When starting the server, multiple Initializers trigger to set up everything correctly, the last one of which starts listening to the specified port. Similarly, when stopping the server several Finalizers trigger to clean up where necessary, although the latter only happens when starting the server through code.
flowchart TD App("<strong>App</strong><br>App") App --> AppArgs subgraph AppArgs[" "] Initializer("<strong>Initializer</strong><br><i>Initializer</i>") AppFinalizer("<strong>Finalizer</strong><br><i>Finalizer</i>") end
urn:solid-server:default:App) is the main component that gets instantiated by Components.js.
Every other component should be able to trace an instantiation path back to it if it also wants to be instantiated.
It's only function is to contain an
which get called by calling
flowchart TD Initializer("<strong>Initializer</strong><br>SequenceHandler") Initializer --> InitializerArgs subgraph InitializerArgs[" "] direction LR LoggerInitializer("<strong>LoggerInitializer</strong><br>LoggerInitializer") PrimaryInitializer("<strong>PrimaryInitializer</strong><br>ProcessHandler") WorkerInitializer("<strong>WorkerInitializer</strong><br>ProcessHandler") end LoggerInitializer --> PrimaryInitializer PrimaryInitializer --> WorkerInitializer
The very first thing that needs to happen is initializing the logger. Before this other classes will be unable to use logging.
PrimaryInitializer will only trigger once, in the primary worker thread,
WorkerInitializer will trigger for every worker thread.
Although if your server setup is single-threaded, which is the default,
there is no relevant difference between those two.
flowchart TD PrimaryInitializer("<strong>PrimaryInitializer</strong><br>ProcessHandler") PrimaryInitializer --> PrimarySequenceInitializer("<strong>PrimarySequenceInitializer</strong><br>SequenceHandler") PrimarySequenceInitializer --> PrimarySequenceInitializerArgs subgraph PrimarySequenceInitializerArgs[" "] direction LR CleanupInitializer("<strong>CleanupInitializer</strong><br>SequenceHandler") PrimaryParallelInitializer("<strong>PrimaryParallelInitializer</strong><br>ParallelHandler") WorkerManager("<strong>WorkerManager</strong><br>WorkerManager") end CleanupInitializer --> PrimaryParallelInitializer PrimaryParallelInitializer --> WorkerManager
The above is a simplification of all the initializers that are present in the
as there are several smaller initializers that also trigger but are less relevant here.
CleanupInitializer is an initializer that cleans up anything
that might have remained from a previous server start
and could impact behaviour.
Relevant components in other parts of the configuration are responsible for adding themselves to this array if needed.
An example of this is file-based locking components which might need to remove any dangling locking files.
PrimaryParallelInitializer can be used to add any initializers to that have to happen in the primary process.
This makes it easier for users to add initializers by being able to append to its handlers.
WorkerManager is responsible for setting up the worker threads, if any.
flowchart TD WorkerInitializer("<strong>WorkerInitializer</strong><br>ProcessHandler") WorkerInitializer --> WorkerSequenceInitializer("<strong>WorkerSequenceInitializer</strong><br>SequenceHandler") WorkerSequenceInitializer --> WorkerSequenceInitializerArgs subgraph WorkerSequenceInitializerArgs[" "] direction LR WorkerParallelInitializer("<strong>WorkerParallelInitializer</strong><br>ParallelHandler") ServerInitializer("<strong>ServerInitializer</strong><br>ServerInitializer") end WorkerParallelInitializer --> ServerInitializer
WorkerInitializer is quite similar to the
PrimaryInitializer but triggers once per worker thread.
WorkerParallelInitializer can be used
to add any custom initializers that need to run.
ServerInitializer is the initializer that finally starts up the server by listening to the relevant port,
once all the initialization described above is finished.
This is an example of a component that differs based on some of the choices made during configuration.
flowchart TD ServerInitializer("<strong>ServerInitializer</strong><br>ServerInitializer") ServerInitializer --> WebSocketServerFactory("<strong>ServerFactory</strong><br>WebSocketServerFactory") WebSocketServerFactory --> BaseHttpServerFactory("<br>BaseHttpServerFactory") BaseHttpServerFactory --> HttpHandler("<strong>HttpHandler</strong><br><i>HttpHandler</i>") ServerInitializer2("<strong>ServerInitializer</strong><br>ServerInitializer") ServerInitializer2 ---> BaseHttpServerFactory2("<strong>ServerFactory</strong><br>BaseHttpServerFactory") BaseHttpServerFactory2 --> HttpHandler2("<strong>HttpHandler</strong><br><i>HttpHandler</i>")
Depending on if the configurations necessary for websockets are imported or not,
urn:solid-server:default:ServerFactory identifier will point to a different resource.
There will always be a
BaseHttpServerFactory that starts the HTTP(S) server,
but there might also be a
WebSocketServerFactory wrapped around it to handle websocket support.
Although not indicated here, the parameters for initializing the
might also differ in case an HTTPS configuration is imported.
HttpHandler it takes as input is responsible for how HTTP requests get resolved.