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  • remove repeated vaules _stack&array

    - by Fatimah
    I want to write a program to implement an array-based stack, which accept integer numbers entered by the user.the program will then identify any occurrences of a given value from user and remove the repeated values from the stack,(using Java programming language). I just need your help of writing (removing values method) e.g. input:6 2 3 4 3 8 output:6 2 4 8

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  • C# print 2D-array in order. Please help!

    - by user339067
    Hello, I got a 2-dimentional array containing boolean values written in C#. The cols and rows of the array are to be determined by the user upon creation of the array. I then want to print out the array and it´s containing values onto the console in order. For example like this, how is this done in C#? ROWS - COLS - VALUE 1 - A - True 1 - B - True 1 - C - True 1 - D - True 2 - A - True 2 - B - False 2 - C - False 2 - D - True

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  • Regular expression to process key value pairs

    - by user677680
    I am attempting to write a regular expression to process a string of key value(s) pairs formatted like so KEY/VALUE KEY/VALUE VALUE KEY/VALUE A key can have multiple values separated by a space. I want to match a keys values together, so the result on the above string would be VALUE VALUE VALUE VALUE I currently have the following as my regex [A-Z0-9]+/([A-Z0-9 ]+)(?:(?!^[A-Z0-9]+/)) but this returns VALUE KEY as the first result.

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  • Changing the Order in a .NET Generic Dictionary

    - by pm_2
    I have a class that inherits from a generic dictionary as follows: Class myClass : System.Collections.Generic.Dictionary<int, Object> I have added a list of values to this in a particular order, but I now wish to change that order. Is there any way (without removing and re-adding) that I could effectively re-index the values; so change the object at index 1 to now be at index 10 for example? For example, this doesn't work: myClass[1].Index = 10;

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  • Python: Sort a dictionary by value

    - by the empirical programmer
    I have a dictionary of values read from 2 fields in a database: a string field and a numeric field. The string field is unique so that is the key of the dictionary. I can sort on the keys, but how can I sort based on the values? Note: I have read this post 72899 and probably could change my code to have a list of dictionaries but since I do not really need a list of dictionaries I wanted to know if there a simpler solution.

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  • Create trigger for auto incerment id and default unix datetime

    - by user1804985
    Any one help me to create a trigger for auto increment fld_id and Unix datetime. My table field is fld_id(int),fld_date(number),fld_value(varchar2). My insert query is insert into table (fld_value)values('xxx'); insert into table (fld_value)values('yyy'); I need the table record like this fld_id fld_date fld_value 1 1354357476 xxx 2 1354357478 yyy Please help me to create this.I can't able to do this..

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  • Difference between INSERT INTO and INSERT ALL INTO

    - by emily soto
    While I was inserting some records in table i found that.. INSERT INTO T_CANDYBAR_DATA SELECT CONSUMER_ID,CANDYBAR_NAME,SURVEY_YEAR,GENDER,1 AS STAT_TYPE,OVERALL_RATING FROM CANDYBAR_CONSUMPTION_DATA UNION SELECT CONSUMER_ID,CANDYBAR_NAME,SURVEY_YEAR,GENDER,2 AS STAT_TYPE,NUMBER_BARS_CONSUMED FROM CANDYBAR_CONSUMPTION_DATA; 79 rows inserted. INSERT ALL INTO t_candybar_data VALUES (consumer_id,candybar_name,survey_year,gender,1,overall_rating) INTO t_candybar_data VALUES (consumer_id,candybar_name,survey_year,gender,2,number_bars_consumed) SELECT * FROM candybar_consumption_data 86 rows inserted. I have read somewhere that INSERT ALL INTO automatically unions then why those difference is showing.

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  • JavaScript: Is there any "python's Generator" equivalent in JavaScript?

    - by JackSMTV
    Is there any "python's Generator" equivalent in JavaScript? PS: Python's Generator is very memory efficient when we need to do one time iterate through a big array, hash... "Generators are iterables, but you can only read them once. It's because they do not store all the values in memory, they generate the values on the fly" (Python's Generator explained in this thread: The Python yield keyword explained )

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  • Problem with PHP & SQL Query

    - by Shahd
    Hi .... i have a problem in php code (inserting values in database) i use PHPMyAdmin my DATABASE has 3 tables: 1) Member with this fields: MemberID, MemberName 2) Room with this fields: RoomID, RoomName 3) Join with this fields: MemberID, RoomID the idea is to join the member in the room. My query was mysql_query("INSERT INTO join (RoomID, MemberID) VALUES ('121', '131')"); but unfortunately it is not work

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  • Is there something in MySQL like IN but which uses AND instead of OR?

    - by Skatox
    I need a SQL statement to retrieve records where it key (or any column) is in a associate table, for example: documentId termId 4 1 4 2 3 3 5 1 This: SELECT documentId FROM table WHERE termId IN (1,2,3) ...will retrieve any documentid value where the termid value is 1 or 2 or 3. Is there something like this but return documentid values where the termid values are 1 and 2 and 3? Like an IN but with AND.

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  • options[Text] is null or not an object in javascript

    - by user9167
    I am getting options[text] is null or not an object error. What i am trying to do here is i am checking what all multi select lookup column values are selected , comparing them with the value in an array and then removing them var responsibleselected = returntags("select","Responsibility selected values"); for(var i=0;i<responsibleselected.options.length;i++) { if(responsibleselected.options[i].selected == true) { for(var j=0;j< ResponsibleArray.length;j++) { if(responsibleselected.options[i].text == ResponsibleArray[j])//throws error here { GipRemoveSelectedItems(ctl00_m_g_6ad915a8_68ea_4c76_b67a_ad1215320288_ff391_ctl00_ctl00_MultiLookupPicker_m); } } } }

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  • Using jQuery to Insert a New Database Record

    - by Stephen Walther
    The goal of this blog entry is to explore the easiest way of inserting a new record into a database using jQuery and .NET. I’m going to explore two approaches: using Generic Handlers and using a WCF service (In a future blog entry I’ll take a look at OData and WCF Data Services). Create the ASP.NET Project I’ll start by creating a new empty ASP.NET application with Visual Studio 2010. Select the menu option File, New Project and select the ASP.NET Empty Web Application project template. Setup the Database and Data Model I’ll use my standard MoviesDB.mdf movies database. This database contains one table named Movies that looks like this: I’ll use the ADO.NET Entity Framework to represent my database data: Select the menu option Project, Add New Item and select the ADO.NET Entity Data Model project item. Name the data model MoviesDB.edmx and click the Add button. In the Choose Model Contents step, select Generate from database and click the Next button. In the Choose Your Data Connection step, leave all of the defaults and click the Next button. In the Choose Your Data Objects step, select the Movies table and click the Finish button. Unfortunately, Visual Studio 2010 cannot spell movie correctly :) You need to click on Movy and change the name of the class to Movie. In the Properties window, change the Entity Set Name to Movies. Using a Generic Handler In this section, we’ll use jQuery with an ASP.NET generic handler to insert a new record into the database. A generic handler is similar to an ASP.NET page, but it does not have any of the overhead. It consists of one method named ProcessRequest(). Select the menu option Project, Add New Item and select the Generic Handler project item. Name your new generic handler InsertMovie.ashx and click the Add button. Modify your handler so it looks like Listing 1: Listing 1 – InsertMovie.ashx using System.Web; namespace WebApplication1 { /// <summary> /// Inserts a new movie into the database /// </summary> public class InsertMovie : IHttpHandler { private MoviesDBEntities _dataContext = new MoviesDBEntities(); public void ProcessRequest(HttpContext context) { context.Response.ContentType = "text/plain"; // Extract form fields var title = context.Request["title"]; var director = context.Request["director"]; // Create movie to insert var movieToInsert = new Movie { Title = title, Director = director }; // Save new movie to DB _dataContext.AddToMovies(movieToInsert); _dataContext.SaveChanges(); // Return success context.Response.Write("success"); } public bool IsReusable { get { return true; } } } } In Listing 1, the ProcessRequest() method is used to retrieve a title and director from form parameters. Next, a new Movie is created with the form values. Finally, the new movie is saved to the database and the string “success” is returned. Using jQuery with the Generic Handler We can call the InsertMovie.ashx generic handler from jQuery by using the standard jQuery post() method. The following HTML page illustrates how you can retrieve form field values and post the values to the generic handler: Listing 2 – Default.htm <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>Add Movie</title> <script src="http://ajax.microsoft.com/ajax/jquery/jquery-1.4.2.js" type="text/javascript"></script> </head> <body> <form> <label>Title:</label> <input name="title" /> <br /> <label>Director:</label> <input name="director" /> </form> <button id="btnAdd">Add Movie</button> <script type="text/javascript"> $("#btnAdd").click(function () { $.post("InsertMovie.ashx", $("form").serialize(), insertCallback); }); function insertCallback(result) { if (result == "success") { alert("Movie added!"); } else { alert("Could not add movie!"); } } </script> </body> </html>     When you open the page in Listing 2 in a web browser, you get a simple HTML form: Notice that the page in Listing 2 includes the jQuery library. The jQuery library is included with the following SCRIPT tag: <script src="http://ajax.microsoft.com/ajax/jquery/jquery-1.4.2.js" type="text/javascript"></script> The jQuery library is included on the Microsoft Ajax CDN so you can always easily include the jQuery library in your applications. You can learn more about the CDN at this website: http://www.asp.net/ajaxLibrary/cdn.ashx When you click the Add Movie button, the jQuery post() method is called to post the form data to the InsertMovie.ashx generic handler. Notice that the form values are serialized into a URL encoded string by calling the jQuery serialize() method. The serialize() method uses the name attribute of form fields and not the id attribute. Notes on this Approach This is a very low-level approach to interacting with .NET through jQuery – but it is simple and it works! And, you don’t need to use any JavaScript libraries in addition to the jQuery library to use this approach. The signature for the jQuery post() callback method looks like this: callback(data, textStatus, XmlHttpRequest) The second parameter, textStatus, returns the HTTP status code from the server. I tried returning different status codes from the generic handler with an eye towards implementing server validation by returning a status code such as 400 Bad Request when validation fails (see http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html ). I finally figured out that the callback is not invoked when the textStatus has any value other than “success”. Using a WCF Service As an alternative to posting to a generic handler, you can create a WCF service. You create a new WCF service by selecting the menu option Project, Add New Item and selecting the Ajax-enabled WCF Service project item. Name your WCF service InsertMovie.svc and click the Add button. Modify the WCF service so that it looks like Listing 3: Listing 3 – InsertMovie.svc using System.ServiceModel; using System.ServiceModel.Activation; namespace WebApplication1 { [ServiceBehavior(IncludeExceptionDetailInFaults=true)] [ServiceContract(Namespace = "")] [AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)] public class MovieService { private MoviesDBEntities _dataContext = new MoviesDBEntities(); [OperationContract] public bool Insert(string title, string director) { // Create movie to insert var movieToInsert = new Movie { Title = title, Director = director }; // Save new movie to DB _dataContext.AddToMovies(movieToInsert); _dataContext.SaveChanges(); // Return movie (with primary key) return true; } } }   The WCF service in Listing 3 uses the Entity Framework to insert a record into the Movies database table. The service always returns the value true. Notice that the service in Listing 3 includes the following attribute: [ServiceBehavior(IncludeExceptionDetailInFaults=true)] You need to include this attribute if you want to get detailed error information back to the client. When you are building an application, you should always include this attribute. When you are ready to release your application, you should remove this attribute for security reasons. Using jQuery with the WCF Service Calling a WCF service from jQuery requires a little more work than calling a generic handler from jQuery. Here are some good blog posts on some of the issues with using jQuery with WCF: http://encosia.com/2008/06/05/3-mistakes-to-avoid-when-using-jquery-with-aspnet-ajax/ http://encosia.com/2008/03/27/using-jquery-to-consume-aspnet-json-web-services/ http://weblogs.asp.net/scottgu/archive/2007/04/04/json-hijacking-and-how-asp-net-ajax-1-0-mitigates-these-attacks.aspx http://www.west-wind.com/Weblog/posts/896411.aspx http://www.west-wind.com/weblog/posts/324917.aspx http://professionalaspnet.com/archive/tags/WCF/default.aspx The primary requirement when calling WCF from jQuery is that the request use JSON: The request must include a content-type:application/json header. Any parameters included with the request must be JSON encoded. Unfortunately, jQuery does not include a method for serializing JSON (Although, oddly, jQuery does include a parseJSON() method for deserializing JSON). Therefore, we need to use an additional library to handle the JSON serialization. The page in Listing 4 illustrates how you can call a WCF service from jQuery. Listing 4 – Default2.aspx <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>Add Movie</title> <script src="http://ajax.microsoft.com/ajax/jquery/jquery-1.4.2.js" type="text/javascript"></script> <script src="Scripts/json2.js" type="text/javascript"></script> </head> <body> <form> <label>Title:</label> <input id="title" /> <br /> <label>Director:</label> <input id="director" /> </form> <button id="btnAdd">Add Movie</button> <script type="text/javascript"> $("#btnAdd").click(function () { // Convert the form into an object var data = { title: $("#title").val(), director: $("#director").val() }; // JSONify the data data = JSON.stringify(data); // Post it $.ajax({ type: "POST", contentType: "application/json; charset=utf-8", url: "MovieService.svc/Insert", data: data, dataType: "json", success: insertCallback }); }); function insertCallback(result) { // unwrap result result = result["d"]; if (result === true) { alert("Movie added!"); } else { alert("Could not add movie!"); } } </script> </body> </html> There are several things to notice about Listing 4. First, notice that the page includes both the jQuery library and Douglas Crockford’s JSON2 library: <script src="Scripts/json2.js" type="text/javascript"></script> You need to include the JSON2 library to serialize the form values into JSON. You can download the JSON2 library from the following location: http://www.json.org/js.html When you click the button to submit the form, the form data is converted into a JavaScript object: // Convert the form into an object var data = { title: $("#title").val(), director: $("#director").val() }; Next, the data is serialized into JSON using the JSON2 library: // JSONify the data var data = JSON.stringify(data); Finally, the form data is posted to the WCF service by calling the jQuery ajax() method: // Post it $.ajax({   type: "POST",   contentType: "application/json; charset=utf-8",   url: "MovieService.svc/Insert",   data: data,   dataType: "json",   success: insertCallback }); You can’t use the standard jQuery post() method because you must set the content-type of the request to be application/json. Otherwise, the WCF service will reject the request for security reasons. For details, see the Scott Guthrie blog post: http://weblogs.asp.net/scottgu/archive/2007/04/04/json-hijacking-and-how-asp-net-ajax-1-0-mitigates-these-attacks.aspx The insertCallback() method is called when the WCF service returns a response. This method looks like this: function insertCallback(result) {   // unwrap result   result = result["d"];   if (result === true) {       alert("Movie added!");   } else {     alert("Could not add movie!");   } } When we called the jQuery ajax() method, we set the dataType to JSON. That causes the jQuery ajax() method to deserialize the response from the WCF service from JSON into a JavaScript object automatically. The following value is passed to the insertCallback method: {"d":true} For security reasons, a WCF service always returns a response with a “d” wrapper. The following line of code removes the “d” wrapper: // unwrap result result = result["d"]; To learn more about the “d” wrapper, I recommend that you read the following blog posts: http://encosia.com/2009/02/10/a-breaking-change-between-versions-of-aspnet-ajax/ http://encosia.com/2009/06/29/never-worry-about-asp-net-ajaxs-d-again/ Summary In this blog entry, I explored two methods of inserting a database record using jQuery and .NET. First, we created a generic handler and called the handler from jQuery. This is a very low-level approach. However, it is a simple approach that works. Next, we looked at how you can call a WCF service using jQuery. This approach required a little more work because you need to serialize objects into JSON. We used the JSON2 library to perform the serialization. In the next blog post, I want to explore how you can use jQuery with OData and WCF Data Services.

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  • Inheritance Mapping Strategies with Entity Framework Code First CTP5: Part 3 – Table per Concrete Type (TPC) and Choosing Strategy Guidelines

    - by mortezam
    This is the third (and last) post in a series that explains different approaches to map an inheritance hierarchy with EF Code First. I've described these strategies in previous posts: Part 1 – Table per Hierarchy (TPH) Part 2 – Table per Type (TPT)In today’s blog post I am going to discuss Table per Concrete Type (TPC) which completes the inheritance mapping strategies supported by EF Code First. At the end of this post I will provide some guidelines to choose an inheritance strategy mainly based on what we've learned in this series. TPC and Entity Framework in the Past Table per Concrete type is somehow the simplest approach suggested, yet using TPC with EF is one of those concepts that has not been covered very well so far and I've seen in some resources that it was even discouraged. The reason for that is just because Entity Data Model Designer in VS2010 doesn't support TPC (even though the EF runtime does). That basically means if you are following EF's Database-First or Model-First approaches then configuring TPC requires manually writing XML in the EDMX file which is not considered to be a fun practice. Well, no more. You'll see that with Code First, creating TPC is perfectly possible with fluent API just like other strategies and you don't need to avoid TPC due to the lack of designer support as you would probably do in other EF approaches. Table per Concrete Type (TPC)In Table per Concrete type (aka Table per Concrete class) we use exactly one table for each (nonabstract) class. All properties of a class, including inherited properties, can be mapped to columns of this table, as shown in the following figure: As you can see, the SQL schema is not aware of the inheritance; effectively, we’ve mapped two unrelated tables to a more expressive class structure. If the base class was concrete, then an additional table would be needed to hold instances of that class. I have to emphasize that there is no relationship between the database tables, except for the fact that they share some similar columns. TPC Implementation in Code First Just like the TPT implementation, we need to specify a separate table for each of the subclasses. We also need to tell Code First that we want all of the inherited properties to be mapped as part of this table. In CTP5, there is a new helper method on EntityMappingConfiguration class called MapInheritedProperties that exactly does this for us. Here is the complete object model as well as the fluent API to create a TPC mapping: public abstract class BillingDetail {     public int BillingDetailId { get; set; }     public string Owner { get; set; }     public string Number { get; set; } }          public class BankAccount : BillingDetail {     public string BankName { get; set; }     public string Swift { get; set; } }          public class CreditCard : BillingDetail {     public int CardType { get; set; }     public string ExpiryMonth { get; set; }     public string ExpiryYear { get; set; } }      public class InheritanceMappingContext : DbContext {     public DbSet<BillingDetail> BillingDetails { get; set; }              protected override void OnModelCreating(ModelBuilder modelBuilder)     {         modelBuilder.Entity<BankAccount>().Map(m =>         {             m.MapInheritedProperties();             m.ToTable("BankAccounts");         });         modelBuilder.Entity<CreditCard>().Map(m =>         {             m.MapInheritedProperties();             m.ToTable("CreditCards");         });                 } } The Importance of EntityMappingConfiguration ClassAs a side note, it worth mentioning that EntityMappingConfiguration class turns out to be a key type for inheritance mapping in Code First. Here is an snapshot of this class: namespace System.Data.Entity.ModelConfiguration.Configuration.Mapping {     public class EntityMappingConfiguration<TEntityType> where TEntityType : class     {         public ValueConditionConfiguration Requires(string discriminator);         public void ToTable(string tableName);         public void MapInheritedProperties();     } } As you have seen so far, we used its Requires method to customize TPH. We also used its ToTable method to create a TPT and now we are using its MapInheritedProperties along with ToTable method to create our TPC mapping. TPC Configuration is Not Done Yet!We are not quite done with our TPC configuration and there is more into this story even though the fluent API we saw perfectly created a TPC mapping for us in the database. To see why, let's start working with our object model. For example, the following code creates two new objects of BankAccount and CreditCard types and tries to add them to the database: using (var context = new InheritanceMappingContext()) {     BankAccount bankAccount = new BankAccount();     CreditCard creditCard = new CreditCard() { CardType = 1 };                      context.BillingDetails.Add(bankAccount);     context.BillingDetails.Add(creditCard);     context.SaveChanges(); } Running this code throws an InvalidOperationException with this message: The changes to the database were committed successfully, but an error occurred while updating the object context. The ObjectContext might be in an inconsistent state. Inner exception message: AcceptChanges cannot continue because the object's key values conflict with another object in the ObjectStateManager. Make sure that the key values are unique before calling AcceptChanges. The reason we got this exception is because DbContext.SaveChanges() internally invokes SaveChanges method of its internal ObjectContext. ObjectContext's SaveChanges method on its turn by default calls AcceptAllChanges after it has performed the database modifications. AcceptAllChanges method merely iterates over all entries in ObjectStateManager and invokes AcceptChanges on each of them. Since the entities are in Added state, AcceptChanges method replaces their temporary EntityKey with a regular EntityKey based on the primary key values (i.e. BillingDetailId) that come back from the database and that's where the problem occurs since both the entities have been assigned the same value for their primary key by the database (i.e. on both BillingDetailId = 1) and the problem is that ObjectStateManager cannot track objects of the same type (i.e. BillingDetail) with the same EntityKey value hence it throws. If you take a closer look at the TPC's SQL schema above, you'll see why the database generated the same values for the primary keys: the BillingDetailId column in both BankAccounts and CreditCards table has been marked as identity. How to Solve The Identity Problem in TPC As you saw, using SQL Server’s int identity columns doesn't work very well together with TPC since there will be duplicate entity keys when inserting in subclasses tables with all having the same identity seed. Therefore, to solve this, either a spread seed (where each table has its own initial seed value) will be needed, or a mechanism other than SQL Server’s int identity should be used. Some other RDBMSes have other mechanisms allowing a sequence (identity) to be shared by multiple tables, and something similar can be achieved with GUID keys in SQL Server. While using GUID keys, or int identity keys with different starting seeds will solve the problem but yet another solution would be to completely switch off identity on the primary key property. As a result, we need to take the responsibility of providing unique keys when inserting records to the database. We will go with this solution since it works regardless of which database engine is used. Switching Off Identity in Code First We can switch off identity simply by placing DatabaseGenerated attribute on the primary key property and pass DatabaseGenerationOption.None to its constructor. DatabaseGenerated attribute is a new data annotation which has been added to System.ComponentModel.DataAnnotations namespace in CTP5: public abstract class BillingDetail {     [DatabaseGenerated(DatabaseGenerationOption.None)]     public int BillingDetailId { get; set; }     public string Owner { get; set; }     public string Number { get; set; } } As always, we can achieve the same result by using fluent API, if you prefer that: modelBuilder.Entity<BillingDetail>()             .Property(p => p.BillingDetailId)             .HasDatabaseGenerationOption(DatabaseGenerationOption.None); Working With The Object Model Our TPC mapping is ready and we can try adding new records to the database. But, like I said, now we need to take care of providing unique keys when creating new objects: using (var context = new InheritanceMappingContext()) {     BankAccount bankAccount = new BankAccount()      {          BillingDetailId = 1                          };     CreditCard creditCard = new CreditCard()      {          BillingDetailId = 2,         CardType = 1     };                      context.BillingDetails.Add(bankAccount);     context.BillingDetails.Add(creditCard);     context.SaveChanges(); } Polymorphic Associations with TPC is Problematic The main problem with this approach is that it doesn’t support Polymorphic Associations very well. After all, in the database, associations are represented as foreign key relationships and in TPC, the subclasses are all mapped to different tables so a polymorphic association to their base class (abstract BillingDetail in our example) cannot be represented as a simple foreign key relationship. For example, consider the the domain model we introduced here where User has a polymorphic association with BillingDetail. This would be problematic in our TPC Schema, because if User has a many-to-one relationship with BillingDetail, the Users table would need a single foreign key column, which would have to refer both concrete subclass tables. This isn’t possible with regular foreign key constraints. Schema Evolution with TPC is Complex A further conceptual problem with this mapping strategy is that several different columns, of different tables, share exactly the same semantics. This makes schema evolution more complex. For example, a change to a base class property results in changes to multiple columns. It also makes it much more difficult to implement database integrity constraints that apply to all subclasses. Generated SQLLet's examine SQL output for polymorphic queries in TPC mapping. For example, consider this polymorphic query for all BillingDetails and the resulting SQL statements that being executed in the database: var query = from b in context.BillingDetails select b; Just like the SQL query generated by TPT mapping, the CASE statements that you see in the beginning of the query is merely to ensure columns that are irrelevant for a particular row have NULL values in the returning flattened table. (e.g. BankName for a row that represents a CreditCard type). TPC's SQL Queries are Union Based As you can see in the above screenshot, the first SELECT uses a FROM-clause subquery (which is selected with a red rectangle) to retrieve all instances of BillingDetails from all concrete class tables. The tables are combined with a UNION operator, and a literal (in this case, 0 and 1) is inserted into the intermediate result; (look at the lines highlighted in yellow.) EF reads this to instantiate the correct class given the data from a particular row. A union requires that the queries that are combined, project over the same columns; hence, EF has to pad and fill up nonexistent columns with NULL. This query will really perform well since here we can let the database optimizer find the best execution plan to combine rows from several tables. There is also no Joins involved so it has a better performance than the SQL queries generated by TPT where a Join is required between the base and subclasses tables. Choosing Strategy GuidelinesBefore we get into this discussion, I want to emphasize that there is no one single "best strategy fits all scenarios" exists. As you saw, each of the approaches have their own advantages and drawbacks. Here are some rules of thumb to identify the best strategy in a particular scenario: If you don’t require polymorphic associations or queries, lean toward TPC—in other words, if you never or rarely query for BillingDetails and you have no class that has an association to BillingDetail base class. I recommend TPC (only) for the top level of your class hierarchy, where polymorphism isn’t usually required, and when modification of the base class in the future is unlikely. If you do require polymorphic associations or queries, and subclasses declare relatively few properties (particularly if the main difference between subclasses is in their behavior), lean toward TPH. Your goal is to minimize the number of nullable columns and to convince yourself (and your DBA) that a denormalized schema won’t create problems in the long run. If you do require polymorphic associations or queries, and subclasses declare many properties (subclasses differ mainly by the data they hold), lean toward TPT. Or, depending on the width and depth of your inheritance hierarchy and the possible cost of joins versus unions, use TPC. By default, choose TPH only for simple problems. For more complex cases (or when you’re overruled by a data modeler insisting on the importance of nullability constraints and normalization), you should consider the TPT strategy. But at that point, ask yourself whether it may not be better to remodel inheritance as delegation in the object model (delegation is a way of making composition as powerful for reuse as inheritance). Complex inheritance is often best avoided for all sorts of reasons unrelated to persistence or ORM. EF acts as a buffer between the domain and relational models, but that doesn’t mean you can ignore persistence concerns when designing your classes. SummaryIn this series, we focused on one of the main structural aspect of the object/relational paradigm mismatch which is inheritance and discussed how EF solve this problem as an ORM solution. We learned about the three well-known inheritance mapping strategies and their implementations in EF Code First. Hopefully it gives you a better insight about the mapping of inheritance hierarchies as well as choosing the best strategy for your particular scenario. Happy New Year and Happy Code-Firsting! References ADO.NET team blog Java Persistence with Hibernate book a { color: #5A99FF; } a:visited { color: #5A99FF; } .title { padding-bottom: 5px; font-family: Segoe UI; font-size: 11pt; font-weight: bold; padding-top: 15px; } .code, .typeName { font-family: consolas; } .typeName { color: #2b91af; } .padTop5 { padding-top: 5px; } .padTop10 { padding-top: 10px; } .exception { background-color: #f0f0f0; font-style: italic; padding-bottom: 5px; padding-left: 5px; padding-top: 5px; padding-right: 5px; }

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  • Include weather information in ASP.Net site from weather.com services

    - by sreejukg
    In this article, I am going to demonstrate how you can use the XMLOAP services (referred as XOAP from here onwards) provided by weather.com to display the weather information in your website. The XOAP services are available to be used for free of charge, provided you are comply with requirements from weather.com. I am writing this article from a technical point of view. If you are planning to use weather.com XOAP services in your application, please refer to the terms and conditions from weather.com website. In order to start using the XOAP services, you need to sign up the XOAP datafeed. The signing process is simple, you simply browse the url http://www.weather.com/services/xmloap.html. The URL looks similar to the following. Click on the sign up button, you will reach the registration page. Here you need to specify the site name you need to use this feed for. The form looks similar to the following. Once you fill all the mandatory information, click on save and continue button. That’s it. The registration is over. You will receive an email that contains your partner id, license key and SDK. The SDK available in a zipped format, contains the terms of use and documentation about the services available. Other than this the SDK includes the logos and icons required to display the weather information. As per the SDK, currently there are 2 types of information available through XOAP. These services are Current Conditions for over 30,000 U.S. and over 7,900 international Location IDs Updated at least Hourly Five-Day Forecast (today + 4 additional forecast days in consecutive order beginning with tomorrow) for over 30,000 U.S. and over 7,900 international Location IDs Updated at least Three Times Daily The SDK provides detailed information about the fields included in response of each service. Additionally there is a refresh rate that you need to comply with. As per the SDK, the refresh rate means the following “Refresh Rate” shall mean the maximum frequency with which you may call the XML Feed for a given LocID requesting a data set for that LocID. During the time period in between refresh periods the data must be cached by you either in the memory on your servers or in Your Desktop Application. About the Services Weather.com will provide you with access to the XML Feed over the Internet through the hostname xoap.weather.com. The weather data from the XML feed must be requested for a specific location. So you need a location ID (LOC ID). The XML feed work with 2 types of location IDs. First one is with City Identifiers and second one is using 5 Digit US postal codes. If you do not know your location ID, don’t worry, there is a location id search service available for you to retrieve the location id from city name. Since I am a resident in the Kingdom of Bahrain, I am going to retrieve the weather information for Manama(the capital of Bahrain) . In order to get the location ID for Manama, type the following URL in your address bar. http://xoap.weather.com/search/search?where=manama I got the following XML output. <?xml version="1.0" encoding="UTF-8"?> <!-- This document is intended only for use by authorized licensees of The –> <!-- Weather Channel. Unauthorized use is prohibited. Copyright 1995-2011, –> <!-- The Weather Channel Interactive, Inc. All Rights Reserved. –> <search ver="3.0">       <loc id="BAXX0001" type="1">Al Manama, Bahrain</loc> </search> You can try this with any city name, if the city is available, it will return the location id, and otherwise, it will return nothing. In order to get the weather information, from XOAP,  you need to pass certain parameters to the XOAP service. A brief about the parameters are as follows. Please refer SDK for more details. Parameter name Possible Value cc Optional, if you include this, the current condition will be returned. Value can be anything, as it will be ignored e.g. cc=* dayf If you want the forecast for 5 days, specify dayf=5 This is optional iink Value should be XOAP par Your partner id. You can find this in your registration email from weather.com prod Value should be XOAP key The license key assigned to you. This will be available in the registration email unit s or m (standard or matric or you can think of Celsius/Fahrenheit) this is optional field, if not specified the unit will be standard(s) The URL host for the XOAP service is http://xoap.weather.com. So for my purpose, I need the following request to be made to access the XOAP services. http://xoap.weather.com/weather/local/BAXX0001?cc=*&link=xoap&prod=xoap&par=*********&key=************** (The ***** to be replaced with the corresponding alternatives) The response XML have a root element “weather”. Under the root element, it has the following sections <head> - the meta data information about the weather results returned. <loc> - the location data block that provides, the information about the location for which the wheather data is retrieved. <lnks> - the 4 promotional links you need to place along with the weather display. Additional to these 4 links, there should be another link with weather channel logo to the home page of weather.com. <cc> - the current condition data. This element will be there only if you specify the cc element in the request. <dayf> - the forcast data as you specified. This element will be there only if you specify the dayf in the request. In this walkthrough, I am going to capture the weather information for Manama (Location ID: BAXX0001). You need 2 applications to display weather information in your website. A Console application that retrieves data from the XMLOAP and store in the SQL Server database (or any data store as you prefer).This application will be scheduled to execute in every 25 minutes using windows task scheduler, so that we can comply with the refresh rate. A web application that display data from the SQL Server database Retrieve the Weather from XOAP I have created a console application named, Weather Service. I created a SQL server database, with the following columns. I named the table as tblweather. You are free to choose any name. Column name Description lastUpdated Datetime, this is the last time when the weather data is updated. This is the time of the service running TemparatureDateTime The date and time returned by XML feed Temparature The temperature returned by the XML feed. TemparatureUnit The unit of the temperature returned by the XML feed iconId The id of the icon to be used. Currently 48 icons from 0 to 47 are available. WeatherDescription The Weather Description Phrase returned by the feed. Link1url The url to the first promo link Link1Text The text for the first promo link Link2url The url to the second promo link Link2Text The text for the second promo link Link3url The url to the third promo link Link3Text The text for the third promo link Link4url The url to the fourth promo link Link4Text The text for the fourth promo link Every time when the service runs, the application will update the database columns from the XOAP data feed. When the application starts, It is going to get the data as XML from the url. This demonstration uses LINQ to extract the necessary data from the fetched XML. The following are the code segment for extracting data from the weather XML using LINQ. // first, create an instance of the XDocument class with the XOAP URL. replace **** with the corresponding values. XDocument weather = XDocument.Load("http://xoap.weather.com/weather/local/BAXX0001?cc=*&link=xoap&prod=xoap&par=***********&key=c*********"); // construct a query using LINQ var feedResult = from item in weather.Descendants() select new { unit = item.Element("head").Element("ut").Value, temp = item.Element("cc").Element("tmp").Value, tempDate = item.Element("cc").Element("lsup").Value, iconId = item.Element("cc").Element("icon").Value, description = item.Element("cc").Element("t").Value, links = from link in item.Elements("lnks").Elements("link") select new { url = link.Element("l").Value, text = link.Element("t").Value } }; // Load the root node to a variable, you may use foreach construct instead. var item1 = feedResult.First(); *If you want to learn more about LINQ and XML, read this nice blog from Scott GU. http://weblogs.asp.net/scottgu/archive/2007/08/07/using-linq-to-xml-and-how-to-build-a-custom-rss-feed-reader-with-it.aspx Now you have all the required values in item1. For e.g. if you want to get the temperature, use item1.temp; Now I just need to execute an SQL query against the database. See the connection part. using (SqlConnection conn = new SqlConnection(@"Data Source=sreeju\sqlexpress;Initial Catalog=Sample;Integrated Security=True")) { string strSql = @"update tblweather set lastupdated=getdate(), temparatureDateTime = @temparatureDateTime, temparature=@temparature, temparatureUnit=@temparatureUnit, iconId = @iconId, description=@description, link1url=@link1url, link1text=@link1text, link2url=@link2url, link2text=@link2text,link3url=@link3url, link3text=@link3text,link4url=@link4url, link4text=@link4text"; SqlCommand comm = new SqlCommand(strSql, conn); comm.Parameters.AddWithValue("temparatureDateTime", item1.tempDate); comm.Parameters.AddWithValue("temparature", item1.temp); comm.Parameters.AddWithValue("temparatureUnit", item1.unit); comm.Parameters.AddWithValue("description", item1.description); comm.Parameters.AddWithValue("iconId", item1.iconId); var lstLinks = item1.links; comm.Parameters.AddWithValue("link1url", lstLinks.ElementAt(0).url); comm.Parameters.AddWithValue("link1text", lstLinks.ElementAt(0).text); comm.Parameters.AddWithValue("link2url", lstLinks.ElementAt(1).url); comm.Parameters.AddWithValue("link2text", lstLinks.ElementAt(1).text); comm.Parameters.AddWithValue("link3url", lstLinks.ElementAt(2).url); comm.Parameters.AddWithValue("link3text", lstLinks.ElementAt(2).text); comm.Parameters.AddWithValue("link4url", lstLinks.ElementAt(3).url); comm.Parameters.AddWithValue("link4text", lstLinks.ElementAt(3).text); conn.Open(); comm.ExecuteNonQuery(); conn.Close(); Console.WriteLine("database updated"); } Now click ctrl + f5 to run the service. I got the following output Check your database and make sure, the data is updated with the latest information from the service. (Make sure you inserted one row in the database by entering some values before executing the service. Otherwise you need to modify your application code to count the rows and conditionally perform insert/update query) Display the Weather information in ASP.Net page Now you got all the data in the database. You just need to create a web application and display the data from the database. I created a new ASP.Net web application with a default.aspx page. In order to comply with the terms of weather.com, You need to use Weather.com logo along with the weather display. You can find the necessary logos to use under the folder “logos” in the SDK. Additionally copy any of the icon set from the folder “icons” to your web application. I used the 93x93 icon set. You are free to use any other sizes available. The design view of the page in VS2010 looks similar to the following. The page contains a heading, an image control (for displaying the weather icon), 2 label controls (for displaying temperature and weather description), 4 hyperlinks (for displaying the 4 promo links returned by the XOAP service) and weather.com logo with hyperlink to the weather.com home page. I am going to write code that will update the values of these controls from the values stored in the database by the service application as mentioned in the previous step. Go to the code behind file for the webpage, enter the following code under Page_Load event handler. using (SqlConnection conn = new SqlConnection(@"Data Source=sreeju\sqlexpress;Initial Catalog=Sample;Integrated Security=True")) { SqlCommand comm = new SqlCommand("select top 1 * from tblweather", conn); conn.Open(); SqlDataReader reader = comm.ExecuteReader(); if (reader.Read()) { lblTemparature.Text = reader["temparature"].ToString() + "&deg;" + reader["temparatureUnit"].ToString(); lblWeatherDescription.Text = reader["description"].ToString(); imgWeather.ImageUrl = "icons/" + reader["iconId"].ToString() + ".png"; lnk1.Text = reader["link1text"].ToString(); lnk1.NavigateUrl = reader["link1url"].ToString(); lnk2.Text = reader["link2text"].ToString(); lnk2.NavigateUrl = reader["link2url"].ToString(); lnk3.Text = reader["link3text"].ToString(); lnk3.NavigateUrl = reader["link3url"].ToString(); lnk4.Text = reader["link4text"].ToString(); lnk4.NavigateUrl = reader["link4url"].ToString(); } conn.Close(); } Press ctrl + f5 to run the page. You will see the following output. That’s it. You need to configure the console application to run every 25 minutes so that the database is updated. Also you can fetch the forecast information and store those in the database, and then retrieve it later in your web page. Since the data resides in your database, you have the full control over your display. You need to make sure your website comply with weather.com license requirements. If you want to get the source code of this walkthrough through the application, post your email address below. Hope you enjoy the reading.

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  • collectd does not work

    - by bery
    I have installed collectd-5.0.0 on Fedora12 server and would like to run its service for receiving data from clients. I have enabled network plugin and rddtool plugin as commented: collectd.conf in server: BaseDir "/opt/collectd/var/lib/collectd" LoadPlugin "logfile" LoadPlugin network LoadPlugin rrdtool <Plugin network> Listen "192.168.8.37" "25826" </Plugin> collectd.conf in client: LoadPlugin logfile LoadPlugin cpu LoadPlugin network LoadPlugin memory <Plugin network> Server"192.168.8.37" "25826" </Plugin> collectd.log in server: [2011-08-03 02:36:04] Exiting normally. [2011-08-03 02:36:04] rrdtool plugin: Shutting down the queue thread. [2011-08-03 02:36:04] network plugin: Stopping receive thread. [2011-08-03 02:36:04] network plugin: Stopping dispatch thread. [2011-08-03 02:37:11] Initialization complete, entering read-loop. collectd.log in client: [2011-08-02 17:31:44] Initialization complete, entering read-loop. results thst execute netstat on server: netstat -ulpn | grep 25826 udp 0 0 192.168.8.37:25826 0.0.0.0:* 4744/collectd problem: but there is noting in "/opt/collectd/var/lib/collectd/" on ser yes,I move the port number of "25826" as your propose(But I think this is the default port for coolectd).there is no rdd files recived on server. collectd.log in client collectd [2011-08-03 10:01:36] plugin_read_thread: Handling memory'. [2011-08-03 10:01:36] plugin_read_thread: Handlingcpu'. [2011-08-03 10:01:36] plugin_dispatch_values: time = 1312380096.431; interval = 10.000; host = uml; plugin = memory; plugin_instance = ; type = memory; type_instance = used; [2011-08-03 10:01:36] plugin_dispatch_values: time = 1312380096.431; interval = 10.000; host = uml; plugin = cpu; plugin_instance = 0; type = cpu; type_instance = user; [2011-08-03 10:01:36] uc_update: uml/memory/memory-used: ds[0] = 280412160.000000 [2011-08-03 10:01:36] plugin: plugin_write: Writing values via network. [2011-08-03 10:01:36] uc_update: uml/cpu-0/cpu-user: ds[0] = 0.100008 [2011-08-03 10:01:36] plugin: plugin_write: Writing values via network. [2011-08-03 10:01:36] plugin_dispatch_values: time = 1312380096.431; interval = 10.000; host = uml; plugin = memory; plugin_instance = ; type = memory; type_instance = buffered; [2011-08-03 10:01:36] plugin_dispatch_values: time = 1312380096.431; interval = 10.000; host = uml; plugin = cpu; plugin_instance = 0; type = cpu; type_instance = nice; [2011-08-03 10:01:36] uc_update: uml/memory/memory-buffered: ds[0] = 344182784.000000 [2011-08-03 10:01:36] plugin: plugin_write: Writing values via network. [2011-08-03 10:01:36] uc_update: uml/cpu-0/cpu-nice: ds[0] = 0.000000 [2011-08-03 10:01:36] plugin: plugin_write: Writing values via network. [2011-08-03 10:01:36] network plugin: flush_buffer: send_buffer_fill = 1340 [2011-08-03 10:01:36] network plugin: network_send_buffer: buffer_len = 1340 ... [2011-08-03 10:01:36] plugin_read_thread: Next read of the cpu plugin at 1312380106.429064774. collectd.log in server collectd: [2011-08-03 20:18:08] type = network [2011-08-03 20:18:08] type = rrdtool [2011-08-03 20:18:08] network plugin: sockent_open: node = 192.168.8.37; service = 25826; [2011-08-03 20:18:08] fd = 3; calling bind' [2011-08-03 20:18:08] Done parsing/opt/collectd//share/collectd/types.db' [2011-08-03 20:18:08] interval_g = 10; [2011-08-03 20:18:08] timeout_g = 2; [2011-08-03 20:18:08] hostname_g = localhost.localdomain; [2011-08-03 20:18:08] Initialization complete, entering read-loop. It looks like, data is sending but doesn't be recived. Where is the mistake?

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  • Excel: conditionally format a cell using the format of another, content-matching cell

    - by Eric A. Meyer
    I have an Excel spreadsheet where I’d like to be able to create a “key” of formatted cells with unique values, and then in another sheet format cells using the key formatting. So for example, my key is as follows, with one value per cell and the visual formatting indicated in parentheses: A (red background) B (green background) C (blue background) So that’s on one sheet (or in a remote corner of the current sheet—whichever is better). Then, in an area that I mark for conditional formatting, I can type one of those three letters and have the cell where I typed it visually formatted according to the key. So if I type a “B” into one of the conditionally formatted cells, it gets a green background. (Note that I’m using backgrounds here solely for ease of explanation: ideally I want to have all visual formatting copied over, whether it’s foreground color, background color, font weight, borders, or whatever. But I’ll take what I can get, obviously.) And—just to make it extra-tricky—if I change the formatting in the key, that change should be reflected in cells that reference the key. Thus, if I change the “B” formatting in the key from a green background to a purple background, any “B” in the main sheet should switch to the new color. Similarly, it should be possible to add or remove values from the key and have those changes applied to the main data set. I’m okay with the formatting-update-on-key-change being triggered by clicking a button or something. I suspect that if any of this is possible it will require VBA, but I’ve never used it so I’ve no idea where to start if that’s the case. I’m hoping it’s possible without VBA. I know it’s possible to just use multiple conditional formats, but my use case here is that I’m trying to create the above-described capability for someone who isn’t conversant with conditional formatting. I’d like to let them be able to define a key, update it if necessary, and keep on truckin’ without me having to rewrite the spreadsheet’s formatting rules for them. --- UPDATE --- So I think I was a bit unclear about my original request. Let me try again with an image. The image shows the “key” on the left, where values and styles are defined using keyboard and mouse input. On the right, you see the data that should be formatted to match the key. Thus if I type a “C” into a cell in the Data area, it should be blue-backed. Furthermore, if I change the formatting of “C” in the Key to have a purple background, all the “C” cells should switch from blue to purple. For further craziness, if I add more to the Key (say, “D” with a yellow background) then any “D” cells will be styled to match; if I remove a Key entry, then matching values in the Data area should revert to default styling. So. Is that more clear? Is it possible, in whole or in part? I don’t have to use conditional formatting for this; in fact, at this point I suspect I probably shouldn’t. But I’m open to any approach!

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  • ASPNET WebAPI REST Guidance

    - by JoshReuben
    ASP.NET Web API is an ideal platform for building RESTful applications on the .NET Framework. While I may be more partial to NodeJS these days, there is no denying that WebAPI is a well engineered framework. What follows is my investigation of how to leverage WebAPI to construct a RESTful frontend API.   The Advantages of REST Methodology over SOAP Simpler API for CRUD ops Standardize Development methodology - consistent and intuitive Standards based à client interop Wide industry adoption, Ease of use à easy to add new devs Avoid service method signature blowout Smaller payloads than SOAP Stateless à no session data means multi-tenant scalability Cache-ability Testability   General RESTful API Design Overview · utilize HTTP Protocol - Usage of HTTP methods for CRUD, standard HTTP response codes, common HTTP headers and Mime Types · Resources are mapped to URLs, actions are mapped to verbs and the rest goes in the headers. · keep the API semantic, resource-centric – A RESTful, resource-oriented service exposes a URI for every piece of data the client might want to operate on. A REST-RPC Hybrid exposes a URI for every operation the client might perform: one URI to fetch a piece of data, a different URI to delete that same data. utilize Uri to specify CRUD op, version, language, output format: http://api.MyApp.com/{ver}/{lang}/{resource_type}/{resource_id}.{output_format}?{key&filters} · entity CRUD operations are matched to HTTP methods: · Create - POST / PUT · Read – GET - cacheable · Update – PUT · Delete - DELETE · Use Uris to represent a hierarchies - Resources in RESTful URLs are often chained · Statelessness allows for idempotency – apply an op multiple times without changing the result. POST is non-idempotent, the rest are idempotent (if DELETE flags records instead of deleting them). · Cache indication - Leverage HTTP headers to label cacheable content and indicate the permitted duration of cache · PUT vs POST - The client uses PUT when it determines which URI (Id key) the new resource should have. The client uses POST when the server determines they key. PUT takes a second param – the id. POST creates a new resource. The server assigns the URI for the new object and returns this URI as part of the response message. Note: The PUT method replaces the entire entity. That is, the client is expected to send a complete representation of the updated product. If you want to support partial updates, the PATCH method is preferred DELETE deletes a resource at a specified URI – typically takes an id param · Leverage Common HTTP Response Codes in response headers 200 OK: Success 201 Created - Used on POST request when creating a new resource. 304 Not Modified: no new data to return. 400 Bad Request: Invalid Request. 401 Unauthorized: Authentication. 403 Forbidden: Authorization 404 Not Found – entity does not exist. 406 Not Acceptable – bad params. 409 Conflict - For POST / PUT requests if the resource already exists. 500 Internal Server Error 503 Service Unavailable · Leverage uncommon HTTP Verbs to reduce payload sizes HEAD - retrieves just the resource meta-information. OPTIONS returns the actions supported for the specified resource. PATCH - partial modification of a resource. · When using PUT, POST or PATCH, send the data as a document in the body of the request. Don't use query parameters to alter state. · Utilize Headers for content negotiation, caching, authorization, throttling o Content Negotiation – choose representation (e.g. JSON or XML and version), language & compression. Signal via RequestHeader.Accept & ResponseHeader.Content-Type Accept: application/json;version=1.0 Accept-Language: en-US Accept-Charset: UTF-8 Accept-Encoding: gzip o Caching - ResponseHeader: Expires (absolute expiry time) or Cache-Control (relative expiry time) o Authorization - basic HTTP authentication uses the RequestHeader.Authorization to specify a base64 encoded string "username:password". can be used in combination with SSL/TLS (HTTPS) and leverage OAuth2 3rd party token-claims authorization. Authorization: Basic sQJlaTp5ZWFslylnaNZ= o Rate Limiting - Not currently part of HTTP so specify non-standard headers prefixed with X- in the ResponseHeader. X-RateLimit-Limit: 10000 X-RateLimit-Remaining: 9990 · HATEOAS Methodology - Hypermedia As The Engine Of Application State – leverage API as a state machine where resources are states and the transitions between states are links between resources and are included in their representation (hypermedia) – get API metadata signatures from the response Link header - in a truly REST based architecture any URL, except the initial URL, can be changed, even to other servers, without worrying about the client. · error responses - Do not just send back a 200 OK with every response. Response should consist of HTTP error status code (JQuery has automated support for this), A human readable message , A Link to a meaningful state transition , & the original data payload that was problematic. · the URIs will typically map to a server-side controller and a method name specified by the type of request method. Stuff all your calls into just four methods is not as crazy as it sounds. · Scoping - Path variables look like you’re traversing a hierarchy, and query variables look like you’re passing arguments into an algorithm · Mapping URIs to Controllers - have one controller for each resource is not a rule – can consolidate - route requests to the appropriate controller and action method · Keep URls Consistent - Sometimes it’s tempting to just shorten our URIs. not recommend this as this can cause confusion · Join Naming – for m-m entity relations there may be multiple hierarchy traversal paths · Routing – useful level of indirection for versioning, server backend mocking in development ASPNET WebAPI Considerations ASPNET WebAPI implements a lot (but not all) RESTful API design considerations as part of its infrastructure and via its coding convention. Overview When developing an API there are basically three main steps: 1. Plan out your URIs 2. Setup return values and response codes for your URIs 3. Implement a framework for your API.   Design · Leverage Models MVC folder · Repositories – support IoC for tests, abstraction · Create DTO classes – a level of indirection decouples & allows swap out · Self links can be generated using the UrlHelper · Use IQueryable to support projections across the wire · Models can support restful navigation properties – ICollection<T> · async mechanism for long running ops - return a response with a ticket – the client can then poll or be pushed the final result later. · Design for testability - Test using HttpClient , JQuery ( $.getJSON , $.each) , fiddler, browser debug. Leverage IDependencyResolver – IoC wrapper for mocking · Easy debugging - IE F12 developer tools: Network tab, Request Headers tab     Routing · HTTP request method is matched to the method name. (This rule applies only to GET, POST, PUT, and DELETE requests.) · {id}, if present, is matched to a method parameter named id. · Query parameters are matched to parameter names when possible · Done in config via Routes.MapHttpRoute – similar to MVC routing · Can alternatively: o decorate controller action methods with HttpDelete, HttpGet, HttpHead,HttpOptions, HttpPatch, HttpPost, or HttpPut., + the ActionAttribute o use AcceptVerbsAttribute to support other HTTP verbs: e.g. PATCH, HEAD o use NonActionAttribute to prevent a method from getting invoked as an action · route table Uris can support placeholders (via curly braces{}) – these can support default values and constraints, and optional values · The framework selects the first route in the route table that matches the URI. Response customization · Response code: By default, the Web API framework sets the response status code to 200 (OK). But according to the HTTP/1.1 protocol, when a POST request results in the creation of a resource, the server should reply with status 201 (Created). Non Get methods should return HttpResponseMessage · Location: When the server creates a resource, it should include the URI of the new resource in the Location header of the response. public HttpResponseMessage PostProduct(Product item) {     item = repository.Add(item);     var response = Request.CreateResponse<Product>(HttpStatusCode.Created, item);     string uri = Url.Link("DefaultApi", new { id = item.Id });     response.Headers.Location = new Uri(uri);     return response; } Validation · Decorate Models / DTOs with System.ComponentModel.DataAnnotations properties RequiredAttribute, RangeAttribute. · Check payloads using ModelState.IsValid · Under posting – leave out values in JSON payload à JSON formatter assigns a default value. Use with RequiredAttribute · Over-posting - if model has RO properties à use DTO instead of model · Can hook into pipeline by deriving from ActionFilterAttribute & overriding OnActionExecuting Config · Done in App_Start folder > WebApiConfig.cs – static Register method: HttpConfiguration param: The HttpConfiguration object contains the following members. Member Description DependencyResolver Enables dependency injection for controllers. Filters Action filters – e.g. exception filters. Formatters Media-type formatters. by default contains JsonFormatter, XmlFormatter IncludeErrorDetailPolicy Specifies whether the server should include error details, such as exception messages and stack traces, in HTTP response messages. Initializer A function that performs final initialization of the HttpConfiguration. MessageHandlers HTTP message handlers - plug into pipeline ParameterBindingRules A collection of rules for binding parameters on controller actions. Properties A generic property bag. Routes The collection of routes. Services The collection of services. · Configure JsonFormatter for circular references to support links: PreserveReferencesHandling.Objects Documentation generation · create a help page for a web API, by using the ApiExplorer class. · The ApiExplorer class provides descriptive information about the APIs exposed by a web API as an ApiDescription collection · create the help page as an MVC view public ILookup<string, ApiDescription> GetApis()         {             return _explorer.ApiDescriptions.ToLookup(                 api => api.ActionDescriptor.ControllerDescriptor.ControllerName); · provide documentation for your APIs by implementing the IDocumentationProvider interface. Documentation strings can come from any source that you like – e.g. extract XML comments or define custom attributes to apply to the controller [ApiDoc("Gets a product by ID.")] [ApiParameterDoc("id", "The ID of the product.")] public HttpResponseMessage Get(int id) · GlobalConfiguration.Configuration.Services – add the documentation Provider · To hide an API from the ApiExplorer, add the ApiExplorerSettingsAttribute Plugging into the Message Handler pipeline · Plug into request / response pipeline – derive from DelegatingHandler and override theSendAsync method – e.g. for logging error codes, adding a custom response header · Can be applied globally or to a specific route Exception Handling · Throw HttpResponseException on method failures – specify HttpStatusCode enum value – examine this enum, as its values map well to typical op problems · Exception filters – derive from ExceptionFilterAttribute & override OnException. Apply on Controller or action methods, or add to global HttpConfiguration.Filters collection · HttpError object provides a consistent way to return error information in the HttpResponseException response body. · For model validation, you can pass the model state to CreateErrorResponse, to include the validation errors in the response public HttpResponseMessage PostProduct(Product item) {     if (!ModelState.IsValid)     {         return Request.CreateErrorResponse(HttpStatusCode.BadRequest, ModelState); Cookie Management · Cookie header in request and Set-Cookie headers in a response - Collection of CookieState objects · Specify Expiry, max-age resp.Headers.AddCookies(new CookieHeaderValue[] { cookie }); Internet Media Types, formatters and serialization · Defaults to application/json · Request Accept header and response Content-Type header · determines how Web API serializes and deserializes the HTTP message body. There is built-in support for XML, JSON, and form-urlencoded data · customizable formatters can be inserted into the pipeline · POCO serialization is opt out via JsonIgnoreAttribute, or use DataMemberAttribute for optin · JSON serializer leverages NewtonSoft Json.NET · loosely structured JSON objects are serialzed as JObject which derives from Dynamic · to handle circular references in json: json.SerializerSettings.PreserveReferencesHandling =    PreserveReferencesHandling.All à {"$ref":"1"}. · To preserve object references in XML [DataContract(IsReference=true)] · Content negotiation Accept: Which media types are acceptable for the response, such as “application/json,” “application/xml,” or a custom media type such as "application/vnd.example+xml" Accept-Charset: Which character sets are acceptable, such as UTF-8 or ISO 8859-1. Accept-Encoding: Which content encodings are acceptable, such as gzip. Accept-Language: The preferred natural language, such as “en-us”. o Web API uses the Accept and Accept-Charset headers. (At this time, there is no built-in support for Accept-Encoding or Accept-Language.) · Controller methods can take JSON representations of DTOs as params – auto-deserialization · Typical JQuery GET request: function find() {     var id = $('#prodId').val();     $.getJSON("api/products/" + id,         function (data) {             var str = data.Name + ': $' + data.Price;             $('#product').text(str);         })     .fail(         function (jqXHR, textStatus, err) {             $('#product').text('Error: ' + err);         }); }            · Typical GET response: HTTP/1.1 200 OK Server: ASP.NET Development Server/10.0.0.0 Date: Mon, 18 Jun 2012 04:30:33 GMT X-AspNet-Version: 4.0.30319 Cache-Control: no-cache Pragma: no-cache Expires: -1 Content-Type: application/json; charset=utf-8 Content-Length: 175 Connection: Close [{"Id":1,"Name":"TomatoSoup","Price":1.39,"ActualCost":0.99},{"Id":2,"Name":"Hammer", "Price":16.99,"ActualCost":10.00},{"Id":3,"Name":"Yo yo","Price":6.99,"ActualCost": 2.05}] True OData support · Leverage Query Options $filter, $orderby, $top and $skip to shape the results of controller actions annotated with the [Queryable]attribute. [Queryable]  public IQueryable<Supplier> GetSuppliers()  · Query: ~/Suppliers?$filter=Name eq ‘Microsoft’ · Applies the following selection filter on the server: GetSuppliers().Where(s => s.Name == “Microsoft”)  · Will pass the result to the formatter. · true support for the OData format is still limited - no support for creates, updates, deletes, $metadata and code generation etc · vnext: ability to configure how EditLinks, SelfLinks and Ids are generated Self Hosting no dependency on ASPNET or IIS: using (var server = new HttpSelfHostServer(config)) {     server.OpenAsync().Wait(); Tracing · tracability tools, metrics – e.g. send to nagios · use your choice of tracing/logging library, whether that is ETW,NLog, log4net, or simply System.Diagnostics.Trace. · To collect traces, implement the ITraceWriter interface public class SimpleTracer : ITraceWriter {     public void Trace(HttpRequestMessage request, string category, TraceLevel level,         Action<TraceRecord> traceAction)     {         TraceRecord rec = new TraceRecord(request, category, level);         traceAction(rec);         WriteTrace(rec); · register the service with config · programmatically trace – has helper extension methods: Configuration.Services.GetTraceWriter().Info( · Performance tracing - pipeline writes traces at the beginning and end of an operation - TraceRecord class includes aTimeStamp property, Kind property set to TraceKind.Begin / End Security · Roles class methods: RoleExists, AddUserToRole · WebSecurity class methods: UserExists, .CreateUserAndAccount · Request.IsAuthenticated · Leverage HTTP 401 (Unauthorized) response · [AuthorizeAttribute(Roles="Administrator")] – can be applied to Controller or its action methods · See section in WebApi document on "Claim-based-security for ASP.NET Web APIs using DotNetOpenAuth" – adapt this to STS.--> Web API Host exposes secured Web APIs which can only be accessed by presenting a valid token issued by the trusted issuer. http://zamd.net/2012/05/04/claim-based-security-for-asp-net-web-apis-using-dotnetopenauth/ · Use MVC membership provider infrastructure and add a DelegatingHandler child class to the WebAPI pipeline - http://stackoverflow.com/questions/11535075/asp-net-mvc-4-web-api-authentication-with-membership-provider - this will perform the login actions · Then use AuthorizeAttribute on controllers and methods for role mapping- http://sixgun.wordpress.com/2012/02/29/asp-net-web-api-basic-authentication/ · Alternate option here is to rely on MVC App : http://forums.asp.net/t/1831767.aspx/1

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  • MySQL Daemon failed to start.

    - by matthewsteiner
    There were no updates when I ran yum update. I was trying to install php-soap (which was failing), and online I found I should run this: wget -q -O - http://www.atomicorp.com/installers/atomic.sh |sh After running that, then "yum install php-soap" ran successfuly. Then I ran yum update just to check for updates and said yes for some packages. I noticed there were some mysql ones and such. Now mysql isn't running anymore and it won't let me start it (I get "MySQL Daemon failed to start") Ideas?

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  • How to install specific version of MySQL?

    - by user85569
    I installed from the repo, 5.0.77... including setup of PowerDNS (and the backend for MySQL). I tried setting up replication from my Master (which is MySQL 5.1.53) but it didn't work even though there were no errors, nothing got replicated. So the last resort is to try the same MySQL version on both the master and the slave (nb, only the slave has pdns installed) How would I go about installing MySQL 5.1.53? I tried downloading the rpm from MySQL (obviously the wrong one, didn't even include the mysql command to shell into the databases), but in turn fucked up the dependencies for pdns' mysql backend. I have the atomic repo which will install MySQL 5.5 (both on my Master server and Slave), but I don't want to do a major upgrade on the master right now as it's in production. Would love some advice!

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  • INNODB mysql. Plugin disabled

    - by alexcunn
    When I startup mysql on my unbuntu server I will get a message. 121122 17:39:37 [Note] Plugin 'FEDERATED' is disabled. 121122 17:39:37 InnoDB: The InnoDB memory heap is disabled 121122 17:39:37 InnoDB: Mutexes and rw_locks use GCC atomic builtins 121122 17:39:37 InnoDB: Compressed tables use zlib 1.2.3.4 121122 17:39:37 InnoDB: Initializing buffer pool, size = 128.0M InnoDB: mmap(137363456 bytes) failed; errno 12 121122 17:39:37 InnoDB: Completed initialization of buffer pool 121122 17:39:37 InnoDB: Fatal error: cannot allocate memory for the buffer pool 121122 17:39:37 [ERROR] Plugin 'InnoDB' init function returned error. 121122 17:39:37 [ERROR] Plugin 'InnoDB' registration as a STORAGE ENGINE failed. 121122 17:39:37 [ERROR] Unknown/unsupported storage engine: InnoDB 121122 17:39:37 [ERROR] Aborting 121122 17:39:37 [Note] mysqld: Shutdown complete a few times I have got a message saying that the plugin is disabled. I use webmin to configure it. Could that be a problem?

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  • XFS and loss of data when power goes down

    - by culebrón
    Each time electricity goes down, my desktop (without UPS) loses some temporary information. Opera can lose settings, history, cache, or mail accounts (Thanks heavens I was wise to use IMAP). Partially or all together. a whole file (complete and save) in Geany appeared empty (and I didn't commit it to Git) rhythmbox lost all podcasts subscription data I'm afraid there are other losses I just didn't see. What's the reason? A memory files cache, a mem-disk? Or non-atomic file writes in xfs? I have Ubuntu 9.10 and XFS on both / and /home partitions. Is ext4 safer in such circumstances? I've seen ext3 is faster. Is it as safe as *4? Given that the apartment I rent is connected to a common bus and 1 safety switch for several apartments, and the neighbors - alone or together - overload it at least once every week, the lights go down often enough for this to be an issue.

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  • Why does a group policy not applied to the domain administrator account?

    - by Saariko
    I have a working policy on my entire domain. I just found out, when logging with the domain administrator, that this policy is not applied (EDIT: Running : gpresult shows that the GPO's are applied - but, this GPO is for Drive Mappings, and the actual drive mappings are NOT shown) The administrator account - does not have any login script on his profile tab. My GPO's are mainly small/atomic settings: single GPO to handle each settings: UAC, Firewall, printers. GPO status for the object is enabled That's an overview of the Drive Maps: Reading on MS support site, I checked the delegation tab, and it is marked as applied to domain and enterprise admins. Every user gets these policies correctly. The OU that is set is the root of the domain. (for testing purpose - I did that to eliminate hierarchy issues - did not help) Block Inheritance is disabled. (never used it anyway) GPO link GPO Security Filterings

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  • PHP 5.2 installation with GD on CentOS 6

    - by Pratik Thakkar
    I am trying to install PHP 5.2.17 on CentOS 6.2. I have downloaded RPMs from http://www6.atomicorp.com/channels/atomic/centos/6/i386/RPMs/ Problem is that the PHP RPM seems to have GD disabled by default. Hence in spite installing php-gd RPM, GD is disabled. Is there any way that I can enable GD. Atomicorp seems to be the only website that has PHP 5.2.17 RPMs. I am not an advanced user to be able to compile PHP. I would appreciate help on this.

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