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.


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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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NuGet Package of the Week: ImageProcessor - lightweight image manipulation in C#

May 21, '14 Comments [39] Posted in NuGet | NuGetPOW
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I really enjoy image manipulation in code. Sure, resizing photos is fun in Photoshop, but there's something viscerally enjoyable when you change images with your own code.

I've talked about image resizing libraries like ImageResizer before, but there's certainly room for more than one. Today I want to showcase ImageProcessor, an open source "collection of lightweight libraries written in C# that allows you to manipulate images on-the-fly using .NET 4+." ImageProcessor is available on GitHub.

ImageProcessor

ImageProcessor methods include; Resize, Rotate, Rounded Corners, Flip, Crop, Watermark, Filter, Saturation, Brightness, Contrast, Quality, Format, Vignette, Gaussian Blur, Gaussian Sharpen, and Transparency.

ImageProcessor has a notable number of configuration options for web apps, and a supporting ImageProcessor.Web package as well. It's an impressive body of work.

I like this simple example of loading, resizing, and saving an image with their fluent API:

// Read a file and resize it.
byte[] photoBytes = File.ReadAllBytes(file);
int quality = 70;
ImageFormat format = ImageFormat.Jpeg;
Size size = new Size(150, 0)

using (MemoryStream inStream = new MemoryStream(photoBytes))
{
using (MemoryStream outStream = new MemoryStream())
{
using (ImageFactory imageFactory = new ImageFactory())
{
// Load, resize, set the format and quality and save an image.
imageFactory.Load(inStream)
.Resize(size)
.Format(format)
.Quality(quality)
.Save(outStream);
}

// Do something with the stream.
}
}

You can easily chain functions with the API, like tinting and constraning:

imageFactory.Load(inStream)
.Constrain(size)
.Tint(Color.FromArgb(255, 106, 166, 204))
.Format(format)
.Save(outStream);

When you add ImageProcessor.Web it adds caching that takes pressure off your web servers. You can easily add HttpHandlers to watermark an image, for example, and cache the result.

This is a library that has as a lot of potential. Since it's open source, I'm sure they'd appreciate help from the community! Personally, I think they could use more Unit Tests and more examples.

Head over to https://github.com/JimBobSquarePants/ImageProcessor and star this project! Get involved, file issues, and contribute! http://imageprocessor.org/

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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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NuGet Package of the Week: Humanizer makes .NET data types more human

April 9, '14 Comments [38] Posted in NuGetPOW | Open Source
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The .NET BCL (Base Class Library) moves too slow, IMHO. That's why NuGet and NuGet packages are so nice. It's a joy to find a "rightly sized" library like NodaTime, for example. It's a better date and time API for .NET. Microsoft should just use it, it's lovely.

Another nicely-sized Open Source library, and the focus for today's blog post, is Humanizer from http://humanizr.net. They say "Humanizer meets all your .NET needs for manipulating and displaying strings, enums, dates, times, timespans, numbers and quantities" and it does just that.

Install-Package Humanizer

It's a lovely joy of a library and you should check it out. Just make yourself a console app now and install-package Humanizer, and explore.

Note: Be sure to check out all the NuGet packages of the week! There's more!

The word "Humanize" evokes, for me, a feeling of making something simpler, more accessible, more useful, more fluent, more flexible.

Here's some great examples of problems that Humanizer solves.

First, Humanzer has a LOT of extension methods to the string type. If you've got a funky string, it will turn it into as close to a normally-cased sentence as possible. This is even more useful if you're using BDD frameworks like BDDfy.

"PascalCaseInputStringIsTurnedIntoSentence".Humanize() => "Pascal case input string is turned into sentence"

"Underscored_input_string_is_turned_into_sentence".Humanize() => "Underscored input string is turned into sentence"

// acronyms are left intact
"HTML".Humanize() => "HTML"

"Can_return_title_Case".Humanize(LetterCasing.Title) => "Can Return Title Case"

"CanReturnLowerCase".Humanize(LetterCasing.LowerCase) => "can return lower case"

There's dozens of great string methods, but it's the DateTime extension methods that really shine. These will feel familiar to Rails developers and Twitter users.

DateTime.UtcNow.AddHours(-30).Humanize() => "yesterday"
DateTime.UtcNow.AddHours(-2).Humanize() => "2 hours ago"

DateTime.UtcNow.AddHours(30).Humanize() => "tomorrow"
DateTime.UtcNow.AddHours(2).Humanize() => "2 hours from now"

TimeSpan.FromMilliseconds(1299630020).Humanize() => "2 weeks"
TimeSpan.FromMilliseconds(1299630020).Humanize(3) => "2 weeks, 1 day, 1 hour"

Pluralization libraries are always fun, as I've blogged before and Humanizer doesn't disappoint. You can pluralize and singularlize strings, but the "To Quantity" methods are fantastic, doing exactly what you'd expect, even if you do something odd:

"men".ToQuantity(2) => "2 men"
"process".ToQuantity(2) => "2 processes"
"process".ToQuantity(1) => "1 process"
"processes".ToQuantity(1) => "1 process"
"case".ToQuantity(0) => "0 cases"
"case".ToQuantity(1) => "1 case"

Even as words!

"case".ToQuantity(5, ShowQuantityAs.Words) => "five cases"

The Number to Words family of methods go even further:

3501.ToWords() => "three thousand five hundred and one"
121.ToOrdinalWords() => "hundred and twenty first"
8.ToRoman() => "VIII"

We've all written a truncate method to take a long string and add "..." at the end.

"Long text to truncate".Truncate(6, Truncator.FixedNumberOfCharacters) => "Long t…"
"Long text to truncate".Truncate(6, "---", Truncator.FixedNumberOfCharacters) => "Lon---"

I'm just scratching the surface of Humanizer, going through it's Getting Started. There's also samples where you can plug it into your own frameworks or deep within ASP.NET MVC and humanize enums, type names, and properties as a way to keep your code DRY.

Humanizer is even starting to support localization to non-English languages, and helping with the localization of Humanizer is a GREAT OPPORTUNITY if you're looking to get into Open Source as well as learning Git and GitHub Flow.

I like open source libraries like this that look like the code we've all written before...except tested and complete. ;) We've all written utilities like this, except as one-of functions. I look forward to NOT writing methods like this in the future, and instead using libraries like Humanizer. I fully plan to use this library in my next project (a startup I'm working on.)

Go take a look at Humanizer and thank the author on Twitter while you're at it!


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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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NuGet Package of the Week: Canopy Web Testing Framework with F#

March 25, '14 Comments [18] Posted in NuGet | NuGetPOW | Open Source
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I've been exploring Automated Browser Testing recently, and also checking out F# for unrelated reasons. However, when you combine the two you end up with "canopy." Canopy is a "f#rictionless web testing" framework that combines the flexibility of Selenium with the clean look of the F# language. F# is much terser (more elegant, even) than C#, and is garnering the interest of a lot of the .NET Open Source community. Folks are creating cool domain specific languages of their own using F# as the base.

You already have F# and perhaps didn't realize you did! If you don't, there's lots of ways to get F# for free. You can use F# for free with VS2013 Desktop Express plus Visual F# Tools 3.1.1.

F# is open source and cross platform, running on Linux, Mac OS X, Android, iOS, Windows as well as HTML5 and GPUs. F# is free to use and has an OSI-approved open source license.

Even if you don't feel like installing anything, you can learn and play with F# in your browser now! Check out http://www.tryfsharp.org 

Also check out FunScript, which is F# to JavaScript! Don't believe them? Try Pacman using F# and JavaScript with source!

image

Anyway, back to Canopy. Make a new Console app and NuGet in the canopy package:

image

The NuGet package will bring in Selenium as a dependency.

Then, try out their "Hello World" web testing sample, that I've also pasted here.

//these are similar to C# using statements
open canopy
open runner
open System

//start an instance of the firefox browser
start firefox

//this is how you define a test
"taking canopy for a spin" &&& fun _ ->
//this is an F# function body, it's whitespace enforced

//go to url
url "http://lefthandedgoat.github.io/canopy/testpages/"

//assert that the element with an id of 'welcome' has
//the text 'Welcome'
"#welcome" == "Welcome"

//assert that the element with an id of 'firstName' has the value 'John'
"#firstName" == "John"

//change the value of element with
//an id of 'firstName' to 'Something Else'
"#firstName" << "Something Else"

//verify another element's value, click a button,
//verify the element is updated
"#button_clicked" == "button not clicked"
click "#button"
"#button_clicked" == "button clicked"

//run all tests
run()

System.Console.WriteLine("press [enter] to exit")
System.Console.ReadLine() |> ignore

quit()

And boom, it just works. You can run this .NET application just like any other. .NET apps are .NET apps, as they say. It doesn't matter what language it's written in. When (if) you distribute this application you'd just include the contents of your Debug folder. No need to "install" F# or anything on the target machine.

image

You can do all sorts of Selenium testing with canopy, like:

//start a bunch of browsers and switch around
start firefox
let mainBrowser = browser
start chrome
let secondBrowser = browser
//switch back to mainBrowser after opening secondBrowser
switchTo mainBrowser

//take screenshots
let path = Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData) + @"\canopy\"
let filename = DateTime.Now.ToString("MMM-d_HH-mm-ss-fff")
screenshot path filename

//get an element
element "#firstName" |> someParent

//press buttons
press tab
press enter
press down
press up
press left
press right

//check and click things
check "#yes"
click "#login"

//or even drag things!
drag ".todo" ".inprogress"

Oh, and by the way, the canopy library builds itself using FAKE, the F# Build System we talked about last week! Go check these projects out and offer to help or support them. There's a lot of interesting open source happening in the .NET space lately that may have been flying under your radar.

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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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NuGet Package of the Week: FluentAutomation for automated testing of Web Applications

March 4, '14 Comments [25] Posted in NuGet | NuGetPOW | Open Source
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FluentAutomation starting a testLast week I was exploring today's varied choices we have for Automated Browser Testing. There's headless WebKit "browsers" like PhantomJS and cloud powered multi-browser testing tools like BrowserStack and SauceLabs.

Selenium is kind of the gold standard and offers not only a lot of "drivers" but also a lot of language bindings with which drive a browser. Sometimes browsers update so fast there can be some version incompatibilities with Selenium, but for the most part it works great once you've settled in.

One option I've been looking at is FluentAutomation. It's a fluent automation API that supports Selenium as well as WatiN along with all their flavors and drivers. Since Fluient supports Selenium, that means you can use the Selenium ChromeDriver, IEDriver, Remote Web Driver or even the headless PhantomJS. FluentAutomation is on GitHub, of course, as well as on NuGet.

FluentAutomation has great (and growing) documentation and has adopted and interesting fluent style for it's API.

Now, not everyone likes a "fluent" API so it may take a while to get used to. Often you'll be doing things over many lines when it's really just one line, for example, this is one line:

I.Open("http://automation.apphb.com/forms")
.Select("Motorcycles").From(".liveExample tr select:eq(0)")
.Select(2).From(".liveExample tr select:eq(1)")
.Enter(6).In(".liveExample td.quantity input:eq(0)")
.Expect
.Text("$197.72").In(".liveExample tr span:eq(1)")
.Value(6).In(".liveExample td.quantity input:eq(0)");

Notice the method chaining as well as the use of CSS selectors.

FluentAutomation also has the cool concept of a PageObject to take your potentially brittle scripts and give them more structure. PageObjects group your actions, expectations, and assertions and let you reuse code when a page appears in multiple tests.

For example you could have a high level test (this is XUnit, but you can use whatever you want):

public class SampleTest : FluentTest {
public SampleTest() {
SeleniumWebDriver.Bootstrap(SeleniumWebDriver.Browser.Chrome);
}

[Fact]
public void SearchForFluentAutomation() {
new BingSearchPage(this)
.Go()
.Search("FluentAutomation")
.FindResultUrl("http://fluent.stirno.com/blog/FluentAutomation-scriptcs/");
}
}

Then you can have separate PageObjects that have your own public methods specific to that page, as well as assertions you can reuse.

public class BingSearchPage : PageObject<BingSearchPage> {
public BingSearchPage(FluentTest test) : base(test) {
Url = "http://bing.com/";
At = () => I.Expect.Exists(SearchInput);
}

public BingSearchResultsPage Search(string searchText) {
I.Enter(searchText).In(SearchInput);
I.Press("{ENTER}");
return this.Switch<BingSearchResultsPage>();
}

private const string SearchInput = "input[title='Enter your search term']";
}

public class BingSearchResultsPage : PageObject<BingSearchResultsPage> {
public BingSearchResultsPage(FluentTest test) : base(test) {
At = () => I.Expect.Exists(SearchResultsContainer);
}

public BingSearchResultsPage FindResultUrl(string url) {
I.Expect.Exists(string.Format(ResultUrlLink, url));
return this;
}

private const string SearchResultsContainer = "#b_results";
private const string ResultUrlLink = "a[href='{0}']";
}

You don't have to be all structure and OO if you don't want. You can just as easily write scripts with FluentAutomation and head in a different direction.

FluentAutomation along with ScriptCS = Automating your Browser with C# Script

I've usually used Python with my Selenium scripts. I like being able to just make a text file and start scripting, then run, debug, continue, all from the command line. It feels simple and lightweight. Creating a DLL and running Unit Tests in C# usually comes later, as I can move faster with a "scripting language."

You can do that with ScriptsCS as it gives you project-less C# that effectively is C# as scripting language. Combine this with FluentAutomation and you've potentially got the best of both worlds.

To install, first you need the Windows apt-get open source equivalent, the oddly-named and -spelled Chocolatey. Then you get ScriptCS and the packages for FluentAutomation.

  • Install Chocolatey - one line installation here
  • Run "cinst ScriptCS" from your command line to use Chocolatey to install ScriptCS
  • Now, get the ScriptCS script packages for FluentAutomation like this:
    • scriptcs -install FluentAutomation.SeleniumWebDriver
    • scriptcs -install ScriptCs.FluentAutomation

Now, as a quick test, create a folder and put a text file called start.csx in it with just these contents:

var Test = Require<F14N>()
.Init<FluentAutomation.SeleniumWebDriver>()
.Bootstrap("Chrome")
.Config(settings => {
// Easy access to FluentAutomation.Settings values
settings.DefaultWaitUntilTimeout = TimeSpan.FromSeconds(1);
});

Test.Run("Hello Google", I => {
I.Open(http://google.com);
});

Notice how there's no namespace, no classes, no main. It's just a script, except it's using C#. You can change the "Chrome" to "IE" or "Firefox" as well, to play around.

Random: I love this Selenium feature, exposed by FluentAutomation...take screenshot!

// Take Screenshot
I.TakeScreenshot("LoginScreen");

If you don't want ScriptCS, while it can act as a REPL itself, there is also the start of a dedicated FluentAutomation REPL (read–eval–print loop). This is basically a command prompt that lets you explore you app interactively and facilitates building your scripts. You can get the Repl as a Chocolatey package as well and just "cinst FluentAutomation.Repl"

You've got LOTS of choices in the world of automated testing. There's so many choices that there's just no good excuse. Pick a library, pick a language, and start automating your web app today.

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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.