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• MySQL Cluster 7.3 Labs Release – Foreign Keys Are In!

  - by Mat Keep

  0 0 1 1097 6254 Homework 52 14 7337 14.0 Normal 0 false false false EN-US JA X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:Cambria; mso-ascii-font-family:Cambria; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Cambria; mso-hansi-theme-font:minor-latin; mso-ansi-language:EN-US;} Summary (aka TL/DR): Support for Foreign Key constraints has been one of the most requested feature enhancements for MySQL Cluster. We are therefore extremely excited to announce that Foreign Keys are part of the first Labs Release of MySQL Cluster 7.3 – available for download, evaluation and feedback now! (Select the mysql-cluster-7.3-labs-June-2012 build) In this blog, I will attempt to discuss the design rationale, implementation, configuration and steps to get started in evaluating the first MySQL Cluster 7.3 Labs Release. Pace of Innovation It was only a couple of months ago that we announced the General Availability (GA) of MySQL Cluster 7.2, delivering 1 billion Queries per Minute, with 70x higher cross-shard JOIN performance, Memcached NoSQL key-value API and cross-data center replication.  This release has been a huge hit, with downloads and deployments quickly reaching record levels. The announcement of the first MySQL Cluster 7.3 Early Access lab release at today's MySQL Innovation Day event demonstrates the continued pace in Cluster development, and provides an opportunity for the community to evaluate and feedback on new features they want to see. What’s the Plan for MySQL Cluster 7.3? Well, Foreign Keys, as you may have gathered by now (!), and this is the focus of this first Labs Release. As with MySQL Cluster 7.2, we plan to publish a series of preview releases for 7.3 that will incrementally add new candidate features for a final GA release (subject to usual safe harbor statement below*), including: - New NoSQL APIs; - Features to automate the configuration and provisioning of multi-node clusters, on premise or in the cloud; - Performance and scalability enhancements; - Taking advantage of features in the latest MySQL 5.x Server GA. Design Rationale MySQL Cluster is designed as a “Not-Only-SQL” database. It combines attributes that enable users to blend the best of both relational and NoSQL technologies into solutions that deliver web scalability with 99.999% availability and real-time performance, including: Concurrent NoSQL and SQL access to the database; Auto-sharding with simple scale-out across commodity hardware; Multi-master replication with failover and recovery both within and across data centers; Shared-nothing architecture with no single point of failure; Online scaling and schema changes; ACID compliance and support for complex queries, across shards. Native support for Foreign Key constraints enables users to extend the benefits of MySQL Cluster into a broader range of use-cases, including: - Packaged applications in areas such as eCommerce and Web Content Management that prescribe databases with Foreign Key support. - In-house developments benefiting from Foreign Key constraints to simplify data models and eliminate the additional application logic needed to maintain data consistency and integrity between tables. Implementation The Foreign Key functionality is implemented directly within MySQL Cluster’s data nodes, allowing any client API accessing the cluster to benefit from them – whether using SQL or one of the NoSQL interfaces (Memcached, C++, Java, JPA or HTTP/REST.) The core referential actions defined in the SQL:2003 standard are implemented: CASCADE RESTRICT NO ACTION SET NULL In addition, the MySQL Cluster implementation supports the online adding and dropping of Foreign Keys, ensuring the Cluster continues to serve both read and write requests during the operation. An important difference to note with the Foreign Key implementation in InnoDB is that MySQL Cluster does not support the updating of Primary Keys from within the Data Nodes themselves - instead the UPDATE is emulated with a DELETE followed by an INSERT operation. Therefore an UPDATE operation will return an error if the parent reference is using a Primary Key, unless using CASCADE action, in which case the delete operation will result in the corresponding rows in the child table being deleted. The Engineering team plans to change this behavior in a subsequent preview release. Also note that when using InnoDB "NO ACTION" is identical to "RESTRICT". In the case of MySQL Cluster “NO ACTION” means “deferred check”, i.e. the constraint is checked before commit, allowing user-defined triggers to automatically make changes in order to satisfy the Foreign Key constraints. Configuration There is nothing special you have to do here – Foreign Key constraint checking is enabled by default. If you intend to migrate existing tables from another database or storage engine, for example from InnoDB, there are a couple of best practices to observe: 1. Analyze the structure of the Foreign Key graph and run the ALTER TABLE ENGINE=NDB in the correct sequence to ensure constraints are enforced 2. Alternatively drop the Foreign Key constraints prior to the import process and then recreate when complete. Getting Started Read this blog for a demonstration of using Foreign Keys with MySQL Cluster.  You can download MySQL Cluster 7.3 Labs Release with Foreign Keys today - (select the mysql-cluster-7.3-labs-June-2012 build) If you are new to MySQL Cluster, the Getting Started guide will walk you through installing an evaluation cluster on a singe host (these guides reflect MySQL Cluster 7.2, but apply equally well to 7.3) Post any questions to the MySQL Cluster forum where our Engineering team will attempt to assist you. Post any bugs you find to the MySQL bug tracking system (select MySQL Cluster from the Category drop-down menu) And if you have any feedback, please post them to the Comments section of this blog. Summary MySQL Cluster 7.2 is the GA, production-ready release of MySQL Cluster. This first Labs Release of MySQL Cluster 7.3 gives you the opportunity to preview and evaluate future developments in the MySQL Cluster database, and we are very excited to be able to share that with you. Let us know how you get along with MySQL Cluster 7.3, and other features that you want to see in future releases. * Safe Harbor Statement This information is intended to outline our general product direction. It is intended for information purposes only, and may not be incorporated into any contract. It is not a commitment to deliver any material, code, or functionality, and should not be relied upon in making purchasing decisions. The development, release, and timing of any features or functionality described for Oracle’s products remains at the sole discretion of Oracle.

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• LINQ – SequenceEqual() method

  - by nmarun

  I have been looking at LINQ extension methods and have blogged about what I learned from them in my blog space. Next in line is the SequenceEqual() method. Here’s the description about this method: “Determines whether two sequences are equal by comparing the elements by using the default equality comparer for their type.” Let’s play with some code: 1: int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 }; 2: // int[] numbersCopy = numbers; 3: int[] numbersCopy = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 }; 4:  5: Console.WriteLine(numbers.SequenceEqual(numbersCopy)); This gives an output of ‘True’ – basically compares each of the elements in the two arrays and returns true in this case. The result is same even if you uncomment line 2 and comment line 3 (I didn’t need to say that now did I?). So then what happens for custom types? For this, I created a Product class with the following definition: 1: class Product 2: { 3: public int ProductId { get; set; } 4: public string Name { get; set; } 5: public string Category { get; set; } 6: public DateTime MfgDate { get; set; } 7: public Status Status { get; set; } 8: } 9:  10: public enum Status 11: { 12: Active = 1, 13: InActive = 2, 14: OffShelf = 3, 15: } In my calling code, I’m just adding a few product items: 1: private static List<Product> GetProducts() 2: { 3: return new List<Product> 4: { 5: new Product 6: { 7: ProductId = 1, 8: Name = "Laptop", 9: Category = "Computer", 10: MfgDate = new DateTime(2003, 4, 3), 11: Status = Status.Active, 12: }, 13: new Product 14: { 15: ProductId = 2, 16: Name = "Compact Disc", 17: Category = "Water Sport", 18: MfgDate = new DateTime(2009, 12, 3), 19: Status = Status.InActive, 20: }, 21: new Product 22: { 23: ProductId = 3, 24: Name = "Floppy", 25: Category = "Computer", 26: MfgDate = new DateTime(1993, 3, 7), 27: Status = Status.OffShelf, 28: }, 29: }; 30: } Now for the actual check: 1: List<Product> products1 = GetProducts(); 2: List<Product> products2 = GetProducts(); 3:  4: Console.WriteLine(products1.SequenceEqual(products2)); This one returns ‘False’ and the reason is simple – this one checks for reference equality and the products in the both the lists get different ‘memory addresses’ (sounds like I’m talking in ‘C’). In order to modify this behavior and return a ‘True’ result, we need to modify the Product class as follows: 1: class Product : IEquatable<Product> 2: { 3: public int ProductId { get; set; } 4: public string Name { get; set; } 5: public string Category { get; set; } 6: public DateTime MfgDate { get; set; } 7: public Status Status { get; set; } 8:  9: public override bool Equals(object obj) 10: { 11: return Equals(obj as Product); 12: } 13:  14: public bool Equals(Product other) 15: { 16: //Check whether the compared object is null. 17: if (ReferenceEquals(other, null)) return false; 18:  19: //Check whether the compared object references the same data. 20: if (ReferenceEquals(this, other)) return true; 21:  22: //Check whether the products' properties are equal. 23: return ProductId.Equals(other.ProductId) 24: && Name.Equals(other.Name) 25: && Category.Equals(other.Category) 26: && MfgDate.Equals(other.MfgDate) 27: && Status.Equals(other.Status); 28: } 29:  30: // If Equals() returns true for a pair of objects 31: // then GetHashCode() must return the same value for these objects. 32: // read why in the following articles: 33: // http://geekswithblogs.net/akraus1/archive/2010/02/28/138234.aspx 34: // http://stackoverflow.com/questions/371328/why-is-it-important-to-override-gethashcode-when-equals-method-is-overriden-in-c 35: public override int GetHashCode() 36: { 37: //Get hash code for the ProductId field. 38: int hashProductId = ProductId.GetHashCode(); 39:  40: //Get hash code for the Name field if it is not null. 41: int hashName = Name == null ? 0 : Name.GetHashCode(); 42:  43: //Get hash code for the ProductId field. 44: int hashCategory = Category.GetHashCode(); 45:  46: //Get hash code for the ProductId field. 47: int hashMfgDate = MfgDate.GetHashCode(); 48:  49: //Get hash code for the ProductId field. 50: int hashStatus = Status.GetHashCode(); 51: //Calculate the hash code for the product. 52: return hashProductId ^ hashName ^ hashCategory & hashMfgDate & hashStatus; 53: } 54:  55: public static bool operator ==(Product a, Product b) 56: { 57: // Enable a == b for null references to return the right value 58: if (ReferenceEquals(a, b)) 59: { 60: return true; 61: } 62: // If one is null and the other not. Remember a==null will lead to Stackoverflow! 63: if (ReferenceEquals(a, null)) 64: { 65: return false; 66: } 67: return a.Equals((object)b); 68: } 69:  70: public static bool operator !=(Product a, Product b) 71: { 72: return !(a == b); 73: } 74: } Now THAT kinda looks overwhelming. But lets take one simple step at a time. Ok first thing you’ve noticed is that the class implements IEquatable<Product> interface – the key step towards achieving our goal. This interface provides us with an ‘Equals’ method to perform the test for equality with another Product object, in this case. This method is called in the following situations: when you do a ProductInstance.Equals(AnotherProductInstance) and when you perform actions like Contains<T>, IndexOf() or Remove() on your collection Coming to the Equals method defined line 14 onwards. The two ‘if’ blocks check for null and referential equality using the ReferenceEquals() method defined in the Object class. Line 23 is where I’m doing the actual check on the properties of the Product instances. This is what returns the ‘True’ for us when we run the application. I have also overridden the Object.Equals() method which calls the Equals() method of the interface. One thing to remember is that anytime you override the Equals() method, its’ a good practice to override the GetHashCode() method and overload the ‘==’ and the ‘!=’ operators. For detailed information on this, please read this and this. Since we’ve overloaded the operators as well, we get ‘True’ when we do actions like: 1: Console.WriteLine(products1.Contains(products2[0])); 2: Console.WriteLine(products1[0] == products2[0]); This completes the full circle on the SequenceEqual() method. See the code used in the article here.

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• How to properly test for constraint violation in hibernate?

  - by Cesar

  I'm trying to test Hibernate mappings, specifically a unique constraint. My POJO is mapped as follows: <property name="name" type="string" unique="true" not-null="true" /> What I want to do is to test that I can't persist two entities with the same name: @Test(expected=ConstraintViolationException.class) public void testPersistTwoExpertiseAreasWithTheSameNameIsNotAllowed(){ ExpertiseArea ea = new ExpertiseArea("Design"); ExpertiseArea otherEA = new ExpertiseArea("Design"); ead.setSession(getSessionFactory().getCurrentSession()); ead.getSession().beginTransaction(); ead.makePersistent(ea); ead.makePersistent(otherEA); ead.getSession().getTransaction().commit(); } On commiting the current transaction, I can see in the logs that a ConstraintViolationException is thrown: 16:08:47,571 DEBUG SQL:111 - insert into ExpertiseArea (VERSION, name, id) values (?, ?, ?) Hibernate: insert into ExpertiseArea (VERSION, name, id) values (?, ?, ?) 16:08:47,571 DEBUG SQL:111 - insert into ExpertiseArea (VERSION, name, id) values (?, ?, ?) Hibernate: insert into ExpertiseArea (VERSION, name, id) values (?, ?, ?) 16:08:47,572 WARN JDBCExceptionReporter:100 - SQL Error: -104, SQLState: 23505 16:08:47,572 ERROR JDBCExceptionReporter:101 - integrity constraint violation: unique constraint or index violation; SYS_CT_10036 table: EXPERTISEAREA 16:08:47,573 ERROR AbstractFlushingEventListener:324 - Could not synchronize database state with session org.hibernate.exception.ConstraintViolationException: Could not execute JDBC batch update So I would expect the test to pass, since the expected ConstraintViolationException is thrown. However, the test never completes (neither pass nor fails) and I have to manually kill the test runner. What's the correct way to test this?

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• SQLite vs Firebird

  - by rwallace

  The scenario I'm looking at is "This program uses Postgres. Oh, you want to just use it single-user for the moment, and put off having to deal with installing a database server? Okay, in the meantime you can use it with the embedded single-user database." The question is then which embedded database is best. As I understand it, the two main contenders are SQLite and Firebird; so which is better? Criteria: Full SQL support, or as close as reasonably possible. Full text search. Easy to call from C# Locks, or allows you to lock, the database file to make sure nobody tries to run it multiuser and ends up six months down the road with intermittent data corruption in all their backups. Last but far from least, reliability. As I understand it, the disadvantages of SQLite are, No right outer join. Workaround: use left outer join instead. Not much integrity checking. Workaround: be really careful in the application code. No decimal numbers. Workaround: lots of aspirin. None of the above are showstoppers. Are there any others I'm missing? (I know it doesn't support some administrative and code-within-database SQL features, that aren't relevant for this kind of use case.) I don't know anything much about Firebird. What are its disadvantages?

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• "Pretty" Continuous Integration for Python

  - by dbr

  This is a slightly.. vain question, but BuildBot's output isn't particularly nice to look at.. For example, compared to.. phpUnderControl Hudson CruiseControl.rb ..and others, BuildBot looks rather.. archaic I'm currently playing with Hudson, but it is very Java-centric (although with this guide, I found it easier to setup than BuildBot, and produced more info) Basically: is there any Continuous Integration systems aimed at python, that produce lots of shiney graphs and the likes? Update: After trying a few alternatives, I think I'll stick with Hudson. Integrity was nice and simple, but quite limited. I think Buildbot is better suited to having numerous build-slaves, rather than everything running on a single machine like I was using it. Setting Hudson up for a Python project was pretty simple: Download Hudson from https://hudson.dev.java.net/ Run it with java -jar hudson.war Open the web interface on the default address of http://localhost:8080 Go to Manage Hudson, Plugins, click "Update" or similar Install the Git plugin (I had to set the git path in the Hudson global preferences) Create a new project, enter the repository, SCM polling intervals and so on Install nosetests via easy_install if it's not already In the a build step, add nosetests --with-xunit --verbose Check "Publish JUnit test result report" and set "Test report XMLs" to **/nosetests.xml That's all that's required. You can setup email notifications, and the plugins are worth a look. A few I'm currently using for Python projects: SLOCCount plugin to count lines of code (and graph it!) - you need to install sloccount separately Violations to parse the PyLint output (you can setup warning thresholds, graph the number of violations over each build) Cobertura can parse the coverage.py output. Nosetest can gather coverage while running your tests, using nosetests --with-coverage (this writes the output to **/coverage.xml)

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• Are there code signing certificates cheaper than US$99 per year? [closed]

  - by gerryLowry

  K Software discounts Comodo code signing certificates to US$99 per year. In the past, I've seen Commodo code signing certificates for US$80. I'm excluding CAcert which AFAIK are FREE but are not covered by browsers like Internet Explorer AFAIK. QUESTION: What is the best price per year for a code signing certificate? Thank you ~~ gerry (lowry) Edit: **THIS SHOULD NOT HAVE BEEN CLOSED** from the FAQ: http://stackoverflow.com/faq ---------------------------- What kind of questions can I ask here? Programming questions, of course! As long as your question is: * detailed and specific <====== YES! * written clearly and simply <====== YES! * of interest to other programmers <====== YES! I've been programming for over 40 years. http://gerrylowryprogrammer.com/ I've taught computer programming at the community college level. I'm a Star level contributer to forums.asp.net. http://forums.asp.net/members/gerrylowry.aspx IMO, I've a very good idea what is of interest to other programmers. MORE INFORMATION http://en.wikipedia.org/wiki/Code_signing http://msdn.microsoft.com/en-us/library/ms537361%28VS.85%29.aspx also: via Google: code signing Ensuring the integrity of code and executables that one distributes is just as much about programming as is knowing how to flip bits in assembler, use delegates in C#, and use the BDD context/specification still of "test first testing".

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• certificate issues running app in windows 7 ?

  - by Jurjen

  Hi, I'm having some problems with my App. I'm using 'org.mentalis.security' assembly to create a certificate object from a 'pfx' file, this is the line of code where the exception occurs : Certificate cert = Certificate.CreateFromPfxFile(publicKey, certificatePassword); this has always worked and still does in production, but for some reason it throws an exception when run in windows 7 (tried it on 2 machines). CertificateException : Unable to import the PFX file! [error code = -2146893792] I can't find much on this message via google, but when checking the EventViewer I get an 'Audit Failure' every time this exception occurs: Event ID = 5061 Source = Microsoft Windows Security Task Category = system Integrity Keywords = Audit Failure Cryptographic operation. Subject: Security ID: NT AUTHORITY\IUSR Account Name: IUSR Account Domain: NT AUTHORITY Logon ID: 0x3e3 Cryptographic Parameters: Provider Name: Microsoft Software Key Storage Provider Algorithm Name: Not Available. Key Name: VriendelijkeNaam Key Type: User key. Cryptographic Operation: Operation: Open Key. Return Code: 0x2 ` I'm not sure why this isn't working on win 7, I've never had problems when I was running on Vista with this. I am running VS2008 as administrator but I guess that maybe the ASP.NET user doesn't have sufficient rights or something. It's pretty strangs that the 'Algorithm name' is 'Not Available' can anyone help me with this... TIA, Jurjen de Groot

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• Magento install errors

  - by nXqd

  I try to install new magento version 1.4.xx . But after the config menu I meet after I copy and change local.example.xml to local.xml . Error in file: "E:\Soft\Programming\xampp\htdocs\magento\app\code\core\Mage\Catalog\sql\catalog_setup\mysql4-install-1.4.0.0.0.php" - SQLSTATE[23000]: Integrity constraint violation: 1062 Duplicate entry '4-page_layout' for key 'entity_type_id' Trace: #0 E:\Soft\Programming\xampp\htdocs\magento\app\code\core\Mage\Core\Model\Resource\Setup.php(374): Mage::exception('Mage_Core', 'Error in file: ...') #1 E:\Soft\Programming\xampp\htdocs\magento\app\code\core\Mage\Core\Model\Resource\Setup.php(260): Mage_Core_Model_Resource_Setup->_modifyResourceDb('install', '', '1.4.0.0.21') #2 E:\Soft\Programming\xampp\htdocs\magento\app\code\core\Mage\Core\Model\Resource\Setup.php(224): Mage_Core_Model_Resource_Setup->_installResourceDb('1.4.0.0.21') #3 E:\Soft\Programming\xampp\htdocs\magento\app\code\core\Mage\Core\Model\Resource\Setup.php(153): Mage_Core_Model_Resource_Setup->applyUpdates() #4 E:\Soft\Programming\xampp\htdocs\magento\app\code\core\Mage\Core\Model\App.php(363): Mage_Core_Model_Resource_Setup::applyAllUpdates() #5 E:\Soft\Programming\xampp\htdocs\magento\app\code\core\Mage\Core\Model\App.php(295): Mage_Core_Model_App->_initModules() #6 E:\Soft\Programming\xampp\htdocs\magento\app\Mage.php(596): Mage_Core_Model_App->run(Array) #7 E:\Soft\Programming\xampp\htdocs\magento\index.php(78): Mage::run('', 'store') #8 {main} I really need your help , thanks so much :)

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• Non-Relational Database Design

  - by Ian Varley

  I'm interested in hearing about design strategies you have used with non-relational "nosql" databases - that is, the (mostly new) class of data stores that don't use traditional relational design or SQL (such as Hypertable, CouchDB, SimpleDB, Google App Engine datastore, Voldemort, Cassandra, SQL Data Services, etc.). They're also often referred to as "key/value stores", and at base they act like giant distributed persistent hash tables. Specifically, I want to learn about the differences in conceptual data design with these new databases. What's easier, what's harder, what can't be done at all? Have you come up with alternate designs that work much better in the non-relational world? Have you hit your head against anything that seems impossible? Have you bridged the gap with any design patterns, e.g. to translate from one to the other? Do you even do explicit data models at all now (e.g. in UML) or have you chucked them entirely in favor of semi-structured / document-oriented data blobs? Do you miss any of the major extra services that RDBMSes provide, like relational integrity, arbitrarily complex transaction support, triggers, etc? I come from a SQL relational DB background, so normalization is in my blood. That said, I get the advantages of non-relational databases for simplicity and scaling, and my gut tells me that there has to be a richer overlap of design capabilities. What have you done? FYI, there have been StackOverflow discussions on similar topics here: the next generation of databases changing schemas to work with Google App Engine choosing a document-oriented database

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• How to prepopulate an Outlook MailItem and avoiding a com Exception from the object model guard

  - by torrente

  Hi, I work for a company that develops a CRM tool and offers integration with MS Office(2003 & 2007) from windows XP to 7. (I'm working using Win7) My task is to call an Outlook instance (using C#) from this CRM tool when the user wants to send an email and prepopulate with data of the CRM tool (email, recipient, etc..) All of this already works just fine. The problem I'm having is that Outlook's "object model guard" is throwing com Exception (Operation aborted (Exception from HRESULT: 0x80004004 (E_ABORT))) the moment I try to read a protected value from the mailItem (such as mail.bodyHTML). Example Snippet: using MSOutlook = Microsoft.Office.Interop.Outlook; //untrusted Instance _outlook = new MSOutlook.Application(); MSOutlook.MailItem mail = (MSOutlook.MailItem)_outlook.CreateItem(MSOutlook.OlItemType.olMailItem); //this where the Exception occurs string outlookStdHTMLBody = mail.HTMLBody; I've done quite a bit of reading and know that my Outlook Instance (derived by using new Application) is considered untrusted and therefore the "omg" kicks in. I do have a workaround for development: I'm running VS2010 as Administrator and if I run Outlook as Administrator as well - all is good. I suppose this is due to them having the same integrity levels(high) and the UAC(?) is not complaining. But that just ain't the way to go for deployment. Now the question is: Is there a way to obtain a trusted instance of Outlook so that I can avoid this exception? I've already read that when developing an Office Add-In using VSTO one can obtain a trusted Instance from the OnComplete event and/or using "ThisAddin" But I "merely" want to start an outlook instance and preopulate it, and do not want to develop an Add-In since this is not the requirement. And to make it clear - I have no problem with pop ups informing the user that outlook is being accessed - I just want to get rid of the exception! So how can I get around this problem using code? Any help is highly appreciated! Thomas

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• Padding is invalid and cannot be removed

  - by Ajay

  I have hosted an asp.net 2.0 site. Everyday, i am getting an error "Padding is invalid and cannot be removed" 2-3 times. Backend used is sql server 2005. the site is controlled via plesk 9.2 CP. Pooling is enabled with timeout as 120 Minutes, in IIS. Can it be the reason for this? I have not used any encryption except for the stored passwords(MD5) The error message is : " Base Exception = : Padding is invalid and cannot be removed. - Source : System.Web - TargetSite :Void ThrowError(System.Exception, System.String, System.String, Boolean)Message : Validation of viewstate MAC failed. If this application is hosted by a Web Farm or cluster, ensure that configuration specifies the same validationKey and validation algorithm. AutoGenerate cannot be used in a cluster. " & System Log (Application) says " Event code: 4009 Event message: Viewstate verification failed. Reason: The viewstate supplied failed integrity check. Event detail code: 50203 ViewStateException information: Exception message: Invalid viewstate. Port: 31235 User-Agent: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1) " I have hosted it in a dedicated server and not in a web farm. Will keeping a static machine key help resolve this issue? Please guide me on this.

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• Symfony fk issue on insertion

  - by Daniel Hertz

  Hi, I posted a similar problem but it could not be resolved. I create a relational database of users and groups but for some reason I cannot insert test data with fixtures properly. Here is a sample of the schema: User: actAs: { Timestampable: ~ } columns: name: { type: string(255), notnull: true } email: { type: string(255), notnull: true, unique: true } nickname: { type: string(255), unique: true } password: { type: string(300), notnull: true } image: { type: string(255) } Group: actAs: { Timestampable: ~ } columns: name: { type: string(500), notnull: true } image: { type: string(255) } type: { type: string(255), notnull: true } created_by_id: { type: integer } relations: User: { onDelete: SET NULL, class: User, local: created_by_id, foreign: id, foreignAlias: groups_created } FanOf: actAs: { Timestampable: ~ } columns: user_id: { type: integer, primary: true } group_id: { type: integer, primary: true } relations: User: { onDelete: CASCADE, local: user_id, foreign: id, foreignAlias: fanhood } Group: { onDelete: CASCADE, local: group_id, foreign: id, foreignAlias: fanhood } And this is the data i try to input: User: user1: name: Danny email: [email protected] nickname: danny password: f05050400c5e586fa6629ef497be Group: group1: name: Mets type: sports FanOf: fans1: user_id: user1 group_id: group1 I keep getting this error: SQLSTATE[23000]: Integrity constraint violation: 1452 Cannot add or update a child row: a foreign key constraint fails (`krowdd`.`fan_of`, CONSTRAINT `fan_of_user_id_user_id` FOREIGN KEY (`user_id`) REFERENCES `user` (`id`) ON DELETE CASCADE) The users and groups are clearly being created before the "fanhood" is so why am I getting this error?? Thanks!

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• are there code signing certificates cheaper than US $99 per year? [closed]

  - by gerryLowry

  ksoftware discounts Commodo code signing certificates to US $99 per year. in the past, I've seen Commodo code signing certificates for US $80. I'm excluding CAcert which AFAIK are FREE but are not covered by browsers like IE AFAIK. QUESTION: What is the best price per year for a code signing certificate? Thank you ~~ gerry (lowry) Edit: **THIS SHOULD NOT HAVE BEEN CLOSED** from the FAQ: http://stackoverflow.com/faq ---------------------------- What kind of questions can I ask here? Programming questions, of course! As long as your question is: * detailed and specific <====== YES! * written clearly and simply <====== YES! * of interest to other programmers <====== YES! I've been programming for over 40 years. http://gerrylowryprogrammer.com/ I've taught computer programming at the community college level. I'm a Star level contributer to forums.asp.net. http://forums.asp.net/members/gerrylowry.aspx imo, I've a very good idea what is of interest to other programmers. MORE INFORMATION Ensuring the integrity of code and executables that one distributes is just as much about programming as is knowing how to flip bits in assembler, use delegates in c#, and use the BDD context/specification still of "test first testing".

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• HTML to 'pretty' text conversion for printing on text only printer (dot matrix)

  - by Gala101

  Hi, I have a web-site that generates some simple tabular data as html tables, many of my users print the web-page on a laser/inkjet printer; however some like to print on legacy Dot Matrix printers (text only) and there-in lies the problem. When giving Print from web-browser onto dot-matrix printer, the printer actually perceives data as 'graphic'/image and proceeds to print it dot-by-dot. i.e If printing a character 'C', printer slices it horizontally and prints in 3-4 passes. Same printer prints a text from an ASCII file (say from notepad) as complete characters in single pass, thereby being 5 times faster and much quieter than when printing a web-page. (Even tried 'generic text-only driver' but Mozilla Firefox has a know bug that it does not print anything over this particular driver since 2.0+) So is there some clean way of formatting an already generated HTML (say method takes the entire html table as string) and generates a corresponding text file with properly aligned columns? I have tried stripping the html tags, but the major issue there is performing good 'wrapping' of a cell's data and maintaining integrity of other cells' data (from same row). eg: ( '|' and '_' not really required) Col1 | Col2 | Colum_Name3 | Col4 | _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 1 | this cell | this column | smaller | | is in three| spans 2 rows | | | rows | | | - - - - - - - - - - - - - - - - - - - - - - - - 2 | smaller now| this also | but this| | | | cell's | | | | data is | | | | now | | | | bigger | _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Could you please suggest preferred approach? I've thought of using xslt and somehow outputting text (instead of more prevalent pdf), but Apache FOP's text renderer is really broken and perhaps forgotten in development path. Commercial one's are way too costly.

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• LINQDataSource and private columns

  - by fyjham

  Hey, I was trying to use a ListView bound to a LinqDataSource to insert to a table where I had a few columns private to the table class (Specifically password columns - only access I want to give outside the class is methods that generate the salt and encrypt the password to store it in 1 go). I gave this a few shots, but I didn't come up with anything I really liked... was wondering if anyone has a better way to do this. The methods I've found: Use the LinqDataSource inserting event and make the appropriate calls on e.NewObject. I don't really like this because it's so far removed from the actual input and there's no simple way to hold the password in the meantime other than a class variable set during the ListView's inserting event (Which works, but seems a little dodgy). Open up these properties and just ask everyone to use the appropriate static methods for encoding the passwords they pass in. I don't really like this cause I'd prefer that class to enforce data integrity rather than relying on all calling code doing it properly... I'm currently going with option #1, but I don't really like passing values between events using class variables like that (It just seems unstructured... even though I can guarantee the events will happen in the right order). Does anyone know a better way, or alternatively am I being too pedantic and one of the methods above is actually the right way to go? Thanks

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• How can I make this method more Scalalicious

  - by Neil Chambers

  I have a function that calculates the left and right node values for some collection of treeNodes given a simple node.id, node.parentId association. It's very simple and works well enough...but, well, I am wondering if there is a more idiomatic approach. Specifically is there a way to track the left/right values without using some externally tracked value but still keep the tasty recursion. /* * A tree node */ case class TreeNode(val id:String, val parentId: String){ var left: Int = 0 var right: Int = 0 } /* * a method to compute the left/right node values */ def walktree(node: TreeNode) = { /* * increment state for the inner function */ var c = 0 /* * A method to set the increment state */ def increment = { c+=1; c } // poo /* * the tasty inner method * treeNodes is a List[TreeNode] */ def walk(node: TreeNode): Unit = { node.left = increment /* * recurse on all direct descendants */ treeNodes filter( _.parentId == node.id) foreach (walk(_)) node.right = increment } walk(node) } walktree(someRootNode) Edit - The list of nodes is taken from a database. Pulling the nodes into a proper tree would take too much time. I am pulling a flat list into memory and all I have is an association via node id's as pertains to parents and children. Adding left/right node values allows me to get a snapshop of all children (and childrens children) with a single SQL query. The calculation needs to run very quickly in order to maintain data integrity should parent-child associations change (which they do very frequently). In addition to using the awesome Scala collections I've also boosted speed by using parallel processing for some pre/post filtering on the tree nodes. I wanted to find a more idiomatic way of tracking the left/right node values. After looking at the answers listed I have settled on this synthesised version: def walktree(node: TreeNode) = { def walk(node: TreeNode, counter: Int): Int = { node.left = counter node.right = treeNodes .filter( _.parentId == node.id) .foldLeft(counter+1) { (counter, curnode) => walk(curnode, counter) + 1 } node.right } walk(node,1) }

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• Foreign key not working in MySQL: Why can I INSERT a value that's not in the foreign column?

  - by stalepretzel

  I've created a table in MySQL: CREATE TABLE actions ( A_id int NOT NULL AUTO_INCREMENT, type ENUM('rate','report','submit','edit','delete') NOT NULL, Q_id int NOT NULL, U_id int NOT NULL, date DATE NOT NULL, time TIME NOT NULL, rate tinyint(1), PRIMARY KEY (A_id), CONSTRAINT fk_Question FOREIGN KEY (Q_id) REFERENCES questions(P_id), CONSTRAINT fk_User FOREIGN KEY (U_id) REFERENCES users(P_id)); This created the table I wanted just fine (although a "DESCRIBE actions;" command showed me that the foreign keys were keys of type MUL, and I'm not sure what this means). However, when I try to enter a Q_id or a U_id that does not exist in the questions or users tables, MySQL still allows these values. What did I do wrong? How can I prevent a table with a foreign key from accepting invalid data? If I add TYPE=InnoDB to the end, I get an error: ERROR 1005 (HY000): Can't create table './quotes/actions.frm' (errno: 150) Why might that happen? I'm told that it's important to enforce data integrity with functional foreign keys, but also that InnoDB should not be used with MySQL. What do you recommend?

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• Which Table Should be Master and Child in Database Design

  - by Jason

  I am quickly learning the ins and outs of database design (something that, as of a week ago, was new to me), but I am running across some questions that don't seem immediately obvious, so I was hoping to get some clarification. The question I have right is about foreign keys. As part of my design, I have a Company table. Originally, I had included address information directly within the table, but, as I was hoping to achieve 3NF, I broke out the address information into its own table, Address. In order to maintain data integrity, I created a row in Company called "addressId" as an INT and the Address table has a corresponding addressId as its primary key. What I'm a little bit confused about (or what I want to make sure I'm doing correctly) is determining which table should be the master (referenced) table and which should be the child (referencing) table. When I originally set this up, I made the Address table the master and the Company the child. However, I now believe this is wrong due to the fact that there should be only one address per Company and, if a Company row is deleted, I would want the corresponding Address to be removed as well (CASCADE deletion). I may be approaching this completely wrong, so I would appreciate any good rules of thumb on how to best think about the relationship between tables when using foreign keys. Thanks!

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• ISBNs are used as primary key, now I want to add non-book things to the DB - should I migrate to EAN

  - by fish2000

  I built an inventory database where ISBN numbers are the primary keys for the items. This worked great for a while as the items were books. Now I want to add non-books. some of the non-books have EANs or ISSNs, some do not. It's in PostgreSQL with django apps for the frontend and JSON api, plus a few supporting python command-line tools for management. the items in question are mostly books and artist prints, some of which are self-published. What is nice about using ISBNs as primary keys is that in on top of relational integrity, you get lots of handy utilities for validating ISBNs, automatically looking up missing or additional information on the book items, etcetera, many of which I've taken advantage. some such tools are off-the-shelf (PyISBN, PyAWS etc) and some are hand-rolled -- I tried to keep all of these parts nice and decoupled, but you know how things can get. I couldn't find anything online about 'private ISBNs' or 'self-assigned ISBNs' but that's the sort of thing I was interested in doing. I doubt that's what I'll settle on, since there is already an apparent run on ISBN numbers. should I retool everything for EAN numbers, or migrate off ISBNs as primary keys in general? if anyone has any experience with working with these systems, I'd love to hear about it, your advice is most welcome.

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• How to speed up an already cached pip install?

  - by Maxime R.

  I frequently have to re-create virtual environments from a requirements.txt and I am already using $PIP_DOWNLOAD_CACHE. It still takes a lot of time and I noticed the following: Pip spends a lot of time between the following two lines: Downloading/unpacking SomePackage==1.4 (from -r requirements.txt (line 2)) Using download cache from $HOME/.pip_download_cache/cached_package.tar.gz Like ~20 seconds on average to decide it's going to use the cached package, then the install is fast. This is a lot of time when you have to install dozens of packages (actually enough to write this question). What is going on in the background? Are they some sort of integrity checks against the online package? Is there a way to speed this up? edit: Looking at: time pip install -v Django==1.4 I get: real 1m16.120s user 0m4.312s sys 0m1.280s The full output is here http://pastebin.com/e4Q2B5BA. Looks like pip is spending his time looking for a valid download link while it already has a valid cache of http://pypi.python.org/packages/source/D/Django/Django-1.4.tar.gz. Is there a way to look for the cache first and stop there if versions match?

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• Counting string length in javascript and Ruby on Rails

  - by williamjones

  I've got a text area on a web site that should be limited in length. I'm allowing users to enter 255 characters, and am enforcing that limit with a Rails validation: validates_length_of :body, :maximum => 255 At the same time, I added a javascript char counter like you see on Twitter, to give feedback to the user on how many characters he has already used, and to disable the submit button when over length, and am getting that length in Javascript with a call like this: element.length Lastly, to enforce data integrity, in my Postgres database, I have created this field as a varchar(255) as a last line of defense. Unfortunately, these methods of counting characters do not appear to be directly compatible. Javascript counts the best, in that it counts what users consider as number of characters where everything is a single character. Once the submission hits Rails, however, all of the carriage returns have been converted to \r\n, now taking up 2 characters worth of space, which makes a close call fail Rails validations. Even if I were to handcode a different length validation in Rails, it would still fail when it hits the database I think, though I haven't confirmed this yet. What's the best way for me to make all this work the way the user would want? Best Solution: an approach that would enable me to meet user expectations, where each character of any type is only one character. If this means increasing the length of the varchar database field, a user should not be able to sneakily send a hand-crafted post that creates a row with more than 255 letters. Somewhat Acceptable Solution: a javascript change that enables the user to see the real character count, such that hitting return increments the counter 2 characters at a time, while properly handling all symbols that might have these strange behaviors.

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• how to design a schema where the columns of a table are not fixed

  - by hIpPy

  I am trying to design a schema where the columns of a table are not fixed. Ex: I have an Employee table where the columns of the table are not fixed and vary (attributes of Employee are not fixed and vary). Nullable columns in the Employee table itself i.e. no normalization Instead of adding nullable columns, separate those columns out in their individual tables ex: if Address is a column to be added then create table Address[EmployeeId, AddressValue]. Create tables ExtensionColumnName [EmployeeId, ColumnName] and ExtensionColumnValue [EmployeeId, ColumnValue]. ExtensionColumnName would have ColumnName as "Address" and ExtensionColumnValue would have ColumnValue as address value. Employee table EmployeeId Name ExtensionColumnName table ColumnNameId EmployeeId ColumnName ExtensionColumnValue table EmployeeId ColumnNameId ColumnValue There is a drawback is the first two ways as the schema changes with every new attribute. Note that adding a new attribute is frequent. I am not sure if this is the good or bad design. If someone had a similar decision to make, please give an insight on things like foreign keys / data integrity, indexing, performance, reporting etc.

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• MSSQL: Views that use SELECT * need to be recreated if the underlying table changes

  - by cbp

  Is there a way to make views that use SELECT * stay in sync with the underlying table. What I have discovered is that if changes are made to the underlying table, from which all columns are to be selected, the view needs to be 'recreated'. This can be achieved simly by running an ALTER VIEW statement. However this can lead to some pretty dangerous situations. If you forgot to recreate the view, it will not be returning the correct data. In fact it can be returning seriously messed up data - with the names of the columns all wrong and out of order. Nothing will pick up that the view is wrong unless you happened to have it covered by a test, or a data integrity check fails. For example, Red Gate SQL Compare doesn't pick up the fact that the view needs to be recreated. To replicate the problem, try these statements: CREATE TABLE Foobar (Bar varchar(20)) CREATE VIEW v_Foobar AS SELECT * FROM Foobar INSERT INTO Foobar (Bar) VALUES ('Hi there') SELECT * FROM v_Foobar ALTER TABLE Foobar ADD Baz varchar(20) SELECT * FROM v_Foobar DROP VIEW v_Foobar DROP TABLE Foobar I am tempted to stop using SELECT * in views, which will be a PITA. Is there a setting somewhere perhaps that could fix this behaviour?

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• How to improve multi-threaded access to Cache (custom implementation)

  - by Andy

  I have a custom Cache implementation, which allows to cache TCacheable<TKey> descendants using LRU (Least Recently Used) cache replacement algorithm. Every time an element is accessed, it is bubbled up to the top of the LRU queue using the following synchronized function: // a single instance is created to handle all TCacheable<T> elements public class Cache() { private object syncQueue = new object(); private void topQueue(TCacheable<T> el) { lock (syncQueue) if (newest != el) { if (el.elder != null) el.elder.newer = el.newer; if (el.newer != null) el.newer.elder = el.elder; if (oldest == el) oldest = el.newer; if (oldest == null) oldest = el; if (newest != null) newest.newer = el; el.newer = null; el.elder = newest; newest = el; } } } The bottleneck in this function is the lock() operator, which limits cache access to just one thread at a time. Question: Is it possible to get rid of lock(syncQueue) in this function while still preserving the queue integrity?

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• How can I help fellow students struggling in programming classes?

  - by David Barry

  I'm a computer science student finishing up my second semester of programming classes. I've enjoyed them quite a bit, and learned a lot, but it seems other students are struggling with the concepts and assignments more than I am. When an assignment is due, the inevitable group email comes out the day or two before with people needing some help either with a specific part of the problem, or sometimes people just seem to have a hard time knowing where to start. I'd really like to be able to help out, but I have a hard time thinking of the right way to give them help without giving them the answer. When I'm having trouble understanding a concept, a code snippet can go along way to helping me, but at the same time if it makes a lot of sense, it can be difficult to think of another way to go about it. Plus the Academic Integrity section of each assignment is always looming overhead warning against sharing code with others. I've tried using pseudo code to help give others an idea on program flow, leaving them to figure out how to implement certain aspects of it, but I didn't get too much feedback and don't know how much it actually helped them out, or if it just confused them further. So I'm basically looking to see if anyone has experience with this, or good ways that I can help out other students to nudge them in the right direction or help them think about the problem in the right way.

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