# Create an application that references an external file in Infrastructure Composer
<a name="using-composer-external-files-examples-example3"></a>

This example uses the Amazon SAM CLI to create an application that references an external file for its state machine definition. You then load your project in Infrastructure Composer with your external file properly referenced.

**Example**

1. First, use the Amazon SAM CLI **sam init** command to initialize a new application named `demo`. During the interactive flow, select the **Multi-step workflow** quick start template.

   ```
   $ sam init
   
   ...
   
   Which template source would you like to use?
           1 - Amazon Quick Start Templates
           2 - Custom Template Location
   Choice: 1
   
   Choose an Amazon Quick Start application template
           1 - Hello World Example
           2 - Multi-step workflow
           3 - Serverless API
           4 - Scheduled task
           ...
   Template: 2
   
   Which runtime would you like to use?
           1 - dotnet6
           2 - dotnetcore3.1
           ...
           15 - python3.7
           16 - python3.10
           17 - ruby2.7
   Runtime: 16
   
   Based on your selections, the only Package type available is Zip.
   We will proceed to selecting the Package type as Zip.
   
   Based on your selections, the only dependency manager available is pip.
   We will proceed copying the template using pip.
   
   Would you like to enable X-Ray tracing on the function(s) in your application?  [y/N]: ENTER
   
   Would you like to enable monitoring using CloudWatch Application Insights?
   For more info, please view https://docs.aws.amazon.com/AmazonCloudWatch/latest/monitoring/cloudwatch-application-insights.html [y/N]: ENTER
   
   Project name [sam-app]: demo
   
       -----------------------
       Generating application:
       -----------------------
       Name: demo
       Runtime: python3.10
       Architectures: x86_64
       Dependency Manager: pip
       Application Template: step-functions-sample-app
       Output Directory: .
       Configuration file: demo/samconfig.toml
       
       Next steps can be found in the README file at demo/README.md
   
   ...
   ```

   This application references an external file for the state machine definition.

   ```
   ...
   Resources:
     StockTradingStateMachine:
       Type: AWS::Serverless::StateMachine
       Properties:
         DefinitionUri: statemachine/stock_trader.asl.json
   ...
   ```

   The external file is located in the `statemachine` subdirectory of our application.

   ```
   demo
   ├── README.md
   ├── __init__.py
   ├── functions
   │   ├── __init__.py
   │   ├── stock_buyer
   │   ├── stock_checker
   │   └── stock_seller
   ├── samconfig.toml
   ├── statemachine
   │   └── stock_trader.asl.json
   ├── template.yaml
   └── tests
   ```

1. Next, load your application in Infrastructure Composer from the console. From the Infrastructure Composer **home** page, select **Load a CloudFormation template**.

1. Select our `demo` project folder and allow the prompt to view files. Select our `template.yaml` file and select **Create**. When prompted, select **Save changes**.  
![\[The Infrastructure Composer Open project folder window with our project folder selected and the Create ready to be selected.\]](http://docs.amazonaws.cn/en_us/infrastructure-composer/latest/dg/images/aac_use_ex_15.png)

Infrastructure Composer automatically detects the external state machine definition file and loads it. Select our **StockTradingStateMachine** resource and choose **Details** to show the **Resource properties** panel. Here, you can see that Infrastructure Composer has automatically connected to our external state machine definition file.

![\[The Infrastructure Composer canvas view with the API Gateway resource properties panel displayed, showing the configuration of the external reference file.\]](http://docs.amazonaws.cn/en_us/infrastructure-composer/latest/dg/images/aac_use_ex_03.png)


Any changes made to the state machine definition file will be automatically reflected in Infrastructure Composer.