Middleware Handlers

The Light platform is a plugin architecture, and there are a lot of middleware handlers provided to address all sort of cross-cutting concerns when you build a microservices. Also, users can add their own plugins within the business context. Basically, the light-4j framework is an embedded gateway that allows users to write their business logic on top of it. Before the request reaches the business handler, there are a lot of middleware handlers need to be executed to address security, metrics, audit, traceability, etc.

In this section, we will include several tutorials that relate to how to use certain middleware handlers.

CORS - Cross-Origin Resource Sharing

For some APIs/services, the endpoints will be accessed from a Single Page Application(React/Vue/Angular) served from another domain. In this case, the API server needs to handle the preflight OPTIONS request to enable CORS. As the light-4j platform can serve a single page application from the same domain as the API/service, you normally don’t need to do that if you are the owner of both client and service. However, during the development of the single page application, most developers will use nodejs to serve the Javascript with webpack hot reload to increase productivity, and you can use a proxy on the nodejs server to your APIs/services built on top of the light-4j frameworks. Read More »

How to use Prometheus for metrics

Introduction Light-4j provide Prometheus metrics handler as MiddlewareHandler to collects the API runtime information and save it to Prometheus Metric data module. And then use pre-defined HttpHandler (PrometheusGetHandler) to expose the prometheus Metric data module; Prometheus server will pull the metric from metrics_path which is configurable on Prometheus config yml file (for exampe: /v1/prometheus) ; The pulling interval is second base on the config file (scrape_interval: 30s). Configuration Configuration file (prometheus. Read More »