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• [NHibernate and ASP.NET MVC] How can I implement a robust session-per-request pattern in my project,

  - by Guillaume Gervais

  I'm currently building an ASP.NET MVC project, with NHibernate as its persistance layer. For now, some functionnalities have been implemented, but only use local NHibernate sessions: each method that accessed the database (read or write) needs to instanciate its own NHibernate session, with the "using()" directive. The problem is that I want to leverage NHibernate's Lazy-Loading capabilities to improve the performance of my project. This implies an open NHibernate session per request until the view is rendered. Furthermore, simultaneous request must be supported (multiple Sessions at the same time). How can I achieve that as cleanly as possible? I searched the Web a little bit and learned about the session-per-request pattern. Most of the implementations I saw used some sort of Http* (HttpContext, etc.) object to store the session. Also, using the Application_BeginRequest/Application_EndRequest functions is complicated, since they get fired for each HTTP request (aspx files, css files, js files, etc.), when I only want to instanciate a session once per request. The concern that I have is that I don't want my views or controllers to have access to NHibernate sessions (or, more generally, NHibernate namespaces and code). That means that I do not want to handle sessions at the controller level nor the view one. I have a few options in mind. Which one seems the best ? Use interceptors (like in GRAILS) that get triggered before and after the controller action. These would open and close sessions/transactions. Is it possible in the ASP.NET MVC world? Use the CurrentSessionContext Singleton provided by NHibernate in a Web context. Using this page as an example, I think this is quite promising, but that still requires filters at the controller level. Use the HttpContext.Current.Items to store the request session. This, coupled with a few lines of code in Global.asax.cs, can easily provide me with a session on the request level. However, it means that dependencies will be injected between NHibernate and my views (HttpContext). Thank you very much!

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• NSNotifications vs delegate for multiple instances of same protocol

  - by Brent Traut

  I could use some architectural advice. I've run into the following problem a few times now and I've never found a truly elegant way to solve it. The issue, described at the highest level possible:I have a parent class that would like to act as the delegate for multiple children (all using the same protocol), but when the children call methods on the parent, the parent no longer knows which child is making the call. I would like to use loose coupling (delegates/protocols or notifications) rather than direct calls. I don't need multiple handlers, so notifications seem like they might be overkill. To illustrate the problem, let me try a super-simplified example: I start with a parent view controller (and corresponding view). I create three child views and insert each of them into the parent view. I would like the parent view controller to be notified whenever the user touches one of the children. There are a few options to notify the parent: Define a protocol. The parent implements the protocol and sets itself as the delegate to each of the children. When the user touches a child view, its view controller calls its delegate (the parent). In this case, the parent is notified that a view is touched, but it doesn't know which one. Not good enough. Same as #1, but define the methods in the protocol to also pass some sort of identifier. When the child tells its delegate that it was touched, it also passes a pointer to itself. This way, the parent know exactly which view was touched. It just seems really strange for an object to pass a reference to itself. Use NSNotifications. The parent defines a separate method for each of the three children and then subscribes to the "viewWasTouched" notification for each of the three children as the notification sender. The children don't need to attach themselves to the user dictionary, but they do need to send the notification with a pointer to themselves as the scope. Same as #4, but rather than using separate methods, the parent could just use one with a switch case or other branching along with the notification's sender to determine which path to take. Create multiple man-in-the-middle classes that act as the delegates to the child views and then call methods on the parent either with a pointer to the child or with some other differentiating factor. This approach doesn't seem scalable. Are any of these approaches considered best practice? I can't say for sure, but it feels like I'm missing something more obvious/elegant.

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• Create a Counter within a For-Loop?

  - by Todd Hartman

  I am a novice programmer and apologize upfront for the complicated question. I am trying to create a lexical decision task for experimental research, in which respondents must decide if a series of letters presented on the screen make a "word" or "not a word". Everything works reasonably well except for the bit where I want to randomly select a word (category A) or nonword (category B) for each of 80 trials from a separate input file (input.txt). The randomization works, but some elements from each list (category A or B) are skipped because I have used "round.catIndex = j;" where "j" is a loop for each successive trial. Because some trials randomly select from Category A and other from Category B, "j" does not move successively down the list for each category. Instead, elements from the Category A list may be selected from something like 1, 2, 5, 8, 9, 10, and so on (it varies each time because of the randomization). To make a long story short(!), how do I create a counter that will work within the for-loop for each trial, so that every word and nonword from Category A and B, respectively, will be used for the lexical decision task? Everything I have tried thus far does not work properly or breaks the javascript entirely. Below is my code snippet and the full code is available at http://50.17.194.59/LDT/trunk/LDT.js. Also, the full lexical decision task can be accessed at http://50.17.194.59/LDT/trunk/LDT.php. Thanks! function initRounds() { numlst = []; for (var k = 0; k<numrounds; k++) { if (k % 2 == 0) numlst[k] = 0; else numlst[k] = 1; } numlst.sort(function() {return 0.5 - Math.random()}) for (var j = 0; j<numrounds; j++) { var round = new LDTround(); if (numlst[j] == 0) { round.category = input.catA.datalabel; } else if (numlst[j] == 1) { round.category = input.catB.datalabel; } // pick a category & stimulus if (round.category == input.catA.datalabel) { round.itemtype = input.catA.itemtype; round.correct = 1; round.catIndex = j; } else if (round.category == input.catB.datalabel) { round.itemtype = input.catB.itemtype; round.correct = 2; round.catIndex = j; } roundArray[i].push(round); } return roundArray; }

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• How to reconcile my support of open-source software and need to feed and house myself?

  - by Guzba

  I have a bit of a dilemma and wanted to get some other developers' opinions on it and maybe some guidance. So I have created a 2D game for Android from the ground up, learning and re factoring as I went along. I did it for the experience, and have been proud of the results. I released it for free as ad supported with AdMob not really expecting much out of it, but curious to see what would happen. Its been a few of months now since release, and it has become very popular (250k downloads!). Additionally, the ad revenue is great and is driving me to make more good games and even allowing me to work less so that I can focus on my own works. When I originally began working on the game, I was pretty new to concurrency and completely new to Android (had Java experience though). The standard advice I got for starting an Android game was to look at the sample games from Google (Snake, Lunar Lander, ...) so I did. In my opinion, these Android sample games from Google are decent to see in general what your code should look like, but not actually all that great to follow. This is because some of their features don't work (saving game state), the concurrency is both unexplained and cumbersome (there is no real separation between the game thread and the UI thread since they sync lock each other out all the time and the UI thread runs game thread code). This made it difficult for me as a newbie to concurrency to understand how it was organized and what was really running what code. Here is my dilemma: After spending this past few months slowly improving my code, I feel that it could be very beneficial to developers who are in the same position that I was in when I started. (Since it is not a complex game, but clearly coded in my opinion.) I want to open up the source so that others can learn from it but don't want to lose my ad revenue stream, which, if I did open the source, I fear I would when people released versions with the ad stripped, or minor tweaks that would fragment my audience, etc. I am a CS undergrad major in college and this money is giving me the freedom to work less at summer job, thus giving me the time and will to work on more of my own projects and improving my own skills while still paying the bills. So what do I do? Open the source at personal sacrifice for the greater good, or keep it closed and be a sort of hypocritical supporter of open source?

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• Rendering problem with UITableview

  - by Spider-Paddy

  I have a very strange problem with a UITableview within a navigation controller on the iPhone simulator. Of the cells displayed, only some are correctly rendered. They are all supposed to look the same but the majority are missing the accessory I've set, scrolling the view changes which cell has the accessory so I suspect it's some sort of cell caching happening, although the contents are correct for each cell. I also set an image as the background and that was also only displaying sporadically but I fixed that by changing cell.backgroundView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"yellow-bar_short.png"]]; (which also only rendered a random cell with the background) to cell.backgroundColor = [[UIColor alloc] initWithPatternImage:[UIImage imageNamed:@"yellow-bar_short.png"]]; I now need to fix the problem with the accessory only showing on a random cell. I tried moving the code from cellForRowAtIndex to willDisplayCell but it made no difference. I put in a log command to confirm that it is running through each frame. Basically it's a table view (UITableViewCellStyleSubtitle) that gets its info from a server & is then updated by a delegate method calling reload. Code is: -(void)tableView:(UITableView *)tableView willDisplayCell:(UITableViewCell *)cell forRowAtIndexPath:(NSIndexPath *)indexPath { NSLog(@"%@", [NSString stringWithFormat:@"Setting colours for cell %i", indexPath.row]); // Set cell background // cell.backgroundView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"yellow-bar_short.png"]]; cell.backgroundColor = [[UIColor alloc] initWithPatternImage:[UIImage imageNamed:@"yellow-bar_short.png"]]; cell.textLabel.backgroundColor = [UIColor clearColor]; cell.detailTextLabel.backgroundColor = [UIColor clearColor]; // detailTableViewAccessory is a view containing an imageview in this view's nib // i.e. nib <- view <- imageview <- image cell.accessoryView = detailTableViewAccessory; } // Called by data fetching object when done -(void)listDataTransferComplete:(ArticleListParser *)articleListParserObject { NSLog(@"Data parsed, reloading detail table"); self.currentTotalResultPages = (((articleListParserObject.currentArticleCount - 1) / 10) + 1); self.detailTableDataSource = [articleListParserObject.returnedArray copy]; // make a local copy of the returned array // Render table again with returned array data (neither of these 2 fixed it) [self.detailTableView performSelectorOnMainThread:@selector(reloadData) withObject:nil waitUntilDone:NO]; // [self.detailTableView reloadData]; // Re-enable necessary buttons (including table cells) letUserSelectRow = TRUE; [btnByName setEnabled:TRUE]; [btnByPrice setEnabled:TRUE]; // Remove please wait message NSLog(@"Removing please wait view"); [pleaseWaitViewControllerObject.view removeFromSuperview]; } I only included code that I thought was relevant, can supply more if needed. I can't test it on an iPhone yet so I don't know if it's maybe just a simulator anomaly or a bug in my code. I've always gotten good feedback from questions, any ideas?

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• Is a Multi-DAL Approach the way to go here?

  - by Krisc

  Working on the data access / model layer in this little MVC2 project and trying to think things out to future projects. I have a database with some basic tables and I have classes in the model layer that represent them. I obviously need something to connect the two. The easiest is to provide some sort of 'provider' that can run operations on the database and return objects. But this is for a website that would potentially be used "a lot" (I know, very general) so I want to cache results from the data layer and keep the cache updated as new data is generated. This question deals with how best to approach this problem of dual DALS. One that returns cached data when possible and goes to the data layer when there is a cache miss. But more importantly, how to integrate the core provider (thing that goes into database) with the caching layer so that it too can rely on cached objects rather than creating new ones. Right now I have the following interfaces: IDataProvider is used to reach the database. It doesn't concern itself with the meaning of the objects it produces, but simply the way to produce them. interface IDataProvider{ // Select, Update, Create, et cetera access IEnumerable<Entry> GetEntries(); Entry GetEntryById(int id); } IDataManager is a layer that sits on top of the IDataProvider layer and manages the cache interface IDataManager : IDataProvider{ void ClearCache(); } Note that in practice the IDataManager implementation will have useful helper functions to add objects to their related cache stores. (In the future I may define other functions on the interface) I guess what I am looking for is the best way to approach a loop back from the IDataProvider implementations so that they can access the cache. Or a different approach entirely may be in order? I am not very interested in 3rd party products at the moment as I am interested in the design of these things much more than this specific implementation. Edit: I realize the title may be a bit misleading. I apologize for that... not sure what to call this question.

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• Dynamic Dispatch without Virtual Functions

  - by Kristopher Johnson

  I've got some legacy code that, instead of virtual functions, uses a kind field to do dynamic dispatch. It looks something like this: // Base struct shared by all subtypes // Plain-old data; can't use virtual functions struct POD { int kind; int GetFoo(); int GetBar(); int GetBaz(); int GetXyzzy(); }; enum Kind { Kind_Derived1, Kind_Derived2, Kind_Derived3 }; struct Derived1: POD { Derived1(): kind(Kind_Derived1) {} int GetFoo(); int GetBar(); int GetBaz(); int GetXyzzy(); // plus other type-specific data and function members }; struct Derived2: POD { Derived2(): kind(Kind_Derived2) {} int GetFoo(); int GetBar(); int GetBaz(); int GetXyzzy(); // plus other type-specific data and function members }; struct Derived3: POD { Derived3(): kind(Kind_Derived3) {} int GetFoo(); int GetBar(); int GetBaz(); int GetXyzzy(); // plus other type-specific data and function members }; and then the POD class's function members are implemented like this: int POD::GetFoo() { // Call kind-specific function switch (kind) { case Kind_Derived1: { Derived1 *pDerived1 = static_cast<Derived1*>(this); return pDerived1->GetFoo(); } case Kind_Derived2: { Derived2 *pDerived2 = static_cast<Derived2*>(this); return pDerived2->GetFoo(); } case Kind_Derived3: { Derived3 *pDerived3 = static_cast<Derived3*>(this); return pDerived3->GetFoo(); } default: throw UnknownKindException(kind, "GetFoo"); } } POD::GetBar(), POD::GetBaz(), POD::GetXyzzy(), and other members are implemented similarly. This example is simplified. The actual code has about a dozen different subtypes of POD, and a couple dozen methods. New subtypes of POD and new methods are added pretty frequently, and so every time we do that, we have to update all these switch statements. The typical way to handle this would be to declare the function members virtual in the POD class, but we can't do that because the objects reside in shared memory. There is a lot of code that depends on these structs being plain-old-data, so even if I could figure out some way to have virtual functions in shared-memory objects, I wouldn't want to do that. So, I'm looking for suggestions as to the best way to clean this up so that all the knowledge of how to call the subtype methods is centralized in one place, rather than scattered among a couple dozen switch statements in a couple dozen functions. What occurs to me is that I can create some sort of adapter class that wraps a POD and uses templates to minimize the redundancy. But before I start down that path, I'd like to know how others have dealt with this.

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• Using hidden values with jQuery (and ASP.NET MVC) -- not working?

  - by SlackerCoder

  Im using a couple of JSON calls to render data, etc etc. In order to keep the proper key value, I am storing it in a tag. I have this in several places in my code, none of which cause an issue like this one is. Here is the jQuery: The call that "sets" the value: $("a[id^='planSetupAddNewPlan']").live('click', function() { var x = $(this).attr('id'); x = x.substring(19); $("#hidPlanSetupCurrentGroupKey").val(x); $.getJSON("/GroupSetup/PlanSetupAddNewList", { GroupKey: x }, function(data) { $("#planSetupAddNew").html('' + data.TableResult + ''); alert('First Inside 2 ' + x); $.blockUI({ message: $("#planSetupAddNew") }); }); }); The call that "gets" the value: $("#ddlPlanSetupAddNewProduct").live('change', function() { var a = $("#hidPlanSetupCurrentGroupKey").val(); var prod = $(this).val(); alert(a); $.getJSON("/GroupSetup/PlanSetupChangePlanList", { GroupKey: a, Product: prod }, function(data) { if (data.Message == "Success") { $("#planSetupAddNewPlan").html('' + data.TableResult + ''); } else if (data.Message == "Error") { //Do something } }); }); Here is the html in question: <div id="planSetupAddNew" style="display:none; cursor: default;"> <input type="hidden" id="hidPlanSetupCurrentGroupKey" /> <div id="planSetupAddNewData"> </div> </div> In the first section, the alert ('First Inside 2 ' + x) returns what I expect (where x = the key value), and if I add a line to display the contents of the hidden field, that works as well: ie. var key = $("#hidPlanSetupCurrentGroupKey").val(); alert(key); In the "alert(a);" call, I am getting "undefined". I have looked at the other code in the same view and it is the same and it works. I must be missing something, or have some sort of mistype that I havent caught. Just an overview of the controller events: The first call (/GroupSetup/PlanSetupAddNewList) will return an html string building a "form" for users to enter information into. The second call (/GroupSetup/PlanSetupChangePlanList) just changes a second dropdown based on the first dropdown selection (overwriting the html in the div). If you need more info, let me know! Any thoughts/tips/pointers/suggestions?!?! Thanks for all your help :)

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• jQuery: load refuses to get dynamic content in IE6

  - by user260157

  jQuery refuses to load my dynamic content in IE6. All in FireFox & Safari works fine. Only IE6 is being a pain. When I try the a html with <p>Hello World</p> that works. Properly. But when loading a PHP it doesn't work! As you can see it's doing multiple things. <script type="text/javascript"> // When the document is ready set up our sortable with it's inherant function(s) $(document).ready(function() { // Sort list & amend in database function sortTableMenuAndReload() { var order = $('#menuList').sortable('serialize'); $.post("PLUGINS/SortableMenu/process-sortable.php",order); $("#menuList").load("PLUGINS/SortableMenu/sortableMenu_ajax.php"); } function sortTableOrder() { var order = $('#menuList').sortable('serialize'); $.post("PLUGINS/SortableMenu/process-sortable.php",order); } function sortTableOrderAndRemove(removeID) { $('#listItem_'+removeID).remove(); var order = $('#menuList').sortable('serialize'); $.post("PLUGINS/SortableMenu/process-sortable.php",order); $("#menuList").load("PLUGINS/SortableMenu/sortableMenu_ajax.php"); } $("#menuList > li > .remove").live('click', function () { var removeID = $(this).attr('id'); $.ajax({ type: 'post', url: 'PLUGINS/SortableMenu/removeLine.php', data: 'id='+removeID, success: sortTableOrderAndRemove(removeID) }); }); $("#menuList > li > .publish").live('click', function () { var publishID = $(this).attr('id'); $.ajax({ type: 'post', url: 'PLUGINS/SortableMenu/publishLine.php', data: 'id='+publishID, success: sortTableOrder }); }); $('#new_documents > li').draggable({ addClasses: false, helper:'clone', connectToSortable:'#menuList' }); $("#menuList").droppable({ addClasses: false, drop: function() { var clone = $("#menuList > li#newArticleTYPE1"); $(clone).attr("id","listItem_newArticleTYPE1"); } }); $("#menuList").sortable({ opacity: 0.6, handle : '.handle, .remove', update : sortTableMenuAndReload }); }); </script>

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• Android Thumbnail Loading Problem

  - by y ramesh rao

  I'm using a thumbnail loader in my project the one mentioned below. The problem is that the it loads all the thumbnails properly except the ones who's size is of about 40K. When our back end is giving that sort of thumbnails are not generated and sometimes this eventually leads to a Crash too. What m I supposed to do with this ? public class ThumbnailManager { private final Map<String, Bitmap> drawableMap; public static Context context; private Resources res; private int thumbnail_size; public ThumbnailManager() { drawableMap = new HashMap<String, Bitmap >(); res = new Resources(context.getAssets(), null, null); thumbnail_size = res.getInteger(R.ThumbnailManager.THUMBNAIL_SIZE); } public Bitmap fetchBitmap(String urlString) { if(drawableMap.containsKey(urlString)) { return (drawableMap.get(urlString)); } //Log.d(getClass().getSimpleName(), " Image URL :: "+ urlString); try { InputStream is = fetch(urlString); android.util.Log.v("ThumbnailManager", "ThumbnailManager " + urlString); drawableMap.put(urlString, BitmapFactory.decodeStream(is));//Bitmap.createScaledBitmap(BitmapFactory.decodeStream(is), thumbnail_size, thumbnail_size, false)); return drawableMap.get(urlString); } catch(Exception e) { android.util.Log.v("EXCEPTION", "EXCEPTION" + urlString); return null; } } public void fetchBitmapOnThread(final String urlString, final ImageView imageView) { if(drawableMap.containsKey(urlString)) { imageView.setImageBitmap(drawableMap.get(urlString)); return; } if(urlString.compareTo("AUDIO") == 0) { Bitmap audioThumb = BitmapFactory.decodeResource(context.getResources(), R.drawable.timeline_audio_thumb); drawableMap.put(urlString, Bitmap.createScaledBitmap(audioThumb, thumbnail_size, thumbnail_size, false)); imageView.setImageBitmap(drawableMap.get(urlString)); return; } final Handler handler = new Handler() { public void handleMessage(Message message) { imageView.setImageBitmap((Bitmap) message.obj); } }; Thread thread = new Thread() { public void run() { Bitmap urlBitmap = fetchBitmap(urlString); Message message = handler.obtainMessage(1, urlBitmap); handler.sendMessage(message); } }; thread.start(); } public InputStream fetch(String urlString) throws IOException, MalformedURLException { final URL url = new URL(urlString); final URLConnection conn = url.openConnection(); HttpURLConnection httpConn = (HttpURLConnection) conn; httpConn.setAllowUserInteraction(true); httpConn.setInstanceFollowRedirects(true); httpConn.setRequestMethod("GET"); httpConn.connect(); return(conn.getInputStream()); } }

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• Where are the function literals c++?

  - by academicRobot

  First of all, maybe literals is not the right term for this concept, but its the closest I could think of (not literals in the sense of functions as first class citizens). The idea is that when you make a conventional function call, it compiles to something like this: callq <immediate address> But if you make a function call using a function pointer, it compiles to something like this: mov <memory location>,%rax callq *%rax Which is all well and good. However, what if I'm writing a template library that requires a callback of some sort with a specified argument list and the user of the library is expected to know what function they want to call at compile time? Then I would like to write my template to accept a function literal as a template parameter. So, similar to template <int int_literal> struct my_template {...};` I'd like to write template <func_literal_t func_literal> struct my_template {...}; and have calls to func_literal within my_template compile to callq <immediate address>. Is there a facility in C++ for this, or a work around to achieve the same effect? If not, why not (e.g. some cataclysmic side effects)? How about C++0x or another language? Solutions that are not portable are fine. Solutions that include the use of member function pointers would be ideal. I'm not particularly interested in being told "You are a <socially unacceptable term for a person of low IQ>, just use function pointers/functors." This is a curiosity based question, and it seems that it might be useful in some (albeit limited) applications. It seems like this should be possible since function names are just placeholders for a (relative) memory address, so why not allow more liberal use (e.g. aliasing) of this placeholder. p.s. I use function pointers and functions objects all the the time and they are great. But this post got me thinking about the don't pay for what you don't use principle in relation to function calls, and it seems like forcing the use of function pointers or similar facility when the function is known at compile time is a violation of this principle, though a small one.

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• Webservice for uploading data: security considerations

  - by Philip Daubmeier

  Hi everyone! Im not sure about what authentification method I should use for my webservice. I've searched on SO, and found nothing that helped me. Preliminary Im building an application that uploads data from a local database to a server (running my webservice), where all records are merged and stored in a central database. I am currently binary serializing a DataTable, that holds a small fragment of the local database, where all uninteresting stuff is already filtered out. The byte[] (serialized DataTable), together with the userid and a hash of the users password is then uploaded to the webservice via SOAP. The application together with the webservice already work exactly like intended. The Problem The issue I am thinking about is now: What is if someone just sniffs the network traffic, 'steals' the users id and password hash to send his own SOAP message with modified data that corrupts my database? Options The approaches to solving that problem, I already thought of, are: Using ssl + certificates for establishing the connection: I dont really want to use ssl, I would prefer a simpler solution. After all, every information that is transfered to the webservice can be seen on the website later on. What I want to say is: there is no secret/financial/business-critical information, that has to be hidden. I think ssl would be sort of an overkill for that task. Encrypting the byte[]: I think that would be a performance killer, considering that the goal of the excercise was simply to authenticate the user. Hashing the users password together with the data: I kind of like the idea: Creating a checksum from the data, concatenating that checksum with the password-hash and hashing this whole thing again. That would assure the data was sent from this specific user, and the data wasnt modified. The actual question So, what do you think is the best approach in terms of meeting the following requirements? Rather simple solution (As it doesnt have to be super secure; no secret/business-critical information transfered) Easily implementable retrospectively (Dont want to write it all again :) ) Doesnt impact to much on performance What do you think of my prefered solution, the last one in the list above? Is there any alternative solution I didnt mention, that would fit better? You dont have to answer every question in detail. Just push me in the right direction. I very much appreciate every well-grounded opinion. Thanks in advance!

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• Force deletion of slot in boost::signals2

  - by villintehaspam

  Hi! I have found that boost::signals2 uses sort of a lazy deletion of connected slots, which makes it difficult to use connections as something that manages lifetimes of objects. I am looking for a way to force slots to be deleted directly when disconnected. Any ideas on how to work around the problem by designing my code differently are also appreciated! This is my scenario: I have a Command class responsible for doing something that takes time asynchronously, looking something like this (simplified): class ActualWorker { public: boost::signals2<void ()> OnWorkComplete; }; class Command : boost::enable_shared_from_this<Command> { public: ... void Execute() { m_WorkerConnection = m_MyWorker.OnWorkDone.connect(boost::bind(&Command::Handle_OnWorkComplete, shared_from_this()); // launch asynchronous work here and return } boost::signals2<void ()> OnComplete; private: void Handle_OnWorkComplete() { // get a shared_ptr to ourselves to make sure that we live through // this function but don't keep ourselves alive if an exception occurs. shared_ptr<Command> me = shared_from_this(); // Disconnect from the signal, ideally deleting the slot object m_WorkerConnection.disconnect(); OnComplete(); // the shared_ptr now goes out of scope, ideally deleting this } ActualWorker m_MyWorker; boost::signals2::connection m_WorkerConnection; }; The class is invoked about like this: ... boost::shared_ptr<Command> cmd(new Command); cmd->OnComplete.connect( foo ); cmd->Execute(); // now go do something else, forget all about the cmd variable etcetera. the Command class keeps itself alive by getting a shared_ptr to itself which is bound to the ActualWorker signal using boost::bind. When the worker completes, the handler in Command is invoked. Now, since I would like the Command object to be destroyed, I disconnect from the signal as can be seen in the code above. The problem is that the actual slot object is not deleted when disconnected, it is only marked as invalid and then deleted at a later time. This in turn appears to depend on the signal to fire again, which it doesn't do in my case, leading to the slot never expiring. The boost::bind object thus never goes out of scope, holding a shared_ptr to my object that will never get deleted. I can work around this by binding using the this pointer instead of a shared_ptr and then keeping my object alive using a member shared_ptr which I then release in the handler function, but it kind of makes the design feel a bit overcomplicated. Is there a way to force signals2 to delete the slot when disconnecting? Or is there something else I could do to simplify the design? Any comments are appreciated!

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• Iphone App deve- Very basic table view but getting errors , trying for 2 days!! just for info using

  - by user342451

  Hi guys, trying to write this code since 2 days now, but i keep getting error, it would be nice if anyone could sort this out, thanks. Basically its the same thing i doing from the tutorial on youtube. awaiting a reply // // BooksTableViewController.m // Mybooks // // import "BooksTableViewController.h" import "BooksDetailViewController.h" import "MYbooksAppDelegate.h" @implementation BooksTableViewController @synthesize BooksArray; @synthesize BooksDetailViewController; /* - (id)initWithStyle:(UITableViewCellStyle)style reuseIdentifier:(NSString *)reuseIdentifier { if ((self = [super initWithStyle:style reuseIdentifier:reuseIdentifier])) { // Initialization code } return self; } */ (void)viewDidLoad { [super viewDidLoad]; self.title = NSLocalizedString(@"XYZ",@"GOD is GREAT"); NSMutableArray *array = [[NSArray alloc] initWithObjects:@"H1",@"2",@"3",nil]; self.booksArray = array; [array release]; } /* // Override to allow orientations other than the default portrait orientation. - (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation { // Return YES for supported orientations return (interfaceOrientation == UIInterfaceOrientationPortrait); } */ (void)didReceiveMemoryWarning { [super didReceiveMemoryWarning]; // Releases the view if it doesn't have a superview // Release anything that's not essential, such as cached data } pragma mark Table view methods (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView { return 1; } // Customize the number of rows in the table view. - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section { return [self.booksArray count]; } // Customize the appearance of table view cells. - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { static NSString *identity = @"Cell"; UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:identity]; if (cell == nil) { cell = [[[UITableViewCell alloc] initWithFrame:CGRectZero reuseIdentifier:identity] autorelease]; } // Set up the cell... cell.textLabel.text = [booksArray objectAtIndex:indexPath.row]; return cell; } /* - (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath { booksDetailsViewControler *NC = [[booksDetailsViewControler alloc] initWithNibName:@"BooksDetailsView" bundle:nil]; [self.navigationController pushViewController:NC animated:YES]; //[booksDetailViewController changeProductText:[booksArray objectAtIndex:indexPath.row]]; } */ NSInteger row = [indexPath row]; if (self.booksDetailViewController == nil) { BooksiDetailViewController *aCellDetails = [[AartiDetailViewController alloc] initWithNibName:@" BooksDetailViewController" bundle:nil]; self.booksDetailViewController = aCellDetails; [aCellDetails release]; } booksDetailViewController.title = [NSString stringWithFormat:@"%@", [booksArray objectAtIndex:row]]; //DailyPoojaAppDelegate *delegate = [[UIApplication sharedApplication] delegate]; //[delegate.AartiNavController pushViewController:aartiDetailsViewControler animated:YES]; [self.navigationController pushViewController:aartiDetailViewController animated:YES]; } /* NSInteger row = [indexPath row]; if (self.booksDetailsViewControler == nil) { AartiDetailsViewControler *aBookDetail = [[BooksDetailsViewControler alloc] initWithNibName:@"booksDetaislView" bundle:nil]; self.booksDetailsViewControler = aBookDetail; [aBookDetail release]; } booksDetailsViewControler.title = [NSString stringWithFormat:@"%@", [booksArray objectAtIndex:row]]; [self.navigationController pushViewController:booksDetailsViewControler animated:YES]; */ (void)dealloc { [aartiDetailViewController release]; [super dealloc]; } @end

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• Getting HIERARCHY_REQUEST_ERR when using Javascript to recursively generate a nested list

  - by Mark

  I have a method that is trying to take in a list. This list can contain data and other lists. The end goal is to try to convert something like this ["a", "b", ["c", "d"]] into <ol> <li> <b>a</a> </li> <li> <b>b</a> </li> <ol> <li> <b>c</a> </li> <li> <b>d</a> </li> </ol> </ol> The code is: function $(tagName) { return document.createElement(tagName); } //returns an html element representing data //data should be an array or some sort of value function tagMaker(data) { tag = null; if(data instanceof Array) { //data is an array, represent using <ol> tag = $("ol"); for(i=0; i<data.length; i++) { //construct one <li> for each item in the array listItem = $("li"); //get the html element representing this particular item in the array child = tagMaker(data[i]); //<li>*html for child*</li> listItem.appendChild(child); //add this item to the list tag.appendChild(listItem); } } else { //data is not an array, represent using <b>data</b> tag = $("b"); tag.innerHTML = data.toString(); } return tag; } Calling tagMaker throws HIERARCHY_REQUEST_ERR: DOM Exception 3, rather than generating a helpful HTML element object which I was planning to append to document.body.

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• IE7 and IE8: Float clearing without adding empty elements

  - by tk-421

  Hello, I'm having a problem similar to the one described here (without a resolution): http://stackoverflow.com/questions/2467745/ie7-float-and-clear-on-the-same-element The following HTML renders as intended in Firefox but not in (both) IE7 and IE8: <html> <head> <style> ul { list-style-type: none; } li { clear: both; padding: 5px; } .left { clear: left; float: left; } .middle { clear: none; float: left; } .right { clear: right; float: left; } </style> </head> <body> <ul> <li>1</li> <li class="left">2</li> <li class="right">3</li> <li class="left">4</li> <li class="middle">5</li> <li class="right">6</li> <li>7</li> </ul> </body> </html> This is a form layout, and in Firefox the results appear like: 1 2 3 4 5 6 7 That's what I'm going for. In IE7 and IE8 however, the results are: 1 2 3 5 6 4 7 [Note: I don't want to float anything to the right because I want the fields on my form to left-align correctly, without a giant space in-between the floated fields to account for the parent container's width.] Apparently I need a full clear, and can probably add an empty list-item element to the list to force clearing, but that seems like a dumb solution and sort of defeats the purpose. Any ideas? I've spent a few hours reading and trying different options without success.

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• Replace text in XSL using wildcards

  - by JosephThomas

  This is similar to an earlier problem I was having which you guys solved in less than a day. I am working with XML files that are generated by a digital video camera. The camera allows the user to save all of the camera's settngs to an SD card so that the settings can be recalled or loaded into another camera. The XSL stylesheet I am writing will allow users to view the camera's settings, as saved to the SD card in a web browser. While most of the values in the XML file -- as formatted by my stylesheet -- make sense to humans, some do not. What I would like to do is have the stylesheet display text that is based on the value in the XML file but more easily understood by humans. A typical value that can be written to the XML file is "_23_970" which represents the camera's frame rate. This would be better displayed as 23.970 (or 023.970). The first underscore is a sort of place holder to make a space for values over 099.999. The second underscore, obviously represents the decimal. My previous (similar) question involved replacing predictable text, and the solution was matching templates. In this case, however, the camera can be set at any one of 119,999 frame rates (I think I did that math correctly). The approach, I would guess, is to pass a value to the displayed webpage that keeps the numeric values (each digit), replaces the second underscore with a decimal, and replaces the first underscore with either an nbsp or a zero (whichever is easier). If the first character in the string is a "1" (the camera can run at frame rates up to 120.000) then the one should be passed on to the page displayed by the stylesheet. I have read other posts here regarding wildcards, but couldn't find one that answered this question. EDIT: Sorry for leaving out important info. I fared better on my first try at asking a question! I guess I got complacent. Anyhow . . . I should have shown you the code that displays the text in the XSL file as is: <tr> <xsl:for-each select="Settings/Groups/Recording"> <tr><td class="title_column">Frame Rate</td><td><xsl:value-of select="RecOutLinkSpeed"/></td></tr> </xsl:for-each> </tr> I should also have given you the URL for the sample file I have been working with: http://josephthomas.info/Alexa/Setup_120511_140322.xml

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• Achieving C# "readonly" behavior in C++

  - by Tommy Fisk

  Hi guys, this is my first question on stack overflow, so be gentle. Let me first explain the exact behavior I would like to see. If you are familiar with C# then you know that declaring a variable as "readonly" allows a programmer to assign some value to that variable exactly once. Further attempts to modify the variable will result in an error. What I am after: I want to make sure that any and all single-ton classes I define can be predictably instantiated exactly once in my program (more details at the bottom). My approach to realizing my goal is to use extern to declare a global reference to the single-ton (which I will later instantiate at a time I choose. What I have sort of looks like this, namespace Global { extern Singleton& mainInstance; // not defined yet, but it will be later! } int main() { // now that the program has started, go ahead and create the singleton object Singleton& Global::mainInstance = Singleton::GetInstance(); // invalid use of qualified name Global::mainInstance = Singleton::GetInstance(); // doesn't work either :( } class Singleton { /* Some details ommited */ public: Singleton& GetInstance() { static Singleton instance; // exists once for the whole program return instance; } } However this does not really work, and I don't know where to go from here. Some details about what I'm up against: I'm concerned about threading as I am working on code that will deal with game logic while communicating with several third-party processes and other processes I will create. Eventually I would have to implement some kind of synchronization so multiple threads could access the information in the Singleton class without worry. Because I don't know what kinds of optimizations I might like to do, or exactly what threading entails (never done a real project using it), I was thinking that being able to predictably control when Singletons were instantiated would be a Good Thing. Imagine if Process A creates Process B, where B contains several Singletons distributed against multiple files and/or libraries. It could be a real nightmare if I can not reliably ensure the order these singleton objects are instantiated (because they could depend on each other, and calling methods on a NULL object is generally a Bad Thing). If I were in C# I would just use the readonly keyword, but is there any way I can implement this (compiler supported) behavior in C++? Is this even a good idea? Thanks for any feedback.

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• Database design advice needed.

  - by user346271

  Hi all, I'm a lone developer for a telecoms company, and am after some database design advice from anyone with a bit of time to answer. I am inserting into one table ~2 million rows each day, these tables then get archived and compressed on a monthly basis. Each monthly table contains ~15,000,000 rows. Although this is increasing month on month. For every insert I do above I am combining the data from rows which belong together and creating another "correlated" table. This table is currently not being archived, as I need to make sure I never miss an update to the correlated table. (Hope that makes sense) Although in general this information should remain fairly static after a couple of days of processing. All of the above is working perfectly. However my company now wishes to perform some stats against this data, and these tables are getting too large to provide the results in what would be deemed a reasonable time. Even with the appropriate indexes set. So I guess after all the above my question is quite simple. Should I write a script which groups the data from my correlated table into smaller tables. Or should I store the queries result sets in something like memcache? I'm already using mysqls cache, but due to having limited control over how long the data is stored for, it's not working ideally. The main advantages I can see of using something like memcache: No blocking on my correlated table after the query has been cashed. Greater flexibility of sharing the collected data between the backend collector and front end processor. (i.e custom reports could be written in the backend and the results of these stored in the cache under a key which then gets shared with anyone who would want to see the data of this report) Redundancy and scalability if we start sharing this data with a large amount of customers. The main disadvantages I can see of using something like memcache: Data is not persistent if machine is rebooted / cache is flushed. The main advantages of using MySql Persistent data. Less code changes (although adding something like memcache is trivial anyway) The main disadvantages of using MySql Have to define table templates every time I want to store provide a new set of grouped data. Have to write a program which loops through the correlated data and fills these new tables. Potentially will still grow slower as the data continues to be filled. Apologies for quite a long question. It's helped me to write down these thoughts here anyway, and any advice/help/experience with dealing with this sort of problem would be greatly appreciated. Many thanks. Alan

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• Is it a good or bad practice to call instance methods from a java constructor?

  - by Steve

  There are several different ways I can initialize complex objects (with injected dependencies and required set-up of injected members), are all seem reasonable, but have various advantages and disadvantages. I'll give a concrete example: final class MyClass { private final Dependency dependency; @Inject public MyClass(Dependency dependency) { this.dependency = dependency; dependency.addHandler(new Handler() { @Override void handle(int foo) { MyClass.this.doSomething(foo); } }); doSomething(0); } private void doSomething(int foo) { dependency.doSomethingElse(foo+1); } } As you can see, the constructor does 3 things, including calling an instance method. I've been told that calling instance methods from a constructor is unsafe because it circumvents the compiler's checks for uninitialized members. I.e. I could have called doSomething(0) before setting this.dependency, which would have compiled but not worked. What is the best way to refactor this? Make doSomething static and pass in the dependency explicitly? In my actual case I have three instance methods and three member fields that all depend on one another, so this seems like a lot of extra boilerplate to make all three of these static. Move the addHandler and doSomething into an @Inject public void init() method. While use with Guice will be transparent, it requires any manual construction to be sure to call init() or else the object won't be fully-functional if someone forgets. Also, this exposes more of the API, both of which seem like bad ideas. Wrap a nested class to keep the dependency to make sure it behaves properly without exposing additional API:class DependencyManager { private final Dependency dependency; public DependecyManager(Dependency dependency) { ... } public doSomething(int foo) { ... } } @Inject public MyClass(Dependency dependency) { DependencyManager manager = new DependencyManager(dependency); manager.doSomething(0); } This pulls instance methods out of all constructors, but generates an extra layer of classes, and when I already had inner and anonymous classes (e.g. that handler) it can become confusing - when I tried this I was told to move the DependencyManager to a separate file, which is also distasteful because it's now multiple files to do a single thing. So what is the preferred way to deal with this sort of situation?

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• Very basic table view but getting errors

  - by user342451

  Hi guys, trying to write this code since 2 days now, but i keep getting error, it would be nice if anyone could sort this out, thanks. Basically its the same thing i doing from the tutorial on youtube. awaiting a reply // // BooksTableViewController.m // Mybooks // // #import "BooksTableViewController.h" #import "BooksDetailViewController.h" #import "MYbooksAppDelegate.h" @implementation BooksTableViewController @synthesize BooksArray; @synthesize BooksDetailViewController; /* - (id)initWithStyle:(UITableViewCellStyle)style reuseIdentifier:(NSString *)reuseIdentifier { if ((self = [super initWithStyle:style reuseIdentifier:reuseIdentifier])) { // Initialization code } return self; } */ - (void)viewDidLoad { [super viewDidLoad]; self.title = NSLocalizedString(@"XYZ",@"GOD is GREAT"); NSMutableArray *array = [[NSArray alloc] initWithObjects:@"H1",@"2",@"3",nil]; self.booksArray = array; [array release]; } /* // Override to allow orientations other than the default portrait orientation. - (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation { // Return YES for supported orientations return (interfaceOrientation == UIInterfaceOrientationPortrait); } */ - (void)didReceiveMemoryWarning { [super didReceiveMemoryWarning]; // Releases the view if it doesn't have a superview // Release anything that's not essential, such as cached data } #pragma mark Table view methods - (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView { return 1; } // Customize the number of rows in the table view. - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section { return [self.booksArray count]; } // Customize the appearance of table view cells. - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { static NSString *identity = @"Cell"; UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:identity]; if (cell == nil) { cell = [[[UITableViewCell alloc] initWithFrame:CGRectZero reuseIdentifier:identity] autorelease]; } // Set up the cell... cell.textLabel.text = [booksArray objectAtIndex:indexPath.row]; return cell; } /* - (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath { booksDetailsViewControler *NC = [[booksDetailsViewControler alloc] initWithNibName:@"BooksDetailsView" bundle:nil]; [self.navigationController pushViewController:NC animated:YES]; //[booksDetailViewController changeProductText:[booksArray objectAtIndex:indexPath.row]]; } */ NSInteger row = [indexPath row]; if (self.booksDetailViewController == nil) { BooksiDetailViewController *aCellDetails = [[AartiDetailViewController alloc] initWithNibName:@" BooksDetailViewController" bundle:nil]; self.booksDetailViewController = aCellDetails; [aCellDetails release]; } booksDetailViewController.title = [NSString stringWithFormat:@"%@", [booksArray objectAtIndex:row]]; //DailyPoojaAppDelegate *delegate = [[UIApplication sharedApplication] delegate]; //[delegate.AartiNavController pushViewController:aartiDetailsViewControler animated:YES]; [self.navigationController pushViewController:aartiDetailViewController animated:YES]; } /* NSInteger row = [indexPath row]; if (self.booksDetailsViewControler == nil) { AartiDetailsViewControler *aBookDetail = [[BooksDetailsViewControler alloc] initWithNibName:@"booksDetaislView" bundle:nil]; self.booksDetailsViewControler = aBookDetail; [aBookDetail release]; } booksDetailsViewControler.title = [NSString stringWithFormat:@"%@", [booksArray objectAtIndex:row]]; [self.navigationController pushViewController:booksDetailsViewControler animated:YES]; */ - (void)dealloc { [aartiDetailViewController release]; [super dealloc]; } @end

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• What is wrong with this attempt of sending a break-signal?

  - by Jook

  I have quite a headache about this seemingly easy task: send a break signal to my device, like the wxTerm (or any similar Terminal application) does. This signal has to be 125ms long, according to my tests and the devices specification. It should result in a specific response, but what I get is a longer response than expected, and the transmitted date is false. e.g.: what it should respond 08 00 81 00 00 01 07 00 what it does respond 08 01 0A 0C 10 40 40 07 00 7F What really boggles me is, that after I have used wxTerm to look at my available com-ports (without connecting or sending anything), my code starts to work! I can send then as many breaks as I like, I get my response right from then on. I have to reset my PC in order to try it again. What the heck is going on here?! Here is my code for a reset through a break-signal: minicom_client(boost::asio::io_service& io_service, unsigned int baud, const string& device) : active_(true), io_service_(io_service), serialPort(io_service, device) { if (!serialPort.is_open()) { cerr << "Failed to open serial port\n"; return; } boost::asio::serial_port_base::flow_control FLOW( boost::asio::serial_port_base::flow_control::hardware ); boost::asio::serial_port_base::baud_rate baud_option(baud); serialPort.set_option(FLOW); serialPort.set_option(baud_option); read_start(); std::cout << SetCommBreak(serialPort.native_handle()) << std::endl; std::cout << GetLastError() << std::endl; boost::posix_time::ptime mst1 = boost::posix_time::microsec_clock::local_time(); boost::this_thread::sleep(boost::posix_time::millisec(125)); boost::posix_time::ptime mst2 = boost::posix_time::microsec_clock::local_time(); std::cout << ClearCommBreak(serialPort.native_handle()) << std::endl; std::cout << GetLastError() << std::endl; boost::posix_time::time_duration msdiff = mst2 - mst1; std::cout << msdiff.total_milliseconds() << std::endl; } Edit: It was only necessary to look at the combo-box selection of com-ports of wxTerm - no active connection was needed to be established in order to make my code work. I am guessing, that there is some sort of initialisation missing, which is done, when wxTerm is creating the list for the serial-port combo-box.

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• How to use unset() for this Linear Linked List in PHP

  - by Peter

  I'm writing a simple linear linked list implementation in PHP. This is basically just for practice... part of a Project Euler problem. I'm not sure if I should be using unset() to help in garbage collection in order to avoid memory leaks. Should I include an unset() for head and temp in the destructor of LLL? I understand that I'll use unset() to delete nodes when I want, but is unset() necessary for general clean up at any point? Is the memory map freed once the script terminates even if you don't use unset()? I saw this SO question, but I'm still a little unclear. Is the answer that you simply don't have to use unset() to avoid any sort of memory leaks associated with creating references? I'm using PHP 5.. btw. Unsetting references in PHP PHP references tutorial Here is the code - I'm creating references when I create $temp and $this-head at certain points in the LLL class: class Node { public $data; public $next; } class LLL { // The first node private $head; public function __construct() { $this->head = NULL; } public function insertFirst($data) { if (!$this->head) { // Create the head $this->head = new Node; $temp =& $this->head; $temp->data = $data; $temp->next = NULL; } else { // Add a node, and make it the new head. $temp = new Node; $temp->next = $this->head; $temp->data = $data; $this->head =& $temp; } } public function showAll() { echo "The linear linked list:<br/>&nbsp;&nbsp;"; if ($this->head) { $temp =& $this->head; do { echo $temp->data . " "; } while ($temp =& $temp->next); } else { echo "is empty."; } echo "<br/>"; } } Thanks!

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• Defined variables and arrays vs functions in php

  - by Frank Presencia Fandos

  Introduction I have some sort of values that I might want to access several times each page is loaded. I can take two different approaches for accessing them but I'm not sure which one is 'better'. Three already implemented examples are several options for the Language, URI and displaying text that I describe here: Language Right now it is configured in this way: lang() is a function that returns different values depending on the argument. Example: lang("full") returns the current language, "English", while lang() returns the abbreviation of the current language, "en". There are many more options, like lang("select"), lang("selectact"), etc that return different things. The code is too long and irrelevant for the case so if anyone wants it just ask for it. Url The $Url array also returns different values depending on the request. The whole array is fully defined in the beginning of the page and used to get shorter but accurate links of the current page. Example: $Url['full'] would return "http://mypage.org/path/to/file.php?page=1" and $Url['file'] would return "file.php". It's useful for action="" within the forms and many other things. There are more values for $Url['folder'], $Url['file'], etc. Same thing about the code, if wanted, just request it. Text [You can skip this section] There's another array called $Text that is defined in the same way than $Url. The whole array is defined at the beginning, making a mysql call and defining all $Text[$i] for current page with a while loop. I'm not sure if this is more efficient than multiple calls for a single mysql cell. Example: $Text['54'] returns "This is just a test array!" which this could perfectly be implemented with a function like text(54). Question With the 3 examples you can see that I use different methods to do almost the same function (no pun intended), but I'm not sure which one should become the standard one for my code. I could create a function called url() and other called text() to output what I want. I think that working with functions in those cases is better, but I'm not sure why. So I'd really appreciate your opinions and advice. Should I mix arrays and functions in the way I described or should I just use funcions? Please, base your answer in this: The source needs to be readable and reusable by other developers Resource consumption (processing, time and memory). The shorter the code the better. The more you explain the reasons the better. Thank you PS, now I know the differences between $Url and $Uri.

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• How do I go about link web content in a database with a nested set model?

  - by wb

  My nested set table is as follows. create table depts ( id int identity(0, 1) primary key , lft int , rgt int , name nvarchar(60) , abbrv nvarchar(20) ); Test departments. insert into depts (lft, rgt, name, abbrv) values (1, 14, 'root', 'r'); insert into depts (lft, rgt, name, abbrv) values (2, 3, 'department 1', 'd1'); insert into depts (lft, rgt, name, abbrv) values (4, 5, 'department 2', 'd2'); insert into depts (lft, rgt, name, abbrv) values (6, 13, 'department 3', 'd3'); insert into depts (lft, rgt, name, abbrv) values (7, 8, 'sub department 3.1', 'd3.1'); insert into depts (lft, rgt, name, abbrv) values (9, 12, 'sub department 3.2', 'd3.2'); insert into depts (lft, rgt, name, abbrv) values (10, 11, 'sub sub department 3.2.1', 'd3.2.1'); My web content table is as follows. create table content ( id int identity(0, 1) , dept_id int , page_name nvarchar(60) , content ntext ); Test content. insert into content (dept_id, page_name, content) values (3, 'index', '<h2>welcome to department 3!</h2>'); insert into content (dept_id, page_name, content) values (4, 'index', '<h2>welcome to department 3.1!</h2>'); insert into content (dept_id, page_name, content) values (6, 'index', '<h2>welcome to department 3.2.1!</h2>'); insert into content (dept_id, page_name, content) values (2, 'what-doing', '<h2>what is department 2 doing?/h2>'); I'm trying to query the correct page content (from the content table) based on the url given. I can easily accomplish this task with a root department. However, querying a department with multiple depths is proving to be a little harder. For example: http://localhost/departments.asp?d3/ (Should return <h2>welcome to department 3!</h2>) http://localhost/departments.asp?d2/what-doing (Should return <h2>what is department 2 doing?</h2>) I'm not sure if this can be create in one query or if there will need to be a recursive function of some sort. Also, if there is nothing after the last / then assume we want the index page. How can this be accomplished? Thank you.

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