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53 lines
2.4 KiB
Markdown
53 lines
2.4 KiB
Markdown
# Parsing Command line arguments
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When starting the server, the application actually uses Components.js twice to instantiate components.
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The first instantiation is used to parse the command line arguments.
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These then get converted into Components.js variables and are used to instantiate the actual server.
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## Architecture
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```mermaid
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flowchart TD
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CliResolver("<strong>CliResolver</strong><br>CliResolver")
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CliResolver --> CliResolverArgs
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subgraph CliResolverArgs[" "]
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CliExtractor("<strong>CliExtractor</strong><br>YargsCliExtractor")
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ShorthandResolver("<strong>ShorthandResolver</strong><br>CombinedShorthandResolver")
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end
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ShorthandResolver --> ShorthandResolverArgs
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subgraph ShorthandResolverArgs[" "]
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BaseUrlExtractor("<br>BaseUrlExtractor")
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KeyExtractor("<br>KeyExtractor")
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AssetPathExtractor("<br>AssetPathExtractor")
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end
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```
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The `CliResolver` (`urn:solid-server-app-setup:default:CliResolver`) is simply a way
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to combine both the `CliExtractor` (`urn:solid-server-app-setup:default:CliExtractor`)
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and `ShorthandResolver` (`urn:solid-server-app-setup:default:ShorthandResolver`)
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into a single object and has no other function.
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Which arguments are supported and which Components.js variables are generated
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can depend on the configuration that is being used.
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For example, for an HTTPS server additional arguments will be needed to specify the necessary key/cert files.
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## CliResolver
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The `CliResolver` converts the incoming string of arguments into a key/value object.
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By default, a `YargsCliExtractor` is used, which makes use of the `yargs` library and is configured similarly.
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## ShorthandResolver
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The `ShorthandResolver` uses the key/value object that was generated above to generate Components.js variable bindings.
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A `CombinedShorthandResolver` combines the results of multiple `ShorthandExtractor`
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by mapping their values to specific variables.
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For example, a `BaseUrlExtractor` will be used to extract the value for `baseUrl`,
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or `port` if no `baseUrl` value is provided,
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and use it to generate the value for the variable `urn:solid-server:default:variable:baseUrl`.
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These extractors are also where the default values for the server are defined.
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For example, BaseUrlExtractor will be instantiated with a default port of `3000`
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which will be used if no port is provided.
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The variables generated here will be used to [initialize the server](initialization.md).
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