Hyperledger Composer Historian

The Hyperledger Composer Historian is a specialised registry which records successful transactions, including the participants and identities that submitted them. The historian stores transactions as HistorianRecord assets, which are defined in the Hyperledger Composer system namespace.

The historian registry is a Hyperledger Composer system-level entity. To refer to the historian registry as a resource for access control the historian must be referenced as: org.hyperledger.composer.system.HistorianRecord.

Please note: All participants must have the permission to create HistorianRecord assets. If a transaction is submitted by a participant who does not have the permission to create HistorianRecord assets, the transaction will fail.

HistorianRecord assets

The historian registry stores successful transactions as HistorianRecord assets. Whenever a transaction successfully completes, a HistorianRecord asset is created and added to the historian registry. Record assets are defined in the system namespace, and have the following definition:

asset HistorianRecord identified by transactionId {
  o String      transactionId
  o String      transactionType
  --> Transaction transactionInvoked
  --> Participant participantInvoking  optional
  --> Identity    identityUsed         optional
  o Event[]       eventsEmitted        optional
  o DateTime      transactionTimestamp
}

String transactionId The transactionId of the transaction that caused the HistorianRecord asset to be created.
String transactionType The class of transaction that caused the HistorianRecord asset to be created.
Transaction transactionInvoked A relationship to the transaction which caused the HistorianRecord asset to be created.
Participant participantInvoking A relationship to the participant who submitted the transaction.
Identity identityUsed A relationship to the identity used to submit the transaction.
Event[] eventsEmitted An optional property containing any events which were emitted by the transaction.
DateTime transactionTimestamp The timestamp of the transaction which caused the HistorianRecord asset to be created.

All HistorianRecord assets have relationships to the transaction that created them, the invoking participant of that transaction, and the identity used when the transaction was submitted. Applications that wish to obtain these attributes must resolve this relationship.

System transactions

Several operations that the Hyperledger Composer runtime makes are classed as transactions. These 'system transactions' are defined in the Hyperledger Composer system model. The following will add HistorianRecord assets:

Adding, removing and updating assets
Adding, removing and updating participants
Issuing, binding, activating and revoking identities
Updating the business network definition

Securing historian data

As a registry, access to the historian data can be controlled with access control rules. However, as a system-level entity the resource name for the historian registry is always org.hyperledger.composer.system.HistorianRecord.

The following access control rule allows members to only see historian data if it references transactions they submitted.

rule historianAccess{
  description: "Only allow members to read historian records referencing transactions they submitted."
  participant(p): "org.example.member"
  operation: READ
  resource(r): "org.hyperledger.composer.system.HistorianRecord"
  condition: (r.participantInvoking.getIdentifier() == p.getIdentifier())
  action: ALLOW

}

Retrieving historian data

Data from the historian registry can be retrieved using either an API call, or queries.

Using the client and REST APIs with historian

HistorianRecord assets can be returned using the system/historian and system/historian/{id} calls using the REST API.

When using the REST API, a GET call of system/historian will return ALL historian data. This call should be used with care, the return is not limited and may result in large volumes of data being returned.

A GET call of system/historian/{id} using the REST API will return the HistorianRecord asset specified.

Querying the Historian

Historian can be queried in the same manner as other registries. For example, a typical query to return all HistorianRecord assets would be as follows:

    .then(() => {       
        return businessNetworkConnection.getHistorian();
    }).then((historian) => {
        return historian.getAll();
    }).then((historianRecords) => {        
        console.log(prettyoutput(historianRecords));
    })

As this is a 'getAll' call it will potentially return high volume of data. Therefore the query capability is vital in being able to select a subset of records. A typical example would be to select records based on a time. This uses the query capability to select records where the transaction timestamp is past a certain point. The returned records can be processed in the same way.

  let now = new Date();
  now.setMinutes(10);  // set the date to be time you want to query from

  let q1 = businessNetworkConnection.buildQuery('SELECT org.hyperledger.composer.system.HistorianRecord ' +
                                                'WHERE (transactionTimestamp > _$justnow)');   

  return businessNetworkConnection.query(q1,{justnow:now});

More advanced queries can be used; for example, the following query selects and returns the Add, Update, and Remove asset system transactions.

  // build the special query for historian records
  let q1 = businessNetworkConnection.buildQuery(
      `SELECT org.hyperledger.composer.system.HistorianRecord
          WHERE (transactionType == 'AddAsset' OR transactionType == 'UpdateAsset' OR transactionType == 'RemoveAsset')`
  );      

  return businessNetworkConnection.query(q1);