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  • WLS Console Timeout

    - by john.graves(at)oracle.com
    The WebLogic console timeout is a great feature for security, yet a horrible feature during development.  Logging in over and over again gets to be annoying.  This is very easy to change, but I would never do this on a production system!   Find the WebLogic consoleapp weblogic.xml file.  This is typically in your WL_HOME/server/lib/consoleapp/webapp/WEB-INF/ directory. Edit the weblogic.xml file: Update the section shown and increase the timeout-secs.  I just throw an extra zero at the end giving me ten full hours of fun!!!: <session-descriptor> <timeout-secs>36000</timeout-secs> <invalidation-interval-secs>60</invalidation-interval-secs> <cookie-name>ADMINCONSOLESESSION</cookie-name> <cookie-max-age-secs>-1</cookie-max-age-secs> <cookie-http-only>false</cookie-http-only> <url-rewriting-enabled>false</url-rewriting-enabled> </session-descriptor> .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; }

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  • Generic Pop and Push for List<T>

    - by Bil Simser
    Here's a little snippet I use to extend a generic List class to have similar capabilites to the Stack class. The Stack<T> class is great but it lives in its own world under System.Object. Wouldn't it be nice to have a List<T> that could do the same? Here's the code: .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; } 1: public static class ExtensionMethods 2: { 3: public static T Pop<T>(this List<T> theList) 4: { 5: var local = theList[theList.Count - 1]; 6: theList.RemoveAt(theList.Count - 1); 7: return local; 8: } 9:   10: public static void Push<T>(this List<T> theList, T item) 11: { 12: theList.Add(item); 13: } 14: } It's a simple extension but I've found it useful, hopefully you will too! Enjoy.

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  • JDBC Triggers

    - by Tim Dexter
    Received a question from a customer last week, they were using the new rollup patch on top of 10.1.3.4.1. What are these boxes for? Don't you know? Surely? Well, they are for ... that new functionality, you know it's in the user docs, that thingmabobby doodah. OK, I dont know either, I can have a guess but let me check first. Serveral IM sessions, emails and a dig through the readme for the new patch and I had my answer. Its not in the official documentation, yet. Leslie is on the case. The two fields were designed to allow an Admin to set a users context attributes before a connection is made to a database and for un-setting the attributes after the connection is broken by the extraction engine. We got a sample from the Enterprise Manager team on how they will be using it with their VPD connections. FUNCTION bip_to_em_user (user_name_in IN VARCHAR2) RETURN BOOLEAN IS BEGIN SETEMUSERCONTEXT(user_name_in, MGMT_USER.OP_SET_IDENTIFIER); return TRUE; END bip_to_em_user; And used in the jdbc data source definition like this (pre-process function): sysman.mgmt_bip.bip_to_em_user(:xdo_user_name) You, of course can call any function that is going to return a boolean value, another example might be. FUNCTION set_per_process_username (username_in IN VARCHAR2) RETURN BOOLEAN IS BEGIN SETUSERCONTEXT(username_in); return TRUE; END set_per_process_username Just use your own function/package to set some user context. Very grateful for the mail from Leslie on the EM team's usage but I had to try it out. Rather than set up a VPD, I opted for a simpler test. Can I log the comings and goings of users and their queries using the same pre-process text box. Reaching back into the depths of my developer brain to remember some pl/sql, it was not that deep and I came up with: CREATE OR REPLACE FUNCTION BIPTEST (user_name_in IN VARCHAR2, smode IN VARCHAR2) RETURN BOOLEAN AS BEGIN INSERT INTO LOGTAB VALUES(user_name_in, sysdate,smode); RETURN true; END BIPTEST; To call it in the pre-fetch trigger. BIPTEST(:xdo_user_name) Not going to set the pl/sql world alight I know, but you get the idea. As a new connection is made to the database its logged in the LOGTAB table. The SMODE value just sets if its an entry or an exit. I used the pre- and post- boxes. NAME UPDATE_DATE S_FLAG oracle 14-MAY-10 09.51.34.000000000 AM Start oracle 14-MAY-10 10.23.57.000000000 AM Finish administrator 14-MAY-10 09.51.38.000000000 AM Start administrator 14-MAY-10 09.51.38.000000000 AM Finish oracle 14-MAY-10 09.51.42.000000000 AM Start oracle 14-MAY-10 09.51.42.000000000 AM Finish It works very well, I had some fun trying to find a nasty query for the extraction engine so that the timestamps from in to out actually had a difference. That engine is fast! The only derived value you can pass from BIP is :xdo_user_name. None of the other server values are available. Connection pools are not currently supported but planned for a future release. Now you know what those fields are for and look for some official documentation, rather than my ramblings, coming soon!

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  • ASP.NET MVC 4: Short syntax for script and style bundling

    - by DigiMortal
    ASP.NET MVC 4 introduces new methods for style and scripts bundling. I found something brilliant there I want to introduce you. In this posting I will show you how easy it is to include whole folder with stylesheets or JavaScripts to your page. I’m using ASP.NET MVC 4 Internet Site template for this example. When we open layout pages located in shared views folder we can see something like this in layout file header: <link href="@System.Web.Optimization.BundleTable.Bundles.ResolveBundleUrl("~/Content/css")" rel="stylesheet" type="text/css" />    <link href="@System.Web.Optimization.BundleTable.Bundles.ResolveBundleUrl("~/Content/themes/base/css")" rel="stylesheet" type="text/css" />    <script src="@System.Web.Optimization.BundleTable.Bundles.ResolveBundleUrl("~/Scripts/js")"></script> Let’s take the last line and modify it so it looks like this: <script src="/Scripts/js"></script> After saving the layout page let’s run browser and see what is coming in over network. As you can see the request to folder ended up with result code 200 which means that request was successful. 327.2KB was received and it is not mark-up size for error page or directory index. Here is the body of response: I scrolled down to point where one script ends and another one starts when I made the screenshot above. All scripts delivered with ASP.NET MVC project templates start with this green note. So now we can be sure that the request to scripts folder ended up with bundled script and not with something else. Conclusion Script and styles bundling uses currently by default long syntax where bundling is done through Bundling class. We can still avoid those long lines and use extremely short syntax for script and styles bundling – we just write usual script or link tag and give folder URL as source. ASP.NET MVC 4 is smart enough to combine styles or scripts when request like this comes in.

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  • How to tell if SPARC T4 crypto is being used?

    - by danx
    A question that often comes up when running applications on SPARC T4 systems is "How can I tell if hardware crypto accleration is being used?" To review, the SPARC T4 processor includes a crypto unit that supports several crypto instructions. For hardware crypto these include 11 AES instructions, 4 xmul* instructions (for AES GCM carryless multiply), mont for Montgomery multiply (optimizes RSA and DSA), and 5 des_* instructions (for DES3). For hardware hash algorithm optimization, the T4 has the md5, sha1, sha256, and sha512 instructions (the last two are used for SHA-224 an SHA-384). First off, it's easy to tell if the processor T4 crypto instructions—use the isainfo -v command and look for "sparcv9" and "aes" (and other hash and crypto algorithms) in the output: $ isainfo -v 64-bit sparcv9 applications crc32c cbcond pause mont mpmul sha512 sha256 sha1 md5 camellia kasumi des aes ima hpc vis3 fmaf asi_blk_init vis2 vis popc These instructions are not-privileged, so are available for direct use in user-level applications and libraries (such as OpenSSL). Here is the "openssl speed -evp" command shown with the built-in t4 engine and with the pkcs11 engine. Both run the T4 AES instructions, but the t4 engine is faster than the pkcs11 engine because it has less overhead (especially for smaller packet sizes): t-4 $ /usr/bin/openssl version OpenSSL 1.0.0j 10 May 2012 t-4 $ /usr/bin/openssl engine (t4) SPARC T4 engine support (dynamic) Dynamic engine loading support (pkcs11) PKCS #11 engine support t-4 $ /usr/bin/openssl speed -evp aes-128-cbc # t4 engine used by default . . . The 'numbers' are in 1000s of bytes per second processed. type 16 bytes 64 bytes 256 bytes 1024 bytes 8192 bytes aes-128-cbc 487777.10k 816822.21k 986012.59k 1017029.97k 1053543.08k t-4 $ /usr/bin/openssl speed -engine pkcs11 -evp aes-128-cbc engine "pkcs11" set. . . . The 'numbers' are in 1000s of bytes per second processed. type 16 bytes 64 bytes 256 bytes 1024 bytes 8192 bytes aes-128-cbc 31703.58k 116636.39k 350672.81k 696170.50k 993599.49k Note: The "-evp" flag indicates use the OpenSSL "EnVeloPe" API, which gives more accurate results. That's because it tells OpenSSL to use the same API that external programs use when calling OpenSSL libcrypto functions, evp(3openssl). DTrace Shows if T4 Crypto Functions Are Used OK, good enough, the isainfo(1) command shows the instructions are present, but how does one know if they are being used? Chi-Chang Lin, who works on Oracle Solaris performance, wrote a Dtrace script to show if T4 instructions are being executed. To show the T4 instructions are being used, run the following Dtrace script. Look for functions named "t4" and "yf" in the output. The OpenSSL T4 engine uses functions named "t4" and the PKCS#11 engine uses functions named "yf". To demonstrate, I'll first run "openssl speed" with the built-in t4 engine then with the pkcs11 engine. The performance numbers are not valid due to dtrace probes slowing things down. t-4 # dtrace -Z -n ' pid$target::*yf*:entry,pid$target::*t4_*:entry{ @[probemod, probefunc] = count();}' \ -c "/usr/bin/openssl speed -evp aes-128-cbc" dtrace: description 'pid$target::*yf*:entry' matched 101 probes . . . dtrace: pid 2029 has exited libcrypto.so.1.0.0 ENGINE_load_t4 1 libcrypto.so.1.0.0 t4_DH 1 libcrypto.so.1.0.0 t4_DSA 1 libcrypto.so.1.0.0 t4_RSA 1 libcrypto.so.1.0.0 t4_destroy 1 libcrypto.so.1.0.0 t4_free_aes_ctr_NIDs 1 libcrypto.so.1.0.0 t4_init 1 libcrypto.so.1.0.0 t4_add_NID 3 libcrypto.so.1.0.0 t4_aes_expand128 5 libcrypto.so.1.0.0 t4_cipher_init_aes 5 libcrypto.so.1.0.0 t4_get_all_ciphers 6 libcrypto.so.1.0.0 t4_get_all_digests 59 libcrypto.so.1.0.0 t4_digest_final_sha1 65 libcrypto.so.1.0.0 t4_digest_init_sha1 65 libcrypto.so.1.0.0 t4_sha1_multiblock 126 libcrypto.so.1.0.0 t4_digest_update_sha1 261 libcrypto.so.1.0.0 t4_aes128_cbc_encrypt 1432979 libcrypto.so.1.0.0 t4_aes128_load_keys_for_encrypt 1432979 libcrypto.so.1.0.0 t4_cipher_do_aes_128_cbc 1432979 t-4 # dtrace -Z -n 'pid$target::*yf*:entry{ @[probemod, probefunc] = count();}   pid$target::*yf*:entry,pid$target::*t4_*:entry{ @[probemod, probefunc] = count();}' \ -c "/usr/bin/openssl speed -engine pkcs11 -evp aes-128-cbc" dtrace: description 'pid$target::*yf*:entry' matched 101 probes engine "pkcs11" set. . . . dtrace: pid 2033 has exited libcrypto.so.1.0.0 ENGINE_load_t4 1 libcrypto.so.1.0.0 t4_DH 1 libcrypto.so.1.0.0 t4_DSA 1 libcrypto.so.1.0.0 t4_RSA 1 libcrypto.so.1.0.0 t4_destroy 1 libcrypto.so.1.0.0 t4_free_aes_ctr_NIDs 1 libcrypto.so.1.0.0 t4_get_all_ciphers 1 libcrypto.so.1.0.0 t4_get_all_digests 1 libsoftcrypto.so.1 rijndael_key_setup_enc_yf 1 libsoftcrypto.so.1 yf_aes_expand128 1 libcrypto.so.1.0.0 t4_add_NID 3 libsoftcrypto.so.1 yf_aes128_cbc_encrypt 1542330 libsoftcrypto.so.1 yf_aes128_load_keys_for_encrypt 1542330 So, as shown above the OpenSSL built-in t4 engine executes t4_* functions (which are hand-coded assembly executing the T4 AES instructions) and the OpenSSL pkcs11 engine executes *yf* functions. Programmatic Use of OpenSSL T4 engine The OpenSSL t4 engine is used automatically with the /usr/bin/openssl command line. Chi-Chang Lin also points out that if you're calling the OpenSSL API (libcrypto.so) from a program, you must call ENGINE_load_built_engines(), otherwise the built-in t4 engine will not be loaded. You do not call ENGINE_set_default(). That's because "openssl speed -evp" test calls ENGINE_load_built_engines() even though the "-engine" option wasn't specified. OpenSSL T4 engine Availability The OpenSSL t4 engine is available with Solaris 11 and 11.1. For Solaris 10 08/11 (U10), you need to use the OpenSSL pkcs311 engine. The OpenSSL t4 engine is distributed only with the version of OpenSSL distributed with Solaris (and not third-party or self-compiled versions of OpenSSL). The OpenSSL engine implements the AES cipher for Solaris 11, released 11/2011. For Solaris 11.1, released 11/2012, the OpenSSL engine adds optimization for the MD5, SHA-1, and SHA-2 hash algorithms, and DES-3. Although the T4 processor has Camillia and Kasumi block cipher instructions, these are not implemented in the OpenSSL T4 engine. The following charts may help view availability of optimizations. The first chart shows what's available with Solaris CLIs and APIs, the second chart shows what's available in Solaris OpenSSL. Native Solaris Optimization for SPARC T4 This table is shows Solaris native CLI and API support. As such, they are all available with the OpenSSL pkcs11 engine. CLIs: "openssl -engine pkcs11", encrypt(1), decrypt(1), mac(1), digest(1), MD5sum(1), SHA1sum(1), SHA224sum(1), SHA256sum(1), SHA384sum(1), SHA512sum(1) APIs: PKCS#11 library libpkcs11(3LIB) (incluDES Openssl pkcs11 engine), libMD(3LIB), and Solaris kernel modules AlgorithmSolaris 1008/11 (U10)Solaris 11Solaris 11.1 AES-ECB, AES-CBC, AES-CTR, AES-CBC AES-CFB128 XXX DES3-ECB, DES3-CBC, DES2-ECB, DES2-CBC, DES-ECB, DES-CBC XXX bignum Montgomery multiply (RSA, DSA) XXX MD5, SHA-1, SHA-256, SHA-384, SHA-512 XXX SHA-224 X ARCFOUR (RC4) X Solaris OpenSSL T4 Engine Optimization This table is for the Solaris OpenSSL built-in t4 engine. Algorithms listed above are also available through the OpenSSL pkcs11 engine. CLI: openssl(1openssl) APIs: openssl(5), engine(3openssl), evp(3openssl), libcrypto crypto(3openssl) AlgorithmSolaris 11Solaris 11SRU2Solaris 11.1 AES-ECB, AES-CBC, AES-CTR, AES-CBC AES-CFB128 XXX DES3-ECB, DES3-CBC, DES-ECB, DES-CBC X bignum Montgomery multiply (RSA, DSA) X MD5, SHA-1, SHA-256, SHA-384, SHA-512 XX SHA-224 X Source Code Availability Solaris Most of the T4 assembly code that called the new T4 crypto instructions was written by Ferenc Rákóczi of the Solaris Security group, with assistance from others. You can download the Solaris source for this and other parts of Solaris as a few zip files at the Oracle Download website. The relevant source files are generally under directories usr/src/common/crypto/{aes,arcfour,des,md5,modes,sha1,sha2}}/sun4v/. and usr/src/common/bignum/sun4v/. Solaris 11 binary is available from the Oracle Solaris 11 download website. OpenSSL t4 engine The source for the OpenSSL t4 engine, which is based on the Solaris source above, is viewable through the OpenGrok source code browser in directory src/components/openssl/openssl-1.0.0/engines/t4 . You can download the source from the same website or through Mercurial source code management, hg(1). Conclusion Oracle Solaris with SPARC T4 provides a rich set of accelerated cryptographic and hash algorithms. Using the latest update, Solaris 11.1, provides the best set of optimized algorithms, but alternatives are often available, sometimes slightly slower, for releases back to Solaris 10 08/11 (U10). Reference See also these earlier blogs. SPARC T4 OpenSSL Engine by myself, Dan Anderson (2011), discusses the Openssl T4 engine and reviews the SPARC T4 processor for the Solaris 11 release. Exciting Crypto Advances with the T4 processor and Oracle Solaris 11 by Valerie Fenwick (2011) discusses crypto algorithms that were optimized for the T4 processor with the Solaris 11 FCS (11/11) and Solaris 10 08/11 (U10) release. T4 Crypto Cheat Sheet by Stefan Hinker (2012) discusses how to make T4 crypto optimization available to various consumers (such as SSH, Java, OpenSSL, Apache, etc.) High Performance Security For Oracle Database and Fusion Middleware Applications using SPARC T4 (PDF, 2012) discusses SPARC T4 and its usage to optimize application security. Configuring Oracle iPlanet WebServer / Oracle Traffic Director to use crypto accelerators on T4-1 servers by Meena Vyas (2012)

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  • A faulty Caviar Blue hard drive?

    - by Glister
    We have a small "homemade" server running fully updated Debian Wheezy (amd64). One hard drive installed: WDC WD6400AAKS. The motherboard is ASUS M4N68T V2. The usual load: CPU: an average of 20% Each week about 50GB of additional space is occupied. About 47GB of uploaded files and 3GB of MySQL data. I'm afraid that the hard drive may be about to fail. I saw Pre-fail on few places when I ran: root@SERVER:/tmp# smartctl -a /dev/sda smartctl 5.41 2011-06-09 r3365 [x86_64-linux-3.2.0-4-amd64] (local build) Copyright (C) 2002-11 by Bruce Allen, http://smartmontools.sourceforge.net === START OF INFORMATION SECTION === Model Family: Western Digital Caviar Blue Serial ATA Device Model: WDC WD6400AAKS-XXXXXXX Serial Number: WD-XXXXXXXXXXXXXXXXXXX LU WWN Device Id: 5 0014ee XXXXXXXXXXXXX Firmware Version: 01.03B01 User Capacity: 640,135,028,736 bytes [640 GB] Sector Size: 512 bytes logical/physical Device is: In smartctl database [for details use: -P show] ATA Version is: 8 ATA Standard is: Exact ATA specification draft version not indicated Local Time is: Mon Oct 28 18:55:27 2013 UTC SMART support is: Available - device has SMART capability. SMART support is: Enabled === START OF READ SMART DATA SECTION === SMART overall-health self-assessment test result: PASSED General SMART Values: Offline data collection status: (0x85) Offline data collection activity was aborted by an interrupting command from host. Auto Offline Data Collection: Enabled. Self-test execution status: ( 247) Self-test routine in progress... 70% of test remaining. Total time to complete Offline data collection: (11580) seconds. Offline data collection capabilities: (0x7b) SMART execute Offline immediate. Auto Offline data collection on/off support. Suspend Offline collection upon new command. Offline surface scan supported. Self-test supported. Conveyance Self-test supported. Selective Self-test supported. SMART capabilities: (0x0003) Saves SMART data before entering power-saving mode. Supports SMART auto save timer. Error logging capability: (0x01) Error logging supported. General Purpose Logging supported. Short self-test routine recommended polling time: ( 2) minutes. Extended self-test routine recommended polling time: ( 136) minutes. Conveyance self-test routine recommended polling time: ( 5) minutes. SCT capabilities: (0x303f) SCT Status supported. SCT Error Recovery Control supported. SCT Feature Control supported. SCT Data Table supported. SMART Attributes Data Structure revision number: 16 Vendor Specific SMART Attributes with Thresholds: ID# ATTRIBUTE_NAME FLAG VALUE WORST THRESH TYPE UPDATED WHEN_FAILED RAW_VALUE 1 Raw_Read_Error_Rate 0x002f 200 200 051 Pre-fail Always - 0 3 Spin_Up_Time 0x0027 157 146 021 Pre-fail Always - 5108 4 Start_Stop_Count 0x0032 098 098 000 Old_age Always - 2968 5 Reallocated_Sector_Ct 0x0033 200 200 140 Pre-fail Always - 0 7 Seek_Error_Rate 0x002e 200 200 051 Old_age Always - 0 9 Power_On_Hours 0x0032 079 079 000 Old_age Always - 15445 10 Spin_Retry_Count 0x0032 100 100 051 Old_age Always - 0 11 Calibration_Retry_Count 0x0032 100 100 051 Old_age Always - 0 12 Power_Cycle_Count 0x0032 098 098 000 Old_age Always - 2950 192 Power-Off_Retract_Count 0x0032 200 200 000 Old_age Always - 426 193 Load_Cycle_Count 0x0032 200 200 000 Old_age Always - 2968 194 Temperature_Celsius 0x0022 111 095 000 Old_age Always - 36 196 Reallocated_Event_Count 0x0032 200 200 000 Old_age Always - 0 197 Current_Pending_Sector 0x0032 200 200 000 Old_age Always - 0 198 Offline_Uncorrectable 0x0030 200 200 000 Old_age Offline - 0 199 UDMA_CRC_Error_Count 0x0032 200 160 000 Old_age Always - 21716 200 Multi_Zone_Error_Rate 0x0008 200 200 051 Old_age Offline - 0 SMART Error Log Version: 1 No Errors Logged SMART Self-test log structure revision number 1 Num Test_Description Status Remaining LifeTime(hours) LBA_of_first_error # 1 Short offline Completed without error 00% 15444 - Error SMART Read Selective Self-Test Log failed: scsi error aborted command Smartctl: SMART Selective Self Test Log Read Failed root@SERVER:/tmp# In one tutorial I read that the pre-fail is a an indication of coming failure, in another tutorial I read that it is not true. Can you guys help me decode the output of smartctl? It would be also nice to share suggestions what should I do if I want to ensure data integrity (about 50GB of new data each week, up to 2TB for the whole period I'm interested in). Maybe I will go with 2x2TB Caviar Black in RAID4?

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  • Awesome new feature for HCC

    - by Steve Tunstall
    I've talked about HCC (Hybrid Columnar Compression) before. This is Oracle's built-in compression feature, free of charge in 11Gr2, that allows a CRAZY amount of compression on historical data inside an Oracle database. It only works if the database is being stored in a ZFSSA, Exadata or Axiom. You can read all about it in this whitepaper, which shows the huge value of HCC when used with the ZFSSA. http://www.oracle.com/technetwork/articles/servers-storage-admin/perf-hybrid-columnar-compression-1689701.html Now, even better, Oracle has announced  a great new feature in Oracle 12c called "Automatic Data Optimization". This allows one to setup HCC to AUTOMATICALLY compress data AS IT AGES.  So this is now ILM all built into the Oracle database. It's free for crying out loud. It just needs to be sitting on Oracle storage, such as the ZFSSA, Exadata or Axiom.  Read about ADO here: http://www.oracle.com/technetwork/database/automatic-data-optimization-wp-12c-1896120.pdf?ssSourceSiteId=ocomen

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  • When there's no TCO, when to worry about blowing the stack?

    - by Cedric Martin
    Every single time there's a discussion about a new programming language targetting the JVM, there are inevitably people saying things like: "The JVM doesn't support tail-call optimization, so I predict lots of exploding stacks" There are thousands of variations on that theme. Now I know that some language, like Clojure for example, have a special recur construct that you can use. What I don't understand is: how serious is the lack of tail-call optimization? When should I worry about it? My main source of confusion probably comes from the fact that Java is one of the most succesful languages ever and quite a few of the JVM languages seems to be doing fairly well. How is that possible if the lack of TCO is really of any concern?

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  • How can calculus and linear algebra be useful to a system programmer?

    - by Victor
    I found a website saying that calculus and linear algebra are necessary for System Programming. System Programming, as far as I know, is about osdev, drivers, utilities and so on. I just can't figure out how calculus and linear algebra can be helpful on that. I know that calculus has several applications in science, but in this particular field of programming I just can't imagine how calculus can be so important. The information was on this site: http://www.wikihow.com/Become-a-Programmer Edit: Some answers here are explaining about algorithm complexity and optimization. When I made this question I was trying to be more specific about the area of System's Programming. Algorithm complexity and optimization can be applied to any area of programming not just System's Programming. That may be why I wasn't able to came up with such thinking at the time of the question.

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  • SH404SEF URLs in Joomla 1.5

    - by Tao Bellamine
    I have two modules to play with urls, the global configuration module and the sh404sef module. The global config is set to "Sef urls: YES" and "mod rewrite enabled: YES" and the sh404sef is set "url optimization: NO". My problem is, even with "Sef urls" set in the global config, my urls still don't seem to be that "user friendly" so I turn on the "Url optimization" using the sh404sef module, and I get better descriptive urls. However, the problem I inherit from doing this is that my dynamically populated chronoforms get messed up (only the chrono forms, other forms are fine); These forms are now showing up at the homepage instead of their own reserved page. Here's an example: Old form "GOOD" url: http://www.mycraftwork.com/index.php?option=com_content&view=article&id=94 New optimized "BAD" URL: http://www.mycraftwork.com/handthrown-pottery/alladin-teapot/index.php?option=com_content&view=article&id=94 Any help would be GREATLY appreciated! I can even turn the sh404sef on and off if some people are interested in seeing the issue LIVE. Thanks!! Tao Bellamine

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  • How to define template directives (from an API perspective)?

    - by Ralph
    Preface I'm writing a template language (don't bother trying to talk me out of it), and in it, there are two kinds of user-extensible nodes. TemplateTags and TemplateDirectives. A TemplateTag closely relates to an HTML tag -- it might look something like div(class="green") { "content" } And it'll be rendered as <div class="green">content</div> i.e., it takes a bunch of attributes, plus some content, and spits out some HTML. TemplateDirectives are a little more complicated. They can be things like for loops, ifs, includes, and other such things. They look a lot like a TemplateTag, but they need to be processed differently. For example, @for($i in $items) { div(class="green") { $i } } Would loop over $items and output the content with the variable $i substituted in each time. So.... I'm trying to decide on a way to define these directives now. Template Tags The TemplateTags are pretty easy to write. They look something like this: [TemplateTag] static string div(string content = null, object attrs = null) { return HtmlTag("div", content, attrs); } Where content gets the stuff between the curly braces (pre-rendered if there are variables in it and such), and attrs is either a Dictionary<string,object> of attributes, or an anonymous type used like a dictionary. It just returns the HTML which gets plunked into its place. Simple! You can write tags in basically 1 line. Template Directives The way I've defined them now looks like this: [TemplateDirective] static string @for(string @params, string content) { var tokens = Regex.Split(@params, @"\sin\s").Select(s => s.Trim()).ToArray(); string itemName = tokens[0].Substring(1); string enumName = tokens[1].Substring(1); var enumerable = data[enumName] as IEnumerable; var sb = new StringBuilder(); var template = new Template(content); foreach (var item in enumerable) { var templateVars = new Dictionary<string, object>(data) { { itemName, item } }; sb.Append(template.Render(templateVars)); } return sb.ToString(); } (Working example). Basically, the stuff between the ( and ) is not split into arguments automatically (like the template tags do), and the content isn't pre-rendered either. The reason it isn't pre-rendered is because you might want to add or remove some template variables or something first. In this case, we add the $i variable to the template variables, var templateVars = new Dictionary<string, object>(data) { { itemName, item } }; And then render the content manually, sb.Append(template.Render(templateVars)); Question I'm wondering if this is the best approach to defining custom Template Directives. I want to make it as easy as possible. What if the user doesn't know how to render templates, or doesn't know that he's supposed to? Maybe I should pass in a Template instance pre-filled with the content instead? Or maybe only let him tamper w/ the template variables, and then automatically render the content at the end? OTOH, for things like "if" if the condition fails, then the template wouldn't need to be rendered at all. So there's a lot of flexibility I need to allow in here. Thoughts?

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  • How to configure Google Analytics experiments manually

    - by John
    I wish to run multivariate tests on an e-commerce site that run across all product pages. I will be setting and deciding the variations myself all I need to do is track the results in GA. I think may be possible (although only A/B testing is available via the GA UI): https://developers.google.com/analytics/devguides/platform/features/experiments#serving-framework EXTERNAL – You will choose variations, handle experiment optimization, and only report the chosen variation to Google Analytics. For example, this should be used by 3rd-party optimization platforms that want to integrate with Google Analytics for reporting purposes. In this case, the Google Analytics statistical engine will not run. However how do I configure this and push the data to GA in my page?

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  • Tips to Keep in Mind While Choosing an SEO Company

    If you own a website and want to have the serious profit with the help of that website then you have to find some of the ethical means by which the website can be promoted in the market and more crowds can come on your site. For this you can take advice from the people who are already into this business and can share some ideas with them. Nowadays the most common technique which is being used in the market is the SEO also known as Search Engine Optimization. There are many people on the web world who are familiar with this term but don't have a full idea. For such people there are many Search Engine Optimization Companies which are assisting the people.

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  • What does the SEO market look like? [closed]

    - by TheEconomist
    I'm an economist (aspiring economist, if we are being technical) and my curiousity has been recently piqued by search engine optimization services. I had the following questions. 1) What industries most widely use search engine optimization services? 2) Is it small business or big firms that use SEO services typically? 3) What is SEO pricing typically dependent upon and how much is it on average? 4) Do SEO services really increase traffic? Is there a dataset I can get a hold of for this sort of thing? I am not looking for answers to the questions necessarily. Although answers would help, a nudge in the right direction is more than sufficient, and greatly appreciated. Thank you!

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  • drupal - override form action?

    - by n00b0101
    I originally started this question in another thread, but that thread was sorta, kinda answered, and now I primarily want to know how to specify another form action... I tried using the code below, but the form action, when output, remains unchanged, although looking at the print_r($form), it's correctly changed... Why isn't it picking up? function mytheme_user_profile_form($form) { global $user; $uid = $user->uid; //print '<pre>'; print_r($form); print '</pre>'; $category = $form['_category']['#value']; switch($category) { case 'account': $form['#action'] = '/user/'.$uid.'/edit?destination=user/'.$uid; break; case 'education': $form['#action'] = '/user/'.$uid.'/edit/education?destination=user/'.$uid; break; case 'experience': $form['#action'] = '/user/'.$uid.'/edit/experience?destination=user/'.$uid; break; case 'publications': $form['#action'] = '/user/'.$uid.'/edit/publications?destination=user/'.$uid; break; case 'conflicts': $form['#action'] = '/user/'.$uid.'/edit/conflicts?destination=user/'.$uid; break; } //print '<pre>'; print_r($form); print '</pre>'; //print $form['#action']; $output .= drupal_render($form); return $output;

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  • Determine between files and folders using cURL

    - by ILMV
    I'm writing a script to download files from an FTP server using cURL + PHP, at the moment I am just trying to build a complete file structure, here's the code I'm using so far: <?php $curl = curl_init(); curl_setopt($curl, CURLOPT_URL, "ftp://www.example.com"); curl_setopt($curl, CURLOPT_USERPWD, "user:pwd"); curl_setopt ($curl, CURLOPT_RETURNTRANSFER, 1) ; curl_setopt($curl, CURLOPT_CUSTOMREQUEST, 'NLST'); // or curl_setopt($curl, CURLOPT_CUSTOMREQUEST, 'LIST -a'); $ftp=curl_exec($curl); $directory=split("[\n|\r]",$ftp); echo("<pre>".print_r($directory,true)."</pre>"); foreach($directory as $key=>$value) if($value=='') unset($directory[$key]); echo("<pre>".print_r($directory,true)."</pre>"); curl_close ($curl); ?> I can use either NLST or the LIST function, but what I want to do is programatically determine what are files and what are folders. Thanks!

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  • How to Manage project in this scenario

    - by vijay.shad
    Hi All, I am working on a web application which has got good amount of static or pre-login pages. These pages can have some simple forms as well where we would like to capture the visitor's details. Post login, I have got my main application. I am confused about the development and deployment architecture of my application. Post login part of my application has a release cycle of 1-2 months while pre-login pages are to be updated on a weekly basis. It is difficult to make a release of pre-login pages as the overall war also contains post-login application & which sometimes is not release ready. Currently, I have got both these parts bundled in the single war project. Please help me by letting me know the best practices whereby I can achieve following: Manage the releases of these two parts independently. I am using Maven. So is there a way I can share the resources, such as CSS, images etc between these two parts. Header and footer of my application is going to be same on pre-login & post-login pages. I was thinking of deploying these apps as two war files in my tomcat container. But then how will I manage the common resources like Css, images etc. Rgds Vijay

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  • Iframe form not submittin in IE but working in Firefox

    - by Younes
    I have got a form that posts values to a page in a wizard. When i'm loading this form in a Iframe everything is working fine in Firefox, it will get me to the second step of the wizard and maintains the values i filled in. When im testing this in Internet Explorer i am not getting to the second step, instead of that it returns me to the first step of the wizard with all fields being blank. When i check this in Fiddler i see that im getting a different response when i'm posting the form in the Iframe from Firefox compared to Internet Explorer. How can i make this work for all browsers? What am I doing wrong? This is what i get back from Fiddler: Firefox Post: Ressult Protocol Host URL Body Caching Content-Type Process Comments Custom 1 302 HTTP www.dmg.eu /brugman/budgetplanner/aanmelden.php 0 no-store, no-cache, must-revalidate, post-check=0, pre-check=0 Expires: Thu, 19 Nov 1981 08:52:00 GMT text/html; charset=UTF-8 firefox:6116 Get: # Result Protocol Host URL Body Caching Content-Type Process Comments Custom 2 200 HTTP www.dmg.eu /brugman/budgetplanner/ 40.677 no-store, no-cache, must-revalidate, post-check=0, pre-check=0 Expires: Thu, 19 Nov 1981 08:52:00 GMT text/html; charset=UTF-8 firefox:6116 Internet Explorer Post: Result Protocol Host URL Body Caching Content-Type Process Comments Custom 73 302 HTTP www.dmg.eu /brugman/budgetplanner/aanmelden.php 0 no-store, no-cache, must-revalidate, post-check=0, pre-check=0 Expires: Thu, 19 Nov 1981 08:52:00 GMT text/html; charset=UTF-8 iexplore:536 Get: Result Protocol Host URL Body Caching Content-Type Process Comments Custom 74 302 HTTP www.dmg.eu /brugman/budgetplanner/ 0 no-store, no-cache, must-revalidate, post-check=0, pre-check=0 Expires: Thu, 19 Nov 1981 08:52:00 GMT text/html; charset=UTF-8 iexplore:536 Hope someone knows what the diff is :).

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  • How to mix Grammar (Rules) & Dictation (Free speech) with SpeechRecognizer in C#

    - by Lee Englestone
    I really like Microsofts latest speech recognition (and SpeechSynthesis) offerings. http://msdn.microsoft.com/en-us/library/ms554855.aspx http://estellasays.blogspot.com/2009/04/speech-recognition-in-cnet.html However I feel like I'm somewhat limited when using grammars. Don't get me wrong grammars are great for telling the speech recognition exactly what words / phrases to look out for, however what if I want it to recognise something i've not given it a heads up about? Or I want to parse a phrase which is half pre-determined command name and half random words? For example.. Scenario A - I say "Google [Oil Spill]" and I want it to open Google with search results for the term in brackets which could be anything. Scenario B - I say "Locate [Manchester]" and I want it to search for Manchester in Google Maps or anything else non pre-determined I want it to know that 'Google' and 'Locate' are commands and what comes after it are parameters (and could be anything). Question : Does anyone know how to mix the use of pre-determined grammars (words the speech recognition should recognise) and words not in its pre-determined grammar? Code fragments.. using System.Speech.Recognition; ... ... SpeechRecognizer rec = new SpeechRecognizer(); rec.SpeechRecognized += rec_SpeechRecognized; var c = new Choices(); c.Add("search"); var gb = new GrammarBuilder(c); var g = new Grammar(gb); rec.LoadGrammar(g); rec.Enabled = true; ... ... void rec_SpeechRecognized(object sender, SpeechRecognizedEventArgs e) { if (e.Result.Text == "search") { string query = "How can I get a word not defined in Grammar recognised and passed into here!"; launchGoogle(query); } } ... ... private void launchGoogle(string term) { Process.Start("IEXPLORE", "google.com?q=" + term); }

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