============================================================================================================== The Alph Fluid Media Model: an immediately applicable version of the Xanalogical referential fluid media model ============================================================================================================== Abstract ======== We introduce the Alph Fluid Media Model, a simple, easily implementable version of the Xanalogical referential fluid media model. We present three techniques to make the model easily applicable to modern systems. Random-id content-carrying spans are useful for text: they allow most of the advantages of Xanalogical fluid media with only an increase in space in non-Xanalogical uses, i.e., no fetching the content of the span from afar. The permanent addresses in the spans refer to *scrollblocks*, clearly delimited, permanent blocks of fluid media data. A span can only contain fluid media units from one scrollblock. PageImage scrollblocks are used for interoperability with the modern real world, where receiving PDFs and Postscript files, i.e., images of pages, is a reality. Introduction ============ .. Starting point: [nelson99xanalogicalneeded]_, where no references to tumblers &c are made. Udanax ... Referential fluid media ======================= The abstraction of the fundamental idea of Xanalogical systems described in [nelson99xanalogicalneeded]_ is, formally, Making an implementation of referential fluid media practical ============================================================= In this section, we present the three most important developments As discussed by Nelson [nelson99xanalogicalneeded]_, the most fundamental and secret idea of the Xanalogical model was to endow each unit of "fluid media" (i.e. character of text, pixel of image, sample of sound, pixel in a frame in a video) with a permanent, universal identifier. Scrollblocks ------------ We have presented the basic idea of scrollblocks in [lukka02guids]_, Random-id content-carrying spans -------------------------------- Random-id content-carrying (RICC) spans are a novel twist on the basic referential fluid media model. A RICC span consists of - a **random** UUID (Unique Universal IDentifier) - offsets (in each dimension) - **the content** of the span Storing the actual content in the span is what makes RICC spans novel: there is no real reference in them, just the identifier. The spans with the same UUID form a virtual scrollblock... Pros: - Easiest to program - Only difference to strings in non-xanalogical use: take up somewhat more space! - no need for servers, scrollblocks, ... - Gets most of the benefits of the full xanalogical model - transclusions - Xanalogical links Cons: - Can only access the parts of the "scrollblock" that are stored in spans - not, e.g., the full keystroke record envisioned by Nelson (private communication) PageImage Spans --------------- The Alph Fluid Media Model formally =================================== The Alph Fluid Media Model (AFMM) is a simple model based on the lowest-level referential fluid media concepts of the Xanalogical model. Instead of continuous permascrolls as the Udanax implementation uses, the Alph model is based on *scrollblocks* which are fixed blocks of permanent media. A *span* in Alph is a reference to a single, contiguous (rectangular) block of fluid media units inside a single scrollblock. Storm URIs ---------- - Like Data URIs, but with content hashes instead of data Text ---- We have developed three different types of text spans Storm text spans """""""""""""""" Storm text spans [lukka02guids]_ are the earliest of the text spans developed for Alph. A storm text span is simply a Storm URI along with an offset and a length. XXX Character sets? Images ------ PageImages (PS/PDF/DjVu/...) ---------------------------- The support for *PageImages* is one of the aspects of Alph geared towards reasonable operability in a modern context. Implementation in Java + OpenGL =============================== Applications ============ Conclusion ========== ... One of the major missing pieces in the Alph Fluid Media Model is support for web pages. Due to the variability of ... Notes ===== We call our model the Alph Fluid Media Model to avoid trademark issues. The name Alph has its origins in the same poem as Xanadu(tm), as the "sacred river". The full model in a modern context ================================== Aspects that have been implemented in other systems --------------------------------------------------- - Micropayments - Refs... - no success yet, consumer interest low, free access or macroscopic payments (e.g. ACM: $XXX for article) the norm. - Versioning - did this appear somewhere before xu plans? - arch/tla = *very* like the xanadu versioning system Aspects that appear incompatible with modern systems ---------------------------------------------------- - Single central authority - Monolithic system storing all documents - Tumblers - We *have* dns, URIs - somewhat similar but very different: - Tumbler = LOGICAL hierarchical, not server address - Has central authority; going out of vogue - Referencing all of an author's work as a single span -- ... - GUIDs - UUID - OIDs! http://www.ariadne.ac.uk/issue8/unique-identifiers/ - DOIs - Xanadu "stations" - Nelson's other predictions including carryable/wearable computers came first, as well as cellular and wireless networking The full Xanalogical model ========================== XM Potentially useful aspects not currently in use ----------------------------------------------- - The referential fluid media model - "permascrolls" - Transclusions - Xanalogical links