Search Results

Search found 22641 results on 906 pages for 'use case'.

Page 751/906 | < Previous Page | 747 748 749 750 751 752 753 754 755 756 757 758  | Next Page >

• Building "isolated" and "automatically updated" caches (java.util.List) in Java.

  - by Aidos

  Hi Guys, I am trying to write a framework which contains a lot of short-lived caches created from a long-living cache. These short-lived caches need to be able to return their entier contents, which is a clone from the original long-living cache. Effectively what I am trying to build is a level of transaction isolation for the short-lived caches. The user should be able to modify the contents of the short-lived cache, but changes to the long-living cache should not be propogated through (there is also a case where the changes should be pushed through, depending on the Cache type). I will do my best to try and explain: master-cache contains: [A,B,C,D,E,F] temporary-cache created with state [A,B,C,D,E,F] 1) temporary-cache adds item G: [A,B,C,D,E,F] 2) temporary-cache removes item B: [A,C,D,E,F] master-cache contains: [A,B,C,D,E,F] 3) master-cache adds items [X,Y,Z]: [A,B,C,D,E,F,X,Y,Z] temporary-cache contains: [A,C,D,E,F] Things get even harder when the values in the items can change and shouldn't always be updated (so I can't even share the underlying object instances, I need to use clones). I have implemented the simple approach of just creating a new instance of the List using the standard Collection constructor on ArrayList, however when you get out to about 200,000 items the system just runs out of memory. I know the value of 200,000 is excessive to iterate, but I am trying to stress my code a bit. I had thought that it might be able to somehow "proxy" the list, so the temporary-cache uses the master-cache, and stores all of it's changes (effectively a Memento for the change), however that quickly becomes a nightmare when you want to iterate the temporary-cache, or retrieve an item at a specific index. Also given that I want some modifications to the contents of the list to come through (depending on the type of the temporary-cache, whether it is "auto-update" or not) and I get completly out of my depth. Any pointers to techniques or data-structures or just general concepts to try and research will be greatly appreciated. Cheers, Aidos

  Read the article

• Does "delegate" mean a type or an object?

  - by Michal Czardybon

  Reading from MSDN: "A delegate is a type that references a method. Once a delegate is assigned a method, it behaves exactly like that method." Does then "delegate" mean a type or an object?! ...It cannot be both. It seems to me that the single word is used in two different meanings: a type containing a reference to a method of some specified signature, an object of that type, which can be actually called like a method. I would prefer a more precise vocabulary and use "delegate type" for the first case. I have been recently reading a lot about events and delegates and that ambiguity was making me confused many times. Some other uses of "delegate" word in MSDN in the first meaning: "Custom event delegates are needed only when an event generates event data" "A delegate declaration defines a class that is derived from the class System.Delegate" Some other uses of "delegate" word in MSDN in the second meaning: "specify a delegate that will be called upon the occurrence of some event" "Delegates are objects that refer to methods. They are sometimes described as type-safe function pointers" What do you think? Why did people from Microsoft introduced this ambiguity? Am I the only person to have conceptual problems with different notions being referenced with the same word.

  Read the article

• Fastest XML parser for small, simple documents in Java

  - by Varkhan

  I have to objectify very simple and small XML documents (less than 1k, and it's almost SGML: no namespaces, plain UTF-8, you name it...), read from a stream, in Java. I am using JAXP to process the data from my stream into a Document object. I have tried Xerces, it's way too big and slow... I am using Dom4j, but I am still spending way too much time in org.dom4j.io.SAXReader. Does anybody out there have any suggestion on a faster, more efficient implementation, keeping in mind I have very tough CPU and memory constraints? [Edit 1] Keep in mind that my documents are very small, so the overhead of staring the parser can be important. For instance I am spending as much time in org.xml.sax.helpers.XMLReaderFactory.createXMLReader as in org.dom4j.io.SAXReader.read [Edit 2] The result has to be in Dom format, as I pass the document to decision tools that do arbitrary processing on it, like switching code based on the value of arbitrary XPaths, but also extracting lists of values packed as children of a predefined node. [Edit 3] In any case I eventually need to load/parse the complete document, since all the information it contains is going to be used at some point. (This question is related to, but different from, http://stackoverflow.com/questions/373833/best-xml-parser-for-java )

  Read the article

• Exporting and reformatting data out of MS Excel

  - by Matt H

  I have a huge Excel spreadsheet containing telephone calling rates to a number of different countries. The format of the columns is: Country, RateLocality, Prefixes, Rate, Wholesale e.g. Afganistan, Default, 93;930;931;9321;9322;9323;9324;9325;9326;9327;9328;9329;9331;9332;9333;9334;9335;9336;9337;9338;9339;9341;9342;9343;9344;9345;9346;9347;9348;9349;9351;9352;9353;9354;9355;9356;9357;9358;9359;9361;9362;9363;9364;9365;9366;9367;9368;9369;9371;9372;9373;9374;9376;938;939; $ 1.023, $0.455 These rates change every so often and I need to get them into another system that can import them using CSV. The eventual format is: LD PREPEND CODE ie. 00 or 011,CountryCode,Area Code,Comment,Connect Cost,Included Seconds,Per Minute Cost,Pricelist,Increment So to convert that above line I'd have 00,"Afganistan",93,"Default",1.023,60,1.023,10 00,"Afganistan",931,"Default",1.023,60,1.023,10 ... 00,"Afganistan",939,"Default",1.023,60,1.023,10 Where 00, 60 and 10 are hard coded and merged with the other data from excel. How can I export this data into the required format given that I need to reformat it as it goes. Should I export to XML and use XSLT or some other process to massage the data into CSV? If that is the case, how do I do it simply and quickly.

  Read the article

• Whose fault is a NullReferenceException?

  - by stefan.at.wpf

  I'm currently working on a class which exposes an internal List through a property. The List shall and can be modified. The problem is, entries in the internal list could be set to null from outside the class. My code actually looks like this: class ClassWithList { List<object> _list = new List<object>(); // get accessor, which however returns the reference to the list, // therefore the list can be modified (this is intended) public List<object> Data { get { return _list; } } private void doSomeWorkWithTheList() { foreach(object obj in _list) // do some work with the objects in the list without checking for null. } } So now in the doSomeWorkWithTheList() I could always check whether the current list entry is null or I could just asume that the person using this class doesn't have the great idea to set entries to null. So finally the questions end up in: Whose fault is a NullReferenceException in this case? Is it the fault of the class developer not checking everything for null (which would make code generally - not only in this class - more complex) or is it the fault of the user of this class, as setting a List entry to null doesn't really make sense? I'd tend to generally not check values for null except in some really special cases. Is this a bad style or de facto standard / standard in praxis? I know there's probably no ultimate answer for this, I'm just missing enough experience for such thing and therefore wondering what other developers think about such cases and want to hear what's done in reality about checking null (or not).

  Read the article

• 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

  Read the article

• Is Assert.Fail() considered bad practice?

  - by Mendelt

  I use Assert.Fail a lot when doing TDD. I'm usually working on one test at a time but when I get ideas for things I want to implement later I quickly write an empty test where the name of the test method indicates what I want to implement as sort of a todo-list. To make sure I don't forget I put an Assert.Fail() in the body. When trying out xUnit.Net I found they hadn't implemented Assert.Fail. Of course you can always Assert.IsTrue(false) but this doesn't communicate my intention as well. I got the impression Assert.Fail wasn't implemented on purpose. Is this considered bad practice? If so why? @Martin Meredith That's not exactly what I do. I do write a test first and then implement code to make it work. Usually I think of several tests at once. Or I think about a test to write when I'm working on something else. That's when I write an empty failing test to remember. By the time I get to writing the test I neatly work test-first. @Jimmeh That looks like a good idea. Ignored tests don't fail but they still show up in a separate list. Have to try that out. @Matt Howells Great Idea. NotImplementedException communicates intention better than assert.Fail() in this case @Mitch Wheat That's what I was looking for. It seems it was left out to prevent it being abused in another way I abuse it.

  Read the article

• C++ Loop - Need variable to accumulate sum

  - by user1780064

  I'm writing a program to ask the user to enter a value between 5 and 21 (inclusive). If the number entered is not in this range, it prints, "Please try again". If the number is within the range, I need to take that number, and print the sum of all the numbers from 1 to the value entered. So if the user entered "7", the sum would be "28". I successfully wrote the first loop, in the case of the number not being within the range, but cannot figure out how to run the second loop- whether to use a while, do-while, or for loop. Please advise. #include <iostream> int main () { int uservalue; int count; int sum; //Prompt user for input do { cout << "Enter a value from 5 to 21: "; cin >> uservalue; if (uservalue < 5 || uservalue > 21) cout << "Value out of range. Try again..." << endl; } while (uservalue < 5 || uservalue > 21); cout << endl; //Loop to accumulate sum for (count = 1, count < uservalue, count++;) { sum = uservalue + count; if (uservalue <= 5 || uservalue <= 21) cout << the sum is " << sum << endl; } return 0; }

  Read the article

• need help with mvc & routes

  - by geoff

  I'm very new to MVC and I'm trying to get a new site set up using it. For SEO reasons we need to make the url of a page something like "Recruiter/4359/John_Smith" or basically {controller}/{id}/{name}. I have that working when I create the url in the code behind like so... //r is a recruiter object that is part of the results for the view r.Summary = searchResult.Summary + "... &lt;a href=\"/Recruiter/" + r.Id + "/" + r.FirstName + "_" + r.LastName + "\"&gt;Read More&lt;/a&gt;" But when I am using the collection of results from a search in my view and iterating through them I am trying to create another link to the same page doing something like <%=Html.ActionLink<RecruiterController>(x => x.Detail((int)r.Id), r.RecruiterName)%> but that doesn't work. When I use that code in the view it gives me a url in the form of /Recruiter/Detail/4359 I was told by a coworker that I should use the Html.ActionLink to create the link in both the view and the controller so that if the route changes in the future it will automatically work. Unfortunately he wasn't sure how to do that in this case. So, my problems are... How can I make the Html.ActionLink work in the view to create a url like I need (like r.Summary above)? How do I use the Html.ActionLink in a controller instead of hardcoding the link like I have above?

  Read the article

• What are salesforce.com and Apex like as an application development platform?

  - by mhollers

  I have recently discovered that salesforce.com is much more than an online CRM after coming across a Morrison's Case Study in which they develop a works management application. I've been trying it out with a view to recreating our own Works Management system on the platform. My background is in Microsoft and .Net, and the obvious 1st choice would be asp.net. However, there's only really myself with .net experience and my manager with a more legacy Synergy programming background, and I am self taught and am looking at evaluating other RAD options (eg Ironspeed). the nature of the business is in the main 2-5 concurrent construction type contracts that run for 3-5 yrs each, each requiring 15-50 system users. Traditionally we have used our character based Works Mangement system for everything and tweaked it for each contract. The Salesforce licensing model on the face of it suits this sort of flexibilty, but I'm worried about the development flexibilty/learning curve and all the issues that surround lock-in. There doesn't seem to be much neutral sober analysis of the platform on the web that isn't salesforce's own material/blogs Has anyone any experience of developing an application on salesforce as compared to the more 'traditional' .Net route?

  Read the article

• media.set_xx giving me grief!

  - by Firas

  New guy here. I asked a while back about a sprite recolouring program that I was having difficulty with and got some great responses. Basically, I tried to write a program that would recolour pixels of all the pictures in a given folder from one given colour to another. I believe I have it down, but, now the program is telling me that I have an invalid value specified for the red component of my colour. (ValueError: Invalid red value specified.), even though it's only being changed from 64 to 56. Any help on the matter would be appreciated! (Here's the code, in case I messed up somewhere else; It's in Python): import os import media import sys def recolour(old, new, folder): old_list = old.split(' ') new_list = new.split(' ') folder_location = os.path.join('C:\', 'Users', 'Owner', 'Spriting', folder) for filename in os.listdir (folder): current_file = media.load_picture(folder_location + '\\' + filename) for pix in current_file: if (media.get_red(pix) == int(old_list[0])) and \ (media.get_green(pix) == int(old_list[1])) and \ (media.get_blue(pix) == int(old_list[2])): media.set_red(pix, new_list[0]) media.set_green(pix, new_list[1]) media.set_blue(pix, new_list[2]) media.save(pic) if name == 'main': while 1: old = str(raw_input('Please insert the original RGB component, separated by a single space: ')) if old == 'quit': sys.exit(0) new = str(raw_input('Please insert the new RGB component, separated by a single space: ')) if new == 'quit': sys.exit(0) folder = str(raw_input('Please insert the name of the folder you wish to modify: ')) if folder == 'quit': sys.exit(0) else: recolour(old, new, folder)

  Read the article

• waveInProc / Windows audio question...

  - by BTR

  I'm using the Windows API to get audio input. I've followed all the steps on MSDN and managed to record audio to a WAV file. No problem. I'm using multiple buffers and all that. I'd like to do more with the buffers than simply write to a file, so now I've got a callback set up. It works great and I'm getting the data, but I'm not sure what to do with it once I have it. Here's my callback... everything here works: // Media API callback void CALLBACK AudioRecorder::waveInProc(HWAVEIN hWaveIn, UINT uMsg, DWORD dwInstance, DWORD dwParam1, DWORD dwParam2) { // Data received if (uMsg == WIM_DATA) { // Get wav header LPWAVEHDR mBuffer = (WAVEHDR *)dwParam1; // Now what? for (unsigned i = 0; i != mBuffer->dwBytesRecorded; ++i) { // I can see the char, how do get them into my file and audio buffers? cout << mBuffer->lpData[i] << "\n"; } // Re-use buffer mResultHnd = waveInAddBuffer(hWaveIn, mBuffer, sizeof(mInputBuffer[0])); // mInputBuffer is a const WAVEHDR * } } // waveInOpen cannot use an instance method as its callback, // so we create a static method which calls the instance version void CALLBACK AudioRecorder::staticWaveInProc(HWAVEIN hWaveIn, UINT uMsg, DWORD_PTR dwInstance, DWORD_PTR dwParam1, DWORD_PTR dwParam2) { // Call instance version of method reinterpret_cast<AudioRecorder *>(dwParam1)->waveInProc(hWaveIn, uMsg, dwInstance, dwParam1, dwParam2); } Like I said, it works great, but I'm trying to do the following: Convert the data to short and copy into an array Convert the data to float and copy into an array Copy the data to a larger char array which I'll write into a WAV Relay the data to an arbitrary output device I've worked with FMOD a lot and I'm familiar with interleaving and all that. But FMOD dishes everything out as floats. In this case, I'm going the other way. I guess I'm basically just looking for resources on how to go from LPSTR to short, float, and unsigned char. Thanks much in advance!

  Read the article

• Dereferencing the null pointer

  - by zilgo

  The standard says that dereferencing the null pointer leads to undefined behaviour. But what is "the null pointer"? In the following code, what we call "the null pointer": struct X { static X* get() { return reinterpret_cast<X*>(1); } void f() { } }; int main() { X* x = 0; (*x).f(); // the null pointer? (1) x = X::get(); (*x).f(); // the null pointer? (2) x = reinterpret_cast<X*>( X::get() - X::get() ); (*x).f(); // the null pointer? (3) (*(X*)0).f(); // I think that this the only null pointer here (4) } My thought is that dereferencing of the null pointer takes place only in the last case. Am I right? Is there difference between compile time null pointers and runtime according to C++ Standard?

  Read the article

• Evaluating expressions using Visual Studio 2005 SDK rather than automation's Debugger::GetExpression

  - by brone

  I'm looking into writing an addin (or package, if necessary) for Visual Studio 2005 that needs watch window type functionality -- evaluation of expressions and examination of the types. The automation facilities provide Debugger::GetExpression, which is useful enough, but the information provided is a bit crude. From looking through the docs, it sounds like an IDebugExpressionContext2 would be more useful. With one of these it looks as if I can get more information from an expression -- detailed information about the type and any members and so on and so forth, without having everything come through as strings. I can't find any way of actually getting a IDebugExpressionContext2, though! IDebugProgramProvider2 sort of looks relevant, in that I could start with IDebugProgramProvider2::GetProviderProcessData and then slowly drill down until reaching something that can supply my expression context -- but I'll need to supply a port to this, and it's not clear how to retrieve the port corresponding to the current debug session. (Even if I tried every port, it's not obvious how to tell which port is the right one...) I'm becoming suspicious that this simply isn't a supported use case, but with any luck I've simply missed something crashingly obvious. Can anybody help?

  Read the article

• Omit return type in C++0x

  - by Clinton

  I've recently found myself using the following macro with gcc 4.5 in C++0x mode: #define RETURN(x) -> decltype(x) { return x; } And writing functions like this: template <class T> auto f(T&& x) RETURN (( g(h(std::forward<T>(x))) )) I've been doing this to avoid the inconvenience having to effectively write the function body twice, and having keep changes in the body and the return type in sync (which in my opinion is a disaster waiting to happen). The problem is that this technique only works on one line functions. So when I have something like this (convoluted example): template <class T> auto f(T&& x) -> ... { auto y1 = f(x); auto y2 = h(y1, g1(x)); auto y3 = h(y1, g2(x)); if (y1) { ++y3; } return h2(y2, y3); } Then I have to put something horrible in the return type. Furthermore, whenever I update the function, I'll need to change the return type, and if I don't change it correctly, I'll get a compile error if I'm lucky, or a runtime bug in the worse case. Having to copy and paste changes to two locations and keep them in sync I feel is not good practice. And I can't think of a situation where I'd want an implicit cast on return instead of an explicit cast. Surely there is a way to ask the compiler to deduce this information. What is the point of the compiler keeping it a secret? I thought C++0x was designed so such duplication would not be required.

  Read the article

• How to get timestamp of tick precision in .NET / C#?

  - by Hermann

  Up until now I used DateTime.Now for getting timestamps, but I noticed that if you print DateTime.Now in a loop you will see that it increments in descrete jumps of approx. 15 ms. But for certain scenarios in my application I need to get the most accurate timestamp possible, preferably with tick (=100 ns) precision. Any ideas? Update: Apparently, StopWatch / QueryPerformanceCounter is the way to go, but it can only be used to measure time, so I was thinking about calling DateTime.Now when the application starts up and then just have StopWatch run and then just add the elapsed time from StopWatch to the initial value returned from DateTime.Now. At least that should give me accurate relative timestamps, right? What do you think about that (hack)? NOTE: StopWatch.ElapsedTicks is different from StopWatch.Elapsed.Ticks! I used the former assuming 1 tick = 100 ns, but in this case 1 tick = 1 / StopWatch.Frequency. So to get ticks equivalent to DateTime use StopWatch.Elapsed.Ticks. I just learned this the hard way. NOTE 2: Using the StopWatch approach, I noticed it gets out of sync with the real time. After about 10 hours, it was ahead by 5 seconds. So I guess one would have to resync it every X or so where X could be 1 hour, 30 min, 15 min, etc. I am not sure what the optimal timespan for resyncing would be since every resync will change the offset which can be up to 20 ms.

  Read the article

• Does it ever make sense to make a fundamental (non-pointer) parameter const?

  - by Scott Smith

  I recently had an exchange with another C++ developer about the following use of const: void Foo(const int bar); He felt that using const in this way was good practice. I argued that it does nothing for the caller of the function (since a copy of the argument was going to be passed, there is no additional guarantee of safety with regard to overwrite). In addition, doing this prevents the implementer of Foo from modifying their private copy of the argument. So, it both mandates and advertises an implementation detail. Not the end of the world, but certainly not something to be recommended as good practice. I'm curious as to what others think on this issue. Edit: OK, I didn't realize that const-ness of the arguments didn't factor into the signature of the function. So, it is possible to mark the arguments as const in the implementation (.cpp), and not in the header (.h) - and the compiler is fine with that. That being the case, I guess the policy should be the same for making local variables const. One could make the argument that having different looking signatures in the header and source file would confuse others (as it would have confused me). While I try to follow the Principle of Least Astonishment with whatever I write, I guess it's reasonable to expect developers to recognize this as legal and useful.

  Read the article

• How to pick a specific object from a Linq Query using Distinct?

  - by Holli

  I have a list with two or more objects of class Agent. Name = "A" Priority = 0 ResultCount = 100 ; Name = "B" Priority = 1 ResultCount = 100 ; Both objects have the same ResultCount. In that case I only need one object and not two or more. I did this with a Linq Query with Distinct and an custom made Comparer. IEnumerable<Agent> distinctResultsAgents = (from agt in distinctUrlsAgents select agt).Distinct(comparerResultsCount); With this query I get only one object from the list but I never know which one. But I don't want just any object, I want object "B" because the Priority is higher then object "A". How can I do that? My custom Comparer is very simple and has a method like this: public bool Equals(Agent x, Agent y) { if (x == null || y == null) return false; if (x.ResultCount == y.ResultCount) return true; return false; }

  Read the article

• Using Relative Paths to Load Resources in Cocoa/C++

  - by moka

  I am currently working directly with Cocoa for the first time to built a screen saver. Now I came across a problem when trying to load resources from within the .saver bundle. I basically have a small C++ wrapper class to load .exr files using freeImage. This works as long as I use absoulte paths, but that's not very useful, is it? So, basically, I tried everything: putting the .exr file at the level of the .saver bundle itself, inside the bundles Resources folder, and so on. Then I simply tried to load the .exr like this, but without success: particleTex = [self loadExrTexture:@"ball.exr"]; I also tried making it go to the .saver bundles location like this: particleTex = [self loadExrTexture:@"../../../ball.exr"]; ...to maybe load the .exr from that location, but without success. I then came across this: NSString * path = [[NSBundle mainBundle] pathForResource:@"ball" ofType:@"exr"]; const char * pChar = [path UTF8String]; ...which seems to be a common way to find resources in Cocoa, but for some reason it's empty in my case. Any ideas about that? I really tried out anything that came to my mind without success so I would be glad about some input!

  Read the article

• WordPress website getting hung up for 10-15 seconds

  - by synergy989

  Problem I have a website (which loads fine): http://testupg.videve.com/ Go to the blog section (and it begins to load, gets hung up, then loads): http://testupg.videve.com/blog/ It's all one WordPress install. The only pages that are getting hung up are the blog page itself and any article page. The video pages load fine etc. What Have I done and noticed. If I disable all plugins, the blog page loads fine. I narrowed it down to DisplayBuddy plugins (Featured posts, Carousel, Slider)...as soon as I enable any single one of them, the site loads slow. The thing that doesn't make sense is, I disabled the sidebar (deleted it from the template) and the article page still loaded slow and it has ZERO instances of this plugin. I disable the plugin and the article page loads fine. How on earth can this be? I am hoping this case above can give just a little bit of insight! One other thing. The video pages use a custom taxonomy so I am wondering if its something to do with the default wordpress taxonomy. Any help is GREATLY appreciated, I have been at this thing for hours and it's time to call in some support. Cheers

  Read the article

• How many WCF connections can a single host handle?

  - by mafutrct

  I'll try to explain this with an example. I'm writing a chat application. There are users that can join chat rooms. A user has to log in before he can join any room. Currently, there is a single service. A user logs in using this service. Then, the user sends and receives messages for all joined rooms via this single service. channel.Login("Hans Moleman", "password"); channel.JoinRoom("name of room"); channel.SendChat("name of room", "hello"); I'm thinking about changing the design so there is a new WCF connection for each joined room. In the actual app, the number of connections is likely going to be in the range of 10-100, possibly more. Is this a good idea? Or are ~100 connections per client too much? The server should be able to handle many clients (range 100-1000, later up to 10k). In case it matters, I'm using NetTcpBinding.

  Read the article

• How do I close a file after catching an IOException in java?

  - by DimDom

  All, I am trying to ensure that a file I have open with BufferedReader is closed when I catch an IOException, but it appears as if my BufferedReader object is out of scope in the catch block. public static ArrayList readFiletoArrayList(String fileName, ArrayList fileArrayList) { fileArrayList.removeAll(fileArrayList); try { //open the file for reading BufferedReader fileIn = new BufferedReader(new FileReader(fileName)); // add line by line to array list, until end of file is reached // when buffered reader returns null (todo). while(true){ fileArrayList.add(fileIn.readLine()); } }catch(IOException e){ fileArrayList.removeAll(fileArrayList); fileIn.close(); return fileArrayList; //returned empty. Dealt with in calling code. } } Netbeans complains that it "cannot find symbol fileIn" in the catch block, but I want to ensure that in the case of an IOException that the Reader gets closed. How can I do that without the ugliness of a second try/catch construct around the first? Any tips or pointers as to best practise in this situation is appreciated,

  Read the article

• Java: fastest way to do random reads on huge disk file(s)

  - by cocotwo

  I've got a moderately big set of data, about 800 MB or so, that is basically some big precomputed table that I need to speed some computation by several orders of magnitude (creating that file took several mutlicores computers days to produce using an optimized and multi-threaded algo... I do really need that file). Now that it has been computed once, that 800MB of data is read only. I cannot hold it in memory. As of now it is one big huge 800MB file but splitting in into smaller files ain't a problem if it can help. I need to read about 32 bits of data here and there in that file a lot of time. I don't know before hand where I'll need to read these data: the reads are uniformly distributed. What would be the fastest way in Java to do my random reads in such a file or files? Ideally I should be doing these reads from several unrelated threads (but I could queue the reads in a single thread if needed). Is Java NIO the way to go? I'm not familiar with 'memory mapped file': I think I don't want to map the 800 MB in memory. All I want is the fastest random reads I can get to access these 800MB of disk-based data. btw in case people wonder this is not at all the same as the question I asked not long ago: http://stackoverflow.com/questions/2346722/java-fast-disk-based-hash-set

  Read the article

• Using JMX classes to notify on events over time

  - by Cincinnati Joe

  I've been looking at JMX for monitoring application and system metrics (partially because MBeans can accessed by various tools such as JConsole). It would seem like the classes included with JMX would be useful for things like notification when metrics have exceeded thresholds. But I'm not sure they fit with the way I want to measure these over a specified time period. For example, let's say I want to notify an admin when the average CPU load is over 95% for more than 5 minutes. Is that something can be done with a GaugeMonitor? From the docs, it doesn't seem quite suited for this, and I'm wondering if instead I should write my own MBean with the necessary logic. A more relevant example is when the login times for users exceed 10s over a period of 5 mins. Slightly different would be the last 20 logins took more than 10s on average. Another case would be when a process crashes 4+ times in an hour. Or the request queue exceeds 15 for 5 mins. Are the JMX Monitor classes useful for this kind of thing?

  Read the article

• Problem with mouse event on a user control (wpf).

  - by csciguy

  All, I have a user control, defined as follows. <UserControl x:Class="IDOView.AnimatedCharacter" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:local="clr-namespace:IDOView" mc:Ignorable="d" Background="Transparent" > <Image Name="displayImage" Height="Auto" Width="Auto" Stretch="Fill" IsHitTestVisible="True"/> The control is added to a main page twice, as follows. <local:customControl x:Name="A1" Height="259" Width="197" DisplayImage="circle.png" Canvas.Left="-279" Canvas.Top="-56" MouseLeftButtonUp="DoA1"> <local:customControl x:Name="A1" Height="259" Width="197" DisplayImage="square.png" Canvas.Left="-209" Canvas.Top="-56" MouseLeftButtonUp="DoA2"> Essentially, about half of the circle is behind the square. I need the square image in this case to pass through events to the circle behind it. The square has an element cut out of it (transparent). What is happening now is that the circle event only registers if I click on the region that is not covered by the square. Surely there has to be a way to bubble this event, or click-through?

  Read the article

< Previous Page | 747 748 749 750 751 752 753 754 755 756 757 758  | Next Page >