-- Access log processes all example. Documentation at: /docs/config/valve.html --> <!-- <Valve className="org.apache.catalina.valves.AccessLogValve" directory="logs" prefix="localhost_access_log." suffix=".txt" pattern="common" resolveHosts="false"/> --> </Host> </Engine> </Service> </Server> I dont know what it is. but I been trying for days

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  • External exception C000001E (STATUS_INVALID_LOCK_SEQUENCE)

    - by adnan
    I'm building a web service client. I've used many other functions from this web service, i've finished most of this work. But now i'm getting this error "External exception C000001E" as i try to use the function as example below. Var asi_ : Asi.MCCI_AR000001TR_PortType; asi_Istek : Asi.QUQI_IN000001TR01; asi_Cevap : Asi.QUQI_IN000002TR01; Begin // bla.. blaa. setting wsse header etc. giving httprio parameters .. // bla... blaa.. some code here , creating the asi_Istek, setting the values etc. Try asi_Cevap := asi_.MCCI_AR000001TR_QUQI_IN000001TR(asi_Istek); // **error** Except On e: Exception Do Begin ShowMessage(e.Message); // External exception C000001E End; End; that is sample code, my code is something like that, and i've many other smilar functions of this webservice, which are working without error, but here is missing something but what ? what is the "External exception C000001E" has anyone idea ? thanks.

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  • MVC Html.ActionLink not passing querystring properly

    - by Dave Hanna
    This seems like it should be pretty straight forward, but I'm apparently confused. I have a List view that displays a paged list. At the bottom I have a set of actionlinks: <%= Html.ActionLink("First Page", "List", new { page = 1} ) %> &nbsp; <%= Html.ActionLink("Prev Page", "List", new { page = Model.PageNumber - 1 }) %> &nbsp; <%= Html.ActionLink("Next Page", "List", new { page = Model.PageNumber + 1 }) %> &nbsp; <%= Html.ActionLink("Last Page", "List", new { page = Model.LastPage } )%> I'm using the basic default routes setup, except with "List" substituted for "Index": routes.MapRoute( "Default", // Route name "{controller}/{action}/{id}", // URL with parameters new { controller = "Home", action = "List", id = UrlParameter.Optional } // Parameter defaults ); The problem is that the ActionLink helpers are generating links of the form: http://localhost:2083/Retrofit?page=2 rather than http://localhost:2083/Retrofit/?page=2 (with the trailing slash after the controller name & before the query string). When the first URL is routed, it completely loses the query string - if I look at Request.QueryString by the time it gets to the controller, it's null. If I enter the second URL (with the trailing slash), it comes in properly (i.e., QueryString of "page=2"). So how can I either get the ActionLink helper to generate the right URL, or get the Routing to properly parse what ActionLink is generating? Thanks.

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  • Making TeamCity integrate the Subversion build number into the assembly version.

    - by Lasse V. Karlsen
    I want to adjust the output from my TeamCity build configuration of my class library so that the produced dll files have the following version number: 3.5.0.x, where x is the subversion revision number that TeamCity has picked up. I've found that I can use the BUILD_NUMBER environment variable to get x, but unfortunately I don't understand what else I need to do. The "tutorials" I find all say "You just add this to the script", but they don't say which script, and "this" is usually referring to the AssemblyInfo task from the MSBuild Community Extensions. Do I need to build a custom MSBuild script somehow to use this? Is the "script" the same as either the solution file or the C# project file? I don't know much about the MSBuild process at all, except that I can pass a solution file directly to MSBuild, but what I need to add to "the script" is XML, and the solution file decidedly does not look like XML. So, can anyone point me to a step-by-step guide on how to make this work? This is what I ended up with: Install the MSBuild Community Tasks Edit the .csproj file of my core class library, and change the bottom so that it reads: <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" /> <Import Project="$(MSBuildExtensionsPath)\MSBuildCommunityTasks\MSBuild.Community.Tasks.Targets" /> <Target Name="BeforeBuild"> <AssemblyInfo Condition=" '$(BUILD_NUMBER)' != '' " CodeLanguage="CS" OutputFile="$(MSBuildProjectDirectory)\..\GlobalInfo.cs" AssemblyVersion="3.5.0.0" AssemblyFileVersion="$(BUILD_NUMBER)" /> </Target> <Target Name="AfterBuild"> Change all my AssemblyInfo.cs files so that they don't specify either AssemblyVersion or AssemblyFileVersion (in retrospect, I'll look into putting AssemblyVersion back) Added a link to the now global GlobalInfo.cs that is located just outside all the project Make sure this file is built once, so that I have a default file in source control This will now update GlobalInfo.cs only if the environment variable BUILD_NUMBER is set, which it is when I build through TeamCity. I opted for keeping AssemblyVersion constant, so that references still work, and only update AssemblyFileVersion, so that I can see which build a dll is from.

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  • What good technology podcasts are out there?

    - by Michael Stum
    Yes, Podcasts, those nice little Audiobooks I can listen to on the way to work. With the current amount of Podcasts, it's like searching a needle in a haystack, except that the haystack happens to be the Internet and is filled with too many of these "Hot new Gadgets" stuff :( Now, even though I am mainly a .NET developer nowadays, maybe anyone knows some good Podcasts from people regarding the whole software lifecycle? Unit Testing, Continous Integration, Documentation, Deployment... So - what are you guys and gals listening to? Please note that the categorizations are somewhat subjective and may not be 100% accurate as many podcasts cover several areas. Categorization is made against what is considered the "main" area. General Software Engineering / Productivity Stack Overflow TekPub (Requires Paid Subscription) SE Radio 43 Folders Perspectives Dr. Dobb's (now a video feed) The Pragmatic Podcast (Inactive) IT Matters Agile Toolkit Podcast The Stack Trace (Inactive) Parleys Techzing The Startup Success Podcast Berkeley CS class lectures FOSS Weekly .NET / Visual Studio / Microsoft Herding Code Hanselminutes .NET Rocks! Deep Fried Bytes Alt.Net Podcast Polymorphic Podcast Sparkling Client (The Silverlight Podcast) dnrTV! Spaghetti Code ASP.NET Podcast Channel 9 Radio TFS PowerScripting Podcast The Thirsty Developer Elegant Code ConnectedShow Crafty Coders Coding QA jQuery yayQuery The official jQuery podcast Java / Groovy The Java Posse Grails Podcast Java Technology Insider Ruby / Rails Railscasts Rails Envy The Ruby on Rails Podcast Rubiverse Web Design / JavaScript / Ajax WebDevRadio Boagworld The Rissington podcast Ajaxian YUI Theater Unix / Linux / Mac / iPhone Mac Developer Network Hacker Public Radio Linux Outlaws Mac OS Ken LugRadio Linux radio show (Inactive) The Linux Action Show! Linux Kernel Mailing List (LKML) Summary Podcast Stanford's iPhone programming class SysAdmin, Security or Infrastructure RunAs Radio Security Now! Crypto-Gram Security Podcast Hak5 VMWare VMTN Windows Weekly PaulDotCom Security The Register - Semi-Coherent Computing FeatherCast General Tech / Business Tekzilla This Week in Tech The Guardian Tech Weekly PCMag Radio Podcast Entrepreneurship Corner Manager Tools Other / Misc. / Podcast Networks IT Conversations Retrobits Podcast No Agenda Netcast Cranky Geeks The Command Line Freelance Radio IBM developerWorks The Register - Open Season Drunk and Retired Technometria Sod This Radio4Nerds Hacker Medley

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  • WCF: Manually configuring Binding and Endpoint causes SerciveChannel Faulted State

    - by Matthias
    Hi there, I've created a ComVisible assembly to be used in a classic-asp application. The assembly should act as a wcf client and connect to a wcf service host (inside a windows service) on the same machine using named pipes. The wcf service host works fine with other clients, so the problem must be within this assembly. In order to get things work I added a service reference to the ComVisible assembly and proxy classes and the corresponding app.config settings were generated for me. Everything fine so far except that the app config would not be recognized when doing an CreateObject with my assembly in the asp code. I went and tried to hardcode (just for testing) the Binding and Endpoint and pass those two to the constructor of my ClientBase derived proxy using this code: private NetNamedPipeBinding clientBinding = null; private EndpointAddress clientAddress = null; clientBinding = new NetNamedPipeBinding(); clientBinding.OpenTimeout = new TimeSpan(0, 1, 0); clientBinding.CloseTimeout = new TimeSpan(0, 0, 10); clientBinding.ReceiveTimeout = new TimeSpan(0, 2, 0); clientBinding.SendTimeout = new TimeSpan(0, 1, 0); clientBinding.TransactionFlow = false; clientBinding.TransferMode = TransferMode.Buffered; clientBinding.TransactionProtocol = TransactionProtocol.OleTransactions; clientBinding.HostNameComparisonMode = HostNameComparisonMode.StrongWildcard; clientBinding.MaxBufferPoolSize = 524288; clientBinding.MaxBufferSize = 65536; clientBinding.MaxConnections = 10; clientBinding.MaxReceivedMessageSize = 65536; clientAddress = new EndpointAddress("net.pipe://MyService/"); MyServiceClient client = new MyServiceClient(clientBinding, clientAddress); client.Open(); // do something with the client client.Close(); But this causes the following error: The communication object, System.ServiceModel.Channels.ServiceChannel, cannot be used for communication because it is in the faulted state. The environment is .Net Framework 3.5 / C#. What am I missing here?

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  • Datapager in silverlight 4 -Nested datagrid visibility issue

    - by Archie
    I have a datagrid in silverlight with child datagrid nested in it. Also I have a DataPager on the outer datagrid. The code looks like this: <data:DataGrid x:Name="dgData" Width="600" ItemsSource="{Binding}" AutoGenerateColumns="False" IsReadOnly="True" HorizontalScrollBarVisibility="Hidden" CanUserSortColumns="False" RowDetailsVisibilityChanged="dgData_RowDetailsVisibilityChanged" Margin="20,0" Grid.RowSpan="2"> <data:DataGrid.Columns> <data:DataGridTextColumn Header="Item" Width="*" Binding="{Binding ItemName,Mode=TwoWay}"/> <data:DataGridTextColumn Header="Company" Width="*" Binding="{Binding Company,Mode=TwoWay}"/> </data:DataGrid.Columns> <data:DataGrid.RowDetailsTemplate> <DataTemplate> <data:DataGrid x:Name="dgRowDetail" Width="400" HorizontalScrollBarVisibility="Hidden" AutoGenerateColumns="False" Visibility="Collapsed"> <data:DataGrid.Columns> <data:DataGridTextColumn Header="Date" Width="*" Binding="{Binding Date,Mode=TwoWay}"/> <data:DataGridTextColumn Header="Price" Width="*" Binding="{Binding Price,Mode=TwoWay}"/> </data:DataGrid.Columns> </data:DataGrid> </DataTemplate> </data:DataGrid.RowDetailsTemplate> </data:DataGrid> <data:DataPager x:Name="dpData" HorizontalAlignment="Center" DisplayMode="FirstLastPreviousNextNumeric" Source="{Binding}"/> I have one PagedCollectionView pgv which is bound to outer datagrid as: DataContext = pgv; When the row is clicked I set the child datagrid's ItemsSource property to another PagedCollectionView. My problem is it works fine except for the first row for the first time. When I click on it, it doesn't fire the dgData_RowDetailsVisibilityChanged event. Also, when I click on second row, firstly first row fires the event and then the second row fires it and shows the nested grid. Please help.

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  • Add an array of buttons to a GridView in an Android application

    - by Tai Squared
    I have an application that will have 5-15 buttons depending on what is available from a backend. How do I define the proper GridView layout files to include an array of buttons that will each have different text and other attributes? Each button will essentially add an item to a cart, so the onClick code will be the same except for the item it adds to the cart. How can I define an array so I can add a variable number of buttons, but still reference each of them by a unique ID? I've seen examples of the arrays.xml, but they have created an array of strings that are pre-set. I need a way to create an object and not have the text defined in the layout or arrays xml file. Update - Added info about adding to a GridView I want to add this to a GridView, so calling the addView method results in an UnsupportedOperationException. I can do the following: ImageButton b2 = new ImageButton(getApplicationContext()); b2.setBackgroundResource(R.drawable.img_3); android.widget.LinearLayout container = (android.widget.LinearLayout) findViewById(R.id.lay); container.addView(b2); but that doesn't layout the buttons in a grid like I would like. Can this be done in a GridView?

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  • ConcurrentDictionary and updating values

    - by rboarman
    Hello, After searching via Google and coming up empty, I decided to ask the gurus here on StackOverflow. I am trying to update entries in a ConcurrentDictionary something like this: class Class1 { public int Counter { get; set; } } class Test { private ConcurrentDictionary<int, Class1> dict = new ConcurrentDictionary<int, Class1>(); public void TestIt() { foreach (var foo in dict) { foo.Value.Counter = foo.Value.Counter + 1; // Simplified example } } } Essentially I need to iterate over the dictionary and update a field on each Value. I understand from the documentation that I need to avoid using the Value property. Instead I think I need to use TryUpdate except that I don’t want to replace my whole object. Instead, I want to update a field on the object. After reading this: http://blogs.msdn.com/b/pfxteam/archive/2010/01/08/9945809.aspx Perhaps I need to use AddOrUpdate and simply do nothing in the add delegate. Does anyone have any insight as to how to do this? Thank you, Rick

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