# 🔧 Method Development Workflow

This guide explains the typical steps to develop and publish a method in the Cloud Computing Platform (CCP).

If you're new to the platform, it will help you understand **how a method works behind the scenes**, what CCP expects, and how to go from your algorithm to a fully executable component.

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## 🧠 What is a Method?

In CCP, a *method* is not just code — it is a full description of:

- What the method does
- What inputs it requires
- How to run it inside a container
- Where to collect its outputs
- Which environment it needs to execute

Your method becomes an object that users can execute via a form or programmatically through APIs.

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## 1. 📁 Prepare Your Code

Your algorithm must live in a **public repository or archive**. You should:

- Separate code from data
- Ensure it’s **executable via shell** (e.g., `python script.py`)
- Include a dependency file (e.g., `requirements.txt` for Python)

CCP will **clone your repo** and run your code inside a Docker container.

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## 2. 🧩 Define Inputs

Identify what your script needs as configuration or input data.

Each of these will be represented as a **form field** when users run your method:

| Type          | Examples                                |
|---------------|------------------------------------------|
| Files         | Upload or workspace file                |
| URLs          | Links to remote resources               |
| Parameters    | Text, numbers, booleans, dates          |
| Lists         | Dropdowns, checklists (single or multi) |
| Credentials   | API keys, tokens                        |
| Docker image  | Required runtime (`ccpimage`)           |

Each field is declared in your `method.json`.

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## 3. 🐳 Choose the Runtime (ccpimage)

Set the `ccpimage` input to define the **Docker image** that your method runs inside.

You can use:

- 🐧 `bash` — basic Unix environment
- 🐍 `python:3.9`, `r-base`, etc.
- 🐳 Custom Docker image (see [Consolidation](./08_consolidation))

---

## 4. ⚙️ Deploy and Execute Scripts

CCP separates two phases:

- **Deploy script**: runs before execution. Use it to:
  - Clone your repo
  - Install dependencies
  - Download data
- **Execute script**: runs your algorithm with input parameters

Use `{{placeholders}}` to substitute field values dynamically.

Example:

```bash
python repo/myscript.py --input {{file}} --output /ccp_data/result.json
```

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## 5. 📦 Write to `/ccp_data`

To be collected by CCP, your output files must be saved in `/ccp_data/`.

CCP will package this directory as `output.zip`, including:

- Result files
- Execution logs (`stdout`, `stderr`)
- Metadata (`method.json`, `jobStatus.json`, `provo.xml`, ...)

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## 💡 Common Pitfalls

| ❌ Don't Do This                            | ✅ Instead |
|---------------------------------------------|------------|
| Bundle data into the script                 | Expect files from the execution form |
| Hardcode input paths                        | Use script arguments and `{{param}}` |
| Forget to write outputs to `/ccp_data`      | Always direct your output files there |
| Require manual install of dependencies      | Use a `requirements.txt` in your repo |

---

## ✅ Ready to Continue?

Now that you understand the structure, you can:

- 🐍 [Write your Python-based method](./03_python_method)

- 🧩 [Define inputs of various types](./05_input_types/00_inputs.md)

- 🛠 [Write execution scripts with placeholders](./06_scripts_and_placeholders)

---

## 🔗 Related Pages

- 🐣 [Concepts for Beginners](/01_quickstart/04_concepts_for_beginners)

- 👨‍💻 [Quickstart: Building simple methods](/01_quickstart/05_building_simple_method)

- 🐧 [Docker image input](./02_defining_ccpimage.md)

- 🔣 [Structure of method.json](./07_method_json)

- 📂 [Execution output structure](/03_execution/02_outputs_and_logs)