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AEA Quick Start

If you want to create Autonomous Economic Agents (AEAs) that can act independently of constant user input and autonomously execute actions to achieve their objective, you can use the AEA framework.

<iframe width="560" height="315" src="" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>

This example will take you through a simple AEA to familiarise you with the basics of the framework.

Echo Skill Demo

This is a simple demo that introduces you to the main components of an AEA.

The fastest way to have your first AEA is to fetch one that already exists!

aea fetch fetchai/my_first_aea:0.28.5
cd my_first_aea

To learn more about the folder structure of an AEA project read on here.

??? note "Alternatively: step by step install:" Create a new AEA

First, create a new AEA project and enter it.

``` bash
aea create my_first_aea
cd my_first_aea

**Add the stub connection**

Second, add the stub connection to the project.

``` bash
aea add connection fetchai/stub:0.21.3

**Add the echo skill**

Third, add the echo skill to the project.

``` bash
aea add skill fetchai/echo:0.20.6

This copies the <code>fetchai/echo:0.20.6</code> skill code containing the "behaviours", and "handlers" into the project, ready to run. The identifier of the skill <code>fetchai/echo:0.20.6</code> consists of the name of the author of the skill, followed by the skill name and its version.

Echo Skill

Just like humans, AEAs can have skills to achieve their tasks. As an agent developer, you can create skills to add to your own AEAs. You can also choose to publish your skills so others add them to their AEAs. More details on skills can be found on this page .

The above agent has an echo skill, fetched from the registry, which simply echoes any messages it receives back to its sender.

Communication via Envelopes and Messages

AEAs use envelopes containing messages for communication. To learn more, check out the next section.

Stub Connection

Besides skills, AEAs may have one or more connections enabling them to interface with entities in the outside world. For example, an HTTP client connection allows an AEA to communicate with HTTP servers. To read more about connections see this page.

In this demo, we use the stub connection (fetchai/stub0.15.0) to send envelopes to and receive envelopes from the AEA.

A stub connection provides an I/O reader and writer. It uses two files for communication: one for incoming envelopes and the other for outgoing envelopes.

The AEA waits for a new envelope posted to the file my_first_aea/input_file, and adds a response to the file my_first_aea/output_file.

The format of each envelope is the following:


For example:


Install AEA Dependencies

aea install

Add and Create a Private Key

All AEAs need a private key to run. Add one now:

aea generate-key fetchai
aea add-key fetchai

Run the AEA

Run the AEA.

aea run

You will see the echo skill running in the terminal window (an output similar to the one below).

    _     _____     _
   / \   | ____|   / \
  / _ \  |  _|    / _ \
 / ___ \ | |___  / ___ \
/_/   \_\|_____|/_/   \_\


Starting AEA 'my_first_aea' in 'async' mode ...
info: Echo Handler: setup method called.
info: Echo Behaviour: setup method called.
info: [my_first_aea]: Start processing messages...
info: Echo Behaviour: act method called.
info: Echo Behaviour: act method called.
info: Echo Behaviour: act method called.

The framework first calls the setup methods in the skill's Handler and Behaviour classes in that order; after which it repeatedly calls the act method of Behaviour class. This is the main agent loop in action.

Add a Message to the Input File

You can send the AEA a message wrapped in an envelope using the CLI's interact command.

From a different terminal and same directory (ensure you are in the same virtual environment: pipenv shell):

cd my_first_aea
aea interact

You can now send messages to this AEA via an interactive tool by typing anything into the prompt and hitting enter twice (once to send the message and once more to check for a response).

Let us send hello to this AEA (type hello and press enter twice). In the original terminal, you will see the Echo Handler dealing with this envelope and its contained message. You should see an output similar to the one below but with a different dialogue_reference.

info: Echo Behaviour: act method called.
info: Echo Handler: message=Message(dialogue_reference=('1', '') message_id=1 target=0 performative=bytes content=b'hello'), sender=my_first_aea_interact
info: Echo Behaviour: act method called.
info: Echo Behaviour: act method called.

??? note "Manual approach:" Optionally, from a different terminal and same directory (i.e. the my_first_aea project), you can send the AEA a message wrapped in an envelope via the input file.

``` bash
echo 'my_first_aea,sender_aea,fetchai/default:1.0.0,\x12\x10\x08\x01\x12\x011*\t*\x07\n\x05hello,' >> input_file

You will see the <code>Echo Handler</code> dealing with the envelope and responding with the same message to the <code>output_file</code>, and also decoding the Base64 encrypted message in this case.

``` bash
info: Echo Behaviour: act method called.
Echo Handler: message=Message(sender=sender_aea,to=my_first_aea,content=b'hello',dialogue_reference=('1', ''),message_id=1,performative=bytes,target=0), sender=sender_aea
info: Echo Behaviour: act method called.
info: Echo Behaviour: act method called.

Note, due to the dialogue reference having to be incremented, you can only send the above envelope once! This approach does not work in conjunction with the <code>aea interact</code> command.

Stop the AEA

You can stop an AEA by pressing CTRL C.

Once you do, you should see the AEA being interrupted and then calling the teardown() methods:

info: Echo Behaviour: act method called.
info: Echo Behaviour: act method called.
^C my_first_aea interrupted!
my_first_aea stopping ...
info: Echo Handler: teardown method called.
info: Echo Behaviour: teardown method called.

Write a Test for the AEA

We can write an end-to-end test for the AEA utilising helper classes provided by the framework.

??? note "Writing tests:" The following test class replicates the preceding demo and tests its correct behaviour. The AEATestCase classes are a tool for AEA developers to write useful end-to-end tests of their AEAs.

First, get the `packages` directory from the AEA repository (execute from the working directory which contains the <code>my_first_aea</code> folder):

``` bash
svn export

Then write the test:

``` python
import signal
import time

from aea.common import Address
from aea.mail.base import Envelope
from aea.protocols.base import Message
from aea.protocols.dialogue.base import Dialogue

from packages.fetchai.protocols.default.dialogues import DefaultDialogue, DefaultDialogues
from packages.fetchai.protocols.default.message import DefaultMessage
from packages.fetchai.protocols.default.serialization import DefaultSerializer
from aea.test_tools.test_cases import AEATestCase

class TestEchoSkill(AEATestCase):
    """Test that echo skill works."""

    def test_echo(self):
        """Run the echo skill sequence."""
        process = self.run_agent()
        is_running = self.is_running(process)
        assert is_running, "AEA not running within timeout!"

        # add sending and receiving envelope from input/output files
        sender_aea = "sender_aea"
        def role_from_first_message(
            message: Message, receiver_address: Address
        ) -> Dialogue.Role:
            return DefaultDialogue.Role.AGENT
        dialogues = DefaultDialogues(sender_aea, role_from_first_message)
        message_content = b"hello"
        message = DefaultMessage(
        sent_envelope = Envelope(

        self.send_envelope_to_agent(sent_envelope, self.agent_name)

        received_envelope = self.read_envelope_from_agent(self.agent_name)

        assert == received_envelope.sender
        assert sent_envelope.sender ==
        assert sent_envelope.protocol_id == received_envelope.protocol_id
        received_message = DefaultMessage.serializer.decode(received_envelope.message)
        assert message.content == received_message.content

        check_strings = (
            "Echo Handler: setup method called.",
            "Echo Behaviour: setup method called.",
            "Echo Behaviour: act method called.",
        missing_strings = self.missing_from_output(process, check_strings)
        assert (
            missing_strings == []
        ), "Strings {} didn't appear in agent output.".format(missing_strings)

        assert (
        ), "Echo agent wasn't successfully terminated."


Place the above code into a file <code></code> in your AEA project directory (the same level as the <code>aea-config.yaml</code> file).

To run, execute the following:

``` bash

Delete the AEA

Delete the AEA from the parent directory (cd .. to go to the parent directory).

aea delete my_first_aea

Next Steps

To gain an understanding of the core components of the framework, please continue to the next page:

For more demos, use cases or step-by-step guides, please check the following: