What do you do if you are a small company launching a technically obscure product against formidable competition?
You take a page out of the Microsoft Corp. playbook and declare your product a standard the day you announce it.
Which is exactly what Adobe Systems Inc. has done in announcing Display PostScript (DPS), an extension to its page-description language for writing graphics to a screen instead of to a printer.
DPS was first announced in September 1987 by Adobe and NeXT Inc., who jointly developed the graphics-imaging software. Digital Equipment Corp. signed on to incorporate DPS in its DEC Windows product in January of this year. But things didn’t really start heating up until the NeXT computer was announced in October.
DPS, as demonstrated in the NextStep interface, coupled with the announcement of IBM’s licensing of DPS for its AIX Unix operating system, suddenly made DPS a hot technology and Adobe a company to watch.
DPS is an implementation of the PostScript language for interactive graphics displays. NextStep will not be shipped until sometime next year, and it is unclear how IBM and Digital will implement DPS on their Unix systems.
However, the real opponent for DPS and Adobe is Microsoft and the OS/2 Presentation Manager (PM). Since IBM announced its licensing of DPS for AIX, various IBM officials have made oblique statements about ”accommodating” DPS in PM as well as in Unix.
IBM does not appear to have formalized its plans to license DPS for incorporation into PM, but Microsoft officials reacted strongly to the implication that PM was somehow lacking a mystery ingredient that DPS could provide.
It would not be difficult to build a DPS library for OS/2, Microsoft officials claim, but the functionality would be redundant; Microsoft is adamant that it is doing no such thing.
To the contrary, Microsoft officials are so convinced of the superiority of the Presentation Manager Graphics Programming Interface (GPI) that they are toying with taking the offensive and building a GPI-based page-description language for printers, according to Adrian King, director of systems software for the Redmond, Wash., company.
There isn’t a one-to-one correlation between PM and DPS. Presentation Manager is tied to OS/2 and offers a graphical user interface, a window manager and a graphics engine (the GPI) for writing graphics applications.
DPS, on the other hand, is only a programming language and a graphics-imaging system. It is being licensed by Adobe to hardware OEM customers for incorporation into whatever operating systems and window managers those manufacturers choose to support.
Adobe claims that DPS offers developers portability for their applications between DPS-based systems from different vendors. This thesis presumes, however, that the graphics portion of an application could easily be dissembled from window system- and operating system-specific code, which necessarily would have to be rewritten for a port. At best, only a small, but critical, portion of an applications code — the DPS — would not have to be rewritten for a port.
Whereas PM applications are typically written in C, and PM services are accessed via a procedure-call interface, DPS services are accessed by writing segments of code in the PostScript language. PostScript code is then passed to an interpreter for execution.
Adobe also offers an extendable client library of PostScript language instructions that can be ”wrapped” in C code and invoked from a C program and translated into C-language source code.
For as much functionality as an OEM chooses to include in its Client Library, the programmer is insulated from having to write in the PostScript language, which Microsoft claims is as difficult as assembly language.
Despite the programming differences, ”the power of the graphics engines in PM and DPS are basically the same,” said Nathan Mirvald, director of advanced development at Microsoft.
For most basic business applications, users would not be able to distinguish between the two graphics programming models, but for programs that push the limits of the system, there are differences.
DPS has better font-scaling capabilities than PM, and can rotate bit-mapped images. DPS can also provide a high level of what-you-see-is-what-you-get with PostScript printers, because the imaging model is the same.
PM, on the other hand, provides the application with more ”knowledge” of the output device, so that programs can fine-tune color output and manipulate images at the pixel level on-screen.
The technical fine points notwithstanding, PM appears destined to be a standard insofar as OS/2 wins over the DOS user base. DPS, on the other hand, must first makes its way into popular operating environments before developers will have financial motivation for supporting it.