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• PHP not obeying my defined ETags

  - by Sam Bisbee

  What I'm doing I'm pulling an image from the database and sending it to the browser with all the proper headers - the image displays fine. I also send an ETag header, using the SHA1 of the image's content as the tag. The images are getting called semi regularly, so caching is a bit of an issue (won't kill the site, but nice to have). The Problem $_SERVER['HTTP_IF_NONE_MATCH'] is not available to me. As far as I can tell, this is because of PHP's "disobey the cache controls" life style. I can't mess with the session cache limiter, because I don't have access. But, even if I did have access, I wouldn't want to touch it: 99% of the site is under WordPress. The Environment PHP 4 (don't ask) Apache 2.2 WordPress The images live in the database (largeblog), which I can't change. Any guidance, tip/tricks, etc. would be helpful. I don't have much room to change the environmental/structural stuff. Cheers.

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• SQL Query to return maximums over decades

  - by Abraham Lincoln

  My question is the following. I have a baseball database, and in that baseball database there is a master table which lists every player that has ever played. There is also a batting table, which tracks every players' batting statistics. I created a view to join those two together; hence the masterplusbatting table. CREATE TABLE `Master` ( `lahmanID` int(9) NOT NULL auto_increment, `playerID` varchar(10) NOT NULL default '', `nameFirst` varchar(50) default NULL, `nameLast` varchar(50) NOT NULL default '', PRIMARY KEY (`lahmanID`), KEY `playerID` (`playerID`), ) ENGINE=MyISAM AUTO_INCREMENT=18968 DEFAULT CHARSET=latin1; CREATE TABLE `Batting` ( `playerID` varchar(9) NOT NULL default '', `yearID` smallint(4) unsigned NOT NULL default '0', `teamID` char(3) NOT NULL default '', `lgID` char(2) NOT NULL default '', `HR` smallint(3) unsigned default NULL, PRIMARY KEY (`playerID`,`yearID`,`stint`), KEY `playerID` (`playerID`), KEY `team` (`teamID`,`yearID`,`lgID`) ) ENGINE=MyISAM DEFAULT CHARSET=latin1; Anyway, my first query involved finding the most home runs hit every year since baseball began, including ties. The query to do that is the following.... select f.yearID, f.nameFirst, f.nameLast, f.HR from ( select yearID, max(HR) as HOMERS from masterplusbatting group by yearID )as x inner join masterplusbatting as f on f.yearID = x.yearId and f.HR = x.HOMERS This worked great. However, I now want to find the highest HR hitter in each decade since baseball began. Here is what I tried. select f.yearID, truncate(f.yearid/10,0) as decade,f.nameFirst, f.nameLast, f.HR from ( select yearID, max(HR) as HOMERS from masterplusbatting group by yearID )as x inner join masterplusbatting as f on f.yearID = x.yearId and f.HR = x.HOMERS group by decade You can see that I truncated the yearID in order to get 187, 188, 189 etc instead of 1897, 1885,. I then grouped by the decade, thinking that it would give me the highest per decade, but it is not returning the correct values. For example, it's giving me Adrian Beltre with 48 HR's in 2004 but everyone knows that Barry Bonds hit 73 HR in 2001. Can anyone give me some pointers?

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• Http Digest Authentication, Handle different browser char-sets...

  - by user160561

  Hi all, I tried to use the Http Authentication Digest Scheme with my php (apache module) based website. In general it works fine, but when it comes to verification of the username / hash against my user database i run into a problem. Of course i do not want to store the user´s password in my database, so i tend to store the A1 hashvalue (which is md5($username . ':' . $realm . ':' . $password)) in my db. This is just how the browser does it too to create the hashes to send back. The Problem: I am not able to detect if the browser does this in ISO-8859-1 fallback (like firefox, IE) or UTF-8 (Opera) or whatever. I have chosen to do the calculation in UTF-8 and store this md5 hash. Which leads to non-authentication in Firefox and IE browsers. How do you solve this problem? Just do not use this auth-scheme? Or Store a md5 Hash for each charset? Force users to Opera? (Terms of A1 refer to the http://php.net/manual/en/features.http-auth.php example.) (for digest access authentication read the according wikipedia entry)

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• How to port an Ajax CMS based on metadata in Asp.Net MVC?

  - by Maushu

  I'm maintaining a CMS where I have this feeling it was made in the age of dinosaurs (Asp.net 1.0?) and decided to upgrade it with Asp.Net MVC and jQuery. But I have some problems regarding the design/specifications of the CMS which I cannot change. The CMS The CMS uses JavaScript. Alot. As in "I don't load pages, I request new pages using Ajax and render the information using javascript" alot. Not to mention the animations, the weird horizontal apresentation of structures... anyways, besides the first page (that is the login page) every other "page" is just data requested from a WebService that comes with the website. Would MVC have any problems with this design? The Database The database is in a SQL Server 2k8 and, like the CMS, this part is also... interesting. Basically, the user can create data structures using metadata (and saved on the Structure table). These structures are saved on tables that are created (and regenerated when changed) at runtime using said metadata. I don't know how I would implement this part in MVC. The question is, can and should I convert this project to MVC? Any tips regarding the metadata and overuse of ajax?

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• How to disable mod_security2 rule (false positive) for one domain on centos 5

  - by nicholas.alipaz

  Hi I have mod_security enabled on a centos5 server and one of the rules is keeping a user from posting some text on a form. The text is legitimate but it has the words 'create' and an html <table> tag later in it so it is causing a false positive. The error I am receiving is below: [Sun Apr 25 20:36:53 2010] [error] [client 76.171.171.xxx] ModSecurity: Access denied with code 500 (phase 2). Pattern match "((alter|create|drop)[[:space:]]+(column|database|procedure|table)|delete[[:space:]]+from|update.+set.+=)" at ARGS:body. [file "/usr/local/apache/conf/modsec2.user.conf"] [line "352"] [id "300015"] [rev "1"] [msg "Generic SQL injection protection"] [severity "CRITICAL"] [hostname "www.mysite.com"] [uri "/node/181/edit"] [unique_id "@TaVDEWnlusAABQv9@oAAAAD"] and here is /usr/local/apache/conf/modsec2.user.conf (line 352) #Generic SQL sigs SecRule ARGS "((alter|create|drop)[[:space:]]+(column|database|procedure|table)|delete[[:space:]]+from|update.+set.+=)" "id:1,rev:1,severity:2,msg:'Generic SQL injection protection'" The questions I have are: What should I do to "whitelist" or allow this rule to get through? What file do I create and where? How should I alter this rule? Can I set it to only be allowed for the one domain, since it is the only one having the issue on this dedicated server or is there a better way to exclude table tags perhaps? Thanks guys

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• How can I write System preferences with Java? Can I invoke UAC?

  - by Jonas

  How can I write system preferences with Java, using Preferences.systemRoot()? I tried with: Preferences preferences = Preferences.systemRoot(); preferences.put("/myapplication/databasepath", pathToDatabase); But I got this error message: 2010-maj-29 19:02:50 java.util.prefs.WindowsPreferences openKey VARNING: Could not open windows registry node Software\JavaSoft\Prefs at root 0x80000002. Windows RegOpenKey(...) returned error code 5. Exception in thread "AWT-EventQueue-0" java.lang.SecurityException: Could not open windows registry node Software\JavaSoft\Prefs at root 0x80000002: Access denied at java.util.prefs.WindowsPreferences.openKey(Unknown Source) at java.util.prefs.WindowsPreferences.openKey(Unknown Source) at java.util.prefs.WindowsPreferences.openKey(Unknown Source) at java.util.prefs.WindowsPreferences.putSpi(Unknown Source) at java.util.prefs.AbstractPreferences.put(Unknown Source) at biz.accountia.pos.install.Setup$2.actionPerformed(Setup.java:43) I would like to do this, because I want to install an embedded JavaDB database, and let multiple users on the computer to use the same database with the application. How to solve this? Can I invoke UAC and do this as Administrator from Java? And if I log in as Administrator when writing, can I read the values with my Java application if I'm logged in as a User?

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• What's the most DRY-appropriate way to execute an SQL command?

  - by Sean U

  I'm looking to figure out the best way to execute a database query using the least amount of boilerplate code. The method suggested in the SqlCommand documentation: private static void ReadOrderData(string connectionString) { string queryString = "SELECT OrderID, CustomerID FROM dbo.Orders;"; using (SqlConnection connection = new SqlConnection(connectionString)) { SqlCommand command = new SqlCommand(queryString, connection); connection.Open(); SqlDataReader reader = command.ExecuteReader(); try { while (reader.Read()) { Console.WriteLine(String.Format("{0}, {1}", reader[0], reader[1])); } } finally { reader.Close(); } } } mostly consists of code that would have to be repeated in every method that interacts with the database. I'm already in the habit of factoring out the establishment of a connection, which would yield code more like the following. (I'm also modifying it so that it returns data, in order to make the example a bit less trivial.) private SQLConnection CreateConnection() { var connection = new SqlConnection(_connectionString); connection.Open(); return connection; } private List<int> ReadOrderData() { using(var connection = CreateConnection()) using(var command = connection.CreateCommand()) { command.CommandText = "SELECT OrderID FROM dbo.Orders;"; using(var reader = command.ExecuteReader()) { var results = new List<int>(); while(reader.Read()) results.Add(reader.GetInt32(0)); return results; } } } That's an improvement, but there's still enough boilerplate to nag at me. Can this be reduced further? In particular, I'd like to do something about the first two lines of the procedure. I don't feel like the method should be in charge of creating the SqlCommand. It's a tiny piece of repetition as it is in the example, but it seems to grow if transactions are being managed manually or timeouts are being altered or anything like that.

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• Windows Workflow Foundation: Recommendations how to design architecture

  - by Petr Felzmann

  We are running several the same ASP.NET applications (one per customer) based on our custom framework (libraries). Each application use its own database (Initial Catalog in the term of connection string). Now we would like to add workflow capability (of course 4.0 ;) to the applications. So the particular workflows will be the same for all the applications only some initial settings of each workflow can vary, e.g. in one application the e-mail will be send to the user X, but in other application to the user Y. I have several general questions how to design architecture: (1) Can be the workflow database shared for all the applications? (2) Where to host workflow engine - inside our custom windows NT service or inside IIS? What are the criteria to choose the right host? (3) How the workflow engine should communicate with applications? Should application call some WCF endpoint API configured in workflow host or vice verse - should each application provide WCF endpoint API and workflow engine will call it? How then the workflow engine will identify applications? Both cases requires probably some application identifier as a parameter in API calls? (4) We would like to also store some information to the application databases based on the workflow states. Is it possible? Thanks for suggestions!

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• Table valued function only returns CLR error

  - by Anthony

  I have read-only access to a database that was set up for a third-party, closed-source app. Once group of (hopefully) useful table functions only returns the error: Failed to initialize the Common Language Runtime (CLR) v2.0.50727 with HRESULT 0x80131522. You need to restart SQL server to use CLR integration features. (severity 16) But in theory, the third-party app should be able to use the function (either directly or indirectly), so I'm convinced I'm not setting things up right. I'm very new to SQL Server, so I could be missing something obvious. Or I could be missing something really slight, I have no idea. Here is an example of a query that returns the above error: SELECT * FROM dbo.UncompressDataDateRange(4,'Apr 24 2010 12:00AM','Apr 30 2010 12:00AM') Where the function takes three parameters: The Data Set (int) -- basically the data has 6 classifications, and the giant table this should be pulling from has a column to indicate which is which. startDate (smalldatetime) endDate (smalldatetime) There are other, similar functions that expand on the same idea, all returning the same error. Quick Note: I'm not sure if this is relevant, but I was able to connect to the database via SQL Studio (but without the privs to script the functions as code), and a checked the dependency for the above sample function. It turns out that it is a dependent of a view that I have gotten to work, and that view is dependent of the larger, much-hairier data-table. This makes me think I should somehow be pointing the function at the results of the view, but I'm not seeing any documentation that shows how that is done.

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• DataGridView not displaying a row after it is created

  - by joslinm

  Hi, I'm using Visual Studio 10 and I just created a Database using SQL Server CE. Within it, I made a table CSLDataTable and that automatically created a CSLDataSet & CSLDataTableTableAdapter. The three variables were automatically created in my MainWindow.cs class: cSLDataSet cSLDataTableTableAdapter cSLDataTableBindingSource I have added a DataGridView in my Form called dataGridView and datasource cSLDataTableBindingSource. In my MainWindow(), I tried adding a row as a test: public MainWindow() { InitializeComponent(); CSLDataSet.CSLDataTableRow row = cSLDataSet.CSLDataTable.NewCSLDataTableRow(); row.File_ = "file"; row.Artist = "artist11"; row.Album = "album"; row.Save_Structure = "save"; row.Sent = false; row.Error = true; row.Release_Format = "release"; row.Bit_Rate = "bitrate.."; row.Year = "year"; row.Physical_Format = "format"; row.Bit_Format = "bitformat"; row.File_Path = "File!!path"; row.Site_Origin = "what"; cSLDataSet.CSLDataTable.Rows.Add(row); cSLDataSet.AcceptChanges(); cSLDataTableTableAdapter.Fill(cSLDataSet.CSLDataTable); cSLDataTableTableAdapter.Update(cSLDataSet); dataGridView.Refresh(); dataGridView.Update(); } In regards to the DataSet methods I tried calling, I had been trying to find a "correct" way to interact with the adapter, dataset, and datatable to successfully show the row, but to no avail. I'm rather new to using SQL Server CE Database, and read a lot of the MSDN sites & thought I was on the right track, but I've had no luck. The DataGridView shows the headers correctly, but that new row does not show up.

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• When developing a Microsoft Office Add-In (for Word), is it possible to store hidden metadata inform

  - by leftend

  I am trying to store metadata (basically a unique id) along with each cell of a table in a Word document. Currently, for the add-in I'm developing, I am querying the database, and building a table inside the Word document using the data that is retrieved. I want to be able to save any of the user's edits to the document, and persist it back to the database. My initial thought was to store a unique id along with each cell in the table so that I would be able to tell which records to update. I would also like to store some sort of "isChanged" flag within each cell so that I could tell which cells were changed. I found that I could add the needed information into the "ID" property of the cell - however, that information was not retained if the user saved the document, closed it, and re-opened it. I then tried storing the data by adding a data to the "Fields" collection - but that did not work and threw a runtime error. Here is the code that I tried: object t1 = Word.WdFieldType.wdFieldEmpty; object val = "myValue: " + counter; object preserveFormatting = true; tbl.Cell(i, j).Range.Fields.Add(tbl.Cell(i, j).Range, ref t1, ref val, ref preserveFormatting); This compiles fine, but throws this runtime error "This command is not available". So, is this possible at all? Or am I headed in the wrong direction? Thanks in advance.

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• Generate an ID via COM interop

  - by Erik van Brakel

  At the moment, we've got an unmaintanable ball of code which offers an interface to a third party application. The third party application has a COM assembly which MUST be used to create new entries. This process involves two steps: generate a new object (basically an ID), and update that object with new field values. Because COM interop is so slow, we only use that to generate the ID (and related objects) in the database. The actual update is done using a regular SQL query. What I am trying to figure out if it's possible to use NHibernate to do some of the heavy lifting for us, without bypassing the COM assembly. Here's the code for saving something to the database as I envision it: using(var s = sessionFactory.OpenSession()) using(var t = s.BeginTransaction()) { MyEntity entity = new MyEntity(); s.Save(entity); t.Commit(); } Regular NH code I'd say. Now, this is where it gets tricky. I think I have to supply my own implementation of NHibernate.Id.IIdentifierGenerator which calls the COM assembly in the Generate method. That's not a problem. What IS a problem is that the COM assembly requires initialisation, which does take a bit of time. It also doesn't like multiple instances in the same process, for some reason. What I would like to know is if there's a way to properly access an external service in the generator code. I'm free to use any technique I want, so if it involves something like an IoC container that's no problem. The thing I am looking for is where exactly to hook-up my code so I can access the things I need in my generator, without having to resort to using singletons or other nasty stuff.

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• Mysql InnoDB performance optimization and indexing

  - by Davide C

  Hello everybody, I have 2 databases and I need to link information between two big tables (more than 3M entries each, continuously growing). The 1st database has a table 'pages' that stores various information about web pages, and includes the URL of each one. The column 'URL' is a varchar(512) and has no index. The 2nd database has a table 'urlHops' defined as: CREATE TABLE urlHops ( dest varchar(512) NOT NULL, src varchar(512) DEFAULT NULL, timestamp timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP, KEY dest_key (dest), KEY src_key (src) ) ENGINE=InnoDB DEFAULT CHARSET=latin1 Now, I need basically to issue (efficiently) queries like this: select p.id,p.URL from db1.pages p, db2.urlHops u where u.src=p.URL and u.dest=? At first, I thought to add an index on pages(URL). But it's a very long column, and I already issue a lot of INSERTs and UPDATEs on the same table (way more than the number of SELECTs I would do using this index). Other possible solutions I thought are: -adding a column to pages, storing the md5 hash of the URL and indexing it; this way I could do queries using the md5 of the URL, with the advantage of an index on a smaller column. -adding another table that contains only page id and page URL, indexing both columns. But this is maybe a waste of space, having only the advantage of not slowing down the inserts and updates I execute on 'pages'. I don't want to slow down the inserts and updates, but at the same time I would be able to do the queries on the URL efficiently. Any advice? My primary concern is performance; if needed, wasting some disk space is not a problem. Thank you, regards Davide

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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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• Custom rowsetClass does not return values

  - by Wesley

  Hi, I'm quite new to Zend and the database classes from it. I'm having problems mapping a Zend_Db_Table_Row_Abstract to my rows. The problem is that whenever I try to map it to a class (Job) that extends the Zend_Db_Table_Row_Abstract class, the database data is not receivable anymore. I'm not getting any errors, trying to get data simply returns null. Here is my code so far: Jobs: class Jobs extends Zend_Db_Table_Abstract { protected $_name = 'jobs'; protected $_rowsetClass = "Job"; public function getActiveJobs() { $select = $this->select()->where('jobs.jobDateOpen < UNIX_TIMESTAMP()')->limit(15,0); $rows = $this->fetchAll($select); return $rows; } } Job: class Job extends Zend_Db_Table_Row_Abstract { public function getCompanyName() { //Gets the companyName } } Controller: $oJobs = new Jobs(); $aActiveJobs = $oJobs->getActiveJobs(); foreach ($aActiveJobs as $value) { var_dump($value->jobTitle); } When I remove the "protected $_rowsetClass = "Job";" line, so that the table row is not mapped to my own class, I get all the jobTitles perfectly. What am I doing wrong here? Thanks in advance, Wesley

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• Setting nested object to null when selected option has empty value

  - by Javi

  Hello, I have a Class which models a User and another which models his country. Something like this: public class User{ private Country country; //other attributes and getter/setters } public class Country{ private Integer id; private String name; //other attributes and getter/setters } I have a Spring form where I have a combobox so the user can select his country or can select the undefined option to indicate he doen't want to provide this information. So I have something like this: <form:select path="country"> <form:option value="">-Select one-</form:option> <form:options items="${countries}" itemLabel="name" itemValue="id"/> </form:select> In my controller I get the autopopulated object with the user information and I want to have country set to null when the "-Select one-" option has been selected. So I have set a initBinder with a custom editor like this: @InitBinder protected void initBinder(WebDataBinder binder) throws ServletException { binder.registerCustomEditor(Country.class, "country", new CustomCountryEditor()); } and my editor do something like this: public class CustomCountryEditor(){ @Override public String getAsText() { //I return the Id of the country } @Override public void setAsText(String str) { //I search in the database for a country with id = new Integer(str) //and set country to that value //or I set country to null in case str == null } } When I submit the form it works because when I have country set to null when I have selected "-Select one-" option or the instance of the country selected. The problem is that when I load the form I have a method like the following one to load the user information. @ModelAttribute("user") public User getUser(){ //loads user from database } The object I get from getUser() has country set to a specific country (not a null value), but in the combobox is not selected any option. I've debugged the application and the CustomCountryEditor works good when setting and getting the text, thoughgetAsText method is called for every item in the list "countries" not only for the "country" field. Any idea? Is there a better way to set null the country object when I select no country option in the combobox? Thanks

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• Python many-to-one mapping (creating equivalence classes)

  - by Adam Matan

  Hi, I have a project of converting one database to another. One of the original database columns defines the row's category. This coulmn should be mapepd to a new category in the new databse. For example, let's assume the original categories are:parrot, spam, cheese_shop, Cleese, Gilliam, Palin Now that's a little verbose for me, And I want to have these rows categorized as sketch, actor - That is, define all the sketches and all the actors as two equivalence classes. >>> monty={'parrot':'sketch', 'spam':'sketch', 'cheese_shop':'sketch', 'Cleese':'actor', 'Gilliam':'actor', 'Palin':'actor'} >>> monty {'Gilliam': 'actor', 'Cleese': 'actor', 'parrot': 'sketch', 'spam': 'sketch', 'Palin': 'actor', 'cheese_shop': 'sketch'} That's quite awkward- I would prefer having something like: monty={ ('parrot','spam','cheese_shop'): 'sketch', ('Cleese', 'Gilliam', 'Palin') : 'actors'} But this, of course, sets the entire tuple as a key: >>> monty['parrot'] Traceback (most recent call last): File "<pyshell#29>", line 1, in <module> monty['parrot'] KeyError: 'parrot' Any ideas how to create an elegant many-to-one dictionary in Python? Thanks, Adam

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• problem with mysql character set & GWT

  - by Ehsan Khodarahmi

  Hi I've a SmartGWT application which interacts with a mysql database using rpc services. Suppose it as a simple form with a textbox & two save & load buttons. My database & tables & all fields collation is utf8_persian_ci. All java source files & module html & xml files have saved with utf8 character set. & also I've a meta tag in module html file which contains my form : <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> my application works correctly in eclipse develpment mode & also in my local tomcat server. Then i put it on remote server (I compress it using jar.exe into a war file with -cvf flag & then upload it using my server's plesk control panel). In this mode, when I load data from a mysql table (load a record from any table), data will load into my form with no problem, but when I want to save some data (in persian language), mysql just writes some ? (question sign) in characteristic table fields. Any idea ?

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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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• How to identify a particular entity's Session Factory with Fluent NHibernate and Multiple Databases

  - by Trevor

  I've already asked this question as part of an answer to another question ( see http://stackoverflow.com/questions/2655861/fluent-nhibernate-multiple-databases ) but thought it better to ask again here. My problem is this: I'm using Fluent NHibernate. My application uses multiple databases. Each database has its own entities registered (mapped) against it. The result is that have multiple Session Factories, each one relating to a single DB, and each 'containing' its own set of mapped entities. For loading entities I've created a generic Factory class that provides some standard load methods usable for any registered entity (in any DB). The problem is: The load methods need to use the correct session factory for the entity class I'm busy dealing with. How would I determine which session factory I need to use? I have all the Session Factories 'on hand' (and indexed by database name), I just need a way, knowing just the type of Entity I'm about to load, of choosing the right Session Factory to use. For example: public IBaseBusinessObject CreatePopulatedInstance(Type boType, Guid instanceKey) { IBaseBusinessObject result = null; ISessionFactory sessionFactory = GetSessionFactory(boType); using (ISession session = sessionFactory.OpenSession()) { using (session.BeginTransaction()) { result = (IBaseBusinessObject)session.Get(boType, instanceKey); } } return result; } What needs to go on in GetSessionFactory(boType) ? Thanks for reading!

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• Communication between EJB3 Instances (JEE inter-bean communication) possible?

  - by Hank

  I'm designing a part of a JEE6 application, consisting of EJB3 beans. Part of the requirements are multiple parallel (say a few hundred) long running (over days) database hunts. Individual hunts have different search parameters (start time, end time, query filter). Parameters may get changed over time. Currently I'm thinking of the following: SearchController (Stateless Session Bean) formulates a set of search parameters, sends it off to a SearchListener via JMS SearchListener (Message Driven Bean) receives search parameters, instantiates a SearchWorker with the parameters SearchWorker (SLSB) hunts repeatedly through the database; when it finds something, the result is sent off via JMS, and the search continues; when the given 'end-time' has reached, it ends What I'm wondering now: Is there a problem, with EJB3 instances running for days? (Other than that I need to be able to deal with container restarts...) How do I know how many and which EJB instances of SearchWorker are currently running? Is it possible to communicate with them individually (similar to sending a System V signal to a unix process), e.g. to send new parameters, to end an instance, etc..

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• Computing complex math equations in python

  - by dassouki

  Are there any libraries or techniques that simplify computing equations ? Take the following two examples: F = B * { [ a * b * sumOf (A / B ''' for all i ''' ) ] / [ sumOf(c * d * j) ] } where: F = cost from i to j B, a, b, c, d, j are all vectors in the format [ [zone_i, zone_j, cost_of_i_to_j], [..]] This should produce a vector F [ [1,2, F_1_2], ..., [i,j, F_i_j] ] T_ij = [ P_i * A_i * F_i_j] / [ SumOf [ Aj * F_i_j ] // j = 1 to j = n ] where: n is the number of zones T = vector [ [1, 2, A_1_2, P_1_2], ..., [i, j, A_i_j, P_i_j] ] F = vector [1, 2, F_1_2], ..., [i, j, F_i_j] so P_i would be the sum of all P_i_j for all j and Aj would be sum of all P_j for all i I'm not sure what I'm looking for, but perhaps a parser for these equations or methods to deal with multiple multiplications and products between vectors? To calculate some of the factors, for example A_j, this is what i use from collections import defaultdict A_j_dict = defaultdict(float) for A_item in TG: A_j_dict[A_item[1]] += A_item[3] Although this works fine, I really feel that it is a brute force / hacking method and unmaintainable in the case we want to add more variables or parameters. Are there any math equation parsers you'd recommend? Side Note: These equations are used to model travel. Currently I use excel to solve a lot of these equations; and I find that process to be daunting. I'd rather move to python where it pulls the data directly from our database (postgres) and outputs the results into the database. All that is figured out. I'm just struggling with evaluating the equations themselves. Thanks :)

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• Saving multiple objects in a single call in rails

  - by CaptnCraig

  I have a method in rails that is doing something like this: a = Foo.new("bar") a.save b = Foo.new("baz") b.save ... x = Foo.new("123", :parent_id => a.id) x.save ... z = Foo.new("zxy", :parent_id => b.id) z.save The problem is this takes longer and longer the more entities I add. I suspect this is because it has to hit the database for every record. Since they are nested, I know I can't save the children before the parents are saved, but I would like to save all of the parents at once, and then all of the children. It would be nice to do something like: a = Foo.new("bar") b = Foo.new("baz") ... saveall(a,b,...) x = Foo.new("123", :parent_id => a.id) ... z = Foo.new("zxy", :parent_id => b.id) saveall(x,...,z) That would do it all in only two database hits. Is there an easy way to do this in rails, or am I stuck doing it one at a time?

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• Extensionless URLs in IIS 6

  - by Jason Marsell

  My client has asked me to build a personalized URL system so that they can send out really short URLs in postcards to customers like this: www.client.com/JasonSmith03 www.client.com/TonyAdams With these URLs, I need IIS 6 to trap the incoming request and pass that “JasonSmith03” token to my database to determine which landing page to redirect them to. I’d love to use an HttpHandler or HttpModule but they both look like they require an file extension (.aspx) in the URL. Wildcard mapping will chew up every incoming request and that’s ridiculous. ISAPI filters are just text routing files, so I can’t employ logic to call the database. According to Scott Guthrie, this would be cake if I had IIS 7, but I don’t. Can this be done using MVC? I’ve been working with MVP for the last few years, so I haven’t done any MVC and routing. I thought I remembered that MVC has the ability to use REST-style extensionless URLs. I’d be more than happy to have these personalized URLs land on a site that’s built in MVC, if it will work. Thank you!

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• Hadoop Map/Reduce - simple use example to do the following...

  - by alexeypro

  I have MySQL database, where I store the following BLOB (which contains JSON object) and ID (for this JSON object). JSON object contains a lot of different information. Say, "city:Los Angeles" and "state:California". There are about 500k of such records for now, but they are growing. And each JSON object is quite big. My goal is to do searches (real-time) in MySQL database. Say, I want to search for all JSON objects which have "state" to "California" and "city" to "San Francisco". I want to utilize Hadoop for the task. My idea is that there will be "job", which takes chunks of, say, 100 records (rows) from MySQL, verifies them according to the given search criteria, returns those (ID's) which qualify. Pros/cons? I understand that one might think that I should utilize simple SQL power for that, but the thing is that JSON object structure is pretty "heavy", if I put it as SQL schemas, there will be at least 3-5 tables joins, which (I tried, really) creates quite a headache, and building all the right indexes eats RAM faster than I one can think. ;-) And even then, every SQL query has to be analyzed to be utilizing the indexes, otherwise with full scan it literally is a pain. And with such structure we have the only way "up" is just with vertical scaling. But I am not sure it's the best option for me, as I see how JSON objects will grow (the data structure), and I see that the number of them will grow too. :-) Help? Can somebody point me to simple examples of how this can be done? Does it make sense at all? Am I missing something important? Thank you.

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