[paganel]

> except for one piece of technology that saved them all: AJAX.

We have to thank the MS Office guys for that. Also interesting how RPCs have become cool again, even though under different names, one would have thought that the whole REST thing would have had the better of them.

[pdntspa]

The way everyone seems to demand finished API libraries like spoiled children, it would seem we are building RPC right on the back of REST.

[paganel]

> it would seem we are building RPC right on the back of REST

Yeah, that, most definitely, but as I've stopped following that space some many years ago (I used to be a REST groupie) I didn't know how best to put it.

[DonHopkins]

https://en.wikipedia.org/wiki/NeWS

NeWS was architecturally similar to what is now called AJAX, except that NeWS coherently:

- used PostScript code instead of JavaScript for programming.

- used PostScript graphics instead of DHTML and CSS for rendering.

- used PostScript data instead of XML and JSON for data representation.

http://www.chilton-computing.org.uk/inf/literature/books/wm/...

Methodology of Window Management: 29 April 1985: 5. SunDew [nee NeWS] - A Distributed and Extensible Window System: James Gosling

5.1 INTRODUCTION

SunDew is a distributed, extensible window system that is currently being developed at SUN. It has arisen out of an effort to step back and examine various window system issues without the usual product development constraints. It should really be viewed as speculative research into the right way to build a window system. We started out by looking at a number of window systems and clients of window systems, and came up with a set of goals. From those goals, and a little bit of inspiration, we came up with a design.

GOALS

A clean programmer interface: simple things should be simple to do, and hard things, such as changing the shape of the cursor, should not require taking pliers to the internals of the beast. There should be a smooth slope from what is needed to do easy things, up to what is needed to do hard things. This implies a conceptual organization of coordinated, independent components that can be layered. This also enables being able to improve or replace various parts of the system with minimal impact on the other components or clients.

Similarly, the program interface probably should be procedural, rather than simply exposing a data structure that the client then interrogates or modifies. This is important for portability, as well as hiding implementation details, thereby making it easier for subsequent changes or enhancements not to render existing code incompatible.

Retained windows: a clean programmer interface should completely hide window damage from the programmer. His model of a window should be just that it is a surface on which he can write, and that it persists. All overlap issues should be completely hidden from the client. I believe that the amount of extra storage required to maintain the hidden bitmaps on a black and white display is negligible - based on the observation that people generally do not stack windows very deeply. The situation is somewhat different with colour, but there are games to be played. Retained windows is one way of hiding window damage, but we do not want to commit to a particular solution to this problem at this time.

Flexibility: users need to attach devices, change menu behaviours and generally modify almost all components of the system. For example, the menu package ought to be independent of the particular format or contents of the menu, thereby allowing the user to develop his own idioms without having to reimplement the entire system. [This paragraph is what caught my attention and excited me during the time I was experimenting with pie menus on X10, because of SunDew's/NeWS's ability to redefine all menus in the system to use pie menus. See: "Just the Pie Menus from All the Widgets" -DonHopkins]

https://www.youtube.com/watch?v=mOLS9I_tdKE

Part of flexibility is device independence: SUN provides a spectrum of display devices to which clients need consistent and transparent interfaces. This leads directly to portability, which we also need to achieve.

Users should be able to make various tradeoffs differently than in the standard system, because of either particular hardware or performance requirements. For example, if the system provides retained windows because we believe that the cost in terms of memory usage is worth the performance improvements, a user should be able to make this tradeoff differently, for example if he has less memory.

This extreme flexibility might appear to be at odds with having a clean, simple, well-abstracted programmer interface, but we do not believe that it is.

Remote access to windows: in the kind of distributed networked environment that SUN promotes, it is natural to want to be able to access windows on another machine as naturally as the NFS promises to support accessing remote files. We believe that this will fall out of any reasonably designed system.

Powerful graphical primitives: the primitives that the Macintosh provides should be considered as a lower bound. Curves and colour need to be well integrated. Attention should also be paid to what CGI [30], GKS [28], CORE [24] and PHIGS [6] need. A consequence of an emphasis on power and flexibility is the ability to emulate other window systems, eg it would be very valuable to be able to provide an emulation of the Macintosh toolbox.

Exploit the hardware: in particular, none of the systems mentioned above deal well with colour. In the future, colour is going to play an even larger part in display design. One can view black and white as a temporary technological stopgap, just as happened with television. Besides, SUN makes some pretty good colour displays, so the window system should exploit them. One implication of this is that the font file format must completely hide the details of the representation of characters, since we might eventually want to support antialiased text, and even illuminated monastic typefaces.

Perform well: the performance of the current window system should be considered as the minimum acceptable level. Performance in the common cases is especially critical. The new system should perform faster than the current system on such common operations as repainting and scrolling of text.

DESIGN SKETCH

The work on a language called PostScript by John Warnock and Charles Geschke at Adobe Systems provided a key inspiration for a path to a solution that meets these goals. PostScript is a Forth-like language, but has data types such as integers, reals, canvases, dictionaries and arrays.

Inter process communication is usually accomplished by sending messages from one process to another via some communication medium. They usually contain a stream of commands and parameters. One can view these streams of commands as a program in a very simple language. What happens if this simple language is extended to being Turing-equivalent? Now, programs do not communicate by sending messages back and forth, they communicate by sending programs which are elaborated by the receiver. This has interesting implications on data compression, performance and flexibility.

What Warnock and Geschke were trying to do was communicate with a printer. They transmit programs in the PostScript language to the printer which are elaborated by a processor in the printer, and this elaboration causes an image to appear on the page. The ability to define a function allows the extension and alteration of the capabilities of the printer.

This idea has very powerful implications within the context of window systems: it provides a graceful way to make the system much more flexible, and it provides some interesting solutions to performance and synchronization problems. SunDew contains a complete implementation of PostScript. The messages that client programs send to SunDew are really PostScript programs.

Two pieces of work were done at SUN which provide other key components of the solution to the imaging problems. One is Vaughan Pratt's Conix, a package for quickly manipulating curve bounded regions, and the other is Craig Taylor's Pixscene, a package for performing graphics operations in overlapped layers of bitmaps.

Out of these goals and pieces grew a design, which will be sketched here. The window system is considered in four parts. The imaging model, window management, user interaction, and client interaction. The imaging model refers to the capabilities of the graphic system - the manipulation of the contents of a window. Window management refers to the manipulation of windows as objects themselves. User interaction refers to the way a user at a workstation will interact with the window system: how keystrokes and mouse actions will be handled. Client interaction refers to the way in which clients (programs) will interact with the window system: how programs make requests to the window system.

What is usually thought of as the user interface of the window system is explicitly outside the design of the window system. User interface includes such things as how menu title bars are drawn and what the desktop background looks like and whether or not the user can stretch a window by clicking the left button in the upper right hand corner of the window outline. All these issues are addressed by implementing appropriate procedures in the PostScript.