我正在寻找一种在两台服务器之间共享缓存的方法,并且正在研究使用 Redis 作为对象存储缓存策略,但在读取存储值时遇到问题。
当缓存命中为未命中值时,它会成功存储值,但在检索该值时会抛出错误。
所需的对象/属性“muleContext”为 null
据猜测,对象存储缓存策略可能需要一个实现 MuleContextAware 接口的对象存储。
有谁知道这是否正确或如何解决这个问题?
这是示例流程
<mule xmlns:redis="http://www.mulesoft.org/schema/mule/redis" xmlns:ee="http://www.mulesoft.org/schema/mule/ee/core"
xmlns:http="http://www.mulesoft.org/schema/mule/http" xmlns="http://www.mulesoft.org/schema/mule/core" xmlns:doc="http://www.mulesoft.org/schema/mule/documentation" xmlns:spring="http://www.springframework.org/schema/beans" version="EE-3.4.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.mulesoft.org/schema/mule/ee/core http://www.mulesoft.org/schema/mule/ee/core/current/mule-ee.xsd
http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-current.xsd
http://www.mulesoft.org/schema/mule/core http://www.mulesoft.org/schema/mule/core/current/mule.xsd
http://www.mulesoft.org/schema/mule/http http://www.mulesoft.org/schema/mule/http/current/mule-http.xsd
http://www.mulesoft.org/schema/mule/redis http://www.mulesoft.org/schema/mule/redis/3.4/mule-redis.xsd">
<redis:config name="Redis" doc:name="Redis" defaultPartitionName="test" />
<ee:object-store-caching-strategy name="Redis_Caching_Strategy" doc:name="Caching Strategy">
<spring-object-store ref="Redis" />
</ee:object-store-caching-strategy>
<flow name="htmlCacheRedisFlow" doc:name="htmlCacheRedisFlow">
<http:inbound-endpoint exchange-pattern="request-response" host="localhost" port="8084" path="cacheRedis" doc:name="HTTP"/>
<expression-transformer expression="#[payload.substring(payload.lastIndexOf('/') + 1)]" doc:name="Expression"/>
<ee:cache doc:name="Cache" cachingStrategy-ref="Redis_Caching_Strategy" >
<logger message="getting item from db for key #[payload]" level="INFO" doc:name="Logger"/>
<expression-transformer expression="#[payload + 'asd']" doc:name="Expression"/>
</ee:cache>
</flow>
</mule>
正如 David 已经指出的那样,在问题评论中,EE 缓存范围在社区版中不可用。然而,有一些方法可以在社区版中实现缓存。
博客文章使用 Mule ESB 社区版进行企业缓存展示了如何通过添加自定义拦截器来做到这一点。该博客文章使用 ehcache,但您可以修改此示例以使用 Redis。
这篇博文简而言之就是:
<custom-interceptor doc:name="PayloadCache"
class="se.redpill.mulecomponents.cache.PayloadCache">
<spring:property name="cache" ref="MyCache"/>
</custom-interceptor>
和 PayloadCache.java
package se.redpill.mulecomponents.cache;
import net.sf.ehcache.Ehcache;
import net.sf.ehcache.Element;
import org.mule.DefaultMuleEvent;
import org.mule.DefaultMuleMessage;
import org.mule.api.MuleEvent;
import org.mule.api.MuleException;
import org.mule.api.MuleMessage;
import org.mule.api.interceptor.Interceptor;
import org.mule.api.processor.MessageProcessor;
/**
* A mule interceptor acting as a ehCache component.
* Based on the Cache interceptor blueprint from Mule In Action by David Dossot and John D'Emic,
*
*/
public class PayloadCache implements Interceptor
{
private MessageProcessor next;
private Ehcache cache;
public void setListener(MessageProcessor listener)
{
next = listener;
}
public void setCache(final Ehcache cache)
{
this.cache = cache;
}
public MuleEvent process(MuleEvent event) throws MuleException
{
final MuleMessage currentMessage = event.getMessage();
final Object key = currentMessage.getPayload();
final Element cachedElement = cache.get(key);
if (cachedElement != null)
{
return new DefaultMuleEvent(new DefaultMuleMessage(cachedElement.getObjectValue(),
currentMessage, event.getMuleContext()), event);
}
final MuleEvent result = next.process(event);
cache.put(new Element(key, result.getMessage().getPayload()));
return result;
}
}
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