Developing Apps

Node.js apps that interact with a Node.js Client for VMware GemFire cluster are the clients within a client/server model. The VMware GemFire cluster contains the servers.

A best practice is to first develop in a local envirornment, followed by deployment and testing with a Cloud Cache service instance. Read about the environments in The Development Environment.

All apps must implement a set of intialization steps. See App Initialization Steps for details.

Example code is available at https://github.com/gemfire/node-examples. Each example has a README file that briefly explains what the example demonstrates and how to run the example. The CRUD-ops example presents introductory code to get started using the Node.js Client. CRUD Operations describes the example and introduces the operations.

API Characteristics

Many API methods return a Javascript promise; these methods execute asynchronously and resolve to a value when complete. This implementation is intentional. All method invocations that may result in an extra network hop while executing are defined to return a promise.

To capture the resolved value from a method that returns a promise, use a Javascript await. For example, the region.get(key) function returns a promise that resolves to the entry’s value for the given key. The value will be assigned once the promise resolves when using await, as in the example code fragment:

value = await region.get(CustomerId)
// code here that uses value

Or, the code may be written as:

region.get(CustomerId)
  .then(value => {
    // code here that uses value
  })

  .catch(err => {
    // code here that handles errors
  });