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• Java plugin framework choice

  - by Marcus

  We're trying to determine how to implement a simple plugin framework for a service we are implementing that allows different types of calculators to be "plugged-in". After reading a number of posts about Java plugin frameworks, it seems like the most common options are: OSGI "Rolling your own" plugin framework The Java Plugin Framework (JPF) The Java Simple Plugin Framework (JSPF) OSGI seems to be more than we need. "Rolling your own" is ok but it would be nice to reuse a common library. So we're down to the JPF and JSPF. JPF seems to not be in active development right now. JSPF seems very simple and really all we need. However I haven't heard much about it. I've only seen one post on StackOverflow about it. Does anyone else have any experience with JSPF? Or any other comments on this design choice? Update: There isn't necessarily a correct answer to this.. however we're going to go with Pavol's idea as we need just a really, really simple solution. Thanks EoH for the nice guide.

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• How to fix: unrecognized selector sent to instance

  - by Matt

  I am having a problem that may be simple to fix, but not simple for me to debug. I simple have a button inside a view in IB; the file's owner is set to the view controller class I am using and when making the connections, everything seems fine, ie. the connector is finding the method I am trying to call etc. however, I am receiving this error: Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** -[UIApplication getStarted:]: unrecognized selector sent to instance 0x3d19130' My code is as follows: RootViewController.h @interface RootViewController : UIViewController { IBOutlet UIButton* getStartedButton; } @property (nonatomic, retain) UIButton* getStartedButton; - (IBAction) getStarted: (id)sender; @end RootViewController.m #import "RootViewController.h" #import "SimpleDrillDownAppDelegate.h" @implementation RootViewController @synthesize getStartedButton; - (void)viewDidLoad { [super viewDidLoad]; } - (IBAction) getStarted: (id)sender { NSLog(@"Button Tapped!"); //[self.view removeFromSuperview]; } - (void)dealloc { [getStartedButton release]; [super dealloc]; } @end Seems simple enough...any thoughs?

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• Removing "Using temporary; Using filesort" from this MySQL select+join+group by query

  - by claytontstanley

  I have the following query: select t.Chunk as LeftChunk, t.ChunkHash as LeftChunkHash, q.Chunk as RightChunk, q.ChunkHash as RightChunkHash, count(t.ChunkHash) as ChunkCount from chunksubset as t join chunksubset as q on t.ID = q.ID group by LeftChunkHash, RightChunkHash And the following explain table: id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE subsets ref PRIMARY,IDIndex,SubsetIndex SubsetIndex 767 const 522014 "Using where; Using temporary; Using filesort" 1 SIMPLE subsets eq_ref PRIMARY,IDIndex,SubsetIndex PRIMARY 771 sotero.subsets.Id,const 1 "Using where; Using index" 1 SIMPLE c ref IDIndex IDIndex 4 sotero.subsets.Id 12 "Using where" 1 SIMPLE c ref IDIndex IDIndex 4 sotero.subsets.Id 12 note the "using temporary; using filesort". When this query is run, I quickly run out of RAM (presumably b/c of the temp table), and then the HDD kicks in, and the query slows to a halt. I thought it might be an index issue, so I started adding a few that sort of made sense: Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment Index_comment chunks 0 PRIMARY 1 ChunkId A 17796190 NULL NULL BTREE chunks 1 ChunkHashIndex 1 ChunkHash A 243783 NULL NULL BTREE chunks 1 IDIndex 1 Id A 1483015 NULL NULL BTREE chunks 1 ChunkIndex 1 Chunk A 243783 NULL NULL BTREE chunks 1 ChunkTypeIndex 1 ChunkType A 2 NULL NULL BTREE chunks 1 chunkHashByChunkIDIndex 1 ChunkHash A 243783 NULL NULL BTREE chunks 1 chunkHashByChunkIDIndex 2 ChunkId A 17796190 NULL NULL BTREE chunks 1 chunkHashByChunkTypeIndex 1 ChunkHash A 243783 NULL NULL BTREE chunks 1 chunkHashByChunkTypeIndex 2 ChunkType A 261708 NULL NULL BTREE chunks 1 chunkHashByIDIndex 1 ChunkHash A 243783 NULL NULL BTREE chunks 1 chunkHashByIDIndex 2 Id A 17796190 NULL NULL BTREE But still using the temporary table. The db engine is MyISAM. How can I get rid of the using temporary; using filesort in this query? Just changing to InnoDB w/o explaining the underlying cause is not a particularly satisfying answer. Besides, if the solution is to just add the proper index, then that's much easier than migrating to another db engine.

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• How to insert several thousand columns into sqlite3?

  - by user291071

  Similar to my last question, but I ran into problem lets say I have a simple dictionary like below but its Big, when I try inserting a big dictionary using the methods below I get operational error for the c.execute(schema) for too many columns so what should be my alternate method to populate an sql databases columns? Using the alter table command and add each one individually? import sqlite3 con = sqlite3.connect('simple.db') c = con.cursor() dic = { 'x1':{'y1':1.0,'y2':0.0}, 'x2':{'y1':0.0,'y2':2.0,'joe bla':1.5}, 'x3':{'y2':2.0,'y3 45 etc':1.5} } # 1. Find the unique column names. columns = set() for _, cols in dic.items(): for key, _ in cols.items(): columns.add(key) # 2. Create the schema. col_defs = [ # Start with the column for our key name '"row_name" VARCHAR(2) NOT NULL PRIMARY KEY' ] for column in columns: col_defs.append('"%s" REAL NULL' % column) schema = "CREATE TABLE simple (%s);" % ",".join(col_defs) c.execute(schema) # 3. Loop through each row for row_name, cols in dic.items(): # Compile the data we have for this row. col_names = cols.keys() col_values = [str(val) for val in cols.values()] # Insert it. sql = 'INSERT INTO simple ("row_name", "%s") VALUES ("%s", "%s");' % ( '","'.join(col_names), row_name, '","'.join(col_values) )

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• MySql product\tag query optimisation - please help!

  - by Nige

  Hi There I have an sql query i am struggling to optimise. It basically is used to pull back products for a shopping cart. The products each have tags attached using a many to many table product_tag and also i pull back a store name from a separate store table. Im using group_concat to get a list of tags for the display (this is why i have the strange groupby orderby clauses at the bottom) and i need to order by dateadded, showing the latest scheduled product first. Here is the query.... SELECT products.*, stores.name, GROUP_CONCAT(tags.taglabel ORDER BY tags.id ASC SEPARATOR " ") taglist FROM (products) JOIN product_tag ON products.id=product_tag.productid JOIN tags ON tags.id=product_tag.tagid JOIN stores ON products.cid=stores.siteid WHERE dateadded < '2010-05-28 07:55:41' GROUP BY products.id ASC ORDER BY products.dateadded DESC LIMIT 2 Unfortunately even with a small set of data (3 tags and about 12 products) the query is taking 00.0034 seconds to run. Eventually i want to have about 2000 products and 50 tagsin this system (im guessing this will be very slooooow). Here is the ExplainSql... id|select_type|table|type|possible_keys|key|key_len|ref|rows|Extra 1|SIMPLE|tags|ALL|PRIMARY|NULL|NULL|NULL|4|Using temporary; Using filesort 1|SIMPLE|product_tag|ref|tagid,productid|tagid|4|cs_final.tags.id|2| 1|SIMPLE|products|eq_ref|PRIMARY,cid|PRIMARY|4|cs_final.product_tag.productid|1|Using where 1|SIMPLE|stores|ALL|siteid|NULL|NULL|NULL|7|Using where; Using join buffer Can anyone help?

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• Inexplicably slow query in MySQL

  - by Brandon M.

  Given this result-set: mysql> EXPLAIN SELECT c.cust_name, SUM(l.line_subtotal) FROM customer c -> JOIN slip s ON s.cust_id = c.cust_id -> JOIN line l ON l.slip_id = s.slip_id -> JOIN vendor v ON v.vend_id = l.vend_id WHERE v.vend_name = 'blahblah' -> GROUP BY c.cust_name -> HAVING SUM(l.line_subtotal) > 49999 -> ORDER BY c.cust_name; +----+-------------+-------+--------+---------------------------------+---------------+---------+----------------------+------+----------------------------------------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+-------+--------+---------------------------------+---------------+---------+----------------------+------+----------------------------------------------+ | 1 | SIMPLE | v | ref | PRIMARY,idx_vend_name | idx_vend_name | 12 | const | 1 | Using where; Using temporary; Using filesort | | 1 | SIMPLE | l | ref | idx_vend_id | idx_vend_id | 4 | csv_import.v.vend_id | 446 | | | 1 | SIMPLE | s | eq_ref | PRIMARY,idx_cust_id,idx_slip_id | PRIMARY | 4 | csv_import.l.slip_id | 1 | | | 1 | SIMPLE | c | eq_ref | PRIMARY,cIndex | PRIMARY | 4 | csv_import.s.cust_id | 1 | | +----+-------------+-------+--------+---------------------------------+---------------+---------+----------------------+------+----------------------------------------------+ 4 rows in set (0.04 sec) I'm a bit baffled as to why the query referenced by this EXPLAIN statement is still taking about a minute to execute. Isn't it true that this query only has to search through 449 rows? Anyone have any idea as to what could be slowing it down so much?

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• Making firefox refresh images faster

  - by Earlz

  I have a thing I'm doing where I need a webpage to stream a series of images from the local client computer. I have a very simple run here: http://jsbin.com/idowi/34 The code is extremely simple setTimeout ( "refreshImage()", 100 ); function refreshImage(){ var date = new Date() var ticks = date.getTime() $('#image').attr('src','http://127.0.0.1:2723/signature?'+ticks.toString()); setTimeout ("refreshImage()", 100 ); } Basically I have a signature pad being used on the client machine. We want for the signature to show up in the web page and for them to see themselves signing it within the web page(the pad does not have an LCD to show it to them right there). So I setup a simple local HTTP server which grabs an image of what the current state of the signature pad looks like and it gets sent to the browser. This has no problems in any browser(tested in IE7, 8, and Chrome) but Firefox where it is extremely laggy and jumpy and doesn't keep with the 10 FPS rate. Does anyone have any ideas on how to fix this? I've tried creating very simple double buffering in javascript but that just made things worse. Also for a bit more information it seems that Firefox is executing the javascript at the correct framerate as on the server the requests are coming in at a constant speed. But the images are only refreshed inconsistently ranging from 5 times per second all the way down to 0 times per second(taking 2 seconds to do a refresh) Also I have tried using different image formats all with the same results. The formats I've tried include bitmaps, PNGs, and GIFs (GIFs caused a minor problem in Chrome with flicker though) Could it be possible that Firefox is somehow caching my images causing a slight lag? I send these headers though: Pragma-directive: no-cache Cache-directive: no-cache Cache-control: no-cache Pragma: no-cache Expires: 0

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• Using SimpleDB (with SimpleSavant) with POCO / existing entities, not attributes on my classes

  - by alex

  I'm trying to use Simple Savant within my application, to use SimpleDB I currently have (for example) public class Person { public Guid Id { get; set; } public string Name { get; set; } public string Description { get; set; } public DateTime DateOfBirth { get; set; } } To use this with Simple Savant, i'd have to put attributes above the class declaration, and property - [DomainName("Person")] above the class, and [ItemName] above the Id property. I have all my entities in a seperate assembly. I also have my Data access classes an a seperate assembly, and a class factory selects, based on config, the IRepository (in this case, IRepository I want to be able to use my existing simple class - without having attributes on the properties etc.. In case I switch out of simple db, to something else - then I only need to create a different implementation of IRepository. Should I create a "DTO" type class to map the two together? Is there a better way?

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• Voice Recognition Google API

  - by user2966744

  thanks for reading. I'm creating a simple web based drawing app that uses speech recognition. I have created a simple page, the project is on github here: https://github.com/a5hton/speechdraw It has a 16x16 pixel grid. I would like to be able to draw on this grid by using simple words. For example if you say "right", the pixel to the right will be colored black. If you say "down" the pixel below the last one will be colored black. You can say up, down, left or right and the corresponding pixels will be colored. Saying "erase" will switch to erase mode, colouring the pixels back to their original color. Saying "lift" will lift the pen off the page. Saying "draw" will enable the draw mode. Could you please help me work out how to make this happen. Please see the simple page at to get an understanding. Thank you! Cheers, Michael

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• QNTC and Windows Server 2008 R2

  - by Ben

  I am having a really hard time getting an iSeries (AS/400) machine talking to my new Windows Server 2008 R2 box using the QNTC file system on the iSeries. I had similar problems getting it to initially talk to a Windows Server 2003 machine, but enabling the local Guest account on the 2003 box solved that one. No such luck with the new 2008 box. When I do a WRKLNK /QNTC/SVR01 on the iSeries (which should show share listings, and does on any 2003 boxes) all I get is (Cannot find object to match specified name.). I know the iSeries likes the same username and password on the remote server, but unfortunately for us this is not the case. Anyhow, it does currently work with different username/password combinations on a 2003 box. To try and get the wretched things talking, I have made the 2008 server pretty open but the iSeries will not see shares on it. I have enabled the local Guest account, turned Windows firewall off, set the share permissions so Everyone has full control but to no avail. I read something on the internet about the iSeries only being able to handle NTLM authentication (and I understand by default that Server 2008 R2 only uses NTLMv2 and has NTLM disabled), so I made a special group policy for the server and tweaked all Group Policy settings under Computer Configuration\Policies\Windows Settings\Security Settings\Local Policies\Security Options but the iSeries STILL won't see it. We have a team of programmers who do all the system administration of the iSeries, but they are stumped for ideas on their side, and I'm stumped for ideas on my side. This is driving me crazy now, and if anybody has managed to get an iSeries to talk to Windows Server 2008 R2 using QNTC I would be very appreciative of any suggestions, be it on the Windows side, iSeries settings or even IBM PTF's that might patch anything. The iSeries is running V5R4 and I have *SECOFR privileges on it, if it helps. One final (most important!) note - The programmers think it's my system being tricky, and I think it's theirs - please prove me right :)

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• pfSense: How to route traffic out the WAN port?

  - by Ian Boyd

  Expert version i want to create a route in pfSense that will send traffic out the physical WAN port, not the PPPoE WAN port. i want to talk to talk to the web-server on my DSL modem, but it doesn't see packets wrapped in a PPPoE header. Long version My pfSense router is responsible for setting up the PPPoE connection over DSL to my ISP. When a machine on the LAN wants to sent packets to the internet, the default route sends packets out over the PPPoE connection. Those packets, wrapped in a PPPoE header, are sent on the ethernet cable to my DSL modem. From there they are sent the ISP, and the internet at large. i want a way to send a packet out the WAN port itself - not the PPPoE WAN port. My modem is sitting out there, with a http interface where i can monitor connection speed signal-to-noise ratio bandwidth connection time Whenever i try to set a route for destination of 192.168.2.1 (the IP that the modem will listen to for HTTP requests) to go out the WAN port, they instead end up going out the PPPoE port. The difference being that they're wrapped in a PPPoE protocol packet, and the modem isn't being sent the packet, it's being delivered to the ISP. Given that pfSense has no ability to direct traffic out the physical WAN port: how can i direct traffic out the physical WAN port on pfSense?

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• What is the correct iptables rule when NATing multiple private subnets?

  - by Jose Mendez

  I have a Centos minimal 6.5 acting as a router. eth0 is connected to a Cisco switch trunk port, allowing VLANs 200-213. I have several VLAN interfaces just as this link suggests: https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Deployment_Guide/s2-networkscripts-interfaces_802.1q-vlan-tagging.html And have IPv4 forwarding, so all my network devices from any of the networks 200-213 can communicate with each other using this linux box as their router. Problem is, I need them to access the Internet, so I added the following rule: iptables -t nat -A POSTROUTING -s 192.168.0.0/16 -j SNAT --to 1.1.1.56 1.1.1.56 is the "outside" address. This works fine, devices connected to the internal networks can ping Intertnet addresses BUT, they stop being able to talk to each other across subnets, so 192.168.211.55 can ping 8.8.8.8, but can't talk to 192.168.213.5. As soon as I do a service iptables restart to remove the rule, I can start talking across internal subnets again. What would be the correct way to set up NAT for multiple private subnets? Or maybe the correct way to set up forwarding?

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• New AD-DC in a new Site is refusing cross-site IPv4 connections

  - by sysadmin1138

  We just added a new Server 2008 (sp2) Domain Controller in a new Site, our first such config. It's over a VPN gateway WAN (10Mbit). Unfortunately it is displaying a strange network symptom. Connections to the SMB ports (TCP/139 and TCP/445) are being actively refused... if the connection is coming in on pure IPv4. If the incoming connection is coming by way of the 6to4 tunnel those connections establish and work just fine. It isn't the Firewall, since this behavior can be replicated with the firewall turned off. Also, it's actually issuing RST packets to connection attempts; something that only happens with a Windows Firewall if there is a service behind a port and the service itself denies access. I doubt it's some firewall device on the wire, since the server this one replaced was running Samba and access to it from our main network functioned just fine. I'm thinking it might have something to do with the Subnet lists in AD Sites & Services, but I'm not sure. We haven't put any IPv6 addresses in there, just v4, and it's the v4 connections that are being denied. Unfortunately, I can't figure this out. We need to be able to talk to this DC from the main campus. Is there some kind of site-based SMB-level filtering going on? I can talk to the DC's on campus just fine, but that's over that v6 tunnel. I don't have access to a regular machine on that remote subnet, which limits my ability to test.

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• How can I mount dd image of a partition?

  - by Puneet Arora

  I created a dd image of a partition (containing an HFS+ FS) of one of my disks (and not the entire disk) a few days ago using the following command - dd conv=sync,noerror bs=8k if=/dev/sdc2 of=/path/to/img How can I mount it? I tried the following but it doesn't work - mount -o loop,ro -t hfsplus /path/to/img /path/to/mntDir It gives me mount: wrong fs type, bad option, bad superblock on /dev/loop1, missing codepage or helper program, or other error In some cases useful info is found in syslog - try dmesg | tail or so and dmesg | tail gives me - [5248455.568479] hfs: invalid secondary volume header [5248455.568494] hfs: unable to find HFS+ superblock [5248462.674836] hfs: invalid secondary volume header [5248462.674843] hfs: unable to find HFS+ superblock [5248550.672105] hfs: invalid secondary volume header [5248550.672115] hfs: unable to find HFS+ superblock [5248993.612026] hfs: unable to find HFS+ superblock [5248998.103385] hfs: unable to find HFS+ superblock [5249031.441359] hfs: unable to find HFS+ superblock [5249036.274864] hfs: unable to find HFS+ superblock Is there something wrong that I am doing? I tried searching on how to do this but all the results I get only talk about mounting a partition from within a full disk image, using the offset option with mount - none talk about the case where the image itself is that of a partition. Thanks. PS: I'm running 64bit Arch Linux, and the partition from the original disk /dev/sdc2 mounts fine.

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• Can any postfix guru assist me determine how emails are still being sent via my server from unauthorized sources?

  - by Dave

  Hi all, I'm getting a little concerned as I run a small server hosting a number of websites and manage the email for a few dozen people. Just recently though I've had a couple of notifications from spamcop alerting me that spam has been sent from my server, and when I have a look over the logs from time to time I can indeed see that there are many repeated attempts of mail being sent from my server. Most of the time it gets knocked back from the destination servers but sometimes its getting through. Unfortunately I'm not linux or postfix expert, I can get by but had though I had my machine locked down quite securely, I don't allow relaying, when I check the online DNS/MX tools they tend to report my server as being OK so I'm not sure where to take it now and hoping someone might be able to throw me a few pointers. I get lots of entries like this in my MAIL.INFO log Jan 2 08:39:34 Debian-50-lenny-64-LAMP postfix/qmgr[15993]: 66B88257C12F: from=<>, size=3116, nrcpt=1 (queue active) Jan 2 08:39:34 Debian-50-lenny-64-LAMP postfix/qmgr[15993]: 614C2257C1BC: from=<[email protected]>, size=2490, nrcpt=3 (queue active) and Jan 7 16:09:37 Debian-50-lenny-64-LAMP postfix/error[6471]: 0A316257C204: to=<[email protected]>, relay=none, delay=384387, delays=384384/3/0/0.01, dsn=4.0.0, status=deferred (delivery temporarily suspended: host mx.fakemx.net[46.4.35.23] refused to talk to me: 421 mx.fakemx.net Service Unavailable) Jan 7 16:09:37 Debian-50-lenny-64-LAMP postfix/error[6470]: 5848C257C20D: to=<[email protected]>, relay=none, delay=384373, delays=384370/3/0/0.01, dsn=4.0.0, status=deferred (delivery temporarily suspended: host mx.fakemx.net[46.4.35.23] refused to talk to me: 421 mx.fakemx.net Service Unavailable) then there tends to be connection timeouts, so from what I see even though I had relaying disabled.. something is getting by and trying to send.. So if you can help that will be greatly appreciated, and any further logging/config info I can supply. Thanks

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• Would like to change audio codec, but keep video settings with ffmpeg

  - by Craig Tataryn

  I have a video for which I'd like to convert the audio codec to AAC 320 kbps / 44.100 kHz. What would I use for ffmpeg switches such that all the video settings and codec remain the same, but only the audio codec and settings change? Here's my video: $ ffmpeg -i Winnipeg.rb\ Scala-Talk.mov FFmpeg version SVN-r25375, Copyright (c) 2000-2010 the FFmpeg developers built on Oct 6 2010 13:02:41 with gcc 4.2.1 (Apple Inc. build 5664) configuration: --enable-libmp3lame --enable-shared --disable-mmx --arch=x86_64 libavutil 50.32. 2 / 50.32. 2 libavcore 0. 9. 1 / 0. 9. 1 libavcodec 52.92. 0 / 52.92. 0 libavformat 52.80. 0 / 52.80. 0 libavdevice 52. 2. 2 / 52. 2. 2 libavfilter 1.48. 0 / 1.48. 0 libswscale 0.12. 0 / 0.12. 0 Seems stream 0 codec frame rate differs from container frame rate: 2000.00 (2000/1) -> 10.00 (10/1) Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'Winnipeg.rb Scala-Talk.mov': Metadata: major_brand : qt minor_version : 537199360 compatible_brands: qt Duration: 01:10:53.00, start: 0.000000, bitrate: 283 kb/s Stream #0.0(eng): Video: h264, yuv420p, 800x598, 94 kb/s, 10 fps, 10 tbr, 1k tbn, 2k tbc Stream #0.1(eng): Audio: adpcm_ima_qt, 22050 Hz, 1 channels, s16 Stream #0.2(eng): Audio: adpcm_ima_qt, 22050 Hz, 1 channels, s16 At least one output file must be specified Many thanks in advance! One with with ffmpeg I've never been able to grok is how to just "tweak" files without having to regurgitate every little setting for things you don't want changes.

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• Preventing endless forwarding with two routers

  - by jarmund

  The network in quesiton looks basically like this: /----Inet1 / H1---[111.0/24]---GW1---[99.0/24] \----GW2-----Inet2 Device explaination H1: Host with IP 192.168.111.47 GW1: Linux box with IPs 192.168.111.1 and 192.168.99.2, as well as its own route to the internet. GW2: Generic wireless router with IP 192.168.99.1 and its own route to the internet. Inet1 & Inet2: Two possible routes to the internet In short: H has more than one possible route to the internet. H is supposed to only access the internet via GW2 when that link is up, so GW1 has some policy based routing special just for H1: ip rule add from 192.168.111.47 table 991 ip route add default via 192.168.99.1 table 991 While this works as long as GW2 has a direct link to the internet, the problem occurs when that link is down. What then happens is that GW2 forwards the packet back to GW1, which again forwards back to GW2, creating an endless loop of TCP-pingpong. The preferred result would be that the packet was just dropped. Is there something that can be done with iptables on GW1 to prevent this? Basically, an iptables-friendly version of "If packet comes from GW2, but originated from H1, drop it" Note1: It is preferable not to change anything on GW2. Note2: H1 needs to be able to talk to both GW1 and GW2, and vice versa, but only GW2 should lead to the internet TLDR; H1 should only be allowed internet access via GW2, but still needs to be able to talk to both GW1 and GW2. EDIT: The interfaces for GW1 are br0.105 for the '99' network, and br0.111 for the '111' network. The sollution may or may not be obnoxiously simple, but i have not been able to produce the proper iptables syntax myself, so help would be most appreciated. PS: This is a follow-up question from this question

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• what is best multi-server configuration with OpenVPN

  - by sebut

  We have a number of Database severs running MongoDB on Debian plus a number of Application servers also on Debian. The db servers hold replicating db clusters, so they need to talk to each other. Application servers need to talk to all db servers (for reasons of fault tolerance). The servers are potentially spread across multiple hosting centers, so we need secure channels between all servers. The number of servers is bound to grow, so we need a VPN solution that's easy to maintain and expand. This is why I feel that SSH that we use for testing might not be up to the task and OpenVPN seems the way to go. I have ruled out TAP, since I understand that this would mean all traffic going to all the servers - perhaps this is a misunderstanding and TAP acts more like a switch? With TUN devices I imagine that all DB servers would live in their own separate subnet, they would also need a client configured to be able to connect to each of their peers. The application servers could live in a common subnet range with a client config only. Does this sound like a reasonable setup? Strangely, on the web I did not find anything about multi-server with OpenVPN. Thanks for all insights and ideas!

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• C# 4: The Curious ConcurrentDictionary

  - by James Michael Hare

  In my previous post (here) I did a comparison of the new ConcurrentQueue versus the old standard of a System.Collections.Generic Queue with simple locking.  The results were exactly what I would have hoped, that the ConcurrentQueue was faster with multi-threading for most all situations.  In addition, concurrent collections have the added benefit that you can enumerate them even if they're being modified. So I set out to see what the improvements would be for the ConcurrentDictionary, would it have the same performance benefits as the ConcurrentQueue did?  Well, after running some tests and multiple tweaks and tunes, I have good and bad news. But first, let's look at the tests.  Obviously there's many things we can do with a dictionary.  One of the most notable uses, of course, in a multi-threaded environment is for a small, local in-memory cache.  So I set about to do a very simple simulation of a cache where I would create a test class that I'll just call an Accessor.  This accessor will attempt to look up a key in the dictionary, and if the key exists, it stops (i.e. a cache "hit").  However, if the lookup fails, it will then try to add the key and value to the dictionary (i.e. a cache "miss").  So here's the Accessor that will run the tests: 1: internal class Accessor 2: { 3: public int Hits { get; set; } 4: public int Misses { get; set; } 5: public Func<int, string> GetDelegate { get; set; } 6: public Action<int, string> AddDelegate { get; set; } 7: public int Iterations { get; set; } 8: public int MaxRange { get; set; } 9: public int Seed { get; set; } 10:  11: public void Access() 12: { 13: var randomGenerator = new Random(Seed); 14:  15: for (int i=0; i<Iterations; i++) 16: { 17: // give a wide spread so will have some duplicates and some unique 18: var target = randomGenerator.Next(1, MaxRange); 19:  20: // attempt to grab the item from the cache 21: var result = GetDelegate(target); 22:  23: // if the item doesn't exist, add it 24: if(result == null) 25: { 26: AddDelegate(target, target.ToString()); 27: Misses++; 28: } 29: else 30: { 31: Hits++; 32: } 33: } 34: } 35: } Note that so I could test different implementations, I defined a GetDelegate and AddDelegate that will call the appropriate dictionary methods to add or retrieve items in the cache using various techniques. So let's examine the three techniques I decided to test: Dictionary with mutex - Just your standard generic Dictionary with a simple lock construct on an internal object. Dictionary with ReaderWriterLockSlim - Same Dictionary, but now using a lock designed to let multiple readers access simultaneously and then locked when a writer needs access. ConcurrentDictionary - The new ConcurrentDictionary from System.Collections.Concurrent that is supposed to be optimized to allow multiple threads to access safely. So the approach to each of these is also fairly straight-forward.  Let's look at the GetDelegate and AddDelegate implementations for the Dictionary with mutex lock: 1: var addDelegate = (key,val) => 2: { 3: lock (_mutex) 4: { 5: _dictionary[key] = val; 6: } 7: }; 8: var getDelegate = (key) => 9: { 10: lock (_mutex) 11: { 12: string val; 13: return _dictionary.TryGetValue(key, out val) ? val : null; 14: } 15: }; Nothing new or fancy here, just your basic lock on a private object and then query/insert into the Dictionary. Now, for the Dictionary with ReadWriteLockSlim it's a little more complex: 1: var addDelegate = (key,val) => 2: { 3: _readerWriterLock.EnterWriteLock(); 4: _dictionary[key] = val; 5: _readerWriterLock.ExitWriteLock(); 6: }; 7: var getDelegate = (key) => 8: { 9: string val; 10: _readerWriterLock.EnterReadLock(); 11: if(!_dictionary.TryGetValue(key, out val)) 12: { 13: val = null; 14: } 15: _readerWriterLock.ExitReadLock(); 16: return val; 17: }; And finally, the ConcurrentDictionary, which since it does all it's own concurrency control, is remarkably elegant and simple: 1: var addDelegate = (key,val) => 2: { 3: _concurrentDictionary[key] = val; 4: }; 5: var getDelegate = (key) => 6: { 7: string s; 8: return _concurrentDictionary.TryGetValue(key, out s) ? s : null; 9: };                    Then, I set up a test harness that would simply ask the user for the number of concurrent Accessors to attempt to Access the cache (as specified in Accessor.Access() above) and then let them fly and see how long it took them all to complete.  Each of these tests was run with 10,000,000 cache accesses divided among the available Accessor instances.  All times are in milliseconds. 1: Dictionary with Mutex Locking 2: --------------------------------------------------- 3: Accessors Mostly Misses Mostly Hits 4: 1 7916 3285 5: 10 8293 3481 6: 100 8799 3532 7: 1000 8815 3584 8:  9:  10: Dictionary with ReaderWriterLockSlim Locking 11: --------------------------------------------------- 12: Accessors Mostly Misses Mostly Hits 13: 1 8445 3624 14: 10 11002 4119 15: 100 11076 3992 16: 1000 14794 4861 17:  18:  19: Concurrent Dictionary 20: --------------------------------------------------- 21: Accessors Mostly Misses Mostly Hits 22: 1 17443 3726 23: 10 14181 1897 24: 100 15141 1994 25: 1000 17209 2128 The first test I did across the board is the Mostly Misses category.  The mostly misses (more adds because data requested was not in the dictionary) shows an interesting trend.  In both cases the Dictionary with the simple mutex lock is much faster, and the ConcurrentDictionary is the slowest solution.  But this got me thinking, and a little research seemed to confirm it, maybe the ConcurrentDictionary is more optimized to concurrent "gets" than "adds".  So since the ratio of misses to hits were 2 to 1, I decided to reverse that and see the results. So I tweaked the data so that the number of keys were much smaller than the number of iterations to give me about a 2 to 1 ration of hits to misses (twice as likely to already find the item in the cache than to need to add it).  And yes, indeed here we see that the ConcurrentDictionary is indeed faster than the standard Dictionary here.  I have a strong feeling that as the ration of hits-to-misses gets higher and higher these number gets even better as well.  This makes sense since the ConcurrentDictionary is read-optimized. Also note that I tried the tests with capacity and concurrency hints on the ConcurrentDictionary but saw very little improvement, I think this is largely because on the 10,000,000 hit test it quickly ramped up to the correct capacity and concurrency and thus the impact was limited to the first few milliseconds of the run. So what does this tell us?  Well, as in all things, ConcurrentDictionary is not a panacea.  It won't solve all your woes and it shouldn't be the only Dictionary you ever use.  So when should we use each? Use System.Collections.Generic.Dictionary when: You need a single-threaded Dictionary (no locking needed). You need a multi-threaded Dictionary that is loaded only once at creation and never modified (no locking needed). You need a multi-threaded Dictionary to store items where writes are far more prevalent than reads (locking needed). And use System.Collections.Concurrent.ConcurrentDictionary when: You need a multi-threaded Dictionary where the writes are far more prevalent than reads. You need to be able to iterate over the collection without locking it even if its being modified. Both Dictionaries have their strong suits, I have a feeling this is just one where you need to know from design what you hope to use it for and make your decision based on that criteria.

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• CodePlex Daily Summary for Thursday, March 11, 2010

  CodePlex Daily Summary for Thursday, March 11, 2010New ProjectsASP.NET Wiki Control: This ASP.NET user control allows you to embed a very useful wiki directly into your already existing ASP.NET website taking advantage of the popula...BabyLog: Log baby daily activity.buddyHome: buddyHome is a project that can make your home smarter. as good as your buddy. Cloud Community: Cloud Community makes it easier for organizations to have a simple to use community platform. Our mission is to create an easy to use community pl...Community Connectors for Microsoft CRM 4.0: Community Connectors for Microsoft CRM 4.0 allows Microsoft CRM 4.0 customers and partners to monitor and analyze customers’ interaction from their...Console Highlighter: Hightlights Microsoft Windows Command prompt (cmd.exe) by outputting ANSI VT100 Control sequences to color the output. These sequences are not hand...Cornell Store: This is IN NO WAY officially affiliated or related to the Cornell University store. Instead, this is a project that I am doing for a class. Ther...DevUtilities: This project is for creating some utility tools, and they will be useful during the development.DotNetNuke® Skin Maple: A DotNetNuke Design Challenge skin package submitted to the "Personal" category by DyNNamite.co.uk. The package includes 4 color variations and sev...HRNet: HRNetIIS Web Site Monitoring: A software for monitor a particular web site on IIS, even if its IP is sharing between different web site.Iowa Code Camp: The source code for the Iowa Code Camp website.Leonidas: Leonidas is a virtual tutorLunch 'n Learn: The Lunch 'n Learn web application is an open source ASP.NET MVC application that allows you to setup lunch 'n learn presentations for your team, c...MNT Cryptography: A very simple cryptography classMooiNooi MVC2LINQ2SQL Web Databinder: mvc2linq2sql is a databinder for ASP.NET MVC that make able developer to clean bind object from HTML FORMS to Linq entities. Even 1 to N relations ...MoqBot: MoqBot is an auto mocking library for Moq and Ninject.mtExperience1: hoiMvcPager: MvcPager is a free paging component for ASP.NET MVC web application, it exposes a series of extension methods for using in ASP.NET MVC applications...OCal: OCal is based on object calisthenics to identify code smellsPex Custom Arithmetic Solver: Pex Custom Arithmetic Solver contains a collection of meta-heuristic search algorithms. The goal is to improve Pex's code coverage for code involvi...SetControls: Расширеные контролы для ASP.NET приложений. Полная информация ближе к релизу...shadowrage1597: CTC 195 Game Design classSharePoint Team-Mailer: A SharePoint 2007 solution that defines a generic CustomList for sending e-mails to SharePoint Groups.Sql Share: SQL Share is a collaboration tool used within the science to allow database engineers to work tightly with domain scientists.TechCalendar: Tech Events Calendar ASP.NET project.ZLYScript: A very simple script language compiler.New ReleasesALGLIB: ALGLIB 2.4.0: New ALGLIB release contains: improved versions of several linear algebra algorithms: QR decomposition, matrix inversion, condition number estimatio...AmiBroker Plug-Ins with C#: AmiBroker Plug-Ins v0.0.2: Source codes and a binaryAppFabric Caching UI Admin Tool: AppFabric Caching Beta 2 UI Admin Tool: System Requirements:.NET 4.0 RC AppFabric Caching Beta2 Test On:Win 7 (64x)Autodocs - WCF REST Automatic API Documentation Generator: Autodocs.ServiceModel.Web: This archive contains the reference DLL, instructions and license.Compact Plugs & Compact Injection: Compact Injection and Compact Plugs 1.1 Beta: First release of Compact Plugs (CP). The solution includes a simple example project of CP, called "TestCompactPlugs1". Also some fixes where made ...Console Highlighter: Console Highlighter 0.9 (preview release): Preliminary release.Encrypted Notes: Encrypted Notes 1.3: This is the latest version of Encrypted Notes (1.3). It has an installer - it will create a directory 'CPascoe' in My Documents. The last one was ...Family Tree Analyzer: Version 1.0.2: Family Tree Analyzer Version 1.0.2 This early beta version implements loading a gedcom file and displaying some basic reports. These reports inclu...FRC1103 - FRC Dashboard viewer: 2010 Documentation v0.1: This is my current version of the control system documentation for 2010. It isn't complete, but it has the information required for a custom dashbo...jQuery.cssLess: jQuery.cssLess 0.5 (Even less release): NEW - support for nested special CSS classes (like :hover) MAIN RELEASE This release, code "Even less", is the one that will interpret cssLess wit...MooiNooi MVC2LINQ2SQL Web Databinder: MooiNooi MVC2LINQ2SQL DataBinder: I didn't try this... I just took it off from my project. Please, tell me any problem implementing in your own development and I'll be pleased to h...MvcPager: MvcPager 1.2 for ASP.NET MVC 1.0: MvcPager 1.2 for ASP.NET MVC 1.0Mytrip.Mvc: Mytrip 1.0 preview 1: Article Manager Blog Manager L2S Membership(.NET Framework 3.5) EF Membership(.NET Framework 4) User Manager File Manager Localization Captcha ...NodeXL: Network Overview, Discovery and Exploration for Excel: NodeXL Excel 2007 Template, version 1.0.1.117: The NodeXL Excel 2007 template displays a network graph using edge and vertex lists stored in an Excel 2007 workbook. What's NewThis version adds ...Pex Custom Arithmetic Solver: PexCustomArithmeticSolver: This is the alpha release containing the Alternating Variable Method and Evolution Strategies to try and solve constraints over floating point vari...Scrum Sprint Monitor: v1.0.0.44877: What is new in this release? Major performance increase in animations (up to 50 fps from 2 fps) by replacing DropShadow effect with png bitmaps; ...sELedit: sELedit v1.0b: + Added support for empty strings / wstrings + Fixed: critical bug in configuration files (list 53)sPWadmin: pwAdmin v0.9_nightly: + Fixed: XML editor can now open and save character templates + Added: PWI item name database + Added: Plugin SupportTechCalendar: Events Calendar v.1.0: Initial release.The Silverlight Hyper Video Player [http://slhvp.com]: Beta 2: Beta 2.0 Some fixes from Beta 1, and a couple small enhancements. Intensive testing continues, and I will continue to update the code at least ever...ThreadSafe.Caching: 2010.03.10.1: Updates to the scavanging behaviour since last release. Scavenging will now occur every 30 seconds by default and all objects in the cache will be ...VCC: Latest build, v2.1.30310.0: Automatic drop of latest buildVisual Studio DSite: Email Sender (C++): The same Email Sender program that I but made in visual c plus plus 2008 instead of visual basic 2008.Web Forms MVP: Web Forms MVP CTP7: The release can be considered stable, and is in use behind several high traffic, public websites. It has been marked as a CTP release as it is not ...White Tiger: 0.0.3.1: Now you can load or create files with whatever root element you want *check f or sets file permisionsMost Popular ProjectsMetaSharpWBFS ManagerRawrAJAX Control ToolkitMicrosoft SQL Server Product Samples: DatabaseSilverlight ToolkitWindows Presentation Foundation (WPF)ASP.NETMicrosoft SQL Server Community & SamplesASP.NET Ajax LibraryMost Active ProjectsUmbraco CMSRawrSDS: Scientific DataSet library and toolsN2 CMSFasterflect - A Fast and Simple Reflection APIjQuery Library for SharePoint Web ServicesBlogEngine.NETFarseer Physics Enginepatterns & practices – Enterprise LibraryCaliburn: An Application Framework for WPF and Silverlight

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• Is Berkeley DB a NoSQL solution?

  - by Gregory Burd

  Berkeley DB is a library. To use it to store data you must link the library into your application. You can use most programming languages to access the API, the calls across these APIs generally mimic the Berkeley DB C-API which makes perfect sense because Berkeley DB is written in C. The inspiration for Berkeley DB was the DBM library, a part of the earliest versions of UNIX written by AT&T's Ken Thompson in 1979. DBM was a simple key/value hashtable-based storage library. In the early 1990s as BSD UNIX was transitioning from version 4.3 to 4.4 and retrofitting commercial code owned by AT&T with unencumbered code, it was the future founders of Sleepycat Software who wrote libdb (aka Berkeley DB) as the replacement for DBM. The problem it addressed was fast, reliable local key/value storage. At that time databases almost always lived on a single node, even the most sophisticated databases only had simple fail-over two node solutions. If you had a lot of data to store you would choose between the few commercial RDBMS solutions or to write your own custom solution. Berkeley DB took the headache out of the custom approach. These basic market forces inspired other DBM implementations. There was the "New DBM" (ndbm) and the "GNU DBM" (GDBM) and a few others, but the theme was the same. Even today TokyoCabinet calls itself "a modern implementation of DBM" mimicking, and improving on, something first created over thirty years ago. In the mid-1990s, DBM was the name for what you needed if you were looking for fast, reliable local storage. Fast forward to today. What's changed? Systems are connected over fast, very reliable networks. Disks are cheep, fast, and capable of storing huge amounts of data. CPUs continued to follow Moore's Law, processing power that filled a room in 1990 now fits in your pocket. PCs, servers, and other computers proliferated both in business and the personal markets. In addition to the new hardware entire markets, social systems, and new modes of interpersonal communication moved onto the web and started evolving rapidly. These changes cause a massive explosion of data and a need to analyze and understand that data. Taken together this resulted in an entirely different landscape for database storage, new solutions were needed. A number of novel solutions stepped up and eventually a category called NoSQL emerged. The new market forces inspired the CAP theorem and the heated debate of BASE vs. ACID. But in essence this was simply the market looking at what to trade off to meet these new demands. These new database systems shared many qualities in common. There were designed to address massive amounts of data, millions of requests per second, and scale out across multiple systems. The first large-scale and successful solution was Dynamo, Amazon's distributed key/value database. Dynamo essentially took the next logical step and added a twist. Dynamo was to be the database of record, it would be distributed, data would be partitioned across many nodes, and it would tolerate failure by avoiding single points of failure. Amazon did this because they recognized that the majority of the dynamic content they provided to customers visiting their web store front didn't require the services of an RDBMS. The queries were simple, key/value look-ups or simple range queries with only a few queries that required more complex joins. They set about to use relational technology only in places where it was the best solution for the task, places like accounting and order fulfillment, but not in the myriad of other situations. The success of Dynamo, and it's design, inspired the next generation of Non-SQL, distributed database solutions including Cassandra, Riak and Voldemort. The problem their designers set out to solve was, "reliability at massive scale" so the first focal point was distributed database algorithms. Underneath Dynamo there is a local transactional database; either Berkeley DB, Berkeley DB Java Edition, MySQL or an in-memory key/value data structure. Dynamo was an evolution of local key/value storage onto networks. Cassandra, Riak, and Voldemort all faced similar design decisions and one, Voldemort, choose Berkeley DB Java Edition for it's node-local storage. Riak at first was entirely in-memory, but has recently added write-once, append-only log-based on-disk storage similar type of storage as Berkeley DB except that it is based on a hash table which must reside entirely in-memory rather than a btree which can live in-memory or on disk. Berkeley DB evolved too, we added high availability (HA) and a replication manager that makes it easy to setup replica groups. Berkeley DB's replication doesn't partitioned the data, every node keeps an entire copy of the database. For consistency, there is a single node where writes are committed first - a master - then those changes are delivered to the replica nodes as log records. Applications can choose to wait until all nodes are consistent, or fire and forget allowing Berkeley DB to eventually become consistent. Berkeley DB's HA scales-out quite well for read-intensive applications and also effectively eliminates the central point of failure by allowing replica nodes to be elected (using a PAXOS algorithm) to mastership if the master should fail. This implementation covers a wide variety of use cases. MemcacheDB is a server that implements the Memcache network protocol but uses Berkeley DB for storage and HA to replicate the cache state across all the nodes in the cache group. Google Accounts, the user authentication layer for all Google properties, was until recently running Berkeley DB HA. That scaled to a globally distributed system. That said, most NoSQL solutions try to partition (shard) data across nodes in the replication group and some allow writes as well as reads at any node, Berkeley DB HA does not. So, is Berkeley DB a "NoSQL" solution? Not really, but it certainly is a component of many of the existing NoSQL solutions out there. Forgetting all the noise about how NoSQL solutions are complex distributed databases when you boil them down to a single node you still have to store the data to some form of stable local storage. DBMs solved that problem a long time ago. NoSQL has more to do with the layers on top of the DBM; the distributed, sometimes-consistent, partitioned, scale-out storage that manage key/value or document sets and generally have some form of simple HTTP/REST-style network API. Does Berkeley DB do that? Not really. Is Berkeley DB a "NoSQL" solution today? Nope, but it's the most robust solution on which to build such a system. Re-inventing the node-local data storage isn't easy. A lot of people are starting to come to appreciate the sophisticated features found in Berkeley DB, even mimic them in some cases. Could Berkeley DB grow into a NoSQL solution? Absolutely. Our key/value API could be extended over the net using any of a number of existing network protocols such as memcache or HTTP/REST. We could adapt our node-local data partitioning out over replicated nodes. We even have a nice query language and cost-based query optimizer in our BDB XML product that we could reuse were we to build out a document-based NoSQL-style product. XML and JSON are not so different that we couldn't adapt one to work with the other interchangeably. Without too much effort we could add what's missing, we could jump into this No SQL market withing a single product development cycle. Why isn't Berkeley DB already a NoSQL solution? Why aren't we working on it? Why indeed...

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• Using Table-Valued Parameters in SQL Server

  - by Jesse

  I work with stored procedures in SQL Server pretty frequently and have often found myself with a need to pass in a list of values at run-time. Quite often this list contains a set of ids on which the stored procedure needs to operate the size and contents of which are not known at design time. In the past I’ve taken the collection of ids (which are usually integers), converted them to a string representation where each value is separated by a comma and passed that string into a VARCHAR parameter of a stored procedure. The body of the stored procedure would then need to parse that string into a table variable which could be easily consumed with set-based logic within the rest of the stored procedure. This approach works pretty well but the VARCHAR variable has always felt like an un-wanted “middle man” in this scenario. Of course, I could use a BULK INSERT operation to load the list of ids into a temporary table that the stored procedure could use, but that approach seems heavy-handed in situations where the list of values is usually going to contain only a few dozen values. Fortunately SQL Server 2008 introduced the concept of table-valued parameters which effectively eliminates the need for the clumsy middle man VARCHAR parameter. Example: Customer Transaction Summary Report Let’s say we have a report that can summarize the the transactions that we’ve conducted with customers over a period of time. The report returns a pretty simple dataset containing one row per customer with some key metrics about how much business that customer has conducted over the date range for which the report is being run. Sometimes the report is run for a single customer, sometimes it’s run for all customers, and sometimes it’s run for a handful of customers (i.e. a salesman runs it for the customers that fall into his sales territory). This report can be invoked from a website on-demand, or it can be scheduled for periodic delivery to certain users via SQL Server Reporting Services. Because the report can be created from different places and the query to generate the report is complex it’s been packed into a stored procedure that accepts three parameters: @startDate – The beginning of the date range for which the report should be run. @endDate – The end of the date range for which the report should be run. @customerIds – The customer Ids for which the report should be run. Obviously, the @startDate and @endDate parameters are DATETIME variables. The @customerIds parameter, however, needs to contain a list of the identity values (primary key) from the Customers table representing the customers that were selected for this particular run of the report. In prior versions of SQL Server we might have made this parameter a VARCHAR variable, but with SQL Server 2008 we can make it into a table-valued parameter. Defining And Using The Table Type In order to use a table-valued parameter, we first need to tell SQL Server about what the table will look like. We do this by creating a user defined type. For the purposes of this stored procedure we need a very simple type to model a table variable with a single integer column. We can create a generic type called ‘IntegerListTableType’ like this: CREATE TYPE IntegerListTableType AS TABLE (Value INT NOT NULL) Once defined, we can use this new type to define the @customerIds parameter in the signature of our stored procedure. The parameter list for the stored procedure definition might look like: 1: CREATE PROCEDURE dbo.rpt_CustomerTransactionSummary 2: @starDate datetime, 3: @endDate datetime, 4: @customerIds IntegerListTableTableType READONLY   Note the ‘READONLY’ statement following the declaration of the @customerIds parameter. SQL Server requires any table-valued parameter be marked as ‘READONLY’ and no DML (INSERT/UPDATE/DELETE) statements can be performed on a table-valued parameter within the routine in which it’s used. Aside from the DML restriction, however, you can do pretty much anything with a table-valued parameter as you could with a normal TABLE variable. With the user defined type and stored procedure defined as above, we could invoke like this: 1: DECLARE @cusomterIdList IntegerListTableType 2: INSERT @customerIdList VALUES (1) 3: INSERT @customerIdList VALUES (2) 4: INSERT @customerIdList VALUES (3) 5:  6: EXEC dbo.rpt_CustomerTransationSummary 7: @startDate = '2012-05-01', 8: @endDate = '2012-06-01' 9: @customerIds = @customerIdList   Note that we can simply declare a variable of type ‘IntegerListTableType’ just like any other normal variable and insert values into it just like a TABLE variable. We could also populate the variable with a SELECT … INTO or INSERT … SELECT statement if desired. Using The Table-Valued Parameter With ADO .NET Invoking a stored procedure with a table-valued parameter from ADO .NET is as simple as building a DataTable and passing it in as the Value of a SqlParameter. Here’s some example code for how we would construct the SqlParameter for the @customerIds parameter in our stored procedure: 1: var customerIdsParameter = new SqlParameter(); 2: customerIdParameter.Direction = ParameterDirection.Input; 3: customerIdParameter.TypeName = "IntegerListTableType"; 4: customerIdParameter.Value = selectedCustomerIds.ToIntegerListDataTable("Value");   All we’re doing here is new’ing up an instance of SqlParameter, setting the pamameters direction, specifying the name of the User Defined Type that this parameter uses, and setting its value. We’re assuming here that we have an IEnumerable<int> variable called ‘selectedCustomerIds’ containing all of the customer Ids for which the report should be run. The ‘ToIntegerListDataTable’ method is an extension method of the IEnumerable<int> type that looks like this: 1: public static DataTable ToIntegerListDataTable(this IEnumerable<int> intValues, string columnName) 2: { 3: var intergerListDataTable = new DataTable(); 4: intergerListDataTable.Columns.Add(columnName); 5: foreach(var intValue in intValues) 6: { 7: var nextRow = intergerListDataTable.NewRow(); 8: nextRow[columnName] = intValue; 9: intergerListDataTable.Rows.Add(nextRow); 10: } 11:  12: return intergerListDataTable; 13: }   Since the ‘IntegerListTableType’ has a single int column called ‘Value’, we pass that in for the ‘columnName’ parameter to the extension method. The method creates a new single-columned DataTable using the provided column name then iterates over the items in the IEnumerable<int> instance adding one row for each value. We can then use this SqlParameter instance when invoking the stored procedure just like we would use any other parameter. Advanced Functionality Using passing a list of integers into a stored procedure is a very simple usage scenario for the table-valued parameters feature, but I’ve found that it covers the majority of situations where I’ve needed to pass a collection of data for use in a query at run-time. I should note that BULK INSERT feature still makes sense for passing large amounts of data to SQL Server for processing. MSDN seems to suggest that 1000 rows of data is the tipping point where the overhead of a BULK INSERT operation can pay dividends. I should also note here that table-valued parameters can be used to deal with more complex data structures than single-columned tables of integers. A User Defined Type that backs a table-valued parameter can use things like identities and computed columns. That said, using some of these more advanced features might require the use the SqlDataRecord and SqlMetaData classes instead of a simple DataTable. Erland Sommarskog has a great article on his website that describes when and how to use these classes for table-valued parameters. What About Reporting Services? Earlier in the post I referenced the fact that our example stored procedure would be called from both a web application and a SQL Server Reporting Services report. Unfortunately, using table-valued parameters from SSRS reports can be a bit tricky and warrants its own blog post which I’ll be putting together and posting sometime in the near future.

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• SQL SERVER – Weekly Series – Memory Lane – #052

  - by Pinal Dave

  Let us continue with the final episode of the Memory Lane Series. Here is the list of selected articles of SQLAuthority.com across all these years. Instead of just listing all the articles I have selected a few of my most favorite articles and have listed them here with additional notes below it. Let me know which one of the following is your favorite article from memory lane. 2007 Set Server Level FILLFACTOR Using T-SQL Script Specifies a percentage that indicates how full the Database Engine should make the leaf level of each index page during index creation or alteration. fillfactor must be an integer value from 1 to 100. The default is 0. Limitation of Online Index Rebuld Operation Online operation means when online operations are happening in the database are in normal operational condition, the processes which are participating in online operations does not require exclusive access to the database. Get Permissions of My Username / Userlogin on Server / Database A few days ago, I was invited to one of the largest database company. I was asked to review database schema and propose changes to it. There was special username or user logic was created for me, so I can review their database. I was very much interested to know what kind of permissions I was assigned per server level and database level. I did not feel like asking Sr. DBA the question about permissions. Simple Example of WHILE Loop With CONTINUE and BREAK Keywords This question is one of those questions which is very simple and most of the users get it correct, however few users find it confusing for the first time. I have tried to explain the usage of simple WHILE loop in the first example. BREAK keyword will exit the stop the while loop and control is moved to the next statement after the while loop. CONTINUE keyword skips all the statement after its execution and control is sent to the first statement of while loop. Forced Parameterization and Simple Parameterization – T-SQL and SSMS When the PARAMETERIZATION option is set to FORCED, any literal value that appears in a SELECT, INSERT, UPDATE or DELETE statement is converted to a parameter during query compilation. When the PARAMETERIZATION database option is SET to SIMPLE, the SQL Server query optimizer may choose to parameterize the queries. 2008 Transaction and Local Variables – Swap Variables – Update All At Once Concept Summary : Transaction have no effect over memory variables. When UPDATE statement is applied over any table (physical or memory) all the updates are applied at one time together when the statement is committed. First of all I suggest that you read the article listed above about the effect of transaction on local variant. As seen there local variables are independent of any transaction effect. Simulate INNER JOIN using LEFT JOIN statement – Performance Analysis Just a day ago, while I was working with JOINs I find one interesting observation, which has prompted me to create following example. Before we continue further let me make very clear that INNER JOIN should be used where it cannot be used and simulating INNER JOIN using any other JOINs will degrade the performance. If there are scopes to convert any OUTER JOIN to INNER JOIN it should be done with priority. 2009 Introduction to Business Intelligence – Important Terms & Definitions Business intelligence (BI) is a broad category of application programs and technologies for gathering, storing, analyzing, and providing access to data from various data sources, thus providing enterprise users with reliable and timely information and analysis for improved decision making. Difference Between Candidate Keys and Primary Key Candidate Key – A Candidate Key can be any column or a combination of columns that can qualify as unique key in database. There can be multiple Candidate Keys in one table. Each Candidate Key can qualify as Primary Key. Primary Key – A Primary Key is a column or a combination of columns that uniquely identify a record. Only one Candidate Key can be Primary Key. 2010 Taking Multiple Backup of Database in Single Command – Mirrored Database Backup I recently had a very interesting experience. In one of my recent consultancy works, I was told by our client that they are going to take the backup of the database and will also a copy of it at the same time. I expressed that it was surely possible if they were going to use a mirror command. In addition, they told me that whenever they take two copies of the database, the size of the database, is always reduced. Now this was something not clear to me, I said it was not possible and so I asked them to show me the script. Corrupted Backup File and Unsuccessful Restore The CTO, who was also present at the location, got very upset with this situation. He then asked when the last successful restore test was done. As expected, the answer was NEVER.There were no successful restore tests done before. During that time, I was present and I could clearly see the stress, confusion, carelessness and anger around me. I did not appreciate the feeling and I was pretty sure that no one in there wanted the atmosphere like me. 2011 TRACEWRITE – Wait Type – Wait Related to Buffer and Resolution SQL Trace is a SQL Server database engine technology which monitors specific events generated when various actions occur in the database engine. When any event is fired it goes through various stages as well various routes. One of the routes is Trace I/O Provider, which sends data to its final destination either as a file or rowset. DATEDIFF – Accuracy of Various Dateparts If you want to have accuracy in seconds, you need to use a different approach. In the first example, the accurate method is to find the number of seconds first and then divide it by 60 to convert it in minutes. Dedicated Access Control for SQL Server Express Edition http://www.youtube.com/watch?v=1k00z82u4OI Book Signing at SQLPASS 2012 Who I Am And How I Got Here – True Story as Blog Post If there was a shortcut to success – I want to know. I learnt SQL Server hard way and I am still learning. There are so many things, I have to learn. There is not enough time to learn everything which we want to learn. I am constantly working on it every day. I welcome you to join my journey as well. Please join me in my journey to learn SQL Server – more the merrier. Vacation, Travel and Study – A New Concept Even those who have advanced degrees and went to college for years, or even decades, find studying hard.  There is a difference between studying for a career and studying for a certification.  At least to get a degree there is a variety of subjects, with labs, exams, and practice problems to make things more interesting. Order By Numeric Values Formatted as String We have a table which has a column containing alphanumeric data. The data always has first as an integer and later part as a string. The business need is to order the data based on the first part of the alphanumeric data which is an integer. Now the problem is that no matter how we use ORDER BY the result is not produced as expected. Let us understand this with an example. Resolving SQL Server Connection Errors – SQL in Sixty Seconds #030 – Video One of the most famous errors related to SQL Server is about connecting to SQL Server itself. Here is how it goes, most of the time developers have worked with SQL Server and knows pretty much every error which they face during development language. However, hardly they install fresh SQL Server. As the installation of the SQL Server is a rare occasion unless you are a DBA who is responsible for such an instance – the error faced during installations are pretty rare as well. http://www.youtube.com/watch?v=1k00z82u4OI Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Memory Lane, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• My Code Kata–A Solution Kata

  - by Glav

  There are many developers and coders out there who like to do code Kata’s to keep their coding ability up to scratch and to practice their skills. I think it is a good idea. While I like the concept, I find them dead boring and of minimal purpose. Yes, they serve to hone your skills but that’s about it. They are often quite abstract, in that they usually focus on a small problem set requiring specific solutions. It is fair enough as that is how they are designed but again, I find them quite boring. What I personally like to do is go for something a little larger and a little more fun. It takes a little more time and is not as easily executed as a kata though, but it services the same purposes from a practice perspective and allows me to continue to solve some problems that are not directly part of the initial goal. This means I can cover a broader learning range and have a bit more fun. If I am lucky, sometimes they even end up being useful tools. With that in mind, I thought I’d share my current ‘kata’. It is not really a code kata as it is too big. I prefer to think of it as a ‘solution kata’. The code is on bitbucket here. What I wanted to do was create a kind of simplistic virtual world where I can create a player, or a class, stuff it into the world, and see if it survives, and can navigate its way to the exit. Requirements were pretty simple: Must be able to define a map to describe the world using simple X,Y co-ordinates. Z co-ordinates as well if you feel like getting clever. Should have the concept of entrances, exists, solid blocks, and potentially other materials (again if you want to get clever). A coder should be able to easily write a class which will act as an inhabitant of the world. An inhabitant will receive stimulus from the world in the form of surrounding environment and be able to make a decision on action which it passes back to the ‘world’ for processing. At a minimum, an inhabitant will have sight and speed characteristics which determine how far they can ‘see’ in the world, and how fast they can move. Coders who write a really bad ‘inhabitant’ should not adversely affect the rest of world. Should allow multiple inhabitants in the world. So that was the solution I set out to act as a practice solution and a little bit of fun. It had some interesting problems to solve and I figured, if it turned out ok, I could potentially use this as a ‘developer test’ for interviews. Ask a potential coder to write a class for an inhabitant. Show the coder the map they will navigate, but also mention that we will use their code to navigate a map they have not yet seen and a little more complex. I have been playing with solution for a short time now and have it working in basic concepts. Below is a screen shot using a very basic console visualiser that shows the map, boundaries, blocks, entrance, exit and players/inhabitants. The yellow asterisks ‘*’ are the players, green ‘O’ the entrance, purple ‘^’ the exit, maroon/browny ‘#’ are solid blocks. The players can move around at different speeds, knock into each others, and make directional movement decisions based on what they see and who is around them. It has been quite fun to write and it is also quite fun to develop different players to inject into the world. The code below shows a really simple implementation of an inhabitant that can work out what to do based on stimulus from the world. It is pretty simple and just tries to move in some direction if there is nothing blocking the path. public class TestPlayer:LivingEntity { public TestPlayer() { Name = "Beta Boy"; LifeKey = Guid.NewGuid(); } public override ActionResult DecideActionToPerform(EcoDev.Core.Common.Actions.ActionContext actionContext) { try { var action = new MovementAction(); // move forward if we can if (actionContext.Position.ForwardFacingPositions.Length > 0) { if (CheckAccessibilityOfMapBlock(actionContext.Position.ForwardFacingPositions[0])) { action.DirectionToMove = MovementDirection.Forward; return action; } } if (actionContext.Position.LeftFacingPositions.Length > 0) { if (CheckAccessibilityOfMapBlock(actionContext.Position.LeftFacingPositions[0])) { action.DirectionToMove = MovementDirection.Left; return action; } } if (actionContext.Position.RearFacingPositions.Length > 0) { if (CheckAccessibilityOfMapBlock(actionContext.Position.RearFacingPositions[0])) { action.DirectionToMove = MovementDirection.Back; return action; } } if (actionContext.Position.RightFacingPositions.Length > 0) { if (CheckAccessibilityOfMapBlock(actionContext.Position.RightFacingPositions[0])) { action.DirectionToMove = MovementDirection.Right; return action; } } return action; } catch (Exception ex) { World.WriteDebugInformation("Player: "+ Name, string.Format("Player Generated exception: {0}",ex.Message)); throw ex; } } private bool CheckAccessibilityOfMapBlock(MapBlock block) { if (block == null || block.Accessibility == MapBlockAccessibility.AllowEntry || block.Accessibility == MapBlockAccessibility.AllowExit || block.Accessibility == MapBlockAccessibility.AllowPotentialEntry) { return true; } return false; } } It is simple and it seems to work well. The world implementation itself decides the stimulus context that is passed to he inhabitant to make an action decision. All movement is carried out on separate threads and timed appropriately to be as fair as possible and to cater for additional skills such as speed, and eventually maybe stamina, strength, with actions like fighting. It is pretty fun to make up random maps and see how your inhabitant does. You can download the code from here. Along the way I have played with parallel extensions to make the compute intensive stuff spread across all cores, had to heavily factor in visibility of methods and properties so design of classes was paramount, work out movement algorithms that play fairly in the world and properly favour the players with higher abilities, as well as a host of other issues. So that is my ‘solution kata’. If I keep going with it, I may develop a web interface for it where people can upload assemblies and watch their player within a web browser visualiser and maybe even a map designer. What do you do to keep the fires burning?

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• Cloud Computing = Elasticity * Availability

  - by Herve Roggero

  What is cloud computing? Is hosting the same thing as cloud computing? Are you running a cloud if you already use virtual machines? What is the difference between Infrastructure as a Service (IaaS) and a cloud provider? And the list goes on… these questions keep coming up and all try to fundamentally explain what “cloud” means relative to other concepts. At the risk of over simplification, answering these questions becomes simpler once you understand the primary foundations of cloud computing: Elasticity and Availability.   Elasticity The basic value proposition of cloud computing is to pay as you go, and to pay for what you use. This implies that an application can expand and contract on demand, across all its tiers (presentation layer, services, database, security…).  This also implies that application components can grow independently from each other. So if you need more storage for your database, you should be able to grow that tier without affecting, reconfiguring or changing the other tiers. Basically, cloud applications behave like a sponge; when you add water to a sponge, it grows in size; in the application world, the more customers you add, the more it grows. Pure IaaS providers will provide certain benefits, specifically in terms of operating costs, but an IaaS provider will not help you in making your applications elastic; neither will Virtual Machines. The smallest elasticity unit of an IaaS provider and a Virtual Machine environment is a server (physical or virtual). While adding servers in a datacenter helps in achieving scale, it is hardly enough. The application has yet to use this hardware.  If the process of adding computing resources is not transparent to the application, the application is not elastic.   As you can see from the above description, designing for the cloud is not about more servers; it is about designing an application for elasticity regardless of the underlying server farm.   Availability The fact of the matter is that making applications highly available is hard. It requires highly specialized tools and trained staff. On top of it, it's expensive. Many companies are required to run multiple data centers due to high availability requirements. In some organizations, some data centers are simply on standby, waiting to be used in a case of a failover. Other organizations are able to achieve a certain level of success with active/active data centers, in which all available data centers serve incoming user requests. While achieving high availability for services is relatively simple, establishing a highly available database farm is far more complex. In fact it is so complex that many companies establish yearly tests to validate failover procedures.   To a certain degree certain IaaS provides can assist with complex disaster recovery planning and setting up data centers that can achieve successful failover. However the burden is still on the corporation to manage and maintain such an environment, including regular hardware and software upgrades. Cloud computing on the other hand removes most of the disaster recovery requirements by hiding many of the underlying complexities.   Cloud Providers A cloud provider is an infrastructure provider offering additional tools to achieve application elasticity and availability that are not usually available on-premise. For example Microsoft Azure provides a simple configuration screen that makes it possible to run 1 or 100 web sites by clicking a button or two on a screen (simplifying provisioning), and soon SQL Azure will offer Data Federation to allow database sharding (which allows you to scale the database tier seamlessly and automatically). Other cloud providers offer certain features that are not available on-premise as well, such as the Amazon SC3 (Simple Storage Service) which gives you virtually unlimited storage capabilities for simple data stores, which is somewhat equivalent to the Microsoft Azure Table offering (offering a server-independent data storage model). Unlike IaaS providers, cloud providers give you the necessary tools to adopt elasticity as part of your application architecture.    Some cloud providers offer built-in high availability that get you out of the business of configuring clustered solutions, or running multiple data centers. Some cloud providers will give you more control (which puts some of that burden back on the customers' shoulder) and others will tend to make high availability totally transparent. For example, SQL Azure provides high availability automatically which would be very difficult to achieve (and very costly) on premise.   Keep in mind that each cloud provider has its strengths and weaknesses; some are better at achieving transparent scalability and server independence than others.    Not for Everyone Note however that it is up to you to leverage the elasticity capabilities of a cloud provider, as discussed previously; if you build a website that does not need to scale, for which elasticity is not important, then you can use a traditional host provider unless you also need high availability. Leveraging the technologies of cloud providers can be difficult and can become a journey for companies that build their solutions in a scale up fashion. Cloud computing promises to address cost containment and scalability of applications with built-in high availability. If your application does not need to scale or you do not need high availability, then cloud computing may not be for you. In fact, you may pay a premium to run your applications with cloud providers due to the underlying technologies built specifically for scalability and availability requirements. And as such, the cloud is not for everyone.   Consistent Customer Experience, Predictable Cost With all its complexities, buzz and foggy definition, cloud computing boils down to a simple objective: consistent customer experience at a predictable cost.  The objective of a cloud solution is to provide the same user experience to your last customer than the first, while keeping your operating costs directly proportional to the number of customers you have. Making your applications elastic and highly available across all its tiers, with as much automation as possible, achieves the first objective of a consistent customer experience. And the ability to expand and contract the infrastructure footprint of your application dynamically achieves the cost containment objectives.     Herve Roggero is a SQL Azure MVP and co-author of Pro SQL Azure (APress).  He is the co-founder of Blue Syntax Consulting (www.bluesyntax.net), a company focusing on cloud computing technologies helping customers understand and adopt cloud computing technologies. For more information contact herve at hroggero @ bluesyntax.net .

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