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• PCI Encryption Key Management

  - by Unicorn Bob

  (Full disclosure: I'm already an active participant here and at StackOverflow, but for reasons that should hopefully be obvious, I'm choosing to ask this particular question anonymously). I currently work for a small software shop that produces software that's sold commercially to manage small- to mid-size business in a couple of fairly specialized industries. Because these industries are customer-facing, a large portion of the software is related to storing and managing customer information. In particular, the storage (and securing) of customer credit card information. With that, of course, comes PCI compliance. To make a long story short, I'm left with a couple of questions about why certain things were done the way they were, and I'm unfortunately without much of a resource at the moment. This is a very small shop (I report directly to the owner, as does the only other full-time employee), and the owner doesn't have an answer to these questions, and the previous developer is...err...unavailable. Issue 1: Periodic Re-encryption As of now, the software prompts the user to do a wholesale re-encryption of all of the sensitive information in the database (basically credit card numbers and user passwords) if either of these conditions is true: There are any NON-encrypted pieces of sensitive information in the database (added through a manual database statement instead of through the business object, for example). This should not happen during the ordinary use of the software. The current key has been in use for more than a particular period of time. I believe it's 12 months, but I'm not certain of that. The point here is that the key "expires". This is my first foray into commercial solution development that deals with PCI, so I am unfortunately uneducated on the practices involved. Is there some aspect of PCI compliance that mandates (or even just strongly recommends) periodic key updating? This isn't a huge issue for me other than I don't currently have a good explanation to give to end users if they ask why they are being prompted to run it. Question 1: Is the concept of key expiration standard, and, if so, is that simply industry-standard or an element of PCI? Issue 2: Key Storage Here's my real issue...the encryption key is stored in the database, just obfuscated. The key is padded on the left and right with a few garbage bytes and some bits are twiddled, but fundamentally there's nothing stopping an enterprising person from examining our (dotfuscated) code, determining the pattern used to turn the stored key into the real key, then using that key to run amok. This seems like a horrible practice to me, but I want to make sure that this isn't just one of those "grin and bear it" practices that people in this industry have taken to. I have developed an alternative approach that would prevent such an attack, but I'm just looking for a sanity check here. Question 2: Is this method of key storage--namely storing the key in the database using an obfuscation method that exists in client code--normal or crazy? Believe me, I know that free advice is worth every penny that I've paid for it, nobody here is an attorney (or at least isn't offering legal advice), caveat emptor, etc. etc., but I'm looking for any input that you all can provide. Thank you in advance!

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• Where should instantiated classes be stored?

  - by Eric C.

  I'm having a bit of a design dilemma here. I'm writing a library that consists of a bunch of template classes that are designed to be used as a base for creating content. For example: public class Template { public string Name {get; set;} public string Description {get; set;} public string Attribute1 {get; set;} public string Attribute2 {get; set;} public Template() { //constructor } public void DoSomething() { //does something } ... } The problem is, not only is the library providing the templates, it will also supply quite a few predefined templates which are instances of these template classes. The question is, where do I put these instances of the templates? The three solutions I've come up with so far are: 1) Provide serialized instances of the templates as files. On the one hand, this solution would keep the instances separated from the library itself, which is nice, but it would also potentially add complexity for the user. Even if we provided methods for loading/deserializing the files, they'd still have to deal with a bunch of files, and some kind of config file so the app knows where to look for those files. Plus, creating the template files would probably require a separate app, so if the user wanted to stick with the files method of storing templates, we'd have to provide some kind of app for creating the template files. Also, this requires external dependencies for testing the templates in the user's code. 2) Add readonly instances to the template class Example: public class Template { public string Name {get; set;} public string Description {get; set;} public string Attribute1 {get; set;} public string Attribute2 {get; set;} public Template PredefinedTemplate { get { Template templateInstance = new Template(); templateInstance.Name = "Some Name"; templateInstance.Description = "A description"; ... return templateInstance; } } public Template() { //constructor } public void DoSomething() { //does something } ... } This method would be convenient for users, as they would be able to access the predefined templates in code directly, and would be able to unit test code that used them. The drawback here is that the predefined templates pollute the Template type namespace with a bunch of extra stuff. I suppose I could put the predefined templates in a different namespace to get around this drawback. The only other problem with this approach is that I'd have to basically duplicate all the namespaces in the library in the predefined namespace (e.g. Templates.SubTemplates and Predefined.Templates.SubTemplates) which would be a pain, and would also make refactoring more difficult. 3) Make the templates abstract classes and make the predefined templates inherit from those classes. For example: public abstract class Template { public string Name {get; set;} public string Description {get; set;} public string Attribute1 {get; set;} public string Attribute2 {get; set;} public Template() { //constructor } public void DoSomething() { //does something } ... } and public class PredefinedTemplate : Template { public PredefinedTemplate() { this.Name = "Some Name"; this.Description = "A description"; this.Attribute1 = "Some Value"; ... } } This solution is pretty similar to #2, but it ends up creating a lot of classes that don't really do anything (none of our predefined templates are currently overriding behavior), and don't have any methods, so I'm not sure how good a practice this is. Has anyone else had any experience with something like this? Is there a best practice of some kind, or a different/better approach that I haven't thought of? I'm kind of banging my head against a wall trying to figure out the best way to go. Thanks!

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• Profiling Startup Of VS2012 &ndash; JustTrace Profiler

  - by Alois Kraus

  JustTrace is made by Telerik which is mainly known for its collection of UI controls. The current version (2012.3.1127.0) does include a performance and memory profiler which does cost 614€ and is currently with a special offer for 306€ on sale. It does include one year of free upgrades. The uneven € numbers are calculated from the 799€ and 50% dicsount price. The UI is already in Metro style and simple to use. Multi process, attach, method recording filter are not supported. It looks like JustTrace is like Ants a Just My Code profiler. For stuff where you do not have the pdbs or you want to dig deeper into the BCL code you will not get far. After getting the profile data you get in the All Methods grid a plain list with hit count and own time. The method list for all methods is also suspiciously short which is a clear sign that you will not get far during the analysis of foreign code. But at least there is also a memory profiler included. For this I have to choose in the first window for Profiling Type “Memory Profiler” to check the memory consumption of VS.  There are some interesting number to see but I do really miss from YourKit the thread stack window. How am I supposed to get a clue when much memory is allocated and the CPU consumption is high in which places I should look? The Snapshot summary gives a rough overview which is ok for a first impression. Next is Assemblies? This gives you a list of all loaded assemblies. Not terribly useful.   The By Type view gives you exactly what it is supposed to do. You have to keep in mind that this list is filtered by the types you did check in the Assemblies list. The By Type instance list does only show types from assemblies which do not originate from Microsoft. By default mscorlib and System are not checked. That is the reason why for the first time my By Type window looked like The idea behind this feature is to show only your instances because you are ultimately responsible for the overall memory consumption. I am not sure if I do like this feature because by default it does hide too much. I do want to see at least how many strings and arrays are allocated. A simple namespace filter would also do it in my opinion. Now you can examine all string instances and look who in the object graph does keep a reference on them. That is nice but YourKit has the big plus that you can also look into the string contents.  I am also not sure how in the graph cycles are visualized and what will happen if you have thousands of objects referencing you. That's pretty much it about JustTrace. It can help the average developer to pinpoint performance and memory issues by just looking at his own code and instances. Showing them more will not help them because the sheer amount of information will overwhelm them. And you need to have a pretty good understanding how the GC and the CLR does work. When you have a performance issue at a customer machine it is sometimes very helpful to be able a bring a profiler onto the machine (no pdbs, …) and to get a full snapshot of all processes which are in the problematic use case involved. For these more advanced use cased JustTrace is certainly the wrong tool. Next: SpeedTrace

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• Data breakpoints to find points where data gets broken

  - by raccoon_tim

  When working with a large code base, finding reasons for bizarre bugs can often be like finding a needle in a hay stack. Finding out why an object gets corrupted without no apparent reason can be quite daunting, especially when it seems to happen randomly and totally out of context. Scenario Take the following scenario as an example. You have defined the a class that contains an array of characters that is 256 characters long. You now implement a method for filling this buffer with a string passed as an argument. At this point you mistakenly expect the buffer to be 256 characters long. At some point you notice that you require another character buffer and you add that after the previous one in the class definition. You now figure that you don’t need the 256 characters that the first member can hold and you shorten that to 128 to conserve space. At this point you should start thinking that you also have to modify the method defined above to safeguard against buffer overflow. It so happens, however, that in this not so perfect world this does not cross your mind. Buffer overflow is one of the most frequent sources for errors in a piece of software and often one of the most difficult ones to detect, especially when data is read from an outside source. Many mass copy functions provided by the C run-time provide versions that have boundary checking (defined with the _s suffix) but they can not guard against hard coded buffer lengths that at some point get changed. Finding the bug Getting back to the scenario, you’re now wondering why does the second string get modified with data that makes no sense at all. Luckily, Visual Studio provides you with a tool to help you with finding just these kinds of errors. It’s called data breakpoints. To add a data breakpoint, you first run your application in debug mode or attach to it in the usual way, and then go to Debug, select New Breakpoint and New Data Breakpoint. In the popup that opens, you can type in the memory address and the amount of bytes you wish to monitor. You can also use an expression here, but it’s often difficult to come up with an expression for data in an object allocated on the heap when not in the context of a certain stack frame. There are a couple of things to note about data breakpoints, however. First of all, Visual Studio supports a maximum of four data breakpoints at any given time. Another important thing to notice is that some C run-time functions modify memory in kernel space which does not trigger the data breakpoint. For instance, calling ReadFile on a buffer that is monitored by a data breakpoint will not trigger the breakpoint. The application will now break at the address you specified it to. Often you might immediately spot the issue but the very least this feature can do is point you in the right direction in search for the real reason why the memory gets inadvertently modified. Conclusions Data breakpoints are a great feature, especially when doing a lot of low level operations where multiple locations modify the same data. With the exception of some special cases, like kernel memory modification, you can use it whenever you need to check when memory at a certain location gets changed on purpose or inadvertently.

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• JEP 124: Enhance the Certificate Revocation-Checking API

  - by smullan

  Revocation checking is the mechanism to determine the revocation status of a certificate. If it is revoked, it is considered invalid and should not be used. Currently as of JDK 7, the PKIX implementation of java.security.cert.CertPathValidator  includes a revocation checking implementation that supports both OCSP and CRLs, the two main methods of checking revocation. However, there are very few options that allow you to configure the behavior. You can always implement your own revocation checker, but that's a lot of work. JEP 124 (Enhance the Certificate Revocation-Checking API) is one of the 11 new security features in JDK 8. This feature enhances the java.security.cert API to support various revocation settings such as best-effort checking, end-entity certificate checking, and mechanism-specific options and parameters. Let's describe each of these in more detail and show some examples. The features are provided through a new class named PKIXRevocationChecker. A PKIXRevocationChecker instance is returned by a PKIX CertPathValidator as follows: CertPathValidator cpv = CertPathValidator.getInstance("PKIX"); PKIXRevocationChecker prc = (PKIXRevocationChecker)cpv.getRevocationChecker(); You can now set various revocation options by calling different methods of the returned PKIXRevocationChecker object. For example, the best-effort option (called soft-fail) allows the revocation check to succeed if the status cannot be obtained due to a network connection failure or an overloaded server. It is enabled as follows: prc.setOptions(Enum.setOf(Option.SOFT_FAIL)); When the SOFT_FAIL option is specified, you can still obtain any exceptions that may have been thrown due to network issues. This can be useful if you want to log this information or treat it as a warning. You can obtain these exceptions by calling the getSoftFailExceptions method: List<CertPathValidatorException> exceptions = prc.getSoftFailExceptions(); Another new option called ONLY_END_ENTITY allows you to only check the revocation status of the end-entity certificate. This can improve performance, but you should be careful using this option, as the revocation status of CA certificates will not be checked. To set more than one option, simply specify them together, for example: prc.setOptions(Enum.setOf(Option.SOFT_FAIL, Option.ONLY_END_ENTITY)); By default, PKIXRevocationChecker will try to check the revocation status of a certificate using OCSP first, and then CRLs as a fallback. However, you can switch the order using the PREFER_CRLS option, or disable the fallback altogether using the NO_FALLBACK option. For example, here is how you would only use CRLs to check the revocation status: prc.setOptions(Enum.setOf(Option.PREFER_CRLS, Option.NO_FALLBACK)); There are also a number of other useful methods which allow you to specify various options such as the OCSP responder URI, the trusted OCSP responder certificate, and OCSP request extensions. However, one of the most useful features is the ability to specify a cached OCSP response with the setOCSPResponse method. This can be quite useful if the OCSPResponse has already been obtained, for example in a protocol that uses OCSP stapling. After you have set all of your preferred options, you must add the PKIXRevocationChecker to your PKIXParameters object as one of your custom CertPathCheckers before you validate the certificate chain, as follows: PKIXParameters params = new PKIXParameters(keystore); params.addCertPathChecker(prc); CertPathValidatorResult result = cpv.validate(path, params); Early access binaries of JDK 8 can be downloaded from http://jdk8.java.net/download.html

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• Android Game Development. Async Task. Loading Bitmap Images Sounds

  - by user2534694

  Im working on this game for android. And wanted to know if my thread architecture was right or wrong. Basically, what is happening is, i am loading All the bitmaps,sounds etc in the initializevariables() method. But sometimes the game crashes and sometimes it doesnt. So i decided to use async task. But that doesnt seem to work either (i too loads at times and crashes at times) @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setFullScreen(); initializeVariables(); new initVariables().execute(); // setContentView(ourV); } private void setFullScreen() { requestWindowFeature(Window.FEATURE_NO_TITLE); getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN); getWindow().setFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON, WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON ); } private void initializeVariables() { ourV=new OurView(this); stats = getSharedPreferences(filename, 0); ballPic = BitmapFactory.decodeResource(getResources(), R.drawable.ball5); platform = BitmapFactory.decodeResource(getResources(), R.drawable.platform3); gameB = BitmapFactory.decodeResource(getResources(), R.drawable.game_back2); waves = BitmapFactory.decodeResource(getResources(), R.drawable.waves); play = BitmapFactory.decodeResource(getResources(), R.drawable.play_icon); pause = BitmapFactory.decodeResource(getResources(), R.drawable.pause_icon); platform2 = BitmapFactory.decodeResource(getResources(), R.drawable.platform4); countdown = BitmapFactory.decodeResource(getResources(), R.drawable.countdown); bubbles = BitmapFactory.decodeResource(getResources(), R.drawable.waves_bubbles); backgroundMusic = MediaPlayer.create(this, R.raw.music); jump = MediaPlayer.create(this, R.raw.jump); click = MediaPlayer.create(this, R.raw.jump_crack); sm = (SensorManager) getSystemService(SENSOR_SERVICE); acc = sm.getDefaultSensor(Sensor.TYPE_ACCELEROMETER); sm.registerListener(this, acc, SensorManager.SENSOR_DELAY_GAME); ourV.setOnTouchListener(this); dialog = new Dialog(this,android.R.style.Theme_Translucent_NoTitleBar_Fullscreen); dialog.setContentView(R.layout.pausescreen); dialog.hide(); dialog.setOnDismissListener(this); resume = (Button) dialog.findViewById(R.id.bContinue); menu = (Button) dialog.findViewById(R.id.bMainMenu); newTry = (Button) dialog.findViewById(R.id.bNewTry); tv_time = (TextView) dialog.findViewById(R.id.tv_time); tv_day = (TextView) dialog.findViewById(R.id.tv_day); tv_date = (TextView) dialog.findViewById(R.id.tv_date); resume.setOnClickListener(this); menu.setOnClickListener(this); newTry.setOnClickListener(this); } @Override protected void onResume() { //if its running the first time it goes in the brackets if(firstStart) { ourV.onResume(); firstStart=false; } } Now what onResume in ourV does is , its responsible for starting the thread //this is ourV.onResume public void onResume() { t=new Thread(this); isRunning=true; t.start(); } Now what I want is to initialise all bitmaps sounds etc in the async background method public class initVariables extends AsyncTask<Void, Integer, Void> { ProgressDialog pd; @Override protected void onPreExecute() { pd = new ProgressDialog(GameActivity.this); pd.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL); pd.setMax(100); pd.show(); } @Override protected Void doInBackground(Void... arg0) { synchronized (this) { for(int i=0;i<20;i++) { publishProgress(5); try { Thread.sleep(89); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } } } return null; } @Override protected void onProgressUpdate(Integer... values) { pd.incrementProgressBy(values[0]); } @Override protected void onPostExecute(Void result) { pd.dismiss(); setContentView(ourV); } } Now since I am new to this. You could tellme maybe if async is not required for such stuff and there is another way of doing it normally.

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• DirectX particle system. ConstantBuffer

  - by Liuka

  I'm new in DirectX and I'm making a 2D game. I want to use a particle system to simulate a 3D starfield, so each star has to set its own constant buffer for the vertexshader es. to set it's world matrix. So if i have 500 stars (that move every frame) i need to call 500 times VSsetconstantbuffer, and map/unmap each buffer. with 500 stars i have an average of 220 fps and that's quite good. My bottelneck is Vs/PsSetconstantbuffer. If i dont call this function i have 400 fps(obliviously nothing is display, since i dont set the position of the stars). So is there a method to speed up the render of the particle system?? Ps. I'm using intel integrate graphic (hd 2000-3000). with a nvidia (or amd) gpu will i have the same bottleneck?? If, for example, i dont call setshaderresource i have 10-20 fps more (for 500 objcets), that is not 180.Why does SetConstantBuffer take so long?? LPVOID VSdataPtr = VSmappedResource.pData; memcpy(VSdataPtr, VSdata, CszVSdata); context->Unmap(VertexBuffer, 0); result = context->Map(PixelBuffer, 0, D3D11_MAP_WRITE_DISCARD, 0, &PSmappedResource); if (FAILED(result)) { outputResult.OutputErrorMessage(TITLE, L"Cannot map the PixelBuffer", &result, OUTPUT_ERROR_FILE); return; } LPVOID PSdataPtr = PSmappedResource.pData; memcpy(PSdataPtr, PSdata, CszPSdata); context->Unmap(PixelBuffer, 0); context->VSSetConstantBuffers(0, 1, &VertexBuffer); context->PSSetConstantBuffers(0, 1, &PixelBuffer); this update and set the buffer. It's part of the render method of a sprite class that contains a the vertex buffer and the texture to apply to the quads(it's a 2d game) too. I have an array of 500 stars (sprite setup with a star texture). Every frame: clear back buffer; draw the array of stars; present the backbuffer; draw also call the function update( which calculate the position of the sprite on screen based on a "camera class") Ok, create a vertex buffer with the vertices of each quads(stars) seems to be good, since the stars don't change their "virtual" position; so.... In a particle system (where particles move) it's better to have all the object in only one vertices array, rather then an array of different sprite/object in order to update all the vertices' position with a single setbuffer call. In this case i have to use a dynamic vertex buffer with the vertices positions like this: verticesForQuad={{ XMFLOAT3((float)halfDImensions.x-1+pos.x, (float)halfDImensions.y-1+pos.y, 1.0f), XMFLOAT2(1.0f, 0.0f) }, { XMFLOAT3((float)halfDImensions.x-1+pos.x, -(float)halfDImensions.y-1+pos.y, 1.0f), XMFLOAT2(1.0f, 1.0f) }, { XMFLOAT3(-(float)halfDImensions.x-1+pos.x, (float)halfDImensions.y-1.pos.y, 1.0f), XMFLOAT2(0.0f, 0.0f) }, { XMFLOAT3(-(float)halfDImensions.x-1.pos.x, -(float)halfDImensions.y-1+pos.y, 1.0f), XMFLOAT2(0.0f, 1.0f) }, ....other quads} where halfDimensions is the halfsize in pixel of a texture and pos the virtual position of a star. than create an array of verticesForQuad and create the vertex buffer ZeroMemory(&vertexDesc, sizeof(vertexDesc)); vertexDesc.Usage = D3D11_USAGE_DEFAULT; vertexDesc.BindFlags = D3D11_BIND_VERTEX_BUFFER; vertexDesc.ByteWidth = sizeof(VertexType)* 4*numStars; ZeroMemory(&resourceData, sizeof(resourceData)); resourceData.pSysMem = verticesForQuad; result = device->CreateBuffer(&vertexDesc, &resourceData, &CvertexBuffer); and call each frame Context->IASetVertexBuffers(0, 1, &CvertexBuffer, &stride, &offset); But if i want to add and remove obj i have to recreate the buffer each time, havent i?? There is a faster way? I think i can create a vertex buffer with a max size (es. 10000 objs) and when i update it set only the 250 position (for 250 onjs for example) and pass this number as the vertexCount to the draw function (numObjs*4), or i'm worng

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• Selective Suppression of Log Messages

  - by Duncan Mills

  Those of you who regularly read this blog will probably have noticed that I have a strange predilection for logging related topics, so why break this habit I ask?  Anyway here's an issue which came up recently that I thought was a good one to mention in a brief post.  The scenario really applies to production applications where you are seeing entries in the log files which are harmless, you know why they are there and are happy to ignore them, but at the same time you either can't or don't want to risk changing the deployed code to "fix" it to remove the underlying cause. (I'm not judging here). The good news is that the logging mechanism provides a filtering capability which can be applied to a particular logger to selectively "let a message through" or suppress it. This is the technique outlined below. First Create Your Filter  You create a logging filter by implementing the java.util.logging.Filter interface. This is a very simple interface and basically defines one method isLoggable() which simply has to return a boolean value. A return of false will suppress that particular log message and not pass it onto the handler. The method is passed the log record of type java.util.logging.LogRecord which provides you with access to everything you need to decide if you want to let this log message pass through or not, for example  getLoggerName(), getMessage() and so on. So an example implementation might look like this if we wanted to filter out all the log messages that start with the string "DEBUG" when the logging level is not set to FINEST:  public class MyLoggingFilter implements Filter {     public boolean isLoggable(LogRecord record) {         if ( !record.getLevel().equals(Level.FINEST) && record.getMessage().startsWith("DEBUG")){          return false;            }         return true;     } } Deploying   This code needs to be put into a JAR and added to your WebLogic classpath.  It's too late to load it as part of an application, so instead you need to put the JAR file into the WebLogic classpath using a mechanism such as the PRE_CLASSPATH setting in your domain setDomainEnv script. Then restart WLS of course. Using The final piece if to actually assign the filter.  The simplest way to do this is to add the filter attribute to the logger definition in the logging.xml file. For example, you may choose to define a logger for a specific class that is raising these messages and only apply the filter in that case.  <logger name="some.vendor.adf.ClassICantChange"         filter="oracle.demo.MyLoggingFilter"/> You can also apply the filter using WLST if you want a more script-y solution.

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• Don’t string together XML

  - by KyleBurns

  XML has been a pervasive tool in software development for over a decade.  It provides a way to communicate data in a manner that is simple to understand and free of platform dependencies.  Also pervasive in software development is what I consider to be the anti-pattern of using string manipulation to create XML.  This usually starts with a “quick and dirty” approach because you need an XML document and looks like (for all of the examples here, we’ll assume we’re writing the body of a method intended to take a Contact object and return an XML string): return string.Format("<Contact><BusinessName>{0}</BusinessName></Contact>", contact.BusinessName);   In the code example, I created (or at least believe I created) an XML document representing a simple contact object in one line of code with very little overhead.  Work’s done, right?  No it’s not.  You see, what I didn’t realize was that this code would be used in the real world instead of my fantasy world where I own all the data and can prevent any of it containing problematic values.  If I use this code to create a contact record for the business “Sanford & Son”, any XML parser will be incapable of processing the data because the ampersand is special in XML and should have been encoded as &amp;. Following the pattern that I have seen many times over, my next step as a developer is going to be to do what any developer in his right mind would do – instruct the user that ampersands are “bad” and they cannot be used without breaking computers.  This may work in many cases and is often accompanied by logic at the UI layer of applications to block these “bad” characters, but sooner or later someone is going to figure out that other applications allow for them and will want the same.  This often leads to the creation of “cleaner” functions that perform a replace on the strings for every special character that the person writing the function can think of.  The cleaner function will usually grow over time as support requests reveal characters that were missed in the initial cut.  Sooner or later you end up writing your own somewhat functional XML engine. I have never been told by anyone paying me to write code that they would like to buy a somewhat functional XML engine.  My employer/customer’s needs have always been for something that may use XML, but ultimately is functionality that drives business value. I’m not going to build an XML engine. So how can I generate XML that is always well-formed without writing my own engine?  Easy – use one of the ones provided to you for free!  If you’re in a shop that still supports VB6 applications, you can use the DomDocument or MXXMLWriter object (of the two I prefer MXXMLWriter, but I’m not going to fully describe either here).  For .Net Framework applications prior to the 3.5 framework, the code is a little more verbose than I would like, but easy once you understand what pieces are required:             using (StringWriter sw = new StringWriter())             {                 using (XmlTextWriter writer = new XmlTextWriter(sw))                 {                     writer.WriteStartDocument();                     writer.WriteStartElement("Contact");                     writer.WriteElementString("BusinessName", contact.BusinessName);                     writer.WriteEndElement(); // end Contact element                     writer.WriteEndDocument();                     writer.Flush();                     return sw.ToString();                 }             }   Looking at that code, it’s easy to understand why people are drawn to the initial one-liner.  Lucky for us, the 3.5 .Net Framework added the System.Xml.Linq.XElement object.  This object takes away a lot of the complexity present in the XmlTextWriter approach and allows us to generate the document as follows: return new XElement("Contact", new XElement("BusinessName", contact.BusinessName)).ToString();   While it is very common for people to use string manipulation to create XML, I’ve discussed here reasons not to use this method and introduced powerful APIs that are built into the .Net Framework as an alternative.  I’ve given a very simplistic example here to highlight the most basic XML generation task.  For more information on the XmlTextWriter and XElement APIs, check out the MSDN library.

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• Getting current time in milliseconds

  - by user90293423

  How to get the current time in milliseconds? I'm working on a hacking simulation game and when ever someone connects to another computer/NPC, a login screen popups with a button on the side called BruteForce. When BruteForce is clicked, what i want the program to do is, calculate how many seconds cracking the password is going to take based on the player's CPU speed but that's the easy part. The hard part is i want to enter a character in the password's box every X milliseconds based on a TimeToCrack divided by PasswordLength formula. But since i don't know how to find how many milliseconds have elapsed since the second has passed, the program waits until the CurrentTime is higher than the TimeBeforeTheLoopStarted + HowLongItTakesToTypeaCharacter which is always going to be a second. How would you handle my problems? I've commented the game breaking part. std::vector<QString> hardware = user.getHardware(); QString CPU = hardware[0]; unsigned short Speed = 0; if(CPU == "OMG SingleCore 1.8GHZ"){ Speed = 2; } const short passwordLength = password.length(); /* It's equal to 16 */ int Time = passwordLength / Speed; double TypeSpeed = Time / passwordLength; time_t t = time(0); struct tm * now = localtime(&t); unsigned short EndTime = (now->tm_sec + Time) % 60; unsigned short CurrentTime = 0; short i = passwordLength - 1; do{ t = time(0); now = localtime(&t); CurrentTime = now->tm_sec; do{ t = time(0); now = localtime(&t); }while(now->tm_sec < CurrentTime + TypeSpeed); /* Highly flawed */ /* Do this while your integer value is under this double value */ QString tempPass = password; tempPass.chop(i); ui->lineEdit_2->setText(tempPass); i--; }while(CurrentTime != EndTime);

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• alias gcc='gcc -fpermissive' or modifying ./configure script

  - by robo

  I am compiling quite big project from source. The compilation always ends with: error: invalid conversion from ‘const char*’ to ‘char*’ [-fpermissive] I have already compiled this project one year ago. So I know a solution to this. Actualy I found more solutions: Adding a typecast to appropriate line of cpp code (It went to endless number of changes in each file. So I found next solution.) Modifying a makefile to compile that file with -fpermissive option. (I had to modify a lot of lines in each makefile. So I find even better solution.) "g++" or "gcc" was stored in a variable so I added -fpermissive to these variables. This is the best solution I have. It is sufficient to add this option to each makefile once. Unfortunately this software has big number of subdirectories. So I need to modify more than 100 makefiles. It took me whole day one year ago. Is there a way how to do this faster. What about this? alias gcc='gcc -fpermissive' I am not familiar with aliases. But it should be easy to try this. Is the syntax correct? And is this one correct? alias g++='g++ -fpermissive' ? And do I need to export the alias somehow? Will the make program respect the alias? Should I maybe change ./configure script? Or the ./configure.in? Or other file?

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• Customizing user privileges for an account in Windows (xp/vista/7)?

  - by claws

  Hello, I'm a .NET developer and recently learning WINDOWS API. When ever a program starts, my Kaspersky anti-virus says "application belonging to trusted group is trying to set debug previleges". I started wondering what are debug privileges? When ever application tries to open a file (using OpenFileDialog) it gives this message about debug privileges. It sometimes also says the so & so application is trying to read desktop.ini I'm not sure about what exactly it is either. Any way, my concern is about user previlages. When creating user account. We can only set the account to be either Administrative or Limited user. I read in MSDN that there are so many privileges for a user account. http://msdn.microsoft.com/en-us/library/bb530716(VS.85).aspx SE_ASSIGNPRIMARYTOKEN_NAME SE_AUDIT_NAME SE_BACKUP_NAME SE_CHANGE_NOTIFY_NAME SE_CREATE_GLOBAL_NAME SE_CREATE_PAGEFILE_NAME SE_CREATE_PERMANENT_NAME SE_CREATE_SYMBOLIC_LINK_NAME SE_CREATE_TOKEN_NAME SE_DEBUG_NAME SE_ENABLE_DELEGATION_NAME SE_IMPERSONATE_NAME SE_INC_BASE_PRIORITY_NAME SE_INCREASE_QUOTA_NAME SE_INC_WORKING_SET_NAME SE_LOAD_DRIVER_NAME SE_LOCK_MEMORY_NAME SE_MACHINE_ACCOUNT_NAME SE_MANAGE_VOLUME_NAME SE_PROF_SINGLE_PROCESS_NAME SE_RELABEL_NAME SE_REMOTE_SHUTDOWN_NAME SE_RESTORE_NAME SE_SECURITY_NAME SE_SHUTDOWN_NAME SE_SYNC_AGENT_NAME SE_SYSTEM_ENVIRONMENT_NAME SE_SYSTEM_PROFILE_NAME SE_SYSTEMTIME_NAME SE_TAKE_OWNERSHIP_NAME SE_TCB_NAME SE_TIME_ZONE_NAME SE_TRUSTED_CREDMAN_ACCESS_NAME SE_UNDOCK_NAME SE_UNSOLICITED_INPUT_NAME Well, my question is How can I manually (not programatically) set/customize these privileges for a user account? Surprisingly I'm unable to find a PRIVILEGE CONST for registry access. On my lab computer admin has disabled the registry access to my account. Where can I know more information about these information? I use all 3 operating systems (XP, VISTA, 7) :)

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• Compile PHP 5.3.2 with intl extension on Snow Leopard 10.6.3

  - by fsb

  Does anyone have some tips on compiling PHP's intl extension on PHP? I'm getting compile errors each way I try it and I've been googling for ages and getting nowhere. Any help greatly appreciated. When make gets to the huge gcc command to compile libphp5.bundle, I get the following error: Undefined symbols: "___gxx_personality_v0", referenced from: icu_4_2::MessageFormatAdapter::getArgTypeList(icu_4_2::MessageFormat const&, int&)in msgformat_helpers.o _umsg_parse_helper in msgformat_helpers.o _umsg_format_arg_count in msgformat_helpers.o _umsg_format_helper in msgformat_helpers.o CIE in msgformat_helpers.o ld: symbol(s) not found collect2: ld returned 1 exit status make: *** [libs/libphp5.bundle] Error 1 My compile commands are: MACOSX_DEPLOYMENT_TARGET=10.6 CFLAGS="-arch x86_64 -g -Os -pipe -no-cpp-precomp" CCFLAGS="-arch x86_64 -g -Os -pipe" CXXFLAGS="-arch x86_64 -g -Os -pipe" LDFLAGS="-arch x86_64 -bind_at_load" export CFLAGS CXXFLAGS LDFLAGS CCFLAGS MACOSX_DEPLOYMENT_TARGET ./configure --prefix=/usr \ --mandir=/usr/share/man \ --infodir=/usr/share/info \ --sysconfdir=/private/etc \ --with-apxs2=/usr/sbin/apxs \ --enable-cli \ --with-config-file-path=/etc \ --with-libxml-dir=/usr \ --with-openssl=/usr \ --with-zlib=/usr \ --with-bz2=/usr \ --with-curl=/usr \ --with-gd \ --with-jpeg-dir=/src/jpeg/jpeg-local \ --with-png-dir=/usr/X11R6 \ --with-freetype-dir=/usr/X11R6 \ --with-xpm-dir=/usr/X11R6 \ --with-ldap=/usr \ --with-ldap-sasl=/usr \ --enable-mbstring \ --enable-mbregex \ --with-mysql=mysqlnd \ --with-mysqli=mysqlnd \ --with-pdo-mysql=mysqlnd \ --with-mysql-sock=/var/mysql/mysql.sock \ --with-iodbc=/usr \ --enable-shmop \ --with-snmp=/usr \ --enable-soap \ --enable-sockets \ --enable-sysvmsg \ --enable-sysvsem \ --enable-sysvshm \ --with-xmlrpc \ --with-iconv-dir=/usr \ --with-xsl=/usr \ --with-pcre-regex=/src/pcre/pcre-local/usr/local \ --with-pcre-dir=/src/pcre/pcre-local/usr/local \ --with-icu-dir=/usr/local \ --enable-intl export EXTRA_CFLAGS="-lresolv" make

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• Win XP error 0x80041003 using GetObject/winmgmts

  - by John Lewis

  My computer is called "neil" and I want to set some values using WMI in vbScript. I adapetd the script below from one supplied by Microsoft. When I run it in my browser I get Error Type: (0x80041003) /dressage/30/pdf2.asp, line 8 I suspect it is some registry/security setting. Any advice? John Lewis FULL SCRIPT call Print_HTML_Page("http://neil/dressage/ascii.asp", "ascii") Sub SetPDFFile(strPDFFile) Const HKEY_LOCAL_MACHINE = &H80000002 strKeyPath = "SOFTWARE\Dane Prairie Systems\Win2PDF" strComputer = "." Set objReg=GetObject( _ "winmgmts:{impersonationLevel=impersonate}!\\" & _ strComputer & "\root\default:StdRegProv") strValueName = "PDFFileName" objReg.SetExpandedStringValue HKEY_LOCAL_MACHINE,_ strKeyPath,strValueName,strPDFFile End Sub Sub Print_HTML_Page(strPathToPage, strPDFFile) SetPDFFile( strPDFFile ) Set objIE = CreateObject("InternetExplorer.Application") 'From http://www.tek-tips.com/viewthread.cfm?qid=1092473&page=5 On Error Resume Next strPrintStatus = objIE.QueryStatusWB(6) If Err.Number 0 Then MsgBox "Cannot find a printer. Operation aborted." objIE.Quit Set objIE = Nothing Exit Sub End If With objIE .visible=0 .left=200 .top=200 .height=400 .width=400 .menubar=0 .toolbar=1 .statusBar=0 .navigate strPathToPage End With 'Wait until IE has finished loading Do while objIE.busy WScript.Sleep 100 Loop On Error Goto 0 objIE.ExecWB 6,2 'Wait until IE has finished printing WScript.Sleep 2000 objIE.Quit Set objIE = Nothing End Sub

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• Bypassing SQUID on freebsd with PF

  - by epema

  I have PF+SQUID31 on FREEBSD-9.0, and I want to have some hosts(aka goodguys) to bypass the proxy, so that torrents are not logged. Also, I am not sure about transparent. It means that I dont have to configure proxy settings on the client side right? I have tried doing a redirect no rdr on $int_if inet proto {tcp,udp} from 192.168.1.233/32 to any However, no luck :( Here is a quick look of my conf files: SQUID /usr/local/etc/squid/squid.conf http_port 192.168.1.1:8080 transparent RC /etc/rc.conf: gateway_enable="YES" pf_enable="YES" pf_rules="/usr/local/etc/pf.conf" pflog_enable="YES" squid_enable="YES" I have squid31 installed from ports with SQUID_PF "Enable transparent proxying with PF" on PF /usr/loca/etc/pf.conf: int_if="re0" ext_if="bge0" localnet="{ 192.168.1.0/24 }" table <goodguys> const { "192.168.1.219", "192.168.1.233" } set block-policy drop set skip on lo0 scrub in all fragment reassemble scrub out all random-id max-mss 1440 block in on $ext_if pass out on $ext_if keep state block in on $int_if pass in on $int_if inet proto tcp from $int_if:network to $int_if port 8080 keep state pass in on $int_if inet proto udp from $int_if:network to $int_if port 21 keep state pass in on $int_if inet proto udp from $int_if:network to $int_if port 22 keep state pass in on $int_if inet proto udp from $int_if:network to $int_if port 53 keep state pass in on $int_if inet proto tcp from $int_if:network to any port { smtp, pop3 } keep state pass in on $int_if inet proto icmp from $int_if:network to $int_if keep state pass out on $int_if keep state What lines should I add in conf files? I am assuming that the problem is on the firewall(pf).

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• What cause high CPU usage on the server during file upload

  - by bosiang

  When I try to upload a huge file size (approx 2GB), the server cpu usage goes really high. What should I do to fix this? I just use standard html form and php, for file upload. I'm sorry if I post on the wrong forum. Please point me to the right direction here is the result of "top" command during uploading 4 files (18mb, 38mb, 60mb, 33mb) 1904 apache 20 0 33504 5740 1952 R 28.3 0.2 0:02.19 httpd 1905 apache 20 0 33504 5740 1952 R 28.3 0.2 0:01.99 httpd 1903 apache 20 0 33232 6968 3060 R 28.0 0.2 0:01.98 httpd 1910 apache 20 0 33240 6020 2248 S 11.5 0.2 0:02.85 httpd 2133 root 20 0 2656 1124 896 R 1.6 0.0 0:00.71 top 1 root 20 0 2864 1404 1188 S 0.0 0.0 0:03.99 init the code for chunking, although eventhough I don't use this code (just simple file upload), it still cause that high cpu usage function sendRequest() { //clean the screen //bars.innerHTML = ''; var file = document.getElementById('fileToUpload'); for(var i = 0; i < file.files.length; i++) { var blob = file.files[i]; var originalFileName = blob.name; var filePart = 0 const BYTES_PER_CHUNK = 100 * 1024 * 1024; // 10MB chunk sizes. var realFileSize = blob.size; var start = 0; var end = BYTES_PER_CHUNK; totalChunks = Math.ceil(realFileSize / BYTES_PER_CHUNK); alert(realFileSize); while( start < realFileSize ) { if (blob.webkitSlice) { //for Google Chrome var chunk = blob.webkitSlice(start, end); } else if (blob.mozSlice) { //for Mozilla Firefox var chunk = blob.mozSlice(start, end); } uploadFile(chunk, originalFileName, filePart, totalChunks, i); filePart++; start = end; end = start + BYTES_PER_CHUNK; } } }

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• Using GPO to collect data about VMware view activity

  - by MoSiAc

  Our security group wants us to begin logging data for external access to our view enviroment. At first we thought that view security would be logging all source ip's that are external in nature so if for some reason there is an intrusion we would have record of it there. Of course our firewall logs all that information but correlating it to view is sketchy at best with our current implementation. We know on viewdesktops there is a set of keys in VolitateEnviroment that contains stuff such as source ip and username, etc. We have a script in place that, when run as a logon script attached to a user account in AD collects the information as we need it. If we have a GPO run the same script the information does not get collected. We feel like there is a piece of the puzzle we're missing but we don't know what. If anyone knows what we're forgetting or misconfiguring that would be great, or if you have a better way of us collecting external source ip's for view specifically we'd be interested in that as well. Thanks, EDIT CODE Batch script to dump to text file @echo off timeout 20 echo %computername%/%username% %time% %date% c:\vdi\vmware.txt echo ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~c:\vdi\vmware.txt reg query "HKEY_CURRENT_USER\Volatile Environment" /v "ViewClient_LoggedOn_Username"c:\vdi\vmware.txt reg query "HKEY_CURRENT_USER\Volatile Environment" /v "ViewClient_IP_Address"c:\vdi\vmware.txt echo.c:\vdi\vmware.txt VB Script to display values Const HKEY_CURRENT_USER = &H80000001 Set wmiLocator=CreateObject("WbemScripting.SWbemLocator") Set wmiNameSpace = wmiLocator.ConnectServer(".", "root\default") Set objRegistry = wmiNameSpace.Get("StdRegProv") sPath = "Volatile Environment" lRC = objRegistry.GetStringValue(HKEY_CURRENT_USER, sPath, "ViewClien_Machine_Name", vMachine) lRC = objRegistry.GetStringValue(HKEY_CURRENT_USER, sPath, "ViewClien_IP_Address", vIP) lRC = objRegistry.GetStringValue(HKEY_CURRENT_USER, sPath, "ViewClien_MAC_Address", vMAC) msgbox "The Remote Device Name is " & vMachine & " @ " & vIP & " (" & vMAC & ") " he wanted me to mention that the batch file actually runs and I can see it counting down when I reconnect but it does not grab the registry values.

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• Using MVVM, how to pass SelectedItems of a XamDataGrid as parameter to the Command raised by the Co

  - by saddaypally

  Hi, I'm trying to pass the item on XamDataGrid on which I do a mouse right click to open a ContextMenu, which raises a Command in my ViewModel. Somehow the method that the Command calls is not reachable in debug mode. This is the snipped from the view <ig:XamDataGrid DataSource="{Binding DrdResults}" Height="700" Width="600"> <ig:XamDataGrid.ContextMenu> <ContextMenu DataContext="{Binding RelativeSource={RelativeSource Mode=Self}, Path=PlacementTarget.DataContext}" AllowDrop="True" Name="cmAudit"> <MenuItem Header="View History" Command="{Binding ViewTradeHistory}" CommandParameter="{Binding Path=SelectedItems}"> </MenuItem> </ContextMenu> </ig:XamDataGrid.ContextMenu> <ig:XamDataGrid.FieldSettings> <ig:FieldSettings AllowFixing="NearOrFar" AllowEdit="False" Width="auto" Height="auto" /> </ig:XamDataGrid.FieldSettings> </ig:XamDataGrid> My code in the corresponding ViewModel for this View is as follows public WPF.ICommand ViewTradeHistory { get { if (_viewTradeHistory == null) { _viewTradeHistory = new DelegateCommand( (object SelectedItems) = { this.OpenTradeHistory(SelectedItems); }); } return _viewTradeHistory; } } And lastly the actual method that gets called by the Command is as below private void OpenTradeHistory(object records) { DataPresenterBase.SelectedItemHolder auditRecords = (DataPresenterBase.SelectedItemHolder)records; // Do something with the auditRecords now. } I'm not sure what am I doing incorrectly here. Any help will be very much appreciated. Thanks, Shravan

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• Iterate over rows/checkboxes in a RadGrid

  - by ChessWhiz

  Hi, I have a Telerik RadGrid with a GridTemplateColumn that contains a checkbox, as follows: <telerik:GridTemplateColumn HeaderText="MINE" UniqueName="MyTemplateColumn"> <ItemTemplate> <asp:CheckBox id="MyCheckBox" runat="server"></asp:CheckBox> </ItemTemplate> </telerik:GridTemplateColumn> I want to set the box to be "checked" based on a value read from the database. I could handle the ItemDataBound event and read the database when each row is bound, but that results in n lookups. Instead, I want to handle DataBound, and then set all the values at once. So, in that method, I want code like this: // read all values from database first, then... foreach(var chkbox in MyRadGrid.MasterTableView.Columns.FindByUniqueName("MyTemplateColumn").FindControl("MyCheckBox")) { chkbox.Checked = oneValue; } That doesn't work, because FindControl isn't a method of GridColumn, and it won't generate an iterable list of the checkboxes. What is the correct way to iterate through the checkboxes in the template column? Thanks!

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• Is it possible for a WPF control to have an ActualWidth and ActualHeight if it has never been render

  - by DanM

  I need a Viewport3D for the sole purpose of doing geometric calculations using Petzold.Media3D.ViewportInfo. I do now want to place it in a Window. I'm creating a Viewport3D using the following code: private Viewport3D CreateViewport(MainSettings settings) { var cameraPosition = new Point3D(0, 0, settings.CameraHeight); var cameraLookDirection = new Vector3D(0, 0, -1); var cameraUpDirection = new Vector3D(0, 1, 0); var camera = new PerspectiveCamera { Position = cameraPosition, LookDirection = cameraLookDirection, UpDirection = cameraUpDirection }; var viewport = new Viewport3D { Camera = camera, Width = settings.ViewportWidth, Height = settings.ViewportHeight }; return viewport; } Later, I'm attempting to use this viewport to convert the mouse location to a 3D location using this method: public Point3D? Point2dToPoint3d(Point point) { var range = new LineRange(); var isValid = ViewportInfo.Point2DtoPoint3D(_viewport, point, out range); if (isValid) return range.PointFromZ(0); else return null; } Unfortunately, it's not working. I think the reason is that the ActualWidth and ActualHeight of the viewport and both zero (and these are read-only properties, so I can't set them manually). (I have tested the exact same with an actual rendered Viewport3D, so I know the issue is not with my converter method.) Any idea how I can get WPF to assign the ActualWidth and ActualHeight based on my Width and Height settings? I tried setting the HorizontalAlignment and VerticalAlignment to Left and Top, respectively, and I also messed with the MinWidth and MinHeight, but none of these properties had any effect on the ActualWidth or ActualHeight.

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• Encryption is hard: AES encryption to Hex

  - by Rob Cameron

  So, I've got an app at work that encrypts a string using ColdFusion. ColdFusion's bulit-in encryption helpers make it pretty simple: encrypt('string_to_encrypt','key','AES','HEX') What I'm trying to do is use Ruby to create the same encrypted string as this ColdFusion script is creating. Unfortunately encryption is the most confusing computer science subject known to man. I found a couple helper methods that use the openssl library and give you a really simple encryption/decryption method. Here's the resulting string: "\370\354D\020\357A\227\377\261G\333\314\204\361\277\250" Which looks unicode-ish to me. I've tried several libraries to convert this to hex but they all say it contains invalid characters. Trying to unpack it results in this: string = "\370\354D\020\357A\227\377\261G\333\314\204\361\277\250" string.unpack('U') ArgumentError: malformed UTF-8 character from (irb):19:in `unpack' from (irb):19 At the end of the day it's supposed to look like this (the output of the ColdFusion encrypt method): F8E91A689565ED24541D2A0109F201EF Of course that's assuming that all the padding, initialization vectors, salts, cypher types and a million other possible differences all line up. Here's the simple script I'm using to encrypt/decrypt: def aes(m,k,t) (aes = OpenSSL::Cipher::Cipher.new('aes-256-cbc').send(m)).key = Digest::SHA256.digest(k) aes.update(t) << aes.final end def encrypt(key, text) aes(:encrypt, key, text) end def decrypt(key, text) aes(:decrypt, key, text) end Any help? Maybe just a simple option I can pass to OpenSSL::Cipher::Cipher that will tell it to hex-encode the final string?

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• Deleting file with SharePoint List web service fails

  - by Robert MacLean

  I am trying to delete a file from SharePoint using the list web service which is failing with the following error. Error Code: 0x81020030 Message: Invalid file name Detail: The file name you specified could not be used. It may be the name of an existing file or directory, or you may not have permission to access the file. The update XML I sent through is: <Batch OnError="Continue" PreCalc="TRUE" ListVersion="0" ViewName="{8FE4E2C8-939E-4462-ABA2-D633EED7F76E}"><Method ID="1" Cmd="Delete"><Field Name="ID">84</Field><Field Name="FileRef">http://win-4h0xp59sn75:40414/Shared%20Documents/del.txt</Field></Method></Batch> The SharePoint server error logs indicate: ERROR: Failed to OpenThreadToken, LastError=1008 The file you are attempting to save or retrieve has been blocked from this Web site by the server administrators. Things I have tried I've tried the changes in #1372971 which has no helped. I have also tried the changes recommended on the Microsoft Social site, which has also not helped. I have confirmed that the txt file extension is not blocked as indicated here. In addition I can remove the file via the website, it is just on the web service that this fails. The permissions are correct (or rather not in play) as I am running as a SharePoint administrator, which is the same account that uploaded it via the copy web service.

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• Reactive Extensions vs FileSystemWatcher

  - by Joel Mueller

  One of the things that has long bugged me about the FileSystemWatcher is the way it fires multiple events for a single logical change to a file. I know why it happens, but I don't want to have to care - I just want to reparse the file once, not 4-6 times in a row. Ideally, there would be an event that only fires when a given file is done changing, rather than every step along the way. Over the years I've come up with various solutions to this problem, of varying degrees of ugliness. I thought Reactive Extensions would be the ultimate solution, but there's something I'm not doing right, and I'm hoping someone can point out my mistake. I have an extension method: public static IObservable<IEvent<FileSystemEventArgs>> GetChanged(this FileSystemWatcher that) { return Observable.FromEvent<FileSystemEventArgs>(that, "Changed"); } Ultimately, I would like to get one event per filename, within a given time period - so that four events in a row with a single filename are reduced to one event, but I don't lose anything if multiple files are modified at the same time. BufferWithTime sounds like the ideal solution. var bufferedChange = watcher.GetChanged() .Select(e => e.EventArgs.FullPath) .BufferWithTime(TimeSpan.FromSeconds(1)) .Where(e => e.Count > 0) .Select(e => e.Distinct()); When I subscribe to this observable, a single change to a monitored file triggers my subscription method four times in a row, which rather defeats the purpose. If I remove the Distinct() call, I see that each of the four calls contains two identical events - so there is some buffering going on. Increasing the TimeSpan passed to BufferWithTime seems to have no effect - I went as high as 20 seconds without any change in behavior. This is my first foray into Rx, so I'm probably missing something obvious. Am I doing it wrong? Is there a better approach? Thanks for any suggestions...

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• CA2000 passing object reference to base constructor in C#

  - by Timothy

  I receive a warning when I run some code through Visual Studio's Code Analysis utility which I'm not sure how to resolve. Perhaps someone here has come across a similar issue, resolved it, and is willing to share their insight. I'm programming a custom-painted cell used in a DataGridView control. The code resembles: public class DataGridViewMyCustomColumn : DataGridViewColumn { public DataGridViewMyCustomColumn() : base(new DataGridViewMyCustomCell()) { } It generates the following warning: CA2000 : Microsoft.Reliability : In method 'DataGridViewMyCustomColumn.DataGridViewMyCustomColumn()' call System.IDisposable.Dispose on object 'new DataGridViewMyCustomCell()' before all references to it are out of scope. I understand it is warning me DataGridViewMyCustomCell (or a class that it inherits from) implements the IDisposable interface and the Dispose() method should be called to clean up any resources claimed by DataGridViewMyCustomCell when it is no longer. The examples I've seen on the internet suggest a using block to scope the lifetime of the object and have the system automatically dispose it, but base isn't recognized when moved into the body of the constructor so I can't write a using block around it... which I'm not sure I'd want to do anyway, since wouldn't that instruct the run time to free the object which could still be used later inside the base class? My question then, is the code okay as is? Or, how could it be refactored to resolve the warning? I don't want to suppress the warning unless it is truly appropriate to do so.

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• Spring Framework 3 and session attributes

  - by newbie

  I have form object that I set to request in GET request handler in my Spring controller. First time user enters to page, a new form object should be made and set to request. If user sends form, then form object is populated from request and now form object has all user givern attributes. Then form is validated and if validation is ok, then form is saved to database. If form is not validated, I want to save form object to session and then redirect to GET request handling page. When request is redirected to GET handler, then it should check if session contains form object. I have figured out that there is @SessionAttributes("form") annotation in Spring, but for some reason following doesnt work, because at first time, session attribute form is null and it gives error: org.springframework.web.HttpSessionRequiredException: Session attribute 'form' required - not found in session Here is my controller: @RequestMapping(value="form", method=RequestMethod.GET) public ModelAndView viewForm(@ModelAttribute("form") Form form) { ModelAndView mav = new ModelAndView("form"); if(form == null) form = new Form(); mav.addObject("form", form); return mav; } @RequestMapping(value="form", method=RequestMethod.POST) @Transactional(readOnly = true) public ModelAndView saveForm(@ModelAttribute("form") Form form) { FormUtils.populate(form, request); if(form.validate()) { formDao.save(); } else { return viewForm(form); } return null; }

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