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added usage section to readme

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Christian Bergmiller 2019-05-01 18:12:51 +02:00
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README.md
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@ -16,12 +16,6 @@ This library has also [sync wrapper](https://github.com/FreeOpcUa/opcua-asyncio/
The primary goal of opcua-asyncio is to create an asynchronous OPC UA client based on asyncio and remove hacks for support of python 2 and older python 3 versions.
Asynchronous programming allows for simpler code (e.g. less need for locks) and potentially performance gains.
## Documentation
The API remains mostly unchanged in regards to [python-opcua](https://github.com/FreeOpcUa/python-opcua). Main difference is that many methods have been refactored to return coroutines.
Please have a look at [the examples](https://github.com/FreeOpcUa/opcua-asyncio/blob/master/examples) and/or the code.
---
OPC UA binary protocol implementation is quasi complete and has been tested against many different OPC UA stacks. API offers both a low level interface to send and receive all UA defined structures and high level classes allowing to write a server or a client in a few lines. It is easy to mix high level objects and low level UA calls in one application.
@ -37,15 +31,69 @@ With pip
pip install asyncua
# Usage
We assume that you already have some experience with the asyncio module, the async / await syntax and the concept of
asyncio Tasks.
## Client
The `Client` class provides a high level API for connecting to APU UA servers, session management and access to basic
address space services.
The client can be used as a context manager. The client will automatically connect before the code inside the `with`
statement is executed. When your code leaves the `with` statement the client will disconnect. If you want to keep the
connection open (e.g. for listening to a subscription) you could write something like this:
```python
from asyncua import Client
async with Client(url='opc.tcp://localhost:4840/freeopcua/server/') as client:
while True:
# Do something with client
node = client.get_node('i=85')
value = await node.get_value()
```
Of course you can also call the `connect`, `disconnect` methods yourself if you do not want to use the context manager.
```python
from asyncua import Client
client = Client(url='opc.tcp://localhost:4840/freeopcua/server/')
await client.connect()
node = client.get_node('i=85')
value = await node.get_value()
# close connection before you exit the program
await client.disconnect()
```
See the example folder for more information on the client API.
## Node
The `Node` class provides a high level API for management of nodes as well as data access services.
## Subscription
The `Subscription` class provides a high level API for management of monitored items.
## Server
The `Server` class provides a high level API for creation of OPC UA server instances.
# Documentation
Some documentation is available on [ReadTheDocs](http://python-opcua.readthedocs.org/en/latest/).
The API remains mostly unchanged in regards to [python-opcua](https://github.com/FreeOpcUa/python-opcua).
Main difference is that many methods have been refactored to return coroutines.
Please have a look at [the examples](https://github.com/FreeOpcUa/opcua-asyncio/blob/master/examples) and/or the code.
The original documentation (for python-opcua) is available here [ReadTheDocs](http://python-opcua.readthedocs.org/en/latest/).
A simple GUI client is available: https://github.com/FreeOpcUa/opcua-client-gui
Examples: https://github.com/FreeOpcUa/opcua-asyncio/tree/master/examples
Browse the examples: https://github.com/FreeOpcUa/opcua-asyncio/tree/master/examples
A good starting point are the minimal examples.
Minimal client example: https://github.com/FreeOpcUa/opcua-asyncio/blob/master/examples/client-minimal.py
Minimal server example: https://github.com/FreeOpcUa/opcua-asyncio/blob/master/examples/server-minimal.py

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examples/client-minimal.py
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@ -9,7 +9,6 @@ _logger = logging.getLogger('asyncua')
async def main():
# url = 'opc.tcp://192.168.2.64:4840'
url = 'opc.tcp://localhost:4840/freeopcua/server/'
# url = 'opc.tcp://commsvr.com:51234/UA/CAS_UA_Server'
try: