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• SQL Server and Hyper-V Dynamic Memory - Part 1

  - by SQLOS Team

  SQL and Dynamic Memory Blog Post Series   Hyper-V Dynamic Memory is a new feature in Windows Server 2008 R2 SP1 that allows the memory assigned to guest virtual machines to vary according to demand. Using this feature with SQL Server is supported, but how well does it work in an environment where available memory can vary dynamically, especially since SQL Server likes memory, and is not very eager to let go of it? The next three posts will look at this question in detail. In Part 1 Serdar Sutay, a program manager in the Windows Hyper-V team, introduces Dynamic Memory with an overview of the basic architecture, configuration and monitoring concepts. In subsequent parts we will look at SQL Server memory handling, and develop some guidelines on using SQL Server with Dynamic Memory.   Part 1: Dynamic Memory Introduction   In virtualized environments memory is often the bottleneck for reaching higher VM densities. In Windows Server 2008 R2 SP1 Hyper-V introduced a new feature “Dynamic Memory” to improve VM densities on Hyper-V hosts. Dynamic Memory increases the memory utilization in virtualized environments by enabling VM memory to be changed dynamically when the VM is running.   This brings up the question of how to utilize this feature with SQL Server VMs as SQL Server performance is very sensitive to the memory being used. In the next three posts we’ll discuss the internals of Dynamic Memory, SQL Server Memory Management and how to use Dynamic Memory with SQL Server VMs.   Memory Utilization Efficiency in Virtualized Environments   The primary reason memory is usually the bottleneck for higher VM densities is that users tend to be generous when assigning memory to their VMs. Here are some memory sizing practices we’ve heard from customers:   ·         I assign 4 GB of memory to my VMs. I don’t know if all of it is being used by the applications but no one complains. ·         I take the minimum system requirements and add 50% more. ·         I go with the recommendations provided by my software vendor.   In reality correctly sizing a virtual machine requires significant effort to monitor the memory usage of the applications. Since this is not done in most environments, VMs are usually over-provisioned in terms of memory. In other words, a SQL Server VM that is assigned 4 GB of memory may not need to use 4 GB.   How does Dynamic Memory help?   Dynamic Memory improves the memory utilization by removing the requirement to determine the memory need for an application. Hyper-V determines the memory needed by applications in the VM by evaluating the memory usage information in the guest with Dynamic Memory. VMs can start with a small amount of memory and they can be assigned more memory dynamically based on the workload of applications running inside.   Overview of Dynamic Memory Concepts   ·         Startup Memory: Startup Memory is the starting amount of memory when Dynamic Memory is enabled for a VM. Dynamic Memory will make sure that this amount of memory is always assigned to the VMs by default.   ·         Maximum Memory: Maximum Memory specifies the maximum amount of memory that a VM can grow to with Dynamic Memory. ·         Memory Demand: Memory Demand is the amount determined by Dynamic Memory as the memory needed by the applications in the VM. In Windows Server 2008 R2 SP1, this is equal to the total amount of committed memory of the VM. ·         Memory Buffer: Memory Buffer is the amount of memory assigned to the VMs in addition to their memory demand to satisfy immediate memory requirements and file cache needs.   Once Dynamic Memory is enabled for a VM, it will start with the “Startup Memory”. After the boot process Dynamic Memory will determine the “Memory Demand” of the VM. Based on this memory demand it will determine the amount of “Memory Buffer” that needs to be assigned to the VM. Dynamic Memory will assign the total of “Memory Demand” and “Memory Buffer” to the VM as long as this value is less than “Maximum Memory” and as long as physical memory is available on the host.   What happens when there is not enough physical memory available on the host?   Once there is not enough physical memory on the host to satisfy VM needs, Dynamic Memory will assign less than needed amount of memory to the VMs based on their importance. A concept known as “Memory Weight” is used to determine how much VMs should be penalized based on their needed amount of memory. “Memory Weight” is a configuration setting on the VM. It can be configured to be higher for the VMs with high performance requirements. Under high memory pressure on the host, the “Memory Weight” of the VMs are evaluated in a relative manner and the VMs with lower relative “Memory Weight” will be penalized more than the ones with higher “Memory Weight”.   Dynamic Memory Configuration   Based on these concepts “Startup Memory”, “Maximum Memory”, “Memory Buffer” and “Memory Weight” can be configured as shown below in Windows Server 2008 R2 SP1 Hyper-V Manager. Memory Demand is automatically calculated by Dynamic Memory once VMs start running.     Dynamic Memory Monitoring    In Windows Server 2008 R2 SP1, Hyper-V Manager displays the memory status of VMs in the following three columns:         ·         Assigned Memory represents the current physical memory assigned to the VM. In regular conditions this will be equal to the sum of “Memory Demand” and “Memory Buffer” assigned to the VM. When there is not enough memory on the host, this value can go below the Memory Demand determined for the VM. ·         Memory Demand displays the current “Memory Demand” determined for the VM. ·         Memory Status displays the current memory status of the VM. This column can represent three values for a VM: o   OK: In this condition the VM is assigned the total of Memory Demand and Memory Buffer it needs. o   Low: In this condition the VM is assigned all the Memory Demand and a certain percentage of the Memory Buffer it needs. o   Warning: In this condition the VM is assigned a lower memory than its Memory Demand. When VMs are running in this condition, it’s likely that they will exhibit performance problems due to internal paging happening in the VM.    So far so good! But how does it work with SQL Server?   SQL Server is aggressive in terms of memory usage for good reasons. This raises the question: How do SQL Server and Dynamic Memory work together? To understand the full story, we’ll first need to understand how SQL Server Memory Management works. This will be covered in our second post in “SQL and Dynamic Memory” series. Meanwhile if you want to dive deeper into Dynamic Memory you can check the below posts from the Windows Virtualization Team Blog:   http://blogs.technet.com/virtualization/archive/2010/03/18/dynamic-memory-coming-to-hyper-v.aspx   http://blogs.technet.com/virtualization/archive/2010/03/25/dynamic-memory-coming-to-hyper-v-part-2.aspx   http://blogs.technet.com/virtualization/archive/2010/04/07/dynamic-memory-coming-to-hyper-v-part-3.aspx   http://blogs.technet.com/b/virtualization/archive/2010/04/21/dynamic-memory-coming-to-hyper-v-part-4.aspx   http://blogs.technet.com/b/virtualization/archive/2010/05/20/dynamic-memory-coming-to-hyper-v-part-5.aspx   http://blogs.technet.com/b/virtualization/archive/2010/07/12/dynamic-memory-coming-to-hyper-v-part-6.aspx   - Serdar Sutay   Originally posted at http://blogs.msdn.com/b/sqlosteam/

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• How about a new platform for your next API&hellip; a CMS?

  - by Elton Stoneman

  Originally posted on: http://geekswithblogs.net/EltonStoneman/archive/2014/05/22/how-about-a-new-platform-for-your-next-apihellip-a.aspxSay what? I’m seeing a type of API emerge which serves static or long-lived resources, which are mostly read-only and have a controlled process to update the data that gets served. Think of something like an app configuration API, where you want a central location for changeable settings. You could use this server side to store database connection strings and keep all your instances in sync, or it could be used client side to push changes out to all users (and potentially driving A/B or MVT testing). That’s a good candidate for a RESTful API which makes proper use of HTTP expiration and validation caching to minimise traffic, but really you want a front end UI where you can edit the current config that the API returns and publish your changes. Sound like a Content Mangement System would be a good fit? I’ve been looking at that and it’s a great fit for this scenario. You get a lot of what you need out of the box, the amount of custom code you need to write is minimal, and you get a whole lot of extra stuff from using CMS which is very useful, but probably not something you’d build if you had to put together a quick UI over your API content (like a publish workflow, fine-grained security and an audit trail). You typically use a CMS for HTML resources, but it’s simple to expose JSON instead – or to do content negotiation to support both, so you can open a resource in a browser and see a nice visual representation, or request it with: Accept=application/json and get the same content rendered as JSON for the app to use. Enter Umbraco Umbraco is an open source .NET CMS that’s been around for a while. It has very good adoption, a lively community and a good release cycle. It’s easy to use, has all the functionality you need for a CMS-driven API, and it’s scalable (although you won’t necessarily put much scale on the CMS layer). In the rest of this post, I’ll build out a simple app config API using Umbraco. We’ll define the structure of the configuration resource by creating a new Document Type and setting custom properties; then we’ll build a very simple Razor template to return configuration documents as JSON; then create a resource and see how it looks. And we’ll look at how you could build this into a wider solution. If you want to try this for yourself, it’s ultra easy – there’s an Umbraco image in the Azure Website gallery, so all you need to to is create a new Website, select Umbraco from the image and complete the installation. It will create a SQL Azure website to store all the content, as well as a Website instance for editing and accessing content. They’re standard Azure resources, so you can scale them as you need. The default install creates a starter site for some HTML content, which you can use to learn your way around (or just delete). 1. Create Configuration Document Type In Umbraco you manage content by creating and modifying documents, and every document has a known type, defining what properties it holds. We’ll create a new Document Type to describe some basic config settings. In the Settings section from the left navigation (spanner icon), expand Document Types and Master, hit the ellipsis and select to create a new Document Type: This will base your new type off the Master type, which gives you some existing properties that we’ll use – like the Page Title which will be the resource URL. In the Generic Properties tab for the new Document Type, you set the properties you’ll be able to edit and return for the resource: Here I’ve added a text string where I’ll set a default cache lifespan, an image which I can use for a banner display, and a date which could show the user when the next release is due. This is the sort of thing that sits nicely in an app config API. It’s likely to change during the life of the product, but not very often, so it’s good to have a centralised place where you can make and publish changes easily and safely. It also enables A/B and MVT testing, as you can change the response each client gets based on your set logic, and their apps will behave differently without needing a release. 2. Define the response template Now we’ve defined the structure of the resource (as a document), in Umbraco we can define a C# Razor template to say how that resource gets rendered to the client. If you only want to provide JSON, it’s easy to render the content of the document by building each property in the response (Umbraco uses dynamic objects so you can specify document properties as object properties), or you can support content negotiation with very little effort. Here’s a template to render the document as HTML or JSON depending on the Accept header, using JSON.NET for the API rendering: @inherits Umbraco.Web.Mvc.UmbracoTemplatePage @using Newtonsoft.Json @{ Layout = null; } @if(UmbracoContext.HttpContext.Request.Headers["accept"] != null &amp;&amp; UmbracoContext.HttpContext.Request.Headers["accept"] == "application/json") { Response.ContentType = "application/json"; @Html.Raw(JsonConvert.SerializeObject(new { cacheLifespan = CurrentPage.cacheLifespan, bannerImageUrl = CurrentPage.bannerImage, nextReleaseDate = CurrentPage.nextReleaseDate })) } else { <h1>App configuration</h1> <p>Cache lifespan: <b>@CurrentPage.cacheLifespan</b></p> <p>Banner Image: </p> <img src="@CurrentPage.bannerImage"> <p>Next Release Date: <b>@CurrentPage.nextReleaseDate</b></p> } That’s a rough-and ready example of what you can do. You could make it completely generic and just render all the document’s properties as JSON, but having a specific template for each resource gives you control over what gets sent out. And the templates are evaluated at run-time, so if you need to change the output – or extend it, say to add caching response headers – you just edit the template and save, and the next client request gets rendered from the new template. No code to build and ship. 3. Create the content With your document type created, in  the Content pane you can create a new instance of that document, where Umbraco gives you a nice UI to input values for the properties we set up on the Document Type: Here I’ve set the cache lifespan to an xs:duration value, uploaded an image for the banner and specified a release date. Each property gets the appropriate input control – text box, file upload and date picker. At the top of the page is the name of the resource – myapp in this example. That specifies the URL for the resource, so if I had a DNS entry pointing to my Umbraco instance, I could access the config with a URL like http://static.x.y.z.com/config/myapp. The setup is all done now, so when we publish this resource it’ll be available to access.  4. Access the resource Now if you open  that URL in the browser, you’ll see the HTML version rendered: - complete with the  image and formatted date. Umbraco lets you save changes and preview them before publishing, so the HTML view could be a good way of showing editors their changes in a usable view, before they confirm them. If you browse the same URL from a REST client, specifying the Accept=application/json request header, you get this response:   That’s the exact same resource, with a managed UI to publish it, being accessed as HTML or JSON with a tiny amount of effort. 5. The wider landscape If you have fairy stable content to expose as an API, I think  this approach is really worth considering. Umbraco scales very nicely, but in a typical solution you probably wouldn’t need it to. When you have additional requirements, like logging API access requests - but doing it out-of-band so clients aren’t impacted, you can put a very thin API layer on top of Umbraco, and cache the CMS responses in your API layer:   Here the API does a passthrough to CMS, so the CMS still controls the content, but it caches the response. If the response is cached for 1 minute, then Umbraco only needs to handle 1 request per minute (multiplied by the number of API instances), so if you need to support 1000s of request per second, you’re scaling a thin, simple API layer rather than having to scale the more complex CMS infrastructure (including the database). This diagram also shows an approach to logging, by asynchronously publishing a message to a queue (Redis in this case), which can be picked up later and persisted by a different process. Does it work? Beautifully. Using Azure, I spiked the solution above (including the Redis logging framework which I’ll blog about later) in half a day. That included setting up different roles in Umbraco to demonstrate a managed workflow for publishing changes, and a couple of document types representing different resources. Is it maintainable? We have three moving parts, which are all managed resources in Azure –  an Azure Website for Umbraco which may need a couple of instances for HA (or may not, depending on how long the content can be cached), a message queue (Redis is in preview in Azure, but you can easily use Service Bus Queues if performance is less of a concern), and the Web Role for the API. Two of the components are off-the-shelf, from open source projects, and the only custom code is the API which is very simple. Does it scale? Pretty nicely. With a single Umbraco instance running as an Azure Website, and with 4x instances for my API layer (Standard sized Web Roles), I got just under 4,000 requests per second served reliably, with a Worker Role in the background saving the access logs. So we had a nice UI to publish app config changes, with a friendly Web preview and a publishing workflow, capable of supporting 14 million requests in an hour, with less than a day’s effort. Worth considering if you’re publishing long-lived resources through your API.

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• SQL Server and Hyper-V Dynamic Memory - Part 1

  - by SQLOS Team

  SQL and Dynamic Memory Blog Post Series   Hyper-V Dynamic Memory is a new feature in Windows Server 2008 R2 SP1 that allows the memory assigned to guest virtual machines to vary according to demand. Using this feature with SQL Server is supported, but how well does it work in an environment where available memory can vary dynamically, especially since SQL Server likes memory, and is not very eager to let go of it? The next three posts will look at this question in detail. In Part 1 Serdar Sutay, a program manager in the Windows Hyper-V team, introduces Dynamic Memory with an overview of the basic architecture, configuration and monitoring concepts. In subsequent parts we will look at SQL Server memory handling, and develop some guidelines on using SQL Server with Dynamic Memory.   Part 1: Dynamic Memory Introduction   In virtualized environments memory is often the bottleneck for reaching higher VM densities. In Windows Server 2008 R2 SP1 Hyper-V introduced a new feature “Dynamic Memory” to improve VM densities on Hyper-V hosts. Dynamic Memory increases the memory utilization in virtualized environments by enabling VM memory to be changed dynamically when the VM is running.   This brings up the question of how to utilize this feature with SQL Server VMs as SQL Server performance is very sensitive to the memory being used. In the next three posts we’ll discuss the internals of Dynamic Memory, SQL Server Memory Management and how to use Dynamic Memory with SQL Server VMs.   Memory Utilization Efficiency in Virtualized Environments   The primary reason memory is usually the bottleneck for higher VM densities is that users tend to be generous when assigning memory to their VMs. Here are some memory sizing practices we’ve heard from customers:   ·         I assign 4 GB of memory to my VMs. I don’t know if all of it is being used by the applications but no one complains. ·         I take the minimum system requirements and add 50% more. ·         I go with the recommendations provided by my software vendor.   In reality correctly sizing a virtual machine requires significant effort to monitor the memory usage of the applications. Since this is not done in most environments, VMs are usually over-provisioned in terms of memory. In other words, a SQL Server VM that is assigned 4 GB of memory may not need to use 4 GB.   How does Dynamic Memory help?   Dynamic Memory improves the memory utilization by removing the requirement to determine the memory need for an application. Hyper-V determines the memory needed by applications in the VM by evaluating the memory usage information in the guest with Dynamic Memory. VMs can start with a small amount of memory and they can be assigned more memory dynamically based on the workload of applications running inside.   Overview of Dynamic Memory Concepts   ·         Startup Memory: Startup Memory is the starting amount of memory when Dynamic Memory is enabled for a VM. Dynamic Memory will make sure that this amount of memory is always assigned to the VMs by default.   ·         Maximum Memory: Maximum Memory specifies the maximum amount of memory that a VM can grow to with Dynamic Memory. ·         Memory Demand: Memory Demand is the amount determined by Dynamic Memory as the memory needed by the applications in the VM. In Windows Server 2008 R2 SP1, this is equal to the total amount of committed memory of the VM. ·         Memory Buffer: Memory Buffer is the amount of memory assigned to the VMs in addition to their memory demand to satisfy immediate memory requirements and file cache needs.   Once Dynamic Memory is enabled for a VM, it will start with the “Startup Memory”. After the boot process Dynamic Memory will determine the “Memory Demand” of the VM. Based on this memory demand it will determine the amount of “Memory Buffer” that needs to be assigned to the VM. Dynamic Memory will assign the total of “Memory Demand” and “Memory Buffer” to the VM as long as this value is less than “Maximum Memory” and as long as physical memory is available on the host.   What happens when there is not enough physical memory available on the host?   Once there is not enough physical memory on the host to satisfy VM needs, Dynamic Memory will assign less than needed amount of memory to the VMs based on their importance. A concept known as “Memory Weight” is used to determine how much VMs should be penalized based on their needed amount of memory. “Memory Weight” is a configuration setting on the VM. It can be configured to be higher for the VMs with high performance requirements. Under high memory pressure on the host, the “Memory Weight” of the VMs are evaluated in a relative manner and the VMs with lower relative “Memory Weight” will be penalized more than the ones with higher “Memory Weight”.   Dynamic Memory Configuration   Based on these concepts “Startup Memory”, “Maximum Memory”, “Memory Buffer” and “Memory Weight” can be configured as shown below in Windows Server 2008 R2 SP1 Hyper-V Manager. Memory Demand is automatically calculated by Dynamic Memory once VMs start running.     Dynamic Memory Monitoring    In Windows Server 2008 R2 SP1, Hyper-V Manager displays the memory status of VMs in the following three columns:         ·         Assigned Memory represents the current physical memory assigned to the VM. In regular conditions this will be equal to the sum of “Memory Demand” and “Memory Buffer” assigned to the VM. When there is not enough memory on the host, this value can go below the Memory Demand determined for the VM. ·         Memory Demand displays the current “Memory Demand” determined for the VM. ·         Memory Status displays the current memory status of the VM. This column can represent three values for a VM: o   OK: In this condition the VM is assigned the total of Memory Demand and Memory Buffer it needs. o   Low: In this condition the VM is assigned all the Memory Demand and a certain percentage of the Memory Buffer it needs. o   Warning: In this condition the VM is assigned a lower memory than its Memory Demand. When VMs are running in this condition, it’s likely that they will exhibit performance problems due to internal paging happening in the VM.    So far so good! But how does it work with SQL Server?   SQL Server is aggressive in terms of memory usage for good reasons. This raises the question: How do SQL Server and Dynamic Memory work together? To understand the full story, we’ll first need to understand how SQL Server Memory Management works. This will be covered in our second post in “SQL and Dynamic Memory” series. Meanwhile if you want to dive deeper into Dynamic Memory you can check the below posts from the Windows Virtualization Team Blog:   http://blogs.technet.com/virtualization/archive/2010/03/18/dynamic-memory-coming-to-hyper-v.aspx   http://blogs.technet.com/virtualization/archive/2010/03/25/dynamic-memory-coming-to-hyper-v-part-2.aspx   http://blogs.technet.com/virtualization/archive/2010/04/07/dynamic-memory-coming-to-hyper-v-part-3.aspx   http://blogs.technet.com/b/virtualization/archive/2010/04/21/dynamic-memory-coming-to-hyper-v-part-4.aspx   http://blogs.technet.com/b/virtualization/archive/2010/05/20/dynamic-memory-coming-to-hyper-v-part-5.aspx   http://blogs.technet.com/b/virtualization/archive/2010/07/12/dynamic-memory-coming-to-hyper-v-part-6.aspx   - Serdar Sutay   Originally posted at http://blogs.msdn.com/b/sqlosteam/

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• A Nondeterministic Engine written in VB.NET 2010

  - by neil chen

  When I'm reading SICP (Structure and Interpretation of Computer Programs) recently, I'm very interested in the concept of an "Nondeterministic Algorithm". According to wikipedia:  In computer science, a nondeterministic algorithm is an algorithm with one or more choice points where multiple different continuations are possible, without any specification of which one will be taken. For example, here is an puzzle came from the SICP: Baker, Cooper, Fletcher, Miller, and Smith live on different floors of an apartment housethat contains only five floors. Baker does not live on the top floor. Cooper does not live onthe bottom floor. Fletcher does not live on either the top or the bottom floor. Miller lives ona higher floor than does Cooper. Smith does not live on a floor adjacent to Fletcher's.Fletcher does not live on a floor adjacent to Cooper's. Where does everyone live? After reading this I decided to build a simple nondeterministic calculation engine with .NET. The rough idea is that we can use an iterator to track each set of possible values of the parameters, and then we implement some logic inside the engine to automate the statemachine, so that we can try one combination of the values, then test it, and then move to the next. We also used a backtracking algorithm to go back when we are running out of choices at some point. Following is the core code of the engine itself: Code highlighting produced by Actipro CodeHighlighter (freeware)http://www.CodeHighlighter.com/--Public Class NonDeterministicEngine Private _paramDict As New List(Of Tuple(Of String, IEnumerator)) 'Private _predicateDict As New List(Of Tuple(Of Func(Of Object, Boolean), IEnumerable(Of String))) Private _predicateDict As New List(Of Tuple(Of Object, IList(Of String))) Public Sub AddParam(ByVal name As String, ByVal values As IEnumerable) _paramDict.Add(New Tuple(Of String, IEnumerator)(name, values.GetEnumerator())) End Sub Public Sub AddRequire(ByVal predicate As Func(Of Object, Boolean), ByVal paramNames As IList(Of String)) CheckParamCount(1, paramNames) _predicateDict.Add(New Tuple(Of Object, IList(Of String))(predicate, paramNames)) End Sub Public Sub AddRequire(ByVal predicate As Func(Of Object, Object, Boolean), ByVal paramNames As IList(Of String)) CheckParamCount(2, paramNames) _predicateDict.Add(New Tuple(Of Object, IList(Of String))(predicate, paramNames)) End Sub Public Sub AddRequire(ByVal predicate As Func(Of Object, Object, Object, Boolean), ByVal paramNames As IList(Of String)) CheckParamCount(3, paramNames) _predicateDict.Add(New Tuple(Of Object, IList(Of String))(predicate, paramNames)) End Sub Public Sub AddRequire(ByVal predicate As Func(Of Object, Object, Object, Object, Boolean), ByVal paramNames As IList(Of String)) CheckParamCount(4, paramNames) _predicateDict.Add(New Tuple(Of Object, IList(Of String))(predicate, paramNames)) End Sub Public Sub AddRequire(ByVal predicate As Func(Of Object, Object, Object, Object, Object, Boolean), ByVal paramNames As IList(Of String)) CheckParamCount(5, paramNames) _predicateDict.Add(New Tuple(Of Object, IList(Of String))(predicate, paramNames)) End Sub Public Sub AddRequire(ByVal predicate As Func(Of Object, Object, Object, Object, Object, Object, Boolean), ByVal paramNames As IList(Of String)) CheckParamCount(6, paramNames) _predicateDict.Add(New Tuple(Of Object, IList(Of String))(predicate, paramNames)) End Sub Public Sub AddRequire(ByVal predicate As Func(Of Object, Object, Object, Object, Object, Object, Object, Boolean), ByVal paramNames As IList(Of String)) CheckParamCount(7, paramNames) _predicateDict.Add(New Tuple(Of Object, IList(Of String))(predicate, paramNames)) End Sub Public Sub AddRequire(ByVal predicate As Func(Of Object, Object, Object, Object, Object, Object, Object, Object, Boolean), ByVal paramNames As IList(Of String)) CheckParamCount(8, paramNames) _predicateDict.Add(New Tuple(Of Object, IList(Of String))(predicate, paramNames)) End Sub Sub CheckParamCount(ByVal count As Integer, ByVal paramNames As IList(Of String)) If paramNames.Count <> count Then Throw New Exception("Parameter count does not match.") End If End Sub Public Property IterationOver As Boolean Private _firstTime As Boolean = True Public ReadOnly Property Current As Dictionary(Of String, Object) Get If IterationOver Then Return Nothing Else Dim _nextResult = New Dictionary(Of String, Object) For Each item In _paramDict Dim iter = item.Item2 _nextResult.Add(item.Item1, iter.Current) Next Return _nextResult End If End Get End Property Function MoveNext() As Boolean If IterationOver Then Return False End If If _firstTime Then For Each item In _paramDict Dim iter = item.Item2 iter.MoveNext() Next _firstTime = False Return True Else Dim canMoveNext = False Dim iterIndex = _paramDict.Count - 1 canMoveNext = _paramDict(iterIndex).Item2.MoveNext If canMoveNext Then Return True End If Do While Not canMoveNext iterIndex = iterIndex - 1 If iterIndex = -1 Then Return False IterationOver = True End If canMoveNext = _paramDict(iterIndex).Item2.MoveNext If canMoveNext Then For i = iterIndex + 1 To _paramDict.Count - 1 Dim iter = _paramDict(i).Item2 iter.Reset() iter.MoveNext() Next Return True End If Loop End If End Function Function GetNextResult() As Dictionary(Of String, Object) While MoveNext() Dim result = Current If Satisfy(result) Then Return result End If End While Return Nothing End Function Function Satisfy(ByVal result As Dictionary(Of String, Object)) As Boolean For Each item In _predicateDict Dim pred = item.Item1 Select Case item.Item2.Count Case 1 Dim p1 = DirectCast(pred, Func(Of Object, Boolean)) Dim v1 = result(item.Item2(0)) If Not p1(v1) Then Return False End If Case 2 Dim p2 = DirectCast(pred, Func(Of Object, Object, Boolean)) Dim v1 = result(item.Item2(0)) Dim v2 = result(item.Item2(1)) If Not p2(v1, v2) Then Return False End If Case 3 Dim p3 = DirectCast(pred, Func(Of Object, Object, Object, Boolean)) Dim v1 = result(item.Item2(0)) Dim v2 = result(item.Item2(1)) Dim v3 = result(item.Item2(2)) If Not p3(v1, v2, v3) Then Return False End If Case 4 Dim p4 = DirectCast(pred, Func(Of Object, Object, Object, Object, Boolean)) Dim v1 = result(item.Item2(0)) Dim v2 = result(item.Item2(1)) Dim v3 = result(item.Item2(2)) Dim v4 = result(item.Item2(3)) If Not p4(v1, v2, v3, v4) Then Return False End If Case 5 Dim p5 = DirectCast(pred, Func(Of Object, Object, Object, Object, Object, Boolean)) Dim v1 = result(item.Item2(0)) Dim v2 = result(item.Item2(1)) Dim v3 = result(item.Item2(2)) Dim v4 = result(item.Item2(3)) Dim v5 = result(item.Item2(4)) If Not p5(v1, v2, v3, v4, v5) Then Return False End If Case 6 Dim p6 = DirectCast(pred, Func(Of Object, Object, Object, Object, Object, Object, Boolean)) Dim v1 = result(item.Item2(0)) Dim v2 = result(item.Item2(1)) Dim v3 = result(item.Item2(2)) Dim v4 = result(item.Item2(3)) Dim v5 = result(item.Item2(4)) Dim v6 = result(item.Item2(5)) If Not p6(v1, v2, v3, v4, v5, v6) Then Return False End If Case 7 Dim p7 = DirectCast(pred, Func(Of Object, Object, Object, Object, Object, Object, Object, Boolean)) Dim v1 = result(item.Item2(0)) Dim v2 = result(item.Item2(1)) Dim v3 = result(item.Item2(2)) Dim v4 = result(item.Item2(3)) Dim v5 = result(item.Item2(4)) Dim v6 = result(item.Item2(5)) Dim v7 = result(item.Item2(6)) If Not p7(v1, v2, v3, v4, v5, v6, v7) Then Return False End If Case 8 Dim p8 = DirectCast(pred, Func(Of Object, Object, Object, Object, Object, Object, Object, Object, Boolean)) Dim v1 = result(item.Item2(0)) Dim v2 = result(item.Item2(1)) Dim v3 = result(item.Item2(2)) Dim v4 = result(item.Item2(3)) Dim v5 = result(item.Item2(4)) Dim v6 = result(item.Item2(5)) Dim v7 = result(item.Item2(6)) Dim v8 = result(item.Item2(7)) If Not p8(v1, v2, v3, v4, v5, v6, v7, v8) Then Return False End If Case Else Throw New NotSupportedException End Select Next Return True End FunctionEnd Class    And now we can use the engine to solve the problem we mentioned above:   Code highlighting produced by Actipro CodeHighlighter (freeware)http://www.CodeHighlighter.com/--Sub Test2() Dim engine = New NonDeterministicEngine() engine.AddParam("baker", {1, 2, 3, 4, 5}) engine.AddParam("cooper", {1, 2, 3, 4, 5}) engine.AddParam("fletcher", {1, 2, 3, 4, 5}) engine.AddParam("miller", {1, 2, 3, 4, 5}) engine.AddParam("smith", {1, 2, 3, 4, 5}) engine.AddRequire(Function(baker) As Boolean Return baker <> 5 End Function, {"baker"}) engine.AddRequire(Function(cooper) As Boolean Return cooper <> 1 End Function, {"cooper"}) engine.AddRequire(Function(fletcher) As Boolean Return fletcher <> 1 And fletcher <> 5 End Function, {"fletcher"}) engine.AddRequire(Function(miller, cooper) As Boolean 'Return miller = cooper + 1 Return miller > cooper End Function, {"miller", "cooper"}) engine.AddRequire(Function(smith, fletcher) As Boolean Return smith <> fletcher + 1 And smith <> fletcher - 1 End Function, {"smith", "fletcher"}) engine.AddRequire(Function(fletcher, cooper) As Boolean Return fletcher <> cooper + 1 And fletcher <> cooper - 1 End Function, {"fletcher", "cooper"}) engine.AddRequire(Function(a, b, c, d, e) As Boolean Return a <> b And a <> c And a <> d And a <> e And b <> c And b <> d And b <> e And c <> d And c <> e And d <> e End Function, {"baker", "cooper", "fletcher", "miller", "smith"}) Dim result = engine.GetNextResult() While Not result Is Nothing Console.WriteLine(String.Format("baker: {0}, cooper: {1}, fletcher: {2}, miller: {3}, smith: {4}", result("baker"), result("cooper"), result("fletcher"), result("miller"), result("smith"))) result = engine.GetNextResult() End While Console.WriteLine("Calculation ended.")End Sub   Also, this engine can solve the classic 8 queens puzzle and find out all 92 results for me.   Code highlighting produced by Actipro CodeHighlighter (freeware)http://www.CodeHighlighter.com/--Sub Test3() ' The 8-Queens problem. Dim engine = New NonDeterministicEngine() ' Let's assume that a - h represents the queens in row 1 to 8, then we just need to find out the column number for each of them. engine.AddParam("a", {1, 2, 3, 4, 5, 6, 7, 8}) engine.AddParam("b", {1, 2, 3, 4, 5, 6, 7, 8}) engine.AddParam("c", {1, 2, 3, 4, 5, 6, 7, 8}) engine.AddParam("d", {1, 2, 3, 4, 5, 6, 7, 8}) engine.AddParam("e", {1, 2, 3, 4, 5, 6, 7, 8}) engine.AddParam("f", {1, 2, 3, 4, 5, 6, 7, 8}) engine.AddParam("g", {1, 2, 3, 4, 5, 6, 7, 8}) engine.AddParam("h", {1, 2, 3, 4, 5, 6, 7, 8}) Dim NotInTheSameDiagonalLine = Function(cols As IList) As Boolean For i = 0 To cols.Count - 2 For j = i + 1 To cols.Count - 1 If j - i = Math.Abs(cols(j) - cols(i)) Then Return False End If Next Next Return True End Function engine.AddRequire(Function(a, b, c, d, e, f, g, h) As Boolean Return a <> b AndAlso a <> c AndAlso a <> d AndAlso a <> e AndAlso a <> f AndAlso a <> g AndAlso a <> h AndAlso b <> c AndAlso b <> d AndAlso b <> e AndAlso b <> f AndAlso b <> g AndAlso b <> h AndAlso c <> d AndAlso c <> e AndAlso c <> f AndAlso c <> g AndAlso c <> h AndAlso d <> e AndAlso d <> f AndAlso d <> g AndAlso d <> h AndAlso e <> f AndAlso e <> g AndAlso e <> h AndAlso f <> g AndAlso f <> h AndAlso g <> h AndAlso NotInTheSameDiagonalLine({a, b, c, d, e, f, g, h}) End Function, {"a", "b", "c", "d", "e", "f", "g", "h"}) Dim result = engine.GetNextResult() While Not result Is Nothing Console.WriteLine("(1,{0}), (2,{1}), (3,{2}), (4,{3}), (5,{4}), (6,{5}), (7,{6}), (8,{7})", result("a"), result("b"), result("c"), result("d"), result("e"), result("f"), result("g"), result("h")) result = engine.GetNextResult() End While Console.WriteLine("Calculation ended.")End Sub (Chinese version of the post: http://www.cnblogs.com/RChen/archive/2010/05/17/1737587.html) Cheers,  

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• Productivity Tips

  - by Brian T. Jackett

  A few months ago during my first end of year review at Microsoft I was doing an assessment of my year.  One of my personal goals to come out of this reflection was to improve my personal productivity.  While I hear many people say “I wish I had more hours in the day so that I could get more done” I feel like that is the wrong approach.  There is an inherent assumption that you are being productive with your time that you already have and thus more time would allow you to be as productive given more time.    Instead of wishing I could add more hours to the day I’ve begun adopting a number of processes or behavior changes in my personal life to make better use of my time with the goal of improving productivity.  The areas of focus are as follows: Focus Processes Tools Personal health Email Note: A number of these topics have spawned from reading Scott Hanselman’s blog posts on productivity, reading of David Allen’s book Getting Things Done, and discussions with friends and coworkers who had great insights into this topic.   Focus Pre-reading / viewing: Overcome your work addiction Millennials paralyzed by choice Its Not What You Read Its What You Ignore (Scott Hanselman video)    I highly recommend Scott Hanselman’s video above and this post before continuing with this article.  It is well worth the 40+ mins price of admission for the video and couple minutes for article.  One key takeaway for me was listing out my activities in an average week and realizing which ones held little or no value to me.  We all have a finite amount of time to work each day.  Do you know how much time and effort you spend on various aspects of your life (family, friends, religion, work, personal happiness, etc.)?  Do your actions and commitments reflect your priorities?    The biggest time consumers with little value for me were time spent on social media services (Twitter and Facebook), playing an MMO video game, and watching TV.  I still check up on Facebook, Twitter, Microsoft internal chat forums, and other services to keep contact with others but I’ve reduced that time significantly.  As for TV I’ve cut the cord and no longer subscribe to cable TV.  Instead I use Netflix, RedBox, and over the air channels but again with reduced time consumption.  With the time I’ve freed up I’m back to working out 2-3 times a week and reading 4 nights a week (both of which I had been neglecting previously).  I’ll mention a few tools for helping measure your time in the Tools section.   Processes    Do not multi-task.  I’ll say it again.  Do not multi-task.  There is no such thing as multi tasking.  The human brain is optimized to work on one thing at a time.  When you are “multi-tasking” you are really doing 2 or more things at less than 100%, usually by a wide margin.  I take pride in my work and when I’m doing something less than 100% the results typically degrade rapidly.    Now there are some ways of bending the rules of physics for this one.  There is the notion of getting a double amount of work done in the same timeframe.  Some examples would be listening to podcasts / watching a movie while working out, using a treadmill as your work desk, or reading while in the bathroom.    Personally I’ve found good results in combining one task that does not require focus (making dinner, playing certain video games, working out) and one task that does (watching a movie, listening to podcasts).  I believe this is related to me being a visual and kinesthetic (using my hands or actually doing it) learner.  I’m terrible with auditory learning.  My fiance and I joke that sometimes we talk and talk to each other but never really hear each other.   Goals / Tasks    Goals can give us direction in life and a sense of accomplishment when we complete them.  Goals can also overwhelm us and give us a sense of failure when we don’t complete them.  I propose that you shift your perspective and not dwell on all of the things that you haven’t gotten done, but focus instead on regularly setting measureable goals that are within reason of accomplishing.    At the end of each time frame have a retrospective to review your progress.  Do not feel guilty about what you did not accomplish.  Feel proud of what you did accomplish and readjust your goals for the next time frame to more attainable goals.  Here is a sample schedule I’ve seen proposed by some.  I have not consistently set goals for each timeframe, but I do typically set 3 small goals a day (this blog post is #2 for today). Each day set 3 small goals Each week set 3 medium goals Each month set 1 large goal Each year set 2 very large goals   Tools    Tools are an extension of our human body.  They help us extend beyond what we can physically and mentally do.  Below are some tools I use almost daily or have found useful as of late. Disclaimer: I am not getting endorsed to promote any of these products.  I just happen to like them and find them useful. Instapaper – Save internet links for reading later.  There are many tools like this but I’ve found this to be a great one.  There is even a “read it later” JavaScript button you can add to your browser so when you navigate to a site it will then add this to your list. Stacks for Instapaper – A Windows Phone 7 app for reading my Instapaper articles on the go.  It does require a subscription to Instapaper (nominal $3 every three months) but is easily worth the cost.  Alternatively you can set up your Kindle to sync with Instapaper easily but I haven’t done so. SlapDash Podcast – Apps for Windows Phone and  Windows 8 (possibly other platforms) to sync podcast viewing / listening across multiple devices.  Now that I have my Surface RT device (which I love) this is making my consumption easier to manage. Feed Reader – Simple Windows 8 app for quickly catching up on my RSS feeds.  I used to have hundreds of unread items all the time.  Now I’m down to 20-50 regularly and it is much easier and faster to consume on my Surface RT.  There is also a free version (which I use) and I can’t see much different between the free and paid versions currently. Rescue Time – Have you ever wondered how much time you’ve spent on websites vs. email vs. “doing work”?  This service tracks your computer actions and then lets you report on them.  This can help you quantitatively identify areas where your actions are not in line with your priorities. PowerShell – Windows automation tool.  It is now built into every client and server OS.  This tool has saved me days (and I mean the full 24 hrs worth) of time and effort in the past year alone.  If you haven’t started learning PowerShell and you administrating any Windows OS or server product you need to start today. Various blogging tools – I wrote a post a couple years ago called How I Blog about my blogging process and tools used.  Almost all of it still applies today.   Personal Health    Some of these may be common sense or debatable, but I’ve found them to help prioritize my daily activities. Get plenty of sleep on a regular basis.  Sacrificing sleep too many nights a week negatively impacts your cognition, attitude, and overall health. Exercise at least three days.  Exercise could be lifting weights, taking the stairs up multiple flights of stairs, walking for 20 mins, or a number of other "non-traditional” activities.  I find that regular exercise helps with sleep and improves my overall attitude. Eat a well balanced diet.  Too much sugar, caffeine, junk food, etc. are not good for your body.  This is not a matter of losing weight but taking care of your body and helping you perform at your peak potential.   Email    Email can be one of the biggest time consumers (i.e. waster) if you aren’t careful. Time box your email usage.  Set a meeting invite for yourself if necessary to limit how much time you spend checking email. Use rules to prioritize your email.  Email from external customers, my manager, or include me directly on the To line go into my inbox.  Everything else goes a level down and I have 30+ rules to further sort it, mostly distribution lists. Use keyboard shortcuts (when available).  I use Outlook for my primary email and am constantly hitting Alt + S to send, Ctrl + 1 for my inbox, Ctrl + 2 for my calendar, Space / Tab / Shift + Tab to mark items as read, and a number of other useful commands.  Learn them and you’ll see your speed getting through emails increase. Keep emails short.  No one Few people like reading through long emails.  The first line should state exactly why you are sending the email followed by a 3-4 lines to support it.  Anything longer might be better suited as a phone call or in person discussion.   Conclusion    In this post I walked through various tips and tricks I’ve found for improving personal productivity.  It is a mix of re-focusing on the things that matter, using tools to assist in your efforts, and cutting out actions that are not aligned with your priorities.  I originally had a whole section on keyboard shortcuts, but with my recent purchase of the Surface RT I’m finding that touch gestures have replaced numerous keyboard commands that I used to need.  I see a big future in touch enabled devices.  Hopefully some of these tips help you out.  If you have any tools, tips, or ideas you would like to share feel free to add in the comments section.         -Frog Out   Links Scott Hanselman Productivity posts http://www.hanselman.com/blog/CategoryView.aspx?category=Productivity Overcome your work addiction http://blogs.hbr.org/hbsfaculty/2012/05/overcome-your-work-addiction.html?awid=5512355740280659420-3271   Millennials paralyzed by choice http://priyaparker.com/blog/millennials-paralyzed-by-choice   Its Not What You Read Its What You Ignore (video) http://www.hanselman.com/blog/ItsNotWhatYouReadItsWhatYouIgnoreVideoOfScottHanselmansPersonalProductivityTips.aspx   Cutting the cord – Jeff Blankenburg http://www.jeffblankenburg.com/2011/04/06/cutting-the-cord/   Building a sitting standing desk – Eric Harlan http://www.ericharlan.com/Everything_Else/building-a-sitting-standing-desk-a229.html   Instapaper http://www.instapaper.com/u   Stacks for Instapaper http://www.stacksforinstapaper.com/   Slapdash Podcast Windows Phone -  http://www.windowsphone.com/en-us/store/app/slapdash-podcasts/90e8b121-080b-e011-9264-00237de2db9e Windows 8 - http://apps.microsoft.com/webpdp/en-us/app/slapdash-podcasts/0c62e66a-f2e4-4403-af88-3430a821741e/m/ROW   Feed Reader http://apps.microsoft.com/webpdp/en-us/app/feed-reader/d03199c9-8e08-469a-bda1-7963099840cc/m/ROW   Rescue Time http://www.rescuetime.com/   PowerShell Script Center http://technet.microsoft.com/en-us/scriptcenter/bb410849.aspx

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• That Escalated Quickly

  - by Jesse Taber

  Originally posted on: http://geekswithblogs.net/GruffCode/archive/2014/05/17/that-escalated-quickly.aspxI have been working remotely out of my home for over 4 years now. All of my coworkers during that time have also worked remotely. Lots of folks have written about the challenges inherent in facilitating communication on remote teams and strategies for overcoming them. A popular theme around this topic is the notion of “escalating communication”. In this context “escalating” means taking a conversation from one mode of communication to a different, higher fidelity mode of communication. Here are the five modes of communication I use at work in order of increasing fidelity: Email – This is the “lowest fidelity” mode of communication that I use. I usually only check it a few times a day (and I’m trying to check it even less frequently than that) and I only keep items in my inbox if they represent an item I need to take action on that I haven’t tracked anywhere else. Forums / Message boards – Being a developer, I’ve gotten into the habit of having other people look over my code before it becomes part of the product I’m working on. These code reviews often happen in “real time” via screen sharing, but I also always have someone else give all of the changes another look using pull requests. A pull request takes my code and lets someone else see the changes I’ve made side-by-side with the existing code so they can see if I did anything dumb. Pull requests can facilitate a conversation about the code changes in an online-forum like style. Some teams I’ve worked on also liked using tools like Trello or Google Groups to have on-going conversations about a topic or task that was being worked on. Chat & Instant Messaging  - Chat and instant messaging are the real workhorses for communication on the remote teams I’ve been a part of. I know some teams that are co-located that also use it pretty extensively for quick messages that don’t warrant walking across the office to talk with someone but reqire more immediacy than an e-mail. For the purposes of this post I think it’s important to note that the terms “chat” and “instant messaging” might insinuate that the conversation is happening in real time, but that’s not always true. Modern chat and IM applications maintain a searchable history so people can easily see what might have been discussed while they were away from their computers. Voice, Video and Screen sharing – Everyone’s got a camera and microphone on their computers now, and there are an abundance of services that will let you use them to talk to other people who have cameras and microphones on their computers. I’m including screen sharing here as well because, in my experience, these discussions typically involve one or more people showing the other participants something that’s happening on their screen. Obviously, this mode of communication is much higher-fidelity than any of the ones listed above. Scheduled meetings are typically conducted using this mode of communication. In Person – No matter how great communication tools become, there’s no substitute for meeting with someone face-to-face. However, opportunities for this kind of communcation are few and far between when you work on a remote team. When a conversation gets escalated that usually means it moves up one or more positions on this list. A lot of people advocate jumping to #4 sooner than later. Like them, I used to believe that, if it was possible, organizing a call with voice and video was automatically better than any kind of text-based communication could be. Lately, however, I’m becoming less convinced that escalating is always the right move. Working Asynchronously Last year I attended a talk at our local code camp given by Drew Miller. Drew works at GitHub and was talking about how they use GitHub internally. Many of the folks at GitHub work remotely, so communication was one of the main themes in Drew’s talk. During the talk Drew used the phrase, “asynchronous communication” to describe their use of chat and pull request comments. That phrase stuck in my head because I hadn’t heard it before but I think it perfectly describes the way in which remote teams often need to communicate. You don’t always know when your co-workers are at their computers or what hours (if any) they are working that day. In order to work this way you need to assume that the person you’re talking to might not respond right away. You can’t always afford to wait until everyone required is online and available to join a voice call, so you need to use text-based, persistent forms of communication so that people can receive and respond to messages when they are available. Going back to my list from the beginning of this post for a second, I characterize items #1-3 as being “asynchronous” modes of communication while we could call items #4 and #5 “synchronous”. When communication gets escalated it’s almost always moving from an asynchronous mode of communication to a synchronous one. Now, to the point of this post: I’ve become increasingly reluctant to escalate from asynchronous to synchronous communication for two primary reasons: 1 – You can often find a higher fidelity way to convey your message without holding a synchronous conversation 2 - Asynchronous modes of communication are (usually) persistent and searchable. You Don’t Have to Broadcast Live Let’s start with the first reason I’ve listed. A lot of times you feel like you need to escalate to synchronous communication because you’re having difficulty describing something that you’re seeing in words. You want to provide the people you’re conversing with some audio-visual aids to help them understand the point that you’re trying to make and you think that getting on Skype and sharing your screen with them is the best way to do that. Firing up a screen sharing session does work well, but you can usually accomplish the same thing in an asynchronous manner. For example, you could take a screenshot and annotate it with some text and drawings to illustrate what it is you’re seeing. If a screenshot won’t work, taking a short screen recording while your narrate over it and posting the video to your forum or chat system along with a text-based description of what’s in the recording that can be searched for later can be a great way to effectively communicate with your team asynchronously. I Said What?!? Now for the second reason I listed: most asynchronous modes of communication provide a transcript of what was said and what decisions might have been made during the conversation. There have been many occasions where I’ve used the search feature of my team’s chat application to find a conversation that happened several weeks or months ago to remember what was decided. Unfortunately, I think the benefits associated with the persistence of communicating asynchronously often get overlooked when people decide to escalate to a in-person meeting or voice/video call. I’m becoming much more reluctant to suggest a voice or video call if I suspect that it might lead to codifying some kind of design decision because everyone involved is going to hang up the call and immediately forget what was decided. I recognize that you can record and archive these types of interactions, but without being able to search them the recordings aren’t terribly useful. When and How To Escalate I don’t mean to imply that communicating via voice/video or in person is never a good idea. I probably jump on a Skype call with a co-worker at least once a day to quickly hash something out or show them a bit of code that I’m working on. Also, meeting in person periodically is really important for remote teams. There’s no way around the fact that sometimes it’s easier to jump on a call and show someone my screen so they can see what I’m seeing. So when is it right to escalate? I think the simplest way to answer that is when the communication starts to feel painful. Everyone’s tolerance for that pain is different, but I think you need to let it hurt a little bit before jumping to synchronous communication. When you do escalate from asynchronous to synchronous communication, there are a couple of things you can do to maximize the effectiveness of the communication: Takes notes – This is huge and yet I’ve found that a lot of teams don’t do this. If you’re holding a meeting with  > 2 people you should have someone taking notes. Taking notes while participating in a meeting can be difficult but there are a few strategies to deal with this challenge that probably deserve a short post of their own. After the meeting, make sure the notes are posted to a place where all concerned parties (including those that might not have attended the meeting) can review and search them. Persist decisions made ASAP – If any decisions were made during the meeting, persist those decisions to a searchable medium as soon as possible following the conversation. All the teams I’ve worked on used a web-based system for tracking the on-going work and a backlog of work to be done in the future. I always try to make sure that all of the cards/stories/tasks/whatever in these systems always reflect the latest decisions that were made as the work was being planned and executed. If held a quick call with your team lead and decided that it wasn’t worth the effort to build real-time validation into that new UI you were working on, go and codify that decision in the story associated with that work immediately after you hang up. Even better, write it up in the story while you are both still on the phone. That way when the folks from your QA team pick up the story to test a few days later they’ll know why the real-time validation isn’t there without having to invoke yet another conversation about the work. Communicating Well is Hard At this point you might be thinking that communicating asynchronously is more difficult than having a live conversation. You’re right: it is more difficult. In order to communicate effectively this way you need to very carefully think about the message that you’re trying to convey and craft it in a way that’s easy for your audience to understand. This is almost always harder than just talking through a problem in real time with someone; this is why escalating communication is such a popular idea. Why wouldn’t we want to do the thing that’s easier? Easier isn’t always better. If you and your team can get in the habit of communicating effectively in an asynchronous manner you’ll find that, over time, all of your communications get less painful because you don’t need to re-iterate previously made points over and over again. If you communicate right the first time, you often don’t need to rehash old conversations because you can go back and find the decisions that were made laid out in plain language. You’ll also find that you get better at doing things like writing useful comments in your code, creating written documentation about how the feature that you just built works, or persuading your team to do things in a certain way.

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• BizTalk and SQL: Alternatives to the SQL receive adapter. Using Msmq to receive SQL data

  - by Leonid Ganeline

  If we have to get data from the SQL database, the standard way is to use a receive port with SQL adapter. SQL receive adapter is a solicit-response adapter. It periodically polls the SQL database with queries. That’s only way it can work. Sometimes it is undesirable. With new WCF-SQL adapter we can use the lightweight approach but still with the same principle, the WCF-SQL adapter periodically solicits the database with queries to check for the new records. Imagine the situation when the new records can appear in very broad time limits, some - in a second interval, others - in the several minutes interval. Our requirement is to process the new records ASAP. That means the polling interval should be near the shortest interval between the new records, a second interval. As a result the most of the poll queries would return nothing and would load the database without good reason. If the database is working under heavy payload, it is very undesirable. Do we have other choices? Sure. We can change the polling to the “eventing”. The good news is the SQL server could issue the event in case of new records with triggers. Got a new record –the trigger event is fired. No new records – no the trigger events – no excessive load to the database. The bad news is the SQL Server doesn’t have intrinsic methods to send the event data outside. For example, we would rather use the adapters that do listen for the data and do not solicit. There are several such adapters-listeners as File, Ftp, SOAP, WCF, and Msmq. But the SQL Server doesn’t have methods to create and save files, to consume the Web-services, to create and send messages in the queue, does it? Can we use the File, FTP, Msmq, WCF adapters to get data from SQL code? Yes, we can. The SQL Server 2005 and 2008 have the possibility to use .NET code inside SQL code. See the SQL Integration. How it works for the Msmq, for example: ·         New record is created, trigger is fired ·         Trigger calls the CLR stored procedure and passes the message parameters to it ·         The CLR stored procedure creates message and sends it to the outgoing queue in the SQL Server computer. ·         Msmq service transfers message to the queue in the BizTalk Server computer. ·         WCF-NetMsmq adapter receives the message from this queue. For the File adapter the idea is the same, the CLR stored procedure creates and stores the file with message, and then the File adapter picks up this file. Using WCF-NetMsmq adapter to get data from SQL I am describing the full set of the deployment and development steps for the case with the WCF-NetMsmq adapter. Development: 1.       Create the .NET code: project, class and method to create and send the message to the MSMQ queue. 2.       Create the SQL code in triggers to call the .NET code. Installation and Deployment: 1.       SQL Server: a.       Register the CLR assembly with .NET (CLR) code b.      Install the MSMQ Services 2.       BizTalk Server: a.       Install the MSMQ Services b.      Create the MSMQ queue c.       Create the WCF-NetMsmq receive port. The detailed description is below. Code .NET code … using System.Xml; using System.Xml.Linq; using System.Xml.Serialization;   //namespace MyCompany.MySolution.MyProject – doesn’t work. The assembly name is MyCompany.MySolution.MyProject // I gave up with the compound namespace. Seems the CLR Integration cannot work with it L. Maybe I’m wrong.     public class Event     {         static public XElement CreateMsg(int par1, int par2, int par3)         {             XNamespace ns = "http://schemas.microsoft.com/Sql/2008/05/TypedPolling/my_storedProc";             XElement xdoc =                 new XElement(ns + "TypedPolling",                     new XElement(ns + "TypedPollingResultSet0",                         new XElement(ns + "TypedPollingResultSet0",                             new XElement(ns + "par1", par1),                             new XElement(ns + "par2", par2),                             new XElement(ns + "par3", par3),                         )                     )                 );             return xdoc;         }     }   //////////////////////////////////////////////////////////////////////// … using System.ServiceModel; using System.ServiceModel.Channels; using System.Transactions; using System.Data; using System.Data.Sql; using System.Data.SqlTypes;   public class MsmqHelper {     [Microsoft.SqlServer.Server.SqlProcedure]     // msmqAddress as "net.msmq://localhost/private/myapp.myqueue";     public static void SendMsg(string msmqAddress, string action, int par1, int par2, int par3)     {         using (TransactionScope scope = new TransactionScope(TransactionScopeOption.Suppress))         {             NetMsmqBinding binding = new NetMsmqBinding(NetMsmqSecurityMode.None);             binding.ExactlyOnce = true;             EndpointAddress address = new EndpointAddress(msmqAddress);               using (ChannelFactory<IOutputChannel> factory = new ChannelFactory<IOutputChannel>(binding, address))             {                 IOutputChannel channel = factory.CreateChannel();                 try                 {                     XElement xe = Event.CreateMsg(par1, par2, par3);                     XmlReader xr = xe.CreateReader();                     Message msg = Message.CreateMessage(MessageVersion.Default, action, xr);                     channel.Send(msg);                     //SqlContext.Pipe.Send(…); // to test                 }                 catch (Exception ex)                 { …                 }             }             scope.Complete();         }     }   SQL code in triggers   -- sp_SendMsg was registered as a name of the MsmqHelper.SendMsg() EXEC sp_SendMsg'net.msmq://biztalk_server_name/private/myapp.myqueue', 'Create', @par1, @par2, @par3   Installation and Deployment On the SQL Server Registering the CLR assembly 1.       Prerequisites: .NET 3.5 SP1 Framework. It could be the issue for the production SQL Server! 2.       For more information, please, see the link http://nielsb.wordpress.com/sqlclrwcf/ 3.       Copy files: >copy “\Windows\Microsoft.net\Framework\v3.0\Windows Communication Foundation\Microsoft.Transactions.Bridge.dll” “\Program Files\Reference Assemblies\Microsoft\Framework\v3.0 \Microsoft.Transactions.Bridge.dll” If your machine is a 64-bit, run two commands: >copy “\Windows\Microsoft.net\Framework\v3.0\Windows Communication Foundation\Microsoft.Transactions.Bridge.dll” “\Program Files (x86)\Reference Assemblies\Microsoft\Framework\v3.0 \Microsoft.Transactions.Bridge.dll” >copy “\Windows\Microsoft.net\Framework64\v3.0\Windows Communication Foundation\Microsoft.Transactions.Bridge.dll” “\Program Files\Reference Assemblies\Microsoft\Framework\v3.0 \Microsoft.Transactions.Bridge.dll” 4.       Execute the SQL code to register the .NET assemblies: -- For x64 OS: CREATE ASSEMBLY SMdiagnostics AUTHORIZATION dbo FROM 'C:\Windows\Microsoft.NET\Framework\v3.0\Windows Communication Foundation\SMdiagnostics.dll' WITH permission_set = unsafe CREATE ASSEMBLY [System.Web] AUTHORIZATION dbo FROM 'C:\Windows\Microsoft.NET\Framework64\v2.0.50727\System.Web.dll' WITH permission_set = unsafe CREATE ASSEMBLY [System.Messaging] AUTHORIZATION dbo FROM 'C:\Windows\Microsoft.NET\Framework\v2.0.50727\System.Messaging.dll' WITH permission_set = unsafe CREATE ASSEMBLY [System.ServiceModel] AUTHORIZATION dbo FROM 'C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\v3.0\System.ServiceModel.dll' WITH permission_set = unsafe CREATE ASSEMBLY [System.Xml.Linq] AUTHORIZATION dbo FROM 'C:\Program Files\Reference Assemblies\Microsoft\Framework\v3.5\System.Xml.Linq.dll' WITH permission_set = unsafe   -- For x32 OS: --CREATE ASSEMBLY SMdiagnostics AUTHORIZATION dbo FROM 'C:\Windows\Microsoft.NET\Framework\v3.0\Windows Communication Foundation\SMdiagnostics.dll' WITH permission_set = unsafe --CREATE ASSEMBLY [System.Web] AUTHORIZATION dbo FROM 'C:\Windows\Microsoft.NET\Framework\v2.0.50727\System.Web.dll' WITH permission_set = unsafe --CREATE ASSEMBLY [System.Messaging] AUTHORIZATION dbo FROM 'C:\Windows\Microsoft.NET\Framework\v2.0.50727\System.Messaging.dll' WITH permission_set = unsafe --CREATE ASSEMBLY [System.ServiceModel] AUTHORIZATION dbo FROM 'C:\Program Files\Reference Assemblies\Microsoft\Framework\v3.0\System.ServiceModel.dll' WITH permission_set = unsafe 5.       Register the assembly with the external stored procedure: CREATE ASSEMBLY [HelperClass] AUTHORIZATION dbo FROM ’<FilePath>MyCompany.MySolution.MyProject.dll' WITH permission_set = unsafe where the <FilePath> - the path of the file on this machine! 6. Create the external stored procedure CREATE PROCEDURE sp_SendMsg (        @msmqAddress nvarchar(100),        @Action NVARCHAR(50),        @par1 int,        @par2 int,        @par3 int ) AS EXTERNAL NAME HelperClear.MsmqHelper.SendMsg   Installing the MSMQ Services 1.       Check if the MSMQ service is NOT installed. To check:  Start / Administrative Tools / Computer Management, on the left pane open the “Services and Applications”, search to the “Message Queuing”. If you cannot see it, follow next steps. 2.       Start / Control Panel / Programs and Features 3.       Click “Turn Windows Features on or off” 4.       Click Features, click “Add Features” 5.       Scroll down the feature list; open the “Message Queuing” / “Message Queuing Services”; and check the “Message Queuing Server” option  6.       Click Next; Click Install; wait to the successful finish of the installation Creating the MSMQ queue We don’t need to create the queue on the “sender” side. On the BizTalk Server Installing the MSMQ Services The same is as for the SQL Server. Creating the MSMQ queue 1.       Start / Administrative Tools / Computer Management, on the left pane open the “Services and Applications”, open the “Message Queuing”, and open the “Private Queues”. 2.       Right-click the “Private Queues”; choose New; choose “Private Queue”. 3.       Type the Queue name as ’myapp.myqueue'; check the “Transactional” option. Creating the WCF-NetMsmq receive port I will not go through this step in all details. It is straightforward. URI for this receive location should be 'net.msmq://localhost/private/myapp.myqueue'. Notes ·         The biggest problem is usually on the step the “Registering the CLR assembly”. It is hard to predict where are the assemblies from the assembly list, what version should be used, x86 or x64. It is pity of such “rude” integration of the SQL with .NET. ·         In couple cases the new WCF-NetMsmq port was not able to work with the queue. Try to replace the WCF- NetMsmq port with the WCF-Custom port with netMsmqBinding. It was working fine for me. ·         To test how messages go through the queue you can turn on the Journal /Enabled option for the queue. I used the QueueExplorer utility to look to the messages in Journal. The Computer Management can also show the messages but it shows only small part of the message body and in the weird format. The QueueExplorer can do the better job; it shows the whole body and Xml messages are in good color format.

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• Of transactions and Mongo

  - by Nuri Halperin

  Originally posted on: http://geekswithblogs.net/nuri/archive/2014/05/20/of-transactions-and-mongo-again.aspxWhat's the first thing you hear about NoSQL databases? That they lose your data? That there's no transactions? No joins? No hope for "real" applications? Well, you *should* be wondering whether a certain of database is the right one for your job. But if you do so, you should be wondering that about "traditional" databases as well! In the spirit of exploration let's take a look at a common challenge: You are a bank. You have customers with accounts. Customer A wants to pay B. You want to allow that only if A can cover the amount being transferred. Let's looks at the problem without any context of any database engine in mind. What would you do? How would you ensure that the amount transfer is done "properly"? Would you prevent a "transaction" from taking place unless A can cover the amount? There are several options: Prevent any change to A's account while the transfer is taking place. That boils down to locking. Apply the change, and allow A's balance to go below zero. Charge person A some interest on the negative balance. Not friendly, but certainly a choice. Don't do either. Options 1 and 2 are difficult to attain in the NoSQL world. Mongo won't save you headaches here either. Option 3 looks a bit harsh. But here's where this can go: ledger. See, and account doesn't need to be represented by a single row in a table of all accounts with only the current balance on it. More often than not, accounting systems use ledgers. And entries in ledgers - as it turns out – don't actually get updated. Once a ledger entry is written, it is not removed or altered. A transaction is represented by an entry in the ledger stating and amount withdrawn from A's account and an entry in the ledger stating an addition of said amount to B's account. For sake of space-saving, that entry in the ledger can happen using one entry. Think {Timestamp, FromAccountId, ToAccountId, Amount}. The implication of the original question – "how do you enforce non-negative balance rule" then boils down to: Insert entry in ledger Run validation of recent entries Insert reverse entry to roll back transaction if validation failed. What is validation? Sum up the transactions that A's account has (all deposits and debits), and ensure the balance is positive. For sake of efficiency, one can roll up transactions and "close the book" on transactions with a pseudo entry stating balance as of midnight or something. This lets you avoid doing math on the fly on too many transactions. You simply run from the latest "approved balance" marker to date. But that's an optimization, and premature optimizations are the root of (some? most?) evil.. Back to some nagging questions though: "But mongo is only eventually consistent!" Well, yes, kind of. It's not actually true that Mongo has not transactions. It would be more descriptive to say that Mongo's transaction scope is a single document in a single collection. A write to a Mongo document happens completely or not at all. So although it is true that you can't update more than one documents "at the same time" under a "transaction" umbrella as an atomic update, it is NOT true that there' is no isolation. So a competition between two concurrent updates is completely coherent and the writes will be serialized. They will not scribble on the same document at the same time. In our case - in choosing a ledger approach - we're not even trying to "update" a document, we're simply adding a document to a collection. So there goes the "no transaction" issue. Now let's turn our attention to consistency. What you should know about mongo is that at any given moment, only on member of a replica set is writable. This means that the writable instance in a set of replicated instances always has "the truth". There could be a replication lag such that a reader going to one of the replicas still sees "old" state of a collection or document. But in our ledger case, things fall nicely into place: Run your validation against the writable instance. It is guaranteed to have a ledger either with (after) or without (before) the ledger entry got written. No funky states. Again, the ledger writing *adds* a document, so there's no inconsistent document state to be had either way. Next, we might worry about data loss. Here, mongo offers several write-concerns. Write-concern in Mongo is a mode that marshals how uptight you want the db engine to be about actually persisting a document write to disk before it reports to the application that it is "done". The most volatile, is to say you don't care. In that case, mongo would just accept your write command and say back "thanks" with no guarantee of persistence. If the server loses power at the wrong moment, it may have said "ok" but actually no written the data to disk. That's kind of bad. Don't do that with data you care about. It may be good for votes on a pole regarding how cute a furry animal is, but not so good for business. There are several other write-concerns varying from flushing the write to the disk of the writable instance, flushing to disk on several members of the replica set, a majority of the replica set or all of the members of a replica set. The former choice is the quickest, as no network coordination is required besides the main writable instance. The others impose extra network and time cost. Depending on your tolerance for latency and read-lag, you will face a choice of what works for you. It's really important to understand that no data loss occurs once a document is flushed to an instance. The record is on disk at that point. From that point on, backup strategies and disaster recovery are your worry, not loss of power to the writable machine. This scenario is not different from a relational database at that point. Where does this leave us? Oh, yes. Eventual consistency. By now, we ensured that the "source of truth" instance has the correct data, persisted and coherent. But because of lag, the app may have gone to the writable instance, performed the update and then gone to a replica and looked at the ledger there before the transaction replicated. Here are 2 options to deal with this. Similar to write concerns, mongo support read preferences. An app may choose to read only from the writable instance. This is not an awesome choice to make for every ready, because it just burdens the one instance, and doesn't make use of the other read-only servers. But this choice can be made on a query by query basis. So for the app that our person A is using, we can have person A issue the transfer command to B, and then if that same app is going to immediately as "are we there yet?" we'll query that same writable instance. But B and anyone else in the world can just chill and read from the read-only instance. They have no basis to expect that the ledger has just been written to. So as far as they know, the transaction hasn't happened until they see it appear later. We can further relax the demand by creating application UI that reacts to a write command with "thank you, we will post it shortly" instead of "thank you, we just did everything and here's the new balance". This is a very powerful thing. UI design for highly scalable systems can't insist that the all databases be locked just to paint an "all done" on screen. People understand. They were trained by many online businesses already that your placing of an order does not mean that your product is already outside your door waiting (yes, I know, large retailers are working on it... but were' not there yet). The second thing we can do, is add some artificial delay to a transaction's visibility on the ledger. The way that works is simply adding some logic such that the query against the ledger never nets a transaction for customers newer than say 15 minutes and who's validation flag is not set. This buys us time 2 ways: Replication can catch up to all instances by then, and validation rules can run and determine if this transaction should be "negated" with a compensating transaction. In case we do need to "roll back" the transaction, the backend system can place the timestamp of the compensating transaction at the exact same time or 1ms after the original one. Effectively, once A or B visits their ledger, both transactions would be visible and the overall balance "as of now" would reflect no change.  The 2 transactions (attempted/ reverted) would be visible , since we do actually account for the attempt. Hold on a second. There's a hole in the story: what if several transfers from A to some accounts are registered, and 2 independent validators attempt to compute the balance concurrently? Is there a chance that both would conclude non-sufficient-funds even though rolling back transaction 100 would free up enough for transaction 117 (some random later transaction)? Yes. there is that chance. But the integrity of the business rule is not compromised, since the prime rule is don't dispense money you don't have. To minimize or eliminate this scenario, we can also assign a single validation process per origin account. This may seem non-scalable, but it can easily be done as a "sharded" distribution. Say we have 11 validation threads (or processing nodes etc.). We divide the account number space such that each validator is exclusively responsible for a certain range of account numbers. Sounds cunningly similar to Mongo's sharding strategy, doesn't it? Each validator then works in isolation. More capacity needed? Chop the account space into more chunks. So where  are we now with the nagging questions? "No joins": Huh? What are those for? "No transactions": You mean no cross-collection and no cross-document transactions? Granted - but don't always need them either. "No hope for real applications": well... There are more issues and edge cases to slog through, I'm sure. But hopefully this gives you some ideas of how to solve common problems without distributed locking and relational databases. But then again, you can choose relational databases if they suit your problem.

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• "Exception: msg 'axis2:null', not-found" when using a suds client with an axis2 server

  - by konrad

  I am writing a Suds (Python) SOAP client for an Axis2 server I have no control over. Suds chokes on the WSDL file with the following exception: File "site-packages/suds/wsdl.py", line 494, in resolve raise Exception("msg '%s', not-found" % op.input) Exception: msg 'axis2:null', not-found This is the WSDL file (I have replaced the hostnames with localhost). Any clue on how to fix this with the ImportDoctor? <?xml version="1.0" encoding="UTF-8"?> <wsdl:definitions xmlns:wsdl="http://schemas.xmlsoap.org/wsdl/" xmlns:axis2="http://ws.apache.org/axis2" xmlns:wsaw="http://www.w3.org/2006/05/addressing/wsdl" xmlns:http="http://schemas.xmlsoap.org/wsdl/http/" xmlns:soap="http://schemas.xmlsoap.org/wsdl/soap/" xmlns:mime="http://schemas.xmlsoap.org/wsdl/mime/" xmlns:soap12="http://schemas.xmlsoap.org/wsdl/soap12/" targetNamespace="http://ws.apache.org/axis2"> <wsdl:types/> <wsdl:portType name="__SynapseServicePortType"> <wsdl:operation name="mediate"> <wsdl:input message="axis2:null" wsaw:Action="urn:mediate"/> <wsdl:output message="axis2:null" wsaw:Action="urn:mediateResponse"/> </wsdl:operation> </wsdl:portType> <wsdl:binding name="__SynapseServiceSoap11Binding" type="axis2:__SynapseServicePortType"> <soap:binding transport="http://schemas.xmlsoap.org/soap/http" style="document"/> <wsdl:operation name="mediate"> <soap:operation soapAction="urn:mediate" style="document"/> <wsdl:input> <soap:body use="literal"/> </wsdl:input> <wsdl:output> <soap:body use="literal"/> </wsdl:output> </wsdl:operation> </wsdl:binding> <wsdl:binding name="__SynapseServiceSoap12Binding" type="axis2:__SynapseServicePortType"> <soap12:binding transport="http://schemas.xmlsoap.org/soap/http" style="document"/> <wsdl:operation name="mediate"> <soap12:operation soapAction="urn:mediate" style="document"/> <wsdl:input> <soap12:body use="literal"/> </wsdl:input> <wsdl:output> <soap12:body use="literal"/> </wsdl:output> </wsdl:operation> </wsdl:binding> <wsdl:binding name="__SynapseServiceHttpBinding" type="axis2:__SynapseServicePortType"> <http:binding verb="POST"/> <wsdl:operation name="mediate"> <http:operation location="mediate"/> <wsdl:input> <mime:content type="text/xml" part="mediate"/> </wsdl:input> <wsdl:output> <mime:content type="text/xml" part="mediate"/> </wsdl:output> </wsdl:operation> </wsdl:binding> <wsdl:service name="__SynapseService"> <wsdl:port name="__SynapseServiceHttpsSoap11Endpoint" binding="axis2:__SynapseServiceSoap11Binding"> <soap:address location="https://localhost:8843/services/__SynapseService.__SynapseServiceHttpsSoap11Endpoint"/> </wsdl:port> <wsdl:port name="__SynapseServiceHttpSoap11Endpoint" binding="axis2:__SynapseServiceSoap11Binding"> <soap:address location="http://localhost:8880/services/__SynapseService.__SynapseServiceHttpSoap11Endpoint"/> </wsdl:port> <wsdl:port name="__SynapseServiceHttpsSoap12Endpoint" binding="axis2:__SynapseServiceSoap12Binding"> <soap12:address location="https://localhost:8843/services/__SynapseService.__SynapseServiceHttpsSoap12Endpoint"/> </wsdl:port> <wsdl:port name="__SynapseServiceHttpSoap12Endpoint" binding="axis2:__SynapseServiceSoap12Binding"> <soap12:address location="http://localhost:8880/services/__SynapseService.__SynapseServiceHttpSoap12Endpoint"/> </wsdl:port> <wsdl:port name="__SynapseServiceHttpsEndpoint" binding="axis2:__SynapseServiceHttpBinding"> <http:address location="https://localhost:8843/services/__SynapseService.__SynapseServiceHttpsEndpoint"/> </wsdl:port> <wsdl:port name="__SynapseServiceHttpEndpoint" binding="axis2:__SynapseServiceHttpBinding"> <http:address location="http://localhost:8880/services/__SynapseService.__SynapseServiceHttpEndpoint"/> </wsdl:port> </wsdl:service> </wsdl:definitions>

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• WPF Blurry Images - Bitmap Class

  - by Luke

  I am using the following sample at http://blogs.msdn.com/dwayneneed/archive/2007/10/05/blurry-bitmaps.aspx within VB.NET. The code is shown below. I am having a problem when my application loads the CPU is pegging 50-70%. I have determined that the problem is with the Bitmap class. The OnLayoutUpdated() method is calling the InvalidateVisual() continously. This is because some points are not returning as equal but rather, Point(0.0,-0.5) Can anyone see any bugs within this code or know a better implmentation for pixel snapping a Bitmap image so it is not blurry? p.s. The sample code was in C#, however I believe that it was converted correctly. Imports System Imports System.Collections.Generic Imports System.Windows Imports System.Windows.Media Imports System.Windows.Media.Imaging Class Bitmap Inherits FrameworkElement ' Use FrameworkElement instead of UIElement so Data Binding works as expected Private _sourceDownloaded As EventHandler Private _sourceFailed As EventHandler(Of ExceptionEventArgs) Private _pixelOffset As Windows.Point Public Sub New() _sourceDownloaded = New EventHandler(AddressOf OnSourceDownloaded) _sourceFailed = New EventHandler(Of ExceptionEventArgs)(AddressOf OnSourceFailed) AddHandler LayoutUpdated, AddressOf OnLayoutUpdated End Sub Public Shared ReadOnly SourceProperty As DependencyProperty = DependencyProperty.Register("Source", GetType(BitmapSource), GetType(Bitmap), New FrameworkPropertyMetadata(Nothing, FrameworkPropertyMetadataOptions.AffectsRender Or FrameworkPropertyMetadataOptions.AffectsMeasure, New PropertyChangedCallback(AddressOf Bitmap.OnSourceChanged))) Public Property Source() As BitmapSource Get Return DirectCast(GetValue(SourceProperty), BitmapSource) End Get Set(ByVal value As BitmapSource) SetValue(SourceProperty, value) End Set End Property Public Shared Function FindParentWindow(ByVal child As DependencyObject) As Window Dim parent As DependencyObject = VisualTreeHelper.GetParent(child) 'Check if this is the end of the tree If parent Is Nothing Then Return Nothing End If Dim parentWindow As Window = TryCast(parent, Window) If parentWindow IsNot Nothing Then Return parentWindow Else ' Use recursion until it reaches a Window Return FindParentWindow(parent) End If End Function Public Event BitmapFailed As EventHandler(Of ExceptionEventArgs) ' Return our measure size to be the size needed to display the bitmap pixels. ' ' Use MeasureOverride instead of MeasureCore so Data Binding works as expected. ' Protected Overloads Overrides Function MeasureCore(ByVal availableSize As Size) As Size Protected Overloads Overrides Function MeasureOverride(ByVal availableSize As Size) As Size Dim measureSize As New Size() Dim bitmapSource As BitmapSource = Source If bitmapSource IsNot Nothing Then Dim ps As PresentationSource = PresentationSource.FromVisual(Me) If Me.VisualParent IsNot Nothing Then Dim window As Window = window.GetWindow(Me.VisualParent) If window IsNot Nothing Then ps = PresentationSource.FromVisual(window.GetWindow(Me.VisualParent)) ElseIf FindParentWindow(Me) IsNot Nothing Then ps = PresentationSource.FromVisual(FindParentWindow(Me)) End If End If ' If ps IsNot Nothing Then Dim fromDevice As Matrix = ps.CompositionTarget.TransformFromDevice Dim pixelSize As New Vector(bitmapSource.PixelWidth, bitmapSource.PixelHeight) Dim measureSizeV As Vector = fromDevice.Transform(pixelSize) measureSize = New Size(measureSizeV.X, measureSizeV.Y) Else measureSize = New Size(bitmapSource.PixelWidth, bitmapSource.PixelHeight) End If End If Return measureSize End Function Protected Overloads Overrides Sub OnRender(ByVal dc As DrawingContext) Dim bitmapSource As BitmapSource = Me.Source If bitmapSource IsNot Nothing Then _pixelOffset = GetPixelOffset() ' Render the bitmap offset by the needed amount to align to pixels. dc.DrawImage(bitmapSource, New Rect(_pixelOffset, DesiredSize)) End If End Sub Private Shared Sub OnSourceChanged(ByVal d As DependencyObject, ByVal e As DependencyPropertyChangedEventArgs) Dim bitmap As Bitmap = DirectCast(d, Bitmap) Dim oldValue As BitmapSource = DirectCast(e.OldValue, BitmapSource) Dim newValue As BitmapSource = DirectCast(e.NewValue, BitmapSource) If ((oldValue IsNot Nothing) AndAlso (bitmap._sourceDownloaded IsNot Nothing)) AndAlso (Not oldValue.IsFrozen AndAlso (TypeOf oldValue Is BitmapSource)) Then RemoveHandler DirectCast(oldValue, BitmapSource).DownloadCompleted, bitmap._sourceDownloaded RemoveHandler DirectCast(oldValue, BitmapSource).DownloadFailed, bitmap._sourceFailed ' ((BitmapSource)newValue).DecodeFailed -= bitmap._sourceFailed; // 3.5 End If If ((newValue IsNot Nothing) AndAlso (TypeOf newValue Is BitmapSource)) AndAlso Not newValue.IsFrozen Then AddHandler DirectCast(newValue, BitmapSource).DownloadCompleted, bitmap._sourceDownloaded AddHandler DirectCast(newValue, BitmapSource).DownloadFailed, bitmap._sourceFailed ' ((BitmapSource)newValue).DecodeFailed += bitmap._sourceFailed; // 3.5 End If End Sub Private Sub OnSourceDownloaded(ByVal sender As Object, ByVal e As EventArgs) InvalidateMeasure() InvalidateVisual() End Sub Private Sub OnSourceFailed(ByVal sender As Object, ByVal e As ExceptionEventArgs) Source = Nothing ' setting a local value seems scetchy... RaiseEvent BitmapFailed(Me, e) End Sub Private Sub OnLayoutUpdated(ByVal sender As Object, ByVal e As EventArgs) ' This event just means that layout happened somewhere. However, this is ' what we need since layout anywhere could affect our pixel positioning. Dim pixelOffset As Windows.Point = GetPixelOffset() If Not AreClose(pixelOffset, _pixelOffset) Then InvalidateVisual() End If End Sub ' Gets the matrix that will convert a Windows.Point from "above" the ' coordinate space of a visual into the the coordinate space ' "below" the visual. Private Function GetVisualTransform(ByVal v As Visual) As Matrix If v IsNot Nothing Then Dim m As Matrix = Matrix.Identity Dim transform As Transform = VisualTreeHelper.GetTransform(v) If transform IsNot Nothing Then Dim cm As Matrix = transform.Value m = Matrix.Multiply(m, cm) End If Dim offset As Vector = VisualTreeHelper.GetOffset(v) m.Translate(offset.X, offset.Y) Return m End If Return Matrix.Identity End Function Private Function TryApplyVisualTransform(ByVal Point As Windows.Point, ByVal v As Visual, ByVal inverse As Boolean, ByVal throwOnError As Boolean, ByRef success As Boolean) As Windows.Point success = True If v IsNot Nothing Then Dim visualTransform As Matrix = GetVisualTransform(v) If inverse Then If Not throwOnError AndAlso Not visualTransform.HasInverse Then success = False Return New Windows.Point(0, 0) End If visualTransform.Invert() End If Point = visualTransform.Transform(Point) End If Return Point End Function Private Function ApplyVisualTransform(ByVal Point As Windows.Point, ByVal v As Visual, ByVal inverse As Boolean) As Windows.Point Dim success As Boolean = True Return TryApplyVisualTransform(Point, v, inverse, True, success) End Function Private Function GetPixelOffset() As Windows.Point Dim pixelOffset As New Windows.Point() Dim ps As PresentationSource = PresentationSource.FromVisual(Me) If ps IsNot Nothing Then Dim rootVisual As Visual = ps.RootVisual ' Transform (0,0) from this element up to pixels. pixelOffset = Me.TransformToAncestor(rootVisual).Transform(pixelOffset) pixelOffset = ApplyVisualTransform(pixelOffset, rootVisual, False) pixelOffset = ps.CompositionTarget.TransformToDevice.Transform(pixelOffset) ' Round the origin to the nearest whole pixel. pixelOffset.X = Math.Round(pixelOffset.X) pixelOffset.Y = Math.Round(pixelOffset.Y) ' Transform the whole-pixel back to this element. pixelOffset = ps.CompositionTarget.TransformFromDevice.Transform(pixelOffset) pixelOffset = ApplyVisualTransform(pixelOffset, rootVisual, True) pixelOffset = rootVisual.TransformToDescendant(Me).Transform(pixelOffset) End If Return pixelOffset End Function Private Function AreClose(ByVal Point1 As Windows.Point, ByVal Point2 As Windows.Point) As Boolean Return AreClose(Point1.X, Point2.X) AndAlso AreClose(Point1.Y, Point2.Y) End Function Private Function AreClose(ByVal value1 As Double, ByVal value2 As Double) As Boolean If value1 = value2 Then Return True End If Dim delta As Double = value1 - value2 Return ((delta < 0.00000153) AndAlso (delta > -0.00000153)) End Function End Class

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• Entity Framework 4.0 and DDD patterns

  - by Voice

  Hi everybody I use EntityFramework as ORM and I have simple POCO Domain Model with two base classes that represent Value Object and Entity Object Patterns (Evans). These two patterns is all about equality of two objects, so I overrode Equals and GetHashCode methods. Here are these two classes: public abstract class EntityObject<T>{ protected T _ID = default(T); public T ID { get { return _ID; } protected set { _ID = value; } } public sealed override bool Equals(object obj) { EntityObject<T> compareTo = obj as EntityObject<T>; return (compareTo != null) && ((HasSameNonDefaultIdAs(compareTo) || (IsTransient && compareTo.IsTransient)) && HasSameBusinessSignatureAs(compareTo)); } public virtual void MakeTransient() { _ID = default(T); } public bool IsTransient { get { return _ID == null || _ID.Equals(default(T)); } } public override int GetHashCode() { if (default(T).Equals(_ID)) return 0; return _ID.GetHashCode(); } private bool HasSameBusinessSignatureAs(EntityObject<T> compareTo) { return ToString().Equals(compareTo.ToString()); } private bool HasSameNonDefaultIdAs(EntityObject<T> compareTo) { return (_ID != null && !_ID.Equals(default(T))) && (compareTo._ID != null && !compareTo._ID.Equals(default(T))) && _ID.Equals(compareTo._ID); } public override string ToString() { StringBuilder str = new StringBuilder(); str.Append(" Class: ").Append(GetType().FullName); if (!IsTransient) str.Append(" ID: " + _ID); return str.ToString(); } } public abstract class ValueObject<T, U> : IEquatable<T> where T : ValueObject<T, U> { private static List<PropertyInfo> Properties { get; set; } private static Func<ValueObject<T, U>, PropertyInfo, object[], object> _GetPropValue; static ValueObject() { Properties = new List<PropertyInfo>(); var propParam = Expression.Parameter(typeof(PropertyInfo), "propParam"); var target = Expression.Parameter(typeof(ValueObject<T, U>), "target"); var indexPar = Expression.Parameter(typeof(object[]), "indexPar"); var call = Expression.Call(propParam, typeof(PropertyInfo).GetMethod("GetValue", new[] { typeof(object), typeof(object[]) }), new[] { target, indexPar }); var lambda = Expression.Lambda<Func<ValueObject<T, U>, PropertyInfo, object[], object>>(call, target, propParam, indexPar); _GetPropValue = lambda.Compile(); } public U ID { get; protected set; } public override Boolean Equals(Object obj) { if (ReferenceEquals(null, obj)) return false; if (obj.GetType() != GetType()) return false; return Equals(obj as T); } public Boolean Equals(T other) { if (ReferenceEquals(null, other)) return false; if (ReferenceEquals(this, other)) return true; foreach (var property in Properties) { var oneValue = _GetPropValue(this, property, null); var otherValue = _GetPropValue(other, property, null); if (null == oneValue && null == otherValue) return false; if (false == oneValue.Equals(otherValue)) return false; } return true; } public override Int32 GetHashCode() { var hashCode = 36; foreach (var property in Properties) { var propertyValue = _GetPropValue(this, property, null); if (null == propertyValue) continue; hashCode = hashCode ^ propertyValue.GetHashCode(); } return hashCode; } public override String ToString() { var stringBuilder = new StringBuilder(); foreach (var property in Properties) { var propertyValue = _GetPropValue(this, property, null); if (null == propertyValue) continue; stringBuilder.Append(propertyValue.ToString()); } return stringBuilder.ToString(); } protected static void RegisterProperty(Expression<Func<T, Object>> expression) { MemberExpression memberExpression; if (ExpressionType.Convert == expression.Body.NodeType) { var body = (UnaryExpression)expression.Body; memberExpression = body.Operand as MemberExpression; } else memberExpression = expression.Body as MemberExpression; if (null == memberExpression) throw new InvalidOperationException("InvalidMemberExpression"); Properties.Add(memberExpression.Member as PropertyInfo); } } Everything was OK until I tried to delete some related objects (aggregate root object with two dependent objects which was marked for cascade deletion): I've got an exception "The relationship could not be changed because one or more of the foreign-key properties is non-nullable". I googled this and found http://blog.abodit.com/2010/05/the-relationship-could-not-be-changed-because-one-or-more-of-the-foreign-key-properties-is-non-nullable/ I changed GetHashCode to base.GetHashCode() and error disappeared. But now it breaks all my code: I can't override GetHashCode for my POCO objects = I can't override Equals = I can't implement Value Object and Entity Object patters for my POCO objects. So, I appreciate any solutions, workarounds here etc.

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• Trying to create scrolling horizontal thumbnail navigation that hides on left side when not in use

  - by user346602

  Hi, I am trying recreate the following type of scrolling thumbnail navigation as described in the following tutorial: http://tympanus.net/codrops/2010/05/10/scrollable-thumbs-menu/ I require my thumbs to slide out horizontally from the left. I have amended the code to the best of my abilities, but I can't get it to work. (Think the problem is in the top third of the jquery). Here is what I have to date: HTML <ul class="menu" id="menu"> <li> <a href="#"></a> <div class="sc_menu_wrapper"> <div class="sc_menu"> <a href="#"><img src="images/gallery/1.jpg" alt=""/></a> <a href="#"><img src="images/gallery/2.jpg" alt=""/></a> <a href="#"><img src="images/gallery/3.jpg" alt=""/></a> <a href="#"><img src="images/gallery/4.jpg" alt=""/></a> <a href="#"><img src="images/gallery/5.jpg" alt=""/></a> </div> </div> </li> </ul> CSS /* Navigation Style */ ul.menu{ position: fixed; top: 0px; left:0px; width: 100%; } ul.menu li{ position:relative; width: 100% } ul.menu li > a{ position:absolute; top:300px; left:0px; width:40px; height:200px; background-color:#e7e7e8; } /* Thumb Scrolling Style */ div.sc_menu_wrapper { position: absolute; right: 0px; height: 220px; overflow: hidden; top: 300px; left:0px; visibility:hidden; } div.sc_menu { height: 200px; visibility:hidden; } .sc_menu a { display: block; background-color:#e7e7e8; } .sc_menu img { display: block; border: none; opacity:0.3; filter:progid:DXImageTransform.Microsoft.Alpha(opacity=30); } JQUERY $(function(){ // function to make the thumbs menu scrollable function buildThumbs($elem){ var $wrapper = $elem.next(); var $menu = $wrapper.find('.sc_menu'); var inactiveMargin = 220; // move the scroll down to the beggining (move as much as the height of the menu) $wrapper.scrollRight($menu.outerHeight()); //when moving the mouse up or down, the wrapper moves (scrolls) up or down $wrapper.bind('mousemove',function(e){ var wrapperWidth = $wrapper.width(); var menuWidth = $menu.outerWidth() + 2 * inactiveMargin; var top = (e.pageX - $wrapper.offset().right) * (menuWidth - wrapperWidth) / wrapperWidth - inactiveMargin; $wrapper.scrollRight(right+10); }); } var stacktime; $('#menu li > a').bind('mouseover',function () { var $this = $(this); buildThumbs($this); var pos = $this.next().find('a').size(); var f = function(){ if(pos==0) clearTimeout(stacktime); $this.next().find('a:nth-child('+pos+')').css('visibility','visible'); --pos; }; // each thumb will appear with a delay stacktime = setInterval(f , 50); }); /// on mouseleave of the whole <li> the scrollable area is hidden $('#menu li').bind('mouseleave',function () { var $this = $(this); clearTimeout(stacktime); $this.find('.sc_menu').css('visibility','hidden').find('a').css('visibility','hidden'); $this.find('.sc_menu_wrapper').css('visibility','hidden'); }); // when hovering a thumb, change its opacity $('.sc_menu a').hover( function () { var $this = $(this); $this.find('img') .stop() .animate({'opacity':'1.0'},400); }, function () { var $this = $(this); $this.find('img') .stop() .animate({'opacity':'0.3'},400); } ); }); Wondering if some eagle eye might be able to point out where I am going wrong. As my knowledge of JQuery is limited, I'm guessing it is in there. I really appreciate anyone taking the time to look this over. Thank you!

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• Problem in generation of custom classes at web service client

  - by user443324

  I have a web service which receives an custom object and returns another custom object. It can be deployed successfully on GlassFish or JBoss. @WebMethod(operationName = "providerRQ") @WebResult(name = "BookingInfoResponse" , targetNamespace = "http://tlonewayresprovidrs.jaxbutil.rakes.nhst.com/") public com.nhst.rakes.jaxbutil.tlonewayresprovidrs.BookingInfoResponse providerRQ(@WebParam(name = "BookingInfoRequest" , targetNamespace = "http://tlonewayresprovidrq.jaxbutil.rakes.nhst.com/") com.nhst.rakes.jaxbutil.tlonewayresprovidrq.BookingInfoRequest BookingInfoRequest) { com.nhst.rakes.jaxbutil.tlonewayresprovidrs.BookingInfoResponse BookingInfoResponse = new com.nhst.rakes.jaxbutil.tlonewayresprovidrs.BookingInfoResponse(); return BookingInfoResponse; } But when I create a client for this web service, two instances of BookingInfoRequest and BookingInfoResponse generated even I need only one instance. This time an error is returned that says multiple classes with same name are can not be possible....... Here is wsdl..... <?xml version='1.0' encoding='UTF-8'?><!-- Published by JAX-WS RI at http://jax-ws.dev.java.net. RI's version is JAX-WS RI 2.2.1-hudson-28-. --><!-- Generated by JAX-WS RI at http://jax-ws.dev.java.net. RI's version is JAX-WS RI 2.2.1-hudson-28-. --><definitions xmlns:wsu="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd" xmlns:wsp="http://www.w3.org/ns/ws-policy" xmlns:wsp1_2="http://schemas.xmlsoap.org/ws/2004/09/policy" xmlns:wsam="http://www.w3.org/2007/05/addressing/metadata" xmlns:soap="http://schemas.xmlsoap.org/wsdl/soap/" xmlns:tns="http://demo/" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns="http://schemas.xmlsoap.org/wsdl/" targetNamespace="http://demo/" name="DemoJAXBParamService"> <wsp:Policy wsu:Id="DemoJAXBParamPortBindingPolicy"> <ns1:OptimizedMimeSerialization xmlns:ns1="http://schemas.xmlsoap.org/ws/2004/09/policy/optimizedmimeserialization" /> </wsp:Policy> <types> <xsd:schema> <xsd:import namespace="http://tlonewayresprovidrs.jaxbutil.rakes.nhst.com/" schemaLocation="http://localhost:31133/DemoJAXBParamService/DemoJAXBParamService?xsd=1" /> </xsd:schema> <xsd:schema> <xsd:import namespace="http://tlonewayresprovidrs.jaxbutil.rakes.nhst.com" schemaLocation="http://localhost:31133/DemoJAXBParamService/DemoJAXBParamService?xsd=2" /> </xsd:schema> <xsd:schema> <xsd:import namespace="http://tlonewayresprovidrq.jaxbutil.rakes.nhst.com/" schemaLocation="http://localhost:31133/DemoJAXBParamService/DemoJAXBParamService?xsd=3" /> </xsd:schema> <xsd:schema> <xsd:import namespace="http://tlonewayresprovidrq.jaxbutil.rakes.nhst.com" schemaLocation="http://localhost:31133/DemoJAXBParamService/DemoJAXBParamService?xsd=4" /> </xsd:schema> <xsd:schema> <xsd:import namespace="http://demo/" schemaLocation="http://localhost:31133/DemoJAXBParamService/DemoJAXBParamService?xsd=5" /> </xsd:schema> </types> <message name="providerRQ"> <part name="parameters" element="tns:providerRQ" /> </message> <message name="providerRQResponse"> <part name="parameters" element="tns:providerRQResponse" /> </message> <portType name="DemoJAXBParam"> <operation name="providerRQ"> <input wsam:Action="http://demo/DemoJAXBParam/providerRQRequest" message="tns:providerRQ" /> <output wsam:Action="http://demo/DemoJAXBParam/providerRQResponse" message="tns:providerRQResponse" /> </operation> </portType> <binding name="DemoJAXBParamPortBinding" type="tns:DemoJAXBParam"> <wsp:PolicyReference URI="#DemoJAXBParamPortBindingPolicy" /> <soap:binding transport="http://schemas.xmlsoap.org/soap/http" style="document" /> <operation name="providerRQ"> <soap:operation soapAction="" /> <input> <soap:body use="literal" /> </input> <output> <soap:body use="literal" /> </output> </operation> </binding> <service name="DemoJAXBParamService"> <port name="DemoJAXBParamPort" binding="tns:DemoJAXBParamPortBinding"> <soap:address location="http://localhost:31133/DemoJAXBParamService/DemoJAXBParamService" /> </port> </service> </definitions> So, I want to know that how to generate only one instance(I don't know why two instances are generated at client side?). Please help me to move in right direction.

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• Using jQuery to Insert a New Database Record

  - by Stephen Walther

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

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• jQuery and Windows Azure

  - by Stephen Walther

  The goal of this blog entry is to describe how you can host a simple Ajax application created with jQuery in the Windows Azure cloud. In this blog entry, I make no assumptions. I assume that you have never used Windows Azure and I am going to walk through the steps required to host the application in the cloud in agonizing detail. Our application will consist of a single HTML page and a single service. The HTML page will contain jQuery code that invokes the service to retrieve and display set of records. There are five steps that you must complete to host the jQuery application: Sign up for Windows Azure Create a Hosted Service Install the Windows Azure Tools for Visual Studio Create a Windows Azure Cloud Service Deploy the Cloud Service Sign Up for Windows Azure Go to http://www.microsoft.com/windowsazure/ and click the Sign up Now button. Select one of the offers. I selected the Introductory Special offer because it is free and I just wanted to experiment with Windows Azure for the purposes of this blog entry.     To sign up, you will need a Windows Live ID and you will need to enter a credit card number. After you finish the sign up process, you will receive an email that explains how to activate your account. Accessing the Developer Portal After you create your account and your account is activated, you can access the Windows Azure developer portal by visiting the following URL: http://windows.azure.com/ When you first visit the developer portal, you will see the one project that you created when you set up your Windows Azure account (In a fit of creativity, I named my project StephenWalther).     Creating a New Windows Azure Hosted Service Before you can host an application in the cloud, you must first add a hosted service to your project. Click your project on the summary page and click the New Service link. You are presented with the option of creating either a new Storage Account or a new Hosted Services.     Because we have code that we want to run in the cloud – the WCF Service -- we want to select the Hosted Services option. After you select this option, you must provide a name and description for your service. This information is used on the developer portal so you can distinguish your services.     When you create a new hosted service, you must enter a unique name for your service (I selected jQueryApp) and you must select a region for this service (I selected Anywhere US). Click the Create button to create the new hosted service.   Install the Windows Azure Tools for Visual Studio We’ll use Visual Studio to create our jQuery project. Before you can use Visual Studio with Windows Azure, you must first install the Windows Azure Tools for Visual Studio. Go to http://www.microsoft.com/windowsazure/ and click the Get Tools and SDK button. The Windows Azure Tools for Visual Studio works with both Visual Studio 2008 and Visual Studio 2010.   Installation of the Windows Azure Tools for Visual Studio is painless. You just need to check some agreement checkboxes and click the Next button a few times and installation will begin:   Creating a Windows Azure Application After you install the Windows Azure Tools for Visual Studio, you can choose to create a Windows Azure Cloud Service by selecting the menu option File, New Project and selecting the Windows Azure Cloud Service project template. I named my new Cloud Service with the name jQueryApp.     Next, you need to select the type of Cloud Service project that you want to create from the New Cloud Service Project dialog.   I selected the C# ASP.NET Web Role option. Alternatively, I could have picked the ASP.NET MVC 2 Web Role option if I wanted to use jQuery with ASP.NET MVC or even the CGI Web Role option if I wanted to use jQuery with PHP. After you complete these steps, you end up with two projects in your Visual Studio solution. The project named WebRole1 represents your ASP.NET application and we will use this project to create our jQuery application. Creating the jQuery Application in the Cloud We are now ready to create the jQuery application. We’ll create a super simple application that displays a list of records retrieved from a WCF service (hosted in the cloud). Create a new page in the WebRole1 project named Default.htm and add the following code: <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>Products</title> <style type="text/css"> #productContainer div { border:solid 1px black; padding:5px; margin:5px; } </style> </head> <body> <h1>Product Catalog</h1> <div id="productContainer"></div> <script id="productTemplate" type="text/html"> <div> Name: {{= name }} <br /> Price: {{= price }} </div> </script> <script src="Scripts/jquery-1.4.2.js" type="text/javascript"></script> <script src="Scripts/jquery.tmpl.js" type="text/javascript"></script> <script type="text/javascript"> var products = [ {name:"Milk", price:4.55}, {name:"Yogurt", price:2.99}, {name:"Steak", price:23.44} ]; $("#productTemplate").render(products).appendTo("#productContainer"); </script> </body> </html> The jQuery code in this page simply displays a list of products by using a template. I am using a jQuery template to format each product. You can learn more about using jQuery templates by reading the following blog entry by Scott Guthrie: http://weblogs.asp.net/scottgu/archive/2010/05/07/jquery-templates-and-data-linking-and-microsoft-contributing-to-jquery.aspx You can test whether the Default.htm page is working correctly by running your application (hit the F5 key). The first time that you run your application, a database is set up on your local machine to simulate cloud storage. You will see the following dialog: If the Default.htm page works as expected, you should see the list of three products: Adding an Ajax-Enabled WCF Service In the previous section, we created a simple jQuery application that displays an array by using a template. The application is a little too simple because the data is static. In this section, we’ll modify the page so that the data is retrieved from a WCF service instead of an array. First, we need to add a new Ajax-enabled WCF Service to the WebRole1 project. Select the menu option Project, Add New Item and select the Ajax-enabled WCF Service project item. Name the new service ProductService.svc. Modify the service so that it returns a static collection of products. The final code for the ProductService.svc should look like this: using System.Collections.Generic; using System.ServiceModel; using System.ServiceModel.Activation; namespace WebRole1 { public class Product { public string name { get; set; } public decimal price { get; set; } } [ServiceContract(Namespace = "")] [AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)] public class ProductService { [OperationContract] public IList<Product> SelectProducts() { var products = new List<Product>(); products.Add(new Product {name="Milk", price=4.55m} ); products.Add(new Product { name = "Yogurt", price = 2.99m }); products.Add(new Product { name = "Steak", price = 23.44m }); return products; } } }   In real life, you would want to retrieve the list of products from storage instead of a static array. We are being lazy here. Next you need to modify the Default.htm page to use the ProductService.svc. The jQuery script in the following updated Default.htm page makes an Ajax call to the WCF service. The data retrieved from the ProductService.svc is displayed in the client template. <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>Products</title> <style type="text/css"> #productContainer div { border:solid 1px black; padding:5px; margin:5px; } </style> </head> <body> <h1>Product Catalog</h1> <div id="productContainer"></div> <script id="productTemplate" type="text/html"> <div> Name: {{= name }} <br /> Price: {{= price }} </div> </script> <script src="Scripts/jquery-1.4.2.js" type="text/javascript"></script> <script src="Scripts/jquery.tmpl.js" type="text/javascript"></script> <script type="text/javascript"> $.post("ProductService.svc/SelectProducts", function (results) { var products = results["d"]; $("#productTemplate").render(products).appendTo("#productContainer"); }); </script> </body> </html>   Deploying the jQuery Application to the Cloud Now that we have created our jQuery application, we are ready to deploy our application to the cloud so that the whole world can use it. Right-click your jQueryApp project in the Solution Explorer window and select the Publish menu option. When you select publish, your application and your application configuration information is packaged up into two files named jQueryApp.cspkg and ServiceConfiguration.cscfg. Visual Studio opens the directory that contains the two files. In order to deploy these files to the Windows Azure cloud, you must upload these files yourself. Return to the Windows Azure Developers Portal at the following address: http://windows.azure.com/ Select your project and select the jQueryApp service. You will see a mysterious cube. Click the Deploy button to upload your application.   Next, you need to browse to the location on your hard drive where the jQueryApp project was published and select both the packaged application and the packaged application configuration file. Supply the deployment with a name and click the Deploy button.     While your application is in the process of being deployed, you can view a progress bar.     Running the jQuery Application in the Cloud Finally, you can run your jQuery application in the cloud by clicking the Run button.   It might take several minutes for your application to initialize (go grab a coffee). After WebRole1 finishes initializing, you can navigate to the following URL to view your live jQuery application in the cloud: http://jqueryapp.cloudapp.net/default.htm The page is hosted on the Windows Azure cloud and the WCF service executes every time that you request the page to retrieve the list of products. Summary Because we started from scratch, we needed to complete several steps to create and deploy our jQuery application to the Windows Azure cloud. We needed to create a Windows Azure account, create a hosted service, install the Windows Azure Tools for Visual Studio, create the jQuery application, and deploy it to the cloud. Now that we have finished this process once, modifying our existing cloud application or creating a new cloud application is easy. jQuery and Windows Azure work nicely together. We can take advantage of jQuery to build applications that run in the browser and we can take advantage of Windows Azure to host the backend services required by our jQuery application. The big benefit of Windows Azure is that it enables us to scale. If, all of the sudden, our jQuery application explodes in popularity, Windows Azure enables us to easily scale up to meet the demand. We can handle anything that the Internet might throw at us.

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• CLSF & CLK 2013 Trip Report by Jeff Liu

  - by jamesmorris

  This is a contributed post from Jeff Liu, lead XFS developer for the Oracle mainline Linux kernel team. Recently, I attended both the China Linux Storage and Filesystem workshop (CLSF), and the China Linux Kernel conference (CLK), which were held in Shanghai. Here are the highlights for both events. CLSF - 17th October XFS update (led by Jeff Liu) XFS keeps rapid progress with a lot of changes, especially focused on the infrastructure/performance improvements as well as  new feature development.  This can be reflected with a sample statistics among XFS/Ext4+JBD2/Btrfs via: # git diff --stat --minimal -C -M v3.7..v3.12-rc4 -- fs/xfs|fs/ext4+fs/jbd2|fs/btrfs XFS: 141 files changed, 27598 insertions(+), 19113 deletions(-) Ext4+JBD2: 39 files changed, 10487 insertions(+), 5454 deletions(-) Btrfs: 70 files changed, 19875 insertions(+), 8130 deletions(-) What made up those changes in XFS? Self-describing metadata(CRC32c). This is a new feature and it contributed about 70% code changes, it can be enabled via `mkfs.xfs -m crc=1 /dev/xxx` for v5 superblock. Transaction log space reservation improvements. With this change, we can calculate the log space reservation at mount time rather than runtime to reduce the the CPU overhead. User namespace support. So both XFS and USERNS can be enabled on kernel configuration begin from Linux 3.10. Thanks Dwight Engen's efforts for this thing. Split project/group quota inodes. Originally, project quota can not be enabled with group quota at the same time because they were share the same quota file inode, now it works but only for v5 super block. i.e, CRC enabled. CONFIG_XFS_WARN, an new lightweight runtime debugger which can be deployed in production environment. Readahead log object recovery, this change can speed up the log replay progress significantly. Speculative preallocation inode tracking, clearing and throttling. The main purpose is to deal with inodes with post-EOF space due to speculative preallocation, support improved quota management to free up a significant amount of unwritten space when at or near EDQUOT. It support backgroup scanning which occurs on a longish interval(5 mins by default, tunable), and on-demand scanning/trimming via ioctl(2). Bitter arguments ensued from this session, especially for the comparison between Ext4 and Btrfs in different areas, I have to spent a whole morning of the 1st day answering those questions. We basically agreed on XFS is the best choice in Linux nowadays because: Stable, XFS has a good record in stability in the past 10 years. Fengguang Wu who lead the 0-day kernel test project also said that he has observed less error than other filesystems in the past 1+ years, I own it to the XFS upstream code reviewer, they always performing serious code review as well as testing. Good performance for large/small files, XFS does not works very well for small files has already been an old story for years. Best choice (maybe) for distributed PB filesystems. e.g, Ceph recommends delopy OSD daemon on XFS because Ext4 has limited xattr size. Best choice for large storage (>16TB). Ext4 does not support a single file more than around 15.95TB. Scalability, any objection to XFS is best in this point? :) XFS is better to deal with transaction concurrency than Ext4, why? The maximum size of the log in XFS is 2038MB compare to 128MB in Ext4. Misc. Ext4 is widely used and it has been proved fast/stable in various loads and scenarios, XFS just need more customers, and Btrfs is still on the road to be a manhood. Ceph Introduction (Led by Li Wang) This a hot topic.  Li gave us a nice introduction about the design as well as their current works. Actually, Ceph client has been included in Linux kernel since 2.6.34 and supported by Openstack since Folsom but it seems that it has not yet been widely deployment in production environment. Their major work is focus on the inline data support to separate the metadata and data storage, reduce the file access time, i.e, a file access need communication twice, fetch the metadata from MDS and then get data from OSD, and also, the small file access is limited by the network latency. The solution is, for the small files they would like to store the data at metadata so that when accessing a small file, the metadata server can push both metadata and data to the client at the same time. In this way, they can reduce the overhead of calculating the data offset and save the communication to OSD. For this feature, they have only run some small scale testing but really saw noticeable improvements. Test environment: Intel 2 CPU 12 Core, 64GB RAM, Ubuntu 12.04, Ceph 0.56.6 with 200GB SATA disk, 15 OSD, 1 MDS, 1 MON. The sequence read performance for 1K size files improved about 50%. I have asked Li and Zheng Yan (the core developer of Ceph, who also worked on Btrfs) whether Ceph is really stable and can be deployed at production environment for large scale PB level storage, but they can not give a positive answer, looks Ceph even does not spread over Dreamhost (subject to confirmation). From Li, they only deployed Ceph for a small scale storage(32 nodes) although they'd like to try 6000 nodes in the future. Improve Linux swap for Flash storage (led by Shaohua Li) Because of high density, low power and low price, flash storage (SSD) is a good candidate to partially replace DRAM. A quick answer for this is using SSD as swap. But Linux swap is designed for slow hard disk storage, so there are a lot of challenges to efficiently use SSD for swap. SWAPOUT swap_map scan swap_map is the in-memory data structure to track swap disk usage, but it is a slow linear scan. It will become a bottleneck while finding many adjacent pages in the use of SSD. Shaohua Li have changed it to a cluster(128K) list, resulting in O(1) algorithm. However, this apporoach needs restrictive cluster alignment and only enabled for SSD. IO pattern In most cases, the swap io is in interleaved pattern because of mutiple reclaimers or a free cluster is shared by all reclaimers. Even though block layer can merge interleaved IO to some extent, but we cannot count on it completely. Hence the per-cpu cluster is added base on the previous change, it can help reclaimer do sequential IO and the block layer will be easier to merge IO. TLB flush: If we're reclaiming one active page, we should first move the page from active lru list to inactive lru list, and then reclaim the page from inactive lru to swap it out. During the process, we need to clear PTE twice: first is 'A'(ACCESS) bit, second is 'P'(PRESENT) bit. Processors need to send lots of ipi which make the TLB flush really expensive. Some works have been done to improve this, including rework smp_call_functiom_many() or remove the first TLB flush in x86, but there still have some arguments here and only parts of works have been pushed to mainline. SWAPIN: Page fault does iodepth=1 sync io, but it's a little waste if only issue a page size's IO. The obvious solution is doing swap readahead. But the current in-kernel swap readahead is arbitary(always 8 pages), and it always doesn't perform well for both random and sequential access workload. Shaohua introduced a new flag for madvise(MADV_WILLNEED) to do swap prefetch, so the changes happen in userspace API and leave the in-kernel readahead unchanged(but I think some improvement can also be done here). SWAP discard As we know, discard is important for SSD write throughout, but the current swap discard implementation is synchronous. He changed it to async discard which allow discard and write run in the same time. Meanwhile, the unit of discard is also optimized to cluster. Misc: lock contention For many concurrent swapout and swapin , the lock contention such as anon_vma or swap_lock is high, so he changed the swap_lock to a per-swap lock. But there still have some lock contention in very high speed SSD because of swapcache address_space lock. Zproject (led by Bob Liu) Bob gave us a very nice introduction about the current memory compression status. Now there are 3 projects(zswap/zram/zcache) which all aim at smooth swap IO storm and promote performance, but they all have their own pros and cons. ZSWAP It is implemented based on frontswap API and it uses a dynamic allocater named Zbud to allocate free pages. Zbud means pairs of zpages are "buddied" and it can only store at most two compressed pages in one page frame, so the max compress ratio is 50%. Each page frame is lru-linked and can do shink in memory pressure. If the compressed memory pool reach its limitation, shink or reclaim happens. It decompress the page frame into two new allocated pages and then write them to real swap device, but it can fail when allocating the two pages. ZRAM Acts as a compressed ramdisk and used as swap device, and it use zsmalloc as its allocator which has high density but may have fragmentation issues. Besides, page reclaim is hard since it will need more pages to uncompress and free just one page. ZRAM is preferred by embedded system which may not have any real swap device. Now both ZRAM and ZSWAP are in driver/staging tree, and in the mm community there are some disscussions of merging ZRAM into ZSWAP or viceversa, but no agreement yet. ZCACHE Handles file page compression but it is removed out of staging recently. From industry (led by Tang Jie, LSI) An LSI engineer introduced several new produces to us. The first is raid5/6 cards that it use full stripe writes to improve performance. The 2nd one he introduced is SandForce flash controller, who can understand data file types (data entropy) to reduce write amplification (WA) for nearly all writes. It's called DuraWrite and typical WA is 0.5. What's more, if enable its Dynamic Logical Capacity function module, the controller can do data compression which is transparent to upper layer. LSI testing shows that with this virtual capacity enables 1x TB drive can support up to 2x TB capacity, but the application must monitor free flash space to maintain optimal performance and to guard against free flash space exhaustion. He said the most useful application is for datebase. Another thing I think it's worth to mention is that a NV-DRAM memory in NMR/Raptor which is directly exposed to host system. Applications can directly access the NV-DRAM via a memory address - using standard system call mmap(). He said that it is very useful for database logging now. This kind of NVM produces are beginning to appear in recent years, and it is said that Samsung is building a research center in China for related produces. IMHO, NVM will bring an effect to current os layer especially on file system, e.g. its journaling may need to redesign to fully utilize these nonvolatile memory. OCFS2 (led by Canquan Shen) Without a doubt, HuaWei is the biggest contributor to OCFS2 in the past two years. They have posted 46 upstream patches and 39 patches have been merged. Their current project is based on 32/64 nodes cluster, but they also tried 128 nodes at the experimental stage. The major work they are working is to support ATS (atomic test and set), it can be works with DLM at the same time. Looks this idea is inspired by the vmware VMFS locking, i.e, http://blogs.vmware.com/vsphere/2012/05/vmfs-locking-uncovered.html CLK - 18th October 2013 Improving Linux Development with Better Tools (Andi Kleen) This talk focused on how to find/solve bugs along with the Linux complexity growing. Generally, we can do this with the following kind of tools: Static code checkers tools. e.g, sparse, smatch, coccinelle, clang checker, checkpatch, gcc -W/LTO, stanse. This can help check a lot of things, simple mistakes, complex problems, but the challenges are: some are very slow, false positives, may need a concentrated effort to get false positives down. Especially, no static checker I found can follow indirect calls (“OO in C”, common in kernel): struct foo_ops { int (*do_foo)(struct foo *obj); } foo->do_foo(foo); Dynamic runtime checkers, e.g, thread checkers, kmemcheck, lockdep. Ideally all kernel code would come with a test suite, then someone could run all the dynamic checkers. Fuzzers/test suites. e.g, Trinity is a great tool, it finds many bugs, but needs manual model for each syscall. Modern fuzzers around using automatic feedback, but notfor kernel yet: http://taviso.decsystem.org/making_software_dumber.pdf Debuggers/Tracers to understand code, e.g, ftrace, can dump on events/oops/custom triggers, but still too much overhead in many cases to run always during debug. Tools to read/understand source, e.g, grep/cscope work great for many cases, but do not understand indirect pointers (OO in C model used in kernel), give us all “do_foo” instances: struct foo_ops { int (*do_foo)(struct foo *obj); } = { .do_foo = my_foo }; foo>do_foo(foo); That would be great to have a cscope like tool that understands this based on types/initializers XFS: The High Performance Enterprise File System (Jeff Liu) [slides] I gave a talk for introducing the disk layout, unique features, as well as the recent changes.   The slides include some charts to reflect the performances between XFS/Btrfs/Ext4 for small files. About a dozen users raised their hands when I asking who has experienced with XFS. I remembered that when I asked the same question in LinuxCon/Japan, only 3 people raised their hands, but they are Chris Mason, Ric Wheeler, and another attendee. The attendee questions were mainly focused on stability, and comparison with other file systems. Linux Containers (Feng Gao) The speaker introduced us that the purpose for those kind of namespaces, include mount/UTS/IPC/Network/Pid/User, as well as the system API/ABI. For the userspace tools, He mainly focus on the Libvirt LXC rather than us(LXC). Libvirt LXC is another userspace container management tool, implemented as one type of libvirt driver, it can manage containers, create namespace, create private filesystem layout for container, Create devices for container and setup resources controller via cgroup. In this talk, Feng also mentioned another two possible new namespaces in the future, the 1st is the audit, but not sure if it should be assigned to user namespace or not. Another is about syslog, but the question is do we really need it? In-memory Compression (Bob Liu) Same as CLSF, a nice introduction that I have already mentioned above. Misc There were some other talks related to ACPI based memory hotplug, smart wake-affinity in scheduler etc., but my head is not big enough to record all those things. -- Jeff Liu

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• ASPNET WebAPI REST Guidance

  - by JoshReuben

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

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• Informed TDD &ndash; Kata &ldquo;To Roman Numerals&rdquo;

  - by Ralf Westphal

  Originally posted on: http://geekswithblogs.net/theArchitectsNapkin/archive/2014/05/28/informed-tdd-ndash-kata-ldquoto-roman-numeralsrdquo.aspxIn a comment on my article on what I call Informed TDD (ITDD) reader gustav asked how this approach would apply to the kata “To Roman Numerals”. And whether ITDD wasn´t a violation of TDD´s principle of leaving out “advanced topics like mocks”. I like to respond with this article to his questions. There´s more to say than fits into a commentary. Mocks and TDD I don´t see in how far TDD is avoiding or opposed to mocks. TDD and mocks are orthogonal. TDD is about pocess, mocks are about structure and costs. Maybe by moving forward in tiny red+green+refactor steps less need arises for mocks. But then… if the functionality you need to implement requires “expensive” resource access you can´t avoid using mocks. Because you don´t want to constantly run all your tests against the real resource. True, in ITDD mocks seem to be in almost inflationary use. That´s not what you usually see in TDD demonstrations. However, there´s a reason for that as I tried to explain. I don´t use mocks as proxies for “expensive” resource. Rather they are stand-ins for functionality not yet implemented. They allow me to get a test green on a high level of abstraction. That way I can move forward in a top-down fashion. But if you think of mocks as “advanced” or if you don´t want to use a tool like JustMock, then you don´t need to use mocks. You just need to stand the sight of red tests for a little longer ;-) Let me show you what I mean by that by doing a kata. ITDD for “To Roman Numerals” gustav asked for the kata “To Roman Numerals”. I won´t explain the requirements again. You can find descriptions and TDD demonstrations all over the internet, like this one from Corey Haines. Now here is, how I would do this kata differently. 1. Analyse A demonstration of TDD should never skip the analysis phase. It should be made explicit. The requirements should be formalized and acceptance test cases should be compiled. “Formalization” in this case to me means describing the API of the required functionality. “[D]esign a program to work with Roman numerals” like written in this “requirement document” is not enough to start software development. Coding should only begin, if the interface between the “system under development” and its context is clear. If this interface is not readily recognizable from the requirements, it has to be developed first. Exploration of interface alternatives might be in order. It might be necessary to show several interface mock-ups to the customer – even if that´s you fellow developer. Designing the interface is a task of it´s own. It should not be mixed with implementing the required functionality behind the interface. Unfortunately, though, this happens quite often in TDD demonstrations. TDD is used to explore the API and implement it at the same time. To me that´s a violation of the Single Responsibility Principle (SRP) which not only should hold for software functional units but also for tasks or activities. In the case of this kata the API fortunately is obvious. Just one function is needed: string ToRoman(int arabic). And it lives in a class ArabicRomanConversions. Now what about acceptance test cases? There are hardly any stated in the kata descriptions. Roman numerals are explained, but no specific test cases from the point of view of a customer. So I just “invent” some acceptance test cases by picking roman numerals from a wikipedia article. They are supposed to be just “typical examples” without special meaning. Given the acceptance test cases I then try to develop an understanding of the problem domain. I´ll spare you that. The domain is trivial and is explain in almost all kata descriptions. How roman numerals are built is not difficult to understand. What´s more difficult, though, might be to find an efficient solution to convert into them automatically. 2. Solve The usual TDD demonstration skips a solution finding phase. Like the interface exploration it´s mixed in with the implementation. But I don´t think this is how it should be done. I even think this is not how it really works for the people demonstrating TDD. They´re simplifying their true software development process because they want to show a streamlined TDD process. I doubt this is helping anybody. Before you code you better have a plan what to code. This does not mean you have to do “Big Design Up-Front”. It just means: Have a clear picture of the logical solution in your head before you start to build a physical solution (code). Evidently such a solution can only be as good as your understanding of the problem. If that´s limited your solution will be limited, too. Fortunately, in the case of this kata your understanding does not need to be limited. Thus the logical solution does not need to be limited or preliminary or tentative. That does not mean you need to know every line of code in advance. It just means you know the rough structure of your implementation beforehand. Because it should mirror the process described by the logical or conceptual solution. Here´s my solution approach: The arabic “encoding” of numbers represents them as an ordered set of powers of 10. Each digit is a factor to multiply a power of ten with. The “encoding” 123 is the short form for a set like this: {1*10^2, 2*10^1, 3*10^0}. And the number is the sum of the set members. The roman “encoding” is different. There is no base (like 10 for arabic numbers), there are just digits of different value, and they have to be written in descending order. The “encoding” XVI is short for [10, 5, 1]. And the number is still the sum of the members of this list. The roman “encoding” thus is simpler than the arabic. Each “digit” can be taken at face value. No multiplication with a base required. But what about IV which looks like a contradiction to the above rule? It is not – if you accept roman “digits” not to be limited to be single characters only. Usually I, V, X, L, C, D, M are viewed as “digits”, and IV, IX etc. are viewed as nuisances preventing a simple solution. All looks different, though, once IV, IX etc. are taken as “digits”. Then MCMLIV is just a sum: M+CM+L+IV which is 1000+900+50+4. Whereas before it would have been understood as M-C+M+L-I+V – which is more difficult because here some “digits” get subtracted. Here´s the list of roman “digits” with their values: {1, I}, {4, IV}, {5, V}, {9, IX}, {10, X}, {40, XL}, {50, L}, {90, XC}, {100, C}, {400, CD}, {500, D}, {900, CM}, {1000, M} Since I take IV, IX etc. as “digits” translating an arabic number becomes trivial. I just need to find the values of the roman “digits” making up the number, e.g. 1954 is made up of 1000, 900, 50, and 4. I call those “digits” factors. If I move from the highest factor (M=1000) to the lowest (I=1) then translation is a two phase process: Find all the factors Translate the factors found Compile the roman representation Translation is just a look-up. Finding, though, needs some calculation: Find the highest remaining factor fitting in the value Remember and subtract it from the value Repeat with remaining value and remaining factors Please note: This is just an algorithm. It´s not code, even though it might be close. Being so close to code in my solution approach is due to the triviality of the problem. In more realistic examples the conceptual solution would be on a higher level of abstraction. With this solution in hand I finally can do what TDD advocates: find and prioritize test cases. As I can see from the small process description above, there are two aspects to test: Test the translation Test the compilation Test finding the factors Testing the translation primarily means to check if the map of factors and digits is comprehensive. That´s simple, even though it might be tedious. Testing the compilation is trivial. Testing factor finding, though, is a tad more complicated. I can think of several steps: First check, if an arabic number equal to a factor is processed correctly (e.g. 1000=M). Then check if an arabic number consisting of two consecutive factors (e.g. 1900=[M,CM]) is processed correctly. Then check, if a number consisting of the same factor twice is processed correctly (e.g. 2000=[M,M]). Finally check, if an arabic number consisting of non-consecutive factors (e.g. 1400=[M,CD]) is processed correctly. I feel I can start an implementation now. If something becomes more complicated than expected I can slow down and repeat this process. 3. Implement First I write a test for the acceptance test cases. It´s red because there´s no implementation even of the API. That´s in conformance with “TDD lore”, I´d say: Next I implement the API: The acceptance test now is formally correct, but still red of course. This will not change even now that I zoom in. Because my goal is not to most quickly satisfy these tests, but to implement my solution in a stepwise manner. That I do by “faking” it: I just “assume” three functions to represent the transformation process of my solution: My hypothesis is that those three functions in conjunction produce correct results on the API-level. I just have to implement them correctly. That´s what I´m trying now – one by one. I start with a simple “detail function”: Translate(). And I start with all the test cases in the obvious equivalence partition: As you can see I dare to test a private method. Yes. That´s a white box test. But as you´ll see it won´t make my tests brittle. It serves a purpose right here and now: it lets me focus on getting one aspect of my solution right. Here´s the implementation to satisfy the test: It´s as simple as possible. Right how TDD wants me to do it: KISS. Now for the second equivalence partition: translating multiple factors. (It´a pattern: if you need to do something repeatedly separate the tests for doing it once and doing it multiple times.) In this partition I just need a single test case, I guess. Stepping up from a single translation to multiple translations is no rocket science: Usually I would have implemented the final code right away. Splitting it in two steps is just for “educational purposes” here. How small your implementation steps are is a matter of your programming competency. Some “see” the final code right away before their mental eye – others need to work their way towards it. Having two tests I find more important. Now for the next low hanging fruit: compilation. It´s even simpler than translation. A single test is enough, I guess. And normally I would not even have bothered to write that one, because the implementation is so simple. I don´t need to test .NET framework functionality. But again: if it serves the educational purpose… Finally the most complicated part of the solution: finding the factors. There are several equivalence partitions. But still I decide to write just a single test, since the structure of the test data is the same for all partitions: Again, I´m faking the implementation first: I focus on just the first test case. No looping yet. Faking lets me stay on a high level of abstraction. I can write down the implementation of the solution without bothering myself with details of how to actually accomplish the feat. That´s left for a drill down with a test of the fake function: There are two main equivalence partitions, I guess: either the first factor is appropriate or some next. The implementation seems easy. Both test cases are green. (Of course this only works on the premise that there´s always a matching factor. Which is the case since the smallest factor is 1.) And the first of the equivalence partitions on the higher level also is satisfied: Great, I can move on. Now for more than a single factor: Interestingly not just one test becomes green now, but all of them. Great! You might say, then I must have done not the simplest thing possible. And I would reply: I don´t care. I did the most obvious thing. But I also find this loop very simple. Even simpler than a recursion of which I had thought briefly during the problem solving phase. And by the way: Also the acceptance tests went green: Mission accomplished. At least functionality wise. Now I´ve to tidy up things a bit. TDD calls for refactoring. Not uch refactoring is needed, because I wrote the code in top-down fashion. I faked it until I made it. I endured red tests on higher levels while lower levels weren´t perfected yet. But this way I saved myself from refactoring tediousness. At the end, though, some refactoring is required. But maybe in a different way than you would expect. That´s why I rather call it “cleanup”. First I remove duplication. There are two places where factors are defined: in Translate() and in Find_factors(). So I factor the map out into a class constant. Which leads to a small conversion in Find_factors(): And now for the big cleanup: I remove all tests of private methods. They are scaffolding tests to me. They only have temporary value. They are brittle. Only acceptance tests need to remain. However, I carry over the single “digit” tests from Translate() to the acceptance test. I find them valuable to keep, since the other acceptance tests only exercise a subset of all roman “digits”. This then is my final test class: And this is the final production code: Test coverage as reported by NCrunch is 100%: Reflexion Is this the smallest possible code base for this kata? Sure not. You´ll find more concise solutions on the internet. But LOC are of relatively little concern – as long as I can understand the code quickly. So called “elegant” code, however, often is not easy to understand. The same goes for KISS code – especially if left unrefactored, as it is often the case. That´s why I progressed from requirements to final code the way I did. I first understood and solved the problem on a conceptual level. Then I implemented it top down according to my design. I also could have implemented it bottom-up, since I knew some bottom of the solution. That´s the leaves of the functional decomposition tree. Where things became fuzzy, since the design did not cover any more details as with Find_factors(), I repeated the process in the small, so to speak: fake some top level, endure red high level tests, while first solving a simpler problem. Using scaffolding tests (to be thrown away at the end) brought two advantages: Encapsulation of the implementation details was not compromised. Naturally private methods could stay private. I did not need to make them internal or public just to be able to test them. I was able to write focused tests for small aspects of the solution. No need to test everything through the solution root, the API. The bottom line thus for me is: Informed TDD produces cleaner code in a systematic way. It conforms to core principles of programming: Single Responsibility Principle and/or Separation of Concerns. Distinct roles in development – being a researcher, being an engineer, being a craftsman – are represented as different phases. First find what, what there is. Then devise a solution. Then code the solution, manifest the solution in code. Writing tests first is a good practice. But it should not be taken dogmatic. And above all it should not be overloaded with purposes. And finally: moving from top to bottom through a design produces refactored code right away. Clean code thus almost is inevitable – and not left to a refactoring step at the end which is skipped often for different reasons.   PS: Yes, I have done this kata several times. But that has only an impact on the time needed for phases 1 and 2. I won´t skip them because of that. And there are no shortcuts during implementation because of that.

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• Block Hover Effect - Why doesn't it work correctly in FF3.6?

  - by Brian Ojeda

  Why doesn't following code work correctly in FireFox 3.6? I have tested in IE7, IE8, and Chrome with out any issues. Issue: The first block hover link (the table's 3rd row) doesn't apply the same style/effect as the following below it. Notes: I am trying to create my own table framework. This project is something I am doing to learn more about CSS. Before I started, I thought I knew a lot about CSS. However, to my surprise I was wrong. Who knew? Moving on... As side note, I do not want to take the time to support IE6. So, if you see a problem related IE6, please don't waste your time telling. One another side note, the following style script and HTML listed when this question is strip-down/bare-bone of the complete CSS/HTML. It should be enough to assist me. CSS: /* Main Properties */ .ojtable{display:block;clear:both; margin-left:auto;margin-right:auto; margin-top:0px; width:650px;} .ojtable-row, .ojtable-head {display:block;clear:both;position:relative; margin-left:0px;margin-right:0px;padding:0px;} .col-1, .col-2, .col-3, .col-4, .col-5, .col-6, .col-7, .col-8, .col-9, .col-10, .col-11, .col-12, .col-13, .col-1-b1, .col-2-b1, .col-3-b1, .col-4-b1, .col-5-b1, .col-6-b1, .col-7-b1, .col-8-b1, .col-9-b1, .col-10-b1, .col-11-b1, .col-12-b1, .col-13-b1 {display:block;float:left;position:relative; margin-left:0px;margin-right:0px;padding:0px 2px;} /* Border */ .border-b1{border:solid #000000; border-width:0 0 1px 0;} .border-ltr{border:solid #000000; border-width:1px 1px 0 1px;} /* Header */ .ojtable-row{width:100%;} .ojtable-head{width:100%;} /* No Border*/ .col-2{width:96px;} /* Border: 1px */ .col-2-b1{width:95px;} .col-7-b1{width:345px;} /*--- Clear Floated Elements ---*/ /* Credit: http://sonspring.com/journal/clearing-floats */ .clear { clear: both; display: block; overflow: hidden; visibility: hidden; width: 0; height: 0; } /* Credit: http://perishablepress.com/press/2008/02/05/ lessons-learned-concerning-the-clearfix-css-hack/ */ .clearfix:after { visibility: hidden; display: block; font-size: 0; content: " "; clear: both; height: 0; } .clearfix { display:inline-block; } /* start commented backslash hack \*/ * html .clearfix { height: 1%; } .clearfix { display: block; } /* close commented backslash hack */ /*--- Hover Effect for the Tables ---*/ a {text-decoration:none;} * .ojtable a .ojtable-row{width:650px; display:block; text-decoration:none;} * html .ojtable a .ojtable-row {width:650px;}/* Hover Fix for IE */ .ojtable a:hover .ojtable-row{background:#AAAAAA; cursor:pointer;} HTML: <div class="ojtable border-ltr clearfix"> <div class="ojtable-row border-b1 clearfix"> <div class="col-13">Newest Blogs</div> </div> <div class="ojtable-row border-b1 clearfix"> <div class="col-7-b1 border-r1">Name</div> <div class="col-4-b1 border-r1">Creater's Name</div> <div class="col-2">Dated Created</div> </div> <a href="#"><div class="ojtable-row border-b1 clearfix"> <div class="col-7-b1 border-r1">Why jQuery?</div> <div class="col-4-b1 border-r1">Gramcracker</div> <div class="col-2">Mar 11 2010</div> </div></a> <a href="#"><div class="ojtable-row border-b1 clearfix"> <div class="col-7-b1 border-r1">Thank You For Your Help</div> <div class="col-4-b1 border-r1">O'Hater</div> <div class="col-2">Nov 2 2009</div> </div></a> <a href="#"><div class="ojtable-row border-b1 clearfix"> <div class="col-7-b1 border-r1">Click Me! Hahaha!</div> <div class="col-4-b1 border-r1">Brian Ojeda</div> <div class="col-2">Nov 29 2008</div> </div></a> <a href="#"><div class="ojtable-row border-b1 clearfix"> <div class="col-7-b1 border-r1">Moment of Zen</div> <div class="col-4-b1 border-r1">Jedi</div> <div class="col-2">Mar 11 2010</div> </div></a> <a href="#"><div class="ojtable-row border-b1 clearfix"> <div class="col-7-b1 border-r1"></div> <div class="col-4-b1 border-r1">SGT OJ</div> <div class="col-2">Mar 11 2010</div> </div></a> </div> <!-- End of Table --> PS: Thank you for assistant, if you do choose to help.

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• Azure Diagnostics wrt Custom Logs and honoring scheduledTransferPeriod

  - by kjsteuer

  I have implemented my own TraceListener similar to http://blogs.technet.com/b/meamcs/archive/2013/05/23/diagnostics-of-cloud-services-custom-trace-listener.aspx . One thing I noticed is that that logs show up immediately in My Azure Table Storage. I wonder if this is expected with Custom Trace Listeners or because I am in a development environment. My diagnosics.wadcfg <?xml version="1.0" encoding="utf-8"?> <DiagnosticMonitorConfiguration configurationChangePollInterval="PT1M""overallQuotaInMB="4096" xmlns="http://schemas.microsoft.com/ServiceHosting/2010/10/DiagnosticsConfiguration"> <DiagnosticInfrastructureLogs scheduledTransferLogLevelFilter="Information" /> <Directories scheduledTransferPeriod="PT1M"> <IISLogs container="wad-iis-logfiles" /> <CrashDumps container="wad-crash-dumps" /> </Directories> <Logs bufferQuotaInMB="0" scheduledTransferPeriod="PT30M" scheduledTransferLogLevelFilter="Information" /> </DiagnosticMonitorConfiguration> I have changed my approach a bit. Now I am defining in the web config of my webrole. I notice when I set autoflush to true in the webconfig, every thing works but scheduledTransferPeriod is not honored because the flush method pushes to the table storage. I would like to have scheduleTransferPeriod trigger the flush or trigger flush after a certain number of log entries like the buffer is full. Then I can also flush on server shutdown. Is there any method or event on the CustomTraceListener where I can listen to the scheduleTransferPeriod? <system.diagnostics> <!--http://msdn.microsoft.com/en-us/library/sk36c28t(v=vs.110).aspx By default autoflush is false. By default useGlobalLock is true. While we try to be threadsafe, we keep this default for now. Later if we would like to increase performance we can remove this. see http://msdn.microsoft.com/en-us/library/system.diagnostics.trace.usegloballock(v=vs.110).aspx --> <trace> <listeners> <add name="TableTraceListener" type="Pos.Services.Implementation.TableTraceListener, Pos.Services.Implementation" /> <remove name="Default" /> </listeners> </trace> </system.diagnostics> I have modified the custom trace listener to the following: namespace Pos.Services.Implementation { class TableTraceListener : TraceListener { #region Fields //connection string for azure storage readonly string _connectionString; //Custom sql storage table for logs. //TODO put in config readonly string _diagnosticsTable; [ThreadStatic] static StringBuilder _messageBuffer; readonly object _initializationSection = new object(); bool _isInitialized; CloudTableClient _tableStorage; readonly object _traceLogAccess = new object(); readonly List<LogEntry> _traceLog = new List<LogEntry>(); #endregion #region Constructors public TableTraceListener() : base("TableTraceListener") { _connectionString = RoleEnvironment.GetConfigurationSettingValue("DiagConnection"); _diagnosticsTable = RoleEnvironment.GetConfigurationSettingValue("DiagTableName"); } #endregion #region Methods /// <summary> /// Flushes the entries to the storage table /// </summary> public override void Flush() { if (!_isInitialized) { lock (_initializationSection) { if (!_isInitialized) { Initialize(); } } } var context = _tableStorage.GetTableServiceContext(); context.MergeOption = MergeOption.AppendOnly; lock (_traceLogAccess) { _traceLog.ForEach(entry => context.AddObject(_diagnosticsTable, entry)); _traceLog.Clear(); } if (context.Entities.Count > 0) { context.BeginSaveChangesWithRetries(SaveChangesOptions.None, (ar) => context.EndSaveChangesWithRetries(ar), null); } } /// <summary> /// Creates the storage table object. This class does not need to be locked because the caller is locked. /// </summary> private void Initialize() { var account = CloudStorageAccount.Parse(_connectionString); _tableStorage = account.CreateCloudTableClient(); _tableStorage.GetTableReference(_diagnosticsTable).CreateIfNotExists(); _isInitialized = true; } public override bool IsThreadSafe { get { return true; } } #region Trace and Write Methods /// <summary> /// Writes the message to a string buffer /// </summary> /// <param name="message">the Message</param> public override void Write(string message) { if (_messageBuffer == null) _messageBuffer = new StringBuilder(); _messageBuffer.Append(message); } /// <summary> /// Writes the message with a line breaker to a string buffer /// </summary> /// <param name="message"></param> public override void WriteLine(string message) { if (_messageBuffer == null) _messageBuffer = new StringBuilder(); _messageBuffer.AppendLine(message); } /// <summary> /// Appends the trace information and message /// </summary> /// <param name="eventCache">the Event Cache</param> /// <param name="source">the Source</param> /// <param name="eventType">the Event Type</param> /// <param name="id">the Id</param> /// <param name="message">the Message</param> public override void TraceEvent(TraceEventCache eventCache, string source, TraceEventType eventType, int id, string message) { base.TraceEvent(eventCache, source, eventType, id, message); AppendEntry(id, eventType, eventCache); } /// <summary> /// Adds the trace information to a collection of LogEntry objects /// </summary> /// <param name="id">the Id</param> /// <param name="eventType">the Event Type</param> /// <param name="eventCache">the EventCache</param> private void AppendEntry(int id, TraceEventType eventType, TraceEventCache eventCache) { if (_messageBuffer == null) _messageBuffer = new StringBuilder(); var message = _messageBuffer.ToString(); _messageBuffer.Length = 0; if (message.EndsWith(Environment.NewLine)) message = message.Substring(0, message.Length - Environment.NewLine.Length); if (message.Length == 0) return; var entry = new LogEntry() { PartitionKey = string.Format("{0:D10}", eventCache.Timestamp >> 30), RowKey = string.Format("{0:D19}", eventCache.Timestamp), EventTickCount = eventCache.Timestamp, Level = (int)eventType, EventId = id, Pid = eventCache.ProcessId, Tid = eventCache.ThreadId, Message = message }; lock (_traceLogAccess) _traceLog.Add(entry); } #endregion #endregion } }

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