Event Introduction - JS/TS

Read and write the event store.

Logic Type	Available
Generic logic	✅
Aggregator logic	❌

A LOC event is a timestamped log or metadata representing a data flow, which can be read and write in LOC's event store (implemented with Elasticsearch).

The source and target digital identity (DID) are customised nodes defined by users. Multiple events with shared source/target nodes form a data lineage:

Import and Usage

JavaScript

import {
    EventAgent,
} from "@fstnetwork/loc-logic-sdk";

export async function run(ctx) {
    await EventAgent.emit([
        {
            labelName: "event",
            sourceDID: "source",
            targetDID: "target",
            meta: "",
            type: "default",
        },
    ]);
}

export async function handleError(ctx, error) {
    // ... same
}

TypeScript

import {
    Event,
    EventAgent,
    GenericContext,
    RailwayError,
} from "@fstnetwork/loc-logic-sdk";

export async function run(ctx: GenericContext) {
    await EventAgent.emit([
        {
            labelName: "event",
            sourceDID: "source",
            targetDID: "target",
            meta: "",
            type: "default",
        },
    ] as Event.Event[]);
}

export async function handleError(ctx: GenericContext, error: RailwayError) {
    // ... same
}

Events Fields For Query

An event in the event store has the following field names that can be added in query, exclude, filter and sort conditions:

Field Name	Description
label_id	label ID
label_name	Label name (labelName in emit())
source_digital_identity	Source DID (sourceDID in emit())
target_digital_identity	Target DID (targetDID in emit())
type	Type (type in emit())
timestamp	Event emitted time (unix timestamp)
sequence	Event sequence number (the emit order in an array, starting from 0)
execution_id	Execution ID
task_id	Task ID
data_process_permanent_identity	Data process permanent ID
data_process_name	Data process name
data_process_revision	Data process revision number
logic_name	Logic name
logic_permanent_identity	Logic permanent ID
logic_revision	Logic revision number

info

The sequence number represents the order of an event emitted in the array. If you emit 10 events at once, they will have sequence number from 1 to 10.

Class Reference

Type

• EventAgent

Method: Emit Events

Refer to: Emit Events

Method: Search Events

Refer to: Search Events

Method: Search Event Sequences

Refer to: Search Event Sequences

Examples

See each method pages for their examples.