Name ==== PGXN Meta Spec - The PGXN distribution metadata specification Version ======= 1.0.0 Synopsis ======== { "name": "pgTAP", "abstract": "Unit testing for PostgreSQL", "description": "pgTAP is a suite of database functions that make it easy to write TAP-emitting unit tests in psql scripts or xUnit-style test functions.", "version": "0.2.5", "maintainer": [ "David E. Wheeler ", "pgTAP List " ], "license": { "PostgreSQL": "https://www.postgresql.org/about/licence" }, "prereqs": { "runtime": { "requires": { "plpgsql": 0, "PostgreSQL": "8.0.0" }, "recommends": { "PostgreSQL": "8.4.0" } } }, "provides": { "pgtap": { "file": "sql/pgtap.sql", "docfile": "doc/pgtap.mmd", "version": "0.2.4", "abstract": "Unit testing assertions for PostgreSQL" }, "schematap": { "file": "sql/schematap.sql", "docfile": "doc/schematap.mmd", "version": "0.2.4", "abstract": "Schema testing assertions for PostgreSQL" } }, "resources": { "homepage": "https://pgtap.org/", "bugtracker": { "web": "https://github.com/theory/pgtap/issues" }, "repository": { "url": "https://github.com/theory/pgtap.git", "web": "https://github.com/theory/pgtap", "type": "git" } }, "generated_by": "David E. Wheeler", "meta-spec": { "version": "1.0.0", "url": "https://pgxn.org/meta/spec.txt" }, "tags": [ "testing", "unit testing", "tap", "tddd", "test driven database development" ] } Description =========== This document describes version 1.0.0 of the PGXN distribution metadata specification, also known as the “PGXN Meta Spec.” It is formatted using the [MultiMarkdown](https://fletcherpenney.net/multimarkdown/) variant of [Markdown](https://daringfireball.net/projects/markdown/), and the canonical copy may always be found at [master.pgxn.org/meta/spec.txt](https://master.pgxn.org/meta/spec.txt). A generated HTML-formatted copy found at [pgxn.org/spec/](https://pgxn.org/spec/) may also be considered canonical. This document is stable. Any revisions to this specification for typo corrections and prose clarifications may be issued as “PGXN Meta Spec 1.0.*x*”. These revisions will never change semantics or add or remove specified behavior. Distribution metadata describe important properties of PGXN distributions. Distribution building tools should create a metadata file in accordance with this specification and include it with the distribution for use by automated tools that index, examine, package, or install PGXN distributions. Terminology =========== distribution : The primary object described by the metadata. In the context of this document it usually refers to a collection of extensions, source code, utilities, tests, and/or documents that are distributed together for other developers to use. Examples of distributions are [`semver`](https://pgxn.org/dist/semver/), [`pair`](https://pgxn.org/dist/pair/), and [`pgTAP`](https://pgxn.org/dist/pgTAP/). extension : A reusable library of code contained in a single file or within files referenced by the [`CREATE EXTENSION` statement](https://www.postgresql.org/docs/current/static/sql-createextension.html). Extensions usually contain one or more PostgreSQL objects — such as data types, functions, and operators — and are often referred to by the name of a primary object that can be mapped to the file name. For example, one might refer to `pgTAP` instead of `sql/pgtap.sql`. consumer : Code that reads a metadata file, deserializes it into a data structure in memory, or interprets a data structure of metadata elements. producer : Code that constructs a metadata data structure, serializes into a bytestream and/or writes it to disk. must, should, may, etc. : These terms are interpreted as described in [IETF RFC 2119](https://www.ietf.org/rfc/rfc2119.txt). Data Types ========== Fields in the [Structure](#Structure) section describe data elements, each of which has an associated data type as described herein. There are four primitive types: *Boolean*, *String*, *List*, and *Map*. Other types are subtypes of primitives and define compound data structures or define constraints on the values of a data element. Boolean ------- A *Boolean* is used to provide a true or false value. It **must** be represented as a defined (not `null`) value. String ------ A *String* is data element containing a non-zero length sequence of Unicode characters. List ---- A *List* is an ordered collection of zero or more data elements. Elements of a List may be of mixed types. Producers **must** represent List elements using a data structure which unambiguously indicates that multiple values are possible, such as a JavaScript array. Consumers expecting a List **must** consider a [String](#String) as equivalent to a List of length 1. Map --- A *Map* is an unordered collection of zero or more data elements (“values”), indexed by associated [String](#String) elements (“keys”). The Map’s value elements may be of mixed types. License String -------------- A *License String* is a subtype of [String](#String) with a restricted set of values. Valid values are described in detail in the description of the [license field](#license). Term ---- A *Term* is a subtype of [String](#String) that **must** be at least two characters long contain no slash (`/`), backslash (`\`), control, or space characters. Tag --- A *Tag* is a subtype of [String](#String) that **must** be fewer than 256 characters long contain no slash (`/`), backslash (`\`), control, or space characters. URI --- *URI* is a subtype of [String](#String) containing a Uniform Resource Identifier or Locator. Version ------- A *Version* is a subtype of [String](#String) containing a value that describes the version number of extensions or distributions. Restrictions on format are described in detail in the [Version Format](#Version.Format) section. Version Range ------------- The *Version Range* type is a subtype of [String](#String). It describes a range of Versions that may be present or installed to fulfill prerequisites. It is specified in detail in the [Version Ranges](#Version.Ranges) section. Structure ========= The metadata structure is a data element of type [Map](#Map). This section describes valid keys within the [Map](#Map). Any keys not described in this specification document (whether top-level or within compound data structures described herein) are considered *custom keys* and **must** begin with an “x” or “X” and be followed by an underscore; i.e. they must match the pattern: `/\Ax_/i`. If a custom key refers to a compound data structure, subkeys within it do not need an “x_” or “X_” prefix. Consumers of metadata may ignore any or all custom keys. All other keys not described herein are invalid and should be ignored by consumers. Producers must not generate or output invalid keys. For each key, an example is provided followed by a description. The description begins with the version of spec in which the key was added or in which the definition was modified, whether the key is *required* or *optional*, and the data type of the corresponding data element. These items are in parentheses, brackets, and braces, respectively. If a data type is a [Map](#Map) or [Map](#Map) subtype, valid subkeys will be described as well. All examples are represented as [JSON](https://json.org/). Required Fields --------------- ### abstract ### Example: "abstract": "Unit testing for PostgreSQL" (Spec 1) [required] {[String](#String)} This is a short description of the purpose of the distribution. ### maintainer ### Examples: "maintainer": "David E. Wheeler " "maintainer": [ "David E. Wheeler ", "Josh Berkus " ] (Spec 1) [required] {[List](#List) of one or more [Strings](#String)} This [List](#List) indicates the person(s) to contact concerning the distribution. The preferred form of the contact string is: contact-name This field provides a general contact list independent of other structured fields provided within the [resources](#resources) field, such as `bugtracker`. The addressee(s) can be contacted for any purpose including but not limited to: (security) problems with the distribution, questions about the distribution, or bugs in the distribution. A distribution’s original author is usually the contact listed within this field. Co-maintainers, successor maintainers, or mailing lists devoted to the distribution may also be listed in addition to or instead of the original author. ### license ### Examples: "license": { "PostgreSQL": "https://www.postgresql.org/about/licence" } "license": { "Perl 5": "https://dev.perl.org/licenses/", "BSD": "https://www.opensource.org/licenses/bsd-license.html" } "license": "perl_5" "license": [ "apache_2_0", "mozilla_1_0" ] (Spec 1) [required] {[Map](#Map) or [List](#List) of one or more [License Strings](#License.String)} One or more licenses that apply to some or all of the files in the distribution. If multiple licenses are listed, the distribution documentation should be consulted to clarify the interpretation of multiple licenses. The [Map](#Map) type describes the license or licenses. Each subkey may be any string naming a license. All values must be [URIs](#URI) that link to the appropriate license. The [List](#List) type may be used as a shortcut to identify one or more well-known licenses. The following list of [License Strings](#License.String) are valid in the [List](#List) representation: string | description --------------|------------------------------------------------------ agpl_3 | GNU Affero General Public License, Version 3 apache_1_1 | Apache Software License, Version 1.1 apache_2_0 | Apache License, Version 2.0 artistic_1 | Artistic License, (Version 1) artistic_2 | Artistic License, Version 2.0 bsd | BSD License (three-clause) freebsd | FreeBSD License (two-clause) gfdl_1_2 | GNU Free Documentation License, Version 1.2 gfdl_1_3 | GNU Free Documentation License, Version 1.3 gpl_1 | GNU General Public License, Version 1 gpl_2 | GNU General Public License, Version 2 gpl_3 | GNU General Public License, Version 3 lgpl_2_1 | GNU Lesser General Public License, Version 2.1 lgpl_3_0 | GNU Lesser General Public License, Version 3.0 mit | MIT (aka X11) License mozilla_1_0 | Mozilla Public License, Version 1.0 mozilla_1_1 | Mozilla Public License, Version 1.1 openssl | OpenSSL License perl_5 | The Perl 5 License (Artistic 1 & GPL 1 or later) postgresql | The PostgreSQL License qpl_1_0 | Q Public License, Version 1.0 ssleay | Original SSLeay License sun | Sun Internet Standards Source License (SISSL) zlib | zlib License The following [License Strings](#License.String) are also valid and indicate other licensing not described above: string | description --------------|------------------------------------------------------ open_source | Other Open Source Initiative (OSI) approved license restricted | Requires special permission from copyright holder unrestricted | Not an OSI approved license, but not restricted unknown | License not provided in metadata All other strings are invalid in the license [List](#List). ### provides ### Example: "provides": { "pgtap": { "file": "sql/pgtap.sql", "docfile": "doc/pgtap.mmd", "version": "0.2.4", "abstract": "Unit testing assertions for PostgreSQL" }, "schematap": { "file": "sql/schematap.sql", "docfile": "doc/schematap.mmd", "version": "0.2.4", "abstract": "Schema testing assertions for PostgreSQL" } } (Spec 1) [required] {[Map](#Map) of [Terms](#Term)} This describes all extensions provided by this distribution. This information is used by PGXN to build indexes identifying in which distributions various extensions can be found. The keys of `provides` are [Terms](#Term) that name the extensions found within the distribution. The values are [Maps](#Map) with the following subkeys: file : The value must contain a relative file path from the root of the distribution to the file containing the extension. The path **must be** specified with unix conventions. Required. version : This field contains a [Version](#Version) for the extension. All extensions must have versions. Required. abstract : A short [String](#String) value describing the extension. Optional. docfile : The value must contain a relative file path from the root of the distribution to the file containing documentation for the extension. The path **must be** specified with unix conventions. Optional. ### meta-spec ### Example: "meta-spec": { "version": "1.0.0", "url": "https://pgxn.org/meta/spec.txt" } (Spec 1) [required] {[Map](#Map)} This field indicates the [Version](#Version) of the PGXN Meta Spec that should be used to interpret the metadata. Consumers must check this key as soon as possible and abort further metadata processing if the meta-spec [Version](#Version) is not supported by the consumer. The following keys are valid, but only `version` is required. version : This subkey gives the integer [Version](#Version) of the PGXN Meta Spec against which the document was generated. url : This is a [URI](#URI) of the metadata specification document corresponding to the given version. This is strictly for human-consumption and should not impact the interpretation of the document. ### name ### Example: "name": "pgTAP" (Spec 1) [required] {[Term](#Term)} This field is the name of the distribution. This is usually the same as the name of the “main extension” in the distribution, but may be completely unrelated to the extensions within the distribution. This value will be used in the distribution file name on PGXN. ### version ### Example: "version": "1.3.6" (Spec 1) [required] {[Version](#Version)} This field gives the version of the distribution to which the metadata structure refers. Its value must be a [Version](#Version). Optional Fields -------------- ### description ### Example: "description": "pgTAP is a suite of database functions that make it easy to write TAP-emitting unit tests in psql scripts or xUnit-style test functions." (Spec 1) [optional] {[String](#String)} A longer, more complete description of the purpose or intended use of the distribution than the one provided by the `abstract` key. ### generated_by ### Example: "generated_by": "Module::Build::PGXN version 0.42" (Spec 1) [optional] {[String](#String)} This field indicates the tool that was used to create this metadata. There are no defined semantics for this field, but it is traditional to use a string in the form “Software package version 1.23” or the maintainer’s name, if the file was generated by hand. ### tags ### Example: "tags": [ "testing", "unit testing", "tap" ] (Spec 1) [optional] {[List](#List) of [Tags](#Tag)} A [List](#List) of keywords that describe this distribution. ### no_index ### Example: "no_index": { "file": [ "src/file.sql" ], "directory": [ "src/private" ], } (Spec 1) [optional] {[Map](#Map)} This [Map](#Map) describes any files or directories that are private to the packaging or implementation of the distribution and should be ignored by indexing or search tools. Valid subkeys are as follows: file : A [List](#List) of relative paths to files. Paths **must be** specified with unix conventions. directory : A [List](#List) of relative paths to directories. Paths **must be** specified with unix conventions. ### prereqs ### Example: "prereqs": { "runtime": { "requires": { "PostgreSQL": "8.0.0", "PostGIS": "1.5.0" }, "recommends": { "PostgreSQL": "8.4.0" }, "suggests": { "sha1": 0 } }, "build": { "requires": { "prefix": 0 } }, "test": { "recommends": { "pgTAP": 0 } } } (Spec 1) [optional] {[Map](#Map)} This is a [Map](#Map) that describes all the prerequisites of the distribution. The keys are phases of activity, such as `configure`, `build`, `test`, or `runtime`. Values are [Maps](#Map) in which the keys name the type of prerequisite relationship such as `requires`, `recommends`, `suggests`, or "conflicts", and the values provide sets of prerequisite relations. The sets of relations **must** be specified as a [Map](#Map) of extension names to [Version Ranges](#Version.Ranges). The full definition for this field is given in the [Prereq Spec](#Prereq.Spec) section. ### release_status ### Example: "release_status": "stable" (Spec 1) [optional] {[String](#String)} This field specifies the release status of this distribution. It **must** have one of the following values: stable : Indicates an ordinary, “final” release that should be indexed by PGXN. testing : Indicates a “beta” release that is substantially complete, but has an elevated risk of bugs and requires additional testing. The distribution should not be installed over a stable release without an explicit request or other confirmation from a user. This release status may also be used for “release candidate” versions of a distribution. unstable : Indicates an “alpha” release that is under active development, but has been released for early feedback or testing and may be missing features or may have serious bugs. The distribution should not be installed over a stable release without an explicit request or other confirmation from a user. Consumers **may** use this field to determine how to index the distribution for PGXN or other repositories. If this field is not present, consumers **may** assume that the distribution status is “stable.” ### resources ### Example: "resources": { "homepage": "https://pgxn.org/", "bugtracker": { "web": "https://github.com/theory/pgtap/issues", "mailto": "pgxn-bugs@example.com" }, "repository": { "url": "git://github.com/theory/pgtap.git", "web": "https://github.com/theory/pgtap/", "type": "git" }, "x_twitter": "https://twitter.com/pgtap/" } (Spec 1) [optional] {[Map](#Map)} This field describes resources related to this distribution. Valid subkeys include: homepage : A [URI](#URI) for the official home of this project on the web. bugtracker : This entry describes the bug tracking system for this distribution. It is a [Map](#Map) with the following valid keys:
web

a URI pointing to a web front-end for the bug tracker

mailto

an email address to which bug reports can be sent

repository : This entry describes the source control repository for this distribution. It is a [Map](#Map) with the following valid keys:
url

a URI pointing to the repository itself

web

a URI pointing to a web front-end for the repository

type

a lowercase string indicating the VCS used

: Because a URI like `https://myrepo.example.com/` is ambiguous as to type, producers should provide a `type` whenever a `url` key is given. The `type` field should be the name of the most common program used to work with the repository, e.g. git, svn, cvs, darcs, bzr or hg. Version Numbers =============== Version Format -------------- This section defines the [Version](#Version) type, used by several fields in the PGXN Meta Spec. Version numbers must be treated as strings, and adhere to the [Semantic Versioning Specification](https://semver.org/). Semantic versions take a dotted-integer format consisting of three positive integers separated by full stop characters (i.e. “dots”, “periods” or “decimal points”). A “special version” *may* be denoted by appending an arbitrary ASCII string immediately following the patch version. Please see [the specification](https://semver.org/) for all details on the format. Version Ranges -------------- Some fields (`prereqs`) indicate the particular version(s) of some other extension that may be required as a prerequisite. This section details the [Version Range](#Version.Range) type used to provide this information. The simplest format for a Version Range is just the version number itself, e.g. `2.4.0`. This means that **at least**version 2.4.0 must be present. To indicate that **any** version of a prerequisite is okay, even if the prerequisite doesn’t define a version at all, use the version `0`. Alternatively, a version range **may** use the operators `<` (less than), `<=` (less than or equal), `>` (greater than), `>=` (greater than or equal), `==` (equal), and `!=` (not equal). For example, the specification `< 2.0.0` means that any version of the prerequisite less than 2.0.0 is suitable. For more complicated situations, version specifications **may** be AND-ed together using commas. The specification `>= 1.2.0, != 1.5.0, < 2.0.0` indicates a version that must be **at least** 1.2.0, **less than** 2.0.0, and **not equal to** 1.5.0. Prerequisites ============= Prereq Spec ----------- The `prereqs` key defines the relationship between a distribution and other extensions. The prereq spec structure is a hierarchical data structure which divides prerequisites into *Phases* of activity in the installation process and *Relationships* that indicate how prerequisites should be resolved. For example, to specify that `pgtap` is required during the `test` phase, this entry would appear in the distribution metadata: "prereqs": { "test": { "requires": { "pgtap": 0 } } } Note that the `prereqs` key may not be used to specify prerequisites distributed outside PGXN or the PostgreSQL core and its contrib extensions. ### Phases ### Requirements for regular use must be listed in the `runtime` phase. Other requirements should be listed in the earliest stage in which they are required and consumers must accumulate and satisfy requirements across phases before executing the activity. For example, `build` requirements must also be available during the `test` phase. before action | requirements that must be met ----------------|--------------------------------- ./configure | configure make | configure, runtime, build make test | configure, runtime, build, test Consumers that install the distribution must ensure that *runtime* requirements are also installed and may install dependencies from other phases. after action | requirements that must be met ----------------|--------------------------------- make install | runtime
configure : The configure phase occurs before any dynamic configuration has been attempted. Extensions required by the configure phase **must** be available for use before the distribution building tool has been executed. build : The build phase is when the distribution’s source code is compiled (if necessary) and otherwise made ready for installation. test : The test phase is when the distribution’s automated test suite is run. Any extension needed only for testing and not for subsequent use should be listed here. runtime : The runtime phase refers not only to when the distribution’s contents are installed, but also to its continued use. Any extension that is a prerequisite for regular use of this distribution should be indicated here. develop : The develop phase’s prereqs are extensions needed to work on the distribution’s source code as its maintainer does. These tools might be needed to build a release tarball, to run maintainer-only tests, or to perform other tasks related to developing new versions of the distribution. ### Relationships ### requires : These dependencies **must** be installed for proper completion of the phase. recommends : Recommended dependencies are *strongly* encouraged and should be satisfied except in resource constrained environments. suggests : These dependencies are optional, but are suggested for enhanced operation of the described distribution. conflicts : These dependencies cannot be installed when the phase is in operation. This is a very rare situation, and the conflicts relationship should be used with great caution, or not at all. Merging and Resolving Prerequisites ----------------------------------- Whenever metadata consumers merge prerequisites, they should be merged in a way that preserves the intended semantics of the prerequisite structure. Generally, this means concatenating the version specifications using commas, as described in the [Version Ranges](#Version.Ranges) section. A subtle error that can occur when resolving prerequisites comes from the way that extensions in prerequisites are indexed to distribution files on PGXN. When a extension is deleted from a distribution, prerequisites calling for that extension could indicate that an older distribution should installed, potentially overwriting files from a newer distribution. For example, say the PGXN index contained these extension-distribution mappings: Extension | Version | Distribution ------------|---------|------------------ pgtap | 0.25.0 | pgTAP-0.25.0.zip schematap | 0.25.0 | pgTAP-0.25.0.zip functap | 0.18.1 | pgTAP-0.18.1.zip Note that functap was removed from the pgTAP distribution sometime after 0.18.1. Consider the case where pgTAP 0.25.0 is installed. If a distribution specified “functap” as a prerequisite, it could result in `pgTAP-0.18.1.tar.gz` being installed, overwriting any files from `pgTAP-0.25.0.zip`. Consumers of metadata **should** test whether prerequisites would result in installed module files being “downgraded” to an older version and **may** warn users or ignore the prerequisite that would cause such a result. Serialization ============= Distribution metadata should be serialized as JSON-encoded data and packaged with distributions as the file `META.json`. Notes For Implementors ====================== Comparing Version Numbers ------------------------- Following the [Semantic Versioning Spec](https://semver.org/), version numbers **must** be strictly compared by splitting the [Version](#Version) string on full stop characters (i.e. “dots”, “periods” or “decimal points”) and comparing each of the three parts as integers. If an ASCII string has been appended to the third number, it will be extracted and compared in ASCII-betical order, and in any event will be considered to be less than an un-encumbered third integer of the same value. Some examples: 0.12.1 < 0.12.2 1.42.0 > 1.41.99 2.0.0 > 1.999.999 2.0.0alpha3 < 2.0.0beta1 2.0.0beta < 2.0.0 See Also ======== * [CPAN Meta Spec](https://metacpan.org/pod/CPAN::Meta::Spec) * [PGXN](https://www.pgxn.org/) * [JSON](https://json.org/) * [Semantic Versioning](https://semver.org/) Contributors ============ The PGXN Meta Spec borrows heavily from the [CPAN Meta Spec](https://metacpan.org/pod/CPAN::Meta::Spec), which was originally written by Ken Williams in 2003 and has since been updated by Randy Sims, David Golden, and Ricardo Signes. Ported to PGXN by David E. Wheeler.