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  • Project Euler Problem 14

    - by MarkPearl
    The Problem The following iterative sequence is defined for the set of positive integers: n n/2 (n is even) n 3n + 1 (n is odd) Using the rule above and starting with 13, we generate the following sequence: 13 40 20 10 5 16 8 4 2 1 It can be seen that this sequence (starting at 13 and finishing at 1) contains 10 terms. Although it has not been proved yet (Collatz Problem), it is thought that all starting numbers finish at 1. Which starting number, under one million, produces the longest chain? NOTE: Once the chain starts the terms are allowed to go above one million. The Solution   public static long NextResultOdd(long n) { return (3 * n) + 1; } public static long NextResultEven(long n) { return n / 2; } public static long TraverseSequence(long n) { long x = n; long count = 1; while (x > 1) { if (x % 2 == 0) x = NextResultEven(x); else x = NextResultOdd(x); count++; } return count; } static void Main(string[] args) { long largest = 0; long pos = 0; for (long i = 1000000; i > 1; i--) { long temp = TraverseSequence(i); if (temp > largest) { largest = temp; pos = i; } } Console.WriteLine("{0} - {1}", pos, largest); Console.ReadLine(); }

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  • The [2] table entry '[3]' has no associated entry in the Media table. (error 2602)

    - by derekf
    Coworker started getting the above message in the event log and as dialog during install.  Argument [2] was File and argument [3] was a specific file. Error dialog read   Product: (app name) -- The installer has encountered an unexpected error installing this package. This may indicate a problem with this package. The error code is 2602. Package was a vendor-provided MSI that had been installed administratively, and then a patch (.msp) applied to the administrative install point. With some digging we found that the MSI still had the entries in the media table pointing at the CAB files, and that there were several files at the end of the sequence that did not have corresponding entries in the Media table (last sequence 990 in Media table, last entry in File table had sequence 994).  Attributes on files in the File table all had the msidbFileAttributesCompressed (&16384) attribute set, so they were all expecting to be within the CAB files, but since this was an admin install there were no CAB files. Resolved by clearing the Media table (replace with a single entry: Disk ID 1, LastSequence 994) and going through the file table and subtracting 8192 from each entry to mark files as not compressed.  Tested and worked.

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  • Click event to a Gwt-connector

    - by sprasad12
    Hi, I am trying to add click event to one of the widgets that use gwt-connector. Here is the code: public class Diagrams extends Diagram implements HasClickHandlers{ public Diagrams(AbsolutePanel boundaryPanel) { super(boundaryPanel); } @Override public HandlerRegistration addClickHandler(ClickHandler handler) { return addDomHandler(handler, ClickEvent.getType()); } @Override public void fireEvent(GwtEvent<?> event) { } } Here Diagram is a gwt-connector class. Here is the link to the Diagram class and also link to GWT-Connector. Question: Am i doing anything wrong in the code while adding the clickhandler? I am getting error saying that addDomHandler is undefined for the type Diagrams. are there limitations for adding click handlers? Any input will be of great help. Thank you.

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  • NetBeans 6.8/6.7 UML Class Diagrams

    - by ikurtz
    i have tried to generate Class Diagrams in NetBeans 6.7 and 6.8 but all i get is: i figured out installing UML for 6.8 here: NetBeans 6.8 UML i have followed the instructions here: UML Class diagrams i so far i failed to generate anything meaningful. i have followed the tips: Open your project, then create a new UML project (choose "Reverse Engineered Java-Platform model"). After that all your classes will be available in the UML project under "Model". You can now create a new class diagram and drag your classes from "Model" onto the diagram. but nothing meaningful happens when i drag my classes to the Class Diagrams. it always represents the classes as "datatype" on the diagram and class info is not displayed. any helpful tips regarding how can i fix this? or another way of generating Java class diagrams? thank you for your time.

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  • Sparx Enterprise Architect conversion (from source to UML)

    - by user228938
    I need to make a UML class diagram for a project. I used Sparx Enterprise Architect in the past to generate source code from a diagram so I'm using that. The project is complete so all of the code is done and I don't really want to write all the classes / functions manually, so I was trying to generate the diagram from the source code but can't seem to find a way to do it. I searched online and on their website but nothing. Any help appreciated. Thanks in advance.

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  • Layering of CSS with z-index

    - by Matt Hintzke
    I have a created a 3 circle venn diagram using pure CSS3 and each circle has a :hover event attached to it. I also have an image of an arrow which is pointing to the center of the venn diagram. I want the arrow to visually appear to be on top of the circles, so I put the z-index higher on the arrow than the circles. The problem now, is that the :hover event does not trigger on half of the venn diagram now because the arrow image is on top, which causes the hover to be on top of the arrow rather than the circle that I want it to be over. So is it possible to make an element have a high z-index visually but not programmatically?

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  • Simple graphics import and manipulation

    - by gnuboi
    What do I need to do something like this? User builds a diagram and tags certain boxes and circles with text. User imports diagram into my program. My program processes the tagged boxes and circles and fills them with different colors. My program exports color-filled diagram. So the questions are... What graphics format supports tag-able boxes and circles? What existing application should I recommend users to use to produce diagrams in the above format? Would this graphics format be very easily readable in code to do things like reading tags and coloring in the associated boxes and circles? Free / open source libraries and apps are desired as this would be for academic use. Thank you!

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  • XmlSchema.read throws exception when an element is declared nillable

    - by G33kKahuna
    I have a simple schema that I am trying to read using XmlSchema.Read() method. I keep getting The 'nillable' attribute is not supported in this context Here is a simple code in C# XmlSchema schema = null; using (StreamReader reader = new StreamReader(<Path to Schema file name>) { schema = XmlSchema.Read(reader.BaseStream, null); } Below is the schema <xs:schema xmlns:b="http://schemas.microsoft.com/BizTalk/2003" xmlns="http://xyz.com.schema.bc.mySchema" attributeFormDefault="unqualified" elementFormDefault="qualified" targetNamespace="http://xyz.com.schema.bc.mySchema" xmlns:xs="http://www.w3.org/2001/XMLSchema"> <xs:element name="data"> <xs:complexType> <xs:sequence> <xs:element name="Component"> <xs:complexType> <xs:sequence> <xs:element minOccurs="1" maxOccurs="unbounded" name="row"> <xs:complexType> <xs:sequence> <xs:element name="changed_by" type="xs:string" nillable="true" /> <xs:element name="column_name" type="xs:string" nillable="true" /> <xs:element name="comment_text" type="xs:string" nillable="true" /> <xs:element name="is_approved" type="xs:string" nillable="true" /> <xs:element name="log_at" type="xs:dateTime" nillable="true" /> <xs:element name="new_val" type="xs:string" nillable="true" /> <xs:element name="old_val" type="xs:string" nillable="true" /> <xs:element name="person_id" type="xs:string" nillable="true" /> <xs:element name="poh_id" type="xs:string" nillable="true" /> <xs:element name="pol_id" type="xs:string" nillable="true" /> <xs:element name="search_name" type="xs:string" nillable="true" /> <xs:element name="unique_id" type="xs:integer" nillable="true" /> </xs:sequence> </xs:complexType> </xs:element> </xs:sequence> </xs:complexType> </xs:element> </xs:complexType> </xs:element> </xs:schema>

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  • Authorizing a computer to access a web application

    - by HackedByChinese
    I have a web application, and am tasked with adding secure sign-on to bolster security, akin to what Google has added to Google accounts. Use Case Essentially, when a user logs in, we want to detect if the user has previously authorized this computer. If the computer has not been authorized, the user is sent a one-time password (via email, SMS, or phone call) that they must enter, where the user may choose to remember this computer. In the web application, we will track authorized devices, allowing users to see when/where they logged in from that device last, and deauthorize any devices if they so choose. We require a solution that is very light touch (meaning, requiring no client-side software installation), and works with Safari, Chrome, Firefox, and IE 7+ (unfortunately). We will offer x509 security, which provides adequate security, but we still need a solution for customers that can't or won't use x509. My intention is to store authorization information using cookies (or, potentially, using local storage, degrading to flash cookies, and then normal cookies). At First Blush Track two separate values (local data or cookies): a hash representing a secure sign-on token, as well as a device token. Both values are driven (and recorded) by the web application, and dictated to the client. The SSO token is dependent on the device as well as a sequence number. This effectively allows devices to be deauthorized (all SSO tokens become invalid) and mitigates replay (not effectively, though, which is why I'm asking this question) through the use of a sequence number, and uses a nonce. Problem With this solution, it's possible for someone to just copy the SSO and device tokens and use in another request. While the sequence number will help me detect such an abuse and thus deauthorize the device, the detection and response can only happen after the valid device and malicious request both attempt access, which is ample time for damage to be done. I feel like using HMAC would be better. Track the device, the sequence, create a nonce, timestamp, and hash with a private key, then send the hash plus those values as plain text. Server does the same (in addition to validating the device and sequence) and compares. That seems much easier, and much more reliable.... assuming we can securely negotiate, exchange, and store private keys. Question So then, how can I securely negotiate a private key for authorized device, and then securely store that key? Is it more possible, at least, if I settle for storing the private key using local storage or flash cookies and just say it's "good enough"? Or, is there something I can do to my original draft to mitigate the vulnerability I describe?

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  • Distinct rand() sequences yielding the same results in an expression

    - by suszterpatt
    Ok, this is a really weird one. I have an MPI program, where each process has to generate random numbers in a fixed range (the range is read from file). What happens is that even though I seed each process with a different value, and the numbers generated by rand() are different in each process, the expression to generate the random numbers still yields the same sequence between them. Here's all relevant code: // 'rank' will be unique for each process int rank; MPI_Comm_rank(MPI_COMM_WORLD, &rank); // seed the RNG with a different value for each process srand(time(NULL) + rank); // print some random numbers to see if we get a unique sequence in each process // 'log' is a uniquely named file, each process has its own log << rand() << " " << rand() << " " << rand() << std::endl; // do boring deterministic stuff while (true) { // waitTimeMin and waitTimeMax are integers, Max is always greater than Min waitSecs = waitTimeMin + rand() % (waitTimeMax - waitTimeMin); log << "waiting " << waitSecs << " seconds" << std::endl; sleep(waitSecs); // do more boring deterministic stuff } Here's the output of each process, with 3 processes generating numbers in the range [1,9]. process 1: 15190 28284 3149 waiting 6 seconds waiting 8 seconds waiting 9 seconds waiting 4 seconds process 2: 286 6264 3153 waiting 6 seconds waiting 8 seconds waiting 9 seconds waiting 4 seconds process 3: 18151 17013 3156 waiting 6 seconds waiting 8 seconds waiting 9 seconds waiting 4 seconds So while rand() clearly generates different numbers, the expression to calculate waitSecs still evaluates to the same sequence on all processes. What's even weirder: if I run the program with the same parameteres again, only the first 3 random numbers will change, the rest of the "random" sequence will be exactly the same in each run! Changing the range of numbers will obviously produce a different result from this one, but the same parameters always yield the same sequence, between processes and between executions: except for the first 3 numbers. Just what the hell is going on here?

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  • Why does JAXB not create a member variable in its generated code when an XML schema base type and subtype have the same element declared in them?

    - by belltower
    I have a question regarding with regard to JAXB generated classes. As you can I see, I have a complex type, DG_PaymentIdentification1, declared in my schema. Its a restriction of PaymentIdentification1. DG_PaymentIdentification1 is also identical to PaymentIdentification1. I also have a type called DG_CreditTransferTransactionInformation10 which has a base type of CreditTransferTransactionInformation10 and is identical to it. I have included the relevant XML schema snippets below. <xs:complexType name="DG_PaymentIdentification1"> <xs:complexContent> <xs:restriction base="PaymentIdentification1"> <xs:sequence> <xs:element name="InstrId" type="DG_Max35Text_REF" minOccurs="0"/> <xs:element name="EndToEndId" type="DG_Max35Text_REF" id="DG-41"/> </xs:sequence> </xs:restriction> </xs:complexContent> </xs:complexType> <xs:complexType name="PaymentIdentification1"> <xs:sequence> <xs:element name="InstrId" type="Max35Text" minOccurs="0"/> <xs:element name="EndToEndId" type="Max35Text"/> </xs:sequence> </xs:complexType> <xs:complexType name="DG_CreditTransferTransactionInformation10"> <xs:complexContent> <xs:restriction base="CreditTransferTransactionInformation10"> <xs:sequence> <xs:element name="PmtId" type="DG_PaymentIdentification1"/> <xs:simpleType name="DG_Max35Text_REF"> <xs:restriction base="DG_NotEmpty35"> <xs:pattern value="[\-A-Za-z0-9\+/\?:\(\)\.,'&#x20;]*"/> </xs:restriction> </xs:simpleType> <xs:simpleType name="Max35Text"> <xs:restriction base="xs:string"> <xs:minLength value="1"/> <xs:maxLength value="35"/> </xs:restriction> </xs:simpleType> JAXB generates the following java class for DG_PaymentIdentification1: @XmlAccessorType(XmlAccessType.FIELD) @XmlType(name = "DG_CreditTransferTransactionInformDGion10") public class DGCreditTransferTransactionInformation10 extends CreditTransferTransactionInformation10 { } My question is why doesnt the DGCreditTransferTransactionInformation10 generated class have a variable of type DG_PaymentIdentification1 in the generated code? The base class CreditTransferTransactionInformation10 does have a type PaymentIdentification1 declared in it. Is there any way of ensuring that DGCreditTransferTransactionInformation10 will have a DG_PaymentIdentification1 in it?

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  • Building Visual Studio Setup Projects with TFS 2010 Team Build

    - by Jakob Ehn
    One of the most common complaints from people starting to use Team Build is that is doesn’t support building Microsoft’s own Setup and Deployment project (*.vdproj). When creating a default build definition that compiles a solution containing a setup project, you’ll get the following warning: The project file "MyProject.vdproj" is not supported by MSBuild and cannot be built.   This is what the problem is all about. MSBuild, that is used for compiling your projects, does not understand the proprietary vdproj format defined by Microsoft quite some time ago. Unfortunately there is no sign that this will change in the near future, in fact the setup projects has barely changed at all since they were introduced. VS 2010 brings no new features or improvements hen it comes to the setup projects. VS 2010 does include a limited version of InstallShield which promises to be more MSBuild friendly and with more or less the same features as VS setup projects. I hope to get a closer look at this installer project type soon. But, how do we go about to build a Visual Studio setup project and produce an MSI as part of a Team Build process? Well, since only one application known to man understands the vdproj projects, we will have to installa copy of Visual Studio on the build server. Sad but true. After doing this, we use the Visual Studio command line interface (devenv) to perform the build. In this post I will show how to do this by using the InvokeProcess activity directly in a build workflow template. You’ll want to run build your setup projects after you have successfully compiled the projects.   Install Visual Studio 2010 on the build server(s)   Open your build process template /remember to branch or copy the xaml file before modifying it!)   Locate the Try to Compile the Project activity   Drop an instance of the InvokeProcess activity from the toolbox onto the designer, after the Run MSBuild for Project activity   Drop an instance of the WriteBuildMessage activity inside the Handle Standard Output section. Set the Importance property to Microsoft.TeamFoundation.Build.Client.BuildMessageImportance.High (NB: This is necessary if you want the output from devenv to show up in the build log when running the build with the default verbosity) Set the Message property to stdOutput   Drop an instance of the WriteBuildError activity to the Handle Error Output section Set the Message property to errOutput   Select the InvokeProcess activity and set the values of the parameters to:     The finished workflow should look like this:     This will generate the MSI files, but they won’t be copied to the drop location. This is because we are using devenv and not MSBuild, so we have to do this explicitly   Drop a Sequence activity somewhere after the Copy to Drop location activity.   Create a variable in the Sequence activity of type IEnumerable<String> and call it GeneratedInstallers   Drop a FindMatchingFiles activity in the sequence activity and set the properties to:     Drop a ForEach<String> activity after the FindMatchingFiles activity. Set the Value property to GeneratedInstallers   Drop an InvokeProcess activity inside the ForEach activity.  FileName: “xcopy.exe” Arguments: String.Format("""{0}"" ""{1}""", item, BuildDetail.DropLocation) The Sequence activity should look like this:     Save the build process template and check it in.   Run the build and verify that the MSI’s is built and copied to the drop location.   Note 1: One of the drawback of using devenv like this in a team build is that since all the output from the default compilations is placed in the Binaries folder, the outputs is not avaialable when devenv is invoked, which causes the whole solution to rebuild again. In TFS 2008, this was pretty simple to fix by using the CustomizableOutDir property. In TFS 2010, the same feature is not avaialble. Jim Lamb blogged about this recently, have a look at it if you have a problem with this: http://blogs.msdn.com/jimlamb/archive/2010/04/13/customizableoutdir-in-tfs-2010.aspx   Note 2: Although the above solution works, a better approach is to wrap this in a custom activity that you can use in your builds. I will come back to this in a future post.

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  • Exploring packages in code

    In my previous post Searching for tasks with code you can see how to explore the control flow side of packages, drilling down through containers, task, and event handlers, but it didn’t cover the data flow. I recently saw a post on the MSDN forum asking how to edit an existing package programmatically, and the sticking point was how to find the the data flow and the components inside. This post builds on some of the previous code and shows how you can explore all objects inside a package. I took the sample Task Search application I’d written previously, and came up with a totally pointless little console application that just walks through the package and writes out the basic type and name of every object it finds, starting with the package itself e.g. Package – MyPackage . The sample package we used last time showed nested objects as well an event handler; a OnPreExecute event tucked away on the task SQL In FEL. The output of this sample tool would look like this: PackageObjects v1.0.0.0 (1.0.0.26627) Copyright (C) 2009 Konesans Ltd Processing File - Z:\Users\Darren Green\Documents\Visual Studio 2005\Projects\SSISTestProject\EventsAndContainersWithExe cSQLForSearch.dtsx Package - EventsAndContainersWithExecSQLForSearch For Loop - FOR Counter Loop Task - SQL In Counter Loop Sequence Container - SEQ For Each Loop Wrapper For Each Loop - FEL Simple Loop Task - SQL In FEL Task - SQL On Pre Execute for FEL SQL Task Sequence Container - SEQ Top Level Sequence Container - SEQ Nested Lvl 1 Sequence Container - SEQ Nested Lvl 2 Task - SQL In Nested Lvl 2 Task - SQL In Nested Lvl 1 #1 Task - SQL In Nested Lvl 1 #2 Connection Manager – LocalHost The code is very similar to what we had previously, but there are a couple of extra bits to deal with connections and to look more closely at a task and see if it is a Data Flow task. For connections your just examine the package's Connections collection as shown in the abridged snippets below. First you can see the call to the ProcessConnections method, followed by the method itself. // Load the package file Application application = new Application(); using (Package package = application.LoadPackage(filename, null)) { // Write out the package name Console.WriteLine("Package - {0}", package.Name); ... More ... // Look and the connections ProcessConnections(package.Connections); } private static void ProcessConnections(Connections connections) { foreach (ConnectionManager connectionManager in connections) { Console.WriteLine("Connection Manager - {0}", connectionManager.Name); } } What we didn’t see in the sample output above was anything to do with the Data Flow, but rest assured the code now handles it too. The following snippet shows how each task is examined to see if it is a Data Flow task, and if so we can then loop through all of the components inside the data flow. private static void ProcessTaskHost(TaskHost taskHost) { if (taskHost == null) { return; } Console.WriteLine("Task - {0}", taskHost.Name); // Check if the task is a Data Flow task MainPipe pipeline = taskHost.InnerObject as MainPipe; if (pipeline != null) { ProcessPipeline(pipeline); } } private static void ProcessPipeline(MainPipe pipeline) { foreach (IDTSComponentMetaData90 componentMetadata in pipeline.ComponentMetaDataCollection) { Console.WriteLine("Pipeline Component - {0}", componentMetadata.Name); // If you wish to make changes to the component then you should really use the managed wrapper. // CManagedComponentWrapper wrapper = componentMetadata.Instantiate(); // wrapper.SetComponentProperty("PropertyName", "Value"); } } Hopefully you can see how we get a reference to the Data Flow task, and then use the ComponentMetaDataCollection to find out what components we have inside the pipeline. If you wanted to know more about the component you could look at the ObjectType or ComponentClassID properties. After that it gets a bit harder and you should get a reference to the wrapper object as the comment suggest and start using the properties, just like you would in the create packages samples, see our Code Development category for some for these examples. Download Sample code project PackageObjects.zip (5KB)

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  • Exploring packages in code

    In my previous post Searching for tasks with code you can see how to explore the control flow side of packages, drilling down through containers, task, and event handlers, but it didn’t cover the data flow. I recently saw a post on the MSDN forum asking how to edit an existing package programmatically, and the sticking point was how to find the the data flow and the components inside. This post builds on some of the previous code and shows how you can explore all objects inside a package. I took the sample Task Search application I’d written previously, and came up with a totally pointless little console application that just walks through the package and writes out the basic type and name of every object it finds, starting with the package itself e.g. Package – MyPackage . The sample package we used last time showed nested objects as well an event handler; a OnPreExecute event tucked away on the task SQL In FEL. The output of this sample tool would look like this: PackageObjects v1.0.0.0 (1.0.0.26627) Copyright (C) 2009 Konesans Ltd Processing File - Z:\Users\Darren Green\Documents\Visual Studio 2005\Projects\SSISTestProject\EventsAndContainersWithExe cSQLForSearch.dtsx Package - EventsAndContainersWithExecSQLForSearch For Loop - FOR Counter Loop Task - SQL In Counter Loop Sequence Container - SEQ For Each Loop Wrapper For Each Loop - FEL Simple Loop Task - SQL In FEL Task - SQL On Pre Execute for FEL SQL Task Sequence Container - SEQ Top Level Sequence Container - SEQ Nested Lvl 1 Sequence Container - SEQ Nested Lvl 2 Task - SQL In Nested Lvl 2 Task - SQL In Nested Lvl 1 #1 Task - SQL In Nested Lvl 1 #2 Connection Manager – LocalHost The code is very similar to what we had previously, but there are a couple of extra bits to deal with connections and to look more closely at a task and see if it is a Data Flow task. For connections your just examine the package's Connections collection as shown in the abridged snippets below. First you can see the call to the ProcessConnections method, followed by the method itself. // Load the package file Application application = new Application(); using (Package package = application.LoadPackage(filename, null)) { // Write out the package name Console.WriteLine("Package - {0}", package.Name); ... More ... // Look and the connections ProcessConnections(package.Connections); } private static void ProcessConnections(Connections connections) { foreach (ConnectionManager connectionManager in connections) { Console.WriteLine("Connection Manager - {0}", connectionManager.Name); } } What we didn’t see in the sample output above was anything to do with the Data Flow, but rest assured the code now handles it too. The following snippet shows how each task is examined to see if it is a Data Flow task, and if so we can then loop through all of the components inside the data flow. private static void ProcessTaskHost(TaskHost taskHost) { if (taskHost == null) { return; } Console.WriteLine("Task - {0}", taskHost.Name); // Check if the task is a Data Flow task MainPipe pipeline = taskHost.InnerObject as MainPipe; if (pipeline != null) { ProcessPipeline(pipeline); } } private static void ProcessPipeline(MainPipe pipeline) { foreach (IDTSComponentMetaData90 componentMetadata in pipeline.ComponentMetaDataCollection) { Console.WriteLine("Pipeline Component - {0}", componentMetadata.Name); // If you wish to make changes to the component then you should really use the managed wrapper. // CManagedComponentWrapper wrapper = componentMetadata.Instantiate(); // wrapper.SetComponentProperty("PropertyName", "Value"); } } Hopefully you can see how we get a reference to the Data Flow task, and then use the ComponentMetaDataCollection to find out what components we have inside the pipeline. If you wanted to know more about the component you could look at the ObjectType or ComponentClassID properties. After that it gets a bit harder and you should get a reference to the wrapper object as the comment suggest and start using the properties, just like you would in the create packages samples, see our Code Development category for some for these examples. Download Sample code project PackageObjects.zip (5KB)

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  • Strings in .NET are Enumerable

    - by Scott Dorman
    It seems like there is always some confusion concerning strings in .NET. This is both from developers who are new to the Framework and those that have been working with it for quite some time. Strings in the .NET Framework are represented by the System.String class, which encapsulates the data manipulation, sorting, and searching methods you most commonly perform on string data. In the .NET Framework, you can use System.String (which is the actual type name or the language alias (for C#, string). They are equivalent so use whichever naming convention you prefer but be consistent. Common usage (and my preference) is to use the language alias (string) when referring to the data type and String (the actual type name) when accessing the static members of the class. Many mainstream programming languages (like C and C++) treat strings as a null terminated array of characters. The .NET Framework, however, treats strings as an immutable sequence of Unicode characters which cannot be modified after it has been created. Because strings are immutable, all operations which modify the string contents are actually creating new string instances and returning those. They never modify the original string data. There is one important word in the preceding paragraph which many people tend to miss: sequence. In .NET, strings are treated as a sequence…in fact, they are treated as an enumerable sequence. This can be verified if you look at the class declaration for System.String, as seen below: // Summary:// Represents text as a series of Unicode characters.public sealed class String : IEnumerable, IComparable, IComparable<string>, IEquatable<string> The first interface that String implements is IEnumerable, which has the following definition: // Summary:// Exposes the enumerator, which supports a simple iteration over a non-generic// collection.public interface IEnumerable{ // Summary: // Returns an enumerator that iterates through a collection. // // Returns: // An System.Collections.IEnumerator object that can be used to iterate through // the collection. IEnumerator GetEnumerator();} As a side note, System.Array also implements IEnumerable. Why is that important to know? Simply put, it means that any operation you can perform on an array can also be performed on a string. This allows you to write code such as the following: string s = "The quick brown fox";foreach (var c in s){ System.Diagnostics.Debug.WriteLine(c);}for (int i = 0; i < s.Length; i++){ System.Diagnostics.Debug.WriteLine(s[i]);} If you executed those lines of code in a running application, you would see the following output in the Visual Studio Output window: In the case of a string, these enumerable or array operations return a char (System.Char) rather than a string. That might lead you to believe that you can get around the string immutability restriction by simply treating strings as an array and assigning a new character to a specific index location inside the string, like this: string s = "The quick brown fox";s[2] = 'a';   However, if you were to write such code, the compiler will promptly tell you that you can’t do it: This preserves the notion that strings are immutable and cannot be changed once they are created. (Incidentally, there is no built in way to replace a single character like this. It can be done but it would require converting the string to a character array, changing the appropriate indexed location, and then creating a new string.)

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  • Following the Thread in OSB

    - by Antony Reynolds
    Threading in OSB The Scenario I recently led an OSB POC where we needed to get high throughput from an OSB pipeline that had the following logic: 1. Receive Request 2. Send Request to External System 3. If Response has a particular value   3.1 Modify Request   3.2 Resend Request to External System 4. Send Response back to Requestor All looks very straightforward and no nasty wrinkles along the way.  The flow was implemented in OSB as follows (see diagram for more details): Proxy Service to Receive Request and Send Response Request Pipeline   Copies Original Request for use in step 3 Route Node   Sends Request to External System exposed as a Business Service Response Pipeline   Checks Response to Check If Request Needs to Be Resubmitted Modify Request Callout to External System (same Business Service as Route Node) The Proxy and the Business Service were each assigned their own Work Manager, effectively giving each of them their own thread pool. The Surprise Imagine our surprise when, on stressing the system we saw it lock up, with large numbers of blocked threads.  The reason for the lock up is due to some subtleties in the OSB thread model which is the topic of this post.   Basic Thread Model OSB goes to great lengths to avoid holding on to threads.  Lets start by looking at how how OSB deals with a simple request/response routing to a business service in a route node. Most Business Services are implemented by OSB in two parts.  The first part uses the request thread to send the request to the target.  In the diagram this is represented by the thread T1.  After sending the request to the target (the Business Service in our diagram) the request thread is released back to whatever pool it came from.  A multiplexor (muxer) is used to wait for the response.  When the response is received the muxer hands off the response to a new thread that is used to execute the response pipeline, this is represented in the diagram by T2. OSB allows you to assign different Work Managers and hence different thread pools to each Proxy Service and Business Service.  In out example we have the “Proxy Service Work Manager” assigned to the Proxy Service and the “Business Service Work Manager” assigned to the Business Service.  Note that the Business Service Work Manager is only used to assign the thread to process the response, it is never used to process the request. This architecture means that while waiting for a response from a business service there are no threads in use, which makes for better scalability in terms of thread usage. First Wrinkle Note that if the Proxy and the Business Service both use the same Work Manager then there is potential for starvation.  For example: Request Pipeline makes a blocking callout, say to perform a database read. Business Service response tries to allocate a thread from thread pool but all threads are blocked in the database read. New requests arrive and contend with responses arriving for the available threads. Similar problems can occur if the response pipeline blocks for some reason, maybe a database update for example. Solution The solution to this is to make sure that the Proxy and Business Service use different Work Managers so that they do not contend with each other for threads. Do Nothing Route Thread Model So what happens if there is no route node?  In this case OSB just echoes the Request message as a Response message, but what happens to the threads?  OSB still uses a separate thread for the response, but in this case the Work Manager used is the Default Work Manager. So this is really a special case of the Basic Thread Model discussed above, except that the response pipeline will always execute on the Default Work Manager.   Proxy Chaining Thread Model So what happens when the route node is actually calling a Proxy Service rather than a Business Service, does the second Proxy Service use its own Thread or does it re-use the thread of the original Request Pipeline? Well as you can see from the diagram when a route node calls another proxy service then the original Work Manager is used for both request pipelines.  Similarly the response pipeline uses the Work Manager associated with the ultimate Business Service invoked via a Route Node.  This actually fits in with the earlier description I gave about Business Services and by extension Route Nodes they “… uses the request thread to send the request to the target”. Call Out Threading Model So what happens when you make a Service Callout to a Business Service from within a pipeline.  The documentation says that “The pipeline processor will block the thread until the response arrives asynchronously” when using a Service Callout.  What this means is that the target Business Service is called using the pipeline thread but the response is also handled by the pipeline thread.  This implies that the pipeline thread blocks waiting for a response.  It is the handling of this response that behaves in an unexpected way. When a Business Service is called via a Service Callout, the calling thread is suspended after sending the request, but unlike the Route Node case the thread is not released, it waits for the response.  The muxer uses the Business Service Work Manager to allocate a thread to process the response, but in this case processing the response means getting the response and notifying the blocked pipeline thread that the response is available.  The original pipeline thread can then continue to process the response. Second Wrinkle This leads to an unfortunate wrinkle.  If the Business Service is using the same Work Manager as the Pipeline then it is possible for starvation or a deadlock to occur.  The scenario is as follows: Pipeline makes a Callout and the thread is suspended but still allocated Multiple Pipeline instances using the same Work Manager are in this state (common for a system under load) Response comes back but all Work Manager threads are allocated to blocked pipelines. Response cannot be processed and so pipeline threads never unblock – deadlock! Solution The solution to this is to make sure that any Business Services used by a Callout in a pipeline use a different Work Manager to the pipeline itself. The Solution to My Problem Looking back at my original workflow we see that the same Business Service is called twice, once in a Routing Node and once in a Response Pipeline Callout.  This was what was causing my problem because the response pipeline was using the Business Service Work Manager, but the Service Callout wanted to use the same Work Manager to handle the responses and so eventually my Response Pipeline hogged all the available threads so no responses could be processed. The solution was to create a second Business Service pointing to the same location as the original Business Service, the only difference was to assign a different Work Manager to this Business Service.  This ensured that when the Service Callout completed there were always threads available to process the response because the response processing from the Service Callout had its own dedicated Work Manager. Summary Request Pipeline Executes on Proxy Work Manager (WM) Thread so limited by setting of that WM.  If no WM specified then uses WLS default WM. Route Node Request sent using Proxy WM Thread Proxy WM Thread is released before getting response Muxer is used to handle response Muxer hands off response to Business Service (BS) WM Response Pipeline Executes on Routed Business Service WM Thread so limited by setting of that WM.  If no WM specified then uses WLS default WM. No Route Node (Echo functionality) Proxy WM thread released New thread from the default WM used for response pipeline Service Callout Request sent using proxy pipeline thread Proxy thread is suspended (not released) until the response comes back Notification of response handled by BS WM thread so limited by setting of that WM.  If no WM specified then uses WLS default WM. Note this is a very short lived use of the thread After notification by callout BS WM thread that thread is released and execution continues on the original pipeline thread. Route/Callout to Proxy Service Request Pipeline of callee executes on requestor thread Response Pipeline of caller executes on response thread of requested proxy Throttling Request message may be queued if limit reached. Requesting thread is released (route node) or suspended (callout) So what this means is that you may get deadlocks caused by thread starvation if you use the same thread pool for the business service in a route node and the business service in a callout from the response pipeline because the callout will need a notification thread from the same thread pool as the response pipeline.  This was the problem we were having. You get a similar problem if you use the same work manager for the proxy request pipeline and a business service callout from that request pipeline. It also means you may want to have different work managers for the proxy and business service in the route node. Basically you need to think carefully about how threading impacts your proxy services. References Thanks to Jay Kasi, Gerald Nunn and Deb Ayers for helping to explain this to me.  Any errors are my own and not theirs.  Also thanks to my colleagues Milind Pandit and Prasad Bopardikar who travelled this road with me. OSB Thread Model Great Blog Post on Thread Usage in OSB

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  • Types of ER Diagrams

    - by syrion
    I'm currently taking a class for database design, and we're using the ER diagram style designed by Peter Chen. I have a couple of problems with this style: Keys in relationships don't seem realistic. In practice, synthetic keys like "orderid" seem to be used in almost all tables, including association tables, but the Chen style diagrams heavily favor (table1key, table2key) compound keys. There is no notation for datatype. The diamond shape for associations is horrible, and produces a cluttered diagram. In general, it just seems hard to capture some relationships with the Chen system. What ERD style, if any, do you use? What has been the most popular in your workplaces? What tools have you used, or do you use, to create these diagrams?

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  • The Best Websites and Software for Brainstorming and Mind Mapping

    - by Lori Kaufman
    A mind map is a diagram that allows you to visually outline information, helping you organize, solve problems, and make decisions. Start with a single idea in the center of the diagram and add associated ideas, words, and concepts connected radially around the central idea. We’ve collected links to websites and software that can help you create mind maps, and collaborate on and share your maps with others. The programs and websites listed here are all either free or have a free option. How To Delete, Move, or Rename Locked Files in Windows HTG Explains: Why Screen Savers Are No Longer Necessary 6 Ways Windows 8 Is More Secure Than Windows 7

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  • What is a non commital approach to software analysis

    - by dsjbirch
    When I think about software analysis the first thing which comes to mind is SSADM and the UML. But, what I want is a high level view of the system before I commit to a programming paradigm. Where am I going wrong? How do I approach a problem in a high level and generic way before I commit to a paradigm? What are the diagrams/tools available to support me? Edit: Some examples of tools that appear to be what I'm after are... A block diagram - http://en.wikipedia.org/wiki/Block_diagram A data flow diagram - http://en.wikipedia.org/wiki/Data_flow_diagram

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  • Do real developers use UML and other CASE tools?

    - by Avi
    I'm a CS student, currently a junior, and in one of my classes this semester they have us studying all sorts of UML diagramming methods. Among others, we've touched on Petri nets, DFD diagrams, sequence diagrams, use case diagrams, collaboration diagrams, Jackson System Development diagrams, entity-relation diagrams, and more. I've worked on more than a few professional projects over the years and never encountered anyone who used these systems to any great degree (other than a general class diagram or a diagram of the tables in a database). I was just wondering if I could query the hive mind to see if this is true in your work experience too. Have you used these models at all and found them to be as important as they tell us students they are? Or is all this stuff just academic ivory-tower crap that people in the real world hardly ever touch? Which of these systems have you found to be effective and useful? Are there specific kinds of scenarios that they are more intended to be used in than what the typical software developer encounters?

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  • UML Class diagrams with Java packages?

    - by loosebruce
    I am trying to model in UML 2.0 a Java servlet application that has three classes Servlet class; essentially a main class that acts as the controller DatabaseLogic; contains methods for database operations XMLBuilder; builds an XML from a query result string The classes use a variety of packages from the Java library. I am unsure how to model this in UML Do I have to create a package and show which libraries are used for each individual class or can I just have one large package in the diagram with all the libraries showing which classes have dependencies on which. As per this diagram This is my first time working with java properly (im a C++ guy) Apart from being a bit messy , is this a correct UML representation of the system I described? Does a Package in UML mean the same as a Package in Java?

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  • OOD: All classes at bottom of hierarchy contain the same field

    - by My Head Hurts
    I am creating a class diagram for what I thought was a fairly simple problem. However, when I get to the bottom of the hierarchy, all of the classes only contain one field and it is the same one. This to me looks very wrong, but this field does not belong in any of the parent classes. I was wondering if there are any suggested design patterns in a situation like this? A simplified version of the class diagram can be found below. Note, fields named differently cannot belong to any other class +------------------+ | ObjectA | |------------------| | String one | | String two | | | +---------+--------+ | +---------------+----------------+ | | +--------|--------+ +--------|--------+ | ObjectAA | | ObjectAB | |-----------------| |-----------------| | String three | | String four | | | | | +--------+--------+ +--------+--------+ | | | | +--------|--------+ +--------|--------+ | ObjectAAA | | ObjectABA | |-----------------| |-----------------| | String five | | String five | | | | | +-----------------+ +-----------------+ ASCII tables drawn using http://www.asciiflow.com/

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  • Wiki based requirements engineering tool

    - by Shanon
    Hi, I'm looking to to build a wiki based tool the helps/aides in the requirements engineering process. More specifically I am hoping to end up with a tool that helps inexperienced users easily create and design requirements documents on a wiki platform. I was wondering if there exist any wiki/wiki platforms that either already exist or are easily extendible or would be worth looking at that for this purpose. For instance some of the features I was hoping to add would be to add structure to a document so that information is filled out in a standardised manner. Another idea I was looking at was to somehow create relationships between different types of documents (for example- a goal diagram gets evolves/ helps in the development of the class diagram). So far I have come across FOSwiki which claims to to fully customisalble...but I'm not sure what it means and what I can really do with that. Any input on FOSwiki is also highly appreciated.

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  • Problem hosting WebBrowser control in an ATL app.

    - by Andrew Bucknell
    I have a legacy atl app that hosts a webbrowser control in an ATL window. I create an instance of the client to host the browser using the following sequence CComPtr<IOleObject> spOleObject; HRESULT hr = CoCreateInstance(CLSID_WebBrowser, NULL, CLSCTX_INPROC, ID_IOleObject,(void**)&spOleObject); spOleObject->SetClientSite(this); GetClientRect(&rcClient); hr = spOleObject->DoVerb(OLEIVERB_INPLACEACTIVATE, &msg, this, 0, m_hWnd, &rcClient); hr = AtlAdvise(m_spWebBrowser, GetUnknown(), DIID_DWebBrowserEvents2, &m_dwCookie); CComVariant navvar(navurl); m_spWebBrowser->Navigate2(&navvar, NULL, NULL, NULL, NULL); This sequence works fine to create the initial browse window. The call to navigate2 works and if I look at the window via spy++ I have Shell Embedding - Shell DocObject View - Internet Explorer_Server. When a popup occurs (detected through NewWindow3) I launch a new window and execute the same code sequence for the new window. In the popup window the navigate2 doesnt work, and when I look at this new window in spy++ I just have Shell Embedding. I get the same problem even if I instantiate the popup window on startup, so its not related to NewWindow3 at all - it seems the second instance of the web control isnt instantiating even though all the calls return S_OK. This sequence worked fine under IE7 but now I am using IE8 and the popup window isnt working. There is clearly something I am missing but I cant guess what it may be. Any suggestions would be incredibly helpful.

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  • Using complex data types from Java in Axis webservice

    - by Manuel Ferreria
    I am currently developing a Java app which handles a SOAP webservice. The problem lies after I parse the WSDL [the Parser object from Apache Axis does it for me], and I create the call. When I try to invoke it, I have to pass a Object[] to assign the parameters [taken from the Action of the WSDL]. A normal action is easy, but when I have custom datatypes, I can't get it to fill it out for me. I try to pass Object[]{ new Object { }}, but it assigns the first field instead. I can't pass it already processed, because it changes the '< ' to '--lt --gt', and the server doesn't recognize it'. This is a fragment of the WSDL. <s:element name="FERecuperaQTYRequest"> <s:complexType> <s:sequence> <s:element minOccurs="0" maxOccurs="1" name="argAuth" type="tns:FEAuthRequest" /> </s:sequence> </s:complexType> </s:element> <s:complexType name="FEAuthRequest"> <s:sequence> <s:element minOccurs="0" maxOccurs="1" name="Token" type="s:string" /> <s:element minOccurs="0" maxOccurs="1" name="Sign" type="s:string" /> <s:element minOccurs="1" maxOccurs="1" name="cuit" type="s:long" /> </s:sequence> </s:complexType> And this is the troublesome Java Fragment QTY = (String) call.invoke ( new Object[]{ new Object[]{ tokenConexion.getToken (), tokenConexion.getSign (), tokenConexion.getCUIT () } });

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