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• How to implement a network protocol?

  - by gotch4

  Here is a generic question. I'm not in search of the best answer, I'd just like you to express your favourite practices. I want to implement a network protocol in Java (but this is a rather general question, I faced the same issues in C++), this is not the first time, as I have done this before. But I think I am missing a good way to implement it. In fact usually it's all about exchanging text messages and some byte buffers between hosts, storing the status and wait until the next message comes. The problem is that I usually end up with a bunch of switch and more or less complex if statements that react to different statuses / messages. The whole thing usually gets complicated and hard to mantain. Not to mention that sometimes what comes out has some "blind spot", I mean statuses of the protocol that have not been covered and that behave in a unpredictable way. I tried to write down some state machine classes, that take care of checking start and end statuses for each action in more or less smart ways. This makes programming the protocol very complicated as I have to write lines and lines of code to cover every possible situation. What I'd like is something like a good pattern, or a best practice that is used in programming complex protocols, easy to mantain and to extend and very readable. What are your suggestions?

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• Generating a canonical path

  - by Joel

  Does any one know of any Java libraries I could use to generate canonical paths (basically remove back-references). I need something that will do the following: Raw Path - Canonical Path /../foo/ -> /foo /foo/ -> /foo /../../../ -> / /./foo/./ -> /foo //foo//bar -> /foo/bar //foo/../bar -> /bar etc... At the moment I lazily rely on using: new File("/", path).getCanonicalPath(); But this resolves the path against the actual file system, and is synchronised. java.lang.Thread.State: BLOCKED (on object monitor) at java.io.ExpiringCache.get(ExpiringCache.java:55) - waiting to lock <0x93a0d180> (a java.io.ExpiringCache) at java.io.UnixFileSystem.canonicalize(UnixFileSystem.java:137) at java.io.File.getCanonicalPath(File.java:559) The paths that I am canonicalising do not exist on my file system, so just the logic of the method will do me fine, thus not requiring any synchronisation. I'm hoping for a well tested library rather than having to write my own.

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• PHP OOP: Avoid Singleton/Static Methods in Domain Model Pattern

  - by sunwukung

  I understand the importance of Dependency Injection and its role in Unit testing, which is why the following issue is giving me pause: One area where I struggle not to use the Singleton is the Identity Map/Unit of Work pattern (Which keeps tabs on Domain Object state). //Not actual code, but it should demonstrate the point class Monitor{//singleton construction omitted for brevity static $members = array();//keeps record of all objects static $dirty = array();//keeps record of all modified objects static $clean = array();//keeps record of all clean objects } class Mapper{//queries database, maps values to object fields public function find($id){ if(isset(Monitor::members[$id]){ return Monitor::members[$id]; } $values = $this->selectStmt($id); //field mapping process omitted for brevity $Object = new Object($values); Monitor::new[$id]=$Object return $Object; } $User = $UserMapper->find(1);//domain object is registered in Id Map $User->changePropertyX();//object is marked "dirty" in UoW // at this point, I can save by passing the Domain Object back to the Mapper $UserMapper->save($User);//object is marked clean in UoW //but a nicer API would be something like this $User->save(); //but if I want to do this - it has to make a call to the mapper/db somehow $User->getBlogPosts(); //or else have to generate specific collection/object graphing methods in the mapper $UserPosts = $UserMapper->getBlogPosts(); $User->setPosts($UserPosts); Any advice on how you might handle this situation? I would be loathe to pass/generate instances of the mapper/database access into the Domain Object itself to satisfy DI - At the same time, avoiding that results in lots of calls within the Domain Object to external static methods. Although I guess if I want "save" to be part of its behaviour then a facility to do so is required in its construction. Perhaps it's a problem with responsibility, the Domain Object shouldn't be burdened with saving. It's just quite a neat feature from the Active Record pattern - it would be nice to implement it in some way.

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• How is timezone handled in the lifecycle of an ADO.NET + SQL Server DateTime column?

  - by stimpy77

  Using SQL Server 2008. This is a really junior question and I could really use some elaborate information, but the information on Google seems to dance around the topic quite a bit and it would be nice if there was some detailed elaboration on how this works... Let's say I have a datetime column and in ADO.NET I set it to DateTime.UtcNow. 1) Does SQL Server store DateTime.UtcNow accordingly, or does it offset it again based on the timezone of where the server is installed, and then return it offset-reversed when queried? I think I know that the answer is "of course it stores it without offsetting it again" but want to be certain. So then I query for it and cast it from, say, an IDataReader column to a DateTime. As far as I know, System.DateTime has metadata that internally tracks whether it is a UTC DateTime or it is an offsetted DateTime, which may or may not cause .ToLocalTime() and .ToUniversalTime() to have different behavior depending on this state. So, 2) Does this casted System.DateTime object already know that it is a UTC DateTime instance, or does it assume that it has been offset? Now let's say I don't use UtcNow, I use DateTime.Now, when performing an ADO.NET INSERT or UPDATE. 3) Does ADO.NET pass the offset to SQL Server and does SQL Server store DateTime.Now with the offset metadata? So then I query for it and cast it from, say, an IDataReader column to a DateTime. 4) Does this casted System.DateTime object already know that it is an offset time, or does it assume that it is UTC?

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• GWT in its web-mode throws StatusCodeException but in its hosted-mode , it's working perfect

  - by broshni

  Hi to all, I am new to this forum. Actually I have an issue here regarding my application which is hibernate+struts based application. Recently we have decided to integrate GWT into our application. We are using gwt 1.5.3 build. We have set up everything exactly as we find in documentation and various blogs. Yeah I am now in a very nervy state as gwt in its web- mode is treating me in a very embarassing manner. But it is compiling and working perfectly fine in its hosted-mode and everything works fine as we expected and designed. When I try to integrate GWT with our application i.e. running in tomcat (http://localhost:8080/myapps/example.do? reqCode=takeMeToGWT&userId=12&templateId=10). The gwt page is loaded partially and in the midst it throws an exception i.e. StatusCodeException. This doesn't happen when I run the gwt application in hosted-mode ( http://localhost:8888/com.myapp.gwt.MyApp/Home.html ) . I am using Intellij Idea 8, struts 1.3 ,hibernate 3 and tomcat 5.5 . Expecting your responses at the earliest possible time. Thanking you B Roshnikanta Sharma [email protected]

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• Use properties or methods to expose business rules in C#?

  - by Val

  I'm writing a class to encapsulate some business rules, each of which is represented by a boolean value. The class will be used in processing an InfoPath form, so the rules get the current program state by looking up values in a global XML data structure using XPath operations. What's the best (most idiomatic) way to expose these rules to callers -- properties or public methods? Call using properties Rules rules = new Rules(); if ( rules.ProjectRequiresApproval ) { // get approval } else { // skip approval } Call using methods Rules rules = new Rules(); if ( rules.ProjectRequiresApproval() ) { // get approval } else { // skip approval } Rules class exposing rules as properties public class Rules() { private int _amount; private int threshold = 100; public Rules() { _amount = someExpensiveXpathOperation; } // rule property public bool ProjectRequiresApproval { get { return _amount < threshold } } } Rules class exposing rules as methods public class Rules() { private int _amount; private int threshold = 100; public Rules() { _amount = someExpensiveXpathOperation; } // rule method public bool ProjectRequiresApproval() { return _amount < threshold; } } What are the pros and cons of one over the other?

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• Is something along the lines of nested memoization needed here?

  - by Daniel

  System.Transactions notoriously escalates transactions involving multiple connections to the same database to the DTC. The module and helper class, ConnectionContext, below are meant to prevent this by ensuring multiple connection requests for the same database return the same connection object. This is, in some sense, memoization, although there are multiple things being memoized and the second is dependent on the first. Is there some way to hide the synchronization and/or mutable state (perhaps using memoization) in this module, or perhaps rewrite it in a more functional style? (It may be worth nothing that there's no locking when getting the connection by connection string because Transaction.Current is ThreadStatic.) type ConnectionContext(connection:IDbConnection, ownsConnection) = member x.Connection = connection member x.OwnsConnection = ownsConnection interface IDisposable with member x.Dispose() = if ownsConnection then connection.Dispose() module ConnectionManager = let private _connections = new Dictionary<string, Dictionary<string, IDbConnection>>() let private getTid (t:Transaction) = t.TransactionInformation.LocalIdentifier let private removeConnection tid = let cl = _connections.[tid] for (KeyValue(_, con)) in cl do con.Close() lock _connections (fun () -> _connections.Remove(tid) |> ignore) let getConnection connectionString (openConnection:(unit -> IDbConnection)) = match Transaction.Current with | null -> new ConnectionContext(openConnection(), true) | current -> let tid = getTid current // get connections for the current transaction let connections = match _connections.TryGetValue(tid) with | true, cl -> cl | false, _ -> let cl = Dictionary<_,_>() lock _connections (fun () -> _connections.Add(tid, cl)) cl // find connection for this connection string let connection = match connections.TryGetValue(connectionString) with | true, con -> con | false, _ -> let initial = (connections.Count = 0) let con = openConnection() connections.Add(connectionString, con) // if this is the first connection for this transaction, register connections for cleanup if initial then current.TransactionCompleted.Add (fun args -> let id = getTid args.Transaction removeConnection id) con new ConnectionContext(connection, false)

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• How deserealizing JSON with GSON

  - by loko

  I have one result of APPI http://developer.yahoo.com/geo/placefinder/guide/examples.html, I need to deserealizing the result JSON of example only with GSON http://where.yahooapis.com/geocode?location=San+Francisco,+CA&flags=J&appid=yourappid But i dont now have to do the class for deserealizing one JSON with array This is the reponse: {"ResultSet": {"version":"1.0", "Error":0, "ErrorMessage":"No error", "Locale":"en_US", "Quality":40, "Found":1, "Results":[ {"quality":40, "latitude":"37.779160", "longitude":"-122.420049", "offsetlat":"37.779160", "offsetlon":"-122.420049", "radius":5000, "name":"", "line1":"", "line2":"San Francisco, CA", "line3":"", "line4":"United States", "house":"", "street":"", "xstreet":"", "unittype":"", "unit":"", "postal":"", "neighborhood":"", "city":"San Francisco", "county":"San Francisco County", "state":"California", "country":"United States", "countrycode":"US", "statecode":"CA", "countycode":"", "uzip":"94102", "hash":"C1D313AD706E3B3C", "woeid":12587707, "woetype":9}] } } Im trying to deserealizing of this way but i couldn´t do that, please help me to do the correct class to get the JSON with GSON. public class LocationAddress { private ResultSet resultset; public static class ResultSet{ private String version; private String Error; private String ErrorMessage; private List<Results> results; } public static class Results{ private String quality; private String latitude; private String longitude; public String getQuality() { return quality; } public void setQuality(String quality) { this.quality = quality; } public String getLatitude() { return latitude; } public void setLatitude(String latitude) { this.latitude = latitude; } public String getLongitude() { return longitude; } public void setLongitude(String longitude) { this.longitude = longitude; } } }

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• SharePoint Web Part on Masterpage not displaying on SubSite

  - by madatanic

  Hi all, Scenario: - A out-of-the-box DataFormWebPart on masterpage connected to a top-level site List. - A subsite using that same masterpage from top-level site. - Error happens when accessing the sub site as below Stack Trace [InvalidOperationException: Operation is not valid due to the current state of the object.] Microsoft.SharePoint.SPFolder.get_ContentTypeOrder() +488 Microsoft.SharePoint.SPContext.get_ContentTypes() +898 Microsoft.SharePoint.SPContext.get_ContentType() +472 Microsoft.SharePoint.SPContext.get_Fields() +271 Microsoft.SharePoint.WebControls.FormComponent.get_Fields() +44 Microsoft.SharePoint.WebControls.FieldMetadata.get_Field() +419 Microsoft.SharePoint.WebControls.FormField.CreateChildControls() +596 System.Web.UI.Control.EnsureChildControls() +87 Microsoft.SharePoint.WebControls.BaseFieldControl.OnLoad(EventArgs e) +176 System.Web.UI.Control.LoadRecursive() +50 System.Web.UI.Control.LoadRecursive() +141 System.Web.UI.Control.AddedControl(Control control, Int32 index) +265 System.Web.UI.ControlCollection.Add(Control child) +80 System.Web.UI.Control.AddParsedSubObject(Object obj) +41 Microsoft.SharePoint.WebPartPages.WebPart.AddParsedSubObject(Object obj) +1149 Microsoft.SharePoint.WebPartPages.DataFormWebPart.CreateChildControls() +1267 System.Web.UI.Control.EnsureChildControls() +87 System.Web.UI.Control.PreRenderRecursiveInternal() +44 System.Web.UI.WebControls.WebParts.WebPart.PreRenderRecursiveInternal() +42 System.Web.UI.Control.PreRenderRecursiveInternal() +171 System.Web.UI.Control.PreRenderRecursiveInternal() +171 System.Web.UI.Control.PreRenderRecursiveInternal() +171 System.Web.UI.Control.PreRenderRecursiveInternal() +171 System.Web.UI.Control.PreRenderRecursiveInternal() +171 System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +842 I have tried the solution from this site to enable the subsite to access top level site list. Is this a bug? Any help would be appreciated.

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• Thread Locking CollectionViewSource

  - by Robert

  I added an event handler to my code and it broke all access to the CollectionViewSources in the SystemHTA class saying "The calling thread cannot access this object because a different thread owns it". My class was working when "this.systemHTA = new SystemHTA();" was placed outside of the DeviceManager_StateChanged() function. public partial class MainWindow : Window { private DeviceManager DeviceManager = DeviceManager.Instance; public SystemHTA systemHTA; public MainWindow() { InitializeComponent(); } private void Window_Loaded(object sender, RoutedEventArgs e) { DeviceManager.StateChanged += new EventHandler<DeviceManagerStateChangedEventArgs>(DeviceManager_StateChanged); DeviceManager.Initialize(); } void DeviceManager_StateChanged(object sender, DeviceManagerStateChangedEventArgs e) { if (e.State == DeviceManagerState.Operational) { this.systemHTA = new SystemHTA(); } } private void button1_Click(object sender, RoutedEventArgs e) { this.systemHTA.GetViewSourceTest(); } } public class SystemHTA { private CollectionViewSource _deviceTestSource; public SystemHTA() { _deviceTestSource = new CollectionViewSource(); _deviceTestSource.Source = CreateLoadData<HWController>.ControllerCollection; } public void GetViewSourceTest() { ListCollectionView view = (ListCollectionView)_deviceTestSource.View; //This creates an error saying a thread already owns _deviceTestSource } }

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• Get part of array string

  - by user1560295

  Hello my output PHP code is : Array ( [country] => BG - Bulgaria ) ... and he comes from here : <?php $ip = $_SERVER['REMOTE_ADDR']; print_r(geoCheckIP($ip)); //Array ( [domain] => dslb-094-219-040-096.pools.arcor-ip.net [country] => DE - Germany [state] => Hessen [town] => Erzhausen ) //Get an array with geoip-infodata function geoCheckIP($ip) { //check, if the provided ip is valid if(!filter_var($ip, FILTER_VALIDATE_IP)) { throw new InvalidArgumentException("IP is not valid"); } //contact ip-server $response=@file_get_contents('http://www.netip.de/search?query='.$ip); if (empty($response)) { throw new InvalidArgumentException("Error contacting Geo-IP-Server"); } //Array containing all regex-patterns necessary to extract ip-geoinfo from page $patterns=array(); $patterns["country"] = '#Country: (.*?)&nbsp;#i'; //Array where results will be stored $ipInfo=array(); //check response from ipserver for above patterns foreach ($patterns as $key => $pattern) { //store the result in array $ipInfo[$key] = preg_match($pattern,$response,$value) && !empty($value[1]) ? $value[1] : ''; } return $ipInfo; } ?> How can I get ONLY the name of the Country like in my case "Bulgaria"? I think it will happen with preg_replace or substr but i dont know what is the better solution now.

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• regressions with many nested categorical covariates

  - by eric

  I have a few hundred thousand measurements where the dependent variable is a probability, and would like to use logistic regression. However, the covariates I have are all categorical, and worse, are all nested. By this I mean that if a certain measurement has "city - Phoenix" then obviously it is certain to have "state - Arizona" and "country - U.S." I have four such factors - the most granular has some 20k levels, but if need be I could do without that one, I think. I also have a few non-nested categorical covariates (only four or so, with maybe three different levels each). What I am most interested in is prediction - given a new observation in some city, I would like to know the relevant probability/dependent variable. I am not interested as much in the related inferential machinery - standard deviations, etc - at least as of now. I am hoping I can afford to be sloppy. However, I would love to have that information unless it requires methods that are more computationally expensive. Does anyone have any advice on how to attack this? I have looked into mixed effects, but am not sure it is what I am looking for.

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• What's the best way to store Logon User information for Web Application?

  - by Morgan Cheng

  I was once in a project of web application developed on ASP.NET. For each logon user, there is an object (let's call it UserSessionObject here) created and stored in RAM. For each HTTP request of given user, matching UserSessoinObject instance is used to visit user state information and connection to database. So, this UserSessionObject is pretty important. This design brings several problems found later: 1) Since this UserSessionObject is cached in ASP.NET memory space, we have to config load balancer to be sticky connection. That is, HTTP request in single session would always be sent to one web server behind. This limit scalability and maintainability. 2) This UserSessionObject is accessed in every HTTP request. To keep the consistency, there is a exclusive lock for the UserSessionObject. Only one HTTP request can be processed at any given time because it must to obtain the lock first. The performance and response time is affected. Now, I'm wondering whether there is better design to handle such logon user case. It seems Sharing-Nothing-Architecture helps. That means long user info is retrieved from database each time. I'm afraid that would hurt performance. Is there any design pattern for long user web app? Thanks.

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• 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

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• Coordinating typedefs and structs in std::multiset (C++)

  - by Sarah

  I'm not a professional programmer, so please don't hesitate to state the obvious. My goal is to use a std::multiset container (typedef EventMultiSet) called currentEvents to organize a list of structs, of type Event, and to have members of class Host occasionally add new Event structs to currentEvents. The structs are supposed to be sorted by one of their members, time. I am not sure how much of what I am trying to do is legal; the g++ compiler reports (in "Host.h") "error: 'EventMultiSet' has not been declared." Here's what I'm doing: // Event.h struct Event { public: bool operator < ( const Event & rhs ) const { return ( time < rhs.time ); } double time; int eventID; int hostID; }; // Host.h ... void calcLifeHist( double, EventMultiSet * ); // produces compiler error ... void addEvent( double, int, int, EventMultiSet * ); // produces compiler error // Host.cpp #include "Event.h" ... // main.cpp #include "Event.h" ... typedef std::multiset< Event, std::less< Event > > EventMultiSet; EventMultiSet currentEvents; EventMultiSet * cePtr = &currentEvents; ... Major questions Where should I include the EventMultiSet typedef? Are my EventMultiSet pointers obviously problematic? Is the compare function within my Event struct (in theory) okay? Thank you very much in advance.

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• DO NOT BOTHER. THE PROBLEM IS NOT TRANSACTIONS. DUNNO HOW TO CLOSE / DELETE

  - by matti

  THE PROBLEM IS SOLVED. I DUNNO HOW TO CLOSE THIS QUESTION. ANOTHER SERVICE IS PROPABLY RUNNING AT ALMOST SAME SYNC THAT DOES THE THING. MY WORK "MATE" WILL HEAR A THING OR TWO IN THE MORNING. I have following code in windows service: data is in the dataset and it has been populated earlier and then rows are updated and inserted to dataset tables before calling code below. using (dataSetTxn = _cnctn.BeginTransaction()) { try { _somePlanAdptr.UpdateCommand.Transaction = dataSetTxn; _someLogAdptr.InsertCommand.Transaction = dataSetTxn; _someLinkAdptr.InsertCommand.Transaction = dataSetTxn; _someDataAdptr.InsertCommand.Transaction = dataSetTxn; _log.WriteDebug("Updating SomePlanAction"); _somePlanAdptr.Update(_ofDataSet, "SomePlanAction"); _log.WriteDebug(string.Format("Inserting {0} rows to SomeLog")); //error _someLogAdptr.Update(_ofDataSet, "SomeLog"); _log.WriteDebug(string.Format("Updating SomeLink with {0} rows", _ofDataSet.Tables["SomeLink"].Rows.Count)); _someLinkAdptr.Update(_ofDataSet, "SomeLink"); _log.WriteDebug(string.Format("Updating SomeData with {0} rows", _ofDataSet.Tables["SomeData"].Rows.Count)); _someDataAdptr.Update(_ofDataSet, "SomeData"); _log.WriteDebug("Commiting all changes to database."); dataSetTxn.Commit(); } catch (Exception e) { _log.WriteError("Updating database failed -> rollback", e); if (dataSetTxn != null && _cnctn.State == ConnectionState.Open) dataSetTxn.Rollback(); throw e; } } so one of the lines causes an exception log.WriteDebug(string.Format("Inserting {0} rows to SomeLog")); //error still the first adapter's data is updated to database. when debugged the data is not yet updated until the method that calls all (including this bit) exits. The method that does all is timed with System.Threading.Timer. Thanks & BR -Matti

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• jQuery adding a row to a table with click() handler for tr

  - by Dave

  I'm having an issue with a control I'm building that contains a table where the body is scrollable. The rows have a click() function handler established like: /** * This function is called when the user clicks the mouse on a row in * our scrolling table. */ $('.innerTable tr').click (function (e) { // // Only react to the click if the mouse was clicked in the DIV or // the TD. // if (event.target.nodeName == 'DIV' || event.target.nodeName == 'TD' ) { // // If the user wasn't holding down the control key, then deselect // any previously selected columns. // if (e.ctrlKey == false) { $('.innerTable tr').removeClass ('selected'); } // // Toggle the selected state of the row that was clicked. // $(this).toggleClass ('selected'); } }); There is a button that adds rows to the table like: $('#innerTable > tbody:last').append('<tr>...some information...</tr>'); While the rows ARE added successfully, for some reason, the static rows work with the click handler, but the newly added rows do not. Is there something I'm missing? Thanks in advance!

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• Database schema for a library

  - by ABach

  Hi all - I'm designing a library management system for a department at my university and I wanted to enlist your eyes on my proposed schema. This post is primarily concerned with how we store multiple copies of each book; something about what I've designed rubs me the wrong way, and I'm hoping you all can point out better ways to tackle things. For dealing with users checking out books, I've devised three tables: book, customer, and book_copy. The relationships between these tables are as follows: Every book has many book_copies (to avoid duplicating the book's information while storing the fact that we have multiple copies of that book). Every user has many book_copies (the other end of the relationship) The tables themselves are designed like this: ------------------------------------------------ book ------------------------------------------------ + id + title + author + isbn + etc. ------------------------------------------------ ------------------------------------------------ customer ------------------------------------------------ + id + first_name + first_name + email + address + city + state + zip + etc. ------------------------------------------------ ------------------------------------------------ book_copy ------------------------------------------------ + id + book_id (FK to book) + customer_id (FK to customer) + checked_out + due_date + etc. ------------------------------------------------ Something about this seems incorrect (or at least inefficient to me) - the perfectionist in me feels like I'm not normalizing this data correctly. What say ye? Is there a better, more effective way to design this schema? Thanks!

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• Repaint() not calling paint() in Java

  - by Joshua Auriemma

  Let me start off by saying I know I've violated some basic Java principles in this messy code, but I'm desperately trying to finish a program by Tuesday for a social science experiment, and I don't know Java, so I'm basically just fumbling through it for now. With that disclaimer out of the way, I have a separate program working where a circle is moving around the screen and the user must click on it. It works fine when its in its own separate class file, but when I add the code to my main program, it's no longer working. I don't even really understand why repaint() calls my paint() function — as far as I'm concerned, it's magic, but I've noticed that repaint() calls paint() in my test program, but not in the more complicated actual program, and I assume that's why the circle is no longer painting on my program. Entire code is below: import java.awt.Color; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.Rectangle; import javax.swing.*; import java.awt.event.*; import java.awt.geom.Ellipse2D; import java.io.FileReader; import java.io.IOException; import java.util.Calendar; public class Reflexology1 extends JFrame{ private static final long serialVersionUID = -1295261024563143679L; private Ellipse2D ball = new Ellipse2D.Double(0, 0, 25, 25); private Timer moveBallTimer; int _ballXpos, _ballYpos; JButton button1, button2; JButton movingButton; JTextArea textArea1; int buttonAClicked, buttonDClicked; private long _openTime = 0; private long _closeTime = 0; JPanel thePanel = new JPanel(); JPanel thePlacebo = new JPanel(); final JFrame frame = new JFrame("Reflexology"); final JFrame frame2 = new JFrame("The Test"); JLabel label1 = new JLabel("Press X and then click the moving dot as fast as you can."); public static void main(String[] args){ new Reflexology1(); } public Reflexology1(){ frame.setSize(600, 475); frame.setLocationRelativeTo(null); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.setTitle("Reflexology 1.0"); frame.setResizable(false); frame2.setSize(600, 475); frame2.setLocationRelativeTo(null); frame2.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame2.setTitle("Reflexology 1.0"); frame2.setResizable(false); button1 = new JButton("Accept"); button2 = new JButton("Decline"); //movingButton = new JButton("Click Me"); ListenForAcceptButton lForAButton = new ListenForAcceptButton(); ListenForDeclineButton lForDButton = new ListenForDeclineButton(); button1.addActionListener(lForAButton); button2.addActionListener(lForDButton); //movingButton.addActionListener(lForMButton); JTextArea textArea1 = new JTextArea(24, 50); textArea1.setText("Tracking Events\n"); textArea1.setLineWrap(true); textArea1.setWrapStyleWord(true); textArea1.setSize(15, 50); textArea1.setEditable(false); FileReader reader = null; try { reader = new FileReader("EULA.txt"); textArea1.read(reader, "EULA.txt"); } catch (IOException exception) { System.err.println("Problem loading file"); exception.printStackTrace(); } finally { if (reader != null) { try { reader.close(); } catch (IOException exception) { System.err.println("Error closing reader"); exception.printStackTrace(); } } } JScrollPane scrollBar1 = new JScrollPane(textArea1, JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED, JScrollPane.HORIZONTAL_SCROLLBAR_NEVER); AdjustmentListener listener = new MyAdjustmentListener(); thePanel.add(scrollBar1); thePanel.add(button1); thePanel.add(button2); frame.add(thePanel); ListenForMouse lForMouse = new ListenForMouse(); thePlacebo.addMouseListener(lForMouse); thePlacebo.add(label1); frame2.add(thePlacebo); ListenForWindow lForWindow = new ListenForWindow(); frame.addWindowListener(lForWindow); frame2.addKeyListener(new KeyAdapter() { public void keyPressed(KeyEvent e){ if(e.getKeyChar() == 'X' || e.getKeyChar() == 'x') {moveBallTimer.start();} } }); frame.setVisible(true); moveBallTimer = new Timer(1000, new ActionListener() { public void actionPerformed(ActionEvent e) { moveBall(); System.out.println("Timer started!"); repaint(); } }); addKeyListener(new KeyAdapter() { public void keyPressed(KeyEvent e) { if(frame2.isVisible()){ moveBallTimer.start(); } } }); } private class ListenForAcceptButton implements ActionListener{ public void actionPerformed(ActionEvent e){ if (e.getSource() == button1){ Calendar ClCDateTime = Calendar.getInstance(); System.out.println(ClCDateTime.getTimeInMillis() - _openTime); _closeTime = ClCDateTime.getTimeInMillis() - _openTime; //frame.getContentPane().remove(thePanel); //thePlacebo.addKeyListener(lForKeys); //frame.getContentPane().add(thePlacebo); //frame.repaint(); //moveBallTimer.start(); frame.setVisible(false); frame2.setVisible(true); frame2.revalidate(); frame2.repaint(); } } } private class ListenForDeclineButton implements ActionListener{ public void actionPerformed(ActionEvent e){ if (e.getSource() == button2){ JOptionPane.showMessageDialog(Reflexology1.this, "You've declined the license agreement. DO NOT RESTART the program. Please go inform a researcher that you have declined the agreement.", "WARNING", JOptionPane.INFORMATION_MESSAGE); System.exit(0); } } } private class ListenForWindow implements WindowListener{ public void windowActivated(WindowEvent e) { //textArea1.append("Window is active"); } // if this.dispose() is called, this is called: public void windowClosed(WindowEvent arg0) { } // When a window is closed from a menu, this is called: public void windowClosing(WindowEvent arg0) { } // Called when the window is no longer the active window: public void windowDeactivated(WindowEvent arg0) { //textArea1.append("Window is NOT active"); } // Window gone from minimized to normal state public void windowDeiconified(WindowEvent arg0) { //textArea1.append("Window is in normal state"); } // Window has been minimized public void windowIconified(WindowEvent arg0) { //textArea1.append("Window is minimized"); } // Called when the Window is originally created public void windowOpened(WindowEvent arg0) { //textArea1.append("Let there be Window!"); Calendar OlCDateTime = Calendar.getInstance(); _openTime = OlCDateTime.getTimeInMillis(); //System.out.println(_openTime); } } private class MyAdjustmentListener implements AdjustmentListener { public void adjustmentValueChanged(AdjustmentEvent arg0) { AdjustmentEvent scrollBar1; //System.out.println(scrollBar1.getValue())); } } public void paint(Graphics g) { //super.paint(g); frame2.paint(g); Graphics2D g2d = (Graphics2D) g; g2d.setColor(Color.RED); g2d.fill(ball); System.out.println("Calling fill()"); } protected void moveBall() { //System.out.println("I'm in the moveBall() function!"); int width = getWidth(); int height = getHeight(); int min, max, randomX, randomY; min =200; max = -200; randomX = min + (int)(Math.random() * ((max - min)+1)); randomY = min + (int)(Math.random() * ((max - min)+1)); //System.out.println(randomX + ", " + randomY); Rectangle ballBounds = ball.getBounds(); //System.out.println(ballBounds.x + ", " + ballBounds.y); if (ballBounds.x + randomX < 0) { randomX = 200; } else if (ballBounds.x + ballBounds.width + randomX > width) { randomX = -200; } if (ballBounds.y + randomY < 0) { randomY = 200; } else if (ballBounds.y + ballBounds.height + randomY > height) { randomY = -200; } ballBounds.x += randomX; ballBounds.y += randomY; _ballXpos = ballBounds.x; _ballYpos = ballBounds.y; ball.setFrame(ballBounds); } public void start() { moveBallTimer.start(); } public void stop() { moveBallTimer.stop(); } private class ListenForMouse implements MouseListener{ // Called when the mouse is clicked public void mouseClicked(MouseEvent e) { //System.out.println("Mouse Panel pos: " + e.getX() + " " + e.getY() + "\n"); if (e.getX() >=_ballXpos && e.getX() <= _ballXpos + 25 && e.getY() <=_ballYpos && e.getY() >= _ballYpos - 25 ) { System.out.println("TRUE"); } System.out.println("{e.getX(): " + e.getX() + " / " + "_ballXpos: " + _ballXpos + " | " + "{e.getY(): " + e.getY() + " / " + "_ballYpos: " + _ballYpos); } public void mouseEntered(MouseEvent arg0) { // TODO Auto-generated method stub } public void mouseExited(MouseEvent arg0) { // TODO Auto-generated method stub } public void mousePressed(MouseEvent arg0) { // TODO Auto-generated method stub } public void mouseReleased(MouseEvent arg0) { // TODO Auto-generated method stub } } // System.out.println("e.getX(): " + e.getX() + " / " + "_ballXpos: " + _ballXpos); // Mouse over public void mouseEntered(MouseEvent arg0) { // TODO Auto-generated method stub } // Mouse left the mouseover area: public void mouseExited(MouseEvent arg0) { // TODO Auto-generated method stub } public void mousePressed(MouseEvent arg0) { // TODO Auto-generated method stub } public void mouseReleased(MouseEvent arg0) { // TODO Auto-generated method stub } } Could anyone tell me what I need to do to get repaint() to call the paint() method in the above program? I'm assuming the multiple frames is causing the problem, but that's just a guess. Thanks.

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• Can someone confirm how Microsoft Excel 2007 internally represents numbers?

  - by Jon

  I know the IEEE 754 floating point standard by heart as I had to learn it for an exam. I know exactly how floating point numbers are used and the problems that they can have. I can manually do any operation on the binary representation of floating point numbers. However, I have not found a single source which unambiguously states that excel uses 64 bit floating point numbers to internally represent every single cell "type" in excel except for text. I have no idea whether some of the types use signed or unsigned integers and some use 64 bit floating point. I have found literally trillions of articles which 1) describe floating point numbers and then 2) talk about being careful with excel because of floating point numbers. I have not found a single statement saying "all types are 64 bit floating point numbers except text". I have not found a single statement which says "changing the type of a cell only changes its visual representation and not its internal representation, unless you change the type from text to some other type which is not text or you change some other type which is not text to text". This is literally all I want to know, and it's so simple and axiomatic that I am amazed that I can find trillions of articles and pages which talk around these statements but do not state them directly.

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• C# Cast Class to Overridden Class

  - by Nathan Tornquist

  I have a class Application that I need to override with INotifyPropertyChanged events. I have written the logic to override the original class and ended up creating SuperApplication I am pulling the data from a library though, and cannot change the loading logic. I just need a way to get the data from the original class into my superClass. I've tried things like superClass = (SuperApplication)standardClass; but it hasn't worked. How would I go about doing this? If it helps, this is the code I'm using to override the original class: public class SuperCreditApplication : CreditApplication { public SuperCreditApplicant Applicant { get; set; } public SuperCreditApplicant CoApplicant { get; set; } } public class SuperCreditApplicant : CreditApplicant { public SuperProspect Prospect { get; set; } } public class SuperProspect : Prospect, INotifyPropertyChanged { public State DriverLicenseState { get { return DriverLicenseState; } set { DriverLicenseState = value; OnPropertyChanged("DriverLicenseState"); } } public event PropertyChangedEventHandler PropertyChanged; private void OnPropertyChanged(string propertyName) { if (PropertyChanged != null) { PropertyChanged(this, new PropertyChangedEventArgs(propertyName)); } } }

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• iOS Cell Label link

  - by hart1994

  Hi I am new to iOS programming and I need a little help. I have a table view cell which is populated by data from a .plist file. I need to be able to make a link within one of the cells. How could I do this? Here is the code which is loading the data into the cells: - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { static NSString *CellIdentifier = @"CustomTableCell"; static NSString *CellNib = @"DetailViewCell"; DetailViewCell *cell = (DetailViewCell *)[tableView dequeueReusableCellWithIdentifier:CellIdentifier]; if (cell == nil) { NSArray *nib = [[NSBundle mainBundle] loadNibNamed:CellNib owner:self options:nil]; cell = (DetailViewCell *)[nib objectAtIndex:0]; } cell.accessoryType = UITableViewCellAccessoryNone; cell.cellTitleLabel.textColor = [UIColor blackColor]; cell.cellTitleLabel.font = [UIFont systemFontOfSize:20.0]; cell.cellSubtitleLabel.textColor = [UIColor darkGrayColor]; informations = [[NSArray alloc] initWithObjects:@"City", @"Country", @"State", @"History", @"Link", nil]; subtitles = [[NSArray alloc] initWithObjects:titleString, subtitleString, stateString, populationString, @"Link", nil]; cell.cellTitleLabel.text = [informations objectAtIndex:indexPath.row]; cell.cellSubtitleLabel.text = [subtitles objectAtIndex:indexPath.row]; return (DetailViewCell *) cell; } For the cell "Link" I need it to open a url which is stored in the .plist file. How could i do this? Many thanks Ryan PS: I'm a newbie at this stuff, so be descriptive. Thanks

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• Implementing a bitfield using java enums

  - by soappatrol

  Hello, I maintain a large document archive and I often use bit fields to record the status of my documents during processing or when validating them. My legacy code simply uses static int constants such as: static int DOCUMENT_STATUS_NO_STATE = 0 static int DOCUMENT_STATUS_OK = 1 static int DOCUMENT_STATUS_NO_TIF_FILE = 2 static int DOCUMENT_STATUS_NO_PDF_FILE = 4 This makes it pretty easy to indicate the state a document is in, by setting the appropriate flags. For example: status = DOCUMENT_STATUS_NO_TIF_FILE | DOCUMENT_STATUS_NO_PDF_FILE; Since the approach of using static constants is bad practice and because I would like to improve the code, I was looking to use Enums to achieve the same. There are a few requirements, one of them being the need to save the status into a database as a numeric type. So there is a need to transform the enumeration constants to a numeric value. Below is my first approach and I wonder if this is the correct way to go about this? class DocumentStatus{ public enum StatusFlag { DOCUMENT_STATUS_NOT_DEFINED(1<<0), DOCUMENT_STATUS_OK(1<<1), DOCUMENT_STATUS_MISSING_TID_DIR(1<<2), DOCUMENT_STATUS_MISSING_TIF_FILE(1<<3), DOCUMENT_STATUS_MISSING_PDF_FILE(1<<4), DOCUMENT_STATUS_MISSING_OCR_FILE(1<<5), DOCUMENT_STATUS_PAGE_COUNT_TIF(1<<6), DOCUMENT_STATUS_PAGE_COUNT_PDF(1<<7), DOCUMENT_STATUS_UNAVAILABLE(1<<8), private final long statusFlagValue; StatusFlag(long statusFlagValue) { this.statusFlagValue = statusFlagValue } public long getStatusFlagValue(){ return statusFlagValue } } /** * Translates a numeric status code into a Set of StatusFlag enums * @param numeric statusValue * @return EnumSet representing a documents status */ public EnumSet<StatusFlag> getStatusFlags(long statusValue) { EnumSet statusFlags = EnumSet.noneOf(StatusFlag.class) StatusFlag.each { statusFlag -> long flagValue = statusFlag.statusFlagValue if ( (flagValue&statusValue ) == flagValue ) { statusFlags.add(statusFlag) } } return statusFlags } /** * Translates a set of StatusFlag enums into a numeric status code * @param Set if statusFlags * @return numeric representation of the document status */ public long getStatusValue(Set<StatusFlag> flags) { long value=0 flags.each { statusFlag -> value|=statusFlag.getStatusFlagValue() } return value } public static void main(String[] args) { DocumentStatus ds = new DocumentStatus(); Set statusFlags = EnumSet.of( StatusFlag.DOCUMENT_STATUS_OK, StatusFlag.DOCUMENT_STATUS_UNAVAILABLE) assert ds.getStatusValue( statusFlags )==258 // 0000.0001|0000.0010 long numericStatusCode = 56 statusFlags = ds.getStatusFlags(numericStatusCode) assert !statusFlags.contains(StatusFlag.DOCUMENT_STATUS_OK) assert statusFlags.contains(StatusFlag.DOCUMENT_STATUS_MISSING_TIF_FILE) assert statusFlags.contains(StatusFlag.DOCUMENT_STATUS_MISSING_PDF_FILE) assert statusFlags.contains(StatusFlag.DOCUMENT_STATUS_MISSING_OCR_FILE) } }

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• Atomic operations on several transactionless external systems

  - by simendsjo

  Say you have an application connecting 3 different external systems. You need to update something in all 3. In case of a failure, you need to roll back the operations. This is not a hard thing to implement, but say operation 3 fails, and when rolling back, the rollback for operation 1 fails! Now the first external system is in an invalid state... I'm thinking a possible solution is to shut down the application and forcing a manual fix of the external system, but then again... It might already have used this information (and perhaps that's why it failed), or we might not have sufficient access. Or it might not even be a good way to rollback the action! Are there some good ways of handling such cases? EDIT: Some application details.. It's a multi user web application. Most of the work is done with scheduled jobs (through Quartz.Net), so most operations is run in it's own thread. Some user actions should trigger jobs that update several systems though. The external systems are somewhat unstable. I Was thinking of changing the application to use the Command and Unit Of Work pattern

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• Bluetooth to arduino

  - by user1833709

  My current project includes an Arduino Uno attached via USB to a laptop. The laptop is there is receive messages via bluetooth (I realize I could connect a bluetooth modem directly to the arduino but this project has to come in under budget). What I'd ideally like to do is write a program that continually checks whether the laptop has been paired to a bluetooth transmitter (my phone) and sends this to the arduino. Do you think should write a program that checks the bluetooth state and writes a 0 or 1 to a text document, and then use something like Gobetwino to read from the text document? I could probably figure out how to continually read from the file, but I don't know enough about bluetooth to know how to check whether it's paired or not, computer-side. Something that writes directly to the arduino instead of a text document would be my preference, but I don't know where to start. I'm using an Android phone and Windows 7. If you need more info about the setup, just ask. Does anyone have any experience with this?

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