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• Good resources for building web-app in Tapestry

  - by Rich

  Hi, I'm currently researching into Tapestry for my company and trying to decide if I think we can port our pre-existing proprietary web applications to something better. Currently we are running Tomcat and using JSP for our front end backed by our own framework that eventually uses JDBC to connect to an Oracle database. I've gone through the Tapestry tutorial, which was really neat and got me interested, but now I'm faced with what seems to be a common issue of documentation. There are a lot of things I'd need to be sure that I could accomplish with Tapestry before I'd be ready to commit fully to it. Does anyone have any good resources, be it a book or web article or anything else, that go into more detail beyond what the Tapestry tutorial explains? I am also considering integrating with Hibernate, and have read a little bit about Spring too. I'm still having a hard time understanding how Spring would be more useful than cumbersome in tandem with Tapestry,as they seem to have a lot of overlapping features. An example I read seemed to use Spring to interface with Hibernate, and then Tapestry to Spring, but I was under the impression Tapestry integrates to the same degree with Hibernate. The resource I'm speaking of is http://wiki.apache.org/tapestry/Tapstry5First_project_with_Tapestry5,_Spring_and_Hibernate . I was interested because I hadn't found information anywhere else on how to maintain user levels and sessions through a Tapestry application before, but wasn't exactly impressed by the need to use Spring in the example.

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• Writing to EEPROM on PIC

  - by JB

  Are there any PIC microcontroller programmers here? I'm learning some PIC microcontroller programming using a pickit2 and the 16F690 chip that came with it. I'm working through trying out the various facilities at the moment. I can sucessfully read a byte from the EEPROM in code if I set the EEPROM vaklue in MPLAB but I don't seem to be able to modify the value using the PIC itsself. Simply nothing happens and I don't read back the modified value, I always get the original which implies to me that the write isn't working? This is my code for that section, am I missing something? I know I'm doing a lot of unnecessary bank switches, I added most of them to ensure that being on the wrong bank wasn't the issue. ; ------------------------------------------------------ ; Now SET the EEPROM location ZERO to 0x08 ; ------------------------------------------------------ BANKSEL EEADR CLRF EEADR ; Set EE Address to zero BANKSEL EEDAT MOVLW 0x08 ; Store the value 0x08 in the EEPROM MOVWF EEDAT BANKSEL EECON1 BSF EECON1, WREN ; Enable writes to the EEPROM BANKSEL EECON2 MOVLW 0x55 ; Do the thing we have to do so MOVWF EECON2 ; that writes can work MOVLW 0xAA MOVWF EECON2 BANKSEL EECON1 BSF EECON1, WR ; And finally perform the write WAIT BTFSC EECON1, WR ; Wait for write to finish GOTO WAIT BANKSEL PORTC ; Just to make sure we are on the right bank

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• update variable based upon results from .NET backgroundworker

  - by Bruce

  I've got a C# program that talks to an instrument (spectrum analyzer) over a network. I need to be able to change a large number of parameters in the instrument and read them back into my program. I want to use backgroundworker to do the actual talking to the instrument so that UI performance doesn't suffer. The way this works is - 1) send command to the instrument with new parameter value, 2) read parameter back from the instrument so I can see what actually happened (for example, I try to set the center frequency above the max that the instrument will handle and it tells me what it will actually handle), and 3) update a program variable with the actual value received from the instrument. Because there are quite a few parameters to be updated I'd like to use a generic routine. The part I can't seem to get my brain around is updating the variable in my code with what comes back from the instrument via backgroundworker. If I used a separate RunWorkerCompleted event for each parameter I could hardwire the update directly to the variable. I'd like to come up with a way of using a single routine that's capable of updating any of the variables. All I can come up with is passing a reference number (different for each parameter) and using a switch statement in the RunWorkerCompleted handler to direct the result. There has to be a better way.

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• Getting Started with AJAX ToolKit Controls

  - by Aviran

  I am trying to make my first AJAX Control and I get error. I probbly missed some steps but I cann't find them eventhough I read many tutorials, probbly since I am new in AJAX, so I need to be guided step-by-step. These are the steps I've already done: Downloading AJAX ToolKit. Adding These Controls to the ToolBox. creating new ASP.NET Website (I heard about AJAX-Enabled Option, but I dont have this option) Adding a AJAX Tool. And thats it. I read that I need to register add AjaxControlToolkit.dll in application bin folder, but I dont know how to do that and I dont have Bin Folder in my website, only App_Data Folder. than I need to add this to the web config: <add tagPrefix="ajaxToolkit" namespace="AjaxControlToolkit" assembly="AjaxControlToolkit"/> than I need to add this to my website: <asp:ScriptManager ID="scriptmanager1" EnablePartialRendering="true" runat="Server" /> This is the error I receive: "Compilation Error Description: An error occurred during the compilation of a resource required to service this request. Please review the following specific error details and modify your source code appropriately. Compiler Error Message: CS0012: The type 'System.Web.UI.ExtenderControl' is defined in an assembly that is not referenced. You must add a reference to assembly 'System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35'." Source Error: Line 16: <br /> Line 17: <asp:Label ID="Label1" runat="server" Text="Label" Width="229px"></asp:Label><br /> Line 18: <asp:ConfirmButtonExtender ID="ConfirmButtonExtender1" runat="server" ConfirmText="are you sure" Line 19: TargetControlID="Button1"> Line 20: </asp:ConfirmButtonExtender> Does anyone know how can I solve this error?

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• label as dynamic navigation

  - by KareemSaad

  I Made label to had value from database and linked it . but the problem was it had only one value and i want it keep value when navigation thought site as. xyz.... this is my code < if (Request.QueryString["Category_Id"] != null) { Banar.ImageUrl = "Handlers/Banner.ashx?Category_Id=" + Request.QueryString["Category_Id"] + ""; using (SqlConnection conn = Connection.GetConnection()) { SqlCommand cmd = new SqlCommand(); cmd.Connection = conn; cmd.CommandType = CommandType.StoredProcedure; cmd.CommandText = "Navcategory"; cmd.Parameters.Add(Parameter.NewInt("@Category_Id", Request.QueryString["Category_Id"])); SqlDataReader dr = cmd.ExecuteReader(); if (dr.Read()) { LblNavigaton.Visible = true; LblNavigaton.Text = dr[i].ToString(); NavHref.HRef = "ListView.aspx?Category_Id=" + Request.QueryString["Category_Id"] + ""; } } } else if (Request.QueryString["ProductCategory_Id"] != null) { Banar.ImageUrl = "Handlers/ProCatBanner.ashx?ProductCategory_Id=" + Request.QueryString["ProductCategory_Id"] + ""; using (SqlConnection conn = Connection.GetConnection()) { SqlCommand cmd = new SqlCommand(); cmd.Connection = conn; cmd.CommandType = CommandType.StoredProcedure; cmd.CommandText = "NavProductcategory"; cmd.Parameters.Add(Parameter.NewInt("@ProductCategory_Id", Request.QueryString["ProductCategory_Id"])); SqlDataReader dr = cmd.ExecuteReader(); if (dr.Read()) { LblNavigaton.Visible = true; LblNavigaton.Text = dr["Name"].ToString(); NavHref.HRef = "ListView.aspx?ProductCategory_Id=" + Request.QueryString["ProductCategory_Id"] + ""; } else { LblNavigaton.Visible = true; LblNavigaton.Text = Page.Title; } }

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• Isolated storage misunderstand

  - by Costa

  Hi this is a discussion between me and me to understand isolated storage issue. can you help me to convince me about isolated storage!! This is a code written in windows form app (reader) that read the isolated storage of another win form app (writer) which is signed. where is the security if the reader can read the writer's file, I thought only signed code can access the file! If all .Net applications born equal and have all permissions to access Isolated storage, where is the security then? If I can install and run Exe from isolated storage, why I don't install a virus and run it, I am trusted to access this area. but the virus or what ever will not be trusted to access the rest of file system, it only can access the memory, and this is dangerous enough. I cannot see any difference between using app data folder to save the state and using isolated storage except a long nasty path!! I want to try give low trust to Reader code and retest, but they said "Isolated storage is actually created for giving low trusted application the right to save its state". Reader code: private void button1_Click(object sender, EventArgs e) { String path = @"C:\Documents and Settings\All Users\Application Data\IsolatedStorage\efv5cmbz.ewt\2ehuny0c.qvv\StrongName.5v3airc2lkv0onfrhsm2h3uiio35oarw\AssemFiles\toto12\ABC.txt"; StreamReader reader = new StreamReader(path); var test = reader.ReadLine(); reader.Close(); } Writer: private void button1_Click(object sender, EventArgs e) { IsolatedStorageFile isolatedFile = IsolatedStorageFile.GetMachineStoreForAssembly(); isolatedFile.CreateDirectory("toto12"); IsolatedStorageFileStream isolatedStorage = new IsolatedStorageFileStream(@"toto12\ABC.txt", System.IO.FileMode.Create, isolatedFile); StreamWriter writer = new StreamWriter(isolatedStorage); writer.WriteLine("Ana 2akol we ashrab kai a3eesh wa akbora"); writer.Close(); writer.Dispose(); }

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• IIS7 GrantByDefault

  - by jonot

  I have an application (written in c#) that allow me to set IIS to allow or deny access to a website from all ip addresses. The application works fine for IIS6 however it does not work with IIS 7 (even with IIS 6 WMI Compatibility installed). heres the code (basically) Type typ = this.Entry.Properties[IIsWebDirectoryProperty.IPSecurity][0].GetType(); var securityProp = this.Entry.Properties[IIsWebDirectoryProperty.IPSecurity][0]; typ.InvokeMember("GrantByDefault", BindingFlags.DeclaredOnly | BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance | BindingFlags.SetProperty, null, securityProp, new object[] { IPSecurity.GrantByDefault }); this.Entry.CommitChanges(); I have checked the metabase for both IIS6 and IIS7 using the metabase explorer and the only diffecnce I can see is that the "IPSecurity" property does not appear in IIS7 until you also add a an allow or deny IP address, through IIS Manager. Whats really got me stumped is that even when I edit the feature setting to Deny access in the IIS Manager there is no change to the metabase or to the web.config in the site root! So how/where is this property being set and read from? And how can I set and read value of this property programmatically?

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• MySQL return Deadlock with insert row and FK is locked 'for update'

  - by constantin-slednev

  Hello developers! I get deadlock error in my mysql transaction. The simple example of my situation: Thread1 > set autocommit=0; Query OK, 0 rows affected (0.00 sec) Thread1 > SET TRANSACTION ISOLATION LEVEL READ COMMITTED; Query OK, 0 rows affected (0.00 sec) Thread1 > SELECT * FROM A WHERE ID=1000 FOR UPDATE; 1 row in set (0.00 sec) Thread2 > set autocommit=0; Query OK, 0 rows affected (0.00 sec) Thread2 > SET TRANSACTION ISOLATION LEVEL READ COMMITTED; Query OK, 0 rows affected (0.00 sec) Thread2 > INSERT INTO B (AID, NAME) VALUES (1000, 'Hello world'); SLEEP Query OK, 1 row affected (4.99 sec) Thread1 > INSERT INTO B (AID, NAME) VALUES (1000, 'Hello world2'); ERROR 1213 (40001): Deadlock found when trying to get lock; try restarting transaction B.AID -> FK -> A.ID I see three solutions: catch deadlock error in code and retry query. use innodb_locks_unsafe_for_binlog in my.cnf lock (for update) table A in Thread2 before insert Can you give me more solutions ? Current solutions do not fit me.

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• Prevent illegal behavior to the registered user

  - by Al Kush

  I am building a website in which this website will be focused on the publishing of novels. Every writers who publish their novels with us will get a royalty from us. And this royalty comes from the user or the reader who read the novel online in our website. When a user search for a novel and want to read that, they will click a link to the page which its content is that novel. The html page for each novels will have a session function that first will force them to login or register to make a payment such as with a credit-card or paypal before accessing that html page. My problem now is if the user has succesfully login and access the html page, I am afraid if the user will copy the content of the novel. Some disccussion out here How to Disable Copy Paste (Browser) have a solution to create it in Flash so that it can't be coppied-paste. But the I think, if the user who access it is a web developer like us they will try to find the path of the file from the link in the page source, and then they can steal it. For now I think it is enough I am explaining this. I hope anyone fully accept this problem (question) with a good idea to solve it.

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• Reading HTML table data / html tag

  - by user348038

  I have some 50 pages of html which have around 100-plus rows of data in each, with all sort of CSS style, I want to read the html file and just get the data, like Name, Age, Class, Teacher. and store it in Database, but I am not able to read the html tags e.g space i kept to display it here <table class="table_100"> <tr> <td class="col_1"> <span class="txt_student">Gauri Singh</span><br> <span class="txt_bold">13</span><br> <span class="txt_bold">VIII</span><br> </td> <td class="col_2"> <span class="txt_teacher">Praveen M</span><br> <span class="txt_bold">3494</span><br> <span class="txt_bold">3Star</span><br> </td> <td class="col_3"> </td> </tr> </table>

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• What can cause Windows to unhook a low level (global) keyboard hook?

  - by Davy8

  We have some global keyboard hooks installed via SetWindowsHookEx with WH_KEYBOARD_LL that appear to randomly get unhooked by Windows. We verified that they hook was no longer attached because calling UnhookWindowsHookEx on the handle returns false. (Also verified that it returns true when it was working properly) There doesn't seem to be a consistent repro, I've heard that they can get unhooked due to timeouts or exceptions getting thrown, but I've tried both just letting it sit on a breakpoint in the handling method for over a minute, as well as just throwing a random exception (C#) and it still appears to work. In our callback we quickly post to another thread, so that probably isn't the issue. I've read about solutions in Windows 7 for setting the timeout higher in the registry because Windows 7 is more aggressive about the timeouts apparently (we're all running Win7 here, so not sure if this occurs on other OS's) , but that doesn't seem like an ideal solution. I've considered just having a background thread running to refresh the hook every once in a while, which is hackish, but I don't know of any real negative consequences of doing that, and it seems better than changing a global Windows registry setting. Any other suggestions or solutions? The delegates are not being GC'd since they're static members, which is one cause that I've read about.

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• even PHP has 'bugs' with IE

  - by silversky

  It's not a real bug BUT for sure it is not what you would expect. I have this sample code to upload images: <?php if($type=="image/jpg" || $type=="image/jpeg" || $type=="image/pjpeg" || $type=="image/tiff" || $type=="image/gif" || $type=="image/png") { // make upload else echo "Incorect format ...."; ?> The problem is that that if I modify the extention of an image, let's say to .jpgq or even .jpg% and i try to upload it FF and Chrome will say that the file"s type is "application/octet-stream" and normaly the condition will be false BUT since IE is 'smarter' that other brow. it will say that the file is "image/pjeg and the condition will be true and the file will be uploaded and of course latter any brow. will not be able to read / view the image. It is not a bug because on msdn.microsoft.com it says that: "If the "suggested" (server-provided) MIME type is unknown (not known and not ambiguous), FindMimeFromData immediately returns this MIME type" and "If the server-provided MIME type is either known or ambiguous, the buffer is scanned in an attempt to verify or obtain a MIME type from the actual content." plus others 'inovative solutions from Microsoft'. SO my questions are: Why is IE so 'smart' and when I upload the file to server it knows the real MIME type BUT it will fail to read it from the server ? How can i work around this issue (if the file doesn't have the right extention the condition has to be false)? Is it wise to check the extention format (and not the MIME type)? is any of the above extention not recomended to use ? Should I add others?

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• python-xmpp and looping through list of recipients to receive and IM message

  - by David

  I can't figure out the problem and want some input as to whether my Python code is incorrect, or if this is an issue or design limitation of Python XMPP library. I'm new to Python by the way. Here's snippets of code in question below. What I'd like to do is read in a text file of IM recipients, one recipient per line, in XMPP/Jabber ID format. This is read into a Python list variable. I then instantiate an XMPP client session and loop through the list of recipients and send a message to each recipient. Then sleep some time and repeat test. This is for load testing the IM client of recipients as well as IM server. There is code to alternately handle case of taking only one recipient from command line input instead of from file. What ends up happening is that Python does iterate/loop through the list but only last recipient in list receives message. Switch order of recipients to verify. Kind of looks like Python XMPP library is not sending it out right, or I'm missing a step with the library calls, because the debug print statements during runtime indicate the looping works correctly. recipient = "" delay = 60 useFile = False recList = [] ... elif (sys.argv[i] == '-t'): recipient = sys.argv[i+1] useFile = False elif (sys.argv[i] == '-tf'): fil = open(sys.argv[i+1], 'r') recList = fil.readlines() fil.close() useFile = True ... # disable debug msgs cnx = xmpp.Client(svr,debug=[]) cnx.connect(server=(svr,5223)) cnx.auth(user,pwd,'imbot') cnx.sendInitPresence() while (True): if useFile: for listUser in recList: cnx.send(xmpp.Message(listUser,msg+str(msgCounter))) print "sending to "+listUser+" msg = "+msg+str(msgCounter) else: cnx.send(xmpp.Message(recipient,msg+str(msgCounter))) msgCounter += 1 time.sleep(delay)

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• Parsing large delimited files with dynamic number of columns

  - by annelie

  Hi, What would be the best approach to parse a delimited file when the columns are unknown before parsing the file? The file format is Rightmove v3 (.blm), the structure looks like this: #HEADER# Version : 3 EOF : '^' EOR : '~' #DEFINITION# AGENT_REF^ADDRESS_1^POSTCODE1^MEDIA_IMAGE_00~ // can be any number of columns #DATA# agent1^the address^the postcode^an image~ agent2^the address^the postcode^^~ // the records have to have the same number of columns as specified in the definition, however they can be empty etc #END# The files can potentially be very large, the example file I have is 40Mb but they could be several hundred megabytes. Below is the code I had started on before I realised the columns were dynamic, I'm opening a filestream as I read that was the best way to handle large files. I'm not sure my idea of putting every record in a list then processing is any good though, don't know if that will work with such large files. List<string> recordList = new List<string>(); try { using (FileStream fs = new FileStream(path, FileMode.Open, FileAccess.Read)) { StreamReader file = new StreamReader(fs); string line; while ((line = file.ReadLine()) != null) { string[] records = line.Split('~'); foreach (string item in records) { if (item != String.Empty) { recordList.Add(item); } } } } } catch (FileNotFoundException ex) { Console.WriteLine(ex.Message); } foreach (string r in recordList) { Property property = new Property(); string[] fields = r.Split('^'); // can't do this as I don't know which field is the post code property.PostCode = fields[2]; // etc propertyList.Add(property); } Any ideas of how to do this better? It's C# 3.0 and .Net 3.5 if that helps. Thanks, Annelie

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• Change userSettings during MSI installation

  - by pagetailor

  Hi, I am trying to modify the userSettings section (Properties.MyApp.Default) in the MyApp.exe.config file during the installation using an MSI installer. I basically implemented it like in this excellent article: http://raquila.com/software/configure-app-config-application-settings-during-msi-install/ The difference is that I am not editing the appSettings but the userSettings section. The problem is that although the code runs fine, the settings are not saved. After the installation the config file contains the old settings I use in my development environment. I also tried to override OnAfterInstall(System.Collections.IDictionary stateSaver) instead of Install(System.Collections.IDictionary stateSaver) but it doesn't make a difference. Here is the code that should change the config values: protected override void OnAfterInstall(IDictionary savedState) { base.OnAfterInstall(savedState); string targetDirectory = Context.Parameters["targetdir"]; string tvdbAccountID = Context.Parameters["TVDBACCID"]; // read other config elements... Properties.Settings.Default.Tvdb_AccountIdentifier = tvdbAccountID; // set other config elements Properties.Settings.Default.Save(); } Any idea how to persist these changes? I already read about Wix but that seems like an overkill to me. Thanks in advance!

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• How to use SQLAlchemy to dump an SQL file from query expressions to bulk-insert into a DBMS?

  - by Mahmoud Abdelkader

  Please bear with me as I explain the problem, how I tried to solve it, and my question on how to improve it is at the end. I have a 100,000 line csv file from an offline batch job and I needed to insert it into the database as its proper models. Ordinarily, if this is a fairly straight-forward load, this can be trivially loaded by just munging the CSV file to fit a schema, but I had to do some external processing that requires querying and it's just much more convenient to use SQLAlchemy to generate the data I want. The data I want here is 3 models that represent 3 pre-exiting tables in the database and each subsequent model depends on the previous model. For example: Model C --> Foreign Key --> Model B --> Foreign Key --> Model A So, the models must be inserted in the order A, B, and C. I came up with a producer/consumer approach: - instantiate a multiprocessing.Process which contains a threadpool of 50 persister threads that have a threadlocal connection to a database - read a line from the file using the csv DictReader - enqueue the dictionary to the process, where each thread creates the appropriate models by querying the right values and each thread persists the models in the appropriate order This was faster than a non-threaded read/persist but it is way slower than bulk-loading a file into the database. The job finished persisting after about 45 minutes. For fun, I decided to write it in SQL statements, it took 5 minutes. Writing the SQL statements took me a couple of hours, though. So my question is, could I have used a faster method to insert rows using SQLAlchemy? As I understand it, SQLAlchemy is not designed for bulk insert operations, so this is less than ideal. This follows to my question, is there a way to generate the SQL statements using SQLAlchemy, throw them in a file, and then just use a bulk-load into the database? I know about str(model_object) but it does not show the interpolated values. I would appreciate any guidance for how to do this faster. Thanks!

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• Problem locating file in a classpath

  - by Gandalf StormCrow

  I'm trying to read in file content, ex : public void myMethod(){ FileInputStream fstream = new FileInputStream(fileLocation); // Get the object of DataInputStream DataInputStream in = new DataInputStream(fstream); BufferedReader br = new BufferedReader(new InputStreamReader(in)); String strLine; while ((strLine = br.readLine()) != null) { .... .... ..... end while end method And I have at the begining of the class body private String fileLocation; and at the end of a class I have a getter and setter for it. Now I'm trying inject this file location from spring inside bean from this class and I specify the init-method of this class. But I get error cannot find the specified file as if its not on a classpath but it is inside war file? I'm building the project with maven and I put file in src/main/resources This is the error I get when trying to read file : Error: src\main\resources\ids.txt (The system cannot find the path specified) That is when I tried this : FileInputStream fstream = new FileInputStream("src\\main\\resources\\ids.txt"); how to reference the properly from the classpath? EDIT When I edit my code according to @BalusC solution , here is how it looks but I still get null error : ClassLoader classLoader = Thread.currentThread().getContextClassLoader(); InputStream input = classLoader.getResourceAsStream("src/main/resources/ids.txt"); // Get the object of DataInputStream BufferedReader br = new BufferedReader(new InputStreamReader(input)); String strLine; while ((strLine = br.readLine()) != null) { .... .... ..... end while end method

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• Restricting dynamically loaded classes and jars based on a security policy

  - by Max

  Hi, I would like to dynamically load a set of jars or classes (i.e. plugins loaded at runtime). At the same time, I would like to restrict what these plugins are able to do in the JVM. For a test case, I would like to restrict them to pretty much everything (right now I'm just allowing one System.getProperty value to be read). I am currently using a security policy file, but I'm having difficulty specifying a policy for one folder or package in my codeBase, but not another. Here is how my policy looks now: grant codeBase "file:/home/max/programming/java/plugin/plugins/" { permission java.util.PropertyPermission "java.version", "read"; }; grant codeBase "file:/home/max/programming/java/plugin/api/" { permission java.security.AllPermission; }; Where (for testing purposes), all files in the plugins package and folder are restricted, but the classes in the api folder are not. Is this possible? Do I have to create a custom class loader? Is there a better way to go about doing this? Thanks.

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• Lightweight spinlocks built from GCC atomic operations?

  - by Thomas

  I'd like to minimize synchronization and write lock-free code when possible in a project of mine. When absolutely necessary I'd love to substitute light-weight spinlocks built from atomic operations for pthread and win32 mutex locks. My understanding is that these are system calls underneath and could cause a context switch (which may be unnecessary for very quick critical sections where simply spinning a few times would be preferable). The atomic operations I'm referring to are well documented here: http://gcc.gnu.org/onlinedocs/gcc-4.4.1/gcc/Atomic-Builtins.html Here is an example to illustrate what I'm talking about. Imagine a RB-tree with multiple readers and writers possible. RBTree::exists() is read-only and thread safe, RBTree::insert() would require exclusive access by a single writer (and no readers) to be safe. Some code: class IntSetTest { private: unsigned short lock; RBTree<int>* myset; public: // ... void add_number(int n) { // Aquire once locked==false (atomic) while (__sync_bool_compare_and_swap(&lock, 0, 0xffff) == false); // Perform a thread-unsafe operation on the set myset->insert(n); // Unlock (atomic) __sync_bool_compare_and_swap(&lock, 0xffff, 0); } bool check_number(int n) { // Increment once the lock is below 0xffff u16 savedlock = lock; while (savedlock == 0xffff || __sync_bool_compare_and_swap(&lock, savedlock, savedlock+1) == false) savedlock = lock; // Perform read-only operation bool exists = tree->exists(n); // Decrement savedlock = lock; while (__sync_bool_compare_and_swap(&lock, savedlock, savedlock-1) == false) savedlock = lock; return exists; } }; (lets assume it need not be exception-safe) Is this code indeed thread-safe? Are there any pros/cons to this idea? Any advice? Is the use of spinlocks like this a bad idea if the threads are not truly concurrent? Thanks in advance. ;)

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• Embedded SQL in OO languages like Java

  - by Steve De Caux

  One of the things that annoys me working with SQL in OO languages is having to define SQL statements in strings. When I used to work on IBM mainframes, the languages used an SQL preprocessor to parse SQL statements out of the native code, so the statements could be written in cleartext SQL without the obfuscation of strings, for instance in Cobol there is a EXEC SQL .... END-EXEC syntax construct that allows pure SQL statements to be embedded in the Cobol code. <pure cobol code, including assignment of value to local variable HOSTVARIABLE> EXEC SQL SELECT COL_A, COL_B, COL_C INTO :COLA, :COLB, :COLC FROM TAB_A WHERE COL_D = :HOSTVARIABLE END_EXEC <more cobol code, variables COLA, COLB, COLC have been set> ...this makes the SQL statement really easy to read & check for errors. Between the EXEC SQL .... END-EXEC tokens there are no constraints on indentation, linebreaking etc., so you can format the SQL statement according to taste. Note that this example is for a single-row select, when a multiple-row resultset is expected, the coding is different (but still v. easy to read). So, taking Java as an example What made the "old COBOL" approach undesirable ? Not only SQL, but system calls could be made much more readable with that approach. Let's call it the embedded foreign language preprocessor approach. Would an embedded foreign language preprocessor for SQL be useful to implement ? Would you see a benefit in being able to write native SQL statements inside java code ? Edit I'm really asking if you think SQL in OO languages is a throwback, and if not then what could be done to make it better.

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• Run a .java file using ProcessBuilder

  - by David K

  I'm a novice programmer working in Eclipse, and I need to get multiple processes running (this is going to be a simulation of a multi-computer system). My initial hackup used multiple threads to multiple classes, but now I'm trying to replace the threads with processes. From my reading, I've gleaned that ProcessBuilder is the way to go. I have tried many many versions of the input you see below, but cannot for the life of me figure out how to properly use it. I am trying to run the .java files I previously created as classes (which I have modified). I eventually just made a dummy test.java to make sure my process is working properly - its only function is to print that it ran. My code for the two files are below. Am I using ProcessBuilder correctly? Is this the correct way to read the output of my subprocess? Any help would be much appreciated. David primary process package Control; import java.io.*; import java.lang.*; public class runSPARmatch { /** * @param args */ public static void main(String args[]) { try { ProcessBuilder broker = new ProcessBuilder("javac.exe","test.java","src\\Broker\\"); Process runBroker = broker.start(); Reader reader = new InputStreamReader(runBroker.getInputStream()); int ch; while((ch = reader.read())!= -1) System.out.println((char)ch); reader.close(); runBroker.waitFor(); System.out.println("Program complete"); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } } } subprocess package Broker; public class test { /** * @param args */ public static void main(String[] args) { // TODO Auto-generated method stub System.out.println("This works"); } }

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• as3crypto PEM.readRSAPublicKey returns null

  - by www.jefferyfernandez.id.au

  I am trying to implement a bit of encryption in my Air application while communication with a PHP backend server. For this purpose I am using as3crypto library and I can't read the public key to make the encryption possible. Here is my action script code: var rsa:RSAKey = PEM.readRSAPublicKey(this.readApplicationFileContents('server.crt')); if ( rsa ) { var encodeSource:ByteArray = Hex.toArray(Hex.fromString("Hello World")); var encodeDestination:ByteArray = new ByteArray; var encodeDestination2:ByteArray = new ByteArray; rsa.encrypt(encodeSource, encodeDestination, encodeSource.length) rsa.decrypt(encodeDestination, encodeDestination2, encodeDestination.length); trace(encodeDestination2.toString()); } private function readApplicationFileContents(filePath:String):String { var fileObject:File = File.applicationDirectory.resolvePath(filePath); var fileStream:FileStream = new FileStream(); fileStream.open(fileObject, FileMode.READ); var fileContents:String = fileStream.readUTFBytes(fileStream.bytesAvailable); return(fileContents); } readApplicationFileContents function returns the proper certificate contents as a string. But rsa variable always returns null. It would have been easier if I was able to compile the as3crypto library so I can debug through the source, but I can't get the library to compile and can't find any instructions to do the same. Anyone have a clue what's wrong? PS. Sorry first time poster and I can't seem to get the syntax highlighting right. Must be Chrome is not working well with the editor.

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• Making HTTP POST request

  - by infrared

  I'm trying to make a POST request to retrieve information about a book. Here is the code that returns HTTP code: 302, Moved import httplib, urllib params = urllib.urlencode({ 'isbn' : '9780131185838', 'catalogId' : '10001', 'schoolStoreId' : '15828', 'search' : 'Search' }) headers = {"Content-type": "application/x-www-form-urlencoded", "Accept": "text/plain"} conn = httplib.HTTPConnection("bkstr.com:80") conn.request("POST", "/webapp/wcs/stores/servlet/BuybackSearch", params, headers) response = conn.getresponse() print response.status, response.reason data = response.read() conn.close() When I try from a browser, from this page: http://www.bkstr.com/webapp/wcs/stores/servlet/BuybackMaterialsView?langId=-1&catalogId=10001&storeId=10051&schoolStoreId=15828 , it works. What am I missing in my code? Thanks EDIT: Here's what I get when I call print response.msg 302 Moved Date: Tue, 07 Sep 2010 16:54:29 GMT Vary: Host,Accept-Encoding,User-Agent Location: http://www.bkstr.com/webapp/wcs/stores/servlet/BuybackSearch X-UA-Compatible: IE=EmulateIE7 Content-Length: 0 Content-Type: text/plain; charset=utf-8 Seems that the location points to the same url I'm trying to access in the first place? EDIT2: I've tried using urllib2 as suggested here. Here is the code: import urllib, urllib2 url = 'http://www.bkstr.com/webapp/wcs/stores/servlet/BuybackSearch' values = {'isbn' : '9780131185838', 'catalogId' : '10001', 'schoolStoreId' : '15828', 'search' : 'Search' } data = urllib.urlencode(values) req = urllib2.Request(url, data) response = urllib2.urlopen(req) print response.geturl() print response.info() the_page = response.read() print the_page And here is the output: http://www.bkstr.com/webapp/wcs/stores/servlet/BuybackSearch Date: Tue, 07 Sep 2010 16:58:35 GMT Pragma: No-cache Cache-Control: no-cache Expires: Thu, 01 Jan 1970 00:00:00 GMT Set-Cookie: JSESSIONID=0001REjqgX2axkzlR6SvIJlgJkt:1311s25dm; Path=/ Vary: Accept-Encoding,User-Agent X-UA-Compatible: IE=EmulateIE7 Content-Length: 0 Connection: close Content-Type: text/html; charset=utf-8 Content-Language: en-US Set-Cookie: TSde3575=225ec58bcb0fdddfad7332c2816f1f152224db2f71e1b0474c866f3b; Path=/

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• Dynamically create a text file from a C# program

  - by techstu

  Can I dynamically create a text file from a C# program, using data from a previously created xml file and text file, I have written half the code, but can't go any further please help using System; using System.IO; using System.Xml; namespace Task3 { class TextFileReader { static void Main(string[] args) { String strn=" ", strsn=String.Empty; XmlTextReader reader = new XmlTextReader("my.xml"); while (reader.Read()) { switch (reader.NodeType) { case XmlNodeType.Element: // The node is an element. if (reader.HasAttributes) { strn = reader.GetAttribute(0); strsn = reader.GetAttribute(1); int counter = 0; string line; // Read the file and display it line by line. System.IO.StreamReader file = new System.IO.StreamReader("read_file.txt"); string ch, ch1; while ((line = file.ReadLine()) != null) { if (line.Substring(0, 1).Equals("%")) { int a = line.IndexOf('%'); int b = line.LastIndexOf('%'); ch = line.Substring(a + 1, b - 1); ch1 = line.Substring(a, b+1); if (ch == "name") { string test = line.Replace(ch1, strn); Console.WriteLine(test); } else if (ch == "sirname") { string test = line.Replace(ch1, strsn); Console.WriteLine(test); } } else { Console.WriteLine(line); } counter++; } file.Close(); } break; } } // Suspend the screen. Console.ReadLine(); } } } the xml file from which i am reading is: <?xml version="1.0" encoding="utf-8" ?> - <Workflow> <User UserName="pqr" Sirname="sbd" /> <User UserName="abc" Sirname="xyz" /> </Workflow> and the text file is: hi this is me %sirname% %name% but this is not wat i want..please help

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• vtk glyphs 3D, indenpently color and rotation

  - by user3684219

  I try to display thanks to vtk (python wrapper) several glyphs in a scene with each their own colour and rotation. Unfortunately, just the rotation (using vtkTensorGlyph) is taken in consideration by vtk. Reversely, just color is taken in consideration when I use a vtkGlyph3D. Here is a ready to use piece of code with a vtkTensorGlyph. Each cube should have a random color but there all will be in the same color. I read and read again the doc of vtk but I found no solution. Thanks in advance for any idea #!/usr/bin/env python # -*- coding: utf-8 -*- import vtk import scipy.linalg as sc import random as ra import numpy as np import itertools points = vtk.vtk.vtkPoints() # where to locate each glyph in the scene tensors = vtk.vtkDoubleArray() # rotation for each glyph tensors.SetNumberOfComponents(9) colors = vtk.vtkUnsignedCharArray() # should be the color for each glyph colors.SetNumberOfComponents(3) # let's make 10 cubes in the scene for i in range(0, 50, 5): points.InsertNextPoint(i, i, i) # position of a glyph colors.InsertNextTuple3(ra.randint(0, 255), ra.randint(0, 255), ra.randint(0, 255) ) # pick random color rot = list(itertools.chain(*np.reshape(sc.orth(np.random.rand(3, 3)).transpose(), (1, 9)).tolist())) # random rotation matrix (row major) tensors.InsertNextTuple9(*rot) polydata = vtk.vtkPolyData() # create the polydatas polydata.SetPoints(points) polydata.GetPointData().SetTensors(tensors) polydata.GetPointData().SetScalars(colors) cubeSource = vtk.vtkCubeSource() cubeSource.Update() glyphTensor = vtk.vtkTensorGlyph() glyphTensor.SetColorModeToScalars() # is it really work ? try: glyphTensor.SetInput(polydata) except AttributeError: glyphTensor.SetInputData(polydata) glyphTensor.SetSourceConnection(cubeSource.GetOutputPort()) glyphTensor.ColorGlyphsOn() # should not color all cubes independently ? glyphTensor.ThreeGlyphsOff() glyphTensor.ExtractEigenvaluesOff() glyphTensor.Update() # next is usual vtk code mapper = vtk.vtkPolyDataMapper() mapper.SetInputConnection(glyphTensor.GetOutputPort()) actor = vtk.vtkActor() actor.SetMapper(mapper) ren = vtk.vtkRenderer() ren.SetBackground(0.2, 0.5, 0.3) ren.AddActor(actor) renwin = vtk.vtkRenderWindow() renwin.AddRenderer(ren) iren = vtk.vtkRenderWindowInteractor() iren.SetInteractorStyle(vtk.vtkInteractorStyleTrackballCamera()) iren.SetRenderWindow(renwin) renwin.Render() iren.Initialize() renwin.Render() iren.Start()

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