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  • Implementing Linked Lists in C#

    - by nijhawan.saurabh
    Why? The question is why you need Linked Lists and why it is the foundation of any Abstract Data Structure. Take any of the Data Structures - Stacks, Queues, Heaps, Trees; there are two ways to go about implementing them - Using Arrays Using Linked Lists Now you use Arrays when you know about the size of the Nodes in the list at Compile time and Linked Lists are helpful where you are free to add as many Nodes to the List as required at Runtime.   How? Now, let's see how we go about implementing a Simple Linked List in C#. Note: We'd be dealing with singly linked list for time being, there's also another version of linked lists - the Doubly Linked List which maintains two pointers (NEXT and BEFORE).   Class Diagram Let's see the Class Diagram first:     Code     1 // -----------------------------------------------------------------------     2 // <copyright file="Node.cs" company="">     3 // TODO: Update copyright text.     4 // </copyright>     5 // -----------------------------------------------------------------------     6      7 namespace CSharpAlgorithmsAndDS     8 {     9     using System;    10     using System.Collections.Generic;    11     using System.Linq;    12     using System.Text;    13     14     /// <summary>    15     /// TODO: Update summary.    16     /// </summary>    17     public class Node    18     {    19         public Object data { get; set; }    20     21         public Node Next { get; set; }    22     }    23 }    24         1 // -----------------------------------------------------------------------     2 // <copyright file="LinkedList.cs" company="">     3 // TODO: Update copyright text.     4 // </copyright>     5 // -----------------------------------------------------------------------     6      7 namespace CSharpAlgorithmsAndDS     8 {     9     using System;    10     using System.Collections.Generic;    11     using System.Linq;    12     using System.Text;    13     14     /// <summary>    15     /// TODO: Update summary.    16     /// </summary>    17     public class LinkedList    18     {    19         private Node Head;    20     21         public void AddNode(Node n)    22         {    23             n.Next = this.Head;    24             this.Head = n;    25     26         }    27     28         public void printNodes()    29         {    30     31             while (Head!=null)    32             {    33                 Console.WriteLine(Head.data);    34                 Head = Head.Next;    35     36             }    37     38         }    39     }    40 }    41          1 using System;     2 using System.Collections.Generic;     3 using System.Linq;     4 using System.Text;     5      6 namespace CSharpAlgorithmsAndDS     7 {     8     class Program     9     {    10         static void Main(string[] args)    11         {    12             LinkedList ll = new LinkedList();    13             Node A = new Node();    14             A.data = "A";    15     16             Node B = new Node();    17             B.data = "B";    18     19             Node C = new Node();    20             C.data = "C";    21             ll.AddNode(A);    22             ll.AddNode(B);    23             ll.AddNode(C);    24     25             ll.printNodes();    26         }    27     }    28 }    29        Final Words This is just a start, I will add more posts on Linked List covering more operations like Delete etc. and will also explore Doubly Linked List / Implementing Stacks/ Heaps/ Trees / Queues and what not using Linked Lists.   Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;}

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  • Trace File Source Adapter

    The Trace File Source adapter is a useful addition to your SSIS toolbox.  It allows you to read 2005 and 2008 profiler traces stored as .trc files and read them into the Data Flow.  From there you can perform filtering and analysis using the power of SSIS. There is no need for a SQL Server connection this just uses the trace file. Example Usages Cache warming for SQL Server Analysis Services Reading the flight recorder Find out the longest running queries on a server Analyze statements for CPU, memory by user or some other criteria you choose Properties The Trace File Source adapter has two properties, both of which combine to control the source trace file that is read at runtime. SQL Server 2005 and SQL Server 2008 trace files are supported for both the Database Engine (SQL Server) and Analysis Services. The properties are managed by the Editor form or can be set directly from the Properties Grid in Visual Studio. Property Type Description AccessMode Enumeration This property determines how the Filename property is interpreted. The values available are: DirectInput Variable Filename String This property holds the path for trace file to load (*.trc). The value is either a full path, or the name of a variable which contains the full path to the trace file, depending on the AccessMode property. Trace Column Definition Hopefully the majority of you can skip this section entirely, but if you encounter some problems processing a trace file this may explain it and allow you to fix the problem. The component is built upon the trace management API provided by Microsoft. Unfortunately API methods that expose the schema of a trace file have known issues and are unreliable, put simply the data often differs from what was specified. To overcome these limitations the component uses  some simple XML files. These files enable the trace column data types and sizing attributes to be overridden. For example SQL Server Profiler or TMO generated structures define EventClass as an integer, but the real value is a string. TraceDataColumnsSQL.xml  - SQL Server Database Engine Trace Columns TraceDataColumnsAS.xml    - SQL Server Analysis Services Trace Columns The files can be found in the %ProgramFiles%\Microsoft SQL Server\100\DTS\PipelineComponents folder, e.g. "C:\Program Files\Microsoft SQL Server\100\DTS\PipelineComponents\TraceDataColumnsSQL.xml" "C:\Program Files\Microsoft SQL Server\100\DTS\PipelineComponents\TraceDataColumnsAS.xml" If at runtime the component encounters a type conversion or sizing error it is most likely due to a discrepancy between the column definition as reported by the API and the actual value encountered. Whilst most common issues have already been fixed through these files we have implemented specific exception traps to direct you to the files to enable you to fix any further issues due to different usage or data scenarios that we have not tested. An example error that you can fix through these files is shown below. Buffer exception writing value to column 'Column Name'. The string value is 999 characters in length, the column is only 111. Columns can be overridden by the TraceDataColumns XML files in "C:\Program Files\Microsoft SQL Server\100\DTS\PipelineComponents\TraceDataColumnsAS.xml". Installation The component is provided as an MSI file which you can download and run to install it. This simply places the files on disk in the correct locations and also installs the assemblies in the Global Assembly Cache as per Microsoft’s recommendations. You may need to restart the SQL Server Integration Services service, as this caches information about what components are installed, as well as restarting any open instances of Business Intelligence Development Studio (BIDS) / Visual Studio that you may be using to build your SSIS packages. Finally you will have to add the transformation to the Visual Studio toolbox manually. Right-click the toolbox, and select Choose Items.... Select the SSIS Data Flow Items tab, and then check the Trace File Source transformation in the Choose Toolbox Items window. This process has been described in detail in the related FAQ entry for How do I install a task or transform component? We recommend you follow best practice and apply the current Microsoft SQL Server Service pack to your SQL Server servers and workstations. Please note that the Microsoft Trace classes used in the component are not supported on 64-bit platforms. To use the Trace File Source on a 64-bit host you need to ensure you have the 32-bit (x86) tools available, and the way you execute your package is setup to use them, please see the help topic 64-bit Considerations for Integration Services for more details. Downloads Trace Sources for SQL Server 2005 -- Trace Sources for SQL Server 2008 Version History SQL Server 2008 Version 2.0.0.382 - SQL Sever 2008 public release. (9 Apr 2009) SQL Server 2005 Version 1.0.0.321 - SQL Server 2005 public release. (18 Nov 2008) -- Screenshots

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  • 12c??? - Active Data Guard Far Sync

    - by Jian Zhang(??)
    ?? ================ Active Data Guard Far Sync?Oracle 12c????(???Far Sync Standby),Far Sync?????????????(Primary Database)?????????Far Sync??,??(Primary Database) ??(synchronous)??redo?Far Sync??,??Far Sync????redo??(asynchronous)???????(Standby Database)???????????????????????Far Sync????????,init?????????,???????? ??redo ????Maximum Availability??,???????????(Primary Database)?????????Far Sync??,??(Primary Database)??(synchronous)??redo?Far Sync??,???????(zero data loss),?????Far Sync????,??????,??????????????Far Sync????redo??(asynchronous)???????(Standby Database)? ??redo ????Maximum Performance??,???????????(Primary Database)?????????Far Sync??,??(Primary Database) ????redo?Far Sync??,??Far Sync???????redo?????????(Standby Database)????????????????(Standby Database)??redo???(offload)? Far Sync????Data Guard ????(role transitions)????,?switchover/failover?????12c????? ???????Data Guard ????,?switchover/failover,???????????????Far Sync??,??Far Sync???????????????????? ???Far Sync???????,??????????????2?Far Sync??,???????? ???????Far Sync????? Far Sync??? ================ ????Far Sync ================ 1. ??Data Guard,???11.2??,??????«Active Database Duplication for A standby database» 2. ????Far Sync??,Far Sync????????,init?????????,???????? ??Far Sync???????,?????: SQL> ALTER DATABASE CREATE FAR SYNC INSTANCE CONTROLFILE AS '/tmp/controlfs01.ctl'; 3. ????redo?????Far Sync??,????LOG_ARCHIVE_DEST_2??: LOG_ARCHIVE_DEST_2='SERVICE=dg12cfs SYNC AFFIRM MAX_FAILURE=1 ALTERNATE=LOG_ARCHIVE_DEST_3 VALID_FOR=(ONLINE_LOGFILES,PRIMARY_ROLE) DB_UNIQUE_NAME=dg12cfs' 4. ??Far Sync??????redo???,??Far Sync??LOG_ARCHIVE_DEST_2??: LOG_ARCHIVE_DEST_2='SERVICE=dg12cs ASYNC VALID_FOR=(STANDBY_LOGFILES,STANDBY_ROLE) DB_UNIQUE_NAME=dg12cs' 5. ????Far Sync???????,??????????????2?Far Sync??? 6. ???????: SQL> select * from  V$DATAGUARD_CONFIG; DB_UNIQUE_NAME       PARENT_DBUN       DEST_ROLE         CURRENT_SCN     CON_ID ------------------------------ ------------------------------     ----------------- ----------- ---------- dg12cfs                        dg12cp          FAR SYNC INSTANCE      682995          0 dg12cs                         dg12cfs         PHYSICAL STANDBY       682995          0 dg12cp                        NONE             PRIMARY DATABASE      683138          0 ????????????????:Oracle_12c_Active_Data_Guard_Far_Sync_v1.pdf

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  • Oracle GoldenGate 12c - Leading Enterprise Replication

    - by Doug Reid
    Oracle GoldenGate 12c released  on October 17th and includes several new cutting edge features that firmly establishes GoldenGate's leader position in the data replication space.   In fact, this release more than doubles the performance of data delivery, supports Oracle's new multitenant database feature,  it's more secure, has more options for high availability, and has made great strides to simplify the configuration and deployment of the product.     Read through the press release if you haven't already and do not miss the quote from Cern's Eva Dafonte Perez, regarding Oracle GoldenGate 12c "….performs five times faster compared to previous GoldenGate versions and simplifies the management of a multi-tier environment" There are a variety of new and improved features in the Oracle GoldenGate 12c.  Here are the highlights: Optimized for Oracle Database 12c -  GoldenGate 12c is custom tailored to the unique capabilities of Oracle database 12c and out of the box GoldenGate 12c supports multitenant (pluggable database (PDB)) and non-consolidated deployments of Oracle Database 12c.   The naming convention used by database 12c is now in three parts (PDB-name, schema-name, and object name).  We have made changes to the GoldenGate capture process to support the new naming convention and streamlined the whole process so a single GoldenGate capture process is being used at the container level rather than at each individual PDB.  By having the capture process at the container level resource usage and the number of processes are reduced. To view a conceptual architecture diagram click here. Integrated Delivery for the Oracle Database - Leveraging a lightweight streaming API built exclusively for Oracle GoldenGate 12c, this process distributes load, auto tunes the degree of parallelism, scales better, and delivers blinding rates of changed data delivery to the Oracle database.  One of the goals for Oracle GoldenGate 12c was to reduce IT costs by simplifying the configuration and reduce the time to manage complex infrastructures.  In previous versions of Oracle GoldenGate, customers would split transaction loads by grouping tables into multiple different delivery processes (click here to view the previous method). Each delivery process executed independently and without any interaction or knowledge of other delivery processes.  This setup was complicated to configure and time consuming as the developer needed in-depth knowledge of the source and target schemas and the transaction profile. With GoldenGate 12c and Integrated Delivery we have made it easier to configure and faster to deploy.  To view a conceptual architecture diagram of integrated delivery click here Coordinated Delivery for Non-Oracle Databases - Coordinated Delivery orchestrates high-speed apply processes and simplifies the configuration of GoldenGate for non-Oracle targets. In Oracle GoldenGate 12c a single delivery process is used with multiple threads (click here) and key events, such as primary key updates, event markers, DDL, etc, are coordinated between the various threads to insure that the transactions are applied in the same sequence as they were captured, all while delivery improved performance.  Replication Between On-Premises and Cloud-Based systems. - The trend for business to utilize both on-premises and cloud-based systems is rising and businesses need to replicate data back and forth.   GoldenGate 12c can be configured in a variety of ways to provide real-time replication when unrestricted or restricted (limited ports or HTTP tunneling) networks are between on-premises and cloud-based systems.    Expanded Heterogeneity - It wouldn't be a GoldenGate release without new and improved platform support.   Release 1 includes support for MySQL 5.6 and Sybase 15.7.   Upcoming in the next release GoldenGate, support will be expanded for MS SQL Server, DB2, and Teradata. Tighter Security - Oracle GoldenGate 12c is integrated with the Oracle wallet to shield usernames and passwords using strong encryption and aliases.   Customers accustomed to using the Oracle Wallet with other Oracle products will instantly be familiar with how to use this great new feature Expanded Oracle Application and Technology Support -   GoldenGate can be used along with Oracle Coherence to enable real-time changed data feeds to the Coherence cache using Toplink and the Oracle GoldenGate JMS adapter.     Plus,  Oracle Advanced Customer Services (ACS) now offers a low downtime E-Business Suite platform and database migrations using GoldenGate as the enabling technology.  Keep tuned for more blogs on the new features and the upcoming launch webcast where we will go into these new features in more detail.   In the mean time make sure to read through our white paper "Oracle GoldenGate 12c Release 1 New Features Overview"

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  • How do you clean Core Data generated models and code from a project?

    - by Hazmit
    I'm having an extremely annoying problem with Core Data in the iPhone SDK. I would say in general Core Data for the most part appears easy to use and nice to implement. I have a sqlite database that is being used as a read only reference to pull data elements out for an iPhone app. It would seem there are really mysterious issues relating to what seems to be migration of the database to the most recent versions of my schema. Why can't you just clean out your stored objects and models and let a project redo all of it when you compile next? You would think if you setup a stored object model there would be a way to just reset it and recompile. I've tried what feels like a thousand 'tips' that have been the results of hours of google searches and documentation prowling to figure out how to do this. My most recent error during compile time is below. 2010-04-07 18:23:51.891 PE[1962:207] * Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Can't merge models with two different entities named 'PElement'' All of this code has been working in the simulator and is only causing me troubles now because I made a change to the schema. I also have the database options for automatically migrating set as below. NSMutableDictionary *optionsDictionary = [NSMutableDictionary dictionary]; [optionsDictionary setObject:[NSNumber numberWithBool:YES] forKey:NSMigratePersistentStoresAutomaticallyOption]; [optionsDictionary setObject:[NSNumber numberWithBool:YES] forKey:NSInferMappingModelAutomaticallyOption];

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  • How would you implement API key in WCF Data Service?

    - by rushonerok
    Is there a way to require an API key in the URL / or some other way of passing the service a private key in order to grant access to the data? I have this right now... using System; using System.Data.Services; using System.Data.Services.Common; using System.Collections.Generic; using System.Linq; using System.ServiceModel.Web; using Numina.Framework; using System.Web; using System.Configuration; [System.ServiceModel.ServiceBehavior(IncludeExceptionDetailInFaults = true)] public class odata : DataService { public static void InitializeService(DataServiceConfiguration config) { config.SetEntitySetAccessRule("*", EntitySetRights.AllRead); //config.SetServiceOperationAccessRule("*", ServiceOperationRights.All); config.DataServiceBehavior.MaxProtocolVersion = DataServiceProtocolVersion.V2; } protected override void OnStartProcessingRequest(ProcessRequestArgs args) { HttpRequest Request = HttpContext.Current.Request; if(Request["apikey"] != ConfigurationManager.AppSettings["ApiKey"]) throw new DataServiceException("ApiKey needed"); base.OnStartProcessingRequest(args); } } ...This works but it's not perfect because you cannot get at the metadata and discover the service through the Add Service Reference explorer. I could check if $metadata is in the url but it seems like a hack. Is there a better way?

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  • How to test a class that makes HTTP request and parse the response data in Obj-C?

    - by GuidoMB
    I Have a Class that needs to make an HTTP request to a server in order to get some information. For example: - (NSUInteger)newsCount { NSHTTPURLResponse *response; NSError *error; NSURLRequest *request = ISKBuildRequestWithURL(ISKDesktopURL, ISKGet, cookie, nil, nil); NSData *data = [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:&error]; if (!data) { NSLog(@"The user's(%@) news count could not be obtained:%@", username, [error description]); return 0; } NSString *regExp = @"Usted tiene ([0-9]*) noticias? no leídas?"; NSString *stringData = [[NSString alloc] initWithData:data encoding:NSASCIIStringEncoding]; NSArray *match = [stringData captureComponentsMatchedByRegex:regExp]; [stringData release]; if ([match count] < 2) return 0; return [[match objectAtIndex:1] intValue]; } The things is that I'm unit testing (using OCUnit) the hole framework but the problem is that I need to simulate/fake what the NSURLConnection is responding in order to test different scenarios and because I can't relay on the server to test my framework. So the question is Which is the best ways to do this?

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  • Best fit curve for trend line

    - by Dave Jarvis
    Problem Constraints Size of the data set, but not the data itself, is known. Data set grows by one data point at a time. Trend line is graphed one data point at a time (using a spline/Bezier curve). Graphs The collage below shows data sets with reasonably accurate trend lines: The graphs are: Upper-left. By hour, with ~24 data points. Upper-right. By day for one year, with ~365 data points. Lower-left. By week for one year, with ~52 data points. Lower-right. By month for one year, with ~12 data points. User Inputs The user can select: the type of time series (hourly, daily, monthly, quarterly, annual); and the start and end dates for the time series. For example, the user could select a daily report for 30 days in June. Trend Weight To calculate the window size (i.e., the number of data points to average when calculating the trend line), the following expression is used: data points / trend weight Where data points is derived from user inputs and trend weight is 6.4. Even though a trend weight of 6.4 produces good fits, it is rather arbitrary, and might not be appropriate for different user inputs. Question How should trend weight be calculated given the constraints of this problem?

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  • What makes these two R data frames not identical?

    - by Matt Parker
    UPDATE: I remembered dput() about the time Sharpie mentioned it. It's probably the row names. Back in a moment with an answer. I have two small data frames, this_tx and last_tx. They are, in every way that I can tell, completely identical. this_tx == last_tx results in a frame of identical dimensions, all TRUE. this_tx %in% last_tx, two TRUEs. Inspected visually, clearly identical. But when I call identical(this_tx, last_tx) I get a FALSE. Hilariously, even identical(str(this_tx), str(last_tx)) will return a TRUE. If I set this_tx <- last_tx, I'll get a TRUE. What is going on? I don't have the deepest understanding of R's internal mechanics, but I can't find a single difference between the two data frames. If it's relevant, the two variables in the frames are both factors - same levels, same numeric coding for the levels, both just subsets of the same original data frame. Converting them to character vectors doesn't help. Background (because I wouldn't mind help on this, either): I have records of drug treatments given to patients. Each treatment record essentially specifies a person and a date. A second table has a record for each drug and dose given during a particular treatment (usually, a few drugs are given each treatment). I'm trying to identify contiguous periods during which the person was taking the same combinations of drugs at the same doses. The best plan I've come up with is to check the treatments chronologically. If the combination of drugs and doses for treatment[i] is identical to the combination at treatment[i-1], then treatment[i] is a part of the same phase as treatment[i-1]. Of course, if I can't compare drug/dose combinations, that's right out.

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  • How to organize live data integrity tests and code unit tests?

    - by karlthorwald
    I have several files with code testing code (which uses a "unittest" class). Later I found it would be nice to test database integrity also. I put this into a separate directory tree. (Things like the keys have correct format, parent and child nodes are pointing correctly and such.) I use the same unittest class for the integrity tests. Now I wonder if it makes really sense to keep this separate. To test the integrity of data I often duplicate parts of code that I use to test the code that handles the data. But it is not the same. The code tests use test databases (that get deleted after each test) and the integrity tests connect to the live data and analyze it. The integrity tests I want to call from cron and send an alarm if something happens in the live database. How would you handle that? Are there standards for such a setup? What is your experience? My tendency is to put everything in the same file, which would result in the code tests also being executed by the cron on the production environment.

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  • Checking data of all same class elements

    - by Tiffani
    I need the code to check the data-name value of all instances of .account-select. Right now it just checks the first .account-select element and not any subsequent ones. The function right now is on click of an element such as John Smith, it checks the data-name of the .account-select lis. If the data-names are the same, it does not create a new li with the John Smith data. If no data-names are equal to John Smith, then it adds an li with John Smith. This is the JS-Fiddle I made for it so you can see what I am referring to: http://jsfiddle.net/rsxavior/vDCNy/22/ Any help would be greatly appreciated. This is the Jquery Code I am using right now. $('.account').click(function () { var acc = $(this).data("name"); var sel = $('.account-select').data("name"); if (acc === sel) { } else { $('.account-hidden-li').append('<li class="account-select" data-name="'+ $(this).data("name") +'">' + $(this).data("name") + '<a class="close bcn-close" data-dismiss="alert" href="#">&times;</a></li>'); } }); And the HTML: <ul> <li><a class="account" data-name="All" href="#">All</a></li> <li><a class="account" data-name="John Smith" href="#">John Smith</a></li> </ul> <ul class="account-hidden-li"> <ul>

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  • Populate a tree from Hierarchical data using 1 LINQ statement

    - by Midhat
    Hi. I have set up this programming exercise. using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace ConsoleApplication2 { class DataObject { public int ID { get; set; } public int ParentID { get; set; } public string Data { get; set; } public DataObject(int id, int pid, string data) { this.ID = id; this.ParentID = pid; this.Data = data; } } class TreeNode { public DataObject Data {get;set;} public List<DataObject> Children { get; set; } } class Program { static void Main(string[] args) { List<DataObject> data = new List<DataObject>(); data.Add(new DataObject(1, 0, "Item 1")); data.Add(new DataObject(2, 0, "Item 2")); data.Add(new DataObject(21, 2, "Item 2.1")); data.Add(new DataObject(22, 2, "Item 2.2")); data.Add(new DataObject(221, 22, "Item 2.2.1")); data.Add(new DataObject(3, 0, "Item 3")); } } } The desired output is a List of 3 treenodes, having items 1, 2 and 3. Item 2 will have a list of 2 dataobjects as its children member and so on. I have been trying to populate this tree (or rather a forest) using just 1 SLOC using LINQ. A simple group by gives me the desired data but the challenge is to organize it in TreeNode objects. Can someone give a hint or an impossibility result for this?

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  • Is it Possible to Use Constraints on Hierarchical Data in a Self-Referential Table?

    - by pbarney
    Suppose you have the following table, intended to represent hierarchical data: +--------+-------------+ | Field | Type | +--------+-------------+ | id | int(10) | | parent | int(10) | | name | varchar(45) | +--------+-------------+ The table is self-referential in that the parent_id refers to id. So you might have the following data: +----+--------+---------------+ | id | parent | name | +----+--------+---------------+ | 1 | 0 | fruit | | 2 | 0 | vegetable | | 3 | 1 | apple | | 4 | 1 | orange | | 5 | 3 | red delicious | | 6 | 3 | granny smith | | 7 | 3 | gala | +----+--------+---------------+ Using MySQL, I am trying to impose a (self-referential) foreign key constraint upon the data to cascade on update and prevent deletion of a record if it has any "children." So I used the following: CREATE TABLE `test`.`fruit` ( `id` INT(10) UNSIGNED NOT NULL AUTO_INCREMENT, `parent` INT(10) UNSIGNED, `name` VARCHAR(45) NOT NULL, PRIMARY KEY (`id`), CONSTRAINT `fk_parent` FOREIGN KEY (`parent`) REFERENCES `fruit` (`id`) ON UPDATE CASCADE ON DELETE RESTRICT ) ENGINE = InnoDB; From what I understand, this should fit my requirements. (And parent must default to null to allow insertions, correct?) The problem is, if I change the id of a record, it will not cascade: Cannot delete or update a parent row: a foreign key constraint fails (`test`.`fruit`, CONSTRAINT `fk_parent` FOREIGN KEY (`parent`) REFERENCES `fruit` (`id`) ON UPDATE CASCADE) What am I missing? Feel free to correct me if my terminology is screwed up... I'm new to constraints.

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  • Where can I find my iPhone app's Core Data persistent store?

    - by Dr Dork
    I'm diving into iPhone development, so I apologize in advance if this is a ridiculous question, but in a new iPad app project using the Core Data framework, here's the generated code for creating the persistentStoreCoordinator... - (NSPersistentStoreCoordinator *)persistentStoreCoordinator { if (persistentStoreCoordinator != nil) { return persistentStoreCoordinator; } NSURL *storeUrl = [NSURL fileURLWithPath: [[self applicationDocumentsDirectory] stringByAppendingPathComponent: @"ApplicationName.sqlite"]]; NSError *error = nil; persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:[self managedObjectModel]]; if (![persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeUrl options:nil error:&error]) { /* Replace this implementation with code to handle the error appropriately. abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development. If it is not possible to recover from the error, display an alert panel that instructs the user to quit the application by pressing the Home button. Typical reasons for an error here include: * The persistent store is not accessible * The schema for the persistent store is incompatible with current managed object model Check the error message to determine what the actual problem was. */ NSLog(@"Unresolved error %@, %@", error, [error userInfo]); abort(); } return persistentStoreCoordinator; } My questions are... The first time I run the app, is the ApplicationName.sqllite database created automatically if it doesn't exist? If not, when is it created? When data is added to it programmatically? Once the DB does exist, where can I locate the file? I'd like to open it with a different program so I can manually manipulate the data. Thanks so much in advance for your help! I'm going to continue researching these questions right now.

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  • SQL Query to separate data into two fields

    - by Phillip
    I have data in one column that I want to separate into two columns. The data is separated by a comma if present. This field can have no data, only one set of data or two sets of data saperated by the comma. Currently I pull the data and save as a comma delimited file then use an FoxPro to load the data into a table then process the data as needed then I re-insert the data back into a different SQL table for my use. I would like to drop the FoxPro portion and have the SQL query saperate the data for me. Below is a sample of what the data looks like. Store Amount Discount 1 5.95 1 5.95 PO^-479^2 1 5.95 PO^-479^2 2 5.95 2 5.95 PO^-479^2 2 5.95 +CA8A09^-240^4,CORDRC^-239^7 3 5.95 3 5.95 +CA8A09^-240^4,CORDRC^-239^7 3 5.95 +CA8A09^-240^4,CORDRC^-239^7 In the data above I want to sum the data in the amount field to get a gross amount. Then pull out the specific discount amount which is located between the carat characters and sum it to get the total discount amount. Then add the two together and get the total net amount. The query I want to write will separate the discount field as needed, see store 2 line 3 for two discounts being applied, then pull out the value between carat characters.

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  • Is there a Java data structure that is effectively an ArrayList with double indicies and built-in in

    - by Bob Cross
    I am looking for a pre-built Java data structure with the following characteristics: It should look something like an ArrayList but should allow indexing via double-precision rather than integers. Note that this means that it's likely that you'll see indicies that don't line up with the original data points (i.e., asking for the value that corresponds to key "1.5"). As a consequence, the value returned will likely be interpolated. For example, if the key is 1.5, the value returned could be the average of the value at key 1.0 and the value at key 2.0. The keys will be sorted but the values are not ensured to be monotonically increasing. In fact, there's no assurance that the first derivative of the values will be continuous (making it a poor fit for certain types of splines). Freely available code only, please. For clarity, I know how to write such a thing. In fact, we already have an implementation of this and some related data structures in legacy code that I want to replace due to some performance and coding issues. What I'm trying to avoid is spending a lot of time rolling my own solution when there might already be such a thing in the JDK, Apache Commons or another standard library. Frankly, that's exactly the approach that got this legacy code into the situation that it's in right now.... Is there such a thing out there in a freely available library?

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  • MATLAB: What is an appropriate Data Structure for a Matrix with Random Variable Entries?

    - by user568249
    I'm currently working in an area that is related to simulation and trying to design a data structure that can include random variables within matrices. To motivate this let me say I have the following matrix: [a b; c d] I want to find a data structure that will allow for a, b, c, d to either be real numbers or random variables. As an example, let's say that a = 1, b = -1, c = 2 but let d be a normally distributed random variable with mean 0 and SD 1. The data structure that I have in mind will give no value to d. However, I also want to be able to design a function that can take in the structure, simulate an uniform(0,1), obtain a value for d using an inverse CDF and then spit out an actual matrix. I have several ideas to do this (all related to the MATLAB icdf function) but would like to know how more experienced programmers would do this. In this application, it's important that the structure is as "lean" as possible since I will be working with very very large matrices and memory will be an issue.

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  • Can't return data to parent activity

    - by user23
    I'm trying to return data (the position of the item picked from the grid) to parent activity, but my code fails. The debbuger shows how 'data' gets right the key and data in the "data.putExtra("POS_ICON", position)" at child activity, but after in onActivityResult() at parent activity the debbuger shows 'data' with no key nor data returned...it's like if data loses its content. I've followed other posts and tutorials but no way. Please help. Parent activity: public void selIcono(View v){ Intent intent = new Intent (this, SelIconoActivity.class); startActivityForResult(intent,PICK_ICON_REQUEST); } protected void onActivityResult(int requestCode, int resultCode, Intent data) { //here's the problem: no data is returned!! if (requestCode == PICK_ICON_REQUEST) { if (resultCode == RESULT_OK) { // An icon was picked. putIcon(data.getIntExtra("POS_ICON", -1)); } } } Child activity: public class SelIconoActivity extends Activity { @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_sel_icono); GridView gridview = (GridView)findViewById(R.id.gr_iconos); gridview.setAdapter(new ImageAdapter (this)); gridview.setOnItemClickListener(new OnItemClickListener() { public void onItemClick(AdapterView<?> parent, View v, int position, long id) { Intent data = new Intent(); data.putExtra("POS_ICON", position); setResult(Activity.RESULT_OK, data); finish(); } }); } }

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  • How to recover deleted files?

    - by vijay.shad
    Hi My laptop has two os. one is windows vista. and other is Ubuntu. I am currently on ubuntu system, this is my primary OS. There are 4 partitions of my hard disk Windows OS Linux(Ubuntu OS) Data Now the problem part. The data partition is NTFS. I have mounted this partition on the location /media/windrive-a under ubuntu OS. A little while back i decided to delete the mounting of the data partition and i fired command rm -r /media/windrive-a/. To give me a shock; all my data on data drive is gone. Now, I know this is not the command to remove mounted partition. But I have committed the wrong. Is there any way i can get my data back. These are very important data for me. Please suggest.

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  • What's the right way to do mutable data structures (e.g., skip lists, splay trees) in F#?

    - by dan
    What's a good way to implement mutable data structures in F#? The reason I’m asking is because I want to go back and implement the data structures I learned about in the algorithms class I took this semester (skip lists, splay trees, fusion trees, y-fast tries, van Emde Boas trees, etc.), which was a pure theory course with no coding whatsoever, and I figure I might as well try to learn F# while I’m doing it. I know that I “should” use finger trees to get splay tree functionality in a functional language, and that I should do something with laziness to get skip-list functionality, etc. , but I want to get the basics nailed down before I try playing with purely functional implementations. There are lots of examples of how to do functional data structures in F#, but there isn’t much on how to do mutable data structures, so I started by fixing up the doubly linked list here into something that allows inserts and deletes anywhere. My plan is to turn this into a skip list, and then use a similar structure (discriminated union of a record) for the tree structures I want to implement. Before I start on something more substantial, is there a better way to do mutable structures like this in F#? Should I just use records and not bother with the discriminated union? Should I use a class instead? Is this question "not even wrong"? Should I be doing the mutable structures in C#, and not dip into F# until I want to compare them to their purely functional counterparts? And, if a DU of records is what I want, could I have written the code below better or more idiomatically? It seems like there's a lot of redundancy here, but I'm not sure how to get rid of it. module DoublyLinkedList = type 'a ll = | None | Node of 'a ll_node and 'a ll_node = { mutable Prev: 'a ll; Element : 'a ; mutable Next: 'a ll; } let insert x l = match l with | None -> Node({ Prev=None; Element=x; Next=None }) | Node(node) -> match node.Prev with | None -> let new_node = { Prev=None; Element=x; Next=Node(node)} node.Prev <- Node(new_node) Node(new_node) | Node(prev_node) -> let new_node = { Prev=node.Prev; Element=x; Next=Node(node)} node.Prev <- Node(new_node) prev_node.Next <- Node(new_node) Node(prev_node) let rec nth n l = match n, l with | _,None -> None | _,Node(node) when n > 0 -> nth (n-1) node.Next | _,Node(node) when n < 0 -> nth (n+1) node.Prev | _,Node(node) -> Node(node) //hopefully only when n = 0 :-) let rec printLinkedList head = match head with | None -> () | Node(x) -> let prev = match x.Prev with | None -> "-" | Node(y) -> y.Element.ToString() let cur = x.Element.ToString() let next = match x.Next with | None -> "-" | Node(y) -> y.Element.ToString() printfn "%s, <- %s -> %s" prev cur next printLinkedList x.Next

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  • Updating D3 column chart with different values and different data sizes

    - by mbeasley
    Background I am attempting to create a reusable chart object with D3.js. I have setup a chart() function that will produce a column chart. On a click event on any of the columns, the chart will update with a new random data array that will contain a random number of data points (i.e. the original chart could have 8 columns, but upon update, could have 20 columns or 4 columns). Problem Say I have 8 data points (and thus 8 columns) in my original dataset. When I update the chart with random data, the columns appropriately adjust their height to the new values - but new bars aren't added. Additionally, while the width of the columns appropriately adjust to accommodate the width of the container and the new number of data points, if that number of data points is less than the original set, then some of those columns from the original dataset will linger until the number of data points is greater than or equal than the original. My end goal is to have new data dynamically added or old data outside of the range of the new data count dynamically removed. I've created a jsfiddle of the behavior. You may have to click the columns a couple of times to see the behavior I'm describing. Additionally, I've pasted my code below. Thanks in advance! function chart(config) { // set default options var defaultOptions = { selector: '#chartZone', class: 'chart', id: null, data: [1,2,6,4, 2, 6, 7, 2], type: 'column', width: 200, height: 200, callback: null, interpolate: 'monotone' }; // fill in unspecified settings in the config with the defaults var settings = $.extend(defaultOptions, config); function my() { // generate chart with this function var w = settings.width, h = settings.height, barPadding = 3, scale = 10, max = d3.max(settings.data); var svg = d3.select(settings.selector) // create the main svg container .append("svg") .attr("width",w) .attr("height",h); var y = d3.scale.linear().range([h, 0]), yAxis = d3.svg.axis().scale(y).ticks(5).orient("left"), x = d3.scale.linear().range([w, 0]); y.domain([0, max]).nice(); x.domain([0, settings.data.length - 1]).nice(); var rect = svg.selectAll("rect") .data(settings.data) .enter() .append("rect") .attr("x", function(d,i) { return i * (w / settings.data.length); }) .attr("y", function(d) { return h - h * (d / max); }) .attr("width", w / settings.data.length - barPadding) .attr("height", function(d) { return h * (d / max); }) .attr("fill", "rgb(90,90,90)"); svg.append("svg:g") .attr("class", "y axis") .attr("transform", "translate(-4,0)") .call(yAxis); svg.on("click", function() { var newData = [], maxCap = Math.round(Math.random() * 100); for (var i = 0; i < Math.round(Math.random()*100); i++) { var newNumber = Math.random() * maxCap; newData.push(Math.round(newNumber)); } newMax = d3.max(newData); y.domain([0, newMax]).nice(); var t = svg.transition().duration(750); t.select(".y.axis").call(yAxis); rect.data(newData) .transition().duration(750) .attr("height", function(d) { return h * (d / newMax); }) .attr("x", function(d,i) { return i * (w / newData.length); }) .attr("width", w / newData.length - barPadding) .attr("y", function(d) { return h - h * (d / newMax); }); }); } my(); return my; } var myChart = chart();

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  • What is a good java data structure for storing nested items (like cities in states)?

    - by anotherAlan
    I'm just getting started in Java and am looking for advice on a good way to store nested sets of data. For example, I'm interested in storing city population data that can be accessed by looking up the city in a given state. (Note: eventually, other data will be stored with each city as well, this is just the first attempt at getting started.) The current approach I'm using is to have a StateList Object which contains a HashMap that stores State Objects via a string key (i.e. HashMap<String, State>). Each State Object contains its own HashMap of City Objects keyed off the city name (i.e. HashMap<String, City>). A cut down version of what I've come up with looks like this: // TestPopulation.java public class TestPopulation { public static void main(String [] args) { // build the stateList Object StateList sl = new StateList(); // get a test state State stateAl = sl.getState("AL"); // make sure it's there. if(stateAl != null) { // add a city stateAl.addCity("Abbeville"); // now grab the city City cityAbbevilleAl = stateAl.getCity("Abbeville"); cityAbbevilleAl.setPopulation(2987); System.out.print("The city has a pop of: "); System.out.println(Integer.toString(cityAbbevilleAl.getPopulation())); } // otherwise, print an error else { System.out.println("That was an invalid state"); } } } // StateList.java import java.util.*; public class StateList { // define hash map to hold the states private HashMap<String, State> theStates = new HashMap<String, State>(); // setup constructor that loads the states public StateList() { String[] stateCodes = {"AL","AK","AZ","AR","CA","CO"}; // etc... for (String s : stateCodes) { State newState = new State(s); theStates.put(s, newState); } } // define method for getting a state public State getState(String stateCode) { if(theStates.containsKey(stateCode)) { return theStates.get(stateCode); } else { return null; } } } // State.java import java.util.*; public class State { // Setup the state code String stateCode; // HashMap for cities HashMap<String, City> cities = new HashMap<String, City>(); // define the constructor public State(String newStateCode) { System.out.println("Creating State: " + newStateCode); stateCode = newStateCode; } // define the method for adding a city public void addCity(String newCityName) { City newCityObj = new City(newCityName); cities.put(newCityName, newCityObj); } // define the method for getting a city public City getCity(String cityName) { if(cities.containsKey(cityName)) { return cities.get(cityName); } else { return null; } } } // City.java public class City { // Define the instance vars String cityName; int cityPop; // setup the constructor public City(String newCityName) { cityName = newCityName; System.out.println("Created City: " + newCityName); } public void setPopulation(int newPop) { cityPop = newPop; } public int getPopulation() { return cityPop; } } This is working for me, but I'm wondering if there are gotchas that I haven't run into, or if there are alternate/better ways to do the same thing. (P.S. I know that I need to add some more error checking in, but right now, I'm focused on trying to figure out a good data structure.) (NOTE: Edited to change setPop() and getPop() to setPopulation() and getPopulation() respectively to avoid confucsion)

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  • Week in Geek: US Govt E-card Scam Siphons Confidential Data Edition

    - by Asian Angel
    This week we learned how to “back up photos to Flickr, automate repetitive tasks, & normalize MP3 volume”, enable “stereo mix” in Windows 7 to record audio, create custom papercraft toys, read up on three alternatives to Apple’s flaky iOS alarm clock, decorated our desktops & app docks with Google icon packs, and more. Photo by alexschlegel. Random Geek Links It has been a busy week on the security & malware fronts and we have a roundup of the latest news to help keep you updated. Photo by TopTechWriter.US. US govt e-card scam hits confidential data A fake U.S. government Christmas e-card has managed to siphon off gigabytes of sensitive data from a number of law enforcement and military staff who work on cybersecurity matters, many of whom are involved in computer crime investigations. Security tool uncovers multiple bugs in every browser Michal Zalewski reports that he discovered the vulnerability in Internet Explorer a while ago using his cross_fuzz fuzzing tool and reported it to Microsoft in July 2010. Zalewski also used cross_fuzz to discover bugs in other browsers, which he also reported to the relevant organisations. Microsoft to fix Windows holes, but not ones in IE Microsoft said that it will release two security bulletins next week fixing three holes in Windows, but it is still investigating or working on fixing holes in Internet Explorer that have been reportedly exploited in attacks. Microsoft warns of Windows flaw affecting image rendering Microsoft has warned of a Windows vulnerability that could allow an attacker to take control of a computer if the user is logged on with administrative rights. Windows 7 Not Affected by Critical 0-Day in the Windows Graphics Rendering Engine While confirming that details on a Critical zero-day vulnerability have made their way into the wild, Microsoft noted that customers running the latest iteration of Windows client and server platforms are not exposed to any risks. Microsoft warns of Office-related malware Microsoft’s Malware Protection Center issued a warning this week that it has spotted malicious code on the Internet that can take advantage of a flaw in Word and infect computers after a user does nothing more than read an e-mail. *Refers to a flaw that was addressed in the November security patch releases. Make sure you have all of the latest security updates installed. Unpatched hole in ImgBurn disk burning application According to security specialist Secunia, a highly critical vulnerability in ImgBurn, a lightweight disk burning application, can be used to remotely compromise a user’s system. Hole in VLC Media Player Virtual Security Research (VSR) has identified a vulnerability in VLC Media Player. In versions up to and including 1.1.5 of the VLC Media Player. Flash Player sandbox can be bypassed Flash applications run locally can read local files and send them to an online server – something which the sandbox is supposed to prevent. Chinese auction site touts hacked iTunes accounts Tens of thousands of reportedly hacked iTunes accounts have been found on Chinese auction site Taobao, but the company claims it is unable to take action unless there are direct complaints. What happened in the recent Hotmail outage Mike Schackwitz explains the cause of the recent Hotmail outage. DOJ sends order to Twitter for Wikileaks-related account info The U.S. Justice Department has obtained a court order directing Twitter to turn over information about the accounts of activists with ties to Wikileaks, including an Icelandic politician, a legendary Dutch hacker, and a U.S. computer programmer. Google gets court to block Microsoft Interior Department e-mail win The U.S. Federal Claims Court has temporarily blocked Microsoft from proceeding with the $49.3 million, five-year DOI contract that it won this past November. Google Apps customers get email lockdown Companies and organisations using Google Apps are now able to restrict the email access of selected users. LibreOffice Is the Default Office Suite for Ubuntu 11.04 Matthias Klose has announced some details regarding the replacement of the old OpenOffice.org 3.2.1 packages with the new LibreOffice 3.3 ones, starting with the upcoming Ubuntu 11.04 (Natty Narwhal) Alpha 2 release. Sysadmin Geek Tips Photo by Filomena Scalise. How to Setup Software RAID for a Simple File Server on Ubuntu Do you need a file server that is cheap and easy to setup, “rock solid” reliable, and has Email Alerting? This tutorial shows you how to use Ubuntu, software RAID, and SaMBa to accomplish just that. How to Control the Order of Startup Programs in Windows While you can specify the applications you want to launch when Windows starts, the ability to control the order in which they start is not available. However, there are a couple of ways you can easily overcome this limitation and control the startup order of applications. Random TinyHacker Links Using Opera Unite to Send Large Files A tutorial on using Opera Unite to easily send huge files from your computer. WorkFlowy is a Useful To-do List Tool A cool to-do list tool that lets you integrate multiple tasks in one single list easily. Playing Flash Videos on iOS Devices Yes, you can play flash videos on jailbroken iPhones. Here’s a tutorial. Clear Safari History and Cookies On iPhone A tutorial on clearing your browser history on iPhone and other iOS devices. Monitor Your Internet Usage Here’s a cool, cross-platform tool to monitor your internet bandwidth. Super User Questions See what the community had to say on these popular questions from Super User this week. Why is my upload speed much less than my download speed? Where should I find drivers for my laptop if it didn’t come with a driver disk? OEM Office 2010 without media – how to reinstall? Is there a point to using theft tracking software like Prey on my laptop, if you have login security? Moving an “all-in-one” PC when turned on/off How-To Geek Weekly Article Recap Get caught up on your HTG reading with our hottest articles from this past week. How to Combine Rescue Disks to Create the Ultimate Windows Repair Disk How To Boot 10 Different Live CDs From 1 USB Flash Drive What is Camera Raw, and Why Would a Professional Prefer it to JPG? Did You Know Facebook Has Built-In Shortcut Keys? The How-To Geek Guide to Audio Editing: The Basics One Year Ago on How-To Geek Enjoy looking through our latest gathering of retro article goodness. Learning Windows 7: Create a Homegroup & Join a New Computer To It How To Disconnect a Machine from a Homegroup Use Remote Desktop To Access Other Computers On a Small Office or Home Network How To Share Files and Printers Between Windows 7 and Vista Allow Users To Run Only Specified Programs in Windows 7 The Geek Note That is all we have for you this week and we hope your first week back at work or school has gone very well now that the holidays are over. Know a great tip? Send it in to us at [email protected]. Photo by Pamela Machado. Latest Features How-To Geek ETC HTG Projects: How to Create Your Own Custom Papercraft Toy How to Combine Rescue Disks to Create the Ultimate Windows Repair Disk What is Camera Raw, and Why Would a Professional Prefer it to JPG? The How-To Geek Guide to Audio Editing: The Basics How To Boot 10 Different Live CDs From 1 USB Flash Drive The 20 Best How-To Geek Linux Articles of 2010 Arctic Theme for Windows 7 Gives Your Desktop an Icy Touch Install LibreOffice via PPA and Receive Auto-Updates in Ubuntu Creative Portraits Peek Inside the Guts of Modern Electronics Scenic Winter Lane Wallpaper to Create a Relaxing Mood Access Your Web Apps Directly Using the Context Menu in Chrome The Deep – Awesome Use of Metal Objects as Deep Sea Creatures [Video]

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  • Using Oracle Data in the Business Rules Engine

    - by Christopher House
    Yesterday I started working on some new functionality that I had planned to implement using the Business Rules Engine.  As I got further into it, I realized that some of my rules were going to need to reference some data that resides in an Oracle database.  I knew the Business Rules Composer supports using DataConnections and TypedDataTables, but I’d never used this functionality myself, so I wasn’t so sure how it would work with Oracle.  As it turns out, it’s very do-able, there’s just little hoop you need to jump through. I fired up BRC and my suspicions were quickly confirmed.  BRC only recognizes SQL Server databases when it comes to editing rules.  Not letting that deter me, I decided to see if I could “trick” BRE into using Oracle data. On my local SQL server, I created a new database and in that database, created a table that matched the schema of the table I wanted to use in the Oracle database.  I then set about creating my rules, referencing the new SQL Server database everywhere I wanted to use Oracle data.  Finally, I created a new class library and added a class that implements Microsoft.RuleEngine.IFactRetriever.  In that class, I added the necessary code to get a DataSet from the Oracle server, wrap it in a TypedDataTable and assert it into the rule engine.  It’s worth pointing out that in my IFactRetriever class, I made sure to set my DataSet name to the name of the database I’d referenced in the BRC and the DataTable’s name to the name of the table that I’d referenced in the BRC. After gac’ing the new class library and deploying my policy, I tested and everything worked as expected.

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  • How does Comparison Sites work?

    - by Vijay
    Need your thinking on how does these Comparision Sites actually work. Sites like Junglee.com policybazaar.com and there are many like these which provides comaprision of products , fares etc. grabbed from different websites. I had read a little about it and what i found is-: These sites uses Feeds of the sites data. These sites uses APIs of the sites which are actually provided by those sites. And for some sites which do not have any of these two posibility then the Comparision sites uses web-crawler to crawl their data. This is what i have found out. If you think there is more things to it please do give your own views. But i want to know these for my learning purpose and a little for curiosity- how does they actually matches the crawled data , feeds, and other so that there is no duplicacy. What is the process or algorithms for it. And where should i go to learn these concepts. References for books , articles or anything else.

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