OCEL

Object-Centric Event Log (OCEL) is a standard interchange format for object-centric event data with multiple case notions [1]. This library aims to implement this standard in .NET with a high degree of type safety.

Supported formats

The OCEL standard is defined for both JSON and XML. Both include a validation schema that is used by the library to validate input.

An additional useful format is to store OCEL data in document databases such as MongoDB [2]. A very good alternative for .NET is LiteDB, which is an embedded NoSQL database that is similar to MongoDB. It allows writing to files directly and does not require a database server to use. Support for MongoDB will be evaluated in the future.

Format	Status
JSON	Implemented
XML	Implemented
LiteDB	Implemented
MongoDB	TBD

Libraries

The library is written in F# and can be used directly by all .NET languages. For idiomatic usage in C#, a wrapper library is provided that mainly converts between appropriate types for the parsed logs.

Both libraries are available on NuGet:

Library	NuGet Link
F#	https://www.nuget.org/packages/OCEL
C#	https://www.nuget.org/packages/OCEL.CSharp

Examples

Validating an OCEL file (F# and C#)

let json = File.ReadAllText("minimal.jsonocel")
let valid = OCEL.OcelJson.validate json
let valid, errors = OCEL.OcelJson.validateWithErrorMessages json

var json = File.ReadAllText("minimal.jsonocel");
var valid = OCEL.CSharp.OcelJson.Validate(json);
var (valid, errors) = OCEL.CSharp.OcelXml.ValidateWithErrorMessages(xml);

Parsing a JSON-OCEL and XML-OCEL string (F# and C#)

let json = File.ReadAllText("minimal.jsonocel")
let xml = File.ReadAllText("minimal.xmlocel")
let fromJson = OCEL.OcelJson.deserialize json
let fromXml = OCEL.OcelXml.deserialize xml

var json = File.ReadAllText("minimal.jsonocel");
var xml = File.ReadAllText("minimal.xmlocel");
var fromJson = OCEL.CSharp.OcelJson.Deserialize(json);
var fromXml = OCEL.CSharp.OcelXml.Deserialize(xml);

Writing and reading from a LiteDB database (F# and C#)

let log = File.ReadAllText("minimal.jsonocel") |> OCEL.OcelJson.deserialize
let db = new LiteDatabase(":memory:")
OCEL.OcelLiteDB.serialize db log
let serializedLog = OCEL.OcelLiteDB.deserialize db

var log = OCEL.CSharp.OcelJson.Deserialize(File.ReadAllText("minimal.jsonocel"));
var db = new LiteDatabase(":memory:");
OCEL.CSharp.OcelLiteDB.Serialize(db, log);
var serializedLog = OCEL.CSharp.OcelLiteDB.Deserialize(db);

Converting between formats (F# and C#)

let json = File.ReadAllText("minimal.jsonocel")
let parsed = OCEL.OcelJson.deserialize json
let xml = OCEL.OcelXml.serialize parsed OCEL.Types.Formatting.Indented

var json = File.ReadAllText("minimal.jsonocel");
var parsed = OCEL.CSharp.OcelJson.Deserialize(json);
var xml = OCEL.CSharp.OcelXml.Serialize(parsed, OCEL.Types.Formatting.Indented);

References

[1] Farhang, A., Park, G. G., Berti, A., & Aalst, W. Van Der. (2020). OCEL Standard. http://ocel-standard.org/

[2] Berti, A., Ghahfarokhi, A. F., Park, G., & van der Aalst, W. M. P. (2021). A Scalable Database for the Storage of Object-Centric Event Logs. CEUR Workshop Proceedings, 3098, 19–20. https://arxiv.org/abs/2202.05639.