Plugins or Middleware Handlers that address all the cross-cutting concerns Read More »

Introduction When deploying large-scale microservices in an organization, monitoring and alerting are very important for the operation team. The traditional way to monitor monolithic application logs to find potential error status is not feasible anymore. When all service logs are aggregated to the ELK or Splunk, we have a big melting pot of logging statements from different services. To dig useful information from it and identify problematic service instances is not an easy job. Read More »

Logger-config is a module in the Light-4j framework that will be used to get the loggers and their current logging levels. It can also change the logging level for given loggers at runtime (Example: Change logging level to DEBUG for “com.networknt” logger for troubleshooting purposes). The user can also create a brand new logger with a level for debugging issues for a specific package or class on the target server. Read More »

In the entire life cycle of the exchange, there might be a lot of logging statements written to log files or other persistence storage. These logs will be used to assist production issue identifying and resolving, and a broad group of people might have access to these logs. For confidentiality, sensitive info needs to be masked before logging, for example, credit card numbers, sin numbers, etc. StarupHookProvider The mask module depends on JsonPath which is a third party library that gives us access to the JSON strings easily. Read More »

This module contains all the interfaces needed in registry and discovery. It also implements a direct registry, which you can hard-code services into the service.yml or direct-registry.yml to simulate Consul or Portal Registry during development. Although this is for local development, many users are still using it during production when they have allocated services to the exact IP and port on virtual machines. Currently, Consul and portal-registry are supported for external service registry and discovery. Read More »

Introduction This is a middleware handler that addresses cross-site scripting concerns. It encodes the header and body according to the configuration. As body encoding depends on BodyHandler middleware, it has to be plugged into the request/response chain after the body handler if the sanitizer.bodyEnabled is true in the values.yml If you use the http-sidecar or light-gateway, the sanitizer handler will only work with the headers. The body sanitization won’t work as the request body won’t be intercepted but transferred to the backend API directly. Read More »

API security is paramount, and today most APIs don’t have security built-in at all but rely on third-party API gateways to handle the security at the network level. It assumes that it is safe within the organization or utilizes some firewall setup to ensure that only the Gateway server can access the service host. Once we move to the cloud, everything is dynamic, and firewalls won’t work anymore as services can be down on one VM but start in another VM immediately through container orchestration tools. Read More »

This module is responsible for managing the life cycle of the embedded Undertow core HTTP server. It starts the server and initializes all middleware handlers/plugins along with a route handler provider when the handler chain is defined in the service.yml or OrchestrationHandler when the handler chains are defined in the handler.yml. It gracefully stops the server and allows the resources to be released and all in-flight requests to be processed before the server instance is deregistered on the service registry even someone clicks CTRL+C on the terminal. Read More »

Why we reinvent the wheel While building a lightweight microservices platform, we need an IoC service to bind implementations to interfaces. Given light-4j has server startup and shutdown hooks, we usually only need to inject with a constructor injection during the server startup. We have evaluated several IoC containers and found them to be too heavy for my use cases. Also, most of them are still using XML as configuration or annotations which eliminate the benefit of configurable IoC. Read More »

This module implement a switcher service interface and a local implementation. Switch is useful at system runtime to turn on or off some logic or service given certain conditions. For example, the light-4j server won’t stop handling requests but just switching off during server shutdown process. The service registry will be notified but in coming requests are still processed until all clients receives notification from service registry. Read More »

For microservices architecture, a request sent from a client may pass through several services to the backend repository/Book of Record, and then a response is returned in the reverse path. If there is an error in the call tree, we need to identify where the problem is during runtime. Also, for some mission-critical applications, the entire call tree must be in the audit log to meet regulatory compliance requirements, for example, banking applications. Read More »

This module contains some useful classes that are shared by multiple modules within the light-* frameworks. Constants Contains all the constants shared by all modules. ModuleRegistry When the plugin modules are loaded, it will register itself to this module along with configuration. When /server/info is called, the endpoint will return all plugged in modules and their configurations. Util Some useful utility method like uuid generator etc. CollectionUtil Utility for collection Read More »

A Zookeeper registry implementation uses Zookeeper as a registry and discovery server. It implements both registry and discovery in the same module for Zookeeper communication. If the API/server is delivered as a docker image, another product called registrator will be used to register it with Zookeeper server. Otherwise, the server module will be responsible to register itself during startup. Interface Here is the interface of ZooKeeper client. public interface ZooKeeperClient { void subscribeStateChanges(IZkStateListener listener); java. Read More »