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Learn how MildServer enables APL developers to create web pages easily. Manage user sessions, security, and generate HTML effortlessly. Utilize the object-oriented approach for seamless web development with APL.
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Overview of MildServer Morten Kromberg Dyalog’09 – Princeton, NJ
Goals and Philosophy • The goal is to make it possible for ”ordinary” APL developers to develop web pages • The ”MildServer” is an experimental platform for this work. • What’s the problem, anyway? Dyalog’09 - Princeton
What’s the Problem? POST /linreg.dyalog HTTP/1.1 Accept: image/gif, image/x-xbitmap, image/jpeg, image/pjpeg, application/x-ms-application, application/vnd.ms-xpsdocument, application/xaml+xml, ... blah blah blah ... Accept-Language: da Content-Type: multipart/form-data; boundary=---------------------------7d83002220638 UA-CPU: x86 User-Agent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.0; SLCC1; ... blah blah ... Content-Length: 2198 Connection: Keep-Alive Cache-Control: no-cache Cookie: UserId=mkrom; Session=dOiEkOvDgxAVdTpXZMRhpwCxpalFAI5p2pvbbhTHHAA= -----------------------------7d83002220638 Content-Disposition: form-data; name="Degree" 1 -----------------------------7d83002220638 Content-Disposition: form-data; name="X" 1 -----------------------------7d83002220638 Content-Disposition: form-data; name="Y" 2 Dyalog’09 - Princeton
The Desired Answer... HTTP/1.0 200 OK Content-Length: 2515 content-type: text/html; charset=utf-8 <html> <head> <title>Demo Server</title> <link href="/Styles/Style.css" rel="stylesheet" type="text/css"> </head> <body> <h2>Linear Regression</h2> <table > <tr> <td><form action="/linreg.dyalog" method="post" enctype="multipart/form-data"> <table> <tr><td ><b>Degree...</b></td> <td><select " name="Degree" value="1"> <option selected>1</option> <option>2</option> <option>3</option> </select>... of polynomial</td></tr> Dyalog’09 - Princeton
What’s The Problem (again)? • Decode the HTTP Headers and Data • Make data available to the application developer • (Detect and) Manage ”Sessions”: Persistence of data from one request to the next • A ”Cookie” is a bit of data stored on your PC, which is transmitted to the server with every request • A session cookie tracks a user from one page to the next • Provide Security: Identify the User and Restrict Access to parts of the Web Site • Help the application developer generate HTML • And a bit later (perhaps), more complex controls Dyalog’09 - Princeton
BIG Thanks to ”WildHeart” • I have been allowed to steal code from the ”WildServer” and other servers Stefano Lanzavecchia has built • (all the tricky bits about decoding HTTP!) • WildServer is a more complete, ”more object-oriented” HTTP server developed by Stefano • MildServer is Mortens ”watered down” environment • ”Anyone who is able to write an APL function should be able to turn it into a web page” ™ Dyalog’09 - Princeton
A MildServer Page • Each page is a class which must derive from MildPage • It must have a public function called Render which takes an instance of HTTPRequest as its argument • Render must end by calling one of: • Request.Return (HTML) • Request.ReturnFile (FileName) • Request.Fail (HTTPCode) Dyalog’09 - Princeton
Page Data • For each user session, an instance of the page class is made (object orientation is a good tool for this ) • If your page has Public Fields or Properties, MildServer will move data from the HTTP request into your page if the HTTP element has the same name • Any data inside the instance will survive until the session ends (times out after inactivity or user LogOut) Dyalog’09 - Princeton
Page Data – Example ... Dyalog’09 - Princeton
Source Code Management ... • MildServer is also a demonstration of the ”new way” of developing Dyalog applications • ALL the code is in UTF-8 text files, managed by SALT (the Simple APL Library Toolkit) • SubVersion (a free source code management system) is used to manage the source code • It is available as a download from the APL Wiki • This does not compromise the way that you develop APL applications at all ... Dyalog’09 - Princeton
MildServer Components • MildServer is a TCP/IP server which accepts connections, incoming data, and returns output • HTTPRequest is a class which decodes an HTTP Request into APL data • SimpleAuth is a basic security provider which uses the HTTP Challenge protocol based on XML input • SimpleSessions is a simple cookie-based session manager which preserves application data for the duration of a session Dyalog’09 - Princeton
MildServer Configuration Dyalog’09 - Princeton
Open, Modular Design • Note that the Session Handler and Authentication components are configurable • Each one is defined in a script file; you can enhance them or replace them • Over time, more and more of the MildServer should become configurable • The idea is that the community will build a more sophisticated shared web framework in APL Dyalog’09 - Princeton
My Own ”To Do” List • Make HTMLInput Class Extensible • Add optional Authentication Handlers • Combine SSL and certificates with passwords • Provide a more elegant security plugin using an HTML subform rather than the HTTP Challenge protocol • Error Logging and Reporting module prototyped • Run MildServer as a Windows Service (autostart when Windows starts) Dyalog’09 - Princeton
Conclusion • Proposition: • MildServer is sufficient for many ”simple” applications • Anyone who can write an APL function can implement a web site using MildServer • Scripted code does not compromise the ”APL Way” • NO additional components needed (IIS/Apache) • It is an experiment (but already in ”production” use in simple applications) ... • Please take a look and comment, and contribute! Dyalog’09 - Princeton
