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• simple and reliable centralized logging inside Amazon VPC

  - by Nakedible

  I need to set up centralized logging for a set of servers (10-20) in an Amazon VPC. The logging should be as to not lose any log messages in case any single server goes offline - or in the case that an entire availability zone goes offline. It should also tolerate packet loss and other normal network conditions without losing or duplicating messages. It should store the messages durably, at the minimum on two different EBS volumes in two availability zones, but S3 is a good place as well. It should also be realtime so that the messages arrive within seconds of their generation to two different availability zones. I also need to sync logfiles not generated via syslog, so a syslog-only centralized logging solution would not fulfill all the needs, although I guess that limitation could be worked around. I have already reviewed a few solutions, and I will list them here: Flume to Flume to S3: I could set up two logservers as Flume hosts which would store log messages either locally or in S3, and configure all the servers with Flume to send all messages to both servers, using the end-to-end reliability options. That way the loss of a single server shouldn't cause lost messages and all messages would arrive in two availability zones in realtime. However, there would need to be some way to join the logs of the two servers, deduplicating all the messages delivered to both. This could be done by adding a unique id on the sending side to each message and then write some manual deduplication runs on the logfiles. I haven't found an easy solution to the duplication problem. Logstash to Logstash to ElasticSearch: I could install Logstash on the servers and have them deliver to a central server via AMQP, with the durability options turned on. However, for this to work I would need to use some of the clustering capable AMQP implementations, or fan out the deliver just as in the Flume case. AMQP seems to be a yet another moving part with several implementations and no real guidance on what works best this sort of setup. And I'm not entirely convinced that I could get actual end-to-end durability from logstash to elasticsearch, assuming crashing servers in between. The fan-out solutions run in to the deduplication problem again. The best solution that would seem to handle all the cases, would be Beetle, which seems to provide high availability and deduplication via a redis store. However, I haven't seen any guidance on how to set this up with Logstash and Redis is one more moving part again for something that shouldn't be terribly difficult. Logstash to ElasticSearch: I could run Logstash on all the servers, have all the filtering and processing rules in the servers themselves and just have them log directly to a removet ElasticSearch server. I think this should bring me reliable logging and I can use the ElasticSearch clustering features to share the database transparently. However, I am not sure if the setup actually survives Logstash restarts and intermittent network problems without duplicating messages in a failover case or similar. But this approach sounds pretty promising. rsync: I could just rsync all the relevant log files to two different servers. The reliability aspect should be perfect here, as the files should be identical to the source files after a sync is done. However, doing an rsync several times per second doesn't sound fun. Also, I need the logs to be untamperable after they have been sent, so the rsyncs would need to be in append-only mode. And log rotations mess things up unless I'm careful. rsyslog with RELP: I could set up rsyslog to send messages to two remote hosts via RELP and have a local queue to store the messages. There is the deduplication problem again, and RELP itself might also duplicate some messages. However, this would only handle the things that log via syslog. None of these solutions seem terribly good, and they have many unknowns still, so I am asking for more information here from people who have set up centralized reliable logging as to what are the best tools to achieve that goal.

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• 2 way SSL between SOA and OSB

  - by Johnny Shum

  If you have a need to use 2 way SSL between SOA composite and external partner links, you can follow these steps. Create the identity keystores, trust keystores, and server certificates. Setup keystores and SSL on WebLogic Setup server to use 2 way SSL Configure your SOA composite's partner link to use 2 way SSL Configure SOA engine two ways SSL In this case,  I use SOA and OSB for the test.  I started with a separate OSB and SOA domains.  I deployed two soap based proxies on OSB and two composites on SOA.  In SOA, one composite invokes a OSB proxy service, the other is invoked by the OSB.  Similarly,  in OSB,  one proxy invokes a SOA composite and the other is invoked by SOA. 1. Create the identity keystores, trust keystores and the server certificates Since this is a development environment, I use JDK's keytool to create the stores and use self signing certificate.  For production environment, you should use certificates from a trusted certificate authority like Verisign.    I created a script below to show what is needed in this step.  The only requirement is when creating the SOA identity certificate, you MUST use the alias mykey. STOREPASS=welcome1KEYPASS=welcome1# generate identity keystore for soa and osb.  Note: For SOA, you MUST use alias mykeyecho "creating stores"keytool -genkey -alias mykey -keyalg "RSA" -sigalg "SHA1withRSA" -dname "CN=soa, C=US" -keystore soa-default-keystore.jks -storepass $STOREPASS -keypass $KEYPASS keytool -genkey -alias osbkey -keyalg "RSA" -sigalg "SHA1withRSA" -dname "CN=osb, C=US" -keystore osb-default-keystore.jks -storepass $STOREPASS -keypass $KEYPASS# listing keystore contentsecho "listing stores contents"keytool -list -alias mykey -keystore soa-default-keystore.jks -storepass $STOREPASSkeytool -list -alias osbkey -keystore osb-default-keystore.jks -storepass $STOREPASS# exporting certs from storesecho "export certs from  stores"keytool -exportcert -alias mykey -keystore soa-default-keystore.jks -storepass $STOREPASS -file soacert.derkeytool -exportcert -alias osbkey -keystore osb-default-keystore.jks -storepass $STOREPASS -file osbcert.der # import certs to trust storesecho "import certs"keytool -importcert -alias osbkey -keystore soa-trust-keystore.jks -storepass $STOREPASS -file osbcert.der -keypass $KEYPASSkeytool -importcert -alias mykey -keystore osb-trust-keystore.jks -storepass $STOREPASS -file soacert.der  -keypass $KEYPASS SOA suite uses the JDK's SSL implementation for outbound traffic instead of the WebLogic's implementation.  You will need to import the partner's public cert into the trusted keystore used by SOA.  The default trusted keystore for SOA is DemoTrust.jks and it is located in $MW_HOME/wlserver_10.3/server/lib.   (This is set in the startup script -Djavax.net.ssl.trustStore).   If you use your own trusted keystore, then you will need to import it into your own trusted keystore. keytool -importcert -alias osbkey -keystore $MW_HOME/wlserver_10.3/server/lib/DemoTrust.jks -storepass DemoTrustKeyStorePassPhrase  -file osbcert.der -keypass $KEYPASS If you do not perform this step, you will encounter this exception in runtime when SOA invokes OSB service using 2 way SSL Message send failed: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target  2.  Setup keystores and SSL on WebLogic First, you will need to login to the WebLogic console, navigate to the server's configuration->Keystore's tab.   Change the Keystores type to Custom Identity and Custom Trust and enter the rest of the fields. Then you navigate to the SSL tab, enter the fields in the identity section and expand the Advanced section.  Since I am using self signing cert on my VM enviornment, I disabled Hostname verification.  In real production system, this should not be the case.   I also enabled the option "Use Server Certs", so that the application uses the server cert to initiate https traffic (it is important to enable this in OSB). Last, you enable SSL listening port in the Server's configuration->General tab. 3.  Setup server to use 2 way SSL If you follow the screen shot in previous step, you can see in the Server->Configuration->SSL->Advanced section, there is an option for Two Way Client Cert Behavior,  you should set this to Client Certs Requested and Enforced. Repeat step 2 and 3 done on OSB.  After all these configurations,  you have to restart all the servers. 4.  Configure your SOA composite's partner link to use 2 way SSL You do this by modifying the composite.xml in your project, locate the partner's link reference and add the property oracle.soa.two.way.ssl.enabled.   <reference name="callosb" ui:wsdlLocation="helloword.wsdl">    <interface.wsdl interface="http://www.examples.com/wsdl/HelloService.wsdl#wsdl.interface(Hello_PortType)"/>    <binding.ws port="http://www.examples.com/wsdl/HelloService.wsdl#wsdl.endpoint(Hello_Service/Hello_Port)"                location="helloword.wsdl" soapVersion="1.1">      <property name="weblogic.wsee.wsat.transaction.flowOption"                type="xs:string" many="false">WSDLDriven</property>   <property name="oracle.soa.two.way.ssl.enabled">true</property>    </binding.ws>  </reference> In OSB, you should have checked the HTTPS required flag in the proxy's transport configuration.  After this,  rebuilt the composite jar file and ready to deploy in the EM console later. 5.  Configure SOA engine two ways SSL Oracle SOA Suite uses both Oracle WebLogic Server and Sun Secure Socket Layer (SSL) stacks for two-way SSL configurations. For the inbound web service bindings, Oracle SOA Suite uses the Oracle WebLogic Server infrastructure and, therefore, the Oracle WebLogic Server libraries for SSL.  This is already done by step 2 and 3 in the previous section. For the outbound web service bindings, Oracle SOA Suite uses JRF HttpClient and, therefore, the Sun JDK libraries for SSL.  You do this by configuring the SOA Engine in the Enterprise Manager Console, select soa-infra->SOA Administration->Common Properties Then click at the link at the bottom of the page:  "More SOA Infra Advances Infrastructure Configuration Properties" and then enter the full path of soa identity keystore in the value field of the KeyStoreLocation attribute.  Click Apply and Return then navigate to the domain->security->credential. Here, you provide the password to the keystore.  Note: the alias of the certficate must be mykey as described in step 1, so you only need to provide the password to the identity keystore.   You accomplish this by: Click Create Map In the Map Name field, enter SOA, and click OK Click Create Key Enter the following details where the password is the password for the SOA identity keystore. 6.  Test and Trouble Shooting Once the setup is complete and server restarted, you can deploy the composite in the EM console and test it.  In case of error,  you can read the server log file to determine the cause of the error.  For example, If you have not setup step 5 and test 2 way SSL, you will see this in the log when invoking OSB from BPEL: java.lang.Exception: oracle.sysman.emSDK.webservices.wsdlapi.SoapTestException: oracle.fabric.common.FabricInvocationException: Unable to access the following endpoint(s): https://localhost.localdomain:7002/default/helloword ####<Sep 22, 2012 2:07:37 PM CDT> <Error> <oracle.soa.bpel.engine.ws> <rhel55> <AdminServer> <[ACTIVE] ExecuteThread: '1' for queue: 'weblogic.kernel.Default (self-tuning)'> <<anonymous>> <BEA1-0AFDAEF20610F8FD89C5> ............ <11d1def534ea1be0:-4034173:139ef56d9f0:-8000-00000000000002ec> <1348340857956> <BEA-000000> <got FabricInvocationException sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target If you have not enable WebLogic SSL to use server certificate in the console and invoke SOA composite from OSB using two ways SSL, you will see this error: ####<Sep 22, 2012 2:07:37 PM CDT> <Warning> <Security> <rhel55> <AdminServer> <[ACTIVE] ExecuteThread: '6' for queue: 'weblogic.kernel.Default (self-tuning)'> <<WLS Kernel>> <> <11d1def534ea1be0:-51f5c76a:139ef5e1e1a:-8000-00000000000000e2> <1348340857776> <BEA-090485> <CERTIFICATE_UNKNOWN alert was received from localhost.localdomain - 127.0.0.1. The peer has an unspecified issue with the certificate. SSL debug tracing should be enabled on the peer to determine what the issue is.> ####<Sep 22, 2012 2:07:37 PM CDT> <Warning> <Security> <rhel55> <AdminServer> <[ACTIVE] ExecuteThread: '6' for queue: 'weblogic.kernel.Default (self-tuning)'> <<WLS Kernel>> <> <11d1def534ea1be0:-51f5c76a:139ef5e1e1a:-8000-00000000000000e4> <1348340857786> <BEA-090485> <CERTIFICATE_UNKNOWN alert was received from localhost.localdomain - 127.0.0.1. The peer has an unspecified issue with the certificate. SSL debug tracing should be enabled on the peer to determine what the issue is.> ####<Sep 22, 2012 2:27:21 PM CDT> <Warning> <Security> <rhel55> <AdminServer> <[ACTIVE] ExecuteThread: '0' for queue: 'weblogic.kernel.Default (self-tuning)'> <<anonymous>> <> <11d1def534ea1be0:-51f5c76a:139ef5e1e1a:-8000-0000000000000124> <1348342041926> <BEA-090497> <HANDSHAKE_FAILURE alert received from localhost - 127.0.0.1. Check both sides of the SSL configuration for mismatches in supported ciphers, supported protocol versions, trusted CAs, and hostname verification settings.> References http://docs.oracle.com/cd/E23943_01/admin.1111/e10226/soacompapp_secure.htm#CHDCFABB   Section 5.6.4 http://docs.oracle.com/cd/E23943_01/web.1111/e13707/ssl.htm#i1200848

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• Investigation: Can different combinations of components effect Dataflow performance?

  - by jamiet

  Introduction The Dataflow task is one of the core components (if not the core component) of SQL Server Integration Services (SSIS) and often the most misunderstood. This is not surprising, its an incredibly complicated beast and we’re abstracted away from that complexity via some boxes that go yellow red or green and that have some lines drawn between them. Example dataflow In this blog post I intend to look under that facade and get into some of the nuts and bolts of the Dataflow Task by investigating how the decisions we make when building our packages can affect performance. I will do this by comparing the performance of three dataflows that all have the same input, all produce the same output, but which all operate slightly differently by way of having different transformation components. I also want to use this blog post to challenge a common held opinion that I see perpetuated over and over again on the SSIS forum. That is, that people assume adding components to a dataflow will be detrimental to overall performance. Its not surprising that people think this –it is intuitive to think that more components means more work- however this is not a view that I share. I have always been of the opinion that there are many factors affecting dataflow duration and the number of components is actually one of the less important ones; having said that I have never proven that assertion and that is one reason for this investigation. I have actually seen evidence that some people think dataflow duration is simply a function of number of rows and number of components. I’ll happily call that one out as a myth even without any investigation!  The Setup I have a 2GB datafile which is a list of 4731904 (~4.7million) customer records with various attributes against them and it contains 2 columns that I am going to use for categorisation: [YearlyIncome] [BirthDate] The data file is a SSIS raw format file which I chose to use because it is the quickest way of getting data into a dataflow and given that I am testing the transformations, not the source or destination adapters, I want to minimise external influences as much as possible. In the test I will split the customers according to month of birth (12 of those) and whether or not their yearly income is above or below 50000 (2 of those); in other words I will be splitting them into 24 discrete categories and in order to do it I shall be using different combinations of SSIS’ Conditional Split and Derived Column transformation components. The 24 datapaths that occur will each input to a rowcount component, again because this is the least resource intensive means of terminating a datapath. The test is being carried out on a Dell XPS Studio laptop with a quad core (8 logical Procs) Intel Core i7 at 1.73GHz and Samsung SSD hard drive. Its running SQL Server 2008 R2 on Windows 7. The Variables Here are the three combinations of components that I am going to test:     One Conditional Split - A single Conditional Split component CSPL Split by Month of Birth and income category that will use expressions on [YearlyIncome] & [BirthDate] to send each row to one of 24 outputs. This next screenshot displays the expression logic in use: Derived Column & Conditional Split - A Derived Column component DER Income Category that adds a new column [IncomeCategory] which will contain one of two possible text values {“LessThan50000”,”GreaterThan50000”} and uses [YearlyIncome] to determine which value each row should get. A Conditional Split component CSPL Split by Month of Birth and Income Category then uses that new column in conjunction with [BirthDate] to determine which of the same 24 outputs to send each row to. Put more simply, I am separating the Conditional Split of #1 into a Derived Column and a Conditional Split. The next screenshots display the expression logic in use: DER Income Category         CSPL Split by Month of Birth and Income Category       Three Conditional Splits - A Conditional Split component that produces two outputs based on [YearlyIncome], one for each Income Category. Each of those outputs will go to a further Conditional Split that splits the input into 12 outputs, one for each month of birth (identical logic in each). In this case then I am separating the single Conditional Split of #1 into three Conditional Split components. The next screenshots display the expression logic in use: CSPL Split by Income Category         CSPL Split by Month of Birth 1& 2       Each of these combinations will provide an input to one of the 24 rowcount components, just the same as before. For illustration here is a screenshot of the dataflow containing three Conditional Split components: As you can these dataflows have a fair bit of work to do and remember that they’re doing that work for 4.7million rows. I will execute each dataflow 10 times and use the average for comparison. I foresee three possible outcomes: The dataflow containing just one Conditional Split (i.e. #1) will be quicker There is no significant difference between any of them One of the two dataflows containing multiple transformation components will be quicker Regardless of which of those outcomes come to pass we will have learnt something and that makes this an interesting test to carry out. Note that I will be executing the dataflows using dtexec.exe rather than hitting F5 within BIDS. The Results and Analysis The table below shows all of the executions, 10 for each dataflow. It also shows the average for each along with a standard deviation. All durations are in seconds. I’m pasting a screenshot because I frankly can’t be bothered with the faffing about needed to make a presentable HTML table. It is plain to see from the average that the dataflow containing three conditional splits is significantly faster, the other two taking 43% and 52% longer respectively. This seems strange though, right? Why does the dataflow containing the most components outperform the other two by such a big margin? The answer is actually quite logical when you put some thought into it and I’ll explain that below. Before progressing, a side note. The standard deviation for the “Three Conditional Splits” dataflow is orders of magnitude smaller – indicating that performance for this dataflow can be predicted with much greater confidence too. The Explanation I refer you to the screenshot above that shows how CSPL Split by Month of Birth and salary category in the first dataflow is setup. Observe that there is a case for each combination of Month Of Date and Income Category – 24 in total. These expressions get evaluated in the order that they appear and hence if we assume that Month of Date and Income Category are uniformly distributed in the dataset we can deduce that the expected number of expression evaluations for each row is 12.5 i.e. 1 (the minimum) + 24 (the maximum) divided by 2 = 12.5. Now take a look at the screenshots for the second dataflow. We are doing one expression evaluation in DER Income Category and we have the same 24 cases in CSPL Split by Month of Birth and Income Category as we had before, only the expression differs slightly. In this case then we have 1 + 12.5 = 13.5 expected evaluations for each row – that would account for the slightly longer average execution time for this dataflow. Now onto the third dataflow, the quick one. CSPL Split by Income Category does a maximum of 2 expression evaluations thus the expected number of evaluations per row is 1.5. CSPL Split by Month of Birth 1 & CSPL Split by Month of Birth 2 both have less work to do than the previous Conditional Split components because they only have 12 cases to test for thus the expected number of expression evaluations is 6.5 There are two of them so total expected number of expression evaluations for this dataflow is 6.5 + 6.5 + 1.5 = 14.5. 14.5 is still more than 12.5 & 13.5 though so why is the third dataflow so much quicker? Simple, the conditional expressions in the first two dataflows have two boolean predicates to evaluate – one for Income Category and one for Month of Birth; the expressions in the Conditional Split in the third dataflow however only have one predicate thus they are doing a lot less work. To sum up, the difference in execution times can be attributed to the difference between: MONTH(BirthDate) == 1 && YearlyIncome <= 50000 and MONTH(BirthDate) == 1 In the first two dataflows YearlyIncome <= 50000 gets evaluated an average of 12.5 times for every row whereas in the third dataflow it is evaluated once and once only. Multiply those 11.5 extra operations by 4.7million rows and you get a significant amount of extra CPU cycles – that’s where our duration difference comes from. The Wrap-up The obvious point here is that adding new components to a dataflow isn’t necessarily going to make it go any slower, moreover you may be able to achieve significant improvements by splitting logic over multiple components rather than one. Performance tuning is all about reducing the amount of work that needs to be done and that doesn’t necessarily mean use less components, indeed sometimes you may be able to reduce workload in ways that aren’t immediately obvious as I think I have proven here. Of course there are many variables in play here and your mileage will most definitely vary. I encourage you to download the package and see if you get similar results – let me know in the comments. The package contains all three dataflows plus a fourth dataflow that will create the 2GB raw file for you (you will also need the [AdventureWorksDW2008] sample database from which to source the data); simply disable all dataflows except the one you want to test before executing the package and remember, execute using dtexec, not within BIDS. If you want to explore dataflow performance tuning in more detail then here are some links you might want to check out: Inequality joins, Asynchronous transformations and Lookups Destination Adapter Comparison Don’t turn the dataflow into a cursor SSIS Dataflow – Designing for performance (webinar) Any comments? Let me know! @Jamiet

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• Android page Curl animation

  - by Meymann

  Hi... Two questions: Is there a simple way to do the Curl page flipping animation? A Curl animation is animation of pages flipping, including the page above rolling and the shadows over the lower page. What is the recommended way to do a "gallery" that displays two pages at a time (just like a book)? Is it: Letting the adapter display a linear layout of two images at a time? (it won't let me show a page flipping over the other like a book) Using two pages, placing somehow one near the other, and then when it's time to animate -move the next two pages over? What is the better way that would enable displaying the left page flipping over the right page? Thanks Meymann

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• SQL SERVER – Simple Example to Configure Resource Governor – Introduction to Resource Governor

  - by pinaldave

  Let us jump right away with question and answer mode. What is resource governor? Resource Governor is a feature which can manage SQL Server Workload and System Resource Consumption. We can limit the amount of CPU and memory consumption by limiting /governing /throttling on the SQL Server. Why is resource governor required? If there are different workloads running on SQL Server and each of the workload needs different resources or when workloads are competing for resources with each other and affecting the performance of the whole server resource governor is a very important task. What will be the real world example of need of resource governor? Here are two simple scenarios where the resource governor can be very useful. Scenario 1: A server which is running OLTP workload and various resource intensive reports on the same server. The ideal situation is where there are two servers which are data synced with each other and one server runs OLTP transactions and the second server runs all the resource intensive reports. However, not everybody has the luxury to set up this kind of environment. In case of the situation where reports and OLTP transactions are running on the same server, limiting the resources to the reporting workload it can be ensured that OTLP’s critical transaction is not throttled. Scenario 2: There are two DBAs in one organization. One DBA A runs critical queries for business and another DBA B is doing maintenance of the database. At any point in time the DBA A’s work should not be affected but at the same time DBA B should be allowed to work as well. The ideal situation is that when DBA B starts working he get some resources but he can’t get more than defined resources. Does SQL Server have any default resource governor component? Yes, SQL Server have two by default created resource governor component. 1) Internal –This is used by database engine exclusives and user have no control. 2) Default – This is used by all the workloads which are not assigned to any other group. What are the major components of the resource governor? Resource Pools Workload Groups Classification In simple words here is what the process of resource governor is. Create resource pool Create a workload group Create classification function based on the criteria specified Enable Resource Governor with classification function Let me further explain you the same with graphical image. Is it possible to configure resource governor with T-SQL? Yes, here is the code for it with explanation in between. Step 0: Here we are assuming that there are separate login accounts for Reporting server and OLTP server. /*----------------------------------------------- Step 0: (Optional and for Demo Purpose) Create Two User Logins 1) ReportUser, 2) PrimaryUser Use ReportUser login for Reports workload Use PrimaryUser login for OLTP workload -----------------------------------------------*/ Step 1: Creating Resource Pool We are creating two resource pools. 1) Report Server and 2) Primary OLTP Server. We are giving only a few resources to the Report Server Pool as described in the scenario 1 the other server is mission critical and not the report server. ----------------------------------------------- -- Step 1: Create Resource Pool ----------------------------------------------- -- Creating Resource Pool for Report Server CREATE RESOURCE POOL ReportServerPool WITH ( MIN_CPU_PERCENT=0, MAX_CPU_PERCENT=30, MIN_MEMORY_PERCENT=0, MAX_MEMORY_PERCENT=30) GO -- Creating Resource Pool for OLTP Primary Server CREATE RESOURCE POOL PrimaryServerPool WITH ( MIN_CPU_PERCENT=50, MAX_CPU_PERCENT=100, MIN_MEMORY_PERCENT=50, MAX_MEMORY_PERCENT=100) GO Step 2: Creating Workload Group We are creating two workloads each mapping to each of the resource pool which we have just created. ----------------------------------------------- -- Step 2: Create Workload Group ----------------------------------------------- -- Creating Workload Group for Report Server CREATE WORKLOAD GROUP ReportServerGroup USING ReportServerPool ; GO -- Creating Workload Group for OLTP Primary Server CREATE WORKLOAD GROUP PrimaryServerGroup USING PrimaryServerPool ; GO Step 3: Creating user defiled function which routes the workload to the appropriate workload group. In this example we are checking SUSER_NAME() and making the decision of Workgroup selection. We can use other functions such as HOST_NAME(), APP_NAME(), IS_MEMBER() etc. ----------------------------------------------- -- Step 3: Create UDF to Route Workload Group ----------------------------------------------- CREATE FUNCTION dbo.UDFClassifier() RETURNS SYSNAME WITH SCHEMABINDING AS BEGIN DECLARE @WorkloadGroup AS SYSNAME IF(SUSER_NAME() = 'ReportUser') SET @WorkloadGroup = 'ReportServerGroup' ELSE IF (SUSER_NAME() = 'PrimaryServerPool') SET @WorkloadGroup = 'PrimaryServerGroup' ELSE SET @WorkloadGroup = 'default' RETURN @WorkloadGroup END GO Step 4: In this final step we enable the resource governor with the classifier function created in earlier step 3. ----------------------------------------------- -- Step 4: Enable Resource Governer -- with UDFClassifier ----------------------------------------------- ALTER RESOURCE GOVERNOR WITH (CLASSIFIER_FUNCTION=dbo.UDFClassifier); GO ALTER RESOURCE GOVERNOR RECONFIGURE GO Step 5: If you are following this demo and want to clean up your example, you should run following script. Running them will disable your resource governor as well delete all the objects created so far. ----------------------------------------------- -- Step 5: Clean Up -- Run only if you want to clean up everything ----------------------------------------------- ALTER RESOURCE GOVERNOR WITH (CLASSIFIER_FUNCTION = NULL) GO ALTER RESOURCE GOVERNOR DISABLE GO DROP FUNCTION dbo.UDFClassifier GO DROP WORKLOAD GROUP ReportServerGroup GO DROP WORKLOAD GROUP PrimaryServerGroup GO DROP RESOURCE POOL ReportServerPool GO DROP RESOURCE POOL PrimaryServerPool GO ALTER RESOURCE GOVERNOR RECONFIGURE GO I hope this introductory example give enough light on the subject of Resource Governor. In future posts we will take this same example and learn a few more details. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology Tagged: Resource Governor

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• Replication - between pools in the same system

  - by Steve Tunstall

  OK, I fully understand that's it's been a LONG time since I've blogged with any tips or tricks on the ZFSSA, and I'm way behind. Hey, I just wrote TWO BLOGS ON THE SAME DAY!!! Make sure you keep scrolling down to see the next one too, or you may have missed it. To celebrate, for the one or two of you out there who are still reading this, I got something for you. The first TWO people who make any comment below, with your real name and email so I can contact you, will get some cool Oracle SWAG that I have to give away. Don't get excited, it's not an iPad, but it pretty good stuff. Only the first two, so if you already see two below, then settle down. Now, let's talk about Replication and Migration.  I have talked before about Shadow Migration here: https://blogs.oracle.com/7000tips/entry/shadow_migrationShadow Migration lets one take a NFS or CIFS share in one pool on a system and migrate that data over to another pool in the same system. That's handy, but right now it's only for file systems like NFS and CIFS. It will not work for LUNs. LUN shadow migration is a roadmap item, however. So.... What if you have a ZFSSA cluster with multiple pools, and you have a LUN in one pool but later you decide it's best if it was in the other pool? No problem. Replication to the rescue. What's that? Replication is only for replicating data between two different systems? Who told you that? We've been able to replicate to the same system now for a few code updates back. These instructions below will also work just fine if you're setting up replication between two different systems. After replication is complete, you can easily break replication, change the new LUN into a primary LUN and then delete the source LUN. Bam. Step 1- setup a target system. In our case, the target system is ourself, but you still have to set it up like it's far away. Go to Configuration-->Services-->Remote Replication. Click the plus sign and setup the target, which is the ZFSSA you're on now. Step 2. Now you can go to the LUN you want to replicate. Take note which Pool and Project you're in. In my case, I have a LUN in Pool2 called LUNp2 that I wish to replicate to Pool1.  Step 3. In my case, I made a Project called "Luns" and it has LUNp2 inside of it. I am going to replicate the Project, which will automatically replicate all of the LUNs and/or Filesystems inside of it.  Now, you can also replicate from the Share level instead of the Project. That will only replicate the share, and not all the other shares of a project. If someone tells you that if you replicate a share, it always replicates all the other shares also in that Project, don't listen to them.Note below how I can choose not only the Target (which is myself), but I can also choose which Pool to replicate it to. So I choose Pool1.  Step 4. I did not choose a schedule or pick the "Continuous" button, which means my replication will be manual only. I can now push the Manual Replicate button on my Actions list and you will see it start. You will see both a barber pole animation and also an update in the status bar on the top of the screen that a replication event has begun. This also goes into the event log.  Step 5. The status bar will also log an event when it's done. Step 6. If you go back to Configuration-->Services-->Remote Replication, you will see your event. Step 7. Done. To see your new replica, go to the other Pool (Pool1 for me), and click the "Replica" area below the words "Filesystems | LUNs" Here, you will see any replicas that have come in from any of your sources. It's a simple matter from here to break the replication, which will change this to a "Local" LUN, and then delete the original LUN back in Pool2. Ok, that's all for now, but I promise to give out more tricks sometime in November !!! There's very exciting stuff coming down the pipe for the ZFSSA. Both new hardware and new software features that I'm just drooling over. That's all I can say, but contact your local sales SC to get a NDA roadmap talk if you want to hear more.   Happy Halloween,Steve 

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• Unix RPC programming

  - by Abhi

  Heyy all, I needed some help with ONC RPC programming. My task is to create two-tier client-server architecture wherein one main server (something like a directory) keeps a track of level-two servers and acts as a lookup; the level-two servers exposing some trivial functions, and finally, the clients for level-two servers. The clients ask the directory where a server is located, and then communicate with it. Using RPCGEN, we can create a pair of client-server code; however, the clients in this case need to have stubs for the directory as well as the level-two functions. Being a newbie to RPC, I'm having trouble conceptualizing the way I should code this. How can I call a function from a different server if a client is generated using a different IDL ? Any pointers would be appreciated :) Regards, Abhi

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• how to change default page for a site in Sharepoint using Team Definition?

  - by netadictos

  Now i am using the sharepoint extensions 1.1 for Visual Studio 2005 to deploy my website in Sharepoint 2007. When you create a new site, there is a new default page with the contenttype: Welcomelinks..., i would like to change it including my own ContentType and PageLayout in the onet.xml. The way to deploy I am using is Team Definition. Could someone give some code, plz?

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• How do I resolve this exercise on C++? [closed]

  - by user40630

  (Card Shuffling and Dealing) Create a program to shuffle and deal a deck of cards. The program should consist of class Card, class DeckOfCards and a driver program. Class Card should provide: a) Data members face and suit of type int. b) A constructor that receives two ints representing the face and suit and uses them to initialize the data members. c) Two static arrays of strings representing the faces and suits. d) A toString function that returns the Card as a string in the form “face of suit.” You can use the + operator to concatenate strings. Class DeckOfCards should contain: a) A vector of Cards named deck to store the Cards. b) An integer currentCard representing the next card to deal. c) A default constructor that initializes the Cards in the deck. The constructor should use vector function push_back to add each Card to the end of the vector after the Card is created and initialized. This should be done for each of the 52 Cards in the deck. d) A shuffle function that shuffles the Cards in the deck. The shuffle algorithm should iterate through the vector of Cards. For each Card, randomly select another Card in the deck and swap the two Cards. e) A dealCard function that returns the next Card object from the deck. f) A moreCards function that returns a bool value indicating whether there are more Cards to deal. The driver program should create a DeckOfCards object, shuffle the cards, then deal the 52 cards. This above is the exercise I'm trying to solve. I'd be very much appreciated if someone could solve it and explain it to me. The main idea of the program is quite simple. What I don't get is how to build the constructor for the class DeckOfCards and how to generate the 52 cards of the deck with different suits and faces. Untill now I've managed to do this: #include <iostream> #include <vector> using namespace std; /* * */ /* a) Data members face and suit of type int. b) A constructor that receives two ints representing the face and suit and uses them to initialize the data members. c) Two static arrays of strings representing the faces and suits. d) A toString function that returns the Card as a string in the form “face of suit.” You can use the + operator to concatenate strings. */ class Card { public: Card(int, int); string toString(); private: int suit, face; static string faceNames[13]; static string suitNames[4]; }; string Card::faceNames[13] = {"Ace","Two","Three","Four","Five","Six","Seven","Eight","Nine","Ten","Queen","Jack","King"}; string Card::suitNames[4] = {"Diamonds","Clubs","Hearts","Spades"}; string Card::toString() { return faceNames[face]+" of "+suitNames[suit]; } Card::Card(int f, int s) :face(f), suit(s) { } /* Class DeckOfCards should contain: a) A vector of Cards named deck to store the Cards. b) An integer currentCard representing the next card to deal. c) A default constructor that initializes the Cards in the deck. The constructor should use vector function push_back to add each Card to the end of the vector after the Card is created and initialized. This should be done for each of the 52 Cards in the deck. d) A shuffle function that shuffles the Cards in the deck. The shuffle algorithm should iterate through the vector of Cards. For each Card, randomly select another Card in the deck and swap the two Cards. e) A dealCard function that returns the next Card object from the deck. f) A moreCards function that returns a bool value indicating whether there are more Cards to deal. */ class DeckOfCards { public: DeckOfCards(); void shuffleCards(); Card dealCard(); bool moreCards(); private: vector<Card> deck(52); int currentCard; }; int main(int argc, char** argv) { return 0; } DeckOfCards::DeckOfCards() { //I'm stuck here I have no idea of what to take out of here. //I still don't fully get the idea of class inside class and that's turning out as a problem. I try to find a way to set the suits and faces members of the class Card but I can't figure out how. for(int i=0; i<deck.size(); i++) { deck[i]//....There is no function to set them. They must be set when initialized. But how?? } } For easier reading: http://pastebin.com/pJeXMH0f

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• C#: What is the preferred way to handle this error?

  - by Ash

  I have a class 'Hand' that consists of two playing cards as below: public class Card { public char r, s; public Card(char rank, char suit) { r = rank; s = suit; } } public class Hand { public Card c1, c2; public Hand(Card one, Card two) { c1 = one; c2 = two; } } In a 52 card deck we can't have two identical cards. How should I deal with an error where I accidentally instance a class with two identical cards, e.g (Ah, Ah)? Thanks, Ash

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• Auto Increment feature of SQL Server

  - by Rahul Tripathi

  I have created a table named as ABC. It has three columns which are as follows:- The column number_pk (int) is the primary key of my table in which I have made the auto increment feature on for that column. Now I have deleted two rows from that table say Number_pk= 5 and Number_pk =6. The table which I get now is like this:- Now if I again enter two new rows in this table with the same value I get the two new Number_pk starting from 7 and 8 i.e, My question is that what is the logic behind this since I have deleted the two rows from the table. I know that a simple answer is because I have set the auto increment on for the primary key of my table. But I want to know is there any way that I can insert the two new entries starting from the last Number_pk without changing the design of my table? And how the SQL Server manage this record since I have deleted the rows from the database??

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• javascript open window references

  - by duckofrubber

  Hi, I'm having some issues understanding how to reference new browser windows after opening them. As an example, if I created 3 new windows from a main one (index.html): var one = window.open( 'one.html', 'one',"top=10,left=10,width=100,height=100,location=no,menubar=no,scrollbars=no,status=no,toolbar=no,resizable=no"); var two = window.open( 'two.html', 'two',"top=100,left=10,width=100,height=100,location=no,menubar=no,scrollbars=no,status=no,toolbar=no,resizable=no"); var three = window.open( 'three.html', 'three',"top=200,left=10,width=100,height=100,location=no,menubar=no,scrollbars=no,status=no,toolbar=no,resizable=no"); two.focus(); How could I programmatically focus on (or just refer to) browser "three" if browser "two" is currently in focus?

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• merging arrays of hashes

  - by Ben

  I have two arrays of hashes. Array1 => [{attribute_1 = A, attribute_2 = B}, {attribute_1 = A, attribute_2 = B}] Array2 => [{attribute_3 = C, attribute_2 = D}, {attribute_3 = C, attribute_4 = D}] Each hash in the array is holding attributes for an object. In the above example, there are two objects that I'm working with. There are two attributes in each array for each object How do I merge the two arrays? I am trying to get a single array (there is no way to get a single array from the start because I have to make two different API calls to get these attributes). DesiredArray => [{attribute_1 = A, attribute_2 = B, attribute_3 = C, attribute_2 = D}, {attribute_1 = A, attribute_2 = B, attribute_3 = C, attribute_2 = D}] I've tried a couple things, including the iteration methods and the merge method, but I've been unable to get the array I need.

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• Multiple CSS Classes: Properties Overlapping based on the order defined.

  - by Jian Lin

  Is there a rule in CSS that determines the cascading order when multiple classes are defined on an element? (class="one two" vs class="two one") Right now, there seems to be no such effect. Example: both divs are orange in color on Firefox <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd"> <html> <head> <style> .one { border: 6px dashed green } .two { border: 6px dashed orange } </style> </head> <body> <div class="one two"> hello world </div> <div class="two one"> hello world </div>

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• Cocos2d: Moving background on update: offsett issue

  - by mm24

  working with Objective C, iOS and Cocos2d I am developing a vertical scrolling shooter game for iPhone (retina display models with 640 width x 960 height pixel resolution). My basic algorithm works as following: I create two instances of an image that has exactly 640 width x 960 height pixel of resolution, which we will call imageA and imageB I then set the two imags with exactly 480.0f of offset from each other, as the screenSize of a CCScene is set by default to 480.0f. At each update method call I move the two images by the same value. I make sure that their offsett stays to 480.0f However when running the game I see a 1 pixel height line between the two images. This literally bugs me and would like to adjust this. What am I doing wrong? This is a zoom in on the background when the "offsett line" is visible. The white line you can see divides the two background images and is not meant to exist as both images are completely black :): If I change the yPositionOfSecondElement value to 479.0f until the first loop the two images overlap correctly, but as soon as the loop starts the two images starts having an offsett of -1.0f. Here is the initialization code: -(void) init { //... screenHeight = 480.0f; yPositionOfSecondElement= screenHeight;//I tried subtracting an offsett of -1 but eventually the image would go wrong again yPositionOfFirstElement = 0.0f; loopedBackgroundImageInstanceA = [BackgroundLoopedImage loopImageForLevel:levelName]; loopedBackgroundImageInstanceA.anchorPoint = CGPointMake(0.5f, 0.0f); loopedBackgroundImageInstanceA.position = CGPointMake(160.0f, yPositionOfFirstElement); [node addChild:loopedBackgroundImageInstanceA z:zLevelBackground]; //loopedBackgroundImageInstanceA.color= ccRED; loopedBackgroundImageInstanceB = [BackgroundLoopedImage loopImageForLevel:levelName]; loopedBackgroundImageInstanceB.anchorPoint = CGPointMake(0.5f, 0.0f); loopedBackgroundImageInstanceB.position = CGPointMake(160.0f, yPositionOfSecondElement); [node addChild:loopedBackgroundImageInstanceB z:zLevelBackground]; //.... } And here is the move code called at each update: -(void) moveBackgroundSprites:(BackgroundLoopedImage*)imageA :(BackgroundLoopedImage*)imageB :(ccTime)delta { isEligibleToMove=false; //This is done to avoid rounding errors float yStep = delta * [GameController sharedGameController].currentBackgroundSpeed; NSString* formattedNumber = [NSString stringWithFormat:@"%.02f", yStep]; yStep = atof([formattedNumber UTF8String]); //First should adjust position of images [self adjustPosition:imageA :imageB]; //The can get the actual image position CGPoint posA = imageA.position; CGPoint posB = imageB.position; //Here could verify if the checksum is equal to the required difference (should be 479.0f) if (![self verifyCheckSum:posA :posB]) { CCLOG(@"does not comply A"); } //At this stage can compute the hypotetical new position CGPoint newPosA = CGPointMake(posA.x, posA.y - yStep); CGPoint newPosB = CGPointMake(posB.x, posB.y - yStep); // Reposition stripes when they're out of bounds if (newPosA.y <= -yPositionOfSecondElement) { newPosA.y = yPositionOfSecondElement; [imageA shuffle]; if (timeElapsed>=endTime && hasReachedEndLevel==FALSE) { hasReachedEndLevel=TRUE; shouldMoveImageEnd=TRUE; } } else if (newPosB.y <= -yPositionOfSecondElement) { newPosB.y = yPositionOfSecondElement; [imageB shuffle]; if (timeElapsed>=endTime && hasReachedEndLevel==FALSE) { hasReachedEndLevel=TRUE; shouldMoveImageEnd=TRUE; } } //Here should verify that the check sum is equal to 479.0f if (![self verifyCheckSum:posA :posB]) { CCLOG(@"does not comply B"); } imageA.position = newPosA; imageB.position = newPosB; //Here could verify that the check sum is equal to 479.0f if (![self verifyCheckSum:posA :posB]) { CCLOG(@"does not comply C"); } isEligibleToMove=true; } -(BOOL) verifyCheckSum:(CGPoint)posA :(CGPoint)posB { BOOL comply = false; float sum = 0.0f; if (posA.y > posB.y) { sum = posA.y - posB.y; } else if (posB.y > posA.y){ sum = posB.y - posA.y; } else{ return false; } if (sum!=yPositionOfSecondElement) { comply= false; } else{ comply=true; } return comply; } And here is what happens on the update: if(shouldMoveImageA && shouldMoveImageB) { if (isEligibleToMove) { [self moveBackgroundSprites:loopedBackgroundImageInstanceA :loopedBackgroundImageInstanceB :delta]; } Forget about shouldMoveImageA and shouldMoveImageB, this is just for when the background reaches the end of level, this works.

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• How to convert JavaScript dictionary into Python syntax

  - by Sputnix

  Writing out javascript dictionary from inside of JavaScript- enabled application (such as Adobe) into external .jsx file (or any other .txt file) the context of resulted file dictionary looks like: ({one:"1", two:"2"}) (Please note that each dictionary keys are written as they are the variables name (which is not true). A next step is to read this .jsx file with Python. I need to find a way to convert ({one:"1", two:"2"}) into Python dictionary syntax such as: {'one':"1", 'two':"2"} It has been already suggested that instead of using JavaScript's built-in dict.toSource() it would make more sense to use JSON which would write a dictionary content in similar to Python syntax. But unfortunately using JSON is not an option for me. I need to find a way to convert ({one:"1", two:"2"}) into {'one':"1", 'two':"2"} using Python alone. Any suggestions on how to achieve it? Once again, the problem mostly in dictionary keys syntax which inside of Python look like variable names instead of strings-like dictionary keys names: one vs "one"

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• PASS: SQLRally Thoughts

  - by Bill Graziano

  The PASS Board recently decided that we wouldn’t put another US-based SQLRally on the calendar until we had a chance to review the program. I wanted to provide some of my thinking around this. Keep in mind that this is the opinion of one Board member. The Board committed to complete two SQLRally events to determine if an event modeled between SQL Saturday and the Summit was viable. We’ve completed the two events and now it’s time to step back and review the program. This is my seventh year on the PASS Board. Over that time people have asked me why PASS does certain things. Many, many times my answer has been “Because that’s the way we did it last year”. And I am tired of giving that answer. We need to take a step back and review the US-based SQLRally before we schedule another one. It would be irresponsible for me as a Board member to commit resources to this without validating that what we’re doing makes sense for the organization and our members. I have no doubt that this was a great event for the attendees. We just need to validate it’s the best use of our resources. Please keep in mind that we haven’t cancelled the event. We’ve just said we need to review it before scheduling another one. My opinion is that some fairly serious changes are needed to the model before we consider it again – IF we do it again. I’ve come to that conclusion after speaking with the Dallas organizers, our HQ team, our Marketing team, other Board members (including one of the Orlando organizers), attendees in Orlando and Dallas and visiting other similar events. I should point out that their views aren’t unanimous on nearly any part of this event -- which is one of the reasons I want to take some time and think about this before continuing. I think it’s helpful to look at the original goals of what we were trying to accomplish. Andy Warren wrote these up in August of 2010. My summary of these goals and some thoughts on each one is below. Many of these thoughts revolve around the growth of SQL Saturdays. In the two years since that document was written these events have grown significantly. The largest SQL Saturdays are now over 500 people which mean they are nearly the same size as our recent SQLRally. Our goals included: Geographic diversity. We wanted an event in an area of the country that was away from any given Summit location. I think that’s still a valid goal. But we also have SQL Saturdays all over the country. What does SQLRally bring to this that SQLSaturday doesn’t? Speaker growth. One of the stated goals was to build a “farm club” for speakers. This gives us a way for speakers to work up to speaking at Summit by speaking in front of larger crowds. What does SQLRally bring to this that the larger SQL Saturdays aren’t providing? Pre-Conference speakers is one obvious answer here. Lower price. On a per-day basis, SQLRally is roughly 1/4th the price of the Summit. We wanted a way for people to experience something Summit-like at a lower price point. The challenge is that we are very budget constrained at that lower price point. International Event Model.  (I need to write more about this but I’m out of time.  I’ll cover it in the next installment.) There are a number of things I really like about SQLRally. I love the smaller conferences. They give me a chance to meet more people than at something the size of Summit. I like the two day format. That gives you two evenings to be at social events with people. Seeing someone a second day is a great way to build a bond with that person. That’s more difficult to do at a SQL Saturday. We also need to talk about the financial aspects of the event. Last year generated a small $17,000 profit on revenues of $200,000. Percentage-wise that’s reasonable but on an absolute basis it’s not a huge amount in our budget. We think this year will lose between $30,000 and $50,000 and take roughly 1,000 hours of HQ time. We don’t have detailed financials back yet but that’s our best guess at this point. Part of that was driven by using a convention center instead of a hotel. Until we get detailed financials back we won’t have the full picture around the financial impact. This event also takes time and mindshare from our Marketing team. This may sound like a small thing but please don’t underestimate it. Our original vision for this was something that would take very little time from our Marketing team and just a few mentions in the Connector. It turned out to need more than that. And all those mentions and emails take up space we could use to talk about other events and other programs. Last I wanted to talk about some of the things I’m thinking about. I don’t think it’s as simple as saying if we just fix “X” it all gets better. Is this that much better of an event than SQL Saturdays? What if we gave a few SQL Saturdays some extra resources? When SQL Saturdays were around 250 people that wasn’t as viable. With some of those events over 500 we need to reconsider this. We need to get back to a hotel venue. That will help with cost and networking. Is this the best use of the 1,000 HQ hours that we invested in the event? Is our price-point correct? I’m leaning toward raising our price closer to Summit on a per-day basis. I think this will let us put on a higher quality event and alleviate much of the budget pressure. Should growing speakers be a focus? Having top-line pre-conference speakers helps market the event. It will also have an impact on pricing and overall profit. We should also ask if it actually does grow speakers. How many of these people will eventually register for Summit? Attend chapters? Is SQLRally a driver into PASS or is it something that chapters, etc. drive people to? Should we have one paid day and one free instead of two paid days? This is a very interesting model that is used by SQLBits in the UK. This gives you the two day aspect as well as offering options for paid and free attendees. I’m very intrigued by this. Should we focus on a topic? Buried in the minutes is a discussion of whether PASS should have a Business Analytics conference separate from Summit. This is an interesting question to consider. Would making SQLRally be focused on a particular topic make it more attractive? Would that even be a SQLRally? Can PASS effectively manage the two events? (FYI - Probably not.) Would it help differentiate it from Summit and SQL Saturday? These are all questions that I think should be asked and answered before we do this event again. And we can’t do that if we don’t take time to have the discussion. I wanted to get this published before I take off for a few days of vacation. When I get back I’d like to write more about why the international events are different and talk about where we go from here.

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• How can I create different DLLs in one project?

  - by jaloplo

  I have a question I don't know if it can be solved. I have one C# project on Visual Studio 2005 and I want to create different DLL names depending on a preprocessor constant. What I have in this moment is the preprocessor constant, two snk files and two assembly's guid. I also create two configurations (Debug and Debug Preprocessor) and they compile perfectly using the snk and guid appropiate. #if PREPROCESSOR_CONSTANT [assembly: AssemblyTitle("MyLibraryConstant")] [assembly: AssemblyProduct("MyLibraryConstant")] #else [assembly: AssemblyTitle("MyLibrary")] [assembly: AssemblyProduct("MyLibrary")] #endif Now, I have to put the two assemblies into the GAC. The first assembly is added without problems but the second isn't. What can I do to create two or more different assemblies from one Visual Studio project? It's possible that I forgot to include a new line on "AssemblyInfo.cs" to change the DLL name depending on the preprocessor constant?

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• Can I mix compile time string comparison with MPL templates?

  - by Negative Zero

  I got this compile time string comparison from another thread using constexpr and C++11 (http://stackoverflow.com/questions/5721813/compile-time-assert-for-string-equality). It works with constant strings like "OK" constexpr bool isequal(char const *one, char const *two) { return (*one && *two) ? (*one == *two && isequal(one + 1, two + 1)) : (!*one && !*two); } I am trying to use it in the following context: static_assert(isequal(boost::mpl::c_str<boost::mpl::string<'ak'>>::value, "ak"), "should not fail"); But it gives me an compilation error of static_assert expression is not an constant integral expression. Can I do this?

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• How to handle splitting a file under source control?

  - by sharptooth

  I have a .cpp file and .h file containing a class. Class.cpp contains the implementation and Class.h contains the definition. The class is overcomplicated so I want to separate some code and move it into a separate class. So I create NewClass.cpp and NewClass.h and move the code there. How do I handle this when the files are under SVN? I can simply "svn add" the two new files, but then they will appear as new and will have no history. I could instead "svn copy and rename" the two initial files and edit the the two old files and the two new files - then the two new files will have common history. Which approach is better from the point of version control? Should the new files share history with the old files or should they appear as new?

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• Why does $('#id') return true if id doesn't exist?

  - by David

  I always wondered why jQuery returns true if I'm trying to find elements by id selector that doesnt exist in the DOM structure. Like this: <div id="one">one</div> <script> console.log( !!$('#one') ) // prints true console.log( !!$('#two') ) // is also true! (empty jQuery object) console.log( !!document.getElementById('two') ) // prints false </script> I know I can use !!$('#two').length since length === 0 if the object is empty, but it seems logical to me that a selector would return the element if found, otherwise null (like the native document.getElementById does). F.ex, this logic can't be done in jQuery: var div = $('#two') || $('<div id="two"></div>'); Wouldnt it be more logical if the ID selector returned null if not found? anyone?

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• Determining whether a file is a duplicate

  - by Todd R

  Is there a reliable way to determine whether or not two files are the same? For example, two files with the same size and type may or may not be the same binarilly (yeah, I know it's not really a word). I assume that comparing one or two checksums of the files will help, but I wonder: How reliable are checksums at determining whether two files are different; what are the chances of two different files having the same checksum? Would reliability increase by applying additional checksum comparisons? Which checksum algorithm(s) would be the most efficient and/or reliable? Any ideas, suggestions or thoughts are appreciated! P.S. The code for this is being written in Java running on a nix system, but generic or platform agnostic input is most helpful.

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• PHP Classes: parent/child communication

  - by Fffff

  Hi all, I'm having some trouble extending Classes in PHP. Have been Googling for a while. $a = new A(); $a->one(); $a->b1(); // something like this, or... class A { public $test1; public function one() { echo "this is A-one"; $this->two(); $parent->two(); $parent->B->two(); // ...how do i do something like this (prepare it for using in instance $a)? } } class B extends A { public $test2; public function two($test) { echo "this is B-two"; } } I'm ok at procedural PHP.

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• Grammatically correct double-noun identifiers, plural versions

  - by Michal Czardybon

  Consider compounds of two nouns, which in natural English would most often appear in the form "noun of noun", e.g. "direction of light", "output of a filter". When programming we usually write "LightDirection" and "FilterOutput". Now, I have a problem with plural nouns. There are two cases: 1) singular of plural e.g. "union of (two) sets", "intersection of (two) segments" Which is correct, SetUnion and SegmentIntersection or SetsUnion and SegmentsIntersection? 2) plural of plural There are two subcases: (a) Many elements, each having many related elements, e.g. "outputs of filters" (b) Many elements, each having single related element, e.g. "directions of vectors" Shell I use FilterOutputs and VectorDirections or FiltersOutputs and VectorsDirections? I suspect correct is the first version (FilterOutupts, VectorDirections), but I think it may lead to ambiguities, e.g. FilterOutputs - many outputs of a single filter or many outputs of many filters? LineSegmentProjections - projections of many segments or many projections of a single segment?

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• SQL Server JOIN with optional NULL values

  - by Paul McLoughlin

  Imagine that we have two tables as follows: Trades ( TradeRef INT NOT NULL, TradeStatus INT NOT NULL, Broker INT NOT NULL, Country VARCHAR(3) NOT NULL ) CTMBroker ( Broker INT NOT NULL, Country VARCHAR(3) NULL ) (These have been simplified for the purpose of this example). Now, if we wish to join these two tables on the Broker column, and if a country exists in the CTMBroker table on the Country, we have the following two choices: SELECT T.TradeRef,T.TradeStatus FROM Trades AS T JOIN CTMBroker AS B ON B.Broker=T.Broker AND ISNULL(B.Country, T.Country) = T.Country or SELECT T.TradeRef,T.TradeStatus FROM Trades AS T JOIN CTMBroker AS B ON B.Broker=T.Broker AND (B.COUNTRY=T.Country OR B.Country IS NULL) These are both logically equivalent, however in this specific circumstance for our database (SQL Server 2008, SP1) two different execution plans are produced for these two queries with the second version significantly outperforming the first version in terms of both time and logical reads. My question really is as follows: as a general rule would (2) be preferred to (1), or does this just happen to be exploiting some particular idiosyncracy of the optimiser in 2008 SP1 (that could therefore change with future versions of SQL Server).

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