# Recipes & Ingredients

### Recipes

At design-time, resource assignments can be defined through so-called *Recipes*. Each recipe specifies the process of how to find the best-fitting allocation for a specific problem. At run-time, as soon as such an allocation is required, the corresponding recipe is executed on the basis of the currently available resources.

### Ingredients

Each recipe consists of so-called *ingredients*, which provide different types of functionality within the allocation process. They can be seen as building blocks plugged together in recipes. Currently, there are four different types of ingredients:

* **Input**. They are used as inputs for an allocation process and define on which resource types the allocation should be done. At run-time, they are replaced by the list of currently known resource instances of the type set in the input ingredient.
* **Transformer**. Transformers are used to modify the list of resource instances. The modification can either be that each instance is altered (*map*), *filtering* for e.g. certain attribute values, or *reducing* the set to a new object.
* **Algorithm**. Docker images can be used to process incoming resource instance lists and to compute the optimized allocation/result based on the input. The output of an algorithm ingredient is again a list of resource instances.
* **Output**. Output ingredients write the input they receive back to the database. They are used to persist the allocation result and can only be used at the end of a recipe, as they do not have any outgoing connectors.