Websockets

What it is responsible for

The Websockets subsystem manages websocket-oriented work entering through

BaseWsInstance

AbstractWsAdapter

, and

MESSAGE_MAPPING_METADATA

. Its documented repository context describes Nest as a framework for building Node.js server-side applications; within that context, this subsystem owns the named websocket entry points rather than an independently documented external dependency.

MESSAGE_MAPPING_METADATA

marks a metadata-based boundary for work entering the subsystem, while the two class-level entry points establish the visible instance and adapter sides of that boundary. The available evidence does not describe transport behavior, connection lifecycle rules, message formats, routing semantics, or external integration details, so those should not be assumed from these names alone.

What it refuses

It rejects activation when

!canActivate

, with

WsException

. It rejects exception-filter input when

!Array.isArray(filters)

, with

InvalidExceptionFilterException

. It rejects a socket port when

!Number.isInteger(port)

, with

InvalidSocketPortException

. No literal exception text is present in the supplied evidence; the exception symbols and predicate conditions are the developers’ stated rejection information.

Notable members

```
BaseWsInstance
```
is a work-entry symbol and carries the instance-facing side of the subsystem’s visible boundary.
```
AbstractWsAdapter
```
is a work-entry symbol and identifies the abstract adapter-facing side of that boundary.
```
MESSAGE_MAPPING_METADATA
```
is a work-entry constant that identifies the metadata boundary associated with incoming mapped work in this named subsystem.

87 entities in

packages/websockets

. Nothing else in this repository depends on it.

What it is made of

Its 87 entities sit in 36 files under

packages/websockets

: 29 doc comments, 15 classes, 14 constants, 14 functions and 15 more.

constants.ts

holds 12 of them — more than any other file here.

WebSocketsController

declares 10 methods, the widest surface here.

Where work enters

```
Readme.md
```
—
```
packages/websockets/Readme.md
```
:1

BaseWsInstance

—

packages/websockets/adapters/ws-adapter.ts

AbstractWsAdapter

—

packages/websockets/adapters/ws-adapter.ts

:13

MESSAGE_MAPPING_METADATA

—

packages/websockets/constants.ts

How it refuses and fails

10 of its components record a refusal or a failure handler. 9 of them refuse work outright, under a condition written into the component itself. Their

catch

blocks handle a failure that already happened in 1 place.

How this code is named

These conventions cover most of the codebase. Learning them is faster than reading an index — each one lets you find any member of its family without looking it up.

Pattern Where Count Examples

Pattern	Where	Count	Examples
`*.interface.ts`	across the repository	9	`ws-response.interface.ts` , `nest-gateway.interface.ts` , `on-gateway-init.interface.ts` , `gateway-metadata.interface.ts`
`*.decorator.ts`	`packages/websockets/decorators/`	6	`ack.decorator.ts` , `message-body.decorator.ts` , `gateway-server.decorator.ts` , `socket-gateway.decorator.ts`

*.interface.ts

across the repository

ws-response.interface.ts

nest-gateway.interface.ts

on-gateway-init.interface.ts

gateway-metadata.interface.ts

*.decorator.ts

packages/websockets/decorators/

ack.decorator.ts

message-body.decorator.ts

gateway-server.decorator.ts

socket-gateway.decorator.ts

What it is responsible for

What it refuses

Notable members

What it is made of

Where work enters

How it refuses and fails

How this code is named

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