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  • Where is Prolog used for traffic control systems?

    - by Masi
    The user Laurent had an interesting reply to the question [Why hasn’t logic programming caught on?]: If you look at the influence logic-programming has had in the field of -- air traffic control -- I don't think it can be said logic-programming has not caught on. A question arises: Where is prolog used for traffic control systems on the roads? Why is it used instead of languages, such as C or Python, in such environments?

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  • Metaprogramming on web server

    - by bobobobo
    From time to time, I find myself writing server code that produces JavaScript code as the output result. I can point out why it is really bad: Inextricable tie between server code and client code. Can render client code un-reusable. But sometimes, it just seems to make sense. And isn't it kinda sorta interesting? I guess the question is, is writing server code that produces JavaScript code a really bad practice, or "does everyone do it"?

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  • Example of application to design with fingers (source code)

    - by STD
    Hi, i'm new user about this interesting forum! I want start develop application for android and before starting i want learn about some android feature... the first android feature is how to correlate finger motion in screen with java... Exist some source code that show how to realize application to draw with finger in android screen? can you suggest me where donwload it? thanks

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  • C++, class as parameter to a method, not template.

    - by ra170
    So, I came across an interesting method signature that I don't quite understand, it went along the lines of: void Initialize(std::vector< std::string > & param1, class SomeClassName * p); what I don't understand is the "class" keyword being used as the parameter, why is it there? Is it necessary to specify or it is purely superficial?

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  • UIView viewWithTag 0 problem

    - by leon
    Hi, On view in IB I have numerous items (including view itself). ONLY one item has tag 0, yet following line works for ANY UITextBox other then the one with tag 0. Note that only ONE UITextBox has tag 0, why: (UITextField *) [self.view viewWithTag:0]).text = @"foo"; Interesting that when triggered event received for the element with tag 0, I can get value of Tag 0 with no problem. Is there a limitation to look for tag 0 elements?

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  • Easy way to add custom prerequisite in clickonce publish (VS 2010)

    - by Maciej
    I would like to add Infragistics dlls as custom prerequisite when publishing my project. I've read about that: http://msdn.microsoft.com/en-us/library/aa730839%28VS.80%29.aspx But this seems to be a bit complicated... I wonder if exists a bit simple way to archive that (eg by passing URL to setup.exe or such) ? EDIT This Might be also interesting: http://www.codeproject.com/KB/aspnet/Add_Custom_Prerequisite.aspx?msg=2520811 will check and let you know...

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  • Where c++ really shines?

    - by pygabriel
    I know C and python, and I'm moving toward another language for learning purposes. My problem is that I like to learn things with something to do (for example contributing to some project or do something amazing, not boring plain algebra). I would like to hear suggestions about the fields in which C++ shines and where I can found interesting programming with C++. (for fields I mean networking/gui programming/algorithms/games ...)

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  • Fade portfolio image on hover to reveal a magnifying glass or plus sign etc?

    - by ade123
    Hi, I've seen an interesting image hover effect being used a lot lately and was wondering whether anyone has any tips or advice on how best to create this effect? What I'd like to create is a hover effect, so that when you hover over an image, the image fades and a magnifying glass or similar icon fades in. Highlighting the fact that if you click the image, it will enlarge etc. Here is a nice example of the effect: http://themes.mysitemyway.com/infocus/gallery/portfolio/ Any advice or pointers would be greatly appreciated.

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  • Malthusian Growth Model in Ruby

    - by GregDean
    Hello. I am interested in modeling a Malthusian growth model in Ruby. Does anyone have any ideas, or are there any interesting libraries that cover this? Any help is appreciated. http://en.wikipedia.org/wiki/Malthusian_growth_model

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  • Why there are no semicolons and {} blocks in some languages

    - by Incognito
    I know the question has no practical value, but it is interesting why in some languages semicolons and {} blocks are removed although their predecessor have them. Actually it makes me nervous to write a code in Python as there are no ";" and {}. Also in new language Google-GO semicolons are also missing although it says that lexer uses a rule to insert semicolons automatically as it scans. So is there any secret :) reason for this.

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  • Simple Reliable UDP C++ Libraries

    - by EToreo
    Hello, I am in need of a reliable UDP library. The one I wrote does not work too well and I would like to see what a 3rd party can do in the same circumstances. Enet will not work because of some "interesting" compile issues in xcode (I have another question on stack overflow about that). Any suggestions for a portable, reliable UDP library would be greatly appreciated.

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  • Drupal: png is not allowed extension (but it is!)

    - by Patrick
    hi, I'm running Drupal on IIS server 6. I'm having an interesting error to upload images into my node. I get "png" is not a known file. See image: http://dl.dropbox.com/u/72686/pngError.png But I've added png (default settings) to the allow image files list, and indeed you can see in the same image, that png is an allowed extension. Thanks

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  • cf3 Can't stat ... in files.copyfrom promise

    - by Xerxes
    On the client: # cf-agent -KIv ... cf3 -> Handling file existence constraints on /etc/cfengine3 cf3 -> Copy file /etc/cfengine3 from /srv/cfengine/sysconf/server/inputs check cf3 No existing connection to 172.31.69.83 is established... cf3 Set cfengine port number to 5308 = 5308 cf3 -> Connect to 172.31.69.83 = 172.31.69.83 on port 5308 cf3 LastSaw host 172.31.69.83 now cf3 Loaded /var/lib/cfengine3/ppkeys/root-172.31.69.83.pub cf3 .....................[.h.a.i.l.]................................. cf3 Strong authentication of server=172.31.69.83 connection confirmed cf3 Server returned error: Unspecified server refusal (see verbose server output) cf3 Can't stat /srv/cfengine/sysconf/server/inputs in files.copyfrom promise cf3 ?> defining promise result class Cfengine_Inputs_Updated_Failed .... cf3 ......................................................... cf3 Promise handle: cf3 Promise made by: [cf-agent.cf ] FAILED 172.31.69.83:///srv/cfengine/sysconf/server/inputs -> localhost:///etc/cfengine3 However, on the server (172.31.69.83), there's no reason why it can't stat the directory: cyrus:/srv/cfengine/sysconf/server# ls -l /srv/cfengine/sysconf/server/inputs total 52 -rw-r--r-- 1 root root 2142 Sep 6 21:54 cf-agent.cf -rw-r--r-- 1 root root 831 Sep 6 18:31 cf-execd.cf -rw-r--r-- 1 root root 4517 Sep 6 21:44 cf-serverd.cf -rw-r--r-- 1 root root 3082 Sep 6 21:44 dns.cf -rw-r--r-- 1 root root 2028 Sep 6 15:12 failsafe.cf -rw-r--r-- 1 root root 5966 Sep 6 21:44 ldap-masters.cf -rw-r--r-- 1 root root 4380 Sep 6 18:31 ldap-security.cf -rw-r--r-- 1 root root 2735 Sep 6 08:21 lib-core.cf -rw-r--r-- 1 root root 1506 Sep 6 21:45 lib-utils.cf -rw-r--r-- 1 root root 2635 Sep 6 20:27 lib-vars.cf -rw-r--r-- 1 root root 2057 Sep 3 17:46 nss.cf -rw-r--r-- 1 root root 1472 Sep 6 18:31 packages.cf -rw-r--r-- 1 root root 1257 Sep 6 18:01 pam-security.cf -rw-r--r-- 1 root root 4019 Sep 6 19:32 promises.cf -rw-r--r-- 1 root root 2808 Sep 3 17:22 site.cf -rw-r--r-- 1 root root 1670 Sep 6 18:31 sudo-security.cf -rw-r--r-- 1 root root 831 Sep 6 18:31 sys-security.cf -rw-r--r-- 1 root root 890 Sep 6 18:31 sys-users.cf cyrus:/srv/cfengine/sysconf/server# I don't see anything interesting server side either when running: /usr/sbin/cf-serverd -d4 --verbose --no-fork And the following does not have any complaints: /usr/sbin/cf-promises -v Any ideas? I'm running cfengine3 on debian, v3.0.5+dfsg-1 - and the cf-agent.cf file is as follows: bundle agent Update { files: linux:: "${cf3.path[inputs]}" action => immediate, move_obstructions => "true", depth_search => Recursive, copy_from => MirrorFrom( "${cf3.host[server]}", "${cf3.path[scm-inputs]}", "true", "0400" ), classes => DefineSoftClass("Cfengine_Inputs_Updated") ; "${cf3.path[sbin]}" comment => "Setting cf3 client sbin scripts: ${cf3.path[sbin]}/", action => immediate, depth_search => Recursive, copy_from => MirrorFrom( "${cf3.host[server]}", "${cf3.path[scm-cnt-scripts]}", "false", "0555" ) ; reports: Cfengine_Inputs_Updated:: "[cf-agent.cf ] Services:CFAgent:Inputs:Updated"; Cfengine_Inputs_Updated_Failed:: "[cf-agent.cf ] FAILED ${cf3.host[server]}://${cf3.path[scm-inputs]} -> localhost://${cf3.path[inputs]}"; } I lie, there is something interesting with a little more debugging... AccessControl(/srv/cfengine/sysconf/server/inputs) AccessControl, match(/srv/cfengine/sysconf/server/inputs,client.com.au) encrypt request=1 Examining rule in access list (/srv/cfengine/sysconf/server/inputs,/home/cfengine)? cf3 Host client.com.au denied access to /srv/cfengine/sysconf/server/inputs Unappending Host client.com.au denied access to /srv/cfengine/sysconf/server/inputs cf3 Access control in sync Unappending Access control in sync Transaction Send[t 59][Packed text] Attempting to send 67 bytes SendSocketStream, sent 67 cf3 From (host=client.com.au,user=root,ip=172.31.69.3) Unappending From (host=client.com.au,user=root,ip=172.31.69.3) cf3 REFUSAL of request from connecting host: (SYNCH 1283777156 STAT /srv/cfengine/sysconf/server/inputs) Unappending REFUSAL of request from connecting host: (SYNCH 1283777156 STAT /srv/cfengine/sysconf/server/inputs) RecvSocketStream(8) cf3 -> Accepting a connection I'll keep looking.

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  • Linux not buffering block I/O when the device is not "in use" (i.e. mounted)

    - by Radek Hladík
    I am installing new server and I've found an interesting issue. The server is running Fedora 19 (3.11.7-200.fc19.x86_64 kernel) and is supposed to host a few KVM/Qemu virtual servers (mail server, file server, etc..). The HW is Intel(R) Xeon(R) CPU 5160 @ 3.00GHz with 16GB RAM. One of the most important features will be Samba server and we have decided to make it as virtual machine with almost direct access to the disks. So the real HDD is cached on SSD (via bcache) then raided with md and the final device is exported into the virtual machine via virtio. The virtual machine is again Fedora 19 with the same kernel. One important topic to find out is whether the virtualization layer will not introduce high overload into disk I/Os. So far I've been able to get up to 180MB/s in VM and up to 220MB/s on real HW (on the SSD disk). I am still not sure why the overhead is so big but it is more than the network can handle so I do not care so much. The interesting thing is that I've found that the disk reads are not buffered in the VM unless I create and mount FS on the disk or I use the disks somehow. Simply put: Lets do dd to read disk for the first time (the /dev/vdd is an old Raptor disk 70MB/s is its real speed): [root@localhost ~]# dd if=/dev/vdd of=/dev/null bs=256k count=10000 ; cat /proc/meminfo | grep Buffers 2621440000 bytes (2.6 GB) copied, 36.8038 s, 71.2 MB/s Buffers: 14444 kB Rereading the data shows that they are cached somewhere but not in buffers of the VM. Also the speed increased to "only" 500MB/s. The VM has 4GB of RAM (more that the test file) [root@localhost ~]# dd if=/dev/vdd of=/dev/null bs=256k count=10000 ; cat /proc/meminfo | grep Buffers 2621440000 bytes (2.6 GB) copied, 5.16016 s, 508 MB/s Buffers: 14444 kB [root@localhost ~]# dd if=/dev/vdd of=/dev/null bs=256k count=10000 ; cat /proc/meminfo | grep Buffers 2621440000 bytes (2.6 GB) copied, 5.05727 s, 518 MB/s Buffers: 14444 kB Now lets mount the FS on /dev/vdd and try the dd again: [root@localhost ~]# mount /dev/vdd /mnt/tmp [root@localhost ~]# dd if=/dev/vdd of=/dev/null bs=256k count=10000 ; cat /proc/meminfo | grep Buffers 2621440000 bytes (2.6 GB) copied, 4.68578 s, 559 MB/s Buffers: 2574592 kB [root@localhost ~]# dd if=/dev/vdd of=/dev/null bs=256k count=10000 ; cat /proc/meminfo | grep Buffers 2621440000 bytes (2.6 GB) copied, 1.50504 s, 1.7 GB/s Buffers: 2574592 kB While the first read was the same, all 2.6GB got buffered and the next read was at 1.7GB/s. And when I unmount the device: [root@localhost ~]# umount /mnt/tmp [root@localhost ~]# cat /proc/meminfo | grep Buffers Buffers: 14452 kB [root@localhost ~]# dd if=/dev/vdd of=/dev/null bs=256k count=10000 ; cat /proc/meminfo | grep Buffers 2621440000 bytes (2.6 GB) copied, 5.10499 s, 514 MB/s Buffers: 14468 kB The bcache was disabled while testing and the results are same on faster (newer) HDDs and on SSD (except for the initial read speed of course). To sum it up. When I read from the device via dd first time, it gets read from the disk. Next time I reread it gets cached in the host but not in the guest (thats actually the same issue, more on that later). When I mount the filesystem but try to read the device directly it gets cached in VM (via buffers). As soon as I stop "using" it, buffers are discarded and the device is not cached anymore in the VM. When I looked into buffers value on the host I realized that the situation is the same. The block I/O gets buffered only when the disk is in use, in this case it means "exported to a VM". On host, after all the measurement done: 3165552 buffers On the host, after the VM shutdown: 119176 buffers I know it is not important as the disks will be mounted all the time but I am curious and I would like to know why it is working like this.

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  • SNTP, why do you mock me?!

    - by Matthew
    --- SOLVED SEE EDIT 5 --- My w2k3 pdc is configured as an authoritative time server. Other servers on the domain are able to sync with it if I manually specify it in the peer list. By if I try to sync from flags 'domhier', it wont resync; I get the error message The computer did not resync because no time data was available. I can only think that it is not querying the pdc. I also tried setting the registry as shown here (http://support.microsoft.com/kb/193825). But no luck (I have not restarted the server, I am hoping I wont have to since it is the pdc) If you would like any further information on my config, please let me know. Edit 1: I have set the w32time service config AnnouceFlags to 0x05 as documented here www.krr.org/microsoft/authoritative_time_servers.php and a number of other places. The PDC syncs to an external time source (ntp). I can get the stripchart on the client from the pdc no problems. The loginserver for the host I am trying to configure is shown as the pdc. Edit 2: The packet capture has revealed something interesting. The client is contacting the correct server, and getting a valid response but I still get the same error message. Here is the NTP excerpt from the client to the server Flags: 11.. .... = Leap Indicator: alarm condition (clock not synchronized) (3) ..01 1... = Version number: NTP Version 3 (3) .... .011 = Mode: client (3) Peer Clock Stratum: unspecified or unavailable (0) Peer Polling Interval: 10 (1024 sec) Peer Clock Precision: 0.015625 sec Root Delay: 0.0000 sec Root Dispersion: 1.0156 sec Reference Clock ID: NULL Reference Clock Update Time: Sep 1, 2010 05:29:39.8170 UTC Originate Time Stamp: NULL Receive Time Stamp: NULL Transmit Time Stamp: Nov 8, 2010 01:44:44.1450 UTC Key ID: DC080000 Here is the reply NTP excerpt from the server to the client Flags: 0x1c 00.. .... = Leap Indicator: no warning (0) ..01 1... = Version number: NTP Version 3 (3) .... .100 = Mode: server (4) Peer Clock Stratum: secondary reference (3) Peer Polling Interval: 10 (1024 sec) Peer Clock Precision: 0.00001 sec Root Delay: 0.1484 sec Root Dispersion: 0.1060 sec Reference Clock ID: 192.189.54.17 Reference Clock Update Time: Nov 8,2010 01:18:04.6223 UTC Originate Time Stamp: Nov 8, 2010 01:44:44.1450 UTC Receive Time Stamp: Nov 8, 2010 01:46:44.1975 UTC Transmit Time Stamp: Nov 8, 2010 01:46:44.1975 UTC Key ID: 00000000 Edit 3: dumpreg for paramters on pdc Value Name Value Type Value Data ------------------------------------------------------------------------ ServiceMain REG_SZ SvchostEntry_W32Time ServiceDll REG_EXPAND_SZ C:\WINDOWS\system32\w32time.dll NtpServer REG_SZ bhvmmgt01.domain.com,0x1 Type REG_SZ AllSync and config Value Name Value Type Value Data -------------------------------------------------------------------------- LastClockRate REG_DWORD 156249 MinClockRate REG_DWORD 155860 MaxClockRate REG_DWORD 156640 FrequencyCorrectRate REG_DWORD 4 PollAdjustFactor REG_DWORD 5 LargePhaseOffset REG_DWORD 50000000 SpikeWatchPeriod REG_DWORD 900 HoldPeriod REG_DWORD 5 LocalClockDispersion REG_DWORD 10 EventLogFlags REG_DWORD 2 PhaseCorrectRate REG_DWORD 7 MinPollInterval REG_DWORD 6 MaxPollInterval REG_DWORD 10 UpdateInterval REG_DWORD 100 MaxNegPhaseCorrection REG_DWORD -1 MaxPosPhaseCorrection REG_DWORD -1 AnnounceFlags REG_DWORD 5 MaxAllowedPhaseOffset REG_DWORD 300 FileLogSize REG_DWORD 10000000 FileLogName REG_SZ C:\Windows\Temp\w32time.log FileLogEntries REG_SZ 0-300 Edit 4: Here are some notables from the ntp log file on the pdc. ReadConfig: failed. Use default one 'TimeJumpAuditOffset'=0x00007080 DomainHierachy: we are now the domain root. ClockDispln: we're a reliable time service with no time source: LS: 0, TN: 864000000000, WAIT: 86400000 Edit 5: F&^%ING SOLVED! Ok so I was reading about people with similar problems, some mentioned w32time server settings applied by GPO, but I tested this early on and there were no settings applied to this service by gpo. Others said that the reporting software may not be picking up some old gpo settings applied. So I searched the registry for all w32time instaces. I came across an interesting key that indicated there may be some other ntp software running on the server. Sure enough, I look through the installed software list and there the little F*&%ER is. Uninstalled and now working like a dream. FFFFFFFUUUUUUUUUUUU

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  • Why should you choose Oracle WebLogic 12c instead of JBoss EAP 6?

    - by Ricardo Ferreira
    In this post, I will cover some technical differences between Oracle WebLogic 12c and JBoss EAP 6, which was released a couple days ago from Red Hat. This article claims to help you in the evaluation of key points that you should consider when choosing for an Java EE application server. In the following sections, I will present to you some important aspects that most customers ask us when they are seriously evaluating for an middleware infrastructure, specially if you are considering JBoss for some reason. I would suggest that you keep the following question in mind while you are reading the points: "Why should I choose JBoss instead of WebLogic?" 1) Multi Datacenter Deployment and Clustering - D/R ("Disaster & Recovery") architecture support is embedded on the WebLogic Server 12c product. JBoss EAP 6 on the other hand has no direct D/R support included, Red Hat relies on third-part tools with higher prices. When you consider a middleware solution to host your business critical application, you should worry with every architectural aspect that are related with the solution. Fail-over support is one little aspect of a truly reliable solution. If you do not worry about D/R, your solution will not be reliable. Having said that, with Red Hat and JBoss EAP 6, you have this extra cost that will increase considerably the total cost of ownership of the solution. As we commonly hear from analysts, open-source are not so cheaper when you start seeing the big picture. - WebLogic Server 12c supports advanced LAN clustering, detection of death servers and have a common alert framework. JBoss EAP 6 on the other hand has limited LAN clustering support with no server death detection. They do not generate any alerts when servers goes down (only if you buy JBoss ON which is a separated technology, but until now does not support JBoss EAP 6) and manual intervention are required when servers goes down. In most cases, admin people must rely on "kill -9", "tail -f someFile.log" and "ps ax | grep java" commands to manage failures and clustering anomalies. - WebLogic Server 12c supports the concept of Node Manager, which is a separated process that runs on the physical | virtual servers that allows extend the administration of the cluster to WebLogic managed servers that are often distributed across multiple machines and geographic locations. JBoss EAP 6 on the other hand has no equivalent technology. Whole server instances must be managed individually. - WebLogic Server 12c Node Manager supports Coherence to boost performance when managing servers. JBoss EAP 6 on the other hand has no similar technology. There is no way to coordinate JBoss and infiniband instances provided by JBoss using high throughput and low latency protocols like InfiniBand. The Node Manager feature also allows another very important feature that JBoss EAP lacks: secure the administration. When using WebLogic Node Manager, all the administration tasks are sent to the managed servers in a secure tunel protected by a certificate, which means that the transport layer that separates the WebLogic administration console from the managed servers are secured by SSL. - WebLogic Server 12c are now integrated with OTD ("Oracle Traffic Director") which is a web server technology derived from the former Sun iPlanet Web Server. This software complements the web server support offered by OHS ("Oracle HTTP Server"). Using OTD, WebLogic instances are load-balanced by a high powerful software that knows how to handle SDP ("Socket Direct Protocol") over InfiniBand, which boost performance when used with engineered systems technologies like Oracle Exalogic Elastic Cloud. JBoss EAP 6 on the other hand only offers support to Apache Web Server with custom modules created to deal with JBoss clusters, but only across standard TCP/IP networks.  2) Application and Runtime Diagnostics - WebLogic Server 12c have diagnostics capabilities embedded on the server called WLDF ("WebLogic Diagnostic Framework") so there is no need to rely on third-part tools. JBoss EAP 6 on the other hand has no diagnostics capabilities. Their only diagnostics tool is the log generated by the application server. Admin people are encouraged to analyse thousands of log lines to find out what is going on. - WebLogic Server 12c complement WLDF with JRockit MC ("Mission Control"), which provides to administrators and developers a complete insight about the JVM performance, behavior and possible bottlenecks. WebLogic Server 12c also have an classloader analysis tool embedded, and even a log analyzer tool that enables administrators and developers to view logs of multiple servers at the same time. JBoss EAP 6 on the other hand relies on third-part tools to do something similar. Again, only log searching are offered to find out whats going on. - WebLogic Server 12c offers end-to-end traceability and monitoring available through Oracle EM ("Enterprise Manager"), including monitoring of business transactions that flows through web servers, ESBs, application servers and database servers, all of this with high deep JVM analysis and diagnostics. JBoss EAP 6 on the other hand, even using JBoss ON ("Operations Network"), which is a separated technology, does not support those features. Red Hat relies on third-part tools to provide direct Oracle database traceability across JVMs. One of those tools are Oracle EM for non-Oracle middleware that manage JBoss, Tomcat, Websphere and IIS transparently. - WebLogic Server 12c with their JRockit support offers a tool called JRockit Flight Recorder, which can give developers a complete visibility of a certain period of application production monitoring with zero extra overhead. This automatic recording allows you to deep analyse threads latency, memory leaks, thread contention, resource utilization, stack overflow damages and GC ("Garbage Collection") cycles, to observe in real time stop-the-world phenomenons, generational, reference count and parallel collects and mutator threads analysis. JBoss EAP 6 don't even dream to support something similar, even because they don't have their own JVM. 3) Application Server Administration - WebLogic Server 12c offers a complete administration console complemented with scripting and macro-like recording capabilities. A single WebLogic console can managed up to hundreds of WebLogic servers belonging to the same domain. JBoss EAP 6 on the other hand has a limited console and provides a XML centric administration. JBoss, after ten years, started the development of a rudimentary centralized administration that still leave a lot of administration tasks aside, so admin people and developers must touch scripts and XML configuration files for most advanced and even simple administration tasks. This lead applications to error prone and risky deployments. Even using JBoss ON, JBoss EAP are not able to offer decent administration features for admin people which must be high skilled in JBoss internal architecture and its managing capabilities. - Oracle EM is available to manage multiple domains, databases, application servers, operating systems and virtualization, with a complete end-to-end visibility. JBoss ON does not provide management capabilities across the complete architecture, only basic monitoring. Even deployment must be done aside JBoss ON which does no integrate well with others softwares than JBoss. Until now, JBoss ON does not supports JBoss EAP 6, so even their minimal support for JBoss are not available for JBoss EAP 6 leaving customers uncovered and subject to high skilled JBoss admin people. - WebLogic Server 12c has the same administration model whatever is the topology selected by the customer. JBoss EAP 6 on the other hand differentiates between two operational models: standalone-mode and domain-mode, that are not consistent with each other. Depending on the mode used, the administration skill is different. - WebLogic Server 12c has no point-of-failures processes, and it does not need to define any specialized server. Domain model in WebLogic is available for years (at least ten years or more) and is production proven. JBoss EAP 6 on the other hand needs special processes to garantee JBoss integrity, the PC ("Process-Controller") and the HC ("Host-Controller"). Different from WebLogic, the domain model in JBoss is quite new (one year at tops) of maturity, and need to mature considerably until start doing things like WebLogic domain model does. - WebLogic Server 12c supports parallel deployment model which enables some artifacts being deployed at the same time. JBoss EAP 6 on the other hand does not have any similar feature. Every deployment are done atomically in the containers. This means that if you have a huge EAR (an EAR of 120 MB of size for instance) and deploy onto JBoss EAP 6, this EAR will take some minutes in order to starting accept thread requests. The same EAR deployed onto WebLogic Server 12c will reduce the deployment time at least in 2X compared to JBoss. 4) Support and Upgrades - WebLogic Server 12c has patch management available. JBoss EAP 6 on the other hand has no patch management available, each JBoss EAP instance should be patched manually. To achieve such feature, you need to buy a separated technology called JBoss ON ("Operations Network") that manage this type of stuff. But until now, JBoss ON does not support JBoss EAP 6 so, in practice, JBoss EAP 6 does not have this feature. - WebLogic Server 12c supports previuous WebLogic domains without any reconfiguration since its kernel is robust and mature since its creation in 1995. JBoss EAP 6 on the other hand has a proven lack of supportability between JBoss AS 4, 5, 6 and 7. Different kernels and messaging engines were implemented in JBoss stack in the last five years reveling their incapacity to create a well architected and proven middleware technology. - WebLogic Server 12c has patch prescription based on customer configuration. JBoss EAP 6 on the other hand has no such capability. People need to create ticket supports and have their installations revised by Red Hat support guys to gain some patch prescription from them. - Oracle WebLogic Server independent of the version has 8 years of support of new patches and has lifetime release of existing patches beyond that. JBoss EAP 6 on the other hand provides patches for a specific application server version up to 5 years after the release date. JBoss EAP 4 and previous versions had only 4 years. A good question that Red Hat will argue to answer is: "what happens when you find issues after year 5"?  5) RAC ("Real Application Clusters") Support - WebLogic Server 12c ships with a specific JDBC driver to leverage Oracle RAC clustering capabilities (Fast-Application-Notification, Transaction Affinity, Fast-Connection-Failover, etc). Oracle JDBC thin driver are also available. JBoss EAP 6 on the other hand ships only the standard Oracle JDBC thin driver. Load balancing with Oracle RAC are not supported. Manual intervention in case of planned or unplanned RAC downtime are necessary. In JBoss EAP 6, situation does not reestablish automatically after downtime. - WebLogic Server 12c has a feature called Active GridLink for Oracle RAC which provides up to 3X performance on OLTP applications. This seamless integration between WebLogic and Oracle database enable more value added to critical business applications leveraging their investments in Oracle database technology and Oracle middleware. JBoss EAP 6 on the other hand has no performance gains at all, even when admin people implement some kind of connection-pooling tuning. - WebLogic Server 12c also supports transaction and web session affinity to the Oracle RAC, which provides aditional gains of performance. This is particularly interesting if you are creating a reliable solution that are distributed not only in an LAN cluster, but into a different data center. JBoss EAP 6 on the other hand has no such support. 6) Standards and Technology Support - WebLogic Server 12c is fully Java EE 6 compatible and production ready since december of 2011. JBoss EAP 6 on the other hand became fully compatible with Java EE 6 only in the community version after three months, and production ready only in a few days considering that this article was written in June of 2012. Red Hat says that they are the masters of innovation and technology proliferation, but compared with Oracle and even other proprietary vendors like IBM, they historically speaking are lazy to deliver the most newest technologies and standards adherence. - Oracle is the steward of Java, driving innovation into the platform from commercial and open-source vendors. Red Hat on the other hand does not have its own JVM and relies on third-part JVMs to complete their application server offer. 95% of Red Hat customers are using Oracle HotSpot as JVM, which means that without Oracle involvement, their support are limited exclusively to the application server layer and we all know that most problems are happens in the JVM layer. - WebLogic Server 12c supports natively JDK 7, which empower developers to explore the maximum of the Java platform productivity when writing code. This feature differentiate WebLogic from others application servers (except GlassFish that are also managed by Oracle) because the usage of JDK 7 introduce such remarkable productivity features like the "try-with-resources" enhancement, catching multiple exceptions with one try block, Strings in the switch statements, JVM improvements in terms of JDBC, I/O, networking, security, concurrency and of course, the most important feature of Java 7: native support for multiple non-Java languages. More features regarding JDK 7 can be found here. JBoss EAP 6 on the other hand does not support JDK 7 officially, they comment in their community version that "Java SE 7 can be used with JBoss 7" which does not gives you any guarantees of enterprise support for JDK 7. - Oracle WebLogic Server 12c supports integration with Spring framework allowing Spring applications to use WebLogic special transaction manager, exposing bean interfaces to WebLogic MBeans to take advantage of all WebLogic monitoring and administration advantages. JBoss EAP 6 on the other hand has no special integration with Spring. In fact, Red Hat offers a suspicious package called "JBoss Web Platform" that in theory supports Spring, but in practice this package does not offers any special integration. It is just a facility for Red Hat customers to have support from both JBoss and Spring technology using the same customer support. 7) Lightweight Development - Oracle WebLogic Server 12c and Oracle GlassFish are completely integrated and can share applications without any modifications. Starting with the 12c version, WebLogic now understands natively GlassFish deployment descriptors and specific configurations in order to offer you a truly and reliable migration path from a community Java EE application server to a enterprise middleware product like WebLogic. JBoss EAP 6 on the other hand has no support to natively reuse an existing (or still in development) application from JBoss AS community server. Users of JBoss suffer of critical issues during deployment time that includes: changing the libraries and dependencies of the application, patching the DTD or XSD deployment descriptors, refactoring of the application layers due classloading issues and anomalies, rebuilding of persistence, business and web layers due issues with "usage of the certified version of an certain dependency" or "frameworks that Red Hat potentially does not recommend" etc. If you have the culture or enterprise IT directive of developing Java EE applications using community middleware to in a certain future, transition to enterprise (supported by a vendor) middleware, Oracle WebLogic plus Oracle GlassFish offers you a more sustainable solution. - WebLogic Server 12c has a very light ZIP distribution (less than 165 MB). JBoss EAP 6 ZIP size is around 130 MB, together with JBoss ON you have more 100 MB resulting in a higher download footprint. This is particularly interesting if you plan to use automated setup of application server instances (for example, to rapidly setup a development or staging environment) using Maven or Hudson. - WebLogic Server 12c has a complete integration with Maven allowing developers to setup WebLogic domains with few commands. Tasks like downloading WebLogic, installation, domain creation, data sources deployment are completely integrated. JBoss EAP 6 on the other hand has a limited offer integration with those tools.  - WebLogic Server 12c has a startup mode called WLX that turns-off EJB, JMS and JCA containers leaving enabled only the web container with Java EE 6 web profile. JBoss EAP 6 on the other hand has no such feature, you need to disable manually the containers that you do not want to use. - WebLogic Server 12c supports fastswap, which enables you to change classes without redeployment. This is particularly interesting if you are developing patches for the application that is already deployed and you do not want to redeploy the entire application. This is the same behavior that most application servers offers to JSP pages, but with WebLogic Server 12c, you have the same feature for Java classes in general. JBoss EAP 6 on the other hand has no such support. Even JBoss EAP 5 does not support this until now. 8) JMS and Messaging - WebLogic Server 12c has a proven and high scalable JMS implementation since its initial release in 1995. JBoss EAP 6 on the other hand has a still immature technology called HornetQ, which was introduced in JBoss EAP 5 replacing everything that was implemented in the previous versions. Red Hat loves to introduce new technologies across JBoss versions, playing around with customers and their investments. And when they are asked about why they have changed the implementation and caused such a mess, their answer is always: "the previous implementation was inadequate and not aligned with the community strategy so we are creating a new a improved one". This Red Hat practice leads to uncomfortable investments that in a near future (sometimes less than a year) will be affected in someway. - WebLogic Server 12c has troubleshooting and monitoring features included on the WebLogic console and WLDF. JBoss EAP 6 on the other hand has no direct monitoring on the console, activity is reflected only on the logs, no debug logs available in case of JMS issues. - WebLogic Server 12c has extremely good performance and scalability. JBoss EAP 6 on the other hand has a JMS storage mechanism relying on Oracle database or MySQL. This means that if an issue in production happens and Red Hat affirms that an performance issue is happening due to database problems, they will not support you on the performance issue. They will orient you to call Oracle instead. - WebLogic Server 12c supports messaging enterprise features like SAF ("Store and Forward"), Distributed Queues/Topics and Foreign JMS providers support that leverage JMS implementations without compromise developer code making things completely transparent. JBoss EAP 6 on the other hand do not even dream to support such features. 9) Caching and Grid - Coherence, which is the leading and most mature data grid technology from Oracle, is available since early 2000 and was integrated with WebLogic in 2009. Coherence and WebLogic clusters can be both managed from WebLogic administrative console. Even Node Manager supports Coherence. JBoss on the other hand discontinued JBoss Cache, which was their caching implementation just like they did with the messaging implementation (JBossMQ) which was a issue for long term customers. JBoss EAP 6 ships InfiniSpan version 1.0 which is immature and lack a proven record of successful cases and reliability. - WebLogic Server 12c has a feature called ActiveCache which uses Coherence to, without any code changes, replicate HTTP sessions from both WebLogic and other application servers like JBoss, Tomcat, Websphere, GlassFish and even Microsoft IIS. JBoss EAP 6 on the other hand does have such support and even when they do in the future, they probably will support only their own application server. - Coherence can be used to manage both L1 and L2 cache levels, providing support to Oracle TopLink and others JPA compliant implementations, even Hibernate. JBoss EAP 6 and Infinispan on the other hand supports only Hibernate. And most important of all: Infinispan does not have any successful case of L1 or L2 caching level support using Hibernate, which lead us to reflect about its viability. 10) Performance - WebLogic Server 12c is certified with Oracle Exalogic Elastic Cloud and can run unchanged applications at this engineered system. This approach can benefit customers from Exalogic optimization's of both kernel and JVM layers to boost performance in terms of 10X for web, OLTP, JMS and grid applications. JBoss EAP 6 on the other hand has no investment on engineered systems: customers do not have the choice to deploy on a Java ultra fast system if their project becomes relevant and performance issues are detected. - WebLogic Server 12c maintains a performance gain across each new release: starting on WebLogic 5.1, the overall performance gain has been close to 4X, which close to a 20% gain release by release. JBoss on the other hand does not provide SPECJAppServer or SPECJEnterprise performance benchmarks. Their so called "performance gains" remains hidden in their customer environments, which lead us to think if it is true or not since we will never get access to those environments. - WebLogic Server 12c has industry performance benchmarks with submissions across platforms and configurations leading SPECJ. Oracle WebLogic leads SPECJAppServer performance in multiple categories, fitting all customer topologies like: dual-node, single-node, multi-node and multi-node with RAC. JBoss... again, does not provide any SPECJAppServer performance benchmarks. - WebLogic Server 12c has a feature called work manager which allows your application to embrace new performance levels based on critical resource utilization of the CPUs usage. Work managers prioritizes work and allocates threads based on an execution model that takes into account administrator-defined parameters and actual run-time performance and throughput. JBoss EAP 6 on the other hand has no compared feature and probably they never will. Not supporting such feature like work managers, JBoss EAP 6 forces admin people and specially developers to uncover performance gains in a intrusive way, rewriting the code and doing performance refactorings. 11) Professional Services Support - WebLogic Server 12c and any other technology sold by Oracle give customers the possibility of hire OCS ("Oracle Consulting Services") to manage critical scenarios, deployment assistance of new applications, high skilled consultancy of architecture, best practices and people allocation together with customer teams. All OCS services are available without any restrictions, having the customer bought software from Oracle or just starting their implementation before any acquisition. JBoss EAP 6 or Red Hat to be more specifically, only offers professional services if you buy subscriptions from them. If you are developing a new critical application for your business and need the help of Red Hat for a serious issue or architecture decision, they will probably say: "OK... I can help you but after you buy subscriptions from me". Red Hat also does not allows their professional services consultants to manage environments that uses community based software. They will probably force you to first buy a subscription, download their "enterprise" version and them, optionally hire their consultants. - Oracle provides you our university to educate your team into our technologies, including of course specialized trainings of WebLogic application server. At any time and location, you can hire Oracle to train your team so you get trustful knowledge according to your specific needs. Certifications for the products are also available if your technical people desire to differentiate themselves as professionals. Red Hat on the other hand have a limited pool of resources to train your team in their technologies. Basically they are selling training and certification for RHEL ("Red Hat Enterprise Linux") but if you demand more specialized training in JBoss middleware, they will probably connect you to some "certified" partner localized training since they are apparently discontinuing their education center, at least here in Brazil. They were not able to reproduce their success with RHEL education to their middleware division since they need first sell the subscriptions to after gives you specialized training. And again, they only offer you specialized training based on their enterprise version (EAP in the case of JBoss) which means that the courses will be a quite outdated. There are reports of developers that took official training's from Red Hat at this year (2012) and in a certain JBoss advanced course, Red Hat supposedly covered JBossMQ as the messaging subsystem, and even the printed material provided was based on JBossMQ since the training was created for JBoss EAP 4.3. 12) Encouraging Transparency without Ulterior Motives - WebLogic Server 12c like any other software from Oracle can be downloaded any time from anywhere, you should only possess an OTN ("Oracle Technology Network") credential and you can download any enterprise software how many times you want. And is not some kind of "trial" version. It is the official binaries that will be running for ever in your data center. Oracle does not encourages the usage of "specific versions" of our software. The binaries you buy from Oracle are the same binaries anyone in the world could download and use for testing and personal education. JBoss EAP 6 on the other hand are not available for download unless you buy a subscription and get access to the Red Hat enterprise repositories. If you need to test, learn or just start creating your application using Red Hat's middleware software, you should download it from the community website. You are not allowed to download the enterprise version that, according to Red Hat are more secure, reliable and robust. But no one of us want to start the development of a software with an unsecured, unreliable and not scalable middleware right? So what you do? You are "invited" by Red Hat to buy subscriptions from them to get access to the "cool" version of the software. - WebLogic Server 12c prices are publicly available in the Oracle website. If you want to know right now how much WebLogic will cost to your organization, just click here and get access to our price list. In the case of WebLogic, check out the "US Oracle Technology Commercial Price List". Oracle also encourages you to get in touch with a sales representative to discuss discounts that would make possible the investment into our technology. But you are not required to do this, only if you are interested in buying our technology or maybe you want to discuss some discount scenarios. JBoss EAP 6 on the other hand does not have its cost publicly available in Red Hat's website or in any other media, at least is not so easy to get such information. The only link you will possibly find in their website is a "Contact a Sales Representative" link. This is not a very good relationship between an customer and an vendor. This is not an example of transparency, mainly when the software are sold as open. In this situations, customers expects to see the software prices publicly available, so they can have the chance to decide, based on the existing features of the software, if the cost is fair or not. Conclusion Oracle WebLogic is the most mature, secure, reliable and scalable Java EE application server of the market, and have a proven record of success around the globe to prove it's majority. Don't lose the chance to discover today how WebLogic could fit your needs and sustain your global IT middleware strategy, no matter if your strategy are completely based on the Cloud or not.

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  • Using jQuery and SPServices to Display List Items

    - by Bil Simser
    I had an interesting challenge recently that I turned to Marc Anderson’s wonderful SPServices project for. If you haven’t already seen or used SPServices, please do. It’s a jQuery library that does primarily two things. First, it wraps up all of the SharePoint web services in a nice little AJAX wrapper for use in JavaScript. Second, it enhances the form editing of items in SharePoint so you’re not hacking up your List Form pages. My challenge was simple but interesting. The user wanted to display a SharePoint item page (DispForm.aspx, which already had some customization on it to display related items via this blog post from Codeless Solutions for SharePoint) but launch from an external application using the value of one of the fields in the SharePoint list. For simplicity let’s say my list is a list of customers and the related list is a list of orders for that customer. It would look something like this (click on the item to see the full image): Your first thought might be, that’s easy! Display the customer information using a DataView Web Part and filter the item using a query string to match the customer number. However there are a few problems with this idea: You’ll need to build a custom page and then attach that related orders view to it. This is a bit of a problem because the solution from Codeless Solutions relies on the Title field on the page to be displayed. On a custom page you would have to recreate all of the elements found on the DispForm.aspx page so the related view would work. The DataView Web Part doesn’t look *exactly* like what the out of the box display form page does. Not a huge problem and can be overcome with some CSS style overrides but still, more work. A DVWP showing a single record doesn’t have the same toolbar that you would using the DispForm.aspx. Not a show-stopper and you can rebuild the toolbar but it’s going to potentially require code and then there’s the security trimming, etc. that you have to get right. DVWPs are not automatically updated if you add a column to the list like DispForm.aspx is. Work, work, work. For these reasons I thought it would be easier to take the already existing (modified) DispForm.aspx page and just add some jQuery magic to the page to find the item. Why do we need to find it? DispForm.aspx relies on a querystring parameter called “ID” which then displays whatever that item ID number is in the list. Trouble is, when you’re coming in from an external app via a link, you don’t know what that internal ID is (and frankly shouldn’t). I don’t like exposing internal SharePoint IDs to the outside world for the same reason I don’t do it with database IDs. They’re internal and while it’s find to use on the site itself you don’t want external links using it. It’s volatile and can change (delete one item then re-add it back with the same data and watch any ID references break). The next thought might be to call a SharePoint web service with a CAML query to get the item ID number using some criteria (in this case, the customer number). That’s great if you have that ability but again we had an existing application we were just adding a link to. The last thing I wanted to do was to crack open the code on that sucker and start calling web services (primarily because it’s Java, but really I’m a lazy geek). However if you’re doing this and have access to call a web service that would be an option. Back to this problem, how do I a) find a SharePoint List Item based on some field value other than ID and b) make it low impact so I can just construct a URL to it? That’s where jQuery and SPServices came to the rescue. After spending a few hours of emails back and forth with Marc and a couple of phone calls (and updating jQuery to the latest version, duh!) it was a simple answer. First we need a reference to a) jQuery b) SPServices and c) our script. I just dropped a Content Editor Web Part, the Swiss Army Knives of Web Parts, onto the DispForm.aspx page and added these lines: <script type="text/javascript" src="http://intranet/JavaScript/jquery-1.4.2.min.js"></script> <script type="text/javascript" src="http://intranet/JavaScript/jquery.SPServices-0.5.3.min.js"></script> <script type="text/javascript" src="http://intranet/JavaScript/RedirectToID.js"> </script> Update it to point to where you keep your scripts located. I prefer to keep them all in Document Libraries as I can make changes to them without having to remote into the server (and on a multiple web front end, that’s just a PITA), it provides me with version control of sorts, and it’s quick to add new plugins and scripts. Now we can look at our RedirectToID.js script. This invokes the SPServices Library to call the GetListItems method of the Lists web service and then rewrites the URL to DispForm.aspx to use the correct SharePoint ID (the internal one). $(document).ready(function(){ var queryStringValues = $().SPServices.SPGetQueryString(); var id = queryStringValues["ID"]; if(id == "0") { var customer = queryStringValues["CustomerNumber"]; var query = "<Query><Where><Eq><FieldRef Name='CustomerNumber'/><Value Type='Text'>" + customer + "</Value></Eq></Where></Query>"; var url = window.location; $().SPServices({ operation: "GetListItems", listName: "Customers", async: false, CAMLQuery: query, completefunc: function (xData, Status) { $(xData.responseXML).find("[nodeName=z:row]").each(function(){ id = $(this).attr("ows_ID"); url = $().SPServices.SPGetCurrentSite() + "/Lists/Customers/DispForm.aspx?ID=" + id; window.location = url; }); } }); } }); What’s happening here? Line 3: We call SPServices.SPGetQueryString to get an array of query string values (a handy function in the library as I had 15 lines of code to do this which is now gone). Line 4: Extract the ID value from the query string Line 6: If we pass in “0” it means we’re looking up a field value. This allows DispForm.aspx to work like normal with SharePoint lists but lookup our values when invoked. Why ID at all? DispForm.aspx doesn’t work unless you pass in something and “0” is a *magic* number that will invoke the page but not lookup a value in the database. Line 8-15: Extract the CustomerNumber query string value, build a CAML query to find it then call the GetListitems method using SPServices Line 16: Process the results in our completefunc to iterate over all the rows (there should only be one) and extract the real ID of the item Line 17-20: Build a new URL based on the site (using a call to SPGetCurrentSite) and append our real ID to redirect to the DispForm.aspx page As you can see, it dynamically creates a CAML query for the call to the web service using the passed in value. You could even make this generic to take in different query strings, one for the field name to search for and the other for the value to find. That way it could be used for any field you want. For example you could bring up the correct item on the DispForm.aspx page based on customer name with something like this: http://myserver/Lists/Customers/DispForm.aspx?ID=0&FilterId=CustomerName&FilterValue=Sony Use your imagination. Some people would opt for building a custom page with a DVWP but if you want to leverage all the functionality of DispForm.aspx this might come in handy if you don’t want to rely on internal SharePoint IDs.

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  • DropDownList and SelectListItem Array Item Updates in MVC

    - by Rick Strahl
    So I ran into an interesting behavior today as I deployed my first MVC 4 app tonight. I have a list form that has a filter drop down that allows selection of categories. This list is static and rarely changes so rather than loading these items from the database each time I load the items once and then cache the actual SelectListItem[] array in a static property. However, when we put the site online tonight we immediately noticed that the drop down list was coming up with pre-set values that randomly changed. Didn't take me long to trace this back to the cached list of SelectListItem[]. Clearly the list was getting updated - apparently through the model binding process in the selection postback. To clarify the scenario here's the drop down list definition in the Razor View:@Html.DropDownListFor(mod => mod.QueryParameters.Category, Model.CategoryList, "All Categories") where Model.CategoryList gets set with:[HttpPost] [CompressContent] public ActionResult List(MessageListViewModel model) { InitializeViewModel(model); busEntry entryBus = new busEntry(); var entries = entryBus.GetEntryList(model.QueryParameters); model.Entries = entries; model.DisplayMode = ApplicationDisplayModes.Standard; model.CategoryList = AppUtils.GetCachedCategoryList(); return View(model); } The AppUtils.GetCachedCategoryList() method gets the cached list or loads the list on the first access. The code to load up the list is housed in a Web utility class. The method looks like this:/// <summary> /// Returns a static category list that is cached /// </summary> /// <returns></returns> public static SelectListItem[] GetCachedCategoryList() { if (_CategoryList != null) return _CategoryList; lock (_SyncLock) { if (_CategoryList != null) return _CategoryList; var catBus = new busCategory(); var categories = catBus.GetCategories().ToList(); // Turn list into a SelectItem list var catList= categories .Select(cat => new SelectListItem() { Text = cat.Name, Value = cat.Id.ToString() }) .ToList(); catList.Insert(0, new SelectListItem() { Value = ((int)SpecialCategories.AllCategoriesButRealEstate).ToString(), Text = "All Categories except Real Estate" }); catList.Insert(1, new SelectListItem() { Value = "-1", Text = "--------------------------------" }); _CategoryList = catList.ToArray(); } return _CategoryList; } private static SelectListItem[] _CategoryList ; This seemed normal enough to me - I've been doing stuff like this forever caching smallish lists in memory to avoid an extra trip to the database. This list is used in various places throughout the application - for the list display and also when adding new items and setting up for notifications etc.. Watch that ModelBinder! However, it turns out that this code is clearly causing a problem. It appears that the model binder on the [HttpPost] method is actually updating the list that's bound to and changing the actual entry item in the list and setting its selected value. If you look at the code above I'm not setting the SelectListItem.Selected value anywhere - the only place this value can get set is through ModelBinding. Sure enough when stepping through the code I see that when an item is selected the actual model - model.CategoryList[x].Selected - reflects that. This is bad on several levels: First it's obviously affecting the application behavior - nobody wants to see their drop down list values jump all over the place randomly. But it's also a problem because the array is getting updated by multiple ASP.NET threads which likely would lead to odd crashes from time to time. Not good! In retrospect the modelbinding behavior makes perfect sense. The actual items and the Selected property is the ModelBinder's way of keeping track of one or more selected values. So while I assumed the list to be read-only, the ModelBinder is actually updating it on a post back producing the rather surprising results. Totally missed this during testing and is another one of those little - "Did you know?" moments. So, is there a way around this? Yes but it's maybe not quite obvious. I can't change the behavior of the ModelBinder, but I can certainly change the way that the list is generated. Rather than returning the cached list, I can return a brand new cloned list from the cached items like this:/// <summary> /// Returns a static category list that is cached /// </summary> /// <returns></returns> public static SelectListItem[] GetCachedCategoryList() { if (_CategoryList != null) { // Have to create new instances via projection // to avoid ModelBinding updates to affect this // globally return _CategoryList .Select(cat => new SelectListItem() { Value = cat.Value, Text = cat.Text }) .ToArray(); } …}  The key is that newly created instances of SelectListItems are returned not just filtered instances of the original list. The key here is 'new instances' so that the ModelBinding updates do not update the actual static instance. The code above uses LINQ and a projection into new SelectListItem instances to create this array of fresh instances. And this code works correctly - no more cross-talk between users. Unfortunately this code is also less efficient - it has to reselect the items and uses extra memory for the new array. Knowing what I know now I probably would have not cached the list and just take the hit to read from the database. If there is even a possibility of thread clashes I'm very wary of creating code like this. But since the method already exists and handles this load in one place this fix was easy enough to put in. Live and learn. It's little things like this that can cause some interesting head scratchers sometimes…© Rick Strahl, West Wind Technologies, 2005-2012Posted in MVC  ASP.NET  .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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  • Test All Features of Windows Phone 7 On Your PC

    - by Matthew Guay
    Are you developer or just excited about the upcoming Windows Phone 7, and want to try it out now?  Thanks to free developer tools from Microsoft and a new unlocked emulator rom, you can try out most of the exciting features today from your PC. Last week we showed you how to try out Windows Phone 7 on your PC and get started developing for the upcoming new devices.  We noticed, however, that the emulator only contains Internet Explorer Mobile and some settings.  This is still interesting to play around with, but it wasn’t the full Windows Phone 7 experience. Some enterprising tweakers discovered that more applications were actually included in the emulator, but were simply hidden from users.  Developer Dan Ardelean then figured out how to re-enable these features, and released a tweaked emulator rom so everyone can try out all of the Windows Phone 7 features for themselves.  Here we’ll look at how you can run this new emulator image on your PC, and then look at some interesting features in Windows Phone 7. Editor Note: This modified emulator image is not official, and isn’t sanctioned by Microsoft. Use your own judgment when choosing to download and use the emulator. Setting Up Emulator Rom To test-drive Windows Phone 7 on your PC, you must first download and install the Windows Phone Developer Tools CTP (link below).  Follow the steps we showed you last week at: Try out Windows Phone 7 on your PC today.  Once it’s installed, go ahead and run the default emulator as we showed to make sure everything works ok. Once the Windows Phone Developer Tools are installed and running, download the new emulator rom from XDA Forums (link below).  This will be a zip file, so extract it first. Note where you save the file, as you will need the address in the next step. Now, to run our new emulator image, we need to open the emulator in command line and point to the new rom image.  To do this, browse to the correct directory, depending on whether you’re running the 32 bit or 64 bit version of Windows: 32 bit: C:\Program Files\Microsoft XDE\1.0\ 64 bit: C:\Program Files (x86)\Microsoft XDE\1.0\ Hold your Shift key down and right-click in the folder.  Choose Open Command Window here. At the command prompt, enter XDE.exe followed by the location of your new rom image.  Here, we downloaded the rom to our download folder, so at the command prompt we entered: XDE.exe C:\Users\Matthew\Downloads\WM70Full\WM70Full.bin The emulator loads … with the full Windows Phone 7 experience! To make it easier, let’s make a shortcut on our desktop to load the emulator with the new rom directly.  Right-click on your desktop (or any folder you want to create the shortcut in), select New, and then Shortcut. Now, in the box, we need to enter the path for the emulator followed by the location of our rom.  Both items must be in quotes.  So, in our test, we entered the following: 32 bit: “C:\Program Files\Microsoft XDE\1.0\” “C:\Users\Matthew\Downloads\WM70Full\WM70Full.bin” 64 bit: “C:\Program Files (x86)\Microsoft XDE\1.0\” “C:\Users\Matthew\Downloads\WM70Full\WM70Full.bin” Make sure to enter the correct location of the new emulator rom for your computer, and keep both items in separate quotes.  Click next when you’ve entered the location. Name the shortcut; we named it Windows Phone 7, but simply enter whatever you’d like.  Click Finish when you’re done. You should now have a nice Windows Phone icon and your fully functional shortcut!  Double-click it to run the Windows Phone 7 emulator as above. Features in the Unlocked Windows Phone 7 Emulator So let’s look at what you can do with this new emulator.  Almost everything you’ve seen in demos from the Mobile World Conference and Mix’10 are right here for you to play with.  Here’s the application menu, which you can access by clicking on the arrow on the top of the home screen, which shows how much stuff they’ve got in this!   And, of course, even the home screen itself shows much more activity than it did in the original emulator. Let’s check out some of these sections.  Here’s Zune running on Windows Phone 7, and the Zune Marketplace.  The animations are beautiful, so be sure to check this out yourself. The new picture hub is much nicer than any picture viewer included with Windows Mobile in the past…   Stay productive, and on schedule with the new Calendar. The XBOX hub gives us only a hint of things to come, and the links to games now are simply placeholders. Here’s a look at the Office hub.  This doesn’t show up on the homescreen right now, but you can access it in the applications menu.  Office obviously still has a lot of work left on it, but even at a glance here it looks like it includes a lot more functionality than Office Mobile in Windows Mobile 6. Here’s a look at each of the three apps: Word, Excel, and OneNote, and the formatting pallet in Office apps.   This emulator also includes a lot more settings than the default one, including settings for individual applications. You can even activate the screen lock, and try out the lift-to-peek-or-unlock feature… Finally, this version of Windows Phone 7 includes a very nice SystemInfo app with an advanced task manager.  We hope this is still available when the actual phones are released. Conclusion If you’re excited about the upcoming Windows Phone 7 series, or simply want to learn more about what’s coming, this is a great way to test it out.  With these exciting new hubs and applications, there’s something here for everyone.  Let us know what you like most about Windows Phone 7 and what your favorite app or hub is. Links Please note: These roms are not officially supported by Microsoft, and could be taken down. Download the unlocked Windows Phone 7 emulator from XDA Forums – click the link in this post to download How the unlocked emulator image was created Similar Articles Productive Geek Tips Try out Windows Phone 7 on your PC todayGet stats on your Ruby on Rails codeDisable Windows Vista’s Built-in CD/DVD Burning FeaturesWeek in Geek – The Slick Windows 7 File Copy Animation EditionGeek Fun: Virtualized Old School Windows – Windows 95 TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips Revo Uninstaller Pro Registry Mechanic 9 for Windows PC Tools Internet Security Suite 2010 PCmover Professional Get Better Windows Search With UltraSearch Scan News With NY Times Article Skimmer SpeedyFox Claims to Speed up your Firefox Beware Hover Kitties Test Drive Mobile Phones Online With TryPhone Ben & Jerry’s Free Cone Day, 3/23/10

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  • Oracle Data Mining a Star Schema: Telco Churn Case Study

    - by charlie.berger
    There is a complete and detailed Telco Churn case study "How to" Blog Series just posted by Ari Mozes, ODM Dev. Manager.  In it, Ari provides detailed guidance in how to leverage various strengths of Oracle Data Mining including the ability to: mine Star Schemas and join tables and views together to obtain a complete 360 degree view of a customer combine transactional data e.g. call record detail (CDR) data, etc. define complex data transformation, model build and model deploy analytical methodologies inside the Database  His blog is posted in a multi-part series.  Below are some opening excerpts for the first 3 blog entries.  This is an excellent resource for any novice to skilled data miner who wants to gain competitive advantage by mining their data inside the Oracle Database.  Many thanks Ari! Mining a Star Schema: Telco Churn Case Study (1 of 3) One of the strengths of Oracle Data Mining is the ability to mine star schemas with minimal effort.  Star schemas are commonly used in relational databases, and they often contain rich data with interesting patterns.  While dimension tables may contain interesting demographics, fact tables will often contain user behavior, such as phone usage or purchase patterns.  Both of these aspects - demographics and usage patterns - can provide insight into behavior.Churn is a critical problem in the telecommunications industry, and companies go to great lengths to reduce the churn of their customer base.  One case study1 describes a telecommunications scenario involving understanding, and identification of, churn, where the underlying data is present in a star schema.  That case study is a good example for demonstrating just how natural it is for Oracle Data Mining to analyze a star schema, so it will be used as the basis for this series of posts...... Mining a Star Schema: Telco Churn Case Study (2 of 3) This post will follow the transformation steps as described in the case study, but will use Oracle SQL as the means for preparing data.  Please see the previous post for background material, including links to the case study and to scripts that can be used to replicate the stages in these posts.1) Handling missing values for call data recordsThe CDR_T table records the number of phone minutes used by a customer per month and per call type (tariff).  For example, the table may contain one record corresponding to the number of peak (call type) minutes in January for a specific customer, and another record associated with international calls in March for the same customer.  This table is likely to be fairly dense (most type-month combinations for a given customer will be present) due to the coarse level of aggregation, but there may be some missing values.  Missing entries may occur for a number of reasons: the customer made no calls of a particular type in a particular month, the customer switched providers during the timeframe, or perhaps there is a data entry problem.  In the first situation, the correct interpretation of a missing entry would be to assume that the number of minutes for the type-month combination is zero.  In the other situations, it is not appropriate to assume zero, but rather derive some representative value to replace the missing entries.  The referenced case study takes the latter approach.  The data is segmented by customer and call type, and within a given customer-call type combination, an average number of minutes is computed and used as a replacement value.In SQL, we need to generate additional rows for the missing entries and populate those rows with appropriate values.  To generate the missing rows, Oracle's partition outer join feature is a perfect fit.  select cust_id, cdre.tariff, cdre.month, minsfrom cdr_t cdr partition by (cust_id) right outer join     (select distinct tariff, month from cdr_t) cdre     on (cdr.month = cdre.month and cdr.tariff = cdre.tariff);   ....... Mining a Star Schema: Telco Churn Case Study (3 of 3) Now that the "difficult" work is complete - preparing the data - we can move to building a predictive model to help identify and understand churn.The case study suggests that separate models be built for different customer segments (high, medium, low, and very low value customer groups).  To reduce the data to a single segment, a filter can be applied: create or replace view churn_data_high asselect * from churn_prep where value_band = 'HIGH'; It is simple to take a quick look at the predictive aspects of the data on a univariate basis.  While this does not capture the more complex multi-variate effects as would occur with the full-blown data mining algorithms, it can give a quick feel as to the predictive aspects of the data as well as validate the data preparation steps.  Oracle Data Mining includes a predictive analytics package which enables quick analysis. begin  dbms_predictive_analytics.explain(   'churn_data_high','churn_m6','expl_churn_tab'); end; /select * from expl_churn_tab where rank <= 5 order by rank; ATTRIBUTE_NAME       ATTRIBUTE_SUBNAME EXPLANATORY_VALUE RANK-------------------- ----------------- ----------------- ----------LOS_BAND                                      .069167052          1MINS_PER_TARIFF_MON  PEAK-5                   .034881648          2REV_PER_MON          REV-5                    .034527798          3DROPPED_CALLS                                 .028110322          4MINS_PER_TARIFF_MON  PEAK-4                   .024698149          5From the above results, it is clear that some predictors do contain information to help identify churn (explanatory value > 0).  The strongest uni-variate predictor of churn appears to be the customer's (binned) length of service.  The second strongest churn indicator appears to be the number of peak minutes used in the most recent month.  The subname column contains the interior piece of the DM_NESTED_NUMERICALS column described in the previous post.  By using the object relational approach, many related predictors are included within a single top-level column. .....   NOTE:  These are just EXCERPTS.  Click here to start reading the Oracle Data Mining a Star Schema: Telco Churn Case Study from the beginning.    

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