Server Utilities

The plaything.io server is written from ground up and uses its own solutions. Here are the widespread types used across the codebase:

Events

The Events.ts file defines the event API:

CreateEvent creates 2 objects in a tuple - the event interface (Event<T>) and the event trigger. The interface allows you to:

• addEventListener - adds a listener that fires every time the trigger is used
• removeEventListener - removed the listener
• addOnce - adds a listener that will fire on the next trigger and then be removed
• addOnceWhen - adds a listener that will fire once when a condition is met, then be removed

Reactives

The Reactive.ts file defines the Reactive<T> class

A reactive is a wrapper for a value, which has an event for when the value changes. It also can be synchronized with another reactive with a WeakRef.

Aggregate reactive

It is also possible to create an aggregate reactive with CreateReactiveAggregate<Tin, Tout>.

This will create a reactive whose value will be determined based on several input reactives of a homogenous type.

Pools

The Subscription.ts file defines 2 pool types:

• SubscribablePool<T> - any object which has an event for when an entry is added and removed as well as a way to get all current entries
• ManagedPool<T> created with CreatePool<T> - a default implementation of a SubscribablePool<T> which allows you to add, remove and clear the pool

Pools are used as a list which can be watched for updates.

Session pool

The Session.ts file defines a pool of sessions created with the CreateSessionPool<T> function

This is a simple pool which in addition to values also has keys

User pool

The User.ts file defines a pool of Users created with CreateUserPool<Tsession>.

A single user might have multiple sessions active at once - this pool keeps track of unique users with at least one session.

Active user pool

The User.ts file defines a pool of active Users created with CreateActiveUserPool<Tsession>.

The input session needs to have an isActive: Reactive<boolean> field. This pool will keep track of all unique users which are active on at least one session, as defined by the reactive field.

Subscriptions

The Subscription.ts file defines PoolSubscription<T>

A pool subscription is a wrapper for event listeners linked to a pool.

Pool Subscription

A pool subscription can be created with the CreatePoolSubscription function. The parameters are:

• The pool to subscribe to
• What to do when an entry is added. This callback has 2 arguments - the entry and whether it already was in the pool when creating the subscription
• What to do when an entry is removed
• Filter options

The returned object has a ReactTo<T> and unsubscribe function.

The ReactTo<T> function requires a getter which returns a Reactive<T> from a given entry. The second argument is the callback which accepts the entry, then the new value, then the old value. This function can be chained multiple times. It will be removed when the entry is removed

The unsubscribe function will remove all added event listeners and reactives

Nested Pools

The CreateNestedPool<T> function accepts a pool of pools and generates the flattened pool which is kept in sync with the input pool.

Web Socket Subscription Manager

The CreateWebsocketSubscriptionManager function creates an object which will manage any kind of subscription for Web Sockets.

This is a simple mechanism which accepts a Web Socket and name for a subscription and allows you to:

• Check if it already exists, in which case you dont need to subscribe again
• Create a subscription - this accepts a callback to call when the subscription expires. It will be called when the Web Socket closes
• Remove a subscription - will call the callback defined when creating the subscription and remove it