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• Problem with tcp server when converting to service

  - by djerry

  Hello lads, I'm working on monitoring some object (cdr-packets). I'm setting up a tcp-server and am listening on port 50043 for the packages. The program as a console application is working just fine, my server is working like it should and i'm receiving the packets. When i try to use it as a service, i cannot seem to get a client connected to my server. Is there something i need to change to deploy this as a service? Code below is from my application: this is my service class where i start protected override void OnStart(string[] args) { server = new TcpServer(); server.StartServer(); } this is the constructor of TcpServer public TcpServer() { try { _server = new TcpListener(IPAddress.Any, 50043); } catch (Exception) { _server = null; } } this is the method i call after initialising the class public void StartServer() { if (_server != null) { // Create a ArrayList for storing SocketListeners before starting the server. _socketListenersList = new ArrayList(); // Start the Server and start the thread to listen client requests. _server.Start(); _serverThread = new Thread(new ThreadStart(ServerThreadStart)); _serverThread.Start(); // Create a low priority thread that checks and deletes client // SocktConnection objcts that are marked for deletion. _purgingThread = new Thread(new ThreadStart(PurgingThreadStart)); _purgingThread.Priority = ThreadPriority.Lowest; _purgingThread.Start(); } } this is the thread that keep checking if any client tries to connect private void ServerThreadStart() { // Client Socket variable; Socket clientSocket = null; TcpSocketListener socketListener = null; while (!_stopServer) { try { // Wait for any client requests and if there is any request from any //client accept it (Wait indefinitely). clientSocket = _server.AcceptSocket(); // Create a SocketListener object for the client. socketListener = new TcpSocketListener(clientSocket); // Add the socket listener to an array list in a thread safe fashon. lock (_socketListenersList) { _socketListenersList.Add(socketListener); } // Start a communicating with the client in a different thread. socketListener.StartSocketListener(); } catch (SocketException se) { _stopServer = true; } } } when for the first time a packet waits to be read, and i get to "clientSocket = _server.AcceptSocket();", it throws an exception (service, not very good debugable) Does anyone recognize this problem or can help me? Thanks in advance

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• Performing full screen grab in windows

  - by Steven Lu

  I am working an idea that involves getting a full capture of the screen including windows and apps, analyzing it, and then drawing items back onto the screen, as an overlay. I want to learn image processing techniques and I could get lots of data to work with if I can directly access the Windows screen. I could use this to build automation tools the likes of which have never been seen before. More on that later. I have full screen capture working for the most part. HWND hwind = GetDesktopWindow(); HDC hdc = GetDC(hwind); int resx = GetSystemMetrics(SM_CXSCREEN); int resy = GetSystemMetrics(SM_CYSCREEN); int BitsPerPixel = GetDeviceCaps(hdc,BITSPIXEL); HDC hdc2 = CreateCompatibleDC(hdc); BITMAPINFO info; info.bmiHeader.biSize = sizeof(BITMAPINFOHEADER); info.bmiHeader.biWidth = resx; info.bmiHeader.biHeight = resy; info.bmiHeader.biPlanes = 1; info.bmiHeader.biBitCount = BitsPerPixel; info.bmiHeader.biCompression = BI_RGB; void *data; hbitmap = CreateDIBSection(hdc2,&info,DIB_RGB_COLORS,(void**)&data,0,0); SelectObject(hdc2,hbitmap); Once this is done, I can call this repeatedly: BitBlt(hdc2,0,0,resx,resy,hdc,0,0,SRCCOPY); The cleanup code (I have no idea if this is correct): DeleteObject(hbitmap); ReleaseDC(hwind,hdc); if (hdc2) { DeleteDC(hdc2); } Every time BitBlt is called it grabs the screen and saves it in memory I can access thru data. Performance is somewhat satisfactory. BitBlt executes in 50 milliseconds (sometimes as low as 33ms) at 1920x1200x32. What surprises me is that when I switch display mode to 16 bit, 1920x1200x16, either through my graphics settings beforehand, or by using ChangeDisplaySettings, I get a massively improved screen grab time between 1ms and 2ms, which cannot be explained by the factor of two reduction in bit-depth. Using CreateDIBSection (as above) offers a significant speed up when in 16-bit mode, compared to if I set up with CreateCompatibleBitmap (6-7ms/f). Does anybody know why dropping to 16bit causes such a speed increase? Is there any hope for me to grab 32bit at such speeds? if not for the color depth, but for not forcing a change of screen buffer modes and the awful flickering.

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• Mysterious constraints problem with SQL Server 2000

  - by Ramon

  Hi all I'm getting the following error from a VB NET web application written in VS 2003, on framework 1.1. The web app is running on Windows Server 2000, IIS 5, and is reading from a SQL server 2000 database running on the same machine. System.Data.ConstraintException: Failed to enable constraints. One or more rows contain values violating non-null, unique, or foreign-key constraints. at System.Data.DataSet.FailedEnableConstraints() at System.Data.DataSet.EnableConstraints() at System.Data.DataSet.set_EnforceConstraints(Boolean value) at System.Data.DataTable.EndLoadData() at System.Data.Common.DbDataAdapter.FillFromReader(Object data, String srcTable, IDataReader dataReader, Int32 startRecord, Int32 maxRecords, DataColumn parentChapterColumn, Object parentChapterValue) at System.Data.Common.DbDataAdapter.Fill(DataSet dataSet, String srcTable, IDataReader dataReader, Int32 startRecord, Int32 maxRecords) at System.Data.Common.DbDataAdapter.FillFromCommand(Object data, Int32 startRecord, Int32 maxRecords, String srcTable, IDbCommand command, CommandBehavior behavior) at System.Data.Common.DbDataAdapter.Fill(DataSet dataSet, Int32 startRecord, Int32 maxRecords, String srcTable, IDbCommand command, CommandBehavior behavior) at System.Data.Common.DbDataAdapter.Fill(DataSet dataSet) The problem appears when the web app is under a high load. The system runs fine when volume is low, but when the number of requests becomes high, the system starts rejecting incoming requests with the above exception message. Once the problem appears, very few requests actually make it through and get processed normally, about 2 in every 30. The vast majority of requests fail, until a SQL Server restart or IIS reset is performed. The system then start processing requests normally, and after some time it starts throwing the same error. The error occurs when a data adapter runs the Fill() method against a SELECT statement, to populate a strongly-typed dataset. It appears that the dataset does not like the data it is given and throws this exception. This error occurs on various SELECT statements, acting on different tables. I have regenerated the dataset and checked the relevant constraints, as well as the table from which the data is read. Both the dataset definition and the data in the table are fine. Admittedly, the hardware running both the web app and SQL Server 2000 is seriously outdated, considering the numbers of incoming requests it currently receives. The amount of RAM consumed by SQL Server is dynamically allocated, and at peak times SQL Server can consume up to 2.8 GB out of a total of 3.5 GB on the server. At first I suspected some sort of index or database corruption, but after running DBCC CHECKDB, no errors were found in the database. So now I'm wondering whether this error is a result of the hardware limitations of the system. Is it possible for SQL Server to somehow mess up the data it's supposed to pass to the dataset, resulting in constraint violation due to, say, data type/length mismatch? I tried accessing the RowError messages of the data rows in the retrieved dataset tables but I kept getting empty strings. I know that HasErrors = true for the datatables in question. I have not set the EnableConstraints = false, and I don't want to do that. Thanks in advance. Ray

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• Reading and writing C++ vector to a file

  - by JB

  For some graphics work I need to read in a large amount of data as quickly as possible and would ideally like to directly read and write the data structures to disk. Basically I have a load of 3d models in various file formats which take too long to load so I want to write them out in their "prepared" format as a cache that will load much faster on subsequent runs of the program. Is it safe to do it like this? My worries are around directly reading into the data of the vector? I've removed error checking, hard coded 4 as the size of the int and so on so that i can give a short working example, I know it's bad code, my question really is if it is safe in c++ to read a whole array of structures directly into a vector like this? I believe it to be so, but c++ has so many traps and undefined behavour when you start going low level and dealing directly with raw memory like this. I realise that number formats and sizes may change across platforms and compilers but this will only even be read and written by the same compiler program to cache data that may be needed on a later run of the same program. #include <fstream> #include <vector> using namespace std; struct Vertex { float x, y, z; }; typedef vector<Vertex> VertexList; int main() { // Create a list for testing VertexList list; Vertex v1 = {1.0f, 2.0f, 3.0f}; list.push_back(v1); Vertex v2 = {2.0f, 100.0f, 3.0f}; list.push_back(v2); Vertex v3 = {3.0f, 200.0f, 3.0f}; list.push_back(v3); Vertex v4 = {4.0f, 300.0f, 3.0f}; list.push_back(v4); // Write out a list to a disk file ofstream os ("data.dat", ios::binary); int size1 = list.size(); os.write((const char*)&size1, 4); os.write((const char*)&list[0], size1 * sizeof(Vertex)); os.close(); // Read it back in VertexList list2; ifstream is("data.dat", ios::binary); int size2; is.read((char*)&size2, 4); list2.resize(size2); // Is it safe to read a whole array of structures directly into the vector? is.read((char*)&list2[0], size2 * sizeof(Vertex)); }

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• What would you suggest as a high school first language?

  - by ldigas

  Edit by OA: After reading some answers I'll just update the question a little. At first I put it a little bluntly, but some of those gave me some good arguments which have to be taken into consideration while making a stand on this one. (these are mostly picked up from comments and answers below). A few things to take into account: to many pupils this is a first programming language - at this stage most of them have trouble grasping a difference between data types, variable passing, ... and whatnot, less alone pointers and similar 'low level stuff' :) they will all have to pass this to get into next grade (well, big majority of them anyway) not all of them have computers at home, not all of them are willing to learn this, less alone interested in - so the concepts have to be taught on a finite time scale in school hours (as well as practice on computers) free literature is a bonus - the teacher will make some scripts and handaways, but still ... I wouldn't like to bear the parents with the burden of buying expensive literature (also, english is not a native language here ... and although they are all learning it, their ability to read it fluently is somewhat questionable) somebody gave an argument - "a language which does not get in the way of ideas" - good one accessibility on different platforms in not expecially important at this point - although most of the suggested ones are available on win as well as linux - not many macs in this part of europe (their prices are sky high for anything but specialised usage) I will check what are the licencing issues on ms express editions about using it massively in high schools for purposes like this - if someone has any info about this, please, do not be shy with it :) A friend of mine, informatics teacher - in EU it comes as something as junior cs teacher, in a local high school asked me what I thought about what should be the first language pupils should be taught? It is a technical school (a little more oriented towards mathematics than the gymnasium, but not computer oriented totally). So I'm asking you - what do you think should be the first language pupils are exposed to in highschool? They have been teaching Pascal so far, but she's not sure that's a good course. She thought about switching to C (which I resented; considering not all pupils have interests in programming, to start with, and should be taught something higher level since they are just gripping the idea of a loop and such ... for a start), I suggested python or ruby (preferably py since it handles all paradigms). What is your opinion on this one? I looked, but didn't find a similar question on SO, so if there is one, please just point me towards it. Edit: The assumption is that none of the pupils have been exposed to any programming in junior school. See also: What is the best way to teach young kids some basic programming concepts? Best ways to teach a beginner to program How and when do you teach a kid to code What is the easiest language to start with? High School Programming

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• Dynamically find other hosts in a LAN in Java

  - by Federico Cristina

  A while ago I developed a little LAN chat app. in Java which allows chatting with other hosts, send images, etc. Although it was created just for fun, now it's being used where I work. Currently, there is no "chat server" on the app. where each client registers, updates it's status, etc. (I liked the idea of symmetric design and not depending on a server running on some other machine). Instead, each host is a client/server which has a hosts.properties file with the hostname of the other hosts, and - for instance - broadcasts to each one of them when sending a massive message/image/whatever. In the beginning there were just a couple of hosts, so this hosts.properties file wasn't an issue. But as the amount of users increased, the need of updating that file was a bit daunting. So now I've decided to get rid of it, and each time the app. starts, dynammically find the other active hosts. However, I cannot find the correct way of implement this. I've tried starting different threads, each one of them searching for other hosts in a known range of IP addresses. Something like this (simplified for the sake of readability): /** HostsLocator */ public static void searchForHosts(boolean waitToEnd) { for (int i=0; i < MAX_IP; i+= MAX_IP / threads) { HostsLocator detector = new HostsLocator(i, i+(MAX_IP / threads - 1)); // range: from - to new Thread(detector).start(); } } public void run() { for (int i=from; i<=to; i++) findHosts( maskAddress + Integer.toString(i) ); } public static boolean findHosts(String IP) { InetAddress address = InetAddress.getByName(IP); if ( address.isReachable(CONNECTION_TIME_OUT) ) // host found! } However: With a single thread and a low value in CONNECTION_TIME_OUT (500ms) I get wrong Host Not Found status for for hosts actually active. With a high value in CONNECTION_TIME_OUT (5000ms) and only one single thread takes forever to end With several threads I've also found problems similar like the first one, due to collisions. So... I guess there's a better way of solving this problem but I couldn't find it. Any advice? Thanks!

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• Instance caching in Objective C

  - by zoul

  Hello! I want to cache the instances of a certain class. The class keeps a dictionary of all its instances and when somebody requests a new instance, the class tries to satisfy the request from the cache first. There is a small problem with memory management though: The dictionary cache retains the inserted objects, so that they never get deallocated. I do want them to get deallocated, so that I had to overload the release method and when the retain count drops to one, I can remove the instance from cache and let it get deallocated. This works, but I am not comfortable mucking around the release method and find the solution overly complicated. I thought I could use some hashing class that does not retain the objects it stores. Is there such? The idea is that when the last user of a certain instance releases it, the instance would automatically disappear from the cache. NSHashTable seems to be what I am looking for, but the documentation talks about “supporting weak relationships in a garbage-collected environment.” Does it also work without garbage collection? Clarification: I cannot afford to keep the instances in memory unless somebody really needs them, that is why I want to purge the instance from the cache when the last “real” user releases it. Better solution: This was on the iPhone, I wanted to cache some textures and on the other hand I wanted to free them from memory as soon as the last real holder released them. The easier way to code this is through another class (let’s call it TextureManager). This class manages the texture instances and caches them, so that subsequent calls for texture with the same name are served from the cache. There is no need to purge the cache immediately as the last user releases the texture. We can simply keep the texture cached in memory and when the device gets short on memory, we receive the low memory warning and can purge the cache. This is a better solution, because the caching stuff does not pollute the Texture class, we do not have to mess with release and there is even a higher chance for cache hits. The TextureManager can be abstracted into a ResourceManager, so that it can cache other data, not only textures.

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• Implementing events to communicate between two processes - C

  - by Jamie Keeling

  Hello all! I have an application consisting of two windows, one communicates to the other and sends it a struct constaining two integers (In this case two rolls of a dice). I will be using events for the following circumstances: Process a sends data to process b, process b displays data Process a closes, in turn closing process b Process b closes a, in turn closing process a I have noticed that if the second process is constantly waiting for the first process to send data then the program will be just sat waiting, which is where the idea of implementing threads on each process occurred and I have started to implement this already. The problem i'm having is that I don't exactly have a lot of experience with threads and events so I'm not sure of the best way to actually implement what I want to do. Following is a small snippet of what I have so far in the producer application; Create thread: case IDM_FILE_ROLLDICE: { hDiceRoll = CreateThread( NULL, // lpThreadAttributes (default) 0, // dwStackSize (default) ThreadFunc(hMainWindow), // lpStartAddress NULL, // lpParameter 0, // dwCreationFlags &hDiceID // lpThreadId (returned by function) ); } break; The data being sent to the other process: DWORD WINAPI ThreadFunc(LPVOID passedHandle) { HANDLE hMainHandle = *((HANDLE*)passedHandle); WCHAR buffer[256]; LPCTSTR pBuf; LPVOID lpMsgBuf; LPVOID lpDisplayBuf; struct diceData storage; HANDLE hMapFile; DWORD dw; //Roll dice and store results in variable storage = RollDice(); hMapFile = CreateFileMapping( (HANDLE)0xFFFFFFFF, // use paging file NULL, // default security PAGE_READWRITE, // read/write access 0, // maximum object size (high-order DWORD) BUF_SIZE, // maximum object size (low-order DWORD) szName); // name of mapping object if (hMapFile == NULL) { dw = GetLastError(); MessageBox(hMainHandle,L"Could not create file mapping object",L"Error",MB_OK); return 1; } pBuf = (LPTSTR) MapViewOfFile(hMapFile, // handle to map object FILE_MAP_ALL_ACCESS, // read/write permission 0, 0, BUF_SIZE); if (pBuf == NULL) { MessageBox(hMainHandle,L"Could not map view of file",L"Error",MB_OK); CloseHandle(hMapFile); return 1; } CopyMemory((PVOID)pBuf, &storage, (_tcslen(szMsg) * sizeof(TCHAR))); //_getch(); MessageBox(hMainHandle,L"Completed!",L"Success",MB_OK); UnmapViewOfFile(pBuf); return 0; } I'm trying to find out how I would integrate an event with the threaded code to signify to the other process that something has happened, I've seen an MSDN article on using events but it's just confused me if anything, I'm coming up on empty whilst searching on the internet too. Thanks for any help Edit: I can only use the Create/Set/Open methods for events, sorry for not mentioning it earlier.

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• Algorithm to split an article without breaking the reading flow or HTML code

  - by Victor Stanciu

  Hello, I have a very large database of articles, of varying lengths. The articles have HTML elements in them. I have to insert some ads (simple <script> elements) in the body of each article when it is displayed (I know, I hate ads that interrupt my reading too). Now, the problem is that each ad must be inserted at about the same position in each article. The simplest solution is to simply split the article on a fixed number of characters (without breaking words), and insert the ad code. This, however, runs the risk of inserting the ad in the middle of a HTML tag. I could go the regex way, but I was thinking about the following solution, using JS: Establish a character count threshold. For example, "the add should be inserted at about 200 words" Set accepted deviations in each direction, say -20, +20 characters. Loop through each text node inside the article, and while doing so, keep count of the total number of characters so far Once the count exceeds the threshold, make the following decision: 4.1. If count exceeds the threshold by a value lower that the positive accepted deviation (for example, 17 characters), insert the ad code just after the current text node. 4.2. If the count is greater than the sum of the threshold and the deviation, roll back to the previous text node, and make the same decision, only this time use the previous count and check if it's lower than the difference between the threshold and the deviation, and if not, insert the ad between the current node and the previous one. 4.3. If the 4.1 and 4.2 fail (which means that the previous node reached a too low character count and the current node a too high one), insert the ad after whatever character count is needed inside the current element. I know it's convoluted, but it's the first thing out of my mind and it has the advantage that, by trying to insert the ad between text nodes, perhaps it will not break the flow of the article as bad as it would if I would just stick it in (like the final 4.3 case) Here is some pseudo-code I put together, I don't trust my english-explaining skills: threshold = 200 deviation = 20 current_count = 0 for each node in article_nodes { previous_count = current_count current_count = current_count + node.length if current_count < threshold { continue // next interation } if current_count > threshold + deviation { if previous_count < threshdold - deviation { // insert ad in current node } else { // insert ad between the current and previous nodes } } else { // insert ad after the current node } break; } Am I over-complicating stuff, or am I missing a simpler, more elegant solution?

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• How do you remind your Scrum Product Owner about his promises/actions?

  - by Felix Ogg

  ** EDIT: Rephrased the question to re-focus ** Our Scrum team meets as seldomly as possible, but we meet with the product owner every chance we get. We track everyone's agreed action points (particularly theirs). We are 100% agile, but our product owner lives in traditional world, we remain off-site. We facilitate him in crossing over to our fast-paced world. There's not much wrong. The team and the PO are in good spirits. PO is present at every meeting and positively energized. Just imagine this person as a 70 year old, slow grandpa, who is forgetful, yet kind. In reality he isn't, but he is used to a working environment (public servants) that is much slooooower. Manyana-manyana etc. It is frustrating for my team to cooperate: PO lives in a non-prioritized environment, and everyone in it has learned the productivity-technique of NGTD (Not Getting Things Done). He WANTS to, it's just that he forgets or 'sinks' somewhere along the away. We have experimented with a text file, maintained by the Scrum master (low-tech), which he broadcasts by e-mail every day JIRA, our issue tracker. Turns out this is nice for programmers, but too steep for 'regular people' I Googled for Issue tracking webtools but came up empty handed: All tools are aimed at IT issue tracking, instead of meeting action point tracking/planning for mere mortals. I did find TODO-lists like RememberTheMilk, but they don't track comments, and - to be honest - I doubt we could get our product owner to use it (too complicated). We have three requirements: Register action points, assign to a team member and a deadline Offer anyone to 'comment' on progress of any action point Do not build our own tool from scratch We do not need: - impressive authorization models, - multi-project, - workflow, - crosslinking. Is there any trick/tool you use to assist your product owner 'fly' like the rest of the rest of the team? Communication before tools I agree with the general consensus that one should not try to apply technology to a communication problem, however in this case I am merely looking for a tool to save me time in setting up prioritized lists. I found www.thymer.com today, may be what I am looking for. The guys are cool. It is getting rather feature-bloated though.

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• deallocated memory in tableview: message sent to deallocated instance

  - by Kirn

  I tried looking up other issues but couldn't find anything to match so here goes: I'm trying to display text in the table view so I use this bit of code: // StockData is an object I created and it pulls information from Yahoo APIs based on // a stock ticker stored in NSString *heading NSArray* tickerValues = [heading componentsSeparatedByString:@" "]; StockData *chosenStock = [[StockData alloc] initWithContents:[tickerValues objectAtIndex:0]]; [chosenStock getData]; // Set up the cell... NSDictionary *tempDict = [chosenStock values]; NSArray *tempArr = [tempDict allValues]; cell.textLabel.text = [tempArr objectAtIndex:indexPath.row]; return cell; This is all under cellForRowAtIndexPath When I try to release the chosenStock object though I get this error: [CFDictionary release]: message sent to deallocated instance 0x434d3d0 Ive tried using NSZombieEnabled and Build and Analyze to detect problems but no luck thus far. Ive even gone so far as to comment bits and pieces of the code with NSLog but no luck. I'll post the code for StockData below this. As far as I can figure something is getting deallocated before I do the release but I'm not sure how. The only place I've got release in my code is under dealloc method call. Here's the StockData code: // StockData contains all stock information pulled in through Yahoo! to be displayed @implementation StockData @synthesize ticker, values; - (id) initWithContents: (NSString *)newName { if(self = [super init]){ ticker = newName; } return self; } - (void) getData { NSURL *url = [NSURL URLWithString: [NSString stringWithFormat:@"http://download.finance.yahoo.com/d/quotes.csv?s=%@&f=%@&e=.csv", ticker, @"chgvj1"]]; NSError *error; NSURLResponse *response; NSURLRequest *request = [NSURLRequest requestWithURL:url]; NSData *stockData = [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:&error]; if(stockData) { NSString *tempStr = [[NSString alloc] initWithData:stockData encoding:NSASCIIStringEncoding]; NSArray *receivedValuesArr = [tempStr componentsSeparatedByString:@","]; [tempStr release]; values = [NSDictionary dictionaryWithObjects:receivedValuesArr forKeys:[@"change, high, low, volume, market" componentsSeparatedByString:@", "]]; } else { NSLog(@"Connection failed: %@", error); } } - (void)dealloc { [ticker release]; [values release]; [super dealloc]; NSLog(@"Release took place fine"); } @end

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• Where are the function literals in c++?

  - by academicRobot

  First of all, maybe literals is not the right term for this concept, but its the closest I could think of (not literals in the sense of functions as first class citizens). The idea is that when you make a conventional function call, it compiles to something like this: callq <immediate address> But if you make a function call using a function pointer, it compiles to something like this: mov <memory location>,%rax callq *%rax Which is all well and good. However, what if I'm writing a template library that requires a callback of some sort with a specified argument list and the user of the library is expected to know what function they want to call at compile time? Then I would like to write my template to accept a function literal as a template parameter. So, similar to template <int int_literal> struct my_template {...};` I'd like to write template <func_literal_t func_literal> struct my_template {...}; and have calls to func_literal within my_template compile to callq <immediate address>. Is there a facility in C++ for this, or a work around to achieve the same effect? If not, why not (e.g. some cataclysmic side effects)? How about C++0x or another language? Solutions that are not portable are fine. Solutions that include the use of member function pointers would be ideal. I'm not particularly interested in being told "You are a <socially unacceptable term for a person of low IQ>, just use function pointers/functors." This is a curiosity based question, and it seems that it might be useful in some (albeit limited) applications. It seems like this should be possible since function names are just placeholders for a (relative) memory address, so why not allow more liberal use (e.g. aliasing) of this placeholder. p.s. I use function pointers and functions objects all the the time and they are great. But this post got me thinking about the don't pay for what you don't use principle in relation to function calls, and it seems like forcing the use of function pointers or similar facility when the function is known at compile time is a violation of this principle, though a small one.

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• Using events in threads between processes - C

  - by Jamie Keeling

  Hello all! I have an application consisting of two windows, one communicates to the other and sends it a struct constaining two integers (In this case two rolls of a dice). I will be using events for the following circumstances: Process a sends data to process b, process b displays data Process a closes, in turn closing process b Process b closes a, in turn closing process a I have noticed that if the second process is constantly waiting for the first process to send data then the program will be just sat waiting, which is where the idea of implementing threads on each process occurred and I have started to implement this already. The problem i'm having is that I don't exactly have a lot of experience with threads and events so I'm not sure of the best way to actually implement what I want to do. Following is a small snippet of what I have so far in the producer application; Create thread: case IDM_FILE_ROLLDICE: { hDiceRoll = CreateThread( NULL, // lpThreadAttributes (default) 0, // dwStackSize (default) ThreadFunc(hMainWindow), // lpStartAddress NULL, // lpParameter 0, // dwCreationFlags &hDiceID // lpThreadId (returned by function) ); } break; The data being sent to the other process: DWORD WINAPI ThreadFunc(LPVOID passedHandle) { HANDLE hMainHandle = *((HANDLE*)passedHandle); WCHAR buffer[256]; LPCTSTR pBuf; LPVOID lpMsgBuf; LPVOID lpDisplayBuf; struct diceData storage; HANDLE hMapFile; DWORD dw; //Roll dice and store results in variable storage = RollDice(); hMapFile = CreateFileMapping( (HANDLE)0xFFFFFFFF, // use paging file NULL, // default security PAGE_READWRITE, // read/write access 0, // maximum object size (high-order DWORD) BUF_SIZE, // maximum object size (low-order DWORD) szName); // name of mapping object if (hMapFile == NULL) { dw = GetLastError(); MessageBox(hMainHandle,L"Could not create file mapping object",L"Error",MB_OK); return 1; } pBuf = (LPTSTR) MapViewOfFile(hMapFile, // handle to map object FILE_MAP_ALL_ACCESS, // read/write permission 0, 0, BUF_SIZE); if (pBuf == NULL) { MessageBox(hMainHandle,L"Could not map view of file",L"Error",MB_OK); CloseHandle(hMapFile); return 1; } CopyMemory((PVOID)pBuf, &storage, (_tcslen(szMsg) * sizeof(TCHAR))); //_getch(); MessageBox(hMainHandle,L"Completed!",L"Success",MB_OK); UnmapViewOfFile(pBuf); return 0; } I'm trying to find out how I would integrate an event with the threaded code to signify to the other process that something has happened, I've seen an MSDN article on using events but it's just confused me if anything, I'm coming up on empty whilst searching on the internet too. Thanks for any help Edit: I can only use the Create/Set/Open methods for events, sorry for not mentioning it earlier.

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• Memory issues - Living vs. overall -> app is killed

  - by D33

  I'm trying to check my applications memory issues in Instruments. When I load the application I play some sounds and show some animations in UIImageViews. To save some memory I load the sounds only when I need it and when I stop playing it I free it from the memory. problem 1: My application is using about 5.5MB of Living memory. BUT The Overall section is growing after start to 20MB and then it's slowly growing (about 100kB/sec). But responsible Library is OpenAL (OAL::Buffer), dyld (_dyld_start)-I am not sure what this really is, and some other stuff like ft_mem_qrealloc, CGFontStrikeSetValue, … problem 2: When the overall section breaks about 30MB, application crashes (is killed). According to the facts I already read about overall memory, it means then my all allocations and deallocation is about 30MB. But I don't really see the problem. When I need some sound for example I load it to the memory and when I don't need it anymore I release it. But that means when I load 1MB sound, this operation increase overall memory usage with 2MB. Am I right? And when I load 10 sounds my app crashes just because the fact my overall is too high even living is still low??? I am very confused about it. Could someone please help me clear it up? (I am on iOS 5 and using ARC) SOME CODE: creating the sound OpenAL: MYOpenALSound *sound = [[MyOpenALSound alloc] initWithSoundFile:filename willRepeat:NO]; if(!sound) return; [soundDictionary addObject:sound]; playing: [sound play]; dispatch_after(dispatch_time(DISPATCH_TIME_NOW, ((sound.duration * sound.pitch) + 0.1) * NSEC_PER_SEC), dispatch_get_current_queue(), ^{ [soundDictionary removeObjectForKey:[NSNumber numberWithInt:soundID]]; }); } creating the sound with AVAudioPlayer: [musics replaceObjectAtIndex:ID_MUSIC_MAP withObject:[[Music alloc] initWithFilename:@"mapMusic.mp3" andWillRepeat:YES]]; pom = [musics objectAtIndex:musicID]; [pom playMusic]; and stop and free it: [musics replaceObjectAtIndex:ID_MUSIC_MAP withObject:[NSNull null]]; AND IMAGE ANIMATIONS: I load images from big PNG file (this is realated also to my other topic : Memory warning - UIImageView and its animations) I have few UIImageViews and by time I'm setting animation arrays to play Animations... UIImage *source = [[UIImage alloc] initWithCGImage:[[UIImage imageNamed:@"imageSource.png"] CGImage]]; cutRect = CGRectMake(0*dimForImg.width,1*dimForImg.height,dimForImg.width,dimForImg.height); image1 = [[UIImage alloc] initWithCGImage:CGImageCreateWithImageInRect([source CGImage], cutRect)]; cutRect = CGRectMake(1*dimForImg.width,1*dimForImg.height,dimForImg.width,dimForImg.height); ... image12 = [[UIImage alloc] initWithCGImage:CGImageCreateWithImageInRect([source CGImage], cutRect)]; NSArray *images = [[NSArray alloc] initWithObjects:image1, image2, image3, image4, image5, image6, image7, image8, image9, image10, image11, image12, image12, image12, nil]; and this array I just use simply like : myUIImageView.animationImages = images, ... duration -> startAnimating

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• Throwing cats out of windows

  - by AndrewF

  Imagine you're in a tall building with a cat. The cat can survive a fall out of a low story window, but will die if thrown from a high floor. How can you figure out the longest drop that the cat can survive, using the least number of attempts? Obviously, if you only have one cat, then you can only search linearly. First throw the cat from the first floor. If it survives, throw it from the second. Eventually, after being thrown from floor f, the cat will die. You then know that floor f-1 was the maximal safe floor. But what if you have more than one cat? You can now try some sort of logarithmic search. Let's say that the build has 100 floors and you have two identical cats. If you throw the first cat out of the 50th floor and it dies, then you only have to search 50 floors linearly. You can do even better if you choose a lower floor for your first attempt. Let's say that you choose to tackle the problem 20 floors at a time and that the first fatal floor is #50. In that case, your first cat will survive flights from floors 20 and 40 before dying from floor 60. You just have to check floors 41 through 49 individually. That's a total of 12 attempts, which is much better than the 50 you would need had you attempted to use binary elimination. In general, what's the best strategy and it's worst-case complexity for an n-storied building with 2 cats? What about for n floors and m cats? Assume that all cats are equivalent: they will all survive or die from a fall from a given window. Also, every attempt is independent: if a cat survives a fall, it is completely unharmed. This isn't homework, although I may have solved it for school assignment once. It's just a whimsical problem that popped into my head today and I don't remember the solution. Bonus points if anyone knows the name of this problem or of the solution algorithm.

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• System.Threading.Timer Doesn't Trigger my TimerCallBack Delegate

  - by Tom Kong

  Hi, I am writing my first Windows Service using C# and I am having some trouble with my Timer class. When the service is started, it runs as expected but the code will not execute again (I want it to run every minute) Please take a quick look at the attached source and let me know if you see any obvious mistakes! TIA using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Diagnostics; using System.Linq; using System.ServiceProcess; using System.Text; using System.Threading; using System.IO; namespace CXO001 { public partial class Service1 : ServiceBase { public Service1() { InitializeComponent(); } /* * Aim: To calculate and update the Occupancy values for the different Sites * * Method: Retrieve data every minute, updating a public value which can be polled */ protected override void OnStart(string[] args) { Daemon(); } public void Daemon() { TimerCallback tcb = new TimerCallback(On_Tick); TimeSpan duetime = new TimeSpan(0, 0, 1); TimeSpan interval = new TimeSpan(0, 1, 0); Timer querytimer = new Timer(tcb, null, duetime, interval); } protected override void OnStop() { } static int[] floorplanids = new int[] { 115, 114, 107, 108 }; public static List<Record> Records = new List<Record>(); static bool firstrun = true; public static void On_Tick(object timercallback) { //Update occupancy data for the last minute //Save a copy of the public values to HDD with a timestamp string starttime; if (Records.Count > 0) { starttime = Records.Last().TS; firstrun = false; } else { starttime = DateTime.Today.AddHours(7).ToString(); firstrun = true; } DateTime endtime = DateTime.Now; GetData(starttime, endtime); } public static void GetData(string starttime, DateTime endtime) { string connstr = "Data Source = 192.168.1.123; Initial Catalog = Brickstream_OPS; User Id = Brickstream; Password = bstas;"; DataSet resultds = new DataSet(); //Get the occupancy for each Zone foreach (int zone in floorplanids) { SQL s = new SQL(); string querystr = "SELECT SUM(DIRECTIONAL_METRIC.NUM_TO_ENTER - DIRECTIONAL_METRIC.NUM_TO_EXIT) AS 'Occupancy' FROM REPORT_OBJECT INNER JOIN REPORT_OBJ_METRIC ON REPORT_OBJECT.REPORT_OBJ_ID = REPORT_OBJ_METRIC.REPORT_OBJECT_ID INNER JOIN DIRECTIONAL_METRIC ON REPORT_OBJ_METRIC.REP_OBJ_METRIC_ID = DIRECTIONAL_METRIC.REP_OBJ_METRIC_ID WHERE (REPORT_OBJ_METRIC.M_START_TIME BETWEEN '" + starttime + "' AND '" + endtime.ToString() + "') AND (REPORT_OBJECT.FLOORPLAN_ID = '" + zone + "');"; resultds = s.Go(querystr, connstr, zone.ToString(), resultds); } List<Record> result = new List<Record>(); int c = 0; foreach (DataTable dt in resultds.Tables) { Record r = new Record(); r.TS = DateTime.Now.ToString(); r.Zone = dt.TableName; if (!firstrun) { r.Occupancy = (dt.Rows[0].Field<int>("Occupancy")) + (Records[c].Occupancy); } else { r.Occupancy = dt.Rows[0].Field<int>("Occupancy"); } result.Add(r); c++; } Records = result; MrWriter(); } public static void MrWriter() { StringBuilder output = new StringBuilder("Time,Zone,Occupancy\n"); foreach (Record r in Records) { output.Append(r.TS); output.Append(","); output.Append(r.Zone); output.Append(","); output.Append(r.Occupancy.ToString()); output.Append("\n"); } output.Append(firstrun.ToString()); output.Append(DateTime.Now.ToFileTime()); string filePath = @"C:\temp\CXO.csv"; File.WriteAllText(filePath, output.ToString()); } } }

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• Ideas on implementing threads and cross process communication. - C

  - by Jamie Keeling

  Hello all! I have an application consisting of two windows, one communicates to the other and sends it a struct constaining two integers (In this case two rolls of a dice). I will be using events for the following circumstances: Process a sends data to process b, process b displays data Process a closes, in turn closing process b Process b closes a, in turn closing process a I have noticed that if the second process is constantly waiting for the first process to send data then the program will be just sat waiting, which is where the idea of implementing threads on each process occured. I have already implemented a thread on the first process which currently creates the data to send to the second process and makes it available to the second process. The problem i'm having is that I don't exactly have a lot of experience with threads and events so I'm not sure of the best way to actually implement what I want to do. Following is a small snippet of what I have so far in the producer application; Rolling the dice and sending the data: case IDM_FILE_ROLLDICE: { hDiceRoll = CreateThread( NULL, // lpThreadAttributes (default) 0, // dwStackSize (default) ThreadFunc(hMainWindow), // lpStartAddress NULL, // lpParameter 0, // dwCreationFlags &hDiceID // lpThreadId (returned by function) ); } break; The data being sent to the other process: DWORD WINAPI ThreadFunc(LPVOID passedHandle) { HANDLE hMainHandle = *((HANDLE*)passedHandle); WCHAR buffer[256]; LPCTSTR pBuf; LPVOID lpMsgBuf; LPVOID lpDisplayBuf; struct diceData storage; HANDLE hMapFile; DWORD dw; //Roll dice and store results in variable storage = RollDice(); hMapFile = CreateFileMapping( (HANDLE)0xFFFFFFFF, // use paging file NULL, // default security PAGE_READWRITE, // read/write access 0, // maximum object size (high-order DWORD) BUF_SIZE, // maximum object size (low-order DWORD) szName); // name of mapping object if (hMapFile == NULL) { dw = GetLastError(); MessageBox(hMainHandle,L"Could not create file mapping object",L"Error",MB_OK); return 1; } pBuf = (LPTSTR) MapViewOfFile(hMapFile, // handle to map object FILE_MAP_ALL_ACCESS, // read/write permission 0, 0, BUF_SIZE); if (pBuf == NULL) { MessageBox(hMainHandle,L"Could not map view of file",L"Error",MB_OK); CloseHandle(hMapFile); return 1; } CopyMemory((PVOID)pBuf, &storage, (_tcslen(szMsg) * sizeof(TCHAR))); //_getch(); MessageBox(hMainHandle,L"Completed!",L"Success",MB_OK); UnmapViewOfFile(pBuf); return 0; } I'd like to think I am at least on the right lines, although for some reason when the application finishes creating the thread it hits the return DefWindowProc(hMainWindow, message, wParam, lParam); it crashes saying there's no more source code for the current location. I know there are certain ways to implement things but as I've mentioned I'm not sure if i'm doing this the right way, has anybody else tried to do the same thing? Thanks!

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• Javascript and VERY LONG string

  - by StealthRT

  Hey all, i am having problems with the below code: function showTableData() { var tableArray; var x = 0; var theHTML; for (i = 0; i < 7032; i++) { if (x = 0) { theHTML = '<tr>' + '<th scope="row" class="spec">' + partNum[i] + '</th>' + '<td>' + Msrp[i] + '</td>' + '<td>' + blah[i] + '</td>' + '<td>' + blahs[i] + '</td>' + '</tr>' + theHTML; x++; }else{ theHTML = '<tr>' + '<th scope="row" class="specalt">' + partNum[i] + '</th>' + '<td class="alt">' + Msrp[i] + '</td>' + '<td class="alt">' + blah[i] + '</td>' + '<td class="alt">' + blahs[i] + '</td>' + '</tr>' + theHTML; x--; } } theHTML = '<table id="mytable" cellspacing="0">' + '<tr>' + '<th scope="col" abbr="Configurations" class="nobg">Part Number</th>' + '<th scope="col" abbr="Dual 1.8">Msrp Price</th>' + '<th scope="col" abbr="Dual 2">blahs Price</th>' + '<th scope="col" abbr="Dual 2.5">Low Price</th>' + '</tr>' + theHTML + '</table>'; $('#example').append(theHTML); } </script> <div id="example"> </div> The problem being that the $('#example').append(theHTML); never executes (or shows on the page). I think its because the string is soooooo long! It has over 7,000 items in the array so im not sure if thats the reason or if its something else? Any help would be great! Thanks! David

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• What IPC method should I use between Firefox extension and C# code running on the same machine?

  - by Rory

  I have a question about how to structure communication between a (new) Firefox extension and existing C# code. The firefox extension will use configuration data and will produce other data, so needs to get the config data from somewhere and save it's output somewhere. The data is produced/consumed by existing C# code, so I need to decide how the extension should interact with the C# code. Some pertinent factors: It's only running on windows, in a relatively controlled corporate environment. I have a windows service running on the machine, built in C#. Storing the data in a local datastore (like sqlite) would be useful for other reasons. The volume of data is low, e.g. 10kb of uncompressed xml every few minutes, and isn't very 'chatty'. The data exchange can be asynchronous for the most part if not completely. As with all projects, I have limited resources so want an option that's relatively easy. It doesn't have to be ultra-high performance, but shouldn't add significant overhead. I'm planning on building the extension in javascript (although could be convinced otherwise if really necessary) Some options I'm considering: use an XPCOM to .NET/COM bridge use a sqlite db: the extension would read from and save to it. The c# code would run in the service, populating the db and then processing data created by the service. use TCP sockets to communicate between the extension and the service. Let the service manage a local data store. My problem with (1) is I think this will be tricky and not so easy. But I could be completely wrong? The main problem I see with (2) is the locking of sqlite: only a single process can write data at a time so there'd be some blocking. However, it would be nice generally to have a local datastore so this is an attractive option if the performance impact isn't too great. I don't know whether (3) would be particularly easy or hard ... or what approach to take on the protocol: something custom or http. Any comments on these ideas or other suggestions? UPDATE: I was planning on building the extension in javascript rather than c++

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• What web platform is right for me?

  - by egervari

  I've been looking at web frameworks like Rails, Grails, etc. I'm used to doing applications in Spring Framework with Hibernate... and I want something more productive. One of the things I realized is that while some of the things in Grails is sexy, there are some serious problems with it. Grails' controllers: 1) are implemented awfully. They don't seem to be able to extend from super classes at runtime. I tried this to add base actions and helper methods, and this seems to cause grails to blow up. 2) are based on an obsolete request parameters model (rather than form backing objects, which are much nicer). 3) are hard to test. Command objects are treated totally differently... and it's actually MUCH harder to write the test than it is to write the controller code. 4) Command objects operate totally differently. They are pre-validated and bound, which causes a lot of inconsistencies than basic parameter model. 5) Command objects are not reusable, and it's a pain in the rear to reuse most of the stuff from the domain classes, like constraints and fields. This is TRIVIAL to do in basic Spring. Why the hell was it not trivial to do in Grails? 6) The scaffolding that is generated is pure crap. It doesn't generalize inserts and updates... and it actually copy/pastes a pile of code in two views: create.gsp and edit.gsp. The views themselves are gargantuan piles of doggie do-do. This is further compounded by the fact that it uses low-level parameters and not objects. Integration tests are 30x slower than a Spring integration test. It is disgusting. Some mocking tests are so hard to write and aren't guaranteed to work when it's deployed, that I think it discourages fast, tdd test cycles. Most things seem to screw up grails while it's running, like adding a taglib, or anything really. The server restart problem wasn't solved at all. I'm starting to think going with Spring/Hibernate/Java is the only way to go. While there is a pretty big cost at startup, I know it'll eventually smooth out. It sucks I can't use a language like Scala... because idiomatically, it is so incompatible with Hibernate. This app is also not a run-of-the-mill UI over a database. It's got some of that, but it's not going to be a slouch. I am deathly scared of Grails now because of how crap it is in the Controller layer. Suggestions on what I can do?

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• Where are the function literals c++?

  - by academicRobot

  First of all, maybe literals is not the right term for this concept, but its the closest I could think of (not literals in the sense of functions as first class citizens). The idea is that when you make a conventional function call, it compiles to something like this: callq <immediate address> But if you make a function call using a function pointer, it compiles to something like this: mov <memory location>,%rax callq *%rax Which is all well and good. However, what if I'm writing a template library that requires a callback of some sort with a specified argument list and the user of the library is expected to know what function they want to call at compile time? Then I would like to write my template to accept a function literal as a template parameter. So, similar to template <int int_literal> struct my_template {...};` I'd like to write template <func_literal_t func_literal> struct my_template {...}; and have calls to func_literal within my_template compile to callq <immediate address>. Is there a facility in C++ for this, or a work around to achieve the same effect? If not, why not (e.g. some cataclysmic side effects)? How about C++0x or another language? Solutions that are not portable are fine. Solutions that include the use of member function pointers would be ideal. I'm not particularly interested in being told "You are a <socially unacceptable term for a person of low IQ>, just use function pointers/functors." This is a curiosity based question, and it seems that it might be useful in some (albeit limited) applications. It seems like this should be possible since function names are just placeholders for a (relative) memory address, so why not allow more liberal use (e.g. aliasing) of this placeholder. p.s. I use function pointers and functions objects all the the time and they are great. But this post got me thinking about the don't pay for what you don't use principle in relation to function calls, and it seems like forcing the use of function pointers or similar facility when the function is known at compile time is a violation of this principle, though a small one.

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• priority_queue with dynamic priorities

  - by Layne

  Hey, I have a server application which accepts incomming queries and executes them. If there are too many queries they should be queued and if some of the other queries got executed the queued queries should be executed as well. Since I want to pass queries with different priorities I think using a priority_queue would be the best choice. e.g. The amout of the axcepting queries (a) hit the limt and new queries will be stored in the queue. All queries have a priority of 1 (lowest) if some of the queries from (a) get executed the programm will pick the query with the highest priority out of the queue and execute it. Still no problem. Now someone is sending a query with a priority of 5 which gets added to the queue. Since this is the query with the highest priority the application will execute this query as soon as the running queries no longer hit the limit. There might be the worst case that 500 queries with a priority of 1 are queued but wont be executed since someone is always sending queries with a priority of 5 hence these 500 queries will be queued for a looooong time. In order to prevent that I want to increase the prioritiy of all queries which have a lower priority than the query with the higher priority, in this example which have a priority lower than 5. So if the query with a priority of 5 gets pulled out of the queue all other queries with a priority < 5 should be increased by 0.2. This way queries with a low priority wont be queued for ever even if there might be 100 queries with a higher priority. I really hope can help me to solve the problem with the priorities: Since my queries consist of an object I thought something like this might work: class Query { public: Query( std::string p_stQuery ) : stQuery( p_stQuery ) {}; std::string getQuery() const {return stQuery;}; void increasePriority( const float fIncrease ) {fPriority += fIncrease;}; friend bool operator < ( const Query& PriorityFirst, const Query& PriorityNext ) { if( PriorityFirst.fPriority < PriorityNext.fPriority ) { if( PriorityFirst.fStartPriority < PriorityNext.fStartPriority ) { Query qTemp = PriorityFirst; qTemp.increasePriority( INCREASE_RATE ); } return true; } else { return false; } }; private: static const float INCREASE_RATE = 0.2; float fPriority; // current priority float fStartPriority; // initialised priority std::string stQuery; };

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• HTML format using Java mail in android

  - by TheDevMan

  I am trying to implement an HTML format mail using the Java mail in android. I would like to get results like this: When I look at the html format sent from lookout in my GMAIL. I don't see any link, but just has this format: [image: Lookout_logo] [image: Signal_flare_icon] Your battery level is really low, so we located your device with Signal Flare. I was trying the following: Properties props = System.getProperties(); props.put("mail.smtp.starttls.enable", "true"); // added this line props.put("mail.smtp.host", host); props.put("mail.smtp.user", from); props.put("mail.smtp.password", pass); props.put("mail.smtp.port", "587"); props.put("mail.smtp.auth", "true"); javax.mail.Session session = javax.mail.Session.getDefaultInstance(props, null); MimeMessage message = new MimeMessage(session); message.setFrom(new InternetAddress(from)); InternetAddress[] toAddress = new InternetAddress[to.length]; // To get the array of addresses for( int i=0; i < to.length; i++ ) { // changed from a while loop toAddress[i] = new InternetAddress(to[i]); } message.setRecipients(Message.RecipientType.BCC, toAddress); message.setSubject(sub); //message.setText(body); body = "<!DOCTYPE html><html><body><img src=\"http://en.wikipedia.org/wiki/Krka_National_Park#mediaviewer/File:Krk_waterfalls.jpg\">"; message.setContent(body, "text/html; charset=utf-8"); Transport transport = session.getTransport("smtp"); transport.connect(host, from, pass); transport.sendMessage(message, message.getAllRecipients()); transport.close(); When I look at the html format sent with the above code. I get the following: <!DOCTYPE html><html><body><img src="http://en.wikipedia.org/wiki/Krka_National_Park#mediaviewer/File:Krk_waterfalls.jpg> How to make sure the user will not be able to see any html code or URL link like the mail sent by LOOKOUT? Thanks!

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• Using jQuery and SPServices to Display List Items

  - by Bil Simser

  I had an interesting challenge recently that I turned to Marc Anderson’s wonderful SPServices project for. If you haven’t already seen or used SPServices, please do. It’s a jQuery library that does primarily two things. First, it wraps up all of the SharePoint web services in a nice little AJAX wrapper for use in JavaScript. Second, it enhances the form editing of items in SharePoint so you’re not hacking up your List Form pages. My challenge was simple but interesting. The user wanted to display a SharePoint item page (DispForm.aspx, which already had some customization on it to display related items via this blog post from Codeless Solutions for SharePoint) but launch from an external application using the value of one of the fields in the SharePoint list. For simplicity let’s say my list is a list of customers and the related list is a list of orders for that customer. It would look something like this (click on the item to see the full image): Your first thought might be, that’s easy! Display the customer information using a DataView Web Part and filter the item using a query string to match the customer number. However there are a few problems with this idea: You’ll need to build a custom page and then attach that related orders view to it. This is a bit of a problem because the solution from Codeless Solutions relies on the Title field on the page to be displayed. On a custom page you would have to recreate all of the elements found on the DispForm.aspx page so the related view would work. The DataView Web Part doesn’t look *exactly* like what the out of the box display form page does. Not a huge problem and can be overcome with some CSS style overrides but still, more work. A DVWP showing a single record doesn’t have the same toolbar that you would using the DispForm.aspx. Not a show-stopper and you can rebuild the toolbar but it’s going to potentially require code and then there’s the security trimming, etc. that you have to get right. DVWPs are not automatically updated if you add a column to the list like DispForm.aspx is. Work, work, work. For these reasons I thought it would be easier to take the already existing (modified) DispForm.aspx page and just add some jQuery magic to the page to find the item. Why do we need to find it? DispForm.aspx relies on a querystring parameter called “ID” which then displays whatever that item ID number is in the list. Trouble is, when you’re coming in from an external app via a link, you don’t know what that internal ID is (and frankly shouldn’t). I don’t like exposing internal SharePoint IDs to the outside world for the same reason I don’t do it with database IDs. They’re internal and while it’s find to use on the site itself you don’t want external links using it. It’s volatile and can change (delete one item then re-add it back with the same data and watch any ID references break). The next thought might be to call a SharePoint web service with a CAML query to get the item ID number using some criteria (in this case, the customer number). That’s great if you have that ability but again we had an existing application we were just adding a link to. The last thing I wanted to do was to crack open the code on that sucker and start calling web services (primarily because it’s Java, but really I’m a lazy geek). However if you’re doing this and have access to call a web service that would be an option. Back to this problem, how do I a) find a SharePoint List Item based on some field value other than ID and b) make it low impact so I can just construct a URL to it? That’s where jQuery and SPServices came to the rescue. After spending a few hours of emails back and forth with Marc and a couple of phone calls (and updating jQuery to the latest version, duh!) it was a simple answer. First we need a reference to a) jQuery b) SPServices and c) our script. I just dropped a Content Editor Web Part, the Swiss Army Knives of Web Parts, onto the DispForm.aspx page and added these lines: <script type="text/javascript" src="http://intranet/JavaScript/jquery-1.4.2.min.js"></script> <script type="text/javascript" src="http://intranet/JavaScript/jquery.SPServices-0.5.3.min.js"></script> <script type="text/javascript" src="http://intranet/JavaScript/RedirectToID.js"> </script> Update it to point to where you keep your scripts located. I prefer to keep them all in Document Libraries as I can make changes to them without having to remote into the server (and on a multiple web front end, that’s just a PITA), it provides me with version control of sorts, and it’s quick to add new plugins and scripts. Now we can look at our RedirectToID.js script. This invokes the SPServices Library to call the GetListItems method of the Lists web service and then rewrites the URL to DispForm.aspx to use the correct SharePoint ID (the internal one). $(document).ready(function(){ var queryStringValues = $().SPServices.SPGetQueryString(); var id = queryStringValues["ID"]; if(id == "0") { var customer = queryStringValues["CustomerNumber"]; var query = "<Query><Where><Eq><FieldRef Name='CustomerNumber'/><Value Type='Text'>" + customer + "</Value></Eq></Where></Query>"; var url = window.location; $().SPServices({ operation: "GetListItems", listName: "Customers", async: false, CAMLQuery: query, completefunc: function (xData, Status) { $(xData.responseXML).find("[nodeName=z:row]").each(function(){ id = $(this).attr("ows_ID"); url = $().SPServices.SPGetCurrentSite() + "/Lists/Customers/DispForm.aspx?ID=" + id; window.location = url; }); } }); } }); What’s happening here? Line 3: We call SPServices.SPGetQueryString to get an array of query string values (a handy function in the library as I had 15 lines of code to do this which is now gone). Line 4: Extract the ID value from the query string Line 6: If we pass in “0” it means we’re looking up a field value. This allows DispForm.aspx to work like normal with SharePoint lists but lookup our values when invoked. Why ID at all? DispForm.aspx doesn’t work unless you pass in something and “0” is a *magic* number that will invoke the page but not lookup a value in the database. Line 8-15: Extract the CustomerNumber query string value, build a CAML query to find it then call the GetListitems method using SPServices Line 16: Process the results in our completefunc to iterate over all the rows (there should only be one) and extract the real ID of the item Line 17-20: Build a new URL based on the site (using a call to SPGetCurrentSite) and append our real ID to redirect to the DispForm.aspx page As you can see, it dynamically creates a CAML query for the call to the web service using the passed in value. You could even make this generic to take in different query strings, one for the field name to search for and the other for the value to find. That way it could be used for any field you want. For example you could bring up the correct item on the DispForm.aspx page based on customer name with something like this: http://myserver/Lists/Customers/DispForm.aspx?ID=0&FilterId=CustomerName&FilterValue=Sony Use your imagination. Some people would opt for building a custom page with a DVWP but if you want to leverage all the functionality of DispForm.aspx this might come in handy if you don’t want to rely on internal SharePoint IDs.

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• Week in Geek: 4chan Falls Victim to DDoS Attack Edition

  - by Asian Angel

  This week we learned how to tweak the low battery action on a Windows 7 laptop, access an eBook collection anywhere in the world, “extend iPad battery life, batch resize photos, & sync massive music collections”, went on a reign of destruction with Snow Crusher, and had fun decorating our desktops with abstract icon collections. Photo by pasukaru76. Random Geek Links We have included extra news article goodness to help you catch up on any developments that you may have missed during the holiday break this past week. Note: The three 27C3 articles listed here represent three different presentations at the 27th Chaos Communication Congress hacker conference. 4chan victim of DDoS as FBI investigates role in PayPal attack Users of 4chan may have gotten a taste of their own medicine after the site was knocked offline by a DDoS attack from an unknown origin early Thursday morning. Report: FBI seizes server in probe of WikiLeaks attacks The FBI has seized a server in Texas as part of its hunt for the groups behind the pro-WikiLeaks denial-of-service attacks launched in December against PayPal, Visa, MasterCard, and others. Mozilla exposes older user-account database Mozilla has disabled 44,000 older user accounts for its Firefox add-ons site after a security researcher found part of a database of the account information on a publicly available server. Data breach affects 4.9 million Honda customers Japanese automaker Honda has put some 2.2 million customers in the United States on a security breach alert after a database containing information on the owners and their cars was hacked. Chinese Trojan discovered in Android games An Android-based Trojan called “Geinimi” has been discovered in the wild and the Trojan is capable of sending personal information to remote servers and exhibits botnet-like behavior. 27C3 presentation claims many mobiles vulnerable to SMS attacks According to security experts, an ‘SMS of death’ threatens to disable many current Sony Ericsson, Samsung, Motorola, Micromax and LG mobiles. 27C3: GSM cell phones even easier to tap Security researchers have demonstrated how open source software on a number of revamped, entry-level cell phones can decrypt and record mobile phone calls in the GSM network. 27C3: danger lurks in PDF documents Security researcher Julia Wolf has pointed out numerous, previously hardly known, security problems in connection with Adobe’s PDF standard. Critical update for WordPress A critical update has been made available for WordPress in the form of version 3.0.4. The update fixes a security bug in WordPress’s KSES library. McAfee Labs Predicts Geolocation, Mobile Devices and Apple Will Top the List of Targets for Emerging Threats in 2011 The list comprises 2010’s most buzzed about platforms and services, including Google’s Android, Apple’s iPhone, foursquare, Google TV and the Mac OS X platform, which are all expected to become major targets for cybercriminals. McAfee Labs also predicts that politically motivated attacks will be on the rise. Windows Phone 7 piracy materializes with FreeMarketplace A proof-of-concept application, FreeMarketplace, that allows any Windows Phone 7 application to be downloaded and installed free of charge has been developed. Empty email accounts, and some bad buzz for Hotmail In the past few days, a number of Hotmail users have been complaining about a rather disconcerting issue: their Hotmail accounts, some up to 10 years old, appear completely empty.  No emails, no folders, nothing, just what appears to be a new account. Reports: Nintendo warns of 3DS risk for kids Nintendo has reportedly issued a warning that the 3DS, its eagerly awaited glasses-free 3D portable gaming device, should not be used by children under 6 when the gadget is in 3D-viewing mode. Google eyes ‘cloaking’ as next antispam target Google plans to take a closer look at the practice of “cloaking,” or presenting one look to a Googlebot crawling one’s site while presenting another look to users. Facebook, Twitter stock trading drawing SEC eye? The high degree of investor interest in shares of hot Silicon Valley companies that aren’t yet publicly traded–like Facebook, Twitter, LinkedIn, and Zynga–may be leading to scrutiny from the U.S. Securities and Exchange Commission (SEC). Random TinyHacker Links Photo by jcraveiro. Exciting Software Set for Release in 2011 A few bloggers from great websites such as How-To Geek, Guiding Tech and 7 Tutorials took the time to sit down and talk about their software wishes for 2011. Take the time to read it and share… Wikileaks Infopr0n An infographic detailing the quest to plug WikiLeaks. The New York Times Guide to Mobile Apps A growing collection of all mobile app coverage by the New York Times as well as lists of favorite apps from Times writers. 7,000,000,000 (Video) A fascinating look at the world’s population via National Geographic Magazine. Super User Questions Check out the great answers to these hot questions from Super User. How to use a Personal computer as a Linux web server for development purposes? How to link processing power of old computers together? Free virtualization tool for testing suspicious files? Why do some actions not work with Remote Desktop? What is the simplest way to send a large batch of pictures to a distant friend or colleague? How-To Geek Weekly Article Recap Had a busy week and need to get caught up on your HTG reading? Then sit back and relax while enjoying these hot posts full of how-to roundup goodness. The 50 Best How-To Geek Windows Articles of 2010 The 20 Best How-To Geek Explainer Topics for 2010 The 20 Best How-To Geek Linux Articles of 2010 How to Search Just the Site You’re Viewing Using Google Search Ask the Readers: Backing Your Files Up – Local Storage versus the Cloud One Year Ago on How-To Geek Need more how-to geekiness for your weekend? Then look through this great batch of articles from one year ago that focus on dual-booting and O.S. installation goodness. Dual Boot Your Pre-Installed Windows 7 Computer with Vista Dual Boot Your Pre-Installed Windows 7 Computer with XP How To Setup a USB Flash Drive to Install Windows 7 Dual Boot Your Pre-Installed Windows 7 Computer with Ubuntu Easily Install Ubuntu Linux with Windows Using the Wubi Installer The Geek Note We hope that you and your families have had a terrific holiday break as everyone prepares to return to work and school this week. Remember to keep those great tips coming in to us at [email protected]! Photo by pjbeardsley. Latest Features How-To Geek ETC The 20 Best How-To Geek Linux Articles of 2010 The 50 Best How-To Geek Windows Articles of 2010 The 20 Best How-To Geek Explainer Topics for 2010 How to Disable Caps Lock Key in Windows 7 or Vista How to Use the Avira Rescue CD to Clean Your Infected PC The Complete List of iPad Tips, Tricks, and Tutorials Tune Pop Enhances Android Music Notifications Another Busy Night in Gotham City Wallpaper Classic Super Mario Brothers Theme for Chrome and Iron Experimental Firefox Builds Put Tabs on the Title Bar (Available for Download) Android Trojan Found in the Wild Chaos, Panic, and Disorder Wallpaper

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