如何缓存数据库查询结果并避免缓存处理 mule 消息而不考虑传入请求？

Question

我正在从数据库中缓存第三方 API URL 并且此 URL 必须被后续传入的消息用于访问第三方系统。

目前，每当我对传入的请求进行任何更改时，URL 就会再次从数据库中加载，当再次发送相同的请求时，URL 就会从缓存中获取。

但我希望 URL 首次加载，然后无论传入请求中的内容如何，都应从缓存中获取。

请告诉我怎么做？

骡子XML:

<http:listener-config name="HTTP_Listener_Configuration" host="localhost" port="8081" doc:name="HTTP Listener Configuration"/>
<http:request-config name="HTTP_Request_Configuration" host="lcdre342.cdr-p01.chp.bankofamerica.com" port="20108" basePath="/ngen/AdministerAccountRelationshipManagement/V001/administer-accounts" doc:name="HTTP Request Configuration"/>
<http:request-config name="HTTP_Outgoing_Request" host="#[sessionVars.api_url]" port="${mule.env.port}" doc:name="HTTP Request Configuration"/>
<context:property-placeholder location="${mule.env}.properties"/>
<db:generic-config name="Generic_Database_Configuration" url="jdbc:db2://db2dvipa9sd92t.bankofamerica.com:446/D92T:user=${mule.env.dbuserName};password=${mule.env.dbPassword};" driverClassName="com.ibm.db2.jcc.DB2Driver" doc:name="Generic Database Configuration"/>
<ee:object-store-caching-strategy name="API_Url_cache" doc:name="Caching Strategy">
    <managed-store storeName="API URL Managed Store" persistent="true" maxEntries="1" entryTTL="600000" expirationInterval="6000"/>
</ee:object-store-caching-strategy>
<flow name="ringfencedemoFlow">
    <http:listener config-ref="HTTP_Listener_Configuration" path="/administer-accounts" allowedMethods="POST" doc:name="HTTP">
        <http:response-builder statusCode="#[message.inboundProperties.'http.status']" reasonPhrase="#[message.inboundProperties.'http.reason']">
            <http:header headerName="x-boa-site-affinity" value="#[message.inboundProperties.'x-boa-site-affinity']"/>
            <http:header headerName="x-boa-site-affinity-wcc" value="#[message.inboundProperties.'x-boa-site-affinity-wcc']"/>
            <http:header headerName="x-boa-trace-id" value="#[message.inboundProperties.'x-boa-trace-id']"/>
        </http:response-builder>
    </http:listener>
    <object-to-string-transformer doc:name="Object to String"/>
    <logger message="#[payload]" level="INFO" doc:name="Input Request Logger"/>
    <set-variable variableName="inputMsg" value="#[payload]" doc:name="Put input request into variable"/>
    <ee:cache doc:name="Cache" cachingStrategy-ref="API_Url_cache" filterExpression="#[payload.isEmpty() == false]">
        <db:select config-ref="Generic_Database_Configuration" doc:name="Get API url from DB">
            <db:parameterized-query><![CDATA[select data_value from ${mule.env.schemavalue}.XWCCSYSPARM where GROUPREFID='WCCD' and CATEGORY='MULE' and KEY_ID='WCC_API_URL' and SEQ_NUM=0]]></db:parameterized-query>
        </db:select>
    </ee:cache>
    <set-session-variable variableName="api_url" value="#[payload.get(0).DATA_VALUE]" encoding="UTF-8" mimeType="text/plain" doc:name="Set Api url in session variable"/>
    <set-payload value="#[flowVars.inputMsg]" encoding="UTF-8" mimeType="application/xml" doc:name="Set back input request in payload"/>
    <http:request config-ref="HTTP_Outgoing_Request" path="${mule.env.path}" method="POST" doc:name="Call to WCC System">
        <http:request-builder>
            <http:header headerName="x-boa-user-id" value="#[message.inboundProperties.'x-boa-user-id']"/>
            <http:header headerName="X-BOA-Trace-ID" value="#[message.inboundProperties.'X-BOA-Trace-ID']"/>
            <http:header headerName="X-BOA-RDS-Auth-ChannelId" value="#[message.inboundProperties.'X-BOA-RDS-Auth-ChannelId']"/>
            <http:header headerName="X-BOA-RDS-Auth-AppId" value="#[message.inboundProperties.'X-BOA-RDS-Auth-AppId']"/>
            <http:header headerName="X-BOA-Security-Token" value="#[message.inboundProperties.'X-BOA-Security-Token']"/>
            <http:header headerName="X-BOA-User-ID-Type" value="#[message.inboundProperties.'X-BOA-User-ID-Type']"/>
            <http:header headerName="X-BOA-Originator-Component" value="#[message.inboundProperties.'X-BOA-Originator-Component']"/>
        </http:request-builder>
        <http:success-status-code-validator values="200,400,207"/>
    </http:request>
    <object-to-string-transformer doc:name="Object to String"/>
   <!--  <component doc:name="PrettyPrintXML" class="org.boa.format.PrettyPrintXML"/> -->
    <logger message="#[payload]" level="INFO" doc:name="Response logger"/>
</flow>

Answer 1

您需要在 caching-strategy 上设置 keyGenerationExpression 属性，如下所示：

<ee:object-store-caching-strategy name="API_Url_cache" doc:name="Caching Strategy"
keyGenerationExpression="#[flowVars.someConstantVariable]">
   <managed-store storeName="API URL Managed Store" persistent="true" maxEntries="1" entryTTL="600000" expirationInterval="6000"/>
</ee:object-store-caching-strategy>

缓存条目根据生成的键存储在缓存中。下次执行缓存范围时，新生成的键与存储的键匹配，以确定它是缓存命中还是缓存未命中。

在你的情况下，Mule 的默认密钥生成器生成的密钥对于每个消息请求可能是唯一的。因此每次都执行缓存范围。

来自 https://docs.mulesoft.com/mule-user-guide/v/3.8/cache-scope -

常量密钥生成的几个示例：

// Generates same key whenever payload is not empty
keyGenerationExpression="#[!payload.isEmpty()]" 

// Generates same key for a calendar month
keyGenerationExpression="#[server.dateTime.month]"

HTH.

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