computer science

Open Hub

Open Hub 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 Open Hub rather than just read about it. In short: Open Hub or Black Duck Open Hub (formerly Ohloh) is a web site providing a web services suite and online community platform that aims to index the open-source software development community. It was founded by former Microsoft managers Jason Allen and Scott Collison in 2004 and joined by the developer Robin Luckey.

Key takeaways

Open Hub 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 Open Hub to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Open Hub from memory before moving on to harder problems.

Reference excerpt

Open Hub or Black Duck Open Hub (formerly Ohloh) is a web site providing a web services suite and online community platform that aims to index the open-source software development community. It was founded by former Microsoft managers Jason Allen and Scott Collison in 2004 and joined by the developer Robin Luckey. As of 15 January 2016, the site lists 669,601 open-source projects, 681,345 source control repositories, 3,848,524 contributors and 31,688,426,179 lines of code. In 2017, Black Duck Software, the company running the site, was acquired by Synopsys for $565 million, but it was spun out as a separate company again in October 2024.

History Ohloh was founded by former Microsoft managers Jason Allen and Scott Collison in 2004, joined by developer Robin Luckey. On 28 May 2009, Ohloh was acquired by Geeknet, owners of the popular open-source development platform SourceForge. However, Geeknet sold Ohloh to the open-source analysis company Black Duck Software on 5 October 2010. Black Duck integrated Ohloh's functionality with their existing products to advance the site into a major resource for FOSS development. On 18 July 2014, Ohloh became Black Duck Open Hub. In late August 2014, the Black Duck Open Hub's Organizations feature moved out of Beta and into Version 1.0.

Functionality and features By retrieving data from revision control repositories, such as CVS, SVN, Git, Bazaar, and Mercurial, Black Duck Open Hub provides statistics about the longevity of projects, their licenses, including license conflict information, as well as software metrics, such as source lines of code and commit statistics. The codebase history informs about the amount of activity for each project. Software stacks — list of software applications used by Black Duck Open Hub's members — and tags are used to calculate the similarity between projects. Global statistics per language measure the popularity of specific programming languages since the early 1990s. Those global statistics across all projects in Black Duck Open Hub have also been used to identify those with the most extensive continuous revision control histories. Contributor statistics are also available, measuring open-source developers' experience as observable in code committed to revision control repositories. Social network features (kudos) have been introduced to allow users to rank open-source contributors. A KudoRank for each user and open-source contributor on a scale of 1 to 10 is automatically extracted from all kudos in the system. The idea of measuring open-source developers' skills and productivity on the basis of commit statistics or mutual rating has received mixed reactions in technology blogs. Contributor profiles may also contain a contributor supplied email address, and avatars loaded from Gravatar using that email address. On 22 August 2007, a public beta of a web-service API was announced, exposing Black Duck Open Hub's data and reports to promote the development of third-party applications. On 18 January 2013, the team announced a new metric, the Project Activity Indicator (PAI). The PAI combines the number of contributors and the number of commits in an algorithm that weighs more recent activity more heavily than past activity. Activity is normalized so that all projects can be considered and weighed equally one against another; that activity assessment is scaled relatively to the number of project contributors and commits. On 14 January 2014, the team announced a new score, the Project Hotness Score. The PAI shows long-term activity and growth on FOSS projects, but its requirement that there be at least a year of data means that new projects can't be ranked. The Project Hotness Score looks at activity over the past few weeks and evaluates daily activity to identify those projects. By design, the Project Hotness Score is highly volatile. On 6 April 2016, the team announced Hub 3.0, which streamlined continuous integration and DevOps processes through policy management and rapid scanning capabilities.

Code search In 2012, Black Duck Open Hub launched Open Hub Code Search, a free code search engine based on the predecessor Koders. It could search over 21 billion lines of open-source code and filter by language, project or syntax, but was discontinued in 2016.

Illustrations

Logo of Ohloh in 2012, the former name of Open Hub.

Worked examples

Example 1 — a first encounter with Open Hub

Start with the simplest possible case. Write down what Open Hub 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 Open Hub 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 Open Hub 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 Open Hub

In research: Open Hub 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 Open Hub 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: Open Hub is common in secondary-school and first-year university syllabi. It links to neighbouring topics American review websites, Code search engines, Free software websites, so understanding it makes those chapters shorter.
In everyday life: Look for Open Hub 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 Open Hub in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Open Hub 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 Open Hub out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Open Hub in simple terms?

Why does Open Hub 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 Open Hub?

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 Open Hub.