om2m-client 0.1.2

A client for interacting with OM2M CSE, compatible with CPython and MicroPython.

om2m-client

A MicroPython and Python client library for interacting with OM2M (Open Middleware for applications in the Internet of Things).
This library simplifies the creation and retrieval of oneM2M resources (AEs, Containers, ContentInstances, Subscriptions) on an OM2M CSE (Common Service Entity).

Table of Contents

1. Overview
2. Features
3. Installation
   • CPython (Regular Python 3)
   • MicroPython
4. Quick Start
5. Usage
   • Creating and Retrieving Resources
   • Retrieving Latest Data
   • Retrieving All Data from a Device
   • Replication (CPython Only)
6. Library Structure
7. MicroPython vs CPython Differences
8. Contributing
9. License
10. Authors & Contact

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Overview

oneM2M is a global standards initiative for Machine-to-Machine (M2M) and Internet of Things (IoT) technologies. OM2M is an open-source implementation of the oneM2M architecture, providing RESTful resources for IoT devices and applications.

The om2m-client library enables developers to:

• Create Application Entities (AEs) in an OM2M Infrastructure Node (IN).
• Create Containers within those AEs.
• Post ContentInstances (CIN) to store sensor data or device states.
• Subscribe to notifications via Subscriptions.
• Retrieve or list AEs, Containers, and ContentInstances from the CSE.

Designed to run on:

• MicroPython (for constrained devices like ESP32).
• CPython (for Middle Nodes (MNs) and general use).

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Features

• Lightweight: Utilizes urequests/ujson for MicroPython and requests/json for CPython.
• OneM2M Resource Management:
  • Application Entity (AE)
  • Container (CNT)
  • ContentInstance (CIN)
  • Subscription (SUB)
• Resource Retrieval: Fetch resources in JSON or XML format (JSON is default).
• Latest Content Retrieval: Helper functions to obtain the latest sensor reading for each device.
• Comprehensive: Covers most typical CRUD operations in OM2M.
• Partial Replication (CPython only): Functionality to replicate AEs and data to another OM2M instance.

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Installation

Installation on CPython

Install the library using pip:

pip install om2m-client

• Requirements:
  • Python 3.6+ (tested with Python 3.7, 3.8, 3.9).
  • requests library (automatically installed as a dependency).

Installation on MicroPython

Since MicroPython does not utilize setup.py or PyPI in the traditional sense, installation involves manually transferring the necessary files or using the mip package manager.

Method 1: Manual Copy

1. Copy the om2m_client Package:

   • Transfer the om2m_client directory (containing client.py, models.py, exceptions.py, etc.) to your MicroPython device using tools like mpremote, ampy, or rshell.

2. Ensure Dependencies are Available:

   • urequests: Many MicroPython firmware images include urequests by default. If not, download and transfer urequests.py to your device.
   • ujson: Typically included in MicroPython firmware. If missing, download and transfer ujson.py.

Method 2: Using mip (MicroPython Package Manager)

1. Create a requirements.txt File:

   micropython-urequests
   micropython-ujson
   

2. Install Dependencies via mip:

   mip install -r requirements.txt
   

3. Transfer the om2m_client Package:

   • Similar to Method 1, ensure the om2m_client directory is on your MicroPython device.

Note: The standard pip or setup.py mechanism does not typically work on microcontrollers.

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Quick Start

This example demonstrates how to use om2m-client in either Python or MicroPython environments.

from om2m_client import OM2MClient, AE, Container, ContentInstance

# 1) Instantiate the OM2MClient
client = OM2MClient(
    base_url="http://localhost:8282",  # OM2M base URL
    cse_id="mn-cse",
    cse_name="mn-name",
    username="admin",
    password="admin",
    use_json=True
)

# 2) Create an AE
ae = AE(rn="myDeviceAE", api="app-sample", rr=False, lbl=["test-device"])
ae_location = client.create_ae(ae)
print("Created AE at:", ae_location)

# 3) Create a Container under that AE
container_path = f"{client.cse_id}/{client.cse_name}/myDeviceAE"
container = Container(rn="DATA", lbl=["sensor/data"])
cnt_location = client.create_container(container_path, container)
print("Created Container at:", cnt_location)

# 4) Create a ContentInstance (sensor reading)
cin_path = f"{client.cse_id}/{client.cse_name}/myDeviceAE/DATA"
temperature_cin = ContentInstance(cnf="application/json", con='{"temperature": 23}')
cin_location = client.create_content_instance(cin_path, temperature_cin)
print("Created ContentInstance at:", cin_location)

# 5) Retrieve the latest data
latest = client.retrieve_latest_data("myDeviceAE", "DATA")
print("Latest data from 'myDeviceAE':", latest)

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Usage

Creating and Retrieving Resources

1. Application Entity (AE)

from om2m_client import OM2MClient, AE

client = OM2MClient(
    base_url="http://localhost:8282",
    cse_id="mn-cse",
    cse_name="mn-name",
    username="admin",
    password="admin",
    use_json=True
)

ae = AE(rn="MyAE", api="my-api", rr=False, lbl=["test-device"])
ae_location = client.create_ae(ae)
print("Created AE at:", ae_location)

2. Container (CNT)

from om2m_client import Container

parent_path = "mn-cse/mn-name/MyAE"
container = Container(rn="DATA", lbl=["sensor/data"])
cnt_location = client.create_container(parent_path, container)
print("Created Container at:", cnt_location)

3. ContentInstance (CIN)

from om2m_client import ContentInstance
import json

cin_path = "mn-cse/mn-name/MyAE/DATA"
cin = ContentInstance(cnf="application/json", con=json.dumps({"temperature": 25}))
cin_location = client.create_content_instance(cin_path, cin)
print("Created ContentInstance at:", cin_location)

4. Subscription (SUB)

from om2m_client import Subscription

sub_path = "mn-cse/mn-name/MyAE"
subscription = Subscription(rn="mySubscription", nu="http://notify-endpoint", nct=2)
sub_location = client.create_subscription(sub_path, subscription)
print("Created Subscription at:", sub_location)

Retrieving Latest Data

Retrieve the latest ContentInstance for a given AE and Container (DATA by default):

latest_cin = client.retrieve_latest_data(device_name="MyAE", container_name="DATA")
print("Latest ContentInstance:", latest_cin)

Retrieving All Data from a Device

Retrieve all ContentInstances from a container and obtain a minimal JSON structure:

all_data = client.retrieve_all_content_instances_minimal(device_name="MyAE", container_name="DATA")
print("All ContentInstances:", all_data)

Replication (CPython Only)

Note: The replication function is not available in MicroPython. Attempting to use it in MicroPython will raise a NotImplementedError.

import sys
from om2m_client import OM2MClient

# Ensure the environment is CPython
if sys.implementation.name != "micropython":
    source_client = OM2MClient(
        base_url="http://source-host:8282",
        cse_id="mn-cse",
        cse_name="mn-name",
        username="admin",
        password="admin",
        use_json=True
    )
    
    target_client = OM2MClient(
        base_url="http://target-host:8282",
        cse_id="mn-cse",
        cse_name="mn-name",
        username="admin",
        password="admin",
        use_json=True
    )
    
    # Retrieve all data from the source AE
    source_data = source_client.retrieve_all_content_instances_minimal(device_name="MyAE")
    
    # Replicate data to the target client
    source_client.replicate_ae_data_from_minimal(
        minimal_data=source_data,
        target_client=target_client,
        container_name="DATA2"
    )

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Library Structure

om2m_client/
├── client.py            # Core OM2MClient class with CRUD methods
├── models.py            # Resource classes (AE, Container, ContentInstance, Subscription)
├── exceptions.py        # Custom exceptions (OM2MRequestError, etc.)
├── __init__.py          # Makes the folder a package
└── ... (additional files, if needed)

Notable Files

• client.py
  Contains the OM2MClient class, providing CRUD functions for AE, Container, CIN, Subscription, and helper methods (e.g., retrieving the latest data).

• models.py
  Defines simple Python classes (AE, Container, ContentInstance, Subscription) to store resource attributes in a structured manner.

• exceptions.py
  Provides custom exception classes for enhanced error handling.

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MicroPython vs CPython Differences

1. Imports:

   • MicroPython: Uses urequests and ujson.
   • CPython: Uses requests and json.

2. Replication Function:

   • MicroPython: replicate_ae_data_from_minimal is not implemented and will raise a NotImplementedError.
   • CPython: Fully functional, allowing replication of AEs and data to another OM2M instance.

3. JSON Indentation:

   • MicroPython’s ujson does not support indent. The library includes fallbacks to produce minimal JSON when running on MicroPython.

4. Setup Tools:

   • MicroPython: Does not support pip install . or typical setup.py usage. Manual file transfers or mip are required.
   • CPython: Supports standard pip and setup.py installations.

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Contributing

Contributions are welcome! To contribute to the om2m-client project, follow these steps:

1. Fork the Repository
   Fork the GitHub repository to your own account.

2. Clone Your Fork

   git clone https://github.com/<your-username>/micropython-om2m-client.git
   cd micropython-om2m-client
   

3. Create a New Branch
   Create a branch for your feature or bug fix:

   git checkout -b feature/my-awesome-update
   

4. Make Your Changes
   Implement your feature or fix the bug. Ensure your code follows the project's coding standards.

5. Commit Your Changes

   git commit -m "Add feature X or fix bug Y"
   

6. Push to Your Fork

   git push origin feature/my-awesome-update
   

7. Open a Pull Request
   Navigate to your fork on GitHub and open a pull request against the main repository.

Guidelines

• Code Quality: Ensure your code is clean, well-documented, and follows PEP 8 guidelines.
• Testing: Add or update tests to cover your changes.
• Documentation: Update the README or other documentation as necessary.
• Issue Tracking: If you're addressing an existing issue, reference it in your pull request.

We appreciate your contributions—whether it's bug reports, feature requests, or code improvements!

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License

This project is licensed under the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) license.

You are free to:

• Share: Copy and redistribute the material in any medium or format.
• Adapt: Remix, transform, and build upon the material.

Under the following terms:

• Attribution: You must give appropriate credit, provide a link to the license, and indicate if changes were made.
• NonCommercial: You may not use the material for commercial purposes.

For full license details, visit https://creativecommons.org/licenses/by-nc/4.0/.

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Authors & Contact

• Ahmad Hammad
  Email: [e-mail]

• Omar Hourani
  Email: [e-mail]

GitHub: SCRCE/micropython-om2m-client

Feedback, bug reports, and feature requests are always welcome!
Feel free to open an issue or submit a pull request on GitHub.

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Enjoy building IoT solutions with OM2M and MicroPython (or CPython). Happy coding!