Consume event

An input event that forms a goal.

Consume operation

An operation that a service can use to receive input from other services (via SPARKL).

Consume/reply operation

An operation that comprises a consume and a reply event. The consume forms a goal event, while the reply of a consume/reply creates a new (consequent) field set.

Expressions extension

The Expressions extension supports the use of Erlang expressions in SPARKL.

Also known as: svc_expr

Field set

A set of fields. A field set usually grows in terms of fields contained as it moves through the Sequencing Graph.

Flag field

A field that does not contain data. It is used only for sequencing purposes. For example YES or NO flag fields.

Island (of vertices)

Islands are bunches of vertices disjoint from other vertices existing on the same mix. Each island makes a different transaction possible on the same Sequencing Graph.


Labels are added to vertices. A label identifies the operations that generated the vertex by listing the fields associated with the operations.


A mix is a SPARKL configuration used for handling interactions between services. A mix comprises services, operations supported by these services, and fields sent to and from the operations.

priv directory

Each SPARKL extension has a priv directory where user assets are kept. The location of the extensions is decided at installation time. By default, the extensions' are at: /usr/local/lib/sse/lib.

Request event

An input event that forms a goal.

Request/reply operation

An operation that a service can use to generate additional data and then send it to SPARKL.

Response event

An input event that forms a goal.

Sequencer extension

The Sequencer extension is responsible for planning and processing the transactions. Services provisioned using this extension can implement notify and solicit/ response operations.

Also known as: svc_sequencer

Sequencing Graph

The Sequencing Graph is derived from all the operations in a mix. It is built once per mix and is used for all transactions on that mix.


Services are service end-points connected by SPARKL. They communicate with each other with the help of operations.

Subroutine extension

The Subroutine extension supports subroutine transactions called by a caller operation.

Also known as: svc_subr


The system configuration file. It is located within each nodes' folder, along with a directory containing system logs, a backup of your SPARKL resources, and a directory that contains your machine key and TLS/SSL certificate.


A process in SPARKL started by the Sequencer upon receiving an initial field set, and stopped by the Sequencer upon having nothing more to do with the field sets present in the transaction.