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is arichly-typed,self-describing, hierarchical data serializationformat offeringinterchangeable binary and text representations. Thetext format(a superset ofJSON) is easy to read and author, supporting rapidprototyping. Thebinary representation isefficient to store, transmit, andskip-scan parse. The rich type system provides unambiguous semantics forlong-term preservation of data which can survive multiple generationsof software evolution.

Ion was built to address rapid development, decoupling, and efficiencychallenges faced every day while engineering large-scale, service-orientedarchitectures. It has been addressing these challenges within Amazon for nearlya decade, and we believe others will benefit as well.

Available Languages:C –C# –Go –Java –JavaScript –Python –Rust
Community Supported:D –PHP –Ion Object Mapper for .NET
Related Projects:Ion Hash –Ion Schema
Tools:Ion CLI –Hive SerDe

Getting Started

All JSON values are valid Ion values, and while any value can be encoded in JSON (e.g., a timestamp value can be converted to a string), such approaches require extra effort, obscure the actual type of the data, and tend to be error-prone.

In contrast, Ion’s rich type system enables unambiguous semantics for data (e.g., a timestamp value can be encoded using the timestamp type). The following illustrates some of the features of the Ion type system:

• timestamp: arbitrary precision date / timestamps

  2003-12-01T2010-03-22T18:00:00Z2019-05-01T18:12:53.472-0800

• int: arbitrary size integers

  0-112345678901234567890...

• decimal: arbitrary precision, base-10 encoded real numbers

  0.-1.23.141592653589793238...6.62607015d-34

• float: 32-/64-bit IEEE-754 floating-point values

  0e0-1.2e06.02e23-inf

• symbol: provides efficient encoding for frequently occurring strings

  inchesdollars'high-priority'    // symbols with special characters ('-' in this example)                   // are enclosed in single-quotes

• blob: binary data

  {{ aGVsbG8= }}

• annotation: metadata associated with a value

  dollars::100.0height::inches::72lotto_numbers::[7, 9, 19, 40, 42, 44]

TheSpecification provides an overview of the full set of Ion types.

Binary Encoding

Ion provides two encodings: human-readable text (as shown above), and a space- and read-efficient binary encoding. When binary-encoded, every Ion value is prefixed with the value’s type and length. The following illustrates a few of the efficiences provided by Ion’s binary encoding:

• The following timestamp encoded as a JSON string requires 26 bytes: “2017-07-26T16:30:04.076Z”. This timestamp requires just 11 bytes when encoded in Ion binary:

  6a 80 0f e1 87 9a 90 9e 84 c3 4c

  That first byte6a indicates the value is a timestamp (type6) represented by the subsequent 10 bytes (that’s what thea represents). If this particular timestamp value is not of interest, a reader can jump over the value by skipping 10 bytes. This ability to skip over a value enables faster navigation over Ion data.

• Binary encoding of a symbol replaces the text of a symbol with an integer that can be resolved to the original text via a symbol table. This can result in substantial space savings for symbols that occur frequently!

• While blob data is base-64 encoded in text (which produces 4 bytes for every 3 bytes of the original data), a blob encoded as Ion binary is simply encoded as is—no base-64 expansion required!

Similar space efficiencies are found in other aspects of Ion’s binary encoding.

Give Ion a Try!

More Information

To learn more, check out theDocs page, or seeLibs for the officially supported libraries as well as community supported tools. For information on how to contribute, how to contact the Ion Team, and answers to the frequently asked questions, seeHelp.