# Quarkus style and content guidelines

Guidelines are provided to help you to contribute clear and consistent content that is also sourced in the required diataxis structure and composition of Quarkus documentation.

## AsciiDoc syntax

Quarkus docs use AsciiDoc syntax. The following links provide background on AsciiDoc syntax and general conventions.

- AsciiDoc Mark-up Quick Reference for Documentation

- AsciiDoctor User Manual

- AsciiDoc Syntax Quick Reference

## Language and grammar

Write clear, concise, and consistent technical information in US English. Write for a global audience with localization, translation, inclusivity, and diversity in mind. Try to use the following grammar styles:

- Present tense

- Active voice

- Second person (you)

- A conversational tone

- Gender neutral language

## Sentence length

Shorter sentences are much easier to read and translate. Try to use less than 32 words per sentence.

## Website publication

Content from this repository is published to the Quarkus.io website.

- Documentation built from the main branch is published nightly (main-SNAPSHOT).

- Documentation for other branches is published at release time.

## Titles and headings

Regardless of content type, ensure that the main title and any headings in your document are:

- Goal-oriented and use the language and keywords of the audience

- Descriptive and avoid filler words

- Between 3-12 words and 50-80 characters per line to optimize findability in search engines

- In sentence case capitalization style

Your titles and headings must also follow the specific guidance for the Quarkus content types, as outlined in the following table:

Table 1. Title guidance for different Quarkus content types
Content type | Should …​ | Good example | Bad example
--- | --- | --- | ---
Concept | Start with a noun that names the concept or topic Never start with an active verb, for example, an action word like configure, install, or start Finish the implied sentence: "Understanding …​" | Security and authentication mechanisms in Quarkus | Discovering Reactive SQL Clients In Quarkus
How-To Guide | Start with an active verb in the imperative verb form, for example, "Create a …​" or "Secure a …​" Be action-oriented or task-oriented, rather than feature-oriented Finish the implied sentence: "How to …​" | Secure your Quarkus application with WebAuthn authentication | Applying WebAuthn Authentication In Quarkus
Reference | Use a noun phrase to concisely summarize the content of the document Not include the word 'reference' Finish the implied sentence: "About …​" | Hibernate Reactive API configuration properties | Reference guide for Configuring Hibernate Reactive API Configuration Properties
Tutorial | Start with an active verb in the imperative verb form, for example, "Create a …​" or "Secure a …​" State what task the user will complete, with emphasis on the key topic or demonstrated activity Be action-oriented or task-oriented, rather than feature-oriented Be led by the needs of the user in learning mode. Finish the implied sentence: "In this tutorial, you will …​" | Create a Quarkus application in JVM mode by using the quick start example | Creating an App

## File conventions

### Source locations

- AsciiDoc files are in the `src/main/asciidoc` directory within the `docs` module of the Quarkus GitHub repository.

- Configuration documentation is generated from JavaDoc comments in Java source files.

- Java, YAML, and other source files can also be referenced by AsciiDoc files.

### Output locations

Configuration references

  Configuration reference documentation is generated from Javadoc comments discovered in MicroProfile Config source files. These generated files are in `target/asciidoc/generated/config/` (from the project root).

AsciiDoc output to HTML

  AsciiDoc processing creates HTML files in `docs/target/generated-docs/`.

### Templates

Create new documentation files with the appropriate template for the content type:

Concepts

  Use `docs/src/main/asciidoc/_templates/template-concept.adoc`

How-To Guides

  Use `docs/src/main/asciidoc/_templates/template-howto.adoc`

Reference

  Use `docs/src/main/asciidoc/_templates/template-reference.adoc`

Tutorials

  Use `docs/src/main/asciidoc/_templates/template-tutorial.adoc`

### File names

Quarkus documentation uses a flat hierarchy.

The bulk of the file name should be some representation of its title. Use all lowercase letters, separate words with hyphens, and avoid symbols and special characters.

Prefix

  Use a common prefix to group-related documents. Documents related to writing and contributing to Quarkus docs share the `doc-` prefix, for example.

Suffix

  Use a suffix that reflects the document type (optional):

  - `-concept.adoc` for concept documents

  - `-howto.adoc` for how-to guides

  - `-reference.adoc` for references

  - `-tutorial.adoc` for tutorials

## Document structure

Use the Quarkus templates to ensure that your content is consistent with the preferred Quarkus documentation structure and style.

### Document header

Each document should define a header for document-scoped attributes. Minimally, each document should define and id and a title, and include common attributes (`_attributes.adoc`).

    [id="doc-reference"] (1)
    = Quarkus style and content guidelines (2)
    \include::_attributes.adoc[] (3)
    :diataxis-type: {type} (4)
    :categories: contributing (5)

1 | Use the filename as the ID for the document.
2 | Define the document title following guidance in Titles and headings.
3 | Include common document attributes.
4 | Specify the diataxis type: `concept`, `howto`, `reference`, or `tutorial`.
5 | Specify the relevant Categories (comma separated).

#### Other common document header attributes

`:extension-status: preview`

  Use this attribute to flag special types of content. Valid values: `experimental`, `preview`, `stable` (not usually used), and `deprecated`.

`:summary: <text>`

  Use the summary to provide a concise (26 words or less) description of the document. The value of this attribute is used in tiles or other descriptions on the website and is not required in newer diataxis-styled docs, as outlined in Abstracts (preamble). If not present, the first sentence of the abstract is automatically used to generate the tile summary.

| Take care with whitespace when working with document-scoped attributes. The document header ends with the first blank line.

### Abstracts (preamble)

The first paragraph in the main body is treated as the abstract, also referred to as the preamble. Add a short description that helps your audience quickly find and understand the purpose and intent of the page. The first sentence of the abstract provides a summary and gets automatically added to the tile on the Quarkus guides homepage.

Try to write the abstract by using the following guidelines:

- User oriented: Contains terms and keywords that are familiar to users.

- Concise: Avoids self-referential expressions and filler words, for example:

  - "This document.."

  - "This tutorial…​"

  - "The following…​"

- Brief: Is no more than three sentences long.

| Ensure that the first sentence explains the value and some benefits of the content in 26 words or less.

If the first sentence is too long or cannot be simplified to fit on the website tile, you can define a `:summary:` attribute in the document header attributes to serve that purpose. For more information, see Other common document header attributes.

### Semantic line breaks

Text in paragraphs, lists, and tables should be broken into pieces that are easier to review[1]. Start a new line at the end of each sentence, and split sentences themselves at natural breaks between clauses.

### Sections

Section titles should be written in sentence case rather than title case.

Start your document with a title, which in AsciiDoc is defined as a `= Level 0` heading. Where appropriate, divide your content into subsections, which in AsciiDoc are defined as `== Level 1` to `====== Level 5`. Do not skip any levels.

| Deep nesting (`====== Level 4`, `====== Level 5`) should be avoided whenever possible. If you end up with deeply nested sections, think about the following: Is this information in the right place? For example, if this is a reference, should some of this content be moved to a concept doc or how-to guide instead? Can the content be reorganized to make it simpler to consume? See Quarkus documentation content types for more information about content types and organization.

## Links

In general, prefer url macros to bare or automatic links. Provide human-readable text for the link, especially if it is included in the middle of other text.

| A URL Macro link with attributes The URL macro also supports additional attributes that may be relevant, like opening a link in a different window.
    https://docs.asciidoctor.org/asciidoc/latest/syntax-quick-reference/[AsciiDoc Syntax Quick Reference,window=_blank,opts=nofollow]
The above source produces this AsciiDoc Syntax Quick Reference.

## Cross-references

Quarkus documentation is built from source in a few different environments.

### Cross-reference source attributes

We use attributes in our cross-references to ensure our docs can be built across these environments.

Table 2. Cross-reference source attributes
Attribute | Description
--- | ---
`{code-examples}` | Relative path to directory containing collected example source files
`{doc-examples}` | Relative path to source examples for documentation guides
`{generated-dir}` | Relative path to generated configuration `*.adoc` files
`{imagesdir}` | Relative path to directory containing images
`{includes}` | Relative path to directory containing partial/reusable content

When cross-referencing content, always use the inter-document `xref:` syntax and supply a human-readable label to your link.

Cross-reference example

    xref:doc-concept.adoc[Quarkus Documentation concepts] (1)

1 | The cross-reference starts with `xref:`, and provides a readable description: `[Quarkus Documentation concepts]`.

### Anchors for in-file and cross-file navigation

- To create an anchored ID, use lower-case characters, separate each word with `-`, and enclose the ID in `[[]]` as in the example below.

      [[title-heading]]
      == Title heading

- To call an anchor created in the same file, insert the anchored ID in a `<<>>` xref macro.

      <<title-heading>>

- To create an anchor with a custom URL caption example, specify the anchored ID and desired name separated by `,` without white space.

      <<title-heading,Title heading description that fits the context of your content>>

  | Do not use the `<<>>` format with the verbatim heading or section description, such as `<<Title heading>>`.

- To call an anchored ID from a different file, use the full file name and anchored ID separated by `#`, and specify the human-readable URL caption.

      xref:<other-file-name>.adoc#title-heading[Title heading]

- To refer to another file, use the xref macro with the full file name syntax and always specify the human-readable URL caption.

      xref:<name-of-the-file>.adoc[Human-readable label]

  For more details about anchored IDs, see the Cross-reference in-file and cross-file content by using anchors section of the "Contribute to Quarkus documentation" guide.

### Cross-reference phrasing

For consistency and context clarity, use the following guidelines for constructing your cross-reference phrases:

- Provide a direct hyperlink to the section, using the `xref` guidance in the previous section.

- Specify the full title of the section and use sentence case.

- Add the definite article “the” before the section title and specify “section” directly after the title.

- Add the definite article “the” and “Quarkus” before the title of the guide, unless the word “Quarkus" is already in the title.

- Insert the title of the guide between double quotations and specify “guide” directly after the title.

- If the context is needed, lead with the phrase:

  - "For more information about …​"

Table 3. Correct and incorrect cross-reference phrases
Correct | Incorrect
--- | ---
For more information, see the Configuring the ValidatorFactory section of the Quarkus "Validation with Hibernate Validator" guide. | For more information, see the 'Configuring the ValidatorFactory' section of the VALIDATION WITH HIBERNATE VALIDATOR guide.
For more information, see the Generating a cache key with CacheKeyGenerator section of the Quarkus "Application Data Caching" guide. | For more information, see Generating a cache key with CacheKeyGenerator.
For more information, see the PKCE-related section of the Quarkus "OpenID Connect (OIDC) Authorization Code Flow Mechanism" guide. | For more information, see OpenID Connect (OIDC) Authorization Code Flow Mechanism.

### Reference source code

There are many ways to include source code and examples in the documentation.

The simplest is to write it directly in the file, like this:

    [source,java]
    ----
    System.out.println("Hello, World!");
    ----

In documents like tutorials, you may want to reference source code that is built and tested regularly. The Quarkus documentation build copies source files enumerated in `*-examples/yaml` files into a flattened structure in the `target/asciidoc/examples` directory (from the project root).

    examples:
    - source: path/to/source/file/SomeClassFile.java (1)
      target: prefix-simplified-unique-filename.java (2)

1 | define the path of source to be copied
2 | define the simplified target file name to use when copying the file into the `target/asciidoc/examples` directory.

Content copied in this way is referenced by the `{code-examples}` source attribute. The literal string `{{source}}` in the source file, if present, will be replaced with the path of the source file in the copy.

Micrometer example

- The source file to be copied is:

  `integration-tests/micrometer-prometheus/src/main/java/documentation/example/telemetry/micrometer/tutorial/ExampleResource.java`

- The target file name we want to use in docs is:

  `telemetry-micrometer-tutorial-example-resource.java`.

- The source and target file names are declared in `docs/src/main/asciidoc/telemetry-examples.yaml`:

      examples:
      - source: integration-tests/micrometer-prometheus/src/main/java/io/quarkus/doc/micrometer/ExampleResource.java
        target: telemetry-micrometer-tutorial-example-resource.java

- Snippets from this source file are then referenced with the following path:

  `{code-examples}/telemetry-micrometer-tutorial-example-resource.java`.

- The source file contains the following comment:

    // Source: {{source}}

- The copied file contains this comment instead:

    // Source: integration-tests/micrometer-prometheus/src/main/java/io/quarkus/doc/micrometer/ExampleResource.java

## Document attributes and variables

### Categories

Quarkus documentation is grouped into the following categories.

Table 4. Categories
Category | Description
--- | ---
`alt-languages` | Support for other languages, namely Kotlin and Scala
`architecture` | Quarkus runtime and ecosystem architecture
`business-automation` | Business automation integrations
`cloud` | Integrations and support for cloud services
`command-line` | Command Line Applications
`compatibility` | Compatibility with other languages and frameworks
`contributing` | Guidance and references to help you contribute to Quarkus.
`core` | Information about how the Quarkus works
`data` | Topics related to using data sources with Quarkus
`getting-started` | Getting started materials
`integration` | Support for integration extensions (Camel)
`messaging` | Integrations with messaging systems like Kafka, AMQP, or RabbitMQ.
`miscellaneous` | Miscellaneous
`native` | Everything related to native executables
`observability` | Extensions and integrations for runtime and application observability
`security` | Security
`serialization` | Serialization
`tooling` | Tooling
`web` | Web
`writing-extensions` | Writing Extensions

Tag your content to improve findability by adding at least one category to the categories attribute line in the document header. To add multiple categories, use comma-separated values. For example:

    :categories: contributing, data

### Quarkus documentation variables

The following variables externalize key information that can change over time. References to such information should use the variable inside of curly brackets, `{}`.

The complete list of externalized variables for use is given in the following table:

Table 5. Variables
Property Name | Value | Description
--- | --- | ---
`{quarkus-version}` | `3.20.2.1` | The current version of the project.
`{quarkus-home-url}` | `https://quarkus.io` | The location of the project home page.
`{quarkus-org-url}` | `https://github.com/quarkusio` | The location of the project GitHub organization.
`{quarkus-base-url}` | `https://github.com/quarkusio/quarkus` | Quarkus GitHub URL common base prefix.
`{quarkus-clone-url}` | `https://github.com/quarkusio/quarkus.git` | Quarkus URL for `git clone` referenced by the documentation.
`{quarkus-archive-url}` | `https://github.com/quarkusio/quarkus/archive/main.zip` | Quarkus URL to main source archive.
`{quarkus-blob-url}` | `https://github.com/quarkusio/quarkus/blob/main` | Quarkus URL to main blob source tree; used for referencing source files.
`{quarkus-tree-url}` | `https://github.com/quarkusio/quarkus/tree/main` | Quarkus URL to main source tree root; used for referencing directories.
`{quarkus-issues-url}` | `https://github.com/quarkusio/quarkus/issues` | Quarkus URL to the issues page.
`{quarkus-images-url}` | `https://github.com/quarkusio/quarkus-images` | Quarkus URL to set of container images delivered for Quarkus.
`{quarkus-chat-url}` | `https://quarkusio.zulipchat.com` | URL of our chat.
`{quarkus-mailing-list-subscription-email}` | `quarkus-dev+subscribe@googlegroups.com` | Email used to subscribe to our mailing list.
`{quarkus-mailing-list-index}` | `https://groups.google.com/d/forum/quarkus-dev` | Mailing list index page.
`{quickstarts-base-url}` | `https://github.com/quarkusio/quarkus-quickstarts` | Quickstarts URL common base prefix.
`{quickstarts-clone-url}` | `https://github.com/quarkusio/quarkus-quickstarts.git` | Quickstarts URL for `git clone` referenced by the documentation.
`{quickstarts-archive-url}` | `https://github.com/quarkusio/quarkus-quickstarts/archive/main.zip` | Quickstarts URL to main source archive.
`{quickstarts-blob-url}` | `https://github.com/quarkusio/quarkus-quickstarts/blob/main` | Quickstarts URL to main blob source tree; used for referencing source files.
`{quickstarts-tree-url}` | `https://github.com/quarkusio/quarkus-quickstarts/tree/main` | Quickstarts URL to main source tree root; used for referencing directories.
`{graalvm-version}` | `for JDK 21` | Recommended GraalVM version to use.
`{graalvm-flavor}` | `jdk-21` | The builder image tag of GraalVM to use e.g. `jdk-17`.

1. Rhodes, B. Semantic Linefeeds. https://rhodesmill.org/brandon/2012/one-sentence-per-line/