Persistence

The Persistence interface is responsible for storing the AAS model.

Each Persistence configuration supports at least the following configuration properties:

Common configuration properties of for all Persistence implementations.

Name	Allowed Value	Description	Default Value
initialModel (optional)	String	An Environment object containing the model to load initially. This can only be set when used via code, not via configuration file. This has precedence over initialModelFile when both are set.
initialModelFile (optional)	String	Path to a model file to load initially.

In-Memory

The In-Memory Persistence keeps the AAS model in the local memory. This means, that once FA³ST Service is stopped or crashes, all changes made during runtime are lost.

Important

If you use In-Memory Persistence from code by setting the initialModel property, the passed instance of Environment will be modified directly (as always the case in Java with pass-by-reference). If you do not want the original instance to be modified by FA³ST Serivce, call DeepCopyHelper.deepCopy(...) with the Environment to create a copy before passing it to FA³ST.

Configuration

In-Memory Persistence has no additional configuration properties.

Example configuration for In-Memory Persistence.

{
    "persistence":
    {
        "@class": "org.eclipse.digitaltwin.fa3st.service.persistence.memory.PersistenceInMemory",
        "initialModel": "{pathTo}/fa3st-service/misc/examples/model.json"
    },
    //...
}

File-based

The File-based Persistence stores the AAS model in a file according to the AAS specification. Therefore, changes are stored permanently even when FA³ST Service is stopped or crashes.

Important

Each modification of the model results in writing the whole model to the file which might become a performance issue for larger models.

Configuration

Configuration properties of File-based Persistence.

Name	Allowed Value	Description	Default Value
dataDir (optional)	String	Path where the model file created by the persistence should be saved.	.
dataformat (optional)	AASX JSON XML	Data format to use when storing. Ignored when keepInitial is set to true.	same as initialModelFile
keepInitial (optional)	Boolean	If true, initialModelFile will not be modified but instead a copy will be created in dataDir where the changes will be saved. If false, all changes will be written directly to the initialModelFile.	true

Example configuration for File-based Persistence.

{
    "persistence":
    {
        "@class": "org.eclipse.digitaltwin.fa3st.service.persistence.file.PersistenceFile",
        "initialModelFile": "{pathTo}/fa3st-service/misc/examples/model.json",
        "dataDir": ".",
        "keepInitial": true,
        "dataformat": "XML"
    },
    //...
}

Mongo

The Mongo Persistence stores the AAS model in a MongoDB according to the AAS specification. Therefore, changes are stored permanently even when FA³ST Service is stopped or crashes.

Important

Each modification of the model results in only writing the specific part to the MongoDB document which should improve performance

Configuration

Configuration properties of MongoDB-based Persistence.

Name	Allowed Value	Description	Default Value
connectionString	String	The connection string where the MongoDB is located.
database (optional)	String	The name of the database to be used inside the MongoDB.	fa3st
override (optional)	Boolean	If true, FA³ST persistence will always override the previous database, this might result in data loss.	false

Example configuration for MongoDB-based Persistence.

{
    "persistence":
    {
        "@class": "org.eclipse.digitaltwin.fa3st.service.persistence.mongo.PersistenceMongo",
        "connectionString": "mongodb://localhost:27017",
        "database": "fa3st-database",
        "override": true
    },
    //...
}