{#========================================== Spincast HTTP Caching plugin ==========================================#} {% extends "../../layout.html" %} {% block sectionClasses %}plugins plugins-spincast-http-caching{% endblock %} {% block meta_title %}Plugins - Spincast HTTP Caching{% endblock %} {% block meta_description %}Spincast HTTP Caching plugin : ETag, Cache-Control, etc.{% endblock %} {% block scripts %} {% endblock %} {% block body %}
  1. Plugins
  2. Spincast HTTP Caching plugin

Spincast HTTP Caching plugin

Spincast HTTP Caching plugin

Overview

The Spincast HTTP Caching plugin provides utilities to send and validate cache headers. The main component is the request context add-on, ICacheHeadersRequestContextAddon.

For the full documentation about HTTP caching using Spincast, please have a look at the HTTP caching section.

Installation

If you use the spincast-default artifact, this plugin is already installed so you have nothing more to do!

If you start from scratch using the spincast-core artifact, you can use the plugin by adding this artifact to your project: 

<dependency>
    <groupId>org.spincast</groupId>
    <artifactId>spincast-plugins-http-caching</artifactId>
    <version>{{spincastCurrrentVersion}}</version>
</dependency>

You then install the plugin's Guice module, by passing it to the Guice.createInjector(...) method: 

Injector guice = Guice.createInjector(
        new SpincastCoreGuiceModule(args),
        new SpincastHttpCachingPluginGuiceModule(IAppRequestContext.class, 
                                                 IAppWebsocketContext.class)
        // other modules...
        );

... or by using the install(...) method from your custom Guice module: 

public class AppModule extends SpincastCoreGuiceModule {

    @Override
    protected void configure() {
        super.configure();
        install(new SpincastHttpCachingPluginGuiceModule(getRequestContextType(), 
                                                         getWebsocketContextType()));
        // other modules...
    }
    
    // ...
}

The request context add-on

Quick example :

public void myHandler(IAppRequestContext context) {
    
    // Sends "Cache-Control" header
    context.cacheHeaders().cache(60);
    
    // Validates the "freshness" headers
    if(context.cacheHeaders().eTag(etag).lastModified(date).validate(true)) {
        return;
    } 
}

Methods :

  • ICacheHeadersRequestContextAddon<R> eTag(String currentTag)
    Specifies the current ETag (strong) of the resource.

    A strong comparison will be used to compare the request ETag to this current ETag.

    Skip, or use null if the resource doesn't exist.

  • ICacheHeadersRequestContextAddon<R> eTag(String currentTag, boolean currentTagIsWeak)
    Specifies the current strong or weak ETag of the resource.

    A strong comparison will be used to compare the request ETag to this current ETag.

    Skip, or use null if the resource doesn't exist.

  • ICacheHeadersRequestContextAddon<R> eTag(String currentTag, boolean currentTagIsWeak, boolean weakComparison)
    Specifies the current strong or weak ETag of the resource.

    Skip, or use null if the resource doesn't exist.

    @param weakComparison should a weak comparison be used instead of a strong one to compare the request ETag to the current ETag?
  • ICacheHeadersRequestContextAddon<R> lastModified(Date lastModificationDate)
    Specifies the last modification date of the resource.

    Skip, or use null if the resource doesn't exist.

  • ICacheHeadersRequestContextAddon<R> cache(int seconds)
    The number of seconds the client should cache this resource before requesting it again.
  • ICacheHeadersRequestContextAddon<R> cache(int seconds, boolean isPrivate)
    The number of seconds the client should cache this resource before requesting it again.
    @param isPrivate should the cache be 'private'? (help)
  • ICacheHeadersRequestContextAddon<R> cache(int seconds, boolean isPrivate, Integer secondsCdn)
    The number of seconds the client should cache this resource before requesting it again.
    @param isPrivate should the cache be 'private'? (help)
    @param secondsCdn The number of seconds the resource associated with this route should be cached by a CDN/proxy. If null, it won't be used.
  • ICacheHeadersRequestContextAddon<R> noCache()
    Sends "No Cache" headers so the resource is not cached at all by the client.
  • boolean validate(boolean resourceCurrentlyExists)
    Call this when you are done setting ETag and/or Last-Modified to validate them agains the headers sent by the client.

    If this method returns true, the route handler should return immediately without returning/creating/modifying/deleting the associated resource! Appropriate headers have already been set on the response.

    @param resourceCurrentlyExists Does the resource currently exist?

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