We are happy to announce the availability of WebSharper 3.3, which you can download here. The main highlight of this release is the addition of JSON serialization functions for client-side code.

The format used for this serialization is identical to the format used by inferred Sitelets. This means that you can now easily craft your request data on the client, perform an AJAX call to your Sitelets API, and parse the reply, all of this type-safely!

For example, for a website defined as follows:

open WebSharper
open WebSharper.Sitelets

type EndPoints =
    | [<EndPoint "POST /article"; Json "article">]
      PostArticle of article: Article
and Article = { title: string; body: string }

[<Website>]
let app = Sitelet.Infer <| function
    | PostArticle article ->
        let articleId = ApplicationLogic.SaveArticle article
        Content.JsonContent (fun _ -> articleId)

You can invoke the REST endpoint POST /article from the client-side like this:

[<JavaScript>]
module Client =
    open WebSharper.JavaScript
    open WebSharper.JQuery

    /// General function to send an AJAX request with a body.
    let Ajax (method: string) (url: string) (serializedData: string) : Async<string> =
        Async.FromContinuations <| fun (ok, ko, _) ->
            JQuery.Ajax(
                JQuery.AjaxSettings(
                    Url = url,
                    Type = As<JQuery.RequestType> method,
                    ContentType = "application/json",
                    DataType = JQuery.DataType.Text,
                    Data = serializedData,
                    Success = (fun (result, _, _) -> ok (result :?> string)),
                    Error = (fun (jqXHR, _, _) -> ko (System.Exception(jqXHR.ResponseText)))))
            |> ignore

    /// Use Json.Serialize and Deserialize to send and receive data to and from the server.
    let PostBlogArticle (article: Article) : Async<int> =
        async { let! response = Ajax "POST" "/article" (Json.Serialize article)
                return Json.Deserialize<int> response }

This new API is located in the module WebSharper.Json. Its only limitation compared with Sitelets is that the [<DateTimeFormat>] attribute is currently ignored, as JavaScript doesn't have built-in datetime formatting capabilities. We might consider using an external library such as moment.js for this purpose in the future.

Future plans

We have lots of exciting things to come in WebSharper. Here is what you can expect from upcoming releases:

• F# 4.0 support, including JavaScript proxies for the new collection library functions.
• A new, cleaner HTML combinator syntax. This syntax will supersede the current Html.Server, Html.Client and UI.Next.HTML with a unique type. This means that the same HTML code will be usable both from the server and client side.

Happy coding!