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• Sporadic crash of master-slave MySQL replication process

  - by obarshay

  Hello, I was wondering if someone has experienced this and can perhaps provide some insight into this issue. We have a plan-vanilla MySQL master-slave replication set up. The tables are MyISAM and the master can get quite read/write active. We use the slave instance to perform full daily backups in order to avoid bringing down the master server. The backup process does the following: STOP SLAVE SQL_THREAD mysqlhotcopy all tables START SLAVE SQL_THREAD Every once in a while (once a month or so) the replication breaks with varying error messages indicating a corrupt query or log file. Here's one that happened last night: mysql> show slave status \G *************************** 1. row *************************** Slave_IO_State: Waiting for master to send event Master_Host: server8.propreports.com Master_User: nexus8 Master_Port: 3306 Connect_Retry: 60 Master_Log_File: bin.000045 Read_Master_Log_Pos: 581644327 Relay_Log_File: relay.000086 Relay_Log_Pos: 94131 Relay_Master_Log_File: bin.000045 Slave_IO_Running: Yes Slave_SQL_Running: No Replicate_Do_DB: Replicate_Ignore_DB: Replicate_Do_Table: Replicate_Ignore_Table: Replicate_Wild_Do_Table: Replicate_Wild_Ignore_Table: Last_Errno: 1064 Last_Error: Error '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 '138070603'£' at line 1' on query. Default database: 'wtsdb'. Query: 'UPDATE fill SET clearing_fee='0.0E id='138070603'£' Skip_Counter: 0 Exec_Master_Log_Pos: 4164743 Relay_Log_Space: 577574251 Until_Condition: None Until_Log_File: Until_Log_Pos: 0 Master_SSL_Allowed: No Master_SSL_CA_File: Master_SSL_CA_Path: Master_SSL_Cert: Master_SSL_Cipher: Master_SSL_Key: Seconds_Behind_Master: NULL I follow the following procedure to recover from above error and resume replication: stop slave; change master to MASTER_LOG_POS = 4164743, MASTER_LOG_FILE = 'bin.000045'; start slave; We have multiple servers set up this way and they all sporadically stop replicating with a similar error. Any advice on how to resolve this would be greatly appreciated.

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• ssh use with netcat to forward connections via bastion host to inside machine

  - by Registered User

  Hi, I am having a server in a corporate data centre who's sys admin is me. There are some virtual machines running on it.The main server is accessible from internet via SSH. There are some people who within the lan access the virtual machines whose IPs on LAN are 192.168.1.1 192.168.1.2 192.168.1.3 192.168.1.4 the main machine which is a bastion host for internet has IP 192.168.1.50 and only I have access to it. I have to give people on internet the access to the internal machines whose IP I mentioned above.I know tunnel is a good way but the people are fairly non technical and do not want to get into a tunnel etc jargons.So I came across a solution as explained on this link On the gateway machine which is 192.168.1.50 in the .ssh/config file I add following Host securehost.example.com ProxyCommand ssh [email protected] nc %h %p Now my question is do I need to create separate accounts on the bastion host (gateway) to those users who can SSH to the inside machines and in each of the users .ssh/config I need to make the above entry or where exactly I put the .ssh/config on the gateway. Also ssh [email protected] where user1 exists only on inside machine 192.168.1.1 and not on the gateway is that right syntax? Because the internal machines are accessilbe to outside world as site1.example.com site2.example.com site3.example.com site4.example.com But SSH is only for example.com and only one user.So How should I go for .ssh/config 1) What is the correct syntax for ProxyCommand on gateway's .ssh/config should I use ProxyCommand ssh [email protected] nc %h %p or I should use ProxyCommand ssh [email protected] in nc %h %p 2) Should I create new user accounts on gateway or adding them in AllowedUsers on ssh_config is sufficient?

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• Apache 2 Fails to Start After Upgrade with No Errors

  - by Mark Davidson

  Hi all Hoping someone can help me with a server issue. Recently we upgraded to the latest apache on 2 boxes within are organisation. One being the master box the other being for failover. The upgrade went fine on the master box but on the failover box apache fails to start with no errors, being output or logged. Both boxes have the exact same configuration so found this a bit strange. I've reinstalled apache and have been through checking the configs and did not find any obvious errors. Eventally I ran a syntax check on each config file being included and found that one of the files apparently has syntax errors. Invalid command 'Order', perhaps misspelled or defined by a module not included in the server configuration Invalid command 'php_value', perhaps misspelled or defined by a module not included in the server configuration Invalid command 'GeoIPEnable', perhaps misspelled or defined by a module not included in the server configuration I've trippled checked all the modules are enabled but it still fails. I've googled the subject of these errors loads but have been unable to fine a solution. I was wondering if anyone had encountered such a problem before and could point me towards a solution. Thanks for your help in advance. P.s: Apache related versions on server. ii apache2 2.2.3-4+etch10 Next generation, scalable, extendable web se ii apache2-mpm-prefork 2.2.3-4+etch10 Traditional model for Apache HTTPD 2.1 ii apache2-utils 2.2.3-4+etch10 utility programs for webservers ii apache2.2-common 2.2.3-4+etch10 Next generation, scalable, extendable web se ii libapache2-mod-geoip 1.1.8-2 GeoIP support for apache2 ii libapache2-mod-php5 5.2.0+dfsg-8+etch15 server-side, HTML-embedded scripting languag

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• How to link to a subfolder of a share?

  - by Nicolas Raoul

  On my Windows XP server, a folder called Share2 is shared. It contains a subfolder called folder3. The guest account is protected by a password, which means network users have to type the guest password to access it. When a user types \\server\Share2 in his file explorer, he is prompted for a password. When a user types \\server\Share2\folder3 in his file explorer, an error appears. He is not even prompted for a password. This is problematic because I want to link to this particular folder. How can I link to folder3? Notes: - Both Desktop shortcuts and HTML links in IE7/8 give an error if I link to folder3, but work if I just link to Share2. - Using the file:// syntax instead of the \\ syntax leads to the same results. - Password setting per http://www.lancelhoff.com/how-to-password-protect-a-shared-folder - Not using "Simple File Sharing" - The error message is ???????????????????????? which means "could not find it. check the path and try again". No English Windows around to try, sorry! It is easy to reproduce the problem though, so can anyone post the English error message for the sake of searchability? Thanks!

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• fedora, dhcpd fails to start

  - by soxs060389

  History: I got a tiny shiny plugserver which I want to plug to my ADSL router (or however you want to call it) on one end (eth0), and the other end (eth1) I want to run a dhcp server for my LAN. ATM I am stuck with getting LAN to work. OS is fedora 12. I configured my /etc/dhcp/dhcpd.conf like this: # # DHCP Server Configuration file. # see /usr/share/doc/dhcp*/dhcpd.conf.sample # see 'man 5 dhcpd.conf' # option domain-name "unknown.org"; option domain-name-servers 192.168.44.1; option subnet-mask 255.255.255.0; option broadcast-address 192.168.44.255; default-lease-time 86400; max-lease-time 172800; subnet 192.168.44.0 netmask 255.255.255.0 { host fedorabigbox { hardware ethernet 00:19:66:8E:61:74; fixed-address 192.168.44.21; } #host mobile #{ # hardware ethernet ***; # fixed-address 192.168.44.22; #} range 192.168.44.100 192.168.44.110; option routers 192.168.44.1; } # this is just dummy, as read many howtos, some suggesting to add a subnet blah netmask blah for each interface subnet 192.168.33.0 netmask 255.255.255.0 { range 192.168.33.100 192.168.33.110; option routers 192.168.33.1; } But the server fails to start when trying to start it via /etc/init.d/dhcpd start In general it would be nice if someone can point me to a in detail explanation of how network works, I am pretty new to this stuff. More concrete question: How to point the subnets to eth1 and the other to eth0, how can this be achieved? Does someone see any errors or flaws? Syntax should be correct, allready checked that with the dhcpd syntax check. Thanks for any help

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• How do you use VIM to edit tabular data (tables)? Specifically, BIND (named) DNS db files.

  - by Richard Bronosky

  I'm usually a purist when it comes to vimming. I don't like remapping keys, or learning to rely on a bunch of plugins. I like to feel just as powerful on foreign boxen as I do on my own dev box. I do, however, believe in syntax files. Even though the solution may not be a syntax file (bindzone.vim is what I use), I want it bad enough to do whatever. I regularly view or edit tab (or comma, but that would be a bonus) delimited data. I hate having to set my tabstop to some ridiculous number in order to have everything line up. Example: The BIND zone files are ~40+,6,2,5,15+. So, even though I could view them on a single screen, if I set ts=40, I cannot. I have been searching for a "dynamic tab size" solution for years, but no luck. I hate that my only good way of editing or even visualizing tabular data is to scp it to my work station and open it in Open Office. There has to be a better way.

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• SQL Error (1064) when importing data from SQL file

  - by mejpark

  I have a MySQL database, which was originally set up with the default latin1 character set and latin1_swedish_ci collation. I was using the database like this for sometime, until I noticed strange characters on my production web site, which is powered by a database exported from my development machine. At this point, I changed the default character set of the database and tables to utf8 and the collation to utf8_unicode_ci, converted the latin1 data inside each table to utf8 (using the 'convert data' option) and exported the database as a single SQL file using HeidiSQL. When the resulting SQL file is opened in Notepad++, several characters are rendered incorrectly. For example, en dashes (-) are displayed as – and e with accent (é) are displayed as é. I changed the encoding of the file from ANSI to UTF-8 (using the encoding menu option in Notepad++) and the offending characters are rendered correctly. I saved the new utf8-encoded SQL file and attempted to import the contents into the MySQL database on my production server. The import process fails with following error: /* SQL Error (1064): 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 '?# -------------------------------------------------------- # Host: ' at line 1 */ /* Error with snippets directory: The specified path was not found */ The head of the SQL file: # -------------------------------------------------------- # Host: 127.0.0.1 # Server version: 5.1.33-community # Server OS: Win32 # HeidiSQL version: 6.0.0.3773 # Date/time: 2011-04-20 09:48:36 # -------------------------------------------------------- It chokes on the first line of the file, which is commented out. Why is this happening? I didn't have a problem loading data from SQL files until I changed the character set and collation of the database. I came up with an ugly workaround to this problem by performing following steps: Export database as single SQL file using HeidiSQL Open resulting file in Notepad++ and convert from ANSI to UTF-8 encoding Create new empty file in Notepad++, paste in UTF-8 and save file normally What am I missing here?

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• auto-mounting shared folders in VirtualBox

  - by brannerchinese

  I am writing to ask what the effect of the auto-mounting process is in VirtualBox, and where the folders can be accessed within a guest Linux system if auto-mount is used. I have VirtualBox 4.0.4 installed on Mac OS 10.6.7, with Guest Additions apparently running correctly. The guest OS is Ubuntu 10.04, and I observe no apparent problems with it. I find that if the shared folders have "auto-mount" unchecked in the VirtualBox settings, they can then be mounted using the prescribed syntax sudo mount -t vboxsf folder_name path_to_mount_point and all works as it is supposed to. But if the auto-mount option is checked, then I find that I can no longer mount the shared folders manually. I get the error mounting failed with the error: Invalid argument and the folders also do not appear to mount anywhere else accessible to me. Using the syntax sudo mount -t vboxsf without specifying a path installs them in /media, with their names prefixed with sf_, but they are not easily accessible there and I have not been able to change their owner using chown, either. Thanks for your patient explanation.

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• When ran as a scheduled task, cannot save an Excel workbook when using Excel.Application COM object in PowerShell

  - by Daniel Richnak

  I'm having an issue where I've automated creating an Excel.Application COM object, add some data into a workbook, and then saving the document as an xlsx. This works fine if: I'm already in Powershell interactive host and either run each command in sequence, or execute as a ps1. I run it from cmd.exe, using the syntax: powershell.exe -command "c:\path\to\powershellscript.ps1" I create a scheduled task in Windows 7 / Server 2008 R2, use the above powershell.exe -command syntax, and use the mode "Run only when the user is logged on". It fails when I modify the same scheduled task, but set it to "run whether the user is logged on or not". Here's a sample script that illustrates the problem I'm having: $Excel = New-Object -Com Excel.Application $Excelworkbook = $Excel.Workbooks.Add() $excelworkbook.saveas("C:\temp\test.xlsx") $excelworkbook.close() I have a theory that the COM object fails somehow if my profile isn't loaded / if it's not performed in a command window. Any ideas on which options to choose when creating the scheduled task, or which options to use when creating the Excel object or using the SaveAs() function? Can anybody reproduce this? I've been able to see this behavior on both a Server 2008 R2 machine, and Windows 7. Haven't tried other platforms.

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• MySQL ADO.NET Connector & MSSQL Integration Services

  - by user1114330

  Here I am, day three... attempting to sync a data view on a Windows Vista box (64 bit) running MSSQL 2012 and Visual Studio 2010. Sanity is slipping and hunger for progress fills my attention. I went through hell trying to get the MySQL ODBC drivers to get the job but to no avail...everyone seems to be lost and all the threads I can find are solutions that do not work for me. The problem: System DSN's not being seen by SSIS. SSIS DSN Not Showing as ODBC Data Source I make the decision to try out the ADO.NET connector...and to my surprise it is actually in the selection list in data sources in SSIS. So I take off running to create a Data Flow Task, create an ADO.NET Source (a local MSSQL DB)...all is good as usual. Then I move swiftly to creating a ADO.NET Destination, enter my credentials...wow, I am selecting a database finally on my linux server! Happy thinking that I finally have figured a way to get the job done. Then I move to mappings...nope, something is wrong...I am getting an error that hurts my eyes: Pipeline component has returned HRESULT error code 0xC0208457 from a a method call. Error at Data Flow Task [ADO NET Destination [81]]: Failed to get properties of external columns. The table name you entered may not exist or you do not have SELECT permission on the table object and an alternative attempt to get column properties through connection has failed. Detailed error messages are" 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 "database".tablename" at line 1. The descriptor files on path C:\Program Files (x86)\Microsoft SQL Server\110\DTS\ProviderDescriptors\ does not contain schema information for connection of type MySQL.Data.MySqlClient.MySqlConnection. So it looks like it can't the information and therefore I cannot map the tables properly. Any ideas on this would be ultra helpful...thanks in advance to All!

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• Coloring of collapsed threads in mutt

  - by Rich

  I'm trying to figure out the syntax of colouring collapsed threads in the mutt index. The documentation for mutt patterns doesn't seem to include a description of how this works, and so far I've been completely unable to figure it out by trial and error. What I'd like is for collapsed threads that contain any unread (new) messages to be always coloured green. If collapsed threads with no unread messages contain any flagged messages, then I'd like them to be red. So far, every set of patterns I've tried results in threads that contain both flagged and unread messages being coloured red (I want them green). These work: color index green default "~N" # unread messages color index green default "~N~F" # unread flagged messages color index red default "~F" # flagged messages color index green default "~v~(~N)" # collapsed thread with unread But these don't: color index green default "~v~(~N~F)" # attempt to keep threads with unread green color index red default "~v~(~F)" # colours collapsed threads with flagged and unread red color index red default "~v~(!~N~F)" # ditto color index red default "~v~(^!~N~F)" # ditto color index red default "~v~(~F)~(!~N)" # ditto color index red default "~v~(~F)~v~(!~N)" # ditto I've also tried switching the order of the "~v~(~F)" and "~v~(~N)" commands in the file, but the "flagged" rule always seems to take precedence over the "new" rule. Ideally I'd like to understand how the syntax for colouring collapsed threads works, but at this point I'd happily settle for a set of rules that achieves the colourscheme described above.

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• Portforwarding Combine Several Ports

  - by kiraitachi

  Hi I got a Raspberry Pi at A.A.A.B in my local network and I have set up a DMZ on my router so that any incoming traffic that comes to my router gets redirected to my raspberry pi wich I can connect via NO-IP adress. The problem is that I want to set up portforwarding since i got several services running on my Pi like SSH, torrent webgui, webalbum, etc. I had this already done before long time ago, but I forgot a bit the syntax and cant get to set it up. Router Help says: The Application allows you to do port forwarding, but only have the ports open when data flowing out of the trigger ports. When a program sends data out on outgoing ports called trigger ports, the device then allows incoming data on the open ports specified in your port triggering configuration. 1.Trigger Port Start Trigger Port Start Specify the start port on the device that would trigger the device to open ports for incoming data. 2.Trigger Port End Specify the end port on the device that would trigger the device to open ports for incoming data. You can enter a port number the same as the trigger port start or enter a larger port number to specify a port range. 3.Trigger Traffic Protocol Type Select the trigger traffic type. Open Port Specify all the ports to be opened. It's content could be: A single port only. A port range only. Start open port number and end port number should be separated by "-" . Combined several single port and several port ranges. Each single port or port range should be separated by "," . Open Traffic Protocol Type Select the open traffic type. This are the fields: http://es.tinypic.com/view.php?pic=n5lv1k&s=8 I think this is the syntax 1-7999,8001-9090,9092-65535. But each time I want to add it gives me an error. Any ideas?

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• Defining recursive algebraic data types in XML XSD

  - by Ben Challenor

  Imagine I have a recursive algebraic data type like this (Haskell syntax): data Expr = Zero | One | Add Expr Expr | Mul Expr Expr I'd like to represent this in XML, and I'd like an XSD schema for it. I have figured out how to achieve this syntax: <Expr> <Add> <Expr> <Zero/> </Expr> <Expr> <Mul> <Expr> <One/> </Expr> <Expr> <Add> <Expr> <One/> </Expr> <Expr> <One/> </Expr> </Add> </Expr> </Mul> </Expr> </Add> </Expr> with this schema: <xs:complexType name="Expr"> <xs:choice minOccurs="1" maxOccurs="1"> <xs:element minOccurs="1" maxOccurs="1" name="Zero" type="Zero" /> <xs:element minOccurs="1" maxOccurs="1" name="One" type="One" /> <xs:element minOccurs="1" maxOccurs="1" name="Add" type="Add" /> <xs:element minOccurs="1" maxOccurs="1" name="Mul" type="Mul" /> </xs:choice> </xs:complexType> <xs:complexType name="Zero"> <xs:sequence> </xs:sequence> </xs:complexType> <xs:complexType name="One"> <xs:sequence> </xs:sequence> </xs:complexType> <xs:complexType name="Add"> <xs:sequence> <xs:element minOccurs="2" maxOccurs="2" name="Expr" type="Expr" /> </xs:sequence> </xs:complexType> <xs:complexType name="Mul"> <xs:sequence> <xs:element minOccurs="2" maxOccurs="2" name="Expr" type="Expr" /> </xs:sequence> </xs:complexType> But what I really want is this syntax: <Add> <Zero/> <Mul> <One/> <Add> <One/> <One/> </Add> </Mul> </Add> Is this possible? Thanks!

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• Grafting LINQ onto C# 2 library

  - by P Daddy

  I'm writing a data access layer. It will have C# 2 and C# 3 clients, so I'm compiling against the 2.0 framework. Although encouraging the use of stored procedures, I'm still trying to provide a fairly complete ability to perform ad-hoc queries. I have this working fairly well, already. For the convenience of C# 3 clients, I'm trying to provide as much compatibility with LINQ query syntax as I can. Jon Skeet noticed that LINQ query expressions are duck typed, so I don't have to have an IQueryable and IQueryProvider (or IEnumerable<T>) to use them. I just have to provide methods with the correct signatures. So I got Select, Where, OrderBy, OrderByDescending, ThenBy, and ThenByDescending working. Where I need help are with Join and GroupJoin. I've got them working, but only for one join. A brief compilable example of what I have is this: // .NET 2.0 doesn't define the Func<...> delegates, so let's define some workalikes delegate TResult FakeFunc<T, TResult>(T arg); delegate TResult FakeFunc<T1, T2, TResult>(T1 arg1, T2 arg2); abstract class Projection{ public static Condition operator==(Projection a, Projection b){ return new EqualsCondition(a, b); } public static Condition operator!=(Projection a, Projection b){ throw new NotImplementedException(); } } class ColumnProjection : Projection{ readonly Table table; readonly string columnName; public ColumnProjection(Table table, string columnName){ this.table = table; this.columnName = columnName; } } abstract class Condition{} class EqualsCondition : Condition{ readonly Projection a; readonly Projection b; public EqualsCondition(Projection a, Projection b){ this.a = a; this.b = b; } } class TableView{ readonly Table table; readonly Projection[] projections; public TableView(Table table, Projection[] projections){ this.table = table; this.projections = projections; } } class Table{ public Projection this[string columnName]{ get{return new ColumnProjection(this, columnName);} } public TableView Select(params Projection[] projections){ return new TableView(this, projections); } public TableView Select(FakeFunc<Table, Projection[]> projections){ return new TableView(this, projections(this)); } public Table Join(Table other, Condition condition){ return new JoinedTable(this, other, condition); } public TableView Join(Table inner, FakeFunc<Table, Projection> outerKeySelector, FakeFunc<Table, Projection> innerKeySelector, FakeFunc<Table, Table, Projection[]> resultSelector){ Table join = new JoinedTable(this, inner, new EqualsCondition(outerKeySelector(this), innerKeySelector(inner))); return join.Select(resultSelector(this, inner)); } } class JoinedTable : Table{ readonly Table left; readonly Table right; readonly Condition condition; public JoinedTable(Table left, Table right, Condition condition){ this.left = left; this.right = right; this.condition = condition; } } This allows me to use a fairly decent syntax in C# 2: Table table1 = new Table(); Table table2 = new Table(); TableView result = table1 .Join(table2, table1["ID"] == table2["ID"]) .Select(table1["ID"], table2["Description"]); But an even nicer syntax in C# 3: TableView result = from t1 in table1 join t2 in table2 on t1["ID"] equals t2["ID"] select new[]{t1["ID"], t2["Description"]}; This works well and gives me identical results to the first case. The problem is if I want to join in a third table. TableView result = from t1 in table1 join t2 in table2 on t1["ID"] equals t2["ID"] join t3 in table3 on t1["ID"] equals t3["ID"] select new[]{t1["ID"], t2["Description"], t3["Foo"]}; Now I get an error (Cannot implicitly convert type 'AnonymousType#1' to 'Projection[]'), presumably because the second join is trying to join the third table to an anonymous type containing the first two tables. This anonymous type, of course, doesn't have a Join method. Any hints on how I can do this?

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• AspxGridView Specified method is not supported. problem

  - by shamim

  Bellow is my .aspx aspxGridview syntax <dx:ASPxGridView ID="ASPxGridView1" runat="server" AutoGenerateColumns="False" KeyFieldName="intProductCode" onrowinserted="ASPxGridView1_RowInserted"> <Columns> <dx:GridViewCommandColumn VisibleIndex="0"> <EditButton Visible="True"> </EditButton> <NewButton Visible="True"> </NewButton> <DeleteButton Visible="True"> </DeleteButton> </dx:GridViewCommandColumn> <dx:GridViewDataTextColumn Caption="intProductCode" FieldName="intProductCode" VisibleIndex="1"> </dx:GridViewDataTextColumn> <dx:GridViewDataTextColumn Caption="strProductName" FieldName="strProductName" VisibleIndex="2"> </dx:GridViewDataTextColumn> <dx:GridViewDataTextColumn Caption="SKU" FieldName="SKU" VisibleIndex="3"> </dx:GridViewDataTextColumn> <dx:GridViewDataTextColumn Caption="PACK" FieldName="PACK" VisibleIndex="4"> </dx:GridViewDataTextColumn> <dx:GridViewDataTextColumn Caption="intQtyPerCase" FieldName="intQtyPerCase" VisibleIndex="5"> </dx:GridViewDataTextColumn> <dx:GridViewDataTextColumn Caption="mnyCasePrice" FieldName="mnyCasePrice" VisibleIndex="6"> </dx:GridViewDataTextColumn> <dx:GridViewDataTextColumn Caption="intTBQtyPerCase" FieldName="intTBQtyPerCase" VisibleIndex="7"> </dx:GridViewDataTextColumn> <dx:GridViewDataCheckColumn Caption="bIsActive" FieldName="bIsActive" VisibleIndex="8"> </dx:GridViewDataCheckColumn> <dx:GridViewDataTextColumn Caption="intSortingOrder" FieldName="intSortingOrder" VisibleIndex="9"> </dx:GridViewDataTextColumn> <dx:GridViewDataTextColumn Caption="strProductAccCode" FieldName="strProductAccCode" VisibleIndex="10"> </dx:GridViewDataTextColumn> </Columns> </dx:ASPxGridView> Bellow is my C# syntax : protected void Page_Load(object sender, EventArgs e) { if (this.IsPostBack != true) { BindGridView(); } } private void BindGridView() { DB_OrderV2DataContext db = new DB_OrderV2DataContext(); var r = from p in db.tblProductInfos select p; ASPxGridView1.DataSource = r; ASPxGridView1.DataBind(); } protected void LinqServerModeDataSource1_Selecting(object sender, DevExpress.Data.Linq.LinqServerModeDataSourceSelectEventArgs e) { DB_OrderV2DataContext db = new DB_OrderV2DataContext(); var r= from p in db.tblProductInfos select p; e.QueryableSource = r; } protected void ASPxGridView1_RowInserted(object sender, DevExpress.Web.Data.ASPxDataInsertedEventArgs e) { DB_OrderV2DataContext db = new DB_OrderV2DataContext(); tblProductInfo otblProductInfo = new tblProductInfo (); otblProductInfo.intProductCode = (db.tblProductInfos.Max(p => (int?)p.intProductCode) ?? 0) + 1;//oProductController.GenerateProductCode(); otblProductInfo.strProductName = Convert.ToString(e.NewValues["strProductName"]); otblProductInfo.SKU = Convert.ToString(e.NewValues["SKU"]); otblProductInfo.PACK = Convert.ToString(e.NewValues["PACK"]); otblProductInfo.intQtyPerCase = Convert.ToInt32(e.NewValues["intQtyPerCase"]); otblProductInfo.mnyCasePrice = Convert.ToDecimal(e.NewValues["mnyCasePrice"]); otblProductInfo.intTBQtyPerCase = Convert.ToInt32(e.NewValues["intTBQtyPerCase"]); otblProductInfo.bIsActive = Convert.ToBoolean(e.NewValues["bIsActive"]); otblProductInfo.intSortingOrder = (db.tblProductInfos.Max(p => (int?)p.intSortingOrder) ?? 0) + 1;//oProductController.GenerateSortingOrder(); db.tblProductInfos.InsertOnSubmit(otblProductInfo);//the InsertOnSubmit method called in the preceding code was named Add and the DeleteOnSubmit method was named Remove. db.SubmitChanges(); BindGridView(); //oProductController.InsertAndSubmit(); // ASPxGridView1.DataBind(); } My SQL syntax CREATE TABLE [dbo].[tblProductInfo]( [intProductCode] [int] NOT NULL, [strProductName] [varchar](100) NULL, [SKU] [varchar](50) NULL, [PACK] [varchar](50) NULL, [intQtyPerCase] [int] NULL, [mnyCasePrice] [money] NULL, [intTBQtyPerCase] [int] NULL, [bIsActive] [bit] NULL, [intSortingOrder] [int] NULL, [strProductAccCode] [varchar](max) NULL, CONSTRAINT [PK_tblProductInfo] PRIMARY KEY CLUSTERED ( [intProductCode] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY] When i want to insert ,show me error message Specified method is not supported. How to solve it.

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• Making Sense of ASP.NET Paths

  - by Rick Strahl

  ASP.Net includes quite a plethora of properties to retrieve path information about the current request, control and application. There's a ton of information available about paths on the Request object, some of it appearing to overlap and some of it buried several levels down, and it can be confusing to find just the right path that you are looking for. To keep things straight I thought it a good idea to summarize the path options along with descriptions and example paths. I wrote a post about this a long time ago in 2004 and I find myself frequently going back to that page to quickly figure out which path I’m looking for in processing the current URL. Apparently a lot of people must be doing the same, because the original post is the second most visited even to this date on this blog to the tune of nearly 500 hits per day. So, I decided to update and expand a bit on the original post with a little more information and clarification based on the original comments. Request Object Paths Available Here's a list of the Path related properties on the Request object (and the Page object). Assume a path like http://www.west-wind.com/webstore/admin/paths.aspx for the paths below where webstore is the name of the virtual. .blackborder td { border-bottom: solid 1px silver; border-left: solid 1px silver; } Request Property Description and Value ApplicationPath Returns the web root-relative logical path to the virtual root of this app. /webstore/ PhysicalApplicationPath Returns local file system path of the virtual root for this app. c:\inetpub\wwwroot\webstore PhysicalPath Returns the local file system path to the current script or path. c:\inetpub\wwwroot\webstore\admin\paths.aspx Path FilePath CurrentExecutionFilePath All of these return the full root relative logical path to the script page including path and scriptname. CurrentExcecutionFilePath will return the ‘current’ request path after a Transfer/Execute call while FilePath will always return the original request’s path. /webstore/admin/paths.aspx AppRelativeCurrentExecutionFilePath Returns an ASP.NET root relative virtual path to the script or path for the current request. If in  a Transfer/Execute call the transferred Path is returned. ~/admin/paths.aspx PathInfo Returns any extra path following the script name. If no extra path is provided returns the root-relative path (returns text in red below). string.Empty if no PathInfo is available. /webstore/admin/paths.aspx/ExtraPathInfo RawUrl Returns the full root relative URL including querystring and extra path as a string. /webstore/admin/paths.aspx?sku=wwhelp40 Url Returns a fully qualified URL including querystring and extra path. Note this is a Uri instance rather than string. http://www.west-wind.com/webstore/admin/paths.aspx?sku=wwhelp40 UrlReferrer The fully qualified URL of the page that sent the request. This is also a Uri instance and this value is null if the page was directly accessed by typing into the address bar or using an HttpClient based Referrer client Http header. http://www.west-wind.com/webstore/default.aspx?Info Control.TemplateSourceDirectory Returns the logical path to the folder of the page, master or user control on which it is called. This is useful if you need to know the path only to a Page or control from within the control. For non-file controls this returns the Page path. /webstore/admin/ As you can see there’s a ton of information available there for each of the three common path formats: Physical Path is an OS type path that points to a path or file on disk. Logical Path is a Web path that is relative to the Web server’s root. It includes the virtual plus the application relative path. ~/ (Root-relative) Path is an ASP.NET specific path that includes ~/ to indicate the virtual root Web path. ASP.NET can convert virtual paths into either logical paths using Control.ResolveUrl(), or physical paths using Server.MapPath(). Root relative paths are useful for specifying portable URLs that don’t rely on relative directory structures and very useful from within control or component code. You should be able to get any necessary format from ASP.NET from just about any path or script using these mechanisms. ~/ Root Relative Paths and ResolveUrl() and ResolveClientUrl() ASP.NET supports root-relative virtual path syntax in most of its URL properties in Web Forms. So you can easily specify a root relative path in a control rather than a location relative path: <asp:Image runat="server" ID="imgHelp" ImageUrl="~/images/help.gif" /> ASP.NET internally resolves this URL by using ResolveUrl("~/images/help.gif") to arrive at the root-relative URL of /webstore/images/help.gif which uses the Request.ApplicationPath as the basepath to replace the ~. By convention any custom Web controls also should use ResolveUrl() on URL properties to provide the same functionality. In your own code you can use Page.ResolveUrl() or Control.ResolveUrl() to accomplish the same thing: string imgPath = this.ResolveUrl("~/images/help.gif"); imgHelp.ImageUrl = imgPath; Unfortunately ResolveUrl() is limited to WebForm pages, so if you’re in an HttpHandler or Module it’s not available. ASP.NET Mvc also has it’s own more generic version of ResolveUrl in Url.Decode: <script src="<%= Url.Content("~/scripts/new.js") %>" type="text/javascript"></script> which is part of the UrlHelper class. In ASP.NET MVC the above sort of syntax is actually even more crucial than in WebForms due to the fact that views are not referencing specific pages but rather are often path based which can lead to various variations on how a particular view is referenced. In a Module or Handler code Control.ResolveUrl() unfortunately is not available which in retrospect seems like an odd design choice – URL resolution really should happen on a Request basis not as part of the Page framework. Luckily you can also rely on the static VirtualPathUtility class: string path = VirtualPathUtility.ToAbsolute("~/admin/paths.aspx"); VirtualPathUtility also many other quite useful methods for dealing with paths and converting between the various kinds of paths supported. One thing to watch out for is that ToAbsolute() will throw an exception if a query string is provided and doesn’t work on fully qualified URLs. I wrote about this topic with a custom solution that works fully qualified URLs and query strings here (check comments for some interesting discussions too). Similar to ResolveUrl() is ResolveClientUrl() which creates a fully qualified HTTP path that includes the protocol and domain name. It’s rare that this full resolution is needed but can be useful in some scenarios. Mapping Virtual Paths to Physical Paths with Server.MapPath() If you need to map root relative or current folder relative URLs to physical URLs or you can use HttpContext.Current.Server.MapPath(). Inside of a Page you can do the following: string physicalPath = Server.MapPath("~/scripts/ww.jquery.js")); MapPath is pretty flexible and it understands both ASP.NET style virtual paths as well as plain relative paths, so the following also works. string physicalPath = Server.MapPath("scripts/silverlight.js"); as well as dot relative syntax: string physicalPath = Server.MapPath("../scripts/jquery.js"); Once you have the physical path you can perform standard System.IO Path and File operations on the file. Remember with physical paths and IO or copy operations you need to make sure you have permissions to access files and folders based on the Web server user account that is active (NETWORK SERVICE, ASPNET typically). Note the Server.MapPath will not map up beyond the virtual root of the application for security reasons. Server and Host Information Between these settings you can get all the information you may need to figure out where you are at and to build new Url if necessary. If you need to build a URL completely from scratch you can get access to information about the server you are accessing: Server Variable Function and Example SERVER_NAME The of the domain or IP Address wwww.west-wind.com or 127.0.0.1 SERVER_PORT The port that the request runs under. 80 SERVER_PORT_SECURE Determines whether https: was used. 0 or 1 APPL_MD_PATH ADSI DirectoryServices path to the virtual root directory. Note that LM typically doesn’t work for ADSI access so you should replace that with LOCALHOST or the machine’s NetBios name. /LM/W3SVC/1/ROOT/webstore Request.Url and Uri Parsing If you still need more control over the current request URL or  you need to create new URLs from an existing one, the current Request.Url Uri property offers a lot of control. Using the Uri class and UriBuilder makes it easy to retrieve parts of a URL and create new URLs based on existing URL. The UriBuilder class is the preferred way to create URLs – much preferable over creating URIs via string concatenation. Uri Property Function Scheme The URL scheme or protocol prefix. http or https Port The port if specifically specified. DnsSafeHost The domain name or local host NetBios machine name www.west-wind.com or rasnote LocalPath The full path of the URL including script name and extra PathInfo. /webstore/admin/paths.aspx Query The query string if any ?id=1 The Uri class itself is great for retrieving Uri parts, but most of the properties are read only if you need to modify a URL in order to change it you can use the UriBuilder class to load up an existing URL and modify it to create a new one. Here are a few common operations I’ve needed to do to get specific URLs: Convert the Request URL to an SSL/HTTPS link For example to take the current request URL and converted  it to a secure URL can be done like this: UriBuilder build = new UriBuilder(Request.Url); build.Scheme = "https"; build.Port = -1; // don't inject port Uri newUri = build.Uri; string newUrl = build.ToString(); Retrieve the fully qualified URL without a QueryString AFAIK, there’s no native routine to retrieve the current request URL without the query string. It’s easy to do with UriBuilder however: UriBuilder builder = newUriBuilder(Request.Url); builder.Query = ""; stringlogicalPathWithoutQuery = builder.ToString(); What else? I took a look through the old post’s comments and addressed as many of the questions and comments that came up in there. With a few small and silly exceptions this update post handles most of these. But I’m sure there are a more things that go in here. What else would be useful to put onto this post so it serves as a nice all in one place to go for path references? If you think of something leave a comment and I’ll try to update the post with it in the future.© Rick Strahl, West Wind Technologies, 2005-2010Posted in ASP.NET  

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• Parallelism in .NET – Part 7, Some Differences between PLINQ and LINQ to Objects

  - by Reed

  In my previous post on Declarative Data Parallelism, I mentioned that PLINQ extends LINQ to Objects to support parallel operations.  Although nearly all of the same operations are supported, there are some differences between PLINQ and LINQ to Objects.  By introducing Parallelism to our declarative model, we add some extra complexity.  This, in turn, adds some extra requirements that must be addressed. In order to illustrate the main differences, and why they exist, let’s begin by discussing some differences in how the two technologies operate, and look at the underlying types involved in LINQ to Objects and PLINQ . LINQ to Objects is mainly built upon a single class: Enumerable.  The Enumerable class is a static class that defines a large set of extension methods, nearly all of which work upon an IEnumerable<T>.  Many of these methods return a new IEnumerable<T>, allowing the methods to be chained together into a fluent style interface.  This is what allows us to write statements that chain together, and lead to the nice declarative programming model of LINQ: double min = collection .Where(item => item.SomeProperty > 6 && item.SomeProperty < 24) .Min(item => item.PerformComputation()); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Other LINQ variants work in a similar fashion.  For example, most data-oriented LINQ providers are built upon an implementation of IQueryable<T>, which allows the database provider to turn a LINQ statement into an underlying SQL query, to be performed directly on the remote database. PLINQ is similar, but instead of being built upon the Enumerable class, most of PLINQ is built upon a new static class: ParallelEnumerable.  When using PLINQ, you typically begin with any collection which implements IEnumerable<T>, and convert it to a new type using an extension method defined on ParallelEnumerable: AsParallel().  This method takes any IEnumerable<T>, and converts it into a ParallelQuery<T>, the core class for PLINQ.  There is a similar ParallelQuery class for working with non-generic IEnumerable implementations. This brings us to our first subtle, but important difference between PLINQ and LINQ – PLINQ always works upon specific types, which must be explicitly created. Typically, the type you’ll use with PLINQ is ParallelQuery<T>, but it can sometimes be a ParallelQuery or an OrderedParallelQuery<T>.  Instead of dealing with an interface, implemented by an unknown class, we’re dealing with a specific class type.  This works seamlessly from a usage standpoint – ParallelQuery<T> implements IEnumerable<T>, so you can always “switch back” to an IEnumerable<T>.  The difference only arises at the beginning of our parallelization.  When we’re using LINQ, and we want to process a normal collection via PLINQ, we need to explicitly convert the collection into a ParallelQuery<T> by calling AsParallel().  There is an important consideration here – AsParallel() does not need to be called on your specific collection, but rather any IEnumerable<T>.  This allows you to place it anywhere in the chain of methods involved in a LINQ statement, not just at the beginning.  This can be useful if you have an operation which will not parallelize well or is not thread safe.  For example, the following is perfectly valid, and similar to our previous examples: double min = collection .AsParallel() .Select(item => item.SomeOperation()) .Where(item => item.SomeProperty > 6 && item.SomeProperty < 24) .Min(item => item.PerformComputation()); However, if SomeOperation() is not thread safe, we could just as easily do: double min = collection .Select(item => item.SomeOperation()) .AsParallel() .Where(item => item.SomeProperty > 6 && item.SomeProperty < 24) .Min(item => item.PerformComputation()); In this case, we’re using standard LINQ to Objects for the Select(…) method, then converting the results of that map routine to a ParallelQuery<T>, and processing our filter (the Where method) and our aggregation (the Min method) in parallel. PLINQ also provides us with a way to convert a ParallelQuery<T> back into a standard IEnumerable<T>, forcing sequential processing via standard LINQ to Objects.  If SomeOperation() was thread-safe, but PerformComputation() was not thread-safe, we would need to handle this by using the AsEnumerable() method: double min = collection .AsParallel() .Select(item => item.SomeOperation()) .Where(item => item.SomeProperty > 6 && item.SomeProperty < 24) .AsEnumerable() .Min(item => item.PerformComputation()); Here, we’re converting our collection into a ParallelQuery<T>, doing our map operation (the Select(…) method) and our filtering in parallel, then converting the collection back into a standard IEnumerable<T>, which causes our aggregation via Min() to be performed sequentially. This could also be written as two statements, as well, which would allow us to use the language integrated syntax for the first portion: var tempCollection = from item in collection.AsParallel() let e = item.SomeOperation() where (e.SomeProperty > 6 && e.SomeProperty < 24) select e; double min = tempCollection.AsEnumerable().Min(item => item.PerformComputation()); This allows us to use the standard LINQ style language integrated query syntax, but control whether it’s performed in parallel or serial by adding AsParallel() and AsEnumerable() appropriately. The second important difference between PLINQ and LINQ deals with order preservation.  PLINQ, by default, does not preserve the order of of source collection. This is by design.  In order to process a collection in parallel, the system needs to naturally deal with multiple elements at the same time.  Maintaining the original ordering of the sequence adds overhead, which is, in many cases, unnecessary.  Therefore, by default, the system is allowed to completely change the order of your sequence during processing.  If you are doing a standard query operation, this is usually not an issue.  However, there are times when keeping a specific ordering in place is important.  If this is required, you can explicitly request the ordering be preserved throughout all operations done on a ParallelQuery<T> by using the AsOrdered() extension method.  This will cause our sequence ordering to be preserved. For example, suppose we wanted to take a collection, perform an expensive operation which converts it to a new type, and display the first 100 elements.  In LINQ to Objects, our code might look something like: // Using IEnumerable<SourceClass> collection IEnumerable<ResultClass> results = collection .Select(e => e.CreateResult()) .Take(100); If we just converted this to a parallel query naively, like so: IEnumerable<ResultClass> results = collection .AsParallel() .Select(e => e.CreateResult()) .Take(100); We could very easily get a very different, and non-reproducable, set of results, since the ordering of elements in the input collection is not preserved.  To get the same results as our original query, we need to use: IEnumerable<ResultClass> results = collection .AsParallel() .AsOrdered() .Select(e => e.CreateResult()) .Take(100); This requests that PLINQ process our sequence in a way that verifies that our resulting collection is ordered as if it were processed serially.  This will cause our query to run slower, since there is overhead involved in maintaining the ordering.  However, in this case, it is required, since the ordering is required for correctness. PLINQ is incredibly useful.  It allows us to easily take nearly any LINQ to Objects query and run it in parallel, using the same methods and syntax we’ve used previously.  There are some important differences in operation that must be considered, however – it is not a free pass to parallelize everything.  When using PLINQ in order to parallelize your routines declaratively, the same guideline I mentioned before still applies: Parallelization is something that should be handled with care and forethought, added by design, and not just introduced casually.

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• Making Sense of ASP.NET Paths

  - by Renso

  Making Sense of ASP.NET Paths ASP.Net includes quite a plethora of properties to retrieve path information about the current request, control and application. There's a ton of information available about paths on the Request object, some of it appearing to overlap and some of it buried several levels down, and it can be confusing to find just the right path that you are looking for. To keep things straight I thought it a good idea to summarize the path options along with descriptions and example paths. I wrote a post about this a long time ago in 2004 and I find myself frequently going back to that page to quickly figure out which path I’m looking for in processing the current URL. Apparently a lot of people must be doing the same, because the original post is the second most visited even to this date on this blog to the tune of nearly 500 hits per day. So, I decided to update and expand a bit on the original post with a little more information and clarification based on the original comments. Request Object Paths Available Here's a list of the Path related properties on the Request object (and the Page object). Assume a path like http://www.west-wind.com/webstore/admin/paths.aspx for the paths below where webstore is the name of the virtual. Request Property Description and Value ApplicationPath Returns the web root-relative logical path to the virtual root of this app. /webstore/ PhysicalApplicationPath Returns local file system path of the virtual root for this app. c:\inetpub\wwwroot\webstore PhysicalPath Returns the local file system path to the current script or path. c:\inetpub\wwwroot\webstore\admin\paths.aspx Path FilePath CurrentExecutionFilePath All of these return the full root relative logical path to the script page including path and scriptname. CurrentExcecutionFilePath will return the ‘current’ request path after a Transfer/Execute call while FilePath will always return the original request’s path. /webstore/admin/paths.aspx AppRelativeCurrentExecutionFilePath Returns an ASP.NET root relative virtual path to the script or path for the current request. If in  a Transfer/Execute call the transferred Path is returned. ~/admin/paths.aspx PathInfo Returns any extra path following the script name. If no extra path is provided returns the root-relative path (returns text in red below). string.Empty if no PathInfo is available. /webstore/admin/paths.aspx/ExtraPathInfo RawUrl Returns the full root relative URL including querystring and extra path as a string. /webstore/admin/paths.aspx?sku=wwhelp40 Url Returns a fully qualified URL including querystring and extra path. Note this is a Uri instance rather than string. http://www.west-wind.com/webstore/admin/paths.aspx?sku=wwhelp40 UrlReferrer The fully qualified URL of the page that sent the request. This is also a Uri instance and this value is null if the page was directly accessed by typing into the address bar or using an HttpClient based Referrer client Http header. http://www.west-wind.com/webstore/default.aspx?Info Control.TemplateSourceDirectory Returns the logical path to the folder of the page, master or user control on which it is called. This is useful if you need to know the path only to a Page or control from within the control. For non-file controls this returns the Page path. /webstore/admin/ As you can see there’s a ton of information available there for each of the three common path formats: Physical Path is an OS type path that points to a path or file on disk. Logical Path is a Web path that is relative to the Web server’s root. It includes the virtual plus the application relative path. ~/ (Root-relative) Path is an ASP.NET specific path that includes ~/ to indicate the virtual root Web path. ASP.NET can convert virtual paths into either logical paths using Control.ResolveUrl(), or physical paths using Server.MapPath(). Root relative paths are useful for specifying portable URLs that don’t rely on relative directory structures and very useful from within control or component code. You should be able to get any necessary format from ASP.NET from just about any path or script using these mechanisms. ~/ Root Relative Paths and ResolveUrl() and ResolveClientUrl() ASP.NET supports root-relative virtual path syntax in most of its URL properties in Web Forms. So you can easily specify a root relative path in a control rather than a location relative path: <asp:Image runat="server" ID="imgHelp" ImageUrl="~/images/help.gif" /> ASP.NET internally resolves this URL by using ResolveUrl("~/images/help.gif") to arrive at the root-relative URL of /webstore/images/help.gif which uses the Request.ApplicationPath as the basepath to replace the ~. By convention any custom Web controls also should use ResolveUrl() on URL properties to provide the same functionality. In your own code you can use Page.ResolveUrl() or Control.ResolveUrl() to accomplish the same thing: string imgPath = this.ResolveUrl("~/images/help.gif"); imgHelp.ImageUrl = imgPath; Unfortunately ResolveUrl() is limited to WebForm pages, so if you’re in an HttpHandler or Module it’s not available. ASP.NET Mvc also has it’s own more generic version of ResolveUrl in Url.Decode: <script src="<%= Url.Content("~/scripts/new.js") %>" type="text/javascript"></script> which is part of the UrlHelper class. In ASP.NET MVC the above sort of syntax is actually even more crucial than in WebForms due to the fact that views are not referencing specific pages but rather are often path based which can lead to various variations on how a particular view is referenced. In a Module or Handler code Control.ResolveUrl() unfortunately is not available which in retrospect seems like an odd design choice – URL resolution really should happen on a Request basis not as part of the Page framework. Luckily you can also rely on the static VirtualPathUtility class: string path = VirtualPathUtility.ToAbsolute("~/admin/paths.aspx"); VirtualPathUtility also many other quite useful methods for dealing with paths and converting between the various kinds of paths supported. One thing to watch out for is that ToAbsolute() will throw an exception if a query string is provided and doesn’t work on fully qualified URLs. I wrote about this topic with a custom solution that works fully qualified URLs and query strings here (check comments for some interesting discussions too). Similar to ResolveUrl() is ResolveClientUrl() which creates a fully qualified HTTP path that includes the protocol and domain name. It’s rare that this full resolution is needed but can be useful in some scenarios. Mapping Virtual Paths to Physical Paths with Server.MapPath() If you need to map root relative or current folder relative URLs to physical URLs or you can use HttpContext.Current.Server.MapPath(). Inside of a Page you can do the following: string physicalPath = Server.MapPath("~/scripts/ww.jquery.js")); MapPath is pretty flexible and it understands both ASP.NET style virtual paths as well as plain relative paths, so the following also works. string physicalPath = Server.MapPath("scripts/silverlight.js"); as well as dot relative syntax: string physicalPath = Server.MapPath("../scripts/jquery.js"); Once you have the physical path you can perform standard System.IO Path and File operations on the file. Remember with physical paths and IO or copy operations you need to make sure you have permissions to access files and folders based on the Web server user account that is active (NETWORK SERVICE, ASPNET typically). Note the Server.MapPath will not map up beyond the virtual root of the application for security reasons. Server and Host Information Between these settings you can get all the information you may need to figure out where you are at and to build new Url if necessary. If you need to build a URL completely from scratch you can get access to information about the server you are accessing: Server Variable Function and Example SERVER_NAME The of the domain or IP Address wwww.west-wind.com or 127.0.0.1 SERVER_PORT The port that the request runs under. 80 SERVER_PORT_SECURE Determines whether https: was used. 0 or 1 APPL_MD_PATH ADSI DirectoryServices path to the virtual root directory. Note that LM typically doesn’t work for ADSI access so you should replace that with LOCALHOST or the machine’s NetBios name. /LM/W3SVC/1/ROOT/webstore Request.Url and Uri Parsing If you still need more control over the current request URL or  you need to create new URLs from an existing one, the current Request.Url Uri property offers a lot of control. Using the Uri class and UriBuilder makes it easy to retrieve parts of a URL and create new URLs based on existing URL. The UriBuilder class is the preferred way to create URLs – much preferable over creating URIs via string concatenation. Uri Property Function Scheme The URL scheme or protocol prefix. http or https Port The port if specifically specified. DnsSafeHost The domain name or local host NetBios machine name www.west-wind.com or rasnote LocalPath The full path of the URL including script name and extra PathInfo. /webstore/admin/paths.aspx Query The query string if any ?id=1 The Uri class itself is great for retrieving Uri parts, but most of the properties are read only if you need to modify a URL in order to change it you can use the UriBuilder class to load up an existing URL and modify it to create a new one. Here are a few common operations I’ve needed to do to get specific URLs: Convert the Request URL to an SSL/HTTPS link For example to take the current request URL and converted  it to a secure URL can be done like this: UriBuilder build = new UriBuilder(Request.Url); build.Scheme = "https"; build.Port = -1; // don't inject portUri newUri = build.Uri; string newUrl = build.ToString(); Retrieve the fully qualified URL without a QueryString AFAIK, there’s no native routine to retrieve the current request URL without the query string. It’s easy to do with UriBuilder however: UriBuilder builder = newUriBuilder(Request.Url); builder.Query = ""; stringlogicalPathWithoutQuery = builder.ToString();

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• SQL SERVER – Weekly Series – Memory Lane – #049

  - by Pinal Dave

  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 Two Connections Related Global Variables Explained – @@CONNECTIONS and @@MAX_CONNECTIONS @@CONNECTIONS Returns the number of attempted connections, either successful or unsuccessful since SQL Server was last started. @@MAX_CONNECTIONS Returns the maximum number of simultaneous user connections allowed on an instance of SQL Server. The number returned is not necessarily the number currently configured. Query Editor – Microsoft SQL Server Management Studio This post may be very simple for most of the users of SQL Server 2005. Earlier this year, I have received one question many times – Where is Query Analyzer in SQL Server 2005? I wrote small post about it and pointed many users to that post – SQL SERVER – 2005 Query Analyzer – Microsoft SQL SERVER Management Studio. Recently I have been receiving similar question. OUTPUT Clause Example and Explanation with INSERT, UPDATE, DELETE SQL Server 2005 has a new OUTPUT clause, which is quite useful. OUTPUT clause has access to insert and deleted tables (virtual tables) just like triggers. OUTPUT clause can be used to return values to client clause. OUTPUT clause can be used with INSERT, UPDATE, or DELETE to identify the actual rows affected by these statements. OUTPUT clause can generate a table variable, a permanent table, or temporary table. Even though, @@Identity will still work with SQL Server 2005, however I find the OUTPUT clause very easy and powerful to use. Let us understand the OUTPUT clause using an example. Find Name of The SQL Server Instance Based on database server stored procedures has to run different logic. We came up with two different solutions. 1) When database schema is very much changed, we wrote completely new stored procedure and deprecated older version once it was not needed. 2) When logic depended on Server Name we used global variable @@SERVERNAME. It was very convenient while writing migrating script which depended on the server name for the same database. Explanation of TRY…CATCH and ERROR Handling With RAISEERROR Function One of the developers at my company thought that we can not use the RAISEERROR function in new feature of SQL Server 2005 TRY… CATCH. When asked for an explanation he suggested SQL SERVER – 2005 Explanation of TRY… CATCH and ERROR Handling article as excuse suggesting that I did not give example of RAISEERROR with TRY…CATCH. We all thought it was funny. Just to keep records straight, TRY… CATCH can sure use RAISEERROR function. Different Types of Cache Objects Serveral kinds of objects can be stored in the procedure cache: Compiled Plans: When the query optimizer finishes compiling a query plan, the principal output is compiled plan. Execution contexts: While executing a compiled plan, SQL Server has to keep track of information about the state of execution. Cursors: Cursors track the execution state of server-side cursors, including the cursor’s current location within a resultset. Algebrizer trees: The Algebrizer’s job is to produce an algebrizer tree, which represents the logic structure of a query. Open SSMS From Command Prompt – sqlwb.exe Example This article is written by request and suggestion of Sr. Web Developer at my organization. Due to the nature of this article most of the content is referred from Book On-Line. sqlwbcommand prompt utility which opens SQL Server Management Studio. Squib command does not run queries from the command prompt. sqlcmd utility runs queries from command prompt, read for more information. 2008 Puzzle – Solution – Computed Columns Datatype Explanation Just a day before I wrote article SQL SERVER – Puzzle – Computed Columns Datatype Explanation which was inspired by SQL Server MVP Jacob Sebastian. I suggest that before continuing this article read the original puzzle question SQL SERVER – Puzzle – Computed Columns Datatype Explanation.The question was if the computed column was of datatype TINYINT how to create a Computed Column of datatype INT? 2008 – Find If Index is Being Used in Database It is very often I get a query that how to find if any index is being used in the database or not. If any database has many indexes and not all indexes are used it can adversely affect performance. If the number of indices are higher it reduces the INSERT / UPDATE / DELETE operation but increase the SELECT operation. It is recommended to drop any unused indexes from table to improve the performance. 2009 Interesting Observation – Execution Plan and Results of Aggregate Concatenation Queries If you want to see what’s going on here, I think you need to shift your point of view from an implementation-centric view to an ANSI point of view. ANSI does not guarantee processing the order. Figure 2 is interesting, but it will be potentially misleading if you don’t understand the ANSI rule-set SQL Server operates under in most cases. Implementation thinking can certainly be useful at times when you really need that multi-million row query to finish before the backup fire off, but in this case, it’s counterproductive to understanding what is going on. SQL Server Management Studio and Client Statistics Client Statistics are very important. Many a times, people relate queries execution plan to query cost. This is not a good comparison. Both parameters are different, and they are not always related. It is possible that the query cost of any statement is less, but the amount of the data returned is considerably larger, which is causing any query to run slow. How do we know if any query is retrieving a large amount data or very little data? 2010 I encourage all of you to go through complete series and write your own on the subject. If you write an article and send it to me, I will publish it on this blog with due credit to you. If you write on your own blog, I will update this blog post pointing to your blog post. SQL SERVER – ORDER BY Does Not Work – Limitation of the View 1 SQL SERVER – Adding Column is Expensive by Joining Table Outside View – Limitation of the View 2 SQL SERVER – Index Created on View not Used Often – Limitation of the View 3 SQL SERVER – SELECT * and Adding Column Issue in View – Limitation of the View 4 SQL SERVER – COUNT(*) Not Allowed but COUNT_BIG(*) Allowed – Limitation of the View 5 SQL SERVER – UNION Not Allowed but OR Allowed in Index View – Limitation of the View 6 SQL SERVER – Cross Database Queries Not Allowed in Indexed View – Limitation of the View 7 SQL SERVER – Outer Join Not Allowed in Indexed Views – Limitation of the View 8 SQL SERVER – SELF JOIN Not Allowed in Indexed View – Limitation of the View 9 SQL SERVER – Keywords View Definition Must Not Contain for Indexed View – Limitation of the View 10 SQL SERVER – View Over the View Not Possible with Index View – Limitations of the View 11 SQL SERVER – Get Query Running in Session I was recently looking for syntax where I needed a query running in any particular session. I always remembered the syntax and ha d actually written it down before, but somehow it was not coming to mind quickly this time. I searched online and I ended up on my own article written last year SQL SERVER – Get Last Running Query Based on SPID. I felt that I am getting old because I forgot this really simple syntax. Find Total Number of Transaction on Interval In one of my recent Performance Tuning assignments I was asked how do someone know how many transactions are happening on a server during certain interval. I had a handy script for the same. Following script displays transactions happened on the server at the interval of one minute. You can change the WAITFOR DELAY to any other interval and it should work. 2011 Here are two DMV’s which are newly introduced in SQL Server 2012 and provides vital information about SQL Server. DMV – sys.dm_os_volume_stats – Information about operating system volume DMV – sys.dm_os_windows_info – Information about Operating System SQL Backup and FTP – A Quick and Handy Tool I have used this tool extensively since 2009 at numerous occasion and found it to be very impressive. What separates it from the crowd the most – it is it’s apparent simplicity and speed. When I install SQLBackupAndFTP and configure backups – all in 1 or 2 minutes, my clients are always impressed. Quick Note about JOIN – Common Questions and Simple Answers In this blog post we are going to talk about join and lots of things related to the JOIN. I recently started office hours to answer questions and issues of the community. I receive so many questions that are related to JOIN. I will share a few of the same over here. Most of them are basic, but note that the basics are of great importance. 2012 Importance of User Without Login Question: “In recent version of SQL Server we can create user without login. What is the use of it?” Great question indeed. Let me first attempt to answer this question but after reading my answer I need your help. I want you to help him as well with adding more value to it. Preserve Leading Zero While Coping to Excel from SSMS Earlier I wrote two articles about how to efficiently copy data from SSMS to Excel. Since I wrote that post there are plenty of interest generated on this subject. There are a few questions I keep on getting over this subject. One of the question is how to get the leading zero preserved while copying the data from SSMS to Excel. Well it is almost the same way as my earlier post SQL SERVER – Excel Losing Decimal Values When Value Pasted from SSMS ResultSet. The key here is in EXCEL and not in SQL Server. Solution – 2 T-SQL Puzzles – Display Star and Shortest Code to Display 1 Earlier on this blog we had asked two puzzles. The response from all of you is nothing but Amazing. I have received 350+ responses. Many are valid and many were indeed something I had not thought about it. I strongly suggest you read all the puzzles and their answers here - trust me if you start reading the comments you will not stop till you read every single comment. Seriously trust me on it. Personally I have learned a lot from it. Identify Most Resource Intensive Queries – SQL in Sixty Seconds #028 – Video http://www.youtube.com/watch?v=TvlYy-TGaaA Importance of User Without Login – T-SQL Demo Script Earlier I wrote a blog post about SQL SERVER – Importance of User Without Login and my friend and SQL Expert Vinod Kumar has written excellent follow up blog post about Contained Databases inside SQL Server 2012. Now lots of people asked me if I can also explain the same concept again so here is the small demonstration for it. Let me show you how login without user can help. Before we continue on this subject I strongly recommend that you read my earlier blog post here. In following demo I am going to demonstrate following situation. Login using the System Admin account Create a user without login Checking Access Impersonate the user without login Checking Access Revert Impersonation Give Permission to user without login Impersonate the user without login Checking Access Revert Impersonation Clean up 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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• Links to my “Best of 2010” Posts

  - by ScottGu

  I hope everyone is having a Happy New Years! 2010 has been a busy blogging year for me (this is the 100th blog post I’ve done in 2010).  Several people this week suggested I put together a summary post listing/organizing my favorite posts from the year.  Below is a quick listing of some of my favorite posts organized by topic area: VS 2010 and .NET 4 Below is a series of posts I wrote (some in late 2009) about the VS 2010 and .NET 4 (including ASP.NET 4 and WPF 4) release we shipped in April: Visual Studio 2010 and .NET 4 Released Clean Web.Config Files Starter Project Templates Multi-targeting Multiple Monitor Support New Code Focused Web Profile Option HTML / ASP.NET / JavaScript Code Snippets Auto-Start ASP.NET Applications URL Routing with ASP.NET 4 Web Forms Searching and Navigating Code in VS 2010 VS 2010 Code Intellisense Improvements WPF 4 Add Reference Dialog Improvements SEO Improvements with ASP.NET 4 Output Cache Extensibility with ASP.NET 4 Built-in Charting Controls for ASP.NET and Windows Forms Cleaner HTML Markup with ASP.NET 4 - Client IDs Optional Parameters and Named Arguments in C# 4 - and a cool scenarios with ASP.NET MVC 2 Automatic Properties, Collection Initializers and Implicit Line Continuation Support with VB 2010 New <%: %> Syntax for HTML Encoding Output using ASP.NET 4 JavaScript Intellisense Improvements with VS 2010 VS 2010 Debugger Improvements (DataTips, BreakPoints, Import/Export) Box Selection and Multi-line Editing Support with VS 2010 VS 2010 Extension Manager (and the cool new PowerCommands Extension) Pinning Projects and Solutions VS 2010 Web Deployment Debugging Tips/Tricks with Visual Studio Search and Navigation Tips/Tricks with Visual Studio Visual Studio Below are some additional Visual Studio posts I’ve done (not in the first series above) that I thought were nice: Download and Share Visual Studio Color Schemes Visual Studio 2010 Keyboard Shortcuts VS 2010 Productivity Power Tools Fun Visual Studio 2010 Wallpapers Silverlight We shipped Silverlight 4 in April, and announced Silverlight 5 the beginning of December: Silverlight 4 Released Silverlight 4 Tools for VS 2010 and WCF RIA Services Released Silverlight 4 Training Kit Silverlight PivotViewer Now Available Silverlight Questions Announcing Silverlight 5 Silverlight for Windows Phone 7 We shipped Windows Phone 7 this fall and shipped free Visual Studio development tools with great Silverlight and XNA support in September: Windows Phone 7 Developer Tools Released Building a Windows Phone 7 Twitter Application using Silverlight ASP.NET MVC We shipped ASP.NET MVC 2 in March, and started previewing ASP.NET MVC 3 this summer.  ASP.NET MVC 3 will RTM in less than 2 weeks from today: ASP.NET MVC 2: Strongly Typed Html Helpers ASP.NET MVC 2: Model Validation Introducing ASP.NET MVC 3 (Preview 1) Announcing ASP.NET MVC 3 Beta and NuGet (nee NuPack) Announcing ASP.NET MVC 3 Release Candidate 1  Announcing ASP.NET MVC 3 Release Candidate 2 Introducing Razor – A New View Engine for ASP.NET ASP.NET MVC 3: Layouts with Razor ASP.NET MVC 3: New @model keyword in Razor ASP.NET MVC 3: Server-Side Comments with Razor ASP.NET MVC 3: Razor’s @: and <text> syntax ASP.NET MVC 3: Implicit and Explicit code nuggets with Razor ASP.NET MVC 3: Layouts and Sections with Razor IIS and Web Server Stack The IIS and Web Stack teams have made a bunch of great improvements to the core web server this year: Fix Common SEO Problems using the URL Rewrite Extension Introducing the Microsoft Web Farm Framework Automating Deployment with Microsoft Web Deploy Introducing IIS Express SQL CE 4 (New Embedded Database Support with ASP.NET) Introducing Web Matrix EF Code First EF Code First is a really nice new data option that enables a very clean code-oriented data workflow: Announcing Entity Framework Code-First CTP5 Release Class-Level Model Validation with EF Code First and ASP.NET MVC 3 Code-First Development with Entity Framework 4 EF 4 Code First: Custom Database Schema Mapping Using EF Code First with an Existing Database jQuery and AJAX Contributions My team began making some significant source code contributions to the jQuery project this year: jQuery Templates, Data Link and Globalization Accepted as Official jQuery Plugins jQuery Templates and Data Linking (and Microsoft contributing to jQuery) jQuery Globalization Plugin from Microsoft Patches and Hot Fixes Some useful fixes you can download prior to VS 2010 SP1: Patch for Cut/Copy “Insufficient Memory” issue with VS 2010 Patch for VS 2010 Find and Replace Dialog Growing Patch for VS 2010 Scrolling Context Menu Videos of My Talks Some recordings of technical talks I’ve done this year: ASP.NET 4, ASP.NET MVC, and Silverlight 4 Talks I did in Europe VS 2010 and ASP.NET 4 Web Forms Talk in Arizona Other About Technical Debates (and ASP.NET Web Forms and ASP.NET MVC debates in particular) ASP.NET Security Fix Now on Windows Update Upcoming Web Camps I’d like to say a big thank you to everyone who follows my blog – I really appreciate you reading it (the comments you post help encourage me to write it).  See you in the New Year! Scott P.S. In addition to blogging, I am also now using Twitter for quick updates and to share links. Follow me at: twitter.com/scottgu

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• Parallelism in .NET – Part 20, Using Task with Existing APIs

  - by Reed

  Although the Task class provides a huge amount of flexibility for handling asynchronous actions, the .NET Framework still contains a large number of APIs that are based on the previous asynchronous programming model.  While Task and Task<T> provide a much nicer syntax as well as extending the flexibility, allowing features such as continuations based on multiple tasks, the existing APIs don’t directly support this workflow. There is a method in the TaskFactory class which can be used to adapt the existing APIs to the new Task class: TaskFactory.FromAsync.  This method provides a way to convert from the BeginOperation/EndOperation method pair syntax common through .NET Framework directly to a Task<T> containing the results of the operation in the task’s Result parameter. While this method does exist, it unfortunately comes at a cost – the method overloads are far from simple to decipher, and the resulting code is not always as easily understood as newer code based directly on the Task class.  For example, a single call to handle WebRequest.BeginGetResponse/EndGetReponse, one of the easiest “pairs” of methods to use, looks like the following: var task = Task.Factory.FromAsync<WebResponse>( request.BeginGetResponse, request.EndGetResponse, null); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } The compiler is unfortunately unable to infer the correct type, and, as a result, the WebReponse must be explicitly mentioned in the method call.  As a result, I typically recommend wrapping this into an extension method to ease use.  For example, I would place the above in an extension method like: public static class WebRequestExtensions { public static Task<WebResponse> GetReponseAsync(this WebRequest request) { return Task.Factory.FromAsync<WebResponse>( request.BeginGetResponse, request.EndGetResponse, null); } } This dramatically simplifies usage.  For example, if we wanted to asynchronously check to see if this blog supported XHTML 1.0, and report that in a text box to the user, we could do: var webRequest = WebRequest.Create("http://www.reedcopsey.com"); webRequest.GetReponseAsync().ContinueWith(t => { using (var sr = new StreamReader(t.Result.GetResponseStream())) { string str = sr.ReadLine();; this.textBox1.Text = string.Format("Page at {0} supports XHTML 1.0: {1}", t.Result.ResponseUri, str.Contains("XHTML 1.0")); } }, TaskScheduler.FromCurrentSynchronizationContext());   By using a continuation with a TaskScheduler based on the current synchronization context, we can keep this request asynchronous, check based on the first line of the response string, and report the results back on our UI directly.

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• Start Learning Ruby with IronRuby – Setting up the Environment

  - by kazimanzurrashid

  Recently I have decided to learn Ruby and for last few days I am playing with IronRuby. Learning a new thing is always been a fun and when it comes to adorable language like Ruby it becomes more entertaining. Like any other language, first we have to create the development environment. In order to run IronRuby we have to download the binaries form the IronRuby CodePlex project. IronRuby supports both .NET 2.0 and .NET 4, but .NET 4 is the recommended version, you can download either the installation or the zip file. If you download the zip file make sure you added the bin directory in the environment path variable. Once you are done, open up the command prompt and type : ir –v It should print message like: IronRuby 1.0.0.0 on .NET 4.0.30319.1 The ir is 32bit version of IronRuby, if you want to use 64bit you can try ir64. Next, we have to find a editor where we can write our Ruby code as there is currently no integration story of IronRuby with Visual Studio like its twin Iron Python. Among the free IDEs only SharpDevelop has the IronRuby support but it does not have auto complete or debugging built into it, only thing that it supports is the syntax highlighting, so using a text editor which has the same features is nothing different comparing to it. To play with the IronRuby we will be using Notepad++, which can be downloaded from its sourceforge download page. The Notepad++ does have a nice syntax highlighting support : I am using the Vibrant Ink with some little modification. The next thing we have to do is configure the Notepad++ that we can run the Ruby script in IronRuby inside the Notepad++. Lets create a batch(.bat) file in the IronRuby bin directory, which will have the following content: @echo off  cls call ir %1 pause This will make sure that the console will be paused once we run the script. Now click Run->Run in the Notepad++, it will bring up the run dialog and put the following command in the textbox: riir.bat "$(FULL_CURRENT_PATH)" Click the save which will bring another dialog. Type Iron Ruby and assign the shortcut to ctrl + f5 (Same as Visual Studio Start without Debugging) and click ok. Once you are done you will find the IronRuby in the Run menu. Now press ctrl + f5, we will find the ruby script running in the IronRuby. Now there are one last thing that we would like to add which is poor man’s context sensitive help. First, download the ruby language help file from the Ruby Installer site and extract into a directory. Next we will have to install the Language Help Plug-in of Notepad++, click Plugins->Plugin Manger –>Show Plugin Manager and scroll down until you find the plug-in the list, now check the plug-in and click install. Once it is installed it will prompt you to restart the Notepad++, click yes. When the Notepad++ restarts, click the Plugins –> Language Help –> Options –> add and enter the following details and click ok: The chm file location can be different depending upon where you extracted it. Now when you put your in any of ruby keyword and press ctrl + f1 it will take you to the help topic of that keyword. For example, when my caret is in the each of the following code and I press ctrl + f1, it will take me to the each api doc of Array. def loop_demo (1..10).each{ |n| puts n} end loop_demo That’s it for today. Happy Ruby coding.

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• OSI Model

  - by kaleidoscope

  The Open System Interconnection Reference Model (OSI Reference Model or OSI Model) is an abstract description for layered communications and computer network protocol design. In its most basic form, it divides network architecture into seven layers which, from top to bottom, are the Application, Presentation, Session, Transport, Network, Data Link, and Physical Layers. It is therefore often referred to as the OSI Seven Layer Model. A layer is a collection of conceptually similar functions that provide services to the layer above it and receives service from the layer below it. Description of OSI layers: Layer 1: Physical Layer ·         Defines the electrical and physical specifications for devices. In particular, it defines the relationship between a device and a physical medium. ·         Establishment and termination of a connection to a communications medium. ·         Participation in the process whereby the communication resources are effectively shared among multiple users. ·         Modulation or conversion between the representation of digital data in user equipment and the corresponding signals transmitted over a communications channel. Layer 2: Data Link Layer ·         Provides the functional and procedural means to transfer data between network entities. ·         Detect and possibly correct errors that may occur in the Physical Layer. The error check is performed using Frame Check Sequence (FCS). ·         Addresses is then sought to see if it needs to process the rest of the frame itself or whether to pass it on to another host. ·         The Layer is divided into two sub layers: The Media Access Control (MAC) layer and the Logical Link Control (LLC) layer. ·         MAC sub layer controls how a computer on the network gains access to the data and permission to transmit it. ·         LLC layer controls frame synchronization, flow control and error checking.   Layer 3: Network Layer ·         Provides the functional and procedural means of transferring variable length data sequences from a source to a destination via one or more networks. ·         Performs network routing functions, and might also perform fragmentation and reassembly, and report delivery errors. ·         Network Layer Routers operate at this layer—sending data throughout the extended network and making the Internet possible.   Layer 4: Transport Layer ·         Provides transparent transfer of data between end users, providing reliable data transfer services to the upper layers. ·         Controls the reliability of a given link through flow control, segmentation/de-segmentation, and error control. ·         Transport Layer can keep track of the segments and retransmit those that fail. Layer 5: Session Layer ·         Controls the dialogues (connections) between computers. ·         Establishes, manages and terminates the connections between the local and remote application. ·         Provides for full-duplex, half-duplex, or simplex operation, and establishes checkpointing, adjournment, termination, and restart procedures. ·         Implemented explicitly in application environments that use remote procedure calls. Layer 6: Presentation Layer ·         Establishes a context between Application Layer entities, in which the higher-layer entities can use different syntax and semantics, as long as the presentation service understands both and the mapping between them. The presentation service data units are then encapsulated into Session Protocol data units, and moved down the stack. ·         Provides independence from differences in data representation (e.g., encryption) by translating from application to network format, and vice versa. The presentation layer works to transform data into the form that the application layer can accept. This layer formats and encrypts data to be sent across a network, providing freedom from compatibility problems. It is sometimes called the syntax layer. Layer 7: Application Layer ·         This layer interacts with software applications that implement a communicating component. ·         Identifies communication partners, determines resource availability, and synchronizes communication. o       When identifying communication partners, the application layer determines the identity and availability of communication partners for an application with data to transmit. o       When determining resource availability, the application layer must decide whether sufficient network or the requested communication exists. o       In synchronizing communication, all communication between applications requires cooperation that is managed by the application layer. Technorati Tags: Kunal,OSI,Networking

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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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• Creating and using VM Groups in VirtualBox

  - by Fat Bloke

  With VirtualBox 4.2 we introduced the Groups feature which allows you to organize and manage your guest virtual machines collectively, rather than individually. Groups are quite a powerful concept and there are a few nice features you may not have discovered yet, so here's a bit more information about groups, and how they can be used.... Creating a group Groups are just ad hoc collections of virtual machines and there are several ways of creating a group: In the VirtualBox Manager GUI: Drag one VM onto another to create a group of those 2 VMs. You can then drag and drop more VMs into that group; Select multiple VMs (using Ctrl or Shift and click) then  select the menu: Machine...Group; or   press Cmd+U (Mac), or Ctrl+U(Windows); or right-click the multiple selection and choose Group, like this: From the command line: Group membership is an attribute of the vm so you can modify the vm to belong in a group. For example, to put the vm "Ubuntu" into the group "TestGroup" run this command: VBoxManage modifyvm "Ubuntu" --groups "/TestGroup" Deleting a Group Groups can be deleted by removing a group attribute from all the VMs that constitute that group. To do this via the command-line the syntax is: VBoxManage modifyvm "Ubuntu" --groups "" In the VirtualBox Manager, this is more easily done by right-clicking on a group header and selecting "Ungroup", like this: Multiple Groups Now that we understand that Groups are just attributes of VMs, it can be seen that VMs can exist in multiple groups, for example, doing this: VBoxManage modifyvm "Ubuntu" --groups "/TestGroup","/ProjectX","/ProjectY" Results in: Or via the VirtualBox Manager, you can drag VMs while pressing the Alt key (Mac) or Ctrl (other platforms). Nested Groups Just like you can drag VMs around in the VirtualBox Manager, you can also drag whole groups around. And dropping a group within a group creates a nested group. Via the command-line, nested groups are specified using a path-like syntax, like this: VBoxManage modifyvm "Ubuntu" --groups "/TestGroup/Linux" ...which creates a sub-group and puts the VM in it. Navigating Groups In the VirtualBox Manager, Groups can be collapsed and expanded by clicking on the carat to the left in the Group Header. But you can also Enter and Leave groups too, either by using the right-arrow/left-arrow keys, or by clicking on the carat on the right hand side of the Group Header, like this: . ..leading to a view of just the Group contents. You can Leave or return to the parent in the same way. Don't worry if you are imprecise with your clicking, you can use a double click on the entire right half of the Group Header to Enter a group, and the left half to Leave a group. Double-clicking on the left half when you're at the top will roll-up or collapse the group.   Group Operations The real power of Groups is not simply in arranging them prettily in the Manager. Rather it is about performing collective operations on them, once you have grouped them appropriately. For example, let's say that you are working on a project (Project X) where you have a solution stack of: Database VM, Middleware/App VM, and  a couple of client VMs which you use to test your app. With VM Groups you can start the whole stack with one operation. Select the Group Header, and choose Start: The full list of operations that may be performed on Groups are: Start Starts from any state (boot or resume) Start VMs in headless mode (hold Shift while starting) Pause Reset Close Save state Send Shutdown signal Poweroff Discard saved state Show in filesystem Sort Conclusion Hopefully we've shown that the introduction of VM Groups not only makes Oracle VM VirtualBox pretty, but pretty powerful too.  - FB 

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