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  • unable to sniff traffic despite network interface being in monitor or promiscuous mode

    - by user65126
    I'm trying to sniff out my network's wireless traffic but am having issues. I'm able to put the card in monitor mode, but am unable to see any traffic except broadcasts, multicasts and probe/beacon frames. I have two network interfaces on this laptop. One is connected normally to 'linksys' and the other is in monitor mode. The interface in monitor mode is on the right channel. I'm not associated with the access point because, as I understand, I don't need to if using monitor mode (vs promiscuous). When I try to ping the router ip, I'm not seeing that traffic show up in wireshark. Here's my ifconfig settings: daniel@seasonBlack:~$ ifconfig eth0 Link encap:Ethernet HWaddr 00:1f:29:9e:b2:89 UP BROADCAST MULTICAST MTU:1500 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:0 (0.0 B) TX bytes:0 (0.0 B) Interrupt:16 lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:112 errors:0 dropped:0 overruns:0 frame:0 TX packets:112 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:8518 (8.5 KB) TX bytes:8518 (8.5 KB) wlan0 Link encap:Ethernet HWaddr 00:21:00:34:f7:f4 inet addr:192.168.1.116 Bcast:192.168.1.255 Mask:255.255.255.0 inet6 addr: fe80::221:ff:fe34:f7f4/64 Scope:Link UP BROADCAST RUNNING MTU:1500 Metric:1 RX packets:9758 errors:0 dropped:0 overruns:0 frame:0 TX packets:4869 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:3291516 (3.2 MB) TX bytes:677386 (677.3 KB) wlan1 Link encap:UNSPEC HWaddr 00-02-72-7B-92-53-33-34-00-00-00-00-00-00-00-00 UP BROADCAST NOTRAILERS PROMISC ALLMULTI MTU:1500 Metric:1 RX packets:112754 errors:0 dropped:0 overruns:0 frame:0 TX packets:101 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:18569124 (18.5 MB) TX bytes:12874 (12.8 KB) wmaster0 Link encap:UNSPEC HWaddr 00-21-00-34-F7-F4-00-00-00-00-00-00-00-00-00-00 UP RUNNING MTU:0 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:0 (0.0 B) TX bytes:0 (0.0 B) wmaster1 Link encap:UNSPEC HWaddr 00-02-72-7B-92-53-00-00-00-00-00-00-00-00-00-00 UP RUNNING MTU:0 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:0 (0.0 B) TX bytes:0 (0.0 B) Here's my iwconfig settings: daniel@seasonBlack:~$ iwconfig lo no wireless extensions. eth0 no wireless extensions. wmaster0 no wireless extensions. wlan0 IEEE 802.11bg ESSID:"linksys" Mode:Managed Frequency:2.437 GHz Access Point: 00:18:F8:D6:17:34 Bit Rate=54 Mb/s Tx-Power=27 dBm Retry long limit:7 RTS thr:off Fragment thr:off Power Management:off Link Quality=68/70 Signal level=-42 dBm Noise level=-69 dBm Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0 Tx excessive retries:0 Invalid misc:0 Missed beacon:0 wmaster1 no wireless extensions. wlan1 IEEE 802.11bg Mode:Monitor Frequency:2.437 GHz Tx-Power=27 dBm Retry long limit:7 RTS thr:off Fragment thr:off Power Management:off Link Quality:0 Signal level:0 Noise level:0 Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0 Tx excessive retries:0 Invalid misc:0 Missed beacon:0 Here's how I know I'm on the right channel: daniel@seasonBlack:~$ iwlist channel lo no frequency information. eth0 no frequency information. wmaster0 no frequency information. wlan0 11 channels in total; available frequencies : Channel 01 : 2.412 GHz Channel 02 : 2.417 GHz Channel 03 : 2.422 GHz Channel 04 : 2.427 GHz Channel 05 : 2.432 GHz Channel 06 : 2.437 GHz Channel 07 : 2.442 GHz Channel 08 : 2.447 GHz Channel 09 : 2.452 GHz Channel 10 : 2.457 GHz Channel 11 : 2.462 GHz Current Frequency=2.437 GHz (Channel 6) wmaster1 no frequency information. wlan1 11 channels in total; available frequencies : Channel 01 : 2.412 GHz Channel 02 : 2.417 GHz Channel 03 : 2.422 GHz Channel 04 : 2.427 GHz Channel 05 : 2.432 GHz Channel 06 : 2.437 GHz Channel 07 : 2.442 GHz Channel 08 : 2.447 GHz Channel 09 : 2.452 GHz Channel 10 : 2.457 GHz Channel 11 : 2.462 GHz Current Frequency=2.437 GHz (Channel 6)

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  • Moving users folder on Windows-7 to another partition - bad idea?

    - by Donat
    Hi, I'd like to re-submit here a question posted by Benjol on Aug 17at 5:57 "Moving users folder on Windows Vista to another partition - bad idea?" (I can't post one than one link until I earn "10 reputation" and removed my "answer" there to post my follow-up questions here). I am anxiously getting ready at long last to to carry out a clean install (using custom install option) from Vista to Windows-7 Home Premium 64bit with the free upgrade I received late October. For my Vista system I successfully set-up last Summer a multi-partitions scheme with Users and Program Data on a a different partition than the operating system (see link below, and its subsequent links in my comment for details). http://tuts4tech.net/2009/08/05/windows-7-move-the-users-and-program-files-directories-to-a-different-partition/comment-page-1/#comment-562 I was planning a similar set-up for windows 7, a little more streamlined, with OS, Program Files on C:, Users and Program Data on D:, and TV media recording on a separate partition. Reading the Question submitted by Benjol, I am second guessing too. Is moving Users and Program Data on a different partition than the default primary partition with OS and Program Files such a good idea? The couple of people I talked to at the official Microsoft Windows 7 booth at CES 2010 gave the same answer to the intention of moving the Users profile folder to another partition. In a nutshell, they all told me that they used to do this in XP and less in Vista but not anymore with Windows 7... "It is stable, after two months still no problem" I had the feeling it was a scripted answer to emphasize how Windows 7 is so stable and efficient... (Will Windows-7 system not become bugged down over the course of several months to a year or two? Only time will tell) Long story short, I share the same view than Benjol expressed with respect to being "able to backup and restore system and user data independently." I just received a 2TB usb2, eSATA external hard drive as a back-up drive, which includes NTI Shadow 4 (4.1.0.150) for back-up solution. I took note of the issue with NTUSER.DAT and I will read more about Volume Shadow Copy Service (VSS) for Windows 7. I am willing to put the effort if placing Users and Program Data on a different partition would allow to restore a fresher OS+Program image when the system gets bugged down. Questions: Is it such a bad idea? What is the "easy route" referred by Benjol in his post? Is it to just relocate folders to another partition using the Folder property tool? (It is not practical for several users and might not provide a straightforward restore process of just OS and Program Files when needed.) I am starting to learn about Windows 7 libraries. Would Windows 7 libraries be another alternative to achieve this? All this reading to decide how to organize the partition scheme for my custom system is starting to be confusing. I apologize for this lengthy Question. It is my first day here on SuperUser and I am just learning how different from a discussion thread it is. Thank you in advance for all your suggestions and comments. Donat

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  • Issues configuring Exchange 2010 as well as SSL problems.

    - by Eric Smith
    Possibly-Relevant Background Info: I've recently moved up from icky shared hosting to a glorious, Remote Desktop-administrated VPS server running Windows Server 2008 R2. Even though I'm only 21 now and a computer science major, I've tried to play with every Windows Server release since '03, just to learn new things. What usually happens is inevitably I'll do something wrong and pretty much ruin the install. You're dealing with an amateur here :) Through the past few months of working with my new server, I've mastered DNS, IIS, got Team Foundation Server running (yay!), and can install all of the other basics like SQL Server and Active Directory. The Problem: Now, these last few weeks I've been trying to install Exchange Server 2010 (SP1). To make a long story short, it took me several attempts, and I even had to get my server wiped just so I could start fresh since Exchange decided uninstalling properly was for sissies (cost me $20, bah). Today, at long last, I got Exchange mostly working. There were two main problems left, however, that left me unsatisfied: Exchange installed itself and all of its child sites into Default Web Site. I wanted to access Exchange via mail.domain.com, but instead everything was configured to domain.com. My limited server admin knowledge was not enough to configure IIS or Exchange to move itself over to the website I had set up for it, appropriately titled 'mail.domain.com', which I had bound to a dedicated IP address (I was told this was necessary, but he may have been wrong). I have two SSL certificates: one for my main domain and one for my mail subdomain. For whatever reason, I had issues geting Exchange to use my mail certificate, even though I had assigned the proper roles in the MMC. I did, at one point, get it to work (or mostly work, anyways. Frankly, my memory of today is clouded by intense frustration). Additionally, I was confused which type of SSL certificate I should be using for Exchange. My SSL provider, GoDaddy, allows me to request a new certificate whenever, so I can use either the certificate request provided by IIS or the more complicated and specific request you can create with Exchange. Which type should I be using, the IIS or Exchange certificate? If I must use the Exchange certificate, will that 1) cause issues when I bind that certificate to my mail.domain.com subdomain or 2) is that an unnecessary step? The SSL Certificate Strikes Back When I thought I had the proper SSL certificate assigned for those brief, sweet moments, Google Chrome reported the correct mail.domain.com certificate when browsing https://mail.domain.com. However, Outlook 2010 threw up an error when trying to configure my email account claiming that the certificate didn't match the domain of "mail.domain.com". Is this an issue that will be resolved by problem #2 or is it a separate one entirely? Apologies for the massive wall of text, but I wanted to provide as much info as I possibly could. Exchange is the last thing I'd like installed on my server, and naturally it's turning out to be the hardest. Thanks for any info at all. Even a point in a vague direction would be a huge help at this point. Thanks! -Eric P.S.: The reason I keep ruining my install is that when I attempt to uninstall Exchange, something invariably goes wrong. The last time the uninstaller complained that there was still a mailbox active and it couldn't proceed until I deleted it. ... The only mailbox left was the Administrator account, the built-in one I couldn't delete. So I attempted to manually uninstall it following several guides online only to now be stuck unable to launch the installer and have to get my system wiped AGAIN for the second time today ($40 down the drain, bah!). I do not understand at all why "uninstall" just can't mean "hey, you, delete everything and go away". There's not even a force uninstall option, only a "recover system" option that just fails to fix anything and makes it so I can't even use the GUI uninstaller. </rant>

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  • CPU/JVM/JBoss 7 slows down over time

    - by lukas
    I'm experiencing performance slow down on JBoss 7.1.1 Final. I wrote simple program that demostrates this behavior. I generate an array of 100,000 of random integers and run bubble sort on it. @Model public class PerformanceTest { public void proceed() { long now = System.currentTimeMillis(); int[] arr = new int[100000]; for(int i = 0; i < arr.length; i++) { arr[i] = (int) (Math.random() * 200000); } long now2 = System.currentTimeMillis(); System.out.println((now2 - now) + "ms took to generate array"); now = System.currentTimeMillis(); bubbleSort(arr); now2 = System.currentTimeMillis(); System.out.println((now2 - now) + "ms took to bubblesort array"); } public void bubbleSort(int[] arr) { boolean swapped = true; int j = 0; int tmp; while (swapped) { swapped = false; j++; for (int i = 0; i < arr.length - j; i++) { if (arr[i] > arr[i + 1]) { tmp = arr[i]; arr[i] = arr[i + 1]; arr[i + 1] = tmp; swapped = true; } } } } } Just after I start the server, it takes approximately 22 seconds to run this code. After few days of JBoss 7.1.1. running, it takes 330 sec to run this code. In both cases, I launch the code when the CPU utilization is very low (say, 1%). Any ideas why? I run the server with following arguments: -Xms1280m -Xmx2048m -XX:MaxPermSize=2048m -Djava.net.preferIPv4Stack=true -Dorg.jboss.resolver.warning=true -Dsun.rmi.dgc.client.gcInterval=3600000 -Dsun.rmi.dgc.server.gcInterval=3600000 -Djboss.modules.system.pkgs=org.jboss.byteman -Djava.awt.headless=true -Duser.timezone=UTC -Djboss.server.default.config=standalone-full.xml -Xrunjdwp:transport=dt_socket,address=8787,server=y,suspend=n I'm running it on Linux 2.6.32-279.11.1.el6.x86_64 with java version "1.7.0_07". It's within J2EE applicaiton. I use CDI so I have a button on JSF page that will call method "proceed" on @RequestScoped component PerformanceTest. I deploy this as separate war file and even if I undeploy other applications, it doesn't change the performance. It's a virtual machine that is sharing CPUs with another machine but that one doesn't consume anything. Here's yet another observation: when the server is after fresh start and I run the bubble sort, It utilizes 100% of one processor core. It never switches to another core or drops utilization below 95%. However after some time the server is running and I'm experiencing the performance problems, the method above is utilizing CPU core usually 100%, however I just found out from htop that this task is being switched very often to other cores. That is, at the beginning it's running on core #1, after say 2 seconds it's running on #5 then after say 2 seconds #8 etc. Furthermore, the utilization is not kept at 100% at the core but sometimes drops to 80% or even lower. For the server after fresh start, even though If I simulate a load, it never switches the task to another core.

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  • File copying utility like rsync with error handling like ddrescue, for data recovery from a hard drive with bad sectors or hardware failure

    - by purefusion
    I have a hard drive with either bad blocks or sectors that are failing to read due to potential mechanical issues, such as a bad disk head, bad motor, or some other issue that is causing the hard drive to read data excruciatingly slowly and with lots of read errors. I'm seeing an average of 50 KB/sec, with some reads dropping below 10 KB/sec, and frequently it gets stuck on a file or sector altogether, usually for quite a long time—from 2-10 minutes or more (when using rsync, before it times out). Speed seems to vary wildly, and it gets stuck on files a lot, and when it finally gets "unstuck" it only seems to last for a short burst before it gets stuck again. The drive is also very quiet with only an occasional sound of files copying (usually when it gets stuck/unstuck for a brief time, before getting stuck again). Thus, there are none of those evil sounds that are normally associated with HDD death. Someone suggested that the problems sounded like they might be caused by a misaligned disk head, which requires a lot of re-reads before it finally reads data with success. Sounds plausible, but I digress... Anyway, the problem with rsync is that it seems to have no decent error handling support. Obviously, it wasn't meant for use in recovering data from failing hard drives, but all the so-called "data recovery" utilities out there that are meant for such use usually focus on recovery of deleted files or messed up partitions, rather than copying files off dying hard drives. Deleted file recovery is not what I need, obviously, so perhaps you can understand my disappointment in not being able to find what I'm after yet. Naturally, this is where you'd probably say "You should use ddrescue!" Well, that's all fine and dandy, but I've already got most of the data backed up, so I just want to recover certain files. I'm not concerned with trying to recover a full partition block-by-block as ddrescue does. I am only interested in rescuing just specific files and directories. Ideally, what I'd like is some sort of cross between rsync and ddrescue: something that lets me specify source and destination as directories of normal files like rsync (rather than two full partitions as ddrescue requires), with a way to skip files with errors in an initial run, and then allows me to attempt recovery of those files with errors in a later run (with a slightly altered command, of course), perhaps even offering an option to specify the number of retry attempts ...just like how ddrescue works with blocks, only I want a utility that works with specific files/directories like rsync does. So am I daydreaming here, or does something out there exist that can do this? Or, maybe even a way to make rsync or ddrescue work in such a way? I'm really open to whatever solutions might work, so long as they let me choose which files I want to "rescue", and can skip files with errors in the initial run, and try/retry those errors again later. So far I've tried rsync with the following options, but it often gets stuck on a file for longer than the timeout, and ideally I'd just like it to move on to the next file and come back later to the files it gets stuck on. I don't think that's possible though. Anyway, here's what I've been using up till now: rsync -avP --stats --block-size=512 --timeout=600 /path/to/source/* /path/to/destination/

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  • Parallel processing slower than sequential?

    - by zebediah49
    EDIT: For anyone who stumbles upon this in the future: Imagemagick uses a MP library. It's faster to use available cores if they're around, but if you have parallel jobs, it's unhelpful. Do one of the following: do your jobs serially (with Imagemagick in parallel mode) set MAGICK_THREAD_LIMIT=1 for your invocation of the imagemagick binary in question. By making Imagemagick use only one thread, it slows down by 20-30% in my test cases, but meant I could run one job per core without issues, for a significant net increase in performance. Original question: While converting some images using ImageMagick, I noticed a somewhat strange effect. Using xargs was significantly slower than a standard for loop. Since xargs limited to a single process should act like a for loop, I tested that, and found it to be about the same. Thus, we have this demonstration. Quad core (AMD Athalon X4, 2.6GHz) Working entirely on a tempfs (16g ram total; no swap) No other major loads Results: /media/ramdisk/img$ time for f in *.bmp; do echo $f ${f%bmp}png; done | xargs -n 2 -P 1 convert -auto-level real 0m3.784s user 0m2.240s sys 0m0.230s /media/ramdisk/img$ time for f in *.bmp; do echo $f ${f%bmp}png; done | xargs -n 2 -P 2 convert -auto-level real 0m9.097s user 0m28.020s sys 0m0.910s /media/ramdisk/img$ time for f in *.bmp; do echo $f ${f%bmp}png; done | xargs -n 2 -P 10 convert -auto-level real 0m9.844s user 0m33.200s sys 0m1.270s Can anyone think of a reason why running two instances of this program takes more than twice as long in real time, and more than ten times as long in processor time to complete the same task? After that initial hit, more processes do not seem to have as significant of an effect. I thought it might have to do with disk seeking, so I did that test entirely in ram. Could it have something to do with how Convert works, and having more than one copy at once means it cannot use processor cache as efficiently or something? EDIT: When done with 1000x 769KB files, performance is as expected. Interesting. /media/ramdisk/img$ time for f in *.bmp; do echo $f ${f%bmp}png; done | xargs -n 2 -P 1 convert -auto-level real 3m37.679s user 5m6.980s sys 0m6.340s /media/ramdisk/img$ time for f in *.bmp; do echo $f ${f%bmp}png; done | xargs -n 2 -P 1 convert -auto-level real 3m37.152s user 5m6.140s sys 0m6.530s /media/ramdisk/img$ time for f in *.bmp; do echo $f ${f%bmp}png; done | xargs -n 2 -P 2 convert -auto-level real 2m7.578s user 5m35.410s sys 0m6.050s /media/ramdisk/img$ time for f in *.bmp; do echo $f ${f%bmp}png; done | xargs -n 2 -P 4 convert -auto-level real 1m36.959s user 5m48.900s sys 0m6.350s /media/ramdisk/img$ time for f in *.bmp; do echo $f ${f%bmp}png; done | xargs -n 2 -P 10 convert -auto-level real 1m36.392s user 5m54.840s sys 0m5.650s

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  • How do I connect my Windows XP laptop to the internet?

    - by rubysiddhi
    Hello fellow super users, The Past I have a Acer Travelmate 2300 laptop running Windows XP. 6 months ago I moved into a new apartment and got a new internet connection set up. After getting an internet connection installed in my apartment I reinstalled Windows XP and at the same time wiped my drive clean losing all the original Acer software and drivers. Once XP was reinstalled I had to find all the drivers again to get the Travelmate laptop connected to the internet. So, using my Vista laptop which was connected fine, I went to the Acer Travelmate Series drivers download page to download the necessary drivers. I transferred them to my Acer XP machine and installed them the best I could (there were no easy instructions so I just had to find all the executables and run them). I eventually got connected to the internet but not exactly in the way I had hoped for. The Present To be connected to the internet I need to have an Ethernet cord connecting my computer (via the Ethernet port) to my router. This is a problem since it defeats the purpose of having a Wireless LAN card in my Acer laptop. One of the programs I downloaded from the Acer Travelmate Series page was the Acer Wireless LAN Configuration Utility. This program allows me to see the current network I am connected to and all the available networks I could potentially connect to. It reminds me of XP's Wireless Network Connection window/utility where you can see all available wireless networks, refresh the network list and connect to one of the networks. I should mention that my ISP set up a security enabled wireless network with WPA. This network requires a network key if you want to connect to it. I guess my Vista computer has the network key entered into it already. The problem is that I do not know what the network key is. Now obviously you would say just contact my ISP to get the key. And I will but there is just one extra weird issue. I am able to connect to another unsecured wireless network in the Wireless Network Connection window/utility. I can be on it as long as my Ethernet cable is plugged in. So this is not really wireless is it? And this indicates that even if I do get that network key password from my ISP, I will only solve one of the two problems I have. I will only solve being able to get online as long as I am connected to my router via the Ethernet cable. The Main Questions So how do I enable my acer IPN2220 Wireless LAN Card so that I can use my Acer laptop from anywhere with in my apartment? Or should I first get the network key from my ISP to access my security enabled wireless network? And then deal with getting the acer IPN2220 Wireless LAN Card working? Hard & Learned VS Easy & Stupid Of course contacting the ISP would be easier. Have em just come in here and do there thing. The problem with that is that they do not speak English (yeah, im in Poland) and it'd be a hell of a time trying to understand what they are doing (uncomfortable looking over their shoulder). Also, I want to learn how to do this task myself so that I can fix the problem if it ever happens again. You know, be more self sufficient. I look forward to helpful replies. Thanks, Xaviour

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  • The dynamic Type in C# Simplifies COM Member Access from Visual FoxPro

    - by Rick Strahl
    I’ve written quite a bit about Visual FoxPro interoperating with .NET in the past both for ASP.NET interacting with Visual FoxPro COM objects as well as Visual FoxPro calling into .NET code via COM Interop. COM Interop with Visual FoxPro has a number of problems but one of them at least got a lot easier with the introduction of dynamic type support in .NET. One of the biggest problems with COM interop has been that it’s been really difficult to pass dynamic objects from FoxPro to .NET and get them properly typed. The only way that any strong typing can occur in .NET for FoxPro components is via COM type library exports of Visual FoxPro components. Due to limitations in Visual FoxPro’s type library support as well as the dynamic nature of the Visual FoxPro language where few things are or can be described in the form of a COM type library, a lot of useful interaction between FoxPro and .NET required the use of messy Reflection code in .NET. Reflection is .NET’s base interface to runtime type discovery and dynamic execution of code without requiring strong typing. In FoxPro terms it’s similar to EVALUATE() functionality albeit with a much more complex API and corresponiding syntax. The Reflection APIs are fairly powerful, but they are rather awkward to use and require a lot of code. Even with the creation of wrapper utility classes for common EVAL() style Reflection functionality dynamically access COM objects passed to .NET often is pretty tedious and ugly. Let’s look at a simple example. In the following code I use some FoxPro code to dynamically create an object in code and then pass this object to .NET. An alternative to this might also be to create a new object on the fly by using SCATTER NAME on a database record. How the object is created is inconsequential, other than the fact that it’s not defined as a COM object – it’s a pure FoxPro object that is passed to .NET. Here’s the code: *** Create .NET COM InstanceloNet = CREATEOBJECT('DotNetCom.DotNetComPublisher') *** Create a Customer Object Instance (factory method) loCustomer = GetCustomer() loCustomer.Name = "Rick Strahl" loCustomer.Company = "West Wind Technologies" loCustomer.creditLimit = 9999999999.99 loCustomer.Address.StreetAddress = "32 Kaiea Place" loCustomer.Address.Phone = "808 579-8342" loCustomer.Address.Email = "[email protected]" *** Pass Fox Object and echo back values ? loNet.PassRecordObject(loObject) RETURN FUNCTION GetCustomer LOCAL loCustomer, loAddress loCustomer = CREATEOBJECT("EMPTY") ADDPROPERTY(loCustomer,"Name","") ADDPROPERTY(loCustomer,"Company","") ADDPROPERTY(loCUstomer,"CreditLimit",0.00) ADDPROPERTY(loCustomer,"Entered",DATETIME()) loAddress = CREATEOBJECT("Empty") ADDPROPERTY(loAddress,"StreetAddress","") ADDPROPERTY(loAddress,"Phone","") ADDPROPERTY(loAddress,"Email","") ADDPROPERTY(loCustomer,"Address",loAddress) RETURN loCustomer ENDFUNC Now prior to .NET 4.0 you’d have to access this object passed to .NET via Reflection and the method code to do this would looks something like this in the .NET component: public string PassRecordObject(object FoxObject) { // *** using raw Reflection string Company = (string) FoxObject.GetType().InvokeMember( "Company", BindingFlags.GetProperty,null, FoxObject,null); // using the easier ComUtils wrappers string Name = (string) ComUtils.GetProperty(FoxObject,"Name"); // Getting Address object – then getting child properties object Address = ComUtils.GetProperty(FoxObject,"Address");    string Street = (string) ComUtils.GetProperty(FoxObject,"StreetAddress"); // using ComUtils 'Ex' functions you can use . Syntax     string StreetAddress = (string) ComUtils.GetPropertyEx(FoxObject,"AddressStreetAddress"); return Name + Environment.NewLine + Company + Environment.NewLine + StreetAddress + Environment.NewLine + " FOX"; } Note that the FoxObject is passed in as type object which has no specific type. Since the object doesn’t exist in .NET as a type signature the object is passed without any specific type information as plain non-descript object. To retrieve a property the Reflection APIs like Type.InvokeMember or Type.GetProperty().GetValue() etc. need to be used. I made this code a little simpler by using the Reflection Wrappers I mentioned earlier but even with those ComUtils calls the code is pretty ugly requiring passing the objects for each call and casting each element. Using .NET 4.0 Dynamic Typing makes this Code a lot cleaner Enter .NET 4.0 and the dynamic type. Replacing the input parameter to the .NET method from type object to dynamic makes the code to access the FoxPro component inside of .NET much more natural: public string PassRecordObjectDynamic(dynamic FoxObject) { // *** using raw Reflection string Company = FoxObject.Company; // *** using the easier ComUtils class string Name = FoxObject.Name; // *** using ComUtils 'ex' functions to use . Syntax string Address = FoxObject.Address.StreetAddress; return Name + Environment.NewLine + Company + Environment.NewLine + Address + Environment.NewLine + " FOX"; } As you can see the parameter is of type dynamic which as the name implies performs Reflection lookups and evaluation on the fly so all the Reflection code in the last example goes away. The code can use regular object ‘.’ syntax to reference each of the members of the object. You can access properties and call methods this way using natural object language. Also note that all the type casts that were required in the Reflection code go away – dynamic types like var can infer the type to cast to based on the target assignment. As long as the type can be inferred by the compiler at compile time (ie. the left side of the expression is strongly typed) no explicit casts are required. Note that although you get to use plain object syntax in the code above you don’t get Intellisense in Visual Studio because the type is dynamic and thus has no hard type definition in .NET . The above example calls a .NET Component from VFP, but it also works the other way around. Another frequent scenario is an .NET code calling into a FoxPro COM object that returns a dynamic result. Assume you have a FoxPro COM object returns a FoxPro Cursor Record as an object: DEFINE CLASS FoxData AS SESSION OlePublic cAppStartPath = "" FUNCTION INIT THIS.cAppStartPath = ADDBS( JustPath(Application.ServerName) ) SET PATH TO ( THIS.cAppStartpath ) ENDFUNC FUNCTION GetRecord(lnPk) LOCAL loCustomer SELECT * FROM tt_Cust WHERE pk = lnPk ; INTO CURSOR TCustomer IF _TALLY < 1 RETURN NULL ENDIF SCATTER NAME loCustomer MEMO RETURN loCustomer ENDFUNC ENDDEFINE If you call this from a .NET application you can now retrieve this data via COM Interop and cast the result as dynamic to simplify the data access of the dynamic FoxPro type that was created on the fly: int pk = 0; int.TryParse(Request.QueryString["id"],out pk); // Create Fox COM Object with Com Callable Wrapper FoxData foxData = new FoxData(); dynamic foxRecord = foxData.GetRecord(pk); string company = foxRecord.Company; DateTime entered = foxRecord.Entered; This code looks simple and natural as it should be – heck you could write code like this in days long gone by in scripting languages like ASP classic for example. Compared to the Reflection code that previously was necessary to run similar code this is much easier to write, understand and maintain. For COM interop and Visual FoxPro operation dynamic type support in .NET 4.0 is a huge improvement and certainly makes it much easier to deal with FoxPro code that calls into .NET. Regardless of whether you’re using COM for calling Visual FoxPro objects from .NET (ASP.NET calling a COM component and getting a dynamic result returned) or whether FoxPro code is calling into a .NET COM component from a FoxPro desktop application. At one point or another FoxPro likely ends up passing complex dynamic data to .NET and for this the dynamic typing makes coding much cleaner and more readable without having to create custom Reflection wrappers. As a bonus the dynamic runtime that underlies the dynamic type is fairly efficient in terms of making Reflection calls especially if members are repeatedly accessed. © Rick Strahl, West Wind Technologies, 2005-2010Posted in COM  FoxPro  .NET  CSharp  

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  • Parallelism in .NET – Part 10, Cancellation in PLINQ and the Parallel class

    - by Reed
    Many routines are parallelized because they are long running processes.  When writing an algorithm that will run for a long period of time, its typically a good practice to allow that routine to be cancelled.  I previously discussed terminating a parallel loop from within, but have not demonstrated how a routine can be cancelled from the caller’s perspective.  Cancellation in PLINQ and the Task Parallel Library is handled through a new, unified cooperative cancellation model introduced with .NET 4.0. Cancellation in .NET 4 is based around a new, lightweight struct called CancellationToken.  A CancellationToken is a small, thread-safe value type which is generated via a CancellationTokenSource.  There are many goals which led to this design.  For our purposes, we will focus on a couple of specific design decisions: Cancellation is cooperative.  A calling method can request a cancellation, but it’s up to the processing routine to terminate – it is not forced. Cancellation is consistent.  A single method call requests a cancellation on every copied CancellationToken in the routine. Let’s begin by looking at how we can cancel a PLINQ query.  Supposed we wanted to provide the option to cancel our query from Part 6: double min = collection .AsParallel() .Min(item => item.PerformComputation()); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } We would rewrite this to allow for cancellation by adding a call to ParallelEnumerable.WithCancellation as follows: var cts = new CancellationTokenSource(); // Pass cts here to a routine that could, // in parallel, request a cancellation try { double min = collection .AsParallel() .WithCancellation(cts.Token) .Min(item => item.PerformComputation()); } catch (OperationCanceledException e) { // Query was cancelled before it finished } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Here, if the user calls cts.Cancel() before the PLINQ query completes, the query will stop processing, and an OperationCanceledException will be raised.  Be aware, however, that cancellation will not be instantaneous.  When cts.Cancel() is called, the query will only stop after the current item.PerformComputation() elements all finish processing.  cts.Cancel() will prevent PLINQ from scheduling a new task for a new element, but will not stop items which are currently being processed.  This goes back to the first goal I mentioned – Cancellation is cooperative.  Here, we’re requesting the cancellation, but it’s up to PLINQ to terminate. If we wanted to allow cancellation to occur within our routine, we would need to change our routine to accept a CancellationToken, and modify it to handle this specific case: public void PerformComputation(CancellationToken token) { for (int i=0; i<this.iterations; ++i) { // Add a check to see if we've been canceled // If a cancel was requested, we'll throw here token.ThrowIfCancellationRequested(); // Do our processing now this.RunIteration(i); } } With this overload of PerformComputation, each internal iteration checks to see if a cancellation request was made, and will throw an OperationCanceledException at that point, instead of waiting until the method returns.  This is good, since it allows us, as developers, to plan for cancellation, and terminate our routine in a clean, safe state. This is handled by changing our PLINQ query to: try { double min = collection .AsParallel() .WithCancellation(cts.Token) .Min(item => item.PerformComputation(cts.Token)); } catch (OperationCanceledException e) { // Query was cancelled before it finished } PLINQ is very good about handling this exception, as well.  There is a very good chance that multiple items will raise this exception, since the entire purpose of PLINQ is to have multiple items be processed concurrently.  PLINQ will take all of the OperationCanceledException instances raised within these methods, and merge them into a single OperationCanceledException in the call stack.  This is done internally because we added the call to ParallelEnumerable.WithCancellation. If, however, a different exception is raised by any of the elements, the OperationCanceledException as well as the other Exception will be merged into a single AggregateException. The Task Parallel Library uses the same cancellation model, as well.  Here, we supply our CancellationToken as part of the configuration.  The ParallelOptions class contains a property for the CancellationToken.  This allows us to cancel a Parallel.For or Parallel.ForEach routine in a very similar manner to our PLINQ query.  As an example, we could rewrite our Parallel.ForEach loop from Part 2 to support cancellation by changing it to: try { var cts = new CancellationTokenSource(); var options = new ParallelOptions() { CancellationToken = cts.Token }; Parallel.ForEach(customers, options, customer => { // Run some process that takes some time... DateTime lastContact = theStore.GetLastContact(customer); TimeSpan timeSinceContact = DateTime.Now - lastContact; // Check for cancellation here options.CancellationToken.ThrowIfCancellationRequested(); // If it's been more than two weeks, send an email, and update... if (timeSinceContact.Days > 14) { theStore.EmailCustomer(customer); customer.LastEmailContact = DateTime.Now; } }); } catch (OperationCanceledException e) { // The loop was cancelled } Notice that here we use the same approach taken in PLINQ.  The Task Parallel Library will automatically handle our cancellation in the same manner as PLINQ, providing a clean, unified model for cancellation of any parallel routine.  The TPL performs the same aggregation of the cancellation exceptions as PLINQ, as well, which is why a single exception handler for OperationCanceledException will cleanly handle this scenario.  This works because we’re using the same CancellationToken provided in the ParallelOptions.  If a different exception was thrown by one thread, or a CancellationToken from a different CancellationTokenSource was used to raise our exception, we would instead receive all of our individual exceptions merged into one AggregateException.

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  • Tips on installing Visual Studio 2010 SP1

    - by Jon Galloway
    Visual Studio SP1 went up on MSDN downloads (here) on March 8, and will be released publicly on March 10 here. Release announcements: Soma: Visual Studio 2010 enhancements Jason Zander: Announcing Visual Studio 2010 Service Pack 1 I started on this post with tips on installing VS2010 SP1 when I realized I’ve been writing these up for Visual Studio and .NET framework SP releases for a while (e.g. VS2008 / .NET 3.5 SP1 post, VS2005 SP1 post). Looking back the years of Visual Studio SP installs (and remembering when we’d get up to SP6 for a Visual Studio release), I’m happy to see that it just keeps getting easier. Service Packs are a lot less finicky about requiring beta software to be uninstalled, install more quickly, and are just generally a lot less scary. If I can’t have a jetpack, at least my future provided me faster, easier service packs. Disclaimer: These tips are just general things I've picked up over the years. I don't have any inside knowledge here. If you see anything wrong, be sure to let me know in the comments. You may want to check the readme file before installing - it's short, and it's in that new-fangled HTML format. On with the tips! Before starting, uninstall Visual Studio features you don't use Visual Studio service packs (and other Microsoft service packs as well) install patches for the specific features you’ve got installed. This is a big reason to always do a custom install when you first install Visual Studio, but it’s not difficult to update your existing installation. Here’s the quick way to do that: Tap the windows key and type “add or remove programs” and press enter (or click on the “Add or remove programs” link if you must).   Type “Visual Studio 2010” in the search box in the upper right corner, click on the Visual Studio program (the one with the VS infinity looking logo) and click on Uninstall/Change. Click on Add or Remove Features The next part’s up to you – what features do you actually use? I’ve been doing primarily ASP.NET MVC development in C# lately, so I selected Visual C# and Visual Web Developer. Remember that you can install features later if needed, and can also install the express versions if you want. Selecting everything just because it’s there - or you paid for it – means that you install updates for everything, every time. When you’ve made your changes, click on the Update button to uninstall unused features. Shut down all instances of Visual Studio It probably goes without saying that you should close a program down before installing it, partly to avoid the file-in-use-reboot-after-install horror. Additional "hunch / works on my machine" quality tip: On one computer I saw a note in the setup log about Visual Studio a prompt for user input to close Visual Studio, although I never saw the prompt. Just to  be sure, I'd personally open up Task Manager and kill any devenv.exe processes I saw running, as it couldn't hurt. Use the web installer I use the Web Installers whenever possible. There’s no point in downloading the DVD unless you’re doing multiple installs or won’t have internet access. The DVD IS is 1.5GB, since it needs to be able to service every possible supported installation option on both x86 and x64. The web installer is 776 KB (smaller than calc.exe), so you can start the installation right away. Like other web installers, the real benefit is that it only installs the updates you need (hence the reason for step 1 – uninstalling unused components). Instead of 1.5GB, my download was roughly 530MB. If you’re installing from MSDN (this link takes you right to the Visual Studio installs), select the first one on the list: The first step in the installation process is to analyze the machine configuration and tell you what needs to be installed. Since I've trimmed down my features, that's a pretty short list. The time's not far off where I may not install SQL Server on my dev machines, just using SQL Server Compact - that would shorten the list further. When I hit next, you can see that the download size has shrunk considerably. When I start the install, note that the installation begins while other components are downloading - another benefit of the web install. On my mid-range desktop machine, the install took 25 minutes. What if it takes longer? According to Heath Stewart (Visual Studio installer guru), average SP1 installs take roughly 45 minutes. An installation which takes hours to complete may be a sign of a problem: see his post Visual Studio 2010 Service Pack 1 installing for over 2 hours could be a sign of a problem. Why so long? Yes, even 25 minutes is a while. Heath's got another blog post explaining why the update can take longer than the initial install (see: A patch may take as long or longer to install than the target product) which explains all the additional steps and complexities a patch needs to deal with, as well as some mitigation steps that deployment authors can take to mitigate the impact. Other things to know about Visual Studio 2010 SP1 Installs over Visual Studio 2010 SP1 Beta That's nice. Previous Visual Studio versions did a number of annoying things when you installed SP's over beta's - fail with weird errors, get part way through and tell you needed to cancel and uninstall first, etc. I've installed this on two machines that had random beta stuff installed without tears. That Readme file you didn't read I mentioned the readme file earlier (http://go.microsoft.com/fwlink/?LinkId=210711 ). Some interesting things I picked up in there: 2.1.3. Visual Studio 2010 Service Pack 1 installation may fail when a USB drive or other removeable drive is connected 2.1.4. Visual Studio must be restarted after Visual Studio 2010 SP1 tooling for SQL Server Compact (Compact) 4.0 is installed 2.2.1. If Visual Studio 2010 Service Pack 1 is uninstalled, Visual Studio 2010 must be reinstalled to restore certain components 2.2.2. If Visual Studio 2010 Service Pack 1 is uninstalled, Visual Studio 2010 must be reinstalled before SP1 can be installed again 2.4.3.1. Async CTP If you installed the pre-SP1 version of Async CTP but did not uninstall it before you installed Visual Studio 2010 SP1, then your computer will be in a state in which the version of the C# compiler in the .NET Framework does not match the C# compiler in Visual Studio. To resolve this issue: After you install Visual Studio 2010 SP1, reinstall the SP1 version of the Async CTP from here. Hardware acceleration for Visual Studio is disabled on Windows XP Visual Studio 2010 SP1 disables hardware acceleration when running on Windows XP (only on XP). You can turn it back on in the Visual Studio options, under Environment / General, as shown below. See Jason Zander's post titled Performance Troubleshooting Article and VS2010 SP1 Change.

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  • Random movement of wandering monsters in x & y axis in LibGDX

    - by Vishal Kumar
    I am making a simple top down RPG game in LibGDX. What I want is ... the enemies should wander here and there in x and y directions in certain interval so that it looks natural that they are guarding something. I spend several hours doing this but could not achieve what I want. After a long time of coding, I came with this code. But what I observed is when enemies come to an end of x or start of x or start of y or end of y of the map. It starts flickering for random intervals. Sometimes they remain nice, sometimes, they start flickering for long time. public class Enemy extends Sprite { public float MAX_VELOCITY = 0.05f; public static final int MOVING_LEFT = 0; public static final int MOVING_RIGHT = 1; public static final int MOVING_UP = 2; public static final int MOVING_DOWN = 3; public static final int HORIZONTAL_GUARD = 0; public static final int VERTICAL_GUARD = 1; public static final int RANDOM_GUARD = 2; private float startTime = System.nanoTime(); private static float SECONDS_TIME = 0; private boolean randomDecider; public int enemyType; public static final float width = 30 * World.WORLD_UNIT; public static final float height = 32 * World.WORLD_UNIT; public int state; public float stateTime; public boolean visible; public boolean dead; public Enemy(float x, float y, int enemyType) { super(x, y); state = MOVING_LEFT; this.enemyType = enemyType; stateTime = 0; visible = true; dead = false; boolean random = Math.random()>=0.5f ? true :false; if(enemyType == HORIZONTAL_GUARD){ if(random) velocity.x = -MAX_VELOCITY; else velocity.x = MAX_VELOCITY; } if(enemyType == VERTICAL_GUARD){ if(random) velocity.y = -MAX_VELOCITY; else velocity.y = MAX_VELOCITY; } if(enemyType == RANDOM_GUARD){ //if(random) //velocity.x = -MAX_VELOCITY; //else //velocity.y = MAX_VELOCITY; } } public void update(Enemy e, float deltaTime) { super.update(deltaTime); e.stateTime+= deltaTime; e.position.add(velocity); // This is for updating the Animation for Enemy Movement Direction. VERY IMPORTANT FOR REAL EFFECTS updateDirections(); //Here the various movement methods are called depending upon the type of the Enemy if(e.enemyType == HORIZONTAL_GUARD) guardHorizontally(); if(e.enemyType == VERTICAL_GUARD) guardVertically(); if(e.enemyType == RANDOM_GUARD) guardRandomly(); //quadrantMovement(e, deltaTime); } private void guardHorizontally(){ if(position.x <= 0){ velocity.x= MAX_VELOCITY; velocity.y= 0; } else if(position.x>= World.mapWidth-width){ velocity.x= -MAX_VELOCITY; velocity.y= 0; } } private void guardVertically(){ if(position.y<= 0){ velocity.y= MAX_VELOCITY; velocity.x= 0; } else if(position.y>= World.mapHeight- height){ velocity.y= -MAX_VELOCITY; velocity.x= 0; } } private void guardRandomly(){ if (System.nanoTime() - startTime >= 1000000000) { SECONDS_TIME++; if(SECONDS_TIME % 5==0) randomDecider = Math.random()>=0.5f ? true :false; if(SECONDS_TIME>=30) SECONDS_TIME =0; startTime = System.nanoTime(); } if(SECONDS_TIME <=30){ if(randomDecider && position.x >= 0) velocity.x= -MAX_VELOCITY; else{ if(position.x < World.mapWidth-width) velocity.x= MAX_VELOCITY; else velocity.x= -MAX_VELOCITY; } velocity.y =0; } else{ if(randomDecider && position.y >0) velocity.y= -MAX_VELOCITY; else velocity.y= MAX_VELOCITY; velocity.x =0; } /* //This is essential so as to keep the enemies inside the boundary of the Map if(position.x <= 0){ velocity.x= MAX_VELOCITY; //velocity.y= 0; } else if(position.x>= World.mapWidth-width){ velocity.x= -MAX_VELOCITY; //velocity.y= 0; } else if(position.y<= 0){ velocity.y= MAX_VELOCITY; //velocity.x= 0; } else if(position.y>= World.mapHeight- height){ velocity.y= -MAX_VELOCITY; //velocity.x= 0; } */ } private void updateDirections() { if(velocity.x > 0) state = MOVING_RIGHT; else if(velocity.x<0) state = MOVING_LEFT; else if(velocity.y>0) state = MOVING_UP; else if(velocity.y<0) state = MOVING_DOWN; } public Rectangle getBounds() { return new Rectangle(position.x, position.y, width, height); } private void quadrantMovement(Enemy e, float deltaTime) { int temp = e.getEnemyQuadrant(e.position.x, e.position.y); boolean random = Math.random()>=0.5f ? true :false; switch(temp){ case 1: velocity.x = MAX_VELOCITY; break; case 2: velocity.x = MAX_VELOCITY; break; case 3: velocity.x = -MAX_VELOCITY; break; case 4: velocity.x = -MAX_VELOCITY; break; default: if(random) velocity.x = MAX_VELOCITY; else velocity.y =-MAX_VELOCITY; } } public float getDistanceFromPoint(float p1,float p2){ Vector2 v1 = new Vector2(p1,p2); return position.dst(v1); } private int getEnemyQuadrant(float x, float y){ Rectangle enemyQuad = new Rectangle(x, y, 30, 32); if(ScreenQuadrants.getQuad1().contains(enemyQuad)) return 1; if(ScreenQuadrants.getQuad2().contains(enemyQuad)) return 2; if(ScreenQuadrants.getQuad3().contains(enemyQuad)) return 3; if(ScreenQuadrants.getQuad4().contains(enemyQuad)) return 4; return 0; } } Is there a better way of doing this. I am new to game development. I shall be very grateful to any help or reference.

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  • Database users in the Oracle Utilities Application Framework

    - by Anthony Shorten
    I mentioned the product database users fleetingly in the last blog post and they deserve a better mention. This applies to all versions of the Oracle Utilities Application Framework. The Oracle Utilities Application Framework uses up to three users initially as part of the base operations of the product. The type of database supported (the framework supports Oracle, IBM DB2 and Microsoft SQL Server) dictates the number of users used and their permissions. For publishing brevity I will outline what is available for the Oracle database and, in summary, mention where it differs for the other database supported. For Oracle database customers we ship three distinct database users: Administration User (SPLADM or CISADM by default) - This is the database user that actually owns the schema. This user is not used by the product to do any DML (Data Manipulation Language) SQL other than that is necessary for maintenance of the database. This database user performs all the DCL (Data Control Language) and DDL (Data Definition Language) against the database. It is typically reserved for Database Administration use only. Product Read Write User (SPLUSER or CISUSER by default) - This is the database user used by the product itself to execute DML (Data Manipulation Language) statements against the schema owned by the Administration user. This user has the appropriate read and write permission to objects within the schema owned by the Administration user. For databases such as DB2 and SQL Server we may not create this user but use other DCL (Data Control Language) statements and facilities to simulate this user. Product Read User (SPLREAD or CISREAD by default) - This is the database that has read only permission to the schema owned by the Administration user. It is used for reporting or any part of the product or interface that requires read permissions to the database (for example, products that have ConfigLab and Archiving use this user for remote access). For databases such as DB2 and SQL Server we may not create this user but use other DCL (Data Control Language) statements and facilities to simulate this user. You may notice the words by default in the list above. The values supplied with the installer are the default and can be changed to what the site standard or implementation wants to use (as long as they conform to the standards supported by the underlying database). You can even create multiples of each within the same database and pointing to same schema. To manage the permissions for the users, there is a utility provided with the installation (oragensec (Oracle), db2gensec (DB2) or msqlgensec (SQL Server)) that generates the security definitions for the above users. That can be executed a number of times for each schema to give users appropriate permissions. For example, it is possible to define more than one read/write User to access the database. This is a common technique used by implementations to have a different user per access mode (to separate online and batch). In fact you can also allocate additional security (such as resource profiles in Oracle) to limit the impact of specific users at the database. To facilitate users and permissions, in Oracle for example, we create a CISREAD role (read only role) and a CISUSER role (read write role) that can be allocated to the appropriate database user. When the security permissions utility, oragensec in this case, is executed it uses the role to determine the permissions. To give you a case study, my underpowered laptop has multiple installations on it of multiple products but I have one database. I create a different schema for each product and each version (with my own naming convention to help me manage the databases). I create individual users on each schema and run oragensec to maintain the permissions for each appropriately. It works fine as long I have setup the userids appropriately. This means: Creating the users with the appropriate roles. I use the common CISUSER and CISREAD role across versions and across Oracle Utilities Application Framework products. Just remember to associate the CISUSER role with the database user you want to use for read/write operations and the CISREAD role with the user you wish to use for the read only operations. The role is treated as a tag to indicate the oragensec utility which appropriate permissions to assign to the user. The utilities for the other database types essentially do the same, obviously using the technology available within those databases. Run oragensec against the read write user and read only user against the appropriate administration user (I will abbreviate the user to ADM user). This ensures the right permissions are allocated to the right users for the right products. To help me there, I use the same prefix on the user name for the same product. For example, my Oracle Utilities Application Framework V4 environment has the administration user set to FW4ADM and the associated FW4USER and FW4READ as the users for the product to use. For my MWM environment I used MWMADM for the administration user and MWMUSER and MWMREAD for my associated users. You get the picture. When I run oragensec (once for each ADM user), I know what other users to associate with it. Remember to rerun oragensec against the users if I run upgrades, service packs or database based single fixes. This assures that the users are in synchronization with the ADM user. As a side note, for those who do not understand the difference between DML, DCL and DDL: DDL (Data Definition Language) - These are SQL statements that define the database schema and the structures within. SQL Statements such as CREATE and DROP are examples of DDL SQL statements. DCL (Data Control Language) - These are the SQL statements that define the database level permissions to DDL maintained objects within the database. SQL Statements such as GRANT and REVOKE are examples of DCL SQL statements. DML (Database Manipulation Language) - These are SQL statements that alter the data within the tables. SQL Statements such as SELECT, INSERT, UPDATE and DELETE are examples of DML SQL statements. Hope this has clarified the database user support. Remember in Oracle Utilities Application Framework V4 we enhanced this by also supporting CLIENT_IDENTIFIER to allow the database to still use the administration user for the main processing but make the database session more traceable.

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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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  • SQLAuthority News – Pluralsight Course Review – Practices for Software Startups – Part 1 of 2

    - by pinaldave
    This is first part of the two part series of Practices for Software Startup Pluralsight Course. The course is written by Stephen Forte (Blog | Twitter). Stephen Forte is the Chief Strategy Officer of the venture backed company, Telerik, a leading vendor of developer and team productivity tools. Stephen is also a Certified Scrum Master, Certified Scrum Professional, PMP, and also speaks regularly at industry conferences around the world. He has written several books on application and database development.  Stephen is also a board member of the Scrum Alliance. Startups – Everybodies Dream Start-up companies are an important topic right now – everyone wants to start their own business.  It is also important to remember that all companies were a start up at one point – from your corner store to the giants like Microsoft and Apple.  Research proves that not every start-up succeeds, in fact, most will fail before their first year.  There are many reasons for this, and this could be due to the fact that there are many stages to a start-up company, and stumbling at any of these stages can lead to failure.  It is important to understand what makes a start-up company succeed at all its hurdles to become successful.  It is even important to define success.  For most start-ups this would mean becoming their own independently functioning company or to be bought out for a hefty profit by a larger company.  The idea of making a hefty profit by living your dream is extremely important, and you can even think of start-ups as the new craze.  That’s why studying them is so important – they are very popular, but things have changed a lot since their inception. Starting the Startups Beginning a start-up company used to be difficult, but now facilities and information is widely available, and it is much easier.  But that means it is much easier to fail, also.  Previously to start your own company, everything was planned and organized, resources were ensured and backed up before beginning; even the idea of starting your own business was a big thing.  Now anybody can do it, and the steps are simple and outlines everywhere – you can get online software and easily outsource , cloud source, or crowdsource a lot of your material.  But without the type of planning previously required, things can often go badly. New Products – New Ideas – New World There are so many fantastic new products, but they don’t reach success all the time.  I find start-up companies very interesting, and whenever I meet someone who is interested in the subject or already starting their own company, I always ask what they are doing, their plans, goals, market, etc.  I am sorry to say that in most cases, they cannot answer my questions.  It is true that many fantastic ideas fail because of bad decisions.  These bad decisions were not made intentionally, but people were simply unaware of what they should be doing.  This will always lead to failure.  But I am happy to say that all these issues can be gone because Pluralsight is now offering a course all about start-ups by Stephen Forte.  Stephen is a start up leader.  He has successfully started many companies and most are still going strong, or have gone on to even bigger and better things. Beginning Course on Startup I have always thought start-ups are a fascinating subject, and decided to take his course, but it is three hours long.  This would be hard to fit into my busy work day all at once, so I decided to do half of his course before my daughter wakes up, and the other half after she goes to sleep.  The course is divided into six modules, so this would be easy to do.  I began the first chapter early in the morning, at 5 am.  Stephen jumped right into the middle of the subject in the very first module – designing your business plan.  The first question you will have to answer to yourself, to others, and to investors is: What is your product and when will we be able to see it?  So a very important concept is a “minimal viable product.”  This means setting goals for yourself and your product.  We all have large dreams, but your minimal viable product doesn’t have to be your final vision at the very first.  For example: Apple is a giant company, but it is still evolving.  Steve Jobs didn’t envision the iPhone 6 at the very beginning.  He had to start at the first iPhone and do his market research, and the idea evolved into the technology you see now.  So for yourself, you should decide a beginning and stop point.  Do your market research.  Determine who you want to reach, what audience you want for your product.  You can have a great idea that simply will not work in the market, do need, bottlenecks, lack of resources, or competition.  There is a lot of research that needs to be done before you even write a business plan, and Stephen covers it in the very first chapter. The Team – Unique Key to Success After jumping right into the subject in the very first module, I wondered what Stephen could have in store for me for the rest of the course.  Chapter number two is building a team.  Having a team is important regardless of what your startup is.  You can be a true visionary with endless ideas and energy, but one person can still not do everything.  It is important to decide from the very beginning if you will have cofounders, team leaders, and how many employees you’ll need.  Even more important, you’ll need to decide what kind of team you want – what personalities, skills, and type of energy you want each of your employees to bring.  Do you want to have an A+ team with a B- idea, or do you have a B- idea that needs an A+ team to sell it?  Stephen asks all the hard questions!  I was especially impressed by his insight on developing.  You have to decide if you need developers, how many, and what their skills should be. I found this insight extremely useful for everyday usage, not just for start-up companies.  I would apply this kind of information in management at any position.  An amazing team will build an amazing product – and that doesn’t matter if you’re a start-up company or a small team working for a much larger business. Customer Development – The Ultimate Obective Chapter three was about customer development. According to Stephen, there are four different steps to develop a customer base.  The first question to ask yourself is if you are envisioning a large customer base buying a few products each, or a small, dedicated base that buys a lot of your product – quantity vs. Quality.  He also discusses how to earn, retain, and get more customers.  He also says that each customer should be placed in a different role – some will be like investors, who regularly spend with you and invest their money in your business.  It is then your job to take that investment and turn it into a better product in the future.  You need to deal with their money properly – think of it is as theirs as investors, not yours as profit.  At the end of this module I felt that only Stephen could provide this kind of insight, and then he listed all the resources he took his information from.  I have never seen a group of people so passionate about their customers. It was indeed a long day for me. In tomorrow’s part 2 we will discuss rest of the three module and also will see a quick video of the Practices for Software Startup Pluralsight Course. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Best Practices, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • Solaris 11 Launch Blog Carnival Roundup

    - by constant
    Solaris 11 is here! And together with the official launch activities, a lot of Oracle and non-Oracle bloggers contributed helpful and informative blog articles to help your datacenter go to eleven. Here are some notable blog postings, sorted by category for your Solaris 11 blog-reading pleasure: Getting Started/Overview A lot of people speculated that the official launch of Solaris 11 would be on 11/11 (whatever way you want to turn it), but it actually happened two days earlier. Larry Wake himself offers 11 Reasons Why Oracle Solaris 11 11/11 Isn't Being Released on 11/11/11. Then, Larry goes on with a summary: Oracle Solaris 11: The First Cloud OS gives you a short and sweet rundown of what the major new features of Solaris 11 are. Jeff Victor has his own list of What's New in Oracle Solaris 11. A popular Solaris 11 meme is to write a blog post about 11 favourite features: Jim Laurent's 11 Reasons to Love Solaris 11, Darren Moffat's 11 Favourite Solaris 11 Features, Mike Gerdt's 11 of My Favourite Things! are just three examples of "11 Favourite Things..." type blog posts, I'm sure many more will follow... More official overview content for Solaris 11 is available from the Oracle Tech Network Solaris 11 Portal. Also, check out Rick Ramsey's blog post Solaris 11 Resources for System Administrators on the OTN Blog and his secret 5 Commands That Make Solaris Administration Easier post from the OTN Garage. (Automatic) Installation and the Image Packaging System (IPS) The brand new Image Packaging System (IPS) and the Automatic Installer (IPS), together with numerous other install/packaging/boot/patching features are among the most significant improvements in Solaris 11. But before installing, you may wonder whether Solaris 11 will support your particular set of hardware devices. Again, the OTN Garage comes to the rescue with Rick Ramsey's post How to Find Out Which Devices Are Supported By Solaris 11. Included is a useful guide to all the first steps to get your Solaris 11 system up and running. Tim Foster had a whole handful of blog posts lined up for the launch, teaching you everything you need to know about IPS but didn't dare to ask: The IPS System Repository, IPS Self-assembly - Part 1: Overlays and Part 2: Multiple Packages Delivering Configuration. Watch out for more IPS posts from Tim! If installing packages or upgrading your system from the net makes you uneasy, then you're not alone: Jim Laurent will tech you how Building a Solaris 11 Repository Without Network Connection will make your life easier. Many of you have already peeked into the future by installing Solaris 11 Express. If you're now wondering whether you can upgrade or whether a fresh install is necessary, then check out Alan Hargreaves's post Upgrading Solaris 11 Express b151a with support to Solaris 11. The trick is in upgrading your pkg(1M) first. Networking One of the first things to do after installing Solaris 11 (or any operating system for that matter), is to set it up for networking. Solaris 11 comes with the brand new "Network Auto-Magic" feature which can figure out everything by itself. For those cases where you want to exercise a little more control, Solaris 11 left a few people scratching their heads. Fortunately, Tschokko wrote up this cool blog post: Solaris 11 manual IPv4 & IPv6 configuration right after the launch ceremony. Thanks, Tschokko! And Milek points out a long awaited networking feature in Solaris 11 called Solaris 11 - hostmodel, which I know for a fact that many customers have looked forward to: How to "bind" a Solaris 11 system to a specific gateway for specific IP address it is using. Steffen Weiberle teaches us how to tune the Solaris 11 networking stack the proper way: ipadm(1M). No more fiddling with ndd(1M)! Check out his tutorial on Solaris 11 Network Tunables. And if you want to get even deeper into the networking stack, there's nothing better than DTrace. Alan Maguire teaches you in: DTracing TCP Congestion Control how to probe deeply into the Solaris 11 TCP/IP stack, the TCP congestion control part in particular. Don't miss his other DTrace and TCP related blog posts! DTrace And there we are: DTrace, the king of all observability tools. Long time DTrace veteran and co-author of The DTrace book*, Brendan Gregg blogged about Solaris 11 DTrace syscall provider changes. BTW, after you install Solaris 11, check out the DTrace toolkit which is installed by default in /usr/dtrace/DTT. It is chock full of handy DTrace scripts, many of which contributed by Brendan himself! Security Another big theme in Solaris 11, and one that is crucial for the success of any operating system in the Cloud is Security. Here are some notable posts in this category: Darren Moffat starts by showing us how to completely get rid of root: Completely Disabling Root Logins on Solaris 11. With no root user, there's one major entry point less to worry about. But that's only the start. In Immutable Zones on Encrypted ZFS, Darren shows us how to double the security of your services: First by locking them into the new Immutable Zones feature, then by encrypting their data using the new ZFS encryption feature. And if you're still missing sudo from your Linux days, Darren again has a solution: Password (PAM) caching for Solaris su - "a la sudo". If you're wondering how much compute power all this encryption will cost you, you're in luck: The Solaris X86 AESNI OpenSSL Engine will make sure you'll use your Intel's embedded crypto support to its fullest. And if you own a brand new SPARC T4 machine you're even luckier: It comes with its own SPARC T4 OpenSSL Engine. Dan Anderson's posts show how there really is now excuse not to encrypt any more... Developers Solaris 11 has a lot to offer to developers as well. Ali Bahrami has a series of blog posts that cover diverse developer topics: elffile: ELF Specific File Identification Utility, Using Stub Objects and The Stub Proto: Not Just For Stub Objects Anymore to name a few. BTW, if you're a developer and want to shape the future of Solaris 11, then Vijay Tatkar has a hint for you: Oracle (Sun Systems Group) is hiring! Desktop and Graphics Yes, Solaris 11 is a 100% server OS, but it can also offer a decent desktop environment, especially if you are a developer. Alan Coopersmith starts by discussing S11 X11: ye olde window system in today's new operating system, then Calum Benson shows us around What's new on the Solaris 11 Desktop. Even accessibility is a first-class citizen in the Solaris 11 user interface. Peter Korn celebrates: Accessible Oracle Solaris 11 - released! Performance Gone are the days of "Slowaris", when Solaris was among the few OSes that "did the right thing" while others cut corners just to win benchmarks. Today, Solaris continues doing the right thing, and it delivers the right performance at the same time. Need proof? Check out Brian's BestPerf blog with continuous updates from the benchmarking lab, including Recent Benchmarks Using Oracle Solaris 11! Send Me More Solaris 11 Launch Articles! These are just a few of the more interesting blog articles that came out around the Solaris 11 launch, I'm sure there are many more! Feel free to post a comment below if you find a particularly interesting blog post that hasn't been listed so far and share your enthusiasm for Solaris 11! *Affiliate link: Buy cool stuff and support this blog at no extra cost. We both win! var flattr_uid = '26528'; var flattr_tle = 'Solaris 11 Launch Blog Carnival Roundup'; var flattr_dsc = '<strong>Solaris 11 is here!</strong>And together with the official launch activities, a lot of Oracle and non-Oracle bloggers contributed helpful and informative blog articles to help your datacenter <a href="http://en.wikipedia.org/wiki/Up_to_eleven">go to eleven</a>.Here are some notable blog postings, sorted by category for your Solaris 11 blog-reading pleasure:'; var flattr_tag = 'blogging,digest,Oracle,Solaris,solaris,solaris 11'; var flattr_cat = 'text'; var flattr_url = 'http://constantin.glez.de/blog/2011/11/solaris-11-launch-blog-carnival-roundup'; var flattr_lng = 'en_GB'

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  • TFS, G.I. Joe and Under-doing

    If I were to rank the most consistently irritating parts of my work day, using TFS would come in first by a wide margin. Even repeated network outages this week seem like a pleasant reprieve from this monolithic beast. This is not a reflexive anti-Microsoft feeling, that attitude just wouldnt work for a consultant who does .NET development. It is also not an utter dismissal of TFS as worthless; Ive seen people use it effectively on several projects. So why? Ill start with a laundry list of shortcomings. An out of the box UI for work items that is insultingly bad, a source control system that is confoundingly fragile when handling merges, folder renames and long file names, the arcane XML wizardry necessary to customize a template and a build system that adds an extra layer of oddness on top of msbuild. Im sure my legion of readers will soon point out to me how I can work around all these issues, how this is fixed in TFS 2010 or with this add-in, and how once you have everything set up, youre fine. And theyd be right, any one of these problems could be worked around. If not dirty laundry, what else? I thought about it for a while, and came to the conclusion that TFS is so irritating to me because it represents a vision of software development that I find unappealing. To expand upon this, lets start with some wisdom from those great PSAs at the end of the G.I. Joe cartoons of the 80s: Now you know, and knowing is half the battle. In software development, Id go further and say knowing is more than half the battle. Understanding the dimensions of the problem you are trying to solve, the needs of the users, the value that your software can provide are more than half the battle. Implementation of this understanding is not easy, but it is not even possible without this knowledge. Assuming we have a fixed amount of time and mental energy for any project, why does this spell trouble for TFS? If you think about what TFS is doing, its offering you a huge array of options to track the day to day implementation of your project. From tasks, to code churn, to test coverage. All valuable metrics, but only in exchange for valuable time to get it all working. In addition, when you have a shiny toy like TFS, the temptation is to feel obligated to use it. So the push from TFS is to encourage a project manager and team to focus on process and metrics around process. You can get great visibility, and graphs to show your project stakeholders, but none of that is important if you are not implementing the right product. Not just unimportant, these activities can be harmful as they drain your time and sap your creativity away from the rest of the project. To be more concrete, lets suppose your organization has invested the time to create a template for your projects and trained people in how to use it, so there is no longer a big investment of time for each project to get up and running. First, Id challenge if that template could be specific enough to be full featured and still applicable for any project. Second, the very existence of this template would be a indication to a project manager that the success of their project was somehow directly related to fitting management of that project into this format. Again, while the capabilities are wonderful, the mirage is there; just get everything into TFS and your project will run smoothly. Ill close the loop on this first topic by proposing a thought experiment. Think of the projects youve worked on. How many times have you been chagrined to discover youve implemented the wrong feature, misunderstood how a feature should work or just plain spent too much time on a screen that nobody uses? That sounds like a really worthwhile area to invest time in improving. How about going back to these projects and thinking about how many times you wished you had optimized the state change flow of your tasks or been embarrassed to not have a code churn report linked back to the latest changeset? With thanks to the Real American Heroes, Ill move on to a more current influence, that of the developers at 37signals, and their philosophy towards software development. This philosophy, fully detailed in the books Getting Real and Rework, is a vision of software that under does the competition. This is software that is deliberately limited in functionality in order to concentrate fully on making sure ever feature that is there is awesome and needed. Why is this relevant? Well, in one of those fun seeming paradoxes in life, constraints can be a spark for creativity. Think Twitter, the small screen of an iPhone, the limitations of HTML for applications, the low memory limits of older or embedded system. As long as there is some freedom within those constraints, amazing things emerge. For project management, some of the most respected people in the industry recommend using just index cards, pens and tape. They argue that with change the constant in software development, your process should be as limited (yet rigorous) as possible. Looking at TFS, this is not a system designed to under do anybody. It is a big jumble of components and options, with every feature you could think of. Predictably this means many basic functions are hard to use. For task management, many people just use an Excel spreadsheet linked up to TFS. Not a stirring endorsement of the tooling there. TFS as a whole would be far more appealing to me if there was less of it, but better. Id cut 50% of the features to make the other half really amaze and inspire me. And thats really the heart of the matter. TFS has great promise and I want to believe it can work better. But ultimately it focuses your attention on a lot of stuff that doesnt really matter and then clamps down your creativity in a mess of forms and dialogs obscuring what does.   --- Relevant Links --- All those great G.I. Joe PSAs are on YouTube, including lots of mashed up versions. A simple Google search will get you on the right track.Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • .NET 4.5 is an in-place replacement for .NET 4.0

    - by Rick Strahl
    With the betas for .NET 4.5 and Visual Studio 11 and Windows 8 shipping many people will be installing .NET 4.5 and hacking away on it. There are a number of great enhancements that are fairly transparent, but it's important to understand what .NET 4.5 actually is in terms of the CLR running on your machine. When .NET 4.5 is installed it effectively replaces .NET 4.0 on the machine. .NET 4.0 gets overwritten by a new version of .NET 4.5 which - according to Microsoft - is supposed to be 100% backwards compatible. While 100% backwards compatible sounds great, we all know that 100% is a hard number to hit, and even the aforementioned blog post at the Microsoft site acknowledges this. But there's so much more than backwards compatibility that makes this awkward at best and confusing at worst. What does ‘Replacement’ mean? When you install .NET 4.5 your .NET 4.0 assemblies in the \Windows\.NET Framework\V4.0.30319 are overwritten with a new set of assemblies. You end up with overwritten assemblies as well as a bunch of new ones (like the new System.Net.Http assemblies for example). The following screen shot demonstrates system.dll on my test machine (left) running .NET 4.5 on the right and my production laptop running stock .NET 4.0 (right):   Clearly they are different files with a difference in file sizes (interesting that the 4.5 version is actually smaller). That’s not all. If you actually query the runtime version when .NET 4.5 is installed with with Environment.Version you still get: 4.0.30319 If you open the properties of System.dll assembly in .NET 4.5 you'll also see: Notice that the file version is also left at 4.0.xxx. There are differences in build numbers: .NET 4.0 shows 261 and the current .NET 4.5 beta build is 17379. I suppose you can use assume a build number greater than 17000 is .NET 4.5, but that's pretty hokey to say the least. There’s no easy or obvious way to tell whether you are running on 4.0 or 4.5 – to the application they appear to be the same runtime version. And that is what Microsoft intends here. .NET 4.5 is intended as an in-place upgrade. Compile to 4.5 run on 4.0 – not quite! You can compile an application for .NET 4.5 and run it on the 4.0 runtime – that is until you hit a new feature that doesn’t exist on 4.0. At which point the app bombs at runtime. Say you write some code that is mostly .NET 4.0, but only has a few of the new features of .NET 4.5 like aync/await buried deep in the bowels of the application where it only fires occasionally. .NET will happily start your application and run everything 4.0 fine, until it hits that 4.5 code – and then crash unceremoniously at runtime. Oh joy! You can .NET 4.0 applications on .NET 4.5 of course and that should work without much fanfare. Different than .NET 3.0/3.5 Note that this in-place replacement is very different from the side by side installs of .NET 2.0 and 3.0/3.5 which all ran on the 2.0 version of the CLR. The two 3.x versions were basically library enhancements on top of the core .NET 2.0 runtime. Both versions ran under the .NET 2.0 runtime which wasn’t changed (other than for security patches and bug fixes) for the whole 3.x cycle. The 4.5 update instead completely replaces the .NET 4.0 runtime and leaves the actual version number set at v4.0.30319. When you build a new project with Visual Studio 2011, you can still target .NET 4.0 or you can target .NET 4.5. But you are in effect referencing the same set of assemblies for both regardless which version you use. What's different is the compiler used to compile and link your code so compiling with .NET 4.0 gives you just the subset of the functionality that is available in .NET 4.0, but when you use the 4.5 compiler you get the full functionality of what’s actually available in the assemblies and extra libraries. It doesn’t look like you will be able to use Visual Studio 2010 to develop .NET 4.5 applications. Good news – Bad news Microsoft is trying hard to experiment with every possible permutation of releasing new versions of the .NET framework apparently. No two updates have been the same. Clearly updating to a full new version of .NET (ie. .NET 2.0, 4.0 and at some point 5.0 runtimes) has its own set of challenges, but doing an in-place update of the runtime and then not even providing a good way to tell which version is installed is pretty whacky even by Microsoft’s standards. Especially given that .NET 4.5 includes a fairly significant update with all the aysnc functionality baked into the runtime. Most of the IO APIs have been updated to support task based async operation which significantly affects many existing APIs. To make things worse .NET 4.5 will be the initial version of .NET that ships with Windows 8 so it will be with us for a long time to come unless Microsoft finally decides to push .NET versions onto Windows machines as part of system upgrades (which currently doesn’t happen). This is the same story we had when Vista launched with .NET 3.0 which was a minor version that quickly was replaced by 3.5 which was more long lived and practical. People had enough problems dealing with the confusing versioning of the 3.x versions which ran on .NET 2.0. I can’t count the amount support calls and questions I’ve fielded because people couldn’t find a .NET 3.5 entry in the IIS version dialog. The same is likely to happen with .NET 4.5. It’s all well and good when we know that .NET 4.5 is an in-place replacement, but administrators and IT folks not intimately familiar with .NET are unlikely to understand this nuance and end up thoroughly confused which version is installed. It’s hard for me to see any upside to an in-place update and I haven’t really seen a good explanation of why this approach was decided on. Sure if the version stays the same existing assembly bindings don’t break so applications can stay running through an update. I suppose this is useful for some component vendors and strongly signed assemblies in corporate environments. But seriously, if you are going to throw .NET 4.5 into the mix, who won’t be recompiling all code and thoroughly test that code to work on .NET 4.5? A recompile requirement doesn’t seem that serious in light of a major version upgrade.  Resources http://blogs.msdn.com/b/dotnet/archive/2011/09/26/compatibility-of-net-framework-4-5.aspx http://www.devproconnections.com/article/net-framework/net-framework-45-versioning-faces-problems-141160© Rick Strahl, West Wind Technologies, 2005-2012Posted in .NET   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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  • Cloud Based Load Testing Using TF Service &amp; VS 2013

    - by Tarun Arora [Microsoft MVP]
    Originally posted on: http://geekswithblogs.net/TarunArora/archive/2013/06/30/cloud-based-load-testing-using-tf-service-amp-vs-2013.aspx One of the new features announced as part of the Visual Studio 2013 Ultimate Preview is ‘Cloud Based Load Testing’. In this blog post I’ll walk you through, What is Cloud Based Load Testing? How have I been using this feature? – Success story! Where can you find more resources on this feature? What is Cloud Based Load Testing? It goes without saying that performance testing your application not only gives you the confidence that the application will work under heavy levels of stress but also gives you the ability to test how scalable the architecture of your application is. It is important to know how much is too much for your application! Working with various clients in the industry I have realized that the biggest barriers in Load Testing & Performance Testing adoption are, High infrastructure and administration cost that comes with this phase of testing Time taken to procure & set up the test infrastructure Finding use for this infrastructure investment after completion of testing Is cloud the answer? 100% Visual Studio Compatible Scalable and Realistic Start testing in < 2 minutes Intuitive Pay only for what you need Use existing on premise tests on cloud There are a lot of vendors out there offering Cloud Based Load Testing, to name a few, Load Storm Soasta Blaze Meter Blitz And others… The question you may want to ask is, why should you go with Microsoft’s Cloud based Load Test offering. If you are a Microsoft shop or already have investments in Microsoft technologies, you’ll see great benefit in the natural integration this offers with existing Microsoft products such as Visual Studio and Windows Azure. For example, your existing Web tests authored in Visual Studio 2010 or Visual Studio 2012 will run on the cloud without requiring any modifications what so ever. Microsoft’s cloud test rig also supports API based testing, for example, if you are building a WPF application which consumes WCF services, you can write unit tests to invoke the WCF service, these tests can be run on the cloud test rig and loaded with ‘N’ concurrent users for performance testing. If you have your assets already hosted in the Azure and possibly in the same data centre as the Cloud test rig, your Azure app will not incur a usage cost because of the generated traffic since the traffic is coming from the same data centre. The licensing or pricing information on Microsoft’s cloud based Load test service is yet to be announced, but I would expect this to be priced attractively to match the market competition.   The only additional configuration required for running load tests on Microsoft Cloud based Load Tests service is to select the Test run location as Run tests using Visual Studio Team Foundation Service, How have I been using Microsoft’s Cloud based Load Test Service? I have been part of the Microsoft Cloud Based Load Test Service advisory council for the last 7 months. This gave the opportunity to see the product shape up from concept to working solution. I was also the first person outside of Microsoft to try this offering out. This gave me the opportunity to test real world application at various clients using the Microsoft Load Test Service and provide real world feedback to the Microsoft product team. One of the most recent systems I tested using the Load Test Service has been an insurance quote generation engine. This insurance quote generation engine is,   hosted in Windows Azure expected to get quote requests from across the globe expected to handle 5 Million quote requests in a day (not clear how this load will be distributed across the day) There was no way, I could simulate such kind of load from on premise without standing up additional hardware. But Microsoft’s Cloud based Load Test service allowed me to test my key performance testing scenarios, i.e. Simulate expected Load, Endurance Testing, Threshold Testing and Testing for Latency. Simulating expected load: approach to devising a load pattern My approach to devising a load test pattern has been to run the test scenario with 1 user to figure out the response time. Then work out how many users are required to reach the target load. So, for example, to invoke 1 quote from the quote engine software takes 0.5 seconds. Now if you do the math,   1 quote request by 1 user = 0.5 seconds   quotes generated by 1 user in 24 hour = 1 * (((2 * 60) * 60) * 24) = 172,800   quotes generated by 30 users in 24 hours = 172,800 * 30 =  5,184,000 This was a very simple example, if your application requires more concurrent users to test scenario’s such as caching, etc then you can devise your own load pattern, some examples of load test patterns can be found here.  Endurance Testing To test for endurance, I loaded the quote generation engine with an expected fixed user load and ran the test for very long duration such as over 48 hours and observed the affect of the long running test on the Azure infrastructure. Currently Microsoft Load Test service does not support metrics from the machine under test. I used Azure diagnostics to begin with, but later started using Cerebrata Azure Diagnostics Manager to capture the metrics of the machine under test. Threshold Testing To figure out how much user load the application could cope with before falling on its belly, I opted to step load the quote generation engine by incrementing user load with different variations of incremental user load per minute till the application crashed out and forced an IIS reset. Testing for Latency Currently the Microsoft Load Test service does not support generating geographically distributed load, I however, deployed the insurance quote generation engine in different Azure data centres and ran the same set of performance tests to measure for latency. Because I could compare load test results from different runs by exporting the results to excel (this feature is provided out of the box right from Visual Studio 2010) I could see the different in response times. More resources on Microsoft Cloud based Load Test Service A few important links to get you started, Download Visual Studio Ultimate 2013 Preview Getting started guide for load testing using Team Foundation Service Troubleshooting guide for FAQs and known issues Team Foundation Service forum for questions and support Detailed demo and presentation (link to Tech-Ed session recording) Detailed demo and presentation (link to Build session recording) There a few limits on the usage of Microsoft Cloud based Load Test service that you can read about here. If you have any feedback on Microsoft Cloud based Load Test service, feel free to share it with the product team via the Visual Studio User Voice forum. I hope you found this useful. Thank you for taking the time out and reading this blog post. If you enjoyed the post, remember to subscribe to http://feeds.feedburner.com/TarunArora. Stay tuned!

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  • WebSocket and Java EE 7 - Getting Ready for JSR 356 (TOTD #181)

    - by arungupta
    WebSocket is developed as part of HTML 5 specification and provides a bi-directional, full-duplex communication channel over a single TCP socket. It provides dramatic improvement over the traditional approaches of Polling, Long-Polling, and Streaming for two-way communication. There is no latency from establishing new TCP connections for each HTTP message. There is a WebSocket API and the WebSocket Protocol. The Protocol defines "handshake" and "framing". The handshake defines how a normal HTTP connection can be upgraded to a WebSocket connection. The framing defines wire format of the message. The design philosophy is to keep the framing minimum to avoid the overhead. Both text and binary data can be sent using the API. WebSocket may look like a competing technology to Server-Sent Events (SSE), but they are not. Here are the key differences: WebSocket can send and receive data from a client. A typical example of WebSocket is a two-player game or a chat application. Server-Sent Events can only push data data to the client. A typical example of SSE is stock ticker or news feed. With SSE, XMLHttpRequest can be used to send data to the server. For server-only updates, WebSockets has an extra overhead and programming can be unecessarily complex. SSE provides a simple and easy-to-use model that is much better suited. SSEs are sent over traditional HTTP and so no modification is required on the server-side. WebSocket require servers that understand the protocol. SSE have several features that are missing from WebSocket such as automatic reconnection, event IDs, and the ability to send arbitrary events. The client automatically tries to reconnect if the connection is closed. The default wait before trying to reconnect is 3 seconds and can be configured by including "retry: XXXX\n" header where XXXX is the milliseconds to wait before trying to reconnect. Event stream can include a unique event identifier. This allows the server to determine which events need to be fired to each client in case the connection is dropped in between. The data can span multiple lines and can be of any text format as long as EventSource message handler can process it. WebSockets provide true real-time updates, SSE can be configured to provide close to real-time by setting appropriate timeouts. OK, so all excited about WebSocket ? Want to convert your POJOs into WebSockets endpoint ? websocket-sdk and GlassFish 4.0 is here to help! The complete source code shown in this project can be downloaded here. On the server-side, the WebSocket SDK converts a POJO into a WebSocket endpoint using simple annotations. Here is how a WebSocket endpoint will look like: @WebSocket(path="/echo")public class EchoBean { @WebSocketMessage public String echo(String message) { return message + " (from your server)"; }} In this code "@WebSocket" is a class-level annotation that declares a POJO to accept WebSocket messages. The path at which the messages are accepted is specified in this annotation. "@WebSocketMessage" indicates the Java method that is invoked when the endpoint receives a message. This method implementation echoes the received message concatenated with an additional string. The client-side HTML page looks like <div style="text-align: center;"> <form action=""> <input onclick="send_echo()" value="Press me" type="button"> <input id="textID" name="message" value="Hello WebSocket!" type="text"><br> </form></div><div id="output"></div> WebSocket allows a full-duplex communication. So the client, a browser in this case, can send a message to a server, a WebSocket endpoint in this case. And the server can send a message to the client at the same time. This is unlike HTTP which follows a "request" followed by a "response". In this code, the "send_echo" method in the JavaScript is invoked on the button click. There is also a <div> placeholder to display the response from the WebSocket endpoint. The JavaScript looks like: <script language="javascript" type="text/javascript"> var wsUri = "ws://localhost:8080/websockets/echo"; var websocket = new WebSocket(wsUri); websocket.onopen = function(evt) { onOpen(evt) }; websocket.onmessage = function(evt) { onMessage(evt) }; websocket.onerror = function(evt) { onError(evt) }; function init() { output = document.getElementById("output"); } function send_echo() { websocket.send(textID.value); writeToScreen("SENT: " + textID.value); } function onOpen(evt) { writeToScreen("CONNECTED"); } function onMessage(evt) { writeToScreen("RECEIVED: " + evt.data); } function onError(evt) { writeToScreen('<span style="color: red;">ERROR:</span> ' + evt.data); } function writeToScreen(message) { var pre = document.createElement("p"); pre.style.wordWrap = "break-word"; pre.innerHTML = message; output.appendChild(pre); } window.addEventListener("load", init, false);</script> In this code The URI to connect to on the server side is of the format ws://<HOST>:<PORT>/websockets/<PATH> "ws" is a new URI scheme introduced by the WebSocket protocol. <PATH> is the path on the endpoint where the WebSocket messages are accepted. In our case, it is ws://localhost:8080/websockets/echo WEBSOCKET_SDK-1 will ensure that context root is included in the URI as well. WebSocket is created as a global object so that the connection is created only once. This object establishes a connection with the given host, port and the path at which the endpoint is listening. The WebSocket API defines several callbacks that can be registered on specific events. The "onopen", "onmessage", and "onerror" callbacks are registered in this case. The callbacks print a message on the browser indicating which one is called and additionally also prints the data sent/received. On the button click, the WebSocket object is used to transmit text data to the endpoint. Binary data can be sent as one blob or using buffering. The HTTP request headers sent for the WebSocket call are: GET ws://localhost:8080/websockets/echo HTTP/1.1Origin: http://localhost:8080Connection: UpgradeSec-WebSocket-Extensions: x-webkit-deflate-frameHost: localhost:8080Sec-WebSocket-Key: mDbnYkAUi0b5Rnal9/cMvQ==Upgrade: websocketSec-WebSocket-Version: 13 And the response headers received are Connection:UpgradeSec-WebSocket-Accept:q4nmgFl/lEtU2ocyKZ64dtQvx10=Upgrade:websocket(Challenge Response):00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00 The headers are shown in Chrome as shown below: The complete source code shown in this project can be downloaded here. The builds from websocket-sdk are integrated in GlassFish 4.0 builds. Would you like to live on the bleeding edge ? Then follow the instructions below to check out the workspace and install the latest SDK: Check out the source code svn checkout https://svn.java.net/svn/websocket-sdk~source-code-repository Build and install the trunk in your local repository as: mvn install Copy "./bundles/websocket-osgi/target/websocket-osgi-0.3-SNAPSHOT.jar" to "glassfish3/glassfish/modules/websocket-osgi.jar" in your GlassFish 4 latest promoted build. Notice, you need to overwrite the JAR file. Anybody interested in building a cool application using WebSocket and get it running on GlassFish ? :-) This work will also feed into JSR 356 - Java API for WebSocket. On a lighter side, there seems to be less agreement on the name. Here are some of the options that are prevalent: WebSocket (W3C API, the URL is www.w3.org/TR/websockets though) Web Socket (HTML5 Demos - html5demos.com/web-socket) Websocket (Jenkins Plugin - wiki.jenkins-ci.org/display/JENKINS/Websocket%2BPlugin) WebSockets (Used by Mozilla - developer.mozilla.org/en/WebSockets, but use WebSocket as well) Web sockets (HTML5 Working Group - www.whatwg.org/specs/web-apps/current-work/multipage/network.html) Web Sockets (Chrome Blog - blog.chromium.org/2009/12/web-sockets-now-available-in-google.html) I prefer "WebSocket" as that seems to be most common usage and used by the W3C API as well. What do you use ?

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  • I Hereby Resolve… (T-SQL Tuesday #14)

    - by smisner
    It’s time for another T-SQL Tuesday, hosted this month by Jen McCown (blog|twitter), on the topic of resolutions. Specifically, “what techie resolutions have you been pondering, and why?” I like that word – pondering – because I ponder a lot. And while there are many things that I do already because of my job, there are many more things that I ponder about doing…if only I had the time. Then I ponder about making time, but then it’s back to work! In 2010, I was moderately more successful in making time for things that I ponder about than I had been in years past, and I hope to continue that trend in 2011. If Jen hadn’t settled on this topic, I could keep my ponderings to myself and no one would ever know the outcome, but she’s egged me on (and everyone else that chooses to participate)! So here goes… For me, having resolve to do something means that I wouldn’t be doing that something as part of my ordinary routine. It takes extra effort to make time for it. It’s not something that I do once and check off a list, but something that I need to commit to over a period of time. So with that in mind, I hereby resolve… To Learn Something New… One of the things I love about my job is that I get to do a lot of things outside of my ordinary routine. It’s a veritable smorgasbord of opportunity! So what more could I possibly add to that list of things to do? Well, the more I learn, the more I realize I have so much more to learn. It would be much easier to remain in ignorant bliss, but I was born to learn. Constantly. (And apparently to teach, too– my father will tell you that as a small child, I had the neighborhood kids gathered together to play school – in the summer. I’m sure they loved that – but they did it!) These are some of things that I want to dedicate some time to learning this year: Spatial data. I have a good understanding of how maps in Reporting Services works, and I can cobble together a simple T-SQL spatial query, but I know I’m only scratching the surface here. Rob Farley (blog|twitter) posted interesting examples of combining maps and PivotViewer, and I think there’s so many more creative possibilities. I’ve always felt that pictures (including charts and maps) really help people get their minds wrapped around data better, and because a lot of data has a geographic aspect to it, I believe developing some expertise here will be beneficial to my work. PivotViewer. Not only is PivotViewer combined with maps a useful way to visualize data, but it’s an interesting way to work with data. If you haven’t seen it yet, check out this interactive demonstration using Netflx OData feed. According to Rob Farley, learning how to work with PivotViewer isn’t trivial. Just the type of challenge I like! Security. You’ve heard of the accidental DBA? Well, I am the accidental security person – is there a word for that role? My eyes used to glaze over when having to study about security, or  when reading anything about it. Then I had a problem long ago that no one could figure out – not even the vendor’s tech support – until I rolled up my sleeves and painstakingly worked through the myriad of potential problems to resolve a very thorny security issue. I learned a lot in the process, and have been able to share what I’ve learned with a lot of people. But I’m not convinced their eyes weren’t glazing over, too. I don’t take it personally – it’s just a very dry topic! So in addition to deepening my understanding about security, I want to find a way to make the subject as it relates to SQL Server and business intelligence more accessible and less boring. Well, there’s actually a lot more that I could put on this list, and a lot more things I have plans to do this coming year, but I run the risk of overcommitting myself. And then I wouldn’t have time… To Have Fun! My name is Stacia and I’m a workaholic. When I love what I do, it’s difficult to separate out the work time from the fun time. But there are some things that I’ve been meaning to do that aren’t related to business intelligence for which I really need to develop some resolve. And they are techie resolutions, too, in a roundabout sort of way! Photography. When my husband and I went on an extended camping trip in 2009 to Yellowstone and the Grand Tetons, I had a nice little digital camera that took decent pictures. But then I saw the gorgeous cameras that other tourists were toting around and decided I needed one too. So I bought a Nikon D90 and have started to learn to use it, but I’m definitely still in the beginning stages. I traveled so much in 2010 and worked on two book projects that I didn’t have a lot of free time to devote to it. I was very inspired by Kimberly Tripp’s (blog|twitter) and Paul Randal’s (blog|twitter) photo-adventure in Alaska, though, and plan to spend some dedicated time with my camera this year. (And hopefully before I move to Alaska – nothing set in stone yet, but we hope to move to a remote location – with Internet access – later this year!) Astronomy. I have this cool telescope, but it suffers the same fate as my camera. I have been gone too much and busy with other things that I haven’t had time to work with it. I’ll figure out how it works, and then so much time passes by that I forget how to use it. I have this crazy idea that I can actually put the camera and the telescope together for astrophotography, but I think I need to start simple by learning how to use each component individually. As long as I’m living in Las Vegas, I know I’ll have clear skies for nighttime viewing, but when we move to Alaska, we’ll be living in a rain forest. I have no idea what my opportunities will be like there – except I know that when the sky is clear, it will be far more amazing than anything I can see in Vegas – even out in the desert - because I’ll be so far away from city light pollution. I’ve been contemplating putting together a blog on these topics as I learn. As many of my fellow bloggers in the SQL Server community know, sometimes the best way to learn something is to sit down and write about it. I’m just stumped by coming up with a clever name for the new blog, which I was thinking about inaugurating with my move to Alaska. Except that I don’t know when that will be exactly, so we’ll just have to wait and see which comes first!

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  • Interview with Lenz Grimmer about MySQL Connect

    - by Keith Larson
    Keith Larson: Thank you for allowing me to do this interview with you.  I have been talking with a few different Oracle ACEs   about the MySQL Connect Conference. I figured the MySQL community might be missing you as well. You have been very busy with Oracle Linux but I know you still have an eye on the MySQL Community. How have things been?Lenz Grimmer: Thanks for including me in this series of interviews, I feel honored! I've read the other interviews, and really liked them. I still try to follow what's going on over in the MySQL community and it's good to see that many of the familiar faces are still around. Over the course of the 9 years that I was involved with MySQL, many colleagues and contacts turned into good friends and we still maintain close relationships.It's been almost 1.5 years ago that I moved into my new role here in the Linux team at Oracle, and I really enjoy working on a Linux distribution again (I worked for SUSE before I joined MySQL AB in 2002). I'm still learning a lot - Linux in the data center has greatly evolved in so many ways and there are a lot of new and exciting technologies to explore. Keith Larson: What were your thoughts when you heard that Oracle was going to deliver the MySQL Connect conference to the MySQL Community?Lenz Grimmer: I think it's testament to the fact that Oracle deeply cares about MySQL, despite what many skeptics may say. What started as "MySQL Sunday" two years ago has now evolved into a full-blown sub-conference, with 80 sessions at one of the largest corporate IT events in the world. I find this quite telling, not many products at Oracle enjoy this level of exposure! So it certainly makes me feel proud to see how far MySQL has come. Keith Larson: Have you had a chance to look over the sessions? What are your thoughts on them?Lenz Grimmer: I did indeed look at the final schedule.The content committee did a great job with selecting these sessions. I'm glad to see that the content selection was influenced by involving well-known and respected members of the MySQL community. The sessions cover a broad range of topics and technologies, both covering established topics as well as recent developments. Keith Larson: When you get a chance, what sessions do you plan on attending?Lenz Grimmer: I will actually be manning the Oracle booth in the exhibition area on one of these days, so I'm not sure if I'll have a lot of time attending sessions. But if I do, I'd love to see the keynotes and catch some of the sessions that talk about recent developments and new features in MySQL, High Availability and Clustering . Quite a lot has happened and it's hard to keep up with this constant flow of new MySQL releases.In particular, the following sessions caught my attention: MySQL Connect Keynote: The State of the Dolphin Evaluating MySQL High-Availability Alternatives CERN’s MySQL “as a Service” Deployment with Oracle VM: Empowering Users MySQL 5.6 Replication: Taking Scalability and High Availability to the Next Level What’s New in MySQL Server 5.6? MySQL Security: Past and Present MySQL at Twitter: Development and Deployment MySQL Community BOF MySQL Connect Keynote: MySQL Perspectives Keith Larson: So I will ask you just like I have asked the others I have interviewed, any tips that you would give to people for handling the long hours at conferences?Lenz Grimmer: Wear comfortable shoes and make sure to drink a lot! Also prepare a plan of the sessions you would like to attend beforehand and familiarize yourself with the venue, so you can get to the next talk in time without scrambling to find the location. The good thing about piggybacking on such a large conference like Oracle OpenWorld is that you benefit from the whole infrastructure. For example, there is a nice schedule builder that helps you to keep track of your sessions of interest. Other than that, bring enough business cards and talk to people, build up your network among your peers and other MySQL professionals! Keith Larson: What features of the MySQL 5.6 release do you look forward to the most ?Lenz Grimmer: There has been solid progress in so many areas like the InnoDB Storage Engine, the Optimizer, Replication or Performance Schema, it's hard for me to really highlight anything in particular. All in all, MySQL 5.6 sounds like a very promising release. I'm confident it will follow the tradition that Oracle already established with MySQL 5.5, which received a lot of praise even from very critical members of the MySQL community. If I had to name a single feature, I'm particularly and personally happy that the precise GIS functions have finally made it into a GA release - that was long overdue. Keith Larson:  In your opinion what is the best reason for someone to attend this event?Lenz Grimmer: This conference is an excellent opportunity to get in touch with the key people in the MySQL community and ecosystem and to get facts and information from the domain experts and developers that work on MySQL. The broad range of topics should attract people from a variety of roles and relations to MySQL, beginning with Developers and DBAs, to CIOs considering MySQL as a viable solution for their requirements. Keith Larson: You will be attending MySQL Connect and have some Oracle Linux Demos, do you see a growing demand for MySQL on Oracle Linux ?Lenz Grimmer: Yes! Oracle Linux is our recommended Linux distribution and we have a good relationship to the MySQL engineering group. They use Oracle Linux as a base Linux platform for development and QA, so we make sure that MySQL and Oracle Linux are well tested together. Setting up a MySQL server on Oracle Linux can be done very quickly, and many customers recognize the benefits of using them both in combination.Because Oracle Linux is available for free (including free bug fixes and errata), it's an ideal choice for running MySQL in your data center. You can run the same Linux distribution on both your development/staging systems as well as on the production machines, you decide which of these should be covered by a support subscription and at which level of support. This gives you flexibility and provides some really attractive cost-saving opportunities. Keith Larson: Since I am a Linux user and fan, what is on the horizon for  Oracle Linux?Lenz Grimmer: We're working hard on broadening the ecosystem around Oracle Linux, building up partnerships with ISVs and IHVs to certify Oracle Linux as a fully supported platform for their products. We also continue to collaborate closely with the Linux kernel community on various projects, to make sure that Linux scales and performs well on large systems and meets the demands of today's data centers. These improvements and enhancements will then rolled into the Unbreakable Enterprise Kernel, which is the key ingredient that sets Oracle Linux apart from other distributions. We also have a number of ongoing projects which are making good progress, and I'm sure you'll hear more about this at the upcoming OpenWorld conference :) Keith Larson: What is something that more people should be aware of when it comes to Oracle Linux and MySQL ?Lenz Grimmer: Many people assume that Oracle Linux is just tuned for Oracle products, such as the Oracle Database or our Engineered Systems. While it's of course true that we do a lot of testing and optimization for these workloads, Oracle Linux is and will remain a general-purpose Linux distribution that is a very good foundation for setting up a LAMP-Stack, for example. We also provide MySQL RPM packages for Oracle Linux, so you can easily stay up to date if you need something newer than what's included in the stock distribution.One more thing that is really unique to Oracle Linux is Ksplice, which allows you to apply security patches to the running Linux kernel, without having to reboot. This ensures that your MySQL database server keeps up and running and is not affected by any downtime. Keith Larson: What else would you like to add ?Lenz Grimmer: Thanks again for getting in touch with me, I appreciated the opportunity. I'm looking forward to MySQL Connect and Oracle OpenWorld and to meet you and many other people from the MySQL community that I haven't seen for quite some time! Keith Larson:  Thank you Lenz!

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  • Keeping track of File System Utilization in Ops Center 12c

    - by S Stelting
    Enterprise Manager Ops Center 12c provides significant monitoring capabilities, combined with very flexible incident management. These capabilities even extend to monitoring the file systems associated with Solaris or Linux assets. Depending on your needs you can monitor and manage incidents, or you can fine tune alert monitoring rules to specific file systems. This article will show you how to use Ops Center 12c to Track file system utilization Adjust file system monitoring rules Disable file system rules Create custom monitoring rules If you're interested in this topic, please join us for a WebEx presentation! Date: Thursday, November 8, 2012 Time: 11:00 am, Eastern Standard Time (New York, GMT-05:00) Meeting Number: 598 796 842 Meeting Password: oracle123 To join the online meeting ------------------------------------------------------- 1. Go to https://oracleconferencing.webex.com/oracleconferencing/j.php?ED=209833597&UID=1512095432&PW=NOWQ3YjJlMmYy&RT=MiMxMQ%3D%3D 2. If requested, enter your name and email address. 3. If a password is required, enter the meeting password: oracle123 4. Click "Join". To view in other time zones or languages, please click the link: https://oracleconferencing.webex.com/oracleconferencing/j.php?ED=209833597&UID=1512095432&PW=NOWQ3YjJlMmYy&ORT=MiMxMQ%3D%3D   Monitoring File Systems for OS Assets The Libraries tab provides basic, device-level information about the storage associated with an OS instance. This tab shows you the local file system associated with the instance and any shared storage libraries mounted by Ops Center. More detailed information about file system storage is available under the Analytics tab under the sub-tab named Charts. Here, you can select and display the individual mount points of an OS, and export the utilization data if desired: In this example, the OS instance has a basic root file partition and several NFS directories. Each file system mount point can be independently chosen for display in the Ops Center chart. File Systems and Incident  Reporting Every asset managed by Ops Center has a "monitoring policy", which determines what represents a reportable issue with the asset. The policy is made up of a bunch of monitoring rules, where each rule describes An attribute to monitor The conditions which represent an issue The level or levels of severity for the issue When the conditions are met, Ops Center sends a notification and creates an incident. By default, OS instances have three monitoring rules associated with file systems: File System Reachability: Triggers an incident if a file system is not reachable NAS Library Status: Triggers an incident for a value of "WARNING" or "DEGRADED" for a NAS-based file system File System Used Space Percentage: Triggers an incident when file system utilization grows beyond defined thresholds You can view these rules in the Monitoring tab for an OS: Of course, the default monitoring rules is that they apply to every file system associated with an OS instance. As a result, any issue with NAS accessibility or disk utilization will trigger an incident. This can cause incidents for file systems to be reported multiple times if the same shared storage is used by many assets, as shown in this screen shot: Depending on the level of control you'd like, there are a number of ways to fine tune incident reporting. Note that any changes to an asset's monitoring policy will detach it from the default, creating a new monitoring policy for the asset. If you'd like, you can extract a monitoring policy from an asset, which allows you to save it and apply the customized monitoring profile to other OS assets. Solution #1: Modify the Reporting Thresholds In some cases, you may want to modify the basic conditions for incident reporting in your file system. The changes you make to a default monitoring rule will apply to all of the file systems associated with your operating system. Selecting the File Systems Used Space Percentage entry and clicking the "Edit Alert Monitoring Rule Parameters" button opens a pop-up dialog which allows you to modify the rule. The first screen lets you decide when you will check for file system usage, and how long you will wait before opening an incident in Ops Center. By default, Ops Center monitors continuously and reports disk utilization issues which exist for more than 15 minutes. The second screen lets you define actual threshold values. By default, Ops Center opens a Warning level incident is utilization rises above 80%, and a Critical level incident for utilization above 95% Solution #2: Disable Incident Reporting for File System If you'd rather not report file system incidents, you can disable the monitoring rules altogether. In this case, you can select the monitoring rules and click the "Disable Alert Monitoring Rule(s)" button to open the pop-up confirmation dialog. Like the first solution, this option affects all file system monitoring. It allows you to completely disable incident reporting for NAS library status or file system space consumption. Solution #3: Create New Monitoring Rules for Specific File Systems If you'd like to have the greatest flexibility when monitoring file systems, you can create entirely new rules. Clicking the "Add Alert Monitoring Rule" (the icon with the green plus sign) opens a wizard which allows you to define a new rule.  This rule will be based on a threshold, and will be used to monitor operating system assets. We'd like to add a rule to track disk utilization for a specific file system - the /nfs-guest directory. To do this, we specify the following attribute FileSystemUsages.name=/nfs-guest.usedSpacePercentage The value of name in the attribute allows us to define a specific NFS shared directory or file system... in the case of this OS, we could have chosen any of the values shown in the File Systems Utilization chart at the beginning of this article. usedSpacePercentage lets us define a threshold based on the percentage of total disk space used. There are a number of other values that we could use for threshold-based monitoring of FileSystemUsages, including freeSpace freeSpacePercentage totalSpace usedSpace usedSpacePercentage The final sections of the screen allow us to determine when to monitor for disk usage, and how long to wait after utilization reaches a threshold before creating an incident. The next screen lets us define the threshold values and severity levels for the monitoring rule: If historical data is available, Ops Center will display it in the screen. Clicking the Apply button will create the new monitoring rule and active it in your monitoring policy. If you combine this with one of the previous solutions, you can precisely define which file systems will generate incidents and notifications. For example, this monitoring policy has the default "File System Used Space Percentage" rule disabled, but the new rule reports ONLY on utilization for the /nfs-guest directory. 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  • Flashing your Windows Phone Dummies

    - by Martin Hinshelwood
    The rate at which vendors release new updates for the HD2 is ridiculously slow. You have to wait for Microsoft to release the new OS, then you wait for HTC to build it into a ROM, and then you have to wait up to 6 months for your operator to badly customise it for their network. Once Windows Phone 7 is released this problem should go away as Microsoft is likely to be able to update the phone over the air, but what do we do until then? I want Windows Mobile 6.5.5 now!   I’m an early adopter. If there is a new version of something then that’s the version I want. As long as you accept that you are using something on a “let the early adopter beware” and accept that there may be bugs, sometimes serious crippling bugs the go for it. Note that I won't be responsible if you end up bricking your phone, unlocking or flashing your radio or ROM can be risky. If you follow the instructions then you should be fine, I've flashed my phones (SPV, M300, M1000, M2000, M3100, TyTN, TyTN 2, HD2) hundreds of times without any problems! I have been using Windows Mobile 6.5.5 before it was called 6.5.5 and for long enough that I don’t even remember when I first started using it. I was using it on my HTC TyTN 2 before I got an HD2 a couple of months before Christmas, and the first custom ROM’s for the HD2 were a couple of months after that. I always update to the latest ROM that I like, and occasionally I go back to the stock ROM’s to have a look see, but I am always disappointed. Terms: Soft Reset: Same as pulling out the battery, but is like a reboot for your phone Hard Reset: Reinstalls the Operating system from the Image that is stored on it ROM: This is Image that is loaded onto your phone and it is used to reinstall your phone whenever you do a “hard reset”. Stock ROM: A ROM from the original vendor… So HTC Cook a ROM: Referring to Cooking a ROM is the process a ROM developer goes through to take all of the parts (OS, Drivers and Applications) that make up a running phone and compiling them into a ROM. ROM Kitchen: A place where you get an SDK and all the component parts of the phone: OD, Drivers and Application. There are usually lots of Tools for making it easier to compile and build the image. Flashing: The process of updating one of the layers of your phone with a new layer Bricked: This is what happens when flashing goes wrong. Your phone is now good for only one thing… stopping paper blowing away in a windy place. You can “cook” you own ROM using one of the many good “ROM Kitchens” or you can use a ROM built and tested by someone else. I have cooked my own ROM before, and while the tutorials are good, it is a lot of hassle. You can only Flash new ROM’s that are specifically for your phone only so find a ROM for your phone and XDA Developers is the best place to look. It has a forum based structure and you can find your phone quite easily. XDA Developer Forum Installing a new ROM does have its risks. In the past there have been stories about phones being “bricked” but I have not heard of a bricked phone for quite some years. if you follow the instructions carefully you should not have any problems. note: Most of the tools are written by people for whom English is not their first language to you will need concentrate hard to understand some of the instructions. Have you ever read a manual that was just literally translated from another language? Enough said… There are a number of layers on your phone that you will need to know about: SPL: This is the lowest level, like a BIOS on a PC and is the Operating Systems gateway to the hardware Radio: I think of this as the hardware drivers, and you will need a different Radio for CDMA than GSM networks ROM: This is like your Windows CD, but it is stored internally to the Phone. Flashing your phone consists of replacing one Image with another and then wiping your phone and automatically reinstall from the Image. Sometimes when you download an Image wither it is for a Radio or for ROM you only get a file called *.nbh. What do you do with this? Well you need an RUU application to push that Image to your phone. The RUU’s are different per phone, but there is a CustomRUU for the HD2 that will update your phone with any *.nbh placed in the same directory. Download and Instructions for CustomRUU #1 Flash HardSPL An SPL is kind of like a BIOS, and the default one has checks to make sure that you are only installing a signed ROM. This would prevent you from installing one that comes from any other source but the vendor. NOTE: Installing a HARD SPL invalidates your warranty so remember to Flash your phone with a “stock” vendor ROM before trying to send your phone in for repairs. Is the warranty reinstated when you go back to a stock ROM? I don’t know… Updating your SPL to a HardSPL effectively unlocks your phone so you can install anything you like. I would recommend the HardSPL2. Download and Instructions for HardSPL2 #2 Task29 One of the problems that has been seen on the HD2 when flashing new ROM’s is that things are left over from the old ROM. For a while the recommendation was to Flash a stock ROM first, but some clever cookies have come up with “Task29” which formats your phone first. After running this your phone will be blank and will only boot to the white HTC logo and no further. You should follow the instructions and reboot (remove battery) and hold down the “volume down” button while turning you HD2 on to enter the bootloader. From here you can run CustomRUU once the USB message appears. Download and Instructions for Task29 #2 Flash Radio You may need to play around with this one, there is no good and bad version and the latest is not always the best. You know that annoying thing when you hit “end call” on your phone and nothing happens? Well that's down to the Radio. Get this version right for you and you may even be able to make calls. From a Windows Mobile as well Download There are no instructions here, but they are the same as th ROM, but you use this *.nbh file. #3 Flash ROM If you have gotten this far then you are probably a pro by now Just download the latest ROM below and Flash to your phone. I have been really impressed by the Artemis line of ROM’s but it is no way the only choice. I like this one as the developer builds them as close to the stock ROM as possible while updating to the latest of everything. Download and Instructions for  Artemis HD2 vXX Conclusion While updating your ROM is not for the faint hearted it provides more options than the Stock ROM’s and quicker feature updates than waiting… Technorati Tags: WM6

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  • Win a set of Infragistics Silverlight Controls with Data Visualization!

    - by mbcrump
    Infragistics recently released their new Silverlight Data Visualization Controls. I saw a couple of samples and had to take a look. I headed over to their website and downloaded the controls. I first noticed the hospital floor-plan demo shown on their site and started thinking of ways that I could use this in my own organization. I emailed them asking if I could give away the Silverlight Data Visualization controls on my site and they said, Yes! They also wanted to throw in the standard Silverlight Line of Business controls. (combined they are worth about $3000 US). I am very thankful they were willing to help the Silverlight community with this giveaway. So some quick rules below: ----------------------------------------------------------------------------------------------------------------------------------------------------------- Win a FREE developer’s license of Infragistics Silverlight Controls with Data Visualization ($3000 Value) Random winner will be announced on January 1st, 2011! To be entered into the contest do the following things: Subscribe to my feed. Leave a comment below with a valid email account (I WILL NOT share this info with anyone.) For extra entries simply: Retweet a link to this page using the following URL [ http://mcrump.me/iscfree ]. It does not matter what the tweet says, just as long as the URL is the same. Unlimited tweets, but please don’t go crazy! This URL will allow me to track the users that Tweet this page. Don’t forget to visit Infragistics because they made this possible. ---------------------------------------------------------------------------------------------------------------------------------------------------------- Before we get started with the Silverlight Controls, here is a couple of links to bookmark: The Silverlight Line of Business Control page is here. You can also check out the live demos here. The Data Visualization page is here. You can also check out the live demos here. Don’t worry about the Samples/Help Documentation. You can install all of that to your local HDD when you are installing it. I am going to walk you through the Silverlight Controls recently released by Infragistics. Begin by downloading the trial version and running the executable. If you downloaded the Complete bundle then you will have the following options to pick from. I like having help documentation and samples on my local HDD in case I do not have access to the internet and want to code. After it is installed, you may want to take a look at your Toolbox in Visual Studio 2010. Look for NetAdvantage 10.3 Silverlight and you will see that you now have access to all of these controls. At this point, to use the controls it’s as simple as drag/drop onto your Silverlight container. It will create the proper Namespaces for you. I wanted to highlight a few of the controls that I liked the most: Grid – After using the Infragistics grid you will wonder how you ever survived using the grid supplied by Microsoft standard controls.  This grid was designed to get your application up and running very fast. It’s simple to bind, it handles LARGE DataSets, easy to filter and allows endless possibilities of formatting data. The screenshot below is an example of the grid. For a real-time updating demo click here. SpellChecker- If your users are creating emails or performing any other function that requires Spell Checking then this control is great. Check out the screenshots below: In this first screen, I have a word that is not in the dictionary [DotNet]. The Spell Checker finds the word and allows the user to correct it. What is so great about Infragistics controls is that it only takes a few lines of code to have a full-featured Spell Checker in your application. TagCloud – This is a control that I haven’t seen anywhere else. It allows you to create keywords for popular search terms. This is very similar to TagCloud seen all over the internet.  Below is a screenshot that shows “Facebook” being a very popular item in the cloud. You can link these items to a hyperlink if you wanted. Importing/Exporting from Excel – I work with data a majority of the time. We all know the importance of Excel in our organizations, its used a lot. With Infragistics controls it make importing and exporting data from a Grid into Excel a snap. One of the things that I liked most about this control was the option to choose the Excel format (2003 or 2007). I haven’t seen this feature in other controls. Creating/Saving/Extracting/Uploading Zip Files – This is another control that I haven’t seen many others making. It allows you to basically manipulate a zip file in any way you like. You can even create a password on the zip file. Schedule – The Schedule that Infragistics provides resembles Outlook’s calendar. I think that it’s important for a user to see your app for the first time and immediately be able to start using because they are already familiar with the UI. The Schedule control accomplishes that in my opinion. I have just barely scratched the surface with the Infragistics Silverlight Line of Business controls. To check all of them then click here. A quick thing to note is that this giveaway also comes with the following Silverlight Data Visualization Controls. Below is a screenshot that list all of them:   I wanted to highlight 2 of the controls that I liked the most: xamBarcode– The xamBarcode supports the following Symbologies: Below is an example of the barcode generated by Infragistics controls. This is a high resolution barcode that you will not have to wonder if your scanner can read it. As long as you have ink in your printer your barcode will read it. I used a Symbol barcode reader to test this barcode. xamTreemap– I’ve never seen a way of displaying data like this before, but I like it. You can style this anyway that you like of course and it also comes with an Office 2010 Theme. Thanks to Infragistics for providing the controls to one lucky reader. I hope that you enjoyed this post and good luck to those that entered the contest.  Subscribe to my feed

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  • C#/.NET Little Pitfalls: The Dangers of Casting Boxed Values

    - by James Michael Hare
    Starting a new series to parallel the Little Wonders series.  In this series, I will examine some of the small pitfalls that can occasionally trip up developers. Introduction: Of Casts and Conversions What happens when we try to assign from an int and a double and vice-versa? 1: double pi = 3.14; 2: int theAnswer = 42; 3:  4: // implicit widening conversion, compiles! 5: double doubleAnswer = theAnswer; 6:  7: // implicit narrowing conversion, compiler error! 8: int intPi = pi; As you can see from the comments above, a conversion from a value type where there is no potential data loss is can be done with an implicit conversion.  However, when converting from one value type to another may result in a loss of data, you must make the conversion explicit so the compiler knows you accept this risk.  That is why the conversion from double to int will not compile with an implicit conversion, we can make the conversion explicit by adding a cast: 1: // explicit narrowing conversion using a cast, compiler 2: // succeeds, but results may have data loss: 3: int intPi = (int)pi; So for value types, the conversions (implicit and explicit) both convert the original value to a new value of the given type.  With widening and narrowing references, however, this is not the case.  Converting reference types is a bit different from converting value types.  First of all when you perform a widening or narrowing you don’t really convert the instance of the object, you just convert the reference itself to the wider or narrower reference type, but both the original and new reference type both refer back to the same object. Secondly, widening and narrowing for reference types refers the going down and up the class hierarchy instead of referring to precision as in value types.  That is, a narrowing conversion for a reference type means you are going down the class hierarchy (for example from Shape to Square) whereas a widening conversion means you are going up the class hierarchy (from Square to Shape).  1: var square = new Square(); 2:  3: // implicitly convers because all squares are shapes 4: // (that is, all subclasses can be referenced by a superclass reference) 5: Shape myShape = square; 6:  7: // implicit conversion not possible, not all shapes are squares! 8: // (that is, not all superclasses can be referenced by a subclass reference) 9: Square mySquare = (Square) myShape; So we had to cast the Shape back to Square because at that point the compiler has no way of knowing until runtime whether the Shape in question is truly a Square.  But, because the compiler knows that it’s possible for a Shape to be a Square, it will compile.  However, if the object referenced by myShape is not truly a Square at runtime, you will get an invalid cast exception. Of course, there are other forms of conversions as well such as user-specified conversions and helper class conversions which are beyond the scope of this post.  The main thing we want to focus on is this seemingly innocuous casting method of widening and narrowing conversions that we come to depend on every day and, in some cases, can bite us if we don’t fully understand what is going on!  The Pitfall: Conversions on Boxed Value Types Can Fail What if you saw the following code and – knowing nothing else – you were asked if it was legal or not, what would you think: 1: // assuming x is defined above this and this 2: // assignment is syntactically legal. 3: x = 3.14; 4:  5: // convert 3.14 to int. 6: int truncated = (int)x; You may think that since x is obviously a double (can’t be a float) because 3.14 is a double literal, but this is inaccurate.  Our x could also be dynamic and this would work as well, or there could be user-defined conversions in play.  But there is another, even simpler option that can often bite us: what if x is object? 1: object x; 2:  3: x = 3.14; 4:  5: int truncated = (int) x; On the surface, this seems fine.  We have a double and we place it into an object which can be done implicitly through boxing (no cast) because all types inherit from object.  Then we cast it to int.  This theoretically should be possible because we know we can explicitly convert a double to an int through a conversion process which involves truncation. But here’s the pitfall: when casting an object to another type, we are casting a reference type, not a value type!  This means that it will attempt to see at runtime if the value boxed and referred to by x is of type int or derived from type int.  Since it obviously isn’t (it’s a double after all) we get an invalid cast exception! Now, you may say this looks awfully contrived, but in truth we can run into this a lot if we’re not careful.  Consider using an IDataReader to read from a database, and then attempting to select a result row of a particular column type: 1: using (var connection = new SqlConnection("some connection string")) 2: using (var command = new SqlCommand("select * from employee", connection)) 3: using (var reader = command.ExecuteReader()) 4: { 5: while (reader.Read()) 6: { 7: // if the salary is not an int32 in the SQL database, this is an error! 8: // doesn't matter if short, long, double, float, reader [] returns object! 9: total += (int) reader["annual_salary"]; 10: } 11: } Notice that since the reader indexer returns object, if we attempt to convert using a cast to a type, we have to make darn sure we use the true, actual type or this will fail!  If the SQL database column is a double, float, short, etc this will fail at runtime with an invalid cast exception because it attempts to convert the object reference! So, how do you get around this?  There are two ways, you could first cast the object to its actual type (double), and then do a narrowing cast to on the value to int.  Or you could use a helper class like Convert which analyzes the actual run-time type and will perform a conversion as long as the type implements IConvertible. 1: object x; 2:  3: x = 3.14; 4:  5: // if you want to cast, must cast out of object to double, then 6: // cast convert. 7: int truncated = (int)(double) x; 8:  9: // or you can call a helper class like Convert which examines runtime 10: // type of the value being converted 11: int anotherTruncated = Convert.ToInt32(x); Summary You should always be careful when performing a conversion cast from values boxed in object that you are actually casting to the true type (or a sub-type). Since casting from object is a widening of the reference, be careful that you either know the exact, explicit type you expect to be held in the object, or instead avoid the cast and use a helper class to perform a safe conversion to the type you desire. Technorati Tags: C#,.NET,Pitfalls,Little Pitfalls,BlackRabbitCoder

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