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  • Write binary stream to browser using PHP

    - by Dave Jarvis
    Background Trying to stream a PDF report written using iReport through PHP to the browser. The general problem is: how do you write binary data to the browser using PHP? Working Code The following code does the job, but (for many reasons) it is not as efficient as it should be (the code writes a file then sends the file contents the browser). // Load the MySQL database driver. // java( 'java.lang.Class' )->forName( 'com.mysql.jdbc.Driver' ); // Attempt a database connection. // $conn = java( 'java.sql.DriverManager' )->getConnection( "jdbc:mysql://localhost:3306/climate?user=$user&password=$password" ); // Extract parameters. // $params = new java('java.util.HashMap'); $params->put('DistrictCode', '101'); $params->put('StationCode', '0066'); $params->put('CategoryCode', '010'); // Use the fill manager to produce the report. // $fm = java('net.sf.jasperreports.engine.JasperFillManager'); $pm = $fm->fillReport($report, $params, $conn); header('Cache-Control: no-cache private'); header('Content-Description: File Transfer'); header('Content-Disposition: attachment, filename=climate-report.pdf'); header('Content-Type: application/pdf'); header('Content-Transfer-Encoding: binary'); header('Content-Length: ' . strlen( $result ) ); $path = realpath( "." ) . "/output.pdf"; $em = java('net.sf.jasperreports.engine.JasperExportManager'); $result = $em->exportReportToPdfFile($pm,$path); readfile( $path ); $conn->close(); Non-working Code To remove the slight redundancy (i.e., write directly to the browser), the following code looks like it should work, but it does not: $em = java('net.sf.jasperreports.engine.JasperExportManager'); $result = $em->exportReportToPdf($pm); header('Content-Length: ' . strlen( $result ) ); echo $result; Content is sent to the browser, but the file is corrupt (it begins with the PDF header) and cannot be read by any PDF reader. Question How can I take out the middle step of writing to the file and write directly to the browser so that the PDF is not corrupted? Thank you!

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  • HTML / PHP from

    - by user317128
    I am trying to code an all in one HTML/PHP contact from with error checking. When I load this file in my browser there is not HTML. I am a newb php programmer so most likely forgot something pretty obvious. <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>All In One Feedback Form</title> </head> <body> <? $form_block = " <input type=\"hidden\" name=\"op\" value=\"ds\"> <form method=\"post\" action=\"$server[PHP_SELF]\"> <p>Your name<br /> <input name=\"sender_name\" type=\"text\" size=30 value=\"$_POST[sender_name]\" /></p> <p>Email<br /> <input name=\"sender_email\" type=\"text\" size=30 value=\"$_POST[sender_email]\"/></p> <p>Message<br /> <textarea name=\"message\" cols=30 rows=5 value=\"$_POST[message]\"></textarea></p> <input name=\"submit\" type=\"submit\" value=\"Send This Form\" /> </form>"; if ($_POST[op] != "ds") { //they see this form echo "$form_block"; } else if ($_POST[op] == "ds") { if ($_POST[sender_name] == "") { $name_err = "Please enter your name<br>"; $send = "no"; } if ($_POST[sender_email] == "ds") { $email_err = "Please enter your email<br>"; $send = "no"; } if ($_POST[message] == "ds") { $message_err = "please enter message<br>"; $send = "no"; } if ($send != "no") { //its ok to send $to = "[email protected]"; $subject = "All in one web site feed back"; $mailheaders = "From: website <some email [email protected]> \n"; $mailheaders .= "Reply-To: $_POST[sender_email]\n"; $msg = "Email sent from this site www.ccccc.com\n"; $msg .= "Senders name: $_POST[senders_name]\n"; $msg .= "Sender's E-Mail: $_POST[sender_email]\n"; $msg .= "Message: $_POST[message]\n\n"; mail($to, $subject, $msg, $mailheaders); echo "<p>Mail has been sent</p>"; } else if ($send == "no") { echo "$name_err"; echo "$email_err"; echo "$message_err"; echo "$form_block"; } } ?> </body> </html> FYI I am trying the example from a book named PHP 6 Fast and Easy Wed Development

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  • Oracle sample data problems

    - by Jay
    So, I have this java based data trasformation / masking tool, which I wanted to test out on Oracle 10g. The good part with Oracle 10g is that you get a load of sample schemas with half a million records in some. The schemas are : SH, OE, HR, IX and etc. So, I installed 10g, found out that the installation scripts are under ORACLE_HOME/demo/scripts. I customized these scripts a bit to run in batch mode. That solves one half of my requirement - to create source data for my testing my data transformation software. The second half of the requirement is that I create the same schemas under different names (TR_HR, TR_OE and so on...) without any data. These schemas would represent my target schemas. So, in short, my software would pick up data from a table in a schema and load it up in to the same table in a different schema. Now, I have two issues in creating my target schema and emptying it. I would like this in a batch job. But the oracle scripts you get, the sample schema names are not configurable. So, I tried creating a script, replacing OE with TR_OE, HR with TR_HR and so on. However, this approach is kind of irritating coz the sample schemas are kind of complicated in the way they are created; Oracle creates synonyms, views, materialized views, data types and lot of weird stuff. I would like the target schemas (TR_HR, TR_OE,...) to be empty. But some of the schemas have circular references, which would not allow me to delete data. The only work around seems to be removing certain foreign keys, deleting data and then adding the constraints back. Is there any easy way to all this, without all this fuss? I would need a complicated data set for my testing (complicated as in tables with triggers, multiple hierarchies.. for instance.. a child table that has children up to 5 levels, a parent table that refers to an IOT table and an IOT table that refers to a non-IOT table etc..). The sample schemas are just about perfect from a data set perspective. The only challenge I see is in automating this whole process of loading up the source schemas, and then creating the target schemas and emptying them. Appreciate your help and suggestions.

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  • Find optimal/good-enough strategy and AI for the game 'Proximity'?

    - by smci
    'Proximity' is a strategy game of territorial domination similar to Othello, Go and Risk. Two players, uses a 10x12 hex grid. Game invented by Brian Cable in 2007. Seems to be a worthy game for discussing a) optimal algorithm then b) how to build an AI. Strategies are going to be probabilistic or heuristic-based, due to the randomness factor, and the insane branching factor (20^120). So it will be kind of hard to compare objectively. A compute time limit of 5s per turn seems reasonable. Game: Flash version here and many copies elsewhere on the web Rules: here Object: to have control of the most armies after all tiles have been placed. Each turn you received a randomly numbered tile (value between 1 and 20 armies) to place on any vacant board space. If this tile is adjacent to any ally tiles, it will strengthen each tile's defenses +1 (up to a max value of 20). If it is adjacent to any enemy tiles, it will take control over them if its number is higher than the number on the enemy tile. Thoughts on strategy: Here are some initial thoughts; setting the computer AI to Expert will probably teach a lot: minimizing your perimeter seems to be a good strategy, to prevent flips and minimize worst-case damage like in Go, leaving holes inside your formation is lethal, only more so with the hex grid because you can lose armies on up to 6 squares in one move low-numbered tiles are a liability, so place them away from your main territory, near the board edges and scattered. You can also use low-numbered tiles to plug holes in your formation, or make small gains along the perimeter which the opponent will not tend to bother attacking. a triangle formation of three pieces is strong since they mutually reinforce, and also reduce the perimeter Each tile can be flipped at most 6 times, i.e. when its neighbor tiles are occupied. Control of a formation can flow back and forth. Sometimes you lose part of a formation and plug any holes to render that part of the board 'dead' and lock in your territory/ prevent further losses. Low-numbered tiles are obvious-but-low-valued liabilities, but high-numbered tiles can be bigger liabilities if they get flipped (which is harder). One lucky play with a 20-army tile can cause a swing of 200 (from +100 to -100 armies). So tile placement will have both offensive and defensive considerations. Comment 1,2,4 seem to resemble a minimax strategy where we minimize the maximum expected possible loss (modified by some probabilistic consideration of the value ß the opponent can get from 1..20 i.e. a structure which can only be flipped by a ß=20 tile is 'nearly impregnable'.) I'm not clear what the implications of comments 3,5,6 are for optimal strategy. Interested in comments from Go, Chess or Othello players. (The sequel ProximityHD for XBox Live, allows 4-player -cooperative or -competitive local multiplayer increases the branching factor since you now have 5 tiles in your hand at any given time, of which you can only play one. Reinforcement of ally tiles is increased to +2 per ally.)

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  • Cannot populate form with ajax and populate jquery plugin

    - by Azriel_
    I'm trying to populate a form with jquery's populate plugin, but using $.ajax The idea is to retrieve data from my database according to the id in the links (ex of link: get_result_edit.php?id=34), reformulate it to json, return it to my page and fill up the form up with the populate plugin. But somehow i cannot get it to work. Any ideas: here's the code: $('a').click(function(){ $('#updatediv').hide('slow'); $.ajax({ type: "GET", url: "get_result_edit.php", success: function(data) { var $response=$(data); $('#form1').populate($response); } }); $('#updatediv').fadeIn('slow'); return false; whilst the php file states as follow: <?php $conn = new mysqli('localhost', 'XXXX', 'XXXXX', 'XXXXX'); @$query = 'Select * FROM news WHERE id ="'.$_GET['id'].'"'; $stmt = $conn->query($query) or die ($mysql->error()); if ($stmt) { $results = $stmt->fetch_object(); // get database data $json = json_encode($results); // convert to JSON format echo $json; } ?> Now first thing is that the mysql returns a null in this way: is there something wrong with he declaration of the sql statement in the $_GET part? Second is that even if i put a specific record to bring up, populate doesn't populate. Update: I changed the populate library with the one called "PHP jQuery helper functions" and the difference is that finally it says something. finally i get an error saying NO SUCH ELEMENT AS i wen into the library to have a look and up comes the following function function populateFormElement(form, name, value) { // check that the named element exists in the form var name = name; // handle non-php naming var element = form[name]; if(element == undefined) { debug('No such element as ' + name); return false; } // debug options if(options.debug) { _populate.elements.push(element); } } Now looking at it one can see that it should print out also the name, but its not printing it out. so i'm guessing that retrieving the name form the json is not working correctly. Link is at http://www.ocdmonline.org/michael/edit%5Fnews.php with username: Testing and pass:test123 Any ideas?

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  • Possible uncommitted transactions causing "System.Data.SqlClient.SqlException: Timeout expired" erro

    - by Michael
    My application requires a user to log in and allows them to edit a list of things. However, it seems that if the same user always logs in and out and edits the list, this user will run into a "System.Data.SqlClient.SqlException: Timeout expired." error. I've read comments about increasing the timeout period but I've also read a comment about it possibly caused by uncommitted transactions. And I do have one going in the application. I'll provide the code I'm working with and there is an IF statement in there that I was a little iffy about but it seemed like a reasonable thing to do. I'll just go over what's going on here, there is a list of objects to update or add into the database. New objects created in the application are given an ID of 0 while existing objects have their own ID's generated from the DB. If the user chooses to delete some objects, their IDs are stored in a separate list of Integers. Once the user is ready to save their changes, the two lists are passed into this method. By use of the IF statement, objects with ID of 0 are added (using the Add stored procedure) and those objects with non-zero IDs are updated (using the Update stored procedure). After all this, a FOR loop goes through all the integers in the "removal" list and uses the Delete stored procedure to remove them. A transaction is used for all this. Public Shared Sub UpdateSomethings(ByVal SomethingList As List(Of Something), ByVal RemovalList As List(Of Integer)) Using DBConnection As New SqlConnection(conn) DBConnection.Open() Dim MyTransaction As SqlTransaction MyTransaction = DBConnection.BeginTransaction() Try For Each SomethingItem As Something In SomethingList Using MyCommand As New SqlCommand() MyCommand.Connection = DBConnection If SomethingItem.ID > 0 Then MyCommand.CommandText = "UpdateSomething" Else MyCommand.CommandText = "AddSomething" End If MyCommand.Transaction = MyTransaction MyCommand.CommandType = CommandType.StoredProcedure With MyCommand.Parameters If MyCommand.CommandText = "UpdateSomething" Then .Add("@id", SqlDbType.Int).Value = SomethingItem.ID End If .Add("@stuff", SqlDbType.Varchar).Value = SomethingItem.Stuff End With MyCommand.ExecuteNonQuery() End Using Next For Each ID As Integer In RemovalList Using MyCommand As New SqlCommand("DeleteSomething", DBConnection) MyCommand.Transaction = MyTransaction MyCommand.CommandType = CommandType.StoredProcedure With MyCommand.Parameters .Add("@id", SqlDbType.Int).Value = ID End With MyCommand.ExecuteNonQuery() End Using Next MyTransaction.Commit() Catch ex As Exception MyTransaction.Rollback() 'Exception handling goes here End Try End Using End Sub There are three stored procedures used here as well as some looping so I can see how something can be holding everything up if the list is large enough. Other users can log in to the system at the same time just fine though. I'm using Visual Studio 2008 to debug and am using SQL Server 2000 for the DB.

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  • Historical / auditable database

    - by Mark
    Hi all, This question is related to the schema that can be found in one of my other questions here. Basically in my database I store users, locations, sensors amongst other things. All of these things are editable in the system by users, and deletable. However - when an item is edited or deleted I need to store the old data; I need to be able to see what the data was before the change. There are also non-editable items in the database, such as "readings". They are more of a log really. Readings are logged against sensors, because its the reading for a particular sensor. If I generate a report of readings, I need to be able to see what the attributes for a location or sensor was at the time of the reading. Basically I should be able to reconstruct the data for any point in time. Now, I've done this before and got it working well by adding the following columns to each editable table: valid_from valid_to edited_by If valid_to = 9999-12-31 23:59:59 then that's the current record. If valid_to equals valid_from, then the record is deleted. However, I was never happy with the triggers I needed to use to enforce foreign key consistency. I can possibly avoid triggers by using the extension to the "PostgreSQL" database. This provides a column type called "period" which allows you to store a period of time between two dates, and then allows you to do CHECK constraints to prevent overlapping periods. That might be an answer. I am wondering though if there is another way. I've seen people mention using special historical tables, but I don't really like the thought of maintainling 2 tables for almost every 1 table (though it still might be a possibility). Maybe I could cut down my initial implementation to not bother checking the consistency of records that aren't "current" - i.e. only bother to check constraints on records where the valid_to is 9999-12-31 23:59:59. Afterall, the people who use historical tables do not seem to have constraint checks on those tables (for the same reason, you'd need triggers). Does anyone have any thoughts about this? PS - the title also mentions auditable database. In the previous system I mentioned, there is always the edited_by field. This allowed all changes to be tracked so we could always see who changed a record. Not sure how much difference that might make. Thanks.

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  • Are "EXC_BREAKPOINT (SIGTRAP)" exceptions caused by debugging breakpoints?

    - by Dennis
    I have a multithreaded app that is very stable on all my test machines and seems to be stable for almost every one of my users (based on no complaints of crashes). The app crashes frequently for one user, though, who was kind enough to send crash reports. All the crash reports (~10 consecutive reports) look essentially identical: Date/Time: 2010-04-06 11:44:56.106 -0700 OS Version: Mac OS X 10.6.3 (10D573) Report Version: 6 Exception Type: EXC_BREAKPOINT (SIGTRAP) Exception Codes: 0x0000000000000002, 0x0000000000000000 Crashed Thread: 0 Dispatch queue: com.apple.main-thread Thread 0 Crashed: Dispatch queue: com.apple.main-thread 0 com.apple.CoreFoundation 0x90ab98d4 __CFBasicHashRehash + 3348 1 com.apple.CoreFoundation 0x90adf610 CFBasicHashRemoveValue + 1264 2 com.apple.CoreText 0x94e0069c TCFMutableSet::Intersect(__CFSet const*) const + 126 3 com.apple.CoreText 0x94dfe465 TDescriptorSource::CopyMandatoryMatchableRequest(__CFDictionary const*, __CFSet const*) + 115 4 com.apple.CoreText 0x94dfdda6 TDescriptorSource::CopyDescriptorsForRequest(__CFDictionary const*, __CFSet const*, long (*)(void const*, void const*, void*), void*, unsigned long) const + 40 5 com.apple.CoreText 0x94e00377 TDescriptor::CreateMatchingDescriptors(__CFSet const*, unsigned long) const + 135 6 com.apple.AppKit 0x961f5952 __NSFontFactoryWithName + 904 7 com.apple.AppKit 0x961f54f0 +[NSFont fontWithName:size:] + 39 (....more text follows) First, I spent a long time investigating [NSFont fontWithName:size:]. I figured that maybe the user's fonts were screwed up somehow, so that [NSFont fontWithName:size:] was requesting something non-existent and failing for that reason. I added a bunch of code using [[NSFontManager sharedFontManager] availableFontNamesWithTraits:NSItalicFontMask] to check for font availability in advance. Sadly, these changes didn't fix the problem. I've now noticed that I forgot to remove some debugging breakpoints, including _NSLockError, [NSException raise], and objc_exception_throw. However, the app was definitely built using "Release" as the active build configuration. I assume that using the "Release" configuration prevents setting of any breakpoints--but then again I am not sure exactly how breakpoints work or whether the program needs to be run from within gdb for breakpoints to have any effect. My questions are: could my having left the breakpoints set be the cause of the crashes observed by the user? If so, why would the breakpoints cause a problem only for this one user? If not, has anybody else had similar problems with [NSFont fontWithName:size:]? I will probably just try removing the breakpoints and sending back to the user, but I'm not sure how much currency I have left with that user. And I'd like to understand more generally whether leaving the breakpoints set could possibly cause a problem (when the app is built using "Release" configuration).

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  • Foreign Key constraint when persisting a many-to-one class

    - by tieTYT
    I'm getting an error when trying to persist a many to one entity: Internal Exception: org.postgresql.util.PSQLException: ERROR: insert or update on table "concept" violates foreign key constraint "concept_concept_class_fk" Detail: Key (concept_class_id)=(Concept) is not present in table "concept_class". Error Code: 0 Call: INSERT INTO concept (concept_key, description, label, code, concept_class_id) VALUES (?, ?, ?, ?, ?) bind = [27, description_1, label_1, code_1, Concept] Query: InsertObjectQuery(com.mirth.results.entities.Concept[conceptKey=27]) at com.sun.ejb.containers.BaseContainer.checkExceptionClientTx(BaseContainer.java:3728) at com.sun.ejb.containers.BaseContainer.postInvokeTx(BaseContainer.java:3576) at com.sun.ejb.containers.BaseContainer.postInvoke(BaseContainer.java:1354) ... 101 more Here is the method that tries to persist it. I've put a comment where the line is: @Override public void loadConcept(String metaDataFilePath, String dataFilePath) throws Exception { try { ConceptClassMetaData conceptClassMetaData = (ConceptClassMetaData) ModelSerializer.getInstance().fromXML(FileUtils.readFileToString(new File(metaDataFilePath), "UTF8")); em.executeNativeQuery(conceptClassMetaData.getCreateStatement()); ConceptClassRow conceptClassRow = conceptClassMetaData.getConceptClassRow(); ConceptClass conceptClass = em.findByPrimaryKey(ConceptClass.class, conceptClassRow.getId()); if (conceptClass == null) { conceptClass = new ConceptClass(conceptClassRow.getId()); } conceptClass.setLabel(conceptClassRow.getLabel()); conceptClass.setOid(conceptClassRow.getOid()); conceptClass.setDescription(conceptClassRow.getDescription()); conceptClass = em.merge(conceptClass); DataParser dataParser = new DataParser(conceptClassMetaData, dataFilePath); for (ConceptModel conceptModel : dataParser.getConceptRows()) { ConceptFilter<Concept> filter = new ConceptFilter<Concept>(Concept.class); filter.setCode(conceptModel.getCode()); filter.setConceptClass(conceptClass.getLabel()); List<Concept> concepts = em.findAllByFilter(filter); Concept concept = new Concept(); if (concepts != null && !concepts.isEmpty()) { concept = concepts.get(0); } concept.setCode(conceptModel.getCode()); concept.setDescription(conceptModel.getDescription()); concept.setLabel(conceptModel.getLabel()); concept.setConceptClass(conceptClass); concept = em.merge(concept); //THIS LINE CAUSES THE ERROR! } } catch (Exception e) { e.printStackTrace(); throw e; } } ... Here are how the two entities are defined: @Entity @Table(name = "concept") @Inheritance(strategy=InheritanceType.JOINED) @DiscriminatorColumn(name="concept_class_id", discriminatorType=DiscriminatorType.STRING) public class Concept extends KanaEntity { @Id @Basic(optional = false) @Column(name = "concept_key") protected Integer conceptKey; @Basic(optional = false) @Column(name = "code") private String code; @Basic(optional = false) @Column(name = "label") private String label; @Column(name = "description") private String description; @JoinColumn(name = "concept_class_id", referencedColumnName = "id") @ManyToOne private ConceptClass conceptClass; ... @Entity @Table(name = "concept_class") public class ConceptClass extends KanaEntity { @Id @Basic(optional = false) @Column(name = "id") private String id; @Basic(optional = false) @Column(name = "label") private String label; @Column(name = "oid") private String oid; @Column(name = "description") private String description; .... And also, what's important is the sql that's being generated: INSERT INTO concept_class (id, oid, description, label) VALUES (?, ?, ?, ?) bind = [LOINC_TEST, 2.16.212.31.231.54, This is a meta data file for LOINC_TEST, loinc_test] INSERT INTO concept (concept_key, description, label, code, concept_class_id) VALUES (?, ?, ?, ?, ?) bind = [27, description_1, label_1, code_1, Concept] The reason this is failing is obvious: It's inserting the word Concept for the concept_class_id. It should be inserting the word LOINC_TEST. I can't figure out why it's using this word. I've used the debugger to look at the Concept and the ConceptClass instance and neither of them contain this word. I'm using eclipselink. Does anyone know why this is happening?

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  • Using array as map value: Cant see the error

    - by Tom
    Hi all, Im trying to create a map, where the key is an int, and the value is an array int red[3] = {1,0,0}; int green[3] = {0,1,0}; int blue[3] = {0,0,1}; std::map<int, int[3]> colours; colours.insert(std::pair<int,int[3]>(GLUT_LEFT_BUTTON,red)); //THIS IS LINE 24 ! colours.insert(std::pair<int,int[3]>(GLUT_MIDDLE_BUTTON,blue)); colours.insert(std::pair<int,int[3]>(GLUT_RIGHT_BUTTON,green)); However, when I try to compile this code, I get the following error. g++ (Ubuntu 4.4.1-4ubuntu8) 4.4.1 In file included from /usr/include/c++/4.4/bits/stl_algobase.h:66, from /usr/include/c++/4.4/bits/stl_tree.h:62, from /usr/include/c++/4.4/map:60, from ../src/utils.cpp:9: /usr/include/c++/4.4/bits/stl_pair.h: In constructor ‘std::pair<_T1, _T2>::pair(const _T1&, const _T2&) [with _T1 = int, _T2 = int [3]]’: ../src/utils.cpp:24: instantiated from here /usr/include/c++/4.4/bits/stl_pair.h:84: error: array used as initializer /usr/include/c++/4.4/bits/stl_pair.h: In constructor ‘std::pair<_T1, _T2>::pair(const std::pair<_U1, _U2>&) [with _U1 = int, _U2 = int [3], _T1 = const int, _T2 = int [3]]’: ../src/utils.cpp:24: instantiated from here /usr/include/c++/4.4/bits/stl_pair.h:101: error: array used as initializer In file included from /usr/include/c++/4.4/map:61, from ../src/utils.cpp:9: /usr/include/c++/4.4/bits/stl_map.h: In member function ‘_Tp& std::map<_Key, _Tp, _Compare, _Alloc>::operator[](const _Key&) [with _Key = int, _Tp = int [3], _Compare = std::less<int>, _Alloc = std::allocator<std::pair<const int, int [3]> >]’: ../src/utils.cpp:30: instantiated from here /usr/include/c++/4.4/bits/stl_map.h:450: error: conversion from ‘int’ to non-scalar type ‘int [3]’ requested make: *** [src/utils.o] Error 1 I really cant see where the error is. Or even if there's an error. Any help (please include an explanation to help me avoid this mistake) will be appreciated. Thanks in advance.

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  • NHibernate criteria query question

    - by Chris
    I have 3 related objects (Entry, GamePlay, Prize) and I'm trying to find the best way to query them for what I need using NHibernate. When a request comes in, I need to query the Entries table for a matching entry and, if found, get a) the latest game play along with the first game play that has a prize attached. Prize is a child of GamePlay and each Entry object has a GamePlays property (IList). Currently, I'm working on a method that pulls the matching Entry and eagerly loads all game plays and associated prizes, but it seems wasteful to load all game plays just to find the latest one and any that contain a prize. Right now, my query looks like this: var entry = session.CreateCriteria<Entry>() .Add(Restrictions.Eq("Phone", phone)) .AddOrder(Order.Desc("Created")) .SetFetchMode("GamePlays", FetchMode.Join) .SetMaxResults(1).UniqueResult<Entry>(); Two problems with this: It loads all game plays up front. With 365 days of data, this could easily balloon to 300k of data per query. It doesn't eagerly load the Prize child property for each game. Therefore, my code that loops through the GamePlays list looking for a non-null Prize must make a call to load each Prize property I check. I'm not an nhibernate expert, but I know there has to be a better way to do this. Ideally, I'd like to do the following (pseudocode): entry = findEntry(phoneNumber) lastPlay = getLatestGamePlay(Entry) firstWinningPlay = getFirstWinningGamePlay(Entry) The end result of course is that I have the entry details, the latest game play, and the first winning game play. The catch is that I want to do this in as few database calls as possible, otherwise I'd just execute 3 separate queries. The object definitions look like: public class Entry { public Guid Id {get;set;} public string Phone {get;set;} public IList<GamePlay> GamePlays {get;set;} // ... other properties } public class GamePlay { public Guid Id {get;set;} public Entry Entry {get;set;} public Prize Prize {get;set;} // ... other properties } public class Prize { public Guid Id {get;set;} // ... other properties } The proper NHibernate mappings are in place, so I just need help figuring out how to set up the criteria query (not looking for HQL, don't use it).

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  • Cross-platform distributed fault-tolerant (disconnected operation/local cache) filesystem

    - by Adrian Frühwirth
    We are facing a design "challenge" where we are required to set up a storage solution with the following properties: What we need HA a scalable storage backend offline/disconnected operation on the client to account for network outages cross-platform access client-side access from certainly Windows (probably XP upwards), possibly Linux backend integrates with AD/LDAP (permission management (user/group management, ...)) should work reasonably well over slow WAN-links Another problem is that we don't really know all possible use cases here, if people need to be able to have concurrent access to shared files or if they will only be accessing their own files, so a possible solution needs to account for concurrent access and how conflict management would look in this case from a user's point of view. This two years old blog posts sums up the impression that I have been getting during the last couple of days of research, that there are lots of current übercool projects implementing (non-Windows) clustered petabyte-capable blob-storage solutions but that there is none that supports disconnected operation nicely and natively, but I am hoping that we have missed an obvious solution. What we have tried OpenAFS We figured that we want a distributed network filesystem with a local cache and tested OpenAFS (which, as the only currently "stable" DFS supporting disconnected operation, seemed the way to go) for a week but there are several problems with it: it's a real pain to set up there are no official RHEL/CentOS packages the package of the current stable version 1.6.5.1 from elrepo randomly kernel panics on fresh installs, this is an absolute no-go Windows support (including the required Kerberos packages) is mystical. The current client for the 1.6 branch does not run on Windows 8, the current client for the 1.7 does but it just randomly crashes. After that experience we didn't even bother testing on XP and Windows 7. Suffice to say, we couldn't get it working and the whole setup has been so unstable and complicated to setup that it's just not an option for production. Samba + Unison Since OpenAFS was a complete disaster and no other DFS seems to support disconnected operation we went for a simpler idea that would sync files against a Samba server using Unison. This has the following advantages: Samba integrates with ADs; it's a pain but can be done. Samba solves the problem of remotely accessing the storage from Windows but introduces another SPOF and does not address the actual storage problem. We could probably stick any clustered FS underneath Samba, but that means we need a HA Samba setup on top of that to maintain HA which probably adds a lot of additional complexity. I vaguely remember trying to implement redundancy with Samba before and I could not silently failover between servers. Even when online, you are working with local files which will result in more conflicts than would be necessary if a local cache were only touched when disconnected It's not automatic. We cannot expect users to manually sync their files using the (functional, but not-so-pretty) GTK GUI on a regular basis. I attempted to semi-automate the process using the Windows task scheduler, but you cannot really do it in a satisfactory way. On top of that, the way Unison works makes syncing against Samba a costly operation, so I am afraid that it just doesn't scale very well or even at all. Samba + "Offline Files" After that we became a little desparate and gave Windows "offline files" a chance. We figured that having something that is inbuilt into the OS would reduce administrative efforts, helps blaming someone else when it's not working properly and should just work since people have been using this for years. Right? Wrong. We really wanted it to work, but it just doesn't. 30 minutes of copying files around and unplugging network cables/disabling network interfaces left us with (silent! there is only a tiny notification in Windows explorer in the statusbar, which doesn't even open Sync Center if you click on it!) undeletable files on the server (!) and conflicts that should not even be conflicts. In the end, we had one successful sync of a tiny text file, everything else just exploded horribly. Beyond that, there are other problems: Microsoft admits that "offline files" in Windows XP cannot cope with "large files" and therefore does not cache/sync them at all which would mean those files become unavailable if the connection drop In Windows 7 the feature is only available in the Professional/Ultimate/Enterprise editions. Summary Unless there is another fault-tolerant DFS that supports Windows natively I assume that stacking a HA Samba cluster on top of something like GlusterFS/Lustre/whatnot is the only option, but I hope that I am wrong here. How do other companies allow fault-tolerant network access to redundant storage in a heterogeneous environment with Windows?

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  • snmptt not translating traps, even with translate_log_trap_oid=1

    - by mbrownnyc
    I am having some trouble configuring snmptt to properly translate snmp traps. The following is a problem: /etc/snmp/snmptt.conf reflects: EVENT fgFmTrapIfChange .1.3.6.1.4.1.12356.101.6.0.1004 "Status Events" Critical FORMAT $* EXEC /usr/local/nagios/libexec/eventhandlers/submit_check_result $r "snmp_traps" 2 "$O: $+*" "$*" SDESC Trap is sent to the managing FortiManager if an interface IP is changed Variables: 1: fnSysSerial 2: ifName 3: fgManIfIp 4: fgManIfMask EDESC when a trap is received, /var/log/messages reflects: Sep 6 12:07:32 SNMPMANAGERHOST snmptrapd[15385]: 2012-09-06 12:07:32 <UNKNOWN> [UDP: [192.168.100.2]:162->[192.168.100.31]]: #012.1.3.6.1.2.1.1.3.0 = Timeticks: (707253943) 81 days, 20:35:39.43 #011.1.3.6.1.6.3.1.1.4.1.0 = OID: .1.3.6.1.4.1.12356.101.6.0.1004 #011.1.3.6.1.4.1.12356.100.1.1.1.0 = STRING: FGTNNNNNNNNN #011.1.3.6.1.2.1.31.1.1.1.1.10 = STRING: internal4 #011.1.3.6.1.4.1.12356.101.6.2.1.0 = IpAddress: 192.168.65.100 #011.1.3.6.1.4.1.12356.101.6.2.2.0 = IpAddress: 255.255.255.0 Sep 6 12:07:37 SNMPMANAGERHOST icinga: EXTERNAL COMMAND: PROCESS_SERVICE_CHECK_RESULT; 192.168.100.2; snmp_traps; 2; enterprises.12356.101.6.0.1004: enterprises.12356.100.1.1.1.0:FGTNNNNNNNNN ifName.10:internal4 enterprises.12356.101.6.2.1.0:192.168.65.100 enterprises.12356.101.6.2.2.0:255.255.255.0 Since the icinga entry reflects the EXEC, it's obvious there is no translations occurring by snmptt. I have verified that translate_log_trap_oid and net_snmp_perl_enable is enabled in snmptt.ini When using --debug=1 to start snmptt, I see the following in the --debugfile: ********** Net-SNMP version 5.05 Perl module enabled ********** The main NET-SNMP version is reported as NET-SNMP version: 5.5. What else can be done to verify that snmptt is configured properly to translate traps? I have run snmptt-net-snmp-test to verify whatever net-snmp-perl version I have installed properly supports translations. The output indicates it does. /root/snmptt_1.3/snmptt-net-snmp-test --best_guess=2 SNMPTT Net-SNMP Test v1.0 (c) 2003 Alex Burger http://snmptt.sourceforge.net MIBS:RFC1213-MIB best_guess: 2 Testing translateObj ******************** Testing: .1.3.6.1.2.1.1.1, long_names=disabled, include_module=disabled Test passed. Result: sysDescr Testing: .1.3.6.1.2.1.1.1, long_names=disabled, include_module=enabled Test passed. Result: RFC1213-MIB::sysDescr Testing: .1.3.6.1.2.1.1.1, long_names=enabled, include_module=disabled Test passed. Result: .iso.org.dod.internet.mgmt.mib-2.system.sysDescr Testing: .1.3.6.1.2.1.1.1, long_names=enabled, include_module=enabled Test passed. Result: RFC1213-MIB::.iso.org.dod.internet.mgmt.mib-2.system.sysDescr Testing: sysDescr, long_names=disabled, include_module=disabled Test passed. Result: .1.3.6.1.2.1.1.1 Testing: RFC1213-MIB::sysDescr, long_names=disabled, include_module=disabled Test passed. Result: .1.3.6.1.2.1.1.1 Testing: system.sysDescr, long_names=disabled, include_module=disabled Test passed. Result: .1.3.6.1.2.1.1.1 Testing: RFC1213-MIB::system.sysDescr, long_names=disabled, include_module=disabled Test passed. Result: .1.3.6.1.2.1.1.1 Testing: .iso.org.dod.internet.mgmt.mib-2.system.sysDescr, long_names=disabled, include_module=disabled Test passed. Result: .1.3.6.1.2.1.1.1 Testing getType *************** Testing: .1.3.6.1.2.1.4.1 Test passed. Result: INTEGER Testing: ipForwarding Test passed. Result: INTEGER Testing Description ******************* Test passed. Result: ------------------------------------------------- The indication of whether this entity is acting as an IP gateway in respect to the forwarding of datagrams received by, but not addressed to, this entity. IP gateways forward datagrams. IP hosts do not (except those source-routed via the host). Note that for some managed nodes, this object may take on only a subset of the values possible. Accordingly, it is appropriate for an agent to return a `badValue' response if a management station attempts to change this object to an inappropriate value. ------------------------------------------------- I have manually gone through the MIB with the definition that's not resolving, and verified that it is properly linking back to the proper resolved definition. It is: FORTINET-FORTIGATE-MIB.txt contains: fgFmTrapIfChange NOTIFICATION-TYPE OBJECTS { fnSysSerial, ifName, fgManIfIp, fgManIfMask } STATUS current DESCRIPTION "Trap is sent to the managing FortiManager if an interface IP is changed" ::= { fgFmTrapPrefix 1004 } fgFmTrapPrefix OBJECT IDENTIFIER ::= { fgMgmt 0 } fgMgmt OBJECT IDENTIFIER ::= { fnFortiGateMib 6 } fnFortiGateMib ::= { fortinet 101 } IMPORTS FnBoolState, FnIndex, fnAdminEntry, fnSysSerial, fortinet FROM FORTINET-CORE-MIB fortinet MODULE-IDENTITY ::= { enterprises 12356 } LOOKS GOOD!!!!! 1.3.6.1.4.1.12356.101.6.0.1004 I've exhausted all the documentation and even posted fruitlessly in the snmptt-users mailing list. I can not prove it is the MIB. Why would snmptt fail to translate traps? Thanks, Matt

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  • Tracking upstream svn changes with git-svn and github?

    - by Joseph Turian
    How do I track upstream SVN changes using git-svn and github? I used git-svn to convert an SVN repo to git on github: $ git svn clone -s http://svn.osqa.net/svnroot/osqa/ osqa $ cd osqa $ git remote add origin [email protected]:turian/osqa.git $ git push origin master I then made a few changes in my git repo, committed, and pushed to github. Now, I am on a new machine. I want to take upstream SVN changes, merge them with my github repo, and push them to my github repo. This documentation says: "If you ever lose your local copy, just run the import again with the same settings, and you’ll get another working directory with all the necessary SVN metainfo." So I did the following. But none of the commands work as desired. How do I track upstream SVN changes using git-svn and github? What am I doing wrong? $ git svn clone -s http://svn.osqa.net/svnroot/osqa/ osqa $ cd osqa $ git remote add origin [email protected]:turian/osqa.git $ git push origin master To [email protected]:turian/osqa.git ! [rejected] master -> master (non-fast forward) error: failed to push some refs to '[email protected]:turian/osqa.git' $ git pull remote: Counting objects: 21, done. remote: Compressing objects: 100% (17/17), done. remote: Total 17 (delta 7), reused 9 (delta 0) Unpacking objects: 100% (17/17), done. From [email protected]:turian/osqa * [new branch] master -> origin/master From [email protected]:turian/osqa * [new tag] master -> master You asked me to pull without telling me which branch you want to merge with, and 'branch.master.merge' in your configuration file does not tell me either. Please name which branch you want to merge on the command line and try again (e.g. 'git pull <repository> <refspec>'). See git-pull(1) for details on the refspec. ... $ /usr//lib/git-core/git-svn rebase warning: refname 'master' is ambiguous. First, rewinding head to replay your work on top of it... Applying: Added forum/management/commands/dumpsettings.py error: Ref refs/heads/master is at 6acd747f95aef6d9bce37f86798a32c14e04b82e but expected a7109d94d813b20c230a029ecd67801e6067a452 fatal: Cannot lock the ref 'refs/heads/master'. Could not move back to refs/heads/master rebase refs/remotes/trunk: command returned error: 1

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  • What does N years of experience with a language really mean?

    - by marcgg
    I've been looking at jobs descriptions since I'm graduating soon and looking for a job and what's always coming back - I'm not teaching you anything - is the "N years of experience in this language". It has been discussed in this question that if you work professionally with let's say Ruby for 2 years, but during these two years you also did some C# and PHP and were actually coding in Ruby 50% of the time. Do you say you have 1 year of experience in Ruby? 2 years? Another issue that hasn't been reviewed in the other post is for "non-professional experience". I'll give you a personal example: I've been working with Ruby on Rails since 2004 while at school. I did a lot of personal projects and school projects using this technology. I also used Rails in 2 6-month internships. Do I have 5 years of Rails experience (2004-now)? Do I have 1 year(2 internships)? Do I have nothing? I feel like I don't deserve the credit for 5 years, because the first years I wasn't working a lot with rails, but since last year I launched some websites and invested myself a lot in this technology and just saying 1 year doesn't really reflect how much I know the technology... Another example: I Learned C++ at school and did 1 big project with it (2-3 month of work and a semester of classes). I never used it in a company but I'd be able to be productive fairly quickly if I had to work on a C++ project and I have a good grasp of the concepts. Do I have no experience? 3 months? 6 months? ... something else? What I'm really trying to do is to find a way to present my skill set in a way that is compliant to what recruiters expect. I also don't want to end up at an interview that would go something like this... Recruiter (finding out the horrible truth): Oh but you said that you had 2 years of experience with this when you have none! / slaps me in the face / Me (in pain): Oh! The irony! Recruiter (yelling): Get out of my office / calls security, punches me in the throat /

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  • Why won't this hit test fire a second time? wpf

    - by csciguy
    All, I have a main window that contains two custom objects (AnimatedCharacter). These objects are nothing but images. These images might contain transparent portions. One of these objects slightly overlaps the other object. There is a listener attached to the main window and is as follows. private void Window_MouseLeftButtonUp_1(object sender, MouseButtonEventArgs e) { Point pt = e.GetPosition((UIElement)sender); //store off the mouse pt hitPointMouse = pt; //clear the result list hitResultsSubList.Clear(); EllipseGeometry m_egHitArea = new EllipseGeometry(pt, 1, 1); VisualTreeHelper.HitTest(sender as Visual, HitTestFilterFuncNew, new HitTestResultCallback(HitTestCallback), new GeometryHitTestParameters(m_egHitArea)); //Check all sub items you have now hit if (hitResultsSubList.Count > 0) { CheckSubHitItems(hitResultsSubList); } } The idea is to filter out only a select group of items (called AnimatedCharacters). The hittest and filters are as follows public HitTestResultBehavior HitTestCallback(HitTestResult htrResult) { IntersectionDetail idDetail = ((GeometryHitTestResult)htrResult).IntersectionDetail; switch (idDetail) { case IntersectionDetail.FullyContains: return HitTestResultBehavior.Continue; case IntersectionDetail.Intersects: return HitTestResultBehavior.Continue; case IntersectionDetail.FullyInside: return HitTestResultBehavior.Continue; default: return HitTestResultBehavior.Stop; } } public HitTestFilterBehavior HitTestFilterFuncNew(DependencyObject potentialHitTestTarget) { if (potentialHitTestTarget.GetType() == typeof(AnimatedCharacter)) { hitResultsSubList.Add(potentialHitTestTarget as AnimatedCharacter); } return HitTestFilterBehavior.Continue; } This returns me back a list (called hitResultsSubList) that I attempt to then process further. I want to take everything in the hitResultsSubList and run a hit test on it again. This time, the hit test will be checking alpha levels on the particular animatedCharacter object. private void CheckSubHitItems(List<DependencyObject> hitResultsSub) { for(int i = 0; i<hitResultsSub.Count; i++) { hitResultsList.Clear(); AnimatedCharacter ac = hitResultsSub[i] as AnimatedCharacter; try { //DEBUGGER SKIPS THIS NEXT LINE EVERY SINGLE TIME. VisualTreeHelper.HitTest(ac, null, new HitTestResultCallback(hitCallBack), new PointHitTestParameters(hitPointMouse)); } catch (Exception e) { System.Diagnostics.Debug.WriteLine(e.StackTrace); } if (hitResultsList.Count > 0) { //do something here } } } Here is my problem now. The hit test in the second function (CheckSubHitItems) never gets called. There are definitely items (DependencyObjects of the type AnimatedCharacter) in the hitResultSub, but no matter what, the second hit test will not fire. I can walk the for loop fine, but when that line is hit, I get the following console statement. Step into: Stepping over non-user code 'System.MulticastDelegate.CtorClosed' No exceptions are thrown. Any help is appreciated.

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  • Implementing ZBar QR Code Reader in UIView

    - by Bobster4300
    I really need help here. I'm pretty new to iOS/Objective-C so sorry if the problem resolution is obvious or if my code is terrible. Be easy on me!! :-) I'm struggling to integrate ZBarSDK for reading QR Codes into an iPad app i'm building. If I use ZBarReaderController (of which there are plenty of tutorials and guides on implementing), it works fine. However I want to make the camera come up in a UIView as opposed to the fullscreen camera. Now I have gotten as far as making the camera view (readerView) come up in the UIView (ZBarReaderView) as expected, but I get an error when it scans a code. The error does not come up until a code is scanned making me believe this is either delegate related or something else. Here's the important parts of my code: (ZBarSDK.h is imported at the PCH file) SignInViewController.h #import <UIKit/UIKit.h> #import <AVFoundation/AVFoundation.h> @class AVCaptureSession, AVCaptureDevice; @interface SignInViewController : UIViewController < ZBarReaderDelegate > { ZBarReaderView *readerView; UITextView *resultText; } @property (nonatomic, retain) UIImagePickerController *imgPicker; @property (strong, nonatomic) IBOutlet UITextView *resultText; @property (strong, nonatomic) IBOutlet ZBarReaderView *readerView; -(IBAction)StartScan:(id) sender; SignInViewController.m #import "SignInViewController.h" @interface SignInViewController () @end @implementation SignInViewController @synthesize resultText, readerView; -(IBAction)StartScan:(id) sender { readerView = [ZBarReaderView new]; readerView.readerDelegate = self; readerView.tracksSymbols = NO; readerView.frame = CGRectMake(30,70,230,230); readerView.torchMode = 0; readerView.device = [self frontFacingCameraIfAvailable]; ZBarImageScanner *scanner = readerView.scanner; [scanner setSymbology: ZBAR_I25 config: ZBAR_CFG_ENABLE to: 0]; [self relocateReaderPopover:[self interfaceOrientation]]; [readerView start]; [self.view addSubview: readerView]; resultText.hidden=NO; } - (void) readerControllerDidFailToRead: (ZBarReaderController*) reader withRetry: (BOOL) retry{ NSLog(@"the image picker failing to read"); } - (void) imagePickerController: (UIImagePickerController*) reader didFinishPickingMediaWithInfo: (NSDictionary*) info { NSLog(@"the image picker is calling successfully %@",info); id<NSFastEnumeration> results = [info objectForKey: ZBarReaderControllerResults]; ZBarSymbol *symbol = nil; NSString *hiddenData; for(symbol in results) hiddenData=[NSString stringWithString:symbol.data]; NSLog(@"the symbols is the following %@",symbol.data); resultText.text=symbol.data; NSLog(@"BARCODE= %@",symbol.data); NSLog(@"SYMBOL : %@",hiddenData); resultText.text=hiddenData; } The error I get when a code is scanned: 2012-12-16 14:28:32.797 QRTestApp[7970:907] -[SignInViewController readerView:didReadSymbols:fromImage:]: unrecognized selector sent to instance 0x1e88b1c0 2012-12-16 14:28:32.799 QRTestApp[7970:907] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[SignInViewController readerView:didReadSymbols:fromImage:]: unrecognized selector sent to instance 0x1e88b1c0' I'm not too worried about what happens with the results just yet, just want to get over this error. Took me ages just to get the camera to come up in the UIView due to severe lack of tutorial or documentation on ZBarReaderView (for beginners anyway). Thanks all.

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  • One entityManger finds entity , the other does not.

    - by Pitelk
    Hi all, I have a very strange behavior in my program. I have 2 classes (class LogIn and CreateGame) where i have injected an EntityManager in each using the annotation @PersistenceContext(unitName="myUnitPU") EntityManager entitymanger; In some point i remove an object called "user" from the database using entitymanger.remove(user) from a method in LogIn class. The business logic is that a user can host and join games ( in the same time) so removing the user all the entries in database about the games the user has created are removed and all the entries showing in which games the user has joined are removed also. After that, i call another function which checks if the user exists using a method in the LogIn class entitymanager.find(user) which surprisingly enough, finds the user. After that I call a method in CreateGame class which tries to find the user by using again entitymanger.find(user) the entitymanger in that class fails to find the user (which is the expected result as the user is removed and it's not in the database) So the question is : Why the entitymanager in one class finds the user (which is wrong) where the other doesn't find it? Does anyone has ever the same problem? PS : This "bug" occurs when the user has hosted a game which is joined by another user (lets call him Buser) and the Buser has made a game which is joined by the current user. GAME | HOST | CLIENTS game1 | user | userB game2 | userB | user where in this case by removing the user, the game1 is deleted and the user is removed from game2 so the result is GAME | HOST | CLIENTS game2 | userB | PS2 : The Beans are EJB3.0. The methods are called from a delegate class. The beans in the delegate class are instantiated using the InitialContext.lookup() method. Note that for logging in ,creating , joining games the appropriate delegate class calls the correspondent EJB which does the transactions. In the case of logOut, the delegate calls an EJB to logout the user but becuase other stuff must be done (as said above) this EJB calls other EJB (again using lookup() ) which has methods like removegame(), removeUserFromGame() etc. After those methods are executed the user is then logged out. Maybe it has something to do with the fact the the first entity manager is called by a delegate but the second from inside an EJb and thats why the one entitymanger can see the non-existent user while the other cannot? Also all the methods have TRANSACTIONTYPE.REQUIRED Thank you in advance

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  • ActiveMQ 5.2.0 + REST + HTTP POST = java.lang.OutOfMemoryError

    - by Bruce Loth
    First off, I am a newbie when it comes to JMS & ActiveMQ. I have been looking into a messaging solution to serve as middleware for a message producer that will insert XML messages into a queue via HTTP POST. The producer is an existing system written in C++ that cannot be modified (so Java and the C++ API are out). Using the "demo" examples and some trial and error, I have cobbled together a working example of what I want to do (on a windows box). The web.xml I configured in a test directory under "webapps" specifies that the HTTP POST messages received from the producer are to be handled by the MessageServlet. I added a line for the text app in "activemq.xml" ('ow' is the test app dir): I created a test script to "insert" messages into the queue which works well. The problem I am running into is that it as I continue to insert messages via REST/HTTP POST, the memory consumption and thread count used by ActiveMQ continues to rise (It happens when I have timely consumers as well as slow or non-existent consumers). When memory consumption gets around 250MB's and the thread count exceeds 5000 (as shown in windows task manager), ActiveMQ crashes and I see this in the log: Exception in thread "ActiveMQ Transport Initiator: vm://localhost#3564" java.lang.OutOfMemoryError: unable to create new native thread It is as if Jetty is spawning a new thread to handle each HTTP POST and the thread never dies. I did look at this page: http://activemq.apache.org/javalangoutofmemory.html and tried but that didn't fix the problem (although I didn't fully understand the implications of the change either). Does anyone have any ideas? Thanks! Bruce Loth PS - I included the "test message producer" python script below for what it is worth. I created batches of 100 messages and continued to run the script manually from the command line while watching the memory consumption and thread count of ActiveMQ in task manager. def foo(): import httplib, urllib body = "<?xml version='1.0' encoding='UTF-8'?>\n \ <ROOT>\n \ [snip: xml deleted to save space] </ROOT>" headers = {"content-type": "text/xml", "content-length": str(len(body))} conn = httplib.HTTPConnection("127.0.0.1:8161") conn.request("POST", "/ow/message/RDRCP_Inbox?type=queue", body, headers) response = conn.getresponse() print response.status, response.reason data = response.read() conn.close() ## end method definition ## Begin test code count = 0; while(count < 100): # Test with batches of 100 msgs count += 1 foo()

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  • MySQL table organization and optimization (Rails)

    - by aguynamedloren
    I've been learning Ruby on Rails over the past few months with no prior programming experience. Lately, I've been thinking about database optimization and table organization. I know there are great books on the subject, but I typically learn by example / as I go. Here's a hypothetical situation: Let's say I am building a social network for a niche community with 250,000 members (users). The users have the ability to attend events. Let's say there are 50,000 past/present/future events. Much like Facebook events, a user can attend any number of events and an event can have any number of attendees. In the database, there would be a table for users and a table for events. Somehow I would have to create an association between the users and events. I could create an "events" column in the users table such that each user row would contain a hash of event IDs, or I could create an "attendees" column in the events table such that each event row would contain a hash of user IDs. Neither of these solutions seem ideal, however. On a users profile page, I want to display the list of events they are associated with, which would require scanning the 50,000 event rows for the user ID of said user if I include an "attendees" column in the events table. Likewise, on an event page, I want to display a list of attendees for the event, which would require scanning the 250,000 user rows for the event ID of said event if I include an "events" column in the users table. Option 3 would be to create a third table that contains the attendee information for each and every event - but I don't see how this would solve any problems. Are these non-issues? Rails makes accessing all of this information easy, but I guess I'm worried about scale. It is entirely possible that I am under-estimating the speed and processing power of modern databases / servers / etc. How long would it take to scan 250,000 user rows for specific event IDs - 10ms? 100ms? 1,000ms? I guess that's not that bad. Am I just over-thinking this?

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  • Problem getting correct parameters for C# P/Invoke call to C++ dll

    - by Jim Jones
    Trying to Interop a functionality from the Outside In API from Oracle. Have the following function: SCCERR EXOpenExport {VTHDOC hDoc, VTDWORD dwOutputId, VTDWORD dwSpecType, VTLPVOID pSpec, VTDWORD dwFlags, VTSYSPARAM dwReserved, VTLPVOID pCallbackFunc, VTSYSPARAM dwCallbackData, VTLPHEXPORT phExport); From the header files I reduced the parameters to: typedef VTSYSPARAM VTHDOC, VTLPHDOC * typedef DWORD_PTR VTSYSPARAM typedef unsigned long DWORD_PTR typedef unsigned long VTDWORD typedef VTVOID* VTLPVOID #define VTVOID void typedef VTHDOC VTHEXPORT, *VTLPEXPORT These are for 32 bit windows Going through the header files, the example programs, and the documentation I found: 1. That pSpec could be a pointer to a buffer or NULL, so I set it to a IntPtr.Zero (documentation). 2. That dwFlags and dwReserved according to the documentation "Must be set by the developer to 0". 3. That pCallbackFunc can be set to NULL if I don't want to handle callbacks. 4. That the last two are based on structs that I wrote C# wrappers for using the [StructLayout(LayoutKind.Sequential)]. Then instatiated an instance and generated the parameters by first creating a IntPtr with Marshal.AllocHGlobal(Marshal.SizeOf(instance)), then getting the address value which is passed as a uint for dwCallbackData and a IntPtr for phExport. The final parameter list is as follows: 1. phDoc as a IntPtr which was loaded with an address by the DAOpenDocument function called before. 2. dwOutputId as uint set to 1535 which represents FI_JPEGFIF 3. dwSpecType as int set to 2 which represents IOTYPE_ANSIPATH 4. pSpec as an IntPtr.Zero where the output will be written 5. dwFlags as uint set to 0 as directed 6. dwReserved as uint set to 0 as directed 7. pCallbackFunc as IntPtr set to NULL as I will handle results 8. dwCallBackDate as uint the address of a buffer for a struct 9. phExport as IntPtr to another struct buffer still get an undefined error from the API. Meaning that the call returns a 961 which is not defined in any of the header files. In the past I have gotten this when my choice of parameter types are incorrect. I started out using Interop Assistant which was helpful in learning how many of the parameter types get translated. It is however limited by how well I am able to glean the correct native type from the header files. For example the hDoc parameter used in the preceding function was defined as a non-filesytem handle, so attempted to use Marshal to create a handle, then used an IntPtr, and finally it turned out to be an int (actually it was &phDoc used here). So is there a more scientific way of doing this, other than trial and error? Jim

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  • Rx IObservable buffering to smooth out bursts of events

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

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  • Purpose of Explicit Default Constructors

    - by Dennis Zickefoose
    I recently noticed a class in C++0x that calls for an explicit default constructor. However, I'm failing to come up with a scenario in which a default constructor can be called implicitly. It seems like a rather pointless specifier. I thought maybe it would disallow Class c; in favor of Class c = Class(); but that does not appear to be the case. Some relevant quotes from the C++0x FCD, since it is easier for me to navigate [similar text exists in C++03, if not in the same places] 12.3.1.3 [class.conv.ctor] A default constructor may be an explicit constructor; such a constructor will be used to perform default-initialization or value initialization (8.5). It goes on to provide an example of an explicit default constructor, but it simply mimics the example I provided above. 8.5.6 [decl.init] To default-initialize an object of type T means: — if T is a (possibly cv-qualified) class type (Clause 9), the default constructor for T is called (and the initialization is ill-formed if T has no accessible default constructor); 8.5.7 [decl.init] To value-initialize an object of type T means: — if T is a (possibly cv-qualified) class type (Clause 9) with a user-provided constructor (12.1), then the default constructor for T is called (and the initialization is ill-formed if T has no accessible default constructor); In both cases, the standard calls for the default constructor to be called. But that is what would happen if the default constructor were non-explicit. For completeness sake: 8.5.11 [decl.init] If no initializer is specified for an object, the object is default-initialized; From what I can tell, this just leaves conversion from no data. Which doesn't make sense. The best I can come up with would be the following: void function(Class c); int main() { function(); //implicitly convert from no parameter to a single parameter } But obviously that isn't the way C++ handles default arguments. What else is there that would make explicit Class(); behave differently from Class();? The specific example that generated this question was std::function [20.8.14.2 func.wrap.func]. It requires several converting constructors, none of which are marked explicit, but the default constructor is.

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  • How does MySQL's ORDER BY RAND() work?

    - by Eugene
    Hi, I've been doing some research and testing on how to do fast random selection in MySQL. In the process I've faced some unexpected results and now I am not fully sure I know how ORDER BY RAND() really works. I always thought that when you do ORDER BY RAND() on the table, MySQL adds a new column to the table which is filled with random values, then it sorts data by that column and then e.g. you take the above value which got there randomly. I've done lots of googling and testing and finally found that the query Jay offers in his blog is indeed the fastest solution: SELECT * FROM Table T JOIN (SELECT CEIL(MAX(ID)*RAND()) AS ID FROM Table) AS x ON T.ID >= x.ID LIMIT 1; While common ORDER BY RAND() takes 30-40 seconds on my test table, his query does the work in 0.1 seconds. He explains how this functions in the blog so I'll just skip this and finally move to the odd thing. My table is a common table with a PRIMARY KEY id and other non-indexed stuff like username, age, etc. Here's the thing I am struggling to explain SELECT * FROM table ORDER BY RAND() LIMIT 1; /*30-40 seconds*/ SELECT id FROM table ORDER BY RAND() LIMIT 1; /*0.25 seconds*/ SELECT id, username FROM table ORDER BY RAND() LIMIT 1; /*90 seconds*/ I was sort of expecting to see approximately the same time for all three queries since I am always sorting on a single column. But for some reason this didn't happen. Please let me know if you any ideas about this. I have a project where I need to do fast ORDER BY RAND() and personally I would prefer to use SELECT id FROM table ORDER BY RAND() LIMIT 1; SELECT * FROM table WHERE id=ID_FROM_PREVIOUS_QUERY LIMIT 1; which, yes, is slower than Jay's method, however it is smaller and easier to understand. My queries are rather big ones with several JOINs and with WHERE clause and while Jay's method still works, the query grows really big and complex because I need to use all the JOINs and WHERE in the JOINed (called x in his query) sub request. Thanks for your time!

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  • Fairness: Where can it be better handled?

    - by Srinivas Nayak
    Hi, I would like to share one of my practical experience with multiprogramming here. Yesterday I had written a multiprogram. Modifications to sharable resources were put under critical sections protected by P(mutex) and V(mutex) and those critical section code were put in a common library. The library will be used by concurrent applications (of my own). I had three applications that will use the common code from library and do their stuff independently. my library --------- work_on_shared_resource { P(mutex) get_shared_resource work_with_it V(mutex) } --------- my application ----------- application1 { *[ work_on_shared_resource do_something_else_non_ctitical ] } application2 { *[ work_on_shared_resource do_something_else_non_ctitical ] } application3 { *[ work_on_shared_resource ] } *[...] denote a loop. ------------ I had to run the applications on Linux OS. I had a thought in my mind, hanging over years, that, OS shall schedule all the processes running under him with all fairness. In other words, it will give all the processes, their pie of resource-usage equally well. When first two applications were put to work, they run perfectly well without deadlock. But when the third application started running, always the third one got the resources, but since it is not doing anything in its non-critical region, it gets the shared resource more often when other tasks are doing something else. So the other two applications were found almost totally halted. When the third application got terminated forcefully, the previous two applications resumed their work as before. I think, this is a case of starvation, first two applications had to starve. Now how can we ensure fairness? Now I started believing that OS scheduler is innocent and blind. It depends upon who won the race; he got the largest pie of CPU and resource. Shall we attempt to ensure fairness of resource users in the critical-section code in library? Or shall we leave it up to the applications to ensure fairness by being liberal, not greedy? To my knowledge, adding code to ensure fairness to the common library shall be an overwhelming task. On the other hand, believing on the applications will also never ensure 100% fairness. The application which does a very little task after working with shared resources shall win the race where as the application which does heavy processing after their work with shared resources shall always starve. What is the best practice in this case? Where we ensure fairness and how? Sincerely, Srinivas Nayak

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