initial WIP Typespec E2E doc (#24343)

* initial WIP Typespec E2E doc

* updated local commands

* Updated doc

documentation/typespec-rest-api-dev-process.md

@@ -0,0 +1,108 @@
+# Azure Rest API, SDK development process with TypeSpec
+
+## Table Of Content
+
+1. Introduction
+2. Repo setup & prerequisites
+3. Setting up
+4. 
+
+### 1. Introduction
+
+This document describes the processes of developing Azure Rest APIs and SDKs with TypeSpec language. The steps below assumes that you are developing TypeSpec API specifications in the `azure-rest-api-specs` repos.
+
+If you are developing within your own ADO repo first and then submitting into `azure-rest-api-specs` repos for review and release, you will need to copy the files over.
+
+### 2. Repo setup & prerequisites
+
+- The main repos for Azure rest-api are [azure-rest-api-specs](https://github.com/azure/azure-rest-api-specs) and [azure-rest-api-specs-pr](https://github.com/azure/azure-rest-api-specs-pr) repos. The `-pr` repo contains `RPSaaSMaster` and `RPSaaSDev` branches for ProviderHub based ARM service specs.
+
+#### 2.1 With VSCode docker .devcontainer
+
+All prerequisites have been installed in the dev container. You should to have `Docker Desktop` and `WSL2` running if you are on Windows machine.
+
+To start, you just need to install `Dev Containers` VS code extension, then open the repo path. 
+
+- VSCode will detect the .devcontainer and prompt you to reopen the workspace.
+
+- Alternatively, you can use Command Palette -> Dev Containers: Reopen in Container.
+  
+Once VSCode reopened in Container, you can run any of the program below in the VSCode integrated terminal.
+
+#### 2.2 With local machine development
+
+- [Node.js LTS](https://nodejs.org/en) version 16 or above. Ensure you can run the npm command in a command prompt:
+```
+  npm --version
+```
+
+- Run following command in the **repository root folder**. This will install required packages such as TypeSpec compilers and Azure Library packages.
+
+```
+   npm install
+```
+
+- Ensure you can run TypeSpec command within the repo folders.
+
+```
+   tsp --version 
+```
+
+- Install TypeSpec VisualStudio or VSCode extensions to get syntex highlighting, tool tips in IDE:
+  
+```
+  tsp code install
+``` 
+OR
+```
+  tsp vs install
+```
+
+### 3. Creating a TypeSpec project
+
+Please first review recommended folder structure detailed in [this document](https://github.com/Azure/azure-rest-api-specs/blob/main/documentation/typespec-structure-guidelines.md).
+
+1. Under `[reporoot]\specifications`, create service folder directly.
+2. Create your service component folder under the service folder. For example, `Sphere.Management` or `Azure.OpenAI`.
+3. Create a new TypeSpec project based on Azure template with command:
+
+```cli
+   tsp init https://aka.ms/typespec/azure-init
+```
+
+4. Compile the TypeSpec project with command:
+
+```cli
+  tsp compile .
+```
+  The generated swagger files should be correctly placed in `data-plane` or `resource-manager` folders follwoing the naming conventions.
+
+5. Now the project has been set up. You can modify the sample and develop your own APIs with TypeSpec
+
+
+### 4. Generate or Refresh SDK code from a TypeSpec project
+
+The section describe the process for data-plane SDKs. Management-plane SDKs still follow the `autorest` process.
+
+#### 4.1 With VSCode docker .devcontainer
+
+
+#### 4.2 With local machine development
+
+This assumes you have cloned language SDKs into your local folder. `./eng/script/TypeSpec-Generate-Sdk.ps1` script will generate the necessary SDK folder and project structure if it does not already exist, and then regenerate the SDK source code.
+
+Scenarios:
+
+1. Test generation of SDK project and code with local TypeSpec changes in your `rest-api-specs` repo. Please note this cannot be used to submit a SDK PR as it does not contain a valid commit id for the TypeSpec file.
+
+```cli
+   cd specifications/contoso/contoso.widgetmanager
+   ..\..\..\eng\script\TypeSpec-Generate-Sdk.ps1 -SdkRepoRootDirectory C:\Github\fork\azure-sdk-for-java\
+```
+
+2. Generate/refresh SDK code for PR submission. The following command will update tsp-location.yaml with commit id and repo info so the build can be generated and verified by the CI and release pipeline.
+
+```
+   cd specifications/contoso/contoso.widgetmanager
+   ..\..\..\eng\script\TypeSpec-Generate-Sdk.ps1 -SdkRepoRootDirectory C:\Github\fork\azure-sdk-for-java\ [commit id] Azure/azure-rest-api-specs
+```