Written and maintained by the same author of the Eve Framework itself, Eve.NET is delivered as a portable library (PCL) and runs seamlessly on .NET4, Mono, Xamarin.iOS, Xamarin.Android, Windows Phone 8 and Windows 8. We use Eve.NET internally to power our iOS, Web and Windows applications.

And now please forgive me while I take you on a quick motivational, strongly opinionated, probably boring and overzealous detour

Python and C# Motherfucker, Do You Speak It? *

If you don’t then well, you should consider doing just that. Especially so these days, with C# and the whole .NET platform going open source and cross platform. Actually, thanks to technologies like Mono and Xamarin (also based on Mono) we have been able to run C# code on all major platforms for a while: iOS, Android, OSX, Linux, Windows, Windows Phone, you-name-it. And what’s even better, on mobile platforms C# is compiled to native so performance is a non-issue.

What makes C# a perfect match for a REST API is precisely that: it’s ubiquity. You can have a portable client library like Eve.NET which runs seamlessly (and untouched) on all these mobile desktop and server platforms.

If you already have a Web Service running on Eve and are now looking at the client side of things then well, you should consider C# and Eve.NET because you know, you can’t have a native iOS app written in Python anyway. On the other hand if you are a C#/.NET shop consider this: you can have a powerful Web Service up and running in minutes (even if you don’t grok Python yet – trust me on that) and a complete out-of-the-box, cross platform client library ready to go with it.

A few years ago I gave a talk about leaving my Comfort Zone (**) and getting out of my .NET nest. That opened the path to Python, MongoDB, Node and so many other technologies and best practices and, what’s even more relevant, most of what I learned down that path I ended up using in my .NET projects in the long run. But the point I’m trying to make is don’t be afraid of change, it can only improve your skills making you a better all-around professional programmer.

Never mind the naysayers. Polyglot is the way.

(*) I’m paraphrasing Zed A. Shaw’s Programming, Motherfucker. You should get a T-Shirt by the way. They are so cool.

(**) Since then there have been plenty of talks on the same subject. Mine was an 5 minutes ignite talk and was in Italian, so you probably don’t care (it’s on my Talks page anyway).

Back to business now.

Usage

Initialization is as simple as instantiating a new client and providing it with the web service entry point.

// Initialize and set API address.
var client = new EveClient();
client.BaseAddress = new Uri("http://api.com");

// Set target resource for subsequent requests.
client.ResourceName = "companies";

Getting a list of objects is pretty straightforward:

// List<T>
companies = await client.GetAsync<Company>();

// Objects changed since DateTime.
var ifModifiedSince = DateTime.Now.AddDays(-1);
companies = await 
  client.GetAsync<Company>(ifModifiedSince);

// Refresh an object
company = await client.GetAsync<Company>(company);

// Raw, conditional GET request
var companyId = "507c7f79bcf86cd7994f6c0e";
var eTag = "7776cdb01f44354af8bfa4db0c56eebcb1378975";

company = await 
  client.GetAsync<Company>("companies", companyId, eTag);

Other CRUD operations are easy too:

// Create (POST)
company = await 
  client.PostAsync<Company>(
    new Company { Name = "MyCompany" }
  );

// Update (PUT)
company.Name = "YourCompany";
var result = await client.PutAsync<Company>(company);

// Delete (DELETE)
var result = await client.DeleteAsync(company);

As you can see all methods are Async and return full object instances parsing JSON in and out on for you. If you need more control you can query the HttpResponse property to inspect the original JSON, response headers, status code, etc.

Behind the scenes data integrity and concurrency control are transparently handled so for example PutAsync performs a If-Match check and same happens with DeleteAsync. On PostAsync new objects are returned with fresh meta-fields such as ETag, DateCreated, DateUpdated and UniqueId. Mapping object properties to JSON fields and Eve metafields is just a matter of setting the JSonPropertyAttribute and RemoteAttribute:

public abstract class BaseClass
{
  [JsonProperty("_id")]
  [Remote(Meta.DocumentId)]
  public string UniqueId { get; set; }

  [JsonProperty("_etag")]
  [Remote(Meta.ETag)]
  public string ETag { get; set; }

  [JsonProperty("_updated")]
  [Remote(Meta.LastUpdated)]
  public DateTime Updated { get; set; }

  [JsonProperty("_created")]
  [Remote(Meta.DateCreated)]
  public DateTime Created { get; set; }   
}

public class Company : BaseClass
{
  [JsonProperty("n")]
  public string Name { get; set; }

  [JsonProperty("p")]
  public string Password { get; set; }
}

For a complete list of usage examples see the README

Current Status and License

Eve.NET is a Nicola Iarocci and Gestionali Amica open source project distributed under the BSD license. It is a work in progress but it’s pretty stable already. It is available on NuGet as a pre-release package. The test suite can be run against a local Eve instance or, if you don’t grok Python yet, you can use a free test instance which is available online, see the README for details.

Did you read this far? Well thank you! And please, consider showing your appreciation by starring the project on GitHub. It feels so lonely out there.

If you want to get in touch, I’m @nicolaiarocci on Twitter.

A margine dell’evento molte le domande su Eve, la REST API open source a cui sto lavorando e che conto di rilasciare entro fine anno: bene! Grazie a tutti i partecipanti ed a 10Gen per avermi invitato.

Soprattutto ho rilevato una forte curiosità su MongoDB, un database non-relazionale verso il quale sembra prevalere un atteggiamento  di generale timidezza: “vorrei ma non oso”, insomma. Per quanto riguarda Flask direi che ormai, nel vasto firmamento dei micro web framework, è una stella che brilla di luce propria.

Per quanto riguarda le registrazioni video potete andare su YouTube o sulla pagina ufficiale di EuroPython (english track e italian track). Ammetto di essere più soddisfatto della versione inglese nella quale – complice anche l’esperienza italiana del giorno prima – credo di essere stato più sintetico ed efficace. Qui mi limito a proporvi le slide:

Ringraziamenti

Un immenso grazie ai ragazzi dello staff di EuroPython che veramente hanno fatto di tutto per rendere questa manifestazione un evento straordinario – e ci sono riusciti  (una settimana di talk su cinque tracce parallele, sprint, hands-on, corsi, cibo di ottima qualità e credo oltre 800 partecipanti).

Vi racconto un episodio giusto per darvi l’idea di quanto questi ragazzi, tutti volontari, si diano da fare e ci mettano passione vera. Nella sessione italiana ho ‘sforato’ (capita anche ai migliori, mi dicono!) e così mi son trovato a sorvolare su un certo numero di slide. Ebbene il mio talk manager e il suo assistente mi hanno proposto di loro iniziativa di tenere una sessione pomeridiana straordinaria per consentirmi di portare a termine la mia relazione. Non capita tutti i giorni, credetemi. Per mia fortuna gran parte delle persone che avevano assistito alla sessione mattutina sono poi tornate per quella del pomeriggio, altrimenti sai che figura!

Se siete pythonisti o vorreste diventarlo non perdetevi la prossima edizione di questo evento internazionale che, con tutta probabilità, si terrà di nuovo a Firenze l’anno prossimo.

Tutto ciò significa che l’installazione di Flask MimeRender su Windows, OSX e Linux è diventato più semplice:

Codice sorgente e istruzioni sono a vostra disposizione su GitHub, mentre per spiegazione approfondita ed esempio d’uso vi rimando al mio articolo precedente: Una REST API che adatta le sue risposte al MIME Media-Type delle richieste HTTP.