Topics¶
With the initial schema applied to the gateway, you can create new topics. Because they're responsible for storing all data in Apache Kafka, topics are a fundamental part of Quick.
Creating new topics¶
Recalling the schema from the previous section,
there are two types of data: Purchase and Product.
The application should be able to store the data of both types.
Therefore, the next step is to create the corresponding topics.
First, you create the topic for Purchase by running:
quick topic create purchase \
--key-type string --value-type schema --schema example.Purchase
The first parameter is purchase, the topic's name you create.
The key-type and value-type options define the key and value types, respectively.
Quick ensures that data ingested into this topic conforms to these types.
If you'd try to ingest data with a number as the key into the purchase topic, Quick throws an error.
Next to primitives types like string, Quick also supports complex types defined by schema.
When using the schema option, you have to tell Quick what this schema should look like.
You can do this by referencing a type of GraphQL schema applied to a gateway.
In this case, you want first to reference the gateway, here called example.
In example, the Purchase type corresponds to the data in this topic.
Therefore, the --schema option is example.Purchase.
You can now also create the product topic and a price topic:
quick topic create product --key-type long --value-type schema --schema example.Product &&
quick topic create price --key-type long --value-type schema --schema example.Price
In contrast to the purchase topic, this topic has a key type long.
Topic information¶
The Quick CLI comes with commands to view the current state of topics in Quick. First, you can take a look at existing topics:
quick topic list
quick topic describe purchase
Deleting topics¶
You can also delete topics. For example, the price topic is no longer needed, and you want to remove it:
quick topic delete price