HTTP Server
lazarus / 38-Networking and Web Programming

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johnsson · 2016-04-26 00:38

First things first. I'm sorry for my bad english.

Hi guys.

I am using Lazarus/Free pascal at my Master Degree work, coding a
multithread application for accelarate some things etc... Well, one
part of this work involve (maybe in the future) a application running
in multiple computers at the same time like distributed computing.

So, for this I' m working in a High Performance HTTP Server/JSON
WebService with load balance, and maybe I' ll publish this somewhere
(Like SourceForge) when I finish a beta version or whatever, but I' m
not pretty sure if this is good enough or someone will be use. So I'
ll put some code/ideas here about this project and please be free to
comment.

Done

1- HTTP Server (Single Thread, Multi Threaded and Pool of Threads)
2- Advanced Route resolutions (With url params, fixed params and
without params)
3- RPC JSON
4- Pool of Connections (SQLdb)
5- Thread Manager to create and destroy threads dynamically
6- Custom Exception Class (Webservice and RPC)
7- Load Balance with group of servers (We can define a group of
servers to process one or more specific methods of webservice)

I' m working now

1- HTTPS Server
2- Pool of connection (ZeosLib)
3- Add and Remove servers from load balance in runtime.

To do

1- Better options to load balance
2- RPC JSON with HTTP (I' m using only TCP)
3- More optimizations in assembly/SIMD

Well, here it's a sample code about a function add two numbers

Code: [Select]  // First we need register the route
  //Variable types string, integer and double is accepted, I' m still
working in other types
  WSAppRoute.AddRoute('api/math/add/@Integer;@Integer',@FuncAdd,[wsGet
]);

  // Second is the function

function FuncAdd(AData: string; AMethod: THTTPRequisition; AParams:
TStringList; ANumber1, ANumber2: Integer): string;
begin
  // Always will be wsGet because I don't put other option together,
if the server receive a wsPost in this case, a code error 404 will be
returned
  if AMethod = wsGet then
  begin
    Result := IntToStr(ANumber1 + ANumber2);
  end;
end;

// After

  Server := THTTPServer.Create(8080);
  Server.Active := True;


Call example

URL: localhost:8080/api/math/add/80&20
Result: 100

URL: localhost:8080/api/math/add/Hi&20
Result: Error 404

URL: localhost:8080/api/math/add/100&20
Result: 120

URL: localhost:8080/api/math/sub/100&20
Result: Error 404

About RPC Module, here is a simple example. (Server side)

Code: [Select]TMathAdd = class(Tobject)
private
public
published
  procedure Invoke;
  
  property Number1: Integer;
  property Number2: Integer;
  property Result: Integer;
end;

procedure TMathAdd.Invoke;
begin
   FResult := FNumber1 + FNumber2;
end;

// Register the class

  Server := TRPCJSONServer.Create;
  Server.AddMethod(TMathAdd);
  Server.PortNumber := 6900;
  Server.StartServer;


Client Side

Code: [Select]var
  Method: TRPCJSONClient;
  Error: Boolean;
  Message: string;
  JReturn: TJSONData;
begin
  Method  := TRPCJSONClient.Create('write.the-rpc-server.here',6900);
  Message := EmptyStr;
  JReturn := Nil;
  try
    JReturn :=
Method.ExecuteMethod('MathAdd',[100,63],Method.NewID,Error);
    ShowMessage(JReturn.AsJson);
  except
    on E: Exception do begin
      Message := E.Message;
    end;
  end;   

This code above will return 163. The prototype of function
ExecuteMethod is

Code: [Select]  function ExecuteMethod(AMethod: string; const AArgs:
array of const; AID: Integer; out AError: Boolean): TJSONData;  

The server side is prepared to response cases below.

1) Sucess

{"jsonrpc": "2.0", "result": 163, "id": 1}

or

2) Error

-32700    Parse error
-32600    Invalid Request
-32601    Method not found
-32602    Invalid params
-32603    Internal error
-32000 to -32099    Server error

According http://www.jsonrpc.org/specification

So, later I' ll put others examples with load balance.

Cya

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Leledumbo · 2016-04-26 10:11

Mind backporting HTTPS support to fphttpserver? I'm not sure about
your HTTP(S) server if it's written from scratch or based on
fphttpserver.

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Graeme · 2016-04-26 16:16

Sounds very interesting. Keep up the hard work.

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johnsson · 2016-04-27 15:04

Quote from: Leledumbo on April 26, 2016, 12:11:53 pmMind backporting
HTTPS support to fphttpserver? I'm not sure about your HTTP(S) server
if it's written from scratch or based on fphttpserver.


This project is written with synapse, so the support to HTTPS is
provide by them.

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johnsson · 2016-05-14 04:55

Up.

1- New things in project.
2- I' m using jmeter to benchmark. (Any suggestion of other program? 
)

Cya