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  • Communication between modules

    - by David Elentok
    I have an application that consists from the following three modules: Search (to search for objects) List (to display the search results) Painter (to allow me to edit objects) - this module isn't always loaded (Each object is a figure that I can edit in the painter). When I open an object in the painter it's added to the objects that are already in the painter and I can move it and alter it. I'm using an object similar to the EventAggregator to communicate between the modules. For example, to show the search results I publish a "ShowList" event that is caught by the List module (I'm not sure this is the best way to do this, if anyone has better idea please comment...). One of the features of the search module requires it to get the selected object in the painter (if the painter is available), and I'm not sure what would be the best way to do that... I thought of these solutions: Whenever the selected object in the painter changes it will publish a "PainterSelectedObjectChanged" event which will be caught by the search module and stored for later use. When the selected object is needed by the search module it will publish a "RequestingPainterSelectedObject" event which will be caught by the painter module. The painter module will then set the "SelectedObject" property in the EventArgs object, and when the publish is complete and we're back in the search module we will have the painter's selected object in the EventArgs object. What do you think? what is the right way to do this?

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  • Matlab - Propagate points orthogonally on to the edge of shape boundaries

    - by Graham
    Hi I have a set of points which I want to propagate on to the edge of shape boundary defined by a binary image. The shape boundary is defined by a 1px wide white edge. I also have the coordinates of these points stored in a 2 row by n column matrix. The shape forms a concave boundary with no holes within itself made of around 2500 points. I want to cast a ray from each point from the set of points in an orthogonal direction and detect at which point it intersects the shape boundary at. What would be the best method to do this? Are there some sort of ray tracing algorithms that could be used? Or would it be a case of taking orthogonal unit vector and multiplying it by a scalar and testing after multiplication if the end point of the vector is outside the shape boundary. When the end point of the unit vector is outside the shape, just find the point of intersection? Thank you very much in advance for any help!

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  • How can I extend this SQL query to find the k nearest neighbors?

    - by Smigs
    I have a database full of two-dimensional data - points on a map. Each record has a field of the geometry type. What I need to be able to do is pass a point to a stored procedure which returns the k nearest points (k would also be passed to the sproc, but that's easy). I've found a query at http://blogs.msdn.com/isaac/archive/2008/10/23/nearest-neighbors.aspx which gets the single nearest neighbour, but I can't figure how to extend it to find the k nearest neighbours. This is the current query - T is the table, g is the geometry field, @x is the point to search around, Numbers is a table with integers 1 to n: DECLARE @start FLOAT = 1000; WITH NearestPoints AS ( SELECT TOP(1) WITH TIES *, T.g.STDistance(@x) AS dist FROM Numbers JOIN T WITH(INDEX(spatial_index)) ON T.g.STDistance(@x) < @start*POWER(2,Numbers.n) ORDER BY n ) SELECT TOP(1) * FROM NearestPoints ORDER BY n, dist The inner query selects the nearest non-empty region and the outer query then selects the top result from that region; the outer query can easily be changed to (e.g.) SELECT TOP(20), but if the nearest region only contains one result, you're stuck with that. I figure I probably need to recursively search for the first region containing k records, but without using a table variable (which would cause maintenance problems as you have to create the table structure and it's liable to change - there're lots of fields), I can't see how.

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  • is mysql index useful on column 'state' when only doing bit-operations on the column?

    - by Geert-Jan
    I have a lot of domain entities (stored in mysql) which undergo lots of different operations. Each operation is executed from a different program. I need to keep (flow)-state for these entities which I implemented in as a long field 'flowstate' used as a bitset. to query mysql for entities which have undergone a certain operation I do something like: select * from entities where state >> 7 & 1 = 1 Indicating bit 7 (cooresponding to operation 7) has run. (<-- simplified) Anyway, I really didn't pay attention to the performance implications of this setup in the beginning, and I think I'm in a bit of trouble since queries as the above run pretty slow. What I'd like to know: Does an mysql index on 'flowstate' help at all? After all it's not a single value Mysql can quickly find using a binary sort or whatever. If it doesn't, are there any other things I could do to speed things up? . Are there special 'mask-indices' for fields with use-cases as the above? TIA, Geert-jan

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  • SQL Concurrent test update question

    - by ptoinson
    Howdy Folks, I have a SQLServer 2008 database in which I have a table for Tags. A tag is just an id and a name. The definition of the tags table looks like: CREATE TABLE [dbo].[Tag]( [ID] [int] IDENTITY(1,1) NOT NULL, [Name] [varchar](255) NOT NULL CONSTRAINT [PK_Tag] PRIMARY KEY CLUSTERED ( [ID] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ) Name is also a unique index. further I have several processes adding data to this table at a pretty rapid rate. These processes use a stored proc that looks like: ALTER PROC [dbo].[lg_Tag_Insert] @Name varchar(255) AS DECLARE @ID int SET @ID = (select ID from Tag where Name=@Name ) if @ID is null begin INSERT Tag(Name) VALUES (@Name) RETURN SCOPE_IDENTITY() end else begin return @ID end My issues is that, other than being a novice at concurrent database design, there seems to be a race condition that is causing me to occasionally get an error that I'm trying to enter duplicate keys (Name) into the DB. The error is: Cannot insert duplicate key row in object 'dbo.Tag' with unique index 'IX_Tag_Name'. This makes sense, I'm just not sure how to fix this. If it where code I would know how to lock the right areas. SQLServer is quite a different beast. First question is what is the proper way to code this 'check, then update pattern'? It seems I need to get an exclusive lock on the row during the check, rather than a shared lock, but it's not clear to me the best way to do that. Any help in the right direction will be greatly appreciated. Thanks in advance.

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  • If attacker has original data and encrypted data, can they determine the passphrase?

    - by Brad Cupit
    If an attacker has several distinct items (for example: e-mail addresses) and knows the encrypted value of each item, can the attacker more easily determine the secret passphrase used to encrypt those items? Meaning, can they determine the passphrase without resorting to brute force? This question may sound strange, so let me provide a use-case: User signs up to a site with their e-mail address Server sends that e-mail address a confirmation URL (for example: https://my.app.com/confirmEmailAddress/bill%40yahoo.com) Attacker can guess the confirmation URL and therefore can sign up with someone else's e-mail address, and 'confirm' it without ever having to sign in to that person's e-mail account and see the confirmation URL. This is a problem. Instead of sending the e-mail address plain text in the URL, we'll send it encrypted by a secret passphrase. (I know the attacker could still intercept the e-mail sent by the server, since e-mail are plain text, but bear with me here.) If an attacker then signs up with multiple free e-mail accounts and sees multiple URLs, each with the corresponding encrypted e-mail address, could the attacker more easily determine the passphrase used for encryption? Alternative Solution I could instead send a random number or one-way hash of their e-mail address (plus random salt). This eliminates storing the secret passphrase, but it means I need to store that random number/hash in the database. The original approach above does not require storage in the database. I'm leaning towards the the one-way-hash-stored-in-the-db, but I still would like to know the answer: does having multiple unencrypted e-mail addresses and their encrypted counterparts make it easier to determine the passphrase used?

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  • Can I store SQL Server sort order in a variable?

    - by Steve Weet
    I have the following SQL within a stored procedure. Is there a way to remove the IF statement and pass the 'ASC'/'DESC' option as a variable? I know I could do the query a number of different ways, or return a table and sort it externally etc. I would just like to know if I can avoid duplicating the CASE statement. IF @sortOrder = 'Desc' BEGIN SELECT * FROM #t_results ORDER BY CASE WHEN @OrderBy = 'surname' THEN surname END DESC, CASE WHEN @OrderBy = 'forename' THEN forename END DESC, CASE WHEN @OrderBy = 'fullName' THEN fullName END DESC, CASE WHEN @OrderBy = 'userId' THEN userId END DESC, CASE WHEN @OrderBy = 'MobileNumber' THEN MSISDN END DESC, CASE WHEN @OrderBy = 'DeviceStatus' THEN DeviceStatus END DESC, CASE WHEN @OrderBy = 'LastPosition' THEN LastPosition END DESC, CASE WHEN @OrderBy = 'LastAlert' THEN LastAlert END DESC, CASE WHEN @OrderBy = 'LastCommunication' THEN LastCommunication END DESC, CASE WHEN @OrderBy = 'LastPreAlert' THEN LastPreAlert END DESC END ELSE BEGIN SELECT * FROM #t_results ORDER BY CASE WHEN @OrderBy = 'surname' THEN surname END DESC, CASE WHEN @OrderBy = 'forename' THEN forename END DESC, CASE WHEN @OrderBy = 'fullName' THEN fullName END DESC, CASE WHEN @OrderBy = 'userId' THEN userId END DESC, CASE WHEN @OrderBy = 'MobileNumber' THEN MSISDN END DESC, CASE WHEN @OrderBy = 'DeviceStatus' THEN DeviceStatus END DESC, CASE WHEN @OrderBy = 'LastPosition' THEN LastPosition END DESC, CASE WHEN @OrderBy = 'LastAlert' THEN LastAlert END DESC, CASE WHEN @OrderBy = 'LastCommunication' THEN LastCommunication END DESC, CASE WHEN @OrderBy = 'LastPreAlert' THEN LastPreAlert END DESC END END

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  • Is there anyway to carry a value in php forward to a second page?

    - by Henry Aspden
    I have created a php site, and previously it was listing only products with defined values. I have now changed it to include an array of products for example all products WHERE id = "spotlights" and this works great so it means I can add new products just to the database, but I still have to add the second page manually. e.g going from the product div on the main page, through to www.example.com/spotlight_1.php Is there anyway in PHP to carry the data from my index.php e.g. the ID through to the next page? so that I can have a template product.php page, and I can use a database pull to echo the product information required. So on index.php i click on the product with ID="1" and on the product.php page, it loads the relevant data for product 1. I can write the php SQL/mySQL calls myself, its just the way to carry accross a value from the previous page which I dont understand Regards Henry p.s. all the IDs and things are stored in the database already as 1 to 3digit values e.g. 3 or or 93 or 254 Any advice as always is greatly appreciated Regards Henry

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  • Read HTML file into email

    - by cast01
    Ive written a script to send html emails and all works well. I have the email stored in a separate HTML file which is then read in usin a while loop and fgets(). However, i want to be able to pass variables into the html. For example, in a html file i may have something like.. <body> Dear Name <br/> Thank you for your recent purhcase </body> and i read this into a string like so $file = fopen($filename, "r"); while(!feof($file)) { $html.= fgets($file, 4096); } fclose ($file); I want to be able to replace "Name" in the html file by a variable and im not entirely sure on the best way to do this. I could always make my own tag and then use regex to replace that with the name once ive read the file into the string, but im wondering if there is a better/easier method to do this. (On a side note, if anyone knows whether its better to use file_get_contents instead of multiple calls to fgets, id be interested to know)

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  • Combining properties made available via webservices profile service aspnet

    - by Adam
    I really wasn't sure what the title for my question could be, so sorry if it's a bit vague. I'm working on an application that uses client application services for authentication/profile management etc. In web.config for my website, I have the following profile properties like this: <properties> <add name="FirstName" type="string" defaultValue="" customProviderData="FirstName;nvarchar"/> ... Basic things like first name, last name etc. I'm exposing properties for my client app like this: <system.web.extensions> <scripting> <webServices> <authenticationService enabled="true" requireSSL="false"/> <profileService enabled="true" readAccessProperties="UserProfile" writeAccessProperties="UserProfile"/> <roleService enabled="true"/> </webServices> </scripting> </system.web.extensions> What I'm wondering is whether it's possible to bundle all the individual profile properties into a single object for client apps to utilize? I originally had all my profile data stored as members of a single class (UserProfile) but I broke it all out so that I could use the SqlTableProfileProvider to store each field as individual columns in relevant tables. I know I can create an class with members for each type, I'm just not sure if there's an easy way to create an object with all my property values (other than assigning values to this object whenever I assign to the the standalone properties). I don't think I'm explaining this very well, so I'll try an example. Say in my website profile I have FirstName and LastName as properties. For my client application profileService I want to have one ReadAccessProperty FullName. Is there some way to automatically create FullName from the existing FirstName and LastName properties without having to also have a seperate FullName property (and manually assign data to it whenever I assign data to FirstName and LastName)?

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  • Setting Ringtone notification from SD card file

    - by sgarman
    My goal is to set the users notification sound from a file that is stored onto the SD card from with in the application. I am using this code: if(path != null){ File k = new File(path, "moment.mp3"); ContentValues values = new ContentValues(); values.put(MediaStore.MediaColumns.DATA, k.getAbsolutePath()); values.put(MediaStore.MediaColumns.TITLE, "My Song title"); values.put(MediaStore.MediaColumns.SIZE, 215454); values.put(MediaStore.MediaColumns.MIME_TYPE, "audio/mp3"); values.put(MediaStore.Audio.Media.ARTIST, "Some Artist"); values.put(MediaStore.Audio.Media.DURATION, 230); values.put(MediaStore.Audio.Media.IS_RINGTONE, false); values.put(MediaStore.Audio.Media.IS_NOTIFICATION, true); values.put(MediaStore.Audio.Media.IS_ALARM, false); values.put(MediaStore.Audio.Media.IS_MUSIC, false); values.put(MediaStore.MediaColumns.DISPLAY_NAME, "Some Name"); //Insert it into the database Uri uri = MediaStore.Audio.Media.getContentUriForPath(k.getAbsolutePath()); Uri newUri = MainActivity.this.getContentResolver().insert(uri, values); RingtoneManager.setActualDefaultRingtoneUri( MainActivity.this, RingtoneManager.TYPE_NOTIFICATION, newUri ); //RingtoneManager.setActualDefaultRingtoneUri(this, RingtoneManager.TYPE_NOTIFICATION, newUri); Toast.makeText(this, "Notification Ringtone Set", Toast.LENGTH_SHORT).show(); } When I run this on the device I keep getting the error: 06-12 15:19:36.741: ERROR/Database(2847): Error inserting is_alarm=false is_ringtone=false artist_id=35 is_music=false album_id=-1 title=My Song title duration=230 is_notification=true title_key=%D%\%%P%H%F%8%%R%<%R%B%4% mime_type=audio/mp3 date_added=1276370376 _display_name=moment.mp3 _size=215454 _data=/mnt/sdcard/Android/data/_MY APP PATH_/files/moment.mp3 06-12 15:19:36.741: ERROR/Database(2847): android.database.sqlite.SQLiteConstraintException: error code 19: constraint failed I have seen others using this technique and I can't find any documentation on which values actually need to be passed in to successfully add the file into the Android system so that it can be set as a notification.

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  • Optimizing processing and management of large Java data arrays

    - by mikera
    I'm writing some pretty CPU-intensive, concurrent numerical code that will process large amounts of data stored in Java arrays (e.g. lots of double[100000]s). Some of the algorithms might run millions of times over several days so getting maximum steady-state performance is a high priority. In essence, each algorithm is a Java object that has an method API something like: public double[] runMyAlgorithm(double[] inputData); or alternatively a reference could be passed to the array to store the output data: public runMyAlgorithm(double[] inputData, double[] outputData); Given this requirement, I'm trying to determine the optimal strategy for allocating / managing array space. Frequently the algorithms will need large amounts of temporary storage space. They will also take large arrays as input and create large arrays as output. Among the options I am considering are: Always allocate new arrays as local variables whenever they are needed (e.g. new double[100000]). Probably the simplest approach, but will produce a lot of garbage. Pre-allocate temporary arrays and store them as final fields in the algorithm object - big downside would be that this would mean that only one thread could run the algorithm at any one time. Keep pre-allocated temporary arrays in ThreadLocal storage, so that a thread can use a fixed amount of temporary array space whenever it needs it. ThreadLocal would be required since multiple threads will be running the same algorithm simultaneously. Pass around lots of arrays as parameters (including the temporary arrays for the algorithm to use). Not good since it will make the algorithm API extremely ugly if the caller has to be responsible for providing temporary array space.... Allocate extremely large arrays (e.g. double[10000000]) but also provide the algorithm with offsets into the array so that different threads will use a different area of the array independently. Will obviously require some code to manage the offsets and allocation of the array ranges. Any thoughts on which approach would be best (and why)?

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  • Password Cracking in 2010 and Beyond

    - by mttr
    I have looked a bit into cryptography and related matters during the last couple of days and am pretty confused by now. I have a question about password strength and am hoping that someone can clear up my confusion by sharing how they think through the following questions. I am becoming obsessed about these things, but need to spend my time otherwise :-) Let's assume we have an eight-digit password that consists of upper and lower-case alphabetic characters, numbers and common symbols. This means we have 8^96 ~= 7.2 quadrillion different possible passwords. As I understand there are at least two approaches to breaking this password. One is to try a brute-force attack where we try to guess each possible combination of characters. How many passwords can modern processors (in 2010, Core i7 Extreme for eg) guess per second (how many instructions does a single password guess take and why)? My guess would be that it takes a modern processor in the order of years to break such a password. Another approach would consist of obtaining a hash of my password as stored by operating systems and then search for collisions. Depending on the type of hash used, we might get the password a lot quicker than by the bruteforce attack. A number of questions about this: Is the assertion in the above sentence correct? How do I think about the time it takes to find collisions for MD4, MD5, etc. hashes? Where does my Snow Leopard store my password hash and what hashing algorithm does it use? And finally, regardless of the strength of file encryption using AES-128/256, the weak link is still my en/decryption password used. Even if breaking the ciphered text would take longer than the lifetime of the universe, a brute-force attack on my de/encryption password (guess password, then try to decrypt file, try next password...), might succeed a lot earlier than the end of the universe. Is that correct? I would be very grateful, if people could have mercy on me and help me think through these probably simple questions, so that I can get back to work.

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  • Password Confirmation Overlay

    - by Alasdair
    Hello, I'm creating a J2EE web application that uses jQuery and Ajax to help with some of the presentation for a user-friendly interface. I've done a lot of work ensuring security around persistant login cookies, and I've decided to request the password from any user that logged in using a persistant login cookie before being allowed to make any changes that could be malicious. This request would only happen once to confirm the user is who they say they are and will last throughout the session. At present, any requests that meet this criteria has their request information stored in session and then the user is forwarded to a page to confirm their password. Once confirmed, the user's original request is then performed and the requestion information removed from session. What I would like to do is avoid all this redirection and minimize what's held in session (even if it's just for a small time), thus improving usability and convenience for the user. I believe that a jQuery overlay could allow me to prompt the user for their password (if required) and then continue to submit the request if successful. I would of originally used ThickBox, but since that's now deprecated I don't see the benefit in implementing it in an application at this development stage. However, I have tried to create an overlay using jQuery but I've scrapped every attempt as I can't seem to make it all come together. My main problem is preventing the submission when the user incorrectly types a password or cancels the overlay. Desired Flow Persistant Login Sensitive Page Submit Password Confirmation Overlay [Continue Submit | (Cancel | Incorrect] I have already created JavaScript code to encrypt the password to be sent in a parameter, but all I need now is a method of controlling the overlay and how best to use Ajax for this purpose. Please ignore the fact that this is a J2EE web application when answering as it is irrelevant really. Thanks in advance, Alasdair

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  • Website --> Add Reference also creates files with pdb extensions

    - by SourceC
    Hello, Q1 Any assemblies stored in Bin directory will automatically be referenced by web application. We can add assembly reference via Website -- Add Reference or simply by copying dll into Bin folder. But I noticed that when we add reference via Website -- Add Reference, that additional files with .pdb extension are placed inside Bin. If these files are also needed, then why does reference still work even if we only place referenced dll into Bin, but not pdb files Q2 It appears that if you add a new item to web project, this class will automatically be added to project list and we can reference it from all pages in this project. So are all files added to project list automatically being referenced ? thanx EDIT: On your second question, you are adding a public class to a namespace so will be visible to other classes in that project and in that namespace. I don’t know much about assemblies, but I’d assume the reason why item( class ) added to the project is visible to other classes in that project is for the simple fact that in web project all classes get compiled into single assembly and for the fact that public classes contained in the same assembly are always visible to each other? much appreciated

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  • Double buffering C#

    - by LmSNe
    Hey, I'm trying to implement the following method: void Ball::DrawOn(Graphics g); The method should draw all previous locations(stored in a queue) of the ball and finally the current location. I don't know if that matters, but I print the previous locations using g.DrawEllipse(...) and the current location using g.FillEllipse(...). The question is, that as you could imagine there is a lot of drawing to be done and thus the display starts to flicker much. I had searched for a way to double buffer, but all I could find is these 2 ways: 1) System.Windows.Forms.Control.DoubleBuffered = true; 2) SetStyle(ControlStyles.DoubleBuffer | ControlStyles.UserPaint | ControlStyles.AllPaintingInWmPaint, true); while trying to use the first, I get the an error explaining that from in this method the Property DoubleBuffered is inaccessible due to its protection level. While I can't figure how to use the SetStyle method. Is it possible at all to double buffer while all the access I have is to the Graphics Object I get as input in the method? Thanks in Advance,

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  • Enumerating a string

    - by JamesB
    I have a status which is stored as a string of a set length, either in a file or a database. I'm looking to enumerate the possible status' I have the following type to define the possible status' Type TStatus = (fsNormal = Ord('N'),fsEditedOnScreen = Ord('O'), fsMissing = Ord('M'),fsEstimated = Ord('E'),fsSuspect = Ord('s'), fsSuspectFromOnScreen = Ord('o'),fsSuspectMissing = Ord('m'), fsSuspectEstimated = Ord('e')); Firstly is this really a good idea? or should I have a seperate const array storing the char conversions? That would mean more than one place to update. Now convert a string to a status array I have the following, but how can I check if a char is valid without looping through the enumeration? Function StrToStatus(Value : String):TStatusArray; var i: Integer; begin if Trim(Value) = '' then begin SetLength(Result,0); Exit; end; SetLength(Result,Length(Value)); for i := 1 to Length(Value) do begin Result[i] := TStatus(Value[i]); // I don't think this line is safe. end; end; AFAIK this should be fine for converting back again. Function StatusToStr(Value : TStatusArray):String; var i: Integer; begin for i := 0 to Length(Value) - 1 do Result := Result + Chr(Ord(Value[i])) end; I'm using Delphi 2007

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  • Date Filtered Collections without Functions

    - by madcapnmckay
    Hi, I have an entity similar to the below: public class Entity { public List<DateItem> PastDates { get; set; } public List<DateItem> FutureDates { get; set; } } public class DateItem { public DateTime Date { get; set; } /* * Other Properties * */ } Where PastDates and FutureDates are both mapped to the same type/table. I have been trying to find a way to have the Past and Future properties mapped automagically by Nhibernate. The closest I came was where clause on the mapping as follows HasMany(x => x.PastDates) .AsBag().Cascade .AllDeleteOrphan() .KeyColumnNames.Add("EventId").Where("Date < currentdate()") .Inverse(); Where currentdate is a UDF. I do not want to have these database specific functions if I can avoid it, mostly because i can't then test my DAL with SQLite as it doesn't support functions or stored procedures. At the moment I am building the past and future collections using Criteria and adding to my DTO manually. Anyone know how this could be achieved without using any UDFs? Many thanks,

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  • How can I fix this clang warning: "Object with +0 retain counts returned to caller where +1 (owning)

    - by mipadi
    I have a piece of Objective-C code that looks like the following: - (NSString *)copyData:(NSData *)data { NSString *path = [[[self outputDirectory] stringByAppendingPathComponent:@"archive"] stringByAppendingPathExtension:@"zip"]; NSLog(@"Copying data to %@", path); [data writeToFile:path atomically:NO]; return path; } The code is called from an initializer that looks like this: - (id)initWithData:(NSData *)data { if ((self = [super init]) != nil) { NSString *path = [self copyData:data]; // Line 41 (referenced in warning, shown below) return [self initWithContentsOfFile:path]; } return self; } When running the clang static analyzer, I get the following warnings for the path variable: Potential leak of an object allocated on line 41 and stored into 'path' Object with +0 retain counts returned to caller where +1 (owning) retain count is expected I'm confused. My understanding is that stringByAppendingPathComponent should not return an autoreleased string, so it should have a net retain count of 0. (Obviously I don't want to retain it.) I've tried altering copyData: to return the following, but it didn't get rid of the warning: return [[path retain] autorelease]; So what's the deal with this warning?

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  • SQL query to get latest record for all distinct items in a table

    - by David Buckley
    I have a table of all sales defined like: mysql> describe saledata; +-------------------+---------------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +-------------------+---------------------+------+-----+---------+-------+ | SaleDate | datetime | NO | | NULL | | | StoreID | bigint(20) unsigned | NO | | NULL | | | Quantity | int(10) unsigned | NO | | NULL | | | Price | decimal(19,4) | NO | | NULL | | | ItemID | bigint(20) unsigned | NO | | NULL | | +-------------------+---------------------+------+-----+---------+-------+ I need to get the last sale price for all items (as the price may change). I know I can run a query like: SELECT price FROM saledata WHERE itemID = 1234 AND storeID = 111 ORDER BY saledate DESC LIMIT 1 However, I want to be able to get the last sale price for all items (the ItemIDs are stored in a separate item table) and insert them into a separate table. How can I get this data? I've tried queries like this: SELECT storeID, itemID, price FROM saledata WHERE itemID IN (SELECT itemID from itemmap) ORDER BY saledate DESC LIMIT 1 and then wrap that into an insert, but it's not getting the proper data. Is there one query I can run to get the last price for each item and insert that into a table defined like: mysql> describe lastsale; +-------------------+---------------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +-------------------+---------------------+------+-----+---------+-------+ | StoreID | bigint(20) unsigned | NO | | NULL | | | Price | decimal(19,4) | NO | | NULL | | | ItemID | bigint(20) unsigned | NO | | NULL | | +-------------------+---------------------+------+-----+---------+-------+

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  • Auditing in Entity Framework.

    - by Gabriel Susai
    After going through Entity Framework I have a couple of questions on implementing auditing in Entity Framework. I want to store each column values that is created or updated to a different audit table. Rightnow I am calling SaveChanges(false) to save the records in the DB(still the changes in context is not reset). Then get the added | modified records and loop through the GetObjectStateEntries. But don't know how to get the values of the columns where their values are filled by stored proc. ie, createdate, modifieddate etc. Below is the sample code I am working on it. //Get the changed entires( ie, records) IEnumerable<ObjectStateEntry> changes = context.ObjectStateManager.GetObjectStateEntries(EntityState.Modified); //Iterate each ObjectStateEntry( for each record in the update/modified collection) foreach (ObjectStateEntry entry in changes) { //Iterate the columns in each record and get thier old and new value respectively foreach (var columnName in entry.GetModifiedProperties()) { string oldValue = entry.OriginalValues[columnName].ToString(); string newValue = entry.CurrentValues[columnName].ToString(); //Do Some Auditing by sending entityname, columnname, oldvalue, newvalue } } changes = context.ObjectStateManager.GetObjectStateEntries(EntityState.Added); foreach (ObjectStateEntry entry in changes) { if (entry.IsRelationship) continue; var columnNames = (from p in entry.EntitySet.ElementType.Members select p.Name).ToList(); foreach (var columnName in columnNames) { string newValue = entry.CurrentValues[columnName].ToString(); //Do Some Auditing by sending entityname, columnname, value } }

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  • Storing an object to use in multiple classes

    - by Aaron Sanders
    I am wondering the best way to store an object in memory that is used in a lot of classes throughout an application. Let me set up my problem for you: We have multiple databases, 1 per customer. We also have a master table and each row is detailed information about the databases such as database name, server IP it's located and a few config settings. I have an application that loops through those multiple databases and runs some updates on them. The settings I mentioned above are updated each loop iteration into memory. The application then runs through series of processes that include multiple classes using this data. The data never changes during the processes, only during the loop iteration. The variables are related to a customer, so I have them stored in a customer class. I suppose I could make all of the members shared or should I use a singleton for the customer class? I've never actually used a singleton, only read they are good in this type of situation. Are there better solutions to this type of scenario? Also, I could have plans for this application to be multithreaded later. Sorry if this is confusing. If you have questions, let me know and I will answer them. Thanks for your help.

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  • Adding shortcut for WiX file in a different fragment.

    - by matt
    I'm using heat.exe to generate fragments similar to this: <Fragment> <DirectoryRef Id="INSTALLDIR"> <Component Id="id1" Guid="*"> <File Id="fid1" KeyPath="yes" Source="SourceDir\Foo1.dll" /> </Component> <Component Id="id2" Guid="*"> <File Id="fid2" KeyPath="yes" Source="SourceDir\Foo2.dll" /> </Component> <Component Id="id3" Guid="*"> <File Id="fid3" KeyPath="yes" Source="SourceDir\Bar.exe" /> </Component> </DirectoryRef> </Fragment> <Fragment> <ComponentGroup Id="Components"> <ComponentRef Id="id1" /> <ComponentRef Id="id2" /> <ComponentRef Id="id3" /> </ComponentGroup> </Fragment> These fragments are stored in the auto-generated wxs file. I'm then adding them into my feature (in the main WiX file) like so: <ComponentGroupRef Id="Components"/> This works fine. However, I'd also like to add a shortcut to Bar.exe to my start menu. I ideally want to do this in my main wix file, with the Bar.exe component still residing in the auto-generated wxs file. How would I approach this problem without modifying the auto-generated code?

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  • Collecting high-volume video viewing data

    - by DanK
    I want to add tracking to our Flash-based media player so that we can provide analytics that show what sections of videos are being watched (at the moment, we just register a view when a video starts playing) For example, if a viewer watches the first 30 seconds of a video and then clicks away to something else, we want the data to reflect that. Likewise, if someone watches the first 10 seconds, then scrubs the timeline to the last minute of the video and watches that, we want to register viewing on the parts watched and not the middle section. My first thought was to collect up the viewing data in the player and send it all to the server at the end of a viewing session. Unfortunately, Flash does not seem to have an event that you can hook into when a viewer clicks away from the page the movie is on (probably a good thing - it would be open to abuse) So, it looks like we're going to have to make regular requests to the server as the video is playing. This is obviously going to lead to a high volume of requests when there are large numbers of simultaneous viewers. The simple approach of dumping all these 'heartbeat' events from clients to a database feels like it will quickly become unmanageable so I'm wondering whether I should be taking an approach where viewing sessions are cached in memory and flushed to database when they become inactive (based on a timeout). That way, the data could be stored as time spans rather than individual heartbeats. So, to the question - what is the best way to approach dealing with this kind of high-volume viewing data? Are there any good existing architectures/patterns? Thanks, Dan.

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  • Google Maps Terms of Service - saving some data to a database

    - by R.M.
    I've read the terms of service, and, from what I understand, I'm not allowed to store any information I retrieve from the Google Maps API. Are there any exceptions to this? More to the point, I'm planning on building an application that shows the user several points of interest (like restaurants, libraries etc) at a certain distance around a location he chooses (it can be in one city or more, depending on the distance he chooses). There are two problems: The first problem is that (at least for my country) the geocoder doesn't locate exact addresses, at best it only locates street names (but completely ignores street numbers) in larger cities. It is even worse for smaller rural areas. So the only way to accurately show the places on the map is by storing their coordinates in the database. Another problem seems to be with calculating distances. To show the points located below a certain distance from the user, it would mean I would have to use GDirections to get all distances between the user's location and the other points, to see which ones to show. That would be really slow for the user (since I also have to set a small delay between requests), and it would also send a pretty large amount of requests to google. Would I be allowed to store those distances in a database? The users would not be able to access a list of all the stored information, they would only see the names of the places, and a map with some markers on it. Thank you.

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