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  • Dust prevention for home servers [closed]

    - by Payson Welch
    I found some posts on here about dealing with dust relating to servers but nothing that specifically addressed my question. I have several servers at home for research and as you can probably guess they are not cheap. It is impossible for me to remove 100% of the dust from my home as much as I may try. Does anyone know of any practical solutions to filtering the air that will go into the servers? For instance maybe place some sort of material over the bezel to catch dust particles before they enter? I realize the ideal home solution would be to have a small room with environmental controls but I'm not there yet. Thanks!

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  • VoIP and IPv6 with IPsec

    - by PhilCisco
    Hi, I had some basic questions about VoIP in a IPv6 architecture, right now I'm running VoIP in a v4 architecture, and I was thinking about to change everything to v6. my questions are not that practical but I would like to understand it well. Question 1: if i had internet full v6 or v4 and that I enable IPsec on my v6 router do I still need a VPN through the internet ? because my routers will anyway exchange their pub/priv key or their certificate to ensure the communication. Question 2: If the answer to question 1 is yes then I only have two advantages to put my VoIP architecture to IPv6 the second advantage for me is the NAT which I will not have anymore. I know that right now I should anyway still use things like NAT-PT, Tunnelling and so one but in full v6 are their any other advantages ? Thank you

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  • Encrypting absolutely everything, even within the LAN

    - by chris_l
    Has anybody tried that approach already? I'm really considering it: Instead of relying on network based IDS etc., every packet must use encryption which was initiated by a certificate issued by my own CA. Every client gets a unique client certificate Every server gets a unique server certificate Every service additionally requires to login. Both SSL and SSH would be ok. Access to the internet would be done via an SSL tunnel to the gateway. Is it feasible? Does it create practical problems? How could it be done and enforced? What do you think?

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  • RDP - Sharing shortcuts and/or toolbars

    - by Joe
    I often have to work across several virtual machines through RDP. I used to work with Terminals, and recently changed to mRemote NG. As of now, I have a checklist that I run on each new VM I create, in order to populate the desktop with the shortcuts and apps that I use regularly. Then, I create a checkpoint and use that when I need to revert to a "clean" machine. However, it's not always practical, and the VMs I have to use are not always created by me so that checkpoint is not always available. I know that I could use a template when creating the VM, but it doesn't solve the problem when I have to use VMs that I do not own. Does anyone know of a way to setup one set of shortcuts/apps and be able to launch them on a remote desktop connection easily? Kind of like a toolbar that is present wherever I'm logged on...

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  • Tweaking "Most visited sites" button in Firefox

    - by Mehper C. Palavuzlar
    It is sometimes practical to use "Most Visited" sites which stands on the left hand side of Firefox window. When I click on it, I can see maximum 10 URLs. At that point, I have 2 questions: Is it possible to increase the number of maximum most visited sites (say, 30)? Let's say example.com is one of the most visited domains. In the most visited list, there are other pages from this domain, like example.com/intro, example.com/info, example.com/help etc. So those sub-addresses are also in the list, but I just want to see max 1 (or maybe 2) pages from the same domain in the list. Is it possible to arrange the list this way?

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  • Difference between two ways of installing tomcat as a service (Linux)

    - by varesa
    I am installing tomcat on a linux server, and would want it to be available as a service. I have found two different ways to achieve this. The first one is to copy the daemon.sh from $CATALINA_HOME/bin to /etc/init.d, and the other one I have seen is to create a simple init script that class $CATALINA_HOME/bin/startup.sh, etc. Startup.sh calls catalina.sh. The contents of the daemon.sh and startup.sh look very similar (at least for the env variables, and stuff like that). Daemon.sh calls jsvc in the end. Catalina.sh calls java. What is the (practical) difference between using the two of these when setting up tomcat as a service?

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  • Open table cache in MySQL

    - by vvanscherpenseel
    I have my open table cache set to 1800 and I have a total of 1112 tables. MySQL Tuning Primer reports that 100% of my table cache is used yet my table cache hit rate is 5%. I understand that this happens due to concurrent connections all opening tables. I think I should raise the cache limit. I understand that the cache size is limited by the file descriptor limit of my operating system, but are there any other practical limitations I should be aware of? Searching Google or this very website yields mostly posts explaining the connection-factor or come up with indecisive answers. My question: can I safely increase the open table cache limit? Is there a maximum?

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  • How can I fully automate the creation and configuration of a SharePoint virtual machine?

    - by vnat
    I typically require multiple SharePoint virtual machines for development purposes. I currently manually build these every time I need one, either starting from a fresh OS install or using sysprep when working with SharePoint 2010 and SQL Server 2008 R2. I currently use VMWare, but am open to VirtualBox or Hyper-V. I'd like to be able to go from zero to a working VM with SharePoint, SQL and Visual Studio all through script. Is this a feasible task? Or are there more practical methods which would start from a VM with a fresh installation of an OS, and then use more standard unattended installs. Although general, I'd like to know which direction to focus my efforts. Thanks in advance, vnat

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  • Best practices for FQDN for standalone domain (is a two part domain.tld okay?)

    - by birchbark
    I've searched quite a bit and can't seem to find a straight, modern answer on this. If I am hosting a domain, say, mydomain.com, on a machine which is going to solely be used for that domain, and there are no subdomains, is there a real, practical reason besides compliance to create an arbitrary hostname (i.e. myhost) just in order to have a three-part FQDN (myhost.mydomain.com) to satisfy some sort of RFC or convention that's expected. This seems to make a lot of undue complexities from my perspective, and I'm not sure if there's an advantage to this or if it's just a hold-over from a time where all web resources came from a subdomains such as www and ftp which may need to scale to separate machines. I don't use www on my domain, either, which is ill-advised for all I know from an administrators perspective (though removing it is the norm from a designer's perspective)...

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  • mirror sql server 2008 to AWS instance from our datacenter?

    - by Alex
    We are currenlty running on hosted pos system locally and would like to mirror to AWS. We are new to AWS and would like to know the most cost effective way to do this? We have 2 DB and 2 web servers right now in one cabinet in CA. One tape drive, one firewall, one SNA. We are thinking to replicate our system in AWS (using sql server 2008) and just mirror both systems and use a witness server between them to keep the data in sync? The goal is, if CA datacenter goes down, AWS keeps running. User see no downtime. All data is synced. Is anyone doing something similar? Would this be practical to just use AWS in this fashion? Thanks

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  • One (or at most two) click listen to sound file

    - by Isaac Rabinovitch
    On my Windows 7 system, I have a bunch of very short sound files. From their names, I have a general notion what they contain, but I need to listen to the most likely files to find out if they meet my purpose. Ideally, I'd like to be able to listen to a file just by clicking on it in Windows explorer. Probably not practical, so I'd like a very simple audio file player that I can associate with the file type. When I double-click on the file, the player plays the file, then closes imediately.

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  • How to run script from root as another user (with user PATH)

    - by Sandra
    I would like to have these commands run as the ss user from root mkdir bin cp -r /opt/gitolite . gitolite/install -ln gitolite setup -pk ss.pub mkdir -p .gitolite/hooks/common ln -s /opt/pre-receive .gitolite/hooks/common/ so everything is executed in /home/ss. The 4th line requires $HOME/bin as you can see from the 3rd line. The only way I can get it to work is by adding su -c "command" ss to each line, which is not a nice hack. This is an extension to my previous question, where I wasn't precise enough. Question How do I run all these commands as a script in a practical way?

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  • How to configure a GridView CommandField to trigger Full Page Update in UpdatePanel

    - by Frinavale
    I have 2 user controls on my page. One is used for searching, and the other is used for editing (along with a few other things). The user control that provides the search functionality uses a GridView to display the search results. This GridView has a CommandField used for editing (showEditButton="true"). I would like to place the GridView into an UpdatePanel so that paging through the search results will be smooth. The thing is that when the user clicks the Edit Link (the CommandField) I need to preform a full page postback so that the search user control can be hidden and the edit user control can be displayed. Edit: the reason I need to do a full page postback is because the edit user control is outside of the UpdatePanel that my GridView is in. It is not only outside the UpdatePanel, but it's in a completely different user control. I have no idea how to add the CommandField as a full page postback trigger to the UpdatePanel. The PostBackTrigger (which is used to indicate the controls cause a full page postback) takes a ControlID as a parameter; however the CommandButton does not have an ID...and you can see why I'm having a problem with this. Update on what else I've tried to solve the problem: I took a new approach to solving the problem. In my new approach, I used a TemplateField instead of a CommandField. I placed a LinkButton control in the TemplateField and gave it a name. During the GridView's RowDataBound event I retrieved the LinkButton control and added it to the UpdatePanel's Triggers. This is the ASP Markup for the UpdatePanel and the GridView <asp:UpdatePanel ID="SearchResultsUpdateSection" runat="server"> <ContentTemplate> <asp:GridView ID="SearchResultsGrid" runat="server" AllowPaging="true" AutoGenerateColumns="false"> <Columns> <asp:TemplateField> <HeaderTemplate></HeaderTemplate> <ItemTemplate> <asp:LinkButton ID="Edit" runat="server" Text="Edit"></asp:LinkButton> </ItemTemplate> </asp:TemplateField> <asp:BoundField ...... </Columns> </asp:GridView> </ContentTemplate> </asp:UpdatePanel> In my VB.NET code. I implemented a function that handles the GridView's RowDataBound event. In this method I find the LinkButton for the row being bound to, create a PostBackTrigger for the LinkButton, and add it to the UpdatePanel's Triggers. This means that a PostBackTrigger is created for every "edit" LinkButton in the GridView Edit: this did not create a PostBackTrigger for Every "edit" LinkButton because the ID is the same for all LinkButtons in the GridView. Private Sub SearchResultsGrid_RowDataBound(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.GridViewRowEventArgs) Handles SearchResultsGrod.RowDataBound If e.Row.RowType = DataControlRowType.Header Then ''I am doing stuff here that does not pertain to the problem Else Dim editLink As LinkButton = CType(e.Row.FindControl("Edit"), LinkButton) If editLink IsNot Nothing Then Dim fullPageTrigger As New PostBackTrigger fullPageTrigger.ControlID = editLink.ID SearchResultsUpdateSection.Triggers.Add(fullPageTrigger) End If End If End Sub And instead of handling the GridView's RowEditing event for editing purposes i use the RowCommand instead. Private Sub SearchResultsGrid_RowCommand(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.GridViewCommandEventArgs) Handles SearchResultsGrid.RowCommand RaiseEvent EditRecord(Me, New EventArgs()) End Sub This new approach didn't work at all because all of the LinkButtons in the GridView have the same ID. After reading the MSDN article on the UpdatePanel.Triggers Property I have the impression that Triggers can only be defined declaratively. This would mean that anything I did in the VB code wouldn't work. Any advise would be greatly appreciated. Thanks, -Frinny

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  • Sharing the model in MVP Winforms App

    - by Keith G
    I'm working on building up an MVP application (C# Winforms). My initial version is at http://stackoverflow.com/questions/1422343/ ... Now I'm increasing the complexity. I've broken out the code to handle two separate text fields into two view/presenter pairs. It's a trivial example, but it's to work out the details of multiple presenters sharing the same model. My questions are about the model: I am basically using a property changed event raised by the model for notifying views that something has changed. Is that a good approach? What if it gets to the point where I have 100 or 1000 properties? Is it still practical at that point? Is instantiating the model in each presenter with   NoteModel _model = NoteModel.Instance   the correct approach? Note that I do want to make sure all of the presenters are sharing the same data. If there is a better approach, I'm open to suggestions .... My code looks like this: NoteModel.cs public class NoteModel : INotifyPropertyChanged { private static NoteModel _instance = null; public static NoteModel Instance { get { return _instance; } } static NoteModel() { _instance = new NoteModel(); } private NoteModel() { Initialize(); } public string Filename { get; set; } public bool IsDirty { get; set; } public readonly string DefaultName = "Untitled.txt"; string _sText; public string TheText { get { return _sText; } set { _sText = value; PropertyHasChanged("TheText"); } } string _sMoreText; public string MoreText { get { return _sMoreText; } set { _sMoreText = value; PropertyHasChanged("MoreText"); } } public void Initialize() { Filename = DefaultName; TheText = String.Empty; MoreText = String.Empty; IsDirty = false; } private void PropertyHasChanged(string sPropName) { IsDirty = true; if (PropertyChanged != null) { PropertyChanged(this, new PropertyChangedEventArgs(sPropName)); } } public event PropertyChangedEventHandler PropertyChanged; } TextEditorPresenter.cs public class TextEditorPresenter { ITextEditorView _view; NoteModel _model = NoteModel.Instance; public TextEditorPresenter(ITextEditorView view)//, NoteModel model) { //_model = model; _view = view; _model.PropertyChanged += new PropertyChangedEventHandler(model_PropertyChanged); } void model_PropertyChanged(object sender, PropertyChangedEventArgs e) { if (e.PropertyName == "TheText") _view.TheText = _model.TheText; } public void TextModified() { _model.TheText = _view.TheText; } public void ClearView() { _view.TheText = String.Empty; } } TextEditor2Presenter.cs is essentially the same except it operates on _model.MoreText instead of _model.TheText. ITextEditorView.cs public interface ITextEditorView { string TheText { get; set; } } ITextEditor2View.cs public interface ITextEditor2View { string MoreText { get; set; } }

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  • Simple show/hide jQuery troubles

    - by Banderdash
    Okay, I feel like a bit of a 800 pound gorilla trying to thread a needle when it comes to jQuery. I need a script that will preform a simple show/hide (preferably with a nice sliding in and out) on a list. My markup looks like this: <div id="themes"> <h2>Research Themes</h2> <ul> <li class="tier_1"><a href="">Learn about our approach to the <strong>environment</strong></a> <ul class="tier_2 hide"> <li><a href=""><em>How we are tying this all together</em></a></li> <li><a href=""><strong>Project:</strong> Solor Powered Biofactories</a></li> <li><a href=""><strong>Project:</strong> Cleaning Water with Nature</a></li> <li><a href=""><strong>Project:</strong> Higher Efficiency Solar Technology</a></li> </ul> </li> <li class="tier_1"><a href="">Learn about our approach to <strong>human health</strong></a> <ul class="tier_2 hide"> <li><a href="">Project name numero uno goes here</a></li> <li><a href="">Project name numero dos goes here</a></li> <li><a href="">Project name numero tres goes here</a></li> </ul> </li> <li class="tier_1"><a href="">Learn about our approach to <strong>national defense</strong></a> <ul class="tier_2 hide"> <li><a href="">Project name numero uno goes here</a></li> <li><a href="">Project name numero dos goes here</a></li> <li><a href="">Project name numero tres goes here</a></li> </ul> </li> </ul> </div><!-- // end themes --> You can see that each nested ul has a class of "tier_2" and "hide". Ideally when the li they are nested within ("li.tier_1") is clicked it's child ul will have the hide class removed and the li's contained within will slideout, but at the same time should check all the other ul.tier_2's and be sure they get a hide class--so only one theme can be expanded at a time. I set up a sandbox to try some things: http://jsbin.com/odete/3 My JS looks like this: $(function(){ $(".tier_1 a").each(function(i,o){ $(this).click(function(e){ e.preventDefault(); $(this).addClass("show").siblings("ul").removeClass("show"); $("ul.tier_2:eq("+i+")").show().siblings("ul.tier_2").hide(); }); }); }); Totally a dumb way to do this, I am sure. But I based it off another script and it does work "a little bit" as you can see in the sandbox. If one of you mean hands at jQuery might be so inclined to take a peek I'd be very grateful. If you could also advise on how to have the transitions slideIn and Out that would also be fantastic!

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  • Mysql - Help me change this single complex query to use temporary tables

    - by sandeepan-nath
    About the system: - There are tutors who create classes and packs - A tags based search approach is being followed.Tag relations are created when new tutors register and when tutors create packs (this makes tutors and packs searcheable). For details please check the section How tags work in this system? below. Following is the concerned query Can anybody help me suggest an approach using temporary tables. We have indexed all the relevant fields and it looks like this is the least time possible with this approach:- SELECT SUM(DISTINCT( t.tag LIKE "%Dictatorship%" OR tt.tag LIKE "%Dictatorship%" OR ttt.tag LIKE "%Dictatorship%" )) AS key_1_total_matches , SUM(DISTINCT( t.tag LIKE "%democracy%" OR tt.tag LIKE "%democracy%" OR ttt.tag LIKE "%democracy%" )) AS key_2_total_matches , COUNT(DISTINCT( od.id_od )) AS tutor_popularity, CASE WHEN ( IF(( wc.id_wc > 0 ), ( wc.wc_api_status = 1 AND wc.wc_type = 0 AND wc.class_date > '2010-06-01 22:00:56' AND wccp.status = 1 AND ( wccp.country_code = 'IE' OR wccp.country_code IN ( 'INT' ) ) ), 0) ) THEN 1 ELSE 0 END AS 'classes_published' , CASE WHEN ( IF(( lp.id_lp > 0 ), ( lp.id_status = 1 AND lp.published = 1 AND lpcp.status = 1 AND ( lpcp.country_code = 'IE' OR lpcp.country_code IN ( 'INT' ) ) ), 0) ) THEN 1 ELSE 0 END AS 'packs_published', td . *, u . * FROM tutor_details AS td JOIN users AS u ON u.id_user = td.id_user LEFT JOIN learning_packs_tag_relations AS lptagrels ON td.id_tutor = lptagrels.id_tutor LEFT JOIN learning_packs AS lp ON lptagrels.id_lp = lp.id_lp LEFT JOIN learning_packs_categories AS lpc ON lpc.id_lp_cat = lp.id_lp_cat LEFT JOIN learning_packs_categories AS lpcp ON lpcp.id_lp_cat = lpc.id_parent LEFT JOIN learning_pack_content AS lpct ON ( lp.id_lp = lpct.id_lp ) LEFT JOIN webclasses_tag_relations AS wtagrels ON td.id_tutor = wtagrels.id_tutor LEFT JOIN webclasses AS wc ON wtagrels.id_wc = wc.id_wc LEFT JOIN learning_packs_categories AS wcc ON wcc.id_lp_cat = wc.id_wp_cat LEFT JOIN learning_packs_categories AS wccp ON wccp.id_lp_cat = wcc.id_parent LEFT JOIN order_details AS od ON td.id_tutor = od.id_author LEFT JOIN orders AS o ON od.id_order = o.id_order LEFT JOIN tutors_tag_relations AS ttagrels ON td.id_tutor = ttagrels.id_tutor LEFT JOIN tags AS t ON t.id_tag = ttagrels.id_tag LEFT JOIN tags AS tt ON tt.id_tag = lptagrels.id_tag LEFT JOIN tags AS ttt ON ttt.id_tag = wtagrels.id_tag WHERE ( u.country = 'IE' OR u.country IN ( 'INT' ) ) AND CASE WHEN ( ( tt.id_tag = lptagrels.id_tag ) AND ( lp.id_lp > 0 ) ) THEN lp.id_status = 1 AND lp.published = 1 AND lpcp.status = 1 AND ( lpcp.country_code = 'IE' OR lpcp.country_code IN ( 'INT' ) ) ELSE 1 END AND CASE WHEN ( ( ttt.id_tag = wtagrels.id_tag ) AND ( wc.id_wc > 0 ) ) THEN wc.wc_api_status = 1 AND wc.wc_type = 0 AND wc.class_date > '2010-06-01 22:00:56' AND wccp.status = 1 AND ( wccp.country_code = 'IE' OR wccp.country_code IN ( 'INT' ) ) ELSE 1 END AND CASE WHEN ( od.id_od > 0 ) THEN od.id_author = td.id_tutor AND o.order_status = 'paid' AND CASE WHEN ( od.id_wc > 0 ) THEN od.can_attend_class = 1 ELSE 1 END ELSE 1 END AND ( t.tag LIKE "%Dictatorship%" OR t.tag LIKE "%democracy%" OR tt.tag LIKE "%Dictatorship%" OR tt.tag LIKE "%democracy%" OR ttt.tag LIKE "%Dictatorship%" OR ttt.tag LIKE "%democracy%" ) GROUP BY td.id_tutor HAVING key_1_total_matches = 1 AND key_2_total_matches = 1 ORDER BY tutor_popularity DESC, u.surname ASC, u.name ASC LIMIT 0, 20 The problem The results returned by the above query are correct (AND logic working as per expectation), but the time taken by the query rises alarmingly for heavier data and for the current data I have it is like 10 seconds as against normal query timings of the order of 0.005 - 0.0002 seconds, which makes it totally unusable. Somebody suggested in my previous question to do the following:- create a temporary table and insert here all relevant data that might end up in the final result set run several updates on this table, joining the required tables one at a time instead of all of them at the same time finally perform a query on this temporary table to extract the end result All this was done in a stored procedure, the end result has passed unit tests, and is blazing fast. I have never worked with temporary tables till now. Only if I could get some hints, kind of schematic representations so that I can start with... Is there something faulty with the query? What can be the reason behind 10+ seconds of execution time? How tags work in this system? When a tutor registers, tags are entered and tag relations are created with respect to tutor's details like name, surname etc. When a Tutors create packs, again tags are entered and tag relations are created with respect to pack's details like pack name, description etc. tag relations for tutors stored in tutors_tag_relations and those for packs stored in learning_packs_tag_relations. All individual tags are stored in tags table. The explain query output:- Please see this screenshot - http://www.test.examvillage.com/Explain_query_improved.jpg

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  • Servlet/JSP Flow Control: Enums, Exceptions, or Something Else?

    - by Christopher Parker
    I recently inherited an application developed with bare servlets and JSPs (i.e.: no frameworks). I've been tasked with cleaning up the error-handling workflow. Currently, each <form> in the workflow submits to a servlet, and based on the result of the form submission, the servlet does one of two things: If everything is OK, the servlet either forwards or redirects to the next page in the workflow. If there's a problem, such as an invalid username or password, the servlet forwards to a page specific to the problem condition. For example, there are pages such as AccountDisabled.jsp, AccountExpired.jsp, AuthenticationFailed.jsp, SecurityQuestionIncorrect.jsp, etc. I need to redesign this system to centralize how problem conditions are handled. So far, I've considered two possible solutions: Exceptions Create an exception class specific to my needs, such as AuthException. Inherit from this class to be more specific when necessary (e.g.: InvalidUsernameException, InvalidPasswordException, AccountDisabledException, etc.). Whenever there's a problem condition, throw an exception specific to the condition. Catch all exceptions via web.xml and route them to the appropriate page(s) with the <error-page> tag. enums Adopt an error code approach, with an enum keeping track of the error code and description. The descriptions can be read from a resource bundle in the finished product. I'm leaning more toward the enum approach, as an authentication failure isn't really an "exceptional condition" and I don't see any benefit in adding clutter to the server logs. Plus, I'd just be replacing one maintenance headache with another. Instead of separate JSPs to maintain, I'd have separate Exception classes. I'm planning on implementing "error" handling in a servlet that I'm writing specifically for this purpose. I'm also going to eliminate all of the separate error pages, instead setting an error request attribute with the error message to display to the user and forwarding back to the referrer. Each target servlet (Logon, ChangePassword, AnswerProfileQuestions, etc.) would add an error code to the request and redirect to my new servlet in the event of a problem. My new servlet would look something like this: public enum Error { INVALID_PASSWORD(5000, "You have entered an invalid password."), ACCOUNT_DISABLED(5002, "Your account has been disabled."), SESSION_EXPIRED(5003, "Your session has expired. Please log in again."), INVALID_SECURITY_QUESTION(5004, "You have answered a security question incorrectly."); private final int code; private final String description; Error(int code, String description) { this.code = code; this.description = description; } public int getCode() { return code; } public String getDescription() { return description; } }; protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String sendTo = "UnknownError.jsp"; String message = "An unknown error has occurred."; int errorCode = Integer.parseInt((String)request.getAttribute("errorCode"), 10); Error errors[] = Error.values(); Error error = null; for (int i = 0; error == null && i < errors.length; i++) { if (errors[i].getCode() == errorCode) { error = errors[i]; } } if (error != null) { sendTo = request.getHeader("referer"); message = error.getDescription(); } request.setAttribute("error", message); request.getRequestDispatcher(sendTo).forward(request, response); } protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } Being fairly inexperienced with Java EE (this is my first real exposure to JSPs and servlets), I'm sure there's something I'm missing, or my approach is suboptimal. Am I on the right track, or do I need to rethink my strategy?

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  • jQuery Hover functions

    - by Banderdash
    Thus far you guys have been wildly helpful with me getting this little ditty working just so. I have one further request: This markup: <div id="themes"> <h2>Research Themes</h2> <ul> <li class="tier_1"><a class="enviro" href="">Learn about our approach to the <strong>environment</strong></a> <ul class="tier_2 hide"> <li><a href=""><em>How we are tying this all together</em></a></li> <li><a href="off.html"><strong>Project:</strong> Solor Powered Biofactories</a></li> <li><a href=""><strong>Project:</strong> Cleaning Water with Nature</a></li> <li><a href=""><strong>Project:</strong> Higher Efficiency Solar Technology</a></li> </ul> </li> <li class="tier_1"><a class="health" href="">Learn about our approach to <strong>human health</strong></a> <ul class="tier_2 hide"> <li><a href="">Project name numero uno goes here</a></li> <li><a href="">Project name numero dos goes here</a></li> <li><a href="">Project name numero tres goes here</a></li> </ul> </li> <li class="tier_1"><a class="defense" href="">Learn about our approach to <strong>national defense</strong></a> <ul class="tier_2 hide"> <li><a href="">Project name numero uno goes here</a></li> <li><a href="">Project name numero dos goes here</a></li> <li><a href="">Project name numero tres goes here</a></li> </ul> </li> </ul> </div><!-- // end themes --> And this jQuery: $(function(){ $(".tier_1 > a").hover(function() { var currentList = jQuery(this).parents('li').find('.tier_2'); $(currentList).slideToggle(); jQuery(this).parents('ul').find('.tier_2').not(currentList).slideUp(); return false; }); }); Create this nifty 'themes' slider you can see working on the right column of this page: http://clients.pixelbleed.net/biodesign/ I have two problems with it...The hover retracts the slideUp/down when you hit one of the links under a tier_2 ul. I'd like it to remain slideout as someone hovers the nested li's. So the slide should only happen on hover for the tier_1 elements. Also I would like, on hover to add an "active" class to the a element on the tier_1 links. So [a class="enviro"..] would, on hover, become [a class="enviro active"]. This is then removed when one of the other tier_1 items is hovered. This way the pretty color icon can stay visible while someone looks at the nested elements. Not even sure all that is possible with hover, but I figured if anyone would know a way it would be here.

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  • A format for storing personal contacts in a database

    - by Gart
    I'm thinking of the best way to store personal contacts in a database for a business application. The traditional and straightforward approach would be to create a table with columns for each element, i.e. Name, Telephone Number, Job title, Address, etc... However, there are known industry standards for this kind of data, like for example vCard, or hCard, or vCard-RDF/XML or even Windows Contacts XML Schema. Utilizing an standard format would offer some benefits, like inter-operablilty with other systems. But how can I decide which method to use? The requirements are mainly to store the data. Search and ordering queries are highly unlikely but possible. The volume of the data is 100,000 records at maximum. My database engine supports native XML columns. I have been thinking to use some XML-based format to store the personal contacts. Then it will be possible to utilize XML indexes on this data, if searching and ordering is needed. Is this a good approach? Which contacts format and schema would you recommend for this? Edited after first answers Here is why I think the straightforward approach is bad. This is due to the nature of this kind of data - it is not that simple. The personal contacts it is not well-structured data, it may be called semi-structured. Each contact may have different data fields, maybe even such fields which I cannot anticipate. In my opinion, each piece of this data should be treated as important information, i.e. no piece of data could be discarded just because there was no relevant column in the database. If we took it further, assuming that no data may be lost, then we could create a big text column named Comment or Description or Other and put there everything which cannot be fitted well into table columns. But then again - the data would lose structure - this might be bad. If we wanted structured data then - according to the database design principles - the data should be decomposed into entities, and relations should be established between the entities. But this adds complexity - there are just too many entities, and lots of design desicions should be made, like "How do we store Address? Personal Name? Phone number? How do we encode home phone numbers and mobile phone numbers? How about other contact info?.." The relations between entities are complex and multiple, and each relation is a table in the database. Each relation needs to be documented in the design papers. That is a lot of work to do. But it is possible to avoid the complexity entirely - just document that the data is stored according to such and such standard schema, period. Then anybody who would be reading that document should easily understand what it was all about. Finally, this is all about using an industry standard. The standard is, hopefully, designed by some clever people who anticipated and described the structure of personal contacts information much better than I ever could. Why should we all reinvent the wheel?? It's much easier to use a standard schema. The problem is, there are just too many standards - it's not easy to decide which one to use!

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  • Hover function for accordion

    - by Banderdash
    Thus far you guys have been wildly helpful with me getting this little ditty working just so. I have one further request: This markup: <div id="themes"> <h2>Research Themes</h2> <ul> <li class="tier_1"><a class="enviro" href="">Learn about our approach to the <strong>environment</strong></a> <ul class="tier_2 hide"> <li><a href=""><em>How we are tying this all together</em></a></li> <li><a href="off.html"><strong>Project:</strong> Solor Powered Biofactories</a></li> <li><a href=""><strong>Project:</strong> Cleaning Water with Nature</a></li> <li><a href=""><strong>Project:</strong> Higher Efficiency Solar Technology</a></li> </ul> </li> <li class="tier_1"><a class="health" href="">Learn about our approach to <strong>human health</strong></a> <ul class="tier_2 hide"> <li><a href="">Project name numero uno goes here</a></li> <li><a href="">Project name numero dos goes here</a></li> <li><a href="">Project name numero tres goes here</a></li> </ul> </li> <li class="tier_1"><a class="defense" href="">Learn about our approach to <strong>national defense</strong></a> <ul class="tier_2 hide"> <li><a href="">Project name numero uno goes here</a></li> <li><a href="">Project name numero dos goes here</a></li> <li><a href="">Project name numero tres goes here</a></li> </ul> </li> </ul> </div><!-- // end themes --> And this jQuery: $(function(){ $(".tier_1 > a").hover(function() { var currentList = jQuery(this).parents('li').find('.tier_2'); $(currentList).slideToggle(); jQuery(this).parents('ul').find('.tier_2').not(currentList).slideUp(); return false; }); }); Create this nifty 'themes' slider you can see working on the right column of this page: http://clients.pixelbleed.net/biodesign/ I have two problems with it...The hover retracts the slideUp/down when you hit one of the links under a tier_2 ul. I'd like it to remain slideout as someone hovers the nested li's. So the slide should only happen on hover for the tier_1 elements. Also I would like, on hover to add an "active" class to the a element on the tier_1 links. So [a class="enviro"..] would, on hover, become [a class="enviro active"]. This is then removed when one of the other tier_1 items is hovered. This way the pretty color icon can stay visible while someone looks at the nested elements. Not even sure all that is possible with hover, but I figured if anyone would know a way it would be here.

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  • Domain Validation in a CQRS architecture

    - by Jupaol
    Basically I want to know if there is a better way to validate my domain entities. This is how I am planning to do it but I would like your opinion The first approach I considered was: class Customer : EntityBase<Customer> { public void ChangeEmail(string email) { if(string.IsNullOrWhitespace(email)) throw new DomainException(“...”); if(!email.IsEmail()) throw new DomainException(); if(email.Contains(“@mailinator.com”)) throw new DomainException(); } } I actually do not like this validation because even when I am encapsulating the validation logic in the correct entity, this is violating the Open/Close principle (Open for extension but Close for modification) and I have found that violating this principle, code maintenance becomes a real pain when the application grows up in complexity. Why? Because domain rules change more often than we would like to admit, and if the rules are hidden and embedded in an entity like this, they are hard to test, hard to read, hard to maintain but the real reason why I do not like this approach is: if the validation rules change, I have to come and edit my domain entity. This has been a really simple example but in RL the validation could be more complex So following the philosophy of Udi Dahan, making roles explicit, and the recommendation from Eric Evans in the blue book, the next try was to implement the specification pattern, something like this class EmailDomainIsAllowedSpecification : IDomainSpecification<Customer> { private INotAllowedEmailDomainsResolver invalidEmailDomainsResolver; public bool IsSatisfiedBy(Customer customer) { return !this.invalidEmailDomainsResolver.GetInvalidEmailDomains().Contains(customer.Email); } } But then I realize that in order to follow this approach I had to mutate my entities first in order to pass the value being valdiated, in this case the email, but mutating them would cause my domain events being fired which I wouldn’t like to happen until the new email is valid So after considering these approaches, I came out with this one, since I am going to implement a CQRS architecture: class EmailDomainIsAllowedValidator : IDomainInvariantValidator<Customer, ChangeEmailCommand> { public void IsValid(Customer entity, ChangeEmailCommand command) { if(!command.Email.HasValidDomain()) throw new DomainException(“...”); } } Well that’s the main idea, the entity is passed to the validator in case we need some value from the entity to perform the validation, the command contains the data coming from the user and since the validators are considered injectable objects they could have external dependencies injected if the validation requires it. Now the dilemma, I am happy with a design like this because my validation is encapsulated in individual objects which brings many advantages: easy unit test, easy to maintain, domain invariants are explicitly expressed using the Ubiquitous Language, easy to extend, validation logic is centralized and validators can be used together to enforce complex domain rules. And even when I know I am placing the validation of my entities outside of them (You could argue a code smell - Anemic Domain) but I think the trade-off is acceptable But there is one thing that I have not figured out how to implement it in a clean way. How should I use this components... Since they will be injected, they won’t fit naturally inside my domain entities, so basically I see two options: Pass the validators to each method of my entity Validate my objects externally (from the command handler) I am not happy with the option 1 so I would explain how I would do it with the option 2 class ChangeEmailCommandHandler : ICommandHandler<ChangeEmailCommand> { public void Execute(ChangeEmailCommand command) { private IEnumerable<IDomainInvariantValidator> validators; // here I would get the validators required for this command injected, and in here I would validate them, something like this using (var t = this.unitOfWork.BeginTransaction()) { var customer = this.unitOfWork.Get<Customer>(command.CustomerId); this.validators.ForEach(x =. x.IsValid(customer, command)); // here I know the command is valid // the call to ChangeEmail will fire domain events as needed customer.ChangeEmail(command.Email); t.Commit(); } } } Well this is it. Can you give me your thoughts about this or share your experiences with Domain entities validation EDIT I think it is not clear from my question, but the real problem is: Hiding the domain rules has serious implications in the future maintainability of the application, and also domain rules change often during the life-cycle of the app. Hence implementing them with this in mind would let us extend them easily. Now imagine in the future a rules engine is implemented, if the rules are encapsulated outside of the domain entities, this change would be easier to implement

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  • Rx IObservable buffering to smooth out bursts of events

    - by Dan
    I have an Observable sequence that produces events in rapid bursts (ie: five events one right after another, then a long delay, then another quick burst of events, etc.). I want to smooth out these bursts by inserting a short delay between events. Imagine the following diagram as an example: Raw: --oooo--------------ooooo-----oo----------------ooo| Buffered: --o--o--o--o--------o--o--o--o--o--o--o---------o--o--o| My current approach is to generate a metronome-like timer via Observable.Interval() that signals when it's ok to pull another event from the raw stream. The problem is that I can't figure out how to then combine that timer with my raw unbuffered observable sequence. IObservable.Zip() is close to doing what I want, but it only works so long as the raw stream is producing events faster than the timer. As soon as there is a significant lull in the raw stream, the timer builds up a series of unwanted events that then immediately pair up with the next burst of events from the raw stream. Ideally, I want an IObservable extension method with the following function signature that produces the bevaior I've outlined above. Now, come to my rescue StackOverflow :) public static IObservable<T> Buffered(this IObservable<T> src, TimeSpan minDelay) PS. I'm brand new to Rx, so my apologies if this is a trivially simple question... 1. Simple yet flawed approach Here's my initial naive and simplistic solution that has quite a few problems: public static IObservable<T> Buffered<T>(this IObservable<T> source, TimeSpan minDelay) { Queue<T> q = new Queue<T>(); source.Subscribe(x => q.Enqueue(x)); return Observable.Interval(minDelay).Where(_ => q.Count > 0).Select(_ => q.Dequeue()); } The first obvious problem with this is that the IDisposable returned by the inner subscription to the raw source is lost and therefore the subscription can't be terminated. Calling Dispose on the IDisposable returned by this method kills the timer, but not the underlying raw event feed that is now needlessly filling the queue with nobody left to pull events from the queue. The second problem is that there's no way for exceptions or end-of-stream notifications to be propogated through from the raw event stream to the buffered stream - they are simply ignored when subscribing to the raw source. And last but not least, now I've got code that wakes up periodically regardless of whether there is actually any work to do, which I'd prefer to avoid in this wonderful new reactive world. 2. Way overly complex appoach To solve the problems encountered in my initial simplistic approach, I wrote a much more complicated function that behaves much like IObservable.Delay() (I used .NET Reflector to read that code and used it as the basis of my function). Unfortunately, a lot of the boilerplate logic such as AnonymousObservable is not publicly accessible outside the system.reactive code, so I had to copy and paste a lot of code. This solution appears to work, but given its complexity, I'm less confident that its bug free. I just can't believe that there isn't a way to accomplish this using some combination of the standard Reactive extensions. I hate feeling like I'm needlessly reinventing the wheel, and the pattern I'm trying to build seems like a fairly standard one.

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  • Calling system commands from Perl

    - by Dan J
    In an older version of our code, we called out from Perl to do an LDAP search as follows: # Pass the base DN in via the ldapsearch-specific environment variable # (rather than as the "-b" paramater) to avoid problems of shell # interpretation of special characters in the DN. $ENV{LDAP_BASEDN} = $ldn; $lcmd = "ldapsearch -x -T -1 -h $gLdapServer" . <snip> " > $lworkfile 2>&1"; system($lcmd); if (($? != 0) || (! -e "$lworkfile")) { # Handle the error } The code above would result in a successful LDAP search, and the output of that search would be in the file $lworkfile. Unfortunately, we recently reconfigured openldap on this server so that a "BASE DC=" is specified in /etc/openldap/ldap.conf and /etc/ldap.conf. That change seems to mean ldapsearch ignores the LDAP_BASEDN environment variable, and so my ldapsearch fails. I've tried a couple of different fixes but without success so far: (1) I tried going back to using the "-b" argument to ldapsearch, but escaping the shell metacharacters. I started writing the escaping code: my $ldn_escaped = $ldn; $ldn_escaped =~ s/\/\\/g; $ldn_escaped =~ s/`/\`/g; $ldn_escaped =~ s/$/\$/g; $ldn_escaped =~ s/"/\"/g; That threw up some Perl errors because I haven't escaped those regexes properly in Perl (the line number matches the regex with the backticks in). Backticks found where operator expected at /tmp/mycommand line 404, at end of line At the same time I started to doubt this approach and looked for a better one. (2) I then saw some Stackoverflow questions (here and here) that suggested a better solution. Here's the code: print("Processing..."); # Pass the arguments to ldapsearch by invoking open() with an array. # This ensures the shell does NOT interpret shell metacharacters. my(@cmd_args) = ("-x", "-T", "-1", "-h", "$gLdapPool", "-b", "$ldn", <snip> ); $lcmd = "ldapsearch"; open my $lldap_output, "-|", $lcmd, @cmd_args; while (my $lline = <$lldap_output>) { # I can parse the contents of my file fine } $lldap_output->close; The two problems I am having with approach (2) are: a) Calling open or system with an array of arguments does not let me pass > $lworkfile 2>&1 to the command, so I can't stop the ldapsearch output being sent to screen, which makes my output look ugly: Processing...ldap_bind: Success (0) additional info: Success b) I can't figure out how to choose which location (i.e. path and file name) to the file handle passed to open, i.e. I don't know where $lldap_output is. Can I move/rename it, or inspect it to find out where it is (or is it not actually saved to disk)? Based on the problems with (2), this makes me think I should return back to approach (1), but I'm not quite sure how to

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  • Loading multiple copies of a group of DLLs in the same process

    - by george
    Background I'm maintaining a plugin for an application. I'm Using Visual C++ 2003. The plugin is composed of several DLLs - there's the main DLL, that's the one that the application loads using LoadLibrary, and there are several utility DLLs that are used by the main DLL and by each other. Dependencies generally look like this: plugin.dll - utilA.dll, utilB.dll utilA.dll - utilB.dll utilB.dll - utilA.dll, utilC.dll You get the picture. Some of the dependencies between the DLLs are load-time and some run-time. All the DLL files are stored in the executable's directory (not a requirement, just how it works now). The problem There's a new requirement - running multiple instances of the plugin within the application. The application runs each instance of a plugin in its own thread, i.e. each thread calls The plugin's code, however, is nothing but thread-safe - lots of global variables etc.. Unfortunately, fixing the whole thing isn't currently an option, so I need a way to load multiple (at most 3) copies of the plugin's DLLs in the same process. Option 1: The distinct names approach Creating 3 copies of each DLL file, so that each file has a distinct name. e.g. plugin1.dll, plugin2.dll, plugin3.dll, utilA1.dll, utilA2.dll, utilA3.dll, utilB1.dll, etc.. The application will load plugin1.dll, plugin2.dll and plugin3.dll. The files will be in the executable's directory. For each group of DLLs to know each other by name (so the inter-dependencies work), the names need to be known at compilation time - meaning the DLLs need to be compiled multiple times, only each time with different output file names. Not very complicated, but I'd hate having 3 copies of the VS project files, and don't like having to compile the same files over and over. Option 2: The side-by-side assemblies approach Creating 3 copies of the DLL files, each group in its own directory, and defining each group as an assembly by putting an assembly manifest file in the directory, listing the plugin's DLLs. Each DLL will have an application manifest pointing to the assembly, so that the loader finds the copies of the utility DLLs that reside in the same directory. The manifest needs to be embedded for it to be found when a DLL is loaded using LoadLibrary. I'll use mt.exe from a later VS version for the job, since VS2003 has no built-in manifest embedding support. I've tried this approach with partial success - dependencies are found during load-time of the DLLs, but not when a DLL function is called that loads another DLL. This seems to be the expected behavior according to this article - A DLL's activation context is only used at the DLL's load-time, and afterwards it's deactivated and the process's activation context is used. I haven't yet tried working around this using ISOLATION_AWARE_ENABLED. Questions Got any other options? Any quick & dirty solution will do. :-) Will ISOLATION_AWARE_ENABLED even work with VS2003? Comments will be greatly appreciated. Thanks!

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  • Type for use in template object to compare double values

    - by DaClown
    I got this n-dimensional point object: template <class T, unsigned int dimension> class Obj { protected: T coords[dimension]; static const unsigned int size = dimension; public: Obj() { }; Obj(T def) { for (unsigned int i = 0; i < size; ++i) coords[i]=def; }; Obj(const Obj& o) { for (unsigned int i = 0; i < size; ++i) coords[i] = o.coords[i]; } const Obj& operator= (const Obj& rhs) { if (this != &rhs) for (unsigned int i = 0; i < size; ++i) coords[i] = rhs.coords[i]; return *this; } virtual ~Obj() { }; T get (unsigned int id) { if (id >= size) throw std::out_of_range("out of range"); return coords[id]; } void set (unsigned int id, T t) { if (id >= size) throw std::out_of_range("out of range"); coords[id] = t; } }; and a 3D point class which uses Obj as base class: template <class U> class Point3DBase : public Obj<U,3> { typedef U type; public: U &x, &y, &z; public: Point3DBase() : x(Obj<U,3>::coords[0]), y(Obj<U,3>::coords[1]), z(Obj<U,3>::coords[2]) { }; Point3DBase(U def) : Obj<U,3>(def), x(Obj<U,3>::coords[0]), y(Obj<U,3>::coords[1]), z(Obj<U,3>::coords[2]) { }; Point3DBase(U x_, U y_, U z_) : x(Obj<U,3>::coords[0]), y(Obj<U,3>::coords[1]), z(Obj<U,3>::coords[2]) { x = x_; y = y_; z= z_; }; Point3DBase(const Point3DBase& other) : x(Obj<U,3>::coords[0]), y(Obj<U,3>::coords[1]), z(Obj<U,3>::coords[2]) { x = other.x; y = other.y; z = other.z; } // several operators ... }; The operators, basically the ones for comparison, use the simple compare-the-member-object approach like: virtual friend bool operator== (const Point3DBase<U> &lhs, const Point3DBase<U> rhs) { return (lhs.x == rhs.x && lhs.y == rhs.y && lhs.z == rhs.z); } Then it occured to me that for the comparion of double values the simply equality approach is not very useful since double values should be compared with an error margin. What would be the best approach to introduce an error margin into the point? I thought about an epsDouble type as template parameter but I can't figure out how to achieve this.

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