Lars Simon Winzer
106 lines
5.0 KiB
Markdown
106 lines
5.0 KiB
Markdown
# Protocol Document
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This document describes the protocol for client-server communication in our application. It defines the structure of requests and responses, the supported commands along with thier request parameters, response formats and possible errors.
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# Table of Contents
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- [Protocol Document](#protocol-document)
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- [Table of Contents](#table-of-contents)
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- [General structure of requests](#general-structure-of-requests)
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- [Preconditions](#preconditions)
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- [Parsing](#parsing)
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- [Error Response](#error-response)
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- [Command dispatching](#command-dispatching)
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- [Error Response](#error-response-1)
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- [Command parsing](#command-parsing)
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- [Error Response](#error-response-2)
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- [Pre executions checks](#pre-executions-checks)
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- [Commands](#commands)
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<!-- Plase see the comments for copy n' paste ready examples -->
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# General structure of requests
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As mentioned before, our protocol is based on POP3.
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Each command is represented as a single line of text, starting with the command name followed by parameters. The server responds with a status line indicating success or failure, followed by the body.
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Requests can have parameters that provide additional information for the command. Parameters are key-value pairs separated by a equal sign (`=`).
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Responses are collections of key-value pairs, containing either a value or another collection, allowing for nested structures.
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Each collection is ended with the `END` keyword.
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# Preconditions
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The serverside pipeline to process incomming requests consists of multiple stages.
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Each of these stages can yield an error response if the request does not meet the requirements of that stage.
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## Parsing
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One of these stages is the parsing. It is responsible for parsing the raw request into a structured format that can be easily processed by the command handlers. It validates the syntax of the request aswell.
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### Error Response
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| Code | Discription |
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| :-------------- | :---------------------------------------------------------------------------------------------- |
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| `PARSING_ERROR` | The body of the request contains syntax errors (see message field of response for more details) |
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## Command dispatching
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After the request has been successfully parsed, the next stage is to dispatch the `PrimitiveRequest` to the appropriate `CommandParser`. This is done by the `CommandDispatcherDispatcher`, which uses the command name to determine which parser to use.
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### Error Response
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| Code | Discription |
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| :---------------- | :---------------------------------------------------------------- |
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| `UNKNOWN_COMMAND` | The command is unknown to this server. No parser has been defined |
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## Command parsing
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Once the `PrimitiveRequest` has been dispatched to the appropriate `CommandParser`, the parser is responsible for parsing the parameters of the request and creating a `Request` that can be executed by the responsible `CommandHandler`.
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### Error Response
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| Code | Discription |
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| :------------------ | :------------------------------------------------------------------------------------------------ |
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| `MISSING_PARAMETER` | A required parameter is missing from the request (see message field of response for more details) |
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# Pre executions checks
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Pre-execution checks are reusable validation steps that can be registered on command handlers.
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They are implemented as `HandlerCheck` instances and are executed by the `CommandHandlerExecutor` before the handler's main logic is invoked.
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<!--
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## Name of the check
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Description of the check, what it does and when it should be used.
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### Response if not met
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| Code | Discription |
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| :----------- | :----------------------- |
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| `ERROR_CODE` | Description of the error |
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-->
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# Commands
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Commands are the core of our protocol, representing the various actions that clients can request from the server. Each command has a unique name and may require specific parameters in addition to pre-execution checks.
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The server processes these commands and responds accordingly.
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<!--
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## Name of the command
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Description of the command, what it does and when it should be used.
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### Required pre-execution checks
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- [`Check1`](#check1)
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### Request Parameters
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| Parameter Name | Type | Optional | Description |
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| :------------- | :----- | :---------------------------------- | :-------------------- |
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| `param1` | `type` | If the parameter is optional or not | Description of param1 |
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### Response
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| Field | Type | Description |
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| :------- | :------------------ | :-------------------- |
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| `field1` | `type` | Description of field1 |
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| `field2` | `Collection<type2>` | |
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| Fields of `type2` | Type | Description |
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| :---------------- | :----- | :-------------------- |
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| `field1` | `type` | Description of field1 |
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-->
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