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.
It takes as input 2 components: a
HttpServerFactory and a
flowchart TD ServerInitializer("<strong>ServerInitializer</strong><br>ServerInitializer") ServerInitializer --> ServerInitializerArgs subgraph ServerInitializerArgs[" "] direction LR ServerFactory("<strong>ServerFactory</strong><br>BaseServerFactory") ServerListener("<strong>ServerListener</strong><br>ParallelHandler") end ServerListener --> HandlerServerListener("<strong>HandlerServerListener</strong><br>HandlerServerListener") HandlerServerListener --> HttpHandler("<strong>HttpHandler</strong><br><i>HttpHandler</i>")
HttpServerFactory is responsible for starting a server on a given port.
Depending on the configuration this can be an HTTP or an HTTPS server.
The created server emits events when it receives requests.
ServerListener is a class that takes the created server as input and attaches a listener to interpret events.
One listener that is always used is the
which calls an
HttpHandler to resolve HTTP requests.
Sometimes it is necessary to add additional listeners,
these can then be added to the
urn:solid-server:default:ServerListener as it is a
An example of this is when WebSockets are used to handle notifications.