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• Why am I getting this error when overriding an inherited method?

  - by Sergio Tapia

  Here's my parent class: public abstract class BaseFile { public string Name { get; set; } public string FileType { get; set; } public long Size { get; set; } public DateTime CreationDate { get; set; } public DateTime ModificationDate { get; set; } public abstract void GetFileInformation(); public abstract void GetThumbnail(); } And here's the class that's inheriting it: public class Picture:BaseFile { public override void GetFileInformation(string filePath) { FileInfo fileInformation = new FileInfo(filePath); if (fileInformation.Exists) { Name = fileInformation.Name; FileType = fileInformation.Extension; Size = fileInformation.Length; CreationDate = fileInformation.CreationTime; ModificationDate = fileInformation.LastWriteTime; } } public override void GetThumbnail() { } } I thought when a method was overridden, I could do what I wanted with it. Any help please? :)

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• Problem with 2 levels of inheritance in hibernate mapping

  - by Seth

  Here's my class structure: class A class B extends A class C extends A class D extends C class E extends C And here are my mappings (class bodies omitted for brevity): Class A: @Entity @Inheritance(strategy=InheritanceType.SINGLE_TABLE) @MappedSuperclass @DiscriminatorColumn( name="className", discriminatorType=DiscriminatorType.STRING ) @ForceDiscriminator public abstract class A Class B: @Entity @DiscriminatorValue("B") public class B extends A Class C: @Entity @DiscriminatorValue("C") @MappedSuperclass @DiscriminatorColumn( name="cType", discriminatorType=DiscriminatorType.STRING ) @ForceDiscriminator public abstract class C extends A Class D: @Entity @DiscriminatorValue("D") public class D extends C Class E: @Entity @DiscriminatorValue("E") public class E extends C I've got a class F that contains a set of A: @Entity public class F { ... @OneToMany(fetch=FetchType.LAZY, cascade=CascadeType.ALL) @JoinTable( name="F_A", joinColumns = @JoinColumn(name="A_ID"), inverseJoinColumns = @JoinColumn(name="F_ID") ) private Set<A> aSet = new HashSet<A>(); ... The problem is that whenever I add a new E instance to aSet and then call session.saveOrUpdate(fInstance), hibernate saves with "A" as the discrimiator string. When I try to access the aSet in the F instance, I get the following exception (full stacktrace ommitted for brevity): org.hibernate.InstantiationException: Cannot instantiate abstract class or interface: path.to.class.A Am I mapping the classes incorrectly? How am I supposed to map multiple levels of inheritance? Thanks for the help!

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• how to read xml properties value?

  - by bala

  I have xml file in sdcard(xxx.file) how to read all the xml tag properties values starting point to end point and prints that value please help me I am not familiar in xml pullparser please help me... This is my xml file code: <?xml version="1.0"?> <layout schemaVersion="1" width="800" height="450" bgcolor="#000000"> <region id="47ff29524ce1b" width="800" height="450" top="0" left="0" userId="1"> <media id="9" type="image" duration="30" lkid="4" userId="1" schemaVersion="1"> <options><uri>9.png</uri></options> <raw/> </media></region></layout> java code: public class MainActivity extends Activity { @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); try{ XmlPullParserFactory factory = XmlPullParserFactory.newInstance(); factory.setNamespaceAware(true); XmlPullParser parser = factory.newPullParser(); File file = new File(Environment.getExternalStorageDirectory()+ "/xxx.xml"); FileInputStream fis = new FileInputStream(file); parser.setInput(new InputStreamReader(fis)); }catch(XmlPullParserException e){ e.printStackTrace(); }catch(FileNotFoundException e){ e.printStackTrace(); } } }

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• How to get the set of beans that are to be created in Spring?

  - by cyborg

  So here's the scenario: I have a Spring XML configuration with some lazy-beans, some not lazy-beans and some beans that depend on other beans. Eventually Spring will resolve all this so that only the beans that are meant to be created are created. The question: how can I programmatically tell what this set is? When I use context.getBean(name) that initializes the bean. BeanDefinition.isLazyInit() will only tell me how I defined the bean. Any other ideas? ETA: In DefaultListableBeanFactory: public void preInstantiateSingletons() throws BeansException { if (this.logger.isInfoEnabled()) { this.logger.info("Pre-instantiating singletons in " + this); } synchronized (this.beanDefinitionMap) { for (Iterator it = this.beanDefinitionNames.iterator(); it.hasNext();) { String beanName = (String) it.next(); RootBeanDefinition bd = getMergedLocalBeanDefinition(beanName); if (!bd.isAbstract() && bd.isSingleton() && !bd.isLazyInit()) { if (isFactoryBean(beanName)) { FactoryBean factory = (FactoryBean) getBean(FACTORY_BEAN_PREFIX + beanName); if (factory instanceof SmartFactoryBean && ((SmartFactoryBean) factory).isEagerInit()) { getBean(beanName); } } else { getBean(beanName); } } } } } The set of instantiable beans is initialized. When initializing this set any beans not in this set referenced by this set will also be created. From looking through the source it does not look like there's going to be any easy way to answer my question.

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• MySQL running on an EC2 m1.small instance has high load but low memory usage, possible resolutions?

  - by Tosh

  I have a MySQL server 5.0.75 Ubuntu, on an m1.small instance running on Amazon's EC2 as part of an application. During peak usage the server load will rise very high, while the memory usage stays low and the application server is no longer responsive since it's waiting for query results. The application server has only 5-8 apache processes running (mod_perl processes). The data directory uses only 140MB of data so the MyIsam tables aren't very big. The queries are pretty complicated with some big joins being performed, and the application makes a lot of queries. mysqltuner reports everything OK except "Maximum possible memory usage: 1.7G (99% of installed RAM)" but I'm nowhere close to using that. My question is, where should I be looking to fix this? Is this something that can be tuned away, or do I just need a larger instance/server? Googling indicates either or also upgrading MySQL server. Any pointers in the right direction would be greatly appreciated, thanks! EDIT: I just discovered this in my slow queries log: # Time: 101116 11:17:00 # User@Host: user[pass] @ [host] # Query_time: 4063 Lock_time: 1035 Rows_sent: 0 Rows_examined: 19960174 SELECT * FROM contacts WHERE contacts.contact_id IN (SELECT external_id FROM contact_relations WHERE external_table = 'contacts' AND contact_id IN (SELECT contact_id FROM contacts WHERE (company_name like '%%butan%%%' OR country like '%%butan%%%' OR city like '%%butan%%%' OR email1 like '%%butan%%%') AND (company_name is not null and company_name != ''))); Which actually brings up a different but related question: If I have a contact table containing: John Smith,The Fun Factory,555-1212,[email protected] What's the best way to search for that record using "factory" as a search key? Fulltext rarely seems to find items in the middle of a word, for example "actor" should bring up "Factory"

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• Reordering fields in Django model

  - by Alex Lebedev

  I want to add few fields to every model in my django application. This time it's created_at, updated_at and notes. Duplicating code for every of 20+ models seems dumb. So, I decided to use abstract base class which would add these fields. The problem is that fields inherited from abstract base class come first in the field list in admin. Declaring field order for every ModelAdmin class is not an option, it's even more duplicate code than with manual field declaration. In my final solution, I modified model constructor to reorder fields in _meta before creating new instance: class MyModel(models.Model): # Service fields notes = my_fields.NotesField() created_at = models.DateTimeField(auto_now_add=True) updated_at = models.DateTimeField(auto_now=True) class Meta: abstract = True last_fields = ("notes", "created_at", "updated_at") def __init__(self, *args, **kwargs): new_order = [f.name for f in self._meta.fields] for field in self.last_fields: new_order.remove(field) new_order.append(field) self._meta._field_name_cache.sort(key=lambda x: new_order.index(x.name)) super(TwangooModel, self).__init__(*args, **kwargs) class ModelA(MyModel): field1 = models.CharField() field2 = models.CharField() #etc ... It works as intended, but I'm wondering, is there a better way to acheive my goal?

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• Where should I put validation code?

  - by D Lawson

  I'm creating interfaces and abstract classes that represent a messaging framework for short text-based messages like SMS, email, twitter, xml, etc.. and I was wondering where I should put the message validation code. The thing is that I am only writing the superclasses and interfaces, so I'm not putting the actual implementation in, I'll just put the hooks in that allow others to validate the content of the messages. The way I see it, I could do it several ways: in the abstract superclass "Message", have an abstract method 'isValid'. A variation on this would be to have isValid be called when the Message constructor is called, throwing a MalformedMessageException if the message is formatted incorrectly. in the transport layer, immediately before sending, validate the message. I would have a send(Message) method that calls an isValid(Message) method immediately before it sends. have a singleton message validator with a static method isValid(Message) that is called at some point. I'm sure there are other options that I'm missing. Currently, I'm leaning towards the first one, but it doesn't feel right to me to have validation code in what should be a domain object.

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• Creating mock Objects in PHP unit

  - by Mike

  Hi, I've searched but can't quite find what I'm looking for and the manual isn't much help in this respect. I'm fairly new to unit testing, so not sure if I'm on the right track at all. Anyway, onto the question. I have a class: <?php class testClass { public function doSomething($array_of_stuff) { return AnotherClass::returnRandomElement($array_of_stuff); } } ?> Now, clearly I want the AnotherClass::returnRandomElement($array_of_stuff); to return the same thing every time. My question is, in my unit test, how do I mockup this object? I've tried adding the AnotherClass to the top of the test file, but when I want to test AnotherClass I get the "Cannot redeclare class" error. I think I understand factory classes, but I'm not sure how I would apply that in this instance. Would I need to write an entirely seperate AnotherClass class which contained test data and then use the Factory class to load that instead of the real AnotherClass? Or is using the Factory pattern just a red herring. I tried this: $RedirectUtils_stub = $this->getMockForAbstractClass('RedirectUtils'); $o1 = new stdClass(); $o1->id = 2; $o1->test_id = 2; $o1->weight = 60; $o1->data = "http://www.google.com/?ffdfd=fdfdfdfd?route=1"; $RedirectUtils_stub->expects($this->any()) ->method('chooseRandomRoot') ->will($this->returnValue($o1)); $RedirectUtils_stub->expects($this->any()) ->method('decodeQueryString') ->will($this->returnValue(array())); in the setUp() function, but these stubs are ignored and I can't work out whether it's something I'm doing wrong, or the way I'm accessing the AnotherClass methods. Help! This is driving me nuts.

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• Java - How to pass a Generic parameter as Class<T> to a constructor

  - by Joe Almore

  I have a problem here that still cannot solve, the thing is I have this abstract class: public abstract class AbstractBean<T> { private Class<T> entityClass; public AbstractBean(Class<T> entityClass) { this.entityClass = entityClass; }... Now I have another class that inherits this abstract: @Stateless @LocalBean public class BasicUserBean<T extends BasicUser> extends AbstractBean<T> { private Class<T> user; public BasicUserBean() { super(user); // Error: cannot reference user before supertype contructor has been called. } My question is how can I make this to work?, I am trying to make the class BasicUserBean inheritable, so if I have class PersonBean which inherits BasicUserBean then I could set in the Generic the entity Person which also inherits the entity BasicUser. And it will end up being: @Stateless @LocalBean public class PersonBean extends BasicUserBean<Person> { public PersonBean() { super(Person.class); } ... I just want to inherit the basic functionality from BasicUserBean to all descendants, so I do not have to repeat the same code among all descendants. Thanks!.

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• Enums and inheritance

  - by devoured elysium

  I will use (again) the following class hierarchy: Event and all the following classes inherit from Event: SportEventType1 SportEventType2 SportEventType3 SportEventType4 I have originally designed the Event class like this: public abstract class Event { public abstract EventType EventType { get; } public DateTime Time { get; protected set; } protected Event(DateTime time) { Time = time; } } with EventType being defined as: public enum EventType { Sport1, Sport2, Sport3, Sport4 } The original idea would be that each SportEventTypeX class would set its correct EventType. Now that I think of it, I think this approach is totally incorrect for two reasons: If I want to later add a new SportEventType class I will have to modify the enum If I later decide to remove one SportEventType that I feel I won't use I'm also in big trouble with the enum. I have a class variable in the Event class that makes, afterall, assumptions about the kind of classes that will inherit from it, which kinda defeats the purpose of inheritance. How would you solve this kind of situation? Define in the Event class an abstract "Description" property, having each child class implement it? Having an Attribute(Annotation in Java!) set its Description variable instead? What would be the pros/cons of having a class variable instead of attribute/annotation in this case? Is there any other more elegant solution out there? Thanks

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• router w/ WOL out-of-the-box, or is known to work with open firmware

  - by Jaroslav Záruba

  I'm looking for a new WiFi router, and one key feature for me is WOL. Seems like many routers won't do this w/ factory firmware. Given my last router (Asus WL-520g) turned into a disco-brick couple hours after flashed to dd-wrt I'd prefer if the new one supported WOL out-of-the-box. other required features would be: dyndns service support port forwarding sometimes it is called "virtual server" I guess NAT loopback so I can access services running in my own network using dyndns hostname or public IP w/o getting too old (for example DIR-615 with factory firmware lets you wait literally minutes) did I mention WiFi? preferably w/ some range extending technology, if such stuff works at all

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• JNDI Datasource definition in Tomcat 6.0

  - by romaintaz

  I want to define a DataSource to an Oracle database on my Tomcat 6.0. So, in conf/server.xml (yes, I know that this DataSource will be available for all the webapps in Tomcat, but it's not a problem here), I've set this Resource: <GlobalNamingResources> <Resource name="hibernate/HibernateDS" auth="Container" type="javax.sql.DataSource" url="jdbc:oracle:thin:@myserver:1542:foo" username="foo" password="bar" driverClassName="oracle.jdbc.OracleDriver" maxActive="50" maxIdle="10" validationQuery="select 1 from dual"/> Then, in the web.xml of my application, I set a resource-ref element: <resource-ref> <description>Hibernate Datasource</description> <res-ref-name>hibernate/HibernateDS</res-ref-name> <res-type>javax.sql.DataSource</res-type> <res-auth>Container</res-auth> </resource-ref> Finally, as Hibernate is used to manage the database connection, I have a webapps/mywebapp/WEB-INF/classes/hibernate.cfg.xml that creates a session-factory using the JNDI DataSource: <hibernate-configuration> <session-factory> <property name="connection.datasource">java:comp/env/hibernate/HibernateDS</property> ... However, when I start my Tomcat server, I get an error that says it could not create the INFO [net.sf.hibernate.util.NamingHelper] JNDI InitialContext properties:{} INFO [net.sf.hibernate.connection.DatasourceConnectionProvider] Using datasource: java:comp/env/hibernate/HibernateDS INFO [net.sf.hibernate.transaction.TransactionFactoryFactory] Transaction strategy: net.sf.hibernate.transaction.JDBCTransactionFactory INFO [net.sf.hibernate.transaction.TransactionManagerLookupFactory] No TransactionManagerLookup configured (in JTA environment, use of process level read-write cache is not recommended) WARN [net.sf.hibernate.cfg.SettingsFactory] Could not obtain connection metadata org.apache.tomcat.dbcp.dbcp.SQLNestedException: Cannot create JDBC driver of class '' for connect URL 'null' at org.apache.tomcat.dbcp.dbcp.BasicDataSource.createDataSource(BasicDataSource.java:1150) at org.apache.tomcat.dbcp.dbcp.BasicDataSource.getConnection(BasicDataSource.java:880) at net.sf.hibernate.connection.DatasourceConnectionProvider.getConnection(DatasourceConnectionProvider.java:59) at net.sf.hibernate.cfg.SettingsFactory.buildSettings(SettingsFactory.java:84) at net.sf.hibernate.cfg.Configuration.buildSettings(Configuration.java:1172) ... Caused by: java.lang.NullPointerException at sun.jdbc.odbc.JdbcOdbcDriver.getProtocol(JdbcOdbcDriver.java:507) at sun.jdbc.odbc.JdbcOdbcDriver.knownURL(JdbcOdbcDriver.java:476) at sun.jdbc.odbc.JdbcOdbcDriver.acceptsURL(JdbcOdbcDriver.java:307) at java.sql.DriverManager.getDriver(DriverManager.java:253) at org.apache.tomcat.dbcp.dbcp.BasicDataSource.createDataSource(BasicDataSource.java:1143) ... 11 more Do you have any idea why Hibernate is not able to construct the session-factory? What is wrong in my configuration?

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• JNDI Datasource definition in Tomcat 6.0

  - by romaintaz

  Hi all, I want to define a DataSource to an Oracle database on my Tomcat 6.0. So, in conf/server.xml (yes, I know that this DataSource will be available for all the webapps in Tomcat, but it's not a problem here), I've set this Resource: <GlobalNamingResources> <Resource name="hibernate/HibernateDS" auth="Container" type="javax.sql.DataSource" url="jdbc:oracle:thin:@myserver:1542:foo" username="foo" password="bar" driverClassName="oracle.jdbc.OracleDriver" maxActive="50" maxIdle="10" validationQuery="select 1 from dual"/> Then, in the web.xml of my application, I set a resource-ref element: <resource-ref> <description>Hibernate Datasource</description> <res-ref-name>hibernate/HibernateDS</res-ref-name> <res-type>javax.sql.DataSource</res-type> <res-auth>Container</res-auth> </resource-ref> Finally, as Hibernate is used to manage the database connection, I have a webapps/mywebapp/WEB-INF/classes/hibernate.cfg.xml that creates a session-factory using the JNDI DataSource: <hibernate-configuration> <session-factory> <property name="connection.datasource">java:comp/env/hibernate/HibernateDS</property> ... However, when I start my Tomcat server, I get an error that says it could not create the INFO [net.sf.hibernate.util.NamingHelper] JNDI InitialContext properties:{} INFO [net.sf.hibernate.connection.DatasourceConnectionProvider] Using datasource: java:comp/env/hibernate/HibernateDS INFO [net.sf.hibernate.transaction.TransactionFactoryFactory] Transaction strategy: net.sf.hibernate.transaction.JDBCTransactionFactory INFO [net.sf.hibernate.transaction.TransactionManagerLookupFactory] No TransactionManagerLookup configured (in JTA environment, use of process level read-write cache is not recommended) WARN [net.sf.hibernate.cfg.SettingsFactory] Could not obtain connection metadata org.apache.tomcat.dbcp.dbcp.SQLNestedException: Cannot create JDBC driver of class '' for connect URL 'null' at org.apache.tomcat.dbcp.dbcp.BasicDataSource.createDataSource(BasicDataSource.java:1150) at org.apache.tomcat.dbcp.dbcp.BasicDataSource.getConnection(BasicDataSource.java:880) at net.sf.hibernate.connection.DatasourceConnectionProvider.getConnection(DatasourceConnectionProvider.java:59) at net.sf.hibernate.cfg.SettingsFactory.buildSettings(SettingsFactory.java:84) at net.sf.hibernate.cfg.Configuration.buildSettings(Configuration.java:1172) ... Caused by: java.lang.NullPointerException at sun.jdbc.odbc.JdbcOdbcDriver.getProtocol(JdbcOdbcDriver.java:507) at sun.jdbc.odbc.JdbcOdbcDriver.knownURL(JdbcOdbcDriver.java:476) at sun.jdbc.odbc.JdbcOdbcDriver.acceptsURL(JdbcOdbcDriver.java:307) at java.sql.DriverManager.getDriver(DriverManager.java:253) at org.apache.tomcat.dbcp.dbcp.BasicDataSource.createDataSource(BasicDataSource.java:1143) ... 11 more Do you have any idea why Hibernate is not able to construct the session-factory? What is wrong in my configuration?

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• Complete Apple Powerbook G4 format without disk

  - by Sam

  I have gone through many sites to look for the exact answer. However I failed. What I want: To completely format my Powerbook G4 to factory or brand new without any DVD/CD or Disk/Disc I am not worried about ethical or un-ethical way. I just need to format the entire Powerbook G4 to factory setting WITHOUT ANY DVD/CD/DISC/DISK so that It’s a brand new one. I am ready to do anything, but please don’t advice me on buying or download the MAC OS 10.5 Leopard from torrent or blah blah.

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• I need to access another user's files.

  - by CDeanMartin

  My system is an HP netbook running Ubuntu 10 netbook edition from a USB drive. I created an admin account and user account, and left in place the 'ubuntu' account. My netbook came with Windows 7 factory loaded and I did some work in Windows before setting up Linux. I copied my work into the HP Tools FAT32 partition that also came Factory Loaded, and was only 20% full. Only the 'ubuntu' account shows the HP Tools partition. So I would like to either view the partition from the 'admin' or 'user' accounts, or copy files from the partition-to a folder accessible from admin or user. I have already tried right clicking the folder, selecting share, and installing the share package, but I got a string of errors and would prefer a short term, one time solution that does not involve installing the share package. All I need is a few plain text Windows files i was working on.

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• Unknown problem causing major computer failure, Booting problem with windows 7, mainly with 0x0000000A

  - by ken

  Where do I begin? OS=Windows 7 I think it all started when I ran an installation file. I suspect it may have been a virus (even though AVG scan didnt pick anything up). The installation failed, computer crashed then restarted. In the middle of the reboot, I get BSOD. Normal boot up doesnt work so I use safe mode. Method 1: Not a problem I thought cos I will do what I normally do and that was to recover from my image file. Unfortunately, my Acronis software cant recover in safe mode. Method 2: I created a bootable disc for the Acronis recovery software. Managed to boot to Acronis and started the recovery from image file. This fail with some error message (did not manage to record). Something to do with not be able to copy to $AVG folder. Method 3: At this stage, assumed it was still a virus causing the problem so decided to format that partition to remove everything and hopefully the virus too. Had a lot of problems trying to bypass the system to allow me to format but (i think- more on this later) I managed to do that. Image was recovered, thought problem was resolved. Tried to boot windows but new error: Boot Manager is missing. Read up on this and managed to copy the Boot Manager from my Laptop's Manufacturer's partition (partition contains factory setup image file). Windows loaded but new BSOD with 0x000000A problem. Method 4: Attempted to reinstall factory settings but this failed cos i suspect by formating the partition, I may have removed the recovery software. Tried to create a bootable dvd of factory setting but machine is so bad it continues to crash. Bootable dvd method failed. Method 5:Spent alot of time reading up on this error, even installed a software to help scan and fix the problem. Scan failed and software required money! Anyway, lots of BSOD with different error message like 0x00000001A and 0x0000000D1. Error message changes with some reboots. Method 6: Found a hotfix from the windows site to fix 0x0000000A problem, great I thought! In safe mode, I cant install the file cos of error:0x8007043c. Tried to then install the fix in normal mode but installation just hangs. Returned to safe mode and followed advice to bypass 0x8007043c by changing the BITS status (read here: http://www.vistaheads.com/forums/microsoft-public-windowsupdate/181931-error-number-0x8007043c-windows-update.html). However, my machine at this time is so flaky that it hangs everytime i right mouse click the computer icon. I am at my wits end. Ya help or ideas? Cheers

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• Cisco 2950 Express Setup

  - by adamtor45

  I've been donated a Cisco Catalyst 2950 Switch by the company I work for to have a play with. I've reset it back to Factory Defaults, but having an issue with getting to Express Setup. I've followed the Express Setup (And Factory Reset) guide as listed here: Catalyst 2950 Switch Getting Started Guide Everything goes fine, until I get to step 10, I enter 10.0.0.1 into the browser, but I just get a Error 324 response. ServerFault wouldn't let me post a picture, so here is a link to the browser screenshot: Does anyone have any suggestions as to what this may be? Thanks in advance!

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• Setting up Rails to work with sqlserver

  - by FortunateDuke

  Ok I followed the steps for setting up ruby and rails on my Vista machine and I am having a problem connecting to the database. Contents of database.yml development: adapter: sqlserver database: APPS_SETUP Host: WindowsVT06\SQLEXPRESS Username: se Password: paswd Run rake db:migrate from myapp directory ---------- rake aborted! no such file to load -- deprecated ADO I have dbi 0.4.0 installed and have created the ADO folder in C:\Ruby\lib\ruby\site_ruby\1.8\DBD\ADO I got the ado.rb from the dbi 0.2.2 What else should I be looking at to fix the issue connecting to the database? Please don't tell me to use MySql or Sqlite or Postgres. *UPDATE* I have installed the activerecord-sqlserver-adapter gem from --source=http://gems.rubyonrails.org Still not working. I have verified that I can connect to the database by logging into SQL Management Studio with the credentials. rake db:migrate --trace PS C:\Inetpub\wwwroot\myapp> rake db:migrate --trace (in C:/Inetpub/wwwroot/myapp) ** Invoke db:migrate (first_time) ** Invoke environment (first_time) ** Execute environment ** Execute db:migrate rake aborted! no such file to load -- deprecated C:/Ruby/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:27:in `gem_original_require' C:/Ruby/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:27:in `require' C:/Ruby/lib/ruby/gems/1.8/gems/activesupport-2.1.1/lib/active_support/dependencies.rb:510:in `require' C:/Ruby/lib/ruby/gems/1.8/gems/activesupport-2.1.1/lib/active_support/dependencies.rb:355:in `new_constants_in' C:/Ruby/lib/ruby/gems/1.8/gems/activesupport-2.1.1/lib/active_support/dependencies.rb:510:in `require' C:/Ruby/lib/ruby/site_ruby/1.8/dbi.rb:48 C:/Ruby/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:27:in `gem_original_require' C:/Ruby/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:27:in `require' C:/Ruby/lib/ruby/gems/1.8/gems/activesupport-2.1.1/lib/active_support/dependencies.rb:510:in `require' C:/Ruby/lib/ruby/gems/1.8/gems/activesupport-2.1.1/lib/active_support/dependencies.rb:355:in `new_constants_in' C:/Ruby/lib/ruby/gems/1.8/gems/activesupport-2.1.1/lib/active_support/dependencies.rb:510:in `require' C:/Ruby/lib/ruby/gems/1.8/gems/activesupport-2.1.1/lib/active_support/core_ext/kernel/requires.rb:7:in `require_library_ or_gem' C:/Ruby/lib/ruby/gems/1.8/gems/activesupport-2.1.1/lib/active_support/core_ext/kernel/reporting.rb:11:in `silence_warnin gs' C:/Ruby/lib/ruby/gems/1.8/gems/activesupport-2.1.1/lib/active_support/core_ext/kernel/requires.rb:5:in `require_library_ or_gem' C:/Ruby/lib/ruby/gems/1.8/gems/activerecord-sqlserver-adapter-1.0.0.9250/lib/active_record/connection_adapters/sqlserver _adapter.rb:29:in `sqlserver_connection' C:/Ruby/lib/ruby/gems/1.8/gems/activerecord-2.1.1/lib/active_record/connection_adapters/abstract/connection_specificatio n.rb:292:in `send' C:/Ruby/lib/ruby/gems/1.8/gems/activerecord-2.1.1/lib/active_record/connection_adapters/abstract/connection_specificatio n.rb:292:in `connection=' C:/Ruby/lib/ruby/gems/1.8/gems/activerecord-2.1.1/lib/active_record/connection_adapters/abstract/connection_specificatio n.rb:260:in `retrieve_connection' C:/Ruby/lib/ruby/gems/1.8/gems/activerecord-2.1.1/lib/active_record/connection_adapters/abstract/connection_specificatio n.rb:78:in `connection' C:/Ruby/lib/ruby/gems/1.8/gems/activerecord-2.1.1/lib/active_record/migration.rb:408:in `initialize' C:/Ruby/lib/ruby/gems/1.8/gems/activerecord-2.1.1/lib/active_record/migration.rb:373:in `new' C:/Ruby/lib/ruby/gems/1.8/gems/activerecord-2.1.1/lib/active_record/migration.rb:373:in `up' C:/Ruby/lib/ruby/gems/1.8/gems/activerecord-2.1.1/lib/active_record/migration.rb:356:in `migrate' C:/Ruby/lib/ruby/gems/1.8/gems/rails-2.1.1/lib/tasks/databases.rake:99 C:/Ruby/lib/ruby/gems/1.8/gems/rake-0.8.2/lib/rake.rb:621:in `call' C:/Ruby/lib/ruby/gems/1.8/gems/rake-0.8.2/lib/rake.rb:621:in `execute' C:/Ruby/lib/ruby/gems/1.8/gems/rake-0.8.2/lib/rake.rb:616:in `each' C:/Ruby/lib/ruby/gems/1.8/gems/rake-0.8.2/lib/rake.rb:616:in `execute' C:/Ruby/lib/ruby/gems/1.8/gems/rake-0.8.2/lib/rake.rb:582:in `invoke_with_call_chain' C:/Ruby/lib/ruby/1.8/monitor.rb:242:in `synchronize' C:/Ruby/lib/ruby/gems/1.8/gems/rake-0.8.2/lib/rake.rb:575:in `invoke_with_call_chain' C:/Ruby/lib/ruby/gems/1.8/gems/rake-0.8.2/lib/rake.rb:568:in `invoke' C:/Ruby/lib/ruby/gems/1.8/gems/rake-0.8.2/lib/rake.rb:2031:in `invoke_task' C:/Ruby/lib/ruby/gems/1.8/gems/rake-0.8.2/lib/rake.rb:2009:in `top_level' C:/Ruby/lib/ruby/gems/1.8/gems/rake-0.8.2/lib/rake.rb:2009:in `each' C:/Ruby/lib/ruby/gems/1.8/gems/rake-0.8.2/lib/rake.rb:2009:in `top_level' C:/Ruby/lib/ruby/gems/1.8/gems/rake-0.8.2/lib/rake.rb:2048:in `standard_exception_handling' C:/Ruby/lib/ruby/gems/1.8/gems/rake-0.8.2/lib/rake.rb:2003:in `top_level' C:/Ruby/lib/ruby/gems/1.8/gems/rake-0.8.2/lib/rake.rb:1982:in `run' C:/Ruby/lib/ruby/gems/1.8/gems/rake-0.8.2/lib/rake.rb:2048:in `standard_exception_handling' C:/Ruby/lib/ruby/gems/1.8/gems/rake-0.8.2/lib/rake.rb:1979:in `run' C:/Ruby/lib/ruby/gems/1.8/gems/rake-0.8.2/bin/rake:31 C:/Ruby/bin/rake:19:in `load' C:/Ruby/bin/rake:19 PS C:\Inetpub\wwwroot\myapp>

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• Facing Null Pointer Exception while using BIRT

  - by srikanth

  Hi, I am using BIRT APIs in a java program.My code is : package com.tecnotree.mdx.product.utils; import java.util.HashMap; import java.util.logging.Level; import org.eclipse.birt.core.exception.BirtException; import org.eclipse.birt.core.framework.Platform; import org.eclipse.birt.report.engine.api.EngineConfig; import org.eclipse.birt.report.engine.api.EngineConstants; import org.eclipse.birt.report.engine.api.HTMLRenderOption; import org.eclipse.birt.report.engine.api.IReportEngine; import org.eclipse.birt.report.engine.api.IReportEngineFactory; import org.eclipse.birt.report.engine.api.IReportRunnable; import org.eclipse.birt.report.engine.api.IRunAndRenderTask; import org.eclipse.birt.report.engine.api.ReportEngine; public class ExampleReport { public static void main(String[] args) { // Variables used to control BIRT Engine instance ReportEngine eng = null; IReportRunnable design = null; IRunAndRenderTask task = null; HTMLRenderOption renderContext = null; HashMap contextMap = null; HTMLRenderOption options = null; final EngineConfig conf = new EngineConfig(); conf .setEngineHome("C:\\birt-runtime-2_5_2\\birt-runtime-2_5_2\\ReportEngine"); System.out.println("conf " + conf.getBIRTHome()); conf.setLogConfig(null, Level.FINE); try { Platform.startup(conf); } catch (BirtException e1) { // TODO Auto-generated catch block e1.printStackTrace(); } IReportEngineFactory factory = (IReportEngineFactory) Platform .createFactoryObject(IReportEngineFactory.EXTENSION_REPORT_ENGINE_FACTORY); System.out.println("Factory : " + factory.toString()); System.out.println(conf.toString()); IReportEngine engine = factory.createReportEngine(conf); System.out.println("Engine : " + engine); try { design = eng .openReportDesign("C:\\birt-runtime-2_5_2\\birt-runtime-2_5_2\\ReportEngine\\samples\\hello_world.rptdesign"); } catch (Exception e) { System.err .println("An error occured during the opening of the report file!"); e.printStackTrace(); System.exit(-1); } task = eng.createRunAndRenderTask(design); renderContext = new HTMLRenderOption(); renderContext.setImageDirectory("image"); contextMap = new HashMap(); contextMap.put(EngineConstants.APPCONTEXT_HTML_RENDER_CONTEXT, renderContext); task.setAppContext(contextMap); options = new HTMLRenderOption(); options.setOutputFileName("c:/temp/output.html"); options.setOutputFormat("html"); task.setRenderOption(options); try { task.run(); } catch (Exception e) { System.err.println("An error occured while running the report!"); e.printStackTrace(); System.exit(-1); } System.out.println("All went well. Closing program!"); eng.destroy(); } } But i am facing NullPointerException while creating the report. STACKTRACE : Exception in thread "main" java.lang.NullPointerException at org.eclipse.birt.report.engine.api.impl.ReportEngine$EngineExtensionManager.<init>(ReportEngine.java:784) at org.eclipse.birt.report.engine.api.impl.ReportEngine.<init>(ReportEngine.java:109) at org.eclipse.birt.report.engine.api.impl.ReportEngineFactory$1.run(ReportEngineFactory.java:18) at org.eclipse.birt.report.engine.api.impl.ReportEngineFactory$1.run(ReportEngineFactory.java:1) at java.security.AccessController.doPrivileged(Native Method) at org.eclipse.birt.report.engine.api.impl.ReportEngineFactory.createReportEngine(ReportEngineFactory.java:14) at com.tecnotree.mdx.product.utils.ExampleReport.main(ExampleReport.java:47) Please help me regarding this... my project deadline has been reached... Appreciate your Reply Thanks in Advance

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• On REST: WADL or not IDL, is the following approach right ?

  - by redben

  This question is a bit long, please bear with me. In REST, i think we should not need WADL or any IDL. But rather something that would implicitly cover its concept. The way I think about it is when we (humans) surf the Web, when we go to a web site for the first time, we don't know what services it provides. You discover those on the html home page (or a sitemap page in a help section) or maybe just the main menu on the home page. If you make an analogy, the homepage or site map to us humans is what WSDL is to WS-* or what WADL could be to a REST service. Only that its just like any other html content. I think that in REST the following is a good way to do things, respecting the HATEOS paradigm. Have a top level (or default) resource that lists links to your other resources. For a library example, say RestLibrary.com/ it could be something like: <root xmlns:lib="http://librarystandards.com/libraryml"> <resource class="lib:book"> <link type="application/vnd.libraryml+xml" template="mylib.com/book/{isbn}" /> <link type="application/vnd.libraryml+xml" rel="add" href="mylib.com/book" method="POST" /> <link type="application/vnd.libraryml+xml" rel="update" template="mylib.com/book/{isbn}" method="PUT" /> </resource> <resource class="lib:bookList"> <link template="mylib.com/book?keywords={keywords}" type="application/vnd.openlibrary+xml" rel="search" /> </resource> </root> Note that it is assumed that the media type "application/vnd.libraryml+xml" is a defined standard or (may be just proprietary vocabulary) named libraryml. Also, the client should be able to understand this "homepage" resource (elements root, resource and link). This is the part that could be used instead of WADL : an Abstract vocabulary that should be understandable by any client. You could use an existing standard like Atom for example. But the main idea is to have an abstract vocabulary understandable by any client. Why not WADL then ? well wadl is only for service discovery. The idea here is to have an light abstract vocabulary that would serve as a base for hypermedia. A "root" vocabulary. Like in owl we have owl:thing...etc Now if the client knows the "libraryml" standard it can follow the links to the things it understands (after parsing the media type properties and xmlns). If not, it just won't. When i can't understand how to deal with something in REST architecture i tend to see how we Humans do it in the Web. In the Web, we have the Generic language that is HTML that enables site builders to deliver any specific content, regardless of its meaning to the client (the user), Browsers understand HTML but not the "meaning" of its content. It is the user that understands the (domain specific) content. If i go to say QuantumPhysics.org, my browser can render the home page (it is just html after all) and i can read the home page. If i understand quantum then fine i can continue browsing. If i don't i just get out (unless i want to learn the hardway :) ) In the RetsLibrary.com example the client app is just like me+my browser on QuantumPhysics.org. the media type "application/vnd.libraryml+xml" is quantum physics (knowledge). http is http in both examples. Now HTML of QuantumPhysics.org is in RestLibrary.com is XML + that tiny little abstract vocabulary (root resource and link, that you could replace with something like Atom). So does this approach have any value ? don't we need a root tiny hyper-vocabulary so we can succeed with hypermedia and the "initial URI" concept ? edit Yeah why not RDF as the root vocabulary !

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• Crypted_password is null when using Authlogic to save a user

  - by kareem

  i'm getting a strange error on my production install when i try and create a new user using AL: ActiveRecord::StatementInvalid: Mysql::Error: Column 'crypted_password' cannot be null: INSERT INTO users especially strange b/c it works as expected on my local box. RUnning Rails 2.3.2 and ruby 1.8.7 on both boxes. user.rb: class User < ActiveRecord::Base before_create :set_username acts_as_authentic do |c| c.require_password_confirmation = false c.login_field = "email" c.validates_length_of_password_field_options = {:minimum => 4} c.validate_login_field = false #don't validate email field with additional validations end end Here's output from my production console: >> u = User.new => #<User id: nil, username: nil, email: nil, crypted_password: nil, password_salt: nil, persistence_token: nil, single_access_token: nil, perishable_token: nil, login_count: 0, failed_login_count: 0, last_request_at: nil, current_login_at: nil, last_login_at: nil, current_login_ip: nil, last_login_ip: nil, created_at: nil, updated_at: nil, is_admin: 0, first_name: nil, last_name: nil> >> u.full_name = 'john smith' => "john smith" >> u.password = 'test' => "test" >> u.email = '[email protected]' => "[email protected]" >> u.valid? => true >> u.save ActiveRecord::StatementInvalid: Mysql::Error: Column 'crypted_password' cannot be null: INSERT INTO `users` (`single_access_token`, `last_request_at`, `created_at`, `crypted_password`, `perishable_token`, `updated_at`, `username`, `failed_login_count`, `current_login_ip`, `password_salt`, `current_login_at`, `is_admin`, `persistence_token`, `login_count`, `last_name`, `last_login_ip`, `last_login_at`, `email`, `first_name`) VALUES('B-XSXwhO7hkbtISIOyEq', NULL, '2009-07-31 01:10:44', NULL, 'FK3mYS2Tp5Tzeq5IXE1z', '2009-07-31 01:10:44', 'john', 0, NULL, NULL, NULL, 0, '2c76b645f761eb3509353290e93874cecdb68a63caa165812ab1b126d63660757090ecf69995caef9e78f93d070b524e2542b3fec4ee050726088c2a9fdb0c9f', 0, 'smith', NULL, NULL, '[email protected]', 'john') from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.2/lib/ active_record/connection_adapters/abstract_adapter.rb:212:in `log' from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.2/lib/ active_record/connection_adapters/mysql_adapter.rb:320:in `execute' from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.2/lib/ active_record/connection_adapters/abstract/database_statements.rb: 259:in `insert_sql' from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.2/lib/ active_record/connection_adapters/mysql_adapter.rb:330:in `insert_sql' from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.2/lib/ active_record/connection_adapters/abstract/database_statements.rb: 44:in `insert_without_query_dirty' from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.2/lib/ active_record/connection_adapters/abstract/query_cache.rb:18:in `insert' from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.2/lib/ active_record/base.rb:2902:in `create_without_timestamps' from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.2/lib/ active_record/timestamp.rb:29:in `create_without_callbacks' from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.2/lib/ active_record/callbacks.rb:266:in `create' from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.2/lib/ active_record/base.rb:2868:in `create_or_update_without_callbacks' from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.2/lib/ active_record/callbacks.rb:250:in `create_or_update' from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.2/lib/ active_record/base.rb:2539:in `save_without_validation' from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.2/lib/ active_record/validations.rb:1009:in `save_without_dirty' from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.2/lib/ active_record/dirty.rb:79:in `save_without_transactions' from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.2/lib/ active_record/transactions.rb:229:in `send' from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.2/lib/ active_record/transactions.rb:229:in `with_transaction_returning_status' from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.2/lib/ active_record/connection_adapters/abstract/database_statements.rb: 136:in `transaction' from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.2/lib/ active_record/transactions.rb:182:in `transaction' from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.2/lib/ active_record/transactions.rb:228:in `with_transaction_returning_status' from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.2/lib/ active_record/transactions.rb:196:in `save' from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.2/lib/ active_record/transactions.rb:208:in `rollback_active_record_state!' from /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.2/lib/ active_record/transactions.rb:196:in `save' No idea why this is happening, and especially why this saves a new user on dev but not on production. Any help is much appreciated, thanks! edit: using Apache & Passenger 2.2.4

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• New cast exception with VS2010/.Net 4

  - by Trevor

  [ Updated 25 May 2010 ] I've recently upgraded from VS2008 to VS2010, and at the same time upgraded to .Net 4. I've recompiled an existing solution of mine and I'm encountering a Cast exception I did not have before. The structure of the code is simple (although the actual implementation somewhat more complicated). Basically I have: public class SomeClass : ISomeClass { // Stuff } public static class ClassFactory { public static IInterface GetClassInstance<IInterface>(Type classType) { return (IInterface)Activator.CreateInstance(classType); // This throws a cast exception } } // Call the factory with: ISomeClass anInstance = ClassFactory.GetClassInstance<ISomeClass>(typeof(SomeClass)); Ignore the 'sensibleness' of the above - its provides just a representation of the issue rather than the specifics of what I'm doing (e.g. constructor parameters have been removed). The marked line throws the exception: Unable to cast object of type 'Namespace.SomeClass' to type 'Namespace.ISomeClass'. I suspect it may have something to do with the additional DotNet security (and in particular, explicit loading of assemblies, as this is something my app does). The reason I suspect this is that I have had to add to the config file the setting: <runtime> <loadFromRemoteSources enabled="true" /> </runtime> .. but I'm unsure if this is related. Update I see (from comments) that my basic code does not reproduce the issue by itself. Not surprising I suppose. It's going to be tricky to identify which part of a largish 3-tier CQS system is relevant to this problem. One issue might be that there are multiple assemblies involved. My static class is actually a factory provider, and the 'SomeClass' is a class factory (relevant in that the factories are 'registered' within the app via explicit assembly/type loading - see below) . Upfront I use reflection to 'register' all factories (i.e. classes that implement a particular interface) and that I do this when the app starts by identifying the relevant assemblies, loading them and adding them to a cache using (in essence): Loop over (file in files) { Assembly assembly = Assembly.LoadFile(file); baseAssemblyList.Add(assembly); } Then I cache the available types in these assemblies with: foreach (Assembly assembly in _loadedAssemblyList) { Type[] assemblyTypes = assembly.GetTypes(); _loadedTypesCache.AddRange(assemblyTypes); } And then I use this cache to do a variety of reflection operations, including 'registering' of factories, which involves looping through all loaded (cached) types and finding those that implement the (base) Factory interface. I've experienced what may be a similar problem in the past (.Net 3.5, so not exactly the same) with an architecture that involved dynamically creating classes on the server and streaming the compiled binary of those classes to the client app. The problem came when trying to deserialize an instance of the dynamic class on the client from a remote call: the exception said the class type was not know, even though the source and destination types were exactly the same name (including namespace). Basically the cross boundry versions of the class were not recognised as being the same. I solved that by intercepting the deserialization process and explicitly defining the deseriazation class type in the context of the local assemblies. This experience is what makes me think the types are considered mismatched because (somehow) the interface of the actual SomeClass object, and the interface of passed into the Generic method are not considered the same type. So (possibly) my question for those more knowledgable about C#/DotNet is: How does the class loading work that somehow my app thinks there are two versions/types of the interface type and how can I fit that? [ whew ... anyone who got here is quite patient .. thanks ]

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• Servlet response wrapper has encoding problem

  - by John O

  A servlet response wrapper is being used in a Servlet Filter. The idea is that the response is manipulated, with a 'nonce' value being injected into forms, as part of defence against CSRF attacks. The web app is using UTF-8 everywhere. When the Servlet Filter is absent, no problems. When the filter is added, encoding issues occur. (It seems as if the response is reverting to 8859-1.) The guts of the code : final class CsrfResponseWrapper extends AbstractResponseWrapper { ... byte[] modifyResponse(byte[] aInputResponse){ ... String originalInput = new String(aInputResponse, encoding); String modifiedResult = addHiddenParamToPostedForms(originalInput); result = modifiedResult.getBytes(encoding); ... } ... } As I understand it, the transition between byte-land and String-land should specify an encoding. That is done here, as you can see, in two places. The value of the 'encoding' variable is 'UTF-8'; the alteration of the String itself is standard string manipulation (with a regex), and never specifies an encoding (addHiddenParamToPostedForms). Where am I in error about the encoding? EDIT: Here is the base class (sorry it's rather long): package hirondelle.web4j.security; import javax.servlet.ServletOutputStream; import javax.servlet.ServletResponse; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpServletResponseWrapper; import java.io.ByteArrayOutputStream; import java.io.IOException; import java.io.PrintWriter; /** Abstract Base Class for altering response content. (May be useful in future contexts as well. For now, keep package-private.) */ abstract class AbstractResponseWrapper extends HttpServletResponseWrapper { AbstractResponseWrapper(ServletResponse aServletResponse) throws IOException { super((HttpServletResponse)aServletResponse); fOutputStream = new ModifiedOutputStream(aServletResponse.getOutputStream()); fWriter = new PrintWriter(fOutputStream); } /** Return the modified response. */ abstract byte[] modifyResponse(byte[] aInputResponse); /** Standard servlet method. */ public final ServletOutputStream getOutputStream() { //fLogger.fine("Modified Response : Getting output stream."); if ( fWriterReturned ) { throw new IllegalStateException(); } fOutputStreamReturned = true; return fOutputStream; } /** Standard servlet method. */ public final PrintWriter getWriter() { //fLogger.fine("Modified Response : Getting writer."); if ( fOutputStreamReturned ) { throw new IllegalStateException(); } fWriterReturned = true; return fWriter; } // PRIVATE /* Well-behaved servlets return either an OutputStream or a PrintWriter, but not both. */ private PrintWriter fWriter; private ModifiedOutputStream fOutputStream; /* These items are used to implement conformance to the javadoc for ServletResponse, regarding exceptions being thrown. */ private boolean fWriterReturned; private boolean fOutputStreamReturned; /** Modified low level output stream. */ private class ModifiedOutputStream extends ServletOutputStream { public ModifiedOutputStream(ServletOutputStream aOutputStream) { fServletOutputStream = aOutputStream; fBuffer = new ByteArrayOutputStream(); } /** Must be implemented to make this class concrete. */ public void write(int aByte) { fBuffer.write(aByte); } public void close() throws IOException { if ( !fIsClosed ){ processStream(); fServletOutputStream.close(); fIsClosed = true; } } public void flush() throws IOException { if ( fBuffer.size() != 0 ){ if ( !fIsClosed ) { processStream(); fBuffer = new ByteArrayOutputStream(); } } } /** Perform the core processing, by calling the abstract method. */ public void processStream() throws IOException { fServletOutputStream.write(modifyResponse(fBuffer.toByteArray())); fServletOutputStream.flush(); } // PRIVATE // private ServletOutputStream fServletOutputStream; private ByteArrayOutputStream fBuffer; /** Tracks if this stream has been closed. */ private boolean fIsClosed = false; } }

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• Issuing Current Time Increments in StreamInsight (A Practical Example)

  The issuing of a Current Time Increment, Cti, in StreamInsight is very definitely one of the most important concepts to learn if you want your Streams to be responsive. A full discussion of how to issue Ctis is beyond the scope of this article but a very good explanation in addition to Books Online can be found in these three articles by a member of the StreamInsight team at Microsoft, Ciprian Gerea. Time in StreamInsight Series http://blogs.msdn.com/b/streaminsight/archive/2010/07/23/time-in-streaminsight-i.aspx http://blogs.msdn.com/b/streaminsight/archive/2010/07/30/time-in-streaminsight-ii.aspx http://blogs.msdn.com/b/streaminsight/archive/2010/08/03/time-in-streaminsight-iii.aspx A lot of the problems I see with unresponsive or stuck streams on the MSDN Forums are to do with how Ctis are enqueued or in a lot of cases not enqueued. If you enqueue events and never enqueue a Cti then StreamInsight will be perfectly happy. You, on the other hand, will never see data on the output as you have not told StreamInsight to flush the stream. This article deals with a specific implementation problem I had recently whilst working on a StreamInsight project. I look at some possible options and discuss why they would not work before showing the way I solved the problem. The stream of data I was dealing with on this project was very bursty that is to say when events were flowing they came through very quickly and in large numbers (1000 events/sec), but when the stream calmed down it could be a few seconds between each event. When enqueuing events into the StreamInsight engne it is best practice to do so with a StartTime that is given to you by the system producing the event . StreamInsight processes events and it doesn't matter whether those events are being pushed into the engine by a source system or the events are being read from something like a flat file in a directory somewhere. You can apply the same logic and temporal algebra to both situations. Reading from a file is an excellent example of where the time of the event on the source itself is very important. We could be reading that file a long time after it was written. Being able to read the StartTime from the events allows us to define windows that will hold the correct sets of events. I was able to do this with my stream but this is where my problems started. Below is a very simple script to create a SQL Server table and populate it with sample data that will show exactly the problem I had. CREATE TABLE [dbo].[t] ( [c1] [int] PRIMARY KEY, [c2] [datetime] NULL ) INSERT t VALUES (1,'20100810'),(2,'20100810'),(3,'20100810') Column c2 defines the StartTime of the event on the source and as you can see the values in all 3 rows of data is the same. If we read Ciprian’s articles we know that we can define how Ctis get injected into the stream in 3 different places The Stream Definition The Input Factory The Input Adapter I personally have always been a fan of enqueing Ctis through the factory. Below is code typical of what I would use to do this On the class itself I do some inheriting public class SimpleInputFactory : ITypedInputAdapterFactory<SimpleInputConfig>, ITypedDeclareAdvanceTimeProperties<SimpleInputConfig> And then I implement the following function public AdapterAdvanceTimeSettings DeclareAdvanceTimeProperties<TPayload>(SimpleInputConfig configInfo, EventShape eventShape) { return new AdapterAdvanceTimeSettings( new AdvanceTimeGenerationSettings(configInfo.CtiFrequency, TimeSpan.FromTicks(-1)), AdvanceTimePolicy.Adjust); } The configInfo .CtiFrequency property is a value I pass through to define after how many events I want a Cti to be injected and this in turn will flush through the stream of data. I usually pass a value of 1 for this setting. The second parameter determines the CTI timestamp in terms of a delay relative to the events. -1 ticks in the past results in 1 tick in the future, i.e., ahead of the event. The problem with this method though is that if consecutive events have the same StartTime then only one of those events will be enqueued. In this example I use the following to define how I assign the StartTime of my events currEvent.StartTime = (DateTimeOffset)dt.c2; If I go ahead and run my StreamInsight process with this configuration i can see on the output adapter that two events have been removed To see this in a little more depth I can use the StreamInsight Debugger and see what happens internally. What is happening here is that the first event arrives and a Cti is injected with a time of 1 tick after the StartTime of that event (Also the EndTime of the event). The second event arrives and it has a StartTime of before the Cti and even though we specified AdvanceTimePolicy.Adjust on the factory we know that a point event can never be adjusted like this and the event is dropped. The same happens for the third event as well (The second and third events get trumped by the Cti). For a more detailed discussion of why this happens look here http://www.sqlis.com/sqlis/post/AdvanceTimePolicy-and-Point-Event-Streams-In-StreamInsight.aspx We end up with a single event being pushed into the output adapter and our result now makes sense. The next way I tried to solve this problem by changing the value of the second parameter to TimeSpan.Zero Here is how my factory code now looks public AdapterAdvanceTimeSettings DeclareAdvanceTimeProperties<TPayload>(SimpleInputConfig configInfo, EventShape eventShape) { return new AdapterAdvanceTimeSettings( new AdvanceTimeGenerationSettings(configInfo.CtiFrequency, TimeSpan.Zero), AdvanceTimePolicy.Adjust); } What I am doing here is declaring a policy that says inject a Cti together with every event and stamp it with a StartTime that is equal to the start time of the event itself (TimeSpan.Zero). This method has plus points as well as a downside. The upside is that no events will be lost by having the same StartTime as previous events. The Downside is that because the Cti is declared with the StartTime of the event itself then it does not actually flush that particular event because in the StreamInsight algebra, a Cti commits only those events that occurred strictly before them. To flush the events we need a Cti to be enqueued with a greater StartTime than the events themselves. Here is what happened when I ran this configuration As you can see all we got through was the Cti and none of the events. The debugger output shows the stamps on the Cti and the events themselves. Because the Cti issued has the same timestamp (StartTime) as the events then none of the events get flushed. I was nearly there but not quite. Because my stream was bursty it was possible that the next event would not come along for a few seconds and this was far too long for an event to be enqueued and not be flushed to the output adapter. I needed another solution. Two possible solutions crossed my mind although only one of them made sense when I explored it some more. Where multiple events have the same StartTime I could add 1 tick to the first event, two to the second, three to third etc thereby giving them unique StartTime values. Add a timer to manually inject Ctis The problem with the first implementation is that I would be giving the events a new StartTime. This would cause me the following problems If I want to define windows over the stream then some events may not be captured in the right windows and therefore any calculations on those windows I did would be wrong What would happen if we had 10,000 events with the same StartTime? I would enqueue them with StartTime + n ticks. Along comes a genuine event with a StartTime of the very first event + 1 tick. It is now too far in the past as far as my stream is concerned and it would be dropped. Not what I would want to do at all. I decided then to look at the Timer based solution I created a timer on my input adapter that elapsed every 200ms. private Timer tmr; public SimpleInputAdapter(SimpleInputConfig configInfo) { ctx = new SimpleTimeExtractDataContext(configInfo.ConnectionString); this.configInfo = configInfo; tmr = new Timer(200); tmr.Elapsed += new ElapsedEventHandler(t_Elapsed); tmr.Enabled = true; } void t_Elapsed(object sender, ElapsedEventArgs e) { ts = DateTime.Now - dtCtiIssued; if (ts.TotalMilliseconds >= 200 && TimerIssuedCti == false) { EnqueueCtiEvent(System.DateTime.Now.AddTicks(-100)); TimerIssuedCti = true; } }   In the t_Elapsed event handler I find out the difference in time between now and when the last event was processed (dtCtiIssued). I then check to see if that is greater than or equal to 200ms and if the last issuing of a Cti was done by the timer or by a genuine event (TimerIssuedCti). If I didn’t do this check then I would enqueue a Cti every time the timer elapsed which is not something I wanted. If the difference between the two times is greater than or equal to 500ms and the last event enqueued was by a real event then I issue a Cti through the timer to flush the event Queue, otherwise I do nothing. When I enqueue the Ctis into my stream in my ProduceEvents method I also set the values of dtCtiIssued and TimerIssuedCti   currEvent = CreateInsertEvent(); currEvent.StartTime = (DateTimeOffset)dt.c2; TimerIssuedCti = false; dtCtiIssued = currEvent.StartTime; If I go ahead and run this configuration I see the following in my output. As we can see the first Cti gets enqueued as before but then another is enqueued by the timer and because this has a later timestamp it flushes the enqueued events through the engine. Conclusion Hopefully this has shown how the enqueuing of Ctis can have a dramatic effect on the responsiveness of your output in StreamInsight. Understanding the temporal nature of the product is for me one of the most important things you can learn. I have attached my solution for the demos. It is all in one project and testing each variation is a simple matter of commenting and un-commenting the parts in the code we have been dealing with here.

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• Attend my Fusion sessions

  - by Daniel Moth

  The inaugural Fusion conference was 1 year ago in June 2011 and I was there doing a demo in the keynote, and also presenting a breakout session. If you look at the abstract and title for that session you won't see the term "C++ AMP" in there because the technology wasn't announced and we didn't want to spill the beans ahead of the keynote, where the technology was announced. It was only an announcement, we did not give any bits out, and in fact the first bits came three months later in September 2011 with the Beta following in February 2012. So it really feels great 1 year later, to be back at Fusion presenting two sessions on C++ AMP, demonstrating our progress from that announcement, to the Visual Studio 2012 Release Candidate that came out last week. If you are attending Fusion (in person or virtually later), be sure to watch my two-part session. Part 1 is PT-3601 on Tuesday 4pm and part 2 is PT-3602 on Wednesday 4pm. Here is the shared abstract for both parts: Harnessing GPU Compute with C++ AMP C++ AMP is an open specification for taking advantage of accelerators like the GPU. In this session we will explore the C++ AMP implementation in Microsoft Visual Studio 2012. After a quick overview of the technology understanding its goals and its differentiation compared with other approaches, we will dive into the programming model and its modern C++ API. This is a code heavy, interactive, two-part session, where every part of the library will be explained. Demos will include showing off the richest parallel and GPU debugging story on the market, in the upcoming Visual Studio release. See you there! Comments about this post by Daniel Moth welcome at the original blog.

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