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• Understanding EDI 997.

  - by VishnuTiwariBlog

  Hi Guys, This is for the EDI starter. Below is the complete detail of EDI 997 segment and element details. 997 Functional Acknowledgment Transaction Layout: No. Seg ID Name Description Example M/O 010 ST Transaction Set Header To indicate the start of a transaction set and to assign a control number ST*997*382823~   M ST01   Code uniquely identifying a Transaction Set   M ST02   Identifying control number that must be unique within the transaction set functional group assigned by the originator for a transaction set   M 020 AK1 Functional Group Response Header To start acknowledgment of a functional group AK1*QM*2459823 M        AK101   Code identifying a group of application related transaction sets IN Invoice Information (810) SH Ship Notice/Manifest (856)     AK102   Assigned number originated and maintained by the sender     030 AK2 Transaction Set Response Header To start acknowledgment of a single transaction set AK2*856*001 M AK201   Code uniquely identifying a Transaction Set 810 Invoice 856 Ship Notice/Manifest   M AK202   Identifying control number that must be unique within the transaction set functional group assigned by the originator for a transaction set   M 040 AK3 Data Segment Note To report errors in a data segment and identify the location of the data segment AK3*TD3*9 O AK301 Segment ID Code Code defining the segment ID of the data segment in error (See Appendix A - Number 77)     AK302 Segment Position in Transaction Set The numerical count position of this data segment from the start of the transaction set: the transaction set header is count position 1     050 AK4 Data Element Note To report errors in a data element or composite data structure and identify the location of the data element AK4*2**2 O AK401 Position in Segment Code indicating the relative position of a simple data element, or the relative position of a composite data structure combined with the relative position of the component data element within the composite data structure, in error; the count starts with 1 for the simple data element or composite data structure immediately following the segment ID     AK402 Element Position in Segment This is used to indicate the relative position of a simple data element, or the relative position of a composite data structure with the relative position of the component within the composite data structure, in error; in the data segment the count starts with 1 for the simple data element or composite data structure immediately following the segment ID     AK403 Data Element Syntax Error Code Code indicating the error found after syntax edits of a data element 1 Mandatory Data Element Missing 2 Conditional Required Data Element Missing 3 Too Many Data Elements 4 Data Element Too Short 5 Data Element Too Long 6 Invalid Character in Data Element 7 Invalid Code Value 8 Invalid Date 9 Invalid Time 10 Exclusion Condition Violated     AK404 Copy of Bad Data Element This is a copy of the data element in error     060 AK5 AK5 Transaction Set Response Trailer To acknowledge acceptance or rejection and report errors in a transaction set AK5*A~ AK5*R*5~ M AK501 Transaction Set Acknowledgment Code Code indicating accept or reject condition based on the syntax editing of the transaction set A Accepted E Accepted But Errors Were Noted R Rejected     AK502 Transaction Set Syntax Error Code Code indicating error found based on the syntax editing of a transaction set 1 Transaction Set Not Supported 2 Transaction Set Trailer Missing 3 Transaction Set Control Number in Header and Trailer Do Not Match 4 Number of Included Segments Does Not Match Actual Count 5 One or More Segments in Error 6 Missing or Invalid Transaction Set Identifier 7 Missing or Invalid Transaction Set Control Number     070 AK9 Functional Group Response Trailer To acknowledge acceptance or rejection of a functional group and report the number of included transaction sets from the original trailer, the accepted sets, and the received sets in this functional group AK9*A*1*1*1~ AK9*R*1*1*0~ M AK901 Functional Group Acknowledge Code Code indicating accept or reject condition based on the syntax editing of the functional group A Accepted E Accepted, But Errors Were Noted. R Rejected     AK902 Number of Transaction Sets Included Total number of transaction sets included in the functional group or interchange (transmission) group terminated by the trailer containing this data element     AK903 Number of Received Transaction Sets Number of Transaction Sets received     AK904 Number of Accepted Transaction Sets Number of accepted Transaction Sets in a Functional Group     AK905 Functional Group Syntax Error Code Code indicating error found based on the syntax editing of the functional group header and/or trailer 1 Functional Group Not Supported 2 Functional Group Version Not Supported 3 Functional Group Trailer Missing 4 Group Control Number in the Functional Group Header and Trailer Do Not Agree 5 Number of Included Transaction Sets Does Not Match Actual Count 6 Group Control Number Violates Syntax     080 SE Transaction Set Trailer To indicate the end of the transaction set and provide the count of the transmitted segments (including the beginning (ST) and ending (SE) segments) SE*9*223~ M SE01 Number of Included Segments Total number of segments included in a transaction set including ST and SE segments     SE02 Transaction Set Control Number Identifying control number that must be unique within the transaction set functional group assigned by the originator for a transaction set

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• Understanding EDI 997

  - by VishnuTiwariBlog

  Hi Guys, This is for the EDI starter. Below is the complete detail of EDI 997 segment and element details. 997 Functional Acknowledgment Transaction Layout:   No. Seg ID Name Description Example M/O 010 ST Transaction Set Header To indicate the start of a transaction set and to assign a control number ST*997*382823~   M ST01   Code uniquely identifying a Transaction Set   M ST02   Identifying control number that must be unique within the transaction set functional group assigned by the originator for a transaction set   M 020 AK1 Functional Group Response Header To start acknowledgment of a functional group AK1*QM*2459823 M        AK101   Code identifying a group of application related transaction sets IN Invoice Information (810) SH Ship Notice/Manifest (856)     AK102   Assigned number originated and maintained by the sender     030 AK2 Transaction Set Response Header To start acknowledgment of a single transaction set AK2*856*001 M AK201   Code uniquely identifying a Transaction Set 810 Invoice 856 Ship Notice/Manifest   M AK202   Identifying control number that must be unique within the transaction set functional group assigned by the originator for a transaction set   M 040 AK3 Data Segment Note To report errors in a data segment and identify the location of the data segment AK3*TD3*9 O AK301 Segment ID Code Code defining the segment ID of the data segment in error (See Appendix A - Number 77)     AK302 Segment Position in Transaction Set The numerical count position of this data segment from the start of the transaction set: the transaction set header is count position 1     050 AK4 Data Element Note To report errors in a data element or composite data structure and identify the location of the data element AK4*2**2 O AK401 Position in Segment Code indicating the relative position of a simple data element, or the relative position of a composite data structure combined with the relative position of the component data element within the composite data structure, in error; the count starts with 1 for the simple data element or composite data structure immediately following the segment ID     AK402 Element Position in Segment This is used to indicate the relative position of a simple data element, or the relative position of a composite data structure with the relative position of the component within the composite data structure, in error; in the data segment the count starts with 1 for the simple data element or composite data structure immediately following the segment ID     AK403 Data Element Syntax Error Code Code indicating the error found after syntax edits of a data element 1 Mandatory Data Element Missing 2 Conditional Required Data Element Missing 3 Too Many Data Elements 4 Data Element Too Short 5 Data Element Too Long 6 Invalid Character in Data Element 7 Invalid Code Value 8 Invalid Date 9 Invalid Time 10 Exclusion Condition Violated     AK404 Copy of Bad Data Element This is a copy of the data element in error     060 AK5 AK5 Transaction Set Response Trailer To acknowledge acceptance or rejection and report errors in a transaction set AK5*A~ AK5*R*5~ M AK501 Transaction Set Acknowledgment Code Code indicating accept or reject condition based on the syntax editing of the transaction set A Accepted E Accepted But Errors Were Noted R Rejected     AK502 Transaction Set Syntax Error Code Code indicating error found based on the syntax editing of a transaction set 1 Transaction Set Not Supported 2 Transaction Set Trailer Missing 3 Transaction Set Control Number in Header and Trailer Do Not Match 4 Number of Included Segments Does Not Match Actual Count 5 One or More Segments in Error 6 Missing or Invalid Transaction Set Identifier 7 Missing or Invalid Transaction Set Control Number     070 AK9 Functional Group Response Trailer To acknowledge acceptance or rejection of a functional group and report the number of included transaction sets from the original trailer, the accepted sets, and the received sets in this functional group AK9*A*1*1*1~ AK9*R*1*1*0~ M AK901 Functional Group Acknowledge Code Code indicating accept or reject condition based on the syntax editing of the functional group A Accepted E Accepted, But Errors Were Noted. R Rejected     AK902 Number of Transaction Sets Included Total number of transaction sets included in the functional group or interchange (transmission) group terminated by the trailer containing this data element     AK903 Number of Received Transaction Sets Number of Transaction Sets received     AK904 Number of Accepted Transaction Sets Number of accepted Transaction Sets in a Functional Group     AK905 Functional Group Syntax Error Code Code indicating error found based on the syntax editing of the functional group header and/or trailer 1 Functional Group Not Supported 2 Functional Group Version Not Supported 3 Functional Group Trailer Missing 4 Group Control Number in the Functional Group Header and Trailer Do Not Agree 5 Number of Included Transaction Sets Does Not Match Actual Count 6 Group Control Number Violates Syntax     080 SE Transaction Set Trailer To indicate the end of the transaction set and provide the count of the transmitted segments (including the beginning (ST) and ending (SE) segments) SE*9*223~ M SE01 Number of Included Segments Total number of segments included in a transaction set including ST and SE segments     SE02 Transaction Set Control Number Identifying control number that must be unique within the transaction set functional group assigned by the originator for a transaction set

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• Understanding MotionEvent to implement a virtual DPad and Buttons on Android (Multitouch)

  - by Fabio Gomes

  I once implemented a DPad in XNA and now I'm trying to port it to android, put, I still don't get how the touch events work in android, the more I read the more confused I get. Here is the code I wrote so far, it works, but guess that it will only handle one touch point. public boolean onTouchEvent(MotionEvent event) { if (event.getPointerCount() == 0) return true; int touchX = -1; int touchY = -1; pressedDirection = DPadDirection.None; int actionCode = event.getAction() & MotionEvent.ACTION_MASK; if (actionCode == MotionEvent.ACTION_UP) { if (event.getPointerId(0) == idDPad) { pressedDirection = DPadDirection.None; idDPad = -1; } } else if (actionCode == MotionEvent.ACTION_DOWN || actionCode == MotionEvent.ACTION_MOVE) { touchX = (int)event.getX(); touchY = (int)event.getY(); if (rightRect.contains(touchX, touchY)) pressedDirection = DPadDirection.Right; else if (leftRect.contains(touchX, touchY)) pressedDirection = DPadDirection.Left; else if (upRect.contains(touchX, touchY)) pressedDirection = DPadDirection.Up; else if (downRect.contains(touchX, touchY)) pressedDirection = DPadDirection.Down; if (pressedDirection != DPadDirection.None) idDPad = event.getPointerId(0); } return true; } The logic is: Test if there is a "DOWN" or "MOVED" event, then if one of this events collides with one of the 4 rectangles of my DPad, I set the pressedDirectin variable to the side of the touch event, then I read the DPad actual pressed direction in my Update() event on another class. The thing I'm not sure, is how do I get track of the touch points, I store the ID of the touch point which generated the diretion that is being stored (last one), so when this ID is released I set the Direction to None, but I'm really confused about how to handle this in android, here is the code I had in XNA: public override void Update(GameTime gameTime) { PressedDirection = DpadDirection.None; foreach (TouchLocation _touchLocation in TouchPanel.GetState()) { if (_touchLocation.State == TouchLocationState.Released) { if (_touchLocation.Id == _idDPad) { PressedDirection = DpadDirection.None; _idDPad = -1; } } else if (_touchLocation.State == TouchLocationState.Pressed || _touchLocation.State == TouchLocationState.Moved) { _intersectRect.X = (int)_touchLocation.Position.X; _intersectRect.Y = (int)_touchLocation.Position.Y; _intersectRect.Width = 1; _intersectRect.Height = 1; if (_intersectRect.Intersects(_rightRect)) PressedDirection = DpadDirection.Right; else if (_intersectRect.Intersects(_leftRect)) PressedDirection = DpadDirection.Left; else if (_intersectRect.Intersects(_upRect)) PressedDirection = DpadDirection.Up; else if (_intersectRect.Intersects(_downRect)) PressedDirection = DpadDirection.Down; if (PressedDirection != DpadDirection.None) { _idDPad = _touchLocation.Id; continue; } } } base.Update(gameTime); } So, first of all: Am I doing this correctly? if not, why? I don't want my DPad to handle multiple directions, but I still didn't get how to handle the multiple touch points, is the event called for every touch point, or all touch points comes in a single call? I still don't get it.

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• Understanding LINQ to SQL (11) Performance

  - by Dixin

  [LINQ via C# series] LINQ to SQL has a lot of great features like strong typing query compilation deferred execution declarative paradigm etc., which are very productive. Of course, these cannot be free, and one price is the performance. O/R mapping overhead Because LINQ to SQL is based on O/R mapping, one obvious overhead is, data changing usually requires data retrieving:private static void UpdateProductUnitPrice(int id, decimal unitPrice) { using (NorthwindDataContext database = new NorthwindDataContext()) { Product product = database.Products.Single(item => item.ProductID == id); // SELECT... product.UnitPrice = unitPrice; // UPDATE... database.SubmitChanges(); } } Before updating an entity, that entity has to be retrieved by an extra SELECT query. This is slower than direct data update via ADO.NET:private static void UpdateProductUnitPrice(int id, decimal unitPrice) { using (SqlConnection connection = new SqlConnection( "Data Source=localhost;Initial Catalog=Northwind;Integrated Security=True")) using (SqlCommand command = new SqlCommand( @"UPDATE [dbo].[Products] SET [UnitPrice] = @UnitPrice WHERE [ProductID] = @ProductID", connection)) { command.Parameters.Add("@ProductID", SqlDbType.Int).Value = id; command.Parameters.Add("@UnitPrice", SqlDbType.Money).Value = unitPrice; connection.Open(); command.Transaction = connection.BeginTransaction(); command.ExecuteNonQuery(); // UPDATE... command.Transaction.Commit(); } } The above imperative code specifies the “how to do” details with better performance. For the same reason, some articles from Internet insist that, when updating data via LINQ to SQL, the above declarative code should be replaced by:private static void UpdateProductUnitPrice(int id, decimal unitPrice) { using (NorthwindDataContext database = new NorthwindDataContext()) { database.ExecuteCommand( "UPDATE [dbo].[Products] SET [UnitPrice] = {0} WHERE [ProductID] = {1}", id, unitPrice); } } Or just create a stored procedure:CREATE PROCEDURE [dbo].[UpdateProductUnitPrice] ( @ProductID INT, @UnitPrice MONEY ) AS BEGIN BEGIN TRANSACTION UPDATE [dbo].[Products] SET [UnitPrice] = @UnitPrice WHERE [ProductID] = @ProductID COMMIT TRANSACTION END and map it as a method of NorthwindDataContext (explained in this post):private static void UpdateProductUnitPrice(int id, decimal unitPrice) { using (NorthwindDataContext database = new NorthwindDataContext()) { database.UpdateProductUnitPrice(id, unitPrice); } } As a normal trade off for O/R mapping, a decision has to be made between performance overhead and programming productivity according to the case. In a developer’s perspective, if O/R mapping is chosen, I consistently choose the declarative LINQ code, unless this kind of overhead is unacceptable. Data retrieving overhead After talking about the O/R mapping specific issue. Now look into the LINQ to SQL specific issues, for example, performance in the data retrieving process. The previous post has explained that the SQL translating and executing is complex. Actually, the LINQ to SQL pipeline is similar to the compiler pipeline. It consists of about 15 steps to translate an C# expression tree to SQL statement, which can be categorized as: Convert: Invoke SqlProvider.BuildQuery() to convert the tree of Expression nodes into a tree of SqlNode nodes; Bind: Used visitor pattern to figure out the meanings of names according to the mapping info, like a property for a column, etc.; Flatten: Figure out the hierarchy of the query; Rewrite: for SQL Server 2000, if needed Reduce: Remove the unnecessary information from the tree. Parameterize Format: Generate the SQL statement string; Parameterize: Figure out the parameters, for example, a reference to a local variable should be a parameter in SQL; Materialize: Executes the reader and convert the result back into typed objects. So for each data retrieving, even for data retrieving which looks simple: private static Product[] RetrieveProducts(int productId) { using (NorthwindDataContext database = new NorthwindDataContext()) { return database.Products.Where(product => product.ProductID == productId) .ToArray(); } } LINQ to SQL goes through above steps to translate and execute the query. Fortunately, there is a built-in way to cache the translated query. Compiled query When such a LINQ to SQL query is executed repeatedly, The CompiledQuery can be used to translate query for one time, and execute for multiple times:internal static class CompiledQueries { private static readonly Func<NorthwindDataContext, int, Product[]> _retrieveProducts = CompiledQuery.Compile((NorthwindDataContext database, int productId) => database.Products.Where(product => product.ProductID == productId).ToArray()); internal static Product[] RetrieveProducts( this NorthwindDataContext database, int productId) { return _retrieveProducts(database, productId); } } The new version of RetrieveProducts() gets better performance, because only when _retrieveProducts is first time invoked, it internally invokes SqlProvider.Compile() to translate the query expression. And it also uses lock to make sure translating once in multi-threading scenarios. Static SQL / stored procedures without translating Another way to avoid the translating overhead is to use static SQL or stored procedures, just as the above examples. Because this is a functional programming series, this article not dive into. For the details, Scott Guthrie already has some excellent articles: LINQ to SQL (Part 6: Retrieving Data Using Stored Procedures) LINQ to SQL (Part 7: Updating our Database using Stored Procedures) LINQ to SQL (Part 8: Executing Custom SQL Expressions) Data changing overhead By looking into the data updating process, it also needs a lot of work: Begins transaction Processes the changes (ChangeProcessor) Walks through the objects to identify the changes Determines the order of the changes Executes the changings LINQ queries may be needed to execute the changings, like the first example in this article, an object needs to be retrieved before changed, then the above whole process of data retrieving will be went through If there is user customization, it will be executed, for example, a table’s INSERT / UPDATE / DELETE can be customized in the O/R designer It is important to keep these overhead in mind. Bulk deleting / updating Another thing to be aware is the bulk deleting:private static void DeleteProducts(int categoryId) { using (NorthwindDataContext database = new NorthwindDataContext()) { database.Products.DeleteAllOnSubmit( database.Products.Where(product => product.CategoryID == categoryId)); database.SubmitChanges(); } } The expected SQL should be like:BEGIN TRANSACTION exec sp_executesql N'DELETE FROM [dbo].[Products] AS [t0] WHERE [t0].[CategoryID] = @p0',N'@p0 int',@p0=9 COMMIT TRANSACTION Hoverer, as fore mentioned, the actual SQL is to retrieving the entities, and then delete them one by one:-- Retrieves the entities to be deleted: exec sp_executesql N'SELECT [t0].[ProductID], [t0].[ProductName], [t0].[SupplierID], [t0].[CategoryID], [t0].[QuantityPerUnit], [t0].[UnitPrice], [t0].[UnitsInStock], [t0].[UnitsOnOrder], [t0].[ReorderLevel], [t0].[Discontinued] FROM [dbo].[Products] AS [t0] WHERE [t0].[CategoryID] = @p0',N'@p0 int',@p0=9 -- Deletes the retrieved entities one by one: BEGIN TRANSACTION exec sp_executesql N'DELETE FROM [dbo].[Products] WHERE ([ProductID] = @p0) AND ([ProductName] = @p1) AND ([SupplierID] IS NULL) AND ([CategoryID] = @p2) AND ([QuantityPerUnit] IS NULL) AND ([UnitPrice] = @p3) AND ([UnitsInStock] = @p4) AND ([UnitsOnOrder] = @p5) AND ([ReorderLevel] = @p6) AND (NOT ([Discontinued] = 1))',N'@p0 int,@p1 nvarchar(4000),@p2 int,@p3 money,@p4 smallint,@p5 smallint,@p6 smallint',@p0=78,@p1=N'Optimus Prime',@p2=9,@p3=$0.0000,@p4=0,@p5=0,@p6=0 exec sp_executesql N'DELETE FROM [dbo].[Products] WHERE ([ProductID] = @p0) AND ([ProductName] = @p1) AND ([SupplierID] IS NULL) AND ([CategoryID] = @p2) AND ([QuantityPerUnit] IS NULL) AND ([UnitPrice] = @p3) AND ([UnitsInStock] = @p4) AND ([UnitsOnOrder] = @p5) AND ([ReorderLevel] = @p6) AND (NOT ([Discontinued] = 1))',N'@p0 int,@p1 nvarchar(4000),@p2 int,@p3 money,@p4 smallint,@p5 smallint,@p6 smallint',@p0=79,@p1=N'Bumble Bee',@p2=9,@p3=$0.0000,@p4=0,@p5=0,@p6=0 -- ... COMMIT TRANSACTION And the same to the bulk updating. This is really not effective and need to be aware. Here is already some solutions from the Internet, like this one. The idea is wrap the above SELECT statement into a INNER JOIN:exec sp_executesql N'DELETE [dbo].[Products] FROM [dbo].[Products] AS [j0] INNER JOIN ( SELECT [t0].[ProductID], [t0].[ProductName], [t0].[SupplierID], [t0].[CategoryID], [t0].[QuantityPerUnit], [t0].[UnitPrice], [t0].[UnitsInStock], [t0].[UnitsOnOrder], [t0].[ReorderLevel], [t0].[Discontinued] FROM [dbo].[Products] AS [t0] WHERE [t0].[CategoryID] = @p0) AS [j1] ON ([j0].[ProductID] = [j1].[[Products])', -- The Primary Key N'@p0 int',@p0=9 Query plan overhead The last thing is about the SQL Server query plan. Before .NET 4.0, LINQ to SQL has an issue (not sure if it is a bug). LINQ to SQL internally uses ADO.NET, but it does not set the SqlParameter.Size for a variable-length argument, like argument of NVARCHAR type, etc. So for two queries with the same SQL but different argument length:using (NorthwindDataContext database = new NorthwindDataContext()) { database.Products.Where(product => product.ProductName == "A") .Select(product => product.ProductID).ToArray(); // The same SQL and argument type, different argument length. database.Products.Where(product => product.ProductName == "AA") .Select(product => product.ProductID).ToArray(); } Pay attention to the argument length in the translated SQL:exec sp_executesql N'SELECT [t0].[ProductID] FROM [dbo].[Products] AS [t0] WHERE [t0].[ProductName] = @p0',N'@p0 nvarchar(1)',@p0=N'A' exec sp_executesql N'SELECT [t0].[ProductID] FROM [dbo].[Products] AS [t0] WHERE [t0].[ProductName] = @p0',N'@p0 nvarchar(2)',@p0=N'AA' Here is the overhead: The first query’s query plan cache is not reused by the second one:SELECT sys.syscacheobjects.cacheobjtype, sys.dm_exec_cached_plans.usecounts, sys.syscacheobjects.[sql] FROM sys.syscacheobjects INNER JOIN sys.dm_exec_cached_plans ON sys.syscacheobjects.bucketid = sys.dm_exec_cached_plans.bucketid; They actually use different query plans. Again, pay attention to the argument length in the [sql] column (@p0 nvarchar(2) / @p0 nvarchar(1)). Fortunately, in .NET 4.0 this is fixed:internal static class SqlTypeSystem { private abstract class ProviderBase : TypeSystemProvider { protected int? GetLargestDeclarableSize(SqlType declaredType) { SqlDbType sqlDbType = declaredType.SqlDbType; if (sqlDbType <= SqlDbType.Image) { switch (sqlDbType) { case SqlDbType.Binary: case SqlDbType.Image: return 8000; } return null; } if (sqlDbType == SqlDbType.NVarChar) { return 4000; // Max length for NVARCHAR. } if (sqlDbType != SqlDbType.VarChar) { return null; } return 8000; } } } In this above example, the translated SQL becomes:exec sp_executesql N'SELECT [t0].[ProductID] FROM [dbo].[Products] AS [t0] WHERE [t0].[ProductName] = @p0',N'@p0 nvarchar(4000)',@p0=N'A' exec sp_executesql N'SELECT [t0].[ProductID] FROM [dbo].[Products] AS [t0] WHERE [t0].[ProductName] = @p0',N'@p0 nvarchar(4000)',@p0=N'AA' So that they reuses the same query plan cache: Now the [usecounts] column is 2.

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• Understanding Collabnet&rsquo;s LDAP binding

  - by Robert May

  We want to use both subversion usernames and passwords as well as Active Directory for our authentication on our Collabnet subversion server. This has proven to be more of a challenge than we thought, mostly because Collabnet’s documentation is pretty poor. To supplement that documentation, I add my own. The first thing to understand is that the attribute that you specify in the LDAP Login Attribute ONLY applies to lookups done for the user.  It does NOT apply to the LDAP Bind DN field.  Second, know that the debug logs (error is the one you want) don’t give you debug information for the bind DN, just the login attempts.  Third, by default, Active Directory does not allow anonymous binds, so you MUST put in a user that has the authority to query the Active Directory ldap. Because of these items, the values to set in those fields can be somewhat confusing.  You’ll want to have ADSI Edit handy (I also used ldp, which is installed by default on server 2008), since ADSI Edit can help you find stuff in your active directory.  Be careful, you can also break stuff. Here’s what should go into those fields. LDAP Security Level:  Should be set to None LDAP Server Host:  Should be set to the full name of a domain controller in your domain.  For example, dc.mydomain.com LDAP Server Port:  Should be set to 3268.  The default port of 389 will only query that specific server, not the global catalog.  By setting it to 3268, the global catalog will be queried, which is probably what you want. LDAP Base DN:  Should be set to the location where you want the search for users to begin.  By default, the search scope is set to sub, so all child organizational units below this setting will be searched.  In my case, I had created an OU specifically for users for group policies.  My value ended up being:  OU=MyOu,DC=domain,DC=org.   However, if you’re pointing it to the default Users folder, you may end up with something like CN=Users,DC=domain,DC=org (or com or whatever).  Again, use ADSI edit and use the Distinguished Name that it shows. LDAP Bind DN:  This needs to be the Distinguished Name of the user that you’re going to use for binding (i.e. the user you’ll be impersonating) for doing queries.  In my case, it ended up being CN=svn svn,OU=MyOu,DC=domain,DC=org.  Why the double svn, you might ask?  That’s because the first and last name fields are set to svn and by default, the distinguished name is the first and last name fields!  That’s important.  Its NOT the username or account name!  Again, use ADSI edit, browse to the username you want to use, right click and select properties, and then search the attributes for the Distinguished Name.  Once you’ve found that, select it and click View and you can copy and paste that into this field. LDAP Bind Password:  This is the password for the account in the Bind DN LDAP login Attribute: sAMAccountName.  If you leave this blank, uid is used, which may not even be set.  This tells it to use the Account Name field that’s defined under the account tab for users in Active Directory Users and Computers.  Note that this attribute DOES NOT APPLY to the LDAP Bind DN.  You must use the full distinguished name of the bind DN.  This attribute allows users to type their username and password for authentication, rather than typing their distinguished name, which they probably don’t know. LDAP Search Scope:  Probably should stay at sub, but could be different depending on your situation. LDAP Filter:  I left mine blank, but you could provide one to limit what you want to see.  LDP would be helpful for determining what this is. LDAP Server Certificate Verification:  I left it checked, but didn’t try it without it being checked. Hopefully, this will save some others pain when trying to get Collabnet setup. Technorati Tags: Subversion,collabnet

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• Understanding Oracle Fusion Architecture and Fusion Middleware

  Podcasting from Oracle OpenWorld 'Applications Day,' SVP Applications Strategy Jesper Andersen and SVP Applications Technology Cliff Godwin jointly explain the components-based nature of Fusion Architecture, its Fusion Middleware underpinnings, and why Oracle customers (and non-customers) should care.

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• Metro: Understanding CSS Media Queries

  - by Stephen.Walther

  If you are building a Metro style application then your application needs to look great when used on a wide variety of devices. Your application needs to work on tiny little phones, slates, desktop monitors, and the super high resolution displays of the future. Your application also must support portable devices used with different orientations. If someone tilts their phone from portrait to landscape mode then your application must still be usable. Finally, your Metro style application must look great in different states. For example, your Metro application can be in a “snapped state” when it is shrunk so it can share screen real estate with another application. In this blog post, you learn how to use Cascading Style Sheet media queries to support different devices, different device orientations, and different application states. First, you are provided with an overview of the W3C Media Query recommendation and you learn how to detect standard media features. Next, you learn about the Microsoft extensions to media queries which are supported in Metro style applications. For example, you learn how to use the –ms-view-state feature to detect whether an application is in a “snapped state” or “fill state”. Finally, you learn how to programmatically detect the features of a device and the state of an application. You learn how to use the msMatchMedia() method to execute a media query with JavaScript. Using CSS Media Queries Media queries enable you to apply different styles depending on the features of a device. Media queries are not only supported by Metro style applications, most modern web browsers now support media queries including Google Chrome 4+, Mozilla Firefox 3.5+, Apple Safari 4+, and Microsoft Internet Explorer 9+. Loading Different Style Sheets with Media Queries Imagine, for example, that you want to display different content depending on the horizontal resolution of a device. In that case, you can load different style sheets optimized for different sized devices. Consider the following HTML page: <!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>U.S. Robotics and Mechanical Men</title> <link href="main.css" rel="stylesheet" type="text/css" /> <!-- Less than 1100px --> <link href="medium.css" rel="stylesheet" type="text/css" media="(max-width:1100px)" /> <!-- Less than 800px --> <link href="small.css" rel="stylesheet" type="text/css" media="(max-width:800px)" /> </head> <body> <div id="header"> <h1>U.S. Robotics and Mechanical Men</h1> </div> <!-- Advertisement Column --> <div id="leftColumn"> <img src="advertisement1.gif" alt="advertisement" /> <img src="advertisement2.jpg" alt="advertisement" /> </div> <!-- Product Search Form --> <div id="mainContentColumn"> <label>Search Products</label> <input id="search" /><button>Search</button> </div> <!-- Deal of the Day Column --> <div id="rightColumn"> <h1>Deal of the Day!</h1> <p> Buy two cameras and get a third camera for free! Offer is good for today only. </p> </div> </body> </html> The HTML page above contains three columns: a leftColumn, mainContentColumn, and rightColumn. When the page is displayed on a low resolution device, such as a phone, only the mainContentColumn appears: When the page is displayed in a medium resolution device, such as a slate, both the leftColumn and the mainContentColumns are displayed: Finally, when the page is displayed in a high-resolution device, such as a computer monitor, all three columns are displayed: Different content is displayed with the help of media queries. The page above contains three style sheet links. Two of the style links include a media attribute: <link href="main.css" rel="stylesheet" type="text/css" /> <!-- Less than 1100px --> <link href="medium.css" rel="stylesheet" type="text/css" media="(max-width:1100px)" /> <!-- Less than 800px --> <link href="small.css" rel="stylesheet" type="text/css" media="(max-width:800px)" /> The main.css style sheet contains default styles for the elements in the page. The medium.css style sheet is applied when the page width is less than 1100px. This style sheet hides the rightColumn and changes the page background color to lime: html { background-color: lime; } #rightColumn { display:none; } Finally, the small.css style sheet is loaded when the page width is less than 800px. This style sheet hides the leftColumn and changes the page background color to red: html { background-color: red; } #leftColumn { display:none; } The different style sheets are applied as you stretch and contract your browser window. You don’t need to refresh the page after changing the size of the page for a media query to be applied: Using the @media Rule You don’t need to divide your styles into separate files to take advantage of media queries. You can group styles by using the @media rule. For example, the following HTML page contains one set of styles which are applied when a device’s orientation is portrait and another set of styles when a device’s orientation is landscape: <!DOCTYPE html> <html> <head> <meta charset="utf-8" /> <title>Application1</title> <style type="text/css"> html { font-family:'Segoe UI Semilight'; font-size: xx-large; } @media screen and (orientation:landscape) { html { background-color: lime; } p.content { width: 50%; margin: auto; } } @media screen and (orientation:portrait) { html { background-color: red; } p.content { width: 90%; margin: auto; } } </style> </head> <body> <p class="content"> Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Maecenas porttitor congue massa. Fusce posuere, magna sed pulvinar ultricies, purus lectus malesuada libero, sit amet commodo magna eros quis urna. </p> </body> </html> When a device has a landscape orientation then the background color is set to the color lime and the text only takes up 50% of the available horizontal space: When the device has a portrait orientation then the background color is red and the text takes up 90% of the available horizontal space: Using Standard CSS Media Features The official list of standard media features is contained in the W3C CSS Media Query recommendation located here: http://www.w3.org/TR/css3-mediaqueries/ Here is the official list of the 13 media features described in the standard: · width – The current width of the viewport · height – The current height of the viewport · device-width – The width of the device · device-height – The height of the device · orientation – The value portrait or landscape · aspect-ratio – The ratio of width to height · device-aspect-ratio – The ratio of device width to device height · color – The number of bits per color supported by the device · color-index – The number of colors in the color lookup table of the device · monochrome – The number of bits in the monochrome frame buffer · resolution – The density of the pixels supported by the device · scan – The values progressive or interlace (used for TVs) · grid – The values 0 or 1 which indicate whether the device supports a grid or a bitmap Many of the media features in the list above support the min- and max- prefix. For example, you can test for the min-width using a query like this: (min-width:800px) You can use the logical and operator with media queries when you need to check whether a device supports more than one feature. For example, the following query returns true only when the width of the device is between 800 and 1,200 pixels: (min-width:800px) and (max-width:1200px) Finally, you can use the different media types – all, braille, embossed, handheld, print, projection, screen, speech, tty, tv — with a media query. For example, the following media query only applies to a page when a page is being printed in color: print and (color) If you don’t specify a media type then media type all is assumed. Using Metro Style Media Features Microsoft has extended the standard list of media features which you can include in a media query with two custom media features: · -ms-high-contrast – The values any, black-white, white-black · -ms-view-state – The values full-screen, fill, snapped, device-portrait You can take advantage of the –ms-high-contrast media feature to make your web application more accessible to individuals with disabilities. In high contrast mode, you should make your application easier to use for individuals with vision disabilities. The –ms-view-state media feature enables you to detect the state of an application. For example, when an application is snapped, the application only occupies part of the available screen real estate. The snapped application appears on the left or right side of the screen and the rest of the screen real estate is dominated by the fill application (Metro style applications can only be snapped on devices with a horizontal resolution of greater than 1,366 pixels). Here is a page which contains style rules for an application in both a snap and fill application state: <!DOCTYPE html> <html> <head> <meta charset="utf-8" /> <title>MyWinWebApp</title> <style type="text/css"> html { font-family:'Segoe UI Semilight'; font-size: xx-large; } @media screen and (-ms-view-state:snapped) { html { background-color: lime; } } @media screen and (-ms-view-state:fill) { html { background-color: red; } } </style> </head> <body> <p class="content"> Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Maecenas porttitor congue massa. Fusce posuere, magna sed pulvinar ultricies, purus lectus malesuada libero, sit amet commodo magna eros quis urna. </p> </body> </html> When the application is snapped, the application appears with a lime background color: When the application state is fill then the background color changes to red: When the application takes up the entire screen real estate – it is not in snapped or fill state – then no special style rules apply and the application appears with a white background color. Querying Media Features with JavaScript You can perform media queries using JavaScript by taking advantage of the window.msMatchMedia() method. This method returns a MSMediaQueryList which has a matches method that represents success or failure. For example, the following code checks whether the current device is in portrait mode: if (window.msMatchMedia("(orientation:portrait)").matches) { console.log("portrait"); } else { console.log("landscape"); } If the matches property returns true, then the device is in portrait mode and the message “portrait” is written to the Visual Studio JavaScript Console window. Otherwise, the message “landscape” is written to the JavaScript Console window. You can create an event listener which triggers code whenever the results of a media query changes. For example, the following code writes a message to the JavaScript Console whenever the current device is switched into or out of Portrait mode: window.msMatchMedia("(orientation:portrait)").addListener(function (mql) { if (mql.matches) { console.log("Switched to portrait"); } }); Be aware that the event listener is triggered whenever the result of the media query changes. So the event listener is triggered both when you switch from landscape to portrait and when you switch from portrait to landscape. For this reason, you need to verify that the matches property has the value true before writing the message. Summary The goal of this blog entry was to explain how CSS media queries work in the context of a Metro style application written with JavaScript. First, you were provided with an overview of the W3C CSS Media Query recommendation. You learned about the standard media features which you can query such as width and orientation. Next, we focused on the Microsoft extensions to media queries. You learned how to use –ms-view-state to detect whether a Metro style application is in “snapped” or “fill” state. You also learned how to use the msMatchMedia() method to perform a media query from JavaScript.

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• Understanding “Dispatcher” in WPF

  - by Pawan_Mishra

  Level : Beginner to intermediate Consider the following program MainWindow.xaml 1: < Window x:Class ="DispatcherTrial.MainWindow" 2: xmlns ="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 3: xmlns:x ="http://schemas.microsoft.com/winfx/2006/xaml" 4: Title ="MainWindow" Height ="350" Width ="525" > 5: < Grid > 6: < Grid.RowDefinitions > 7: < RowDefinition /> 8: < RowDefinition /> 9: </ Grid.RowDefinitions...(read more)

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• Understanding Oracle: Demystifying OpenWorld

  - by mseika

  Seminar: Wednesday 24th October 2012: Avnet, Bracknell Oracle OpenWorld is the world's largest event dedicated to helping enterprises harness the power of technology, during a full week in October. Oracle Corporation always uses Oracle OpenWorld to make its most important product announcements, and this year is no exception. We realise that not all our partners can attend this prestigious event in San Francisco, primarily due to time and cost pressures. Oracle OpenWorld is the only conference that goes this deep and wide with Oracle technology, providing thousands of sessions and hundreds of demonstrations geared toward helping partners and customers get better results with the technology it has —and plan strategically for the technology it will need to keep ahead of the competition in the years to come. With the sheer number of announcements planned, it is sometimes difficult to find your way through the fog and identify the opportunities relevant to your business to take advantage of, this coming year. So why not engage with the Oracle's UK team via Avnet and get the announcements shared with you face-to-face, in the UK? As a key Value Added Distributor of Oracle Applications, Technology and Hardware solutions, Avnet has been attending Oracle OpenWorld for a number of years and invites our partners to attend a half day summary event which will share the keynote announcements. We will also help prioritise for you the announcements of greatest interest and business opportunity for the UK channel. Agenda Time Module 12:00-13:15 Registration and lunch 13:15-14:00 Introductions and Key Hardware announcements Discover how Oracle's complete and integrated application-aware virtualization solutions, including virtualization for SPARC and x86 architectures, can help you gain better efficiencies across your business. Get updates on how Oracle storage products and solutions can accelerate database performance, improve application responsiveness, and meet your data protection needs. 14:00-14:15 Q&A and Break 14:15-15:00 Key Technology announcements Technology products, encompassing Oracle's Database 12c and Middleware, are revolutionizing the industry with record-breaking performance, helping customers consolidate onto private clouds and achieve high returns on investment. 15:00-15:15 Q&A and Break 15:15-16:00 Key Applications announcements Presentations focused on Oracle's strategy and vision for its applications business, including Oracle E-Business Suite; Oracle's PeopleSoft, JD Edwards, Siebel, Hyperion, and Agile products; and the newly available Oracle Fusion Applications. 16:00-16:30 Oracle-on-Oracle announcements & business opportunities with Avnet Learn about Oracle's cloud computing and Oracle-on-Oracle strategies and find out more about Oracle's engineered systems for the broad market 16:30 Close * Please note agenda may be subject to change What do you need to do now Register now or for more information email our Oracle events team at [email protected]. N.B. Places are limited, so please register early to avoid disappointment.

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• Metro: Understanding Observables

  - by Stephen.Walther

  The goal of this blog entry is to describe how the Observer Pattern is implemented in the WinJS library. You learn how to create observable objects which trigger notifications automatically when their properties are changed. Observables enable you to keep your user interface and your application data in sync. For example, by taking advantage of observables, you can update your user interface automatically whenever the properties of a product change. Observables are the foundation of declarative binding in the WinJS library. The WinJS library is not the first JavaScript library to include support for observables. For example, both the KnockoutJS library and the Microsoft Ajax Library (now part of the Ajax Control Toolkit) support observables. Creating an Observable Imagine that I have created a product object like this: var product = { name: "Milk", description: "Something to drink", price: 12.33 }; Nothing very exciting about this product. It has three properties named name, description, and price. Now, imagine that I want to be notified automatically whenever any of these properties are changed. In that case, I can create an observable product from my product object like this: var observableProduct = WinJS.Binding.as(product); This line of code creates a new JavaScript object named observableProduct from the existing JavaScript object named product. This new object also has a name, description, and price property. However, unlike the properties of the original product object, the properties of the observable product object trigger notifications when the properties are changed. Each of the properties of the new observable product object has been changed into accessor properties which have both a getter and a setter. For example, the observable product price property looks something like this: price: { get: function () { return this.getProperty(“price”); } set: function (value) { this.setProperty(“price”, value); } } When you read the price property then the getProperty() method is called and when you set the price property then the setProperty() method is called. The getProperty() and setProperty() methods are methods of the observable product object. The observable product object supports the following methods and properties: · addProperty(name, value) – Adds a new property to an observable and notifies any listeners. · backingData – An object which represents the value of each property. · bind(name, action) – Enables you to execute a function when a property changes. · getProperty(name) – Returns the value of a property using the string name of the property. · notify(name, newValue, oldValue) – A private method which executes each function in the _listeners array. · removeProperty(name) – Removes a property and notifies any listeners. · setProperty(name, value) – Updates a property and notifies any listeners. · unbind(name, action) – Enables you to stop executing a function in response to a property change. · updateProperty(name, value) – Updates a property and notifies any listeners. So when you create an observable, you get a new object with the same properties as an existing object. However, when you modify the properties of an observable object, then you can notify any listeners of the observable that the value of a particular property has changed automatically. Imagine that you change the value of the price property like this: observableProduct.price = 2.99; In that case, the following sequence of events is triggered: 1. The price setter calls the setProperty(“price”, 2.99) method 2. The setProperty() method updates the value of the backingData.price property and calls the notify() method 3. The notify() method executes each function in the collection of listeners associated with the price property Creating Observable Listeners If you want to be notified when a property of an observable object is changed, then you need to register a listener. You register a listener by using the bind() method like this: (function () { "use strict"; var app = WinJS.Application; app.onactivated = function (eventObject) { if (eventObject.detail.kind === Windows.ApplicationModel.Activation.ActivationKind.launch) { // Simple product object var product = { name: "Milk", description: "Something to drink", price: 12.33 }; // Create observable product var observableProduct = WinJS.Binding.as(product); // Execute a function when price is changed observableProduct.bind("price", function (newValue) { console.log(newValue); }); // Change the price observableProduct.price = 2.99; } }; app.start(); })(); In the code above, the bind() method is used to associate the price property with a function. When the price property is changed, the function logs the new value of the price property to the Visual Studio JavaScript console. The price property is associated with the function using the following line of code: // Execute a function when price is changed observableProduct.bind("price", function (newValue) { console.log(newValue); }); Coalescing Notifications If you make multiple changes to a property – one change immediately following another – then separate notifications won’t be sent. Instead, any listeners are notified only once. The notifications are coalesced into a single notification. For example, in the following code, the product price property is updated three times. However, only one message is written to the JavaScript console. Only the last value assigned to the price property is written to the JavaScript Console window: // Simple product object var product = { name: "Milk", description: "Something to drink", price: 12.33 }; // Create observable product var observableProduct = WinJS.Binding.as(product); // Execute a function when price is changed observableProduct.bind("price", function (newValue) { console.log(newValue); }); // Change the price observableProduct.price = 3.99; observableProduct.price = 2.99; observableProduct.price = 1.99; Only the last value assigned to price, the value 1.99, appears in the console: If there is a time delay between changes to a property then changes result in different notifications. For example, the following code updates the price property every second: // Simple product object var product = { name: "Milk", description: "Something to drink", price: 12.33 }; // Create observable product var observableProduct = WinJS.Binding.as(product); // Execute a function when price is changed observableProduct.bind("price", function (newValue) { console.log(newValue); }); // Add 1 to price every second window.setInterval(function () { observableProduct.price += 1; }, 1000); In this case, separate notification messages are logged to the JavaScript Console window: If you need to prevent multiple notifications from being coalesced into one then you can take advantage of promises. I discussed WinJS promises in a previous blog entry: http://stephenwalther.com/blog/archive/2012/02/22/windows-web-applications-promises.aspx Because the updateProperty() method returns a promise, you can create different notifications for each change in a property by using the following code: // Change the price observableProduct.updateProperty("price", 3.99) .then(function () { observableProduct.updateProperty("price", 2.99) .then(function () { observableProduct.updateProperty("price", 1.99); }); }); In this case, even though the price is immediately changed from 3.99 to 2.99 to 1.99, separate notifications for each new value of the price property are sent. Bypassing Notifications Normally, if a property of an observable object has listeners and you change the property then the listeners are notified. However, there are certain situations in which you might want to bypass notification. In other words, you might need to change a property value silently without triggering any functions registered for notification. If you want to change a property without triggering notifications then you should change the property by using the backingData property. The following code illustrates how you can change the price property silently: // Simple product object var product = { name: "Milk", description: "Something to drink", price: 12.33 }; // Create observable product var observableProduct = WinJS.Binding.as(product); // Execute a function when price is changed observableProduct.bind("price", function (newValue) { console.log(newValue); }); // Change the price silently observableProduct.backingData.price = 5.99; console.log(observableProduct.price); // Writes 5.99 The price is changed to the value 5.99 by changing the value of backingData.price. Because the observableProduct.price property is not set directly, any listeners associated with the price property are not notified. When you change the value of a property by using the backingData property, the change in the property happens synchronously. However, when you change the value of an observable property directly, the change is always made asynchronously. Summary The goal of this blog entry was to describe observables. In particular, we discussed how to create observables from existing JavaScript objects and bind functions to observable properties. You also learned how notifications are coalesced (and ways to prevent this coalescing). Finally, we discussed how you can use the backingData property to update an observable property without triggering notifications. In the next blog entry, we’ll see how observables are used with declarative binding to display the values of properties in an HTML document.

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• SQL SERVER – Understanding XML – Contest Win Joes 2 Pros Combo (USD 198) – Day 5 of 5

  - by pinaldave

  August 2011 we ran a contest where every day we give away one book for an entire month. The contest had extreme success. Lots of people participated and lots of give away. I have received lots of questions if we are doing something similar this month. Absolutely, instead of running a contest a month long we are doing something more interesting. We are giving away USD 198 worth gift every day for this week. We are giving away Joes 2 Pros 5 Volumes (BOOK) SQL 2008 Development Certification Training Kit every day. One copy in India and One in USA. Total 2 of the giveaway (worth USD 198). All the gifts are sponsored from the Koenig Training Solution and Joes 2 Pros. The books are available here Amazon | Flipkart | Indiaplaza How to Win: Read the Question Read the Hints Answer the Quiz in Contact Form in following format Question Answer Name of the country (The contest is open for USA and India residents only) 2 Winners will be randomly selected announced on August 20th. Question of the Day: Is following XML a well formed XML Document? <?xml version=”1.0″?> <address> <firstname>Pinal</firstname> <lastname>Dave</lastname> <title>Founder</title> <company>SQLAuthority.com</company> </address> a) Yes b) No c) I do not know Query Hints: BIG HINT POST A common observation by people seeing an XML file for the first time is that it looks like just a bunch of data inside a text file. XML files are text-based documents, which makes them easy to read.  All of the data is literally spelled out in the document and relies on a just a few characters (<, >, =) to convey relationships and structure of the data.  XML files can be used by any commonly available text editor, like Notepad. Much like a book’s Table of Contents, your first glance at well-formed XML will tell you the subject matter of the data and its general structure. Hints appearing within the data help you to quickly identify the main theme (similar to book’s subject), its headers (similar to chapter titles or sections of a book), data elements (similar to a book’s characters or chief topics), and so forth. We’ll learn to recognize and use the structural “hints,” which are XML’s markup components (e.g., XML tags, root elements). The XML Raw and Auto modes are great for displaying data as all attributes or all elements – but not both at once. If you want your XML stream to have some of its data shown in attributes and some shown as elements, then you can use the XML Path mode. If you are using an XML Path stream, then by default all values will be shown as elements. However, it is possible to pick one or more elements to be shown with an attribute(s) as well. Additional Hints: I have previously discussed various concepts from SQL Server Joes 2 Pros Volume 5. SQL Joes 2 Pros Development Series – OpenXML Options SQL Joes 2 Pros Development Series – Preparing XML in Memory SQL Joes 2 Pros Development Series – Shredding XML SQL Joes 2 Pros Development Series – Using Root With Auto XML Mode SQL Joes 2 Pros Development Series – Using Root With Auto XML Mode SQL Joes 2 Pros Development Series – What is XML? SQL Joes 2 Pros Development Series – What is XML? – 2 Next Step: Answer the Quiz in Contact Form in following format Question - Answer Name of the country (The contest is open for USA and India) Bonus Winner Leave a comment with your favorite article from the “additional hints” section and you may be eligible for surprise gift. There is no country restriction for this Bonus Contest. Do mention why you liked it any particular blog post and I will announce the winner of the same along with the main contest. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Joes 2 Pros, PostADay, SQL, SQL Authority, SQL Puzzle, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• Understanding Regression Analysis

  A ubiquitous tool of scientific research Statistics - Math - Regression and Curve Fitting - Organizations - Research Groups and Centers

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• Understanding node.js: some real-life examples

  - by steweb

  Hi all! As a curious web developer I've been hearing about node.js for several months and (just) now I'd like to learn it and, most of all, understand its "engine". So, as a real newbie about node.js I'm going to follow some tutorials. And as every new technology over the internet, find a very good and exhaustive tutorial is like looking for a needle in a haystack :) My "big question" can be split into this 3 sub-questions: I know node.js can be very useful to build web-chats. But, apart from this example (and from helloworld one :D), how could I use it? Which are the real-life examples that let me think i.e. "oh, it's fantastic, I could really integrate it for my daily projects"? I also know it implements some JS specifications. It is required to deeply know other programming languages apart from JS? Where can I find a good reference (basically, I don't want to search "node.js reference" on google hoping to be lucky enough to get some good websites)? Thanks everyone!

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• Understanding G1 GC Logs

  - by poonam

  The purpose of this post is to explain the meaning of GC logs generated with some tracing and diagnostic options for G1 GC. We will take a look at the output generated with PrintGCDetails which is a product flag and provides the most detailed level of information. Along with that, we will also look at the output of two diagnostic flags that get enabled with -XX:+UnlockDiagnosticVMOptions option - G1PrintRegionLivenessInfo that prints the occupancy and the amount of space used by live objects in each region at the end of the marking cycle and G1PrintHeapRegions that provides detailed information on the heap regions being allocated and reclaimed. We will be looking at the logs generated with JDK 1.7.0_04 using these options. Option -XX:+PrintGCDetails Here's a sample log of G1 collection generated with PrintGCDetails. 0.522: [GC pause (young), 0.15877971 secs] [Parallel Time: 157.1 ms] [GC Worker Start (ms): 522.1 522.2 522.2 522.2 Avg: 522.2, Min: 522.1, Max: 522.2, Diff: 0.1] [Ext Root Scanning (ms): 1.6 1.5 1.6 1.9 Avg: 1.7, Min: 1.5, Max: 1.9, Diff: 0.4] [Update RS (ms): 38.7 38.8 50.6 37.3 Avg: 41.3, Min: 37.3, Max: 50.6, Diff: 13.3] [Processed Buffers : 2 2 3 2 Sum: 9, Avg: 2, Min: 2, Max: 3, Diff: 1] [Scan RS (ms): 9.9 9.7 0.0 9.7 Avg: 7.3, Min: 0.0, Max: 9.9, Diff: 9.9] [Object Copy (ms): 106.7 106.8 104.6 107.9 Avg: 106.5, Min: 104.6, Max: 107.9, Diff: 3.3] [Termination (ms): 0.0 0.0 0.0 0.0 Avg: 0.0, Min: 0.0, Max: 0.0, Diff: 0.0] [Termination Attempts : 1 4 4 6 Sum: 15, Avg: 3, Min: 1, Max: 6, Diff: 5] [GC Worker End (ms): 679.1 679.1 679.1 679.1 Avg: 679.1, Min: 679.1, Max: 679.1, Diff: 0.1] [GC Worker (ms): 156.9 157.0 156.9 156.9 Avg: 156.9, Min: 156.9, Max: 157.0, Diff: 0.1] [GC Worker Other (ms): 0.3 0.3 0.3 0.3 Avg: 0.3, Min: 0.3, Max: 0.3, Diff: 0.0] [Clear CT: 0.1 ms] [Other: 1.5 ms] [Choose CSet: 0.0 ms] [Ref Proc: 0.3 ms] [Ref Enq: 0.0 ms] [Free CSet: 0.3 ms] [Eden: 12M(12M)->0B(10M) Survivors: 0B->2048K Heap: 13M(64M)->9739K(64M)] [Times: user=0.59 sys=0.02, real=0.16 secs] This is the typical log of an Evacuation Pause (G1 collection) in which live objects are copied from one set of regions (young OR young+old) to another set. It is a stop-the-world activity and all the application threads are stopped at a safepoint during this time. This pause is made up of several sub-tasks indicated by the indentation in the log entries. Here's is the top most line that gets printed for the Evacuation Pause. 0.522: [GC pause (young), 0.15877971 secs] This is the highest level information telling us that it is an Evacuation Pause that started at 0.522 secs from the start of the process, in which all the regions being evacuated are Young i.e. Eden and Survivor regions. This collection took 0.15877971 secs to finish. Evacuation Pauses can be mixed as well. In which case the set of regions selected include all of the young regions as well as some old regions. 1.730: [GC pause (mixed), 0.32714353 secs] Let's take a look at all the sub-tasks performed in this Evacuation Pause. [Parallel Time: 157.1 ms] Parallel Time is the total elapsed time spent by all the parallel GC worker threads. The following lines correspond to the parallel tasks performed by these worker threads in this total parallel time, which in this case is 157.1 ms. [GC Worker Start (ms): 522.1 522.2 522.2 522.2Avg: 522.2, Min: 522.1, Max: 522.2, Diff: 0.1] The first line tells us the start time of each of the worker thread in milliseconds. The start times are ordered with respect to the worker thread ids – thread 0 started at 522.1ms and thread 1 started at 522.2ms from the start of the process. The second line tells the Avg, Min, Max and Diff of the start times of all of the worker threads. [Ext Root Scanning (ms): 1.6 1.5 1.6 1.9 Avg: 1.7, Min: 1.5, Max: 1.9, Diff: 0.4] This gives us the time spent by each worker thread scanning the roots (globals, registers, thread stacks and VM data structures). Here, thread 0 took 1.6ms to perform the root scanning task and thread 1 took 1.5 ms. The second line clearly shows the Avg, Min, Max and Diff of the times spent by all the worker threads. [Update RS (ms): 38.7 38.8 50.6 37.3 Avg: 41.3, Min: 37.3, Max: 50.6, Diff: 13.3] Update RS gives us the time each thread spent in updating the Remembered Sets. Remembered Sets are the data structures that keep track of the references that point into a heap region. Mutator threads keep changing the object graph and thus the references that point into a particular region. We keep track of these changes in buffers called Update Buffers. The Update RS sub-task processes the update buffers that were not able to be processed concurrently, and updates the corresponding remembered sets of all regions. [Processed Buffers : 2 2 3 2Sum: 9, Avg: 2, Min: 2, Max: 3, Diff: 1] This tells us the number of Update Buffers (mentioned above) processed by each worker thread. [Scan RS (ms): 9.9 9.7 0.0 9.7 Avg: 7.3, Min: 0.0, Max: 9.9, Diff: 9.9] These are the times each worker thread had spent in scanning the Remembered Sets. Remembered Set of a region contains cards that correspond to the references pointing into that region. This phase scans those cards looking for the references pointing into all the regions of the collection set. [Object Copy (ms): 106.7 106.8 104.6 107.9 Avg: 106.5, Min: 104.6, Max: 107.9, Diff: 3.3] These are the times spent by each worker thread copying live objects from the regions in the Collection Set to the other regions. [Termination (ms): 0.0 0.0 0.0 0.0 Avg: 0.0, Min: 0.0, Max: 0.0, Diff: 0.0] Termination time is the time spent by the worker thread offering to terminate. But before terminating, it checks the work queues of other threads and if there are still object references in other work queues, it tries to steal object references, and if it succeeds in stealing a reference, it processes that and offers to terminate again. [Termination Attempts : 1 4 4 6 Sum: 15, Avg: 3, Min: 1, Max: 6, Diff: 5] This gives the number of times each thread has offered to terminate. [GC Worker End (ms): 679.1 679.1 679.1 679.1 Avg: 679.1, Min: 679.1, Max: 679.1, Diff: 0.1] These are the times in milliseconds at which each worker thread stopped. [GC Worker (ms): 156.9 157.0 156.9 156.9 Avg: 156.9, Min: 156.9, Max: 157.0, Diff: 0.1] These are the total lifetimes of each worker thread. [GC Worker Other (ms): 0.3 0.3 0.3 0.3Avg: 0.3, Min: 0.3, Max: 0.3, Diff: 0.0] These are the times that each worker thread spent in performing some other tasks that we have not accounted above for the total Parallel Time. [Clear CT: 0.1 ms] This is the time spent in clearing the Card Table. This task is performed in serial mode. [Other: 1.5 ms] Time spent in the some other tasks listed below. The following sub-tasks (which individually may be parallelized) are performed serially. [Choose CSet: 0.0 ms] Time spent in selecting the regions for the Collection Set. [Ref Proc: 0.3 ms] Total time spent in processing Reference objects. [Ref Enq: 0.0 ms] Time spent in enqueuing references to the ReferenceQueues. [Free CSet: 0.3 ms] Time spent in freeing the collection set data structure. [Eden: 12M(12M)->0B(13M) Survivors: 0B->2048K Heap: 14M(64M)->9739K(64M)] This line gives the details on the heap size changes with the Evacuation Pause. This shows that Eden had the occupancy of 12M and its capacity was also 12M before the collection. After the collection, its occupancy got reduced to 0 since everything is evacuated/promoted from Eden during a collection, and its target size grew to 13M. The new Eden capacity of 13M is not reserved at this point. This value is the target size of the Eden. Regions are added to Eden as the demand is made and when the added regions reach to the target size, we start the next collection. Similarly, Survivors had the occupancy of 0 bytes and it grew to 2048K after the collection. The total heap occupancy and capacity was 14M and 64M receptively before the collection and it became 9739K and 64M after the collection. Apart from the evacuation pauses, G1 also performs concurrent-marking to build the live data information of regions. 1.416: [GC pause (young) (initial-mark), 0.62417980 secs] ….... 2.042: [GC concurrent-root-region-scan-start] 2.067: [GC concurrent-root-region-scan-end, 0.0251507] 2.068: [GC concurrent-mark-start] 3.198: [GC concurrent-mark-reset-for-overflow] 4.053: [GC concurrent-mark-end, 1.9849672 sec] 4.055: [GC remark 4.055: [GC ref-proc, 0.0000254 secs], 0.0030184 secs] [Times: user=0.00 sys=0.00, real=0.00 secs] 4.088: [GC cleanup 117M->106M(138M), 0.0015198 secs] [Times: user=0.00 sys=0.00, real=0.00 secs] 4.090: [GC concurrent-cleanup-start] 4.091: [GC concurrent-cleanup-end, 0.0002721] The first phase of a marking cycle is Initial Marking where all the objects directly reachable from the roots are marked and this phase is piggy-backed on a fully young Evacuation Pause. 2.042: [GC concurrent-root-region-scan-start] This marks the start of a concurrent phase that scans the set of root-regions which are directly reachable from the survivors of the initial marking phase. 2.067: [GC concurrent-root-region-scan-end, 0.0251507] End of the concurrent root region scan phase and it lasted for 0.0251507 seconds. 2.068: [GC concurrent-mark-start] Start of the concurrent marking at 2.068 secs from the start of the process. 3.198: [GC concurrent-mark-reset-for-overflow] This indicates that the global marking stack had became full and there was an overflow of the stack. Concurrent marking detected this overflow and had to reset the data structures to start the marking again. 4.053: [GC concurrent-mark-end, 1.9849672 sec] End of the concurrent marking phase and it lasted for 1.9849672 seconds. 4.055: [GC remark 4.055: [GC ref-proc, 0.0000254 secs], 0.0030184 secs] This corresponds to the remark phase which is a stop-the-world phase. It completes the left over marking work (SATB buffers processing) from the previous phase. In this case, this phase took 0.0030184 secs and out of which 0.0000254 secs were spent on Reference processing. 4.088: [GC cleanup 117M->106M(138M), 0.0015198 secs] Cleanup phase which is again a stop-the-world phase. It goes through the marking information of all the regions, computes the live data information of each region, resets the marking data structures and sorts the regions according to their gc-efficiency. In this example, the total heap size is 138M and after the live data counting it was found that the total live data size dropped down from 117M to 106M. 4.090: [GC concurrent-cleanup-start] This concurrent cleanup phase frees up the regions that were found to be empty (didn't contain any live data) during the previous stop-the-world phase. 4.091: [GC concurrent-cleanup-end, 0.0002721] Concurrent cleanup phase took 0.0002721 secs to free up the empty regions. Option -XX:G1PrintRegionLivenessInfo Now, let's look at the output generated with the flag G1PrintRegionLivenessInfo. This is a diagnostic option and gets enabled with -XX:+UnlockDiagnosticVMOptions. G1PrintRegionLivenessInfo prints the live data information of each region during the Cleanup phase of the concurrent-marking cycle. 26.896: [GC cleanup ### PHASE Post-Marking @ 26.896### HEAP committed: 0x02e00000-0x0fe00000 reserved: 0x02e00000-0x12e00000 region-size: 1048576 Cleanup phase of the concurrent-marking cycle started at 26.896 secs from the start of the process and this live data information is being printed after the marking phase. Committed G1 heap ranges from 0x02e00000 to 0x0fe00000 and the total G1 heap reserved by JVM is from 0x02e00000 to 0x12e00000. Each region in the G1 heap is of size 1048576 bytes. ### type address-range used prev-live next-live gc-eff### (bytes) (bytes) (bytes) (bytes/ms) This is the header of the output that tells us about the type of the region, address-range of the region, used space in the region, live bytes in the region with respect to the previous marking cycle, live bytes in the region with respect to the current marking cycle and the GC efficiency of that region. ### FREE 0x02e00000-0x02f00000 0 0 0 0.0 This is a Free region. ### OLD 0x02f00000-0x03000000 1048576 1038592 1038592 0.0 Old region with address-range from 0x02f00000 to 0x03000000. Total used space in the region is 1048576 bytes, live bytes as per the previous marking cycle are 1038592 and live bytes with respect to the current marking cycle are also 1038592. The GC efficiency has been computed as 0. ### EDEN 0x03400000-0x03500000 20992 20992 20992 0.0 This is an Eden region. ### HUMS 0x0ae00000-0x0af00000 1048576 1048576 1048576 0.0### HUMC 0x0af00000-0x0b000000 1048576 1048576 1048576 0.0### HUMC 0x0b000000-0x0b100000 1048576 1048576 1048576 0.0### HUMC 0x0b100000-0x0b200000 1048576 1048576 1048576 0.0### HUMC 0x0b200000-0x0b300000 1048576 1048576 1048576 0.0### HUMC 0x0b300000-0x0b400000 1048576 1048576 1048576 0.0### HUMC 0x0b400000-0x0b500000 1001480 1001480 1001480 0.0 These are the continuous set of regions called Humongous regions for storing a large object. HUMS (Humongous starts) marks the start of the set of humongous regions and HUMC (Humongous continues) tags the subsequent regions of the humongous regions set. ### SURV 0x09300000-0x09400000 16384 16384 16384 0.0 This is a Survivor region. ### SUMMARY capacity: 208.00 MB used: 150.16 MB / 72.19 % prev-live: 149.78 MB / 72.01 % next-live: 142.82 MB / 68.66 % At the end, a summary is printed listing the capacity, the used space and the change in the liveness after the completion of concurrent marking. In this case, G1 heap capacity is 208MB, total used space is 150.16MB which is 72.19% of the total heap size, live data in the previous marking was 149.78MB which was 72.01% of the total heap size and the live data as per the current marking is 142.82MB which is 68.66% of the total heap size. Option -XX:+G1PrintHeapRegions G1PrintHeapRegions option logs the regions related events when regions are committed, allocated into or are reclaimed. COMMIT/UNCOMMIT events G1HR COMMIT [0x6e900000,0x6ea00000]G1HR COMMIT [0x6ea00000,0x6eb00000] Here, the heap is being initialized or expanded and the region (with bottom: 0x6eb00000 and end: 0x6ec00000) is being freshly committed. COMMIT events are always generated in order i.e. the next COMMIT event will always be for the uncommitted region with the lowest address. G1HR UNCOMMIT [0x72700000,0x72800000]G1HR UNCOMMIT [0x72600000,0x72700000] Opposite to COMMIT. The heap got shrunk at the end of a Full GC and the regions are being uncommitted. Like COMMIT, UNCOMMIT events are also generated in order i.e. the next UNCOMMIT event will always be for the committed region with the highest address. GC Cycle events G1HR #StartGC 7G1HR CSET 0x6e900000G1HR REUSE 0x70500000G1HR ALLOC(Old) 0x6f800000G1HR RETIRE 0x6f800000 0x6f821b20G1HR #EndGC 7 This shows start and end of an Evacuation pause. This event is followed by a GC counter tracking both evacuation pauses and Full GCs. Here, this is the 7th GC since the start of the process. G1HR #StartFullGC 17G1HR UNCOMMIT [0x6ed00000,0x6ee00000]G1HR POST-COMPACTION(Old) 0x6e800000 0x6e854f58G1HR #EndFullGC 17 Shows start and end of a Full GC. This event is also followed by the same GC counter as above. This is the 17th GC since the start of the process. ALLOC events G1HR ALLOC(Eden) 0x6e800000 The region with bottom 0x6e800000 just started being used for allocation. In this case it is an Eden region and allocated into by a mutator thread. G1HR ALLOC(StartsH) 0x6ec00000 0x6ed00000G1HR ALLOC(ContinuesH) 0x6ed00000 0x6e000000 Regions being used for the allocation of Humongous object. The object spans over two regions. G1HR ALLOC(SingleH) 0x6f900000 0x6f9eb010 Single region being used for the allocation of Humongous object. G1HR COMMIT [0x6ee00000,0x6ef00000]G1HR COMMIT [0x6ef00000,0x6f000000]G1HR COMMIT [0x6f000000,0x6f100000]G1HR COMMIT [0x6f100000,0x6f200000]G1HR ALLOC(StartsH) 0x6ee00000 0x6ef00000G1HR ALLOC(ContinuesH) 0x6ef00000 0x6f000000G1HR ALLOC(ContinuesH) 0x6f000000 0x6f100000G1HR ALLOC(ContinuesH) 0x6f100000 0x6f102010 Here, Humongous object allocation request could not be satisfied by the free committed regions that existed in the heap, so the heap needed to be expanded. Thus new regions are committed and then allocated into for the Humongous object. G1HR ALLOC(Old) 0x6f800000 Old region started being used for allocation during GC. G1HR ALLOC(Survivor) 0x6fa00000 Region being used for copying old objects into during a GC. Note that Eden and Humongous ALLOC events are generated outside the GC boundaries and Old and Survivor ALLOC events are generated inside the GC boundaries. Other Events G1HR RETIRE 0x6e800000 0x6e87bd98 Retire and stop using the region having bottom 0x6e800000 and top 0x6e87bd98 for allocation. Note that most regions are full when they are retired and we omit those events to reduce the output volume. A region is retired when another region of the same type is allocated or we reach the start or end of a GC(depending on the region). So for Eden regions: For example: 1. ALLOC(Eden) Foo2. ALLOC(Eden) Bar3. StartGC At point 2, Foo has just been retired and it was full. At point 3, Bar was retired and it was full. If they were not full when they were retired, we will have a RETIRE event: 1. ALLOC(Eden) Foo2. RETIRE Foo top3. ALLOC(Eden) Bar4. StartGC G1HR CSET 0x6e900000 Region (bottom: 0x6e900000) is selected for the Collection Set. The region might have been selected for the collection set earlier (i.e. when it was allocated). However, we generate the CSET events for all regions in the CSet at the start of a GC to make sure there's no confusion about which regions are part of the CSet. G1HR POST-COMPACTION(Old) 0x6e800000 0x6e839858 POST-COMPACTION event is generated for each non-empty region in the heap after a full compaction. A full compaction moves objects around, so we don't know what the resulting shape of the heap is (which regions were written to, which were emptied, etc.). To deal with this, we generate a POST-COMPACTION event for each non-empty region with its type (old/humongous) and the heap boundaries. At this point we should only have Old and Humongous regions, as we have collapsed the young generation, so we should not have eden and survivors. POST-COMPACTION events are generated within the Full GC boundary. G1HR CLEANUP 0x6f400000G1HR CLEANUP 0x6f300000G1HR CLEANUP 0x6f200000 These regions were found empty after remark phase of Concurrent Marking and are reclaimed shortly afterwards. G1HR #StartGC 5G1HR CSET 0x6f400000G1HR CSET 0x6e900000G1HR REUSE 0x6f800000 At the end of a GC we retire the old region we are allocating into. Given that its not full, we will carry on allocating into it during the next GC. This is what REUSE means. In the above case 0x6f800000 should have been the last region with an ALLOC(Old) event during the previous GC and should have been retired before the end of the previous GC. G1HR ALLOC-FORCE(Eden) 0x6f800000 A specialization of ALLOC which indicates that we have reached the max desired number of the particular region type (in this case: Eden), but we decided to allocate one more. Currently it's only used for Eden regions when we extend the young generation because we cannot do a GC as the GC-Locker is active. G1HR EVAC-FAILURE 0x6f800000 During a GC, we have failed to evacuate an object from the given region as the heap is full and there is no space left to copy the object. This event is generated within GC boundaries and exactly once for each region from which we failed to evacuate objects. When Heap Regions are reclaimed ? It is also worth mentioning when the heap regions in the G1 heap are reclaimed. All regions that are in the CSet (the ones that appear in CSET events) are reclaimed at the end of a GC. The exception to that are regions with EVAC-FAILURE events. All regions with CLEANUP events are reclaimed. After a Full GC some regions get reclaimed (the ones from which we moved the objects out). But that is not shown explicitly, instead the non-empty regions that are left in the heap are printed out with the POST-COMPACTION events.

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• Business/Development Liaison Wanting To Enhance Understanding In Programming

  - by James Alexander

  I lead software development for a team of of about 20 devs and we're primarily a .net/sql server shop. We've recently created a new role in our organization for a more business like role to assist in prioritization of development and this business liaison has asked me if there are any books or resources he could use to better understand software concepts in a meaningful way. Any suggestions or advice would be greatly appreciated.

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• Understanding DeviceContext and Shaders in Direct3D/SlimDX

  - by Carson Myers

  I've been working through this tutorial about drawing triangles with SlimDX, and while it works, I've been trying to structure my program differently than in the tutorial. The tutorial just has everything in the main method, I'm trying to separate components into their own classes. But I'm not sure where certain components belong: namely, contexts and shaders. The tutorial (as it's just rendering one triangle) has one device, one swapchain, one device context and one set of shaders. intuition says that there is only one device/swapchain for one game, but with contexts I don't know. I made a Triangle class and put the vertex stuff in there. Should it also create a context? Should it load its own shaders? Or should I pass some global context and shaders to the triangle class when it is constructed? Or pass the shaders and construct a new context? I'm just getting started with 3D programming, so in addition to answering this question, if anyone knows of a tutorial or article or something about the larger-scale structure of a game, I'd be interested in seeing that as well.

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• Understanding Column Properties for a SQL Server Table

  Designing a table can be a little complicated if you don’t have the correct knowledge of data types, relationships, and even column properties. In this tip, Brady Upton goes over the column properties and provides examples. "It really helped us isolate where we were experiencing a bottleneck"- John Q Martin, SQL Server DBA. Get started with SQL Monitor today to solve tricky performance problems - download a free trial

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• Understanding Process Scheduling in Oracle Solaris

  - by rickramsey

  The process scheduler in the Oracle Solaris kernel allocates CPU resources to processes. By default, the scheduler tries to give every process relatively equal access to the available CPUs. However, you might want to specify that certain processes be given more resources than others. That's where classes come in. A process class defines a scheduling policy for a set of processes. These three resources will help you understand and manage it process classes: Blog: Overview of Process Scheduling Classes in the Oracle Solaris Kernel by Brian Bream Timesharing, interactive, fair-share scheduler, fixed priority, system, and real time. What are these? Scheduling classes in the Solaris kernel. Brian Bream describes them and how the kernel manages them through context switching. Blog: Process Scheduling at the Thread Level by Brian Bream The Fair Share Scheduler allows you to dispatch processes not just to a particular CPU, but to CPU threads. Brian Bream explains how to use and provides examples. Docs: Overview of the Fair Share Scheduler by Oracle Solaris Documentation Team This official Oracle Solaris documentation set provides the nitty-gritty details for setting up classes and managing your processes. Covers: Introduction to the Scheduler CPU Share Definition CPU Shares and Process State CPU Share Versus Utilization CPU Share Examples FSS Configuration FSS and Processor Sets Combining FSS With Other Scheduling Classes Setting the Scheduling Class for the System Scheduling Class on a System with Zones Installed Commands Used With FSS -Rick Follow me on: Blog | Facebook | Twitter | Personal Twitter | YouTube | The Great Peruvian Novel

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• Understanding the value of Customer Experience & Loyalty for the Telecommunications Industry

  - by raul.goycoolea

  Worried by economic woes and market forces, especially in mature markets, communications service providers (CSPs) increasingly focus on improving customer experience. In fact, it seems difficult to find a major message by a C-level executive in the developed world that does not include something on "meeting and exceeding customers' needs". Frequently in customer satisfaction studies by prominent firms, CSPs fall short of the leadership demonstrated by other industries that take customer-centric approaches to their bottom-line strategies. Consider the following:Despite the continued impact of global economic crisis, in July 2010, Apple Computer posted record revenue and net quarterly profit. Those who attribute the results primarily to the iPhone 4 launch should note that Apple also shipped around 30% more Macintosh computers than the same period the previous year. Even sales of the iPod line increased by 8% in a highly commoditized, shrinking media player market. Finally, Apple began selling iPads during the quarter, with total sales of more than 3 million units. What does Apple have that the others lack? Well, some great products (and services) to be sure, but it also excels at customer service and support, marketing, and distribution, and has one of the strongest brands globally. Its products are useful, simple to use, easy to acquire and augment, high quality, and considered very cool. They also evoke such an emotional response from many of Apple's customers, which they turn up their noses at competitive products.In other words, Apple appears to have mastered virtually every aspect of customer experience and the resultant loyalty of its customer base - even in difficult financial times. Through that unwavering customer focus, Apple continues to drive its revenues and profits to new heights. Other customer loyalty leaders like Wal-Mart, Google, Toyota and Honda are also doing well by focusing on customer experience as an essential driver of profitability. Service providers should note this performance and ask themselves how they might leverage the same principles to increase their own profitability. After all, that is what customer experience and loyalty are all about: profitability.To successfully manage all the critical touch points of customer experience, CSPs must shun the one-size-fits-all approach. They can no longer afford to view customer service fundamentally as an act of altruism - which mentality dates back to the industry's civil service days, when CSPs were typically government organizations that were critical to economic development and public safety.As regulators and public officials have pushed, and continue to push, service providers to new heights of reliability - using incentives and punishments - most CSPs already have some of the fundamental building blocks of customer service in place. Yet despite that history and experience, service providers still lag other industries in providing what is seen as good customer service.As we observed in the TMF's 2009 Insights Research report, Customer Experience Management: Driving Loyalty & Profitability there has been resurgence in interest by CSPs. More and more of them have stated ambitions to catch up other industries, and they are realizing that good customer service is a powerful strategy for increasing business performance and profitability, not an act of good will.CSPs are recognizing the connection between customer experience and profitability, as demonstrated in many studies. For example, according to research by Bain & Company, a 5 percent improvement in customer retention rates can yield as much as a 75 percent increase in profits for companies across a range of industries.After decades of customer experience strategy formulation, Bain partner and business author, Frederick Reichheld, considers "would you recommend us to a friend?" as the ultimate question for a customer. How many times have you or your friends recommended an iPod, iPhone or a Mac? What do your children recommend to their peers? Their peers to them?There are certain steps service providers have to take to create more personalized relationships with their customers, as well as reduce churn and increase profitability, all while becoming leaner and more agile. First, they have to define customer experience, we define it as the result of the sum of observations, perceptions, thoughts and feelings arising from interactions and relationships between customers and their service provider(s). Virtually every customer touch point - whether directly or indirectly linked to service providers and their partners - contributes to customer perception, satisfaction, loyalty, and ultimately profitability. Gaining leadership in customer experience and satisfaction will not be a simple task, as it is affected by virtually every customer-facing aspect of the service provider, and in turn impacts the service provider deeply - especially on the all-important bottom line. The scope of issues affecting customer experience is complex and dynamic.With new services, devices and applications extending the basis of customer experience to domains beyond the direct control of the service provider, it is likely to increase in complexity and dynamism.Customer loyalty = increased profitsAs stated earlier, customer experience programs are not fundamentally altruistic exercises, but a strategic means of improving competitiveness and profitability in the short and long term. Loyalty is essential to deriving long term profits from customers.Some of the earliest loyalty programs date back to the 1930s, when packaged goods companies offered embedded coupons for rewards to buyers, and eventually retail chains began offering reward programs to frequent shoppers. These programs continued for decades but were leapfrogged in the 1980s by more aggressive programs from the airlines.This movement was led by American Airlines, which launched the first full-scale loyalty marketing program of the modern era with the AAdvantage frequent flyer scheme. It was the first to reward frequent fliers with notional air miles that could be accumulated and later redeemed for free travel. Figure 1: Opportunities example of Customer loyalty driven profitOther airlines and travel providers were quick to grasp the incredible value of providing customers with an incentive to use their company exclusively. Within a few years, dozens of travel industry companies launched similar initiatives and now loyalty programs are achieving near-ubiquity in many service industries, especially those in which it is difficult to differentiate offerings by product attributes.The belief is that increased profitability will result from customer retention efforts because:•    The cost of acquisition occurs only at the beginning of a relationship: the longer the relationship, the lower the amortized cost;•    Account maintenance costs decline as a percentage of total costs, or as a percentage of revenue, over the lifetime of the relationship;•    Long term customers tend to be less inclined to switch and less price sensitive which can result in stable unit sales volume and increases in dollar-sales volume;•    Long term customers may initiate word-of-mouth promotions and referrals, which cost the company nothing and arguably are the most effective form of advertising;•    Long-term customers are more likely to buy ancillary products and higher margin supplemental products;•    Long term customers tend to be satisfied with their relationship with the company and are less likely to switch to competitors, making market entry or competitors gaining market share difficult;•    Regular customers tend to be less expensive to service, as they are familiar with the processes involved, require less 'education', and are consistent in their order placement;•    Increased customer retention and loyalty makes the employees' jobs easier and more satisfying. In turn, happy employees feed back into higher customer satisfaction in a virtuous circle. Figure 2: The virtuous circle of customer loyaltyFigure 2 represents a high-level example of a virtuous cycle driven by customer satisfaction and loyalty, depicting how superiority in product and service offerings, as well as strong customer support by competent employees, lead to higher sales and ultimately profitability. As stated above, this is not a new concept, but succeeding with it is difficult. It has eluded many a company driven to achieve profitability goals. Of course, for this circle to be virtuous, the customer relationship(s) must be profitable.Trying to maintain the loyalty of unprofitable customers is not a viable business strategy. It is, therefore, important that marketers can assess the profitability of each customer (or customer segment), and either improve or terminate relationships that are not profitable. This means each customer's 'relationship costs' must be understood and compared to their 'relationship revenue'. Customer lifetime value (CLV) is the most commonly used metric here, as it is generally accepted as a representation of exactly how much each customer is worth in monetary terms, and therefore a determinant of exactly how much a service provider should be willing to spend to acquire or retain that customer.CLV models make several simplifying assumptions and often involve the following inputs:•    Churn rate represents the percentage of customers who end their relationship with a company in a given period;•    Retention rate is calculated by subtracting the churn rate percentage from 100;•    Period/horizon equates to the units of time into which a customer relationship can be divided for analysis. A year is the most commonly used period for this purpose. Customer lifetime value is a multi-period calculation, often projecting three to seven years into the future. In practice, analysis beyond this point is viewed as too speculative to be reliable. The model horizon is the number of periods used in the calculation;•    Periodic revenue is the amount of revenue collected from a customer in a given period (though this is often extended across multiple periods into the future to understand lifetime value), such as usage revenue, revenues anticipated from cross and upselling, and often some weighting for referrals by a loyal customer to others; •    Retention cost describes the amount of money the service provider must spend, in a given period, to retain an existing customer. Again, this is often forecast across multiple periods. Retention costs include customer support, billing, promotional incentives and so on;•    Discount rate means the cost of capital used to discount future revenue from a customer. Discounting is an advanced method used in more sophisticated CLV calculations;•    Profit margin is the projected profit as a percentage of revenue for the period. This may be reflected as a percentage of gross or net profit. Again, this is generally projected across the model horizon to understand lifetime value.A strong focus on managing these inputs can help service providers realize stronger customer relationships and profits, but there are some obstacles to overcome in achieving accurate calculations of CLV, such as the complexity of allocating costs across the customer base. There are many costs that serve all customers which must be properly allocated across the base, and often a simple proportional allocation across the whole base or a segment may not accurately reflect the true cost of serving that customer;  This is made worse by the fragmentation of customer information, which is likely to be across a variety of product or operations groups, and may be difficult to aggregate due to different representations.In addition, there is the complexity of account relationships and structures to take into consideration. Complex account structures may not be understood or properly represented. For example, a profitable customer may have a separate account for a second home or another family member, which may appear to be unprofitable. If the service provider cannot relate the two accounts, CLV is not properly represented and any resultant cancellation of the apparently unprofitable account may result in the customer churning from the profitable one.In summary, if service providers are to realize strong customer relationships and their attendant profits, there must be a very strong focus on data management. This needs to be coupled with analytics that help business managers and those who work in customer-facing functions offer highly personalized solutions to customers, while maintaining profitability for the service provider. It's clear that acquiring new customers is expensive. Advertising costs, campaign management expenses, promotional service pricing and discounting, and equipment subsidies make a serious dent in a new customer's profitability. That is especially true given the rising subsidies for Smartphone users, which service providers hope will result in greater profits from profits from data services profitability in future.  The situation is made worse by falling prices and greater competition in mature markets.Customer acquisition through industry consolidation isn't cheap either. A North American service provider spent about $2,000 per subscriber in its acquisition of a smaller company earlier this year. While this has allowed it to leapfrog to become the largest mobile service provider in the country, it required a total investment of more than $28 billion (including assumption of the acquiree's debt).While many operating cost synergies clearly made this deal more attractive to the acquiring company, this is certainly an expensive way to acquire customers: the cost per subscriber in this case is not out of line with the prices others have paid for acquisitions.While growth by acquisition certainly increases overall revenues, it often creates tremendous challenges for profitability. Organic growth through increased customer loyalty and retention is a more effective driver of profit, as well as a stronger predictor of future profitability. Service providers, especially those in mature markets, are increasingly recognizing this and taking steps toward a creating a more personalized, flexible and satisfying experience for their customers.In summary, the clearest path to profitability for companies in virtually all industries is through customer retention and maximization of lifetime value. Service providers would do well to recognize this and focus attention on profitable customer relationships.

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• Getting a solid understanding of Linux fundamentals

  - by JoshEarl

  I'm delving into the Linux world again as a diversion from my Microsoft-centric day job, and every time I tackle a new project I find it a frustrating exercise in trial and error. One thing that I always try to do when learning something new is figure out what the big pieces are and how they work together. I haven't yet come across a resource that explains Linux at this level. Resources seem to be either aimed at the barely computer literate crowd (Linux doesn't bite. Promise!) or the just compile the kernel and make your own distro crowd. I'm looking for a "JavaScript: The Good Parts" type of road map that doesn't necessarily answer all my questions so much as help me understand what questions I need to be asking. Any suggestions?

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• Understanding Photography and Color Temperature

  - by Jason Fitzpatrick

  Most digital cameras have the ability to set the “color temperature” based on the condition, but what exactly does that mean? This simple cheat sheet highlights the differences between various lighting situations and what settings you should use. Courtesy of Digital Camera World, the above chart shows where on the scale various color temperatures fall, how the automatic white balance works, and which presets you should use if available. What Is Color Temperature? [via Unpluggd] HTG Explains: Why Linux Doesn’t Need Defragmenting How to Convert News Feeds to Ebooks with Calibre How To Customize Your Wallpaper with Google Image Searches, RSS Feeds, and More

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• Understanding UML composition better

  - by Prog

  The technical difference between Composition and Aggregation in UML (and sometimes in programming too) is that with Composition, the lifetime of the objects composing the composite (e.g. an engine and a steering wheel in a car) is dependent on the composite object. While with Aggregation, the lifetime of the objects making up the composite is independent of the composite. However I'm not sure about something related to composition in UML. Say ClassA is composed of an object of ClassB: class ClassA{ ClassB bInstance; public ClassA(){ bInstance = new ClassB(); } } This is an example of composition, because bInstance is dependent on the lifetime of it's enclosing object. However, regarding UML notation - I'm not sure if I would notate the relationship between ClassA and ClassB with a filled diamond (composition) or a white diamond (aggregation). This is because while the lifetime of some ClassB instances is dependent of ClassA instances - there could be ClassB instances anywhere else in the program - not only within ClassA instances. The question is: if ClassA objects are composed of ClassB objects - but other ClassB objects are free to be used anywhere else in the program: Should the relationship between ClassA and ClassB be notated as aggregation or as composition?

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• Understanding Ajax crawling of search site

  - by vacuum

  I have a couple of questions about Ajax crawling of site, which is kind of search engine itself. The base article explains the mechanism of making AJAX application crawlable. All this stuff with HTML-snapshots is clear and easy to implement, but I cant understand where will Google bot will get "the crawler finds a pretty AJAX URL"( ie www.example.com/ajax.html#key=value) to work with. First thing, that came on mind - is breadcrumb. In sitemap we can specify pages with breadcrumb on it. so bot will go to these pages and get HTML-snapshots from here. But I'm sure, there are exists other ways to give bot this "pretty AJAX URL". In our case, we have simple search site, where user enters keyword, presses "Find", js execute Ajax request, receives JSON reponce and fill page with results(without any refresh of course). In this case - how to make google bot crawle all the presults in addition to sitemap? Is there some example of solution, described in article above?

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• XNA - Drawing 2D Primitives (Boxes) and Understanding Matrices in Computer Graphics

  - by MintyAnt

  I have two issues which I wish to solve by creating 2D primitives in XNA. In my game, I wish to have a "debug mode" which will draw a red box around all hitboxes in the game (Red outline, transparent inside). This would allow us to see where the hitboxes are being drawn AND still have the sprite graphics being drawn. I wish to further understand how matrices work within computer graphics. I have a basic theoretical grasp of how they work, but I really just want to apply some of my knowledge or find a good tutorial on it. To do this, I wish to draw my own 2D primitives (With Vertex3's) and apply different transormation matrices to them. I was trying to find a tutorial on drawing primitives using Direct3D, but most tutorials are only for c++, and just tell me to use XNA's Spritebatch. I wish to have more control over my program than just with Spritebatch. Any Help on using Direct3D or any other suggestions would greatly be appreciated. Thank you.

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• Understanding C# async / await (1) Compilation

  - by Dixin

  Now the async / await keywords are in C#. Just like the async and ! in F#, this new C# feature provides great convenience. There are many nice documents talking about how to use async / await in specific scenarios, like using async methods in ASP.NET 4.5 and in ASP.NET MVC 4, etc. In this article we will look at the real code working behind the syntax sugar. According to MSDN: The async modifier indicates that the method, lambda expression, or anonymous method that it modifies is asynchronous. Since lambda expression / anonymous method will be compiled to normal method, we will focus on normal async method. Preparation First of all, Some helper methods need to make up. internal class HelperMethods { internal static int Method(int arg0, int arg1) { // Do some IO. WebClient client = new WebClient(); Enumerable.Repeat("http://weblogs.asp.net/dixin", 10) .Select(client.DownloadString).ToArray(); int result = arg0 + arg1; return result; } internal static Task<int> MethodTask(int arg0, int arg1) { Task<int> task = new Task<int>(() => Method(arg0, arg1)); task.Start(); // Hot task (started task) should always be returned. return task; } internal static void Before() { } internal static void Continuation1(int arg) { } internal static void Continuation2(int arg) { } } Here Method() is a long running method doing some IO. Then MethodTask() wraps it into a Task and return that Task. Nothing special here. Await something in async method Since MethodTask() returns Task, let’s try to await it: internal class AsyncMethods { internal static async Task<int> MethodAsync(int arg0, int arg1) { int result = await HelperMethods.MethodTask(arg0, arg1); return result; } } Because we used await in the method, async must be put on the method. Now we get the first async method. According to the naming convenience, it is called MethodAsync. Of course a async method can be awaited. So we have a CallMethodAsync() to call MethodAsync(): internal class AsyncMethods { internal static async Task<int> CallMethodAsync(int arg0, int arg1) { int result = await MethodAsync(arg0, arg1); return result; } } After compilation, MethodAsync() and CallMethodAsync() becomes the same logic. This is the code of MethodAsyc(): internal class CompiledAsyncMethods { [DebuggerStepThrough] [AsyncStateMachine(typeof(MethodAsyncStateMachine))] // async internal static /*async*/ Task<int> MethodAsync(int arg0, int arg1) { MethodAsyncStateMachine methodAsyncStateMachine = new MethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Builder = AsyncTaskMethodBuilder<int>.Create(), State = -1 }; methodAsyncStateMachine.Builder.Start(ref methodAsyncStateMachine); return methodAsyncStateMachine.Builder.Task; } } It just creates and starts a state machine MethodAsyncStateMachine: [CompilerGenerated] [StructLayout(LayoutKind.Auto)] internal struct MethodAsyncStateMachine : IAsyncStateMachine { public int State; public AsyncTaskMethodBuilder<int> Builder; public int Arg0; public int Arg1; public int Result; private TaskAwaiter<int> awaitor; void IAsyncStateMachine.MoveNext() { try { if (this.State != 0) { this.awaitor = HelperMethods.MethodTask(this.Arg0, this.Arg1).GetAwaiter(); if (!this.awaitor.IsCompleted) { this.State = 0; this.Builder.AwaitUnsafeOnCompleted(ref this.awaitor, ref this); return; } } else { this.State = -1; } this.Result = this.awaitor.GetResult(); } catch (Exception exception) { this.State = -2; this.Builder.SetException(exception); return; } this.State = -2; this.Builder.SetResult(this.Result); } [DebuggerHidden] void IAsyncStateMachine.SetStateMachine(IAsyncStateMachine param0) { this.Builder.SetStateMachine(param0); } } The generated code has been cleaned up so it is readable and can be compiled. Several things can be observed here: The async modifier is gone, which shows, unlike other modifiers (e.g. static), there is no such IL/CLR level “async” stuff. It becomes a AsyncStateMachineAttribute. This is similar to the compilation of extension method. The generated state machine is very similar to the state machine of C# yield syntax sugar. The local variables (arg0, arg1, result) are compiled to fields of the state machine. The real code (await HelperMethods.MethodTask(arg0, arg1)) is compiled into MoveNext(): HelperMethods.MethodTask(this.Arg0, this.Arg1).GetAwaiter(). CallMethodAsync() will create and start its own state machine CallMethodAsyncStateMachine: internal class CompiledAsyncMethods { [DebuggerStepThrough] [AsyncStateMachine(typeof(CallMethodAsyncStateMachine))] // async internal static /*async*/ Task<int> CallMethodAsync(int arg0, int arg1) { CallMethodAsyncStateMachine callMethodAsyncStateMachine = new CallMethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Builder = AsyncTaskMethodBuilder<int>.Create(), State = -1 }; callMethodAsyncStateMachine.Builder.Start(ref callMethodAsyncStateMachine); return callMethodAsyncStateMachine.Builder.Task; } } CallMethodAsyncStateMachine has the same logic as MethodAsyncStateMachine above. The detail of the state machine will be discussed soon. Now it is clear that: async /await is a C# level syntax sugar. There is no difference to await a async method or a normal method. A method returning Task will be awaitable. State machine and continuation To demonstrate more details in the state machine, a more complex method is created: internal class AsyncMethods { internal static async Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { HelperMethods.Before(); int resultOfAwait1 = await MethodAsync(arg0, arg1); HelperMethods.Continuation1(resultOfAwait1); int resultOfAwait2 = await MethodAsync(arg2, arg3); HelperMethods.Continuation2(resultOfAwait2); int resultToReturn = resultOfAwait1 + resultOfAwait2; return resultToReturn; } } In this method: There are multiple awaits. There are code before the awaits, and continuation code after each await After compilation, this multi-await method becomes the same as above single-await methods: internal class CompiledAsyncMethods { [DebuggerStepThrough] [AsyncStateMachine(typeof(MultiCallMethodAsyncStateMachine))] // async internal static /*async*/ Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { MultiCallMethodAsyncStateMachine multiCallMethodAsyncStateMachine = new MultiCallMethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Arg2 = arg2, Arg3 = arg3, Builder = AsyncTaskMethodBuilder<int>.Create(), State = -1 }; multiCallMethodAsyncStateMachine.Builder.Start(ref multiCallMethodAsyncStateMachine); return multiCallMethodAsyncStateMachine.Builder.Task; } } It creates and starts one single state machine, MultiCallMethodAsyncStateMachine: [CompilerGenerated] [StructLayout(LayoutKind.Auto)] internal struct MultiCallMethodAsyncStateMachine : IAsyncStateMachine { public int State; public AsyncTaskMethodBuilder<int> Builder; public int Arg0; public int Arg1; public int Arg2; public int Arg3; public int ResultOfAwait1; public int ResultOfAwait2; public int ResultToReturn; private TaskAwaiter<int> awaiter; void IAsyncStateMachine.MoveNext() { try { switch (this.State) { case -1: HelperMethods.Before(); this.awaiter = AsyncMethods.MethodAsync(this.Arg0, this.Arg1).GetAwaiter(); if (!this.awaiter.IsCompleted) { this.State = 0; this.Builder.AwaitUnsafeOnCompleted(ref this.awaiter, ref this); } break; case 0: this.ResultOfAwait1 = this.awaiter.GetResult(); HelperMethods.Continuation1(this.ResultOfAwait1); this.awaiter = AsyncMethods.MethodAsync(this.Arg2, this.Arg3).GetAwaiter(); if (!this.awaiter.IsCompleted) { this.State = 1; this.Builder.AwaitUnsafeOnCompleted(ref this.awaiter, ref this); } break; case 1: this.ResultOfAwait2 = this.awaiter.GetResult(); HelperMethods.Continuation2(this.ResultOfAwait2); this.ResultToReturn = this.ResultOfAwait1 + this.ResultOfAwait2; this.State = -2; this.Builder.SetResult(this.ResultToReturn); break; } } catch (Exception exception) { this.State = -2; this.Builder.SetException(exception); } } [DebuggerHidden] void IAsyncStateMachine.SetStateMachine(IAsyncStateMachine stateMachine) { this.Builder.SetStateMachine(stateMachine); } } The above code is already cleaned up, but there are still a lot of things. More clean up can be done, and the state machine can be very simple: [CompilerGenerated] [StructLayout(LayoutKind.Auto)] internal struct MultiCallMethodAsyncStateMachine : IAsyncStateMachine { // State: // -1: Begin // 0: 1st await is done // 1: 2nd await is done // ... // -2: End public int State; public TaskCompletionSource<int> ResultToReturn; // int resultToReturn ... public int Arg0; // int Arg0 public int Arg1; // int arg1 public int Arg2; // int arg2 public int Arg3; // int arg3 public int ResultOfAwait1; // int resultOfAwait1 ... public int ResultOfAwait2; // int resultOfAwait2 ... private Task<int> currentTaskToAwait; /// <summary> /// Moves the state machine to its next state. /// </summary> void IAsyncStateMachine.MoveNext() { try { switch (this.State) { // Orginal code is splitted by "case"s: // case -1: // HelperMethods.Before(); // MethodAsync(Arg0, arg1); // case 0: // int resultOfAwait1 = await ... // HelperMethods.Continuation1(resultOfAwait1); // MethodAsync(arg2, arg3); // case 1: // int resultOfAwait2 = await ... // HelperMethods.Continuation2(resultOfAwait2); // int resultToReturn = resultOfAwait1 + resultOfAwait2; // return resultToReturn; case -1: // -1 is begin. HelperMethods.Before(); // Code before 1st await. this.currentTaskToAwait = AsyncMethods.MethodAsync(this.Arg0, this.Arg1); // 1st task to await // When this.currentTaskToAwait is done, run this.MoveNext() and go to case 0. this.State = 0; IAsyncStateMachine this1 = this; // Cannot use "this" in lambda so create a local variable. this.currentTaskToAwait.ContinueWith(_ => this1.MoveNext()); // Callback break; case 0: // Now 1st await is done. this.ResultOfAwait1 = this.currentTaskToAwait.Result; // Get 1st await's result. HelperMethods.Continuation1(this.ResultOfAwait1); // Code after 1st await and before 2nd await. this.currentTaskToAwait = AsyncMethods.MethodAsync(this.Arg2, this.Arg3); // 2nd task to await // When this.currentTaskToAwait is done, run this.MoveNext() and go to case 1. this.State = 1; IAsyncStateMachine this2 = this; // Cannot use "this" in lambda so create a local variable. this.currentTaskToAwait.ContinueWith(_ => this2.MoveNext()); // Callback break; case 1: // Now 2nd await is done. this.ResultOfAwait2 = this.currentTaskToAwait.Result; // Get 2nd await's result. HelperMethods.Continuation2(this.ResultOfAwait2); // Code after 2nd await. int resultToReturn = this.ResultOfAwait1 + this.ResultOfAwait2; // Code after 2nd await. // End with resultToReturn. this.State = -2; // -2 is end. this.ResultToReturn.SetResult(resultToReturn); break; } } catch (Exception exception) { // End with exception. this.State = -2; // -2 is end. this.ResultToReturn.SetException(exception); } } /// <summary> /// Configures the state machine with a heap-allocated replica. /// </summary> /// <param name="stateMachine">The heap-allocated replica.</param> [DebuggerHidden] void IAsyncStateMachine.SetStateMachine(IAsyncStateMachine stateMachine) { // No core logic. } } Only Task and TaskCompletionSource are involved in this version. And MultiCallMethodAsync() can be simplified to: [DebuggerStepThrough] [AsyncStateMachine(typeof(MultiCallMethodAsyncStateMachine))] // async internal static /*async*/ Task<int> MultiCallMethodAsync_(int arg0, int arg1, int arg2, int arg3) { MultiCallMethodAsyncStateMachine multiCallMethodAsyncStateMachine = new MultiCallMethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Arg2 = arg2, Arg3 = arg3, ResultToReturn = new TaskCompletionSource<int>(), // -1: Begin // 0: 1st await is done // 1: 2nd await is done // ... // -2: End State = -1 }; (multiCallMethodAsyncStateMachine as IAsyncStateMachine).MoveNext(); // Original code are in this method. return multiCallMethodAsyncStateMachine.ResultToReturn.Task; } Now the whole state machine becomes very clear - it is about callback: Original code are split into pieces by “await”s, and each piece is put into each “case” in the state machine. Here the 2 awaits split the code into 3 pieces, so there are 3 “case”s. The “piece”s are chained by callback, that is done by Builder.AwaitUnsafeOnCompleted(callback), or currentTaskToAwait.ContinueWith(callback) in the simplified code. A previous “piece” will end with a Task (which is to be awaited), when the task is done, it will callback the next “piece”. The state machine’s state works with the “case”s to ensure the code “piece”s executes one after another. Callback Since it is about callback, the simplification  can go even further – the entire state machine can be completely purged. Now MultiCallMethodAsync() becomes: internal static Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { TaskCompletionSource<int> taskCompletionSource = new TaskCompletionSource<int>(); try { // Oringinal code begins. HelperMethods.Before(); MethodAsync(arg0, arg1).ContinueWith(await1 => { int resultOfAwait1 = await1.Result; HelperMethods.Continuation1(resultOfAwait1); MethodAsync(arg2, arg3).ContinueWith(await2 => { int resultOfAwait2 = await2.Result; HelperMethods.Continuation2(resultOfAwait2); int resultToReturn = resultOfAwait1 + resultOfAwait2; // Oringinal code ends. taskCompletionSource.SetResult(resultToReturn); }); }); } catch (Exception exception) { taskCompletionSource.SetException(exception); } return taskCompletionSource.Task; } Please compare with the original async / await code: HelperMethods.Before(); int resultOfAwait1 = await MethodAsync(arg0, arg1); HelperMethods.Continuation1(resultOfAwait1); int resultOfAwait2 = await MethodAsync(arg2, arg3); HelperMethods.Continuation2(resultOfAwait2); int resultToReturn = resultOfAwait1 + resultOfAwait2; return resultToReturn; Yeah that is the magic of C# async / await: Await is literally pretending to wait. In a await expression, a Task object will be return immediately so that caller is not blocked. The continuation code is compiled as that Task’s callback code. When that task is done, continuation code will execute. Please notice that many details inside the state machine are omitted for simplicity, like context caring, etc. If you want to have a detailed picture, please do check out the source code of AsyncTaskMethodBuilder and TaskAwaiter.

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