ZYpp (or libzypp; ''"Zen / YaST Packages Patches Patterns Products"'') is a

package manager A package manager or package-management system is a collection of software tools that automates the process of installing, upgrading, configuring, and removing computer programs for a computer in a consistent manner. A package manager deals wi ...

engine that powers Linux applications like YaST, Zypper and the implementation of

PackageKit PackageKit is a free and open-source suite of software applications designed to provide a consistent and high-level front end for a number of different package management systems. PackageKit was created by Richard Hughes in 2007, and first intro ...

for

openSUSE openSUSE () is a free and open source RPM-based Linux distribution developed by the openSUSE project. The initial release of the community project was a beta version of SUSE Linux 10.0. Additionally the project creates a variety of tools, ...

and

SUSE Linux Enterprise SUSE Linux Enterprise (often abbreviated to SLE) is a Linux-based operating system developed by SUSE. It is available in two editions, suffixed with Server (SLES) for servers and mainframes, and Desktop (SLED) for workstations and desktop compu ...

. Unlike some more basic package managers, it provides a satisfiability solver to compute package dependencies. It is a

free and open-source software Free and open-source software (FOSS) is a term used to refer to groups of software consisting of both free software and open-source software where anyone is freely licensed to use, copy, study, and change the software in any way, and the sour ...

project sponsored by

Novell Novell, Inc. was an American software and services company headquartered in Provo, Utah, that existed from 1980 until 2014. Its most significant product was the multi- platform network operating system known as Novell NetWare. Under the le ...

and licensed under the terms of the

GNU General Public License The GNU General Public License (GNU GPL or simply GPL) is a series of widely used free software licenses that guarantee end users the four freedoms to run, study, share, and modify the software. The license was the first copyleft for general ...

v2 or later. ZYpp is implemented mostly in the programming language C++. Zypper is the native

command-line interface A command-line interpreter or command-line processor uses a command-line interface (CLI) to receive command (computing), commands from a user in the form of lines of text. This provides a means of setting parameters for the environment, invokin ...

of the ZYpp

to install, remove, update and query software packages of local or remote (networked) media. Its graphical equivalent is the YaST package manager module. It has been used in

since version 10.2 beta1. In openSUSE 11.1, Zypper reached version 1.0. On June 2, 2009, Ark Linux announced that it has completed its review of dependency solvers and has chosen ZYpp and its tools to replace the aging APT-RPM, as the first distribution to do so. Zypper is also part of the mobile Linux distributions

MeeGo MeeGo is a discontinued Linux distribution hosted by the Linux Foundation, using source code from the operating systems Moblin (produced by Intel) and Maemo (produced by Nokia). Primarily targeted at mobile devices and information appliances ...

Sailfish OS Sailfish OS is a Linux-based operating system based on free software, and open source projects such as Mer as well as including a closed source UI. The project is being developed by the Finnish company Jolla. The OS first shipped with the ...

, and

Tizen Tizen () is a Linux-based mobile operating system backed by the Linux Foundation, mainly developed and used primarily by Samsung Electronics. The project was originally conceived as an HTML5-based platform for mobile devices to succeed MeeGo. Sa ...

History

Purpose

Following its consecutive acquisitions of

Ximian Ximian, Inc. (previously called Helix Code and originally named International Gnome Support) was an American company that developed, sold and supported application software for Linux and Unix based on the GNOME platform. It was founded by Miguel ...

and SuSE GmbH in 2003,

decided to merge both package management systems, YaST package manager and

Red Carpet A red carpet is traditionally used to mark the route taken by heads of state on ceremonial and formal occasions, and has in recent decades been extended to use by VIPs and celebrities at formal events. History The earliest known reference t ...

, in a best of breed approach, as the two solutions so far were used at Novell. Looking at the extant open source tools and their maturity available back in 2005, none fulfilled the requirements, and were able to work smoothly with the extant Linux management infrastructure software developed by Ximian and SUSE, so it was decided to get the best ideas from extant pieces and to work on a new implementation. Libzypp, the resulting library, was planned to be the software management engine of the SUSE distributions and the Linux Management component of the

Novell ZENworks ZENworks, a suite of software products developed and maintained by Micro Focus International for computer systems management, aims to manage the entire life cycle of servers, of desktop PCs (Windows, Linux or Mac), of laptops, and of handh ...

Management suite.

Early days

The Libzypp's solver was a port from the Red Carpet solver, which was written to update packages in installed systems. Using it for the full installing process brought it to its limits, and adding extensions such as support for weak dependencies and patches made it fragile and unpredictable. Although this first version of ZYpp's solver worked satisfactorily, on the company enterprise products with the coupled ZMD daemon, it led to an openSUSE 10.1 release which came out in May 2006 with a system package not working as expected. In December 2006, the openSUSE 10.2 release corrected some defects of the prior release, using the revisited ZYpp v2. ZMD was subsequently removed from the 10.3 release and reserved for only the company Enterprise products. While ZYpp v3 provided openSUSE with a relatively good package manager, equivalent to other existing package managers, it suffered from some flaws in its implementation which greatly limited its speed performance.

SAT solver integration

An area where libzypp needed improvement was the speed of the dependency solver. libsolv is being written and released under the revised BSD license. Projects like Optimal Package Install/Uninstall Manager (OPIUM) and MANCOOSI were trying to fix dependency solving issues with a

SAT solver The SAT ( ) is a standardized test widely used for college admissions in the United States. Since its debut in 1926, its name and scoring have changed several times; originally called the Scholastic Aptitude Test, it was later called the Schol ...

. Traditional solvers like

Advanced Packaging Tool Advanced package tool, or APT, is a free-software user interface that works with core libraries to handle the installation and removal of software on Debian, and Debian-based Linux distributions. APT simplifies the process of managing software ...

(APT) sometimes show unacceptable deficiencies. It was decided to integrate SAT algorithms into the ZYpp stack; the solver algorithms used were based on the popular minisat solver. The SAT solver implementation as it appears in openSUSE 11.0 is based on two major, but independent, blocks: * Using a

data dictionary A data dictionary, or metadata repository, as defined in the ''IBM Dictionary of Computing'', is a "centralized repository of information about data such as meaning, relationships to other data, origin, usage, and format". ''Oracle'' defines it a ...

approach to store and retrieve package and dependency information. A new solv format was created, which stores a repository as a string dictionary, a relation dictionary and then all package dependencies. Reading and merging multiple solv repositories takes only milliseconds. * Using

satisfiability In mathematical logic, a formula is ''satisfiable'' if it is true under some assignment of values to its variables. For example, the formula x+3=y is satisfiable because it is true when x=3 and y=6, while the formula x+1=x is not satisfiable over ...

for computing package dependencies. The

Boolean satisfiability problem In logic and computer science, the Boolean satisfiability problem (sometimes called propositional satisfiability problem and abbreviated SATISFIABILITY, SAT or B-SAT) is the problem of determining if there exists an interpretation that satisfie ...

is a well-researched problem with many exemplar solvers available. It is very fast, as package solving complexity is very low compared to other areas where SAT solvers are used. Also, it does not need complex algorithms and can provide understandable suggestions by calculating proof of why a problem is unsolvable. After several months of work, the benchmark results of this fourth ZYpp version integrated with the SAT solver are more than encouraging, moving YaST and Zypper ahead of other RPM-based package managers in speed and size.

References

External links