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  • Why does the the Java VM not recover after "Too many open files" errors?

    - by Michael
    In certain well-understood circumstances, our application will open too many sockets (database connections) and reach the maximum open files that the OS allows. We understand this; we are fixing the issue and also bumping up the limit. What we can't explain is why parts of our application don't recover even after the number of connections abates and we're well within the limit. In this case, it's an application running under Tomcat. When this happens, we first start seeing "Too many open files" errors: SEVERE: Socket accept failed java.net.SocketException: Too many open files at java.net.PlainSocketImpl.socketAccept(Native Method) at java.net.PlainSocketImpl.accept(PlainSocketImpl.java:390) at java.net.ServerSocket.implAccept(ServerSocket.java:453) at java.net.ServerSocket.accept(ServerSocket.java:421) at org.apache.tomcat.util.net.DefaultServerSocketFactory.acceptSocket(DefaultServerSocketFactory.java:61) at org.apache.tomcat.util.net.JIoEndpoint$Acceptor.run(JIoEndpoint.java:310) at java.lang.Thread.run(Thread.java:619) Eventually, we start seeing NoClassDefFoundErrors inside an application thread that's trying to open HTTP connections: java.lang.NoClassDefFoundError: org/apache/commons/httpclient/protocol/ControllerThreadSocketFactory at org.apache.commons.httpclient.protocol.DefaultProtocolSocketFactory.createSocket(DefaultProtocolSocketFactory.java:128) at org.apache.commons.httpclient.HttpConnection.open(HttpConnection.java:707) at org.apache.commons.httpclient.MultiThreadedHttpConnectionManager$HttpConnectionAdapter.open(MultiThreadedHttpConnectionManager.java:1349) [...] Caused by: java.lang.ClassNotFoundException: org.apache.commons.httpclient.protocol.ControllerThreadSocketFactory at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1387) at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1233) at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:320) ... 8 more When the errant connections go away, the server starts accepting connections again, and everything seems ok, but we're left with the latter error constantly being spewed to stderr. Although the application typically logs unloaded classes to stdout, I don't see any such logs just before, during or after the "Too many open files" errors. My initial theory was that the Hotspot JVM would unload seemingly unused classes when it encounters "Too many open files," but if so, it doesn't log the fact. I'd also expect it to recover if that were the case. Platform details: Java(TM) SE Runtime Environment (build 1.6.0_14-b08) Java HotSpot(TM) 64-Bit Server VM (build 14.0-b16, mixed mode) Apache Tomcat Version 6.0.18

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  • ClassCastException When Calling an EJB that Exists on Same Server

    - by aaronvargas
    I have 2 ejbs. Ejb-A that calls Ejb-B. They are not in the same Ear. For portability Ejb-B may or may not exist on the same server. (There is an external property file that has the provider URLs of Ejb-B. I have no control over this.) Example Code: in Ejb-A EjbBDelegate delegateB = EjbBDelegateHelper.getRemoteDelegate(); // lookup from list of URLs from props... BookOfMagic bom = delegateB.getSomethingInteresting(); Use Cases/Outcomes: When Ejb-B DOES NOT EXIST on the same server as Ejb-A, everything works correctly. (it round-robbins through the URLs) When Ejb-B DOES EXIST on the same server, and Ejb-A happens to call Ejb-B on the same server, everything works correctly. When Ejb-B DOES EXIST on the same server, and Ejb-A calls Ejb-B on a different server, I get: javax.ejb.EJBException: nested exception is: java.lang.ClassCastException: $Proxy126 java.lang.ClassCastException: $Proxy126 NOTE (not normal use case but may help): When Ejb-B DOES EXIST on the same server, and this server is NOT listed in the provider URLs for Ejb-B, and Ejb-A calls Ejb-B on a different server, I get the same Exception as above. I'm using Weblogic 10.0, Java 5, EJB3 Basically, if Ejb-B Exists on the server, it must be called ONLY on that server. Which leads me to believe that the class is getting loaded by a local classloader (on deployment?), then when called remotely, a different classloader is loading it. (causing the Exception) But it should work, as it should be Serialized into the destination classloader... What am I doing wrong?? Also, when reproducing this locally, Ejb-A would favor the Ejb-B on the same server, so it was difficult to reproduce. But this wasn't the case on other machines.

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  • Executing a modified expression

    - by Sam
    I found this brief demo: http://msdn.microsoft.com/en-us/library/bb546136.aspx Which discusses modifying an expression. However the code starts with a Expression<Func<string, bool>> and ends up with a Expression so it's not complete. How do I take that expression and make it typed as Expression<Func<string,bool>> again? All the examples I have have found on executing an expression all involve dynamically created expressions which is not what this case has. Here the original expression is defined at compile time. And the code I want to write to do this won't know much about the expression, ideally as little as possible. I definately can't see how I would know what "Paramaters" to pass to Expression.LambdaExpression... In my particular case I want to search for any references to a particular propery of type A and swap them out with a reference to a property of type B then pass the expression to a call to IEnumerable.Where. ie. p=>p.Name == "Sam" where P is Foo1 becomes p=>p.FirstName == "Sam" where p is Foo2

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  • Command-Line Parsing API from TestAPI library - Type-Safe Commands how to

    - by MicMit
    Library at http://testapi.codeplex.com/ Excerpt of usage from http://blogs.msdn.com/ivo_manolov/archive/2008/12/17/9230331.aspx A third common approach is forming strongly-typed commands from the command-line parameters. This is common for cases when the command-line looks as follows: some-exe COMMAND parameters-to-the-command The parsing in this case is a little bit more involved: Create one class for every supported command, which derives from the Command abstract base class and implements an expected Execute method. Pass an expected command along with the command-line arguments to CommandLineParser.ParseCommand – the method will return a strongly-typed Command instance that can be Execute()-d. // EXAMPLE #3: // Sample for parsing the following command-line: // Test.exe run /runId=10 /verbose // In this particular case we have an actual command on the command-line (“run”), which we want to effectively de-serialize and execute. public class RunCommand : Command { bool? Verbose { get; set; } int? RunId { get; set; } public override void Execute() { // Implement your "run" execution logic here. } } Command c = new RunCommand(); CommandLineParser.ParseArguments(c, args); c.Execute(); ============================ I don't get if we instantiate specific class before parsing arguments , what's the point of command line argument "run" which is very first one. I thought the idea was to instantiate and execute command/class based on a command line parameter ( "run" parameter becomes instance RunCommand class, "walk" becomes WalkCommand class and so on ). Can it be done with the latest version ?

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  • Rails add a param to the end of a search query

    - by bob
    Hello, I am trying to implement a sort on the returned results of a search with rails. Filter by: 'recent' % | 'lowest_price' % | 'highest_price' % here are my links. I would like to add a filter to the end of my search query. So for example, I submit a search and I get back results and in my url I have http://localhost:3000/junks?search=handbag&condition=&category=&main_submit=Go! I would then like the user to be able to click one of the above links and have the page come back with a new query (i have this set up in the controller like such) con_id = params[:condition] if params[:category].nil? || params[:category].empty? cat_id = params[:category] results = Junk.search params[:search], :with => { :category_id => cat_id, :condition_id => con_id } case params[:filter] when "lowest_price" @junks = results.lowest_price.paginate :page => params[:page], :per_page => 12 when "highest_price" @junks = results.highest_price.paginate :page => params[:page], :per_page => 12 else @junks = results.paginate :page => params[:page], :per_page => 12 end else I would like the user to be able to click on of the above links and append a filter param to the end of the search query so that my controller can pick it up and call the correct database queries as seen in the case statement above. I'm guessing the url will look like this http://localhost:3000/junks?search=handbag&condition=&category=&main_submit=Go!&filter="lowest_price" How can I do this? Is there a better way?

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  • Silverlight DataForm Memory Leak

    - by Andrew Garrison
    Some Background I have noticed that setting the EditTemplate of a DataForm (from the Silverlight Toolkit) can cause the DataForm to not be garbage collected. Consequently, the parent control of the DataForm cannot be garbage collected either, causing a very significant memory leak. Here's some XAML which demonstrates the case. <toolkit:DataForm HorizontalAlignment="Stretch" Margin="10" VerticalAlignment="Stretch"> <toolkit:DataForm.EditTemplate> <DataTemplate> <toolkit:DataField Label="Dummy Binding:"> <TextBox Text="{Binding DummyBinding, Mode=TwoWay}" /> </toolkit:DataField> </DataTemplate> </toolkit:DataForm.EditTemplate> </toolkit:DataForm> I have opened an issue on CodePlex. The isssue has an attachment which has a project which desmonstrates the case. So, My Question Is Has anyone else encountered this issue? More importantly, does anyone know of any workarounds? How can I force this DataForm to be garbage collected?

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  • AutoMapper How To Map Object A To Object B Differently Depending On Context

    - by IanT8
    Calling all AutoMapper gurus! I'd like to be able to map object A to object B differently depending on context at runtime. In particular, I'd like to ignore certain properties in one mapping case, and have all properties mapped in another case. What I'm experiencing is that Mapper.CreateMap can be called successfully in the different mapping cases however, once CreateMap is called, the map for a particular pair of types is set and is not subsequently changed by succeeding CreateMap calls which might describe the mapping differently. I found a blog post which advocates Mapper.Reset() to get round the problem, however, the static nature of the Mapper class means that it is only a matter of time before a collision and crash occur. Is there a way to do this? What I think I need is to call Mapper.CreateMap once per appdomain, and later, be able to call Mapper.Map with hints about which properties should be included / excluded. Right now, I'm thinking about changing the source code by writing a non-static mapping class that holds the mapping config instance based. Poor performance, but thread safe. What are my options. What can be done? Automapper seems so promising.

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  • Genetic Algorithms applied to Curve Fitting

    - by devoured elysium
    Let's imagine I have an unknown function that I want to approximate via Genetic Algorithms. For this case, I'll assume it is y = 2x. I'd have a DNA composed of 5 elements, one y for each x, from x = 0 to x = 4, in which, after a lot of trials and computation and I'd arrive near something of the form: best_adn = [ 0, 2, 4, 6, 8 ] Keep in mind I don't know beforehand if it is a linear function, a polynomial or something way more ugly, Also, my goal is not to infer from the best_adn what is the type of function, I just want those points, so I can use them later. This was just an example problem. In my case, instead of having only 5 points in the DNA, I have something like 50 or 100. What is the best approach with GA to find the best set of points? Generating a population of 100, discard the worse 20% Recombine the remaining 80%? How? Cutting them at a random point and then putting together the first part of ADN of the father with the second part of ADN of the mother? Mutation, how should I define in this kind of problem mutation? Is it worth using Elitism? Any other simple idea worth using around? Thanks

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  • Marshal.StringToCoTaskMemAnsi converting non-Latin characters when sending raw data to a printer

    - by rem
    For sending raw data to a thermal DATAMAX printer I'm using RawPrinterHelper class from this Microsoft KB article. When a string sent to printer contains only Latin characters, everything is OK. But non-Latin, in my case Russian characters in a string, are not printed correct. I think the problem is in using Marshal.StringToCoTaskMemAnsi method for converting the string: public static bool SendStringToPrinter(string szPrinterName, string szString) { IntPtr pBytes; Int32 dwCount; // How many characters are in the string? dwCount = szString.Length; // Assume that the printer is expecting ANSI text, and then convert // the string to ANSI text. pBytes = Marshal.StringToCoTaskMemAnsi(szString); // Send the converted ANSI string to the printer. SendBytesToPrinter(szPrinterName, pBytes, dwCount); Marshal.FreeCoTaskMem(pBytes); return true; } Just to note, Russian characters in the string are put in hex format, like "\x83", but nevertheless the method doesn't put this hex value in unmanaged memory as it is, but converts it, I think, according with ANSI code page to a character and then printer can not read it correctly. If I try to compose a file, using Hex editor and put correct hex values in place of non-Latin characters and then send the file to a printer using another method from the same class SendFileToPrinter, everything, including Russian characters is printed correctly. How in this case the problem with sending string, containing non-Latin characters, could be solved?

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  • Collision Attacks, Message Digests and a Possible solution

    - by Dominar
    I've been doing some preliminary research in the area of message digests. Specifically collision attacks of cryptographic hash functions such as MD5 and SHA-1, such as the Postscript example and X.509 certificate duplicate. From what I can tell in the case of the postscript attack, specific data was generated and embedded within the header of the postscript (which is ignored during rendering) which brought about the internal state of the md5 to a state such that the modified wording of the document would lead to a final MD equivalent to the original. The X.509 took a similar approach where by data was injected within the comment/whitespace of the certificate. Ok so here is my question, and I can't seem to find anyone asking this question: Why isn't the length of ONLY the data being consumed added as a final block to the MD calculation? In the case of X.509 - Why is the whitespace and comments being taken into account as part of the MD? Wouldn't a simple processes such as one of the following be enough to resolve the proposed collision attacks: MD(M + |M|) = xyz MD(M + |M| + |M| * magicseed_0 +...+ |M| * magicseed_n) = xyz where : M : is the message |M| : size of the message MD : is the message digest function (eg: md5, sha, whirlpool etc) xyz : is the acutal message digest value for the message M magicseed_{i}: Is a set random values generated with seed based on the internal-state prior to the size being added. This technqiue should work, as to date all such collision attacks rely on adding more data to the original message. In short, the level of difficulty involved in generating a collision message such that: It not only generates the same MD But is also comprehensible/parsible/compliant and is also the same size as the original message, is immensely difficult if not near impossible. Has this approach ever been discussed? Any links to papers etc would be nice.

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  • How to check for server side update in iPhone application Web service request

    - by Nirmal
    Hello All.... I have kind of Listing application for iPhone application, which always calling a web service to my php server and fetching the data and displaying it onto iPhone screen. Now, the thing to consider in this scenario is, my iPhone application everytime requesting on the server and fetching the data. But now my requirement is like I want to replace following set of actions with above one : - Everytime when my application is launched in iPhone, it should check for the new data at the server`. - And if server replies "true" then only my iPhone application will made a request to fetch the data. - In case of "false", my iPhone application will display the data which is already cached in local phone memory. Now to implement this scenario at server side (which has php, mysql), I am planning with the following solution : Table : tblNewerData id newDataFlag == ============ 1 true Trigger : tgrUpdateNewData Above trigger will update the tblNewerData - newDataFlag field on Insert case of my main table. And every time my iPhone app will request for tblNewerData-newDataFlag field, and if it found true then only it will create new request, and if it founds false then the cached version of data will be displayed. So, I want to know that, is it the correct way to do so ? or else any other smart option available ? Thanks in advance.

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  • Asp.Net MVC2 Clientside Validation problem with controls with prefixes

    - by alexander
    The problem is: when I put 2 controls of the same type on a page I need to specify different prefixes for binding. In this case the validation rules generated right after the form are incorrect. So how to get client validation work for the case?: the page contains: <% Html.RenderPartial(ViewLocations.Shared.PhoneEditPartial, new PhoneViewModel { Phone = person.PhonePhone, Prefix = "PhonePhone" }); Html.RenderPartial(ViewLocations.Shared.PhoneEditPartial, new PhoneViewModel { Phone = person.FaxPhone, Prefix = "FaxPhone" }); %> the control ViewUserControl<PhoneViewModel>: <%= Html.TextBox(Model.GetPrefixed("CountryCode"), Model.Phone.CountryCode) %> <%= Html.ValidationMessage("Phone.CountryCode", new { id = Model.GetPrefixed("CountryCode"), name = Model.GetPrefixed("CountryCode") })%> where Model.GetPrefixed("CountryCode") just returns "FaxPhone.CountryCode" or "PhonePhone.CountryCode" depending on prefix And here is the validation rules generated after the form. They are duplicated for the field name "Phone.CountryCode". While the desired result is 2 rules (required, number) for each of the FieldNames "FaxPhone.CountryCode", "PhonePhone.CountryCode" The question is somewhat duplicate of http://stackoverflow.com/questions/2675606/asp-net-mvc2-clientside-validation-and-duplicate-ids-problem but the advise to manually generate ids doesn't helps.

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  • Moq and accessing called parameters

    - by lozzar
    I've just started to implement unit tests (using xUnit and Moq) on an already established project of mine. The project extensively uses dependency injection via the unity container. I have two services A and B. Service A is the one being tested in this case. Service A calls B and gives it a delegate to an internal function. This 'callback' is used to notify A when a message has been received that it must handle. Hence A calls (where b is an instance of service B): b.RegisterHandler(Guid id, Action<byte[]> messageHandler); In order to test service A, I need to be able to call messageHandler, as this is the only way it currently accepts messages. Can this be done using Moq? ie. Can I mock service B, such that when RegisterHandler is called, the value of messageHandler is passed out to my test? Or do I need to redesign this? Are there any design patterns I should be using in this case? Does anyone know of any good resources on this kind of design?

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  • Unhandled Status Event (facebook application)

    - by Fahim Akhter
    Hi, I'm getting the following error looked around couldn't find a resultion to it. I'm working on Facebook btw with flash. Warning: AllowScriptAccess='never' found in HTML. This setting is ineffective and deprecated. See http://www.adobe.com/go/allowscriptaccess for details. One of your LocalConnection variables was able to connect say: calling callFBJS a329775198094_sendShoeNumber args ["test"] say: sending to _swf416624 method: asMethod args ["10"] Error #2044: Unhandled StatusEvent:. level=error, code= This is the code I am using: var connection:LocalConnection = new LocalConnection(); var connectionName:String = LoaderInfo(this.root.loaderInfo).parameters.fb_local_connection; // Used to get information from javascript connection.allowDomain("*"); connection.client = { asMethod: function(paramOne:Number) { trace("HAVE RECIEVED SOMETHING : "+paramOne); } }; // To call the javascript function callFBJS(methodName:String, parameters:Array):void { if (connectionNameOne) { connectionOne.send(connectionNameOne, "callFBJS", methodName,parameters); } } callFBJS("sendShoeNumber", ["test"]); connection.addEventListener(StatusEvent.STATUS, testStatus); // Listener for status event function testStatus(event:StatusEvent):void { switch (event.level) { case "status": trace("One of your LocalConnection variables was able to connect"); break; case "error": trace("One of your LocalConnection variables FAILED to connect"); break; } } Have been stuck on this for a while now.

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  • Is there an "embedded DBMS" to support multiple writer applications (processes) on the same db files

    - by Amir Moghimi
    I need to know if there is any embedded DBMS (preferably in Java and not necessarily relational) which supports multiple writer applications (processes) on the same set of db files. BerkeleyDB supports multiple readers but just one writer. I need multiple writers and multiple readers. UPDATE: It is not a multiple connection issue. I mean I do not need multiple connections to a running DBMS application (process) to write data. I need multiple DBMS applications (processes) to commit on the same storage files. HSQLDB, H2, JavaDB (Derby) and MongoDB do not support this feature. I think that there may be some File System limitations that prohibit this. If so, is there a File System that allows multiple writers on a single file? Use Case: The use case is a high-throughput clustered system that intends to store its high-volume business log entries into a SAN storage. Storing business logs in separate files for each server does not fit because query and indexing capabilities are needed on the whole biz logs. Because "a SAN typically is its own network of storage devices that are generally not accessible through the regular network by regular devices", I want to use SAN network bandwidth for logging while cluster LAN bandwidth is being used for other server to server and client to server communications.

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  • MDX equivalent to SQL subqueries with aggregation

    - by James Lampe
    I'm new to MDX and trying to solve the following problem. Investigated calculated members, subselects, scope statements, etc but can't quite get it to do what I want. Let's say I'm trying to come up with the MDX equivalent to the following SQL query: SELECT SUM(netMarketValue) net, SUM(CASE WHEN netMarketValue > 0 THEN netMarketValue ELSE 0 END) assets, SUM(CASE WHEN netMarketValue < 0 THEN netMarketValue ELSE 0 END) liabilities, SUM(ABS(netMarketValue)) gross someEntity1 FROM ( SELECT SUM(marketValue) netMarketValue, someEntity1, someEntity2 FROM <some set of tables> GROUP BY someEntity1, someEntity2) t GROUP BY someEntity1 In other words, I have an account ledger where I hide internal offsetting transactions (within someEntity2), then calculate assets & liabilities after aggregating them by someEntity2. Then I want to see the grand total of those assets & liabilities aggregated by the bigger entity, someEntity1. In my MDX schema I'd presumably have a cube with dimensions for someEntity1 & someEntity2, and marketValue would be my fact table/measure. I suppose i could create another DSV that did what my subquery does (calculating net), and simply create a cube with that as my measure dimension, but I wonder if there is a better way. I'd rather not have 2 cubes (one for these net calculations and another to go to a lower level of granularity for other use cases), since it will be a lot of duplicate info in my database. These will be very large cubes.

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  • 2-step user registration with Django

    - by David S
    I'm creating a website with Django and want a fairly common 2-step user registration. What I mean by this is that the user fills in the some basic user information + some application specific information (sort of like a coupon value). Upon submit, an email is sent to ensure email address is valid. This email should contain a link to click on to "finish" the registration. When the link is clicked, the user is marked as validated and they are directed to a new page to complete optional "user profile" type information. So, pretty basic stuff. I have done some research and found django-registration by James Bennett. I do know who James is and have seen him at PyCons and DjanoCons in the past. There is obviously very few people in the world that know Django better than James (so, I know the quality of the code/app is good). But, it almost seems like a bit of over kill. I've read through the docs and was a bit confused (maybe I'm just being a bit dense today). I believe that if I do use django-registration, I will need to have some custom forms, etc. Is there anything else out there I should evaluate? Or are there any good tutorials or videos on using django-registration? I've done a bit of googling, but haven't found anything. But, I suspect that it might be a case of a lot of very common words that don't really find what you are looking for (django user registration tutorial/example). Or is just a case where it would be just about as easy to build your own solution with Django forms, etc? Here is the tech stack I'm using: Python 2.7.2 Django 1.3.1 PostgreSQL 9.1 psycopg2 2.4.1 Twitter Bootstrap 2.0.2

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  • Zend Framework: How to start PHPUnit testing Forms?

    - by Andrew
    I am having trouble getting my filters/validators to work correctly on my form, so I want to create a Unit test to verify that the data I am submitting to my form is being filtered and validated correctly. I started by auto-generating a PHPUnit test in Zend Studio, which gives me this: <?php require_once 'PHPUnit/Framework/TestCase.php'; /** * Form_Event test case. */ class Form_EventTest extends PHPUnit_Framework_TestCase { /** * @var Form_Event */ private $Form_Event; /** * Prepares the environment before running a test. */ protected function setUp () { parent::setUp(); // TODO Auto-generated Form_EventTest::setUp() $this->Form_Event = new Form_Event(/* parameters */); } /** * Cleans up the environment after running a test. */ protected function tearDown () { // TODO Auto-generated Form_EventTest::tearDown() $this->Form_Event = null; parent::tearDown(); } /** * Constructs the test case. */ public function __construct () { // TODO Auto-generated constructor } /** * Tests Form_Event->init() */ public function testInit () { // TODO Auto-generated Form_EventTest->testInit() $this->markTestIncomplete( "init test not implemented"); $this->Form_Event->init(/* parameters */); } /** * Tests Form_Event->getFormattedMessages() */ public function testGetFormattedMessages () { // TODO Auto-generated Form_EventTest->testGetFormattedMessages() $this->markTestIncomplete( "getFormattedMessages test not implemented"); $this->Form_Event->getFormattedMessages(/* parameters */); } } so then I open up terminal, navigate to the directory, and try to run the test: $ cd my_app/tests/unit/application/forms $ phpunit EventTest.php Fatal error: Class 'Form_Event' not found in .../tests/unit/application/forms/EventTest.php on line 19 So then I add a require_once at the top to include my Form class and try it again. Now it says it can't find another class. I include that one and try it again. Then it says it can't find another class, and another class, and so on. I have all of these dependencies on all these other Zend_Form classes. What should I do? How should I go about testing my Form to make sure my Validators and Filters are being attached correctly, and that it's doing what I expect it to do. Or am I thinking about this the wrong way?

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  • Static Data Structures on Embedded Devices (Android in particular)

    - by Mark
    I've started working on some Android applications and have a question regarding how people normally deal with situations where you have a static data set and have an application where that data is needed in memory as one of the standard java collections or as an array. In my current specific issue i have a spreadsheet with some pre-calculated data. It consists of ~100 rows and 3 columns. 1 Column is a string, 1 column is a float, 1 column is an integer. I need access to this data as an array in java. It seems like i could: 1) Encode in XML - This would be cpu intensive to decode in my experience. 2) build into SQLite database - seems like a lot of overhead for static access to data i only need array style access to in ram. 3) Build into binary blob and read in. (never done this in java, i miss void *) 4) Build a python script to take the CSV version of my data and spit out a java function that adds the values to my desired structure with hard coded values. 5) Store a string array via androids resource mechanism and compute the other 2 columns on application load. In my case the computation would require a lot of calls to Math.log, Math.pow and Math.floor which i'd rather not have to do for load time and battery usage reasons. I mostly work in low power embedded applications in C and as such #4 is what i'm used to doing in these situations. It just seems like it should be far easier to gain access to static data structures in java/android. Perhaps I'm just being too battery usage conscious and in my single case i imagine the answer is that it doesn't matter much, but if every application took that stance it could begin to matter. What approaches do people usually take in this situation? Anything I missed?

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  • Secure hash and salt for PHP passwords

    - by luiscubal
    It is currently said that MD5 is partially unsafe. Taking this into consideration, I'd like to know which mechanism to use for password protection. Is “double hashing” a password less secure than just hashing it once? Suggests that hashing multiple times may be a good idea. How to implement password protection for individual files? Suggests using salt. I'm using PHP. I want a safe and fast password encryption system. Hashing a password a million times may be safer, but also slower. How to achieve a good balance between speed and safety? Also, I'd prefer the result to have a constant number of characters. The hashing mechanism must be available in PHP It must be safe It can use salt (in this case, are all salts equally good? Is there any way to generate good salts?) Also, should I store two fields in the database(one using MD5 and another one using SHA, for example)? Would it make it safer or unsafer? In case I wasn't clear enough, I want to know which hashing function(s) to use and how to pick a good salt in order to have a safe and fast password protection mechanism. EDIT: The website shouldn't contain anything too sensitive, but still I want it to be secure. EDIT2: Thank you all for your replies, I'm using hash("sha256",$salt.":".$password.":".$id) Questions that didn't help: What's the difference between SHA and MD5 in PHP Simple Password Encryption Secure methods of storing keys, passwords for asp.net How would you implement salted passwords in Tomcat 5.5

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  • FileSystem.GetFiles() + UnauthorizedAccessException error?

    - by OverTheRainbow
    Hello, It seems like FileSystem.GetFiles() is unable to recover from the UnauthorizedAccessException exception that .Net triggers when trying to access an off-limit directory. In this case, does it mean this class/method isn't useful when scanning a whole drive and I should use some other solution (in which case: Which one?)? Here's some code to show the issue: Private Sub bgrLongProcess_DoWork(ByVal sender As System.Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles bgrLongProcess.DoWork Dim drive As DriveInfo Dim filelist As Collections.ObjectModel.ReadOnlyCollection(Of String) Dim filepath As String 'Scan all fixed-drives for MyFiles.* For Each drive In DriveInfo.GetDrives() If drive.DriveType = DriveType.Fixed Then Try 'How to handle "Access to the path 'C:\System Volume Information' is denied." error? filelist = My.Computer.FileSystem.GetFiles(drive.ToString, FileIO.SearchOption.SearchAllSubDirectories, "MyFiles.*") For Each filepath In filelist DataGridView1.Rows.Add(filepath.ToString, "temp") 'Trigger ProgressChanged() event bgrLongProcess.ReportProgress(0, filepath) Next filepath Catch Ex As UnauthorizedAccessException 'How to ignore this directory and move on? End Try End If Next drive End Sub Thank you. Edit: What about using a Try/Catch just to have GetFiles() fill the array, ignore the exception and just resume? Private Sub bgrLongProcess_DoWork(ByVal sender As System.Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles bgrLongProcess.DoWork 'Do lengthy stuff here Dim filelist As Collections.ObjectModel.ReadOnlyCollection(Of String) Dim filepath As String filelist = Nothing Try filelist = My.Computer.FileSystem.GetFiles("C:\", FileIO.SearchOption.SearchAllSubDirectories, "MyFiles.*") Catch ex As UnauthorizedAccessException 'How to just ignore this off-limit directory and resume searching? End Try 'Object reference not set to an instance of an object For Each filepath In filelist bgrLongProcess.ReportProgress(0, filepath) Next filepath End Sub

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  • Query Optimizing Request

    - by mithilatw
    I am very sorry if this question is structured in not a very helpful manner or the question itself is not a very good one! I need to update a MSSQL table call component every 10 minutes based on information from another table call materials_progress I have nearly 60000 records in component and more than 10000 records in materials_progress I wrote an update query to do the job, but it takes longer than 4 minutes to complete execution! Here is the query : UPDATE component SET stage_id = CASE WHEN t.required_quantity <= t.total_received THEN 27 WHEN t.total_ordered < t.total_received THEN 18 ELSE 18 END FROM ( SELECT mp.job_id, mp.line_no, mp.component, l.quantity AS line_quantity, CASE WHEN mp.component_name_id = 2 THEN l.quantity*2 ELSE l.quantity END AS required_quantity, SUM(ordered) AS total_ordered, SUM(received) AS total_received , c.component_id FROM line l LEFT JOIN component c ON c.line_id = l.line_id LEFT JOIN materials_progress mp ON l.job_id = mp.job_id AND l.line_no = mp.line_no AND c.component_name_id = mp.component_name_id WHERE mp.job_id IS NOT NULL AND (mp.cancelled IS NULL OR mp.cancelled = 0) AND (mp.manual_override IS NULL OR mp.manual_override = 0) AND c.stage_id = 18 GROUP BY mp.job_id, mp.line_no, mp.component, l.quantity, mp.component_name_id, component_id ) AS t WHERE component.component_id = t.component_id I am not going to explain the scenario as it too complex.. could somebody please please tell me what makes this query this much expensive and a way to get around it? Thank you very very much in advance!!!

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  • How can I return json from my WCF rest service (.NET 4), using Json.Net, without it being a string,

    - by Samuel Meacham
    The DataContractJsonSerializer is unable to handle many scenarios that Json.Net handles just fine when properly configured (specifically, cycles). A service method can either return a specific object type (in this case a DTO), in which case the DataContractJsonSerializer will be used, or I can have the method return a string, and do the serialization myself with Json.Net. The problem is that when I return a json string as opposed to an object, the json that is sent to the client is wrapped in quotes. Using DataContractJsonSerializer, returning a specific object type, the response is: {"Message":"Hello World"} Using Json.Net to return a json string, the response is: "{\"Message\":\"Hello World\"}" I do not want to have to eval() or JSON.parse() the result on the client, which is what I would have to do if the json comes back as a string, wrapped in quotes. I realize that the behavior is correct; it's just not what I want/need. I need the raw json; the behavior when the service method's return type is an object, not a string. So, how can I have my method return an object type, but not use the DataContractJsonSerializer? How can I tell it to use the Json.Net serializer instead? Or, is there someway to directly write to the response stream? So I can just return the raw json myself? Without the wrapping quotes? Here is my contrived example, for reference: [DataContract] public class SimpleMessage { [DataMember] public string Message { get; set; } } [ServiceContract] [AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)] [ServiceBehavior(InstanceContextMode = InstanceContextMode.Single)] public class PersonService { // uses DataContractJsonSerializer // returns {"Message":"Hello World"} [WebGet(UriTemplate = "helloObject")] public SimpleMessage SayHelloObject() { return new SimpleMessage("Hello World"); } // uses Json.Net serialization, to return a json string // returns "{\"Message\":\"Hello World\"}" [WebGet(UriTemplate = "helloString")] public string SayHelloString() { SimpleMessage message = new SimpleMessage() { Message = "Hello World" }; string json = JsonConvert.Serialize(message); return json; } // I need a mix of the two. Return an object type, but use the Json.Net serializer. }

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  • iOS iPad UIActionSheet Issue

    - by hart1994
    I am currently developing an application which needs an option to 'share' using multiple services; such as email, twitter. To to this, I have a UIBarButtonItem coded in and when touched, it triggers this: UIActionSheet *sheet = [[UIActionSheet alloc] initWithTitle:@"" delegate:self cancelButtonTitle:nil destructiveButtonTitle:nil otherButtonTitles:nil]; [sheet addButtonWithTitle:@"Email"]; [sheet addButtonWithTitle:@"Tweet"]; [sheet addButtonWithTitle:@"Cancel"]; sheet.cancelButtonIndex = sheet.numberOfButtons-1; [sheet showFromRect:self.view.bounds inView:self.view animated:YES]; [sheet release]; In conjunction with this to detect which button is selected: clickedButtonAtIndex:(NSInteger)buttonIndex { if (buttonIndex == actionSheet.cancelButtonIndex) { return; } switch (buttonIndex) { case 0: { [self emailThis]; break; } case 1: { [self tweetThis]; break; } } This works a treat on the iPhone. But unfortunately it displays incorrectly on the iPad. It looks like it is trying to display the UIPopoverController, but it is positioned center of the navbar with practically no height. I have looked into using the UIPopoverController, but I cannot seem to find out how to use it with buttons. Is there anyway I can adapt the code above to properly display the buttons, as it's trying to already. Many thanks, Ryan PS: I'm new to objective-c/iOS coding, so please be specific. Thank you :)

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  • Cocoa Touch UITableView Alphabetical '#' Match All Unmatched

    - by Kevin Sylvestre
    I have a UITableView containing names that I would like to group (and sort) by the first letter (similar to the Address Book application). I am currently able to match any section ('A'-'Z') using: // Sections is an array of strings "{search}" and "A" to "Z" and "#". NSString *pattern = [self.sections objectAtIndex:section]; NSPredicate *predicate = nil; // Ignore search pattern. if ([pattern isEqualToString:@"{search}"]) return nil; // Non-Alpha and Non-Diacritic-Alpha (?). if ([pattern isEqualToString:@"#"]); // Default case (use case and diacritic insensitivity). if (!predicate) predicate = [NSPredicate predicateWithFormat:@"name beginswith[cd] %@", pattern]; // Return filtered results. return [self.friends filteredArrayUsingPredicate:predicate]; However, matching for the '#' eludes me. I tried constructing a REGEX match using: [NSPredicate predicateWithFormat:@"name matches '[^a-zA-Z].*'"]; But this fails for diacritic-alpha (duplicate rows appear). Any ideas would be greatly appreciated! Thanks.

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