Parsing Command line arguments

When starting the server, the application actually uses Components.js twice to instantiate components. The first instantiation is used to parse the command line arguments. These then get converted into Components.js variables and are used to instantiate the actual server.

Architecture

flowchart TD
  CliResolver("<strong>CliResolver</strong><br>CliResolver")
  CliResolver --> CliResolverArgs

  subgraph CliResolverArgs[" "]
    CliExtractor("<strong>CliExtractor</strong><br>YargsCliExtractor")
    ShorthandResolver("<strong>ShorthandResolver</strong><br>CombinedShorthandResolver")
  end

  ShorthandResolver --> ShorthandResolverArgs
  subgraph ShorthandResolverArgs[" "]
    BaseUrlExtractor("<br>BaseUrlExtractor")
    KeyExtractor("<br>KeyExtractor")
    AssetPathExtractor("<br>AssetPathExtractor")
  end

The CliResolver (urn:solid-server-app-setup:default:CliResolver) is simply a way to combine both the CliExtractor (urn:solid-server-app-setup:default:CliExtractor) and ShorthandResolver (urn:solid-server-app-setup:default:ShorthandResolver) into a single object and has no other function.

Which arguments are supported and which Components.js variables are generated can depend on the configuration that is being used. For example, for an HTTPS server additional arguments will be needed to specify the necessary key/cert files.

CliResolver

The CliResolver converts the incoming string of arguments into a key/value object. By default, a YargsCliExtractor is used, which makes use of the yargs library and is configured similarly.

ShorthandResolver

The ShorthandResolver uses the key/value object that was generated above to generate Components.js variable bindings. A CombinedShorthandResolver combines the results of multiple ShorthandExtractor by mapping their values to specific variables. For example, a BaseUrlExtractor will be used to extract the value for baseUrl, or port if no baseUrl value is provided, and use it to generate the value for the variable urn:solid-server:default:variable:baseUrl.

These extractors are also where the default values for the server are defined. For example, BaseUrlExtractor will be instantiated with a default port of 3000 which will be used if no port is provided.

The variables generated here will be used to initialize the server.