clustered index - Page 258

Building my first Javascript Application (jQuery), struggling on something

- by Jason Wells

I'd really appreciate recommendations on the most efficient way to approach this. I'm building a simple javascript application which displays a list of records and allows the user to edit a record by clicking an "Edit" link in the records row. The user also can click the "Add" link to pop open a dialog allowing them to add a new record. Here's a working prototype of this: http://jsfiddle.net/FfRcG/ You'll note if you click "Edit" a dialog pops up with some canned values. And, if you click "Add", a dialog pops up with empty values. I need help on how to approach two problems I believe we need to pass our index to our edit dialog and reference the values within the JSON, but I am unsure how to pass the index when the user clicks edit. It bothers me that the Edit and Add div contents are so similiar (Edit just pre populates the values). I feel like there is a more efficient way of doing this but am at a loss. Here is my code for reference $(document).ready( function(){ // Our JSON (This would actually be coming from an AJAX database call) people = { "COLUMNS":["DATEMODIFIED", "NAME","AGE"], "DATA":[ ["9/6/2012", "Person 1","32"], ["9/5/2012","Person 2","23"] ] } // Here we loop over our JSON and build our HTML (Will refactor to use templating eventually) members = people.DATA; var newcontent = '<table width=50%><tr><td>date</td><td>name</td><td>age</td><td></td></tr>'; for(var i=0;i<members.length;i++) { newcontent+= '<tr id="member'+i+'"><td>' + members[i][0] + '</td>'; newcontent+= '<td>' + members[i][1] + '</td>'; newcontent+= '<td>' + members[i][2] + '</td>'; newcontent+= '<td><a href="#" class="edit" id=edit'+i+'>Edit</a></td><td>'; } newcontent += "</table>"; $("#result").html(newcontent); // Bind a dialog to the edit link $(".edit").click( function(){ // Trigger our dialog to open $("#edit").dialog("open"); // Not sure the most efficient way to change our dialog field values $("#name").val() // ??? alert($()); return false; }); // Bind a dialog to the add link $(".edit").click( function(){ // Trigger our dialog to open $("#add").dialog("open"); return false; }); // Bind a dialog to our edit DIV $("#edit").dialog(); // Bind a dialog to our add DIV $("#add").dialog(); }); And here's the HTML <h1>People</h1> <a href="#" class="add">Add a new person</a>  <div id="result"></div>  <div id="edit"> <form> <p>Name:<br/><input type="text" id="name" value="foo"></p> <p>Age:<br/><input type="text" id="age" value="33"></p> <input type="submit" value="Save" id="submitEdit"> </form> </div>  <div id="add"> <form> <p>Name:<br/><input type="text" id="name"></p> <p>Age:<br/><input type="text" id="age"></p> <input type="submit" value="Save" id="submitEdit"> </form> </div>

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Trouble with a query

- by Mark Allison

Hi there, I'm having trouble with a query in SQL Server 2008 on some forex trading data. I have a trades table and an orders table. A trade needs to comprise of 2 or more orders. DDL schema and sample data below. What I want to do is write a query that shows the profit/loss in pips for each trade. A pip is 1/1000th of a currency. So the difference between USD 1.3441 and 1.3442 is 1 pip in forex-speak. A trade usually has one entry order and multiple exit orders. So for example if I buy 3 lots of the currency pair GBP/USD at the exchange rate of 1.6100 and then sell 1 lot at 1.6150, 1 lot at 1.6200 and 1 lot at 1.6250 then the profit is (1.6150 - 1.6100) + (1.6200 - 1.6100) + (1.6250 - 1.6100), or 50 + 100 + 150 = 300 pips profit. The trade could also go the other way (Shorting). For example the currency pair can be sold first before it's bought back later at a cheaper price. I would like a query that returns the following: tradeId, currencyPair, profitInPips It seems like a pretty straightforward query, but it's eluding me right now. Here's my DDL and sample data: CREATE TABLE [dbo].[trades]( [tradeId] [int] IDENTITY(1,1) NOT NULL, [currencyPair] [char](6) NOT NULL, CONSTRAINT [PK_trades] PRIMARY KEY CLUSTERED ( [tradeId] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY] GO SET ANSI_PADDING OFF GO SET IDENTITY_INSERT [dbo].[trades] ON INSERT [dbo].[trades] ([tradeId], [currencyPair]) VALUES (1, N'GBPUSD') INSERT [dbo].[trades] ([tradeId], [currencyPair]) VALUES (2, N'GBPUSD') INSERT [dbo].[trades] ([tradeId], [currencyPair]) VALUES (3, N'GBPUSD') INSERT [dbo].[trades] ([tradeId], [currencyPair]) VALUES (4, N'GBPUSD') INSERT [dbo].[trades] ([tradeId], [currencyPair]) VALUES (5, N'GBPUSD') INSERT [dbo].[trades] ([tradeId], [currencyPair]) VALUES (6, N'GBPUSD') INSERT [dbo].[trades] ([tradeId], [currencyPair]) VALUES (7, N'GBPUSD') INSERT [dbo].[trades] ([tradeId], [currencyPair]) VALUES (8, N'GBPUSD') INSERT [dbo].[trades] ([tradeId], [currencyPair]) VALUES (9, N'GBPUSD') INSERT [dbo].[trades] ([tradeId], [currencyPair]) VALUES (10, N'GBPUSD') SET IDENTITY_INSERT [dbo].[trades] OFF GO CREATE TABLE [dbo].[orders]( [orderId] [int] IDENTITY(1,1) NOT NULL, [tradeId] [int] NOT NULL, [amount] [decimal](18, 1) NOT NULL, [buySell] [char](1) NOT NULL, [rate] [decimal](18, 6) NOT NULL, [orderDateTime] [datetime] NOT NULL, CONSTRAINT [PK_orders] PRIMARY KEY CLUSTERED ( [orderId] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY] GO SET ANSI_PADDING OFF GO SET IDENTITY_INSERT [dbo].[orders] ON INSERT [dbo].[orders] ([orderId], [tradeId], [amount], [buySell], [rate], [orderDateTime]) VALUES (1, 1, CAST(3.0 AS Decimal(18, 1)), N'S', CAST(1.606500 AS Decimal(18, 6)), CAST(0x00009CF40083D600 AS DateTime)) INSERT [dbo].[orders] ([orderId], [tradeId], [amount], [buySell], [rate], [orderDateTime]) VALUES (2, 1, CAST(3.0 AS Decimal(18, 1)), N'B', CAST(1.615500 AS Decimal(18, 6)), CAST(0x00009CF400A4CB80 AS DateTime)) INSERT [dbo].[orders] ([orderId], [tradeId], [amount], [buySell], [rate], [orderDateTime]) VALUES (3, 2, CAST(3.0 AS Decimal(18, 1)), N'S', CAST(1.608000 AS Decimal(18, 6)), CAST(0x00009CF500000000 AS DateTime)) INSERT [dbo].[orders] ([orderId], [tradeId], [amount], [buySell], [rate], [orderDateTime]) VALUES (4, 2, CAST(1.0 AS Decimal(18, 1)), N'B', CAST(1.603000 AS Decimal(18, 6)), CAST(0x00009CF50083D600 AS DateTime)) INSERT [dbo].[orders] ([orderId], [tradeId], [amount], [buySell], [rate], [orderDateTime]) VALUES (5, 2, CAST(2.0 AS Decimal(18, 1)), N'B', CAST(1.605500 AS Decimal(18, 6)), CAST(0x00009CF50107AC00 AS DateTime)) INSERT [dbo].[orders] ([orderId], [tradeId], [amount], [buySell], [rate], [orderDateTime]) VALUES (6, 3, CAST(3.0 AS Decimal(18, 1)), N'S', CAST(1.595500 AS Decimal(18, 6)), CAST(0x00009CF70083D600 AS DateTime)) INSERT [dbo].[orders] ([orderId], [tradeId], [amount], [buySell], [rate], [orderDateTime]) VALUES (7, 3, CAST(1.0 AS Decimal(18, 1)), N'B', CAST(1.590500 AS Decimal(18, 6)), CAST(0x00009CF700C5C100 AS DateTime)) INSERT [dbo].[orders] ([orderId], [tradeId], [amount], [buySell], [rate], [orderDateTime]) VALUES (8, 3, CAST(2.0 AS Decimal(18, 1)), N'B', CAST(1.594500 AS Decimal(18, 6)), CAST(0x00009CF701499700 AS DateTime)) INSERT [dbo].[orders] ([orderId], [tradeId], [amount], [buySell], [rate], [orderDateTime]) VALUES (9, 4, CAST(3.0 AS Decimal(18, 1)), N'B', CAST(1.611000 AS Decimal(18, 6)), CAST(0x00009CFB0083D600 AS DateTime)) INSERT [dbo].[orders] ([orderId], [tradeId], [amount], [buySell], [rate], [orderDateTime]) VALUES (10, 4, CAST(1.0 AS Decimal(18, 1)), N'S', CAST(1.616000 AS Decimal(18, 6)), CAST(0x00009CFB00A4CB80 AS DateTime)) INSERT [dbo].[orders] ([orderId], [tradeId], [amount], [buySell], [rate], [orderDateTime]) VALUES (11, 4, CAST(2.0 AS Decimal(18, 1)), N'S', CAST(1.611500 AS Decimal(18, 6)), CAST(0x00009CFB0107AC00 AS DateTime)) INSERT [dbo].[orders] ([orderId], [tradeId], [amount], [buySell], [rate], [orderDateTime]) VALUES (12, 5, CAST(3.0 AS Decimal(18, 1)), N'B', CAST(1.613000 AS Decimal(18, 6)), CAST(0x00009CFC0083D600 AS DateTime)) INSERT [dbo].[orders] ([orderId], [tradeId], [amount], [buySell], [rate], [orderDateTime]) VALUES (13, 5, CAST(1.0 AS Decimal(18, 1)), N'S', CAST(1.618000 AS Decimal(18, 6)), CAST(0x00009CFC0107AC00 AS DateTime)) INSERT [dbo].[orders] ([orderId], [tradeId], [amount], [buySell], [rate], [orderDateTime]) VALUES (14, 5, CAST(1.0 AS Decimal(18, 1)), N'S', CAST(1.623000 AS Decimal(18, 6)), CAST(0x00009CFC0083D600 AS DateTime)) INSERT [dbo].[orders] ([orderId], [tradeId], [amount], [buySell], [rate], [orderDateTime]) VALUES (15, 5, CAST(1.0 AS Decimal(18, 1)), N'S', CAST(1.628000 AS Decimal(18, 6)), CAST(0x00009CFD00C5C100 AS DateTime)) INSERT [dbo].[orders] ([orderId], [tradeId], [amount], [buySell], [rate], [orderDateTime]) VALUES (16, 6, CAST(3.0 AS Decimal(18, 1)), N'B', CAST(1.632000 AS Decimal(18, 6)), CAST(0x00009D020083D600 AS DateTime)) INSERT [dbo].[orders] ([orderId], [tradeId], [amount], [buySell], [rate], [orderDateTime]) VALUES (17, 6, CAST(1.0 AS Decimal(18, 1)), N'S', CAST(1.637000 AS Decimal(18, 6)), CAST(0x00009D0200A4CB80 AS DateTime)) INSERT [dbo].[orders] ([orderId], [tradeId], [amount], [buySell], [rate], [orderDateTime]) VALUES (18, 6, CAST(2.0 AS Decimal(18, 1)), N'S', CAST(1.630000 AS Decimal(18, 6)), CAST(0x00009D0200C5C100 AS DateTime)) INSERT [dbo].[orders] ([orderId], [tradeId], [amount], [buySell], [rate], [orderDateTime]) VALUES (19, 7, CAST(3.0 AS Decimal(18, 1)), N'B', CAST(1.634500 AS Decimal(18, 6)), CAST(0x00009D0201499700 AS DateTime)) INSERT [dbo].[orders] ([orderId], [tradeId], [amount], [buySell], [rate], [orderDateTime]) VALUES (20, 7, CAST(1.0 AS Decimal(18, 1)), N'S', CAST(1.639500 AS Decimal(18, 6)), CAST(0x00009D0300000000 AS DateTime)) INSERT [dbo].[orders] ([orderId], [tradeId], [amount], [buySell], [rate], [orderDateTime]) VALUES (21, 7, CAST(1.0 AS Decimal(18, 1)), N'S', CAST(1.644500 AS Decimal(18, 6)), CAST(0x00009D030083D600 AS DateTime)) INSERT [dbo].[orders] ([orderId], [tradeId], [amount], [buySell], [rate], [orderDateTime]) VALUES (22, 7, CAST(1.0 AS Decimal(18, 1)), N'S', CAST(1.637500 AS Decimal(18, 6)), CAST(0x00009D0300C5C100 AS DateTime)) INSERT [dbo].[orders] ([orderId], [tradeId], [amount], [buySell], [rate], [orderDateTime]) VALUES (23, 8, CAST(3.0 AS Decimal(18, 1)), N'S', CAST(1.625000 AS Decimal(18, 6)), CAST(0x00009D0400C5C100 AS DateTime)) INSERT [dbo].[orders] ([orderId], [tradeId], [amount], [buySell], [rate], [orderDateTime]) VALUES (24, 8, CAST(1.0 AS Decimal(18, 1)), N'B', CAST(1.620000 AS Decimal(18, 6)), CAST(0x00009D050083D600 AS DateTime)) INSERT [dbo].[orders] ([orderId], [tradeId], [amount], [buySell], [rate], [orderDateTime]) VALUES (25, 8, CAST(1.0 AS Decimal(18, 1)), N'B', CAST(1.615000 AS Decimal(18, 6)), CAST(0x00009D0500A4CB80 AS DateTime)) INSERT [dbo].[orders] ([orderId], [tradeId], [amount], [buySell], [rate], [orderDateTime]) VALUES (26, 8, CAST(1.0 AS Decimal(18, 1)), N'S', CAST(1.623000 AS Decimal(18, 6)), CAST(0x00009D050107AC00 AS DateTime)) INSERT [dbo].[orders] ([orderId], [tradeId], [amount], [buySell], [rate], [orderDateTime]) VALUES (27, 9, CAST(3.0 AS Decimal(18, 1)), N'S', CAST(1.618000 AS Decimal(18, 6)), CAST(0x00009D0600C5C100 AS DateTime)) INSERT [dbo].[orders] ([orderId], [tradeId], [amount], [buySell], [rate], [orderDateTime]) VALUES (28, 9, CAST(1.0 AS Decimal(18, 1)), N'B', CAST(1.613000 AS Decimal(18, 6)), CAST(0x00009D0600D63BC0 AS DateTime)) INSERT [dbo].[orders] ([orderId], [tradeId], [amount], [buySell], [rate], [orderDateTime]) VALUES (29, 9, CAST(1.0 AS Decimal(18, 1)), N'B', CAST(1.608000 AS Decimal(18, 6)), CAST(0x00009D0600E6B680 AS DateTime)) INSERT [dbo].[orders] ([orderId], [tradeId], [amount], [buySell], [rate], [orderDateTime]) VALUES (30, 9, CAST(1.0 AS Decimal(18, 1)), N'B', CAST(1.613300 AS Decimal(18, 6)), CAST(0x00009D0601391C40 AS DateTime)) INSERT [dbo].[orders] ([orderId], [tradeId], [amount], [buySell], [rate], [orderDateTime]) VALUES (31, 10, CAST(3.0 AS Decimal(18, 1)), N'B', CAST(1.614500 AS Decimal(18, 6)), CAST(0x00009D090083D600 AS DateTime)) INSERT [dbo].[orders] ([orderId], [tradeId], [amount], [buySell], [rate], [orderDateTime]) VALUES (32, 10, CAST(1.0 AS Decimal(18, 1)), N'S', CAST(1.619500 AS Decimal(18, 6)), CAST(0x00009D090107AC00 AS DateTime)) INSERT [dbo].[orders] ([orderId], [tradeId], [amount], [buySell], [rate], [orderDateTime]) VALUES (33, 10, CAST(1.0 AS Decimal(18, 1)), N'S', CAST(1.624500 AS Decimal(18, 6)), CAST(0x00009D0901499700 AS DateTime)) INSERT [dbo].[orders] ([orderId], [tradeId], [amount], [buySell], [rate], [orderDateTime]) VALUES (34, 10, CAST(1.0 AS Decimal(18, 1)), N'S', CAST(1.619000 AS Decimal(18, 6)), CAST(0x00009D0A0083D600 AS DateTime)) SET IDENTITY_INSERT [dbo].[orders] OFF /****** Object: ForeignKey [FK_orders_trades] Script Date: 04/02/2010 15:05:31 ******/ ALTER TABLE [dbo].[orders] WITH CHECK ADD CONSTRAINT [FK_orders_trades] FOREIGN KEY([tradeId]) REFERENCES [dbo].[trades] ([tradeId]) GO ALTER TABLE [dbo].[orders] CHECK CONSTRAINT [FK_orders_trades] GO Thanks in advance for any help!

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Can rel="next" and rel="prev" can be ignored in blog listings

- by Saahil Sinha

We have a blog - which is current spread to 9 pages, every page has a unique title - page 1, page 2, page 3 and so on. Also, as it's a blog, every page has unique 10 listing entry on one page. Is rel="prev" and rel="next" can be safely ignored as all these are listing and not content pages of article. What I read in all through Google Search is that rel="next" and rel="prev" should be applicable on where the content is spread across multiple pages. But - as it's a blog, it has blog listings and every listing has unique content This is the blog: http://www.mycarhelpline.com/index.php?option=com_easyblog&view=latest&Itemid=91. May recommend, if by ignoring rel="next" and rel="prev" - are we inviting Google to treat the blog listing pages as duplicate.

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NoSQL with RavenDB and ASP.NET MVC - Part 1

- by shiju

A while back, I have blogged NoSQL with MongoDB, NoRM and ASP.NET MVC Part 1 and Part 2 on how to use MongoDB with an ASP.NET MVC application. The NoSQL movement is getting big attention and RavenDB is the latest addition to the NoSQL and document database world. RavenDB is an Open Source (with a commercial option) document database for the .NET/Windows platform developed by Ayende Rahien. Raven stores schema-less JSON documents, allow you to define indexes using Linq queries and focus on low latency and high performance. RavenDB is .NET focused document database which comes with a fully functional .NET client API and supports LINQ. RavenDB comes with two components, a server and a client API. RavenDB is a REST based system, so you can write your own HTTP cleint API. As a .NET developer, RavenDB is becoming my favorite document database. Unlike other document databases, RavenDB is supports transactions using System.Transactions. Also it's supports both embedded and server mode of database. You can access RavenDB site at http://ravendb.netA demo App with ASP.NET MVCLet's create a simple demo app with RavenDB and ASP.NET MVC. To work with RavenDB, do the following steps. Go to http://ravendb.net/download and download the latest build.Unzip the downloaded file.Go to the /Server directory and run the RavenDB.exe. This will start the RavenDB server listening on localhost:8080You can change the port of RavenDB by modifying the "Raven/Port" appSetting value in the RavenDB.exe.config file.When running the RavenDB, it will automatically create a database in the /Data directory. You can change the directory name data by modifying "Raven/DataDirt" appSetting value in the RavenDB.exe.config file.RavenDB provides a browser based admin tool. When the Raven server is running, You can be access the browser based admin tool and view and edit documents and index using your browser admin tool. The web admin tool available at http://localhost:8080The below is the some screen shots of web admin tool Working with ASP.NET MVC To working with RavenDB in our demo ASP.NET MVC application, do the following steps Step 1 - Add reference to Raven Cleint API In our ASP.NET MVC application, Add a reference to the Raven.Client.Lightweight.dll from the Client directory. Step 2 - Create DocumentStoreThe document store would be created once per application. Let's create a DocumentStore on application start-up in the Global.asax.cs. documentStore = new DocumentStore { Url = "http://localhost:8080/" }; documentStore.Initialise(); The above code will create a Raven DB document store and will be listening the server locahost at port 8080 Step 3 - Create DocumentSession on BeginRequest Let's create a DocumentSession on BeginRequest event in the Global.asax.cs. We are using the document session for every unit of work. In our demo app, every HTTP request would be a single Unit of Work (UoW). BeginRequest += (sender, args) => HttpContext.Current.Items[RavenSessionKey] = documentStore.OpenSession(); Step 4 - Destroy the DocumentSession on EndRequest EndRequest += (o, eventArgs) => { var disposable = HttpContext.Current.Items[RavenSessionKey] as IDisposable; if (disposable != null) disposable.Dispose(); }; At the end of HTTP request, we are destroying the DocumentSession object.The below code block shown all the code in the Global.asax.cs private const string RavenSessionKey = "RavenMVC.Session"; private static DocumentStore documentStore; protected void Application_Start() { //Create a DocumentStore in Application_Start //DocumentStore should be created once per application and stored as a singleton. documentStore = new DocumentStore { Url = "http://localhost:8080/" }; documentStore.Initialise(); AreaRegistration.RegisterAllAreas(); RegisterRoutes(RouteTable.Routes); //DI using Unity 2.0 ConfigureUnity(); } public MvcApplication() { //Create a DocumentSession on BeginRequest //create a document session for every unit of work BeginRequest += (sender, args) => HttpContext.Current.Items[RavenSessionKey] = documentStore.OpenSession(); //Destroy the DocumentSession on EndRequest EndRequest += (o, eventArgs) => { var disposable = HttpContext.Current.Items[RavenSessionKey] as IDisposable; if (disposable != null) disposable.Dispose(); }; } //Getting the current DocumentSession public static IDocumentSession CurrentSession { get { return (IDocumentSession)HttpContext.Current.Items[RavenSessionKey]; } } We have setup all necessary code in the Global.asax.cs for working with RavenDB. For our demo app, Let’s write a domain class public class Category { public string Id { get; set; } [Required(ErrorMessage = "Name Required")] [StringLength(25, ErrorMessage = "Must be less than 25 characters")] public string Name { get; set;} public string Description { get; set; } } We have created simple domain entity Category. Let's create repository class for performing CRUD operations against our domain entity Category. public interface ICategoryRepository { Category Load(string id); IEnumerable<Category> GetCategories(); void Save(Category category); void Delete(string id); } public class CategoryRepository : ICategoryRepository { private IDocumentSession session; public CategoryRepository() { session = MvcApplication.CurrentSession; } //Load category based on Id public Category Load(string id) { return session.Load<Category>(id); } //Get all categories public IEnumerable<Category> GetCategories() { var categories= session.LuceneQuery<Category>() .WaitForNonStaleResults() .ToArray(); return categories; } //Insert/Update category public void Save(Category category) { if (string.IsNullOrEmpty(category.Id)) { //insert new record session.Store(category); } else { //edit record var categoryToEdit = Load(category.Id); categoryToEdit.Name = category.Name; categoryToEdit.Description = category.Description; } //save the document session session.SaveChanges(); } //delete a category public void Delete(string id) { var category = Load(id); session.Delete<Category>(category); session.SaveChanges(); } } For every CRUD operations, we are taking the current document session object from HttpContext object. session = MvcApplication.CurrentSession; We are calling the static method CurrentSession from the Global.asax.cs public static IDocumentSession CurrentSession { get { return (IDocumentSession)HttpContext.Current.Items[RavenSessionKey]; } } Retrieve Entities The Load method get the single Category object based on the Id. RavenDB is working based on the REST principles and the Id would be like categories/1. The Id would be created by automatically when a new object is inserted to the document store. The REST uri categories/1 represents a single category object with Id representation of 1. public Category Load(string id) { return session.Load<Category>(id); } The GetCategories method returns all the categories calling the session.LuceneQuery method. RavenDB is using a lucen query syntax for querying. I will explain more details about querying and indexing in my future posts. public IEnumerable<Category> GetCategories() { var categories= session.LuceneQuery<Category>() .WaitForNonStaleResults() .ToArray(); return categories; } Insert/Update entityFor insert/Update a Category entity, we have created Save method in repository class. If the Id property of Category is null, we call Store method of Documentsession for insert a new record. For editing a existing record, we load the Category object and assign the values to the loaded Category object. The session.SaveChanges() will save the changes to document store. //Insert/Update category public void Save(Category category) { if (string.IsNullOrEmpty(category.Id)) { //insert new record session.Store(category); } else { //edit record var categoryToEdit = Load(category.Id); categoryToEdit.Name = category.Name; categoryToEdit.Description = category.Description; } //save the document session session.SaveChanges(); } Delete Entity In the Delete method, we call the document session's delete method and call the SaveChanges method to reflect changes in the document store. public void Delete(string id) { var category = Load(id); session.Delete<Category>(category); session.SaveChanges(); } Let’s create ASP.NET MVC controller and controller actions for handling CRUD operations for the domain class Category public class CategoryController : Controller { private ICategoryRepository categoyRepository; //DI enabled constructor public CategoryController(ICategoryRepository categoyRepository) { this.categoyRepository = categoyRepository; } public ActionResult Index() { var categories = categoyRepository.GetCategories(); if (categories == null) return RedirectToAction("Create"); return View(categories); } [HttpGet] public ActionResult Edit(string id) { var category = categoyRepository.Load(id); return View("Save",category); } // GET: /Category/Create [HttpGet] public ActionResult Create() { var category = new Category(); return View("Save", category); } [HttpPost] public ActionResult Save(Category category) { if (!ModelState.IsValid) { return View("Save", category); } categoyRepository.Save(category); return RedirectToAction("Index"); } [HttpPost] public ActionResult Delete(string id) { categoyRepository.Delete(id); var categories = categoyRepository.GetCategories(); return PartialView("CategoryList", categories); } } RavenDB is an awesome document database and I hope that it will be the winner in .NET space of document database world. The source code of demo application available at http://ravenmvc.codeplex.com/

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Bugzilla ./testserver.pl failing

- by SomeKittens

root@KittensTest:/var/www/Bugzilla/bugzilla-4.2.1# ./testserver.pl http://localhost/Bugzilla/bugzilla-4.2.1 TEST-OK Webserver is running under group id in $webservergroup. TEST-OK Got padlock picture. TEST-FAILED Webserver is fetching rather than executing CGI files. Check the AddHandler statement in your httpd.conf file. Well then. httpd.conf (from here[2.2.4.1.1]): <Directory /var/www/Bugzilla/bugzilla-4.2.1> AddHandler cgi-script .cgi .pl Options +Indexes +Includes +ExecCGI DirectoryIndex index.cgi AllowOverride Limit FileInfo Indexes </Directory> What am I doing wrong? I'm pretty new to this (first Bugzilla install), so I'll appreciate explanation.

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Creating a dynamic proxy generator with c# – Part 3 – Creating the constructors

- by SeanMcAlinden

Creating a dynamic proxy generator with c# – Part 1 – Creating the Assembly builder, Module builder and caching mechanism Creating a dynamic proxy generator with c# – Part 2 – Interceptor Design For the latest code go to http://rapidioc.codeplex.com/ When building our proxy type, the first thing we need to do is build the constructors. There needs to be a corresponding constructor for each constructor on the passed in base type. We also want to create a field to store the interceptors and construct this list within each constructor. So assuming the passed in base type is a User<int, IRepository> class, were looking to generate constructor code like the following: Default Constructor public User`2_RapidDynamicBaseProxy() { this.interceptors = new List<IInterceptor<User<int, IRepository>>>(); DefaultInterceptor<User<int, IRepository>> item = new DefaultInterceptor<User<int, IRepository>>(); this.interceptors.Add(item); } Parameterised Constructor public User`2_RapidDynamicBaseProxy(IRepository repository1) : base(repository1) { this.interceptors = new List<IInterceptor<User<int, IRepository>>>(); DefaultInterceptor<User<int, IRepository>> item = new DefaultInterceptor<User<int, IRepository>>(); this.interceptors.Add(item); } As you can see, we first populate a field on the class with a new list of the passed in base type. Construct our DefaultInterceptor class. Add the DefaultInterceptor instance to our interceptor collection. Although this seems like a relatively small task, there is a fair amount of work require to get this going. Instead of going through every line of code – please download the latest from http://rapidioc.codeplex.com/ and debug through. In this post I’m going to concentrate on explaining how it works. TypeBuilder The TypeBuilder class is the main class used to create the type. You instantiate a new TypeBuilder using the assembly module we created in part 1. /// <summary> /// Creates a type builder. /// </summary> /// <typeparam name="TBase">The type of the base class to be proxied.</typeparam> public static TypeBuilder CreateTypeBuilder<TBase>() where TBase : class { TypeBuilder typeBuilder = DynamicModuleCache.Get.DefineType ( CreateTypeName<TBase>(), TypeAttributes.Class | TypeAttributes.Public, typeof(TBase), new Type[] { typeof(IProxy) } ); if (typeof(TBase).IsGenericType) { GenericsHelper.MakeGenericType(typeof(TBase), typeBuilder); } return typeBuilder; } private static string CreateTypeName<TBase>() where TBase : class { return string.Format("{0}_RapidDynamicBaseProxy", typeof(TBase).Name); } As you can see, I’ve create a new public class derived from TBase which also implements my IProxy interface, this is used later for adding interceptors. If the base type is generic, the following GenericsHelper.MakeGenericType method is called. GenericsHelper using System; using System.Reflection.Emit; namespace Rapid.DynamicProxy.Types.Helpers { /// <summary> /// Helper class for generic types and methods. /// </summary> internal static class GenericsHelper { /// <summary> /// Makes the typeBuilder a generic. /// </summary> /// <param name="concrete">The concrete.</param> /// <param name="typeBuilder">The type builder.</param> public static void MakeGenericType(Type baseType, TypeBuilder typeBuilder) { Type[] genericArguments = baseType.GetGenericArguments(); string[] genericArgumentNames = GetArgumentNames(genericArguments); GenericTypeParameterBuilder[] genericTypeParameterBuilder = typeBuilder.DefineGenericParameters(genericArgumentNames); typeBuilder.MakeGenericType(genericTypeParameterBuilder); } /// <summary> /// Gets the argument names from an array of generic argument types. /// </summary> /// <param name="genericArguments">The generic arguments.</param> public static string[] GetArgumentNames(Type[] genericArguments) { string[] genericArgumentNames = new string[genericArguments.Length]; for (int i = 0; i < genericArguments.Length; i++) { genericArgumentNames[i] = genericArguments[i].Name; } return genericArgumentNames; } } } As you can see, I’m getting all of the generic argument types and names, creating a GenericTypeParameterBuilder and then using the typeBuilder to make the new type generic. InterceptorsField The interceptors field will store a List<IInterceptor<TBase>>. Fields are simple made using the FieldBuilder class. The following code demonstrates how to create the interceptor field. FieldBuilder interceptorsField = typeBuilder.DefineField( "interceptors", typeof(System.Collections.Generic.List<>).MakeGenericType(typeof(IInterceptor<TBase>)), FieldAttributes.Private ); The field will now exist with the new Type although it currently has no data – we’ll deal with this in the constructor. Add method for interceptorsField To enable us to add to the interceptorsField list, we are going to utilise the Add method that already exists within the System.Collections.Generic.List class. We still however have to create the methodInfo necessary to call the add method. This can be done similar to the following: Add Interceptor Field MethodInfo addInterceptor = typeof(List<>) .MakeGenericType(new Type[] { typeof(IInterceptor<>).MakeGenericType(typeof(TBase)) }) .GetMethod ( "Add", BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic, null, new Type[] { typeof(IInterceptor<>).MakeGenericType(typeof(TBase)) }, null ); So we’ve create a List<IInterceptor<TBase>> type, then using the type created a method info called Add which accepts an IInterceptor<TBase>. Now in our constructor we can use this to call this.interceptors.Add(// interceptor); Building the Constructors This will be the first hard-core part of the proxy building process so I’m going to show the class and then try to explain what everything is doing. For a clear view, download the source from http://rapidioc.codeplex.com/, go to the test project and debug through the constructor building section. Anyway, here it is: DynamicConstructorBuilder using System; using System.Collections.Generic; using System.Reflection; using System.Reflection.Emit; using Rapid.DynamicProxy.Interception; using Rapid.DynamicProxy.Types.Helpers; namespace Rapid.DynamicProxy.Types.Constructors { /// <summary> /// Class for creating the proxy constructors. /// </summary> internal static class DynamicConstructorBuilder { /// <summary> /// Builds the constructors. /// </summary> /// <typeparam name="TBase">The base type.</typeparam> /// <param name="typeBuilder">The type builder.</param> /// <param name="interceptorsField">The interceptors field.</param> public static void BuildConstructors<TBase> ( TypeBuilder typeBuilder, FieldBuilder interceptorsField, MethodInfo addInterceptor ) where TBase : class { ConstructorInfo interceptorsFieldConstructor = CreateInterceptorsFieldConstructor<TBase>(); ConstructorInfo defaultInterceptorConstructor = CreateDefaultInterceptorConstructor<TBase>(); ConstructorInfo[] constructors = typeof(TBase).GetConstructors(); foreach (ConstructorInfo constructorInfo in constructors) { CreateConstructor<TBase> ( typeBuilder, interceptorsField, interceptorsFieldConstructor, defaultInterceptorConstructor, addInterceptor, constructorInfo ); } } #region Private Methods private static void CreateConstructor<TBase> ( TypeBuilder typeBuilder, FieldBuilder interceptorsField, ConstructorInfo interceptorsFieldConstructor, ConstructorInfo defaultInterceptorConstructor, MethodInfo AddDefaultInterceptor, ConstructorInfo constructorInfo ) where TBase : class { Type[] parameterTypes = GetParameterTypes(constructorInfo); ConstructorBuilder constructorBuilder = CreateConstructorBuilder(typeBuilder, parameterTypes); ILGenerator cIL = constructorBuilder.GetILGenerator(); LocalBuilder defaultInterceptorMethodVariable = cIL.DeclareLocal(typeof(DefaultInterceptor<>).MakeGenericType(typeof(TBase))); ConstructInterceptorsField(interceptorsField, interceptorsFieldConstructor, cIL); ConstructDefaultInterceptor(defaultInterceptorConstructor, cIL, defaultInterceptorMethodVariable); AddDefaultInterceptorToInterceptorsList ( interceptorsField, AddDefaultInterceptor, cIL, defaultInterceptorMethodVariable ); CreateConstructor(constructorInfo, parameterTypes, cIL); } private static void CreateConstructor(ConstructorInfo constructorInfo, Type[] parameterTypes, ILGenerator cIL) { cIL.Emit(OpCodes.Ldarg_0); if (parameterTypes.Length > 0) { LoadParameterTypes(parameterTypes, cIL); } cIL.Emit(OpCodes.Call, constructorInfo); cIL.Emit(OpCodes.Ret); } private static void LoadParameterTypes(Type[] parameterTypes, ILGenerator cIL) { for (int i = 1; i <= parameterTypes.Length; i++) { cIL.Emit(OpCodes.Ldarg_S, i); } } private static void AddDefaultInterceptorToInterceptorsList ( FieldBuilder interceptorsField, MethodInfo AddDefaultInterceptor, ILGenerator cIL, LocalBuilder defaultInterceptorMethodVariable ) { cIL.Emit(OpCodes.Ldarg_0); cIL.Emit(OpCodes.Ldfld, interceptorsField); cIL.Emit(OpCodes.Ldloc, defaultInterceptorMethodVariable); cIL.Emit(OpCodes.Callvirt, AddDefaultInterceptor); } private static void ConstructDefaultInterceptor ( ConstructorInfo defaultInterceptorConstructor, ILGenerator cIL, LocalBuilder defaultInterceptorMethodVariable ) { cIL.Emit(OpCodes.Newobj, defaultInterceptorConstructor); cIL.Emit(OpCodes.Stloc, defaultInterceptorMethodVariable); } private static void ConstructInterceptorsField ( FieldBuilder interceptorsField, ConstructorInfo interceptorsFieldConstructor, ILGenerator cIL ) { cIL.Emit(OpCodes.Ldarg_0); cIL.Emit(OpCodes.Newobj, interceptorsFieldConstructor); cIL.Emit(OpCodes.Stfld, interceptorsField); } private static ConstructorBuilder CreateConstructorBuilder(TypeBuilder typeBuilder, Type[] parameterTypes) { return typeBuilder.DefineConstructor ( MethodAttributes.Public | MethodAttributes.SpecialName | MethodAttributes.RTSpecialName | MethodAttributes.HideBySig, CallingConventions.Standard, parameterTypes ); } private static Type[] GetParameterTypes(ConstructorInfo constructorInfo) { ParameterInfo[] parameterInfoArray = constructorInfo.GetParameters(); Type[] parameterTypes = new Type[parameterInfoArray.Length]; for (int p = 0; p < parameterInfoArray.Length; p++) { parameterTypes[p] = parameterInfoArray[p].ParameterType; } return parameterTypes; } private static ConstructorInfo CreateInterceptorsFieldConstructor<TBase>() where TBase : class { return ConstructorHelper.CreateGenericConstructorInfo ( typeof(List<>), new Type[] { typeof(IInterceptor<TBase>) }, BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic ); } private static ConstructorInfo CreateDefaultInterceptorConstructor<TBase>() where TBase : class { return ConstructorHelper.CreateGenericConstructorInfo ( typeof(DefaultInterceptor<>), new Type[] { typeof(TBase) }, BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic ); } #endregion } } So, the first two tasks within the class should be fairly clear, we are creating a ConstructorInfo for the interceptorField list and a ConstructorInfo for the DefaultConstructor, this is for instantiating them in each contructor. We then using Reflection get an array of all of the constructors in the base class, we then loop through the array and create a corresponding proxy contructor. Hopefully, the code is fairly easy to follow other than some new types and the dreaded Opcodes. ConstructorBuilder This class defines a new constructor on the type. ILGenerator The ILGenerator allows the use of Reflection.Emit to create the method body. LocalBuilder The local builder allows the storage of data in local variables within a method, in this case it’s the constructed DefaultInterceptor. Constructing the interceptors field The first bit of IL you’ll come across as you follow through the code is the following private method used for constructing the field list of interceptors. private static void ConstructInterceptorsField ( FieldBuilder interceptorsField, ConstructorInfo interceptorsFieldConstructor, ILGenerator cIL ) { cIL.Emit(OpCodes.Ldarg_0); cIL.Emit(OpCodes.Newobj, interceptorsFieldConstructor); cIL.Emit(OpCodes.Stfld, interceptorsField); } The first thing to know about generating code using IL is that you are using a stack, if you want to use something, you need to push it up the stack etc. etc. OpCodes.ldArg_0 This opcode is a really interesting one, basically each method has a hidden first argument of the containing class instance (apart from static classes), constructors are no different. This is the reason you can use syntax like this.myField. So back to the method, as we want to instantiate the List in the interceptorsField, first we need to load the class instance onto the stack, we then load the new object (new List<TBase>) and finally we store it in the interceptorsField. Hopefully, that should follow easily enough in the method. In each constructor you would now have this.interceptors = new List<User<int, IRepository>>(); Constructing and storing the DefaultInterceptor The next bit of code we need to create is the constructed DefaultInterceptor. Firstly, we create a local builder to store the constructed type. Create a local builder LocalBuilder defaultInterceptorMethodVariable = cIL.DeclareLocal(typeof(DefaultInterceptor<>).MakeGenericType(typeof(TBase))); Once our local builder is ready, we then need to construct the DefaultInterceptor<TBase> and store it in the variable. Connstruct DefaultInterceptor private static void ConstructDefaultInterceptor ( ConstructorInfo defaultInterceptorConstructor, ILGenerator cIL, LocalBuilder defaultInterceptorMethodVariable ) { cIL.Emit(OpCodes.Newobj, defaultInterceptorConstructor); cIL.Emit(OpCodes.Stloc, defaultInterceptorMethodVariable); } As you can see, using the ConstructorInfo named defaultInterceptorConstructor, we load the new object onto the stack. Then using the store local opcode (OpCodes.Stloc), we store the new object in the local builder named defaultInterceptorMethodVariable. Add the constructed DefaultInterceptor to the interceptors field collection Using the add method created earlier in this post, we are going to add the new DefaultInterceptor object to the interceptors field collection. Add Default Interceptor private static void AddDefaultInterceptorToInterceptorsList ( FieldBuilder interceptorsField, MethodInfo AddDefaultInterceptor, ILGenerator cIL, LocalBuilder defaultInterceptorMethodVariable ) { cIL.Emit(OpCodes.Ldarg_0); cIL.Emit(OpCodes.Ldfld, interceptorsField); cIL.Emit(OpCodes.Ldloc, defaultInterceptorMethodVariable); cIL.Emit(OpCodes.Callvirt, AddDefaultInterceptor); } So, here’s whats going on. The class instance is first loaded onto the stack using the load argument at index 0 opcode (OpCodes.Ldarg_0) (remember the first arg is the hidden class instance). The interceptorsField is then loaded onto the stack using the load field opcode (OpCodes.Ldfld). We then load the DefaultInterceptor object we stored locally using the load local opcode (OpCodes.Ldloc). Then finally we call the AddDefaultInterceptor method using the call virtual opcode (Opcodes.Callvirt). Completing the constructor The last thing we need to do is complete the constructor. Complete the constructor private static void CreateConstructor(ConstructorInfo constructorInfo, Type[] parameterTypes, ILGenerator cIL) { cIL.Emit(OpCodes.Ldarg_0); if (parameterTypes.Length > 0) { LoadParameterTypes(parameterTypes, cIL); } cIL.Emit(OpCodes.Call, constructorInfo); cIL.Emit(OpCodes.Ret); } private static void LoadParameterTypes(Type[] parameterTypes, ILGenerator cIL) { for (int i = 1; i <= parameterTypes.Length; i++) { cIL.Emit(OpCodes.Ldarg_S, i); } } So, the first thing we do again is load the class instance using the load argument at index 0 opcode (OpCodes.Ldarg_0). We then load each parameter using OpCode.Ldarg_S, this opcode allows us to specify an index position for each argument. We then setup calling the base constructor using OpCodes.Call and the base constructors ConstructorInfo. Finally, all methods are required to return, even when they have a void return. As there are no values on the stack after the OpCodes.Call line, we can safely call the OpCode.Ret to give the constructor a void return. If there was a value, we would have to pop the value of the stack before calling return otherwise, the method would try and return a value. Conclusion This was a slightly hardcore post but hopefully it hasn’t been too hard to follow. The main thing is that a number of the really useful opcodes have been used and now the dynamic proxy is capable of being constructed. If you download the code and debug through the tests at http://rapidioc.codeplex.com/, you’ll be able to create proxies at this point, they cannon do anything in terms of interception but you can happily run the tests, call base methods and properties and also take a look at the created assembly in Reflector. Hope this is useful. The next post should be up soon, it will be covering creating the private methods for calling the base class methods and properties. Kind Regards, Sean.

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Creating an ASP.NET report using Visual Studio 2010 - Part 3

- by rajbk

We continue building our report in this three part series. Creating an ASP.NET report using Visual Studio 2010 - Part 1 Creating an ASP.NET report using Visual Studio 2010 - Part 2 Adding the ReportViewer control and filter drop downs. Open the source code for index.aspx and add a ScriptManager control. This control is required for the ReportViewer control. Add a DropDownList for the categories and suppliers. Add the ReportViewer control. The markup after these steps is shown below. <div> <asp:ScriptManager ID="smScriptManager" runat="server"> </asp:ScriptManager> <div id="searchFilter"> Filter by: Category : <asp:DropDownList ID="ddlCategories" runat="server" /> and Supplier : <asp:DropDownList ID="ddlSuppliers" runat="server" /> </div> <rsweb:ReportViewer ID="rvProducts" runat="server"> </rsweb:ReportViewer> </div> The design view for index.aspx is shown below. The dropdowns will display the categories and suppliers in the database. Changing the selection in the drop downs will cause the report to be filtered by the selections in the dropdowns. You will see how to do this in the next steps. Attaching the RDLC to the ReportViewer control by clicking on the top right of the control, going to Report Viewer tasks and selecting Products.rdlc. Resize the ReportViewer control by dragging at the bottom right corner. I set mine to 800px x 500px. You can also set this value in source view. Defining the data sources. We will now define the Data Source used to populate the report. Go back to the “ReportViewer Tasks” and select “Choose Data Sources” Select a “New data source..” Select “Object” and name your Data Source ID “odsProducts” In the next screen, choose “ProductRepository” as your business object. Choose “GetProductsProjected” in the next screen. The method requires a SupplierID and CategoryID. We will set these so that our data source gets the values from the drop down lists we defined earlier. Set the parameter source to be of type “Control” and set the ControlIDs to be ddlSuppliers and ddlCategories respectively. Your screen will look like this: We are now going to define the data source for our drop downs. Select the ddlCategory drop down and pick “Choose Data Source”. Pick “Object” and give it an id “odsCategories” In the next screen, choose “ProductRepository” Select the GetCategories() method in the next screen. Select “CategoryName” and “CategoryID” in the next screen. We are done defining the data source for the Category drop down. Perform the same steps for the Suppliers drop down. Select each dropdown and set the AppendDataBoundItems to true and AutoPostback to true. The AppendDataBoundItems is needed because we are going to insert an “All“ list item with a value of empty. Go to each drop down and add this list item markup as shown below> Finally, double click on each drop down in the designer and add the following code in the code behind. This along with the “Autopostback= true” attribute refreshes the report anytime a drop down is changed. protected void ddlCategories_SelectedIndexChanged(object sender, EventArgs e) { rvProducts.LocalReport.Refresh(); } protected void ddlSuppliers_SelectedIndexChanged(object sender, EventArgs e) { rvProducts.LocalReport.Refresh(); } Compile your report and run the page. You should see the report rendered. Note that the tool bar in the ReportViewer control gives you a couple of options including the ability to export the data to Excel, PDF or word. Conclusion Through this three part series, we did the following: Created a data layer for use by our RDLC. Created an RDLC using the report wizard and define a dataset for the report. Used the report design surface to design our report including adding a chart. Used the ReportViewer control to attach the RDLC. Connected our ReportWiewer to a data source and take parameter values from the drop downlists. Used AutoPostBack to refresh the reports when the dropdown selection was changed. RDLCs allow you to create interactive reports including drill downs and grouping. For even more advanced reports you can use Microsoft® SQL Server™ Reporting Services with RDLs. With RDLs, the report is rendered on the report server instead of the web server. Another nice thing about RDLs is that you can define a parameter list for the report and it gets rendered automatically for you. RDLCs and RDLs both have their advantages and its best to compare them and choose the right one for your requirements. Download VS2010 RTM Sample project NorthwindReports.zip Alfred Borden: Are you watching closely?

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Screencasts introducing C++ AMP

- by Daniel Moth

It has been almost 2.5 years since I last recorded a screencast, and I had forgotten how time consuming they are to plan/record/edit/produce/publish, but at the same time so much fun to see the end result! So below are links to 4 screencasts to teach you C++ AMP basics from scratch (even if you class yourself as a .NET developer you'll be able to follow). Setup code - part 1 array_view, extent, index - part 2 parallel_for_each - part 3 accelerator - part 4 If you have comments/questions about what is shown in each video, please leave them at each video recoding. If you have generic questions about C++ AMP, please ask in the C++ AMP MSDN forum. Comments about this post by Daniel Moth welcome at the original blog.

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Render MVCContrib Grid with No Header Row

- by Ben Griswold

The MVCContrib Grid allows for the easy construction of HTML tables for displaying data from a collection of Model objects. I add this component to all of my ASP.NET MVC projects. If you aren’t familiar with what the grid has to offer, it’s worth the looking into. What you may notice in the busy example below is the fact that I render my column headers independent of the grid contents. This allows me to keep my headers fixed while the user searches through the table content which is displayed in a scrollable div*. Thus, I needed a way to render my grid without headers. That’s where Grid Renderers come into play. <table border="0" cellspacing="0" cellpadding="0" class="projectHeaderTable"> <tr> <td class="memberTableMemberHeader"> <%= Html.GridColumnHeader("Member", "Index", "MemberFullName")%> </td> <td class="memberTableRoleHeader"> <%= Html.GridColumnHeader("Role", "Index", "ProjectRoleTypeName")%> </td> <td class="memberTableActionHeader"> Action </td> </tr> </table> <div class="scrollContentWrapper"> <% Html.Grid(Model) .Columns(column => { column.For(c => c.MemberFullName).Attributes(@class => "memberTableMemberCol"); column.For(c => c.ProjectRoleTypeName).Attributes(@class => "memberTableRoleCol"); column.For(x => Html.ActionLink("View", "Details", new { Id = x.ProjectMemberId }) + " | " + Html.ActionLink("Edit", "Edit", new { Id = x.ProjectMemberId }) + " | " + Html.ActionLink("Remove", "Delete", new { Id = x.ProjectMemberId })) .Attributes(@class => "memberTableActionCol").DoNotEncode(); }) .Empty("There are no members associated with this project.") .Attributes(@class => "lbContent") .RenderUsing(new GridNoHeaderRenderer<ProjectMemberDetailsViewModel>()) .Render(); %> </div> <div class="scrollContentBottom"> <!– –> </div> <%=Html.Pager(Model) %> Maybe you noticed the reference to the GridNoHeaderRenderer class above? Yep, rendering the grid with no header is straightforward. public class GridNoHeaderRenderer<T> : HtmlTableGridRenderer<T> where T: class { protected override bool RenderHeader() { // Explicitly returning true would suppress the header // just fine, however, Render() will always assume that // items exist in collection and RenderEmpty() will // never be called. // In other words, return ShouldRenderHeader() if you // want to maintain the Empty text when no items exist. return ShouldRenderHeader(); } } Well, if you read through the comments, there is one catch. You might be tempted to have the RenderHeader method always return true. This would work just fine but you should return the result of ShouldRenderHeader() instead so the Empty text will continue to display if there are no items in the collection. The GridRenderer feature found in the MVCContrib Grid is so well put together, I just had to share. * Though you can find countless alternatives to the fixed headers problem online, this is the only solution that I’ve ever found to reliably work across browsers. If you know something I don’t, please share.

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Modify “Link”/ "HyperLink"/URL field using Powershell

- by KunaalKapoor

If you are trying to update a hyperlink/url type of column of a SharePoint list item using PowerShell and are getting the exception:Unable to index into an object of type Microsoft.SharePoint.SPListItem.At C:\mypowershell.ps1:39 char:10+ $item[ <<<< "Website"] = $itemUrl + CategoryInfo : InvalidOperation: (RW_Website:String) [], RuntimeException + FullyQualifiedErrorId : CannotIndexThen look no further :)The url is basically stored like a simple string with url, description divided by comma.So all you need to do is:$myUrl = "http://www.google.com, Google"$listitem["Link"] = $myUrlThat will, assuming "Link" is a type of "Hyperlink or Picture" (Hyperlink), create a link that says Google and links to http://www.google.com.Also make sure you don't miss out on the 'http://' part as without that the value will not pass the SharePoint validation of allowed values.

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ViewBag dynamic in ASP.NET MVC 3 - RC 2

- by hajan

Earlier today Scott Guthrie announced the ASP.NET MVC 3 - Release Candidate 2. I installed the new version right after the announcement since I was eager to see the new features. Among other cool features included in this release candidate, there is a new ViewBag dynamic which can be used to pass data from Controllers to Views same as you use ViewData[] dictionary. What is great and nice about ViewBag (despite the name) is that its a dynamic type which means you can dynamically get/set values and add any number of additional fields without need of strongly-typed classes. In order to see the difference, please take a look at the following examples. Example - Using ViewData Controller public ActionResult Index() { List<string> colors = new List<string>(); colors.Add("red"); colors.Add("green"); colors.Add("blue"); ViewData["listColors"] = colors; ViewData["dateNow"] = DateTime.Now; ViewData["name"] = "Hajan"; ViewData["age"] = 25; return View(); } View (ASPX View Engine) <p> My name is <b><%: ViewData["name"] %></b>, <b><%: ViewData["age"] %></b> years old. <br /> I like the following colors: </p> <ul id="colors"> <% foreach (var color in ViewData["listColors"] as List<string>){ %> <li> <font color="<%: color %>"><%: color %></font> </li> <% } %> </ul> <p> <%: ViewData["dateNow"] %> </p> (I know the code might look cleaner with Razor View engine, but it doesn’t matter right? ;) ) Example - Using ViewBag Controller public ActionResult Index() { List<string> colors = new List<string>(); colors.Add("red"); colors.Add("green"); colors.Add("blue"); ViewBag.ListColors = colors; //colors is List ViewBag.DateNow = DateTime.Now; ViewBag.Name = "Hajan"; ViewBag.Age = 25; return View(); } You see the difference? View (ASPX View Engine) <p> My name is <b><%: ViewBag.Name %></b>, <b><%: ViewBag.Age %></b> years old. <br /> I like the following colors: </p> <ul id="colors"> <% foreach (var color in ViewBag.ListColors) { %> <li> <font color="<%: color %>"><%: color %></font> </li> <% } %> </ul> <p> <%: ViewBag.DateNow %> </p> In my example now I don’t need to cast ViewBag.ListColors as List<string> since ViewBag is dynamic type! On the other hand the ViewData[“key”] is object.I would like to note that if you use ViewData["ListColors"] = colors; in your Controller, you can retrieve it in the View by using ViewBag.ListColors. And the result in both cases is Hope you like it! Regards, Hajan

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Nice wordpress to wordpress redirect?

- by marc.riera

Hi, I have a wordpress blog in http://suportrecerca.barcelonamedia.org/blog/ , and since I can no longer use our company servers for my blog I've had to move it to blog.joanmarcriera.es Google had my old blog well indexed and many people is landing to my old blog. I want to redirect this people to my new blog in a nice way, like a 5 seconds delay with some information or something. Any suggestions? I also would like to let google index the old blog like usual if it's possible. Thanks.

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WordPress hack might affect more than your WordPress installation!

- by Piet

Just a quick note… If you’re managing WordPress installations, and haven’t heard about the recent WordPress hacks (http://wordpress.org/support/topic/307660) yet you probably just got back from holiday. There’s plenty of advice on fixing a hacked installation if you follow some of the links in the above post, so I’m not going to recite that here. However! While cleaning a WordPress installation that resides in a subdirectory of a modx cms I found that the modx index.php files were also infected. I searched for infected files using grep as follows: grep -R 'function gpc_' * If you’re on a shared hosting environment that doesn’t allow shell access: time to change your hosting provider. (mail me if you need recommendations)

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New Tuxedo White Papers

- by todd.little

As part of the Tuxedo 11gR1 release, I've written two new white papers on Tuxedo. One is called "Tuxedo in a SOA World" and discusses how Tuxedo fits into SOA based applications. It covers most of the various connectivity options from Tuxedo into SOA environments and gives guidance as to which connectivity options are best suited for a particular application requirement. The other white paper "SCA: Bringing Modern SOA Programing to Tuxedo" is of a more technical bent and focuses on using the SCA features in SALT to easily build SOA based applications on Tuxedo without using a lot of technical APIs. In fact, services built using SALT's SCA support don't require any technical APIs, just pure business logic, and SCA clients need at most a couple of API calls, simply to look up a service. You can find these two new white papers as well as some additional white papers at http://www.oracle.com/technology/products/tuxedo/index.html.

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Error during update 'Unable to connect to 192.168.43.1:8000'

- by Alex R

When I tried to update my Ubuntu through the update manager I received an error about some unknown resource. so i tried doing it from the terminal with sudo apt-get update but all I got is: 0% [Connecting to 192.168.43.1 repeating itself... and when I press Enter it shows: W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/precise-security/universe/i18n/Translation-en Unable to connect to 192.168.43.1:8000: E: Some index files failed to download. They have been ignored, or old ones used instead. How can I get this to work?

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SEO: Moving articles from one domain to another

- by Melanie

Currently I have articles up on a website (site A) that is not mine (but I can remove the articles.) The article's aren't faring well (not only due to the recent Google changes) but because they really could do better if I made some tweaks myself instead of relying on the domain owner's SEO skills. So I would like to set up my own website and have just my articles on it (site B.) In the past when I've moved content, I've set up redirects but this time I can't do that. What would be the best way to move the articles without having to worry about them being counted as duplicate content or any other lame stuff? Should I, A: Save the articles on my computer and remove them from Site A. Wait for Google to remove them from the index (several months.) B: Remove the articles from Site A and immediately place them on Site B.

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How long would it take to learn Python?

- by Josh

Hi all I have decided to take the time out after work to learn Python. Python appeals to me because at work (Web and eLearning Company), I have to follow out very repetitive tasks like delete all these tags, rename all these tasks and even more advanced repetive tasks. Additionally it would be good for me to get an understanding of Python first because of its fairly easy to learn syntax. How long would it take to learn the basics and go through these tutorials on Python (+ the Python tutorial)? I will only be spending 1 hour or so on it in the afternoons. http://openbookproject.net/thinkcs/python/english2e/index.html I have told my piano teacher I would like to take a month of learning piano to do this would this be adequate time? After this I may choose to learn PHP, because that is mainly what we use for web development at work. Thanks Josh

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Learning resource for 3d modeling

- by Maik Klein

I want to start learning 3d modeling. I already have experience with maya and 3dsmax but I made a long pause (2 years) Now I have free access to maya, 3dsmax and blender (I am a student). I know that all tools are very powerful so I thought I just pick the one with the best learning materials. The best site that I found is http://www.digitaltutors.com/11/index.php and it has over 7600 videos for maya. Maybe you can recommend me some other learning sites that are as good as digitaltutors?

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Using Rich Text Editor (WYSIWYG) in ASP.NET MVC

- by imran_ku07

Introduction: In ASP.NET MVC forum I found some question regarding a sample HTML Rich Text Box Editor(also known as wysiwyg).So i decided to create a sample ASP.NET MVC web application which will use a Rich Text Box Editor. There are are lot of Html Editors are available, but for creating a sample application, i decided to use cross-browser WYSIWYG editor from openwebware. In this article I will discuss what changes needed to work this editor with ASP.NET MVC. Also I had attached the sample application for download at http://www.speedfile.org/155076. Also note that I will only show the important features, not discuss every feature in detail. Description: So Let's start create a sample ASP.NET MVC application. You need to add the following script files, jquery-1.3.2.min.js jquery_form.js wysiwyg.js wysiwyg-settings.js wysiwyg-popup.js Just put these files inside Scripts folder. Also put wysiwyg.css in your Content Folder and add the following folders in your project addons popups Also create a empty folder Uploads to store the uploaded images. Next open wysiwyg.js and set your configuration // Images Directory this.ImagesDir = "/addons/imagelibrary/images/"; // Popups Directory this.PopupsDir = "/popups/"; // CSS Directory File this.CSSFile = "/Content/wysiwyg.css"; Next create a simple View TextEditor.aspx inside View / Home Folder and add the folllowing HTML. <%@ Page Language="C#" Inherits="System.Web.Mvc.ViewPage" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html > <head runat="server"> <title>TextEditor</title> <script src="../../Scripts/wysiwyg.js" type="text/javascript"></script> <script src="../../Scripts/wysiwyg-settings.js" type="text/javascript"></script> <script type="text/javascript"> WYSIWYG.attach('text', full); </script> </head> <body> <% using (Html.BeginForm()){ %> <textarea id="text" name="test2" style="width:850px;height:200px;"> </textarea> <input type="submit" value="submit" /> <%} %> </body> </html> Here i have just added a text area control and a submit button inside a form. Note the id of text area and WYSIWYG.attach function's first parameter is same and next to watch is the HomeController.cs using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.Mvc; using System.IO; namespace HtmlTextEditor.Controllers { [HandleError] public class HomeController : Controller { public ActionResult Index() { ViewData["Message"] = "Welcome to ASP.NET MVC!"; return View(); } public ActionResult About() { return View(); } public ActionResult TextEditor() { return View(); } [AcceptVerbs(HttpVerbs.Post)] [ValidateInput(false)] public ActionResult TextEditor(string test2) { Session["html"] = test2; return RedirectToAction("Index"); } public ActionResult UploadImage() { if (Request.Files[0].FileName != "") { Request.Files[0].SaveAs(Server.MapPath("~/Uploads/" + Path.GetFileName(Request.Files[0].FileName))); return Content(Url.Content("~/Uploads/" + Path.GetFileName(Request.Files[0].FileName))); } return Content("a"); } } } So simple code, just save the posted Html into Session. Here the parameter of TextArea action is test2 which is same as textarea control name of TextArea.aspx View. Also note ValidateInputAttribute is false, so it's up to you to defends against XSS. Also there is an Action method which simply saves the file inside Upload Folder. I am uploading the file using Jquery Form Plugin. Here is the code which is found in insert_image.html inside addons folder, function ChangeImage() { var myform=document.getElementById("formUpload"); $(myform).ajaxSubmit({success: function(responseText){ insertImage(responseText); window.close(); } }); } and here is the Index View which simply renders the html of Editor which was saved in Session <%@ Page Language="C#" MasterPageFile="~/Views/Shared/Site.Master" Inherits="System.Web.Mvc.ViewPage" %> <asp:Content ID="indexTitle" ContentPlaceHolderID="TitleContent" runat="server"> Home Page </asp:Content> <asp:Content ID="indexContent" ContentPlaceHolderID="MainContent" runat="server"> <h2><%= Html.Encode(ViewData["Message"]) %></h2> <p> To learn more about ASP.NET MVC visit <a href="http://asp.net/mvc" title="ASP.NET MVC Website">http://asp.net/mvc</a>. </p> <%if (Session["html"] != null){ Response.Write(Session["html"].ToString()); } %> </asp:Content> Summary: Hopefully you will enjoy this article. Just download the code and see the effect. From security point, you must handle the XSS attack your self. I had uploaded the sample application in http://www.speedfile.org/155076

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Connecting to Magento Web Services with Java

- by kerry

I was in the unenviable position of needing to connect to Magento, a PHP ecommerce platform, web services using Java. It was kind of difficult to get the classes generated from the WSDL so I figured I would throw the results up on my github account for any other poor sap in a similar position. First, pull down the project using git: git clone git://github.com/webdevwilson/magento-java.git and build it with maven: mvn install Here is a quick example of how to pull an order using the generated classes: MagentoServiceLocator serviceLocator = new MagentoServiceLocator(); String url = "http://domain.com/index.php/api/v2_soap"; Mage_Api_Model_Server_V2_HandlerPortType port = serviceLocator.getMage_Api_Model_Server_V2_HandlerPort(url); String sessionId = port.login("username", "key"); SalesOrderEntity salesOrder = port.salesOrderInfo(sessionId, orderId); I also have some wrapper code in there that makes it a little easier to call the API. Checkout the project at https://github.com/webdevwilson/magento-java There is another option. it’s called Magja and it is located at google code.

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php fopen => 500 Internal Server Error

- by Ahmed B

I have a website hosted on a dedicated server, I noticed that Google and other search engines can't access to the most URLs on my website!! On my localhost I have made a small test : var_dump(fopen('http://www.aswat.ma', 'r')); And I got this error : Warning: fopen(http://www.aswat.ma) [function.fopen]: failed to open stream: HTTP request failed! HTTP/1.1 500 Internal Server Error in C:\xampp\htdocs\pnowate\public\index.php on line 4 bool(false) If I change the URL "http://www.aswat.ma" by "www.google.co.ma" I got this : resource(3) of type (stream) Any one have any idea about this issue ??

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Issues installing synapse launcher

- by George Morton

I am trying to install synapse launcher on my desktop . I am using these two commands: sudo add-apt-repository ppa:synapse-core/ppa sudo apt-get update && sudo apt-get install synapse However I am getting an error with the second command saying E: Some index files failed to download, they have been ignored, or old ones used instead. I presume this has something to do with my connection to the hosting servers. But what I don't understand is the fact that synaptic is working it just seems to be something about that ppa. I don't know what I am doing wrong as the commands are widely suggested around the web, But they don't seem to work for me! I would greatly appreciate some advice on this as it is proving to be very frustrating. Many thanks, George

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Project Euler 10: (Iron)Python

- by Ben Griswold

In my attempt to learn (Iron)Python out in the open, here’s my solution for Project Euler Problem 10. As always, any feedback is welcome. # Euler 10 # http://projecteuler.net/index.php?section=problems&id=10 # The sum of the primes below 10 is 2 + 3 + 5 + 7 = 17. # Find the sum of all the primes below two million. import time start = time.time() def primes_to_max(max): primes, number = [2], 3 while number < max: isPrime = True for prime in primes: if number % prime == 0: isPrime = False break if (prime * prime > number): break if isPrime: primes.append(number) number += 2 return primes primes = primes_to_max(2000000) print sum(primes) print "Elapsed Time:", (time.time() - start) * 1000, "millisecs" a=raw_input('Press return to continue')

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Oracle Database Appliance Setup Poster Updated

- by Ravi.Sharma

The newly updated Setup Poster for Oracle Database Appliance is now available at http://wd0338.oracle.com/archive/cd_ns/E22693_01/index.htm This updated poster is a comprehensive source of information for anyone planning to deploy Oracle Database Appliance. It includes two main sections (which are conveniently printed on the two sides of a single 11x17 page) 1. Preparing to Deploy Oracle Database Appliance2. Oracle Database Appliance Setup The Preparing to Deploy Oracle Database Appliance section provides a concise list of items to plan for and review before beginning deployment. This includes registering Support Identifiers, allocating IP addresses, downloading software and patches, choosing configuration options, as well as important links to useful information. The Oracle Database Appliance Setup section provides a step by step procedure for deploying and configuring Oracle Database Appliance. This includes initial powering up of Oracle Database Appliance, configuring initial network, downloading software and completing the configuration using Oracle Database Appliance Configurator (GUI)

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value types in the vm

- by john.rose

value types in the vm p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Times} p.p2 {margin: 0.0px 0.0px 14.0px 0.0px; font: 14.0px Times} p.p3 {margin: 0.0px 0.0px 12.0px 0.0px; font: 14.0px Times} p.p4 {margin: 0.0px 0.0px 15.0px 0.0px; font: 14.0px Times} p.p5 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Courier} p.p6 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Courier; min-height: 17.0px} p.p7 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Times; min-height: 18.0px} p.p8 {margin: 0.0px 0.0px 0.0px 36.0px; text-indent: -36.0px; font: 14.0px Times; min-height: 18.0px} p.p9 {margin: 0.0px 0.0px 12.0px 0.0px; font: 14.0px Times; min-height: 18.0px} p.p10 {margin: 0.0px 0.0px 12.0px 0.0px; font: 14.0px Times; color: #000000} li.li1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Times} li.li7 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Times; min-height: 18.0px} span.s1 {font: 14.0px Courier} span.s2 {color: #000000} span.s3 {font: 14.0px Courier; color: #000000} ol.ol1 {list-style-type: decimal} Or, enduring values for a changing world. Introduction A value type is a data type which, generally speaking, is designed for being passed by value in and out of methods, and stored by value in data structures. The only value types which the Java language directly supports are the eight primitive types. Java indirectly and approximately supports value types, if they are implemented in terms of classes. For example, both Integer and String may be viewed as value types, especially if their usage is restricted to avoid operations appropriate to Object. In this note, we propose a definition of value types in terms of a design pattern for Java classes, accompanied by a set of usage restrictions. We also sketch the relation of such value types to tuple types (which are a JVM-level notion), and point out JVM optimizations that can apply to value types. This note is a thought experiment to extend the JVM’s performance model in support of value types. The demonstration has two phases. Initially the extension can simply use design patterns, within the current bytecode architecture, and in today’s Java language. But if the performance model is to be realized in practice, it will probably require new JVM bytecode features, changes to the Java language, or both. We will look at a few possibilities for these new features. An Axiom of Value In the context of the JVM, a value type is a data type equipped with construction, assignment, and equality operations, and a set of typed components, such that, whenever two variables of the value type produce equal corresponding values for their components, the values of the two variables cannot be distinguished by any JVM operation. Here are some corollaries: A value type is immutable, since otherwise a copy could be constructed and the original could be modified in one of its components, allowing the copies to be distinguished. Changing the component of a value type requires construction of a new value. The equals and hashCode operations are strictly component-wise. If a value type is represented by a JVM reference, that reference cannot be successfully synchronized on, and cannot be usefully compared for reference equality. A value type can be viewed in terms of what it doesn’t do. We can say that a value type omits all value-unsafe operations, which could violate the constraints on value types. These operations, which are ordinarily allowed for Java object types, are pointer equality comparison (the acmp instruction), synchronization (the monitor instructions), all the wait and notify methods of class Object, and non-trivial finalize methods. The clone method is also value-unsafe, although for value types it could be treated as the identity function. Finally, and most importantly, any side effect on an object (however visible) also counts as an value-unsafe operation. A value type may have methods, but such methods must not change the components of the value. It is reasonable and useful to define methods like toString, equals, and hashCode on value types, and also methods which are specifically valuable to users of the value type. Representations of Value Value types have two natural representations in the JVM, unboxed and boxed. An unboxed value consists of the components, as simple variables. For example, the complex number x=(1+2i), in rectangular coordinate form, may be represented in unboxed form by the following pair of variables: /*Complex x = Complex.valueOf(1.0, 2.0):*/ double x_re = 1.0, x_im = 2.0; These variables might be locals, parameters, or fields. Their association as components of a single value is not defined to the JVM. Here is a sample computation which computes the norm of the difference between two complex numbers: double distance(/*Complex x:*/ double x_re, double x_im, /*Complex y:*/ double y_re, double y_im) { /*Complex z = x.minus(y):*/ double z_re = x_re - y_re, z_im = x_im - y_im; /*return z.abs():*/ return Math.sqrt(z_re*z_re + z_im*z_im); } A boxed representation groups component values under a single object reference. The reference is to a ‘wrapper class’ that carries the component values in its fields. (A primitive type can naturally be equated with a trivial value type with just one component of that type. In that view, the wrapper class Integer can serve as a boxed representation of value type int.) The unboxed representation of complex numbers is practical for many uses, but it fails to cover several major use cases: return values, array elements, and generic APIs. The two components of a complex number cannot be directly returned from a Java function, since Java does not support multiple return values. The same story applies to array elements: Java has no ’array of structs’ feature. (Double-length arrays are a possible workaround for complex numbers, but not for value types with heterogeneous components.) By generic APIs I mean both those which use generic types, like Arrays.asList and those which have special case support for primitive types, like String.valueOf and PrintStream.println. Those APIs do not support unboxed values, and offer some problems to boxed values. Any ’real’ JVM type should have a story for returns, arrays, and API interoperability. The basic problem here is that value types fall between primitive types and object types. Value types are clearly more complex than primitive types, and object types are slightly too complicated. Objects are a little bit dangerous to use as value carriers, since object references can be compared for pointer equality, and can be synchronized on. Also, as many Java programmers have observed, there is often a performance cost to using wrapper objects, even on modern JVMs. Even so, wrapper classes are a good starting point for talking about value types. If there were a set of structural rules and restrictions which would prevent value-unsafe operations on value types, wrapper classes would provide a good notation for defining value types. This note attempts to define such rules and restrictions. Let’s Start Coding Now it is time to look at some real code. Here is a definition, written in Java, of a complex number value type. @ValueSafe public final class Complex implements java.io.Serializable { // immutable component structure: public final double re, im; private Complex(double re, double im) { this.re = re; this.im = im; } // interoperability methods: public String toString() { return "Complex("+re+","+im+")"; } public List<Double> asList() { return Arrays.asList(re, im); } public boolean equals(Complex c) { return re == c.re && im == c.im; } public boolean equals(@ValueSafe Object x) { return x instanceof Complex && equals((Complex) x); } public int hashCode() { return 31*Double.valueOf(re).hashCode() + Double.valueOf(im).hashCode(); } // factory methods: public static Complex valueOf(double re, double im) { return new Complex(re, im); } public Complex changeRe(double re2) { return valueOf(re2, im); } public Complex changeIm(double im2) { return valueOf(re, im2); } public static Complex cast(@ValueSafe Object x) { return x == null ? ZERO : (Complex) x; } // utility methods and constants: public Complex plus(Complex c) { return new Complex(re+c.re, im+c.im); } public Complex minus(Complex c) { return new Complex(re-c.re, im-c.im); } public double abs() { return Math.sqrt(re*re + im*im); } public static final Complex PI = valueOf(Math.PI, 0.0); public static final Complex ZERO = valueOf(0.0, 0.0); } This is not a minimal definition, because it includes some utility methods and other optional parts. The essential elements are as follows: The class is marked as a value type with an annotation. The class is final, because it does not make sense to create subclasses of value types. The fields of the class are all non-private and final. (I.e., the type is immutable and structurally transparent.) From the supertype Object, all public non-final methods are overridden. The constructor is private. Beyond these bare essentials, we can observe the following features in this example, which are likely to be typical of all value types: One or more factory methods are responsible for value creation, including a component-wise valueOf method. There are utility methods for complex arithmetic and instance creation, such as plus and changeIm. There are static utility constants, such as PI. The type is serializable, using the default mechanisms. There are methods for converting to and from dynamically typed references, such as asList and cast. The Rules In order to use value types properly, the programmer must avoid value-unsafe operations. A helpful Java compiler should issue errors (or at least warnings) for code which provably applies value-unsafe operations, and should issue warnings for code which might be correct but does not provably avoid value-unsafe operations. No such compilers exist today, but to simplify our account here, we will pretend that they do exist. A value-safe type is any class, interface, or type parameter marked with the @ValueSafe annotation, or any subtype of a value-safe type. If a value-safe class is marked final, it is in fact a value type. All other value-safe classes must be abstract. The non-static fields of a value class must be non-public and final, and all its constructors must be private. Under the above rules, a standard interface could be helpful to define value types like Complex. Here is an example: @ValueSafe public interface ValueType extends java.io.Serializable { // All methods listed here must get redefined. // Definitions must be value-safe, which means // they may depend on component values only. List<? extends Object> asList(); int hashCode(); boolean equals(@ValueSafe Object c); String toString(); } //@ValueSafe inherited from supertype: public final class Complex implements ValueType { … The main advantage of such a conventional interface is that (unlike an annotation) it is reified in the runtime type system. It could appear as an element type or parameter bound, for facilities which are designed to work on value types only. More broadly, it might assist the JVM to perform dynamic enforcement of the rules for value types. Besides types, the annotation @ValueSafe can mark fields, parameters, local variables, and methods. (This is redundant when the type is also value-safe, but may be useful when the type is Object or another supertype of a value type.) Working forward from these annotations, an expression E is defined as value-safe if it satisfies one or more of the following: The type of E is a value-safe type. E names a field, parameter, or local variable whose declaration is marked @ValueSafe. E is a call to a method whose declaration is marked @ValueSafe. E is an assignment to a value-safe variable, field reference, or array reference. E is a cast to a value-safe type from a value-safe expression. E is a conditional expression E0 ? E1 : E2, and both E1 and E2 are value-safe. Assignments to value-safe expressions and initializations of value-safe names must take their values from value-safe expressions. A value-safe expression may not be the subject of a value-unsafe operation. In particular, it cannot be synchronized on, nor can it be compared with the “==” operator, not even with a null or with another value-safe type. In a program where all of these rules are followed, no value-type value will be subject to a value-unsafe operation. Thus, the prime axiom of value types will be satisfied, that no two value type will be distinguishable as long as their component values are equal. More Code To illustrate these rules, here are some usage examples for Complex: Complex pi = Complex.valueOf(Math.PI, 0); Complex zero = pi.changeRe(0); //zero = pi; zero.re = 0; ValueType vtype = pi; @SuppressWarnings("value-unsafe") Object obj = pi; @ValueSafe Object obj2 = pi; obj2 = new Object(); // ok List<Complex> clist = new ArrayList<Complex>(); clist.add(pi); // (ok assuming List.add param is @ValueSafe) List<ValueType> vlist = new ArrayList<ValueType>(); vlist.add(pi); // (ok) List<Object> olist = new ArrayList<Object>(); olist.add(pi); // warning: "value-unsafe" boolean z = pi.equals(zero); boolean z1 = (pi == zero); // error: reference comparison on value type boolean z2 = (pi == null); // error: reference comparison on value type boolean z3 = (pi == obj2); // error: reference comparison on value type synchronized (pi) { } // error: synch of value, unpredictable result synchronized (obj2) { } // unpredictable result Complex qq = pi; qq = null; // possible NPE; warning: “null-unsafe" qq = (Complex) obj; // warning: “null-unsafe" qq = Complex.cast(obj); // OK @SuppressWarnings("null-unsafe") Complex empty = null; // possible NPE qq = empty; // possible NPE (null pollution) The Payoffs It follows from this that either the JVM or the java compiler can replace boxed value-type values with unboxed ones, without affecting normal computations. Fields and variables of value types can be split into their unboxed components. Non-static methods on value types can be transformed into static methods which take the components as value parameters. Some common questions arise around this point in any discussion of value types. Why burden the programmer with all these extra rules? Why not detect programs automagically and perform unboxing transparently? The answer is that it is easy to break the rules accidently unless they are agreed to by the programmer and enforced. Automatic unboxing optimizations are tantalizing but (so far) unreachable ideal. In the current state of the art, it is possible exhibit benchmarks in which automatic unboxing provides the desired effects, but it is not possible to provide a JVM with a performance model that assures the programmer when unboxing will occur. This is why I’m writing this note, to enlist help from, and provide assurances to, the programmer. Basically, I’m shooting for a good set of user-supplied “pragmas” to frame the desired optimization. Again, the important thing is that the unboxing must be done reliably, or else programmers will have no reason to work with the extra complexity of the value-safety rules. There must be a reasonably stable performance model, wherein using a value type has approximately the same performance characteristics as writing the unboxed components as separate Java variables. There are some rough corners to the present scheme. Since Java fields and array elements are initialized to null, value-type computations which incorporate uninitialized variables can produce null pointer exceptions. One workaround for this is to require such variables to be null-tested, and the result replaced with a suitable all-zero value of the value type. That is what the “cast” method does above. Generically typed APIs like List<T> will continue to manipulate boxed values always, at least until we figure out how to do reification of generic type instances. Use of such APIs will elicit warnings until their type parameters (and/or relevant members) are annotated or typed as value-safe. Retrofitting List<T> is likely to expose flaws in the present scheme, which we will need to engineer around. Here are a couple of first approaches: public interface java.util.List<@ValueSafe T> extends Collection<T> { … public interface java.util.List<T extends Object|ValueType> extends Collection<T> { … (The second approach would require disjunctive types, in which value-safety is “contagious” from the constituent types.) With more transformations, the return value types of methods can also be unboxed. This may require significant bytecode-level transformations, and would work best in the presence of a bytecode representation for multiple value groups, which I have proposed elsewhere under the title “Tuples in the VM”. But for starters, the JVM can apply this transformation under the covers, to internally compiled methods. This would give a way to express multiple return values and structured return values, which is a significant pain-point for Java programmers, especially those who work with low-level structure types favored by modern vector and graphics processors. The lack of multiple return values has a strong distorting effect on many Java APIs. Even if the JVM fails to unbox a value, there is still potential benefit to the value type. Clustered computing systems something have copy operations (serialization or something similar) which apply implicitly to command operands. When copying JVM objects, it is extremely helpful to know when an object’s identity is important or not. If an object reference is a copied operand, the system may have to create a proxy handle which points back to the original object, so that side effects are visible. Proxies must be managed carefully, and this can be expensive. On the other hand, value types are exactly those types which a JVM can “copy and forget” with no downside. Array types are crucial to bulk data interfaces. (As data sizes and rates increase, bulk data becomes more important than scalar data, so arrays are definitely accompanying us into the future of computing.) Value types are very helpful for adding structure to bulk data, so a successful value type mechanism will make it easier for us to express richer forms of bulk data. Unboxing arrays (i.e., arrays containing unboxed values) will provide better cache and memory density, and more direct data movement within clustered or heterogeneous computing systems. They require the deepest transformations, relative to today’s JVM. There is an impedance mismatch between value-type arrays and Java’s covariant array typing, so compromises will need to be struck with existing Java semantics. It is probably worth the effort, since arrays of unboxed value types are inherently more memory-efficient than standard Java arrays, which rely on dependent pointer chains. It may be sufficient to extend the “value-safe” concept to array declarations, and allow low-level transformations to change value-safe array declarations from the standard boxed form into an unboxed tuple-based form. Such value-safe arrays would not be convertible to Object[] arrays. Certain connection points, such as Arrays.copyOf and System.arraycopy might need additional input/output combinations, to allow smooth conversion between arrays with boxed and unboxed elements. Alternatively, the correct solution may have to wait until we have enough reification of generic types, and enough operator overloading, to enable an overhaul of Java arrays. Implicit Method Definitions The example of class Complex above may be unattractively complex. I believe most or all of the elements of the example class are required by the logic of value types. If this is true, a programmer who writes a value type will have to write lots of error-prone boilerplate code. On the other hand, I think nearly all of the code (except for the domain-specific parts like plus and minus) can be implicitly generated. Java has a rule for implicitly defining a class’s constructor, if no it defines no constructors explicitly. Likewise, there are rules for providing default access modifiers for interface members. Because of the highly regular structure of value types, it might be reasonable to perform similar implicit transformations on value types. Here’s an example of a “highly implicit” definition of a complex number type: public class Complex implements ValueType { // implicitly final public double re, im; // implicitly public final //implicit methods are defined elementwise from te fields: // toString, asList, equals(2), hashCode, valueOf, cast //optionally, explicit methods (plus, abs, etc.) would go here } In other words, with the right defaults, a simple value type definition can be a one-liner. The observant reader will have noticed the similarities (and suitable differences) between the explicit methods above and the corresponding methods for List<T>. Another way to abbreviate such a class would be to make an annotation the primary trigger of the functionality, and to add the interface(s) implicitly: public @ValueType class Complex { … // implicitly final, implements ValueType (But to me it seems better to communicate the “magic” via an interface, even if it is rooted in an annotation.) Implicitly Defined Value Types So far we have been working with nominal value types, which is to say that the sequence of typed components is associated with a name and additional methods that convey the intention of the programmer. A simple ordered pair of floating point numbers can be variously interpreted as (to name a few possibilities) a rectangular or polar complex number or Cartesian point. The name and the methods convey the intended meaning. But what if we need a truly simple ordered pair of floating point numbers, without any further conceptual baggage? Perhaps we are writing a method (like “divideAndRemainder”) which naturally returns a pair of numbers instead of a single number. Wrapping the pair of numbers in a nominal type (like “QuotientAndRemainder”) makes as little sense as wrapping a single return value in a nominal type (like “Quotient”). What we need here are structural value types commonly known as tuples. For the present discussion, let us assign a conventional, JVM-friendly name to tuples, roughly as follows: public class java.lang.tuple.$DD extends java.lang.tuple.Tuple { double $1, $2; } Here the component names are fixed and all the required methods are defined implicitly. The supertype is an abstract class which has suitable shared declarations. The name itself mentions a JVM-style method parameter descriptor, which may be “cracked” to determine the number and types of the component fields. The odd thing about such a tuple type (and structural types in general) is it must be instantiated lazily, in response to linkage requests from one or more classes that need it. The JVM and/or its class loaders must be prepared to spin a tuple type on demand, given a simple name reference, $xyz, where the xyz is cracked into a series of component types. (Specifics of naming and name mangling need some tasteful engineering.) Tuples also seem to demand, even more than nominal types, some support from the language. (This is probably because notations for non-nominal types work best as combinations of punctuation and type names, rather than named constructors like Function3 or Tuple2.) At a minimum, languages with tuples usually (I think) have some sort of simple bracket notation for creating tuples, and a corresponding pattern-matching syntax (or “destructuring bind”) for taking tuples apart, at least when they are parameter lists. Designing such a syntax is no simple thing, because it ought to play well with nominal value types, and also with pre-existing Java features, such as method parameter lists, implicit conversions, generic types, and reflection. That is a task for another day. Other Use Cases Besides complex numbers and simple tuples there are many use cases for value types. Many tuple-like types have natural value-type representations. These include rational numbers, point locations and pixel colors, and various kinds of dates and addresses. Other types have a variable-length ‘tail’ of internal values. The most common example of this is String, which is (mathematically) a sequence of UTF-16 character values. Similarly, bit vectors, multiple-precision numbers, and polynomials are composed of sequences of values. Such types include, in their representation, a reference to a variable-sized data structure (often an array) which (somehow) represents the sequence of values. The value type may also include ’header’ information. Variable-sized values often have a length distribution which favors short lengths. In that case, the design of the value type can make the first few values in the sequence be direct ’header’ fields of the value type. In the common case where the header is enough to represent the whole value, the tail can be a shared null value, or even just a null reference. Note that the tail need not be an immutable object, as long as the header type encapsulates it well enough. This is the case with String, where the tail is a mutable (but never mutated) character array. Field types and their order must be a globally visible part of the API. The structure of the value type must be transparent enough to have a globally consistent unboxed representation, so that all callers and callees agree about the type and order of components that appear as parameters, return types, and array elements. This is a trade-off between efficiency and encapsulation, which is forced on us when we remove an indirection enjoyed by boxed representations. A JVM-only transformation would not care about such visibility, but a bytecode transformation would need to take care that (say) the components of complex numbers would not get swapped after a redefinition of Complex and a partial recompile. Perhaps constant pool references to value types need to declare the field order as assumed by each API user. This brings up the delicate status of private fields in a value type. It must always be possible to load, store, and copy value types as coordinated groups, and the JVM performs those movements by moving individual scalar values between locals and stack. If a component field is not public, what is to prevent hostile code from plucking it out of the tuple using a rogue aload or astore instruction? Nothing but the verifier, so we may need to give it more smarts, so that it treats value types as inseparable groups of stack slots or locals (something like long or double). My initial thought was to make the fields always public, which would make the security problem moot. But public is not always the right answer; consider the case of String, where the underlying mutable character array must be encapsulated to prevent security holes. I believe we can win back both sides of the tradeoff, by training the verifier never to split up the components in an unboxed value. Just as the verifier encapsulates the two halves of a 64-bit primitive, it can encapsulate the the header and body of an unboxed String, so that no code other than that of class String itself can take apart the values. Similar to String, we could build an efficient multi-precision decimal type along these lines: public final class DecimalValue extends ValueType { protected final long header; protected private final BigInteger digits; public DecimalValue valueOf(int value, int scale) { assert(scale >= 0); return new DecimalValue(((long)value << 32) + scale, null); } public DecimalValue valueOf(long value, int scale) { if (value == (int) value) return valueOf((int)value, scale); return new DecimalValue(-scale, new BigInteger(value)); } } Values of this type would be passed between methods as two machine words. Small values (those with a significand which fits into 32 bits) would be represented without any heap data at all, unless the DecimalValue itself were boxed. (Note the tension between encapsulation and unboxing in this case. It would be better if the header and digits fields were private, but depending on where the unboxing information must “leak”, it is probably safer to make a public revelation of the internal structure.) Note that, although an array of Complex can be faked with a double-length array of double, there is no easy way to fake an array of unboxed DecimalValues. (Either an array of boxed values or a transposed pair of homogeneous arrays would be reasonable fallbacks, in a current JVM.) Getting the full benefit of unboxing and arrays will require some new JVM magic. Although the JVM emphasizes portability, system dependent code will benefit from using machine-level types larger than 64 bits. For example, the back end of a linear algebra package might benefit from value types like Float4 which map to stock vector types. This is probably only worthwhile if the unboxing arrays can be packed with such values. More Daydreams A more finely-divided design for dynamic enforcement of value safety could feature separate marker interfaces for each invariant. An empty marker interface Unsynchronizable could cause suitable exceptions for monitor instructions on objects in marked classes. More radically, a Interchangeable marker interface could cause JVM primitives that are sensitive to object identity to raise exceptions; the strangest result would be that the acmp instruction would have to be specified as raising an exception. @ValueSafe public interface ValueType extends java.io.Serializable, Unsynchronizable, Interchangeable { … public class Complex implements ValueType { // inherits Serializable, Unsynchronizable, Interchangeable, @ValueSafe … It seems possible that Integer and the other wrapper types could be retro-fitted as value-safe types. This is a major change, since wrapper objects would be unsynchronizable and their references interchangeable. It is likely that code which violates value-safety for wrapper types exists but is uncommon. It is less plausible to retro-fit String, since the prominent operation String.intern is often used with value-unsafe code. We should also reconsider the distinction between boxed and unboxed values in code. The design presented above obscures that distinction. As another thought experiment, we could imagine making a first class distinction in the type system between boxed and unboxed representations. Since only primitive types are named with a lower-case initial letter, we could define that the capitalized version of a value type name always refers to the boxed representation, while the initial lower-case variant always refers to boxed. For example: complex pi = complex.valueOf(Math.PI, 0); Complex boxPi = pi; // convert to boxed myList.add(boxPi); complex z = myList.get(0); // unbox Such a convention could perhaps absorb the current difference between int and Integer, double and Double. It might also allow the programmer to express a helpful distinction among array types. As said above, array types are crucial to bulk data interfaces, but are limited in the JVM. Extending arrays beyond the present limitations is worth thinking about; for example, the Maxine JVM implementation has a hybrid object/array type. Something like this which can also accommodate value type components seems worthwhile. On the other hand, does it make sense for value types to contain short arrays? And why should random-access arrays be the end of our design process, when bulk data is often sequentially accessed, and it might make sense to have heterogeneous streams of data as the natural “jumbo” data structure. These considerations must wait for another day and another note. More Work It seems to me that a good sequence for introducing such value types would be as follows: Add the value-safety restrictions to an experimental version of javac. Code some sample applications with value types, including Complex and DecimalValue. Create an experimental JVM which internally unboxes value types but does not require new bytecodes to do so. Ensure the feasibility of the performance model for the sample applications. Add tuple-like bytecodes (with or without generic type reification) to a major revision of the JVM, and teach the Java compiler to switch in the new bytecodes without code changes. A staggered roll-out like this would decouple language changes from bytecode changes, which is always a convenient thing. A similar investigation should be applied (concurrently) to array types. In this case, it seems to me that the starting point is in the JVM: Add an experimental unboxing array data structure to a production JVM, perhaps along the lines of Maxine hybrids. No bytecode or language support is required at first; everything can be done with encapsulated unsafe operations and/or method handles. Create an experimental JVM which internally unboxes value types but does not require new bytecodes to do so. Ensure the feasibility of the performance model for the sample applications. Add tuple-like bytecodes (with or without generic type reification) to a major revision of the JVM, and teach the Java compiler to switch in the new bytecodes without code changes. That’s enough musing me for now. Back to work!

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