Introducing SignalWire – Magical Plumbing with your Data Store + C# and LINQ in your HTML pages


ANOOP MADHUSUDANAN

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imageSignalWire is an experimental Server<->Client plumbing project I started, that magically wires up your HTML5 front end to the collections/tables in your data store or ORM, and I just pushed the first commit to Github. SignalWire uses SignalR and Roslyn libraries to implement features like

  • Exposing collections in your Back end directly over the wire for CRUD operations and for performing LINQ queries from your JavaScript.
  • Enable using C# in your HTML applications.

I got inspired by Meteor and started SignalWire as a POC to implement some of these features on the .NET stack, but I’ve got few more ideas on the way and thought about pushing this to Github.  See the codebase in Github

Check out this quick video (no sound, sorry), a simple Taskboard built using SignalWire. See how we are accessing the collections in Javascript, and check how we are issuing LINQ queries

As of now, support is available for EntityFramework and MongoDb as the back end. Also, it provides

  • A light weight permission framework (wip)
  • A Client side Javascript API to access your collections with minimal/no serverside code
  • Model Validation support using normal C#/ASP.NET Data Validation attributes
  • LINQ support to issue Linq queires from HTML pages (highly experimental, as of now no sandboxing support per caller)
  • C# code in your HTML pages (wip)

How To Start

You may start with Creating an Empty ASP.NET Project in Visual Studio 2012 (You need .NET 4.5 as we are using Roslyn September CTP libraries). Then, install SignalWire using Nuget. In Package Manager console

Install-Package SignalWire

This will add the following components to your project.

  • Models\TaskDb.cs - An example Entity Framework Data Context. You can use your instead
  • Hubs\DataHub.cs - An example Datahub.
  • Scripts\SignalWire.js - Clientside JQuery Pluin for SignalR.

Now, goto Index.html, and verify all your JS file versions are correct. Run the application and see

Server – Data Context and Hub

The Only server side code you need is your POCO objects and a hub inherited from the DataHub base class, which is defined in the SignalWire library. You need to use the Collections attribute to map a POCO class with the set/collection, and make sure you always do that in lower case.

   //Simple POCO class to represent a task
    [Collection("tasks")]
    public class Task
    {
        [Required]
        public int Id { get; set; }

        [Required]
        [MaxLength(100, ErrorMessage = "Subject cannot be longer than 40 characters.")]
        public string Subject { get; set; }

        [Required]
        [MaxLength(200, ErrorMessage = "Details cannot be longer than 40 characters.")]
        public string Details { get; set; }

        public bool Completed { get; set; }
    }


   //Simple demo db context   
    public class TaskDb : DbContext
    {
        public DbSet<Task> Tasks { get; set; }
    }

Now, you need a hub. By convention, Wire assume’s the server hub’s name as Data if it is not specified in the init method of $.wire.init(..). In the example you get when you install the Nuget package, you’ll see we are using an Entity Framework Context Provider, for TaskDb which is a DataContext. Replace TaskDb with your own EF Data context if required. Once you do that, all your collections/sets with in the context can be accessed over the wire. In the example, you’ve only on set in your TaskDb data context as you can see above - that is Tasks. Let us create the Hub.

public class Data : DataHub<EFContextProvider<TaskDb>> 

That's all you need to access collections via the Wire.

Client - Initializing and Issuing Queries

SignalWire magically exposes all your Tables/Sets/Collections in your Data back end via the $.wire Javascript object at client side. You can initialize $.wire using the init() method, which returns a JQuery Deferred. Here is a quick example regarding initializing Wire and issuing a LINQ query.

     //Initialize wire
     $.wire.init().done(function () {

      //Now you can access the tasks collection in your data context
      //You can issue a LINQ Query.
      $.wire.tasks.query("from Task t in Tasks select t")
               .done(function (result) {
                    $.each(result, function (index, task) {
                       //Do something with each task
                    });
                }).fail(function (result) {
                    alert(JSON.stringify(result.Error));
                });
         });

Other Wire Methods

You can use $.wire.yourcollection.add(..) to add objects to a specific collection. The add method will return the added item with updated Id up on completion.

    var t = {
        "subject": $("#subject").val(),
        "details": $("#details").val(),
    };


    //Add a task to the Tasks collection                    
    $.wire.tasks.add(t)
       .done(function (task) {
          //Note that you'll get the auto generated Id
       }).fail(function (result) {
            //result.Error contains the error if any                        
            //result.ValidationResults contains the Validation results if any 
            alert(JSON.stringify(result.Error)); 
       });

Similarly, you can use

  • $.wire.yourcollection.remove(item) to remove items
  • $.wire.yourcollection.update(item) to update an item (based on Id match).
  • $.wire.yourcollection.read({"query":"expression", "skip":"xxx", "take":"xxx"}) to read from a specific collection

Permissions

You can decorate your Model classes with Custom permission attributes that implements IPermission. This will check if the user in the current context can actually perform a specific operation on a Model entity.

What's More

I'm planning the following features based on my time

  • Sandboxed execution for C# scripts in HTML page that can access client side context
  • Publishing and data sync
  • Permission based events, may be using something like PushQA.

Fork on Github to play around

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