Deutsche Anleitung zum Starten des Beispiels
For Self-contained Systems multiple frontends need to be integrated. This sample shows how to do this. Varnish serves as a cache and also ESI (Edge Side Includes) are used to integrate multiple backends into one HTTP site.
This project creates a Docker setup with the complete systems based on Docker Compose and Docker Machine. The services are implemented in Java using Spring and Spring Cloud.
It uses two very simple SCS:
See How to run for details.
The SCS are:
esi:include
in its HTML files to include the HTML snippets of
scs-demo-esi-common
. These are interpreted by the Varnish web
cache. This microservices is written in Java. It has an Java main application
in src/test/java
to run the microservice stand alone with some test data. However, the layout
of the web page will be incomplete because the ESI includes are not handled.Varnish interprets the ESIs. The default.vcl
in the directory
docker/varnish
includes the configuration to enable this. It
defines two backends - one for each SCS. HTTP requests to /catalog
are mapped to the catalog SCS while the default is the order
SCS. The time to live for each item in the cache is 30s i.e. after
30 seconds an entry in the cache in invalidated and the call goes to
the backend. The grace is 15m: Even if the entry in the cache is
invalid it will be served for 15 more minutes of the backend is not
accessible. So if the backend crashes the cache can still provide
some resilience.
This is a technology demo. The coupling between the two components in this case is very tight - the integration is providing rather small components that are embedded in specific pages. In a real world architecture this should not be the case. Please refer to http://scs-architecture.org/ to better understand the architecture this should support.