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Installation and first application¤


ASAB is distributed via pypi. There are three installation options:

We recommend using pip because it's the simplest installation method.

pip install asab

You can clone the repository from the master branch using pip:

pip install git+

Or clone the repository manually:

git clone
pip install -e .

You can install asab using the EasyInstall package manager.

easy_install asab

Creating your first application¤

  1. Create a file called with the following code:
        #!/usr/bin/env python3 
        # (1)!
        import asab # (2)!
        class MyApplication(asab.Application): # (3)!
            async def main(self): # (4)!
                print("Hello world") # (5)!
        if __name__ == '__main__': # (6)!
            app = MyApplication()
    1. All ASAB applications use Python 3.7+. This is specified by a hashbang line at the very beginning of the file.

    2. ASAB is included from as asab module via an import statement.

    3. Every ASAB Application needs to have an application object. It is a singleton: the application must create and operate precisely one instance of the application. ASAB provides the base [asab.Application][#TODO] class that you need to inherit from to implement your custom application class.

    4. The Application.main() method is one of the application lifecycle methods, that you can override to implement desired application functionality. The main method is a coroutine, so that you can await any tasks etc. in a fully asynchronous way. This method is called when the ASAB application is executed and initialized. The lifecycle stage is called "runtime".

    5. In this example, the app is printing a message to the screen.

    6. This part of the code is executed when you launch the Python program. It creates the application object and executes the run() method which creates and runs an event loop. This is the standard way of starting any ASAB application.

  2. Run the server:


    If you see the following output, you have successfully created and run an ASAB application server.

    Hello world!
  3. Stop the application by pressing Ctrl+C.


    ASAB is designed around an event loop. It is meant primarily for server architectures. For that reason, an ASAB application keeps running and serving requests unless or until you terminate the application. See run time.

You can continue with a step-by-step tutorial on how to build an ASAB-based web server.