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  • tftpd-hpa service must be restarted before working after fresh boot

    - by Steve
    I'm running Ubuntu 12.04 inside a VirtualBox VM. I've installed tftpd-hpa so I can boot an embedded Linux device via tftp. My problem is that after a fresh boot of the VM, tftpd doesn't seem to work until I restart the service, after which is works great until the system is rebooted. The transcript below should explain the situation. EDIT: After the fresh boot, I execute netstat -a | grep tftp and find nothing. After restarting the service, the same command returns udp 0 0 *:tftp *:* (whitespace removed). I think this might be the key to the problem, I'm just not sure how to resolve it. I don't think it's related to this specific issue, but I had another problem with tftpd that was asked and answered in this question. steve@steve-VirtualBox:~$ cat /etc/default/tftpd-hpa # /etc/default/tftpd-hpa TFTP_USERNAME="tftp" TFTP_DIRECTORY="/var/lib/tftpboot" TFTP_ADDRESS="0.0.0.0:69" TFTP_OPTIONS="--secure" steve@steve-VirtualBox:~$ ls -l /var/lib/tftpboot total 8204 -rw-r--r-- 1 root root 34352 May 28 08:22 am335x-boneblack.dtb -rw-r--r-- 1 root root 33206 May 28 08:22 am335x-bone.dtb -rw-r--r-- 1 root root 41564 May 28 08:22 am335x-evm.dtb -rw-r--r-- 1 root root 38048 May 28 08:22 am335x-evmsk.dtb -rwxr-xr-x 1 root root 4117904 May 20 09:39 zImage -rw-r--r-- 1 root root 4117616 May 28 08:22 zImage-am335x-evm.bin steve@steve-VirtualBox:~$ tftp localhost tftp> get zImage Transfer timed out. tftp> quit steve@steve-VirtualBox:~$ sudo service tftpd-hpa restart [sudo] password for steve: tftpd-hpa stop/waiting tftpd-hpa start/running, process 2106 steve@steve-VirtualBox:~$ tftp localhost tftp> get zImage Received 4143798 bytes in 1.4 seconds tftp> quit steve@steve-VirtualBox:~$

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  • Apache: How to redirect OPTIONS request with .htaccess?

    - by Milan Babuškov
    I have Apache 2.2.4 server with a lot of messages like this in the access_log: ::1 - - [15/May/2010:19:55:01 +0200] "OPTIONS * HTTP/1.0" 400 543 ::1 - - [15/May/2010:20:22:17 +0200] "OPTIONS * HTTP/1.0" 400 543 ::1 - - [15/May/2010:20:24:58 +0200] "OPTIONS * HTTP/1.0" 400 543 ::1 - - [15/May/2010:20:25:55 +0200] "OPTIONS * HTTP/1.0" 400 543 ::1 - - [15/May/2010:20:27:14 +0200] "OPTIONS * HTTP/1.0" 400 543 These are the "internal dummy connections" as explained on this page: http://wiki.apache.org/httpd/InternalDummyConnection The page also hits my main problem: "In 2.2.6 and earlier, in certain configurations, these requests may hit a heavy-weight dynamic web page and cause unnecessary load on the server. You can avoid this by using mod_rewrite to respond with a redirect when accessed with that specific User-Agent or IP address." Well, obviously I cannot use UserAgent because I minimized the server signature, but I could use IP address. However, I don't have a clue what should the RewriteCond and RewriteRule look for IPv6 address ::1. The website where this runs is using CodeIgniter, so there is already the following .htaccess in place, I just need to add to it: RewriteEngine on RewriteCond %{REQUEST_URI} ^/system.* RewriteRule ^(.*)$ /index.php?/$1 [G] RewriteCond %{REQUEST_FILENAME} !-f RewriteCond %{REQUEST_FILENAME} !-d RewriteRule ^(.*)$ /index.php?/$1 [L] Any idea how to write this .htaccess rule?

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  • Mysql - innoDb - is in the future! Current system log sequence number

    - by Ward Loockx
    I have this error in my syslog. I restored an older dump to solve this problem, after some reading. Now The errors in syslog are far less than before. But still a few times an hour I get Sep 1 14:23:29 homer mysqld: 120901 14:23:29 InnoDB: Error: page 96637 log sequence number 7 1223357717 Sep 1 14:23:29 homer mysqld: InnoDB: is in the future! Current system log sequence number 6 647303887. Sep 1 14:23:29 homer mysqld: InnoDB: Your database may be corrupt or you may have copied the InnoDB Sep 1 14:23:29 homer mysqld: InnoDB: tablespace but not the InnoDB log files. See Sep 1 14:23:29 homer mysqld: InnoDB: http://dev.mysql.com/doc/refman/5.1/en/forcing-recovery.html Sep 1 14:23:29 homer mysqld: InnoDB: for more information. Sep 1 14:23:29 homer mysqld: 120901 14:23:29 InnoDB: Error: page 96638 log sequence number 8 150027924 Sep 1 14:23:29 homer mysqld: InnoDB: is in the future! Current system log sequence number 6 647303887. Sep 1 14:23:29 homer mysqld: InnoDB: Your database may be corrupt or you may have copied the InnoDB Sep 1 14:23:29 homer mysqld: InnoDB: tablespace but not the InnoDB log files. See Sep 1 14:23:29 homer mysqld: InnoDB: http://dev.mysql.com/doc/refman/5.1/en/forcing-recovery.html Sep 1 14:23:29 homer mysqld: InnoDB: for more information. Sep 1 14:23:29 homer mysqld: 120901 14:23:29 InnoDB: Error: page 96639 log sequence number 7 4208567151 Sep 1 14:23:29 homer mysqld: InnoDB: is in the future! Current system log sequence number 6 647303887. Sep 1 14:23:29 homer mysqld: InnoDB: Your database may be corrupt or you may have copied the InnoDB Sep 1 14:23:29 homer mysqld: InnoDB: tablespace but not the InnoDB log files. See Sep 1 14:23:29 homer mysqld: InnoDB: http://dev.mysql.com/doc/refman/5.1/en/forcing-recovery.html Sep 1 14:23:29 homer mysqld: InnoDB: for more information. Anybody that knows how I can track what database is causing this issue? And how to fix?

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  • Revover original email from Sendmail log

    - by Xavi Colomer
    I have a website the contact form has been failing silently for two weeks (Wordpress + Contact form 7). Apparently updating to Contact Form 7 made the assigned email to fail [email protected], I also tested with [email protected] and it also failed until I tried with gmail and it finally worked. Apparently @telefonica.net and @me.com domains are not working with this version of the plugin, but I have to investigate the cause. I found the logs of the lost emails, but I would like to know If I can recover the sender or the content of the original messages. May 24 23:41:11 localhost sendmail[27653]: s4P3fBc3027653: from=www-data, size=3250, class=0, nrcpts=1, msgid=<[email protected]_web.com>, relay=www-data@localhost May 24 23:41:11 localhost sm-mta[27655]: s4P3fBdA027655: from=<[email protected]>, size=3359, class=0, nrcpts=1, msgid=<[email protected]_web.com>, proto=ESMTP, daemon=MTA-v4, relay=localhost.localdomain [127.0.0.1] May 24 23:41:11 localhost sendmail[27653]: s4P3fBc3027653: [email protected], ctladdr=www-data (33/33), delay=00:00:00, xdelay=00:00:00, mailer=relay, pri=33250, relay=[127.0.0.1] [127.0.0.1], dsn=2.0.0, stat=Sent (s4P3fBdA027655 Message accepted for delivery) May 24 23:41:12 localhost sm-mta[27657]: s4P3fBdA027655: to=<[email protected]>, ctladdr=<[email protected]> (33/33), delay=00:00:01, xdelay=00:00:01, mailer=esmtp, pri=123359, relay=tnetmx.telefonica.net. [86.109.99.69], dsn=5.0.0, stat=Service unavailable May 24 23:41:12 localhost sm-mta[27657]: s4P3fBdA027655: s4P3fCdA027657: DSN: Service unavailable May 24 23:41:12 localhost sm-mta[27657]: s4P3fCdA027657: to=<[email protected]>, delay=00:00:00, xdelay=00:00:00, mailer=local, pri=30000, dsn=2.0.0, stat=Sent Thanks

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  • WCF webservice stop working after upgrade to framework 3.5 sp1

    - by Victor
    I have a wcf webservice on one of my testing servers. Everything worked fine until I upgraded frome framework 3.5 to 3.5 sp1. the wcf web service stoped working and returns the error: "Failed to invoke the service. The service may be offline or inaccessible. Refer to the stack trace for details." "The remote server returned an unexpected response: (502) Proxy Error ( The specified network name is no longer available. ). Server stack trace: at System.ServiceModel.Channels.HttpChannelUtilities.ValidateRequestReplyResponse(HttpWebRequest request, HttpWebResponse response, HttpChannelFactory factory, WebException responseException) at System.ServiceModel.Channels.HttpChannelFactory.HttpRequestChannel.HttpChannelRequest.WaitForReply(TimeSpan timeout) at System.ServiceModel.Channels.RequestChannel.Request(Message message, TimeSpan timeout) at System.ServiceModel.Dispatcher.RequestChannelBinder.Request(Message message, TimeSpan timeout) at System.ServiceModel.Channels.ServiceChannel.Call(String action, Boolean oneway, ProxyOperationRuntime operation, Object[] ins, Object[] outs, TimeSpan timeout) at System.ServiceModel.Channels.ServiceChannel.Call(String action, Boolean oneway, ProxyOperationRuntime operation, Object[] ins, Object[] outs) at System.ServiceModel.Channels.ServiceChannelProxy.InvokeService(IMethodCallMessage methodCall, ProxyOperationRuntime operation) at System.ServiceModel.Channels.ServiceChannelProxy.Invoke(IMessage message)" Does anyone know what is going on here?

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  • How to write scripts that can run in bash and csh?

    - by Victor Liu
    I'm not sure if this is even possible, but is there a way to write shell scripts that can be interpreted by both the Bourne shell as well as C shell? I want to avoid simply checking for the shell and running a shell-specific code. If this is possible, are there any guides on how to do it? I have always written my scripts for Bourne shell syntax, and I know next to nothing about csh, so this may be a stupid question. I have Google'd for the differences between shells, but there is little information (as far as I can tell) on its implications for scripting.

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  • Googlebot substitutes the links of Rails app with subdomain.

    - by Victor
    I have this Rails app, with domain name abc.com. I am also having a separate subdomain for Piwik stats, in this subdomain stats.abc.com. Googlebot somehow listed some of the links with my subdomain too. http://abc.com/login http://stats.abc.com/login http://abc.com/signup http://stats.abc.com/signup The ones with stats will reference to the same page in the app, but are treated entirely different website. I have put in robots.txt in stats after this matter, but wondering if there is any appropriate way to block this because I may have new subdomains in future. Here's my content in robots.txt User-agent: * Disallow: / Thanks.

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  • Determining the order of a list of numbers (possibly without sorting)

    - by Victor Liu
    I have an array of unique integers (e.g. val[i]), in arbitrary order, and I would like to populate another array (ord[i]) with the the sorted indexes of the integers. In other words, val[ord[i]] is in sorted order for increasing i. Right now, I just fill in ord with 0, ..., N, then sort it based on the value array, but I am wondering if we can be more efficient about it since ord is not populated to begin with. This is more of a question out of curiousity; I don't really care about the extra overhead from having to prepopulate a list and then sort it (it's small, I use insertion sort). This may be a silly question with an obvious answer, but I couldn't find anything online.

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  • Amazon Elastic Terms and Conditions

    - by PP
    WARNING: Have you really read Amazon's Terms and Conditions? Would anybody seriously agree to this term on Amazon's Elastic services sign up page? 6.2. Restrictions with Respect to Use of Marks. Your use of any trademarks, service marks, service or trade names, logos, and other designations of AWS and its affiliates or licensors, hereinafter "Marks", shall strictly comply with the following provisions. You may use the Marks in conjunction with the display of the AWS Content and for the purpose of indicating that your Application was created using the Services. You may use the Marks only in the form in which we make them available to you and not in any manner that disparages Amazon, its affiliates or its licensors, or that otherwise dilutes any Mark. Other than your limited right to use the Marks as provided in this Agreement, we and our licensors retain all right, title, and interest in and to the Marks. You will not at any time now or in the future challenge or assist others to challenge the validity of the Marks, or attempt to register confusingly similar trademarks, trade names, service marks or logos. You agree to follow our the Trademark Use Guidelines posted on the Amazon Web Services™ Trademark Guidelines page (the "Trademark Guidelines") as those guidelines may change from time to time. The Trademark Guidelines are incorporated herein by reference. You must immediately discontinue use of any Mark as specified by us at any time in writing. We may modify any Marks provided to you at any time, and upon notice, you will use only the modified Marks and not the old Marks. Other than as specified in this Agreement, you may not use any trademark, service mark, trade name or other business identifier of Amazon or its affiliates unless you obtain Amazon's or its affiliates' prior written consent. The foregoing prohibition includes the use of "amazon," any other trademark of AWS, Amazon or its affiliates, or variations or misspellings of any of them, in the name of an Application or in a URL to the left of the top-level domain name (e.g., ".com", ".net", "co.uk", etc.)-for example, a URL such as "amazon.mydomain.com", "amaozn.com" or "amazonauctions.net" are expressly prohibited. Any use you make of the Marks shall inure to our benefit and you hereby irrevocably assign to us all right, title and interest in the same. In addition, you agree not to misrepresent or embellish the relationship between us and you, for example by implying that we support, sponsor, endorse, or contribute money to you or your business endeavors. If you are a large company and you want to use Amazon's services you must agree that: you may not use the word "amazon" in any domain name you control (even if you are a forestry company) you may not use any word Amazon choose to trademark in any domain you control (regardless of whether the name has a different meaning/purpose in your industry) from now until forever you will never dispute any claim Amazon makes on any word you or anybody else uses Seriously, who would sign such a thing?

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  • EF4 CTP5 Conflicting changes detected. This may happen when trying to insert multiple entities with the same key.

    - by user658332
    hi, I am new to EF4 CTP5. I am just hanging at one problem.. I am using CodeFirst without Database, so when i execute application, it generated DB for me. here is my scenario, i have following Class structure... public class KVCalculationWish { public KVCalculationWish() { } public int KVCalculationWishId { get; set; } public string KVCalculationWishName { get; set; } public int KVSingleOfferId { get; set; } public virtual KVSingleOffer SingleOffer { get; set; } public int KVCalculationsForPersonId { get; set; } public virtual KVCalculationsForPerson CaculationsForPerson { get; set; } } public class KVSingleOffer { public KVSingleOffer() { } public int KVSingleOfferId { get; set; } public string KVSingleOfferName { get; set; } public KVCalculationWish CalculationWish { get; set; } } public class KVCalculationsForPerson { public KVCalculationsForPerson() { } public int KVCalculationsForPersonId { get; set; } public string KVCalculationsForPersonName { get; set; } public KVCalculationWish CalculationWish { get; set; } } public class EntiyRelation : DbContext { public EntiyRelation() { } public DbSet<KVCalculationWish> CalculationWish { get; set; } public DbSet<KVSingleOffer> SingleOffer { get; set; } public DbSet<KVCalculationsForPerson> CalculationsForPerson { get; set; } protected override void OnModelCreating(System.Data.Entity.ModelConfiguration.ModelBuilder modelBuilder) { base.OnModelCreating(modelBuilder); modelBuilder.Entity<KVCalculationWish>().HasOptional(m => m.SingleOffer).WithRequired(p => p.CalculationWish); modelBuilder.Entity<KVCalculationWish>().HasOptional(m => m.CaculationsForPerson).WithRequired(p => p.CalculationWish); } } i want to use KVCalcuationWish object in KVCalcuationsForPerson and KVSingleOffer class. So when i am creating object of KVCalcuationForPerson and KVSingleOffer class i initialize both object with New KVCalcuationWish object. like this KVCalculationsForPerson calcPerson = new KVCalculationsForPerson(); KVCalculationWish wish = new KVCalculationWish() { CaculationsForPerson = calcPerson }; calcPerson.KVCalculationsForPersonName = "Person Name"; calcPerson.CalculationWish = wish; KVSingleOffer singleOffer = new KVSingleOffer(); KVCalculationWish wish1 = new KVCalculationWish() { SingleOffer = singleOffer }; singleOffer.KVSingleOfferName = "Offer Name"; singleOffer.CalculationWish = wish1; but my problem is when i save this records using following code try { db.CalculationsForPerson.Add(calcPerson); db.SingleOffer.Add(singleOffer); db.SaveChanges(); } catch (Exception ex) { } i can save successfully in DB, but in Table KVCalcuationWish i am not able to get the ID of SingleOffer and CalcuationsForPerson class object. Following is the data of KVCalcuationWish table. KVCalcuationWishID KVCalcuationWishName KVSingleOfferID KVCalcuationsForPersonID 1 NULL 0 0 Following is the data of KVSingleOFfer Table KVSingleOfferID KVSingleOfferName 1 Offer Name Follwing is the data of KVCalcuationsForPerson Table KVSingleOfferID KVSingleOfferName 1 Person Name I want to have following possible output in KVCalcuationWish table. KVCalcuationWishID KVCalcuationWishName KVSingleOfferID KVCalcuationsForPersonID 1 NULL 1 NULL 2 NULL NULL 1 so what i want to achieve is ...... when i am save KVSingleOffer object i want separate record to be inserted and when i save KVCalcuationsForPerson object another separate record should be save to KVCalcuationwish table. Is that possible? Sorry for long description... but i really hang on this situation... Thanks & Regards, Joyous Suhas

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  • Programmatically measure size and way-order of L1 and L2 caches

    - by osgx
    How can I measure programmatically (not query the OS, but measure) the size and order of associativity of L1 and L2 caches (data caches)? Assumptions about system: It has L1 and L2 cache (may be L3 too, may be cache sharing), It may have a hardware prefetch unit (just like P4+), It has a stable clocksource (tickcounter or good HPET for gettimeofday). There are no assumptions about OS (it can be Linux, Windows, or something non-standard), and we can't use POSIX queries. Language is C. And compiler optimizations may be disabled.

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  • Programicaly measure size and way-order of L1 and L2 caches

    - by osgx
    Hello How can I measure programicaly (not query the OS, but measure) the size and order of associativity of L1 and L2 caches (data caches)? Assumtions about system: It has L1 and L2 cache (may be L3 too, may be cache sharing), It may have a hardware prefetch unit (just like P4+), it has a stable clocksource (tickcounter or good HPET for gettimeofday). There are no assumtions about OS (it can be Linux, Windows, smth non-standart), and we can't use posix queries. Language is C. And Compiler optimizations may be disabled.

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  • Drupal CCK Date: how to set datetime field's default value to a fix date?

    - by Daj pan spokój
    Hi, I have a CCK datetime field and would like to set its default value to 31 May 2011. When I go to the configuration of the field I can set the default value to Now, Blank or Relative. Relative is to be set by a PHP's strtotime argument. However, it fails when I set it to 31 May 2011 last day of May 2011 (that should normally work according to http://php.net/manual/en/function.strtotime.php) Do You have any idea how to set it to default to 31 May 2011?

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  • VB Script and filename with space

    - by Ram
    Hi I wrote a VBS file to open the "6 May" folder with following content path = "F:\Test\2010\May\6 May" Set Sh = CreateObject("WSCript.Shell") Sh.Run ""path"",3,True Set Sh = Nothing However on executing this I am getting following error Windows Script Host Script: F:\Sperry\2010\May_06 May\open.vbs Line: 4 Char: 10 Error: Expected end of statement Code: 800A0401 Source: Microsoft VBScript compilation error OK Can anyone help me in this?

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  • [MySQL Query] How to limit date?

    - by rasouza
    I'd like to select all entries from a table where date is the last one and only those ones. For example: today is May 16th, the last entries I have from my table is dated from May 15th, but I have older ones (May 14th, May13th, etc). I'd like to select only the dated from May 15th, but it's not this specific date, I need to select every entry dated from the last date I have in my database. How to? Thx in advance

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  • Oracle Support Master Note for Troubleshooting Advanced Queuing and Oracle Streams Propagation Issues (Doc ID 233099.1)

    - by faye.todd(at)oracle.com
    Master Note for Troubleshooting Advanced Queuing and Oracle Streams Propagation Issues (Doc ID 233099.1) Copyright (c) 2010, Oracle Corporation. All Rights Reserved. In this Document  Purpose  Last Review Date  Instructions for the Reader  Troubleshooting Details     1. Scope and Application      2. Definitions and Classifications     3. How to Use This Guide     4. Basic AQ Propagation Troubleshooting     5. Additional Troubleshooting Steps for AQ Propagation of User-Enqueued and Dequeued Messages     6. Additional Troubleshooting Steps for Propagation in an Oracle Streams Environment     7. Performance Issues  References Applies to: Oracle Server - Enterprise Edition - Version: 8.1.7.0 to 11.2.0.2 - Release: 8.1.7 to 11.2Information in this document applies to any platform. Purpose This document presents a step-by-step methodology for troubleshooting and resolving problems with Advanced Queuing Propagation in both Streams and basic Advanced Queuing environments. It also serves as a master reference for other more specific notes on Oracle Streams Propagation and Advanced Queuing Propagation issues. Last Review Date December 20, 2010 Instructions for the Reader A Troubleshooting Guide is provided to assist in debugging a specific issue. When possible, diagnostic tools are included in the document to assist in troubleshooting. Troubleshooting Details 1. Scope and Application This note is intended for Database Administrators of Oracle databases where issues are being encountered with propagating messages between advanced queues, whether the queues are used for user-created messaging systems or for Oracle Streams. It contains troubleshooting steps and links to notes for further problem resolution.It can also be used a template to document a problem when it is necessary to engage Oracle Support Services. Knowing what is NOT happening can frequently speed up the resolution process by focusing solely on the pertinent problem area. This guide is divided into five parts: Section 2: Definitions and Classifications (discusses the different types and features of propagations possible - helpful for understanding the rest of the guide) Section 3: How to Use this Guide (to be used as a start part for determining the scope of the problem and what sections to consult) Section 4. Basic AQ propagation troubleshooting (applies to both AQ propagation of user enqueued and dequeued messages as well as Oracle Streams propagations) Section 5. Additional troubleshooting steps for AQ propagation of user enqueued and dequeued messages Section 6. Additional troubleshooting steps for Oracle Streams propagation Section 7. Performance issues 2. Definitions and Classifications Given the potential scope of issues that can be encountered with AQ propagation, the first recommended step is to do some basic diagnosis to determine the type of problem that is being encountered. 2.1. What Type of Propagation is Being Used? 2.1.1. Buffered Messaging For an advanced queue, messages can be maintained on disk (persistent messaging) or in memory (buffered messaging). To determine if a queue is buffered or not, reference the GV_$BUFFERED_QUEUES view. If the queue does not appear in this view, it is persistent. 2.1.2. Propagation mode - queue-to-dblink vs queue-to-queue As of 10.2, an AQ propagation can also be defined as queue-to-dblink, or queue-to-queue: queue-to-dblink: The propagation delivers messages or events from the source queue to all subscribing queues at the destination database identified by the dblink. A single propagation schedule is used to propagate messages to all subscribing queues. Hence any changes made to this schedule will affect message delivery to all the subscribing queues. This mode does not support multiple propagations from the same source queue to the same target database. queue-to-queue: Added in 10.2, this propagation mode delivers messages or events from the source queue to a specific destination queue identified on the database link. This allows the user to have fine-grained control on the propagation schedule for message delivery. This new propagation mode also supports transparent failover when propagating to a destination Oracle RAC system. With queue-to-queue propagation, you are no longer required to re-point a database link if the owner instance of the queue fails on Oracle RAC. This mode supports multiple propagations to the same target database if the target queues are different. The default is queue-to-dblink. To verify if queue-to-queue propagation is being used, in non-Streams environments query DBA_QUEUE_SCHEDULES.DESTINATION - if a remote queue is listed along with the remote database link, then queue-to-queue propagation is being used. For Streams environments, the DBA_PROPAGATION.QUEUE_TO_QUEUE column can be checked.See the following note for a method to switch between the two modes:Document 827473.1 How to alter propagation from queue-to-queue to queue-to-dblink 2.1.3. Combined Capture and Apply (CCA) for Streams In 11g Oracle Streams environments, an optimization called Combined Capture and Apply (CCA) is implemented by default when possible. Although a propagation is configured in this case, Streams does not use it; instead it passes information directly from capture to an apply receiver. To see if CCA is in use: COLUMN CAPTURE_NAME HEADING 'Capture Name' FORMAT A30COLUMN OPTIMIZATION HEADING 'CCA Mode?' FORMAT A10SELECT CAPTURE_NAME, DECODE(OPTIMIZATION,0, 'No','Yes') OPTIMIZATIONFROM V$STREAMS_CAPTURE; Also, see the following note:Document 463820.1 Streams Combined Capture and Apply in 11g 2.2. Queue Table Compatibility There are three types of queue table compatibility. In more recent databases, queue tables may be present in all three modes of compatibility: 8.0 - earliest version, deprecated in 10.2 onwards 8.1 - support added for RAC, asynchronous notification, secure queues, queue level access control, rule-based subscribers, separate storage of history information 10.0 - if the database is in 10.1-compatible mode, then the default value for queue table compatibility is 10.0 2.3. Single vs Multiple Consumer Queue Tables If more than one recipient can dequeue a message from a queue, then its queue table is multiple consumer. You can propagate messages from a multiple-consumer queue to a single-consumer queue. Propagation from a single-consumer queue to a multiple-consumer queue is not possible. 3. How to Use This Guide 3.1. Are Messages Being Propagated at All, or is the Propagation Just Slow? Run the following query on the source database for the propagation (assuming that it is running): select TOTAL_NUMBER from DBA_QUEUE_SCHEDULES where QNAME='<source_queue_name>'; If TOTAL_NUMBER is increasing, then propagation is most likely functioning, although it may be slow. For performance issues, see Section 7. 3.2. Propagation Between Persistent User-Created Queues See Sections 4 and 5 (and optionally Section 6 if performance is an issue). 3.3. Propagation Between Buffered User-Created Queues See Sections 4, 5, and 6 (and optionally Section 7 if performance is an issue). 3.4. Propagation between Oracle Streams Queues (without Combined Capture and Apply (CCA) Optimization) See Sections 4 and 6 (and optionally Section 7 if performance is an issue). 3.5. Propagation between Oracle Streams Queues (with Combined Capture and Apply (CCA) Optimization) Although an AQ propagation is not used directly in this case, some characteristics of the message transfer are inferred from the propagation parameters used. Some parts of Sections 4 and 6 still apply. 3.6. Messaging Gateway Propagations This note does not apply to Messaging Gateway propagations. 4. Basic AQ Propagation Troubleshooting 4.1. Double-check Your Code Make sure that you are consistent in your usage of the database link(s) names, queue names, etc. It may be useful to plot a diagram of which queues are connected via which database links to make sure that the logical structure is correct. 4.2. Verify that Job Queue Processes are Running 4.2.1. Versions 10.2 and Lower - DBA_JOBS Package For versions 10.2 and lower, a scheduled propagation is managed by DBMS_JOB package. The propagation is performed by job queue process background processes. Therefore we need to verify that there are sufficient processes available for the propagation process. We should have at least 4 job queue processes running and preferably more depending on the number of other jobs running in the database. It should be noted that for AQ specific work, AQ will only ever use half of the job queue processes available.An issue caused by an inadequate job queue processes parameter setting is described in the following note:Document 298015.1 Kwqjswproc:Excep After Loop: Assigning To Self 4.2.1.1. Job Queue Processes in Initalization Parameter File The parameter JOB_QUEUE_PROCESSES in the init.ora/spfile should be > 0. The value can be changed dynamically via connect / as sysdbaalter system set JOB_QUEUE_PROCESSES=10; 4.2.1.2. Job Queue Processes in Memory The following command will show how many job queue processes are currentlyin use by this instance (this may be different than what is in the init.ora/spfile): connect / as sysdbashow parameter job; 4.2.1.3. OS PIDs Corresponding to Job Queue Processes Identify the operating system process ids (spids) of job queue processes involved in propagation via select p.SPID, p.PROGRAM from V$PROCESS p, DBA_JOBS_RUNNING jr, V$SESSION s, DBA_JOBS j where s.SID=jr.SID and s.PADDR=p.ADDR and jr.JOB=j.JOBand j.WHAT like '%sys.dbms_aqadm.aq$_propaq(job)%'; and these SPIDs can be used to check at the operating system level that they exist.In 8i a job queue process will have a name similar to: ora_snp1_<instance_name>.In 9i onwards you will see a coordinator process: ora_cjq0_ and multiple slave processes: ora_jnnn_<instance_name>, where nnn is an integer between 1 and 999. 4.2.2. Version 11.1 and Above - Oracle Scheduler In version 11.1 and above, Oracle Scheduler is used to perform AQ and Streams propagations. Oracle Scheduler automatically tunes the number of slave processes for these jobs based on the load on the computer system, and the JOB_QUEUE_PROCESSES initialization parameter is only used to specify the maximum number of slave processes. Therefore, the JOB_QUEUE_PROCESSES initialization parameter does not need to be set (it defaults to a very high number), unless you want to limit the number of slaves that can be created. If JOB_QUEUE_PROCESSES = 0, no propagation jobs will run.See the following note for a discussion of Oracle Streams 11g and Oracle Scheduler:Document 1083608.1 11g Streams and Oracle Scheduler 4.2.2.1. Job Queue Processes in Initalization Parameter File The parameter JOB_QUEUE_PROCESSES in the init.ora/spfile should be > 0, and preferably be left at its default value. The value can be changed dynamically via connect / as sysdbaalter system set JOB_QUEUE_PROCESSES=10; To set the JOB_QUEUE_PROCESSES parameter to its default value, run: connect / as sysdbaalter system reset JOB_QUEUE_PROCESSES; and then bounce the instance. 4.2.2.2. Job Queue Processes in Memory The following command will show how many job queue processes are currently in use by this instance (this may be different than what is in the init.ora/spfile): connect / as sysdbashow parameter job; 4.2.2.3. OS PIDs Corresponding to Job Queue Processes Identify the operating system process ids (SPIDs) of job queue processes involved in propagation via col PROGRAM for a30select p.SPID, p.PROGRAM, j.JOB_namefrom v$PROCESS p, DBA_SCHEDULER_RUNNING_JOBS jr, V$SESSION s, DBA_SCHEDULER_JOBS j where s.SID=jr.SESSION_ID and s.PADDR=p.ADDRand jr.JOB_name=j.JOB_NAME and j.JOB_NAME like '%AQ_JOB$_%'; and these SPIDs can be used to check at the operating system level that they exist.You will see a coordinator process: ora_cjq0_ and multiple slave processes: ora_jnnn_<instance_name>, where nnn is an integer between 1 and 999. 4.3. Check the Alert Log and Any Associated Trace Files The first place to check for propagation failures is the alert logs at all sites (local and if relevant all remote sites). When a job queue process attempts to execute a schedule and fails it will always write an error stack to the alert log. This error stack will also be written in a job queue process trace file, which will be written to the BACKGROUND_DUMP_DEST location for 10.2 and below, and in the DIAGNOSTIC_DEST location for 11g. The fact that errors are written to the alert log demonstrates that the schedule is executing. This means that the problem could be with the set up of the schedule. In this example the ORA-02068 demonstrates that the failure was at the remote site. Further investigation revealed that the remote database was not open, hence the ORA-03114 error. Starting the database resolved the problem. Thu Feb 14 10:40:05 2002 Propagation Schedule for (AQADM.MULTIPLEQ, SHANE816.WORLD) encountered following error:ORA-04052: error occurred when looking up Remote object [email protected]: error occurred at recursive SQL level 4ORA-02068: following severe error from SHANE816ORA-03114: not connected to ORACLEORA-06512: at "SYS.DBMS_AQADM_SYS", line 4770ORA-06512: at "SYS.DBMS_AQADM", line 548ORA-06512: at line 1 Other potential errors that may be written to the alert log can be found in the following notes:Document 827184.1 AQ Propagation with CLOB data types Fails with ORA-22990 (11.1)Document 846297.1 AQ Propagation Fails : ORA-00600[kope2upic2954] or Ora-00600[Kghsstream_copyn] (10.2, 11.1)Document 731292.1 ORA-25215 Reported on Local Propagation When Using Transformation with ANYDATA queue tables (10.2, 11.1, 11.2)Document 365093.1 ORA-07445 [kwqppay2aqe()+7360] Reported on Propagation of a Transformed Message (10.1, 10.2)Document 219416.1 Advanced Queuing Propagation Fails with ORA-22922 (9.0)Document 1203544.1 AQ Propagation Aborted with ORA-600 [ociksin: invalid status] on SYS.DBMS_AQADM_SYS.AQ$_PROPAGATION_PROCEDURE After Upgrade (11.1, 11.2)Document 1087324.1 ORA-01405 ORA-01422 reported by Advanced Queuing Propagation schedules after RAC reconfiguration (10.2)Document 1079577.1 Advanced Queuing Propagation Fails With "ORA-22370 incorrect usage of method" (9.2, 10.2, 11.1, 11.2)Document 332792.1 ORA-04061 error relating to SYS.DBMS_PRVTAQIP reported when setting up Statspack (8.1, 9.0, 9.2, 10.1)Document 353325.1 ORA-24056: Internal inconsistency for QUEUE <queue_name> and destination <dblink> (8.1, 9.0, 9.2, 10.1, 10.2, 11.1, 11.2)Document 787367.1 ORA-22275 reported on Propagating Messages with LOB component when propagating between 10.1 and 10.2 (10.1, 10.2)Document 566622.1 ORA-22275 when propagating >4K AQ$_JMS_TEXT_MESSAGEs from 9.2.0.8 to 10.2.0.1 (9.2, 10.1)Document 731539.1 ORA-29268: HTTP client error 401 Unauthorized Error when the AQ Servlet attempts to Propagate a message via HTTP (9.0, 9.2, 10.1, 10.2, 11.1)Document 253131.1 Concurrent Writes May Corrupt LOB Segment When Using Auto Segment Space Management (ORA-1555) (9.2)Document 118884.1 How to unschedule a propagation schedule stuck in pending stateDocument 222992.1 DBMS_AQADM.DISABLE_PROPAGATION_SCHEDULE Returns ORA-24082Document 282987.1 Propagated Messages marked UNDELIVERABLE after Drop and Recreate Of Remote QueueDocument 1204080.1 AQ Propagation Failing With ORA-25329 After Upgraded From 8i or 9i to 10g or 11g.Document 1233675.1 AQ Propagation stops after upgrade to 11.2.0.1 ORA-30757 4.3.1. Errors Related to Incorrect Network Configuration The most common propagation errors result from an incorrect network configuration. The list below contains common errors caused by tnsnames.ora file or database links being configured incorrectly: - ORA-12154: TNS:could not resolve service name- ORA-12505: TNS:listener does not currently know of SID given in connect descriptor- ORA-12514: TNS:listener could not resolve SERVICE_NAME - ORA-12541: TNS-12541 TNS:no listener 4.4. Check the Database Links Exist and are Functioning Correctly For schedules to remote databases confirm the database link exists via. SQL> col DBLINK for a45SQL> select QNAME, NVL(REGEXP_SUBSTR(DESTINATION, '[^@]+', 1, 2), DESTINATION) dblink2 from DBA_QUEUE_SCHEDULES3 where MESSAGE_DELIVERY_MODE = 'PERSISTENT';QNAME DBLINK------------------------------ ---------------------------------------------MY_QUEUE ORCL102B.WORLD Connect as the owner of the link and select across it to verify it works and connects to the database we expect. i.e. select * from ALL_QUEUES@ ORCL102B.WORLD; You need to ensure that the userid that scheduled the propagation (using DBMS_AQADM.SCHEDULE_PROPAGATION or DBMS_PROPAGATION_ADM.CREATE_PROPAGATION if using Streams) has access to the database link for the destination. 4.5. Has Propagation Been Correctly Scheduled? Check that the propagation schedule has been created and that a job queue process has been assigned. Look for the entry in DBA_QUEUE_SCHEDULES and SYS.AQ$_SCHEDULES for your schedule. For 10g and below, check that it has a JOBNO entry in SYS.AQ$_SCHEDULES, and that there is an entry in DBA_JOBS with that JOBNO. For 11g and above, check that the schedule has a JOB_NAME entry in SYS.AQ$_SCHEDULES, and that there is an entry in DBA_SCHEDULER_JOBS with that JOB_NAME. Check the destination is as intended and spelled correctly. SQL> select SCHEMA, QNAME, DESTINATION, SCHEDULE_DISABLED, PROCESS_NAME from DBA_QUEUE_SCHEDULES;SCHEMA QNAME DESTINATION S PROCESS------- ---------- ------------------ - -----------AQADM MULTIPLEQ AQ$_LOCAL N J000 AQ$_LOCAL in the destination column shows that the queue to which we are propagating to is in the same database as the source queue. If the propagation was to a remote (different) database, a database link will be in the DESTINATION column. The entry in the SCHEDULE_DISABLED column, N, means that the schedule is NOT disabled. If Y (yes) appears in this column, propagation is disabled and the schedule will not be executed. If not using Oracle Streams, propagation should resume once you have enabled the schedule by invoking DBMS_AQADM.ENABLE_PROPAGATION_SCHEDULE (for 10.2 Oracle Streams and above, the DBMS_PROPAGATION_ADM.START_PROPAGATION procedure should be used). The PROCESS_NAME is the name of the job queue process currently allocated to execute the schedule. This process is allocated dynamically at execution time. If the PROCESS_NAME column is null (empty) the schedule is not currently executing. You may need to execute this statement a number of times to verify if a process is being allocated. If a process is at some time allocated to the schedule, it is attempting to execute. SQL> select SCHEMA, QNAME, LAST_RUN_DATE, NEXT_RUN_DATE from DBA_QUEUE_SCHEDULES;SCHEMA QNAME LAST_RUN_DATE NEXT_RUN_DATE------ ----- ----------------------- ----------------------- AQADM MULTIPLEQ 13-FEB-2002 13:18:57 13-FEB-2002 13:20:30 In 11g, these dates are expressed in TIMESTAMP WITH TIME ZONE datatypes. If the NEXT_RUN_DATE and NEXT_RUN_TIME columns are null when this statement is executed, the scheduled propagation is currently in progress. If they never change it would suggest that the schedule itself is never executing. If the next scheduled execution is too far away, change the NEXT_TIME parameter of the schedule so that schedules are executed more frequently (assuming that the window is not set to be infinite). Parameters of a schedule can be changed using the DBMS_AQADM.ALTER_PROPAGATION_SCHEDULE call. In 10g and below, scheduling propagation posts a job in the DBA_JOBS view. The columns are more or less the same as DBA_QUEUE_SCHEDULES so you just need to recognize the job and verify that it exists. SQL> select JOB, WHAT from DBA_JOBS where WHAT like '%sys.dbms_aqadm.aq$_propaq(job)%';JOB WHAT---- ----------------- 720 next_date := sys.dbms_aqadm.aq$_propaq(job); For 11g, scheduling propagation posts a job in DBA_SCHEDULER_JOBS instead: SQL> select JOB_NAME from DBA_SCHEDULER_JOBS where JOB_NAME like 'AQ_JOB$_%';JOB_NAME------------------------------AQ_JOB$_41 If no job exists, check DBA_QUEUE_SCHEDULES to make sure that the schedule has not been disabled. For 10g and below, the job number is dynamic for AQ propagation schedules. The procedure that is executed to expedite a propagation schedule runs, removes itself from DBA_JOBS, and then reposts a new job for the next scheduled propagation. The job number should therefore always increment unless the schedule has been set up to run indefinitely. 4.6. Is the Schedule Executing but Failing to Complete? Run the following query: SQL> select FAILURES, LAST_ERROR_MSG from DBA_QUEUE_SCHEDULES;FAILURES LAST_ERROR_MSG------------ -----------------------1 ORA-25207: enqueue failed, queue AQADM.INQ is disabled from enqueueingORA-02063: preceding line from SHANE816 The failures column shows how many times we have attempted to execute the schedule and failed. Oracle will attempt to execute the schedule 16 times after which it will be removed from the DBA_JOBS or DBA_SCHEDULER_JOBS view and the schedule will become disabled. The column DBA_QUEUE_SCHEDULES.SCHEDULE_DISABLED will show 'Y'. For 11g and above, the DBA_SCHEDULER_JOBS.STATE column will show 'BROKEN' for the job corresponding to DBA_QUEUE_SCHEDULES.JOB_NAME. Prior to 10g the back off algorithm for failures was exponential, whereas from 10g onwards it is linear. The propagation will become disabled on the 17th attempt. Only the last execution failure will be reflected in the LAST_ERROR_MSG column. That is, if the schedule fails 5 times for 5 different reasons, only the last set of errors will be recorded in DBA_QUEUE_SCHEDULES. Any errors need to be resolved to allow propagation to continue. If propagation has also become disabled due to 17 failures, first resolve the reason for the error and then re-enable the schedule using the DBMS_AQADM.ENABLE_PROPAGATION_SCHEDULE procedure, or DBMS_PROPAGATION_ADM.START_PROPAGATION if using 10.2 or above Oracle Streams. As soon as the schedule executes successfully the error message entries will be deleted. Oracle does not keep a history of past failures. However, when using Oracle Streams, the errors will be retained in the DBA_PROPAGATION view even after the schedule resumes successfully. See the following note for instructions on how to clear out the errors from the DBA_PROPAGATION view:Document 808136.1 How to clear the old errors from DBA_PROPAGATION view?If a schedule is active and no errors are being reported then the source queue may not have any messages to be propagated. 4.7. Do the Propagation Notification Queue Table and Queue Exist? Check to see that the propagation notification queue table and queue exist and are enabled for enqueue and dequeue. Propagation makes use of the propagation notification queue for handling propagation run-time events, and the messages in this queue are stored in a SYS-owned queue table. This queue should never be stopped or dropped and the corresponding queue table never be dropped. 10g and belowThe propagation notification queue table is of the format SYS.AQ$_PROP_TABLE_n, where 'n' is the RAC instance number, i.e. '1' for a non-RAC environment. This queue and queue table are created implicitly when propagation is first scheduled. If propagation has been scheduled and these objects do not exist, try unscheduling and rescheduling propagation. If they still do not exist contact Oracle Support. SQL> select QUEUE_TABLE from DBA_QUEUE_TABLES2 where QUEUE_TABLE like '%PROP_TABLE%' and OWNER = 'SYS';QUEUE_TABLE------------------------------AQ$_PROP_TABLE_1SQL> select NAME, ENQUEUE_ENABLED, DEQUEUE_ENABLED2 from DBA_QUEUES where owner='SYS'3 and QUEUE_TABLE like '%PROP_TABLE%';NAME ENQUEUE DEQUEUE------------------------------ ------- -------AQ$_PROP_NOTIFY_1 YES YESAQ$_AQ$_PROP_TABLE_1_E NO NO If the AQ$_PROP_NOTIFY_1 queue is not enabled for enqueue or dequeue, it should be so enabled using DBMS_AQADM.START_QUEUE. However, the exception queue AQ$_AQ$_PROP_TABLE_1_E should not be enabled for enqueue or dequeue.11g and aboveThe propagation notification queue table is of the format SYS.AQ_PROP_TABLE, and is created when the database is created. If they do not exist, contact Oracle Support. SQL> select QUEUE_TABLE from DBA_QUEUE_TABLES2 where QUEUE_TABLE like '%PROP_TABLE%' and OWNER = 'SYS';QUEUE_TABLE------------------------------AQ_PROP_TABLESQL> select NAME, ENQUEUE_ENABLED, DEQUEUE_ENABLED2 from DBA_QUEUES where owner='SYS'3 and QUEUE_TABLE like '%PROP_TABLE%';NAME ENQUEUE DEQUEUE------------------------------ ------- -------AQ_PROP_NOTIFY YES YESAQ$_AQ_PROP_TABLE_E NO NO If the AQ_PROP_NOTIFY queue is not enabled for enqueue or dequeue, it should be so enabled using DBMS_AQADM.START_QUEUE. However, the exception queue AQ$_AQ$_PROP_TABLE_E should not be enabled for enqueue or dequeue. 4.8. Does the Remote Queue Exist and is it Enabled for Enqueueing? Check that the remote queue the propagation is transferring messages to exists and is enabled for enqueue: SQL> select DESTINATION from USER_QUEUE_SCHEDULES where QNAME = 'OUTQ';DESTINATION-----------------------------------------------------------------------------"AQADM"."INQ"@M2V102.ESSQL> select OWNER, NAME, ENQUEUE_ENABLED, DEQUEUE_ENABLED from [email protected];OWNER NAME ENQUEUE DEQUEUE-------- ------ ----------- -----------AQADM INQ YES YES 4.9. Do the Target and Source Database Charactersets Differ? If a message fails to propagate, check the database charactersets of the source and target databases. Investigate whether the same message can propagate between the databases with the same characterset or it is only a particular combination of charactersets which causes a problem. 4.10. Check the Queue Table Type Agreement Propagation is not possible between queue tables which have types that differ in some respect. One way to determine if this is the case is to run the DBMS_AQADM.VERIFY_QUEUE_TYPES procedure for the two queues that the propagation operates on. If the types do not agree, DBMS_AQADM.VERIFY_QUEUE_TYPES will return '0'.For AQ propagation between databases which have different NLS_LENGTH_SEMANTICS settings, propagation will not work, unless the queues are Oracle Streams ANYDATA queues.See the following notes for issues caused by lack of type agreement:Document 1079577.1 Advanced Queuing Propagation Fails With "ORA-22370: incorrect usage of method"Document 282987.1 Propagated Messages marked UNDELIVERABLE after Drop and Recreate Of Remote QueueDocument 353754.1 Streams Messaging Propagation Fails between Single and Multi-byte Charactersets when using Chararacter Length Semantics in the ADT 4.11. Enable Propagation Tracing 4.11.1. System Level This is set it in the init.ora/spfile as follows: event="24040 trace name context forever, level 10" and restart the instanceThis event cannot be set dynamically with an alter system command until version 10.2: SQL> alter system set events '24040 trace name context forever, level 10'; To unset the event: SQL> alter system set events '24040 trace name context off'; Debugging information will be logged to job queue trace file(s) (jnnn) as propagation takes place. You can check the trace file for errors, and for statements indicating that messages have been sent. For the most part the trace information is understandable. This trace should also be uploaded to Oracle Support if a service request is created. 4.11.2. Attaching to a Specific Process We can also attach to an existing job queue processes that is running a propagation schedule and trace it individually using the oradebug utility, as follows:10.2 and below connect / as sysdbaselect p.SPID, p.PROGRAM from v$PROCESS p, DBA_JOBS_RUNNING jr, V$SESSION s, DBA_JOBS j where s.SID=jr.SID and s.PADDR=p.ADDR and jr.JOB=j.JOB and j.WHAT like '%sys.dbms_aqadm.aq$_propaq(job)%';-- For the process id (SPID) attach to it via oradebug and generate the following traceoradebug setospid <SPID>oradebug unlimitoradebug Event 10046 trace name context forever, level 12oradebug Event 24040 trace name context forever, level 10-- Trace the process for 5 minutesoradebug Event 10046 trace name context offoradebug Event 24040 trace name context off-- The following command returns the pathname/filename to the file being written tooradebug tracefile_name 11g connect / as sysdbacol PROGRAM for a30select p.SPID, p.PROGRAM, j.JOB_NAMEfrom v$PROCESS p, DBA_SCHEDULER_RUNNING_JOBS jr, V$SESSION s, DBA_SCHEDULER_JOBS j where s.SID=jr.SESSION_ID and s.PADDR=p.ADDR and jr.JOB_NAME=j.JOB_NAME and j.JOB_NAME like '%AQ_JOB$_%';-- For the process id (SPID) attach to it via oradebug and generate the following traceoradebug setospid <SPID>oradebug unlimitoradebug Event 10046 trace name context forever, level 12oradebug Event 24040 trace name context forever, level 10-- Trace the process for 5 minutesoradebug Event 10046 trace name context offoradebug Event 24040 trace name context off-- The following command returns the pathname/filename to the file being written tooradebug tracefile_name 4.11.3. Further Tracing The previous tracing steps only trace the job queue process executing the propagation on the source. At times it is useful to trace the propagation receiver process (the session which is enqueueing the messages into the target queue) on the target database which is associated with the job queue process on the source database.These following queries provide ways of identifying the processes involved in propagation so that you can attach to them via oradebug to generate trace information.In order to identify the propagation receiver process you need to execute the query as a user with privileges to access the v$ views in both the local and remote databases so the database link must connect as a user with those privileges in the remote database. The <DBLINK> in the queries should be replaced by the appropriate database link.The queries have two forms due to the differences between operating systems. The value returned by 'Rem Process' is the operating system identifier of the propagation receiver on the remote database. Once identified, this process can be attached to and traced on the remote database using the commands given in Section 4.11.2.10.2 and below - Windows select pl.SPID "JobQ Process", pl.PROGRAM, sr.PROCESS "Rem Process" from v$PROCESS pl, DBA_JOBS_RUNNING jr, V$SESSION s, DBA_JOBS j, V$SESSION@<DBLINK> sr where s.SID=jr.SID and s.PADDR=pl.ADDR and jr.JOB=j.JOB and j.WHAT like '%sys.dbms_aqadm.aq$_propaq(job)%' and pl.SPID=substr(sr.PROCESS, instr(sr.PROCESS,':')+1); 10.2 and below - Unix select pl.SPID "JobQ Process", pl.PROGRAM, sr.PROCESS "Rem Process" from V$PROCESS pl, DBA_JOBS_RUNNING jr, V$SESSION s, DBA_JOBS j, V$SESSION@<DBLINK> sr where s.SID=jr.SID and s.PADDR=pl.ADDR and jr.JOB=j.JOB and j.WHAT like '%sys.dbms_aqadm.aq$_propaq(job)%' and pl.SPID=sr.PROCESS; 11g - Windows select pl.SPID "JobQ Process", pl.PROGRAM, sr.PROCESS "Rem Process" from V$PROCESS pl, DBA_SCHEDULER_RUNNING_JOBS jr, V$SESSION s, DBA_SCHEDULER_JOBS j, V$SESSION@<DBLINK> sr where s.SID=jr.SESSION_ID and s.PADDR=pl.ADDR and jr.JOB_NAME=j.JOB_NAME and j.JOB_NAME like '%AQ_JOB$_%%' and pl.SPID=substr(sr.PROCESS, instr(sr.PROCESS,':')+1); 11g - Unix select pl.SPID "JobQ Process", pl.PROGRAM, sr.PROCESS "Rem Process" from V$PROCESS pl, DBA_SCHEDULER_RUNNING_JOBS jr, V$SESSION s, DBA_SCHEDULER_JOBS j, V$SESSION@<DBLINK> sr where s.SID=jr.SESSION_ID and s.PADDR=pl.ADDR and jr.JOB_NAME=j.JOB_NAME and j.JOB_NAME like '%AQ_JOB$_%%' and pl.SPID=sr.PROCESS;   5. Additional Troubleshooting Steps for AQ Propagation of User-Enqueued and Dequeued Messages 5.1. Check the Privileges of All Users Involved Ensure that the owner of the database link has the necessary privileges on the aq packages. SQL> select TABLE_NAME, PRIVILEGE from USER_TAB_PRIVS;TABLE_NAME PRIVILEGE------------------------------ ----------------------------------------DBMS_LOCK EXECUTEDBMS_AQ EXECUTEDBMS_AQADM EXECUTEDBMS_AQ_BQVIEW EXECUTEQT52814_BUFFER SELECT Note that when queue table is created, a view called QT<nnn>_BUFFER is created in the SYS schema, and the queue table owner is given SELECT privileges on it. The <nnn> corresponds to the object_id of the associated queue table. SQL> select * from USER_ROLE_PRIVS;USERNAME GRANTED_ROLE ADM DEF OS_------------------------------ ------------------------------ ---- ---- ---AQ_USER1 AQ_ADMINISTRATOR_ROLE NO YES NOAQ_USER1 CONNECT NO YES NOAQ_USER1 RESOURCE NO YES NO It is good practice to configure central AQ administrative user. All admin and processing jobs are created, executed and administered as this user. This configuration is not mandatory however, and the database link can be owned by any existing queue user. If this latter configuration is used, ensure that the connecting user has the necessary privileges on the AQ packages and objects involved. Privileges for an AQ Administrative user Execute on DBMS_AQADM Execute on DBMS_AQ Granted the AQ_ADMINISTRATOR_ROLE Privileges for an AQ user Execute on DBMS_AQ Execute on the message payload Enqueue privileges on the remote queue Dequeue privileges on the originating queue Privileges need to be confirmed on both sites when propagation is scheduled to remote destinations. Verify that the user ID used to login to the destination through the database link has been granted privileges to use AQ. 5.2. Verify Queue Payload Types AQ will not propagate messages from one queue to another if the payload types of the two queues are not verified to be equivalent. An AQ administrator can verify if the source and destination's payload types match by executing the DBMS_AQADM.VERIFY_QUEUE_TYPES procedure. The results of the type checking will be stored in the SYS.AQ$_MESSAGE_TYPES table. This table can be accessed using the object identifier OID of the source queue and the address database link of the destination queue, i.e. [schema.]queue_name[@destination]. Prior to Oracle 9i the payload (message type) had to be the same for all the queue tables involved in propagation. From Oracle9i onwards a transformation can be used so that payloads can be converted from one type to another. The following procedural call made on the source database can verify whether we can propagate between the source and the destination queue tables. connect aq_user1/[email protected] serverout onDECLARErc_value number;BEGINDBMS_AQADM.VERIFY_QUEUE_TYPES(src_queue_name => 'AQ_USER1.Q_1', dest_queue_name => 'AQ_USER2.Q_2',destination => 'dbl_aq_user2.es',rc => rc_value);dbms_output.put_line('rc_value code is '||rc_value);END;/ If propagation is possible then the return code value will be 1. If it is 0 then propagation is not possible and further investigation of the types and transformations used by and in conjunction with the queue tables is required. With regard to comparison of the types the following sql can be used to extract the DDL for a specific type with' %' changed appropriately on the source and target. This can then be compared for the source and target. SET LONG 20000 set pagesize 50 EXECUTE DBMS_METADATA.SET_TRANSFORM_PARAM(DBMS_METADATA.SESSION_TRANSFORM, 'STORAGE',false); SELECT DBMS_METADATA.GET_DDL('TYPE',t.type_name) from user_types t WHERE t.type_name like '%'; EXECUTE DBMS_METADATA.SET_TRANSFORM_PARAM(DBMS_METADATA.SESSION_TRANSFORM, 'DEFAULT'); 5.3. Check Message State and Destination The first step in this process is to identify the queue table associated with the problem source queue. Although you schedule propagation for a specific queue, most of the meta-data associated with that queue is stored in the underlying queue table. The following statement finds the queue table for a given queue (note that this is a multiple-consumer queue table). SQL> select QUEUE_TABLE from DBA_QUEUES where NAME = 'MULTIPLEQ';QUEUE_TABLE --------------------MULTIPLEQTABLE For a small amount of messages in a multiple-consumer queue table, the following query can be run: SQL> select MSG_STATE, CONSUMER_NAME, ADDRESS from AQ$MULTIPLEQTABLE where QUEUE = 'MULTIPLEQ';MSG_STATE CONSUMER_NAME ADDRESS-------------- ----------------------- -------------READY AQUSER2 [email protected] AQUSER1READY AQUSER3 AQADM.INQ In this example we see 2 messages ready to be propagated to remote queues and 1 that is not. If the address column is blank, the message is not scheduled for propagation and can only be dequeued from the queue upon which it was enqueued. The MSG_STATE column values are discussed in Document 102330.1 Advanced Queueing MSG_STATE Values and their Interpretation. If the address column has a value, the message has been enqueued for propagation to another queue. The first row in the example includes a database link (@M2V102.ES). This demonstrates that the message should be propagated to a queue at a remote database. The third row does not include a database link so will be propagated to a queue that resides on the same database as the source queue. The consumer name is the intended recipient at the target queue. Note that we are not querying the base queue table directly; rather, we are querying a view that is available on top of every queue table, AQ$<queue_table_name>.A more realistic query in an environment where the queue table contains thousands of messages is8.0.3-compatible multiple-consumer queue table and all compatibility single-consumer queue tables select count(*), MSG_STATE, QUEUE from AQ$<queue_table_name>  group by MSG_STATE, QUEUE; 8.1.3 and 10.0-compatible queue tables select count(*), MSG_STATE, QUEUE, CONSUMER_NAME from AQ$<queue_table_name>group by MSG_STATE, QUEUE, CONSUMER_NAME; For multiple-consumer queue tables, if you did not see the expected CONSUMER_NAME , check the syntax of the enqueue code and verify the recipients are declared correctly. If a recipients list is not used on enqueue, check the subscriber list in the AQ$_<queue_table_name>_S view (note that a single-consumer queue table does not have a subscriber view. This view records all members of the default subscription list which were added using the DBMS_AQADM.ADD_SUBSCRIBER procedure and also those enqueued using a recipient list. SQL> select QUEUE, NAME, ADDRESS from AQ$MULTIPLEQTABLE_S;QUEUE NAME ADDRESS---------- ----------- -------------MULTIPLEQ AQUSER2 [email protected] AQUSER1 In this example we have 2 subscribers registered with the queue. We have a local subscriber AQUSER1, and a remote subscriber AQUSER2, on the queue INQ, owned by AQADM, at M2V102.ES. Unless overridden with a recipient list during enqueue every message enqueued to this queue will be propagated to INQ at M2V102.ES.For 8.1 style and above multiple consumer queue tables, you can also check the following information at the target: select CONSUMER_NAME, DEQ_TXN_ID, DEQ_TIME, DEQ_USER_ID, PROPAGATED_MSGID from AQ$<queue_table_name> where QUEUE = '<QUEUE_NAME>'; For 8.0 style queues, if the queue table supports multiple consumers you can obtain the same information from the history column of the queue table: select h.CONSUMER, h.TRANSACTION_ID, h.DEQ_TIME, h.DEQ_USER, h.PROPAGATED_MSGIDfrom AQ$<queue_table_name> t, table(t.history) h where t.Q_NAME = '<QUEUE_NAME>'; A non-NULL TRANSACTION_ID indicates that the message was successfully propagated. Further, the DEQ_TIME indicates the time of propagation, the DEQ_USER indicates the userid used for propagation, and the PROPAGATED_MSGID indicates the message ID of the message that was enqueued at the destination. 6. Additional Troubleshooting Steps for Propagation in an Oracle Streams Environment 6.1. Is the Propagation Enabled? For a propagation job to propagate messages, the propagation must be enabled. For Streams, a special view called DBA_PROPAGATION exists to convey information about Streams propagations. If messages are not being propagated by a propagation as expected, then the propagation might not be enabled. To query for this: SELECT p.PROPAGATION_NAME, DECODE(s.SCHEDULE_DISABLED, 'Y', 'Disabled','N', 'Enabled') SCHEDULE_DISABLED, s.PROCESS_NAME, s.FAILURES, s.LAST_ERROR_MSGFROM DBA_QUEUE_SCHEDULES s, DBA_PROPAGATION pWHERE p.DESTINATION_DBLINK = NVL(REGEXP_SUBSTR(s.DESTINATION, '[^@]+', 1, 2), s.DESTINATION) AND s.SCHEMA = p.SOURCE_QUEUE_OWNER AND s.QNAME = p.SOURCE_QUEUE_NAME AND MESSAGE_DELIVERY_MODE = 'PERSISTENT' order by PROPAGATION_NAME; At times, the propagation job may become "broken" or fail to start after an error has been encountered or after a database restart. If an error is indicated by the above query, an attempt to disable the propagation and then re-enable it can be made. In the examples below, for the propagation named STRMADMIN_PROPAGATE where the queue name is STREAMS_QUEUE owned by STRMADMIN and the destination database link is ORCL2.WORLD, the commands would be:10.2 and above exec dbms_propagation_adm.stop_propagation('STRMADMIN_PROPAGATE'); exec dbms_propagation_adm.start_propagation('STRMADMIN_PROPAGATE'); If the above does not fix the problem, stop the propagation specifying the force parameter (2nd parameter on stop_propagation) as TRUE: exec dbms_propagation_adm.stop_propagation('STRMADMIN_PROPAGATE',true); exec dbms_propagation_adm.start_propagation('STRMADMIN_PROPAGATE'); The statistics for the propagation as well as any old error messages are cleared when the force parameter is set to TRUE. Therefore if the propagation schedule is stopped with FORCE set to TRUE, and upon restart there is still an error message in DBA_PROPAGATION, then the error message is current.9.2 or 10.1 exec dbms_aqadm.disable_propagation_schedule('STRMADMIN.STREAMS_QUEUE','ORCL2.WORLD'); exec dbms.aqadm.enable_propagation_schedule('STRMADMIN.STREAMS_QUEUE','ORCL2.WORLD'); If the above does not fix the problem, perform an unschedule of propagation and then schedule_propagation: exec dbms_aqadm.unschedule_propagation('STRMADMIN.STREAMS_QUEUE','ORCL2.WORLD'); exec dbms_aqadm.schedule_propagation('STRMADMIN.STREAMS_QUEUE','ORCL2.WORLD'); Typically if the error from the first query in Section 6.1 recurs after restarting the propagation as shown above, further troubleshooting of the error is needed. 6.2. Check Propagation Rule Sets and Transformations Inspect the configuration of the rules in the rule set that is associated with the propagation process to make sure that they evaluate to TRUE as expected. If not, then the object or schema will not be propagated. Remember that when a negative rule evaluates to TRUE, the specified object or schema will not be propagated. Finally inspect any rule-based transformations that are implemented with propagation to make sure they are changing the data in the intended way.The following query shows what rule sets are assigned to a propagation: select PROPAGATION_NAME, RULE_SET_OWNER||'.'||RULE_SET_NAME "Positive Rule Set",NEGATIVE_RULE_SET_OWNER||'.'||NEGATIVE_RULE_SET_NAME "Negative Rule Set"from DBA_PROPAGATION; The next two queries list the propagation rules and their conditions. The first is for the positive rule set, the second is for the negative rule set: set long 4000select rsr.RULE_SET_OWNER||'.'||rsr.RULE_SET_NAME RULE_SET ,rsr.RULE_OWNER||'.'||rsr.RULE_NAME RULE_NAME,r.RULE_CONDITION CONDITION fromDBA_RULE_SET_RULES rsr, DBA_RULES rwhere rsr.RULE_NAME = r.RULE_NAME and rsr.RULE_OWNER = r.RULE_OWNER and RULE_SET_NAME in(select RULE_SET_NAME from DBA_PROPAGATION) order by rsr.RULE_SET_OWNER, rsr.RULE_SET_NAME;   set long 4000select c.PROPAGATION_NAME, rsr.RULE_SET_OWNER||'.'||rsr.RULE_SET_NAME RULE_SET ,rsr.RULE_OWNER||'.'||rsr.RULE_NAME RULE_NAME,r.RULE_CONDITION CONDITION fromDBA_RULE_SET_RULES rsr, DBA_RULES r ,DBA_PROPAGATION cwhere rsr.RULE_NAME = r.RULE_NAME and rsr.RULE_OWNER = r.RULE_OWNER andrsr.RULE_SET_OWNER=c.NEGATIVE_RULE_SET_OWNER and rsr.RULE_SET_NAME=c.NEGATIVE_RULE_SET_NAMEand rsr.RULE_SET_NAME in(select NEGATIVE_RULE_SET_NAME from DBA_PROPAGATION) order by rsr.RULE_SET_OWNER, rsr.RULE_SET_NAME; 6.3. Determining the Total Number of Messages and Bytes Propagated As in Section 3.1, determining if messages are flowing can be instructive to see whether the propagation is entirely hung or just slow. If the propagation is not in flow control (see Section 6.5.2), but the statistics are incrementing slowly, there may be a performance issue. For Streams implementations two views are available that can assist with this that can show the number of messages sent by a propagation, as well as the number of acknowledgements being returned from the target site: the V$PROPAGATION_SENDER view at the Source site and the V$PROPAGATION_RECEIVER view at the destination site. It is helpful to query both to determine if messages are being delivered to the target. Look for the statistics to increase.Source: select QUEUE_SCHEMA, QUEUE_NAME, DBLINK,HIGH_WATER_MARK, ACKNOWLEDGEMENT, TOTAL_MSGS, TOTAL_BYTESfrom V$PROPAGATION_SENDER; Target: select SRC_QUEUE_SCHEMA, SRC_QUEUE_NAME, SRC_DBNAME, DST_QUEUE_SCHEMA, DST_QUEUE_NAME, HIGH_WATER_MARK, ACKNOWLEDGEMENT, TOTAL_MSGS from V$PROPAGATION_RECEIVER; 6.4. Check Buffered Subscribers The V$BUFFERED_SUBSCRIBERS view displays information about subscribers for all buffered queues in the instance. This view can be queried to make sure that the site that the propagation is propagating to is listed as a subscriber address for the site being propagated from: select QUEUE_SCHEMA, QUEUE_NAME, SUBSCRIBER_ADDRESS from V$BUFFERED_SUBSCRIBERS; The SUBSCRIBER_ADDRESS column will not be populated when the propagation is local (between queues on the same database). 6.5. Common Streams Propagation Errors 6.5.1. ORA-02082: A loopback database link must have a connection qualifier. This error can occur if you use the Streams Setup Wizard in Oracle Enterprise Manager without first configuring the GLOBAL_NAME for your database. 6.5.2. ORA-25307: Enqueue rate too high. Enable flow control DBA_QUEUE_SCHEDULES will display this informational message for propagation when the automatic flow control (10g feature of Streams) has been invoked.Similar to Streams capture processes, a Streams propagation process can also go into a state of 'flow control. This is an informative message that indicates flow control has been automatically enabled to reduce the rate at which messages are being enqueued into at target queue.This typically occurs when the target site is unable to keep up with the rate of messages flowing from the source site. Other than checking that the apply process is running normally on the target site, usually no action is required by the DBA. Propagation and the capture process will be resumed automatically when the target site is able to accept more messages.The following document contains more information:Document 302109.1 Streams Propagation Error: ORA-25307 Enqueue rate too high. Enable flow controlSee the following document for one potential cause of this situation:Document 1097115.1 Oracle Streams Apply Reader is in 'Paused' State 6.5.3. ORA-25315 unsupported configuration for propagation of buffered messages This error typically occurs when the target database is RAC and usually indicates that an attempt was made to propagate buffered messages with the database link pointing to an instance in the destination database which is not the owner instance of the destination queue. To resolve the problem, use queue-to-queue propagation for buffered messages. 6.5.4. ORA-600 [KWQBMCRCPTS101] after dropping / recreating propagation For cause/fixes refer to:Document 421237.1 ORA-600 [KWQBMCRCPTS101] reported by a Qmon slave process after dropping a Streams Propagation 6.5.5. Stopping or Dropping a Streams Propagation Hangs See the following note:Document 1159787.1 Troubleshooting Streams Propagation When It is Not Functioning and Attempts to Stop It Hang 6.6. Streams Propagation-Related Notes for Common Issues Document 437838.1 Streams Specific PatchesDocument 749181.1 How to Recover Streams After Dropping PropagationDocument 368912.1 Queue to Queue Propagation Schedule encountered ORA-12514 in a RAC environmentDocument 564649.1 ORA-02068/ORA-03114/ORA-03113 Errors From Streams Propagation Process - Remote Database is Available and Unschedule/Reschedule Does Not ResolveDocument 553017.1 Stream Propagation Process Errors Ora-4052 Ora-6554 From 11g To 10201Document 944846.1 Streams Propagation Fails Ora-7445 [kohrsmc]Document 745601.1 ORA-23603 'STREAMS enqueue aborted due to low SGA' Error from Streams Propagation, and V$STREAMS_CAPTURE.STATE Hanging on 'Enqueuing Message'Document 333068.1 ORA-23603: Streams Enqueue Aborted Eue To Low SGADocument 363496.1 Ora-25315 Propagating on RAC StreamsDocument 368237.1 Unable to Unschedule Propagation. Streams Queue is InvalidDocument 436332.1 dbms_propagation_adm.stop_propagation hangsDocument 727389.1 Propagation Fails With ORA-12528Document 730911.1 ORA-4063 Is Reported After Dropping Negative Prop.RulesetDocument 460471.1 Propagation Blocked by Qmon Process - Streams_queue_table / 'library cache lock' waitsDocument 1165583.1 ORA-600 [kwqpuspse0-ack] In Streams EnvironmentDocument 1059029.1 Combined Capture and Apply (CCA) : Capture aborts : ORA-1422 after schedule_propagationDocument 556309.1 Changing Propagation/ queue_to_queue : false -> true does does not work; no LCRs propagatedDocument 839568.1 Propagation failing with error: ORA-01536: space quota exceeded for tablespace ''Document 311021.1 Streams Propagation Process : Ora 12154 After Reboot with Transparent Application Failover TAF configuredDocument 359971.1 STREAMS propagation to Primary of physical Standby configuation errors with Ora-01033, Ora-02068Document 1101616.1 DBMS_PROPAGATION_ADM.DROP_PROPAGATION FAILS WITH ORA-1747 7. Performance Issues A propagation may seem to be slow if the queries from Sections 3.1 and 6.3 show that the message statistics are not changing quickly. In Oracle Streams, this more usually is due to a slow apply process at the target rather than a slow propagation. Propagation could be inferred to be slow if the message statistics are changing, and the state of a capture process according to V$STREAMS_CAPTURE.STATE is PAUSED FOR FLOW CONTROL, but an ORA-25307 'Enqueue rate too high. Enable flow control' warning is NOT observed in DBA_QUEUE_SCHEDULES per Section 6.5.2. If this is the case, see the following notes / white papers for suggestions to increase performance:Document 335516.1 Master Note for Streams Performance RecommendationsDocument 730036.1 Overview for Troubleshooting Streams Performance IssuesDocument 780733.1 Streams Propagation Tuning with Network ParametersWhite Paper: http://www.oracle.com/technetwork/database/features/availability/maa-wp-10gr2-streams-performance-130059.pdfWhite Paper: Oracle Streams Configuration Best Practices: Oracle Database 10g Release 10.2, http://www.oracle.com/technetwork/database/features/availability/maa-10gr2-streams-configuration-132039.pdf, See APPENDIX A: USING STREAMS CONFIGURATIONS OVER A NETWORKFor basic AQ propagation, the network tuning in the aforementioned Appendix A of the white paper 'Oracle Streams Configuration Best Practices: Oracle Database 10g Release 10.2' is applicable. References NOTE:102330.1 - Advanced Queueing MSG_STATE Values and their InterpretationNOTE:102771.1 - Advanced Queueing Propagation using PL/SQLNOTE:1059029.1 - Combined Capture and Apply (CCA) : Capture aborts : ORA-1422 after schedule_propagationNOTE:1079577.1 - Advanced Queuing Propagation Fails With "ORA-22370: incorrect usage of method"NOTE:1083608.1 - 11g Streams and Oracle SchedulerNOTE:1087324.1 - ORA-01405 ORA-01422 reported by Adavanced Queueing Propagation schedules after RAC reconfigurationNOTE:1097115.1 - Oracle Streams Apply Reader is in 'Paused' StateNOTE:1101616.1 - DBMS_PROPAGATION_ADM.DROP_PROPAGATION FAILS WITH ORA-1747NOTE:1159787.1 - Troubleshooting Streams Propagation When It is Not Functioning and Attempts to Stop It HangNOTE:1165583.1 - ORA-600 [kwqpuspse0-ack] In Streams EnvironmentNOTE:118884.1 - How to unschedule a propagation schedule stuck in pending stateNOTE:1203544.1 - AQ PROPAGATION ABORTED WITH ORA-600[OCIKSIN: INVALID STATUS] ON SYS.DBMS_AQADM_SYS.AQ$_PROPAGATION_PROCEDURE AFTER UPGRADENOTE:1204080.1 - AQ Propagation Failing With ORA-25329 After Upgraded From 8i or 9i to 10g or 11g.NOTE:219416.1 - Advanced Queuing Propagation fails with ORA-22922NOTE:222992.1 - DBMS_AQADM.DISABLE_PROPAGATION_SCHEDULE Returns ORA-24082NOTE:253131.1 - Concurrent Writes May Corrupt LOB Segment When Using Auto Segment Space Management (ORA-1555)NOTE:282987.1 - Propagated Messages marked UNDELIVERABLE after Drop and Recreate Of Remote QueueNOTE:298015.1 - Kwqjswproc:Excep After Loop: Assigning To SelfNOTE:302109.1 - Streams Propagation Error: ORA-25307 Enqueue rate too high. Enable flow controlNOTE:311021.1 - Streams Propagation Process : Ora 12154 After Reboot with Transparent Application Failover TAF configuredNOTE:332792.1 - ORA-04061 error relating to SYS.DBMS_PRVTAQIP reported when setting up StatspackNOTE:333068.1 - ORA-23603: Streams Enqueue Aborted Eue To Low SGANOTE:335516.1 - Master Note for Streams Performance RecommendationsNOTE:353325.1 - ORA-24056: Internal inconsistency for QUEUE and destination NOTE:353754.1 - Streams Messaging Propagation Fails between Single and Multi-byte Charactersets when using Chararacter Length Semantics in the ADT.NOTE:359971.1 - STREAMS propagation to Primary of physical Standby configuation errors with Ora-01033, Ora-02068NOTE:363496.1 - Ora-25315 Propagating on RAC StreamsNOTE:365093.1 - ORA-07445 [kwqppay2aqe()+7360] reported on Propagation of a Transformed MessageNOTE:368237.1 - Unable to Unschedule Propagation. Streams Queue is InvalidNOTE:368912.1 - Queue to Queue Propagation Schedule encountered ORA-12514 in a RAC environmentNOTE:421237.1 - ORA-600 [KWQBMCRCPTS101] reported by a Qmon slave process after dropping a Streams PropagationNOTE:436332.1 - dbms_propagation_adm.stop_propagation hangsNOTE:437838.1 - Streams Specific PatchesNOTE:460471.1 - Propagation Blocked by Qmon Process - Streams_queue_table / 'library cache lock' waitsNOTE:463820.1 - Streams Combined Capture and Apply in 11gNOTE:553017.1 - Stream Propagation Process Errors Ora-4052 Ora-6554 From 11g To 10201NOTE:556309.1 - Changing Propagation/ queue_to_queue : false -> true does does not work; no LCRs propagatedNOTE:564649.1 - ORA-02068/ORA-03114/ORA-03113 Errors From Streams Propagation Process - Remote Database is Available and Unschedule/Reschedule Does Not ResolveNOTE:566622.1 - ORA-22275 when propagating >4K AQ$_JMS_TEXT_MESSAGEs from 9.2.0.8 to 10.2.0.1NOTE:727389.1 - Propagation Fails With ORA-12528NOTE:730036.1 - Overview for Troubleshooting Streams Performance IssuesNOTE:730911.1 - ORA-4063 Is Reported After Dropping Negative Prop.RulesetNOTE:731292.1 - ORA-25215 Reported On Local Propagation When Using Transformation with ANYDATA queue tablesNOTE:731539.1 - ORA-29268: HTTP client error 401 Unauthorized Error when the AQ Servlet attempts to Propagate a message via HTTPNOTE:745601.1 - ORA-23603 'STREAMS enqueue aborted due to low SGA' Error from Streams Propagation, and V$STREAMS_CAPTURE.STATE Hanging on 'Enqueuing Message'NOTE:749181.1 - How to Recover Streams After Dropping PropagationNOTE:780733.1 - Streams Propagation Tuning with Network ParametersNOTE:787367.1 - ORA-22275 reported on Propagating Messages with LOB component when propagating between 10.1 and 10.2NOTE:808136.1 - How to clear the old errors from DBA_PROPAGATION view ?NOTE:827184.1 - AQ Propagation with CLOB data types Fails with ORA-22990NOTE:827473.1 - How to alter propagation from queue_to_queue to queue_to_dblinkNOTE:839568.1 - Propagation failing with error: ORA-01536: space quota exceeded for tablespace ''NOTE:846297.1 - AQ Propagation Fails : ORA-00600[kope2upic2954] or Ora-00600[Kghsstream_copyn]NOTE:944846.1 - Streams Propagation Fails Ora-7445 [kohrsmc]

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  • NSFetchedResultsController not processing certain section driven moves

    - by JK
    I utilize a NSFetchedResultsController (frc) with a Core Data store. I implement all the frc delegate methods. The table is sporadically updated by background threads. All the inserts, deletes and updates work fine, with the exception that updates to the frc's index key for rows toward to the bottom of the table (50 rows), do not result in a section move. e.g. if "name" is the index key and the name "Victor" is changed to "Alex", the victor row now shows the name Alex, but is not moved to the top of the table alongside all other names starting with A. As I noted, this is only for rows towards the bottom of the table. If a row like "Andy" is changed to "Ben", the move is indeed processed correctly by the frc. Any suggestions to fix this would be appreciated. I do not use a frc cache. Thanks

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  • Queued Loadtest to remove Concurrency issues using Shared Data Service in OpenScript

    - by stefan.thieme(at)oracle.com
    Queued Processing to remove Concurrency issues in Loadtest ScriptsSome scripts act on information returned by the server, e.g. act on first item in the returned list of pending tasks/actions. This may lead to concurrency issues if the virtual users simulated in a load test scenario are not synchronized in some way.As the load test cases should be carried out in a comparable and straight forward manner simply cancel a transaction in case a collision occurs is clearly not an option. In case you increase the number of virtual users this approach would lead to a high number of requests for the early steps in your transaction (e.g. login, retrieve list of action points, assign an action point to the virtual user) but later steps would be rarely visited successfully or at all, depending on the application logic.A way to tackle this problem is to enqueue the virtual users in a Shared Data Service queue. Only the first virtual user in this queue will be allowed to carry out the critical steps (retrieve list of action points, assign an action point to the virtual user) in your transaction at any one time.Once a virtual user has passed the critical path it will dequeue himself from the head of the queue and continue with his actions. This does theoretically allow virtual users to run in parallel all steps of the transaction which are not part of the critical path.In practice it has been seen this is rarely the case, though it does not allow adding more than N users to perform a transaction without causing delays due to virtual users waiting in the queue. N being the time of the total transaction divided by the sum of the time of all critical steps in this transaction.While this problem can be circumvented by allowing multiple queues to act on individual segments of the list of actions, e.g. per country filter, ends with 0..9 filter, etc.This would require additional handling of these additional queues of slots for the virtual users at the head of the queue in order to maintain the mutually exclusive access to the first element in the list returned by the server at any one time of the load test. Such an improved handling of multiple queues and/or multiple slots is above the subject of this paper.Shared Data Services Pre-RequisitesStart WebLogic Server to host Shared Data ServicesYou will have to make sure that your WebLogic server is installed and started. Shared Data Services may not work if you installed only the minimal installation package for OpenScript. If however you installed the default package including OLT and OTM, you may follow the instructions below to start and verify WebLogic installation.To start the WebLogic Server deployed underneath of Oracle Load Testing and/or Oracle Test Manager you can go to your Start menu, Oracle Application Testing Suite and select the Restart Oracle Application Testing Suite Application Service entry from the Tools submenu.To verify the service has been started you can run the Microsoft Management Console for Services by Selecting Run from the Start Menu and entering services.msc. Look for the entry that reads Oracle Application Testing Suite Application Service, once it has changed it status from Starting to Started you can proceed to verify the login. Please note that this may take several minutes, I would say up to 10 minutes depending on the strength of your CPU horse-power.Verify WebLogic Server user credentialsYou will have to make sure that your WebLogic Server is installed and started. Next open the Oracle WebLogic Server Adminstration Console on http://localhost:8088/console.It may take a while until the application is deployed and started. It may display the following until the Administration Console has been deployed on the fly.Afterwards you can login using the username oats and the password that you selected during install time for your Application Testing Suite administrative purposes.This will bring up the Home page of you WebLogic Server. You have actually verified that you are able to login with these credentials already. However if you want to check the details, navigate to Security Realms, myrealm, Users and Groups tab.Here you could add users to your WebLogic Server which could be used in the later steps. Details on the Groups required for such a custom user to work are exceeding this quick overview and have to be selected with the WebLogic Server Adminstration Guide in mind.Shared Data Services pre-requisites for Load testingOpenScript Preferences have to be set to enable Encryption and provide a default Shared Data Service Connection for Playback.These are pre-requisites you want to use for load testing with Shared Data Services.Please note that the usage of the Connection Parameters (individual directive in the script) for Shared Data Services did not playback reliably in the current version 9.20.0370 of Oracle Load Testing (OLT) and encryption of credentials still seemed to be mandatory as well.General Encryption settingsSelect OpenScript Preferences from the View menu and navigate to the General, Encryption entry in the tree on the left. Select the Encrypt script data option from the list and enter the same password that you used for securing your WebLogic Server Administration Console.Enable global shared data access credentialsSelect OpenScript Preferences from the View menu and navigate to the Playback, Shared Data entry in the tree on the left. Enable the global shared data access credentials and enter the Address, User name and Password determined for your WebLogic Server to host Shared Data Services.Please note, that you may want to replace the localhost in Address with the hosts realname in case you plan to run load tests with Loadtest Agents running on remote systems.Queued Processing of TransactionsEnable Shared Data Services Module in Script PropertiesThe Shared Data Services Module has to be enabled for each Script that wants to employ the Shared Data Service Queue functionality in OpenScript. It can be enabled under the Script menu selecting Script Properties. On the Script Properties Dialog select the Modules section and check Shared Data to enable Shared Data Service Module for your script. Checking the Shared Data Services option will effectively add a line to your script code that adds the sharedData ScriptService to your script class of IteratingVUserScript.@ScriptService oracle.oats.scripting.modules.sharedData.api.SharedDataService sharedData;Record your scriptRecord your script as usual and then add the following things for Queue handling in the Initialize code block, before the first step and after the last step of your critical path and in the Finalize code block.The java code to be added at individual locations is explained in the following sections in full detail.Create a Shared Data Queue in InitializeTo create a Shared Data Queue go to the Java view of your script and enter the following statements to the initialize() code block.info("Create queueA with life time of 120 minutes");sharedData.createQueue("queueA", 120);This will create an instantiation of the Shared Data Queue object named queueA which is maintained for upto 120 minutes.If you want to use the code for multiple scripts, make sure to use a different queue name for each one here and in the subsequent steps. You may even consider to use a dynamic queueName based on filters of your result list being concurrently accessed.Prepare a unique id for each IterationIn order to keep track of individual virtual users in our queue we need to create a unique identifier from the virtual user id and the used username right after retrieving the next record from our databank file.getDatabank("Usernames").getNextDatabankRecord();getVariables().set("usernameValue1","VU_{{@vuid}}_{{@iterationnum}}_{{db.Usernames.Username}}_{{@timestamp}}_{{@random(10000)}}");String usernameValue = getVariables().get("usernameValue1");info("Now running virtual user " + usernameValue);As you can see from the above code block, we have set the OpenScript variable usernameValue1 to VU_{{@vuid}}_{{@iterationnum}}_{{db.Usernames.Username}}_{{@timestamp}}_{{@random(10000)}} which is a concatenation of the virtual user id and the iterationnumber for general uniqueness; as well as the username from our databank, the timestamp and a random number for making it further unique and ease spotting of errors.Not all of these fields are actually required to make it really unique, but adding the queue name may also be considered to help troubleshoot multiple queues.The value is then retrieved with the getVariables.get() method call and assigned to the usernameValue String used throughout the script.Please note that moving the getDatabank("Usernames").getNextDatabankRecord(); call to the initialize block was later considered to remove concurrency of multiple virtual users running with the same userid and therefor accessing the same "My Inbox" in step 6. This will effectively give each virtual user a userid from the databank file. Make sure you have enough userids to remove this second hurdle.Enqueue and attend Queue before Critical PathTo maintain the right order of virtual users being allowed into the critical path of the transaction the following pseudo step has to be added in front of the first critical step. In the case of this example this is right in front of the step where we retrieve the list of actions from which we select the first to be assigned to us.beginStep("[0] Waiting in the Queue", 0);{info("Enqueued virtual user " + usernameValue + " at the end of queueA");sharedData.offerLast("queueA", usernameValue);info("Wait until the user is the first in queueA");String queueValue1 = null;do {// we wait for at least 0.7 seconds before we check the head of the// queue. This is the time it takes one user to move through the// critical path, i.e. pass steps [5] Enter country and [6] Assign// to meThread.sleep(700);queueValue1 = (String) sharedData.peekFirst("queueA");info("The first user in queueA is currently: '" + queueValue1 + "' " + queueValue1.getClass() + " length " + queueValue1.length() );info("The current user is '"+ usernameValue + "' " + usernameValue.getClass() + " length " + usernameValue.length() + ": indexOf " + usernameValue.indexOf(queueValue1) + " equals " + usernameValue.equals(queueValue1) );} while ( queueValue1.indexOf(usernameValue) < 0 );info("Now the user is the first in queueA");}endStep();This will enqueue the username to the tail of our Queue. It will will wait for at least 700 milliseconds, the time it takes for one user to exit the critical path and then compare the head of our queue with it's username. This last step will be repeated while the two are not equal (indexOf less than zero). If they are equal the indexOf will yield a value of zero or larger and we will perform the critical steps.Dequeue after Critical PathAfter the virtual user has left the critical path and complete its last step the following code block needs to dequeue the virtual user. In the case of our example this is right after the action has been actually assigned to the virtual user. This will allow the next virtual user to retrieve the list of actions still available and in turn let him make his selection/assignment.info("Get and remove the current user from the head of queueA");String pollValue1 = (String) sharedData.pollFirst("queueA");The current user is removed from the head of the queue. The next one will now be able to match his username against the head of the queue.Clear and Destroy Queue for FinishWhen the script has completed, it should clear and destroy the queue. This code block can be put in the finish block of your script and/or in a separate script in order to clear and remove the queue in case you have spotted an error or want to reset the queue for some reason.info("Clear queueA");sharedData.clearQueue("queueA");info("Destroy queueA");sharedData.destroyQueue("queueA");The users waiting in queueA are cleared and the queue is destroyed. If you have scripts still executing they will be caught in a loop.I found it better to maintain a separate Reset Queue script which contained only the following code in the initialize() block. I use to call this script to make sure the queue is cleared in between multiple Loadtest runs. This script could also even be added as the first in a larger scenario, which would execute it only once at very start of the Loadtest and make sure the queues do not contain any stale entries.info("Create queueA with life time of 120 minutes");sharedData.createQueue("queueA", 120);info("Clear queueA");sharedData.clearQueue("queueA");This will create a Shared Data Queue instance of queueA and clear all entries from this queue.Monitoring QueueWhile creating the scripts it was useful to monitor the contents, i.e. the current first user in the Queue. The following code block will make sure the Shared Data Queue is accessible in the initialize() block.info("Create queueA with life time of 120 minutes");sharedData.createQueue("queueA", 120);In the run() block the following code will continuously monitor the first element of the Queue and write an informational message with the current username Value to the Result window.info("Monitor the first users in queueA");String queueValue1 = null;do {queueValue1 = (String) sharedData.peekFirst("queueA");if (queueValue1 != null)info("The first user in queueA is currently: '" + queueValue1 + "' " + queueValue1.getClass() + " length " + queueValue1.length() );} while ( true );This script can be run from OpenScript parallel to a loadtest performed by the Oracle Load Test.However it is not recommend to run this in a production loadtest as the performance impact is unknown. Accessing the Queue's head with the peekFirst() method has been reported with about 2 seconds response time by both OpenScript and OTL. It is advised to log a Service Request to see if this could be lowered in future releases of Application Testing Suite, as the pollFirst() and even offerLast() writing to the tail of the Queue usually returned after an average 0.1 seconds.Debugging QueueWhile debugging the scripts the following was useful to remove single entries from its head, i.e. the current first user in the Queue. The following code block will make sure the Shared Data Queue is accessible in the initialize() block.info("Create queueA with life time of 120 minutes");sharedData.createQueue("queueA", 120);In the run() block the following code will remove the first element of the Queue and write an informational message with the current username Value to the Result window.info("Get and remove the current user from the head of queueA");String pollValue1 = (String) sharedData.pollFirst("queueA");info("The first user in queueA was currently: '" + pollValue1 + "' " + pollValue1.getClass() + " length " + pollValue1.length() );ReferencesOracle Functional Testing OpenScript User's Guide Version 9.20 [E15488-05]Chapter 17 Using the Shared Data Modulehttp://download.oracle.com/otn/nt/apptesting/oats-docs-9.21.0030.zipOracle Fusion Middleware Oracle WebLogic Server Administration Console Online Help 11g Release 1 (10.3.4) [E13952-04]Administration Console Online Help - Manage users and groupshttp://download.oracle.com/docs/cd/E17904_01/apirefs.1111/e13952/taskhelp/security/ManageUsersAndGroups.htm

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  • Native packaging for JavaFX

    - by igor
    JavaFX 2.2 adds new packaging option for JavaFX applications, allowing you to package your application as a "native bundle". This gives your users a way to install and run your application without any external dependencies on a system JRE or FX SDK. I'd like to give you an overview of what is it, motivation behind it, and finally explain how to get started with it. Screenshots may give you some idea of user experience but first hand experience is always the best. Before we go into all of the boring details, here are few different flavors of Ensemble for you to try: exe, msi, dmg, rpm installers and zip of linux bundle for non-rpm aware systems. Alternatively, check out native packages for JFXtras 2. Whats wrong with existing deployment options? JavaFX 2 applications are easy to distribute as a standalone application or as an application deployed on the web (embedded in the web page or as link to launch application from the webpage). JavaFX packaging tools, such as ant tasks and javafxpackager utility, simplify the creation of deployment packages even further. Why add new deployment options? JavaFX applications have implicit dependency on the availability of Java and JavaFX runtimes, and while existing deployment methods provide a means to validate the system requirements are met -- and even guide user to perform required installation/upgrades -- they do not fully address all of the important scenarios. In particular, here are few examples: the user may not have admin permissions to install new system software if the application was certified to run in the specific environment (fixed version of Java and JavaFX) then it may be hard to ensure user has this environment due to an autoupdate of the system version of Java/JavaFX (to ensure they are secure). Potentially, other apps may have a requirement for a different JRE or FX version that your app is incompatible with. your distribution channel may disallow dependencies on external frameworks (e.g. Mac AppStore) What is a "native package" for JavaFX application? In short it is  A Wrapper for your JavaFX application that makes is into a platform-specific application bundle Each Bundle is self-contained and includes your application code and resources (same set as need to launch standalone application from jar) Java and JavaFX runtimes (private copies to be used by this application only) native application launcher  metadata (icons, etc.) No separate installation is needed for Java and JavaFX runtimes Can be distributed as .zip or packaged as platform-specific installer No application changes, the same jar app binaries can be deployed as a native bundle, double-clickable jar, applet, or web start app What is good about it: Easy deployment of your application on fresh systems, without admin permissions when using .zip or a user-level installer No-hassle compatibility.  Your application is using a private copy of Java and JavaFX. The developer (you!) controls when these are updated. Easily package your application for Mac AppStore (or Windows, or...) Process name of running application is named after your application (and not just java.exe)  Easily deploy your application using enterprise deployment tools (e.g. deploy as MSI) Support is built in into JDK 7u6 (that includes JavaFX 2.2) Is it a silver bullet for the deployment that other deployment options will be deprecated? No.  There are no plans to deprecate other deployment options supported by JavaFX, each approach addresses different needs. Deciding whether native packaging is a best way to deploy your application depends on your requirements. A few caveats to consider: "Download and run" user experienceUnlike web deployment, the user experience is not about "launch app from web". It is more of "download, install and run" process, and the user may need to go through additional steps to get application launched - e.g. accepting a browser security dialog or finding and launching the application installer from "downloads" folder. Larger download sizeIn general size of bundled application will be noticeably higher than size of unbundled app as a private copy of the JRE and JavaFX are included.  We're working to reduce the size through compression and customizable "trimming", but it will always be substantially larger than than an app that depends on a "system JRE". Bundle per target platformBundle formats are platform specific. Currently a native bundle can only be produced for the same system you are building on.  That is, if you want to deliver native app bundles on Windows, Linux and Mac you will have to build your project on all three platforms. Application updates are the responsibility of developerWeb deployed Java applications automatically download application updates from the web as soon as they are available. The Java Autoupdate mechanism takes care of updating the Java and JavaFX runtimes to latest secure version several times every year. There is no built in support for this in for bundled applications. It is possible to use 3rd party libraries (like Sparkle on Mac) to add autoupdate support at application level.  In a future version of JavaFX we may include built-in support for autoupdate (add yourself as watcher for RT-22211 if you are interested in this) Getting started with native bundles First, you need to get the latest JDK 7u6 beta build (build 14 or later is recommended). On Windows/Mac/Linux it comes with JavaFX 2.2 SDK as part of JDK installation and contains JavaFX packaging tools, including: bin/javafxpackagerCommand line utility to produce JavaFX packages. lib/ant-javafx.jar Set of ant tasks to produce JavaFX packages (most recommended way to deploy apps) For general information on how to use them refer to the Deploying JavaFX Application guide. Once you know how use these tools to package your JavaFX application for other deployment methods there are only a few minor tweaks necessary to produce native bundles: make sure java is used from JDK7u6 bundle you have installed adjust your PATH settings if needed  if you are using ant tasks add "nativeBundles=all" attribute to fx:deploy task if you are using javafxpackager pass "-native" option to deploy command or if you are using makeall command then it will try build native packages by default result bundles will be in the "bundles" folder next to other deployment artifacts Note that building some types of native packages (e.g. .exe or .msi) may require additional free 3rd party software to be installed and available on PATH. As of JDK 7u6 build 14 you could build following types of packages: Windows bundle image EXE Inno Setup 5 or later is required Result exe will perform user level installation (no admin permissions are required) At least one shortcut will be created (menu or desktop) Application will be launched at the end of install MSI WiX 3.0 or later is required Result MSI will perform user level installation (no admin permissions are required) At least one shortcut will be created (menu or desktop)  MacOS bundle image dmg (drag and drop) installer Linux bundle image rpm rpmbuild is required shortcut will be added to the programs menu If you are using Netbeans for producing the deployment packages then you will need to add custom build step to the build.xml to execute the fx:deploy task with native bundles enabled. Here is what we do for BrickBreaker sample: <target name="-post-jfx-deploy"> <fx:deploy width="${javafx.run.width}" height="${javafx.run.height}" nativeBundles="all" outdir="${basedir}/${dist.dir}" outfile="${application.title}"> <fx:application name="${application.title}" mainClass="${javafx.main.class}"> <fx:resources> <fx:fileset dir="${basedir}/${dist.dir}" includes="BrickBreaker.jar"/> </fx:resources> <info title="${application.title}" vendor="${application.vendor}"/> </fx:application> </fx:deploy> </target> This is pretty much regular use of fx:deploy task, the only special thing here is nativeBundles="all". Perhaps the easiest way to try building native bundles is to download the latest JavaFX samples bundle and build Ensemble, BrickBreaker or SwingInterop. Please give it a try and share your experience. We need your feedback! BTW, do not hesitate to file bugs and feature requests to JavaFX bug database! Wait! How can i ... This entry is not a comprehensive guide into native bundles, and we plan to post on this topic more. However, I am sure that once you play with native bundles you will have a lot of questions. We may not have all the answers, but please do not hesitate to ask! Knowing all of the questions is the first step to finding all of the answers.

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  • My View on ASP.NET Web Forms versus MVC

    - by Ricardo Peres
    Introduction A lot has been said on Web Forms and MVC, but since I was recently asked about my opinion on the subject, here it is. First, I have to say that I really like both technologies and I don’t think any is going away – just remember SharePoint, which is built on top of Web Forms. I see them as complementary, targeting different needs and leveraging different skills. Let’s go through some of their differences. Rapid Application Development Rapid Application Development (RAD) is the development process by which you have an Integrated Development Environment (IDE), a visual design surface and a toolbox, and you drag components from the toolbox to the design surface and set their properties through a property inspector. It was introduced with some of the earliest Windows graphical IDEs such as Visual Basic and Delphi. With Web Forms you have RAD out of the box. Visual Studio offers a generally good (and extensible) designer for the layout of pages and web user controls. Designing a page may simply be about dragging controls from the toolbox, setting their properties and wiring up some events to event handlers, which are implemented in code behind .NET classes. Most people will be familiar with this kind of development and enjoy it. You can see what you are doing from the beginning. MVC also has designable pages – called views in MVC terminology – the problem is that they can be built using different technologies, some of which, at the moment (MVC 4) do not support RAD – Razor, for example. I believe it is just a matter of time for that to be implemented in Visual Studio, but it will mostly consist on HTML editing, and until that day comes, you have to live with source editing. Development Model Web Forms features the same development model that you are used to from Windows Forms and other similar technologies: events fired by controls and automatic persistence of their properties between postbacks. For that, it uses concepts such as view state, which some may love and others may hate, because it may be misused quite easily, but otherwise does its job well. Another fundamental concept is data binding, by which a collection of data can be fed to a control and have it render that data somehow – just thing of the GridView control. The focus is on the page, that’s where it all starts, and you can place everything in the same code behind class: data access, business logic, layout, etc. The controls take care of generating a great part of the HTML and JavaScript for you. With MVC there is no free lunch when it comes to data persistence between requests, you have to implement it yourself. As for event handling, that is at the core of MVC, in the form of controllers and action methods, you just don’t think of them as event handlers. In MVC you need to think more in HTTP terms, so action methods such as POST and GET are relevant to you, and may write actions to handle one or the other. Also of crucial importance is model binding: the way by which MVC converts your posted data into a .NET class. This is something that ASP.NET 4.5 Web Forms has introduced as well, but it is a cornerstone in MVC. MVC also has built-in validation of these .NET classes, which out of the box uses the Data Annotations API. You have full control of the generated HTML - except for that coming from the helper methods, usually small fragments - which requires a greater familiarity with the specifications. You normally rely much more on JavaScript APIs, they are even included in the Visual Studio template, that is because much less is done for you. Reuse It is difficult to accept a professional company/project that does not employ reuse. It can save a lot of time thus cutting costs significantly. Code reused in several projects matures as time goes by and helps developers learn from past experiences. ASP.NET Web Forms was built with reuse in mind, in the form of controls. Controls encapsulate functionality and are generally portable from project to project (with the notable exception of web user controls, those with an associated .ASCX markup file). ASP.NET has dozens of controls and it is very easy to develop new ones, so I believe this is a great advantage. A control can inject JavaScript code and external references as well as generate HTML an CSS. MVC on the other hand does not use controls – it is possible to use them, with some view engines like ASPX, but it is just not advisable because it breaks the flow – where do Init, Load, PreRender, etc, fit? The most similar to controls is extension methods, or helpers. They serve the same purpose – generating HTML, CSS or JavaScript – and can be reused between different projects. What differentiates them from controls is that there is no inheritance and no context – an extension method is just a static method which doesn’t know where it is being called. You also have partial views, which you can reuse in the same project, but there is no inheritance as well. This, in my view, is a weakness of MVC. Architecture Both technologies are highly extensible. I have writtenstarted writing a series of posts on ASP.NET Web Forms extensibility and will probably write another series on MVC extensibility as well. A number of scenarios are covered in any of these models, and some extensibility points apply to both, because, of course both stand upon ASP.NET. With Web Forms, if you’re like me, you start by defining you master pages, pages and controls, with some helper classes to glue everything. You may as well throw in some JavaScript, but probably you’re main work will be with plain old .NET code. The controls you define have the chance to inject JavaScript code and references, through either the ScriptManager or the page’s ClientScript object, as well as generating HTML and CSS code. The master page and page model with code behind classes offer a number of “hooks” by which you can change the normal way of things, for example, in a page you can access any control on the master page, add script or stylesheet references to its head and even change the page’s title. Also, with Web Forms, you typically have URLs in the form “/SomePath/SomePage.aspx?SomeParameter=SomeValue”, which isn’t really SEO friendly, no to mention the HTML that some controls produce, far from standards, optimization and best practices. In MVC, you also normally start by defining the master page (or layout) and views, which are the visible parts, and then define controllers on separate files. These controllers do not know anything about the views, except the names and types of the parameters that will be passed to and from them. The controller will be responsible for the data access and business logic, eventually relying on additional classes for this purpose. On a controller you only receive parameters and return a result, which may be a request for the rendering of a view, a redirection to another URL or a JSON object, to name just a few. The controller class does not know anything about the web, so you can effectively reuse it in a non-web project. This separation and the lack of programmatic access to the UI elements, makes it very difficult to implement, for example, something like SharePoint with MVC. OK, I know about Orchard, but it isn’t really a general purpose development framework, but instead, a CMS that happens to use MVC. Not having controls render HTML for you gives you in turn much more control over it – it is your responsibility to create it, which you can either consider a blessing or a curse, in the later case, you probably shouldn’t be using MVC at all. Also MVC URLs tend to be much more SEO-oriented, if you design your controllers and actions properly. Testing In a well defined architecture, you should separate business logic, data access logic and presentation logic, because these are all different things and it might even be the need to switch one implementation for another: for example, you might design a system which includes a data access layer, a business logic layer and two presentation layers, one on top of ASP.NET and the other with WPF; and the data access layer might be implemented first using NHibernate and later on switched for Entity Framework Code First. These changes are not that rare, so care should be taken in designing the system to make them possible. Web Forms are difficult to test, because it relies on event handlers which are only fired in web contexts, when a form is submitted or a page is requested. You can call them with reflection, but you have to set up a number of mocking objects first, HttpContext.Current first coming to my mind. MVC, on the other hand, makes testing controllers a breeze, so much that it even includes a template option for generating boilerplate unit test classes up from start. A well designed – from the unit test point of view - controller will receive everything it needs to work as parameters to its action methods, so you can pass whatever values you need very easily. That doesn’t mean, of course, that everything can be tested: views, for instance, are difficult to test without actually accessing the site, but MVC offers the possibility to compile views at build time, so that, at least, you know you don’t have syntax errors beforehand. Myths Some popular but unfounded myths around MVC include: You cannot use controls in MVC: not true, actually, you can, at least with the Web Forms (ASPX) view engine; the declaration and usage is exactly the same as with Web Forms; You cannot specify a base class for a view: with the ASPX view engine you can use the Inherits Page directive, with this and all the others you can use the pageBaseType and userControlBaseType attributes of the <page> element; MVC shields you from doing “bad things” on your views: well, you can place any code on a code block, at least with the ASPX view engine (you may be starting to see a pattern here), even data access code; The model is the entity model, tied to an O/RM: the model is actually any class that you use to pass values to a view, including (but generally not recommended) an entity model; Unit tests come with no cost: unit tests generally don’t cover the UI, although there are frameworks just for that (see WatiN, for example); also, for some tests, you will have to mock or replace either the HttpContext.Current property or the HttpContextBase class yourself; Everything is testable: views aren’t, without accessing the site; MVC relies on HTML5/some_cool_new_javascript_framework: there is no relation whatsoever, MVC renders whatever you want it to render and does not require any framework to be present. The thing is, the subsequent releases of MVC happened in a time when Microsoft has become much more involved in standards, so the files and technologies included in the Visual Studio templates reflect this, and it just happens to work well with jQuery, for example. Conclusion Well, this is how I see it. Some folks may think that I am being too rude on MVC, probably because I don’t like it, but that’s not true: like I said, I do like MVC and I am starting my new projects with it. I just don’t want to go along with that those that say that MVC is much superior to Web Forms, in fact, some things you can do much more easily with Web Forms than with MVC. I will be more than happy to hear what you think on this!

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  • Code Reuse is (Damn) Hard

    - by James Michael Hare
    Being a development team lead, the task of interviewing new candidates was part of my job.  Like any typical interview, we started with some easy questions to get them warmed up and help calm their nerves before hitting the hard stuff. One of those easier questions was almost always: “Name some benefits of object-oriented development.”  Nearly every time, the candidate would chime in with a plethora of canned answers which typically included: “it helps ease code reuse.”  Of course, this is a gross oversimplification.  Tools only ease reuse, its developers that ultimately can cause code to be reusable or not, regardless of the language or methodology. But it did get me thinking…  we always used to say that as part of our mantra as to why Object-Oriented Programming was so great.  With polymorphism, inheritance, encapsulation, etc. we in essence set up the concepts to help facilitate reuse as much as possible.  And yes, as a developer now of many years, I unquestionably held that belief for ages before it really struck me how my views on reuse have jaded over the years.  In fact, in many ways Agile rightly eschews reuse as taking a backseat to developing what's needed for the here and now.  It used to be I was in complete opposition to that view, but more and more I've come to see the logic in it.  Too many times I've seen developers (myself included) get lost in design paralysis trying to come up with the perfect abstraction that would stand all time.  Nearly without fail, all of these pieces of code become obsolete in a matter of months or years. It’s not that I don’t like reuse – it’s just that reuse is hard.  In fact, reuse is DAMN hard.  Many times it is just a distraction that eats up architect and developer time, and worse yet can be counter-productive and force wrong decisions.  Now don’t get me wrong, I love the idea of reusable code when it makes sense.  These are in the few cases where you are designing something that is inherently reusable.  The problem is, most business-class code is inherently unfit for reuse! Furthermore, the code that is reusable will often fail to be reused if you don’t have the proper framework in place for effective reuse that includes standardized versioning, building, releasing, and documenting the components.  That should always be standard across the board when promoting reusable code.  All of this is hard, and it should only be done when you have code that is truly reusable or you will be exerting a large amount of development effort for very little bang for your buck. But my goal here is not to get into how to reuse (that is a topic unto itself) but what should be reused.  First, let’s look at an extension method.  There’s many times where I want to kick off a thread to handle a task, then when I want to reign that thread in of course I want to do a Join on it.  But what if I only want to wait a limited amount of time and then Abort?  Well, I could of course write that logic out by hand each time, but it seemed like a great extension method: 1: public static class ThreadExtensions 2: { 3: public static bool JoinOrAbort(this Thread thread, TimeSpan timeToWait) 4: { 5: bool isJoined = false; 6:  7: if (thread != null) 8: { 9: isJoined = thread.Join(timeToWait); 10:  11: if (!isJoined) 12: { 13: thread.Abort(); 14: } 15: } 16: return isJoined; 17: } 18: } 19:  When I look at this code, I can immediately see things that jump out at me as reasons why this code is very reusable.  Some of them are standard OO principles, and some are kind-of home grown litmus tests: Single Responsibility Principle (SRP) – The only reason this extension method need change is if the Thread class itself changes (one responsibility). Stable Dependencies Principle (SDP) – This method only depends on classes that are more stable than it is (System.Threading.Thread), and in itself is very stable, hence other classes may safely depend on it. It is also not dependent on any business domain, and thus isn't subject to changes as the business itself changes. Open-Closed Principle (OCP) – This class is inherently closed to change. Small and Stable Problem Domain – This method only cares about System.Threading.Thread. All-or-None Usage – A user of a reusable class should want the functionality of that class, not parts of that functionality.  That’s not to say they most use every method, but they shouldn’t be using a method just to get half of its result. Cost of Reuse vs. Cost to Recreate – since this class is highly stable and minimally complex, we can offer it up for reuse very cheaply by promoting it as “ready-to-go” and already unit tested (important!) and available through a standard release cycle (very important!). Okay, all seems good there, now lets look at an entity and DAO.  I don’t know about you all, but there have been times I’ve been in organizations that get the grand idea that all DAOs and entities should be standardized and shared.  While this may work for small or static organizations, it’s near ludicrous for anything large or volatile. 1: namespace Shared.Entities 2: { 3: public class Account 4: { 5: public int Id { get; set; } 6:  7: public string Name { get; set; } 8:  9: public Address HomeAddress { get; set; } 10:  11: public int Age { get; set;} 12:  13: public DateTime LastUsed { get; set; } 14:  15: // etc, etc, etc... 16: } 17: } 18:  19: ... 20:  21: namespace Shared.DataAccess 22: { 23: public class AccountDao 24: { 25: public Account FindAccount(int id) 26: { 27: // dao logic to query and return account 28: } 29:  30: ... 31:  32: } 33: } Now to be fair, I’m not saying there doesn’t exist an organization where some entites may be extremely static and unchanging.  But at best such entities and DAOs will be problematic cases of reuse.  Let’s examine those same tests: Single Responsibility Principle (SRP) – The reasons to change for these classes will be strongly dependent on what the definition of the account is which can change over time and may have multiple influences depending on the number of systems an account can cover. Stable Dependencies Principle (SDP) – This method depends on the data model beneath itself which also is largely dependent on the business definition of an account which can be very inherently unstable. Open-Closed Principle (OCP) – This class is not really closed for modification.  Every time the account definition may change, you’d need to modify this class. Small and Stable Problem Domain – The definition of an account is inherently unstable and in fact may be very large.  What if you are designing a system that aggregates account information from several sources? All-or-None Usage – What if your view of the account encompasses data from 3 different sources but you only care about one of those sources or one piece of data?  Should you have to take the hit of looking up all the other data?  On the other hand, should you have ten different methods returning portions of data in chunks people tend to ask for?  Neither is really a great solution. Cost of Reuse vs. Cost to Recreate – DAOs are really trivial to rewrite, and unless your definition of an account is EXTREMELY stable, the cost to promote, support, and release a reusable account entity and DAO are usually far higher than the cost to recreate as needed. It’s no accident that my case for reuse was a utility class and my case for non-reuse was an entity/DAO.  In general, the smaller and more stable an abstraction is, the higher its level of reuse.  When I became the lead of the Shared Components Committee at my workplace, one of the original goals we looked at satisfying was to find (or create), version, release, and promote a shared library of common utility classes, frameworks, and data access objects.  Now, of course, many of you will point to nHibernate and Entity for the latter, but we were looking at larger, macro collections of data that span multiple data sources of varying types (databases, web services, etc). As we got deeper and deeper in the details of how to manage and release these items, it quickly became apparent that while the case for reuse was typically a slam dunk for utilities and frameworks, the data access objects just didn’t “smell” right.  We ended up having session after session of design meetings to try and find the right way to share these data access components. When someone asked me why it was taking so long to iron out the shared entities, my response was quite simple, “Reuse is hard...”  And that’s when I realized, that while reuse is an awesome goal and we should strive to make code maintainable, often times you end up creating far more work for yourself than necessary by trying to force code to be reusable that inherently isn’t. Think about classes the times you’ve worked in a company where in the design session people fight over the best way to implement a class to make it maximally reusable, extensible, and any other buzzwordable.  Then think about how quickly that design became obsolete.  Many times I set out to do a project and think, “yes, this is the best design, I can extend it easily!” only to find out the business requirements change COMPLETELY in such a way that the design is rendered invalid.  Code, in general, tends to rust and age over time.  As such, writing reusable code can often be difficult and many times ends up being a futile exercise and worse yet, sometimes makes the code harder to maintain because it obfuscates the design in the name of extensibility or reusability. So what do I think are reusable components? Generic Utility classes – these tend to be small classes that assist in a task and have no business context whatsoever. Implementation Abstraction Frameworks – home-grown frameworks that try to isolate changes to third party products you may be depending on (like writing a messaging abstraction layer for publishing/subscribing that is independent of whether you use JMS, MSMQ, etc). Simplification and Uniformity Frameworks – To some extent this is similar to an abstraction framework, but there may be one chosen provider but a development shop mandate to perform certain complex items in a certain way.  Or, perhaps to simplify and dumb-down a complex task for the average developer (such as implementing a particular development-shop’s method of encryption). And what are less reusable? Application and Business Layers – tend to fluctuate a lot as requirements change and new features are added, so tend to be an unstable dependency.  May be reused across applications but also very volatile. Entities and Data Access Layers – these tend to be tuned to the scope of the application, so reusing them can be hard unless the abstract is very stable. So what’s the big lesson?  Reuse is hard.  In fact it’s damn hard.  And much of the time I’m not convinced we should focus too hard on it. If you’re designing a utility or framework, then by all means design it for reuse.  But you most also really set down a good versioning, release, and documentation process to maximize your chances.  For anything else, design it to be maintainable and extendable, but don’t waste the effort on reusability for something that most likely will be obsolete in a year or two anyway.

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  • Granular Clipboard Control in Oracle IRM

    - by martin.abrahams
    One of the main leak prevention controls that customers are looking for is clipboard control. After all, there is little point in controlling access to a document if authorised users can simply make unprotected copies by use of the cut and paste mechanism. Oddly, for such a fundamental requirement, many solutions only offer very simplistic clipboard control - and require the customer to make an awkward choice between usability and security. In many cases, clipboard control is simply an ON-OFF option. By turning the clipboard OFF, you disable one of the most valuable edit functions known to man. Try working for any length of time without copying and pasting, and you'll soon appreciate how valuable that function is. Worse, some solutions disable the clipboard completely - not just for the protected document but for all of the various applications you have open at the time. Normal service is only resumed when you close the protected document. In this way, policy enforcement bleeds out of the particular assets you need to protect and interferes with the entire user experience. On the other hand, turning the clipboard ON satisfies a fundamental usability requirement - but also makes it really easy for users to create unprotected copies of sensitive information, maliciously or otherwise. All they need to do is paste into another document. If creating unprotected copies is this simple, you have to question how much you are really gaining by applying protection at all. You may not be allowed to edit, forward, or print the protected asset, but all you need to do is create a copy and work with that instead. And that activity would not be tracked in any way. So, a simple ON-OFF control creates a real tension between usability and security. If you are only using IRM on a small scale, perhaps security can outweigh usability - the business can put up with the restriction if it only applies to a handful of important documents. But try extending protection to large numbers of documents and large user communities, and the restriction rapidly becomes really unwelcome. I am aware of one solution that takes a different tack. Rather than disable the clipboard, pasting is always permitted, but protection is automatically applied to any document that you paste into. At first glance, this sounds great - protection travels with the content. However, at any scale this model may not be so appealing once you've had to deal with support calls from users who have accidentally applied protection to documents that really don't need it - which would be all too easily done. This may help control leakage, but it also pollutes the system with documents that have policies applied with no obvious rhyme or reason, and it can seriously inconvenience the business by making non-sensitive documents difficult to access. And what policy applies if you paste some protected content into an already protected document? Which policy applies? There are no prizes for guessing that Oracle IRM takes a rather different approach. The Oracle IRM Approach Oracle IRM offers a spectrum of clipboard controls between the extremes of ON and OFF, and it leverages the classification-based rights model to give granular control that satisfies both security and usability needs. Firstly, we take it for granted that if you have EDIT rights, of course you can use the clipboard within a given document. Why would we force you to retype a piece of content that you want to move from HERE... to HERE...? If the pasted content remains in the same document, it is equally well protected whether it be at the beginning, middle, or end - or all three. So, the first point is that Oracle IRM always enables the clipboard if you have the right to edit the file. Secondly, whether we enable or disable the clipboard, we only affect the protected document. That is, you can continue to use the clipboard in the usual way for unprotected documents and applications regardless of whether the clipboard is enabled or disabled for the protected document(s). And if you have multiple protected documents open, each may have the clipboard enabled or disabled independently, according to whether you have Edit rights for each. So, even for the simplest cases - the ON-OFF cases - Oracle IRM adds value by containing the effect to the protected documents rather than to the whole desktop environment. Now to the granular options between ON and OFF. Thanks to our classification model, we can define rights that enable pasting between documents in the same classification - ie. between documents that are protected by the same policy. So, if you are working on this month's financial report and you want to pull some data from last month's report, you can simply cut and paste between the two documents. The two documents are classified the same way, subject to the same policy, so the content is equally safe in both documents. However, if you try to paste the same data into an unprotected document or a document in a different classification, you can be prevented. Thus, the control balances legitimate user requirements to allow pasting with legitimate information security concerns to keep data protected. We can take this further. You may have the right to paste between related classifications of document. So, the CFO might want to copy some financial data into a board document, where the two documents are sealed to different classifications. The CFO's rights may well allow this, as it is a reasonable thing for a CFO to want to do. But policy might prevent the CFO from copying the same data into a classification that is accessible to external parties. The above option, to copy between classifications, may be for specific classifications or open-ended. That is, your rights might enable you to go from A to B but not to C, or you might be allowed to paste to any classification subject to your EDIT rights. As for so many features of Oracle IRM, our classification-based rights model makes this type of granular control really easy to manage - you simply define that pasting is permitted between classifications A and B, but omit C. Or you might define that pasting is permitted between all classifications, but not to unprotected locations. The classification model enables millions of documents to be controlled by a few such rules. Finally, you MIGHT have the option to paste anywhere - such that unprotected copies may be created. This is rare, but a legitimate configuration for some users, some use cases, and some classifications - but not something that you have to permit simply because the alternative is too restrictive. As always, these rights are defined in user roles - so different users are subject to different clipboard controls as required in different classifications. So, where most solutions offer just two clipboard options - ON-OFF or ON-but-encrypt-everything-you-touch - Oracle IRM offers real granularity that leverages our classification model. Indeed, I believe it is the lack of a classification model that makes such granularity impractical for other IRM solutions, because the matrix of rules for controlling pasting would be impossible to manage - there are so many documents to consider, and more are being created all the time.

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  • Developing Mobile Applications: Web, Native, or Hybrid?

    - by Michelle Kimihira
    Authors: Joe Huang, Senior Principal Product Manager, Oracle Mobile Application Development Framework  and Carlos Chang, Senior Principal Product Director The proliferation of mobile devices and platforms represents a game-changing technology shift on a number of levels. Companies must decide not only the best strategic use of mobile platforms, but also how to most efficiently implement them. Inevitably, this conversation devolves to the developers, who face the task of developing and supporting mobile applications—not a simple task in light of the number of devices and platforms. Essentially, developers can choose from the following three different application approaches, each with its own set of pros and cons. Native Applications: This refers to apps built for and installed on a specific platform, such as iOS or Android, using a platform-specific software development kit (SDK).  For example, apps for Apple’s iPhone and iPad are designed to run specifically on iOS and are written in Xcode/Objective-C. Android has its own variation of Java, Windows uses C#, and so on.  Native apps written for one platform cannot be deployed on another. Native apps offer fast performance and access to native-device services but require additional resources to develop and maintain each platform, which can be expensive and time consuming. Mobile Web Applications: Unlike native apps, mobile web apps are not installed on the device; rather, they are accessed via a Web browser.  These are server-side applications that render HTML, typically adjusting the design depending on the type of device making the request.  There are no program coding constraints for writing server-side apps—they can be written in Java, C, PHP, etc., it doesn’t matter.  Instead, the server detects what type of mobile browser is pinging the server and adjusts accordingly. For example, it can deliver fully JavaScript and CSS-enabled content to smartphone browsers, while downgrading gracefully to basic HTML for feature phone browsers. Mobile apps work across platforms, but are limited to what you can do through a browser and require Internet connectivity. For certain types of applications, these constraints may not be an issue. Oracle supports mobile web applications via ADF Faces (for tablets) and ADF Mobile browser (Trinidad) for smartphone and feature phones. Hybrid Applications: As the name implies, hybrid apps combine technologies from native and mobile Web apps to gain the benefits each. For example, these apps are installed on a device, like their pure native app counterparts, while the user interface (UI) is based on HTML5.  This UI runs locally within the native container, which usually leverages the device’s browser engine.  The advantage of using HTML5 is a consistent, cross-platform UI that works well on most devices.  Combining this with the native container, which is installed on-device, provides mobile users with access to local device services, such as camera, GPS, and local device storage.  Native apps may offer greater flexibility in integrating with device native services.  However, since hybrid applications already provide device integrations that typical enterprise applications need, this is typically less of an issue.  The new Oracle ADF Mobile release is an HTML5 and Java hybrid framework that targets mobile app development to iOS and Android from one code base. So, Which is the Best Approach? The short answer is – the best choice depends on the type of application you are developing.  For instance, animation-intensive apps such as games would favor native apps, while hybrid applications may be better suited for enterprise mobile apps because they provide multi-platform support. Just for starters, the following issues must be considered when choosing a development path. Application Complexity: How complex is the application? A quick app that accesses a database or Web service for some data to display?  You can keep it simple, and a mobile Web app may suffice. However, for a mobile/field worker type of applications that supports mission critical functionality, hybrid or native applications are typically needed. Richness of User Interactivity: What type of user experience is required for the application?  Mobile browser-based app that’s optimized for mobile UI may suffice for quick lookup or productivity type of applications.  However, hybrid/native application would typically be required to deliver highly interactive user experiences needed for field-worker type of applications.  For example, interactive BI charts/graphs, maps, voice/email integration, etc.  In the most extreme case like gaming applications, native applications may be necessary to deliver the highly animated and graphically intensive user experience. Performance: What type of performance is required by the application functionality?  For instance, for real-time look up of data over the network, mobile app performance depends on network latency and server infrastructure capabilities.  If consistent performance is required, data would typically need to be cached, which is supported on hybrid or native applications only. Connectivity and Availability: What sort of connectivity will your application require? Does the app require Web access all the time in order to always retrieve the latest data from the server? Or do the requirements dictate offline support? While native and hybrid apps can be built to operate offline, Web mobile apps require Web connectivity. Multi-platform Requirements: The terms “consumerization of IT” and BYOD (bring your own device) effectively mean that the line between the consumer and the enterprise devices have become blurred. Employees are bringing their personal mobile devices to work and are often expecting that they work in the corporate network and access back-office applications.  Even if companies restrict access to the big dogs: (iPad, iPhone, Android phones and tablets, possibly Windows Phone and tablets), trying to support each platform natively will require increasing resources and domain expertise with each new language/platform. And let’s not forget the maintenance costs, involved in upgrading new versions of each platform.   Where multi-platform support is needed, Web mobile or hybrid apps probably have the advantage. Going native, and trying to support multiple operating systems may be cost prohibitive with existing resources and developer skills. Device-Services Access:  If your app needs to access local device services, such as the camera, contacts app, accelerometer, etc., then your choices are limited to native or hybrid applications.   Fragmentation: Apple controls Apple iOS and the only concern is what version iOS is running on any given device.   Not so Android, which is open source. There are many, many versions and variants of Android running on different devices, which can be a nightmare for app developers trying to support different devices running different flavors of Android.  (Is it an Amazon Kindle Fire? a Samsung Galaxy?  A Barnes & Noble Nook?) This is a nightmare scenario for native apps—on the other hand, a mobile Web or hybrid app, when properly designed, can shield you from these complexities because they are based on common frameworks.  Resources: How many developers can you dedicate to building and supporting mobile application development?  What are their existing skills sets?  If you’re considering native application development due to the complexity of the application under development, factor the costs of becoming proficient on a each platform’s OS and programming language. Add another platform, and that’s another language, another SDK. On the other side of the equation, Web mobile or hybrid applications are simpler to make, and readily support more platforms, but there may be performance trade-offs. Conclusion This only scratches the surface. However, I hope to have suggested some food for thought in choosing your mobile development strategy.  Do your due diligence, search the Web, read up on mobile, talk to peers, attend events. The development team at Oracle is working hard on mobile technologies to help customers extend enterprise applications to mobile faster and effectively.  To learn more on what Oracle has to offer, check out the Oracle ADF Mobile (hybrid) and ADF Faces/ADF Mobile browser (Web Mobile) solutions from Oracle.   Additional Information Blog: ADF Blog Product Information on OTN: ADF Mobile Product Information on Oracle.com: Oracle Fusion Middleware Follow us on Twitter and Facebook Subscribe to our regular Fusion Middleware Newsletter

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  • How to Identify Which Hardware Component is Failing in Your Computer

    - by Chris Hoffman
    Concluding that your computer has a hardware problem is just the first step. If you’re dealing with a hardware issue and not a software issue, the next step is determining what hardware problem you’re actually dealing with. If you purchased a laptop or pre-built desktop PC and it’s still under warranty, you don’t need to care about this. Have the manufacturer fix the PC for you — figuring it out is their problem. If you’ve built your own PC or you want to fix a computer that’s out of warranty, this is something you’ll need to do on your own. Blue Screen 101: Search for the Error Message This may seem like obvious advice, but searching for information about a blue screen’s error message can help immensely. Most blue screens of death you’ll encounter on modern versions of Windows will likely be caused by hardware failures. The blue screen of death often displays information about the driver that crashed or the type of error it encountered. For example, let’s say you encounter a blue screen that identified “NV4_disp.dll” as the driver that caused the blue screen. A quick Google search will reveal that this is the driver for NVIDIA graphics cards, so you now have somewhere to start. It’s possible that your graphics card is failing if you encounter such an error message. Check Hard Drive SMART Status Hard drives have a built in S.M.A.R.T. (Self-Monitoring, Analysis, and Reporting Technology) feature. The idea is that the hard drive monitors itself and will notice if it starts to fail, providing you with some advance notice before the drive fails completely. This isn’t perfect, so your hard drive may fail even if SMART says everything is okay. If you see any sort of “SMART error” message, your hard drive is failing. You can use SMART analysis tools to view the SMART health status information your hard drives are reporting. Test Your RAM RAM failure can result in a variety of problems. If the computer writes data to RAM and the RAM returns different data because it’s malfunctioning, you may see application crashes, blue screens, and file system corruption. To test your memory and see if it’s working properly, use Windows’ built-in Memory Diagnostic tool. The Memory Diagnostic tool will write data to every sector of your RAM and read it back afterwards, ensuring that all your RAM is working properly. Check Heat Levels How hot is is inside your computer? Overheating can rsult in blue screens, crashes, and abrupt shut downs. Your computer may be overheating because you’re in a very hot location, it’s ventilated poorly, a fan has stopped inside your computer, or it’s full of dust. Your computer monitors its own internal temperatures and you can access this information. It’s generally available in your computer’s BIOS, but you can also view it with system information utilities such as SpeedFan or Speccy. Check your computer’s recommended temperature level and ensure it’s within the appropriate range. If your computer is overheating, you may see problems only when you’re doing something demanding, such as playing a game that stresses your CPU and graphics card. Be sure to keep an eye on how hot your computer gets when it performs these demanding tasks, not only when it’s idle. Stress Test Your CPU You can use a utility like Prime95 to stress test your CPU. Such a utility will fore your computer’s CPU to perform calculations without allowing it to rest, working it hard and generating heat. If your CPU is becoming too hot, you’ll start to see errors or system crashes. Overclockers use Prime95 to stress test their overclock settings — if Prime95 experiences errors, they throttle back on their overclocks to ensure the CPU runs cooler and more stable. It’s a good way to check if your CPU is stable under load. Stress Test Your Graphics Card Your graphics card can also be stress tested. For example, if your graphics driver crashes while playing games, the games themselves crash, or you see odd graphical corruption, you can run a graphics benchmark utility like 3DMark. The benchmark will stress your graphics card and, if it’s overheating or failing under load, you’ll see graphical problems, crashes, or blue screens while running the benchmark. If the benchmark seems to work fine but you have issues playing a certain game, it may just be a problem with that game. Swap it Out Not every hardware problem is easy to diagnose. If you have a bad motherboard or power supply, their problems may only manifest through occasional odd issues with other components. It’s hard to tell if these components are causing problems unless you replace them completely. Ultimately, the best way to determine whether a component is faulty is to swap it out. For example, if you think your graphics card may be causing your computer to blue screen, pull the graphics card out of your computer and swap in a new graphics card. If everything is working well, it’s likely that your previous graphics card was bad. This isn’t easy for people who don’t have boxes of components sitting around, but it’s the ideal way to troubleshoot. Troubleshooting is all about trial and error, and swapping components out allows you to pin down which component is actually causing the problem through a process of elimination. This isn’t a complete guide to everything that could likely go wrong and how to identify it — someone could write a full textbook on identifying failing components and still not cover everything. But the tips above should give you some places to start dealing with the more common problems. Image Credit: Justin Marty on Flickr     

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  • therubyracer on Ubuntu install issues with ruby-2.0.0-p247

    - by Victor S
    I can't seem to get therubyracer gem installed on ubuntu, i get the following errors, anyone can help? ERROR: Error installing therubyracer: ERROR: Failed to build gem native extension. /home/victorstan/.rvm/rubies/ruby-2.0.0-p247/bin/ruby extconf.rb checking for main() in -lpthread... yes creating Makefile make compiling constraints.cc compiling array.cc compiling value.cc compiling invocation.cc compiling primitive.cc compiling trycatch.cc compiling context.cc compiling exception.cc compiling template.cc compiling accessor.cc compiling object.cc compiling script.cc compiling external.cc compiling stack.cc compiling gc.cc compiling backref.cc compiling heap.cc compiling v8.cc compiling constants.cc compiling date.cc compiling function.cc compiling rr.cc compiling message.cc compiling init.cc compiling string.cc compiling handles.cc compiling signature.cc compiling locker.cc linking shared-object v8/init.so g++: /home/victorstan/.rvm/gems/ruby-2.0.0-p247@global/gems/libv8-3.11.8.17-x86_64-linux/vendor/v8/out/ia32.release/obj.target/tools/gyp/libv8_base.a: No such file or directory g++: /home/victorstan/.rvm/gems/ruby-2.0.0-p247@global/gems/libv8-3.11.8.17-x86_64-linux/vendor/v8/out/ia32.release/obj.target/tools/gyp/libv8_snapshot.a: No such file or directory make: *** [init.so] Error 1 Update It seems it's trying to use a 32 bit library instead of a 64 bit library, anyone else experience issue trying to install 64 bit applications and packages on Ubuntu, and it trying to install 32 bit version instead (even though the system is a 64 Linux)? Related: https://github.com/cowboyd/therubyracer/issues/262

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