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  • How hide some nodes in Richfaces Tree (do not render nodes by condition)?

    - by VestniK
    I have a tree of categories and courses in my SEAM application. Courses may be active and inactive. I want to be able to show only active or all courses in my tree. I've decided to always build complete tree in my PAGE scope component since building this tree is quite expensive operation. I have boolean flag courseActive in the data wrapped by TreeNode<T>. Now I can't find the way to show courses node only if this flag is true. The best result I've achieved with the following code: <h:outputLabel for="showInactiveCheckbox" value="show all courses: "/> <h:selectBooleanCheckbox id="showInactiveCheckbox" value="#{categoryTreeEditorModel.showAllCoursesInTree}"> <a4j:support event="onchange" reRender="categoryTree"/> </h:selectBooleanCheckbox> <rich:tree id="categoryTree" value="#{categoryTree}" var="item" switchType="ajax" ajaxSubmitSelection="true" reRender="categoryTree,controls" adviseNodeOpened="#{categoryTreeActions.adviseRootOpened}" nodeSelectListener="#{categoryTreeActions.processSelection}" nodeFace="#{item.typeName}"> <rich:treeNode type="Category" icon="..." iconLeaf="..."> <h:outputText value="#{item.title}"/> </rich:treeNode> <rich:treeNode type="Course" icon="..." iconLeaf="..." rendered="#{item.courseActive or categoryTreeEditorModel.showAllCoursesInTree}"> <h:outputText rendered="#{item.courseActive}" value="#{item.title}"/> <h:outputText rendered="#{not item.courseActive}" value="#{item.title}" style="color:#{a4jSkin.inactiveTextColor}"/> </rich:treeNode> </rich:tree> the only problem is if some node is not listed in any rich:treeNode it just still shown with title obtained by Object.toString() method insted of being hidden. Does anybody know how to not show some nodes in the Richfases tree according to some condition?

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  • Aggregating a list of dates to start and end date

    - by Joe Mako
    I have a list of dates and IDs, and I would like to roll them up into periods of consucitutive dates, within each ID. For a table with the columns "testid" and "pulldate" in a table called "data": | A79 | 2010-06-02 | | A79 | 2010-06-03 | | A79 | 2010-06-04 | | B72 | 2010-04-22 | | B72 | 2010-06-03 | | B72 | 2010-06-04 | | C94 | 2010-04-09 | | C94 | 2010-04-10 | | C94 | 2010-04-11 | | C94 | 2010-04-12 | | C94 | 2010-04-13 | | C94 | 2010-04-14 | | C94 | 2010-06-02 | | C94 | 2010-06-03 | | C94 | 2010-06-04 | I want to generate a table with the columns "testid", "group", "start_date", "end_date": | A79 | 1 | 2010-06-02 | 2010-06-04 | | B72 | 2 | 2010-04-22 | 2010-04-22 | | B72 | 3 | 2010-06-03 | 2010-06-04 | | C94 | 4 | 2010-04-09 | 2010-04-14 | | C94 | 5 | 2010-06-02 | 2010-06-04 | This is the the code I came up with: SELECT t2.testid, t2.group, MIN(t2.pulldate) AS start_date, MAX(t2.pulldate) AS end_date FROM(SELECT t1.pulldate, t1.testid, SUM(t1.check) OVER (ORDER BY t1.testid,t1.pulldate) AS group FROM(SELECT data.pulldate, data.testid, CASE WHEN data.testid=LAG(data.testid,1) OVER (ORDER BY data.testid,data.pulldate) AND data.pulldate=date (LAG(data.pulldate,1) OVER (PARTITION BY data.testid ORDER BY data.pulldate)) + integer '1' THEN 0 ELSE 1 END AS check FROM data ORDER BY data.testid, data.pulldate) AS t1) AS t2 GROUP BY t2.testid,t2.group ORDER BY t2.group; I use the use the LAG windowing function to compare each row to the previous, putting a 1 if I need to increment to start a new group, I then do a running sum of that column, and then aggregate to the combinations of "group" and "testid". Is there a better way to accomplish my goal, or does this operation have a name? I am using PostgreSQL 8.4

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  • Is this overly clever or unsafe?

    - by Liberalkid
    I was working on some code recently and decided to work on my operator overloading in c++, because I've never really implemented it before. So I overloaded the comparison operators for my matrix class using a compare function that returned 0 if LHS was less than RHS, 1 if LHS was greater than RHS and 2 if they were equal. Then I exploited the properties of logical not in c++ on integers, to get all of my compares in one line: inline bool Matrix::operator<(Matrix &RHS){ return ! (compare(*this,RHS)); } inline bool Matrix::operator>(Matrix &RHS){ return ! (compare((*this),RHS)-1); } inline bool Matrix::operator>=(Matrix &RHS){ return compare((*this),RHS); } inline bool Matrix::operator<=(Matrix &RHS){ return compare((*this),RHS)-1; } inline bool Matrix::operator!=(Matrix &RHS){ return compare((*this),RHS)-2; } inline bool Matrix::operator==(Matrix &RHS){ return !(compare((*this),RHS)-2); } Obviously I should be passing RHS as a const, I'm just probably not going to use this matrix class again and I didn't feel like writing another function that wasn't a reference to get the array index values solely for the comparator operation.

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  • What is the fastest way to get a DataTable into SQL Server?

    - by John Gietzen
    I have a DataTable in memory that I need to dump straight into a SQL Server temp table. After the data has been inserted, I transform it a little bit, and then insert a subset of those records into a permanent table. The most time consuming part of this operation is getting the data into the temp table. Now, I have to use temp tables, because more than one copy of this app is running at once, and I need a layer of isolation until the actual insert into the permanent table happens. What is the fastest way to do a bulk insert from a C# DataTable into a SQL Temp Table? I can't use any 3rd party tools for this, since I am transforming the data in memory. My current method is to create a parameterized SqlCommand: INSERT INTO #table (col1, col2, ... col200) VALUES (@col1, @col2, ... @col200) and then for each row, clear and set the parameters and execute. There has to be a more efficient way. I'm able to read and write the records on disk in a matter of seconds...

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  • MPI Odd/Even Compare-Split Deadlock

    - by erebel55
    I'm trying to write an MPI version of a program that runs an odd/even compare-split operation on n randomly generated elements. Process 0 should generated the elements and send nlocal of them to the other processes, (keeping the first nlocal for itself). From here, process 0 should print out it's results after running the CompareSplit algorithm. Then, receive the results from the other processes run of the algorithm. Finally, print out the results that it has just received. I have a large chunk of this already done, but I'm getting a deadlock that I can't seem to fix. I would greatly appreciate any hints that people could give me. Here is my code http://pastie.org/3742474 Right now I'm pretty sure that the deadlock is coming from the Send/Recv at lines 134 and 151. I've tried changing the Send to use "tag" instead of myrank for the tag parameter..but when I did that I just keep getting a "MPI_ERR_TAG: invalid tag" for some reason. Obviously I would also run the algorithm within the processors 0 but I took that part out for now, until I figure out what is going wrong. Any help is appreciated.

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  • Crash using WscRegisterForChanges.

    - by user335126
    I'm trying to use the WscRegisterForChanges with C++ function in Windows 7. Documentation located here: http://msdn.microsoft.com/en-us/library/bb432507(v=VS.85).aspx My problem is that even though the callback properly executes, the code crashes when it gets to the end of the callback's execution. Here's the code in question. It's very simple, so I'm not sure why it's crashing: #include #include #include void SecurityCenterChangeOccurred(void *param) { printf("Change occurred!\n"); } int main() { HRESULT result = S_OK; HANDLE callbackRegistration = NULL; result = WscRegisterForChanges( NULL, &callbackRegistration, (LPTHREAD_START_ROUTINE)SecurityCenterChangeOccurred, NULL); while(1) { Sleep(100); } return 0; } My call stack looks like this when the crash occurs: 00faf6e8() ntdll.dll!_TppWorkerThread@4() + 0x1293 bytes kernel32.dll!@BaseThreadInitThunk@12() + 0x12 bytes ntdll.dll!___RtlUserThreadStart@8() + 0x27 bytes ntdll.dll!__RtlUserThreadStart@8() + 0x1b bytes If I add ExitThread(0); to the end of SecurityCenterChangeOccurred, I get an error and the following trace (So I don't think I should be using ExitThread): Unhandled exception at 0x7799852b (ntdll.dll) in WscRegisterForChangesCrash.exe: 0xC000071C: An invalid thread, handle %p, is specified for this operation. Possibly, a threadpool worker thread was specified. ntdll.dll!_TpCheckTerminateWorker@4() + 0x3ca2f bytes ntdll.dll!_RtlExitUserThread@4() + 0x30 bytes WscRegisterForChangesCrash.exe!SecurityCenterChangeOccurred(void * param=0x00000000) Line 8 + 0xa bytes C++ wscapi.dll!WorkItemWrapper() + 0x19 bytes ntdll.dll!_RtlpTpWorkCallback@8() + 0xdf bytes ntdll.dll!_TppWorkerThread@4() + 0x1293 bytes kernel32.dll!@BaseThreadInitThunk@12() + 0x12 bytes ntdll.dll!___RtlUserThreadStart@8() + 0x27 bytes ntdll.dll!__RtlUserThreadStart@8() + 0x1b bytes Does anyone have any ideas why this might be happening? To trigger the crash run the program and turn the firewall on or off.

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  • Injecting the application TransactionManager into a JPA EntityListener

    - by nodje
    I want to use the JPA EntityListener to support spring security ACLs. On @PostPersist events, I create a permission corresponding to the persisted entity. I need this operation to participate to the current Transaction. For this to happen I need to have a reference to the application TransactionManager in the EntityListener. The problem is, Spring can't manage the EntityListener as it is created automatically when EntityManagerFactory is instantiated. And in a classic Spring app, the EntityManagerFactory is itself created during the TransactioManager instantiation. <bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager"> <property name="entityManagerFactory" ref="entityManagerFactory" /> </bean> So I have no way to inject the TransactionManager with the constructor, as it is not yet instantiated. Making the EntityManager a @Component create another instance of the EntityManager. Implementing InitiliazingBean and using afterPropertySet() doesn't work as it's not a Spring managed bean. Any idea would be helpful as I'm stuck and out of ideas.

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  • Diff/Merge functionality for objects (not files!)

    - by gehho
    I have a collection of objects of the same type, let's call it DataItem. The user can view and edit these items in an editor. It should also be possible to compare and merge different items, i.e. some sort of diff/merge for DataItem instances. The DIFF functionality should compare all (relevant) properties/fields of the items and detect possible differences. The MERGE functionality should then be able to merge two instances by applying selected differences to one of the items. For example (pseudo objects): DataItem1 { DataItem2 { Prop1 = 10 Prop1 = 10 Prop2 = 25 Prop2 = 13 Prop3 = 0 Prop3 = 5 Coll = { 7, 4, 8 } Coll = { 7, 4, 8, 12 } } } Now, the user should be provided with a list of differences (i.e. Prop2, Prop3, and Coll) and he should be able to select which differences he wants to eliminate by assigning the value from one item to the other. He should also be able to choose if he wants to assign the value from DataItem1 to DataItem2 or vice versa. Are there common practices which should be used to implement this functionality? Since the same editor should also provide undo/redo functionality (using the Command pattern), I was thinking about reusing the ICommand implementations because both scenarios basically handle with property assignments, collection changes, and so on... My idea was to create Difference objects with ICommand properties which can be used to perform a merge operation for this specific Difference. Btw: The programming language will be C# with .NET 3.5SP1/4.0. However, I think this is more of a language-independent question. Any design pattern/idea/whatsoever is welcome!

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  • PHP – Slow String Manipulation

    - by Simon Roberts
    I have some very large data files and for business reasons I have to do extensive string manipulation (replacing characters and strings). This is unavoidable. The number of replacements runs into hundreds of thousands. It's taking longer than I would like. PHP is generally very quick but I'm doing so many of these string manipulations that it's slowing down and script execution is running into minutes. This is a pain because the script is run frequently. I've done some testing and found that str_replace is fastest, followed by strstr, followed by preg_replace. I've also tried individual str_replace statements as well as constructing arrays of patterns and replacements. I'm toying with the idea of isolating string manipulation operation and writing in a different language but I don't want to invest time in that option only to find that improvements are negligible. Plus, I only know Perl, PHP and COBOL so for any other language I would have to learn it first. I'm wondering how other people have approached similar problems? I have searched and I don't believe that this duplicates any existing questions.

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  • IIS doesn't send two responses to the same client at the same time (only for ASP)

    - by dr. evil
    I've got 2 ASP pages. I do a request to the first page from Firefox (which takes 30 seconds to process on server-side), and during the execution of 30 seconds I do another request from Firefox to the second page (takes less than 1 second in server-side), but it does come after 31 second. Because it waits first requests to finish. When I request to the first page from Firefox and then request the second page from IE it's just instant. So basically ASP - IIS 6 somehow limiting every client to one request (long processing request) at a time. I need to get around this problem in my .NET client application. This is tested in 3 different systems. If you want to test you can try the ASP scripts at the end. This behaviour is same in a long SQL execution or just in a time consuming ASP operation. Note: It's not about HTTP Keep Alive It's not about persistent connection limit (we tried to increase this in firefox and in .NET with Net.ServicePointManager.DefaultConnectionLimit) It's not about User Agent This doesn't happen in ASP.NET so I assume it's something to the with ASP.dll I'm trying to solve this on the client not the server. I don't have direct control over the server it's a 3rd party solution. Is there any way to get around this? Sample ASP Code: First ASP: <% Set cnn = Server.CreateObject("Adodb.Connection") cnn.Open "Provider=sqloledb;Data Source=.;Initial Catalog=master;User Id=sa;Password=;" cnn.Execute("WAITFOR DELAY '0:0:30'") cnn.Close %> Second ASP: <% Response.Write "bla bla" %>

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  • VB.net avoiding cross thread exception with extension method

    - by user574632
    Hello I am trying to implement a solution for updating form controls without using a delegate. I am attempting to use the 1st solution on this page: http://www.dreamincode.net/forums/blog/143/entry-2337-handling-the-dreaded-cross-thread-exception/ Imports System.ComponentModel Imports System.Runtime.CompilerServices Public Module MyInvoke <Extension()> _ Public Sub CustomInvoke(Of T As ISynchronizeInvoke)(ByVal control As T, ByVal toPerform As Action(Of T)) If control.InvokeRequired Then control.Invoke(toPerform, New Object() {control}) toPerform(control) End If End Sub End Module The site gives this as example of how to use: Label1.CustomInvoke(l => l.Text = "Hello World!") But i get 'l' is not declared error. As you can see im very new to VB or any OOP. I can get the second solution on that page to work (using delegates) but i have quite a few things to do in this thread and it seems like i would need to write a new delegate sub for each thing, which seems wasteful. What i need to do is select the 1st item from a combobox, update a textbox.text with the selected item, and pass the selected item to a function. Then wait for x seconds and start again, selecting the second item. I can get it to work in a single threaded application, but i need the interface to remain responsive. Any help greatly appreciated. EDIT: OK so changing the syntax worked for the example. However if i change it from Label1.CustomInvoke(Sub(l) l.text = "hello world!") (which worked just fine) to: Dim indexnumber As Integer = 0 ComboBox1.CustomInvoke(Sub(l) l.SelectedIndex = indexnumber) I get a cross threading error as though i didnt even use this method: Cross-thread operation not valid: Control 'ComboBox1' accessed from a thread other than the thread it was created on. So now im back to where i started? Any further help very much appreciated.

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  • Why is CoRegisterClassObject creating two extra threads?

    - by Stijn Sanders
    I'm trying to fix a problem that only recently happens on a number of machine's on a VPN. They each run a client application I wrote that exposes a COM automation object. For some strange reason I haven't been able to discover yet, one thread in the application takes up all of the available CPU time, slowing other operation on the machine. In observing the application's strange behaviour, I've noticed it's the third thread started, and if I debug on my machine I notice the first call to CoRegisterClassObject created two extra threads. If the second of these two threads is the one that gets into an infinite loop, I'm not at all shure how to fix this. Where could I check next about what's wrong? Could it have started by one of the recent patches rolled out by Microsoft this last 'patch tuesday'? I had a go with ProcessExplorer to extract a stack trace of the thread: ntoskrnl.exe!ExReleaseResourceLite+0x1a3 ntoskrnl.exe!PsGetContextThread+0x329 WLDAP32.dll!Ordinal325+0x1231 WLDAP32.dll!Ordinal325+0x129e WLDAP32.dll!Ordinal325+0x1178 ntdll.dll!LdrInitializeThunk+0x24 ntdll.dll!LdrShutdownThread+0xe9 kernel32.dll!ExitThread+0x3e kernel32.dll!FreeLibraryAndExitThread+0x1e ole32.dll!StringFromGUID2+0x65d kernel32.dll!GetModuleFileNameA+0x1ba

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  • perl - universal operator overload

    - by Todd Freed
    I have an idea for perl, and I'm trying to figure out the best way to implement it. The idea is to have new versions of every operator which consider the undefined value as the identity of that operation. For example: $a = undef + 5; # undef treated as 0, so $a = 5 $a = undef . "foo"; # undef treated as '', so $a = foo $a = undef && 1; # undef treated as false, $a = true and so forth. ideally, this would be in the language as a pragma, or something. use operators::awesome; However, I would be satisfied if I could implement this special logic myself, and then invoke it where needed: use My::Operators; The problem is that if I say "use overload" inside My::Operators only affects objects blessed into My::Operators. So the question is: is there a way (with "use overoad" or otherwise) to do a "universal operator overload" - which would be called for all operations, not just operations on blessed scalars. If not - who thinks this would be a great idea !? It would save me a TON of this kind of code if($object && $object{value} && $object{value} == 15) replace with if($object{value} == 15) ## the special "is-equal-to" operator

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  • Android - save/restore state of custom class

    - by user1209216
    I have some class for ssh support - it uses jsch internally. I use this class on main activity, this way: public class MainActivity extends Activity { SshSupport ssh = new SshSupport(); ..... @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); //Handle events for ssh ssh.eventHandler = new ISshEvents() { @Override public void SshCommandExecuted(SshCommandsEnum commandType, String result) { } //other overrides here } //Ssh operations on gui item click @Override public void onItemClick(AdapterView<?> arg0, View v, int position, long arg3) { if (ssh.IsConnected() == false) { try { ssh.ConnectAsync(/*parameters*/); } catch (Exception e) { e.printStackTrace(); } } try { ssh.ExecuteCommandAsync(SshCommandsEnum.values()[position]); } catch (Exception e) { e.printStackTrace(); } } }); } It works very well. My application connects to ssh, performs all needed operation in background thread and results are reported to gui, via events as shown above. But nothing works after user change device orientation. It's clear for me - activity is re-created and all state is lost. Unfortunately, my SshSupport class object is lost as well. It's pretty easy to store gui state for dynamically changed/added objects (using put/get serializable etc methods). But I have no idea how to prevent my ssh object, ssh connected session being lost. Since my class is not serializable, I can't save it to bundle. Also, even if I make my SshSupport class serializable, jsch objects it uses still are not serializable. So what is the best way to solve this?

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  • FileSystemWatcher Work is Done?

    - by Snowy
    I setup a FsWatcher on a local filesystem directory. I only want to know when files are added to the directory so they can be moved to another filesystem. I seem to be able to detect when the first file is in, but actually I want to know when all files from a given copy operation are done. If I used Windows Explorer to copy files from one directory to another, Explorer would tell me that there are n seconds left in the transfer, so while there is some activity for the begin-transfer and end-transfer for each file, it appears that there is something for the begin-transfer and end-transfer for all files. I wonder if there is something similar that I can do just with the .NET Framework. I would like to know when "all" files are in and not just a single file in a "transaction". If there is nothing baked in, maybe I should come up with some kind of waiting/countering in order to only do my activity when a job is "done". Not sure if I'm making 100% sense on this one, please anyone comment. Thanks.

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  • How to get around LazyInitializationException in scheduled jobs?

    - by Shreerang
    I am working on a J2EE server application which is deployed on Tomcat. I use Spring source as MVC framework and Hibernate as ORM provider. My object model has lot of Lazy relationships (dependent objects are fetched on request). The high level design is like Service level methods call a few DAO methods to perform database operation. The service method is called either from the Flex UI or as a scheduled job. When it is called from Flex UI, the service method works fine i.e. it fetches some objects using DAO methods and even Lazy loading works. This is possible by the use of OpenSessionInViewFilter configured with the UI servlet. But when the same service method is called as scheduled Job, it gives LazyInitializationException. I can not configure OpenSessionInViewFilter because there is no servlet or UI request associated with that. I tried configuring Transaction around the scheduled job method so that service method starts a transaction and all the DAO methods participate in that same transaction, hoping that the transaction will remain active and hibernate session will be available. But it does not work. Please suggest if anyone has ever been able to get such a configuration working. If needed, I can post the Hibernate configuration and log messages. Thanks a lot for help! Shreerang

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  • Creating new image in a loop using OpenCV

    - by user565415
    I am programing some image conversion code with OpenCV and I don't know how can I create image memory buffer to load image on every iteration. I have number of iteration (maxImNumber) and I have an input image. In every loop program must create image that is resized and modified input image. Here is some basic code (concept). for (int imageIndex = 0; imageIndex < maxImNumber; imageIndex++){ cvCopy(inputImage, images[imageIndex], 0); cvReleaseImage(&inputImage); images[imageIndex+1] = cvCreateImage(cvSize((image[imageIndex]->width)/2, image[imageIndex]->height), IPL_DEPTH_8U, 1); for (i=1; i < image[imageIndex]->height; i++) { index = 0; // for(j=0; j < image[imageIndex]->width ; j=j+2){ // doing some basic matematical operation on image content and store it to new image images[imageIndex+1][i][index] = (image[imageIndex][i][j] + image[imageIndex][i][j+2])/2; index++ } } inputImage = cvCreateImage(cvSize((image[imageIndex+1]->width), image[imageIndex]->height), IPL_DEPTH_8U, 1); cvCopy(images[imageIndex+1], inputImage, 0); } Can somebody, please, explain how can I create this image buffer (images[]) and allocate memory for it. Also how can I access any image in this buffer? Thank you very much in advance!

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  • numpy array assignment problem

    - by Sujan
    Hi All: I have a strange problem in Python 2.6.5 with Numpy. I assign a numpy array, then equate a new variable to it. When I perform any operation to the new array, the original's values also change. Why is that? Please see the example below. Kindly enlighten me, as I'm fairly new to Python, and programming in general. -Sujan >>> import numpy as np >>> a = np.array([[1,2],[3,4]]) >>> b = a >>> b array([[1, 2], [3, 4]]) >>> c = a >>> c array([[1, 2], [3, 4]]) >>> c[:,1] = c[:,1] + 5 >>> c array([[1, 7], [3, 9]]) >>> b array([[1, 7], [3, 9]]) >>> a array([[1, 7], [3, 9]])

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  • How to set buffer size in client-server app using sockets?

    - by nelly
    First of all i am new to networking so i may say dumb thing in here. Considering a client-server application using sockets(.net with c# if that matters). The client sends some data, the server process it and sends back a string. The client sends some other data, the serve process it, queries the db and sends back several hundreds of items from the database The client sends some other type of data and the server notifies some other clients . My question is how to set the buffer size correctly for reading/writing operation. Should i do something like this: byte[] buff = new byte[client.ReceiveBufferSize] ? I am thinking of something like this: Client sends data to the server(and the server will follow the same pattern) byte[] bytesToSend=new byte[2048] //2048 to be standard for any command send by the client bytes 0..1 ->command type bytes 1..2047 ->command parameters byte[] bytesToReceive=new byte[8]/byte[64]/byte[8192] //switch(command type) But..what is happening when a client is notified by the server without sending data? What is the correct way to accomplish what i am trying to do? Thanks for reading.

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  • What's the best way to send user-inputted text via AJAX to Google App Engine?

    - by Cuga
    I'm developing in Google App Engine (python sdk) and I want to use jQuery to send an Ajax request to store an answer to a question. What is the best way to send this data to the server? Currently I have: function storeItem(question_id) { var answerInputControl = ".input_answer_"+question_id; var answer_text = $(answerInputControl).text(); $.ajax({ type: "POST", url: "store_answer.html", data: "question="+question_id, success: function(responseText){ alert("Retrieved: " + responseText); } }); } This takes a question Id and provides it to the server via the query string. But on the server-side, I'm unable to access the content of the answer control which I want to store. Without Ajax, I'm able to perform this operation with the following: class StoreAnswers(webapp.RequestHandler): def post(self): question_id = self.request.get("question_id") answer_text = self.request.get("input_answer" + question_id) But when doing this call through Ajax, my answer_text is empty. Do I need to send the contents of this control as part of the data with the Ajax request? Do I add the control itself to the query string? Its contents? Does it matter that the content might be a few hundred characters long? Is this the most-recommended practice? If sending it as a query string, what's the best way to escape the content so that a malicious user doesn't harm the system?

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  • Is locking on the requested object a bad idea?

    - by Quick Joe Smith
    Most advice on thread safety involves some variation of the following pattern: public class Thing { private static readonly object padlock = new object(); private string stuff, andNonsense; public string Stuff { get { lock (Thing.padlock) { if (this.stuff == null) this.stuff = "Threadsafe!"; } return this.stuff; } } public string AndNonsense { get { lock (Thing.padlock) { if (this.andNonsense == null) this.andNonsense = "Also threadsafe!"; } return this.andNonsense; } } // Rest of class... } In cases where the get operations are expensive and unrelated, a single locking object is unsuitable because a call to Stuff would block all calls to AndNonsense, degrading performance. And rather than create a lock object for each call, wouldn't it be better to acquire the lock on the member itself (assuming it is not something that implements SyncRoot or somesuch for that purpose? For example: public string Stuff { get { lock (this.stuff) { // Pretend that this is a very expensive operation. if (this.stuff == null) this.stuff = "Still threadsafe and good?"; } return this.stuff; } } Strangely, I have never seen this approach recommended or warned against. Am I missing something obvious?

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  • Parse files in directory/insert in database

    - by jakesankey
    Hey there, Here is my dillema... I have a directory full of .txt comma delimited files arranged as shown below. What I want to do is to import each of these into a SQL or SQLite database, appending each one below the last. (1 table)... I am open to C# or VB scripting and just not sure how to accomplish this. I want to only extract and import the data starting BELOW the 'Feat. Type,Feat. Name, etc' line. These are stored in a \mynetwork\directory\stats folder on my network drive. Ideally I will be able to add functionality that will make the software/script know not to re-add the file to the database once it has already done so as well. Any guidance or tips is appreciated! $$ SAMPLE= $$ FIXTURE=- $$ OPERATOR=- $$ INSPECTION PROCESS=CMM #4 $$ PROCESS OPERATION=- $$ PROCESS SEQUENCE=- $$ TRIAL=- Feat. Type,Feat. Name,Value,Actual,Nominal,Dev.,Tol-,Tol+,Out of Tol.,Comment Point,_FF_PLN_A_1,X,-17.445,-17.445,0.000,-999.000,999.000,, Point,_FF_PLN_A_1,Y,-195.502,-195.502,0.000,-999.000,999.000,, Point,_FF_PLN_A_1,Z,32.867,33.500,-0.633,-0.800,0.800,, Point,_FF_PLN_A_2,X,-73.908,-73.908,0.000,-999.000,999.000,, Point,_FF_PLN_A_2,Y,-157.957,-157.957,0.000,-999.000,999.000,, Point,_FF_PLN_A_2,Z,32.792,33.500,-0.708,-0.800,0.800,, Point,_FF_PLN_A_3,X,-100.180,-100.180,0.000,-999.000,999.000,, Point,_FF_PLN_A_3,Y,-142.797,-142.797,0.000,-999.000,999.000,, Point,_FF_PLN_A_3,Z,32.768,33.500,-0.732,-0.800,0.800,, Point,_FF_PLN_A_4,X,-160.945,-160.945,0.000,-999.000,999.000,, Point,_FF_PLN_A_4,Y,-112.705,-112.705,0.000,-999.000,999.000,, Point,_FF_PLN_A_4,Z,32.719,33.500,-0.781,-0.800,0.800,, Point,_FF_PLN_A_5,X,-158.096,-158.096,0.000,-999.000,999.000,, Point,_FF_PLN_A_5,Y,-73.821,-73.821,0.000,-999.000,999.000,, Point,_FF_PLN_A_5,Z,32.756,33.500,-0.744,-0.800,0.800,, Point,_FF_PLN_A_6,X,-195.670,-195.670,0.000,-999.000,999.000,, Point,_FF_PLN_A_6,Y,-17.375,-17.375,0.000,-999.000,999.000,, Point,_FF_PLN_A_6,Z,32.767,33.500,-0.733,-0.800,0.800,, Point,_FF_PLN_A_7,X,-173.759,-173.759,0.000,-999.000,999.000,, Point,_FF_PLN_A_7,Y,14.876,14.876,0.000,-999.000,999.000,,

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  • Efficient database access when dealing with multiple abstracted repositories

    - by Nathan Ridley
    I want to know how most people are dealing with the repository pattern when it involves hitting the same database multiple times (sometimes transactionally) and trying to do so efficiently while maintaining database agnosticism and using multiple repositories together. Let's say we have repositories for three different entities; Widget, Thing and Whatsit. Each repository is abstracted via a base interface as per normal decoupling design processes. The base interfaces would then be IWidgetRepository, IThingRepository and IWhatsitRepository. Now we have our business layer or equivalent (whatever you want to call it). In this layer we have classes that access the various repositories. Often the methods in these classes need to do batch/combined operations where multiple repositories are involved. Sometimes one method may make use of another method internally, while that method can still be called independently. What about, in this scenario, when the operation needs to be transactional? Example: class Bob { private IWidgetRepository _widgetRepo; private IThingRepository _thingRepo; private IWhatsitRepository _whatsitRepo; public Bob(IWidgetRepository widgetRepo, IThingRepository thingRepo, IWhatsitRepository whatsitRepo) { _widgetRepo = widgetRepo; _thingRepo= thingRepo; _whatsitRepo= whatsitRepo; } public void DoStuff() { _widgetRepo.StoreSomeStuff(); _thingRepo.ReadSomeStuff(); _whatsitRepo.SaveSomething(); } public void DoOtherThing() { _widgetRepo.UpdateSomething(); DoStuff(); } } How do I keep my access to that database efficient and not have a constant stream of open-close-open-close on connections and inadvertent invocation of MSDTS and whatnot? If my database is something like SQLite, standard mechanisms like creating nested transactions are going to inherently fail, yet the business layer should not have to be concerning itself with such things. How do you handle such issues? Does ADO.Net provide simple mechanisms to handle this or do most people end up wrapping their own custom bits of code around ADO.Net to solve these types of problems?

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  • C++ - Basic WinAPI question

    - by HardCoder1986
    Hello! I am now working on a some sort of a game engine and I had an idea to put everything engine-related into a static library and then link it to my actual problem. Right now I achieved it and actually link that library and every functions seem to work fine, except those, which are windows-related. I have a chunk of code in my library that looks like this: hWnd = CreateWindow(className, "Name", WS_OVERLAPPED | WS_CAPTION | WS_EX_TOPMOST, 0, 0, 800, 600, NULL, NULL, GetModuleHandle(NULL), this); if (hWnd) { ShowWindow(hWnd, SW_NORMAL); UpdateWindow(hWnd); } else { MessageBox(NULL, "Internal program error", "Error", MB_OK | MB_ICONERROR); return; } When this code was not in the library, but in the actual project, it worked fine, created the window and everything was ok. Right now (when I'm linking to my library that contains this code) CreateWindow(...) call returns NULL and GetLastError() returns "Operation succesfully completed" (wtf?). Could anybody help me with this? Is it possible to create a window and display it using a static library call and why could my code fail? Thank you.

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  • C# threading solution for long queries

    - by Eddie
    Senerio We have an application that records incidents. An external database needs to be queried when an incident is approved by a supervisor. The queries to this external database are sometimes taking a while to run. This lag is experienced through the browser. Possible Solution I want to use threading to eliminate the simulated hang to the browser. I have used the Thread class before and heard about ThreadPool. But, I just found BackgroundWorker in this post. MSDN states: The BackgroundWorker class allows you to run an operation on a separate, dedicated thread. Time-consuming operations like downloads and database transactions can cause your user interface (UI) to seem as though it has stopped responding while they are running. When you want a responsive UI and you are faced with long delays associated with such operations, the BackgroundWorker class provides a convenient solution. Is BackgroundWorker the way to go when handling long running queries? What happens when 2 or more BackgroundWorker processes are ran simultaneously? Is it handled like a pool?

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