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  • How To Configure Remote Desktop To Hyper-V Guest Virtual Machines

    - by Brian Jackett
    Configuring Remote Desktop (RDP) from a host Hyper-V machine to a guest virtual machine can be tricky, so this post is dedicated to the issues and resolution steps I went through to allow RDP.  Cutting to the point, below are the things to look for followed by some explanation about my scenario if you care to read.  This is not an exhaustive list of what is required, just the items that were causing problems for my particular scenario. Requirements Allow Remote Desktop Connections in guest OS. The network adapter type must allow communication with host machine (e.g. use an “Internal” virtual adapter.) If running Server 2008 R2 on guest, network discovery mode must be turned on. If running Server 2008 R2 on guest, the services supporting network discovery mode must be running: - DNS Client - Function Discovery Resource Publication - SSDP Discovery - UPnP Device Host My Environment     A quick word about my environment.  I am running Windows Server 2008 R2 with Hyper V on my laptop and numerous guest VMs running Windows Server 2003 R2 or Windows Server 2008 R2.  I run a domain controller VM and then 1 or 2 SharePoint servers depending on my work needs.  I’ve found this setup to work well except when it comes to the display window for my VMs. The Issue     Ever since I began running Hyper-V I haven’t been able to RDP to my guest VMs which means the resolution for my connection windows ha been limited to what the native Hyper-V connections allow.  During personal use I can put the resolution up to 1152 x 864, but during presentations I am usually limited to a measly 800 x 600.  That is until today when I decided to fully investigate why I couldn’t connect via RDP.     First a thank you to John Ross (@johnrossjr), Christina Wheeler (@cwheeler76) and Clayton Cobb (@warrtalon) for various suggestions while I was researching tonight.  As it turns out I had not 1, not 2, but 3 items preventing me from using RDP.  Let’s dig into the requirements above. Allow RDP Connection     This item I had previously taken care of, but it bears repeating because by default Windows Server 2008 R2 does not allow RDP connections.  Change the setting from “Don’t allow…” to whichever “Allow connections…” setting suits your needs.  I chose the less secure option as this is just my dev laptop. Network Adapter Type     When I originally configured my VMs I configured each to use 2 network adapters: one using the physical ethernet adapter for internet use and a virtual private adapter for communication between the VMs.  The connection for the ethernet adapter is an "”External” adapter and thus doesn’t connect between the host and guest.  The virtual private adapter allowed communication ONLY between the VMs and not to my host.  There is a third option “Internal” which allows communication between VMs as well as to the host.  After finding out this distinction I promptly created an Internal network adapter and assigned that to my VMs. Turn On Network Discovery     Seems like a pretty common sense thing, but in order to allow remote desktop connections the target computer must able to be found by the source computer (explained here.)  One of the settings that controls if a computer can be found on the network is aptly named Network Discovery.  By default Windows Server 2008 R2 turns Network Discovery off for security purposes.  To enable it open up the Network and Sharing Center.  Click “Change Advanced Sharing Settings” on the left.  On the following screen select “Turn on network discovery” for the currently used profile and click Save Settings.  You may notice though that your selection to turn on network discovery doesn’t save.  If this is the case then you most likely don’t have the supporting services running (as was my case.) Network Discovery Supporting Services     There are a total of 4 services (listed again below) that need to be running before you can turn on network discovery (explained here.)  The below images highlight these services.  In my guest VM I found that I had DNS Client already running while the other 3 were disabled.  I set them all to enabled and started the ones that were stopped.  After this change I returned to the Sharing settings screen and found that Network Discovery was turned on.  I’m not sure whether this was picking up my attempt to turn it on previously or if starting those services turned it on.  Either way the end result was a success. - DNS Client - Function Discovery Resource Publication - SSDP Discovery - UPnP Device Host Before and After Results     The first image is the smaller square shaped viewing window used by the Hyper-V native connection.  The second is the full-screen RDP connection in all its widescreen glory. Conclusion     Over the past few months I’ve found Hyper-V to be very useful for virtualizing my development environments, but I’ve also had a steep learning curve to get various items configured just right.  Allowing RDP connections to guest VMs was one area that I hadn’t been able to get right for the longest time.  Now that I resolved these issues I hope that others can avoid the pitfalls that I ran into.  If you know of any other items I left off feel free to let me know.        -Frog Out   Links Turning on Network Discovery http://sqlblog.com/blogs/john_paul_cook/archive/2009/08/15/remote-desktop-connection-on-windows-server-2008-r2.aspx Services required for Network Discovery http://social.technet.microsoft.com/Forums/en-US/winservergen/thread/2e1fea01-3f2b-4c46-a631-a8db34ed4f84

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  • A Rose by Any Other Name..

    - by Geoff N. Hiten
    It is always a good start when you can steal a title line from one of the best writers in the English language.  Let’s hope I can make the rest of this post live up to the opening.  One recurring problem with SQL server is moving databases to new servers.  Client applications use a variety of ways to resolve SQL Server names, some of which are not changed easily <cough SharePoint /cough>.  If you happen to be using default instances on both the source and target SQL Server, then the solution is pretty simple.  You create (or bug the network admin until she creates) two DNS “A” records. One points the old name to the new IP address.  The other creates a new alias for the old server, since the original system name is now redirected.  Note this will redirect ALL traffic from the old server to the new server, including RDP and file share connection attempts.    Figure 1 – Microsoft DNS MMC Snap-In   Figure 2 – DNS New Host Dialog Box Both records are necessary so you can still access the old server via an alternate name. Server Role IP Address Name Alias Source 10.97.230.60 SQL01 SQL01_Old Target 10.97.230.80 SQL02 SQL01 Table 1 – Alias List If you or somebody set up connections via IP address, you deserve to have to go to each app and fix it by hand.  That is the only way to fix that particular foul-up. If have to deal with Named Instances either as a source or a target, then it gets more complicated.  The standard fix is to use the SQL Server Configuration Manager (or one of its earlier incarnations) to create a SQL client alias to redirect the connection.  This can be a pain installing and configuring the app on multiple client servers.  The good news is that SQL Server Configuration Manager AND all of its earlier versions simply write a few registry keys.  Extracting the keys into a .reg file makes centralized automated deployment a snap. If the client is a 32-bit system, you have to extract the native key.  If it is a 64-bit, you have to extract the native key and the WoW (32 bit on 64 bit host) key. First, pick a development system to create the actual registry key.  If you do this repeatedly, you can simply edit an existing registry file.  Create the entry using the SQL Configuration Manager.  You must use a 64-bit system to create the WoW key.  The following example redirects from a named instance “SQL01\SQLUtiluty” to a default instance on “SQL02”.   Figure 3 – SQL Server Configuration Manager - Native Figure 3 shows the native key listing. Figure 4 – SQL Server Configuration Manager – WoW If you think you don’t need the WoW key because your app is 64 it, think again.  SQL Server Management Server is a 32-bit app, as are most SQL test utilities.  Always create both keys for 64-bit target systems. Now that the keys exist, we can extract them into a .reg file. Fire up REGEDIT and browse to the following location:  HKLM\Software\Microsoft\MSSQLServer\Client\ConnectTo.  You can also search the registry for the string value of one of the server names (old or new). Right click on the “ConnectTo” label and choose “Export”.  Save with an appropriate name and location.  The resulting file should look something like this: Figure 5 – SQL01_Alias.reg Repeat the process with the location: HKLM\Software\Wow6432Node\Microsoft\MSSQLServer\Client\ConnectTo Note that if you have multiple alias entries, ALL of the entries will be exported.  In that case, you can edit the file and remove the extra aliases. You can edit the files together into a single file.  Just leave a blank line between new keys like this: Figure 6 – SQL01_Alias_All.reg Of course if you have an automatic way to deploy, it makes sense to have an automatic way to Un-deploy.  To delete a registry key, simply edit the .reg file and replace the target with a “-“ sign like so. Figure 7 – SQL01_Alias_UNDO.reg Now we have the ability to move any database to any server without having to install or change any applications on any client server.  The whole process should be transparent to the applications, which makes planning and coordinating database moves a far simpler task.

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  • Wireless Problem on Acer Aspire 5610z

    - by Ugur Can Yalaki
    I installed ubuntu 12.04 on my machine, but I can't get wireless connection to work. My computer is Acer Aspire 5610z. I found that some other people that have same computer, face the same problem. Here is some information about it: ****** info trace ****** * uname -a * Linux ucy-Aspire-5610Z 3.8.0-32-generic #47~precise1-Ubuntu SMP Wed Oct 2 16:22:28 UTC 2013 i686 i686 i386 GNU/Linux * lsb_release * Distributor ID: Ubuntu Description: Ubuntu 12.04.3 LTS Release: 12.04 Codename: precise * lspci * 05:00.0 Network controller [0280]: Broadcom Corporation BCM4311 802.11b/g WLAN [14e4:4311] (rev 01) Subsystem: AMBIT Microsystem Corp. Device [1468:0422] Kernel driver in use: b43-pci-bridge 06:01.0 Ethernet controller [0200]: Broadcom Corporation BCM4401-B0 100Base-TX [14e4:170c] (rev 02) Subsystem: Acer Incorporated [ALI] Device [1025:0090] Kernel driver in use: b44 * lsusb * Bus 001 Device 004: ID 04e8:6863 Samsung Electronics Co., Ltd Bus 001 Device 002: ID 5986:0100 Acer, Inc Orbicam Bus 002 Device 002: ID 046d:c52f Logitech, Inc. Wireless Mouse M305 Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 005 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub * PCMCIA Card Info * PRODID_1="" PRODID_2="" PRODID_3="" PRODID_4="" MANFID=0000,0000 FUNCID=255 * iwconfig * * rfkill * 0: acer-wireless: Wireless LAN Soft blocked: no Hard blocked: no * lsmod * ssb_hcd 12781 0 ssb 51554 2 ssb_hcd,b44 * nm-tool * NetworkManager Tool State: connected (global) Device: usb0 [Wired connection 2] ------------------------------------------- Type: Wired Driver: rndis_host State: connected Default: yes HW Address: Capabilities: Carrier Detect: yes Wired Properties Carrier: on IPv4 Settings: Address: 192.168.42.7 Prefix: 24 (255.255.255.0) Gateway: 192.168.42.129 DNS: 192.168.42.129 IPv6 Settings: Address: ::a05d:a1ff:fea4:1738 Prefix: 64 Gateway: fe80::504d:76ff:fe86:db04 Address: fe80::a05d:a1ff:fea4:1738 Prefix: 64 Gateway: fe80::504d:76ff:fe86:db04 DNS: fe80::504d:76ff:fe86:db04 Device: eth2 ----------------------------------------------------------------- Type: Wired Driver: b44 State: unavailable Default: no HW Address: Capabilities: Carrier Detect: yes Wired Properties Carrier: off * NetworkManager.state * [main] NetworkingEnabled=true WirelessEnabled=true WWANEnabled=true WimaxEnabled=true * NetworkManager.conf * [main] plugins=ifupdown,keyfile dns=dnsmasq [ifupdown] managed=false * interfaces * auto lo iface lo inet loopback * iwlist * * resolv.conf * nameserver 127.0.0.1 * blacklist * [/etc/modprobe.d/blacklist-ath_pci.conf] blacklist ath_pci [/etc/modprobe.d/blacklist-bcm43.conf] blacklist b43 blacklist b43legacy blacklist ssb blacklist bcm43xx blacklist brcm80211 blacklist brcmfmac blacklist brcmsmac blacklist bcma [/etc/modprobe.d/blacklist.conf] blacklist evbug blacklist usbmouse blacklist usbkbd blacklist eepro100 blacklist de4x5 blacklist eth1394 blacklist snd_intel8x0m blacklist snd_aw2 blacklist i2c_i801 blacklist prism54 blacklist bcm43xx blacklist garmin_gps blacklist asus_acpi blacklist snd_pcsp blacklist pcspkr blacklist amd76x_edac * modinfo * filename: /lib/modules/3.8.0-32-generic/kernel/drivers/usb/host/ssb-hcd.ko license: GPL description: Common USB driver for SSB Bus author: Hauke Mehrtens srcversion: E127A51EDC8F44D2C2A8F15 alias: ssb:v4243id0819rev* alias: ssb:v4243id0817rev* alias: ssb:v4243id0808rev* depends: ssb intree: Y vermagic: 3.8.0-32-generic SMP mod_unload modversions 686 filename: /lib/modules/3.8.0-32-generic/kernel/drivers/ssb/ssb.ko license: GPL description: Sonics Silicon Backplane driver srcversion: 14621F6EC014F731244437C alias: pci:v000014E4d00004350sv*sd*bc*sc*i* alias: pci:v000014E4d0000432Csv*sd*bc*sc*i* alias: pci:v000014E4d0000432Bsv*sd*bc*sc*i* alias: pci:v000014E4d00004329sv*sd*bc*sc*i* alias: pci:v000014E4d00004328sv*sd*bc*sc*i* alias: pci:v000014E4d00004325sv*sd*bc*sc*i* alias: pci:v000014E4d00004324sv*sd*bc*sc*i* alias: pci:v000014E4d0000A8D6sv*sd*bc*sc*i* alias: pci:v000014E4d00004322sv*sd*bc*sc*i* alias: pci:v000014E4d00004321sv*sd*bc*sc*i* alias: pci:v000014E4d00004320sv*sd*bc*sc*i* alias: pci:v000014E4d00004319sv*sd*bc*sc*i* alias: pci:v000014A4d00004318sv*sd*bc*sc*i* alias: pci:v000014E4d00004318sv*sd*bc*sc*i* alias: pci:v000014E4d00004315sv*sd*bc*sc*i* alias: pci:v000014E4d00004312sv*sd*bc*sc*i* alias: pci:v000014E4d00004311sv*sd*bc*sc*i* alias: pci:v000014E4d00004307sv*sd*bc*sc*i* alias: pci:v000014E4d00004306sv*sd*bc*sc*i* alias: pci:v000014E4d00004301sv*sd*bc*sc*i* depends: intree: Y vermagic: 3.8.0-32-generic SMP mod_unload modversions 686 * udev rules * PCI device 0x14e4:/sys/devices/pci0000:00/0000:00:1e.0/0000:06:01.0/ssb1:0 (b44) SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="", ATTR{dev_id}=="0x0", ATTR{type}=="1", KERNEL=="eth*", NAME="eth0" PCI device 0x14e4:/sys/devices/pci0000:00/0000:00:1e.0/0000:06:01.0/ssb2:0 (b44) SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="", ATTR{dev_id}=="0x0", ATTR{type}=="1", KERNEL=="eth*", NAME="eth1" PCI device 0x14e4:/sys/devices/pci0000:00/0000:00:1e.0/0000:06:01.0/ssb3:0 (b44) SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="", ATTR{dev_id}=="0x0", ATTR{type}=="1", KERNEL=="eth*", NAME="eth2" * dmesg * [ 2.385241] ssb: Found chip with id 0x4311, rev 0x01 and package 0x00 [ 2.385256] ssb: Core 0 found: ChipCommon (cc 0x800, rev 0x11, vendor 0x4243) [ 2.385266] ssb: Core 1 found: IEEE 802.11 (cc 0x812, rev 0x0A, vendor 0x4243) [ 2.385276] ssb: Core 2 found: USB 1.1 Host (cc 0x817, rev 0x03, vendor 0x4243) [ 2.385286] ssb: Core 3 found: PCI-E (cc 0x820, rev 0x01, vendor 0x4243) [ 2.448147] ssb: Sonics Silicon Backplane found on PCI device 0000:05:00.0 [ 2.468112] ssb: Found chip with id 0x4401, rev 0x02 and package 0x00 [ 2.468124] ssb: Core 0 found: Fast Ethernet (cc 0x806, rev 0x07, vendor 0x4243) [ 2.468132] ssb: Core 1 found: V90 (cc 0x807, rev 0x03, vendor 0x4243) [ 2.468140] ssb: Core 2 found: PCI (cc 0x804, rev 0x0A, vendor 0x4243) [ 2.508230] ssb: Sonics Silicon Backplane found on PCI device 0000:06:01.0 [ 2.528620] b44 ssb1:0 eth0: Broadcom 44xx/47xx 10/100 PCI ethernet driver ******** done ******** Thank you already for your help.

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  • Running a Mongo Replica Set on Azure VM Roles

    - by Elton Stoneman
    Originally posted on: http://geekswithblogs.net/EltonStoneman/archive/2013/10/15/running-a-mongo-replica-set-on-azure-vm-roles.aspxSetting up a MongoDB Replica Set with a bunch of Azure VMs is straightforward stuff. Here’s a step-by-step which gets you from 0 to fully-redundant 3-node document database in about 30 minutes (most of which will be spent waiting for VMs to fire up). First, create yourself 3 VM roles, which is the minimum number of nodes you need for high availability. You can use any OS that Mongo supports. This guide uses Windows but the only difference will be the mechanism for starting the Mongo service when the VM starts (Windows Service, daemon etc.) While the VMs are provisioning, download and install Mongo locally, so you can set up the replica set with the Mongo shell. We’ll create our replica set from scratch, doing one machine at a time (if you have a single node you want to upgrade to a replica set, it’s the same from step 3 onwards): 1. Setup Mongo Log into the first node, download mongo and unzip it to C:. Rename the folder to remove the version – so you have c:\MongoDB\bin etc. – and create a new folder for the logs, c:\MongoDB\logs. 2. Setup your data disk When you initialize a node in a replica set, Mongo pre-allocates a whole chunk of storage to use for data replication. It will use up to 5% of your data disk, so if you use a Windows VM image with a defsault 120Gb disk and host your data on C:, then Mongo will allocate 6Gb for replication. And that takes a while. Instead you can create yourself a new partition by shrinking down the C: drive in Computer Management, by say 10Gb, and then creating a new logical disk for your data from that spare 10Gb, which will be allocated as E:. Create a new folder, e:\data. 3. Start Mongo When that’s done, start a command line, point to the mongo binaries folder, install Mongo as a Windows Service, running in replica set mode, and start the service: cd c:\mongodb\bin mongod -logpath c:\mongodb\logs\mongod.log -dbpath e:\data -replSet TheReplicaSet –install net start mongodb 4. Open the ports Mongo uses port 27017 by default, so you need to allow access in the machine and in Azure. In the VM, open Windows Firewall and create a new inbound rule to allow access via port 27017. Then in the Azure Management Console for the VM role, under the Configure tab add a new rule, again to allow port 27017. 5. Initialise the replica set Start up your local mongo shell, connecting to your Azure VM, and initiate the replica set: c:\mongodb\bin\mongo sc-xyz-db1.cloudapp.net rs.initiate() This is the bit where the new node (at this point the only node) allocates its replication files, so if your data disk is large, this can take a long time (if you’re using the default C: drive with 120Gb, it may take so long that rs.initiate() never responds. If you’re sat waiting more than 20 minutes, start another instance of the mongo shell pointing to the same machine to check on it). Run rs.conf() and you should see one node configured. 6. Fix the host name for the primary – *don’t miss this one* For the first node in the replica set, Mongo on Windows doesn’t populate the full machine name. Run rs.conf() and the name of the primary is sc-xyz-db1, which isn’t accessible to the outside world. The replica set configuration needs the full DNS name of every node, so you need to manually rename it in your shell, which you can do like this: cfg = rs.conf() cfg.members[0].host = ‘sc-xyz-db1.cloudapp.net:27017’ rs.reconfig(cfg) When that returns, rs.conf() will have your full DNS name for the primary, and the other nodes will be able to connect. At this point you have a working database, so you can start adding documents, but there’s no replication yet. 7. Add more nodes For the next two VMs, follow steps 1 through to 4, which will give you a working Mongo database on each node, which you can add to the replica set from the shell with rs.add(), using the full DNS name of the new node and the port you’re using: rs.add(‘sc-xyz-db2.cloudapp.net:27017’) Run rs.status() and you’ll see your new node in STARTUP2 state, which means its initializing and replicating from the PRIMARY. Repeat for your third node: rs.add(‘sc-xyz-db3.cloudapp.net:27017’) When all nodes are finished initializing, you will have a PRIMARY and two SECONDARY nodes showing in rs.status(). Now you have high availability, so you can happily stop db1, and one of the other nodes will become the PRIMARY with no loss of data or service. Note – the process for AWS EC2 is exactly the same, but with one important difference. On the Azure Windows Server 2012 base image, the MongoDB release for 64-bit 2008R2+ works fine, but on the base 2012 AMI that release keeps failing with a UAC permission error. The standard 64-bit release is fine, but it lacks some optimizations that are in the 2008R2+ version.

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  • Challenge 19 – An Explanation of a Query

    - by Dave Ballantyne
    I have received a number of requests for an explanation of my winning query of TSQL Challenge 19. This involved traversing a hierarchy of employees and rolling a count of orders from subordinates up to superiors. The first concept I shall address is the hierarchyId , which is constructed within the CTE called cteTree.   cteTree is a recursive cte that will expand the parent-child hierarchy of the personnel in the table @emp.  One useful feature with a recursive cte is that data can be ‘passed’ from the parent to the child data.  The hierarchyId column is similar to the hierarchyId data type that was introduced in SQL Server 2008 and represents the position of the person within the organisation. Let us start with a simplistic example Albert manages Bob and Eddie.  Bob manages Carl and Dave. The hierarchyId will represent each person’s position in this relationship in a single field.  In this simple example we could append the userID together into a varchar field as detailed below. This will enable us to select a branch of the tree by filtering using Where hierarchyId  ‘1,2%’ to select Bob and all his subordinates.  Naturally, this is not comprehensive enough to provide a full solution, but as opposed to concatenating the Id’s together into a varchar datatyped column, we can apply the same theory to a varbinary.  By CASTing the ID’s into a datatype of varbinary(4) ,4 is used as 4 bytes of data are used to store an integer and building a hierarchyId  from those.  For example: The important point to bear in mind for later in the query is that the binary data generated is 'byte order comparable'. ie We can ORDER a dataset with it and the resulting data, will be in the order required. Now, would probably be a good time to download the example file and, after the cte ‘cteTree’, uncomment the line ‘select * from cteTree’.  Mark this and all prior code and execute.  This will show you how this theory directly relates to the actual challenge data.  The only deviation from the above, is that instead of using the ID of an employee, I have used the row_number() ranking function to order each level by LastName,Firstname.  This enables me to order by the HierarchyId in the final result set so that the result set is in the required order. Your output should be something like the below.  Notice also the ‘Level’ Column that contains the depth that the employee is within the tree.  I would encourage you to ‘play’ with the query, change the order in the row_number() or the length of the cast in the hierarchyId to see how that effects the outcome.  The next cte, ‘cteTreeWithOrderCount’, is a join between cteTree and the @ord table, and COUNT’s the number of orders per employee.  A LEFT JOIN is employed here to account for the occasion where an employee has made no sales.   Executing a ‘Select * from cteTreeWithOrderCount’ will return the result set as below.  The order here is unimportant as this is only a staging point of the data and only the final result set in a cte chain needs an Order by clause, unless TOP is utilised. cteExplode joins the above result set to the tally table (Nums) for Level Occurances.  So, if level is 2 then 2 rows are required.  This is done to expand the dataset, to create a new column (PathInc), which is the (n+1) integers contained within the heirarchyid.  For example, with the data for Robert King as given above, the below 3 rows will be returned. From this you can see that the pathinc column now contains the values for Andrew Fuller and Steven Buchanan who are Robert King’s superiors within the tree.    Finally cteSumUp, sums the orders for each person and their subordinates using the PathInc generated above, and the final select does the final simple mathematics and filters to restrict the result set to only the ‘original’ row per employee.

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  • F# in ASP.NET, mathematics and testing

    - by DigiMortal
    Starting from Visual Studio 2010 F# is full member of .NET Framework languages family. It is functional language with syntax specific to functional languages but I think it is time for us also notice and study functional languages. In this posting I will show you some examples about cool things other people have done using F#. F# and ASP.NET As I am ASP/ASP.NET MVP I am – of course – interested in how people use different languages and technologies with ASP.NET. C# MVP Tomáš Petrícek writes about developing ASP.NET MVC applications using F#. He also shows how to use LINQ To SQL in F# (using F# PowerPack) and provides sample solution and Visual Studio 2010 template for F# MVC web applications. You may also find interesting how you can create controllers in F#. Excellent work, Tomáš! Vladimir Matveev has interesting example about how to use F# and ApplicationHost class to process ASP.NET requests ouside of IIS. This is simple and very straight-forward example and I strongly suggest you to take a look at it. Very cool example is project Strom in Codeplex. Storm is web services testing tool that is fully written on F#. Take a look at this site because Codeplex offers also source code besides binaries. Math Functional languages are strong in fields like mathematics and physics. When I wrote my C# example about BigInteger class I found out that recursive version of Fibonacci algorithm in C# is not performing well. In same time I made same experiment on F# and in F# there were no performance problems with recursive version. You can find F# version of Fibonacci algorithm from Bob Palmer’s blog posting Fibonacci numbers in F#. Although golden spiral is useful for solving many problems I looked for some practical code example and found one. Kean Walmsley published in his Through the Interface blog very interesting posting Creating Fibonacci spirals in AutoCAD using F#. There are also other cool examples you may be interested in. Using numerical components by Extreme Optimization  it is possible to make some numerical integration (quadrature method) using F# (also C# example is available). fsharp.it introduces factorials calculation on F#. Robert Pickering has made very good work on programming The Game of Life in Silverlight and F# – I definitely suggest you to try out this example as it is very illustrative too. Who wants something more complex may take a look at Newton basin fractal example in F# by Jonathan Birge. Testing After some searching and surfing I found out that there is almost everything available for F# to write tests and test your F# code. FsCheck - FsCheck is a port of Haskell's QuickCheck. Important parts of the manual for using FsCheck is almost literally "adapted" from the QuickCheck manual and paper. Any errors and omissions are entirely my responsibility. FsTest - This project is designed to Language Oriented Programming constructs around unit testing and behavior testing in F#. The goal of this project is to create a Domain Specific Language for testing F# code in a way that makes sense for functional programming. FsUnit - FsUnit makes unit-testing with F# more enjoyable. It adds a special syntax to your favorite .NET testing framework. xUnit.NET - xUnit.net is a developer testing framework, built to support Test Driven Development, with a design goal of extreme simplicity and alignment with framework features. It is compatible with .NET Framework 2.0 and later, and offers several runners: console, GUI, MSBuild, and Visual Studio integration via TestDriven.net, CodeRush Test Runner and Resharper. It also offers test project integration for ASP.NET MVC. Getting started Well, as a first thing you need Visual Studio 2010. Then take a look at these resources: F# samples @ MSDN Microsoft F# Developer Center @ MSDN F# Language Reference @ MSDN F# blog F# forums Real World Functional Programming: With Examples in F# and C# (Amazon) Happy F#-ing! :)

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  • From Bluehost to WP Engine, My WordPress Story

    - by thatjeffsmith
    This is probably the longest blog post I’ve written in a LONG time. And if you’re used to coming here for the Oracle stuff, this post is not about that. It’s about my blog, and the stuff under the hood that makes it run, AKA WordPress. If you want to skip to the juicy stuff, then use these shortcuts: My Site Slowed Down How I Moved to WP Engine How WP Engine ‘Hooked’ Me Why WP Engine? I started thatJeffSmith.com on May 28th, 2010. I had been already been blogging for several years, but a couple of really smart people I respected (Andy, Brent – thanks again!) suggested that I take ownership of my content and begin building my personal brand. I thought that was a good idea, and so I signed up for service with bluehost. Bluehost makes setting up a WordPress site very, very easy. And, they continued to be easy to work with for the past 2 years. I would even recommend them to anyone looking to host their own WordPress install/site. For $83.40, I purchased a year’s worth of service and my domain name registration – a very good value. And then last year I paid $107.40 for another year’s services. And when that year expired I paid another $190.80 for an additional two year’s service in advance. I had been up to that point, getting my money’s worth. And then, just a few weeks ago… My Site Slowed to a Crawl That spike was from an April Fool's Day Post, I think Why? Well, when I first started blogging, I had the same problem that most beginner bloggers have – not many readers. In my first year of blogging, I think the highest number of readers on a single day was about 125. I remember that day as I was very excited to break 100! Bluehost was very reliable, serving up my content with maybe a total of 3-4 outages in the past 2 years. Support was usually very prompt with answers and solutions, and I love their ‘Chat now’ technology – much nicer than message boards only or pay-to-talk phone support. In the past 6 months however, I noticed a couple of things: daily traffic was increasing – woohoo! my service was experiencing severe CPU throttling – doh! To be honest, I wasn’t aware the throttling was occuring, but I did know that the response time of my blog was starting to lag. Average load times were approaching 20-30 seconds. Not good when good sites are loading in 5 seconds or less. And just this past week, in getting ready to launch a new website for work that sucked in an RSS feed from my blog, the new page was left waiting for more than a minute. Not good! In fact my boss asked, why aren’t you blogging on Blogger? Ugh. I tried a few things to fix the problem: I paid for a premium WordPress theme – Themify’s Grido (thanks to @SQLRockstar for the heads-up) I installed a couple of WP caching plugins I read every WP optimization blog post I could get my greedy little eyes on However, at the same time I was also getting addicted to WordPress bloggers talking about all the cool things you could do with your blog. As a result I had at one point about 30 different plugins installed. WordPress runs on MySQL, and certain queries running via these plugins were starving for CPU. Plugins that would be called every page load meant that as more people clicked on my site, the more CPU I needed. I’m not stupid, so I eventually figured out that maybe less plugins was better, and was able to go down to just 20. But still, the site was running like a dog. CPU Throttling, makes MySQL wait to run a query Bluehost runs shared servers. Your site runs on the same box that several hundred (or thousand?) other services are running on. If you take more CPU than they think you should have, they will limit your service by making you stand in line for CPU, AKA ‘throttling.’ This is not bad. This business model allows them to serve many, many users for a very fair price. It works great until, well, until it doesn’t. I noticed in the last week that for every minute of service, I was being throttled between 60 and 300 seconds. If there were 5 MySQL processes running, then every single one of them were being held in check. The blog visitor notice this as their page requests would take a minute or more to be answered. Bluehost unfortunately doesn’t offer dedicated server hosting, so there was no real upgrade path for me follow and remain one of their customers. So what was I to do? Uninstall every plugin and hope the site sped up? Ask for people to take turns on my blog? I decided to spend my way out of the problem. I signed up for service with WP Engine and moved ThatJeffSmith.com The first 2 months are free, and after that it’s about $29/month to run my site on their system. My math tells me that’s a good bit more expensive than what Bluehost was charging me – to the tune of about 300% more a month. Oh, and I should just say that my blog is a personal blog even though I talk about work stuff here. I don’t get paid for blogging, I don’t sell ads, and I don’t expense the service fees – this is my personal passion. So is it worth it? In the first 4 days, it seems to be totally worth it. Load times have gone from 20-30 seconds to less than 5 seconds. A few folks have told me via Twitter that they notice faster page loads. I anticipate this will indirectly lead to more traffic as Google penalizes you in search results if your site is too slow, and of course some folks won’t even bother waiting more than 5-10 seconds. I noticed right away that writing posts, uploading pictures, and just using the WordPress dashboard in general was much more responsive. So writing is less of a chore now, which means I won’t have a good reason not to write How I Moved to WP Engine I signed up for the service and registered my domain. I then took a full export of my ‘old’ site by doing a FTP GET of all my files, then did a MySQL database backup, exported my WordPress Theme settings to a .zip file, and then finally used the WordPress ‘Export’ feature. I then used the WordPress ‘Import’ on the new site to load up my posts. Then I uploaded the theme .zip package from Themify. Then I FTP’d the ‘wp-content’ directory up to my new server using SFTP (WP Engine only supports secure FTP – good on them!) Using a temporary URL to see my new site, I was able to confirm that everything looked mostly OK – I’ll detail the challenges and issues of fixing the content next – but then it was time to ‘flip the switch.’ I updated the IP address that the DNS lookup tables use to route traffic to my new server. In a matter of minutes the DNS servers around the world were updated and it was time to see the new site! But It Was ‘Broken’ I had never moved a website before, and in my rush to update the DNS, I had changed the records without really finding out what I was supposed to do first. After re-reading the directions provided by WP Engine and following the guidance of their support engineer, I realized I had needed to set the CNAME (Alias) ‘www’ record to point to a different URL than the ‘www.thatjeffsmith.com’ entry I had set. Once corrected the site was up and running in less than a minute. Then It Was Only Mostly Broken Many of my plugins weren’t working. Apparently just ftp’ing the wp-content directory up wasn’t the proper way to re-install the plugin. I suspect file permissions or file ownership wasn’t proper. Some plug-ins were working, many had their settings wiped to the defaults, and a few just didn’t work again. I had to delete the directory of the plug-in manually via SFTP, and then use the WP Dashboard to install it from scratch. And here was my first ‘lesson’ – don’t switch the DNS records until you’ve completely tested your new site. I wasn’t able to navigate the old WP console to review my plug-in settings. Thankfully I was able to use the Wayback Machine to reverse engineer some things, and of course most plug-ins aren’t that complicated to setup to begin with. An example of one that I had to redo from scratch is the ‘Twitter @Anywhere Plus’ plugin that I use to create the form that allows folks to tweet a post they enjoyed at the end of each story. How WP Engine ‘Hooked’ Me I actually signed up with another provider first. They ranked highly in Google searches and a few Tweeps recommended them to me. But hours after signing up and I still didn’t have sever reyady, I was ready to give up on them. They offered no chat or phone support – only mail and message boards. And the message boards were rife with posts about how the service had gone downhill in the past 6 months. To their credit, they did make it easy to cancel, although I did have to do so via email as their website ‘cancel’ button was non-existent. Within minutes of activating my WP Engine account I had received my welcome message and directions on how to get started. I was able to see my staged website right away. They also did something very cool before I even got started – they looked at my existing site and told me by how much they could improve its performance. The proof is in the web pudding. I like this for a few reasons, but primarily I liked their business model. It told me they knew what they were doing, and that they were willing to put their money where their mouth was. This was further evident by their 60-day money back guarantee. And if I understand it correctly, they don’t even take your money until after that 60 day period is over. After a day, I was welcomed by the WP Engine social media team, and was given the opportunity to subscribe to their newsletter and follow their account on Twitter. I noticed their Twitter team is sure to post regular WordPress tips several times a day. It’s not just an account that’s setup for the sake of having a Twitter presence. These little things add up and give me confidence in my decision to choose them as my hosting partner. ‘Partner’ – that’s a lot nicer word than just ‘service provider,’ isn’t it? Oh, and they offered me a t-shirt. Don’t ever doubt the power of a ‘free’ t-shirt! How awesome is this e-mail, from a customer perspective? I wasn’t really expecting any of this. Exceeding expectations before I have even handed over a single dollar seems like a pretty good business plan. This is how you treat customers. Love them to death, and they reward you with loyalty. But Jeff, You Skipped a Piece Here, Why WP Engine? I found them on one of those ‘Top 10′ list posts, and pulled up their webpage. I noticed they offered a specialized service – they host WordPress installs, and that’s it. Their servers are tuned specifically for running WordPress. They had in bolded text, things like ‘INSANELY FAST. INFINITELY SCALABLE.’ and ‘LIGHTNING SPEED.’ And then they offered insurance against hackers and they took care of automatic backups and restores. The only drawbacks I have noticed so far relate to plugins I used that have been ‘blacklisted.’ In order to guarantee that ‘lightning’ speed, they have banned the use of the CPU-suckiest plugins. One of those is the ‘Related Posts’ plugin. So if you are a subscriber and are reading this in your email, you’ll notice there’s no links back to my blog to continue reading other related stories. Since that referral traffic is very small single-digit for my site, I decided that I’m OK with that. I’d rather have the warp-speed page loads. Again, I think that will lead to higher traffic down the road. In 50+ days I will need to decide if WP Engine is a permanent solution. I’ll be sure to update this post when that time comes and let y’all know how it turns out.

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  • Improving long-polling Ajax performance

    - by Bears will eat you
    I'm writing a webapp (Firefox-compatible only) which uses long polling (via jQuery's ajax abilities) to send more-or-less constant updates from the server to the client. I'm concerned about the effects of leaving this running for long periods of time, say, all day or overnight. The basic code skeleton is this: function processResults(xml) { // do stuff with the xml from the server } function fetch() { setTimeout(function () { $.ajax({ type: 'GET', url: 'foo/bar/baz', dataType: 'xml', success: function (xml) { processResults(xml); fetch(); }, error: function (xhr, type, exception) { if (xhr.status === 0) { console.log('XMLHttpRequest cancelled'); } else { console.debug(xhr); fetch(); } } }); }, 500); } (The half-second "sleep" is so that the client doesn't hammer the server if the updates are coming back to the client quickly - which they usually are.) After leaving this running overnight, it tends to make Firefox crawl. I'd been thinking that this could be partially caused by a large stack depth since I've basically written an infinitely recursive function. However, if I use Firebug and throw a breakpoint into fetch, it looks like this is not the case. The stack that Firebug shows me is only about 4 or 5 frames deep, even after an hour. One of the solutions I'm considering is changing my recursive function to an iterative one, but I can't figure out how I would insert the delay in between Ajax requests without spinning. I've looked at the JS 1.7 "yield" keyword but I can't quite wrap my head around it, to figure out if it's what I need here. Is the best solution just to do a hard refresh on the page periodically, say, once every hour? Is there a better/leaner long-polling design pattern that won't put a hurt on the browser even after running for 8 or 12 hours? Or should I just skip the long polling altogether and use a different "constant update" pattern since I usually know how frequently the server will have a response for me?

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  • Xapian gem failed to install on Mac OS X Snow Leopard + macports

    - by goodwill
    I have installed xapian-core + xapian-bindings with macports on snow leopard, then trying to install xapian gem fails: Building native extensions. This could take a while... ERROR: Error installing xapian: ERROR: Failed to build gem native extension. /opt/ruby-enterprise/bin/ruby extconf.rb ./configure --with-ruby checking for a BSD-compatible install... /usr/bin/install -c checking whether build environment is sane... yes checking for a thread-safe mkdir -p... ./install-sh -c -d checking for gawk... no checking for mawk... no checking for nawk... no checking for awk... awk checking whether make sets $(MAKE)... yes checking how to create a ustar tar archive... gnutar checking build system type... i386-apple-darwin10.3.0 checking host system type... i386-apple-darwin10.3.0 checking for style of include used by make... GNU checking for gcc... gcc checking for C compiler default output file name... a.out checking whether the C compiler works... yes checking whether we are cross compiling... no checking for suffix of executables... checking for suffix of object files... o checking whether we are using the GNU C compiler... yes checking whether gcc accepts -g... yes checking for gcc option to accept ISO C89... none needed checking dependency style of gcc... gcc3 checking for a sed that does not truncate output... /usr/bin/sed checking for grep that handles long lines and -e... /usr/bin/grep checking for egrep... /usr/bin/grep -E checking for ld used by gcc... /usr/libexec/gcc/i686-apple-darwin10/4.2.1/ld checking if the linker (/usr/libexec/gcc/i686-apple-darwin10/4.2.1/ld) is GNU ld... no checking for /usr/libexec/gcc/i686-apple-darwin10/4.2.1/ld option to reload object files... -r checking for BSD-compatible nm... /usr/bin/nm checking whether ln -s works... yes checking how to recognize dependent libraries... pass_all checking how to run the C preprocessor... gcc -E checking for ANSI C header files... yes checking for sys/types.h... yes checking for sys/stat.h... yes checking for stdlib.h... yes checking for string.h... yes checking for memory.h... yes checking for strings.h... yes checking for inttypes.h... yes checking for stdint.h... yes checking for unistd.h... yes checking dlfcn.h usability... yes checking dlfcn.h presence... yes checking for dlfcn.h... yes checking for g++... g++ checking whether we are using the GNU C++ compiler... yes checking whether g++ accepts -g... yes checking dependency style of g++... gcc3 checking how to run the C++ preprocessor... g++ -E checking the maximum length of command line arguments... 196608 checking command to parse /usr/bin/nm output from gcc object... ok checking for objdir... .libs checking for ar... ar checking for ranlib... ranlib checking for strip... strip checking for dsymutil... dsymutil checking for nmedit... nmedit checking for -single_module linker flag... yes checking for -exported_symbols_list linker flag... yes checking if gcc supports -fno-rtti -fno-exceptions... no checking for gcc option to produce PIC... -fno-common checking if gcc PIC flag -fno-common works... yes checking if gcc static flag -static works... no checking if gcc supports -c -o file.o... yes checking whether the gcc linker (/usr/libexec/gcc/i686-apple-darwin10/4.2.1/ld) supports shared libraries... yes checking dynamic linker characteristics... darwin10.3.0 dyld checking how to hardcode library paths into programs... immediate checking whether stripping libraries is possible... yes checking if libtool supports shared libraries... yes checking whether to build shared libraries... yes checking whether to build static libraries... no checking whether we are using the GNU C++ compiler... (cached) yes checking whether g++ accepts -g... (cached) yes checking dependency style of g++... (cached) gcc3 checking for xapian-config... /opt/local/bin/xapian-config checking /opt/local/bin/xapian-config works... yes checking whether to enable maintainer-specific portions of Makefiles... no checking for ruby1.8... no checking for ruby... /opt/ruby-enterprise/bin/ruby checking /opt/ruby-enterprise/bin/ruby version... ruby 1.8.7 (2009-06-12 patchlevel 174) [i686-darwin10.2.0], MBARI 0x6770, Ruby Enterprise Edition 2009.10 checking for /opt/ruby-enterprise/lib/ruby/1.8/i686-darwin10.2.0/ruby.h... yes checking ruby/io.h... no checking whether to use -fvisibility=hidden... yes configure: creating ./config.status config.status: creating Makefile config.status: creating xapian-version.h config.status: creating python/Makefile config.status: creating python/docs/Makefile config.status: creating php/Makefile config.status: creating php/docs/Makefile config.status: creating java/Makefile config.status: creating java/native/Makefile config.status: creating java/org/xapian/Makefile config.status: creating java/org/xapian/errors/Makefile config.status: creating java/org/xapian/examples/Makefile config.status: creating java-swig/Makefile config.status: creating tcl8/Makefile config.status: creating tcl8/docs/Makefile config.status: creating tcl8/pkgIndex.tcl config.status: creating csharp/Makefile config.status: creating csharp/docs/Makefile config.status: creating csharp/AssemblyInfo.cs config.status: creating ruby/Makefile config.status: creating ruby/docs/Makefile config.status: creating xapian-bindings.spec config.status: creating python/generate-python-exceptions config.status: creating config.h config.status: config.h is unchanged config.status: executing depfiles commands *** Building bindings for languages: ruby make make all-recursive Making all in ruby make all-recursive Making all in docs make all-am make[5]: Nothing to be done for `all-am'. /bin/sh ../libtool --tag=CXX --mode=compile g++ -DHAVE_CONFIG_H -I. -I.. -I/opt/ruby-enterprise/lib/ruby/1.8/i686-darwin10.2.0 -I/opt/ruby-enterprise/lib/ruby/1.8/i686-darwin10.2.0 -fno-strict-aliasing -Wall -Wno-unused -Wno-uninitialized -fvisibility=hidden -I/opt/local/include -g -O2 -MT xapian_wrap.lo -MD -MP -MF .deps/xapian_wrap.Tpo -c -o xapian_wrap.lo xapian_wrap.cc ../libtool: line 393: /bin/sed: No such file or directory ../libtool: line 393: /bin/sed: No such file or directory ../libtool: line 792: /bin/sed: No such file or directory : ignoring unknown tag ../libtool: line 792: /bin/sed: No such file or directory *** Warning: inferring the mode of operation is deprecated. *** Future versions of Libtool will require --mode=MODE be specified. ../libtool: line 1103: /bin/sed: No such file or directory ../libtool: line 1103: /bin/sed: No such file or directory ../libtool: line 1103: /bin/sed: No such file or directory ../libtool: line 1103: /bin/sed: No such file or directory ../libtool: line 1103: /bin/sed: No such file or directory ../libtool: line 1103: /bin/sed: No such file or directory ../libtool: line 1103: /bin/sed: No such file or directory ../libtool: line 1103: /bin/sed: No such file or directory ../libtool: line 1103: /bin/sed: No such file or directory ../libtool: line 1103: /bin/sed: No such file or directory ../libtool: line 1103: /bin/sed: No such file or directory ../libtool: line 1103: /bin/sed: No such file or directory ../libtool: line 1103: /bin/sed: No such file or directory ../libtool: line 1103: /bin/sed: No such file or directory ../libtool: line 1103: /bin/sed: No such file or directory ../libtool: line 1103: /bin/sed: No such file or directory ../libtool: line 1103: /bin/sed: No such file or directory ../libtool: line 1103: /bin/sed: No such file or directory ../libtool: line 1103: /bin/sed: No such file or directory ../libtool: line 1103: /bin/sed: No such file or directory ../libtool: line 1103: /bin/sed: No such file or directory ../libtool: line 1156: /bin/sed: No such file or directory : compile: cannot determine name of library object from `' make[4]: *** [xapian_wrap.lo] Error 1 make[3]: *** [all-recursive] Error 1 make[2]: *** [all] Error 2 make[1]: *** [all-recursive] Error 1 make: *** [all] Error 2 extconf.rb:3:in `system!': unhandled exception from extconf.rb:6 Gem files will remain installed in /opt/ruby-enterprise/lib/ruby/gems/1.8/gems/xapian-1.0.15 for inspection. Results logged to /opt/ruby-enterprise/lib/ruby/gems/1.8/gems/xapian-1.0.15/gem_make.out Any idea pal?

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  • How to make xml in C#?

    - by kacalapy
    i have not worked with XML in a while can someone post the syntax needed to build and save an xml node structure that resembles that of a tree structure that is created by a recursive function. basically i have a recursive function that saves data found an a page(url) and then follows each URL found on that page recursivley and does the same to it. to audit this i want an output as a xml file to disk so i can see how it is doing its recursion and parsing. the code i have is below. please add to it the needed xml calls needed to create a xml structure like the one i show below. (please include the full name space so i can see where the objects i need in .net are for this.) page1.htm has 2 links on it: <a href=page1_1.htm> <a href=page1_2.htm> page1_1.htm has 2 links on it <a href=page1_1_a.htm> (this then will have some links also) <a href=page1_1_b.htm> (this then will have no more links on it - dead end) the xml should do something like this: <node url=page1.htm> ...<node url=page1_1_a.htm> ...... <node url="xxx.htm"/> ...... <node url="yyy.htm".> ... </node> ...<node url=page1_1_b.htm /> </node>

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  • How to use Common Table Expression and check no duplication in SQL Server

    - by vodkhang
    I have a table references to itself. User table: id, username, managerid and managerid links back to id Now, I want to get all the managers including direct manager, manager of direct manager, so on and so forth... The problem is that I do not want to have a unstop recursive sql. So, I want to check if an id alreay in a list, I will not include it anymore. Here is my sql for that: with all_managers (id, username, managerid, idlist) as ( select u1.id, u1.username, u1.managerid, ' ' from users u1, users u2 where u1.id = u2.managerid and u2.id = 6 UNION ALL select u.id, u.username, u.managerid, idlist + ' ' + u.id from all_managers a, users u where a.managerid = u.id and charindex(cast(u.id as nvarchar(5)), idlist) != 0 ) select id, username from all_managers; The problem is that in this line: select u1.id, u1.username, u1.managerid, ' ' The SQL Server complains with me that I can not put ' ' as the initialized for idlist. nvarchar(40) does not work as well. I do not know how to declare it inside a common table expression like this one. Usually, in db2, I can just put varchar(40) My sample data: ID UserName ManagerID 1 admin 1 2 a 1 3 b 1 4 c 2 What I want to do is that I want to find all managers of c guy. The result should be: admin, a, b. Some of the user can be his manager (like admin) because the ManagerID does not allow NULL and some does not have direct manager. With common table expression, it can lead to an infinite recursive. So, I am also trying to avoid that situation by trying to not include the id twice. For example, in the 1st iteration, we already have id : 1, so, in the 2nd iteration and later on, 1 should never be allowed. I also want to ask if my current approach is good or not and any other solutions? Because if I have a big database with a deep hierarchy, I will have to initialize a big varchar to keep it and it consumes memory, right?

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  • Regex For Finding Ctypes with Int32

    - by Stefan H
    (Hey all, I am looking for a little regex help... I am trying to find all CType(expression,Int32) s and replace them with CInt(expression) This, however, is proving quite difficult, considering there could be a nested Ctype(expression, Int32) within the regex match. Does anyone have any ideas for how to best go about doing this? Here is what I have now: Dim str As String = "CType((original.Width * CType((targetSize / CType(original.Height, Single)), Single)), Int32)" Dim exp As New Regex("CType\((.+), Int32\)") str = exp.Replace(str, "CInt($1)") But this will match the entire string and replace it. I was thinking of doing a recursive function to find the outer most match, and then work inwards, but that still presents a problem with things like CType(replaceChars(I), Int32)), Chr(CType(replacementChars(I), Int32) Any tips would be appreciated. Input returnString.Replace(Chr(CType(replaceChars(I), Int32)), Chr(CType(replacementChars(I), Int32))) Output: returnString.Replace(Chr(CInt(replaceChars(I))),Chr(CInt(replacementChars(I)))) Edit: Been working on it a little more and have a recursive function that I'm still working out the kinks in. Recursion + regex. it kinda hurts. Private Function FindReplaceCInts(ByVal strAs As String) As String System.Console.WriteLine(String.Format("Testing : {0}", strAs)) Dim exp As New Regex("CType\((.+), Int32\)") If exp.Match(strAs).Success Then For Each match As Match In exp.Matches(strAs) If exp.Match(match.Value.Substring(2)).Success Then Dim replaceT As String = match.Value.Substring(2) Dim Witht As String = FindReplaceCInts(match.Value.Substring(2)) System.Console.WriteLine(strAs.IndexOf(replaceT)) strAs.Replace(replaceT, Witht) End If Next strAs = exp.Replace(strAs, "CInt($1)") End If Return strAs End Function Cheers,

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  • Using hash tables in racket

    - by user2963128
    Im working on an Ngrams program and im having trouble filling out my hash table. i want to write out a recursive function that will take the words and add them to the hash table. The way its supposed to work is given the data set 1 2 3 4 5 6 7 the first entry in the hash table should have a key of [1 2] and the data should be 3. The second entry should be: [2 3] and its data should be 4 and continuing on until the end of the text file. we are given a predefined function called readword that will simply return 1 word from the text. But im not sure how to make these calls overlap each other. The calls would look something like this if the data was hard coded in. (hash-set! (list "1" "2") 3 (hash-set! (list "2" "3") 4 2 calls that ive tried look like this (hash-set! Ngram-table(list((word1) (word2)) readword in))) (hash-set! Ngram-table(append((cdr data) word1)) readword in) apparently the in after readword is supposed to tell the computer that this is and input instead of an output or something like that. How would I call this to make the data in the key of the hashtable overlap like this? And what would the recursive call look like? edit: also we are not allowed to use assigment statements in this program.

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  • stdexcept On Android

    - by David R.
    I'm trying to compile SoundTouch on Android. I started with this configure line: ./configure CPPFLAGS="-I/Volumes/android-build/mydroid/development/ndk/build/platforms/android-3/arch-arm/usr/include/" LDFLAGS="-Wl,-rpath-link=/Volumes/android-build/mydroid/development/ndk/build/platforms/android-3/arch-arm/usr/lib -L/Volumes/android-build/mydroid/development/ndk/build/platforms/android-3/arch-arm/usr/lib -nostdlib -lc" --host=arm-eabi --enable-shared=yes CFLAGS="-nostdlib -O3 -mandroid" host_alias=arm-eabi --no-create --no-recursion Because the Android NDK targets ARM, I also had to change the Makefile to remove the -msse2 flags to progress. When I run 'make', I get: /bin/sh ../../libtool --tag=CXX --mode=compile arm-eabi-g++ -DHAVE_CONFIG_H -I. -I../../include -I../../include -I/Volumes/android-build/mydroid/development/ndk/build/platforms/android-3/arch-arm/usr/include/ -O3 -fcheck-new -I../../include -g -O2 -MT FIRFilter.lo -MD -MP -MF .deps/FIRFilter.Tpo -c -o FIRFilter.lo FIRFilter.cpp libtool: compile: arm-eabi-g++ -DHAVE_CONFIG_H -I. -I../../include -I../../include -I/Volumes/android-build/mydroid/development/ndk/build/platforms/android-3/arch-arm/usr/include/ -O3 -fcheck-new -I../../include -g -O2 -MT FIRFilter.lo -MD -MP -MF .deps/FIRFilter.Tpo -c FIRFilter.cpp -o FIRFilter.o FIRFilter.cpp:46:21: error: stdexcept: No such file or directory FIRFilter.cpp: In member function 'virtual void soundtouch::FIRFilter::setCoefficients(const soundtouch::SAMPLETYPE*, uint, uint)': FIRFilter.cpp:177: error: 'runtime_error' is not a member of 'std' FIRFilter.cpp: In static member function 'static void* soundtouch::FIRFilter::operator new(size_t)': FIRFilter.cpp:225: error: 'runtime_error' is not a member of 'std' make[2]: *** [FIRFilter.lo] Error 1 make[1]: *** [all-recursive] Error 1 make: *** [all-recursive] Error 1 This isn't very surprising, since the -nostdlib flag was required. Android seems to have neither stdexcept nor stdlib. How can I get past this block of compiling SoundTouch? At a guess, there may be some flag I don't know about that I should use. I could refactor the code not to use stdexcept. There may be a way to pull in the original stdexcept source and reference that. I might be able to link to a precompiled stdexcept library.

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  • Invert linear linked list

    - by ArtWorkAD
    Hi, a linear linked list is a set of nodes. This is how a node is defined (to keep it easy we do not distinguish between node an list): class Node{ Object data; Node link; public Node(Object pData, Node pLink){ this.data = pData; this.link = pLink; } public String toString(){ if(this.link != null){ return this.data.toString() + this.link.toString(); }else{ return this.data.toString() ; } } public void inc(){ this.data = new Integer((Integer)this.data + 1); } public void lappend(Node list){ Node child = this.link; while(child != null){ child = child.link; } child.link = list; } public Node copy(){ if(this.link != null){ return new Node(new Integer((Integer)this.data), this.link.copy()); }else{ return new Node(new Integer((Integer)this.data), null); } } public Node invert(){ Node child = this.link; while(child != null){ child = child.link; } child.link = this;.... } } I am able to make a deep copy of the list. Now I want to invert the list so that the first node is the last and the last the first. The inverted list has to be a deep copy. I started developing the invert function but I am not sure. Any Ideas? Update: Maybe there is a recursive way since the linear linked list is a recursive data structure. I would take the first element, iterate through the list until I get to a node that has no child and append the first element, I would repeat this for the second, third....

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  • More FP-correct way to create an update sql query

    - by James Black
    I am working on access a database using F# and my initial attempt at creating a function to create the update query is flawed. let BuildUserUpdateQuery (oldUser:UserType) (newUser:UserType) = let buf = new System.Text.StringBuilder("UPDATE users SET "); if (oldUser.FirstName.Equals(newUser.FirstName) = false) then buf.Append("SET first_name='").Append(newUser.FirstName).Append("'" ) |> ignore if (oldUser.LastName.Equals(newUser.LastName) = false) then buf.Append("SET last_name='").Append(newUser.LastName).Append("'" ) |> ignore if (oldUser.UserName.Equals(newUser.UserName) = false) then buf.Append("SET username='").Append(newUser.UserName).Append("'" ) |> ignore buf.Append(" WHERE id=").Append(newUser.Id).ToString() This doesn't properly put a , between any update parts after the first, for example: UPDATE users SET first_name='Firstname', last_name='lastname' WHERE id=... I could put in a mutable variable to keep track when the first part of the set clause is appended, but that seems wrong. I could just create an list of tuples, where each tuple is oldtext, newtext, columnname, so that I could then loop through the list and build up the query, but it seems that I should be passing in a StringBuilder to a recursive function, returning back a boolean which is then passed as a parameter to the recursive function. Does this seem to be the best approach, or is there a better one?

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  • Recursively MySQL Query

    - by Rachel
    How can I implement recursive MySQL Queries. I am trying to look for it but resources are not very helpful. Trying to implement similar logic. public function initiateInserts() { //Open Large CSV File(min 100K rows) for parsing. $this->fin = fopen($file,'r') or die('Cannot open file'); //Parsing Large CSV file to get data and initiate insertion into schema. $query = ""; while (($data=fgetcsv($this->fin,5000,";"))!==FALSE) { $query = $query + "INSERT INTO dt_table (id, code, connectid, connectcode) VALUES (" + $data[0] + ", " + $data[1] + ", " + $data[2] + ", " + $data[3] + ")"; } $stmt = $this->prepare($query); // Execute the statement $stmt->execute(); $this->checkForErrors($stmt); } @Author: Numenor Error Message: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '0' at line 1 This Approach inspired to look for an MySQL recursive query approach.

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  • postgres stored procedure problem

    - by easyrider
    Hi all, Ich have a problem in postgres function: CREATE OR REPLACE FUNCTION getVar(id bigint) RETURNS TABLE (repoid bigint, suf VARCHAR, nam VARCHAR) AS $$ declare rec record; BEGIN FOR rec IN (WITH RECURSIVE children(repoobjectid,variant_of_object_fk, suffix, variantname) AS ( SELECT repoobjectid, variant_of_object_fk, '' as suffix,variantname FROM b2m.repoobject_tab WHERE repoobjectid = id UNION ALL SELECT repo.repoobjectid, repo.variant_of_object_fk, suffix || '..' , repo.variantname FROM b2m.repoobject_tab repo, children WHERE children.repoobjectid = repo.variant_of_object_fk) SELECT repoobjectid,suffix,variantname FROM children) LOOP RETURN next; END LOOP; RETURN; END; It can be compiled, but if y try to call it select * from getVar(18) I got 8 empty rows with 3 columns. If i execute the following part of procedure with hard-coded id parameter: WITH RECURSIVE children(repoobjectid,variant_of_object_fk, suffix, variantname) AS ( SELECT repoobjectid, variant_of_object_fk, '' as suffix,variantname FROM b2m.repoobject_tab WHERE repoobjectid = 18 UNION ALL SELECT repo.repoobjectid, repo.variant_of_object_fk, suffix || '..' , repo.variantname FROM b2m.repoobject_tab repo, children WHERE children.repoobjectid = repo.variant_of_object_fk) SELECT repoobjectid,suffix,variantname FROM children I got exactly, what i need 8 rows with data: repoobjectid suffix variantname 18 19 .. for IPhone 22 .. for Nokia 23 .... OS 1.0 and so on. What is going wrong ? Please help. Thanx in advance

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  • Recursion in prepared statements

    - by Rob
    I've been using PDO and preparing all my statements primarily for security reasons. However, I have a part of my code that does execute the same statement many times with different parameters, and I thought this would be where the prepared statements really shine. But they actually break the code... The basic logic of the code is this. function someFunction($something) { global $pdo; $array = array(); static $handle = null; if (!$handle) { $handle = $pdo->prepare("A STATEMENT WITH :a_param"); } $handle->bindValue(":a_param", $something); if ($handle->execute()) { while ($row = $handle->fetch()) { $array[] = someFunction($row['blah']); } } return $array; } It looked fine to me, but it was missing out a lot of rows. Eventually I realised that the statement handle was being changed (executed with different param), which means the call to fetch in the while loop will only ever work once, then the function calls itself again, and the result set is changed. So I am wondering what's the best way of using PDO prepared statements in a recursive way. One way could be to use fetchAll(), but it says in the manual that has a substantial overhead. The whole point of this is to make it more efficient. The other thing I could do is not reuse a static handle, and instead make a new one every time. I believe that since the query string is the same, internally the MySQL driver will be using a prepared statement anyway, so there is just the small overhead of creating a new handle on each recursive call. Personally I think that defeats the point. Or is there some way of rewriting this?

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  • [CODE GENERATION] How to generate DELETE statements in PL/SQL, based on the tables FK relations?

    - by The chicken in the kitchen
    Is it possible via script/tool to generate authomatically many delete statements based on the tables fk relations, using Oracle PL/SQL? In example: I have the table: CHICKEN (CHICKEN_CODE NUMBER) and there are 30 tables with fk references to its CHICKEN_CODE that I need to delete; there are also other 150 tables foreign-key-linked to that 30 tables that I need to delete first. Is there some tool/script PL/SQL that I can run in order to generate all the necessary delete statements based on the FK relations for me? (by the way, I know about cascade delete on the relations, but please pay attention: I CAN'T USE IT IN MY PRODUCTION DATABASE, because it's dangerous!) I'm using Oracle DataBase 10G R2. This is the result I've written, but it is not recursive: This is a view I have previously written, but of course it is not recursive! CREATE OR REPLACE FORCE VIEW RUN ( OWNER_1, CONSTRAINT_NAME_1, TABLE_NAME_1, TABLE_NAME, VINCOLO ) AS SELECT OWNER_1, CONSTRAINT_NAME_1, TABLE_NAME_1, TABLE_NAME, '(' || LTRIM ( EXTRACT (XMLAGG (XMLELEMENT ("x", ',' || COLUMN_NAME)), '/x/text()'), ',') || ')' VINCOLO FROM ( SELECT CON1.OWNER OWNER_1, CON1.TABLE_NAME TABLE_NAME_1, CON1.CONSTRAINT_NAME CONSTRAINT_NAME_1, CON1.DELETE_RULE, CON1.STATUS, CON.TABLE_NAME, CON.CONSTRAINT_NAME, COL.POSITION, COL.COLUMN_NAME FROM DBA_CONSTRAINTS CON, DBA_CONS_COLUMNS COL, DBA_CONSTRAINTS CON1 WHERE CON.OWNER = 'TABLE_OWNER' AND CON.TABLE_NAME = 'TABLE_OWNED' AND ( (CON.CONSTRAINT_TYPE = 'P') OR (CON.CONSTRAINT_TYPE = 'U')) AND COL.TABLE_NAME = CON1.TABLE_NAME AND COL.CONSTRAINT_NAME = CON1.CONSTRAINT_NAME --AND CON1.OWNER = CON.OWNER AND CON1.R_CONSTRAINT_NAME = CON.CONSTRAINT_NAME AND CON1.CONSTRAINT_TYPE = 'R' GROUP BY CON1.OWNER, CON1.TABLE_NAME, CON1.CONSTRAINT_NAME, CON1.DELETE_RULE, CON1.STATUS, CON.TABLE_NAME, CON.CONSTRAINT_NAME, COL.POSITION, COL.COLUMN_NAME) GROUP BY OWNER_1, CONSTRAINT_NAME_1, TABLE_NAME_1, TABLE_NAME; ... and it contains the error of using DBA_CONSTRAINTS instead of ALL_CONSTRAINTS...

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  • Tail recursion and memoization with C#

    - by Jay
    I'm writing a function that finds the full path of a directory based on a database table of entries. Each record contains a key, the directory's name, and the key of the parent directory (it's the Directory table in an MSI if you're familiar). I had an iterative solution, but it started looking a little nasty. I thought I could write an elegant tail recursive solution, but I'm not sure anymore. I'll show you my code and then explain the issues I'm facing. Dictionary<string, string> m_directoryKeyToFullPathDictionary = new Dictionary<string, string>(); ... private string ExpandDirectoryKey(Database database, string directoryKey) { // check for terminating condition string fullPath; if (m_directoryKeyToFullPathDictionary.TryGetValue(directoryKey, out fullPath)) { return fullPath; } // inductive step Record record = ExecuteQuery(database, "SELECT DefaultDir, Directory_Parent FROM Directory where Directory.Directory='{0}'", directoryKey); // null check string directoryName = record.GetString("DefaultDir"); string parentDirectoryKey = record.GetString("Directory_Parent"); return Path.Combine(ExpandDirectoryKey(database, parentDirectoryKey), directoryName); } This is how the code looked when I realized I had a problem (with some minor validation/massaging removed). I want to use memoization to short circuit whenever possible, but that requires me to make a function call to the dictionary to store the output of the recursive ExpandDirectoryKey call. I realize that I also have a Path.Combine call there, but I think that can be circumvented with a ... + Path.DirectorySeparatorChar + .... I thought about using a helper method that would memoize the directory and return the value so that I could call it like this at the end of the function above: return MemoizeHelper( m_directoryKeyToFullPathDictionary, Path.Combine(ExpandDirectoryKey(database, parentDirectoryKey)), directoryName); But I feel like that's cheating and not going to be optimized as tail recursion. Any ideas? Should I be using a completely different strategy? This doesn't need to be a super efficient algorithm at all, I'm just really curious. I'm using .NET 4.0, btw. Thanks!

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  • No idea how to solve SICP exercise 1.11

    - by Javier Badia
    This is not homework. Exercise 1.11: A function f is defined by the rule that f(n) = n if n<3 and f(n) = f(n - 1) + 2f(n - 2) + 3f(n - 3) if n 3. Write a procedure that computes f by means of a recursive process. Write a procedure that computes f by means of an iterative process. Implementing it recursively is simple enough. But I couldn't figure out how to do it iteratively. I tried comparing with the Fibonacci example given, but I didn't know how to use it as an analogy. So I gave up (shame on me) and Googled for an explanation, and I found this: (define (f n) (if (< n 3) n (f-iter 2 1 0 n))) (define (f-iter a b c count) (if (< count 3) a (f-iter (+ a (* 2 b) (* 3 c)) a b (- count 1)))) After reading it, I understand the code and how it works. But what I don't understand is the process needed to get from the recursive defintion of the function to this. I don't get how the code formed in someone's head. Could you explain the thought process needed to arrive at the solution?

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  • What exactly is a reentrant function?

    - by eSKay
    Most of the times, the definition of reentrance is quoted from Wikipedia: A computer program or routine is described as reentrant if it can be safely called again before its previous invocation has been completed (i.e it can be safely executed concurrently). To be reentrant, a computer program or routine: Must hold no static (or global) non-constant data. Must not return the address to static (or global) non-constant data. Must work only on the data provided to it by the caller. Must not rely on locks to singleton resources. Must not modify its own code (unless executing in its own unique thread storage) Must not call non-reentrant computer programs or routines. How is safely defined? If a program can be safely executed concurrently, does it always mean that it is reentrant? What exactly is the common thread between the six points mentioned that I should keep in mind while checking my code for reentrant capabilities? Also, Are all recursive functions reentrant? Are all thread-safe functions reentrant? Are all recursive and thread-safe functions reentrant? While writing this question, one thing comes to mind: Are the terms like reentrance and thread safety absolute at all i.e. do they have fixed concrete definations? For, if they are not, this question is not very meaningful. Thanks!

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  • Running a Model::find in for loop in cakephp v1.3

    - by Gaurav Sharma
    Hi all, How can I achieve the following result in cakephp: In my application a Topic is related to category, category is related to city and city is finally related to state in other words: topic belongs to category, category belongs to city , city belongs to state.. Now in the Topic controller's index action I want to find out all the topics and it's city and state. How can I do this. I can easily do this using a custom query ($this-Model-query() function ) but then I will be facing pagination difficulties. I tried doing like this function index() { $this->Topic->recursive = 0; $topics = $this->paginate(); for($i=0; $i<count($topics);$i++) { $topics[$i]['City'] = $this->Topic->Category->City->find('all', array('conditions' => array('City.id' => $topics[$i]['Category']['city_id']))); } $this->set(compact('messages')); } The method that I have adopted is not a good one (running query in a loop) Using the recursive property and setting it to highest value (2) will degrade performance and is not going to yield me state information. How shall I solve this ? Please help Thanks

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  • string comparision and counting the key in target [closed]

    - by mesun
    Suppose we want to count the number of times that a key string appears in a target string. We are going to create two different functions to accomplish this task: one iterative, and one recursive. For both functions, you can rely on Python's find function - you should read up on its specifications to see how to provide optional arguments to start the search for a match at a location other than the beginning of the string. For example, find("atgacatgcacaagtatgcat","atgc") #returns the value 5, while find("atgacatgcacaagtatgcat","atgc",6) #returns the value 15, meaning that by starting the search at index 6, #the next match is found at location 15. For the recursive version, you will want to think about how to use your function on a smaller version of the same problem (e.g., on a smaller target string) and then how to combine the result of that computation to solve the original problem. For example, given you can find the first instance of a key string in a target string, how would you combine that result with invocation of the same function on a smaller target string? You may find the string slicing operation useful in getting substrings of string.

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