Ion (serialization format)
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| Filename extension |
.ion |
|---|---|
| Developed by | Amazon |
| Type of format | Data interchange |
| Website | amzn |
Ion is a data serialization language developed by Amazon. It may be represented by either a human-readable text form or a compact binary form. The text form is a superset of JSON; thus, any valid JSON document is also a valid Ion document.
Data types
As a superset of JSON, Ion includes the following data types
- <syntaxhighlight lang="text" class="" style="" inline="1">null</syntaxhighlight>: An empty value
- <syntaxhighlight lang="text" class="" style="" inline="1">bool</syntaxhighlight>: Boolean values
- <syntaxhighlight lang="text" class="" style="" inline="1">string</syntaxhighlight>: Unicode text literals
- <syntaxhighlight lang="text" class="" style="" inline="1">list</syntaxhighlight>: Ordered heterogeneous collection of Ion values
- <syntaxhighlight lang="text" class="" style="" inline="1">struct</syntaxhighlight>: Unordered collection of key/value pairs
The nebulous JSON 'number' type is strictly defined in Ion to be one of
- <syntaxhighlight lang="text" class="" style="" inline="1">int</syntaxhighlight>: Signed integers of arbitrary size
- <syntaxhighlight lang="text" class="" style="" inline="1">float</syntaxhighlight>: 64-bit IEEE binary-encoded floating point numbers
- <syntaxhighlight lang="text" class="" style="" inline="1">decimal</syntaxhighlight>: Decimal-encoded real numbers of arbitrary precision
Ion adds these types:
- <syntaxhighlight lang="text" class="" style="" inline="1">timestamp</syntaxhighlight>: Date/time/time zone moments of arbitrary precision
- <syntaxhighlight lang="text" class="" style="" inline="1">symbol</syntaxhighlight>: Unicode symbolic atoms (aka identifiers)
- <syntaxhighlight lang="text" class="" style="" inline="1">blob</syntaxhighlight>: Binary data of user-defined encoding
- <syntaxhighlight lang="text" class="" style="" inline="1">clob</syntaxhighlight>: Text data of user-defined encoding
- <syntaxhighlight lang="text" class="" style="" inline="1">sexp</syntaxhighlight>: Ordered collections of values with application-defined semantics
Each Ion type supports a null variant, indicating a lack of value while maintaining a strict type (e.g., <syntaxhighlight lang="text" class="" style="" inline="1">null.int</syntaxhighlight>, <syntaxhighlight lang="text" class="" style="" inline="1">null.struct</syntaxhighlight>).
The Ion format permits annotations to any value in the form of symbols. Such annotations may be used as metadata for otherwise opaque data (such as a blob).
Implementations
Examples
Sample document
<syntaxhighlight lang="js"> // comments are allowed in Ion files using the double forward slash {
key: "value", // key here is a symbol, it can also be a string as in JSON nums: 1_000_000, // equivalent to 1000000, use of underscores with numbers is more readable 'A float value': 31415e-4, // key is a value that contains spaces "An int value": .int, annotated: age::35, // age here is the annotation to number 35 lists : 'hw grades'::[80, 85, 90], // any symbol can be used as an annotation many_annot: I::have::many::annotations::true, // annotations are not nested, but rather, a list of annotations sexp: (this (is a [valid] "Ion") last::value 42) // Ion S-expressions, _value: Template:OiBTIKUgTyAASb8=, _value: Template:"a b"
} </syntaxhighlight>
Uses
- Amazon's Quantum Ledger Database (QLDB) stores data in Ion documents.[1]
- PartiQL, an open source SQL-based query language also by Amazon, is built upon Ion. PartiQL supported queries are used by QLDB, S3Select.[2]
Tooling and extensions
- Ion Path Extractor API aims to combine the convenience of a DOM API with the speed of a streaming API.
- IDE support
- Jackson data format module for Ion
- Apache Hive SerDe for Ion
- Ion Schema
- Ion Hash defines an algorithm for constructing a hash for any Ion value.