R¶

R Language¶

A language and free environment for statistical computing and graphics, widely used by statisticians and data scientists.

RACI¶

Responsible, Accountable, Consulted, Informed. A responsibility matrix that sets out, for each task or deliverable, who does the work, who is accountable for it, who is consulted and who is kept informed.

RACI

RACI.

RAD¶

Rapid Application Development. An approach that develops software quickly through prototypes, workshops, early user testing and component reuse, with less formal documentation.

RAD Environment¶

A development tool that combines a language and an IDE with a toolbox of ready-made user interface components, for building applications quickly.

Radius¶

RADIUS: Remote Authentication Dial-In User Service. The protocol (RFC 2865) that network access servers use to authenticate users, authorise their access and record their usage against a central server. It is widely used for broadband, Wi-Fi and VPN access.

Radius

Radius.

RAN¶

Radio Access Network. The part of a mobile network between devices and the core: the base stations and their controllers. GERAN, UTRAN and E-UTRAN are the 2G, 3G and 4G versions.

RAN

RAN.

See also: GERAN, UTRAN, E-UTRAN, Backhaul.

RANAP¶

Radio Access Network Application Part. The UMTS signalling protocol on the Iu interface between the radio access network (the RNC) and the core (MSC or SGSN).

RANCID¶

Really Awesome New Cisco confIg Differ. An open-source tool that logs in to network devices, collects their configurations, stores them in version control and reports changes.

Rapid Application Development¶

See RAD.

RARP¶

Reverse Address Resolution Protocol. An obsolete protocol (RFC 903) with which a device that knows only its MAC address asks a server for its IP address. BOOTP and DHCP replaced it.

RAS¶

Registration, Admission and Status. The part of H.323 (in H.225) with which endpoints register with a gatekeeper and ask permission to make calls. RAS also stands for remote access server.

RDBMS¶

Relational Database Management System. A database system based on Edgar Codd’s relational model, which stores data in tables with rows and columns and is queried with SQL.

RDBMS

RDBMS.

RDP¶

Remote Desktop Protocol. Microsoft’s protocol for using another computer’s desktop over a network, on TCP and UDP port 3389.

Reading Inspection¶

An inspection that follows every step of the full process except the inspection meeting.

Refactoring¶

Improving the internal structure of code without changing what it does, in small steps backed by tests.

Regression testing¶

Re-running tests after a change to check that what worked before still works.

Regular expression¶

A pattern that describes a set of strings, used to search, match, validate and replace text. It is also called a regex.

Relative Estimation¶

Estimating work by comparing items with each other, or grouping items of similar difficulty, rather than estimating each in absolute units.

Release¶

Delivering a deployable version of a system to a customer, such as a test group or end users. The word also means the version delivered.

Release Management¶

Identifying, packaging and delivering the parts of a product to its customers, internal or external.

Release Test¶

A test that checks software is ready for release.

Requirement¶

A statement of something a system must do, or a quality it must have.

Requirements¶

The work of finding out, recording and managing what a software system should do.

Requirements Lead¶

The person responsible for defining, maintaining and tracing a product’s requirements, and for the user documentation that follows from them.

REST¶

Representational State Transfer. An architecture style for web services in which resources are identified by URLs and handled through a uniform set of stateless operations, usually the HTTP methods. GET reads, POST creates, PUT replaces and DELETE removes.

REST

REST.

Review¶

A defined process in which people other than an artefact’s author examine it to find issues. Reviews range from informal desk checks to formal inspections.

See also: Inspection, Desk Check, Walkthrough.

Reviewer¶

A person who takes part in a review.

Revision¶

One recorded version of an artefact, usually as numbered by a version control system.

Revision Control¶

See Version Control.

Rework¶

Unplanned work needed to bring an artefact into line with the project’s needs, such as fixing defects.

RFC¶

Request for Comments. The IETF’s numbered document series, which includes the internet’s standards and many informational and experimental documents.

RIP¶

Routing Information Protocol. One of the oldest distance-vector routing protocols. It uses hop count as its metric, with a limit of 15 hops, so it suits only small networks.

Risk¶

A possible future event that would harm a project’s features, budget, schedule or quality if it happened.

Risk Analysis¶

Assessing each risk for its likelihood and impact.

Risk Identification¶

Finding and recording a project’s current risks.

Risk List¶

A list of a project’s current and past risks, with their analysis and mitigation plans.

Risk Management¶

Identifying, analysing and controlling a project’s risks, either explicitly or as part of how the project is run.

Risk Mitigation¶

Planning and taking action to reduce a risk’s likelihood or impact.

Risk Reward Matrix¶

A two-by-two grid for comparing options, with risk on one axis and reward on the other. High-reward, low-risk options are the best candidates; high-risk, low-reward ones are to be avoided. The size of each marker can show the resources each option needs.

Risk Reward Matrix

Risk Reward Matrix.

Risk Reward Matrix

Risk Reward Matrix.

Risk Reward Matrix.

RNC¶

Radio Network Controller. The UMTS node that controls a group of Node Bs. It manages radio resources and handovers, and ciphers user data. It connects to the circuit-switched core through the Iu-CS interface and to the packet core through Iu-PS.

RNC

RNC.

RNSAP¶

Radio Network Subsystem Application Part. The UMTS signalling protocol between RNCs, on the Iur interface, used for soft handover and moving a connection from one RNC to another.

Role-feature-reason¶

The usual template for writing user stories: “As a role, I want feature, so that reason.”

Rolling Wave Planning¶

Planning the near future in detail and later work only roughly, then adding detail as each period comes closer.

Root of Trust¶

RoT. The hardware, firmware and keys that a device trusts without checking, because everything else is checked against them. It anchors secure boot, device identity and key storage, and is usually built into the chip or a secure element.

See also: RoT, Secure Element, TrustZone.

RoT¶

See Root of Trust.

Round Robin¶

A scheduling method that gives each task or queue a turn in a fixed circular order, with equal time slices and no priorities. It is simple and no task is starved.

Round Robin

Round Robin.

Router¶

A device that forwards packets between networks, choosing the next hop for each from its routing table, which it builds from configuration and routing protocols.

See also: Switch, Control Plane, BGP, OSPF.

RPC¶

Remote Procedure Call. Calling a procedure that runs in another process or on another machine as if it were a local call, with the messaging hidden by the framework.

RRC¶

Radio Resource Control. The 3GPP control protocol between a device and the radio network in UMTS, LTE and 5G. It sets up and releases connections and radio bearers, broadcasts system information and manages mobility. A state machine, with idle and connected states, governs the device.

RRC

RRC.

RRC.

RSTP¶

Rapid Spanning Tree Protocol. IEEE 802.1w, a faster version of the spanning tree protocol that recovers from a topology change in seconds rather than tens of seconds. It is now part of 802.1D.

RSVP¶

Resource Reservation Protocol. A protocol (RFC 2205) with which receivers reserve network resources for a flow along its path. Its extension, RSVP-TE, sets up traffic-engineered MPLS paths.

RTCP¶

RTP Control Protocol. The companion to RTP, defined in RFC 3550. It reports statistics on an RTP session, such as packet loss, jitter and round-trip time, and helps synchronise streams.

RTOS¶

Real-Time Operating System. An operating system that guarantees tasks respond within defined time limits, usually by priority-based preemptive scheduling. FreeRTOS, Zephyr and VxWorks are examples.

RTP¶

Real-time Transport Protocol. The protocol (RFC 3550) that carries audio and video over IP, usually on UDP, with sequence numbers and timestamps so receivers can play media out smoothly. SIP or another protocol sets up the session.

RTSP¶

Real Time Streaming Protocol. A protocol for controlling streaming media servers with commands such as play, pause and record. The media itself usually travels over RTP.

Ruby¶

A dynamic, object-oriented scripting language created by Yukihiro Matsumoto in the mid-1990s, designed to make programmers productive and happy.

Ruby on Rails¶

A web application framework written in Ruby, built on the model-view-controller pattern and known for “convention over configuration”.

Rule of Simplicity¶

Kent Beck’s rules, in priority order, for judging whether code is simple enough: it passes the tests, reveals its intent, has no duplication and has the fewest elements.

See also: Simple Design, KISS Principle.

RUP¶

Rational Unified Process. An iterative software development process framework from Rational Software (later IBM), with four phases: inception, elaboration, construction and transition.