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  • MySQL and Hadoop Integration - Unlocking New Insight

    - by Mat Keep
    “Big Data” offers the potential for organizations to revolutionize their operations. With the volume of business data doubling every 1.2 years, analysts and business users are discovering very real benefits when integrating and analyzing data from multiple sources, enabling deeper insight into their customers, partners, and business processes. As the world’s most popular open source database, and the most deployed database in the web and cloud, MySQL is a key component of many big data platforms, with Hadoop vendors estimating 80% of deployments are integrated with MySQL. The new Guide to MySQL and Hadoop presents the tools enabling integration between the two data platforms, supporting the data lifecycle from acquisition and organisation to analysis and visualisation / decision, as shown in the figure below The Guide details each of these stages and the technologies supporting them: Acquire: Through new NoSQL APIs, MySQL is able to ingest high volume, high velocity data, without sacrificing ACID guarantees, thereby ensuring data quality. Real-time analytics can also be run against newly acquired data, enabling immediate business insight, before data is loaded into Hadoop. In addition, sensitive data can be pre-processed, for example healthcare or financial services records can be anonymized, before transfer to Hadoop. Organize: Data is transferred from MySQL tables to Hadoop using Apache Sqoop. With the MySQL Binlog (Binary Log) API, users can also invoke real-time change data capture processes to stream updates to HDFS. Analyze: Multi-structured data ingested from multiple sources is consolidated and processed within the Hadoop platform. Decide: The results of the analysis are loaded back to MySQL via Apache Sqoop where they inform real-time operational processes or provide source data for BI analytics tools. So how are companies taking advantage of this today? As an example, on-line retailers can use big data from their web properties to better understand site visitors’ activities, such as paths through the site, pages viewed, and comments posted. This knowledge can be combined with user profiles and purchasing history to gain a better understanding of customers, and the delivery of highly targeted offers. Of course, it is not just in the web that big data can make a difference. Every business activity can benefit, with other common use cases including: - Sentiment analysis; - Marketing campaign analysis; - Customer churn modeling; - Fraud detection; - Research and Development; - Risk Modeling; - And more. As the guide discusses, Big Data is promising a significant transformation of the way organizations leverage data to run their businesses. MySQL can be seamlessly integrated within a Big Data lifecycle, enabling the unification of multi-structured data into common data platforms, taking advantage of all new data sources and yielding more insight than was ever previously imaginable. Download the guide to MySQL and Hadoop integration to learn more. I'd also be interested in hearing about how you are integrating MySQL with Hadoop today, and your requirements for the future, so please use the comments on this blog to share your insights.

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  • IIS FTP 7.5 Data Channel Problem (SSL)

    - by user59050
    Hey there I wonder if anyone can get me in the right direction. I am setting up both a FTPS Client and Server, FTPS Server using Microsoft’s iis FTP 7.5. On the client side it will be running on Linux and I am using M2crypto for the openssl wrapping (python). I am worried the problem is on the server side (iis7.5) due to the following discovery : If I host using Filezilla with BOTH the control and data channel being forced to be encrypted it works 100% (100% file transmission), if i use iis as the server everything works up to the point when the data channel takes over... i.e. all data of the retrieved file is already received correctly in my basket! The ftp server just won't send the final '226 Transfer complete.' on the cmd socket. Why? If i force the client or server to close the connection the file is 100% intact....If i use iis 7.5 with forced encryption on control channel all works 100% as long as i don’t force data channel... Here are some screenshots to demo this... Client View after Kill Client : pics @ http://forums.iis.net/p/1172936/1960994.aspx#1960994 Summary : We can establish the connection, do directory listings, start the upload, see the file (0bytes) created on the server but then the client hangs. If we terminate the client, the uploaded file on the server suddenly jumps up to full size.

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  • Fast distributed filesystem for a large amounts of data with metadata in database

    - by undefined hero
    My project uses several processing machines and one storage machine. Currently storage organized with a MSSQL filetable shared folder. Every file in storage have some metadata in database. Processing machines executes tasks for which they needed files from storage and their metadata. After completing task, processing machine puts resulting data back in storage. From there its taken by another processing machine, which also generates some file and put it back in storage. And etc. Everything was fine, but as number of processing machines increases, I found myself bottlenecked myself with storage machines hard drive performance. So I want processing machines to put files in distributed FS. to lift load from storage machines, from which they can take data from each other, not only storage machine. Can You suggest a particular distributed FS which meets my needs? Or there is another way to solve this problem, without it? Amounts of data in FS in one time are like several terabytes. (storage can handle this, but processors cannot). Data consistence is critical. Read write policy is: once file is written - its constant and may be only removed, but not modified. My current platform is Windows, but I'm ready to switch it, if there is a substantially more convenient solution on another one.

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  • How to Programmatically Split and Manipulate Rows of Data From Excel

    - by Charlene
    I am hoping one of you will be able to help get me started on this issue. I need to create some sort of macro or VBA code to split and manipulate rows of data in Excel. For this example, we have 5 rows of data. The first 3 rows are item information for Order # 0000000000-00 and the last 2 rows are item information for order # 0000000000-01. I need one row ("HDR") for each order number, and one row ("ITM") for each product per order. I have included an example below showing the data I will receive and the desired outcome. Raw Data: order-id product-num date buyer-name product-name quantity-purchased 0000000000-00 10000000000000 5/29/2014 John Doe Product 0 1 0000000000-00 10000000000001 5/29/2014 John Doe Product 1 2 0000000000-00 10000000000002 5/29/2014 John Doe Product 2 1 0000000000-01 10000000000002 5/30/2014 Jane Doe Product 2 1 0000000000-01 10000000000003 5/30/2014 Jane Doe Product 3 1 Desired Outcome: HDR 0000000000-00 John Doe 5/29/2014 ITM 10000000000000 Product 0 1 ITM 10000000000001 Product 1 2 ITM 10000000000002 Product 2 1 HDR 0000000000-01 Jane Doe 5/30/2014 ITM 10000000000002 Product 2 1 ITM 10000000000003 Product 3 1 Any and all help would be much appreciated!!! Thank you.

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  • Solr dataimporthandler problem import data latin

    - by Alvin
    I'm using Solr 1.4 and Tomcat6. DB mysql 5.1 store data latin. when i run dataimporthandler this data = view data in solr admin error font. <doc> <str name="id">295</str> <str name="subject">Tuấn Tú</str> - ...<arr name="title"> <str>tunt721</str> </arr> </doc> True data view : <doc> <str name="id">295</str> <str name="subject">Tu?n Tú</str> - ...<arr name="title"> <str>tunt721</str> </arr> </doc> help me fix problem. Many thanks

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  • Numbering grouped data in Excel

    - by Jeff
    I have an Excel spreadsheet (2010) with data similar to this: Dogs Brown Nice Dogs White Nice Dogs White Moody Cats Black Nice Cats Black Mean Cats White Nice Cats White Mean I want to group these animals but I only care about species and color. I don't care about disposition. I want to assign group numbers to the set as shown here. 1 Dogs Brown Nice 2 Dogs White Nice 2 Dogs White Moody 3 Cats Black Nice 3 Cats Black Mean 4 Cats White Nice 4 Cats White Mean I was able to select all the species and colors, then from the data tab select 'advanced', then 'unique records only'. This collapsed the data so that I could number the visible rows. Then when I 'cleared' the filter I could easily just fill the blank areas under the numbers with the number above. The problem is that my real data has far too many rows for this to be practical. Also, the trick about entering 1 in the first cell, 2 in the cell below, selecting both then dragging the corner down to 'auto-number' doesn't seem to work when you're viewing filtered rows. Any way to do this?

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  • How to publish internal data to the internet - as simple as possible

    - by mlarsen
    I Asked this at Staock Overflow, but I would like your oppinion too as it has as much to do with administration as it does with coding. We have a .net 2-tier application where a desktop program is talking to a database. We support MS SQL Server 2000, 2005, 2008 and Oracle 9, 10 and 11. The application is sold, not as shrink-wrap, but pretty close. It is quite important for us that the installation and configuration is as easy as possible as installation instructions are usually supplied in written form to the customers internal IT-department. Our application is usually not seen as mission critical for the IT-department, so we need to keep their work down to a minimum. Now we are starting to get wishes for a web application build on top of the same data. The web application will be hosted by us and delivered as a SaaS application. Now the challenge is how to move data back and forth between the web application and the customers internal database. as I see it we have some requirements: We must be ready to handle the situation where the customers database is not accessible from the DMZ. I guess the easiest solution is that all communication is initiated from inside the customers lan. As little firewall configuration as possible. The best is if we can run without any special configuration as long as outgoing traffic from the customers lan are not blocked. If we need something changed in the firewall, we must be able to document that the change is secure. It doesn't have to be real time. Moving data in batches every ten minutes or so is OK. Data moves both ways, but not the same tables, so we don't have to support merges. It would be nice if we don't have to roll our own framework completely. Looking forward to hear your suggestions.

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  • Accidentally dd'ed an image to wrong drive / overwrote partition table + NTFS partition start

    - by Kento Locatelli
    I screwed up and set the wrong output for dd when trying to copy a freenas iso, overwriting the wrong external hard drive. Ironically, I was trying to setup a freenas server for data backup... External drive is only used for data storage, system is entirely intact Drive had a single NTFS partition filing the entire device (2TB WD elements) Drive originally had an MBR partition table. Drive now shows as having a GPT, presumably from the freenas image. Drive was mounted at the time, with maybe a couple kB of data written/read after running dd Drive is just a few months old and healthy (regular SMART / fs checks) I have not reboot the OS (crunchbang) /proc/partition still holds the correct information (and has been stored) Have dd's output (records in / out / bytes) testdrive did not find any partitions on quick or deep search running photorec to recover the more important data (a couple recent plaintext files that hadn't been backed up yet). Vast majority of disk content ( 80%) is unnecessary media files. My current plan is to let photorec do it's thing, then recreate the mbr with gparted and use cfdisk to create another NTFS partition using the sector information from /sys/block/.../. Is that a good course of action (that is, a chance of success)? Or anything else I should try first? Possibly relevant information: dd if=FreeNAS-8.0.4-RELEASE-p3-x86.iso of=/dev/sdc: 194568+0 records in 194568+0 records out 99618816 bytes (100 MB) copied grep . /sys/block/sdc/sdc*/{start,size}: /sys/block/sdc/sdc1/start:2048 /sys/block/sdc/sdc1/size:3907022848 cat /proc/partitions: major minor #blocks name ** Snipped ** 8 32 1953512448 sdc 8 33 1953511424 sdc1 current fdisk -l output: WARNING: GPT (GUID Partition Table) detected on '/dev/sdc'! The util fdisk doesn't support GPT. Use GNU Parted. Disk /dev/sdc: 2000.4 GB, 2000396746752 bytes 255 heads, 63 sectors/track, 243201 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00000000 Disk /dev/sdc doesn't contain a valid partition table

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  • IIS FTP 7.5 Data Channel Problem (SSL)

    - by user59050
    Hey there I wonder if anyone can get me in the right direction. I am setting up both a FTPS Client and Server, FTPS Server using Microsoft’s iis FTP 7.5. On the client side it will be running on Linux and I am using M2crypto for the openssl wrapping (python). I am worried the problem is on the server side (iis7.5) due to the following discovery : If I host using Filezilla with BOTH the control and data channel being forced to be encrypted it works 100% (100% file transmission), if i use iis as the server everything works up to the point when the data channel takes over... i.e. all data of the retrieved file is already received correctly in my basket! The ftp server just won't send the final '226 Transfer complete.' on the cmd socket. Why? If i force the client or server to close the connection the file is 100% intact....If i use iis 7.5 with forced encryption on control channel all works 100% as long as i don’t force data channel... Here are some screenshots to demo this... Client View after Kill Client : pics @ http://forums.iis.net/p/1172936/1960994.aspx#1960994 Summary : We can establish the connection, do directory listings, start the upload, see the file (0bytes) created on the server but then the client hangs. If we terminate the client, the uploaded file on the server suddenly jumps up to full size.

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  • Data loss by randomly unplugging the computer during runtime

    - by Kan
    I'm from Austria and we and the Germans have some sort of bad science-show which runs every day. What I call it would rougly translate to "half-knowledge" if you want so. By the way: It is called "Galileo". So they thought they'd make a computer myth busters video right now, and I couldn't believe what I saw and heard... The strangest thing to me was that they asked: "Does unplugging the computer damage your data?" Then they started up some machine with Vista on it, started copying some files and randomly unplugged the PC cable, the whole thing around 50 times. After their computer continued to start up normally, they just said "nothing can happen, your data or computer can't be damaged". They of course excluded unsaved data in running programs like text editors from this. I asked myself: What the hell are their "computer experts" saying? You can't tell by unplugging the cable 50 times if that can damage your computer. Can unplugging the cable during runtime cause data loss (as said by the moderator of the show)? (I destroyed my windows registry once during a reset)

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  • Un-do Windows disk convert HFS+

    - by BLAKE
    Last night, a friend asked my to give him a copy of a word document. He handed me an external hard drive and left. I plugged the hard drive into my file server running Windows Server 2003, opened disk management and clicked OK. (I know that in Windows 2003 you need to manually assign a drive letter to external drives.) I then looked at the drive in disk management and it said that it was unallocated space. I called my friend and he said that there was data on the drive, but he used it with his Mac Book. Aperantly when I clicked OK in disk management I converted the from HFS+ file system to something else. Is there any way to undo the disk convert? I immediately removed the drive, so there was no writing to it. Windows did not format the drive, it just converted it. Is the data still there? All the data recovery programs I have are for windows, can they read the Mac file system? I need to get the data back, what can I do?

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  • Best solution top keep data secure

    - by mrwooster
    What is the simplest and most elegant way of storing a small amount of data in a reasonably secure way? I am not looking for ridiculous levels of advanced encryption (AES-256 is more than enough) and I am only looking to encrypt a small number of files. The files I wish to encrypt are mostly comprised of password lists and SSH keys for servers. Unfortunately it is impossible to keep track of ever changing passwords for my servers (and SSH keys) and so need to keep a list of the passwords. Obviously this list needs to be secure, and also portable (I work from multiple locations). At the moment, I use a 10MB encrypted disk image on my mac (std .dmg AES-256) and just mount it whenever I need access to the data. To my knowledge this is very secure and I am very happy using it. However, the data is not very portable. I would like to be able to access my data from other machines (especially ones running linux), and I am aware that there are quite a few issues trying to mount an encrypted .dmg on linux. An alternative I have considered is to create a tar archive containing the files and use gpg --symmetric to encrypt it, but this is not a very elegant solution as it requires gpg to be installed on every system. So, what over solutions exist, and which ones would you consider to be the most elegant? Ty

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  • Failed Software RAID0 on Linux - Attempting to recover data

    - by Gizmo_the_Great
    I have a two disk RAID0 software raid (not hardware raid) that is reported to have failed during boot and my OS won't start. Using a Live CD, I get the following output : sudo mdadm -E /dev/sdc1 /dev/sdd1 /dev/sdc1: Magic : a92b4efc Version : 1.2 Feature Map : 0x0 Array UUID : 3710713d:fb301031:84b61247:d1d53e0f Name : HP-xw9300:0 Creation Time : Sun Sep 1 15:22:26 2013 Raid Level : -unknown- Raid Devices : 0 Avail Dev Size : 1465145328 (698.64 GiB 750.15 GB) Data Offset : 16 sectors Super Offset : 8 sectors State : active Device UUID : ad427cd2:9f885f57:7f41015f:90f8f6af Update Time : Sun Jun 8 12:35:11 2014 Checksum : a37407ff - correct Events : 1 Device Role : spare Array State : ('A' == active, '.' == missing) /dev/sdd1: Magic : a92b4efc Version : 1.2 Feature Map : 0x0 Array UUID : 3710713d:fb301031:84b61247:d1d53e0f Name : HP-xw9300:0 Creation Time : Sun Sep 1 15:22:26 2013 Raid Level : -unknown- Raid Devices : 0 Avail Dev Size : 976771056 (465.76 GiB 500.11 GB) Data Offset : 16 sectors Super Offset : 8 sectors State : active Device UUID : 2ea0199d:cb08d9e7:0830448a:a1e1e348 Update Time : Sun Jun 8 13:06:19 2014 Checksum : 8883c492 - correct Events : 1 Device Role : spare Array State : ('A' == active, '.' == missing) GParted lists both disks, detects the flags as 'Raid' and lists the data usage. Can anyone please help me re-assemble just so that I can copy some of the data off that I have not backed up recently? Thanks

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  • ZFS & Deduplicating FLAC Data

    - by jasongullickson
    I'm experimenting with using ZFS to deduplicate a large library of FLAC files. The purpose of this is twofold: Reduce storage utilization Reduce bandwidth needed to sync the library with cloud storage Many of these files are of the same music tracks but from different physical media. This means that for the most part they are the same and usually close to the same size, which makes me think that they should benefit from block-level deduplication. However in my testing I'm not seeing good results. When I create a pool and add three of these tracks (identical songs from different source media) zpool list reports 1.00 dedupe. If I copy all of the files (make exact duplicates of the three) dedupe climbs, so I know that it is enabled and functioning, but it's not finding any duplication in the original collection of files. My first thought was that perhaps some of the variable header data (metadata tags, etc.) might be mis-aligning the bulk of the data in these files (the audio frames) but even making the header data consistent across the three files doesn't seem to have any impact on deduplication. I'm considering taking alternate routes (testing other dedupe filesystems as well as some custom code) but since we're already using ZFS and I like the ZFS replication options, I'd prefer to use ZFS dedupe for this project; but perhaps it's simply not capable of working well with this sort of data. Any feedback regarding tuning that might improve dedupe performance for this sort of dataset, or confirmation that ZFS dedupe is not the right tool for this job are appreciated.

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  • Un-do Windows disk convert HFS+

    - by BLAKE
    Last night, a friend asked my to give him a copy of a word document. He handed me an external hard drive and left. I plugged the hard drive into my file server running Windows Server 2003, opened disk management and clicked OK. (I know that in Windows 2003 you need to manually assign a drive letter to external drives.) I then looked at the drive in disk management and it said that it was unallocated space. I called my friend and he said that there was data on the drive, but he used it with his Mac Book. Aperantly when I clicked OK in disk management I converted the from HFS+ file system to something else. Is there any way to undo the disk convert? I immediately removed the drive, so there was no writing to it. Windows did not format the drive, it just converted it. Is the data still there? All the data recovery programs I have are for windows, can they read the Mac file system? I need to get the data back, what can I do?

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  • Show (copy) data at "X" time and stop update

    - by Anka
    I have two sheets. In the first sheet, cell F4, I have 00:00:00 (countdown). G9, G10 and G11 are cells that receive live data (decimal numbers). In the second sheet, I have three cells linked from sheet1, G9 ='Sheet1'!G9, G10 ='Sheet1'!G10, G11 ='Sheet1'!G11 (which update themselves when data is modified in the first sheet). Now I want to set in sheet 2, (assume) cells B9, B10 and B11 to show me (copy) the values from G9, G10 and G11 from sheet 1 when the countdown was 00:00:05 (5 seconds before Start) and not update again if the data changes in the cell it pulled the data from. Like G9 ='Sheet1'!G9 at 00:00:05 and stop here, do not update anything. OK? I can do a part, but the real problem is: I can not make it stop cells to update. Stand frozen, freeze, not move, calm .. however. I do not want to seem pretentious (but my knowledge in excel is limited), the most appropriate would be a formula, not macro or VBA, if possible. I want to post a picture but I can not because of my restrictions. Well, if this is not possible with a formula is just fine with (not really) VBA.

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  • Drupal: Exposing a module's data to Views2 using its API

    - by Sepehr Lajevardi
    I'm forking the filefield_stats module to provide it with the ability of exposing data into the Views module via the API. The filefield_stats module db table schema is as follow: <?php function filefield_stats_schema() { $schema['filefield_stats'] = array( 'fields' => array( 'fid' => array('type' => 'int', 'unsigned' => TRUE, 'not null' => TRUE, 'description' => 'Primary Key: the {files}.fid'), 'vid' => array('type' => 'int', 'unsigned' => TRUE, 'not null' => TRUE, 'description' => 'Primary Key: the {node}.vid'), 'uid' => array('type' => 'int', 'unsigned' => TRUE, 'not null' => TRUE, 'description' => 'The {users}.uid of the downloader'), 'timestamp' => array('type' => 'int', 'unsigned' => TRUE, 'not null' => TRUE, 'description' => 'The timestamp of the download'), 'hostname' => array('type' => 'varchar', 'length' => 128, 'not null' => TRUE, 'default' => '', 'description' => 'The hostname downloading the file (usually IP)'), 'referer' => array('type' => 'text', 'not null' => FALSE, 'description' => 'Referer for the download'), ), 'indexes' => array('fid_vid' => array('fid', 'vid')), ); return $schema; } ?> Well, so I implemented the hook_views_api() in filefield_stats.module & added a filefield_stats.views.inc file in the module's root directory, here it is: <?php // $Id$ /** * @file * Provide the ability of exposing data to Views2, for filefield_stats module. */ function filefield_stats_views_data() { $data = array(); $data['filefield_stats']['table']['group'] = t('FilefieldStats'); // Referencing the {node_revisions} table. $data['filefield_stats']['table']['join'] = array( 'node_revisions' => array( 'left_field' => 'vid', 'field' => 'vid', ), /*'files' => array( 'left_field' => 'fid', 'field' => 'fid', ), 'users' => array( 'left_field' => 'uid', 'field' => 'uid', ),*/ ); // Introducing filefield_stats table fields to Views2. // vid: The node's revision ID which wrapped the downloaded file $data['filefield_stats']['vid'] = array( 'title' => t('Node revision ID'), 'help' => t('The node\'s revision ID which wrapped the downloaded file'), 'relationship' => array( 'base' => 'node_revisions', 'field' => 'vid', 'handler' => 'views_handler_relationship', 'label' => t('Node Revision Reference.'), ), ); // uid: The ID of the user who downloaded the file. $data['filefield_stats']['uid'] = array( 'title' => t('User ID'), 'help' => t('The ID of the user who downloaded the file.'), 'relationship' => array( 'base' => 'users', 'field' => 'uid', 'handler' => 'views_handler_relationship', 'label' => t('User Reference.'), ), ); // fid: The ID of the downloaded file. $data['filefield_stats']['fid'] = array( 'title' => t('File ID'), 'help' => t('The ID of the downloaded file.'), 'relationship' => array( 'base' => 'files', 'field' => 'fid', 'handler' => 'views_handler_relationship', 'label' => t('File Reference.'), ), ); // hostname: The hostname which the file has been downloaded from. $data['filefield_stats']['hostname'] = array( 'title' => t('The Hostname'), 'help' => t('The hostname which the file has been downloaded from.'), 'field' => array( 'handler' => 'views_handler_field', 'click sortable' => TRUE, ), 'sort' => array( 'handler' => 'views_handler_sort', ), 'filter' => array( 'handler' => 'views_handler_filter_string', ), 'argument' => array( 'handler' => 'views_handler_argument_string', ), ); // referer: The referer address which the file download link has been triggered from. $data['filefield_stats']['referer'] = array( 'title' => t('The Referer'), 'help' => t('The referer which the file download link has been triggered from.'), 'field' => array( 'handler' => 'views_handler_field', 'click sortable' => TRUE, ), 'sort' => array( 'handler' => 'views_handler_sort', ), 'filter' => array( 'handler' => 'views_handler_filter_string', ), 'argument' => array( 'handler' => 'views_handler_argument_string', ), ); // timestamp: The time of the download. $data['filefield_stats']['timestamp'] = array( 'title' => t('Download Time'), 'help' => t('The time of the download.'), 'field' => array( 'handler' => 'views_handler_field_date', 'click sortable' => TRUE, ), 'sort' => array( 'handler' => 'views_handler_sort_date', ), 'filter' => array( 'handler' => 'views_handler_filter_date', ), ); return $data; } // filefield_stats_views_data() ?> According to the Views2 documentations this should work as a minimum, I think. But it doesn't! Also there is no error of any kind, when I come through the views UI, there's nothing about filefield_stats data. Any idea?

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  • SocketChannel in Java sends data, but it doesn't get to destination application

    - by Peterson
    Hi Everybody, I'm suffering a lot to create a simple ChatServer in Java, using the NIO libraries. Wonder if someone could help me. I am doing that by using SocketChannel and Selector to handle multiple clients in a single thread. The problem is: I am able to accept new connections and get it's data, but when I try to send data back, the SocketChannel simply doesn't work. In the method write(), it returns a integer that is the same size of the data i'm passing to it, but the client never receives that data. Strangely, when I close the server application, the client receives the data. It's like the socketchannel maintains a buffer, and it only get flushed when I close the application. Here are some more details, to give you more information to help. I'm handling the events in this piece of code: private void run() throws IOException { ServerSocketChannel ssc = ServerSocketChannel.open(); // Set it to non-blocking, so we can use select ssc.configureBlocking( false ); // Get the Socket connected to this channel, and bind it // to the listening port this.serverSocket = ssc.socket(); InetSocketAddress isa = new InetSocketAddress( this.port ); serverSocket.bind( isa ); // Create a new Selector for selecting this.masterSelector = Selector.open(); // Register the ServerSocketChannel, so we can // listen for incoming connections ssc.register( masterSelector, SelectionKey.OP_ACCEPT ); while (true) { // See if we've had any activity -- either // an incoming connection, or incoming data on an // existing connection int num = masterSelector.select(); // If we don't have any activity, loop around and wait // again if (num == 0) { continue; } // Get the keys corresponding to the activity // that has been detected, and process them // one by one Set keys = masterSelector.selectedKeys(); Iterator it = keys.iterator(); while (it.hasNext()) { // Get a key representing one of bits of I/O // activity SelectionKey key = (SelectionKey)it.next(); // What kind of activity is it? if ((key.readyOps() & SelectionKey.OP_ACCEPT) == SelectionKey.OP_ACCEPT) { // Aceita a conexão Socket s = serverSocket.accept(); System.out.println( "LOG: Conexao TCP aceita de " + s.getInetAddress() + ":" + s.getPort() ); // Make sure to make it non-blocking, so we can // use a selector on it. SocketChannel sc = s.getChannel(); sc.configureBlocking( false ); // Registra a conexao no seletor, apenas para leitura sc.register( masterSelector, SelectionKey.OP_READ ); } else if ( key.isReadable() ) { SocketChannel sc = null; // It's incoming data on a connection, so // process it sc = (SocketChannel)key.channel(); // Verifica se a conexão corresponde a um cliente já existente if((clientsMap.getClient(key)) != null){ boolean closedConnection = !processIncomingClientData(key); if(closedConnection){ int id = clientsMap.getClient(key); closeClient(id); } } else { boolean clientAccepted = processIncomingDataFromNewClient(key); if(!clientAccepted){ // Se o cliente não foi aceito, sua conexão é simplesmente fechada sc.socket().close(); sc.close(); key.cancel(); } } } } // We remove the selected keys, because we've dealt // with them. keys.clear(); } } This piece of code is simply handles new clients that wants to connect to the chat. So, a client makes a TCP connection to the server, and once it gets accepted, it sends data to the server following a simply text protocol, informing his id and asking to get registrated to the server. I handle this in the method processIncomingDataFromNewClient(key). I'm also keeping a map of clients and its connections in a data structure similar to a hashtable. I? doing that because I need to recover a client Id from a connection and a connection from a client Id. This is can be shown in: clientsMap.getClient(key). But the problem itself resides in the method processIncomingDataFromNewClient(key). There, I simply read the data that the client sent to me, validate it, and if it's ok, I send a message back to the client to tell that it is connected to the chat server. Here is a similar piece of code: private boolean processIncomingDataFromNewClient(SelectionKey key){ SocketChannel sc = (SocketChannel) key.channel(); String connectionOrigin = sc.socket().getInetAddress() + ":" + sc.socket().getPort(); int id = 0; //id of the client buf.clear(); int bytesRead = 0; try { bytesRead = sc.read(buf); if(bytesRead<=0){ System.out.println("Conexão fechada pelo: " + connectionOrigin); return false; } System.out.println("LOG: " + bytesRead + " bytes lidos de " + connectionOrigin); String msg = new String(buf.array(),0,bytesRead); // Do validations with the client sent me here // gets the client id }catch (Exception e) { e.printStackTrace(); System.out.println("LOG: Oops. Cliente não conhece o protocolo. Fechando a conexão: " + connectionOrigin); System.out.println("LOG: Primeiros 10 caracteres enviados pelo cliente: " + msg); return false; } } } catch (IOException e) { System.out.println("LOG: Erro ao ler dados da conexao: " + connectionOrigin); System.out.println("LOG: "+ e.getLocalizedMessage()); System.out.println("LOG: Fechando a conexão..."); return false; } // If it gets to here, the protocol is ok and we can add the client boolean inserted = clientsMap.addClient(key, id); if(!inserted){ System.out.println("LOG: Não foi possível adicionar o cliente. Ou ele já está conectado ou já têm clientes demais. Id: " + id); System.out.println("LOG: Fechando a conexão: " + connectionOrigin); return false; } System.out.println("LOG: Novo cliente conectado! Enviando mesnsagem de confirmação. Id: " + id + " Conexao: " + connectionOrigin); /* Here is the error */ sendMessage(id, "Servidor pet: connection accepted"); System.out.println("LOG: Novo cliente conectado! Id: " + id + " Conexao: " + connectionOrigin); return true; } And finally, the method sendMessage(SelectionKey key) looks like this: private void sendMessage(int destId, String msg) { Charset charset = Charset.forName("ISO-8859-1"); CharBuffer charBuffer = CharBuffer.wrap(msg, 0, msg.length()); ByteBuffer bf = charset.encode(charBuffer); //bf.flip(); int bytesSent = 0; SelectionKey key = clientsMap.getClient(destId); SocketChannel sc = (SocketChannel) key.channel(); try { / int total_bytes_sent = 0; while(total_bytes_sent < msg.length()){ bytesSent = sc.write(bf); total_bytes_sent += bytesSent; } System.out.println("LOG: Bytes enviados para o cliente " + destId + ": "+ total_bytes_sent + " Tamanho da mensagem: " + msg.length()); } catch (IOException e) { System.out.println("LOG: Erro ao mandar mensagem para: " + destId); System.out.println("LOG: " + e.getLocalizedMessage()); } } So, what is happening is that the server, when send a message, prints something like this: LOG: Bytes sent to the client: 28 Size of the message: 28 So, it tells that it sent the data, but the chat client keeps blocking, waiting in the recv() method. So, the data never gets to it. When I close the server application, though, all the data appears in the client. I wonder why. It is important to say that the client is in C and the server JAVA, and I'm running both in the same machine, an Ubuntu Guest in virtualbox under windows. I also run both under windows host and under linuxes hosts, and keep getting the same strange problem. I'm sorry for the great lenght of this question, but I already searched a lot of places for an answer, found a lot of tutorials and questions, including here at StackOverflow, but coundn't find a reasonable explanation. I am really not liking this Java NIO, and i saw a lot of people complaining about it too. I am thinking that if I had done that in C it would have been a lot easier :-D So, if someone could help me and even discuss this behavor, it would be great! :-) Thanks everybody in advance, Péterson

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  • ftp user and www-data

    - by andrii
    I have a websites that should be completely accessible for Apache(www-data user) and I have an ftp user(that has the same username on the server: user1) that should be able to update the website. I need the user to be able to add files to the website directory, but the www-data should have a full access to the added files. user1 is a member of www-data group. For now when user1 uploads file to the server the file has a rights: 644, but I need 664. How I could organise it. Many thanks

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  • error exporting data using mysql workbench

    - by Rajneesh Rana
    hi, i have been getting warning of version mismatch when i was trying to export data dump using mysql workbench. So, i copied mysqldump from mysql server folder and placed it in workbench folder. Now when i am trying to export data i am getting error Operation failed with exitcode -1073741819 here is a entry of log 16:31:25 Dumping wordpress (wp_posts) Running: "mysqldump.exe" --defaults-extra-file="c:\docume~1\rajneesh.r\locals~1\temp\1\tmpxau7tz" --no-create-info=FALSE --order-by-primary=FALSE --force=FALSE --no-data=FALSE --tz-utc=TRUE --flush-privileges=FALSE --compress=FALSE --replace=FALSE --host=localhost --insert-ignore=FALSE --extended-insert=TRUE --user=root --quote-names=TRUE --hex-blob=FALSE --complete-insert=FALSE --add-locks=TRUE --port=3306 --disable-keys=TRUE --delayed-insert=FALSE --create-options=TRUE --delete-master-logs=FALSE --comments=TRUE --default-character-set=utf8 --max_allowed_packet=1G --flush-logs=FALSE --dump-date=TRUE --lock-tables=TRUE --allow-keywords=FALSE --events=FALSE "wordpress" "wp_posts" Operation failed with exitcode -1073741819 Please help me with these issues Thank You

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  • Recovering portion(s) of file with CRC (cyclic redundancy check) errors in Robocopy

    - by Mark A
    Is it possible to recover portions of files with CRC errors? If so, how? I have a partially damaged hard drive (2.5" SATA) that I have partially recovered using Spinrite 6.0 (took 2 weeks to run!). I have been successful in getting many of the files off of the drive using Robocopy . /V /S /E /COPY:DAT /R:1 /W:0, but some of the files get to +/- 90% in Robocopy and then fail with a CRC Data Error (cyclic redundancy check). I am wondering if it is possible to recover the first 90% of the file and try to recover it in a text editor. 1.0% ... 91.0% 91.1% 2010/06/14 18:21:13 ERROR 23 (0x00000017) Copying File F:\Documents and Settings\user\Local Settings\Application Data\Identities\{GUID}\Microsoft\Outlook Express\Mailbox Folder.dbx Data error (cyclic redundancy check). Thanks in advance!

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  • How to change MySQL data directory?

    - by Jonathan Frank
    I want to place my databases in another directory, so I can store them in an ESB (elastic block storage, just a fancy name for a virtualized harddisk) together with my web-apps and other persistent data. I have tried to walk through a tutorial at http://crashmag.net/change-the-default-mysql-data-directory-with-selinux-enabled. Everything seems fine until I type this command: # semanage fcontext -a -t mysqld_db_t "/srv/mysql(/.*)?" Then the command fails and tells me that mysqld_db_t is an invalid SELinux context even if the default MySQL data directory is labelled with this context. I am running Fedora 15 on Virtualbox (behaves like an ordinary x86-compatible box) and Amazon EC2 (based on Xen) so the tutorial should be compatible. It is also worth to mention that turning off SELinux globally or just for the MySQL process is not an option, because such a solution will decrease the security of the system if a hacker gains access to the system via the MySQL server. I have never seen this problem before I changed to the Redhat/Fedora architecture, so it could be a distribution specific issue. Any help is highly appreciated

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  • sendmail on Ubuntu won't send from www-data user

    - by bumperbox
    I if call mail() function in PHP from webserver (running as www-data) i get an error sending email. If i call the same script from the cmdline logged in as root, then it works If i switch user to www-data and run from the cmdline i get this error message WARNING: RunAsUser for MSP ignored, check group ids (egid=33, want=107) can not chdir(/var/spool/mqueue-client/): Permission denied Program mode requires special privileges, e.g., root or TrustedUser. FAILEDWARNING: RunAsUser for MSP ignored, check group ids (egid=33, want=107) can not chdir(/var/spool/mqueue-client/): Permission denied Program mode requires special privileges, e.g., root or TrustedUser. FAILEDTest Complete$ WARNING: RunAsUser for MSP ignored, check group ids (egid=33, want=107) I am guessing i need to do something in sendmail configuration I have googled for some solutions but have ended up more confused. Can someone let me know what configuration I need to change to fix so i can send from www-data user?

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  • Best alternatives to recover lost directories in FAT32 external hard drive?

    - by Sergio
    Hi: I have an 320 GB ADATA CH91 external hard drive. I guess it has some problems with the connector of the USB jack. The point is that in certain occasions it fails in write operations generating data losses. Right now I lost a directory with several GB's of very useful information. Since then I have not attempted to write to the disk any more. What tool would you recommend to recover the lost data? The disk is FAT32 formatted (only one partition) and I use both Linux and Windows. What filesystem format would you recommend to avoid future data losses? I currently only use this external hard drive in Linux so there are several available choices (FAT, NTFS, ext3, ext4, reiser, etc.). Regards, Sergio

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