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• implementing a Intelligent File Transfer Software in java over TCP/IP

  - by whyjava

  Hello I am working on a proposal where we have to implement a software which can move files between one source to destination.The overall goal of this project is to create intelligent file transfer.This software will have three components :- 1) Broker : Broker is the module that communicates with other brokers, monitors files, moves files, retrieves configurations from the Configuration Manager, supplies process information for the monitor, archives files, writes all process data to log files and escalates issues if necessary 2) Configuration Manager :Configuration Manager is a web-based application used to configure and deploy the configuration to all brokers. 3) Monitor : Monitor is a web-based application used to monitor each Broker in the environment. This project has to be built up in java and protocol for file transfer in tcp/ip. Client does not want to use FTP. File Transfer seems very easy, until there are several processes who are waiting to pick the file up automatically. Several problems arise: How can we guarantee the file is received at the destination? If a file isn’t received the first time, we should try it again (even after a restart or power breakdown) ? How does the receiver knows the file that is received is complete? How can we transfer multiple files synchronously? How can we protect the bandwidth, so file transfer isn’t blocking other processes? How does one interoperate between multiple OS platforms? What about authentication? How can we monitor het workflow? Auditing / logging Archiving Can you please provide answer to some of these? Thanks

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• Java website protection solutions (especially XSS)

  - by Mark

  I'm developing a web application, and facing some security problems. In my app users can send messages and see other's (a bulletin board like app). I'm validating all the form fields that users can send to my app. There are some very easy fields, like "nick name", that can be 6-10 alpabetical characters, or message sending time, which is sended to the users as a string, and then (when users ask for messages, that are "younger" or "older" than a date) I parse this with SimpleDateFormat (I'm developing in java, but my question is not related to only java). The big problem is the message field. I can't restrict it to only alphabetical characters (upper or lowercase), because I have to deal with some often use characters like ",',/,{,} etc... (users would not be satisfied if the system didn't allow them to use these stuff) According to this http://ha.ckers.org/xss.html, there are a lot of ways people can "hack" my site. But I'm wondering, is there any way I can do to prevent that? Not all, because there is no 100% protection, but I'd like a solution that can protect my site. I'm using servlets on the server side, and jQuery, on the client side. My app is "full" AJAX, so users open 1 JSP, then all the data is downloaded and rendered by jQuery using JSON. (yeah, I know it's not "users-without-javascript" friendly, but it's 2010, right? :-) ) I know front end validation is not enough. I'd like to use 3 layer validation: - 1. front end, javascript validate the data, then send to the server - 2. server side, the same validation, if there is anything, that shouldn't be there (because of client side javascript), I BAN the user - 3. if there is anything that I wasn't able to catch earlier, the rendering process handle and render appropriately Is there any "out of the box" solution, especially for java? Or other solution that I can use?

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• Qt/C++ Error handling

  - by ShiGon

  I've been doing a lot of research about handling errors with Qt/C++ and I'm still as lost as when I started. Maybe I'm looking for an easy way out (like other languages provide). One, in particular, provides for an unhandled exception which I use religiously. When the program encounters a problem, it throws the unhandled exception so that I can create my own error report. That report gets sent from my customers machine to a server online which I then read later. The problem that I'm having with C++ is that any error handling that's done has to be thought of BEFORE hand (think try/catch or massive conditionals). In my experience, problems in code are not thought of before hand else there wouldn't be a problem to begin with. Writing a cross-platform application without a cross-platform error handling/reporting/trace mechanism is a little scary to me. My question is: Is there any kind of Qt or C++ Specific "catch-all" error trapping mechanism that I can use in my application so that, if something does go wrong I can, at least, write a report before it crashes?

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• Confirm box always displays first (javascript, jQuery, .Net)

  - by Jan-Frederik Carl

  Hello, I have a jQuery-Script to accomplish the following tasks: if a gridview in my form contains a row with a certain id, it has to be marked red. a confirm dialogue has to pop up to ask the user if he wants to do this or that. I built this code: if (response == "EntryInList") { $('#entryListContainer div table tbody tr').each(function() { if ($(this).attr('id') == 'entry_' + $('#<%= txtProductNumber.ClientID %>').val()) { $(this).css("color", "red"); } } ); if (!confirm("Entry already exists. Really overwrite?")) { jQuery('#<%= txtProductNumber.ClientID %>').val(''); jQuery('#<%= txtCount.ClientID %>').val(''); jQuery('#<%= txtProductNumber.ClientID %>').focus(); return false; } } As a result, the confirm box pops up first, without the row being turned red. Only after using the box, it becomes red. How would I get the row to be turned red at once? Another of my problems is that the confirm box denies my page to be scrolled down. But I would like to do this if the gridview is longer than the entire page.

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• EF4 + STE: Reattaching via a WCF Service? Using a new objectcontext each and every time?

  - by Martin

  Hi there, I am planning to use WCF (not ria) in conjunction with Entity Framework 4 and STE (Self tracking entitites). If i understnad this correctly my WCF should return an entity or collection of entities (using LIST for example and not IQueryable) to the client (in my case silverlight) The client then can change the entity or update it. At this point i believe it is self tracking???? This is where i sort of get a bit confused as there are a lot of reported problems with STEs not tracking.. Anyway... Then to update i just need to send back the entity to my WCF service on another method to do the update. I should be creating a new OBJECTCONTEXT everytime? In every method? If i am creaitng a new objectcontext everytime in everymethod on my WCF then don't i need to re-attach the STE to the objectcontext? So basically this alone wouldn't work?? using(var ctx = new MyContext()) { ctx.Orders.ApplyChanges(order); ctx.SaveChanges(); } Or should i be creating the object context once in the constructor of the WCF service so that 1 call and every additional call using the same wcf instance uses the same objectcontext? I could create and destroy the wcf service in each method call from the client - hence creating in effect a new objectcontext each time. I understand that it isn't a good idea to keep the objectcontext alive for very long. Any insight or information would be gratefully appreciated thanks

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• Avoid slowdowns while using off-site database

  - by Anders Holmström

  The basic layout of my problem is this: Website (ASP.NET/C#) hosted at a dedicated hosting company (location 1) Company database (SQL Server) with records of relevant data (location 2). Location 1 & 2 connected through VPN. Customer visiting the website and wanting to pull data from the company database. No possibility of changing the server locations or layout (i.e. moving the website to an in-office server isn't possible). What I want to do is figure out the best way to handle the data acces in this case, minimizing the need for time-expensive database calls over the VPN. The first idea I'm getting is this: When a user enters the section of the website needing the DB data, you pull all the needed tables from the database into a in-memory dataset. All subsequent views/updates to the data is done on this dataset. When the user leaves (logout, session timeout, browser closed etc) the dataset gets sent to the SQL server. I'm not sure if this is a realistic solution, and it obviously has some problems. If two web visitors are performing updates on the same data, the one finishing up last will have their changes overwriting the first ones. There's also no way of knowing you have the latest data (i.e. if a customer pulls som info on their projects and we update this info while they are viewing them, they won't see these changes PLUS the above overwriting issue will arise). The other solution would be to somehow aggregate database calls and make sure they only happen when you need them, e.g. during data updates but not during data views. But then again the longer a pause between these refreshing DB calls, the bigger a chance that the data view is out of date as per the problem described above. Any input on the above or some fresh ideas would be most welcome.

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• Creating a new object destroys an older object with different name in C++

  - by Mikael

  First question here! So, I am having some problems with pointers in Visual C++ 2008. I'm writing a program which will control six cameras and do some processing on them so to clean things up I have created a Camera Manager class. This class handles all operations which will be carried out on all the cameras. Below this is a Camera class which interacts with each individual camera driver and does some basic image processing. Now, the idea is that when the manager is initialised it creates two cameras and adds them to a vector so that I can access them later. The catch here is that when I create the second camera (camera2) the first camera's destructor is called for some reason, which then disconnects the camera. Normally I'd assume that the problem is somewhere in the Camera class, but in this case everything works perfectly as long as I don't create the camera2 object. What's gone wrong? CameraManager.h: #include "stdafx.h" #include <vector> #include "Camera.h" class CameraManager{ std::vector<Camera> cameras; public: CameraManager(); ~CameraManager(); void CaptureAll(); void ShowAll(); }; CameraManager.cpp: #include "stdafx.h" #include "CameraManager.h" CameraManager::CameraManager() { printf("Camera Manager: Initializing\n"); [...] Camera *camera1 = new Camera(NodeInfo,1, -44,0,0); cameras.push_back(*camera1); // Adding the following two lines causes camera1's destructor to be called. Why? Camera *camera2 = new Camera(NodeInfo,0, 44,0,0); cameras.push_back(*camera2); printf("Camera Manager: Ready\n"); }

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• How to find all initializations of instance variables in a Java package?

  - by Hank Gay

  I'm in the midst of converting a legacy app to Spring. As part of the transition, we're converting our service classes from an "instantiate new ones whenever you need one" style to a Springleton style, so I need a way to make sure they don't have any state. I'm comfortable on the *nix command-line, and I have access to IntelliJ (this strikes me as a good fit for Structural Search and Replace, if I could figure out how to use it), and I could track down an Eclipse install, if that would help. I just want to make absolutely sure I've found all the possible problems. UPDATE: Sorry for the confusion. I don't have a problem finding places where the old constructor was being called. What I'm looking for is a "bullet-proof" why to search all 100+ service classes for any sort of internal state. The most obvious one I could think of (and the only one I've really found so far) is cases where we use memoization in the classes, so they have instance variables that get initialized internally instead of via Spring. This means that when the same Springleton gets used for different requests, data can leak between them. Thanks.

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• Playframework sends 2 queries for fetched query

  - by MRu

  I currently have problems with the JPA at the play framework 1.2.4. I need to have a UserOptions model in a separate database and want to join it lazyly cause its only needed in one query. In this query I want to load the options eagerly and by searching I found out that can only be done by using a join query. If I use eager instead oder lazy, everything would be fine by using User.findById() and the options and the user is found in one query. But play sends two queries when I use a 'left join fetch' query. So heres the query: User.find(" SELECT user FROM User user LEFT JOIN FETCH user.options options WHERE user.id = ? ", Long.parseLong(id)).first(); And here the models: @Entity public class User extends Model { @OneToOne(mappedBy = "user", fetch = FetchType.LAZY) public UserOptions options; // ... } @Entity public class UserOptions extends Model { @OneToOne(fetch = FetchType.LAZY) public User user; } The question is why play sends two query for the fetch query? Thanks in advance

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• How to create custom query for CollectionOfElements

  - by Shervin

  Hi. I have problems creating a custom query. This is what entities: @Entity public class ApplicationProcess { @CollectionOfElements private Set<Template> defaultTemplates; //more fields } And Template.java @Embeddable @EqualsAndHashCode(exclude={"file", "selected", "used"}) public class Template implements Comparable<Template> { @Setter private ApplicationProcess applicationProcess; @Setter private Boolean used = Boolean.valueOf(false); public Template() { } @Parent public ApplicationProcess getApplicationProcess() { return applicationProcess; } @Column(nullable = false) @NotNull public String getName() { return name; } @Column(nullable = true) public Boolean isUsed() { return used; } public int compareTo(Template o) { return getName().compareTo(o.getName()); } } I want to create a update statement. I have tried these two: int v = entityManager.createQuery("update ApplicationProcess_defaultTemplates t set t.used = true " + "WHERE t.applicationProcess.id=:apId").setParameter("apId", ap.getId()) .executeUpdate(); ApplicationProcess_defaultTemplates is not mapped [update ApplicationProcess_defaultTemplates t set t.used = true WHERE t.applicationProcess.id=:apId] And I have tried int v = entityManager.createQuery("update Template t set t.used = true " + "WHERE t.applicationProcess.id=:apId").setParameter("apId", ap.getId()) .executeUpdate(); With the same error: Template is not mapped [update Template t set t.used = true WHERE t.applicationProcess.id=:apId] Any ideas? UPDATE I fixed it by creating native query int v = entityManager.createNativeQuery("update ApplicationProcess_defaultTemplates t set t.used=true where t.ApplicationProcess_id=:apId").setParameter("apId", ap.getId()).executeUpdate();

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• Uniquely identify files/folders in NTFS, even after move/rename

  - by Felix Dombek

  I haven't found a backup (synchronization) program which does what I want so I'm thinking about writing my own. What I have now does the following: It goes through the data in the source and for every file which has its archive bit set OR does not exist in the destination, copies it to the destination, overwriting a possibly existing file. When done, it checks for all files in the destination if it exists in the source, and if it doesn't, deletes it. The problem is that if I move or rename a large folder, it first gets copied to the destination even though it is in principle already there, just has a different path. Then the folder which was already there is deleted afterwards. Apart from the unnecessary copying, I frequently run into space problems because my backup drive isn't large enough to hold the original data twice. Is there a way to programmatically identify such moved/renamed files or folders, i.e. by NTFS ID or physical location on media or something else? Are there solutions to this problem? I do not care about the programming language, but hints for doing this with Python, C++, C#, Java or Prolog are appreciated.

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• jQuery Manual Resizable DIV

  - by JC

  Hi, I'm trying to create a resizable div without using jQuery's interface library. var myY = 0; var mouseDown = false; var originalHeight = 0; function resize(e){ if(mouseDown == true){ $("#cooldiv").height(originalHeight+e.pageY-myY); } } $(document).ready(function(){ $().mouseup(function(e){ myY = 0; mouseDown = false; originalHeight = 0; $().unbind("mousemove", resize); }); $("#resizeBar").mousedown(function(e){ myY = e.pageY; originalHeight = $("#cooldiv").height(); mouseDown = true; $().bind("mousemove", resize); }); }); ... <div id="cooldiv" style="width: 500px; height: 300px; background-color: #cccccc; position: relative;"> <div id="resizeBar" style="height: 10px; width: 500px; background-color: #aaaaaa; position: absolute; bottom: 0;"></div> </div> The first resize works fine(i.e. mousedown, mousemove then mouseup), but on subsequent (mousedown+mousemove)s, the browser attempts to drag the whole resizeBar div instead of properly resizing its parent container. On mouseup, the div then starts resizing "cooldiv" on mousemove without any mousedown required, until a further click of the mouse. These problems don't show up in Internet Explorer.

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• Setting up a web development/build environment

  - by Eric

  Hello all, My current project has a development web server and live web server. Developers make changes to files on the dev server and test them (by going to the dev address) and make changes as necessary. When the file or files are ready to go, they are copied to the live server. There is no version control. As you might expect, there are some problems with this model: It's hard to keep track of what other programmers have done. It's hard to keep track of what files should be copied to the live server. There is no version control. I'm in a position to make nearly any change I like, but I want it to be the right one! I have been turning this over in my head for quite a while, and I have a solution that might be okay. But I want SO's opinion. Certainly version control needs to be added. But how should it work with the existing codebase and where should the developers be testing? How can anyone know what needs to be moved to the live server? What other details need to be addressed? How would you attack this problem? Supplementary information: The website is vital, but not mission critical. A small amount of downtime is acceptable. There are very few developers. (Right now, only 4.) History: Before I started, the project used Visual Source Safe. This was a sufficiently bad experience that they quit using it and abandoned version control. The project is an ASP.NET (C#) website. This seems like a question that may have a complicated answer. Thanks for thinking about it!

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• Creating Binary Block from struct

  - by MOnsDaR

  I hope the title is describing the problem, i'll change it if anyone has a better idea. I'm storing information in a struct like this: struct AnyStruct { AnyStruct : testInt(20), testDouble(100.01), testBool1(true), testBool2(false), testBool3(true), testChar('x') {} int testInt; double testDouble; bool testBool1; bool testBool2; bool testBool3; char testChar; std::vector<char> getBinaryBlock() { //how to build that? } } The struct should be sent via network in a binary byte-buffer with the following structure: Bit 00- 31: testInt Bit 32- 61: testDouble most significant portion Bit 62- 93: testDouble least significant portion Bit 94: testBool1 Bit 95: testBool2 Bit 96: testBool3 Bit 97-104: testChar According to this definition the resulting std::vector should have a size of 13 bytes (char == byte) My question now is how I can form such a packet out of the different datatypes I've got. I've already read through a lot of pages and found datatypes like std::bitset or boost::dynamic_bitset, but neither seems to solve my problem. I think it is easy to see, that the above code is just an example, the original standard is far more complex and contains more different datatypes. Solving the above example should solve my problems with the complex structures too i think. One last point: The problem should be solved just by using standard, portable language-features of C++ like STL or Boost (

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• Why would paperclip not assign an ID to my uploaded photos?

  - by Trip

  I just deployed to a cluster server, and my delayed_jobs recipe was overwritten in the process. I solved that, delayed_jobs is up and running but can't find the ID of images that are uploaded. The images are saved correctly : Processing PhotosController#create (for 173.161.167.41 at 2010-06-01 05:09:14) [POST] Parameters: {"Filename"="1.jpg", "gallery_id"="1298", "action"="create", "amp"=nil, "authenticity_token"="qmbnpwFY8a5E3YtS/4fMWF/Z8evCE4hMxqKVJw0I7Ek=", "Upload"="Submit Query", "controller"="photos", "organization_id"="470", "_hq_channel_session"="BAh7CSIYdXNlcl9jcmVkZW50aWFsc19pZGkHIhV1c2VyX2NyZWRlbnRpYWxzIgGAOGRlZDc0NGJlOWU3NTNlNDFlYmVlMDdjMzIzYjA1ZjQxNGE5ZDY4YjNmYjFmNjNkMDQ2OWY2ZDQyOTljZDhiMDFlNmRkMDljNThmMzBmOWJhMTIwNDhkMDI5MTMxYmU5MDczYjIxZmI4YmQxMDVlMTBmNjZmOWFhODE1ZTBjMGM6EF9jc3JmX3Rva2VuIjFxbWJucHdGWThhNUUzWXRTLzRmTVdGL1o4ZXZDRTRoTXhxS1ZKdzBJN0VrPToPc2Vzc2lvbl9pZCIlMjAwMDQ3ZDQ3ZWUyZTgzODIxYzdjOGI3OTdmZGJiMDM=--ac6aa580262938bf5a4d6b9a740722b680eb5d48", "Filedata"=#} [paperclip] Saving attachments. [paperclip] saving /data/HQ_Channel/releases/20100530153454/public/system/photos/9253/original/1.jpg [paperclip] Saving attachments. [paperclip] Saving attachments. Completed in 127ms (View: 2, DB: 91) | 200 OK [http://invent.hqchannel.com/organizations/470/media/galleries/1298/photos?_hq_channel_session=BAh7CSIYdXNlcl9jcmVkZW50aWFsc19pZGkHIhV1c2VyX2NyZWRlbnRpYWxzIgGAOGRlZDc0NGJlOWU3NTNlNDFlYmVlMDdjMzIzYjA1ZjQxNGE5ZDY4YjNmYjFmNjNkMDQ2OWY2ZDQyOTljZDhiMDFlNmRkMDljNThmMzBmOWJhMTIwNDhkMDI5MTMxYmU5MDczYjIxZmI4YmQxMDVlMTBmNjZmOWFhODE1ZTBjMGM6EF9jc3JmX3Rva2VuIjFxbWJucHdGWThhNUUzWXRTLzRmTVdGL1o4ZXZDRTRoTXhxS1ZKdzBJN0VrPToPc2Vzc2lvbl9pZCIlMjAwMDQ3ZDQ3ZWUyZTgzODIxYzdjOGI3OTdmZGJiMDM%3D--ac6aa580262938bf5a4d6b9a740722b680eb5d48&authenticity_token=qmbnpwFY8a5E3YtS%2F4fMWF%2FZ8evCE4hMxqKVJw0I7Ek%3D] And then delayed_jobs keeps spinning around in circles on this one : 2010-06-01T05:09:02-0700: * [Worker(delayed_job host:ip-10-251-197-159 pid:19994)] acquired lock on PhotoJob 2010-06-01T05:09:02-0700: * [JOB] delayed_job host:ip-10-251-197-159 pid:19994 failed with ActiveRecord::RecordNotFound: Couldn't find Photo with ID=9247 - 0 failed attempts 2010-06-01T05:09:02-0700: * [Worker(delayed_job host:ip-10-251-197-159 pid:19994)] acquired lock on PhotoJob 2010-06-01T05:09:02-0700: * [JOB] delayed_job host:ip-10-251-197-159 pid:19994 failed with ActiveRecord::RecordNotFound: Couldn't find Photo with ID=9245 - 0 failed attempts 2010-06-01T05:09:02-0700: * [Worker(delayed_job host:ip-10-251-197-159 pid:19994)] acquired lock on PhotoJob So what I get is that the photos are not being assigned ID's by paperclip. Anyone know where I could poke and pry from here? UPDATE: I created a clone application on a single server. And there are no problems. The images on the cluster do show up (occassionally). If I keep clicking on the folders that lead to photos, it will 50% of the time return a 404 with it not being able to find the photo, and the other half it will present the photo. So the problem has got to be with the server interaction between the ActiveRecord through multiple servers.

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• Cross domain javascript to access localhost. Possible?

  - by Earlz

  Hello, for one reason or another I need for javascript to access a webserver on the localhost. This localhost webserver is under our control so we can have whatever software running in it. How would you do this? I've seen things like YQL but this accesses another domain from the internet. This kind of access causes a lot of problems with firewalls and such. So I want to access the same computer that the browser is running on. How would you do this with javascript and whatever software running on the localhost server? Also, the javascript is being run from an internet site. And the localhost server will not be running on the same port are the internet website is. Is this possible to do? I know about the cross-domain restrictions but I've also seen there are ways around them such as YQL. How does something like YQL work? How would you reimplement it?

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• Updating UI objects in windows forms

  - by P a u l

  Pre .net I was using MFC, ON_UPDATE_COMMAND_UI, and the CCmdUI class to update the state of my windows UI. From the older MFC/Win32 reference: Typically, menu items and toolbar buttons have more than one state. For example, a menu item is grayed (dimmed) if it is unavailable in the present context. Menu items can also be checked or unchecked. A toolbar button can also be disabled if unavailable, or it can be checked. Who updates the state of these items as program conditions change? Logically, if a menu item generates a command that is handled by, say, a document, it makes sense to have the document update the menu item. The document probably contains the information on which the update is based. If a command has multiple user-interface objects (perhaps a menu item and a toolbar button), both are routed to the same handler function. This encapsulates your user-interface update code for all of the equivalent user-interface objects in a single place. The framework provides a convenient interface for automatically updating user-interface objects. You can choose to do the updating in some other way, but the interface provided is efficient and easy to use. What is the guidance for .net Windows Forms? I am using an Application.Idle handler in the main form but am not sure this is the best way to do this. About the time I put all my UI updates in the Idle event handler my app started to show some performance problems, and I don't have the metrics to track this down yet. Not sure if it's related.

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• Smallcaps / multiple fonts and bolding using 'DrawString' in GDI+

  - by Simon_Weaver

  I want to write out some text using smallcaps in combination with different fonts for different words. To clarify I might want the message 'Welcome to our New Website' which is generated into a PNG file for the header of a page. The text will be smallcaps - everything is capitalized but the 'W', 'N' and 'W' are slightly larger. The 'New Website' will be in a different font than the rest of the text. Is there a way i can do this without doing it completely manually? Doing something like this is conceptually what I want to do : graphics.DrawString("<font size=2>W</font>ELCOME TO OUR <b><font size=2>N</font>" + "EW <font size=2>W</font>EBSITE</b>"); The best approach I could find so far is here, but I'm worried that I'll go to all the trouble to do this manually and end up with some horrible kerning or tracking problems. Edit: I should have mentioned that this is being done within ASP.NET so it needs to be fast and as lean as possible. I want it to be automated so I can localize easily and not have to create tonnes of little images.

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• 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.

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• Can JMX operations take interfaces as parameters?

  - by Thor84no

  I'm having problems with an MBean that takes a Map<String, Object> as a parameter. If I try to execute it via JMX using a proxy object, I get an Exception: Caused by: javax.management.ReflectionException at org.jboss.mx.server.AbstractMBeanInvoker.invoke(AbstractMBeanInvoker.java:231) at org.jboss.mx.server.MBeanServerImpl.invoke(MBeanServerImpl.java:668) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) Caused by: java.lang.IllegalArgumentException: Unable to find operation updateProperties(java.util.HashMap) It appears that it attempts to use the actual implementation class rather than the interface, and doesn't check if this is a child of the required interface. The same thing happens for extended classes (for example declare HashMap, pass in LinkedHashMap). Does this mean it's impossible to use an interface for such methods? At the moment I'm getting around it by changing the method signature to accept a HashMap, but it seems odd that I wouldn't be able to use interfaces (or extended classes) in my MBeans. Edit: The proxy object is being created by an in-house utility class called JmxInvocationHandler. The (hopefully) relevant parts of it are as follows: public class JmxInvocationHandler implements InvocationHandler { ... public static <T> T createMBean(final Class<T> iface, SFSTestProperties properties, String mbean, int shHostID) { T newProxyInstance = (T) Proxy.newProxyInstance(iface.getClassLoader(), new Class[] { iface }, (InvocationHandler) new JmxInvocationHandler(properties, mbean, shHostID)); return newProxyInstance; } ... private JmxInvocationHandler(SFSTestProperties properties, String mbean, int shHostID) { this.mbeanName = mbean + MBEAN_SUFFIX + shHostID; msConfig = new MsConfiguration(properties.getHost(0), properties.getMSAdminPort(), properties.getMSUser(), properties.getMSPassword()); } ... public Object invoke(Object proxy, Method method, Object[] args) throws Throwable { if (management == null) { management = ManagementClientStore.getInstance().getManagementClient(msConfig.getHost(), msConfig.getAdminPort(), msConfig.getUser(), msConfig.getPassword(), false); } final Object result = management.methodCall(mbeanName, method.getName(), args == null? new Object[] {} : args); return result; } }

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• Best method to search hierarchical data

  - by WDuffy

  I'm looking at building a facility which allows querying for data with hierarchical filtering. I have a few ideas how I'm going to go about it but was wondering if there are any recommendations or suggestions that might be more efficient. As an example imagine that a user is searching for a job. The job areas would be as follows. 1: Scotland 2: --- West Central 3: ------ Glasgow 4: ------ Etc 5: --- North East 6: ------ Ayrshire 7: ------ Etc A user can search specific (i.e. Glasgow) or in a larger area (i.e. Scotland). The two approaches I am considering are: keep a note of children in the database for each record (i.e. cat 1 would have 2, 3, 4 in its children field) and query against that record with a SELECT * FROM Jobs WHERE Category IN Areas.childrenField. Use a recursive function to find all results who have a relation to the selected area. The problems I see from both are: Holding this data in the db will mean having to keep track of all changes to structure. Recursion is slow and inefficent. Any ideas, suggestion or recommendations on the best approach? I'm using C# ASP.NET with MSSQL 2005 DB.

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• Java ArrayList remove dupes without sets

  - by Kieran

  I'm having problems removing duplicates from an ArrayList. It's for an assignment for college. Here's the code I have already: public int numberOfDiffWords() { ArrayList<String> list = new ArrayList<>(); for(int i=0; i<words.size()-1; i++) { for(int j=i+1; j<words.size(); j++) { if(words.get(i).equals(words.get(j))) { // do nothing } else { list.add(words.get(i)); } } } return list.size(); } The problem is in the numberOfDiffWords() method. The populate list method is working correctly, as my instructor has given me a sample string (containing 4465 words) to analyse - printing words.size() gives the correct result. I want to return the size of the new ArrayList with all duplicates removed. words is an ArrayList class attribute. UPDATE: I should have mentioned I'm only allowed to use dynamic indexed-based storage for this part of the assignment, which means no hash-based storage.

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• How can I get git to work with a remote server?

  - by Adrienne

  I am the CM person for a small company that just started using Git. We have two Git repositories currently hosted on a Windows box that is our all-purpose Windows server. But, we just set up a dedicated server for our CM software on an Ubuntu Linux server named "Callisto". So I created a test Git repository on Callisto. I gave its directory all of the proper permissions recursively. I had the sysadmin create a login for me on Callisto, and I created a key to use for logging in via SSH. I set up my key to use a passphrase; I don't know if that could be contributing to my problems? Anyway, I know my SSH login works because I tested it through puTTY. But, even after hours of trials and head scratching, I can't get my Windows Git bash (mSysGit) to talk to Callisto for the purposes of pushing or pulling Callisto's git repository files. I keep getting "Fatal error. The remote end hung up unexpectedly." And I've even gotten the error that Git doesn't recognize the test repository on Callisto as a git repository. I read online that the "Fatal error...hung up unexpectedly" is usually a problem with the server connection or permissions. So what am I missing or overlooking here? And why doesn't a pull using the git:// protocol work, since that only uses read-only access? Group and public permissions for the git repository's directory on Callisto are set to read and execute, but not write. If anyone could help, I would be so grateful. Thank you.

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• Starting a code library.

  - by Rob Stevenson-Leggett

  Hi, I've been meaning to start a library of reusable code snippets for a while and never seem to get round to it. I think my main problems are: Where to start. What structure should my library take? Should it be a compiled library (where appropriate or just classes I can drop into any project? Or a library project that can be included? In my experience, a built library will quickly become out of date and the source will get lost. So I'm leaning towards source libraries that I can export from SVN and include in any project. Intellectual property. I am employeed, so a lot of the code I write is not my IP. How can I ensure that I don't give my own IP away using it on projects in work and at home? I'm thinking the best way would be to licence my library with an open source licence and make sure I only add to it in my own time using my own equipment and therefore making sure that if I use it in a work project the same rules apply as if I was using a third party library. I write in many different languages and often would require two or more parts of this library. Should I look at implementing a few template projects and a core project for each of my chosen reusable components and languages? Has anyone else got this sort of library and how do you organise and update it?

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• Scala path dependent return type from parameter

  - by Rich Oliver

  In the following code using 2.10.0M3 in Eclipse plugin 2.1.0 for 2.10M3. I'm using the default setting which is targeting JVM 1.5 class GeomBase[T <: DTypes] { abstract class NewObjs { def newHex(gridR: GridBase, coodI: Cood): gridR.HexRT } class GridBase { selfGrid => type HexRT = HexG with T#HexTr def uniformRect (init: NewObjs) { val hexCood = Cood(2 ,2) val hex: HexRT = init.newHex(selfGrid, hexCood)// won't compile } } } Error message: Description Resource Path Location Type type mismatch; found: GeomBase.this.GridBase#HexG with T#HexTr required: GridBase.this.HexRT (which expands to) GridBase.this.HexG with T#HexTr GeomBase.scala Why does the compiler think the method returns the type projection GridBase#HexG when it should be this specific instance of GridBase? Edit transferred to a simpler code class in responce to comments now getting a different error message. package rStrat class TestClass { abstract class NewObjs { def newHex(gridR: GridBase): gridR.HexG } class GridBase { selfGrid => def uniformRect (init: NewObjs) { val hex: HexG = init.newHex(this) //error here } class HexG { val test12 = 5 } } } . Error line 11:Description Resource Path Location Type type mismatch; found : gridR.HexG required: GridBase.this.HexG possible cause: missing arguments for method or constructor TestClass.scala /SStrat/src/rStrat line 11 Scala Problem Update I've switched to 2.10.0M4 and updated the plug-in to the M4 version on a fresh version of Eclipse and switched to JVM 1.6 (and 1.7) but the problems are unchanged.

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