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• Recommendations for a free GIS library supporting raster images

  - by gspr

  Hi. I'm quite new to the whole field of GIS, and I'm about to make a small program that essentially overlays GPS tracks on a map together with some other annotations. I primarily need to allow scanned (thus raster) maps (although it would be nice to support proper map formats and something like OpenStreetmap in the long run). My first exploratory program uses Qt's graphics view framework and overlays the GPS points by simply projecting them onto the tangent plane to the WGS84 ellipsoid at a calibration point. This gives half-decent accuracy, and actually looks good. But then I started wondering. To get the accuracy I need (i.e. remove the "half" in "half-decent"), I have to correct for the map projection. While the math is not a problem in itself, supporting many map projection feels like needless work. Even though a few projections would probably be enough, I started thinking about just using something like the PROJ.4 library to do my projections. But then, why not take it all the way? Perhaps I might aswell use a full-blown map library such as Mapnik (edit: Quantum GIS also looks very nice), which will probably pay off when I start to want even more fancy annotations or some other symptom of featuritis. So, finally, to the question: What would you do? Would you use a full-blown map library? If so, which one? Again, it's important that it supports using (and zooming in and out with) raster maps and has pretty overlay features. Or would you just keep it simple, and go with Qt's own graphics view framework together with something like PROJ.4 to handle the map projections? I appreciate any feedback! Some technicalities: I'm writing in C++ with a Qt-based GUI, so I'd prefer something that plays relatively nicely with those. Also, the library must be free software (as in FOSS), and at least decently cross-platform (GNU/Linux, Windows and Mac, at least). Edit: OK, it seems I didn't do quite enough research before asking this question. Both Quantum GIS and Mapnik seem very well suited for my purpose. The former especially so since it's based on Qt.

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• ArithmeticException thrown during BigDecimal.divide

  - by polygenelubricants

  I thought java.math.BigDecimal is supposed to be The Answer™ to the need of performing infinite precision arithmetic with decimal numbers. Consider the following snippet: import java.math.BigDecimal; //... final BigDecimal one = BigDecimal.ONE; final BigDecimal three = BigDecimal.valueOf(3); final BigDecimal third = one.divide(three); assert third.multiply(three).equals(one); // this should pass, right? I expect the assert to pass, but in fact the execution doesn't even get there: one.divide(three) causes ArithmeticException to be thrown! Exception in thread "main" java.lang.ArithmeticException: Non-terminating decimal expansion; no exact representable decimal result. at java.math.BigDecimal.divide It turns out that this behavior is explicitly documented in the API: In the case of divide, the exact quotient could have an infinitely long decimal expansion; for example, 1 divided by 3. If the quotient has a non-terminating decimal expansion and the operation is specified to return an exact result, an ArithmeticException is thrown. Otherwise, the exact result of the division is returned, as done for other operations. Browsing around the API further, one finds that in fact there are various overloads of divide that performs inexact division, i.e.: final BigDecimal third = one.divide(three, 33, RoundingMode.DOWN); System.out.println(three.multiply(third)); // prints "0.999999999999999999999999999999999" Of course, the obvious question now is "What's the point???". I thought BigDecimal is the solution when we need exact arithmetic, e.g. for financial calculations. If we can't even divide exactly, then how useful can this be? Does it actually serve a general purpose, or is it only useful in a very niche application where you fortunately just don't need to divide at all? If this is not the right answer, what CAN we use for exact division in financial calculation? (I mean, I don't have a finance major, but they still use division, right???).

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• With EJB 2.1, is declaring references to resources in ejb-jar.xml required?

  - by zwerd328

  I'm using Weblogic 9.2 with a lot of MDBs. These MDBs access JDBC DataSources and write to both locally and externally managed JMS Destinations using local and foreign XAConnectionFactorys, respectively. Each MDB demarcates a container-managed JTA transaction that should be distributed amongst all of these resources. Below is an excerpt from my ejb-jar.xml for an MDB that consumes from a local Queue called "MyDestination" and produces to an IBM Websphere MQ Queue called "MyOtherDestination". These logical names are linked to physical objects in my weblogic-ejb-jar.xml file. Is it required to use the <resource-ref> and <message-destination-ref> tags to expose the ConnectionFactory and Queue to the MDB? If so, is it required by Weblogic or is it required by the J2EE spec? And for what purpose? For example, is it required to support XA transactionality? I'm already aware of the benefit of decoupling the administered objects from my MDB using names exposed to the naming context of the MDB. Is this the only value added when specifying these tags? In other words, is it acceptable to just reference these objects from my MDB using the InitialContext and the objects' fully-qualified names? <enterprise-bean> <message-driven> <ejb-name>MyMDB</ejb-name> <ejb-class>com.mycompany.MyMessageDrivenBean</ejb-class> <transaction-type>Container</transaction-type> <message-destination-type>javax.jms.Queue</message-destination> <message-destination-link>MyDestination</message-destination-link> <resource-ref> <res-ref-name>jms/myQCF</res-ref-name> <res-type>javax.jms.XAConnectionFactory</res-type> <res-auth>Container</res-auth> </resource-ref> <message-destination-ref> <message-destination-ref-name>jms/myOtherDestination</message-destination-ref-name> <message-destination-type>javax.jms.Queue</message-destination-type> <message-destination-usage>Produces</message-destination-usage> <message-destination-link>MyOtherDestination</message-destination-link> </message-destination-ref> </message-driven> <enterprise-bean>

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• How to initiate chatting between two clients and two clients only, using applets and servlets?

  - by mithun1538

  Hello everyone, I first need to apologize for my earlier questions. (You can check my profile for them)They seemed to ask more questions than give answers. Hence, I am laying down the actual question that started all them absurd questions. I am trying to design a chat applet. Till now, I have coded the applet, servlet and communication between the applet and the servlet. The code in the servlet side is such that I was able to establish chatting between clients using the applets, but the code was more like a broadcast all feature, i.e. all clients would be chatting with each other. That was my first objective when I started designing the chat applet. The second step is chatting between only two specific users, much like any other chat application we have. So this was my idea for it: I create an instance of the servlet that has the 'broadcast-all' code. I then pass the address of this instance to the respective clients. 2 client applets use the address to then chat. Technically the code is 'broadcast-all', but since only 2 clients are connected to it, it gives the chatting between two clients feature. Thus, groups of 2 clients have different instances of the same servlet, and each instance handles chatting between two clients at a max. However, as predicted, the idea didn't materialize! I tried to create an instance of the servlet but the only solution for that was using sessions on the servlet side, and I don't know how to use this session for later communications. I then tried to modify my broadcast-all code. In that code, I was using classes that implemented Observer and Observable interfaces. So the next idea that I got was: Create a new object of the Observable class(say class_1). This object be common to 2 clients. 2 clients that wish to chat will use same object of the class_1. 2 other clients will use a different object of class_1. But the problem here lies with the class that implements the Observer interface(say class_2). Since this has observers monitoring the same type of class, namely class_1, how do I establish an observer monitoring one object of class_1 and another observer monitoring another object of the same class class_1 (Because notifyObservers() would notify all the observers and I can't assign a particular observer to a particular object)? I first decided to ask individual problems, like how to create instances of servlets, using objects of observable and observer and so on in stackoverflow... but I got confused even more. Can anyone give me an idea how to establish chatting between two clients only?(I am using Http and not sockets or RMI). Regards, Mithun. P.S. Thanks to all who replied to my previous (absurd) queries. I should have stated the purpose earlier so that you guys could help me better.

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• Why does my ko computed observable not update bound UI elements when its value changes?

  - by Allen

  I'm trying to wrap a cookie in a computed observable (which I'll later turn into a protectedObservable) and I'm having some problems with the computed observable. I was under the opinion that changes to the computed observable would be broadcast to any UI elements that have been bound to it. I've created the following fiddle JavaScript: var viewModel = {}; // simulating a cookie store, this part isnt as important var cookie = function () { // simulating a value stored in cookies var privateZipcode = "12345"; return { 'write' : function (val) { privateZipcode = val; }, 'read': function () { return privateZipcode; } } }(); viewModel.zipcode = ko.computed({ read: function () { return cookie.read(); }, write: function (value) { cookie.write(value); }, owner: viewModel }); ko.applyBindings(viewModel);? HTML: zipcode: <input type='text' data-bind="value: zipcode"> <br /> zipcode: <span data-bind="text: zipcode"></span>? I'm not using an observable to store privateZipcode since that's really just going to be in a cookie. I'm hoping that the ko.computed will provide the notifications and binding functionality that I need, though most of the examples I've seen with ko.computed end up using a ko.observable underneath the covers. Shouldn't the act of writing the value to my computed observable signal the UI elements that are bound to its value? Shouldn't these just update? Workaround I've got a simple workaround where I just use a ko.observable along side of my cookie store and using that will trigger the required updates to my DOM elements but this seems completely unnecessary, unless ko.computed lacks the signaling / dependency type functionality that ko.observable has. My workaround fiddle, you'll notice that the only thing that changes is that I added a seperateObservable that isn't used as a store, its only purpose is to signal to the UI that the underlying data has changed. // simulating a cookie store, this part isnt as important var cookie = function () { // simulating a value stored in cookies var privateZipcode = "12345"; // extra observable that isnt really used as a store, just to trigger updates to the UI var seperateObservable = ko.observable(privateZipcode); return { 'write' : function (val) { privateZipcode = val; seperateObservable(val); }, 'read': function () { seperateObservable(); return privateZipcode; } } }(); This makes sense and works as I'd expect because viewModel.zipcode depends on seperateObservable and updates to that should (and does) signal the UI to update. What I don't understand, is why doesn't a call to the write function on my ko.computed signal the UI to update, since that element is bound to that ko.computed? I suspected that I might have to use something in knockout to manually signal that my ko.computed has been updated, and I'm fine with that, that makes sense. I just haven't been able to find a way to accomplish that.

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• Time required for a process to complete

  - by yelkawar

  I am new to C# world. I am attempting to calculate time taken by a algorithum for the purpose of comparison. Following code measures the elapsed time from when a subroutine is called until the subroutine returns to the main program.This example is taken from "Data structures through C#" by Michael McMillan. After running this program the output is Time=0, which is incorrect. The program appears to be logically correct. Can anybody help me. Following is the code using System.Collections.Generic; using System.Collections; using System.Linq; using System.Text; namespace Chap1 { class Program { static void Main(string[] args) { int num1 = 100; int num2 = 200; Console.WriteLine("num1: " + num1); Console.WriteLine("num2: " + num2); Swap<int>(ref num1, ref num2); Console.WriteLine("num1: " + num1); Console.WriteLine("num2: " + num2); string str1 = "Sam"; string str2 = "Tom"; Console.WriteLine("String 1: " + str1); Console.WriteLine("String 2: " + str2); Swap<string>(ref str1, ref str2); Console.WriteLine("String 1: " + str1); Console.WriteLine("String 2: " + str2); Console.ReadKey(); } static void Swap<T>(ref T val1, ref T val2) { T temp; temp = val1; val1 = val2; val2 = temp; } } class Timing { TimeSpan StartTiming; TimeSpan duration; public Timing() { StartTiming = new TimeSpan(0); duration = new TimeSpan(0); } public TimeSpan startTime() { GC.Collect(); GC.WaitForPendingFinalizers(); StartTiming = Process.GetCurrentProcess().Threads[0].UserProcessorTime; return StartTiming; } public void stopTime() { duration = Process.GetCurrentProcess().Threads[0].UserProcessorTime.Subtract(StartTiming); } public TimeSpan result() { return duration; } } }

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• Feeding PDF through IInternetSession to WebBrowser control - Error

  - by Codesleuth

  As related to my previous question, I have developed a temporary asynchronous pluggable protocol with the specific aim to be able to serve PDF documents directly to a WebBrowser control via a database. I need to do this because my limitations include not being able to access the disk other than IsolatedStorage; and a MemoryStream would be far better for serving up PDF documents that average around 31kb. Unfortunately the code doesn't work, and I'm getting an error from the WebBrowser control (i.e. IE): Unable to download . Unable to open this Internet site. The requested site is either unavailable or cannot be found. Please try again later. The line in my code where this occurs is within the following: pOIProtSink.ReportData(BSCF.BSCF_LASTDATANOTIFICATION, (uint)_stream.Length, (uint)_stream.Length); However, if you download the project and run it, you will be able to see the stream is successfully read and passed to the browser, so it seems like there's a problem somewhere to do with the end of reading the data: public uint Read(IntPtr pv, uint cb, out uint pcbRead) { var bytesToRead = Math.Min(cb, _streamBuffer.Length); pcbRead = (uint)_stream.Read(_streamBuffer, 0, (int)bytesToRead); Marshal.Copy(_streamBuffer, 0, pv, (int)pcbRead); return (pcbRead == 0 || pcbRead < cb) ? HRESULT.S_FALSE : HRESULT.S_OK; } Here is the entire sample project: InternetSessionSample.zip (VS2010) I will leave this up for as long as I can to help other people in the future If anyone has any ideas why I might be getting this message and can shed some light on the problem, I would be grateful for the assistance. EDIT: A friend suggested inserting a line that calls the IInternetProtocolSink.ReportProgress with BINDSTATUS_CACHEFILENAMEAVAILABLE pointing at the original file. This prevents it from failing now and shows the PDF in the Adobe Reader control, but means it defeats the purpose of this by having Adobe Reader simply load from the cache file (which I can't provide). See below: pOIProtSink.ReportProgress(BINDSTATUS.BINDSTATUS_CACHEFILENAMEAVAILABLE, @"D:\Visual Studio Solutions\Projects\InternetSessionSample\bin\Debug\sample.pdf"); pOIProtSink.ReportData(BSCF.BSCF_LASTDATANOTIFICATION, (uint)_stream.Length, (uint)_stream.Length); This is progress though, I guess.

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• What benefits are there to storing Javascript in external files vs in the <head>?

  - by RenderIn

  I have an Ajax-enabled CRUD application. If I display a record from my database it shows that record's values for each column, including its primary key. For the Ajax actions tied to buttons on the page I am able to set up their calls by printing the ID directly into their onclick functions when rendering the HTML server-side. For example, to save changes to the record I may have a button as follows, with '123' being the primary key of the record. <button type="button" onclick="saveRecord('123')">Save</button> Sometimes I have pages with Javascript generating HTML and Javascript. In some of these cases the primary key is not naturally available at that place in the code. In these cases I took a shortcut and generate buttons like so, taking the primary key from a place it happens to be displayed on screen for visual consumption: ... <td>Primary Key: </td> <td><span id="PRIM_KEY">123</span></td> ... <button type="button" onclick="saveRecord(jQuery('#PRIM_KEY').text())">DoSomething</button> This definitely works, but it seems wrong to drive database queries based on the value of text whose purpose was user consumption rather than method consumption. I could solve this by adding a series of additional parameters to various methods to usher the primary key along until it is eventually needed, but that also seems clunky. The most natural way for me to solve this problem would be to simply situate all the Javascript which currently lives in external files, in the <head> of the page. In that way I could generate custom Javascript methods without having to pass around as many parameters. Other than readability, I'm struggling to see what benefit there is to storing Javascript externally. It seems like it makes the already weak marriage between HTML/DOM and Javascript all the more distant. I've seen some people suggest that I leave the Javascript external, but do set various "custom" variables on the page itself, for example, in PHP: <script type="text/javascript"> var primaryKey = <?php print $primaryKey; ?>; </script> <script type="text/javascript" src="my-external-js-file-depending-on-primaryKey-being-set.js"></script> How is this any better than just putting all the Javascript on the page in the first place? There HTML and Javascript are still strongly dependent on each other.

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• Repeating fields in similar database tables

  - by user1738833

  I have been tasked with working on a database that I have never seen before and I'm looking at the DB structure. Some of the central and most heavily queried and joined tables look like virtual duplicates of each other. Here's a massively simplified representation of the situation, with business-sensitive information changed, listing hypothetical table names and fields: TopLevelGroup: PK_TLGroupId, DisplaysXOnBill, DisplaysYOnBill, IsInvoicedForJ, IsInvoicedForK SubGroup: PK_SubGroupId, FK_ParentTopLevelGroupId, DisplaysXOnBill, DisplaysYOnBill, IsInvoicedForJ, IsInvoicedForK SubSubGroup: PK_SubSUbGroupId, FK_ParentSubGroupId, DisplaysXOnBill, DisplaysYOnBill, IsInvoicedForJ, IsInvoicedForK I haven't listed the types of the fields as I don't think it's particularly important to the situation. In addition, it's worth saying that rather than four repeated fields as in the example above, I'm looking at 86 repeated fields. For the most part, those fields genuinely do represent "facts" about the primary table entity, so it's not automatically wrong for that reason. In addition, the "groups" represented here have a property inheritance relationship. If DisplaysXOnBill is NULL in the SubSubGroup, it takes the value of DisplaysXOnBillfrom it's parent, the SubGroup, and so-on up to the TopLevelGroup. Further, the requirements will never require that the model extends beyond three levels, so there is no need for flexibility in that area. Is there a design smell from several tables which describe very similar entities having almost identical fields? If so, what might be a better design of the example above? I'm using the phrase "design smell" to indicate a possible problem. Of course, in any given situation, a particular design might well be the best solution. I'm looking for a more general answer - wondering what might be wrong with this design and what might be the better design were that the case. Possibly related, but not primary questions: Is this database schema in a reasonably normal form (e.g. to 3NF), insofar as can be told from the information I've provided. I can't see a problem with the requirements of 2NF and 3NF, except in their inheriting the requirements of 1NF. Is 1NF satisfied though? Are repeating groups allowed in different tables? Is there a best-practice method for implementing the inheritance relationship in a database as I require? The method above feels clunky to me because any query on the SubSubGroup necessarily needs to join onto the SubGroup and the TopLevelGroup tables to collect inherited facts, which can make even trivial joins requiring facts from the SubSubGroup table rather long-winded. There are, of course, political considerations to making a relatively large change like this. For the purpose of this question, I'm happy to ignore that fact in the interests of keeping the answers ring-fenced to the technical problem.

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• JAVA - Strange problem (probably thread problem) with JTable & Model

  - by Stefanos Kargas

  I am using 2 Tables (JTable) with their DefaultTableModels. The first table is already populated. The second table is populated for each row of the first table (using an SQL Query). My purpose is to export every line of the first table with it's respective lines of the second in an Excel File. I am doing it with a for (for each line of 1st table), in which I write a line of the 1st table in the Excel File, then I populate the 2nd table (for this line of 1st Table), I get every line from the Table (from it's Model actually) and put it in the Excel File under the current line of 1st table. This means that if I have n lines in first table I will clear and populate again the second table n times. All this code is called in a seperate thread. THE PROBLEM IS: Everything works perfectly fine ecxept that I am getting some exceptions. The strange thing is that I'm not getting anything false in my result. The Excel file is perfect. Some of the lines of the exceptions are: Exception in thread "AWT-EventQueue-0" java.lang.ArrayIndexOutOfBoundsException: 0 = 0 at java.util.Vector.elementAt(Vector.java:427) at javax.swing.table.DefaultTableModel.getValueAt(DefaultTableModel.java:632) at javax.swing.JComponent.paint(JComponent.java:1017) at javax.swing.RepaintManager.paint(RepaintManager.java:1220) at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:803) I am assuming that the problem lies in the fact that the second table needs some more time to be populated before I try to get any data from it. That's why I see RepaintManager and paintDirtyRegions in my exceptions. Another thing I did is that I ran my program in debug mode and I put a breakpoint after each population of the 2nd table. Then I pressed F5 to continue for each population of 2nd table and no exception appeared. The program came to it's end without any exceptions. This is another important fact that tells me that maybe in this case I gave the table enough time to be populated. Of course you will ask me: If your program works fine, why do you care about the exceptions? I care for avoiding any future problems and I care to have a better understanding of Java and Java GUI and threads. Why do you depend on a GUI component (and it's model) to get your information and why don't you recreate the resultset that populates your tables using an SQL Query and get your info from the resultset? That would be the best and the right way. The fact is that I have the tables code ready and it was easier for me to just get the info from them. But the right way would be to get everything direct from database. Anyway what I did brought out my question, and answering it would help me understand more things about java. So I posted it.

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• using '.each' method: how do I get the indexes of multiple ordered lists to each begin at [0]?

  - by shecky

  I've got multiple divs, each with an ordered list (various lengths). I'm using jquery to add a class to each list item according to its index (for the purpose of columnizing portions of each list). What I have so far ... <script type="text/javascript"> /* Objective: columnize list items from a single ul or ol in a pre-determined number of columns 1. get the index of each list item 2. assign column class according to li's index */ $(document).ready(function() { $('ol li').each(function(index){ // assign class according to li's index ... index = li number -1: 1-6 = 0-5; 7-12 = 6-11, etc. if ( index <= 5 ) { $(this).addClass('column-1'); } if ( index > 5 && index < 12 ) { $(this).addClass('column-2'); } if ( index > 11 ) { $(this).addClass('column-3'); } // add another class to the first list item in each column $('ol li').filter(function(index) { return index != 0 && index % 6 == 0; }).addClass('reset'); }); // closes li .each func }); // closes doc.ready.func </script> ... succeeds if there's only one list; when there are additional lists, the last column class ('column-3') is added to all remaining list items on the page. In other words, the script is presently indexing continuously through all subsequent lists/list items, rather than being re-set to [0] for each ordered list. Can someone please show me the proper method/syntax to correct/amend this, so that the script addresses/indexes each ordered list anew? many thanks in advance. shecky p.s. the markup is pretty straight-up: <div class="tertiary"> <h1>header</h1> <ol> <li><a href="#" title="a link">a link</a></li> <li><a href="#" title="a link">a link</a></li> <li><a href="#" title="a link">a link</a></li> </ol> </div><!-- END div class="tertiary" -->

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• Array within Form collecting multiple values with the same name possible?

  - by JM4

  Good afternoon, I will first start with the goal I am trying to accomplish and then give a very basic sample of what I need to do. Goal Instead of collecting several variables and naming them with keys individually, I have decided to give in and use an array structure to handle all inputs of the same type and rules. Once I have the variables, I will validate against them and if 'ok' store them in a MySQL table. The table will hold consumer information and will need to store multiple rows of the same type of information. First Pass I will leave out the validation portion of this question because I feel I need to first understand the basics. <form action="?" method="POST" name="Form"> Member 1 First Name:<input type="text" name="MemberFirstName[]" /><br /> Member 1 Last Name: <input type="text" name="MemberLastName[]" /><br /> Member 1 Email: <input type="text" name="MemberEmail[]" /><br /> Member 2 First Name:<input type="text" name="MemberFirstName[]" /><br /> Member 2 Last Name: <input type="text" name="MemberLastName[]" /><br /> Member 2 Email: <input type="text" name="MemberEmail[]" /><br /> Member 3 First Name:<input type="text" name="MemberFirstName[]" /><br /> Member 3 Last Name: <input type="text" name="MemberLastName[]" /><br /> Member 3 Email: <input type="text" name="MemberEmail[]" /><br /> <input type="submit" name="submit" value="Continue" /> </form> I am hoping that each input given for First Name (a required field) will generate a unique key for that particular entry and not overwrite any data entered. Because I am carrying information from page to page (checkout form), I am turning the POST variables into SESSION variables then storing in a mysql database in the end. My hope is to have: <?php $conn = mysql_connect("localhost", "username", "password"); mysql_select_db("DBname",$conn); $sql = "INSERT INTO tablename VALUES ('$_SESSION[Member1FirstName]', '$_SESSION[Member1LastName]', '$_SESSION[Member1Email]', '$_SESSION[Member2FirstName]', '$_SESSION[Member2LastName]', '$_SESSION[Member2Email]', '$_SESSION[Member1FirstName]', '$_SESSION[Member3LastName]', '$_SESSION[Member3Email]')"; $result = mysql_query($sql, $conn) or die(mysql_error()); Header ("Location: completed.php"); ?> Where Member1, Member2, and Member3 values will appear on their own row within the table. I KNOW my code is wrong but I am giving a first shot at the overall business purpose I am trying to achieve and trying to learn how to code the right way. I am very, very new to programming so any 'baby advice' is greatly appreciated.

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• Android Couchdb - libcouch and IPC Aidl Services

  - by dirtySanchez

  I am working on a native CouchdDB app with android. Now just this week CouchOne released libcouch, described as "Library files needed to interact with CouchDB on Android": couchone_libcouch@Github It is a basic app that installs CouchDB if the CouchDB service (that comes with CouchDB if it was installed previously) can't be bound to. To be more precise, as I understand it: libcouch estimates CouchDb's presence on the device by trying to bind to a IPC Service from CouchDB and through that service wants communicate with CouchDB. Please see the method "attemptLaunch()" at CouchAppLauncher.class for reviewing this: public void attemptLaunch() { Log.i(TAG,"1.) called attemptLaunch"); Intent intent = new Intent(ICouchService.class.getName()); Log.i(TAG,"1.a) setup Intent"); Boolean canStart = bindService(intent, couchServiceConn, Context.BIND_AUTO_CREATE); Log.i(TAG,"1.b bound service. canStart: " + Boolean.toString(canStart)); if (!canStart) { setContentView(R.layout.install_couchdb); TextView label = (TextView) findViewById(R.id.install_couchdb_text); Button btn = (Button) this.findViewById(R.id.install_couchdb_btn); String text = getString(R.string.app_name) + " requires Apache CouchDB to be installed."; label.setText(text); // Launching the market will fail on emulators btn.setOnClickListener(new View.OnClickListener() { public void onClick(View v) { launchMarket(); finish(); } }); } } The question(s) I have about this are: libcouch never is able to "find" a previously installed CouchDB. It always attempts to install CouchDB from the market. This is because it never actually is able to bind to the CouchDBService. As I understand the purpose auf AIDL generated service interfaces, the actual service that intends to offer it's IPC to other applications should make use of AIDL. In this case the AIDL has been moved to the application that is trying to bind to the remote service, which is libcouch in this case. Reviewing the commits the AIDL files have just been moved out of that repository to libcouch. For complete linkage, here's the link to the Android CouchDB sources: github.com/couchone/libcouch-android Now, I could be completely wrong in my findings, it could also be lincouch's Manifest that s missing something, but I am really looking forward to get some answers!

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• Problem determining how to order F# types due to circular references

  - by James Black

  I have some types that extend a common type, and these are my models. I then have DAO types for each model type for CRUD operations. I now have a need for a function that will allow me to find an id given any model type, so I created a new type for some miscellaneous functions. The problem is that I don't know how to order these types. Currently I have models before dao, but I somehow need DAOMisc before CityDAO and CityDAO before DAOMisc, which isn't possible. The simple approach would be to put this function in each DAO, referring to just the types that can come before it, so, State comes before City as State has a foreign key relationship with City, so the miscellaneous function would be very short. But, this just strikes me as wrong, so I am not certain how to best approach this. Here is my miscellaneous type, where BaseType is a common type for all my models. type DAOMisc = member internal self.FindIdByType item = match(item:BaseType) with | :? StateType as i -> let a = (StateDAO()).Retrieve i a.Head.Id | :? CityType as i -> let a = (CityDAO()).Retrieve i a.Head.Id | _ -> -1 Here is one dao type. CommonDAO actually has the code for the CRUD operations, but that is not important here. type CityDAO() = inherit CommonDAO<CityType>("city", ["name"; "state_id"], (fun(reader) -> [ while reader.Read() do let s = new CityType() s.Id <- reader.GetInt32 0 s.Name <- reader.GetString 1 s.StateName <- reader.GetString 3 ]), list.Empty ) This is my model type: type CityType() = inherit BaseType() let mutable name = "" let mutable stateName = "" member this.Name with get() = name and set restnameval=name <- restnameval member this.StateName with get() = stateName and set stateidval=stateName <- stateidval override this.ToSqlValuesList = [this.Name;] override this.ToFKValuesList = [StateType(Name=this.StateName);] The purpose for this FindIdByType function is that I want to find the id for a foreign key relationship, so I can set the value in my model and then have the CRUD functions do the operations with all the correct information. So, City needs the id for the state name, so I would get the state name, put it into the state type, then call this function to get the id for that state, so my city insert will also include the id for the foreign key. This seems to be the best approach, in a very generic way to handle inserts, which is the current problem I am trying to solve.

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• Problem with Executing Mysql stored procedure

  - by karthik

  The stored procedure builds without any problem. The purpose of this is to take backup of selected tables to a script file. when the SP returns a value {Insert statements}. I am using the below MySql stored procedure, created by SQLWAYS [Tool to convert MsSql to MySql]. The actual MsSql SP is from http://www.codeproject.com/KB/database/InsertGeneratorPack.aspx When i execute the SP in MySql Query Browser, It says "Unknown column 'tbl_users' in 'field list'" What would be the problem ? Because there was no error when i build-ed this Converted MySql SP. Help.. DELIMITER $$ DROP PROCEDURE IF EXISTS `demo`.`InsertGenerator` $$ CREATE DEFINER=`root`@`localhost` PROCEDURE `InsertGenerator`(v_tableName VARCHAR(100)) SWL_return: BEGIN -- SQLWAYS_EVAL# to retrieve column specific information -- SQLWAYS_EVAL# table DECLARE v_string NATIONAL VARCHAR(3000); -- SQLWAYS_EVAL# first half -- SQLWAYS_EVAL# tement DECLARE v_stringData NATIONAL VARCHAR(3000); -- SQLWAYS_EVAL# data -- SQLWAYS_EVAL# statement DECLARE v_dataType NATIONAL VARCHAR(1000); -- SQLWAYS_EVAL# -- SQLWAYS_EVAL# columns DECLARE v_colName NATIONAL VARCHAR(50); DECLARE NO_DATA INT DEFAULT 0; DECLARE cursCol CURSOR FOR SELECT column_name,data_type FROM `columns` WHERE table_name = v_tableName; DECLARE CONTINUE HANDLER FOR SQLEXCEPTION BEGIN SET NO_DATA = -2; END; DECLARE CONTINUE HANDLER FOR NOT FOUND SET NO_DATA = -1; OPEN cursCol; SET v_string = CONCAT('INSERT ',v_tableName,'('); SET v_stringData = ''; SET NO_DATA = 0; FETCH cursCol INTO v_colName,v_dataType; IF NO_DATA <> 0 then -- NOT SUPPORTED print CONCAT('Table ',@tableName, ' not found, processing skipped.') close cursCol; LEAVE SWL_return; end if; WHILE NO_DATA = 0 DO IF v_dataType in('varchar','char','nchar','nvarchar') then SET v_stringData = CONCAT(v_stringData,'SQLWAYS_EVAL# ll(',v_colName,'SQLWAYS_EVAL# ''+'); ELSE if v_dataType in('text','ntext') then -- SQLWAYS_EVAL# -- SQLWAYS_EVAL# else SET v_stringData = CONCAT(v_stringData,'SQLWAYS_EVAL# ll(cast(',v_colName,'SQLWAYS_EVAL# 00)),'''')+'''''',''+'); ELSE IF v_dataType = 'money' then -- SQLWAYS_EVAL# doesn't get converted -- SQLWAYS_EVAL# implicitly SET v_stringData = CONCAT(v_stringData,'SQLWAYS_EVAL# y,''''''+ isnull(cast(',v_colName,'SQLWAYS_EVAL# 0)),''0.0000'')+''''''),''+'); ELSE IF v_dataType = 'datetime' then SET v_stringData = CONCAT(v_stringData,'SQLWAYS_EVAL# time,''''''+ isnull(cast(',v_colName, 'SQLWAYS_EVAL# 0)),''0'')+''''''),''+'); ELSE IF v_dataType = 'image' then SET v_stringData = CONCAT(v_stringData,'SQLWAYS_EVAL# ll(cast(convert(varbinary,',v_colName, 'SQLWAYS_EVAL# 6)),''0'')+'''''',''+'); ELSE SET v_stringData = CONCAT(v_stringData,'SQLWAYS_EVAL# ll(cast(',v_colName,'SQLWAYS_EVAL# 0)),''0'')+'''''',''+'); end if; end if; end if; end if; end if; SET v_string = CONCAT(v_string,v_colName,','); SET NO_DATA = 0; FETCH cursCol INTO v_colName,v_dataType; END WHILE; END $$ DELIMITER ;

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• Checking to see if a number is evenly divisible by other numbers with recursion in Python

  - by Ernesto

  At the risk of receiving negative votes, I will preface this by saying this is a midterm problem for a programming class. However, I have already submitted the code and passed the question. I changed the name of the function(s) so that someone can't immediately do a search and find the correct code, as that is not my purpose. I am actually trying to figure out what is actually MORE CORRECT from two pieces that I wrote. The problem tells us that a certain fast food place sells bite-sized pieces of chicken in packs of 6, 9, and 20. It wants us to create a function that will tell if a given number of bite-sized piece of chicken can be obtained by buying different packs. For example, 15 can be bought, because 6 + 9 is 15, but 16 cannot be bought, because no combination of the packs will equal 15. The code I submitted and was "correct" on, was: def isDivisible(n): """ n is an int Returns True if some integer combination of 6, 9 and 20 equals n Otherwise returns False. """ a, b, c = 20, 9, 6 if n == 0: return True elif n < 0: return False elif isDivisible(n - a) or isDivisible(n - b) or isDivisible(n - c): return True else: return False However, I got to thinking, if the initial number is 0, it will return True. Would an initial number of 0 be considered "buying that amount using 6, 9, and/or 20"? I cannot view the test cases the grader used, so I don't know if the grader checked 0 as a test case and decided that True was an acceptable answer or not. I also can't just enter the new code, because it is a midterm. I decided to create a second piece of code that would handle an initial case of 0, and assuming 0 is actually False: def isDivisible(n): """ n is an int Returns True if some integer combination of 6, 9 and 20 equals n Otherwise returns False. """ a, b, c = 20, 9, 6 if n == 0: return False else: def helperDivisible(n): if n == 0: return True elif n < 0: return False elif helperDivisible(n - a) or helperDivisible(n - b) or helperDivisible(n - c): return True else: return False return helperDivisible(n) As you can see, my second function had to use a "helper" function in order to work. My overall question, though, is which function do you think would provide the correct answer, if the grader had tested for 0 as an initial input?

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• Approach for authentication and storing user details.

  - by cappuccino

  Hey folks, I am using the Zend Framework but my question is broadly about sessions / databases / auth (PHP MySQL). Currently this is my approach to authentication: 1) User signs in, the details are checked in database. - Standard stuff really. 2) If the details are correct only the user's unique ID is stored in the session and a security token (user unique ID + IP + Browser info + salt). The session in written to the filesystem. I've been reading around and many are saying that storing stuff in sessions is not a good idea, and that you should really only write a unique ID which refers back to the user's details and a security token to prevent session hijacking. So this is the approach i've taken, i use to write the user's details in session, but i've moved that out. Wanted to know your opinions on this. I'm keeping sessions in the filesystem since i don't run on multiple servers, and since i'm only writting a tiny tiny bit of data to sessions, i thought that performance would be greater keeping sessions in the filesystem to reduce load on the database. Once the session is written on authentication, it really is only read-only from then on. 3) The rest of the user's details (like subscription details, permissions, account info etc) are cached in the filesystem (this can always be easily moved to memory if i wanted even more performance). So rather than keeping the user's details in session, the user's details are cached in the file system. I'm using Zend_Cache and the unique cache id is something like md5(/cache/auth/2892), the number is the unique id of the user. I guess the benefit of this method is that once the user is logged in, there is essentially not database queries being run to get the user's details. Just wonder if this approach is better than keeping the whole lot in session... 4) As the user moves throughout the site the only thing that is checked is the ID in the session and the security token. So, overall the first question is 1) is the filesystem more efficient than a database for this purpose 2) have i taken enough security precautions 3) is separating user detail's from the session into a cached file a pointless task? Thanks.

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• Smoke testing a .NET web application

  - by pdr

  I cannot believe I'm the first person to go through this thought process, so I'm wondering if anyone can help me out with it. Current situation: developers write a web site, operations deploy it. Once deployed, a developer Smoke Tests it, to make sure the deployment went smoothly. To me this feels wrong, it essentially means it takes two people to deploy an application; in our case those two people are on opposite sides of the planet and timezones come into play, causing havoc. But the fact remains that developers know what the minimum set of tests is and that may change over time (particularly for the web service portion of our app). Operations, with all due respect to them (and they would say this themselves), are button-pushers who need a set of instructions to follow. The manual solution is that we document the test cases and operations follow that document each time they deploy. That sounds painful, plus they may be deploying different versions to different environments (specifically UAT and Production) and may need a different set of instructions for each. On top of this, one of our near-future plans is to have an automated daily deploy environment, so then we'll have to instruct a computer as to how to deploy a given version of our app. I would dearly like to add to that instructions for how to smoke test the app. Now developers are better at documenting instructions for computers than they are for people, so the obvious solution seems to be to use a combination of nUnit (I know these aren't unit tests per se, but it is a built-for-purpose test runner) and either the Watin or Selenium APIs to run through the obvious browser steps and call to the web service and explain to the Operations guys how to run those unit tests. I can do that; I have mostly done it already. But wouldn't it be nice if I could make that process simpler still? At this point, the Operations guys and the computer are going to have to know which set of tests relate to which version of the app and tell the nUnit runner which base URL it should point to (say, www.example.com = v3.2 or test.example.com = v3.3). Wouldn't it be nicer if the test runner itself had a way of giving it a base URL and letting it download say a zip file, unpack it and edit a configuration file automatically before running any test fixtures it found in there? Is there an open source app that would do that? Is there a need for one? Is there a solution using something other than nUnit, maybe Fitnesse? For the record, I'm looking at .NET-based tools first because most of the developers are primarily .NET developers, but we're not married to it. If such a tool exists using other languages to write the tests, we'll happily adapt, as long as there is a test runner that works on Windows.

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• Quick question regarding this issue, Why doesnt it print out the second value(converted second value

  - by sil3nt

  Quick question, What have I done wrong here. The purpose of this code is to get the input into a string, the input being "12 34", with a space in between the "12" and "32" and to convert and print the two separate numbers from an integer variable known as number. Why doesn't the second call to the function copyTemp, not produce the value 34?. I have an index_counter variable which keeps track of the string index and its meant to skip the 'space' character?? what have i done wrong? thanks. #include <stdio.h> #include <string.h> int index_counter = 0; int number; void copyTemp(char *expr,char *temp); int main(){ char exprstn[80]; //as global? char tempstr[80]; gets(exprstn); copyTemp(exprstn,tempstr); printf("Expression: %s\n",exprstn); printf("Temporary: %s\n",tempstr); printf("number is: %d\n",number); copyTemp(exprstn,tempstr); //second call produces same output shouldnt it now produce 34 in the variable number? printf("Expression: %s\n",exprstn); printf("Temporary: %s\n",tempstr); printf("number is: %d\n",number); return 0; } void copyTemp(char *expr,char *temp){ int i; for(i = index_counter; expr[i] != '\0'; i++){ if (expr[i] == '0'){ temp[i] = expr[i]; } if (expr[i] == '1'){ temp[i] = expr[i]; } if (expr[i] == '2'){ temp[i] = expr[i]; } if (expr[i] == '3'){ temp[i] = expr[i]; } if (expr[i] == '4'){ temp[i] = expr[i]; } if (expr[i] == '5'){ temp[i] = expr[i]; } if (expr[i] == '6'){ temp[i] = expr[i]; } if (expr[i] == '7'){ temp[i] = expr[i]; } if (expr[i] == '8'){ temp[i] = expr[i]; } if (expr[i] == '9'){ temp[i] = expr[i]; } if (expr[i] == ' '){ temp[i] = '\0'; sscanf(temp,"%d",&number); index_counter = i+1; //skips? } } // is this included here? temp[i] = '\0'; }

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• how to create a system-wide independent universal counter object primarily for Database keys?

  - by andora

  I would like to create/use a system-wide independent universal 'counter object' that can be called via COM in a thread-safe manner. The counter object will be passed an ID to identify which counter to return, handle the counting, 'persist' the count (occasionally), have reasonable performance (as fast as possible) perhaps capable of 1000 counts per second or better (1mS) and be accessible cross-process/out-of-process. The current count status must be persisted between object restarts/shutdowns. The counter object is liklely to be a 'singleton' type object implemented in some form of free-threaded dictionary, containing maybe 10 counters (perhaps 50 max). The count needs to be monotonic and consistent, (ie: guaranteed unique sequential values). Each counter should have a few methods, like reset, inc, dec, set, clear, remove. As a luxury, I would like to have a variable-increment (ie: 'step by' value). To support thread-safefty, perhaps some sorm of critical-section or mutex call. It just needs to return a long/4byte signed integer. I really want something that can be called from anywhere, including VBScript, so I figure COM is my preferred solution. The primary use of this is for database keys. I am unable to use autoinc or guid type keys and have ruled out database-generated counting systems at this point. I've spent days researching this and I have really struggled to find a solution. The best I can find is a free-threaded dictionary object that can be instantiated using COM+ from Motobit - it seems to offer all the 'basics' and I guess I could create some form of wrapper for this. So, here are my questions: Does such a 'general purpose counter-object already exist? Can you direct me to it? (MS did do an IIS/ASP object called 'MSWC.Counter' but this isn't 'cross-process'/ out-of-process component and isn't thread-safe. (but if it was, it would do!) What is the best way of creating such a Component? (I'd prefer VB6 right-now, [don't ask!] but can do in VB.NET2005 if I had to). I don't have the skills/knowledge/tools to use anything else. I am desparate for a workable solution. I need specific guidance! If anybody can code something up for me I am prepared to pay for it.

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• How do I define a template class and divide it into multiple files?

  - by hkBattousai

  I have written a simple template class for test purpose. It compiles without any errors, but when I try to use it in main(), it give some linker errors. main.cpp #include <iostream> #include "MyNumber.h" int wmain(int argc, wchar_t * argv[]) { MyNumber<float> num; num.SetValue(3.14); std::cout << "My number is " << num.GetValue() << "." << std::endl; system("pause"); return 0; } MyNumber.h #pragma once template <class T> class MyNumber { public: MyNumber(); ~MyNumber(); void SetValue(T val); T GetValue(); private: T m_Number; }; MyNumber.cpp #include "MyNumber.h" template <class T> MyNumber<T>::MyNumber() { m_Number = static_cast<T>(0); } template <class T> MyNumber<T>::~MyNumber() { } template <class T> void MyNumber<T>::SetValue(T val) { m_Number = val; } template <class T> T MyNumber<T>::GetValue() { return m_Number; } When I build this code, I get the following linker errors: Error 7 Console Demo C:\Development\IDE\Visual Studio 2010\SAVE\Grand Solution\X64\Debug\Console Demo.exe 1 error LNK1120: 4 unresolved externals Error 3 Console Demo C:\Development\IDE\Visual Studio 2010\SAVE\Grand Solution\Console Demo\main.obj error LNK2019: unresolved external symbol "public: __cdecl MyNumber::~MyNumber(void)" (??1?$MyNumber@M@@QEAA@XZ) referenced in function wmain Error 6 Console Demo C:\Development\IDE\Visual Studio 2010\SAVE\Grand Solution\Console Demo\main.obj error LNK2019: unresolved external symbol "public: __cdecl MyNumber::MyNumber(void)" (??0?$MyNumber@M@@QEAA@XZ) referenced in function wmain Error 4 Console Demo C:\Development\IDE\Visual Studio 2010\SAVE\Grand Solution\Console Demo\main.obj error LNK2019: unresolved external symbol "public: float __cdecl MyNumber::GetValue(void)" (?GetValue@?$MyNumber@M@@QEAAMXZ) referenced in function wmain Error 5 Console Demo C:\Development\IDE\Visual Studio 2010\SAVE\Grand Solution\Console Demo\main.obj error LNK2019: unresolved external symbol "public: void __cdecl MyNumber::SetValue(float)" (?SetValue@?$MyNumber@M@@QEAAXM@Z) referenced in function wmain But, if I leave main() empty, I don't get any linker errors. What is wrong with my template class? What am I doing wrong?

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• Using empty row as default in a ComboBox with Style "DropDownList"?

  - by Pesche Helfer

  Hi board I am trying to write a method, that takes a ComboBox, a DataTable and a TextBox as arguments. The purpose of it is to filter the members displayed in the ComboBox according to the TextBox.Text. The DataTable contains the entire list of possible entries that will then be filtered. For filtering, I create a DataView of the DataTable, add a RowFilter and then bind this View to the ComboBox as DataSource. To prevent the user from typing into the ComboBox, I choose the DropDownStyle DropDownList. That’s working fine so far, except that the user should also be able to choose nothing / empty line. In fact, this should be the default member to be displayed (to prevent choosing a wrong member by accident, if the user clicks through the dialog too fast). I tried to solve this problem by adding a new Row to the view. While this works for some cases, the main issue here is that any DataTable can be passed to the method. If the DataTable contains columns that cannot be null and don’t contain a default value, I suppose I will raise an error by adding an empty row. A possibility would be to create a view that contains only the column that is defined as DisplayMember, and the one that is defined as ValueMember. Alas, this can’t be done with a view in C#. I would like to avoid creating a true copy of the DataTable at all cost, since who knows how big it will get with time. Do you have any suggestions how to get around this problem? Instead of a view, could I create an object containing two members and assign the DisplayMember and the ValueMember to these members? Would the members be passed as reference (what I hope) or would true copied be created (in which case it would not be a solution)? Thank you very much for your help! Best regards public static void ComboFilter(ComboBox cb, DataTable dtSource, TextBox filterTextBox) { cb.DropDownStyle = ComboBoxStyle.DropDownList; string displayMember = cb.DisplayMember; DataView filterView = new DataView(dtSource); filterView.AddNew(); filterView.RowFilter = displayMember + " LIKE '%" + filterTextBox.Text + "%'"; cb.DataSource = filterView; }

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• I have to select the checkbox two times to check/uncheck in jTable

  - by 117526709403775781607

  I have a jTable code i intend to use, but the problem with it is that when i click on the checkbox once it doesn't select/deselect it, instead i have to click twice. But if i select any other cell in the row except the one containing the checkbox the purpose is solved. HERE IS MY CODE : public class TableSelectionTest extends JFrame implements ListSelectionListener { private final int COLUMN_COUNT = 5; private TblModel model; public TableSelectionTest() { initialize(); setDefaultCloseOperation(EXIT_ON_CLOSE); pack(); } private void initialize() { List data = new ArrayList(); for (int i = 0; i < 10; i++) { Object record[] = new Object[COLUMN_COUNT]; record[0] = Boolean.FALSE; for (int j = 1; j < COLUMN_COUNT; j++) { record[j] = new Integer(j); } data.add(record); } model = new TblModel(data); JTable table = new JTable(model); table.getSelectionModel().setSelectionMode(ListSelectionModel.SINGLE_SELECTION); table.getSelectionModel().addListSelectionListener (this); JScrollPane scroll = new JScrollPane(table); getContentPane().add(scroll, BorderLayout.CENTER); } public static void main(String[] args) { TableSelectionTest f = new TableSelectionTest(); f.show(); } class TblModel extends AbstractTableModel { private List data; public TblModel(List data) { this.data = data; } public int getColumnCount() { return COLUMN_COUNT; } public int getRowCount() { return data == null ? 0 : data.size(); } public void setValueAt(Object value, int rowIndex, int columnIndex) { getRecord(rowIndex)[columnIndex] = value; super.fireTableCellUpdated(rowIndex, columnIndex); } public Object getValueAt(int rowIndex, int columnIndex) { return getRecord(rowIndex)[columnIndex]; } public boolean isCellEditable(int rowIndex, int columnIndex) { if(columnIndex == 0) return true; else return false; } public Class getColumnClass(int columnIndex) { if (data == null || data.size() == 0) { return Object.class; } Object o = getValueAt(0, columnIndex); return o == null ? Object.class : o.getClass(); } private Object[] getRecord(int rowIndex) { return (Object[]) data.get(rowIndex); } } public void valueChanged(ListSelectionEvent e) { if (!e.getValueIsAdjusting()) { ListSelectionModel lsm = (ListSelectionModel) e.getSource(); int index = lsm.getMinSelectionIndex(); if(model.getRecord(index)[0] == Boolean.FALSE) model.setValueAt(Boolean.TRUE, index, 0); else if(model.getRecord(index)[0] == Boolean.TRUE) model.setValueAt(Boolean.FALSE, index, 0); } } } Please reply soon as it is bugging me a lot Thank you in advance :)

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• Dependency Injection: I don't get where to start!

  - by Andy

  I have several articles about Dependency Injection, and I can see the benefits, especially when it comes to unit testing. The units can me loosely coupled, and mocking of dependencies can be made. The trouble is - I just don't get where to start. Consider this snippet below of (much edited for the purpose of this post) code that I have. I am instantiating a Plc object from the main form, and passing in a communications mode via the Connect method. In it's present form it becomes hard to test, because I can't isolate the Plc from the CommsChannel to unit test it. (Can I?) The class depends on using a CommsChannel object, but I am only passing in a mode that is used to create this channel within the Plc itself. To use dependancy injection, I should really pass in an already created CommsChannel (via an 'ICommsChannel' interface perhaps) to the Connect method, or maybe via the Plc constructor. Is that right? But then that would mean creating the CommsChannel in my main form first, and this doesn't seem right either, because it feels like everything will come back to the base layer of the main form, where everything begins. Somehow it feels like I am missing a crucial piece of the puzzle. Where do you start? You have to create an instance of something somewhere, but I'm struggling to understand where that should be. public class Plc() { public bool Connect(CommsMode commsMode) { bool success = false; // Create new comms channel. this._commsChannel = this.GetCommsChannel(commsMode); // Attempt connection success = this._commsChannel.Connect(); return this._connected; } private CommsChannel GetCommsChannel(CommsMode mode) { CommsChannel channel; switch (mode) { case CommsMode.RS232: channel = new SerialCommsChannel( SerialCommsSettings.Default.ComPort, SerialCommsSettings.Default.BaudRate, SerialCommsSettings.Default.DataBits, SerialCommsSettings.Default.Parity, SerialCommsSettings.Default.StopBits); break; case CommsMode.Tcp: channel = new TcpCommsChannel( TCPCommsSettings.Default.IP_Address, TCPCommsSettings.Default.Port); break; default: // Throw unknown comms channel exception. } return channel; } }

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• JavaScript - Cross Site Scripting - Permission Denied

  - by Villager

  Hello, I have a web application for which I am trying to use Twitter's OAuth functionality. This application has a link that prompts a user for their Twitter credentials. When a user clicks this link, a new window is opened via JavaScript. This window serves as a dialog. This is accomplished like such: MainPage: <div id="promptDiv"><a href="#" onclick="launchDialog('twitter/prompt.aspx');">Provide Credentials</a></div> ... function launchDialog(url) { var specs = "location=0,menubar=0,status=0,titlebar=0,toolbar=0"; var dialogWindow = window.open(url, "dialog", specs, true); } When a user clicks the link, they are redirected to Twitter's site from the prompt.aspx page. On the Twitter site, the user has the option to enter their Twitter credentials. When they have provided their credentials, they are redirected back to my site. This is accomplished through a callback url which can be set for applications on Twitter's site. When the callback happens, the user is redirected to "/twitter/confirm.aspx" on my site in the dialog window. When this happens I want to update the contents of "promptDiv" to say "You have successfully connected with Twitter" to replace the link and close the dialog. This serves the purpose of notifying the user they have successfully completed this step. I can successfully close the dialog window. However, when I am try to update the HTML DOM, I receive an error that says "Error: Permission denied to get property Window.document". In an attempt to update the HTML DOM, I tried using the following script in "/twitter/confirm.aspx": // Error is thrown on the first line. var confirmDiv = window.opener.document.getElementById("confirmDiv"); if (confirmDiv != null) { // Update the contents } window.close(); I then just tried to read the HTML to see if I could even access the DOM via the following script: alert(window.opener.document.body.innerHTML); When I attempted this, I still got a "Permission denied" error. I know this has something to do with cross-site scripting. However, I do not know how to resolve it. How do I fix this problem? Am I structuring my application incorrectly? How do I update the HTML DOM after a user has been redirected back to my site? Thank you for your help!

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