Developing apps

SimSpace Weaver development requires an Amazon Linux 2 (AL2) environment to build apps because your simulations run on Amazon Linux in the AWS Cloud. If you're using Windows, you can use scripts in the SimSpace Weaver app SDK to create and launch a Docker container that runs AL2 with the dependencies that you need to build SimSpace Weaver apps. You can also launch an AL2 environment using Windows Subsystem for Linux (WSL), or use a native AL2 system. For more information, see Set up your local environment for SimSpace Weaver.

Note

Regardless of how you configure your local development environment, your apps run in Docker containers when you upload them to run in the AWS Cloud. Your apps don't have direct access to the host operating system.

General flow of a SimSpace Weaver app

1. Create an application.

2. Loop:

   1. Begin the update by creating a Transaction.

      1. Exit the loop if the simulation is shutting down.

   2. Process subscription and ownership entity events.

   3. Update the simulation.

   4. Commit the Transaction to end the update.

3. Destroy the application.

Spatial apps

Each spatial app has an ownership area that is a spatial region of the simulation world. Entities located in a spatial app's ownership area are stored in the app's assigned partition. The single spatial app has full ownership (read and write permissions) over all entities within its assigned partition. No other apps can write to those entities. The spatial app advances the state of its entities. Each spatial app owns only 1 partition. SimSpace Weaver uses the spatial location of an entity to index and assign it to a spatial app partition.

The SimSpace Weaver app SDK provides a sample application. You can find the source code for the spatial app of the sample application in the following folder (use the correct path separator for your operating system):

sdk-folder\Samples\PathfindingSample\src\SpatialApp

Custom apps

You create and use custom apps to interact with the simulation.

Custom apps can

• Create entities

• Subscribe to other partitions

• Commit changes

General flow of a custom app

1. Create an application.

2. Subscribe to a specific region in the simulation:

   1. Create a Transaction to begin the first update.

   2. Create a subscription for the specific region.

   3. Commit the Transaction to end the first update.

3. Loop:

   1. Create a Transaction to begin the update.

      1. Exit the loop if the simulation is shutting down.

   2. Process state changes.

   3. Commit the Transaction to end the update.

4. Destroy the application.

After a custom app creates an entity, it must transfer the entity to a spatial domain in order for the entity to exist spatially within the simulation. SimSpace Weaver uses the entity's spatial location to place the entity in the appropriate spatial app partition. The custom app that created the entity can't update or delete the entity after transferring it to a spatial domain.

The SimSpace Weaver app SDK provides a sample application. You can use the custom apps included in the sample application as models for your own custom apps. You can find the source code for the view app (a custom app) of the sample application in the following folder (use the correct path separator for your operating system):

sdk-folder\Samples\PathfindingSample\src\ViewApp