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  • Is Polymorphism and Method Overloading is almost the same thing in C++

    - by Maxood
    In C++, there are 2 types of Polymorphism: Object Polymorphism Function Polymorphism Function polymorphism is exactly the same thing as method or function overloading i.e. We use the same method names with different parameters and return types. Now the question is why do we have this fancy name Polymorphism in OOP? What distinctly distinguishes polymorphism from method overloading? Can someone explain with a scenario. Thanks

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  • .Net Library for parsing source code files?

    - by Jörg Battermann
    Does anyone know of a good .NET library that allows me to parse source code files, but not only .NET source code files (like java, perl, ruby, etc)? I need programmatic access to the contents of various source code files (e.g. class/method /parameter names, types, etc.). Has anyone come across something like this? I know within .NET it is reasonably possible and there are some libraries out there, but I need that to be abstracted to more types of programming languages.

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  • Attach a formatter to a UITextField on iPhone

    - by charlax
    I'm trying to format an UITextField as user types text, for instance to show separator for thousands. I found this web page : http://www.iphonedevsdk.com/forum/iphone-sdk-development/16512-trying-add-commas.html It seems that shouldChangeCharactersInRange: is not a good solution. I thought of a custom UIView where the view would be updated as the user types digits, yet it would require recreating the wheel...

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  • ASP.NET MVC - Data Annotations - Why add a default RequiredAttribute?

    - by redsquare
    Can anyone explain why it is assumed that a non nullable type property should always have a RequiredAttribue? I am trying to write a label helper that will auto append * or change the css class so that I can indicate to the user that the field is required. However when querying the metadata the non nullable properties end up with a required attribute. MVC Source Code: protected override IEnumerable<ModelValidator> GetValidators( ModelMetadata metadata, ControllerContext context, IEnumerable<Attribute> attributes) { _adaptersLock.EnterReadLock(); try { List<ModelValidator> results = new List<ModelValidator>(); if (metadata.IsRequired && !attributes.Any(a => a is RequiredAttribute)) { //******* Why Do this? attributes = attributes.Concat(new[] { new RequiredAttribute() }); } foreach (ValidationAttribute attribute in attributes.OfType<ValidationAttribute>()) { DataAnnotationsModelValidationFactory factory; if (!_adapters.TryGetValue(attribute.GetType(), out factory)) factory = _defaultFactory; results.Add(factory(metadata, context, attribute)); } return results; } finally { _adaptersLock.ExitReadLock(); } }

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  • Need to lookup function arguments (in/out) from pdb by dbghelp

    - by Usman
    I need to lookup function parameters(their types infact) from PDB file From dbghelp, we can parse any pdb and can get info like how many functions,addresses function names and others etc. My problem is I am also interested to get function parameters as well. As SYMBOL_INFO structure in callback function only contains symbolName,Addresses and Size. How can we lookup PARAMETERES(in/out Types/names)of any function. Regards Usman

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  • Implementing PyMyType_Check methods with Python C API?

    - by Paul D.
    All the Python-provided types have a check method (i.e., PyList_Check) that allows you to check if an arbitrary PyObject* is actually a specific type. How can I implement this for my own types? I haven't found anything good online for this, though it seems like a pretty normal thing to want to do. Also, maybe I'm just terrible at looking through large source trees, but I cannot for the life of me find the implementation of PyList_Check or any of it's companions in the Python (2.5) source.

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  • How to tell what name RIA Services/EF Model uses for Associations?

    - by Nick Gotch
    Hi, I'm working on a C#.NET 3.5 WCF RIA Services app and having an issue with my Entity Framework model. My entity Foo is mapped to a DB table and has a primary key called FooId. My Bar is mapped to a DB view. I've selectively designed this view to generate a composite key in the EF using two of the columns (by making sure they were non-nullable and the others are all nullable. This was done using NULLIF and ISNULL in the view design.) I'm able to add this view to the model with no problem but I keep running into an issue when I try to map an association between the two. Foo should contain many Bars but I keep getting the following error when I add the association: Unable to retrieve AssociationType for association 'FK_Bar_Foo' According to this page, it looks like this might work if I can properly name the association (since RIA Services looks for specific names.) I've tried several variants of names that match the pattern of other associations with no success. Does anyone know if there's a place I can look to find out what name it's looking for? Thanks,

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  • Anything new for WinForms in .NET 4.0

    - by Robert
    I could not find any information about new WinForm features, exept for this blog post: http://blog.codinglight.com/2009/05/future-of-winforms-whats-changed-in.html which states: 213 types were changed, and 9 types were added. 596 methods were changed, 50 were added, and 8 were removed. So whats in these changes, for joe developer?

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  • database design to speed up hibernate querying of large dataset

    - by paddydub
    I currently have the below tables representing a bus network mapped in hibernate, accessed from a Spring MVC based bus route planner I'm trying to make my route planner application perform faster, I load all the above tables into Lists to perform the route planner logic. I would appreciate if anyone has any ideas of how to speed my performace Or any suggestions of another method to approach this problem of handling a large set of data Coordinate Connections Table (INT,INT,INT)( Containing 50,000 Coordinate Connections) ID, FROMCOORDID, TOCOORDID 1 1 2 2 1 17 3 1 63 4 1 64 5 1 65 6 1 95 Coordinate Table (INT,DECIMAL, DECIMAL) (Containing 4700 Coordinates) ID , LAT, LNG 0 59.352669 -7.264341 1 59.352669 -7.264341 2 59.350012 -7.260653 3 59.337585 -7.189798 4 59.339221 -7.193582 5 59.341408 -7.205888 Bus Stop Table (INT, INT, INT)(Containing 15000 Stops) StopID RouteID COORDINATEID 1000100001 100 17 1000100002 100 18 1000100003 100 19 1000100004 100 20 1000100005 100 21 1000100006 100 22 1000100007 100 23 This is how long it takes to load all the data from each table: stop.findAll = 148ms, stops.size: 15670 Hibernate: select coordinate0_.COORDINATEID as COORDINA1_2_, coordinate0_.LAT as LAT2_, coordinate0_.LNG as LNG2_ from COORDINATES coordinate0_ coord.findAll = 51ms , coordinates.size: 4704 Hibernate: select coordconne0_.COORDCONNECTIONID as COORDCON1_3_, coordconne0_.DISTANCE as DISTANCE3_, coordconne0_.FROMCOORDID as FROMCOOR3_3_, coordconne0_.TOCOORDID as TOCOORDID3_ from COORDCONNECTIONS coordconne0_ coordinateConnectionDao.findAll = 238ms ; coordConnectioninates.size:48132 Hibernate Annotations @Entity @Table(name = "STOPS") public class Stop implements Serializable { @Id @GeneratedValue @Column(name = "COORDINATEID") private Integer CoordinateID; @Column(name = "LAT") private double latitude; @Column(name = "LNG") private double longitude; } @Table(name = "COORDINATES") public class Coordinate { @Id @GeneratedValue @Column(name = "COORDINATEID") private Integer CoordinateID; @Column(name = "LAT") private double latitude; @Column(name = "LNG") private double longitude; } @Entity @Table(name = "COORDCONNECTIONS") public class CoordConnection { @Id @GeneratedValue @Column(name = "COORDCONNECTIONID") private Integer CoordinateID; /** * From Coordinate_id value */ @Column(name = "FROMCOORDID", nullable = false) private int fromCoordID; /** * To Coordinate_id value */ @Column(name = "TOCOORDID", nullable = false) private int toCoordID; //private Coordinate toCoordID; }

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  • Schema qualified tables with SQLAlchemy, SQLite and Postgresql?

    - by Chris Reid
    I have a Pylons project and a SQLAlchemy model that implements schema qualified tables: class Hockey(Base): __tablename__ = "hockey" __table_args__ = {'schema':'winter'} hockey_id = sa.Column(sa.types.Integer, sa.Sequence('score_id_seq', optional=True), primary_key=True) baseball_id = sa.Column(sa.types.Integer, sa.ForeignKey('summer.baseball.baseball_id')) This code works great with Postgresql but fails when using SQLite on table and foreign key names (due to SQLite's lack of schema support) sqlalchemy.exc.OperationalError: (OperationalError) unknown database "winter" 'PRAGMA "winter".table_info("hockey")' () I'd like to continue using SQLite for dev and testing. Is there a way of have this fail gracefully on SQLite?

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  • Groovy on Grails: GORM and BitSets?

    - by Visionary Software Solutions
    I don't see anything in the official documentation about unsupported persistence data types, so I'm working under the assumption that types available in the Groovy language should be handled. However, for the following domain class: class DocGroupPermissions { Workgroup workgroup; Document document; BitSet permissions = new BitSet(2) public DocGroupPermissions() {} void setPermissions(boolean canRead, boolean canWrite){ setReadPermissions(canRead) setWritePermissions(canWrite) } BitSet getPermissions() { return permissions } void setReadPermissions(boolean canRead) { permissions.set(0,canRead) } void setWritePermissions(boolean canWrite) { permissions.set(1,canWrite) } boolean getReadPermissions() { return permissions.get(0) } boolean getWritePermissions() { return permissions.get(1) } static belongsTo = [workgroup:Workgroup, document:Document] static constraints = { workgroup(nullable:false, blank:false) document(nullable:false, blank:false) } } I'm getting: 2009-11-15 16:46:12,298 [main] ERROR context.ContextLoader - Context initialization failed org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'messageSource': Initialization of bean failed; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'transactionManager': Cannot resolve reference to bean 'sessionFactory' while setting bean property 'sessionFactory'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'sessionFactory': Invocation of init method failed; nested exception is org.hibernate.MappingException: An association from the table doc_group_permissions refers to an unmapped class: java.util.BitSet Has anyone run into this before?

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  • SOAP web service evolution

    - by Thilo
    Are there any guidelines/tutorials as to how to handle the evolution of a SOAP web service? I can see that changing existing methods or types would probably not work, but can I just add new methods, complex types, enumeration values without breaking existing clients?

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  • Unable to execute stored Procedure using Java and JDBC on SQL server

    - by jwmajors81
    I have been trying to execute a MS SQL Server stored procedure via JDBC today and have been unsuccessful thus far. The stored procedure has 1 input and 1 output parameter. With every combination I use when setting up the stored procedure call in code I get an error stating that the stored procedure couldn't be found. I have provided the stored procedure I'm executing below (NOTE: this is vendor code, so I cannot change it). set ANSI_NULLS ON set QUOTED_IDENTIFIER ON GO ALTER PROC [dbo].[spWCoTaskIdGen] @OutIdentifier int OUTPUT AS BEGIN DECLARE @HoldPolicyId int DECLARE @PolicyId char(14) IF NOT EXISTS ( SELECT * FROM UniqueIdentifierGen (UPDLOCK) ) INSERT INTO UniqueIdentifierGen VALUES (0) UPDATE UniqueIdentifierGen SET CurIdentifier = CurIdentifier + 1 SELECT @OutIdentifier = (SELECT CurIdentifier FROM UniqueIdentifierGen) END The code looks like: CallableStatement statement = connection .prepareCall("{call dbo.spWCoTaskIdGen(?)}"); statement.setInt(1, 0); ResultSet result = statement.executeQuery(); I get the following error: SEVERE: Could not find stored procedure 'dbo.spWCoTaskIdGen'. I have also tried CallableStatement statement = connection .prepareCall("{? = call dbo.spWCoTaskIdGen(?)}"); statement.registerOutParameter(1, java.sql.Types.INTEGER); statement.registerOutParameter(2, java.sql.Types.INTEGER); statement.executeQuery(); The above results in: SEVERE: Could not find stored procedure 'dbo.spWCoTaskIdGen'. I have also tried: CallableStatement statement = connection .prepareCall("{? = call spWCoTaskIdGen(?)}"); statement.registerOutParameter(1, java.sql.Types.INTEGER); statement.registerOutParameter(2, java.sql.Types.INTEGER); statement.executeQuery(); The code above resulted in the following error: Could not find stored procedure 'spWCoTaskIdGen'. Finally, I should also point out the following: I have used the MS SQL Server Management Studio tool and have been able to successfully run the stored procedure. The sql generated to execute the stored procedure is provided below: GO DECLARE @return_value int, @OutIdentifier int EXEC @return_value = [dbo].[spWCoTaskIdGen] @OutIdentifier = @OutIdentifier OUTPUT SELECT @OutIdentifier as N'@OutIdentifier ' SELECT 'Return Value' = @return_value GO The code being executed runs with the same user id that was used in point #1 above. In the code that creates the Connection object I log which database I'm connecting to and the code is connecting to the correct database. Any ideas? Thank you very much in advance.

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  • PDO fails to prepare a statement with over 13 placeholders

    - by Javier Parra
    Hello, this is the code I'm using: self::$DB->prepare($query, $types); when the $query and types are: //$query UPDATE Permisos SET empleado_id = ?, agregar_mensaje = ?, borrar_mensaje = ?, agregar_noticia = ?, borrar_noticia = ?, agregar_documento = ?, borrar_documento = ?, agregar_usuario = ?, borrar_usuario = ?, agregar_empresa = ?, borrar_empresa = ?, agregar_tarea = ? WHERE id = ? //$types Array( [0] => integer [1] => boolean [2] => boolean [3] => boolean [4] => boolean [5] => boolean [6] => boolean [7] => boolean [8] => boolean [9] => boolean [10] => boolean [11] => boolean [12] => integer ) Everything works great, but when they are: //$query UPDATE Permisos SET empleado_id = ?, agregar_mensaje = ?, borrar_mensaje = ?, agregar_noticia = ?, borrar_noticia = ?, agregar_documento = ?, borrar_documento = ?, agregar_usuario = ?, borrar_usuario = ?, agregar_empresa = ?, borrar_empresa = ?, agregar_tarea = ?, borrar_tarea = ? WHERE id = ? //$types Array( [0] => integer [1] => boolean [2] => boolean [3] => boolean [4] => boolean [5] => boolean [6] => boolean [7] => boolean [8] => boolean [9] => boolean [10] => boolean [11] => boolean [12] => boolean [13] => integer ) It fails with the following message: <b>Warning</b>: PDO::prepare() [<a href='pdo.prepare'>pdo.prepare</a>]: SQLSTATE[HY000]: General error: PDO::ATTR_STATEMENT_CLASS requires format array(classname, array(ctor_args)); the classname must be a string specifying an existing class in <b>C:\wamp\www\intratin\JP\includes\empleado\mapper\Permiso.php</b> on line <b>137</b><br /> Doesn't matter which field I add or remove, it fails every time with more than 13 placeholders.

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  • Looking for MDI Manager with tab grouping that allows show and hide of groups?

    - by Jeff Lundstrom
    I am looking for a MDI manager solution that allows documents to be grouped and show/hidden programmaticly. Example, 3 document types, red, yellow and green. When you click a button the MDI manager shows only the red documents by hiding the other 2 types tabs. None of the MDI managers (Actipro, Infragistics, etx) I have looked at can do this. They require all documents to be visible... Anyone know of a good solution for this in C#? Thanks, Jeff

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  • Deadlock in ThreadPoolExecutor

    - by Vitaly
    Encountered a situation when ThreadPoolExecutor is parked in execute(Runnable) function while all the ThreadPool threads are waiting in getTask func, workQueue is empty. Does anybody have any ideas? The ThreadPoolExecutor is created with ArrayBlockingQueue, corePoolSize == maximumPoolSize = 4 [Edit] To be more precise, the thread is blocked in ThreadPoolExecutor.exec(Runnable command) func. It has the task to execute, but doesn't do it. [Edit2] The executor is blocked somewhere inside the working queue (ArrayBlockingQueue). [Edit3] The callstack: thread = front_end(224) at sun.misc.Unsafe.park(Native methord) at java.util.concurrent.locks.LockSupport.park(LockSupport.java:158) at java.util.concurrent.locks.AbstractQueuedSynchronizer.parkAndCheckInterrupt(AbstractQueuedSynchronizer.java:747) at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireQueued(AbstractQueuedSynchronizer.java:778) at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquire(AbstractQueuedSynchronizer.java:1114) at java.util.concurrent.locks.ReentrantLock$NonfairSync.lock(ReentrantLock.java:186) at java.util.concurrent.locks.ReentrantLock.lock(ReentrantLock.java:262) at java.util.concurrent.ArrayBlockingQueue.offer(ArrayBlockingQueue.java:224) at java.util.concurrent.ThreadPoolExecutor.execute(ThreadPoolExecutor.java:653) at net.listenThread.WorkersPool.execute(WorkersPool.java:45) at the same time the workQueue is empty (checked using remote debug) [Edit4] Code working with ThreadPoolExecutor: public WorkersPool(int size) { pool = new ThreadPoolExecutor(size, size, IDLE_WORKER_THREAD_TIMEOUT, TimeUnit.SECONDS, new ArrayBlockingQueue<Runnable>(WORK_QUEUE_CAPACITY), new ThreadFactory() { @NotNull private final AtomicInteger threadsCount = new AtomicInteger(0); @NotNull public Thread newThread(@NotNull Runnable r) { final Thread thread = new Thread(r); thread.setName("net_worker_" + threadsCount.incrementAndGet()); return thread; } }, new RejectedExecutionHandler() { public void rejectedExecution(@Nullable Runnable r, @Nullable ThreadPoolExecutor executor) { Verify.warning("new task " + r + " is discarded"); } }); } public void execute(@NotNull Runnable task) { pool.execute(task); } public void stopWorkers() throws WorkersTerminationFailedException { pool.shutdownNow(); try { pool.awaitTermination(THREAD_TERMINATION_WAIT_TIME, TimeUnit.SECONDS); } catch (InterruptedException e) { throw new WorkersTerminationFailedException("Workers-pool termination failed", e); } } }

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  • Help regarding composite pattern with hibernate

    - by molleman
    Hello, So i am stuck, i am creating a gwt web application, i will be using a tree(gwt Tree and TreeItems) structure to show a list of folders(class Folder) and files(class FileLocation), the folder and filelocation class will all implement a Hierarchy interface basing the classes on the composite pattern. but i am using hibernate to store my data , and i am using annotations for the mapping of the data to the database. my trouble is i do not know how to annotate my interface. have any of you guys used the composite pattern while persisting the data with hibernate public interface Hierarchy(){ // a few abstract methods that will be implemented by the sub classes } @Entity @Table() public class Folder extends Hierarchy implements Serializable { @Id @GeneratedValue(strategy = GenerationType.AUTO) @Column(name = "folder_id", updatable = false, nullable = false) private int id; @OneToMany(cascade = CascadeType.ALL,fetch = FetchType.EAGER) @JoinTable(name = "FOLDER_FILELOCATION", joinColumns = { @JoinColumn(name = "folder_id") }, inverseJoinColumns = { @JoinColumn(name = "file_information_id") }) private List<Hierarchy> children = new ArrayList<Hierarchy>() ; @Column(name = "folder_name") private String folderName; @Column(name = "tree_item") private TreeItem item; @Column (name = "parent") private Hierarchy parent; @Entity @Table(name = "FILE_INFORMATION_TABLE") public class FileInformation extends Hierarchy implements Serializable { @Id @GeneratedValue(strategy = GenerationType.AUTO) @Column(name = "file_information_id", updatable = false, nullable = false) private int fiId; @Column (name = "location") private String location; @Column(name = "tree_item") private TreeItem item; @Column (name = "parent") private Hierarchy parent;

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  • Dynamic Typed Table/Model in J2EE?

    - by Viele
    Hi, Usually with J2EE when we create Model, we define the fields and types of fields through XML or annotation before compilation time. Is there a way to change those in runtime? or better, is it possible to create a new Model based on the user's input during the runtime? such that the number of columns and types of fields are dynamic (determined at runtime)? Help is much appreciated. Thank you.

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  • Maintaining content type pk integrity in a Django deployment

    - by hekevintran
    When you run syncdb in Django, the primary keys of the content types will be recomputed. If I create new models, the next time I run syncdb, the primary keys of the content types will be different. If I have an application running in production, how can I update the database with the new models and keep the integrity of content type pks?

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  • Textually diffing JSON

    - by Richard Levasseur
    As part of my release processes, I have to compare some JSON configuration data used by my application. As a first attempt, I just pretty-printed the JSON and diff'ed them (using kdiff3 or just diff). As that data has grown, however, kdiff3 confuses different parts in the output, making additions look like giant modifies, odd deletions, etc. It makes it really hard to figure out what is different. I've tried other diff tools, too (meld, kompare, diff, a few others), but they all have the same problem. Despite my best efforts, I can't seem to format the JSON in a way that the diff tools can understand. Example data: [ { "name": "date", "type": "date", "nullable": true, "state": "enabled" }, { "name": "owner", "type": "string", "nullable": false, "state": "enabled", } ...lots more... ] The above probably wouldn't cause the problem (the problem occurs when there begin to be hundreds of lines), but thats the gist of what is being compared. Thats just a sample; the full objects are 4-5 attributes, and some attributes have 4-5 attributes in them. The attribute names are pretty uniform, but their values pretty varied. In general, it seems like all the diff tools confuse the closing "}" with the next objects closing "}". I can't seem to break them of this habit. I've tried adding whitespace, changing indentation, and adding some "BEGIN" and "END" strings before and after the respective objects, but the tool still get confused.

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  • Unable to execute stored Procedure using Java and JDBC

    - by jwmajors81
    I have been trying to execute a MS SQL Server stored procedure via JDBC today and have been unsuccessful thus far. The stored procedure has 1 input and 1 output parameter. With every combination I use when setting up the stored procedure call in code I get an error stating that the stored procedure couldn't be found. I have provided the stored procedure I'm executing below (NOTE: this is vendor code, so I cannot change it). set ANSI_NULLS ON set QUOTED_IDENTIFIER ON GO ALTER PROC [dbo].[spWCoTaskIdGen] @OutIdentifier int OUTPUT AS BEGIN DECLARE @HoldPolicyId int DECLARE @PolicyId char(14) IF NOT EXISTS ( SELECT * FROM UniqueIdentifierGen (UPDLOCK) ) INSERT INTO UniqueIdentifierGen VALUES (0) UPDATE UniqueIdentifierGen SET CurIdentifier = CurIdentifier + 1 SELECT @OutIdentifier = (SELECT CurIdentifier FROM UniqueIdentifierGen) END The code looks like: CallableStatement statement = connection .prepareCall("{call dbo.spWCoTaskIdGen(?)}"); statement.setInt(1, 0); ResultSet result = statement.executeQuery(); I get the following error: SEVERE: Could not find stored procedure 'dbo.spWCoTaskIdGen'. I have also tried CallableStatement statement = connection .prepareCall("{? = call dbo.spWCoTaskIdGen(?)}"); statement.registerOutParameter(1, java.sql.Types.INTEGER); statement.registerOutParameter(2, java.sql.Types.INTEGER); statement.executeQuery(); The above results in: SEVERE: Could not find stored procedure 'dbo.spWCoTaskIdGen'. I have also tried: CallableStatement statement = connection .prepareCall("{? = call spWCoTaskIdGen(?)}"); statement.registerOutParameter(1, java.sql.Types.INTEGER); statement.registerOutParameter(2, java.sql.Types.INTEGER); statement.executeQuery(); The code above resulted in the following error: Could not find stored procedure 'spWCoTaskIdGen'. Finally, I should also point out the following: I have used the MS SQL Server Management Studio tool and have been able to successfully run the stored procedure. The sql generated to execute the stored procedure is provided below: GO DECLARE @return_value int, @OutIdentifier int EXEC @return_value = [dbo].[spWCoTaskIdGen] @OutIdentifier = @OutIdentifier OUTPUT SELECT @OutIdentifier as N'@OutIdentifier ' SELECT 'Return Value' = @return_value GO The code being executed runs with the same user id that was used in point #1 above. In the code that creates the Connection object I log which database I'm connecting to and the code is connecting to the correct database. Any ideas? Thank you very much in advance.

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  • Ideas for multiplatform encrypted java mobile storage system

    - by Fernando Miguélez
    Objective I am currently designing the API for a multiplatform storage system that would offer same interface and capabilities accross following supported mobile Java Platforms: J2ME. Minimum configuration/profile CLDC 1.1/MIDP 2.0 with support for some necessary JSRs (JSR-75 for file storage). Android. No minimum platform version decided yet, but rather likely could be API level 7. Blackberry. It would use the same base source of J2ME but taking advantage of some advaced capabilities of the platform. No minimum configuration decided yet (maybe 4.6 because of 64 KB limitation for RMS on 4.5). Basically the API would sport three kind of stores: Files. These would allow standard directory/file manipulation (read/write through streams, create, mkdir, etc.). Preferences. It is a special store that handles properties accessed through keys (Similar to plain old java properties file but supporting some improvements such as different value data types such as SharedPreferences on Android platform) Local Message Queues. This store would offer basic message queue functionality. Considerations Inspired on JSR-75, all types of stores would be accessed in an uniform way by means of an URL following RFC 1738 conventions, but with custom defined prefixes (i.e. "file://" for files, "prefs://" for preferences or "queue://" for message queues). The address would refer to a virtual location that would be mapped to a physical storage object by each mobile platform implementation. Only files would allow hierarchical storage (folders) and access to external extorage memory cards (by means of a unit name, the same way as in JSR-75, but that would not change regardless of underlying platform). The other types would only support flat storage. The system should also support a secure version of all basic types. The user would indicate it by prefixing "s" to the URL (i.e. "sfile://" instead of "file://"). The API would only require one PIN (introduced only once) to access any kind of secure object types. Implementation issues For the implementation of both plaintext and encrypted stores, I would use the functionality available on the underlying platforms: Files. These are available on all platforms (J2ME only with JSR-75, but it is mandatory for our needs). The abstract File to actual File mapping is straight except for addressing issues. RMS. This type of store available on J2ME (and Blackberry) platforms is convenient for Preferences and maybe Message Queues (though depending on performance or size requirements these could be implemented by means of normal files). SharedPreferences. This type of storage, only available on Android, would match Preferences needs. SQLite databases. This could be used for message queues on Android (and maybe Blackberry). When it comes to encryption some requirements should be met: To ease the implementation it will be carried out on read/write operations basis on streams (for files), RMS Records, SharedPreferences key-value pairs, SQLite database columns. Every underlying storage object should use the same encryption key. Handling of encrypted stores should be the same as the unencrypted counterpart. The only difference (from the user point of view) accessing an encrypted store would be the addressing. The user PIN provides access to any secure storage object, but the change of it would not require to decrypt/re-encrypt all the encrypted data. Cryptographic capabilities of underlying platform should be used whenever it is possible, so we would use: J2ME: SATSA-CRYPTO if it is available (not mandatory) or lightweight BoncyCastle cryptographic framework for J2ME. Blackberry: RIM Cryptographic API or BouncyCastle Android: JCE with integraced cryptographic provider (BouncyCastle?) Doubts Having reached this point I was struck by some doubts about what solution would be more convenient, taking into account the limitation of the plataforms. These are some of my doubts: Encryption Algorithm for data. Would AES-128 be strong and fast enough? What alternatives for such scenario would you suggest? Encryption Mode. I have read about the weakness of ECB encryption versus CBC, but in this case the first would have the advantage of random access to blocks, which is interesting for seek functionality on files. What type of encryption mode would you choose instead? Is stream encryption suitable for this case? Key generation. There could be one key generated for each storage object (file, RMS RecordStore, etc.) or just use one for all the objects of the same type. The first seems "safer", though it would require some extra space on device. In your opinion what would the trade-offs of each? Key storage. For this case using a standard JKS (or PKCS#12) KeyStore file could be suited to store encryption keys, but I could also define a smaller structure (encryption-transformation / key data / checksum) that could be attached to each storage store (i.e. using addition files with the same name and special extension for plain files or embedded inside other types of objects such as RMS Record Stores). What approach would you prefer? And when it comes to using a standard KeyStore with multiple-key generation (given this is your preference), would it be better to use a record-store per storage object or just a global KeyStore keeping all keys (i.e. using the URL identifier of abstract storage object as alias)? Master key. The use of a master key seems obvious. This key should be protected by user PIN (introduced only once) and would allow access to the rest of encryption keys (they would be encrypted by means of this master key). Changing the PIN would only require to reencrypt this key and not all the encrypted data. Where would you keep it taking into account that if this got lost all data would be no further accesible? What further considerations should I take into account? Platform cryptography support. Do SATSA-CRYPTO-enabled J2ME phones really take advantage of some dedicated hardware acceleration (or other advantage I have not foreseen) and would this approach be prefered (whenever possible) over just BouncyCastle implementation? For the same reason is RIM Cryptographic API worth the license cost over BouncyCastle? Any comments, critics, further considerations or different approaches are welcome.

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