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• Reading a user input (character or string of letters) into ggplot command inside a switch statement or a nested ifelse (with functions in it)

  - by statisticalbeginner

  I have code like AA <- as.integer(readline("Select any number")) switch(AA, 1={ num <-as.integer(readline("Select any one of the options \n")) print('You have selected option 1') #reading user data var <- readline("enter the variable name \n") #aggregating the data based on required condition gg1 <- aggregate(cbind(get(var))~Mi+hours,a, FUN=mean) #Ploting ggplot(gg1, aes(x = hours, y = get(var), group = Mi, fill = Mi, color = Mi)) + geom_point() + geom_smooth(stat="smooth", alpha = I(0.01)) }, 2={ print('bar') }, { print('default') } ) The dataset is [dataset][1] I have loaded the dataset into object list a <- read.table(file.choose(), header=FALSE,col.names= c("Ei","Mi","hours","Nphy","Cphy","CHLphy","Nhet","Chet","Ndet","Cdet","DON","DOC","DIN","DIC","AT","dCCHO","TEPC","Ncocco","Ccocco","CHLcocco","PICcocco","par","Temp","Sal","co2atm","u10","dicfl","co2ppm","co2mol","pH")) I am getting error like source ("switch_statement_check.R") Select any one of the options 1 [1] "You have selected option 1" enter the variable name Nphy Error in eval(expr, envir, enclos) : (list) object cannot be coerced to type 'double' > gg1 is getting data that is fine. I dont know what to do to make the variable entered by user to work in that ggplot command. Please suggest any solution for this. The dput output structure(list(Ei = c(1L, 1L, 1L, 1L, 1L, 1L), Mi = c(1L, 1L, 1L, 1L, 1L, 1L), hours = 1:6, Nphy = c(0.1023488, 0.104524, 0.1064772, 0.1081702, 0.1095905, 0.110759), Cphy = c(0.6534707, 0.6448216, 0.6369597, 0.6299084, 0.6239005, 0.6191941), CHLphy = c(0.1053458, 0.110325, 0.1148174, 0.1187672, 0.122146, 0.1249877), Nhet = c(0.04994161, 0.04988347, 0.04982555, 0.04976784, 0.04971029, 0.04965285), Chet = c(0.3308593, 0.3304699, 0.3300819, 0.3296952, 0.3293089, 0.3289243), Ndet = c(0.04991916, 0.04984045, 0.04976363, 0.0496884, 0.04961446, 0.04954156), Cdet = c(0.3307085, 0.3301691, 0.3296314, 0.3290949, 0.3285598, 0.3280252), DON = c(0.05042275, 0.05085697, 0.05130091, 0.05175249, 0.05220978, 0.05267118 ), DOC = c(49.76304, 49.52745, 49.29323, 49.06034, 48.82878, 48.59851), DIN = c(14.9933, 14.98729, 14.98221, 14.9781, 14.97485, 14.97225), DIC = c(2050.132, 2050.264, 2050.396, 2050.524, 2050.641, 2050.758), AT = c(2150.007, 2150.007, 2150.007, 2150.007, 2150.007, 2150.007), dCCHO = c(0.964222, 0.930869, 0.8997098, 0.870544, 0.843196, 0.8175117), TEPC = c(0.1339044, 0.1652179, 0.1941872, 0.2210289, 0.2459341, 0.2690721), Ncocco = c(0.1040715, 0.1076058, 0.1104229, 0.1125141, 0.1140222, 0.1151228), Ccocco = c(0.6500288, 0.6386706, 0.6291149, 0.6213265, 0.6152447, 0.6108502), CHLcocco = c(0.1087667, 0.1164099, 0.1225822, 0.1273103, 0.1308843, 0.1336465), PICcocco = c(0.1000664, 0.1001396, 0.1007908, 0.101836, 0.1034179, 0.1055634), par = c(0, 0, 0.8695131, 1.551317, 2.777707, 4.814341), Temp = c(9.9, 9.9, 9.9, 9.9, 9.9, 9.9), Sal = c(31.31, 31.31, 31.31, 31.31, 31.31, 31.31), co2atm = c(370, 370, 370, 370, 370, 370), u10 = c(0.01, 0.01, 0.01, 0.01, 0.01, 0.01), dicfl = c(-2.963256, -2.971632, -2.980446, -2.989259, -2.997877, -3.005702), co2ppm = c(565.1855, 565.7373, 566.3179, 566.8983, 567.466, 567.9814), co2mol = c(0.02562326, 0.02564828, 0.0256746, 0.02570091, 0.02572665, 0.02575002 ), pH = c(7.879427, 7.879042, 7.878636, 7.878231, 7.877835, 7.877475)), .Names = c("Ei", "Mi", "hours", "Nphy", "Cphy", "CHLphy", "Nhet", "Chet", "Ndet", "Cdet", "DON", "DOC", "DIN", "DIC", "AT", "dCCHO", "TEPC", "Ncocco", "Ccocco", "CHLcocco", "PICcocco", "par", "Temp", "Sal", "co2atm", "u10", "dicfl", "co2ppm", "co2mol", "pH"), row.names = c(NA, 6L), class = "data.frame") As per the below suggestions I have tried a lot but it is not working. Summarizing I will say: var <- readline("enter a variable name") I cant use get(var) inside any command but not inside ggplot, it wont work. gg1$var it also doesnt work, even after changing the column names. Does it have a solution or should I just choose to import from an excel sheet, thats better? Tried with if else and functions fun1 <- function() { print('You have selected option 1') my <- as.character((readline("enter the variable name \n"))) gg1 <- aggregate(cbind(get(my))~Mi+hours,a, FUN=mean) names(gg1)[3] <- my #print(names(gg1)) ggplot (gg1,aes_string(x="hours",y=(my),group="Mi",color="Mi")) + geom_point() } my <- as.integer(readline("enter a number")) ifelse(my == 1,fun1(),"") ifelse(my == 2,print ("its 2"),"") ifelse(my == 3,print ("its 3"),"") ifelse(my != (1 || 2|| 3) ,print("wrong number"),"") Not working either...:(

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• When is a SQL function not a function?

  - by Rob Farley

  Should SQL Server even have functions? (Oh yeah – this is a T-SQL Tuesday post, hosted this month by Brad Schulz) Functions serve an important part of programming, in almost any language. A function is a piece of code that is designed to return something, as opposed to a piece of code which isn’t designed to return anything (which is known as a procedure). SQL Server is no different. You can call stored procedures, even from within other stored procedures, and you can call functions and use these in other queries. Stored procedures might query something, and therefore ‘return data’, but a function in SQL is considered to have the type of the thing returned, and can be used accordingly in queries. Consider the internal GETDATE() function. SELECT GETDATE(), SomeDatetimeColumn FROM dbo.SomeTable; There’s no logical difference between the field that is being returned by the function and the field that’s being returned by the table column. Both are the datetime field – if you didn’t have inside knowledge, you wouldn’t necessarily be able to tell which was which. And so as developers, we find ourselves wanting to create functions that return all kinds of things – functions which look up values based on codes, functions which do string manipulation, and so on. But it’s rubbish. Ok, it’s not all rubbish, but it mostly is. And this isn’t even considering the SARGability impact. It’s far more significant than that. (When I say the SARGability aspect, I mean “because you’re unlikely to have an index on the result of some function that’s applied to a column, so try to invert the function and query the column in an unchanged manner”) I’m going to consider the three main types of user-defined functions in SQL Server: Scalar Inline Table-Valued Multi-statement Table-Valued I could also look at user-defined CLR functions, including aggregate functions, but not today. I figure that most people don’t tend to get around to doing CLR functions, and I’m going to focus on the T-SQL-based user-defined functions. Most people split these types of function up into two types. So do I. Except that most people pick them based on ‘scalar or table-valued’. I’d rather go with ‘inline or not’. If it’s not inline, it’s rubbish. It really is. Let’s start by considering the two kinds of table-valued function, and compare them. These functions are going to return the sales for a particular salesperson in a particular year, from the AdventureWorks database. CREATE FUNCTION dbo.FetchSales_inline(@salespersonid int, @orderyear int) RETURNS TABLE AS  RETURN (     SELECT e.LoginID as EmployeeLogin, o.OrderDate, o.SalesOrderID     FROM Sales.SalesOrderHeader AS o     LEFT JOIN HumanResources.Employee AS e     ON e.EmployeeID = o.SalesPersonID     WHERE o.SalesPersonID = @salespersonid     AND o.OrderDate >= DATEADD(year,@orderyear-2000,'20000101')     AND o.OrderDate < DATEADD(year,@orderyear-2000+1,'20000101') ) ; GO CREATE FUNCTION dbo.FetchSales_multi(@salespersonid int, @orderyear int) RETURNS @results TABLE (     EmployeeLogin nvarchar(512),     OrderDate datetime,     SalesOrderID int     ) AS BEGIN     INSERT @results (EmployeeLogin, OrderDate, SalesOrderID)     SELECT e.LoginID, o.OrderDate, o.SalesOrderID     FROM Sales.SalesOrderHeader AS o     LEFT JOIN HumanResources.Employee AS e     ON e.EmployeeID = o.SalesPersonID     WHERE o.SalesPersonID = @salespersonid     AND o.OrderDate >= DATEADD(year,@orderyear-2000,'20000101')     AND o.OrderDate < DATEADD(year,@orderyear-2000+1,'20000101')     ;     RETURN END ; GO You’ll notice that I’m being nice and responsible with the use of the DATEADD function, so that I have SARGability on the OrderDate filter. Regular readers will be hoping I’ll show what’s going on in the execution plans here. Here I’ve run two SELECT * queries with the “Show Actual Execution Plan” option turned on. Notice that the ‘Query cost’ of the multi-statement version is just 2% of the ‘Batch cost’. But also notice there’s trickery going on. And it’s nothing to do with that extra index that I have on the OrderDate column. Trickery. Look at it – clearly, the first plan is showing us what’s going on inside the function, but the second one isn’t. The second one is blindly running the function, and then scanning the results. There’s a Sequence operator which is calling the TVF operator, and then calling a Table Scan to get the results of that function for the SELECT operator. But surely it still has to do all the work that the first one is doing... To see what’s actually going on, let’s look at the Estimated plan. Now, we see the same plans (almost) that we saw in the Actuals, but we have an extra one – the one that was used for the TVF. Here’s where we see the inner workings of it. You’ll probably recognise the right-hand side of the TVF’s plan as looking very similar to the first plan – but it’s now being called by a stack of other operators, including an INSERT statement to be able to populate the table variable that the multi-statement TVF requires. And the cost of the TVF is 57% of the batch! But it gets worse. Let’s consider what happens if we don’t need all the columns. We’ll leave out the EmployeeLogin column. Here, we see that the inline function call has been simplified down. It doesn’t need the Employee table. The join is redundant and has been eliminated from the plan, making it even cheaper. But the multi-statement plan runs the whole thing as before, only removing the extra column when the Table Scan is performed. A multi-statement function is a lot more powerful than an inline one. An inline function can only be the result of a single sub-query. It’s essentially the same as a parameterised view, because views demonstrate this same behaviour of extracting the definition of the view and using it in the outer query. A multi-statement function is clearly more powerful because it can contain far more complex logic. But a multi-statement function isn’t really a function at all. It’s a stored procedure. It’s wrapped up like a function, but behaves like a stored procedure. It would be completely unreasonable to expect that a stored procedure could be simplified down to recognise that not all the columns might be needed, but yet this is part of the pain associated with this procedural function situation. The biggest clue that a multi-statement function is more like a stored procedure than a function is the “BEGIN” and “END” statements that surround the code. If you try to create a multi-statement function without these statements, you’ll get an error – they are very much required. When I used to present on this kind of thing, I even used to call it “The Dangers of BEGIN and END”, and yes, I’ve written about this type of thing before in a similarly-named post over at my old blog. Now how about scalar functions... Suppose we wanted a scalar function to return the count of these. CREATE FUNCTION dbo.FetchSales_scalar(@salespersonid int, @orderyear int) RETURNS int AS BEGIN     RETURN (         SELECT COUNT(*)         FROM Sales.SalesOrderHeader AS o         LEFT JOIN HumanResources.Employee AS e         ON e.EmployeeID = o.SalesPersonID         WHERE o.SalesPersonID = @salespersonid         AND o.OrderDate >= DATEADD(year,@orderyear-2000,'20000101')         AND o.OrderDate < DATEADD(year,@orderyear-2000+1,'20000101')     ); END ; GO Notice the evil words? They’re required. Try to remove them, you just get an error. That’s right – any scalar function is procedural, despite the fact that you wrap up a sub-query inside that RETURN statement. It’s as ugly as anything. Hopefully this will change in future versions. Let’s have a look at how this is reflected in an execution plan. Here’s a query, its Actual plan, and its Estimated plan: SELECT e.LoginID, y.year, dbo.FetchSales_scalar(p.SalesPersonID, y.year) AS NumSales FROM (VALUES (2001),(2002),(2003),(2004)) AS y (year) CROSS JOIN Sales.SalesPerson AS p LEFT JOIN HumanResources.Employee AS e ON e.EmployeeID = p.SalesPersonID; We see here that the cost of the scalar function is about twice that of the outer query. Nicely, the query optimizer has worked out that it doesn’t need the Employee table, but that’s a bit of a red herring here. There’s actually something way more significant going on. If I look at the properties of that UDF operator, it tells me that the Estimated Subtree Cost is 0.337999. If I just run the query SELECT dbo.FetchSales_scalar(281,2003); we see that the UDF cost is still unchanged. You see, this 0.0337999 is the cost of running the scalar function ONCE. But when we ran that query with the CROSS JOIN in it, we returned quite a few rows. 68 in fact. Could’ve been a lot more, if we’d had more salespeople or more years. And so we come to the biggest problem. This procedure (I don’t want to call it a function) is getting called 68 times – each one between twice as expensive as the outer query. And because it’s calling it in a separate context, there is even more overhead that I haven’t considered here. The cheek of it, to say that the Compute Scalar operator here costs 0%! I know a number of IT projects that could’ve used that kind of costing method, but that’s another story that I’m not going to go into here. Let’s look at a better way. Suppose our scalar function had been implemented as an inline one. Then it could have been expanded out like a sub-query. It could’ve run something like this: SELECT e.LoginID, y.year, (SELECT COUNT(*)     FROM Sales.SalesOrderHeader AS o     LEFT JOIN HumanResources.Employee AS e     ON e.EmployeeID = o.SalesPersonID     WHERE o.SalesPersonID = p.SalesPersonID     AND o.OrderDate >= DATEADD(year,y.year-2000,'20000101')     AND o.OrderDate < DATEADD(year,y.year-2000+1,'20000101')     ) AS NumSales FROM (VALUES (2001),(2002),(2003),(2004)) AS y (year) CROSS JOIN Sales.SalesPerson AS p LEFT JOIN HumanResources.Employee AS e ON e.EmployeeID = p.SalesPersonID; Don’t worry too much about the Scan of the SalesOrderHeader underneath a Nested Loop. If you remember from plenty of other posts on the matter, execution plans don’t push the data through. That Scan only runs once. The Index Spool sucks the data out of it and populates a structure that is used to feed the Stream Aggregate. The Index Spool operator gets called 68 times, but the Scan only once (the Number of Executions property demonstrates this). Here, the Query Optimizer has a full picture of what’s being asked, and can make the appropriate decision about how it accesses the data. It can simplify it down properly. To get this kind of behaviour from a function, we need it to be inline. But without inline scalar functions, we need to make our function be table-valued. Luckily, that’s ok. CREATE FUNCTION dbo.FetchSales_inline2(@salespersonid int, @orderyear int) RETURNS table AS RETURN (SELECT COUNT(*) as NumSales     FROM Sales.SalesOrderHeader AS o     LEFT JOIN HumanResources.Employee AS e     ON e.EmployeeID = o.SalesPersonID     WHERE o.SalesPersonID = @salespersonid     AND o.OrderDate >= DATEADD(year,@orderyear-2000,'20000101')     AND o.OrderDate < DATEADD(year,@orderyear-2000+1,'20000101') ); GO But we can’t use this as a scalar. Instead, we need to use it with the APPLY operator. SELECT e.LoginID, y.year, n.NumSales FROM (VALUES (2001),(2002),(2003),(2004)) AS y (year) CROSS JOIN Sales.SalesPerson AS p LEFT JOIN HumanResources.Employee AS e ON e.EmployeeID = p.SalesPersonID OUTER APPLY dbo.FetchSales_inline2(p.SalesPersonID, y.year) AS n; And now, we get the plan that we want for this query. All we’ve done is tell the function that it’s returning a table instead of a single value, and removed the BEGIN and END statements. We’ve had to name the column being returned, but what we’ve gained is an actual inline simplifiable function. And if we wanted it to return multiple columns, it could do that too. I really consider this function to be superior to the scalar function in every way. It does need to be handled differently in the outer query, but in many ways it’s a more elegant method there too. The function calls can be put amongst the FROM clause, where they can then be used in the WHERE or GROUP BY clauses without fear of calling the function multiple times (another horrible side effect of functions). So please. If you see BEGIN and END in a function, remember it’s not really a function, it’s a procedure. And then fix it. @rob_farley

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• Windows Azure Service Bus Splitter and Aggregator

  - by Alan Smith

  This article will cover basic implementations of the Splitter and Aggregator patterns using the Windows Azure Service Bus. The content will be included in the next release of the “Windows Azure Service Bus Developer Guide”, along with some other patterns I am working on. I’ve taken the pattern descriptions from the book “Enterprise Integration Patterns” by Gregor Hohpe. I bought a copy of the book in 2004, and recently dusted it off when I started to look at implementing the patterns on the Windows Azure Service Bus. Gregor has also presented an session in 2011 “Enterprise Integration Patterns: Past, Present and Future” which is well worth a look. I’ll be covering more patterns in the coming weeks, I’m currently working on Wire-Tap and Scatter-Gather. There will no doubt be a section on implementing these patterns in my “SOA, Connectivity and Integration using the Windows Azure Service Bus” course. There are a number of scenarios where a message needs to be divided into a number of sub messages, and also where a number of sub messages need to be combined to form one message. The splitter and aggregator patterns provide a definition of how this can be achieved. This section will focus on the implementation of basic splitter and aggregator patens using the Windows Azure Service Bus direct programming model. In BizTalk Server receive pipelines are typically used to implement the splitter patterns, with sequential convoy orchestrations often used to aggregate messages. In the current release of the Service Bus, there is no functionality in the direct programming model that implements these patterns, so it is up to the developer to implement them in the applications that send and receive messages. Splitter A message splitter takes a message and spits the message into a number of sub messages. As there are different scenarios for how a message can be split into sub messages, message splitters are implemented using different algorithms. The Enterprise Integration Patterns book describes the splatter pattern as follows: How can we process a message if it contains multiple elements, each of which may have to be processed in a different way? Use a Splitter to break out the composite message into a series of individual messages, each containing data related to one item. The Enterprise Integration Patterns website provides a description of the Splitter pattern here. In some scenarios a batch message could be split into the sub messages that are contained in the batch. The splitting of a message could be based on the message type of sub-message, or the trading partner that the sub message is to be sent to. Aggregator An aggregator takes a stream or related messages and combines them together to form one message. The Enterprise Integration Patterns book describes the aggregator pattern as follows: How do we combine the results of individual, but related messages so that they can be processed as a whole? Use a stateful filter, an Aggregator, to collect and store individual messages until a complete set of related messages has been received. Then, the Aggregator publishes a single message distilled from the individual messages. The Enterprise Integration Patterns website provides a description of the Aggregator pattern here. A common example of the need for an aggregator is in scenarios where a stream of messages needs to be combined into a daily batch to be sent to a legacy line-of-business application. The BizTalk Server EDI functionality provides support for batching messages in this way using a sequential convoy orchestration. Scenario The scenario for this implementation of the splitter and aggregator patterns is the sending and receiving of large messages using a Service Bus queue. In the current release, the Windows Azure Service Bus currently supports a maximum message size of 256 KB, with a maximum header size of 64 KB. This leaves a safe maximum body size of 192 KB. The BrokeredMessage class will support messages larger than 256 KB; in fact the Size property is of type long, implying that very large messages may be supported at some point in the future. The 256 KB size restriction is set in the service bus components that are deployed in the Windows Azure data centers. One of the ways of working around this size restriction is to split large messages into a sequence of smaller sub messages in the sending application, send them via a queue, and then reassemble them in the receiving application. This scenario will be used to demonstrate the pattern implementations. Implementation The splitter and aggregator will be used to provide functionality to send and receive large messages over the Windows Azure Service Bus. In order to make the implementations generic and reusable they will be implemented as a class library. The splitter will be implemented in the LargeMessageSender class and the aggregator in the LargeMessageReceiver class. A class diagram showing the two classes is shown below. Implementing the Splitter The splitter will take a large brokered message, and split the messages into a sequence of smaller sub-messages that can be transmitted over the service bus messaging entities. The LargeMessageSender class provides a Send method that takes a large brokered message as a parameter. The implementation of the class is shown below; console output has been added to provide details of the splitting operation. public class LargeMessageSender {     private static int SubMessageBodySize = 192 * 1024;     private QueueClient m_QueueClient;       public LargeMessageSender(QueueClient queueClient)     {         m_QueueClient = queueClient;     }       public void Send(BrokeredMessage message)     {         // Calculate the number of sub messages required.         long messageBodySize = message.Size;         int nrSubMessages = (int)(messageBodySize / SubMessageBodySize);         if (messageBodySize % SubMessageBodySize != 0)         {             nrSubMessages++;         }           // Create a unique session Id.         string sessionId = Guid.NewGuid().ToString();         Console.WriteLine("Message session Id: " + sessionId);         Console.Write("Sending {0} sub-messages", nrSubMessages);           Stream bodyStream = message.GetBody<Stream>();         for (int streamOffest = 0; streamOffest < messageBodySize;             streamOffest += SubMessageBodySize)         {                                     // Get the stream chunk from the large message             long arraySize = (messageBodySize - streamOffest) > SubMessageBodySize                 ? SubMessageBodySize : messageBodySize - streamOffest;             byte[] subMessageBytes = new byte[arraySize];             int result = bodyStream.Read(subMessageBytes, 0, (int)arraySize);             MemoryStream subMessageStream = new MemoryStream(subMessageBytes);               // Create a new message             BrokeredMessage subMessage = new BrokeredMessage(subMessageStream, true);             subMessage.SessionId = sessionId;               // Send the message             m_QueueClient.Send(subMessage);             Console.Write(".");         }         Console.WriteLine("Done!");     }} The LargeMessageSender class is initialized with a QueueClient that is created by the sending application. When the large message is sent, the number of sub messages is calculated based on the size of the body of the large message. A unique session Id is created to allow the sub messages to be sent as a message session, this session Id will be used for correlation in the aggregator. A for loop in then used to create the sequence of sub messages by creating chunks of data from the stream of the large message. The sub messages are then sent to the queue using the QueueClient. As sessions are used to correlate the messages, the queue used for message exchange must be created with the RequiresSession property set to true. Implementing the Aggregator The aggregator will receive the sub messages in the message session that was created by the splitter, and combine them to form a single, large message. The aggregator is implemented in the LargeMessageReceiver class, with a Receive method that returns a BrokeredMessage. The implementation of the class is shown below; console output has been added to provide details of the splitting operation.   public class LargeMessageReceiver {     private QueueClient m_QueueClient;       public LargeMessageReceiver(QueueClient queueClient)     {         m_QueueClient = queueClient;     }       public BrokeredMessage Receive()     {         // Create a memory stream to store the large message body.         MemoryStream largeMessageStream = new MemoryStream();           // Accept a message session from the queue.         MessageSession session = m_QueueClient.AcceptMessageSession();         Console.WriteLine("Message session Id: " + session.SessionId);         Console.Write("Receiving sub messages");           while (true)         {             // Receive a sub message             BrokeredMessage subMessage = session.Receive(TimeSpan.FromSeconds(5));               if (subMessage != null)             {                 // Copy the sub message body to the large message stream.                 Stream subMessageStream = subMessage.GetBody<Stream>();                 subMessageStream.CopyTo(largeMessageStream);                   // Mark the message as complete.                 subMessage.Complete();                 Console.Write(".");             }             else             {                 // The last message in the sequence is our completeness criteria.                 Console.WriteLine("Done!");                 break;             }         }                     // Create an aggregated message from the large message stream.         BrokeredMessage largeMessage = new BrokeredMessage(largeMessageStream, true);         return largeMessage;     } }   The LargeMessageReceiver initialized using a QueueClient that is created by the receiving application. The receive method creates a memory stream that will be used to aggregate the large message body. The AcceptMessageSession method on the QueueClient is then called, which will wait for the first message in a message session to become available on the queue. As the AcceptMessageSession can throw a timeout exception if no message is available on the queue after 60 seconds, a real-world implementation should handle this accordingly. Once the message session as accepted, the sub messages in the session are received, and their message body streams copied to the memory stream. Once all the messages have been received, the memory stream is used to create a large message, that is then returned to the receiving application. Testing the Implementation The splitter and aggregator are tested by creating a message sender and message receiver application. The payload for the large message will be one of the webcast video files from http://www.cloudcasts.net/, the file size is 9,697 KB, well over the 256 KB threshold imposed by the Service Bus. As the splitter and aggregator are implemented in a separate class library, the code used in the sender and receiver console is fairly basic. The implementation of the main method of the sending application is shown below.   static void Main(string[] args) {     // Create a token provider with the relevant credentials.     TokenProvider credentials =         TokenProvider.CreateSharedSecretTokenProvider         (AccountDetails.Name, AccountDetails.Key);       // Create a URI for the serivce bus.     Uri serviceBusUri = ServiceBusEnvironment.CreateServiceUri         ("sb", AccountDetails.Namespace, string.Empty);       // Create the MessagingFactory     MessagingFactory factory = MessagingFactory.Create(serviceBusUri, credentials);       // Use the MessagingFactory to create a queue client     QueueClient queueClient = factory.CreateQueueClient(AccountDetails.QueueName);       // Open the input file.     FileStream fileStream = new FileStream(AccountDetails.TestFile, FileMode.Open);       // Create a BrokeredMessage for the file.     BrokeredMessage largeMessage = new BrokeredMessage(fileStream, true);       Console.WriteLine("Sending: " + AccountDetails.TestFile);     Console.WriteLine("Message body size: " + largeMessage.Size);     Console.WriteLine();         // Send the message with a LargeMessageSender     LargeMessageSender sender = new LargeMessageSender(queueClient);     sender.Send(largeMessage);       // Close the messaging facory.     factory.Close();  } The implementation of the main method of the receiving application is shown below. static void Main(string[] args) {       // Create a token provider with the relevant credentials.     TokenProvider credentials =         TokenProvider.CreateSharedSecretTokenProvider         (AccountDetails.Name, AccountDetails.Key);       // Create a URI for the serivce bus.     Uri serviceBusUri = ServiceBusEnvironment.CreateServiceUri         ("sb", AccountDetails.Namespace, string.Empty);       // Create the MessagingFactory     MessagingFactory factory = MessagingFactory.Create(serviceBusUri, credentials);       // Use the MessagingFactory to create a queue client     QueueClient queueClient = factory.CreateQueueClient(AccountDetails.QueueName);       // Create a LargeMessageReceiver and receive the message.     LargeMessageReceiver receiver = new LargeMessageReceiver(queueClient);     BrokeredMessage largeMessage = receiver.Receive();       Console.WriteLine("Received message");     Console.WriteLine("Message body size: " + largeMessage.Size);       string testFile = AccountDetails.TestFile.Replace(@"\In\", @"\Out\");     Console.WriteLine("Saving file: " + testFile);       // Save the message body as a file.     Stream largeMessageStream = largeMessage.GetBody<Stream>();     largeMessageStream.Seek(0, SeekOrigin.Begin);     FileStream fileOut = new FileStream(testFile, FileMode.Create);     largeMessageStream.CopyTo(fileOut);     fileOut.Close();       Console.WriteLine("Done!"); } In order to test the application, the sending application is executed, which will use the LargeMessageSender class to split the message and place it on the queue. The output of the sender console is shown below. The console shows that the body size of the large message was 9,929,365 bytes, and the message was sent as a sequence of 51 sub messages. When the receiving application is executed the results are shown below. The console application shows that the aggregator has received the 51 messages from the message sequence that was creating in the sending application. The messages have been aggregated to form a massage with a body of 9,929,365 bytes, which is the same as the original large message. The message body is then saved as a file. Improvements to the Implementation The splitter and aggregator patterns in this implementation were created in order to show the usage of the patterns in a demo, which they do quite well. When implementing these patterns in a real-world scenario there are a number of improvements that could be made to the design. Copying Message Header Properties When sending a large message using these classes, it would be great if the message header properties in the message that was received were copied from the message that was sent. The sending application may well add information to the message context that will be required in the receiving application. When the sub messages are created in the splitter, the header properties in the first message could be set to the values in the original large message. The aggregator could then used the values from this first sub message to set the properties in the message header of the large message during the aggregation process. Using Asynchronous Methods The current implementation uses the synchronous send and receive methods of the QueueClient class. It would be much more performant to use the asynchronous methods, however doing so may well affect the sequence in which the sub messages are enqueued, which would require the implementation of a resequencer in the aggregator to restore the correct message sequence. Handling Exceptions In order to keep the code readable no exception handling was added to the implementations. In a real-world scenario exceptions should be handled accordingly.

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• Windows Azure Service Bus Scatter-Gather Implementation

  - by Alan Smith

  One of the more challenging enterprise integration patterns that developers may wish to implement is the Scatter-Gather pattern. In this article I will show the basic implementation of a scatter-gather pattern using the topic-subscription model of the windows azure service bus. I’ll be using the implementation in demos, and also as a lab in my training courses, and the pattern will also be included in the next release of my free e-book the “Windows Azure Service Bus Developer Guide”. The Scatter-Gather pattern answers the following scenario. How do you maintain the overall message flow when a message needs to be sent to multiple recipients, each of which may send a reply? Use a Scatter-Gather that broadcasts a message to multiple recipients and re-aggregates the responses back into a single message. The Enterprise Integration Patterns website provides a description of the Scatter-Gather pattern here.   The scatter-gather pattern uses a composite of the publish-subscribe channel pattern and the aggregator pattern. The publish-subscribe channel is used to broadcast messages to a number of receivers, and the aggregator is used to gather the response messages and aggregate them together to form a single message. Scatter-Gather Scenario The scenario for this scatter-gather implementation is an application that allows users to answer questions in a poll based voting scenario. A poll manager application will be used to broadcast questions to users, the users will use a voting application that will receive and display the questions and send the votes back to the poll manager. The poll manager application will receive the users’ votes and aggregate them together to display the results. The scenario should be able to scale to support a large number of users.   Scatter-Gather Implementation The diagram below shows the overall architecture for the scatter-gather implementation.       Messaging Entities Looking at the scatter-gather pattern diagram it can be seen that the topic-subscription architecture is well suited for broadcasting a message to a number of subscribers. The poll manager application can send the question messages to a topic, and each voting application can receive the question message on its own subscription. The static limit of 2,000 subscriptions per topic in the current release means that 2,000 voting applications can receive question messages and take part in voting. The vote messages can then be sent to the poll manager application using a queue. The voting applications will send their vote messages to the queue, and the poll manager will receive and process the vote messages. The questions topic and answer queue are created using the Windows Azure Developer Portal. Each instance of the voting application will create its own subscription in the questions topic when it starts, allowing the question messages to be broadcast to all subscribing voting applications. Data Contracts Two simple data contracts will be used to serialize the questions and votes as brokered messages. The code for these is shown below.   [DataContract] public class Question {     [DataMember]     public string QuestionText { get; set; } }     To keep the implementation of the voting functionality simple and focus on the pattern implementation, the users can only vote yes or no to the questions.   [DataContract] public class Vote {     [DataMember]     public string QuestionText { get; set; }       [DataMember]     public bool IsYes { get; set; } }     Poll Manager Application The poll manager application has been implemented as a simple WPF application; the user interface is shown below. A question can be entered in the text box, and sent to the topic by clicking the Add button. The topic and subscriptions used for broadcasting the messages are shown in a TreeView control. The questions that have been broadcast and the resulting votes are shown in a ListView control. When the application is started any existing subscriptions are cleared form the topic, clients are then created for the questions topic and votes queue, along with background workers for receiving and processing the vote messages, and updating the display of subscriptions.   public MainWindow() {     InitializeComponent();       // Create a new results list and data bind it.     Results = new ObservableCollection<Result>();     lsvResults.ItemsSource = Results;       // Create a token provider with the relevant credentials.     TokenProvider credentials =         TokenProvider.CreateSharedSecretTokenProvider         (AccountDetails.Name, AccountDetails.Key);       // Create a URI for the serivce bus.     Uri serviceBusUri = ServiceBusEnvironment.CreateServiceUri         ("sb", AccountDetails.Namespace, string.Empty);       // Clear out any old subscriptions.     NamespaceManager = new NamespaceManager(serviceBusUri, credentials);     IEnumerable<SubscriptionDescription> subs =         NamespaceManager.GetSubscriptions(AccountDetails.ScatterGatherTopic);     foreach (SubscriptionDescription sub in subs)     {         NamespaceManager.DeleteSubscription(sub.TopicPath, sub.Name);     }       // Create the MessagingFactory     MessagingFactory factory = MessagingFactory.Create(serviceBusUri, credentials);       // Create the topic and queue clients.     ScatterGatherTopicClient =         factory.CreateTopicClient(AccountDetails.ScatterGatherTopic);     ScatterGatherQueueClient =         factory.CreateQueueClient(AccountDetails.ScatterGatherQueue);       // Start the background worker threads.     VotesBackgroundWorker = new BackgroundWorker();     VotesBackgroundWorker.DoWork += new DoWorkEventHandler(ReceiveMessages);     VotesBackgroundWorker.RunWorkerAsync();       SubscriptionsBackgroundWorker = new BackgroundWorker();     SubscriptionsBackgroundWorker.DoWork += new DoWorkEventHandler(UpdateSubscriptions);     SubscriptionsBackgroundWorker.RunWorkerAsync(); }     When the poll manager user nters a question in the text box and clicks the Add button a question message is created and sent to the topic. This message will be broadcast to all the subscribing voting applications. An instance of the Result class is also created to keep track of the votes cast, this is then added to an observable collection named Results, which is data-bound to the ListView control.   private void btnAddQuestion_Click(object sender, RoutedEventArgs e) {     // Create a new result for recording votes.     Result result = new Result()     {         Question = txtQuestion.Text     };     Results.Add(result);       // Send the question to the topic     Question question = new Question()     {         QuestionText = result.Question     };     BrokeredMessage msg = new BrokeredMessage(question);     ScatterGatherTopicClient.Send(msg);       txtQuestion.Text = ""; }     The Results class is implemented as follows.   public class Result : INotifyPropertyChanged {     public string Question { get; set; }       private int m_YesVotes;     private int m_NoVotes;       public event PropertyChangedEventHandler PropertyChanged;       public int YesVotes     {         get { return m_YesVotes; }         set         {             m_YesVotes = value;             NotifyPropertyChanged("YesVotes");         }     }       public int NoVotes     {         get { return m_NoVotes; }         set         {             m_NoVotes = value;             NotifyPropertyChanged("NoVotes");         }     }       private void NotifyPropertyChanged(string prop)     {         if(PropertyChanged != null)         {             PropertyChanged(this, new PropertyChangedEventArgs(prop));         }     } }     The INotifyPropertyChanged interface is implemented so that changes to the number of yes and no votes will be updated in the ListView control. Receiving the vote messages from the voting applications is done asynchronously, using a background worker thread.   // This runs on a background worker. private void ReceiveMessages(object sender, DoWorkEventArgs e) {     while (true)     {         // Receive a vote message from the queue         BrokeredMessage msg = ScatterGatherQueueClient.Receive();         if (msg != null)         {             // Deserialize the message.             Vote vote = msg.GetBody<Vote>();               // Update the results.             foreach (Result result in Results)             {                 if (result.Question.Equals(vote.QuestionText))                 {                     if (vote.IsYes)                     {                         result.YesVotes++;                     }                     else                     {                         result.NoVotes++;                     }                     break;                 }             }               // Mark the message as complete.             msg.Complete();         }       } }     When a vote message is received, the result that matches the vote question is updated with the vote from the user. The message is then marked as complete. A second background thread is used to update the display of subscriptions in the TreeView, with a dispatcher used to update the user interface. // This runs on a background worker. private void UpdateSubscriptions(object sender, DoWorkEventArgs e) {     while (true)     {         // Get a list of subscriptions.         IEnumerable<SubscriptionDescription> subscriptions =             NamespaceManager.GetSubscriptions(AccountDetails.ScatterGatherTopic);           // Update the user interface.         SimpleDelegate setQuestion = delegate()         {             trvSubscriptions.Items.Clear();             TreeViewItem topicItem = new TreeViewItem()             {                 Header = AccountDetails.ScatterGatherTopic             };               foreach (SubscriptionDescription subscription in subscriptions)             {                 TreeViewItem subscriptionItem = new TreeViewItem()                 {                     Header = subscription.Name                 };                 topicItem.Items.Add(subscriptionItem);             }             trvSubscriptions.Items.Add(topicItem);               topicItem.ExpandSubtree();         };         this.Dispatcher.BeginInvoke(DispatcherPriority.Send, setQuestion);           Thread.Sleep(3000);     } }       Voting Application The voting application is implemented as another WPF application. This one is more basic, and allows the user to vote “Yes” or “No” for the questions sent by the poll manager application. The user interface for that application is shown below. When an instance of the voting application is created it will create a subscription in the questions topic using a GUID as the subscription name. The application can then receive copies of every question message that is sent to the topic. Clients for the new subscription and the votes queue are created, along with a background worker to receive the question messages. The voting application is set to receiving mode, meaning it is ready to receive a question message from the subscription.   public MainWindow() {     InitializeComponent();       // Set the mode to receiving.     IsReceiving = true;       // Create a token provider with the relevant credentials.     TokenProvider credentials =         TokenProvider.CreateSharedSecretTokenProvider         (AccountDetails.Name, AccountDetails.Key);       // Create a URI for the serivce bus.     Uri serviceBusUri = ServiceBusEnvironment.CreateServiceUri         ("sb", AccountDetails.Namespace, string.Empty);       // Create the MessagingFactory     MessagingFactory factory = MessagingFactory.Create(serviceBusUri, credentials);       // Create a subcription for this instance     NamespaceManager mgr = new NamespaceManager(serviceBusUri, credentials);     string subscriptionName = Guid.NewGuid().ToString();     mgr.CreateSubscription(AccountDetails.ScatterGatherTopic, subscriptionName);       // Create the subscription and queue clients.     ScatterGatherSubscriptionClient = factory.CreateSubscriptionClient         (AccountDetails.ScatterGatherTopic, subscriptionName);     ScatterGatherQueueClient =         factory.CreateQueueClient(AccountDetails.ScatterGatherQueue);       // Start the background worker thread.     BackgroundWorker = new BackgroundWorker();     BackgroundWorker.DoWork += new DoWorkEventHandler(ReceiveMessages);     BackgroundWorker.RunWorkerAsync(); }     I took the inspiration for creating the subscriptions in the voting application from the chat application that uses topics and subscriptions blogged by Ovais Akhter here. The method that receives the question messages runs on a background thread. If the application is in receive mode, a question message will be received from the subscription, the question will be displayed in the user interface, the voting buttons enabled, and IsReceiving set to false to prevent more questing from being received before the current one is answered.   // This runs on a background worker. private void ReceiveMessages(object sender, DoWorkEventArgs e) {     while (true)     {         if (IsReceiving)         {             // Receive a question message from the topic.             BrokeredMessage msg = ScatterGatherSubscriptionClient.Receive();             if (msg != null)             {                 // Deserialize the message.                 Question question = msg.GetBody<Question>();                   // Update the user interface.                 SimpleDelegate setQuestion = delegate()                 {                     lblQuestion.Content = question.QuestionText;                     btnYes.IsEnabled = true;                     btnNo.IsEnabled = true;                 };                 this.Dispatcher.BeginInvoke(DispatcherPriority.Send, setQuestion);                 IsReceiving = false;                   // Mark the message as complete.                 msg.Complete();             }         }         else         {             Thread.Sleep(1000);         }     } }     When the user clicks on the Yes or No button, the btnVote_Click method is called. This will create a new Vote data contract with the appropriate question and answer and send the message to the poll manager application using the votes queue. The user voting buttons are then disabled, the question text cleared, and the IsReceiving flag set to true to allow a new message to be received.   private void btnVote_Click(object sender, RoutedEventArgs e) {     // Create a new vote.     Vote vote = new Vote()     {         QuestionText = (string)lblQuestion.Content,         IsYes = ((sender as Button).Content as string).Equals("Yes")     };       // Send the vote message.     BrokeredMessage msg = new BrokeredMessage(vote);     ScatterGatherQueueClient.Send(msg);       // Update the user interface.     lblQuestion.Content = "";     btnYes.IsEnabled = false;     btnNo.IsEnabled = false;     IsReceiving = true; }     Testing the Application In order to test the application, an instance of the poll manager application is started; the user interface is shown below. As no instances of the voting application have been created there are no subscriptions present in the topic. When an instance of the voting application is created the subscription will be displayed in the poll manager. Now that a voting application is subscribing, a questing can be sent from the poll manager application. When the message is sent to the topic, the voting application will receive the message and display the question. The voter can then answer the question by clicking on the appropriate button. The results of the vote are updated in the poll manager application. When two more instances of the voting application are created, the poll manager will display the new subscriptions. More questions can then be broadcast to the voting applications. As the question messages are queued up in the subscription for each voting application, the users can answer the questions in their own time. The vote messages will be received by the poll manager application and aggregated to display the results. The screenshots of the applications part way through voting are shown below. The messages for each voting application are queued up in sequence on the voting application subscriptions, allowing the questions to be answered at different speeds by the voters.

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• SSRS sum(distinct()) equivalent

  - by HurnsMobile

  I am currently working with an SSRS 2008 report that returns a dataset similar to the following: Job# ClientId MoneyIn MoneyOut ------------------------------ 1 ABC123 10 25 1 ABC123 10 25 1 ABC123 5 25 2 XYZ123 25 50 2 XYZ123 25 50 3 XYZ123 15 15 Where MoneyOut should be equal to the total amount of MoneyIn for a job if the job has been balanced out correctly. The problem that I am running into is when displaying this in a tablix in SSRS I can return the correct MoneyOut value for a job by setting the field to =first(Fields!MoneyOut.Value) but I also need to sum the value of these by day and attempting to do =sum(first(Fields!MoneyOut.Value)) yields an error about nesting aggregate functions. I've also attempted to sum the value of the textboxes using something like =sum(ReportItems!MoneyOut1.Value) which yields an error that you can only use aggregates on report items in the header or footer. So my question is, is there some way to duplicate the functionality of distinct() in SSRS reports or is there some way to just total up the values of text fields that I am unaware of? Thanks in advance, TJ

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• vs2010 Linq to SQL -- adding an entity from my DBML

  - by Matt

  I think I may be going crazy here... Anyways, I have a DBML with a table 'User' in it. Pretty simple stuff -- From within a class, I have the following: BusinessDataContext businessDataContext = new BusinessDataContext(); var user = new User(); user.FirstName = FirstName; user.LastName = LastName; user.MiddleInitial = MiddleInitial; user.DateCreated = DateTime.UtcNow; /* There's no businessDataContext.User.Add method -- There's a bunch of generic collection methods with the <> symbols (Aggregate, All, Any...) Am I just too tired and missing something basic or did something simple change with vs 2010? */ businessDataContext.SubmitChanges(); I think I really just need sleep. :-)

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• Design for a machine learning artificial intelligence framework

  - by Lirik

  This is a community wiki which aims to provide a good design for a machine learning/artificial intelligence framework (ML/AI framework). Please contribute to the design of a language-agnostic framework which would allow multiple ML/AI algorithms to be plugged into a single framework which: runs the algorithms with a user-specified data set. facilitates learning, qualification, and classification. allows users to easily plug in new algorithms. can aggregate or create an ensemble of the existing algorithms. can save/load the progress of the algorithm (i.e. save the network and weights of a neural network, save the tree of a decision tree, etc.). What is a good design for this sort of ML/AI framework?

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• Design for a machine learning artificial intelligence framework (community wiki)

  - by Lirik

  This is a community wiki which aims to provide a good design for a machine learning/artificial intelligence framework (ML/AI framework). Please contribute to the design of a language-agnostic framework which would allow multiple ML/AI algorithms to be plugged into a single framework which: runs the algorithms with a user-specified data set. facilitates learning, qualification, and classification. allows users to easily plug in new algorithms. can aggregate or create an ensemble of the existing algorithms. can save/load the progress of the algorithm (i.e. save the network and weights of a neural network, save the tree of a decision tree, etc.). What is a good design for this sort of ML/AI framework?

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• django select max field from mysql when column is varchar

  - by doza

  Hi, Using Django 1.1, I am trying to select the maximum value from a varchar column (in MySQL.) The data stored in the column looks like: 9001 9002 9017 9624 10104 11823 (In reality, the numbers are much bigger than this.) This worked until the numbers incremented above 10000: Feedback.objects.filter(est__pk=est_id).aggregate(sid=Max('sid')) Now, that same line would return 9624 instead of 11823. I'm able to run a query directly in the DB that gives me what I need, but I can't figure out the best way to do this in Django. The query would be: select max(sid+0) from Feedback; Any help would be much appreciated. Thanks!

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• How to store Ruby method references in a database?

  - by Mad Wombat

  I am writing my first rails app. It needs to aggregate some data from multiple sites and for each site I have a unique way of getting the data (some provide RSS, some JSON, for some I scrape the HTML etc.). These will run on schedule, probably as a rake task from cron. It seems logical to store the sites and relevant information in a model, but I am not sure where to put unique data retrieval methods. Do I store method names in the model? Do I just name the methods the same as site name and call them that way? Basically, I need a way to read a list of sites and call appropriate method for each site. What is the Ruby on Rails way to do it?

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• mvc presentation model best-practices

  - by Andrew Florko

  Hello, everybody How do you usually convert business objects to presentation? For example: Business object Person { Id, FirstName, LastName, Patronymic ... } should be presented as "LastName F. P. " in html layout. We use Presentation classes hierarchy to represent data ready for output from Business model. Questions: Will you keep presentation model completely separated from Business Model. For example, can strong-typed views (MVC ASP.NET) aggregate formatted business data as well as raw business objects (that leads toward <%=Html.Encode(PersonHelper.ToShort(Model.Person))% html layout injections) What architecture layer do you choose for conversion (mvc controllers that formats business data from business layer, for instance). Thank you in advance

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• How t have the RDLC pie chart show ranges instead of individual values

  - by Emad

  I have some data coming from a custom dataset that look like the following example Person Age P1 20 P2 21 P3 30 P4 31 P5 40 And I want to develop a pie showing the age distribution against the age. The point is that I want this Age to be shown in ranges. (20-29, 30-39, etc for example So we have: Slice with total number =2 (P1 + P2) as age is 20-29 (one at 20 and another at 21) Slice with total number =3 (P3 + P4) as age is 30-39 (one at 30 and another at 31) Slice with total number =1 (P5) as age is 40 (one at 40). How can i customize the pie chart to aggregate values by ranges that I can define?

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• Are there any existing batch log file aggregation solutions?

  - by Mohan Gulati

  I wish to export from multiple nodes log files (in my case apache access and error logs) and aggregate that data in batch, as a scheduled job. I have seen multiple solutions that work with streaming data (i.e think scribe). I would like a tool that gives me the flexibility to define the destination. This requirement comes from the fact that I want to use HDFS as the destination. I have not been able to find a tool that supports this in batch. Before re-creating the wheel I wanted to ask the StackOverflow community for their input. If a solution exists already in python that would be even better.

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• Passing Custom event arguments to timer_TICK event

  - by Nimesh

  I have class //Create GroupFieldArgs as an EventArgs public class GroupFieldArgs : EventArgs { private string groupName = string.Empty; private int aggregateValue = 0; //Get the fieldName public string GroupName { set { groupName = value; } get { return groupName; } } //Get the aggregate value public int AggregateValue { set { aggregateValue = value; } get { return aggregateValue; } } } I have another class that creates a event handler public class Groupby { public event EventHandler eh; } Finally I have Timer on my form that has Timer_TICK event. I want to pass GroupFieldArgs in Timer_TICK event. What is the best way to do it?

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• Implementing Domain Driven Design

  - by Steve Dunn

  Is anyone using the techniques from Domain Driven Design? I've recently read the Eric Evans book of the same name (well, most of it!) and would be interested to hear from anyone who's implemented all/some of it in a project (particularly in C#/C++) I've kept this question open ended as I'd like to see as many comments as possible, but I have a few questions in particular: 1 - Should value types be real 'value types' if the language supports it? e.g. a struct in C# 2- Is there any feature in C# that makes clearer the association between the language and the model (for instance, this is an entity, this is an aggregate etc.)

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• Domain driven design value object, how to ensure a unique value

  - by Darren

  Hi, I am building a questionnaire creator. A questionnaire consists of sections, sections consist of pages and pages consist of questions. Questionnaire is the aggregate root. Sections, pages and questions can have what are called shortcodes which should be unique within a questionnaire (but not unique within the database hence they are not strictly an identity). I intended to make the shortcode a value object and wanted to include the business rule that it should be unique within the questionnaire but I am unsure how to ensure that. My understanding is that the value object should not access the repository or service layer so how does it find out if it is unique? Thanks for any help. Darren

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• Hadoop 0.2: How to read outputs from TextOutputFormat?

  - by S.N

  My reducer class produces outputs with TextOutputFormat (the default OutputFormat given by Job). I like to consume this outputs after the MapReduce job complete to aggregate the outputs. In addition to this, I like to write out the aggregated information with TextInputFormat so that the output from this process can be consumed by the next iteration of MapReduce task. Can anyone give me an example on how to write & read with TextFormat? By the way, the reason why I am using TextFormat, rather Sequence, is the interoperability. The outputs should be consumed by any software.

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• possible to make text messaging with php have a constant "telephone number" value?

  - by Rees

  hello, i have an iphone 3g and can successfully send text messages using the PHP mail() function. My issue is that for each message i receive, the "telephone number" associated with the incoming text message changes each time. If possible, I would like to somehow make this number constant so that I can take advantage of iphone's ability to aggregate all text messages from the same telephone number -Otherwise my iphone would be cluttered with messages. Is there a way to do this? an example of the numbers I receive would be 1(410) 000-001, 1(410) 000-002, 1(410) 000-003, etc... can i make this constant somehow? $message = stripslashes("new user just joined!"); mail("[email protected]", "Subject", "$message"); please let me know! thanks...

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• Using Java to retrieve the CPU Usage for Window's Processes

  - by stjowa

  Hello all, I am looking for a Java solution to finding the CPU usage for a running process in Windows. After looking around the web, there seems to be little information on a solution in Java. Keep in mind, I am not looking to find the CPU usage for the JVM, but any process running in Windows at the time. I am able to retrieve the memory usage in Java by using the exec("tasklist.exe ... ") to retrieve and parse process information. Although there is an aggregate CPU cycle timer for each process, I do not see a CPU usage column. Any help would be greatly appreciated. Also, if possible, I would like to stay away from C libraries; however, if there is no other alternative, a solution by that means would be appropriate. Thanks a lot, Steve

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• How to produce a merged RSS feed (from DokuWiki and Serendipity)

  - by symcbean

  Hi, I've got an application developed on top of DokuWiki. I'd like to provide a 'News' page providing the latest updates from the internal RSS feed, some other feeds maintained in Serendipity and potentially other locations. Although its trivial to attach feed parsers to each one individually, I'd like to aggregate this into a single list (possibly a single RSS feed). Both the DokuWiki and Serendipity servers are not connected to the internet - so I can't use an external service for this - looking for code. Anybody got any ideas? TIA C.

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• Getting Line Numbers for Errors Thrown in SQL Server CLR Runtime

  - by fetucine53

  Hi all, I've created a CLR stored procedure that I'm running on SQL 2k5 and I'm wondering if there's any way to get line numbers for exceptions thrown by the .NET code. When an Exception is thrown, I get something along the lines of Msg 6522, Level 16, State 1, Procedure myProcedure, Line 0 A .NET Framework error occurred during execution of user-defined routine or aggregate "myProcedure": System.Exception: testing exception System.Exception: at DummyDLL.myProcedure (String dummyInput) . Is there some way I can load the assembly to give me specific line numbers rather than just the function in which the error was thrown? The assembly itself was compiled with a .pdb, but SQL 2k5 doesn't appear to be reading it in when I load the assembly initially. Thanks!

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• Is it possible to "merge" the values of multiple records into a single field without using a stored

  - by j0rd4n

  A co-worker posed this question to me, and I told them, "No, you'll need to write a sproc for that". But I thought I'd give them a chance and put this out to the community. Essentially, they have a table with keys mapping to multiple values. For a report, they want to aggregate on the key and "mash" all of the values into a single field. Here's a visual: --- ------- Key Value --- ------- 1 A 1 B 1 C 2 X 2 Y The result would be as follows: --- ------- Key Value --- ------- 1 A,B,C 2 X,Y They need this in SQLServer 2005. Again, I think they need to write a stored procedure, but if anyone knows a magic out-of-the-box function that does this, I'd be impressed.

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• Finding parents where child collection does not contain an item with a specific property value

  - by Colin Bowern

  I am trying to get a list of parents where the child collection does not contain an item of a specific type. The LINQ equivalent would be something like: dataset.Where(x => x.Items.FirstOrDefault(y => y.Type.Code == "ABC") == null) The object model is Parent Child (Items) Type Code If Parent is my aggregate root, how would I model this in NHibernate criteria/query? Here's my first attempt: var results = session.CreateCriteria<Parent>() .CreateCriteria("Items") .CreateCriteria("Type") .Add(Restrictions.Not(Restrictions.Eq("Code", "ABC"))) .SetResultTransformer(Transformers.DistinctRootEntity) .List<Parent>(); This doesn't seem to return the right entities - it just returns them all.

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• How to optimize Dijkstra algorithm for a single shortest path between 2 nodes?

  - by Nazgulled

  Hi, I was trying to understand this implementation in C of the Dijkstra algorithm and at the same time modify it so that only the shortest path between 2 specific nodes (source and destination) is found. However, I don't know exactly what do to. The way I see it, there's nothing much to do, I can't seem to change d[] or prev[] cause those arrays aggregate some important data for the shortest path calculation. The only thing I can think of is stopping the algorithm when the path is found, that is, break the cycle when mini = destination when it's being marked as visited. Is there anything else I could do to make it better or is that enough? P.S: I just noticed that the for loops start at 1 until <=, why can't it start at 0 and go until <?

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• Aging Data Structure in C#

  - by thelsdj

  I want a data structure that will allow querying how many items in last X minutes. An item may just be a simple identifier or a more complex data structure, preferably the timestamp of the item will be in the item, rather than stored outside (as a hash or similar, wouldn't want to have problems with multiple items having same timestamp). So far it seems that with LINQ I could easily filter items with timestamp greater than a given time and aggregate a count. Though I'm hesitant to try to work .NET 3.5 specific stuff into my production environment yet. Are there any other suggestions for a similar data structure? The other part that I'm interested in is aging old data out, If I'm only going to be asking for counts of items less than 6 hours ago I would like anything older than that to be removed from my data structure because this may be a long-running program.

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