Scott Hanselman

NuGet Package of the Week: ASP.NET Web API Caching with CacheCow and CacheOutput

June 27, '14 Comments [9] Posted in ASP.NET Web API | NuGet | NuGetPOW
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You can see other cool NuGet Packages I've mentioned on the blog here. Today's NuGet package is CacheCow, which has possibly the coolest Open Source Library name since Lawnchair.js.

image

"CacheCow is a library for implementing HTTP caching on both client and server in ASP.NET Web API. It uses message handlers on both client and server to intercept request and response and apply caching logic and rules."

CacheCow was started by Ali Kheyrollahi with help from Tugberk Ugurlu and the community, and is a fantastically useful piece of work. I wouldn't be surprised to see this library start showing in more places one day.

As an aside, Ali, this would be a great candidate for setting up a free AppVeyor Continuous Integration build along with a badge showing that the project is building and healthy!

CacheCow on the server can manage the cache in a number of ways. You can store it in SQL Server with the EntityTagStore, or implement your own storage handler. You can keep the cache in memcached, Redis, etc.

Consider using a library like CacheCow if you're putting together a Web API and haven't given sufficient thought to caching yet, or if you're already sprinkling cache code throughout your business logic. You might already suspect that is going to litter your code but perhaps haven't gotten around to tidying up. Now is a good time to unify your caching.

As a very simple example, here's the HTTP Headers from an HTTP GET to a Web API:

Cache-Control: no-cache
Content-Length: 19
Content-Type: application/json; charset=utf-8
Date: Fri, 27 Jun 2014 23:22:10 GMT
Expires: -1
Pragma: no-cache

Here's the same thing after adding the most basic caching to my ASP.NET applications config:

GlobalConfiguration.Configuration.MessageHandlers.Add(new CachingHandler(GlobalConfiguration.Configuration));

The HTTP Headers with the same GET with CacheCow enabled:

Cache-Control: no-transform, must-revalidate, max-age=0, private
Content-Length: 19
Content-Type: application/json; charset=utf-8
Date: Fri, 27 Jun 2014 23:24:16 GMT
ETag: W/"e1c5ab4f818f4cde9426c6b0824afe5b"
Last-Modified: Fri, 27 Jun 2014 23:24:16 GMT

Notice the Cache-Control header, the Last-Modified, and the ETag. The ETag is weak as indicted by "W/" which means that this response is semantically equivalent to the last response. If I was caching persistently, I could get a strong ETag indicating that the cached response was byte-for-byte identical. Also, if the client was smart about caching and added If-Modified-Since or If-None-Match for ETags, the response might be a 304 Not Modified, rather than a 200 OK. If you're going to add caching to your Web API server, you'll want to make sure your clients respect those headers fully!

From ALI's blog, you can still use HttpClient in your clients, but you use WebRequestHandler as the message handler:

HttpClient client = new HttpClient(new WebRequestHandler()
{
CachePolicy = new RequestCachePolicy(RequestCacheLevel.Default)
});
var httpResponseMessage = await client.GetAsync(http://superpoopy);

Really don't want a resource cached? Remember, this is HTTP so, Cache-Control: no-cache from the client!

Of course, one of the most important aspects of caching anything is "when do I invalidate the cache?" CacheCow gives you a lot control over this, but you really need to be aware of what your actual goal is or you'll find things cache you don't want, or things not cached that you do.

  • Are you looking for time-based caching? Cache for 5 min after a DB access?
  • Are you looking for smart caching that invalidates when it sees what could be a modification? Invalidate a collection after a POST/PUT/DELETE?

Given that you're likely using REST, you'll want to make sure that the semantics of these caching headers and their intent is reflected in your behavior. Last-Modified should reflect realty when possible.

From the CacheCow Wiki, there's great features for both the Server-side and Client-side. Here's CacheCow.Server features

  • Managing ETag, Last Modified, Expires and other cache related headers
  • Implementing returning Not-Modified 304 and precondition failed 412 responses for conditional calls
  • Invalidating cache in case of PUT, POST, PATCH and DELETE
  • Flexible resource organization. Rules can be defined so invalidation of a resource can invalidate linked resources

and the CacheCow.Client features

  • Caching GET responses according to their caching headers
  • Verifying cached items for their staleness
  • Validating cached items if must-revalidate parameter of Cache-Control header is set to true. It will use ETag or Expires whichever exists
  • Making conditional PUT for resources that are cached based on their ETag or expires header, whichever exists

Another good ASP.NET caching library to explore is ASP.NET Web API "CacheOutput" by Filip Wojcieszyn. While it doesn't have an fun to say name ;) it's got some great features and is super easy to get started with. You can find CacheOutput with NuGet at

Install-Package Strathweb.CacheOutput.WebApi2

And you'll configure your caching options using the intuitive CacheOutput attributes like those you may have seen in ASP.NET MVC:

[CacheOutput(ClientTimeSpan = 100, ServerTimeSpan = 100)]
public IEnumerable<string> Get()
{
return new string[] { "value1", "value2" };
}

ASP.NET Web API CacheOutput has great getting started docs and clear easy to ready code.

So, you've got options. Go explore!

You can also pickup the Pro ASP.NET Web API book at Amazon. Go explore CacheCow or CacheOutput and support open source! If you find issues or feel there's work to be done in the documentation, why not do it and submit a pull request? I'm sure any project would appreciate some help with updated samples, quickstarts, or better docs.


Sponsor: Many thanks to our friends at Octopus Deploy for sponsoring the feed this week. Did you know that NuGet.org deploys with Octopus? Using NuGet and powerful conventions, Octopus Deploy makes it easy to automate releases of ASP.NET applications and Windows Services. Say goodbye to remote desktop and start automating today!

About Scott

Scott Hanselman is a former professor, former Chief Architect in finance, now speaker, consultant, father, diabetic, and Microsoft employee. He is a failed stand-up comic, a cornrower, and a book author.

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Trying Redis Caching as a Service on Windows Azure

June 25, '14 Comments [15] Posted in Azure
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redis_logo

First, if you have already have an MSDN subscription (through your work, whatever) make sure to link your MSDN account and an Azure Account, otherwise you're throwing money away. MSDN subscribers get between US$50 and US$150 a month in free Azure time, plus a 33% discount on VMs and 25% off Reserved Websites.

Next, log into the Azure Preview Portal at https://portal.azure.com.  Then, go New | Redis Cache to make a new instance. The Redis Cache is in preview today and pricing details are here. both 250 meg and 1 GB caches are free until July 1, 2014 so you've got a week to party hard for free.

image

Of course, if you're a Redis expert, you can (and always could) run your own VM with Redis on it. There's two "Security Hardened" Ubuntu VMs with Redis at the MS Open Tech VMDepot that you could start with.

I put one Redis Cache in Northwest US where my podcast's website is.  The new Azure Portal knows that these two resources are associated with each other because I put them in the same resource group.

image

There's Basic and Standard. Similar to Website's "basic vs standard" it comes down to Standard you can count on, it has an SLA and replication setup. Basic doesn't. Both have SSL, are dedicated, and include auth. I'd think of Standard as being "I'm serious about my cache" and Basic is "I'm messing around."

There are multiple caching services (or Cache as a Service) on Azure.

  • Redis Cache: Built on the open source Redis cache. This is a dedicated service, currently in Preview.
  • Managed Cache Service: Built on AppFabric Cache. This is a dedicated service, currently in General Availability.
  • In-Role Cache: Built on App Fabric Cache. This is a self-hosted cache, available via the Azure SDK.

Having Redis available on Azure is nice since my startup MyEcho uses SignalR and SignalR can use Redis as the backplane for scaleout.

Redis Server managing SignalR state

Marc Gravell (with a "C") over at StackExchange/StackOverflow has done us all a service with the StackExchange.Redis client for .NET on NuGet. Getting stuff in and out of Redis using .NET is very familiar to anyone who has used a distributed Key Value store before.

  • BONUS: There's also ServiceStack.Redis from https://servicestack.net that includes both the native-feeling IRedisNativeClient and the more .NET-like IRedisClient. Service Stack also supports Redis 2.8's new SCAN operations for cursoring around large data sets.
ConnectionMultiplexer connection = ConnectionMultiplexer.Connect("contoso5.redis.cache.windows.net,ssl=true,password=...");

IDatabase cache = connection.GetDatabase();

// Perform cache operations using the cache object...
// Simple put of integral data types into the cache
cache.StringSet("key1", "value");
cache.StringSet("key2", 25);

// Simple get of data types from the cache
string key1 = cache.StringGet("key1");
int key2 = (int)cache.StringGet("key2");

In fact, the ASP.NET team announced just last month the ASP.NET Session State Provider for Redis Preview Release that you may have missed. Also on NuGet (as a -preview) this lets you point the Session State of your existing (perhaps legacy) ASP.NET apps to Redis.

After pushing and pulling data out of Redis for a while, you'll notice how nice the new dashboard is. It gives you a great visual sense of what's going on with your cache. You see CPU and Memory Usage, but more importantly Cache Hits and Misses, Gets and Sets, as well as any extraordinary events you need to know about. As a managed service, though, there's no need to sweat the VM (or whatever) that your cache is running on. It's handled.

image

From the Azure Redis site:

Perhaps you're interested in Redis but you don't want to run it on Azure, or perhaps even on Linux. You can run Redis via MSOpenTech's Redis on Windows fork. You can install it from NuGet, Chocolatey or download it directly from the project github repository. If you do get Redis for Windows (super easy with Chocolatey), you can use the redis-cli.exe at the command line to talk to the Azure Redis Cache as well (of course!).

It's easy to run a local Redis server with redis-server.exe, test it out in develoment, then change your app's Redis connection string when you deploy to Azure.


Sponsor: Many thanks to our friends at Octopus Deploy for sponsoring the feed this week. Did you know that NuGet.org deploys with Octopus? Using NuGet and powerful conventions, Octopus Deploy makes it easy to automate releases of ASP.NET applications and Windows Services. Say goodbye to remote desktop and start automating today!

About Scott

Scott Hanselman is a former professor, former Chief Architect in finance, now speaker, consultant, father, diabetic, and Microsoft employee. He is a failed stand-up comic, a cornrower, and a book author.

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Exploring cross-browser math equations using MathML or LaTeX with MathJax

June 23, '14 Comments [11] Posted in Tools
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Let me just start by saying that I got a C in Calculus. It just didn't click for me. I'm aces at basic math, but you lost me at limits. That said, I have always found MathML to be fascinating, and I'm surprised that even now over 15 years after MathML's first release that is has such minimal browser support. Other than Firefox, and surprisingly iOS Safari, there's basically no widely available native support.

Perhaps it's because MathML is, well, XML. You wanna express something simple like 2+2, except stacked up with a line? Here's that:

<mstack>
<mn>2</mn>
<msrow> <mo>+</mo> <none/> <mn>2</mn> </msrow>
<msline/>
</mstack>

That's rather verbose. Most math folks that I've talked to (including a very nice Stanford professor I met on a plane recently) use LaTeX to express Math. The professor I met edited whole academic papers in raw LaTeX and compiled them to PDF. He was surprised when I explained that he was a programmer but perhaps didn't realize it!

LaTeX looks like this, for the 2+2 example:

\(2+2\)

I'd show you some more complex MathML examples but it would get pretty crazy very quickly.

The landscape for writing equations easily online using either MathML or LaTeX is, from my untrained eye, rather chaotic, link-rotty, and messy. Many Math and MathML online resources are full of link rot or their apps have been forgotten. While looking for a MathML to LaTeX convertor I found four different sits that promised to deliver only to discover that their back end systems are gone.

It seems that there are two places online that are shining examples of online Math rendering and that's MathJax and Math.StackExchange.com. MathJax is "an open source JavaScript display engine for mathematics that works in all browsers" and Math.StackOverflow.com is well, StackOverflow for Math people. What's special about Math.SO is that it's integrated MathJax's fantastic library into it's main editor.

NOTE: Not all StackExchange sites have the integrated math preview due to the size of the libraries involves. It's not something that you just "throw in just in case."

Here's an example where I'm typing some LaTeX into StackOverflow's site. In this case, I'm using Chrome.

image

They are using MathJax's library here. I can right-click on the equation, and ask "show math as MathML" and get this popup:

image

How does MathJax manage all this without actual browser support for MathML (or LaTeX?)

You configure MathJax like this, telling it what to look for when doing inline math. Sometimes it's bracketed by $ and $ and sometimes by \( and \).

<script type="text/x-mathjax-config">
MathJax.Hub.Config({
tex2jax: { inlineMath: [['$','$'],['\\(','\\)']] }
});
</script>
<script type='text/javascript' src='http://cdn.mathjax.org/mathjax/latest/MathJax.js?config=TeX-AMS-MML_HTMLorMML'></script>

For Tex as in this example, MathJax is using HTML and CSS, generating the inline Math equations into a series of DOM elements.

image

When using MathML proper, you can configure MathJax to use native MathML rendering when it's available. Only FireFox really supports that. This page lets you switch between HTML-CSS using Web Fonts, MathML, or SVG. SVG looks a little rough to me, but HTML-CSS always looks nice.

image

Bottom line, if you have a need to express mathematical equations of any kind online, you're going to want to use MathJax. Love them, thank them, appreciate them.

NOTE via Wikipedia: The MathJax project was founded by the American Mathematical Society, Design Science, and the Society for Industrial and Applied Mathematics and is supported by numerous sponsors such as the American Institute of Physics and Stack Exchange.

Oh, and if you're English, "Maths."


Sponsor: Many thanks to our friends at Octopus Deploy for sponsoring the feed this week. Did you know that NuGet.org deploys with Octopus? Using NuGet and powerful conventions, Octopus Deploy makes it easy to automate releases of ASP.NET applications and Windows Services. Say goodbye to remote desktop and start automating today!

About Scott

Scott Hanselman is a former professor, former Chief Architect in finance, now speaker, consultant, father, diabetic, and Microsoft employee. He is a failed stand-up comic, a cornrower, and a book author.

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Download Visual Studio Express

June 19, '14 Comments [31] Posted in Tools
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http://downloadvisualstudio.com

visual-studio-2013-logoYou liked http://downloadsqlserverexpress.com, so, here's http://downloadvisualstudio.com because I like you so much.

Here are the direct links to all the Express SKUs for Visual Studio. They are all completely free.

NOTE: I wrote this post on my own, and not as a representative of Microsoft. That's their copyrighted logo over there on the right, and these downloads are all Microsoft's.

Visual Studio 2013 Express for Web

Visual Studio Express 2013 for Web provides the core tools for creating compelling, innovative web applications and services. This includes the ASP.NET editors for HTML5, CSS3, JavaScript, etc.

Visual Studio 2013 Express for Windows (Desktop)

Visual Studio Express 2013 for Windows Desktop enables the creation of desktop apps in C#, Visual Basic, and C++, and supports Windows Presentation Foundation (WPF), Windows Forms, and Win32.

Visual Studio 2013 Express for Windows (Store)

The tools include a full-featured code editor, a powerful debugger, a focused profiler, and rich language support that you can use to build apps that you write in HTML5/JavaScript, C++, C#, or Visual Basic. Visual Studio Express 2013 for Windows also includes tools for Windows Phone 8.0 development and Windows Phone emulators that you can use to test how your Windows Phone apps will run on different devices.

Microsoft Visual Studio Team Foundation Server Express 2013

Visual Studio Team Foundation Server Express 2013 is a source-code-control, project-management, and team-collaboration platform at the core of the Microsoft suite of Application Lifecycle Management (ALM) tools.

Hope this helps! All these links were dug out of http://www.visualstudio.com/downloads/download-visual-studio-vs with Fiddler.


Sponsor: A big thank you to my friends at Octopus Deploy. They are sponsoring the blog feed this week. Using NuGet and powerful conventions, Octopus Deploy makes it easy to automate releases of ASP.NET applications and Windows Services. Say goodbye to remote desktop and start automating today!

About Scott

Scott Hanselman is a former professor, former Chief Architect in finance, now speaker, consultant, father, diabetic, and Microsoft employee. He is a failed stand-up comic, a cornrower, and a book author.

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Download SQL Server Express

June 17, '14 Comments [56] Posted in Tools
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There's a funny blog post about how to download SQL Server Express from Long Zheng. It surprisingly how complex some companies make downloading things. I've always thought that a giant Download Now button is the best way, but perhaps that's just me?

Downloading SQL Server Express is unnecessarily hard, and it's made harder by the new Microsoft Download Center "download multiple files" interface that doesn't include descriptions or primary file recommendations. It should be a list of links, and you should be able to right click and Save As.

Introducing http://downloadsqlserverexpress.com 
(this short link goes directly to this post)

So, I've done the HTTP sniffing and work, and written this blog post in the hopes that it helps you (and I'm bookmarking it for myself, for the future).

Download SQL Server 2014 Express

Download SQL Server 2012 Express

Download SQL Server 2008 Express R2 SP2

You can get back here via downloadsqlserverexpress.com. Tell your friends.


Sponsor: A big thank you to my friends at Octopus Deploy. They are sponsoring the blog feed this week. Using NuGet and powerful conventions, Octopus Deploy makes it easy to automate releases of ASP.NET applications and Windows Services. Say goodbye to remote desktop and start automating today!

About Scott

Scott Hanselman is a former professor, former Chief Architect in finance, now speaker, consultant, father, diabetic, and Microsoft employee. He is a failed stand-up comic, a cornrower, and a book author.

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Disclaimer: The opinions expressed herein are my own personal opinions and do not represent my employer's view in any way.