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• MSTest unit test passes by itself, fails when other tests are run

  - by Sarah Vessels

  I'm having trouble with some MSTest unit tests that pass when I run them individually but fail when I run the entire unit test class. The tests test some code that SLaks helped me with earlier, and he warned me what I was doing wasn't thread-safe. However, now my code is more complicated and I don't know how to go about making it thread-safe. Here's what I have: public static class DLLConfig { private static string _domain; public static string Domain { get { return _domain = AlwaysReadFromFile ? readCredentialFromFile(DOMAIN_TAG) : _domain ?? readCredentialFromFile(DOMAIN_TAG); } } } And my test is simple: string expected = "the value I know exists in the file"; string actual = DLLConfig.Domain; Assert.AreEqual(expected, actual); When I run this test by itself, it passes. When I run it alongside all the other tests in the test class (which perform similar checks on different properties), actual is null and the test fails. I note this is not a problem with a property whose type is a custom Enum type; maybe I'm having this problem with the Domain property because it is a string? Or maybe it's a multi-threaded issue with how MSTest works?

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• Anonymous union definition/declaration in a macro GNU vs VS2008

  - by Alan_m

  I am attempting to alter an IAR specific header file for a lpc2138 so it can compile with Visual Studio 2008 (to enable compatible unit testing). My problem involves converting register definitions to be hardware independent (not at a memory address) The "IAR-safe macro" is: #define __IO_REG32_BIT(NAME, ADDRESS, ATTRIBUTE, BIT_STRUCT) \ volatile __no_init ATTRIBUTE union \ { \ unsigned long NAME; \ BIT_STRUCT NAME ## _bit; \ } @ ADDRESS //declaration //(where __gpio0_bits is a structure that names //each of the 32 bits as P0_0, P0_1, etc) __IO_REG32_BIT(IO0PIN,0xE0028000,__READ_WRITE,__gpio0_bits); //usage IO0PIN = 0x0xAA55AA55; IO0PIN_bit.P0_5 = 0; This is my comparable "hardware independent" code: #define __IO_REG32_BIT(NAME, BIT_STRUCT)\ volatile union \ { \ unsigned long NAME; \ BIT_STRUCT NAME##_bit; \ } NAME; //declaration __IO_REG32_BIT(IO0PIN,__gpio0_bits); //usage IO0PIN.IO0PIN = 0xAA55AA55; IO0PIN.IO0PIN_bit.P0_5 = 1; This compiles and works but quite obviously my "hardware independent" usage does not match the "IAR-safe" usage. How do I alter my macro so I can use IO0PIN the same way I do in IAR? I feel this is a simple anonymous union matter but multiple attempts and variants have proven unsuccessful. Maybe the IAR GNU compiler supports anonymous unions and vs2008 does not. Thank you.

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• VB.net httpwebrequest For loop hangs every 10 or so iterations

  - by user574632

  Hello, I am trying to loop through an array and perform an httpwebrequest in each iteration. The code seems to work, however it pauses for a while (eg alot longer than the set timeout. Tried setting that to 100 to check and it still pauses) after every 10 or so iterations, then carries on working. Here is what i have so far: For i As Integer = 0 To numberOfProxies - 1 Try 'create request to a proxyJudge php page using proxy Dim request As HttpWebRequest = HttpWebRequest.Create("http://www.pr0.net/deny/azenv.php") request.Proxy = New Net.WebProxy(proxies(i)) 'select the current proxie from the proxies array request.Timeout = 10000 'set timeout Dim response As HttpWebResponse = request.GetResponse() Dim sr As StreamReader = New StreamReader(response.GetResponseStream()) Dim pageSourceCode As String = sr.ReadToEnd() 'check the downloaded source for certain phrases, each identifies a type of proxy 'HTTP_X_FORWARDED_FOR identifies a transparent proxy If pageSourceCode.Contains("HTTP_X_FORWARDED_FOR") Then 'delegate method for cross thread safe UpdateListbox(ListBox3, proxies(i)) ElseIf pageSourceCode.Contains("HTTP_VIA") Then UpdateListbox(ListBox2, proxies(i)) Else UpdateListbox(ListBox1, proxies(i)) End If Catch ex As Exception 'MessageBox.Show(ex.ToString) used in testing UpdateListbox(ListBox4, proxies(i)) End Try completedProxyCheck += 1 lblTotalProxiesChecked.CustomInvoke(Sub(l) l.Text = completedProxyCheck) Next I have searched all over this site and via google, and most responses to this type of question say the response must be closed. I have tried a using block, eg: Using response As HttpWebResponse = request.GetResponse() Using sr As StreamReader = New StreamReader(response.GetResponseStream()) Dim pageSourceCode As String = sr.ReadToEnd() 'check the downloaded source for certain phrases, each identifies a type of proxy 'HTTP_X_FORWARDED_FOR identifies a transparent proxy If pageSourceCode.Contains("HTTP_X_FORWARDED_FOR") Then 'delegate method for cross thread safe UpdateListbox(ListBox3, proxies(i)) ElseIf pageSourceCode.Contains("HTTP_VIA") Then UpdateListbox(ListBox2, proxies(i)) Else UpdateListbox(ListBox1, proxies(i)) End If End Using End Using And it makes no difference (though i may have implemented it wrong) As you can tell im very new to VB or any OOP so its probably a simple problem but i cant work it out. Any suggestions or just tips on how to diagnose these types of problems would be really appreciated.

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• BackgroundWorker and instance variables

  - by Alastair Pitts

  One thing that's always confused me is how a BackgroundWorker seems to have thread-safe access to the instance variables of the surrounding class. Given a basic class: public class BackgroundProcessor { public List<int> Items { get; private set; } public BackgroundProcessor(IEnumerable<int> items) { Items = new List<int>(items); } public void DoWork() { BackgroundWorker worker = new BackgroundWorker(); worker.RunWorkerCompleted += new RunWorkerCompletedEventHandler(worker_RunWorkerCompleted); worker.DoWork += new DoWorkEventHandler(worker_DoWork); worker.RunWorkerAsync(); } void worker_DoWork(object sender, DoWorkEventArgs e) { var processor = new ProcessingClass(); processor.Process(this.Points); //Accessing the instance variable } void worker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e) { //Stuff goes here } } Am I erroneous in my assumption the the call to processor.Process(this.Points); is a thread-safe call? How don't I get a cross-thread access violation? I'm sure it's obvious, but it always has confused me.

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• Change classes instantiated with loadNibNamed

  - by Nick H247

  I am trying to change the class of objects created with a nib with the iPhone SDK. The reason for this is; i dont know until runtime what the class is that i want the nib object to be (though they will have the same UIView based super class), and i dont want to create a different nib for every eventuality - as the .nib will be the same for each, apart from the class of one object. I have been successful, with a couple of methods, but either have some knock on effects or am unsure of how safe the methods I have used are: Method 1: Override alloc, on the super class and set a c variable to the class I require: + (id) alloc { if (theClassIWant) { id object = [theClassIWant allocWithZone:NSDefaultMallocZone()]; theClassIWant = nil; return object; } return [BaseClass allocWithZone:NSDefaultMallocZone()]; } this works well, and i assume is 'reasonably' safe, though if I alloc a subclass myself (without setting 'theClassIWant') - an object of the base class is created. I also dont really like the idea of overriding alloc... Method 2: use object_setClass(self,theClassIWant) in initWithCoder (before calling initWithCoder on the super class): - (id) initWithCoder:(NSCoder *)aDecoder { if (theClassIWant) { // the framework doesn't like this: //[self release]; //self = [theClassIWant alloc]; // whoa now! object_setClass(self,theClassIWant); theClassIWant = nil; return [self initWithCoder:aDecoder]; } if (self = [super initWithCoder:aDecoder]) { ... this also works well, but not all the subclasses are necessarily going to be the same size as the super class, so this could be very unsafe! To combat this i tried releasing and re-allocing to the correct type within initWithCoder, but i got the following error from the framework: "This coder requires that replaced objects be returned from initWithCoder:" dont quite get what this means! i am replacing an object in initWithCoder... Any comments on the validity of these methods, or suggestions of improvements or alternatives welcome!

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• Can threads safely read variables set by VCL events?

  - by Tom1952

  Is it safe for a thread to READ a variable set by a Delphi VCL event? When a user clicks on a VCL TCheckbox, the main thread sets a boolean to the checkbox's Checked state. CheckboxState := CheckBox1.Checked; At any time, a thread reads that variable if CheckBoxState then ... It doesn't matter if the thread "misses" a change to the boolean, because the thread checks the variable in a loop as it does other things. So it will see the state change eventually... Is this safe? Or do I need special code? Is surrounding the read and write of the variable (in the thread and main thread respectively) with critical code calls necessary and sufficient? As I said, it doesn't matter if the thread gets the "wrong" value, but I keep thinking that there might be a low-level problem if one thread tries to read a variable while the main thread is in the middle of writing it, or vice versa. My question is similar to this one: http://stackoverflow.com/questions/1353096/cross-thread-reading-of-a-variable. (Also related to my previous question: http://stackoverflow.com/questions/2449183/using-entercriticalsection-in-thread-to-update-vcl-label)

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• How to Send Headers Through PHP Proxy?

  - by blabus

  Okay, so I have an issue with an AJAX request. I currently have this URL: http://www.google.com/images?hl=en&safe=off&gbv=2&tbs=isch%3A1&sa=1&q=cars+imagesize%3A500x500&aq=f&aqi=&aql=&oq=&gs_rfai=&start=0 I then pass it to my proxy script by modifying the string to this: proxy.php?url=http://www.google.com/images?hl=en&safe=off&gbv=2&tbs=isch%3A1&sa=1&q=cars+imagesize%3A500x500&aq=f&aqi=&aql=&oq=&gs_rfai=&start=0 I need to use the PHP proxy script to grab that page's HTML so that I can then parse through it with javascript. However, the problem is that the headers in that URL are also being sent to the proxy script, and as a result, I get a 'malformed or illegal request' error. I'm pretty sure the two different sets of headers are the problem, because if I just replace the original URL string with 'http://wwww.google.com', the proxy returns the HTML of the page correctly. So basically, I don't know how to fix this. I'm a complete PHP noob, and I tried escaping the original URL before I appended it to the 'proxy.php?url=', but that doesn't fix anything. Any ideas? Thanks!

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• MS hotfix delayed delivery.

  - by MOE37x3

  I just requested a hotfix from support.microsoft.com and put in my email address, but I haven't received the email yet. The splash page I got after I requested the hotfix said: Hotfix Confirmation We will send these hotfixes to the following e-mail address: (my correct email address) Usually, our hotfix e-mail is delivered to you within five minutes. However, sometimes unforeseen issues in e-mail delivery systems may cause delays. We will send the e-mail from the “[email protected]” e-mail account. If you use an e-mail filter or a SPAM blocker, we recommend that you add “[email protected]” or the “microsoft.com” domain to your safe senders list. (The safe senders list is also known as a whitelist or an approved senders list.) This will help prevent our e-mail from going into your junk e-mail folder or being automatically deleted. I'm sure that the email is not getting caught in a spam catcher. How long does it normally take to get one of these hotfixes? Am I waiting for some human to approve it, or something? Should I just give up and try to get the file I need some other way? (Update: Replaced "[email protected]" with "(my correct email address)" to resolve Martín Marconcini's ambiguity.)

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• Achieving Thread-Safety

  - by Smasher

  Question How can I make sure my application is thread-safe? Are their any common practices, testing methods, things to avoid, things to look for? Background I'm currently developing a server application that performs a number of background tasks in different threads and communicates with clients using Indy (using another bunch of automatically generated threads for the communication). Since the application should be highly availabe, a program crash is a very bad thing and I want to make sure that the application is thread-safe. No matter what, from time to time I discover a piece of code that throws an exception that never occured before and in most cases I realize that it is some kind of synchronization bug, where I forgot to synchronize my objects properly. Hence my question concerning best practices, testing of thread-safety and things like that. mghie: Thanks for the answer! I should perhaps be a little bit more precise. Just to be clear, I know about the principles of multithreading, I use synchronization (monitors) throughout my program and I know how to differentiate threading problems from other implementation problems. But nevertheless, I keep forgetting to add proper synchronization from time to time. Just to give an example, I used the RTL sort function in my code. Looked something like FKeyList.Sort (CompareKeysFunc); Turns out, that I had to synchronize FKeyList while sorting. It just don't came to my mind when initially writing that simple line of code. It's these thins I wanna talk about. What are the places where one easily forgets to add synchronization code? How do YOU make sure that you added sync code in all important places?

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• List of fonts installed by default in versions of Windows?

  - by Ricket

  I've been seeing more and more websites using fancy antialiased fonts. Every time I hit one, I think to myself "hmm, what web-safe font is that?" - but after looking at the CSS I typically find some font name in quotes, like "Palatino Linotype". Obviously not web-safe, but according to the Wikipedia article, "Palatino Linotype is shipped with Windows 2000 or later, and Microsoft Office Professional Edition 2003." So that covers what, 95% of users that might visit your website? And thanks to the power of CSS, the website can fallback to a similar generic font typename such as 'serif' for non-Windows users with a line like this: font: 16px/20px "Palatino Linotype", serif; Awesome! I want to start using fancy fonts! Is there a set of lists out there, of the fonts that are preinstalled by default in Windows 98, 2000, NT, ME, XP, 2003, etc., and maybe for the Mac OSX versions and various Linux distributions as well? It would be a great reference for picking web font faces! (if not, someone should compile it!) I had never before heard of Palatino Linotype and I want to know what other fonts have existed since old Windows versions that I've never known about!

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• How to benchmark on multi-core processors

  - by Pascal Cuoq

  I am looking for ways to perform micro-benchmarks on multi-core processors. Context: At about the same time desktop processors introduced out-of-order execution that made performance hard to predict, they, perhaps not coincidentally, also introduced special instructions to get very precise timings. Example of these instructions are rdtsc on x86 and rftb on PowerPC. These instructions gave timings that were more precise than could ever be allowed by a system call, allowed programmers to micro-benchmark their hearts out, for better or for worse. On a yet more modern processor with several cores, some of which sleep some of the time, the counters are not synchronized between cores. We are told that rdtsc is no longer safe to use for benchmarking, but I must have been dozing off when we were explained the alternative solutions. Question: Some systems may save and restore the performance counter and provide an API call to read the proper sum. If you know what this call is for any operating system, please let us know in an answer. Some systems may allow to turn off cores, leaving only one running. I know Mac OS X Leopard does when the right Preference Pane is installed from the Developers Tools. Do you think that this make rdtsc safe to use again? More context: Please assume I know what I am doing when trying to do a micro-benchmark. If you are of the opinion that if an optimization's gains cannot be measured by timing the whole application, it's not worth optimizing, I agree with you, but I cannot time the whole application until the alternative data structure is finished, which will take a long time. In fact, if the micro-benchmark were not promising, I could decide to give up on the implementation now; I need figures to provide in a publication whose deadline I have no control over.

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• Thread-safty of boost RNG

  - by Maciej Piechotka

  I have a loop which should be nicely pararellized by insering one openmp pragma: boost::normal_distribution<double> ddist(0, pow(retention, i - 1)); boost::variate_generator<gen &, BOOST_TYPEOF(ddist)> dgen(rng, ddist); // Diamond const std::uint_fast32_t dno = 1 << i - 1; // #pragma omp parallel for for (std::uint_fast32_t x = 0; x < dno; x++) for (std::uint_fast32_t y = 0; y < dno; y++) { const std::uint_fast32_t diff = size/dno; const std::uint_fast32_t x1 = x*diff, x2 = (x + 1)*diff; const std::uint_fast32_t y1 = y*diff, y2 = (y + 1)*diff; double avg = (arr[x1][y1] + arr[x1][y2] + arr[x2][y1] + arr[x2][y2])/4; arr[(x1 + x2)/2][(y1 + y2)/2] = avg + dgen(); } (unless I make an error each execution does not depend on others at all. Sorry that not all of code is inserted). However my question is - are boost RNG thread-safe? They seems to refer to gcc code for gcc so even if gcc code is thread-safe it may not be the case for other platforms.

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• Socket Read In Multi-Threaded Application Returns Zero Bytes or EINTR (-1)

  - by user309670

  Hi. Am a c-coder for a while now - neither a newbie nor an expert. Now, I have a certain daemoned application in C on a PPC Linux. I use PHP's socket_connect as a client to connect to this service locally. The server uses epoll for concurrent connections via a Unix socket. A user submitted string is parsed for certain characters/words using strstr() and if found, spawns 4 joinable threads to different websites simultaneously. I use socket, connect, write and read, to interact with the said webservers via TCP on port 80 in each thread. All connections and writes seems successful. Reads to the webserver sockets fail however, with either (A) all 3 threads seem to hang, and only one thread returns -1 and errno is set to 104. The responding thread takes like 10 minutes - an eternity long:-(. *I read somewhere that the 104 (is EINTR) suggests that ...'the connection was reset by peer', or (B) 0 bytes from 3 threads, and only 1 of the 4 threads actually returns some data. Isn't the socket read/write thread-safe? Otherwise, use thread-safe (and reentrant) libc functions such as strtok_r, gethostbyname_r, etc. *I doubt that the said webhosts are actually resetting the connection, because when I run a single-threaded standalone (everything else equal) all things works perfectly right. There's a second problem too (oops), I can't write back to the client who connect to my epoll-ed Unix socket. My daemon application will hang and hog CPU 100% for ever. Yet nothing is written to the clients end. Am sure the client (a very typical PHP socket application) hasn't closed the connection whenever this is happening - no error(s) detected either. I cannot figure-out whatever is wrong even with Valgrind or GDB

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• Thread-safety of read-only memory access

  - by Edmund

  I've implemented the Barnes-Hut gravity algorithm in C as follows: Build a tree of clustered stars. For each star, traverse the tree and apply the gravitational forces from each applicable node. Update the star velocities and positions. Stage 2 is the most expensive stage, and so is implemented in parallel by dividing the set of stars. E.g. with 1000 stars and 2 threads, I have one thread processing the first 500 stars and the second thread processing the second 500. In practice this works: it speeds the computation by about 30% with two threads on a two-core machine, compared to the non-threaded version. Additionally, it yields the same numerical results as the original non-threaded version. My concern is that the two threads are accessing the same resource (namely, the tree) simultaneously. I have not added any synchronisation to the thread workers, so it's likely they will attempt to read from the same location at some point. Although access to the tree is strictly read-only I am not 100% sure it's safe. It has worked when I've tested it but I know this is no guarantee of correctness! Questions Do I need to make a private copy of the tree for each thread? Even if it is safe, are there performance problems of accessing the same memory from multiple threads?

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• What exactly is a reentrant function?

  - by eSKay

  Most of the times, the definition of reentrance is quoted from Wikipedia: A computer program or routine is described as reentrant if it can be safely called again before its previous invocation has been completed (i.e it can be safely executed concurrently). To be reentrant, a computer program or routine: Must hold no static (or global) non-constant data. Must not return the address to static (or global) non-constant data. Must work only on the data provided to it by the caller. Must not rely on locks to singleton resources. Must not modify its own code (unless executing in its own unique thread storage) Must not call non-reentrant computer programs or routines. How is safely defined? If a program can be safely executed concurrently, does it always mean that it is reentrant? What exactly is the common thread between the six points mentioned that I should keep in mind while checking my code for reentrant capabilities? Also, Are all recursive functions reentrant? Are all thread-safe functions reentrant? Are all recursive and thread-safe functions reentrant? While writing this question, one thing comes to mind: Are the terms like reentrance and thread safety absolute at all i.e. do they have fixed concrete definations? For, if they are not, this question is not very meaningful. Thanks!

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• php Warning: strtotime() Error

  - by Kavithanbabu

  I have changed my joomla and wordpress files from old server to new server. In the front end and admin side its working without any errors. But in the Database (phpmyadmin) Section it shows some warning messages like this.. Warning: strtotime() [function.strtotime]: It is not safe to rely on the system's timezone settings. You are *required* to use the date.timezone setting or the date_default_timezone_set() function. In case you used any of those methods and you are still getting this warning, you most likely misspelled the timezone identifier. We selected 'Asia/Calcutta' for 'IST/5.0/no DST' instead in /usr/share/phpmyadmin/libraries/db_info.inc.php on line 88 Warning: strftime() [function.strftime]: It is not safe to rely on the system's timezone settings. You are *required* to use the date.timezone setting or the date_default_timezone_set() function. In case you used any of those methods and you are still getting this warning, you most likely misspelled the timezone identifier. We selected 'Asia/Calcutta' for 'IST/5.0/no DST' instead in /usr/share/phpmyadmin/libraries/common.lib.php on line 1483 Can you please suggest, how to hide these warning messages?? Thanks in advance.

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• Error loading il8n console in CakePHP 1.3

  - by inkedmn

  I'm trying to generate the .po files for the site I'm working with. When I run this command from within the console directory: Warning: strtotime(): It is not safe to rely on the system's timezone settings. You are *required* to use the date.timezone setting or the date_default_timezone_set() function. In case you used any of those methods and you are still getting this warning, you most likely misspelled the timezone identifier. We selected 'America/Los_Angeles' for 'PDT/-7.0/DST' instead in /Users/bkelly/Development/[redacted]/www/trunk/about/trunk/cake/libs/cache.php on line 570 Warning: strtotime(): It is not safe to rely on the system's timezone settings. You are *required* to use the date.timezone setting or the date_default_timezone_set() function. In case you used any of those methods and you are still getting this warning, you most likely misspelled the timezone identifier. We selected 'America/Los_Angeles' for 'PDT/-7.0/DST' instead in /Users/bkelly/Development/[redacted]/www/trunk/about/trunk/cake/libs/cache.php on line 570 Error: Class Il8nShell could not be loaded. This also happens if I issue ./cake il8n help . The bake console seems to load fine (no errors, takes me to the expected menu). I'm running CakePHP 1.3.0 under Mac OSX 10.6 (using MAMP). Cake appears to be functioning normally otherwise. Thanks!

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• Casting pointer to object to void * in C++

  - by JB

  I've been reading StackOverflow too much and started doubting all the code I've ever written, I keep thinking "Is that undefined behavour?" even in code that has been working for ages. So my question - Is it safe and well defined behavour to cast a pointer to an object (In this case abstract interface classes) to a void* and then later on cast them back to the original class and call method using them? I'm fully aware that the code that does this is probably awful. I wouldn't even consider writing it like this now (this is old code which I don't really want to change), so I'm not looking for a discussion of better ways to do this. I already know how to write it better if I ever did this again. But if it's actually broken to rely on this in C++ then I'll have to look at changing the code, if it's merely awful code then changing it won't be a priority. I would have had no doubts about something this simple a year or two ago but as my understanding of C++ increases I actually find I have more and more worries about code being safe under the standards even if it works perfectly well. Perhaps reading too much stack overflow is a bad thing for productivity sometimes :P

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• APC decreasing php performance??? (php 5.3, apache 2.2, windows vista 64bit)

  - by M.M.

  Hi, I have an Apache/2.2.15 (VC9) and PHP/5.3.2 (VC9 thread safe) running as an apache module on Vista 64bit machine. All running fine. Project that I'm benchmarking (with apache's ab utility) is basically standard Zend Framework project with no db connection involved. Average (median) apache response is about 0.15 seconds. After I've installed APC (3.1.4-dev VC9 thread safe) with standard settings suddenly the request response time raised to 1.3 seconds (!), which is unacceptable... All apc settings looked always good (through the apc.php script: enough shm memory, no cache full, fragmentation 0%). Only difference was to disable the stats lookup (apc.stat = 0). Then the response dropped to 0.09 seconds which was finally better than without the apc. IIRC, it's expected and obvious that the stat lookup creates some overhead, but shouldn't it still be far more performant compared to running wihout the apc extension at all? Or put it differently why is the apc.stat creating so much overhead? Apparently, something is not working as it should, I don't really know where to start looking. Thank you for your time/answers/direction in advance. Cheers, m.

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• Using multiple Qt (SQL) Models

  - by radix07

  I have a near real-time application that I am using Qt and an SQLite database to run. I am curious if it is safe to have two separate models access a database at once. I know 2 separate views can access a model just fine, but I can't find any document addressing this. I also realize that SQLite is thread safe for reading, so I don't see a real issue to doing this from the SQLite part of things... Basically I want to use a QSqlTableModel to do the real-time read and write in the background and at the same time use a QSqlQueryModel to give the user desired data. Since I may be doing lots of filtering in the background using the table model I can't use it as the main view as well. I have gotten this to work for the most part, but am not sure if this is the best way to do this. If the models act like multiple SQL queries I don't believe this should be an issue, but I would like to know from someone I bit more knowledgeable about this stuff since this is pretty new to me. Thanks

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• Flash Player, security: If a URL starts with "http://" will the SWF always be loaded into REMOTE san

  - by Pavel

  Seems to be a question for a Flash security guru. Suppose we are loading an external SWF movie with MovieClipLoader.loadMovie(url:String) Is it safe to assume that if url starts with "http://", the movie will be loaded in REMOTE sandbox? We need to tell local SWFs from remote ones to close a security hole. If you need the context read on. We have developed a Projector, written in C++ embedding Flash Player ActiveX. Our Flash application runs inside the Projector. Soon we want to give our users a way to create plugins for the application. The plugins are obviously will be SWF movies. The case I'm afraid of is the following. A bad person creates a malicious evil.swf pretending it to be nice plugin for our app. In case evil.swf is loaded from the local file system it is granted an access to the whole MovieClip tree and Projector API, opening C++ file access operations. On the other hand if evil.swf is loaded from the internet, remotely, it will be locked in REMOTE sandbox by Flash security model. Because of this, we need a reliable way to tell local SWF from remote one before loading it. And we must not make a mistake. So again, is it safe to assume that if url begins with "http://", the clip will be loaded inside REMOTE sandbox?

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• Multiple locking task (threading)

  - by Archeg

  I need to implement the class that should perform locking mechanism in our framework. We have several threads and they are numbered 0,1,2,3.... We have a static class called ResourceHandler, that should lock these threads on given objects. The requirement is that n Lock() invokes should be realeased by m Release() invokes, where n = [0..] and m = [0..]. So no matter how many locks was performed on single object, only one Release call is enough to unlock all. Even further if o object is not locked, Release call should perform nothing. Also we need to know what objects are locked on what threads. I have this implementation: public class ResourceHandler { private readonly Dictionary<int, List<object>> _locks = new Dictionary<int, List<object>>(); public static ResourceHandler Instance {/* Singleton */} public virtual void Lock(int threadNumber, object obj) { Monitor.Enter(obj); if (!_locks.ContainsKey(threadNumber)) {_locks.Add(new List<object>());} _locks[threadNumber].Add(obj); } public virtual void Release(int threadNumber, object obj) { // Check whether we have threadN in _lock and skip if not var count = _locks[threadNumber].Count(x => x == obj); _locks[threadNumber].RemoveAll(x => x == obj); for (int i=0; i<count; i++) { Monitor.Exit(obj); } } // ..... } Actually what I am worried here about is thread-safety. I'm actually not sure, is it thread-safe or not, and it's a real pain to fix that. Am I doing the task correctly and how can I ensure that this is thread-safe?

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• An easy way to create Side by Side registrationless COM Manifests with Visual Studio

  - by Rick Strahl

  Here's something I didn't find out until today: You can use Visual Studio to easily create registrationless COM manifest files for you with just a couple of small steps. Registrationless COM lets you use COM component without them being registered in the registry. This means it's possible to deploy COM components along with another application using plain xcopy semantics. To be sure it's rarely quite that easy - you need to watch out for dependencies - but if you know you have COM components that are light weight and have no or known dependencies it's easy to get everything into a single folder and off you go. Registrationless COM works via manifest files which carry the same name as the executable plus a .manifest extension (ie. yourapp.exe.manifest) I'm going to use a Visual FoxPro COM object as an example and create a simple Windows Forms app that calls the component - without that component being registered. Let's take a walk down memory lane… Create a COM Component I start by creating a FoxPro COM component because that's what I know and am working with here in my legacy environment. You can use VB classic or C++ ATL object if that's more to your liking. Here's a real simple Fox one: DEFINE CLASS SimpleServer as Session OLEPUBLIC FUNCTION HelloWorld(lcName) RETURN "Hello " + lcName ENDDEFINE Compile it into a DLL COM component with: BUILD MTDLL simpleserver FROM simpleserver RECOMPILE And to make sure it works test it quickly from Visual FoxPro: server = CREATEOBJECT("simpleServer.simpleserver") MESSAGEBOX( server.HelloWorld("Rick") ) Using Visual Studio to create a Manifest File for a COM Component Next open Visual Studio and create a new executable project - a Console App or WinForms or WPF application will all do. Go to the References Node Select Add Reference Use the Browse tab and find your compiled DLL to import  Next you'll see your assembly in the project. Right click on the reference and select Properties Click on the Isolated DropDown and select True Compile and that's all there's to it. Visual Studio will create a App.exe.manifest file right alongside your application's EXE. The manifest file created looks like this: xml version="1.0" encoding="utf-8"? assembly xsi:schemaLocation="urn:schemas-microsoft-com:asm.v1 assembly.adaptive.xsd" manifestVersion="1.0" xmlns:asmv1="urn:schemas-microsoft-com:asm.v1" xmlns:asmv2="urn:schemas-microsoft-com:asm.v2" xmlns:asmv3="urn:schemas-microsoft-com:asm.v3" xmlns:dsig="http://www.w3.org/2000/09/xmldsig#" xmlns:co.v1="urn:schemas-microsoft-com:clickonce.v1" xmlns:co.v2="urn:schemas-microsoft-com:clickonce.v2" xmlns="urn:schemas-microsoft-com:asm.v1" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" assemblyIdentity name="App.exe" version="1.0.0.0" processorArchitecture="x86" type="win32" / file name="simpleserver.DLL" asmv2:size="27293" hash xmlns="urn:schemas-microsoft-com:asm.v2" dsig:Transforms dsig:Transform Algorithm="urn:schemas-microsoft-com:HashTransforms.Identity" / dsig:Transforms dsig:DigestMethod Algorithm="http://www.w3.org/2000/09/xmldsig#sha1" / dsig:DigestValuepuq+ua20bbidGOWhPOxfquztBCU=dsig:DigestValue hash typelib tlbid="{f10346e2-c9d9-47f7-81d1-74059cc15c3c}" version="1.0" helpdir="" resourceid="0" flags="HASDISKIMAGE" / comClass clsid="{af2c2811-0657-4264-a1f5-06d033a969ff}" threadingModel="Apartment" tlbid="{f10346e2-c9d9-47f7-81d1-74059cc15c3c}" progid="simpleserver.SimpleServer" description="simpleserver.SimpleServer" / file assembly Now let's finish our super complex console app to test with: using System; using System.Collections.Generic; using System.Text; namespace ConsoleApplication1 {     class Program     {         static voidMain(string[] args)         { Type type = Type.GetTypeFromProgID("simpleserver.simpleserver",true); dynamic server = Activator.CreateInstance(type); Console.WriteLine(server.HelloWorld("rick")); Console.ReadLine(); } } } Now run the Console Application… As expected that should work. And why not? The COM component is still registered, right? :-) Nothing tricky about that. Let's unregister the COM component and then re-run and see what happens. Go to the Command Prompt Change to the folder where the DLL is installed Unregister with: RegSvr32 -u simpleserver.dll      To be sure that the COM component no longer works, check it out with the same test you used earlier (ie. o = CREATEOBJECT("SimpleServer.SimpleServer") in your development environment or VBScript etc.). Make sure you run the EXE and you don't re-compile the application or else Visual Studio will complain that it can't find the COM component in the registry while compiling. In fact now that we have our .manifest file you can remove the COM object from the project. When you run run the EXE from Windows Explorer or a command prompt to avoid the recompile. Watch out for embedded Manifest Files Now recompile your .NET project and run it… and it will most likely fail! The problem is that .NET applications by default embeds a manifest file into the compiled EXE application which results in the externally created manifest file being completely ignored. Only one manifest can be applied at a time and the compiled manifest takes precedency. Uh, thanks Visual Studio - not very helpful… Note that if you use another development tool like Visual FoxPro to create your EXE this won't be an issue as long as the tool doesn't automatically add a manifest file. Creating a Visual FoxPro EXE for example will work immediately with the generated manifest file as is. If you are using .NET and Visual Studio you have a couple of options of getting around this: Remove the embedded manifest file Copy the contents of the generated manifest file into a project manifest file and compile that in To remove an embedded manifest in a Visual Studio project: Open the Project Properties (Alt-Enter on project node) Go down to Resources | Manifest and select | Create Application without a Manifest   You can now add use the external manifest file and it will actually be respected when the app runs. The other option is to let Visual Studio create the manifest file on disk and then explicitly add the manifest file into the project. Notice on the dialog above I did this for app.exe.manifest and the manifest actually shows up in the list. If I select this file it will be compiled into the EXE and be used in lieu of any external files and that works as well. Remove the simpleserver.dll reference so you can compile your code and run the application. Now it should work without COM registration of the component. Personally I prefer external manifests because they can be modified after the fact - compiled manifests are evil in my mind because they are immutable - once they are there they can't be overriden or changed. So I prefer an external manifest. However, if you are absolutely sure nothing needs to change and you don't want anybody messing with your manifest, you can also embed it. The option to either is there. Watch for Manifest Caching While working trying to get this to work I ran into some problems at first. Specifically when it wasn't working at first (due to the embedded schema) I played with various different manifest layouts in different files etc.. There are a number of different ways to actually represent manifest files including offloading to separate folder (more on that later). A few times I made deliberate errors in the schema file and I found that regardless of what I did once the app failed or worked no amount of changing of the manifest file would make it behave differently. It appears that Windows is caching the manifest data for a given EXE or DLL. It takes a restart or a recompile of either the EXE or the DLL to clear the caching. Recompile your servers in order to see manifest changes unless there's an outright failure of an invalid manifest file. If the app starts the manifest is being read and caches immediately. This can be very confusing especially if you don't know that it's happening. I found myself always recompiling the exe after each run and before making any changes to the manifest file. Don't forget about Runtimes of COM Objects In the example I used above I used a Visual FoxPro COM component. Visual FoxPro is a runtime based environment so if I'm going to distribute an application that uses a FoxPro COM object the runtimes need to be distributed as well. The same is true of classic Visual Basic applications. Assuming that you don't know whether the runtimes are installed on the target machines make sure to install all the additional files in the EXE's directory alongside the COM DLL. In the case of Visual FoxPro the target folder should contain: The EXE  App.exe The Manifest file (unless it's compiled in) App.exe.manifest The COM object DLL (simpleserver.dll) Visual FoxPro Runtimes: VFP9t.dll (or VFP9r.dll for non-multithreaded dlls), vfp9rENU.dll, msvcr71.dll All these files should be in the same folder. Debugging Manifest load Errors If you for some reason get your manifest loading wrong there are a couple of useful tools available - SxSTrace and SxSParse. These two tools can be a huge help in debugging manifest loading errors. Put the following into a batch file (SxS_Trace.bat for example): sxstrace Trace -logfile:sxs.bin sxstrace Parse -logfile:sxs.bin -outfile:sxs.txt Then start the batch file before running your EXE. Make sure there's no caching happening as described in the previous section. For example, if I go into the manifest file and explicitly break the CLSID and/or ProgID I get a detailed report on where the EXE is looking for the manifest and what it's reading. Eventually the trace gives me an error like this: INFO: Parsing Manifest File C:\wwapps\Conf\SideBySide\Code\app.EXE.     INFO: Manifest Definition Identity is App.exe,processorArchitecture="x86",type="win32",version="1.0.0.0".     ERROR: Line 13: The value {AAaf2c2811-0657-4264-a1f5-06d033a969ff} of attribute clsid in element comClass is invalid. ERROR: Activation Context generation failed. End Activation Context Generation. pinpointing nicely where the error lies. Pay special attention to the various attributes - they have to match exactly in the different sections of the manifest file(s). Multiple COM Objects The manifest file that Visual Studio creates is actually quite more complex than is required for basic registrationless COM object invokation. The manifest file can be simplified a lot actually by stripping off various namespaces and removing the type library references altogether. Here's an example of a simplified manifest file that actually includes references to 2 COM servers: xml version="1.0" encoding="utf-8"? assembly xmlns="urn:schemas-microsoft-com:asm.v1" manifestVersion="1.0" assemblyIdentity name="App.exe" version="1.0.0.0" processorArchitecture="x86" type="win32" / file name="simpleserver.DLL" comClass clsid="{af2c2811-0657-4264-a1f5-06d033a969ff}" threadingModel="Apartment" progid="simpleserver.SimpleServer" description="simpleserver.SimpleServer" / file file name = "sidebysidedeploy.dll" comClass clsid="{EF82B819-7963-4C36-9443-3978CD94F57C}" progid="sidebysidedeploy.SidebysidedeployServer" description="SidebySideDeploy Server" threadingModel="apartment" / file assembly Simple enough right? Routing to separate Manifest Files and Folders In the examples above all files ended up in the application's root folder - all the DLLs, support files and runtimes. Sometimes that's not so desirable and you can actually create separate manifest files. The easiest way to do this is to create a manifest file that 'routes' to another manifest file in a separate folder. Basically you create a new 'assembly identity' via a named id. You can then create a folder and another manifest with the id plus .manifest that points at the actual file. In this example I create: App.exe.manifest A folder called App.deploy A manifest file in App.deploy All DLLs and runtimes in App.deploy Let's start with that master manifest file. This file only holds a reference to another manifest file: App.exe.manifest xml version="1.0" encoding="UTF-8" standalone="yes"? assembly xmlns="urn:schemas-microsoft-com:asm.v1" manifestVersion="1.0" assemblyIdentity name="App.exe" version="1.0.0.0" processorArchitecture="x86" type="win32" / dependency dependentAssembly assemblyIdentity name="App.deploy" version="1.0.0.0" type="win32" / dependentAssembly dependency assembly   Note this file only contains a dependency to App.deploy which is another manifest id. I can then create App.deploy.manifest in the current folder or in an App.deploy folder. In this case I'll create App.deploy and in it copy the DLLs and support runtimes. I then create App.deploy.manifest. App.deploy.manifest xml version="1.0" encoding="UTF-8" standalone="yes"? assembly xmlns="urn:schemas-microsoft-com:asm.v1" manifestVersion="1.0" assemblyIdentity name="App.deploy" type="win32" version="1.0.0.0" / file name="simpleserver.DLL" comClass clsid="{af2c2811-0657-4264-a1f5-06d033a969ff}" threadingModel="Apartment" progid="simpleserver.SimpleServer" description="simpleserver.SimpleServer" / file file name="sidebysidedeploy.dll" comClass clsid="{EF82B819-7963-4C36-9443-3978CD94F57C}" threadingModel="Apartment" progid="sidebysidedeploy.SidebysidedeployServer" description="SidebySideDeploy Server" / file assembly   In this manifest file I then host my COM DLLs and any support runtimes. This is quite useful if you have lots of DLLs you are referencing or if you need to have separate configuration and application files that are associated with the COM object. This way the operation of your main application and the COM objects it interacts with is somewhat separated. You can see the two folders here:   Routing Manifests to different Folders In theory registrationless COM should be pretty easy in painless - you've seen the configuration manifest files and it certainly doesn't look very complicated, right? But the devil's in the details. The ActivationContext API (SxS - side by side activation) is very intolerant of small errors in the XML or formatting of the keys, so be really careful when setting up components, especially if you are manually editing these files. If you do run into trouble SxsTrace/SxsParse are a huge help to track down the problems. And remember that if you do have problems that you'll need to recompile your EXEs or DLLs for the SxS APIs to refresh themselves properly. All of this gets even more fun if you want to do registrationless COM inside of IIS :-) But I'll leave that for another blog post…© Rick Strahl, West Wind Technologies, 2005-2011Posted in COM  .NET  FoxPro   Tweet (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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• Announcing the release of the Windows Azure SDK 2.1 for .NET

  - by ScottGu

  Today we released the v2.1 update of the Windows Azure SDK for .NET.  This is a major refresh of the Windows Azure SDK and it includes some great new features and enhancements. These new capabilities include: Visual Studio 2013 Preview Support: The Windows Azure SDK now supports using the new VS 2013 Preview Visual Studio 2013 VM Image: Windows Azure now has a built-in VM image that you can use to host and develop with VS 2013 in the cloud Visual Studio Server Explorer Enhancements: Redesigned with improved filtering and auto-loading of subscription resources Virtual Machines: Start and Stop VM’s w/suspend billing directly from within Visual Studio Cloud Services: New Emulator Express option with reduced footprint and Run as Normal User support Service Bus: New high availability options, Notification Hub support, Improved VS tooling PowerShell Automation: Lots of new PowerShell commands for automating Web Sites, Cloud Services, VMs and more All of these SDK enhancements are now available to start using immediately and you can download the SDK from the Windows Azure .NET Developer Center.  Visual Studio’s Team Foundation Service (http://tfs.visualstudio.com/) has also been updated to support today’s SDK 2.1 release, and the SDK 2.1 features can now be used with it (including with automated builds + tests). Below are more details on the new features and capabilities released today: Visual Studio 2013 Preview Support Today’s Window Azure SDK 2.1 release adds support for the recent Visual Studio 2013 Preview. The 2.1 SDK also works with Visual Studio 2010 and Visual Studio 2012, and works side by side with the previous Windows Azure SDK 1.8 and 2.0 releases. To install the Windows Azure SDK 2.1 on your local computer, choose the “install the sdk” link from the Windows Azure .NET Developer Center. Then, chose which version of Visual Studio you want to use it with.  Clicking the third link will install the SDK with the latest VS 2013 Preview: If you don’t already have the Visual Studio 2013 Preview installed on your machine, this will also install Visual Studio Express 2013 Preview for Web. Visual Studio 2013 VM Image Hosted in the Cloud One of the requests we’ve heard from several customers has been to have the ability to host Visual Studio within the cloud (avoiding the need to install anything locally on your computer). With today’s SDK update we’ve added a new VM image to the Windows Azure VM Gallery that has Visual Studio Ultimate 2013 Preview, SharePoint 2013, SQL Server 2012 Express and the Windows Azure 2.1 SDK already installed on it.  This provides a really easy way to create a development environment in the cloud with the latest tools. With the recent shutdown and suspend billing feature we shipped on Windows Azure last month, you can spin up the image only when you want to do active development, and then shut down the virtual machine and not have to worry about usage charges while the virtual machine is not in use. You can create your own VS image in the cloud by using the New->Compute->Virtual Machine->From Gallery menu within the Windows Azure Management Portal, and then by selecting the “Visual Studio Ultimate 2013 Preview” template: Visual Studio Server Explorer: Improved Filtering/Management of Subscription Resources With the Windows Azure SDK 2.1 release you’ll notice significant improvements in the Visual Studio Server Explorer. The explorer has been redesigned so that all Windows Azure services are now contained under a single Windows Azure node.  From the top level node you can now manage your Windows Azure credentials, import a subscription file or filter Server Explorer to only show services from particular subscriptions or regions. Note: The Web Sites and Mobile Services nodes will appear outside the Windows Azure Node until the final release of VS 2013. If you have installed the ASP.NET and Web Tools Preview Refresh, though, the Web Sites node will appear inside the Windows Azure node even with the VS 2013 Preview. Once your subscription information is added, Windows Azure services from all your subscriptions are automatically enumerated in the Server Explorer. You no longer need to manually add services to Server Explorer individually. This provides a convenient way of viewing all of your cloud services, storage accounts, service bus namespaces, virtual machines, and web sites from one location: Subscription and Region Filtering Support Using the Windows Azure node in Server Explorer, you can also now filter your Windows Azure services in the Server Explorer by the subscription or region they are in.  If you have multiple subscriptions but need to focus your attention to just a few subscription for some period of time, this a handy way to hide the services from other subscriptions view until they become relevant. You can do the same sort of filtering by region. To enable this, just select “Filter Services” from the context menu on the Windows Azure node: Then choose the subscriptions and/or regions you want to filter by. In the below example, I’ve decided to show services from my pay-as-you-go subscription within the East US region: Visual Studio will then automatically filter the items that show up in the Server Explorer appropriately: With storage accounts and service bus namespaces, you sometimes need to work with services outside your subscription. To accommodate that scenario, those services allow you to attach an external account (from the context menu). You’ll notice that external accounts have a slightly different icon in server explorer to indicate they are from outside your subscription. Other Improvements We’ve also improved the Server Explorer by adding additional properties and actions to the service exposed. You now have access to most of the properties on a cloud service, deployment slot, role or role instance as well as the properties on storage accounts, virtual machines and web sites. Just select the object of interest in Server Explorer and view the properties in the property pane. We also now have full support for creating/deleting/update storage tables, blobs and queues from directly within Server Explorer.  Simply right-click on the appropriate storage account node and you can create them directly within Visual Studio: Virtual Machines: Start/Stop within Visual Studio Virtual Machines now have context menu actions that allow you start, shutdown, restart and delete a Virtual Machine directly within the Visual Studio Server Explorer. The shutdown action enables you to shut down the virtual machine and suspend billing when the VM is not is use, and easily restart it when you need it: This is especially useful in Dev/Test scenarios where you can start a VM – such as a SQL Server – during your development session and then shut it down / suspend billing when you are not developing (and no longer be billed for it). You can also now directly remote desktop into VMs using the “Connect using Remote Desktop” context menu command in VS Server Explorer.  Cloud Services: Emulator Express with Run as Normal User Support You can now launch Visual Studio and run your cloud services locally as a Normal User (without having to elevate to an administrator account) using a new Emulator Express option included as a preview feature with this SDK release.  Emulator Express is a version of the Windows Azure Compute Emulator that runs a restricted mode – one instance per role – and it doesn’t require administrative permissions and uses 40% less resources than the full Windows Azure Emulator. Emulator Express supports both web and worker roles. To run your application locally using the Emulator Express option, simply change the following settings in the Windows Azure project. On the shortcut menu for the Windows Azure project, choose Properties, and then choose the Web tab. Check the setting for IIS (Internet Information Services). Make sure that the option is set to IIS Express, not the full version of IIS. Emulator Express is not compatible with full IIS. On the Web tab, choose the option for Emulator Express. Service Bus: Notification Hubs With the Windows Azure SDK 2.1 release we are adding support for Windows Azure Notification Hubs as part of our official Windows Azure SDK, inside of Microsoft.ServiceBus.dll (previously the Notification Hub functionality was in a preview assembly). You are now able to create, update and delete Notification Hubs programmatically, manage your device registrations, and send push notifications to all your mobile clients across all platforms (Windows Store, Windows Phone 8, iOS, and Android). Learn more about Notification Hubs on MSDN here, or watch the Notification Hubs //BUILD/ presentation here. Service Bus: Paired Namespaces One of the new features included with today’s Windows Azure SDK 2.1 release is support for Service Bus “Paired Namespaces”.  Paired Namespaces enable you to better handle situations where a Service Bus service namespace becomes unavailable (for example: due to connectivity issues or an outage) and you are unable to send or receive messages to the namespace hosting the queue, topic, or subscription. Previously,to handle this scenario you had to manually setup separate namespaces that can act as a backup, then implement manual failover and retry logic which was sometimes tricky to get right. Service Bus now supports Paired Namespaces, which enables you to connect two namespaces together. When you activate the secondary namespace, messages are stored in the secondary queue for delivery to the primary queue at a later time. If the primary container (namespace) becomes unavailable for some reason, automatic failover enables the messages in the secondary queue. For detailed information about paired namespaces and high availability, see the new topic Asynchronous Messaging Patterns and High Availability. Service Bus: Tooling Improvements In this release, the Windows Azure Tools for Visual Studio contain several enhancements and changes to the management of Service Bus messaging entities using Visual Studio’s Server Explorer. The most noticeable change is that the Service Bus node is now integrated into the Windows Azure node, and supports integrated subscription management. Additionally, there has been a change to the code generated by the Windows Azure Worker Role with Service Bus Queue project template. This code now uses an event-driven “message pump” programming model using the QueueClient.OnMessage method. PowerShell: Tons of New Automation Commands Since my last blog post on the previous Windows Azure SDK 2.0 release, we’ve updated Windows Azure PowerShell (which is a separate download) five times. You can find the full change log here. We’ve added new cmdlets in the following areas: China instance and Windows Azure Pack support Environment Configuration VMs Cloud Services Web Sites Storage SQL Azure Service Bus China Instance and Windows Azure Pack We now support the following cmdlets for the China instance and Windows Azure Pack, respectively: China Instance: Web Sites, Service Bus, Storage, Cloud Service, VMs, Network Windows Azure Pack: Web Sites, Service Bus We will have full cmdlet support for these two Windows Azure environments in PowerShell in the near future. Virtual Machines: Stop/Start Virtual Machines Similar to the Start/Stop VM capability in VS Server Explorer, you can now stop your VM and suspend billing: If you want to keep the original behavior of keeping your stopped VM provisioned, you can pass in the -StayProvisioned switch parameter. Virtual Machines: VM endpoint ACLs We’ve added and updated a bunch of cmdlets for you to configure fine-grained network ACL on your VM endpoints. You can use the following cmdlets to create ACL config and apply them to a VM endpoint: New-AzureAclConfig Get-AzureAclConfig Set-AzureAclConfig Remove-AzureAclConfig Add-AzureEndpoint -ACL Set-AzureEndpoint –ACL The following example shows how to add an ACL rule to an existing endpoint of a VM. Other improvements for Virtual Machine management includes Added -NoWinRMEndpoint parameter to New-AzureQuickVM and Add-AzureProvisioningConfig to disable Windows Remote Management Added -DirectServerReturn parameter to Add-AzureEndpoint and Set-AzureEndpoint to enable/disable direct server return Added Set-AzureLoadBalancedEndpoint cmdlet to modify load balanced endpoints Cloud Services: Remote Desktop and Diagnostics Remote Desktop and Diagnostics are popular debugging options for Cloud Services. We’ve introduced cmdlets to help you configure these two Cloud Service extensions from Windows Azure PowerShell. Windows Azure Cloud Services Remote Desktop extension: New-AzureServiceRemoteDesktopExtensionConfig Get-AzureServiceRemoteDesktopExtension Set-AzureServiceRemoteDesktopExtension Remove-AzureServiceRemoteDesktopExtension Windows Azure Cloud Services Diagnostics extension New-AzureServiceDiagnosticsExtensionConfig Get-AzureServiceDiagnosticsExtension Set-AzureServiceDiagnosticsExtension Remove-AzureServiceDiagnosticsExtension The following example shows how to enable Remote Desktop for a Cloud Service. Web Sites: Diagnostics With our last SDK update, we introduced the Get-AzureWebsiteLog –Tail cmdlet to get the log streaming of your Web Sites. Recently, we’ve also added cmdlets to configure Web Site application diagnostics: Enable-AzureWebsiteApplicationDiagnostic Disable-AzureWebsiteApplicationDiagnostic The following 2 examples show how to enable application diagnostics to the file system and a Windows Azure Storage Table: SQL Database Previously, you had to know the SQL Database server admin username and password if you want to manage the database in that SQL Database server. Recently, we’ve made the experience much easier by not requiring the admin credential if the database server is in your subscription. So you can simply specify the -ServerName parameter to tell Windows Azure PowerShell which server you want to use for the following cmdlets. Get-AzureSqlDatabase New-AzureSqlDatabase Remove-AzureSqlDatabase Set-AzureSqlDatabase We’ve also added a -AllowAllAzureServices parameter to New-AzureSqlDatabaseServerFirewallRule so that you can easily add a firewall rule to whitelist all Windows Azure IP addresses. Besides the above experience improvements, we’ve also added cmdlets get the database server quota and set the database service objective. Check out the following cmdlets for details. Get-AzureSqlDatabaseServerQuota Get-AzureSqlDatabaseServiceObjective Set-AzureSqlDatabase –ServiceObjective Storage and Service Bus Other new cmdlets include Storage: CRUD cmdlets for Azure Tables and Queues Service Bus: Cmdlets for managing authorization rules on your Service Bus Namespace, Queue, Topic, Relay and NotificationHub Summary Today’s release includes a bunch of great features that enable you to build even better cloud solutions.  All the above features/enhancements are shipped and available to use immediately as part of the 2.1 release of the Windows Azure SDK for .NET. If you don’t already have a Windows Azure account, you can sign-up for a free trial and start using all of the above features today.  Then visit the Windows Azure Developer Center to learn more about how to build apps with it. Hope this helps, Scott P.S. In addition to blogging, I am also now using Twitter for quick updates and to share links. Follow me at: twitter.com/scottgu

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• A Communication System for XAML Applications

  - by psheriff

  In any application, you want to keep the coupling between any two or more objects as loose as possible. Coupling happens when one class contains a property that is used in another class, or uses another class in one of its methods. If you have this situation, then this is called strong or tight coupling. One popular design pattern to help with keeping objects loosely coupled is called the Mediator design pattern. The basics of this pattern are very simple; avoid one object directly talking to another object, and instead use another class to mediate between the two. As with most of my blog posts, the purpose is to introduce you to a simple approach to using a message broker, not all of the fine details. IPDSAMessageBroker Interface As with most implementations of a design pattern, you typically start with an interface or an abstract base class. In this particular instance, an Interface will work just fine. The interface for our Message Broker class just contains a single method “SendMessage” and one event “MessageReceived”. public delegate void MessageReceivedEventHandler( object sender, PDSAMessageBrokerEventArgs e); public interface IPDSAMessageBroker{  void SendMessage(PDSAMessageBrokerMessage msg);   event MessageReceivedEventHandler MessageReceived;} PDSAMessageBrokerMessage Class As you can see in the interface, the SendMessage method requires a type of PDSAMessageBrokerMessage to be passed to it. This class simply has a MessageName which is a ‘string’ type and a MessageBody property which is of the type ‘object’ so you can pass whatever you want in the body. You might pass a string in the body, or a complete Customer object. The MessageName property will help the receiver of the message know what is in the MessageBody property. public class PDSAMessageBrokerMessage{  public PDSAMessageBrokerMessage()  {  }   public PDSAMessageBrokerMessage(string name, object body)  {    MessageName = name;    MessageBody = body;  }   public string MessageName { get; set; }   public object MessageBody { get; set; }} PDSAMessageBrokerEventArgs Class As our message broker class will be raising an event that others can respond to, it is a good idea to create your own event argument class. This class will inherit from the System.EventArgs class and add a couple of additional properties. The properties are the MessageName and Message. The MessageName property is simply a string value. The Message property is a type of a PDSAMessageBrokerMessage class. public class PDSAMessageBrokerEventArgs : EventArgs{  public PDSAMessageBrokerEventArgs()  {  }   public PDSAMessageBrokerEventArgs(string name,     PDSAMessageBrokerMessage msg)  {    MessageName = name;    Message = msg;  }   public string MessageName { get; set; }   public PDSAMessageBrokerMessage Message { get; set; }} PDSAMessageBroker Class Now that you have an interface class and a class to pass a message through an event, it is time to create your actual PDSAMessageBroker class. This class implements the SendMessage method and will also create the event handler for the delegate created in your Interface. public class PDSAMessageBroker : IPDSAMessageBroker{  public void SendMessage(PDSAMessageBrokerMessage msg)  {    PDSAMessageBrokerEventArgs args;     args = new PDSAMessageBrokerEventArgs(      msg.MessageName, msg);     RaiseMessageReceived(args);  }   public event MessageReceivedEventHandler MessageReceived;   protected void RaiseMessageReceived(    PDSAMessageBrokerEventArgs e)  {    if (null != MessageReceived)      MessageReceived(this, e);  }} The SendMessage method will take a PDSAMessageBrokerMessage object as an argument. It then creates an instance of a PDSAMessageBrokerEventArgs class, passing to the constructor two items: the MessageName from the PDSAMessageBrokerMessage object and also the object itself. It may seem a little redundant to pass in the message name when that same message name is part of the message, but it does make consuming the event and checking for the message name a little cleaner – as you will see in the next section. Create a Global Message Broker In your WPF application, create an instance of this message broker class in the App class located in the App.xaml file. Create a public property in the App class and create a new instance of that class in the OnStartUp event procedure as shown in the following code: public partial class App : Application{  public PDSAMessageBroker MessageBroker { get; set; }   protected override void OnStartup(StartupEventArgs e)  {    base.OnStartup(e);     MessageBroker = new PDSAMessageBroker();  }} Sending and Receiving Messages Let’s assume you have a user control that you load into a control on your main window and you want to send a message from that user control to the main window. You might have the main window display a message box, or put a string into a status bar as shown in Figure 1. Figure 1: The main window can receive and send messages The first thing you do in the main window is to hook up an event procedure to the MessageReceived event of the global message broker. This is done in the constructor of the main window: public MainWindow(){  InitializeComponent();   (Application.Current as App).MessageBroker.     MessageReceived += new MessageReceivedEventHandler(       MessageBroker_MessageReceived);} One piece of code you might not be familiar with is accessing a property defined in the App class of your XAML application. Within the App.Xaml file is a class named App that inherits from the Application object. You access the global instance of this App class by using Application.Current. You cast Application.Current to ‘App’ prior to accessing any of the public properties or methods you defined in the App class. Thus, the code (Application.Current as App).MessageBroker, allows you to get at the MessageBroker property defined in the App class. In the MessageReceived event procedure in the main window (shown below) you can now check to see if the MessageName property of the PDSAMessageBrokerEventArgs is equal to “StatusBar” and if it is, then display the message body into the status bar text block control. void MessageBroker_MessageReceived(object sender,   PDSAMessageBrokerEventArgs e){  switch (e.MessageName)  {    case "StatusBar":      tbStatus.Text = e.Message.MessageBody.ToString();      break;  }} In the Page 1 user control’s Loaded event procedure you will send the message “StatusBar” through the global message broker to any listener using the following code: private void UserControl_Loaded(object sender,  RoutedEventArgs e){  // Send Status Message  (Application.Current as App).MessageBroker.    SendMessage(new PDSAMessageBrokerMessage("StatusBar",      "This is Page 1"));} Since the main window is listening for the message ‘StatusBar’, it will display the value “This is Page 1” in the status bar at the bottom of the main window. Sending a Message to a User Control The previous example sent a message from the user control to the main window. You can also send messages from the main window to any listener as well. Remember that the global message broker is really just a broadcaster to anyone who has hooked into the MessageReceived event. In the constructor of the user control named ucPage1 you can hook into the global message broker’s MessageReceived event. You can then listen for any messages that are sent to this control by using a similar switch-case structure like that in the main window. public ucPage1(){  InitializeComponent();   // Hook to the Global Message Broker  (Application.Current as App).MessageBroker.    MessageReceived += new MessageReceivedEventHandler(      MessageBroker_MessageReceived);} void MessageBroker_MessageReceived(object sender,  PDSAMessageBrokerEventArgs e){  // Look for messages intended for Page 1  switch (e.MessageName)  {    case "ForPage1":      MessageBox.Show(e.Message.MessageBody.ToString());      break;  }} Once the ucPage1 user control has been loaded into the main window you can then send a message using the following code: private void btnSendToPage1_Click(object sender,  RoutedEventArgs e){  PDSAMessageBrokerMessage arg =     new PDSAMessageBrokerMessage();   arg.MessageName = "ForPage1";  arg.MessageBody = "Message For Page 1";   // Send a message to Page 1  (Application.Current as App).MessageBroker.SendMessage(arg);} Since the MessageName matches what is in the ucPage1 MessageReceived event procedure, ucPage1 can do anything in response to that event. It is important to note that when the message gets sent it is sent to all MessageReceived event procedures, not just the one that is looking for a message called “ForPage1”. If the user control ucPage1 is not loaded and this message is broadcast, but no other code is listening for it, then it is simply ignored. Remove Event Handler In each class where you add an event handler to the MessageReceived event you need to make sure to remove those event handlers when you are done. Failure to do so can cause a strong reference to the class and thus not allow that object to be garbage collected. In each of your user control’s make sure in the Unloaded event to remove the event handler. private void UserControl_Unloaded(object sender, RoutedEventArgs e){  if (_MessageBroker != null)    _MessageBroker.MessageReceived -=         _MessageBroker_MessageReceived;} Problems with Message Brokering As with most “global” classes or classes that hook up events to other classes, garbage collection is something you need to consider. Just the simple act of hooking up an event procedure to a global event handler creates a reference between your user control and the message broker in the App class. This means that even when your user control is removed from your UI, the class will still be in memory because of the reference to the message broker. This can cause messages to still being handled even though the UI is not being displayed. It is up to you to make sure you remove those event handlers as discussed in the previous section. If you don’t, then the garbage collector cannot release those objects. Instead of using events to send messages from one object to another you might consider registering your objects with a central message broker. This message broker now becomes a collection class into which you pass an object and what messages that object wishes to receive. You do end up with the same problem however. You have to un-register your objects; otherwise they still stay in memory. To alleviate this problem you can look into using the WeakReference class as a method to store your objects so they can be garbage collected if need be. Discussing Weak References is beyond the scope of this post, but you can look this up on the web. Summary In this blog post you learned how to create a simple message broker system that will allow you to send messages from one object to another without having to reference objects directly. This does reduce the coupling between objects in your application. You do need to remember to get rid of any event handlers prior to your objects going out of scope or you run the risk of having memory leaks and events being called even though you can no longer access the object that is responding to that event. NOTE: You can download the sample code for this article by visiting my website at http://www.pdsa.com/downloads. Select “Tips & Tricks”, then select “A Communication System for XAML Applications” from the drop down list.

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