Apache Pulsar in Action

10 Data access

This chapter covers

• Storing and retrieving data with Pulsar Functions

• Using Pulsar’s internal state mechanism for data storage and retrieval

• Accessing data from external systems with Pulsar Functions

Thus far all of the information used by our Pulsar Functions has been provided inside the incoming messages. While this is an effective way to exchange information, it is not the most efficient or desirable way for Pulsar Functions to exchange information with one another. The biggest drawback to this approach is that it creates a dependency on the message source to provide your Pulsar function with the information it needs to do its job. This violates the encapsulation principle of object-oriented design, which dictates that ...