computer science

Low Bandwidth X

Low Bandwidth X is a computer science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Low Bandwidth X rather than just read about it. In short: In computing, LBX, or Low Bandwidth X, is a protocol to use the X Window System over network links with low bandwidth and high latency. It was introduced in X11R6.3 ("Broadway") in 1996, but never achieved wide use.

Key takeaways

Low Bandwidth X belongs to computer science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Low Bandwidth X to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Low Bandwidth X from memory before moving on to harder problems.

Reference excerpt

In computing, LBX, or Low Bandwidth X, is a protocol to use the X Window System over network links with low bandwidth and high latency. It was introduced in X11R6.3 ("Broadway") in 1996, but never achieved wide use. It was disabled by default as of X.Org Server 7.1, and was removed for version 7.2. X was originally implemented for use with the server and client on the same machine or the same local area network. By 1996, the Internet was becoming popular, and X's performance over narrow, slow links was problematic. LBX ran as a proxy server (lbxproxy). It cached commonly used information — connection setup, large window properties, font metrics, keymaps and so on — and compressed data transmission over the network link. LBX was never widely deployed as it did not offer significant speed improvements. The slow links it was introduced to help were typically insecure, and RFB protocol (VNC) over a secure shell connection — which includes compression — proved faster than LBX, and also provided session resumption. Finally, it was shown that greater speed improvements to X could be obtained for all networked environments with replacement of X's antiquated font system as part of the new composited graphics system, along with care and attention to application and widget toolkit design, particularly care to avoid network round trips and hence latency.

See also Virtual Network Computing (VNC) xmove - a tool allows you to move programs between X Window System displays xpra - a more recent tool which is similar to xmove NX technology, an X acceleration system

References lbxproxy(1) (man page) Design and Implementation of LBX: An Experiment Based Standard (.tar.gz archive file) (Keith Packard, Eighth Annual X Technical Conference, The X Resource no. 9, O'Reilly & Associates, 1994) Broadway/Xweb FAQ (broadwayinfo.com) The LBX mini-HOWTO v1.04 (Paul D. Smith, 11 December 1997) An LBX Postmortem (Keith Packard) X Window System Network Performance (Keith Packard and Jim Gettys, 2003) Design and Implementation of the X Rendering Extension (Keith Packard, 2001

Worked examples

Example 1 — a first encounter with Low Bandwidth X

Start with the simplest possible case. Write down what Low Bandwidth X claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In computer science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Low Bandwidth X before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Low Bandwidth X ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Low Bandwidth X

In research: Low Bandwidth X appears in computer science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Low Bandwidth X in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Low Bandwidth X is common in secondary-school and first-year university syllabi. It links to neighbouring topics History of software, Proxy servers, Remote desktop, so understanding it makes those chapters shorter.
In everyday life: Look for Low Bandwidth X outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Low Bandwidth X in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Low Bandwidth X means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Low Bandwidth X out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Low Bandwidth X in simple terms?

Why does Low Bandwidth X matter?

Because it connects several computer science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Low Bandwidth X?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Low Bandwidth X.