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• ADO/SQL Server: What is the error code for "timeout expired"?

  - by Ian Boyd

  i'm trying to trap a "timeout expired" error from ADO. When a timeout happens, ADO returns: Number: 0x80040E31 (DB_E_ABORTLIMITREACHED in oledberr.h) SQLState: HYT00 NativeError: 0 The NativeError of zero makes sense, since the timeout is not a function of the database engine (i.e. SQL Server), but of ADO's internal timeout mechanism. The Number (i.e. the COM hresult) looks useful, but the definition of DB_E_ABORTLIMITREACHED in oledberr.h says: Execution stopped because a resource limit was reached. No results were returned. This error could apply to things besides "timeout expired" (some potentially server-side), such as a governor that limits: CPU usage I/O reads/writes network bandwidth and stops a query. The final useful piece is SQLState, which is a database-independent error code system. Unfortunately the only reference for SQLState error codes i can find have no mention of HYT00. What to do? What do do? Note: i can't trust 0x80040E31 (DB_E_ABORTLIMITREACHED) to mean "timeout expired", anymore than i could trust 0x80004005 (E_UNSPECIFIED_ERROR) to mean "Transaction was deadlocked on lock resources with another process and has been chosen as the deadlock victim". My pseudo-question becomes: does anyone have documentation on what the SQLState "HYT000" means? And my real question still remains: How can i specifically trap an ADO timeout expired exception thrown by ADO? Gotta love the questions where the developer is trying to "do the right thing", but nobody knows how to do the right thing. Also gotta love how googling for DB_E_ABORTLIMITREACHED and this question is #9, with MSDN nowhere to be found. Update 3 From the OLEdb ICommand.Execute reference: DB_E_ABORTLIMITREACHED Execution has been aborted because a resource limit has been reached. For example, a query timed out. No results have been returned. "For example", meaning not an exhaustive list.

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• WPF DockPanel doesn't respect the "Filled" control's desired size

  - by Dan Puzey

  I have the following Xaml (simplified for brevity, but will repro the problem in Xamlpad or Kaxaml): <DockPanel Width="400"> <TextBlock DockPanel.Dock="Left" TextWrapping="Wrap"> Lorem ipsum dolor sit amet, consectetur adipiscing elit. Vestibulum massa metus, ornare in fringilla nec, fringilla at orci. Nunc pharetra enim sit amet sapien aliquet eu euismod turpis vehicula. Aenean gravida tempus lectus ut ornare. Nullam massa augue, suscipit vel consectetur fringilla, pretium vitae neque. </TextBlock> <Button MinWidth="100" VerticalAlignment="Center" HorizontalAlignment="Left">Hello world</Button> </DockPanel> My problem is that I want the Button to take its minimum 100px of space, and for the text to wrap suitably to leave that space. However, what happens is that the text wraps as close to 400px as possible, and then the Button is clipped. If I Snoop the output I can see that the button is rendering at the desired 100px, but it's being clipped off the side of the DockPanel. If I reverse the Dock (so the button is docked "Right" and the TextBlock fills) then I get the layout I want, but unfortunately that's not an option due to the surrounding layout. Is there something I can do that will make the DockPanel a) not clip and b) layout in a way that respects the MinWidth? Or am I stuck finding an alternative layout mechanism? Thanks in advance!

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• How to output JSON from within Django and call it with jQuery from a cross domain?

  - by Emre Sevinç

  For a bookmarklet project I'm trying to get JSON data using jQuery from my server (which is naturally on a different domain) running a Django powered system. According to jQuery docs: "As of jQuery 1.2, you can load JSON data located on another domain if you specify a JSONP callback, which can be done like so: "myurl?callback=?". jQuery automatically replaces the ? with the correct method name to call, calling your specified callback." And for example I can test it successfully in my Firebug console using the following snippet: $.getJSON("http://api.flickr.com/services/feeds/photos_public.gne?tags=cat&tagmode=any& format=json&jsoncallback=?", function(data){ alert(data.title); }); It prints the returned data in an alert window, e.g. 'Recent uploads tagged cat'. However when I try the similar code with my server I don't get anything at all: $.getJSON("http://mydjango.yafz.org/randomTest?jsoncallback=?", function(data){ alert(data.title); }); There are no alert windows and the Firebug status bar says "Transferring data from mydjango.yafz.org..." and keeps on waiting. On the server side I have this: def randomTest(request): somelist = ['title', 'This is a constant result'] encoded = json.dumps(somelist) response = HttpResponse(encoded, mimetype = "application/json") return response I also tried this without any success: def randomTest(request): if request.is_ajax() == True: req = {} req ['title'] = 'This is a constant result.' response = json.dumps(req) return HttpResponse(response, mimetype = "application/json") So to cut a long story short: what is the suggested method of returning a piece of data from within a Django view and retrieve it using jQuery in a cross domain fashion? What are my mistakes above?

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• Destructuring assignment in JavaScript

  - by Anders Rune Jensen

  As can be seen in the Mozilla changlog for JavaScript 1.7 they have added destructuring assignment. Sadly I'm not very fond of the syntax (why write a and b twice?): var a, b; [a, b] = f(); Something like this would have been a lot better: var [a, b] = f(); That would still be backwards compatible. Python-like destructuring would not be backwards compatible. Anyway the best solution for JavaScript 1.5 that I have been able to come up with is: function assign(array, map) { var o = Object(); var i = 0; $.each(map, function(e, _) { o[e] = array[i++]; }); return o; } Which works like: var array = [1,2]; var _ = assign[array, { var1: null, var2: null }); _.var1; // prints 1 _.var2; // prints 2 But this really sucks because _ has no meaning. It's just an empty shell to store the names. But sadly it's needed because JavaScript doesn't have pointers. On the plus side you can assign default values in the case the values are not matched. Also note that this solution doesn't try to slice the array. So you can't do something like {first: 0, rest: 0}. But that could easily be done, if one wanted that behavior. What is a better solution?

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• h:commandButton action not working inside a h:datatable.

  - by Chris

  I'm stuck with this piece of jsf code that I don't understand why it's working when used outside a datatable and doesn't inside a datatable... <h:dataTable id="myTable" rendered="true" value="#{bean.selectedItemsList}" var="items"> <h:column> <h:commandButton action="#{bean.removeItemFromList}" image="/resources/images/deleterow.gif"> <f:actionListener binding="#{bean.actionListenerImpl}" type="com.mycorp.ActionListenerImpl"/> </h:commandButton> </h:column> <h:column> <h:outputText value="#{items}" /> </h:column> </h:dataTable> I read around the net to put value="#{items}" inside the action listener so the action can get the items in the row like this: <f:actionListener value="#{items}" binding="#{bean.actionListenerImpl}" type="com.mycorp.ActionListenerImpl"/> But it's doesn't work either. Bu if I do the action outside the data table everything work fine. <h:commandButton action="#{bean.removeItemFromList}" image="/resources/images/deleterow.gif"> <f:actionListener binding="#{bean.actionListenerImpl}" type="com.mycorp.ActionListenerImpl"/> </h:commandButton> Side note I also tried a4j:commandButton and didn't so I guess my problem is probably the actionlistener or how the bean handling it.

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• Can I compare a template variable to an integer in App Engine templates?

  - by matt b

  Using Django templates in Google App Engine (on Python), is it possible to compare a template variable to an integer in an {% if %} block? views.py: class MyHandler(webapp.RequestHandler): def get(self): foo_list = db.GqlQuery(...) ... template_values['foos'] = foo_list template_values['foo_count'] = len(foo_list) handler.response.out.write(template.render(...)) My template: {% if foo_count == 1 %} There is one foo. {% endif %} This blows up with 'if' statement improperly formatted. What I was attempting to do in my template was build a simple if/elif/else tree to be grammatically correct to be able to state #foo_count == 0: There are no foos. #foo_count == 1: There is one foo. #else: There are {{ foos|length }} foos. Browsing the Django template documents (this link provided in the GAE documentation appears to be for versions of Django far newer than what is supported on GAE), it appears as if I can only actually use boolean operators (if in fact boolean operators are supported in this older version of Django) with strings or other template variables. Is it not possible to compare variables to integers or non-strings with Django templates? I'm sure there is an easy way to workaround this - built up the message string on the Python side rather than within the template - but this seems like such a simple operation you ought to be able to handle in a template. It sounds like I should be switching to a more advanced templating engine, but as I am new to Django (templates or any part of it), I'd just like some confirmation first.

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• Optimizing drawing on UITableViewCell

  - by Brian

  I am drawing content to a UITableViewCell and it is working well, but I'm trying to understand if there is a better way of doing this. Each cell has the following components: Thumbnail on the left side - could come from server so it is loaded async Title String - variable length so each cell could be different height Timestamp String Gradient background - the gradient goes from the top of the cell to the bottom and is semi-transparent so that background colors shine through with a gloss It currently works well. The drawing occurs as follows: UITableViewController inits/reuses a cell, sets needed data, and calls [cell setNeedsDisplay] The cell has a CALayer for the thumbnail - thumbnailLayer In the cell's drawRect it draws the gradient background and the two strings The cell's drawRect it then calls setIcon - which gets the thumbnail and sets the image as the contents of the thumbnailLayer. If the image is not found locally, it sets a loading image as the contents of the thumbnailLayer and asynchronously gets the thumbnail. Once the thumbnail is received, it is reset by calling setIcon again & resets the thumbnailLayer.contents This all currently works, but using Instruments I see that the thumbnail is compositing with the gradient. I have tried the following to fix this: setting the cell's backgroundView to a view whose drawRect would draw the gradient so that the cell's drawRect could draw the thumbnail and using setNeedsDisplayInRect would allow me to only redraw the thumbnail after it loaded --- but this resulted in the backgroundView's drawing (gradient) covering the cell's drawing (text). I would just draw the thumbnail in the cell's drawRect, but when setNeedsDisplay is called, drawRect will just overlap another image and the loading image may show through. I would clear the rect, but then I would have to redraw the gradient. I would try to draw the gradient in a CAGradientLayer and store a reference to it, so I can quickly redraw it, but I figured I'd have to redraw the gradient if the cell's height changes. Any ideas? I'm sure I'm missing something so any help would be great.

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• Have error message show when form is created through AJAX

  - by Railslearner

  I have a page called /add that you can add a Dog on and the form is in its own partial. I'm using Simple Form and Twitter Bootstrap. I added the files for the main Bootstrap but use a gem for simple_form to work with it just so you know. DogsController # new.js.erb (deleted new.html.erb) def new @dog = Dog.new respond_to do |format| format.js end end # create.js.erb def create @dog = current_user.dogs.new(params[:dog]) respond_to do |format| if @dog.save format.html { redirect_to add_url, notice: 'Dog was successfully added.' } format.json { render json: @dog, status: :created, location: @dog} format.js else format.html { render 'pages/add' } format.json { render json: @dog.errors, status: :unprocessable_entity } end end end dogs/_form.html.erb <%= simple_form_for(@dog, :remote => true) do |f| %> <%= render :partial => "shared/error_message", :locals => { :f => f } %> <%= f.input :name %> <%= f.button :submit, 'Done' %> <% end %> This line: <%= render :partial => "shared/error_message", :locals => { :f => f } %> Is for bootstrap so it renders the errors html correctly. PagesController def add respond_to do |format| format.html end end pages/add.html.erb <div id="generate-form"> </div> dogs/new.js.erb $("#generate-form").html("<%= escape_javascript(render(:partial => 'dogs/form', locals: { dog: @dog })) %>"); Now how would I get this to render the error partial as if it was still on my dogs/new.html.erb since its being created through AJAX? I don't need client side validations do I?

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• Literal ampersands in System.Uri query string

  - by Nathan Baulch

  I'm working on a client app that uses a restful service to look up companies by name. It's important that I'm able to include literal ampersands in my queries since this character is quite common in company names. However whenever I pass %26 (the URI escaped ampersand character) to System.Uri, it converts it back to a regular ampersand character! On closer inspection, the only two characters that aren't converted back are hash (%23) and percent (%25). Lets say I want to search for a company named "Pierce & Pierce": var endPoint = "http://localhost/companies?where=Name eq '{0}'"; var name = "Pierce & Pierce"; Console.WriteLine(new Uri(string.Format(endPoint, name))); Console.WriteLine(new Uri(string.Format(endPoint, Uri.EscapeUriString(name)))); Console.WriteLine(new Uri(string.Format(endPoint, Uri.EscapeDataString(name)))); All three of the above combinations return: http://localhost/companies?where=Name eq 'Pierce & Pierce' This causes errors on the server side since the ampersand is (correctly) interpreted as a query arg delimiter. What I really need it to return is the original string: http://localhost/companies?where=Name eq 'Pierce %26 Pierce' How can I work around this behavior without discarding System.Uri entirely? I can't replace all ampersands with %26 at the last moment because there will usually be multiple query args involved and I don't want to destroy their delimiters. Note: A similar problem was discussed in this question but I'm specifically referring to System.Uri.

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• Get notified when objective-c dom updates are ready initiated from webview

  - by Josh

  I am programmatically updating the DOM on a WebKit webview via DOMElement objects - for complex UI, there is usually a javascript component to any element that I add. This begs the need to be notified when the updates complete -- is there any such event? I know regular divs dont fire an onload or onready event, correct? The other assumption I had, which may be totally wrong, is that DOMElement updates aren't synchronous, so I can't do something like this and be confident it will meet with the label actually in the DOM: DOMElement *displayNameLabel = [document createElement:@"div"]; [displayNameLabel setAttribute:@"class" value:@"user-display-name"]; [displayNameLabel setTextContent:currentAvatar.avatarData.displayName]; [[document getElementById:@"user-card-content"] appendChild:displayNameLabel]; id win = [webView windowScriptObject]; [win evaluateWebScript:@"javascriptInstantiateLabel()"]; Is this true? I am using jquery within the body of the html already, so I don't mind subscribing to a particular classes set of events via "live." I thought I might be able to do something like: $(".some-class-to-be-added-later").live( "ready", function(){ // Instantiate some fantastic javascript here for .some-class }); but have experienced no joy so far. Is there any way on either side (objective-c since I don't programmatically firing javascript post load, or javascript) to be notified when the element is in the DOM? Thanks, Josh

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• Does Ctypes Structures and POINTERS automatically free the memory when the Python object is deleted?

  - by jsbueno

  When using Python CTypes there are the Structures, that allow you to clone c-structures on the Python side, and the POINTERS objects that create a sofisticated Python Object from a memory address value and can be used to pass objects by reference back and forth C code. What I could not find on the documentation or elsewhere is what happens when a Python object containing a Structure class that was de-referenced from a returning pointer from C Code (that is - the C function alocated memory for the structure) is itself deleted. Is the memory for the original C structure freed? If not how to do it? Furthermore -- what if the Structure contains Pointers itself, to other data that was also allocated by the C function? Does the deletion of the Structure object frees the Pointers onits members? (I doubt so) Else - -how to do it? Trying to call the system "free" from Python for the Pointers in the Structure is crashing Python for me. In other words, I have this structure filled up by a c Function call: class PIX(ctypes.Structure): """Comments not generated """ _fields_ = [ ("w", ctypes.c_uint32), ("h", ctypes.c_uint32), ("d", ctypes.c_uint32), ("wpl", ctypes.c_uint32), ("refcount", ctypes.c_uint32), ("xres", ctypes.c_uint32), ("yres", ctypes.c_uint32), ("informat", ctypes.c_int32), ("text", ctypes.POINTER(ctypes.c_char)), ("colormap", ctypes.POINTER(PIXCOLORMAP)), ("data", ctypes.POINTER(ctypes.c_uint32)) ] And I want to free the memory it is using up from Python code.

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• jquery validator message styling error in IE08 only when customised using errorPlacement function

  - by John Slaytor

  Going back to the errorplacement solution by Nadia (http://stackoverflow.com/questions/860055/jquery-override-default-validation-error-message-display-css-popup-tooltip-like) I have tried it and it works like a charm in Safari and Firefox but causes IE08 to bypass the jqueryvalidator and go straight to the server side validator. My code is this - as soon as I insert 'error element.... it is unstable in IE08. All help much appreciated <script type="text/javascript"> $(document).ready(function() { $("#sampleform").validate({ rules: { dinername: "required", venue: "required", contact: "required", dinertelephone: "required", venuetime: "required", numberdiners: "required", dineremail: { required: true, email: true}, datepicker: { required: true,date: true} }, messages: { dinername: "Your name?", numberdiners: "How many guests?", dinertelephone: "Your mobile?", venue: "Which restaurant?", venuetime: "Your arrival time?", datepicker: "Your booking date?", dineremail: "Please enter a valid email address", }, errorElement: "div", errorPlacement: function(error, element) { element.before(error); offset = element.offset(); error.css('right', offset.right); error.css('right', offset.right - element.outerHeight()); } }); }); </script> <script type="text/javascript"> $(function() { $("#datepicker") .datepicker({minDate: 0, maxDate: '+6M +0D',dateFormat: 'DD, d M yy',onClose: function() {$(this).valid();} }); }); </script> The relevant webpage is http://www.johnslaytor.com.au/nilgiris/forms/bookingform/bookingform.html

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• Visual Studio: How to attach a debugger dynamically to a specific process

  - by Jeff Cyr

  I am building an internal dev tool to manage different processes commonly used in our development environment. The tool show the list the monitored processes, indicate their running state and allow to start or stop each process. I'd like to add the functionality of attaching a debugger to a monitored process from my tool instead of going in 'Debug-Attach to process' in visual studio and finding the process. My goal is to have something like Debugger.Launch() that would show a list of the available visual studio. I can't use Debugger.Launch() because it lauches the debugger on the process that make the call. I would need something like Debugger.Launch(processId). Does anyone know how to acheive this functionality? A solution could be to implement a command in each monitored process to call Debugger.Launch() when the command is received from the monitoring tool, but I would prefer something that does not require to modify the code of the monitored processes. Side question: When using Debugger.Launch(), instances of Visual Studio that already have a debugger attached are not listed. Visual Studio is not limited to one attached debugger, you can attach on multiple process when using 'Debug - Attach to process'. Anyone know how to bypass this limitation when using Debugger.Launch() or an alternative?

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• Using bitwise operators on > 32 bit integers

  - by dqhendricks

  I am using bitwise operations in order to represent many access control flags within one integer. ADMIN_ACCESS = 1; EDIT_ACCOUNT_ACCESS = 2; EDIT_ORDER_ACCESS = 4; var myAccess = 3; // ie: ( ADMIN_ACCESS | EDIT_ACCOUNT_ACCESS ) if ( myAccess & EDIT_ACCOUNT_ACCESS ) { // check for correct access // allow for editing of account } Most of this is occurring on the PHP side of my project. There is one piece however where Javascript is used to join several access flags using | when saving someone's access level. This works fine to a point. I have found that once an integer (flag) gets too large ( 32bit), it no longer works correctly with bitwise operators in Javascript. For instance: alert( 4294967296 | 1 ); // equals 1, but should equal 4294967297 I am trying to find a workaround for this so that I do not have to limit my number of access control flags to 32. Each access control flag is two times the previous control flag so that each control flag will not interfere with other control flags. dec(4) = bin(100) dec(8) = bin(1000) dec(16) = bin(10000) I have noticed that when adding two of these flags together with a simple +, it seems to come out with the same answer as a bitwise or operation, but am having trouble wrapping my head around whether this is a simple substitution, or if there might be problems with doing this. Can anyone comment on the validity of this workaround? Example: (4294967296 | 262144 | 524288) == (4294967296 + 262144 + 524288)

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• Old desktop programmer wants to create S+S project

  - by Craig

  I have an idea for a product that I want to be web-based. But because I live in Brasil, the internet is not always available so there needs to be a desktop component that is available for when the internet is down. Also, I have been a SQL programmer, a desktop application programmer using dBase, VB and Pascal, and I have created simple websites using HTML and website creation tools, such as Frontpage. So from my research, I think I have the following options; PHP, Ruby on Rails, Python or .NET for the programming side. MySQL for the DB. And Apache, or possibly IIS, for the webserver. I will probably start with a local ISP provider for the cloud servce. But then maybe move to something more "robust" and universal in the future, ie. Amazon, or Azure, or something along that line. My question then is this. What would you recommend for something like this? I'm sure that I have not listed all of the possibilities, but the ones I have researched and thought of. Thanks everyone, Craig

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• How do you reenable a validation control w/o it simultaneously performing an immediate validation?

  - by Velika2

  When I called this function to enable a validator from client javascript: `ValidatorEnable(document.getElementById('<%=valPassportOtherText.ClientID%>'), true); //enable` validation control the required validation control immediately performed it validation, found the value in the associated text box blank and set focus to the textbox (because SetFocusOnError was set to true). As a result, the side effect was that focus was shifted to the control that was associated with the Validation control, i teh example, txtSpecifyOccupation. <asp:TextBox ID="txtSpecifyOccupation" runat="server" AutoCompleteType="Disabled" CssClass="DefaultTextBox DefaultWidth" MaxLength="24" Rows="2"></asp:TextBox> <asp:RequiredFieldValidator ID="valSpecifyOccupation" runat="server" ControlToValidate="txtSpecifyOccupation" ErrorMessage="1.14b Please specify your &lt;b&gt;Occupation&lt;/b&gt;" SetFocusOnError="True">&nbsp;Required</asp:RequiredFieldValidator> Perhaps there is a way to enable the (required) validator without having it simultaneously perform the validation (at least until the user has tabbed off of it?) I'd like validation of the txtSpecifyOccupation textbox to occur only on a Page submit or when the user has tabbed of the required txtSpecifyoccupation textbox. How can I achieve this?

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• How do I bind an iTunes style source list to an NSTableView using Core Data?

  - by Austin

  I have an iTunes style interface in my application: Source list (NSOutlineView) on the left that contains different libraries and playlists with an NSTableView on the right side of the interface displaying information for "Presentations". Similar to iTunes, I am showing the same type of information in the table view whether a library or playlist is selected (title, author, date created, etc). I currently have an NSArrayController connected to my NSTableView and was setting the fetch predicate based on what was selected in the source list. This works fine when selecting a library because I can just set the fetch predicate to filter by the "type" field in my Presentation Core Data entity. When I try to adjust the fetch predicate for the playlist however, it doesn't look like there is any way to set the fetch predicate because I've got a table in between Playlists and Presentations to keep up with the order within the Playlist. According to the Apple docs, these type of predicates are not doable with Core Data (it basically doesn't multiple inner joins). Below is the relevant portion of my Data Model. Is my data model setup incorrectly? Should I drop the NSArrayController and handle connecting the NSTableView up by hand? I'm trying to figure out if there is a simple fix, or really a design flaw.

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• RIA Services for transmitting non DB object-graph

  - by Mike Gates

  I have been getting into RIA services because I thought it would simplify dealing with the services layer of web applications I wish to build. I see lots of examples out there showing how to create DomainService classes which expose and consume entities that have some kind of relational database backing, and therefore have foreign-key relationships. However, I would like to know how to expose and consume normal object graphs...objects that contain references to eachother but don't have foreign keys. For example, say I want a service operation called "GetFolderInformation(string pathToFolder)". I want this to return a custom object called "FolderInformation" structured with: - string Name - IEnumerable<FileInformation> Files I cannot get this to work because it seems that RIA wants to deal with entities that have foreign key relationships. Why? Why can't the serializer just see my object references and recreate that in the proxy on the other side? Data exists behind service layers that doesn't necessarily have foreign key relationships...like folder/file for example. EDIT: I realized I hadn't asked my question! My question is, is there a way to do what I am trying to do?

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• What is better in WPF for UI layout, using one Grid, or nested Grids.

  - by Matthijs Wessels

  I am making a UI in WPF, I have a bunch of functional areas and I use a Grid to organize it. Now the Grid that I want is not uniform, as in, some functional area will span multiple cells in the Grid. I was wondering what the best practise is in solving this. Should I create one grid and then for each functional area set it to span multiple cells, or should I split it up into multiple nested Grids. In this image, the leftmost panel (panels separated by the gray bar) is what I want. The middle panel shows one grid where the blue lines are overlapped by a functional area. The rightmost panel shows how I could do it with nested grids. You can see the green grid has one horizontal split. In the bottom cell is the yellow Grid with a vertical split. In side the left cell is the red Grid with again a horizontal split. I was just wondering what is best practise, the middle or the right panel.

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• How to distinguish between two different UDP clients on the same IP address?

  - by Ricket

  I'm writing a UDP server, which is a first for me; I've only done a bit of TCP communications. And I'm having trouble figuring out exactly how to distinguish which user is which, since UDP deals only with packets rather than connections and I therefore cannot tell exactly who I'm communicating with. Here is pseudocode of my current server loop: DatagramPacket p; socket.receive(p); // now p contains the user's IP and port, and the data int key = getKey(p); if(key == 0) { // connection request key = makeKey(p); clients.add(key, p.ip); send(p.ip, p.port, key); // give the user his key } else { // user has a key // verify key belongs to that IP address // lookup the user's session data based on the key // react to the packet in the context of the session } When designing this, I kept in mind these points: Multiple users may exist on the same IP address, due to the presence of routers, therefore users must have a separate identification key. Packets can be spoofed, so the key should be checked against its original IP address and ignored if a different IP tries to use the key. The outbound port on the client side might change among packets. Is that third assumption correct, or can I simply assume that one user = one IP+port combination? Is this commonly done, or should I continue to create a special key like I am currently doing? I'm not completely clear on how TCP negotiates a connection so if you think I should model it off of TCP then please link me to a good tutorial or something on TCP's SYN/SYNACK/ACK mess. Also note, I do have a provision to resend a key, if an IP sends a 0 and that IP already has a pending key; I omitted it to keep the snippet simple. I understand that UDP is not guaranteed to arrive, and I plan to add reliability to the main packet handling code later as well.

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• Dependency between operations in scala actors

  - by paradigmatic

  I am trying to parallelise a code using scala actors. That is my first real code with actors, but I have some experience with Java Mulithreading and MPI in C. However I am completely lost. The workflow I want to realise is a circular pipeline and can be described as the following: Each worker actor has a reference to another one, thus forming a circle There is a coordinator actor which can trigger a computation by sending a StartWork() message When a worker receives a StartWork() message, it process some stuff locally and sends DoWork(...) message to its neighbour in the circle. The neighbours do some other stuff and sends in turn a DoWork(...) message to its own neighbour. This continues until the initial worker receives a DoWork() message. The coordinator can send a GetResult() message to the initial worker and wait for a reply. The point is that the coordinator should only receive a result when data is ready. How can a worker wait that the job returned to it before answering the GetResult() message ? To speed up computation, any worker can receive a StartWork() at any time. Here is my first try pseudo-implementation of the worker: class Worker( neighbor: Worker, numWorkers: Int ) { var ready = Foo() def act() { case StartWork() => { val someData = doStuff() neighbor ! DoWork( someData, numWorkers-1 ) } case DoWork( resultData, remaining ) => if( remaining == 0 ) { ready = resultData } else { val someOtherData = doOtherStuff( resultData ) neighbor ! DoWork( someOtherData, remaining-1 ) } case GetResult() => reply( ready ) } } On the coordinator side: worker ! StartWork() val result = worker !? GetResult() // should wait

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• Asp.Net tree view in SharePoint webpart- Input string error

  - by Faiz

  Hi All, I am facing a very strange issue. I have a SharePoint webpart that displays an asp.net tree view. It takes tree depth from a drop down. To improve performance of the tree view, i am setting the PopulateOnDemand property to true for the last level of the tree depth. For example, if i have a total of 10 levels in the data and the user selects tree depth as 3, then the third level data i set PopulateOnDemand to true. Now comes the strange part. When i click on the + image on the third level, and if there are children under that particular node then call back happens and node gets expanded. But if there no children for that particular node, then click + throws "Input string was not in the correct format" error. I have made sure that there is no server side error. Some things looks to be fishy when internet explorer is trying to bind construct the expanded node. Please let me know if any one faced similar issue or the resolution for the same? Thanks in advance

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• Which key value store is the most promising/stable?

  - by Mike Trpcic

  I'm looking to start using a key/value store for some side projects (mostly as a learning experience), but so many have popped up in the recent past that I've got no idea where to begin. Just listing from memory, I can think of: CouchDB MongoDB Riak Redis Tokyo Cabinet Berkeley DB Cassandra MemcacheDB And I'm sure that there are more out there that have slipped through my search efforts. With all the information out there, it's hard to find solid comparisons between all of the competitors. My criteria and questions are: (Most Important) Which do you recommend, and why? Which one is the fastest? Which one is the most stable? Which one is the easiest to set up and install? Which ones have bindings for Python and/or Ruby? Edit: So far it looks like Redis is the best solution, but that's only because I've gotten one solid response (from ardsrk). I'm looking for more answers like his, because they point me in the direction of useful, quantitative information. Which Key-Value store do you use, and why? Edit 2: If anyone has experience with CouchDB, Riak, or MongoDB, I'd love to hear your experiences with them (and even more so if you can offer a comparative analysis of several of them)

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• _Painless_ integration of Eclipse with Vim?

  - by Adnan

  Hi, Has anyone managed to get Vim integrated into Eclipse painlessly? I just want to use Vim for the editor while retaining the general Eclipse interface. I have tried using Eclim plugin but the editor seemed to crash more often than work (the site said that the editor replacement functionality is still beta). On the flip side, is there any IDE which matches Eclipse's functionality -- mainly the integration with SVN, ant, etc. -- and is also able to use Vim? I mostly use eclipse for SAS SCL, Java and Javascript programming and find the eclipse editor too "mouse-y". I'd also like, in a perfect world, to use vimdiff as a diff viewer for SVN (we use TortoiseSVN) while checking for diffs or conflicts during merge etc. I admit I havent spent a lot of time trying to get these things to work. I feel guilty about spending too much time on potential wild-goose-chases while my other team members are working away at their code, perfectly content with all that eclipse has to offer. Edit: Just found this while desperately browsing around: Vim plugin.. Any experience using this? Its saturday afternoon in Kiwi land, so I'll try it later and update if no one has an opinion. From the claims on the site, it sounds perfect.

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• How to setup OpenGL camera for a racing game

  - by vian

  I need the view to show the road polygon (a rectangle 3.f * 100.f) with a vanishing point for a road being at 3/4 height of the viewport and the nearest road edge as a viewport's bottom side. See Crazy Taxi game for an example of what I wish to do. I'm using iPhone SDK 3.1.2 default OpenGL ES project template. I setup the projection matrix as follows: glMatrixMode(GL_PROJECTION); glLoadIdentity(); glFrustumf(-2.25f, 2.25f, -1.5f, 1.5f, 0.1f, 1000.0f); Then I use glRotatef to adjust for landscape mode and setup camera. glMatrixMode(GL_MODELVIEW); glLoadIdentity(); glRotatef(-90, 0.0f, 0.0f, 1.0f); const float cameraAngle = 45.0f * M_PI / 180.0f; gluLookAt(0.0f, 2.0f, 0.0f, 0.0f, 0.0f, 100.0f, 0.0f, cos(cameraAngle), sin(cameraAngle)); My road polygon triangle strip is like this: static const GLfloat roadVertices[] = { -1.5f, 0.0f, 0.0f, 1.5f, 0.0f, 0.0f, -1.5f, 0.0f, 100.0f, 1.5f, 0.0f, 100.0f, }; And I can't seem to find the right parameters for gluLookAt. My vanishing point is always at the center of the screen.

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