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F# Twitter API ServiceStack ASP.NET Web Service on Windows/Mono/OSX
(* F# Twitter API ServiceStack ASP.NET Web Service on Windows/Mono/OSX
Instructions:
1) download https://github.com/ServiceStack/ServiceStack/downloads
2) fsharpc -r:ServiceStack.Common.dll -r:ServiceStack.Interfaces.dll -r:ServiceStack.Text.dll -r:ServiceStack.dll --target:library FTweetStackAsp.fs
3) mkdir bin && cp *.dll bin
4) echo "<%@ Application Inherits=\"FTweetStack.Global\" %>" >> Global.asax
5) copy Web.config mappings from http://www.servicestack.net/ServiceStack.Hello/
6) xsp4
*)
namespace FTweetStack
open System
open ServiceStack.ServiceHost
open ServiceStack.WebHost.Endpoints
module FTweetStack =
type System.Net.WebRequest with
member x.GetResponseAsync() = Async.FromBeginEnd(x.BeginGetResponse, x.EndGetResponse)
let asyncHttp (url:string) =
async {
//printfn "downloading: %s" url
let req = System.Net.WebRequest.Create(url)
let! rsp = req.GetResponseAsync()
use stream = rsp.GetResponseStream()
use reader = new System.IO.StreamReader(stream)
return reader.ReadToEnd() }
let asyncJson url =
async {
try
return! asyncHttp url
with
| ex -> printfn "Error downloading: %s => %s" url ex.Message; return "[]" }
let batchesOf size (s: seq<'v>) =
seq {
let en = s.GetEnumerator ()
let more = ref true
while !more do
let group = [
let i = ref 0
while !i < size && en.MoveNext () do
yield en.Current
i := !i + 1 ]
if List.isEmpty group then
more := false
else
yield group }
let joinWith delim seq =
let sb = new System.Text.StringBuilder()
seq |> Seq.iter (fun x -> sb.Append((if sb.Length > 0 then delim else "") + x.ToString()) |> ignore)
sb.ToString()
let join seq = joinWith "," seq
let jsonTo<'a> json = ServiceStack.Text.JsonSerializer.DeserializeFromString<'a>(json)
type UserStat = {
mutable id: uint64;
mutable screen_name: string;
mutable name: string;
mutable friends_count: int;
mutable followers_count: int;
mutable listed_count: int;
mutable statuses_count: int }
type TwitterIds = { mutable ids: uint64[]; }
let asyncUsers screenNames = asyncJson("http://api.twitter.com/1/users/lookup.json?screen_name=" + (screenNames |> join))
let asyncFollowerIds screenName = asyncJson("http://api.twitter.com/1/followers/ids.json?screen_name=" + screenName)
let asyncFriendIds screenName = asyncJson("http://api.twitter.com/1/friends/ids.json?screen_name=" + screenName)
let asyncUserIds userIds = asyncJson("http://api.twitter.com/1/users/lookup.json?user_id=" + (userIds |> join))
let userCache = System.Collections.Concurrent.ConcurrentDictionary<uint64,UserStat>()
let usersByIds userIds =
let cachedIds, missingIds = userIds |> List.partition userCache.ContainsKey
missingIds |> batchesOf 100
|> Seq.map asyncUserIds
|> Async.Parallel |> Async.RunSynchronously
|> Seq.map jsonTo<UserStat[]>
|> Seq.collect (fun xs -> xs |> Seq.map (fun x -> userCache.TryAdd(x.id, x) |> ignore; x)) |> Seq.toList
|> List.append (cachedIds |> List.map (fun x -> userCache.TryGetValue x |> snd))
let followerIds screenName = (asyncFollowerIds screenName |> Async.RunSynchronously |> jsonTo<TwitterIds>).ids |> Array.toList
let friendIds screenName = (asyncFriendIds screenName |> Async.RunSynchronously |> jsonTo<TwitterIds>).ids |> Array.toList
let followers screenName = followerIds screenName |> usersByIds
let friends screenName = friendIds screenName |> Seq.toList |> usersByIds
let usersByNames screenNames = asyncUsers screenNames |> Async.RunSynchronously |> jsonTo<UserStat[]> |> Seq.toList
open FTweetStack
//Define Web Services
type UserStats = { mutable ScreenNames: string; }
type UserStatsService() =
interface IService<UserStats> with
member this.Execute (req:UserStats) = req.ScreenNames.Split(',') |> usersByNames :> Object
type FollowerStats = { mutable ScreenName: string; }
type FollowerStatsService() =
interface IService<FollowerStats> with
member this.Execute (req:FollowerStats) = followers req.ScreenName :> Object
type FriendsStats = { mutable ScreenName: string; }
type FriendsStatsService() =
interface IService<FriendsStats> with
member this.Execute (req:FriendsStats) = friends req.ScreenName :> Object
//Define the Web Services AppHost
type AppHost =
inherit AppHostBase
new() = { inherit AppHostBase("FTweetStack Services", typeof<UserStatsService>.Assembly ) }
override this.Configure container =
base.Routes
.Add<UserStats>("/users/{ScreenNames}")
.Add<FollowerStats>("/followers/{ScreenName}")
.Add<FriendsStats>("/friends/{ScreenName}")
|> ignore
type Global =
inherit System.Web.HttpApplication
new() = { }
member x.Application_Start() =
let appHost = new AppHost()
appHost.Init()
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