SSE (Server-Sent Events) Configuration

Table of Contents

Introduction
Default Values
The Log Service Ecosystem
Subscribing
Keep SSE Connections Alive
Event Bus Configuration
Configuration
- Environment Variables
- YAML Example

Introduction

The Infinite Scale sse service is responsible for sending sse (server-sent events) to a user. See What is Server-Sent Events…? for a simple introduction and examples of server-sent events.

Default Values

The sse service listens on port 9135 by default.

The Log Service Ecosystem

Log services like the activitylog, clientlog, sse and userlog are responsible for composing notifications for a certain audience.

Log services and their tasks
activitylog ¹	This service stores events per resource. These can be retrieved to show item activities.
clientlog	This service composes machine-readable messages, so clients can act without the need to query the server.
eventhistory	This service stores events and allows other services to retrieve them via an event ID.
sse	This service is only responsible for sending these messages. It does not care about their form or language.
userlog ²	This service translates and adjusts messages to be human-readable.

Log services and their tasks

activitylog ¹

This service stores events per resource. These can be retrieved to show item activities.

clientlog

This service composes machine-readable messages, so clients can act without the need to query the server.

eventhistory

This service stores events and allows other services to retrieve them via an event ID.

sse

This service is only responsible for sending these messages. It does not care about their form or language.

userlog ²

This service translates and adjusts messages to be human-readable.

Services may depend on each other:

The activitylog service requires the eventhistory service.
The userlog service is configured by default to use both the eventhistory and sse service. It can be configured to use both, the one, or the other.

Subscribing

Clients can subscribe to the /sse endpoint to be informed by the server when an event happens. The sse endpoint will respect language changes of the user without needing to reconnect. Note that sse has a limitation of six open connections per browser which can be reached if one has opened various tabs of the Web UI pointing to the same Infinite Scale instance.

Keep SSE Connections Alive

Some intermediate proxies drop connections after an idle time with no activity. If this is the case, configure the SSE_KEEPALIVE_INTERVAL envvar. This will send periodic SSE comments to keep connections open.

Event Bus Configuration

The Infinite Scale event bus can be configured by a set of environment variables.

In case of an orchestrated installation like with Docker or Kubernetes, the event bus must be an external service for scalability like a Redis Sentinel cluster or a key-value-store NATS JetStream. Both named stores are supported and also used in Caching and Persistence. The store used is not part of the Infinite Scale installation and must be separately provided and configured.
Note that from a configuration point of view, caching and persistence are independent of the event bus configuration.

Note that for each global environment variable, a service-based one might be available additionally. For precedences see Environment Variable Notes. Check the configuration section below.

Without the aim of completeness, see the list of environment variables to configure the event bus:

Envvar Description

Envvar	Description
`OCIS_EVENTS_ENDPOINT`	The address of the event system.
`OCIS_EVENTS_CLUSTER`	The clusterID of the event system. Mandatory when using NATS as event system.
`OCIS_EVENTS_ENABLE_TLS`	Enable TLS for the connection to the events broker.
`OCIS_INSECURE`	Whether to verify the server TLS certificates.
`OCIS_EVENTS_AUTH_USERNAME`	The username to authenticate with the events broker.
`OCIS_EVENTS_AUTH_PASSWORD`	The password to authenticate with the events broker.

OCIS_EVENTS_ENDPOINT

The address of the event system.

OCIS_EVENTS_CLUSTER

The clusterID of the event system. Mandatory when using NATS as event system.

OCIS_EVENTS_ENABLE_TLS

Enable TLS for the connection to the events broker.

OCIS_INSECURE

Whether to verify the server TLS certificates.

OCIS_EVENTS_AUTH_USERNAME

The username to authenticate with the events broker.

OCIS_EVENTS_AUTH_PASSWORD

The password to authenticate with the events broker.

Configuration

Environment Variables

The sse service is configured via the following environment variables. Read the Environment Variable Types documentation for important details. Column IV shows with which release the environment variable has been introduced.

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8.1.0

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YAML Example

Note the file shown below must be renamed and placed in the correct folder according to the Configuration File Naming conventions to be effective.
See the Notes for Environment Variables if you want to use environment variables in the yaml file.

8.1.0

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