我收到以下XML SOAP响应作为来自Web服务的响应
<S:Envelope xmlns:env="http://www.w3.org/2003/05/soap-envelope" xmlns:S="http://www.w3.org/2003/05/soap-envelope">
<env:Header/>
<S:Body>
<searchResults xsi:schemaLocation="http://eur-lex.europa.eu/search http://eur-lex.europa.eu/eurlex-ws?xsd=3" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://eur-lex.europa.eu/search" xmlns:searchLayerHelper="xalan//eu.europa.ec.op.searchlayer.domain.util.SearchLayerHelper">
<numhits>1</numhits>
<totalhits>16738</totalhits>
<page>1</page>
<language>en</language>
<result>
<reference>eng_cellar:9462de2e-80bd-4433-bd97-3465ce7804da_en</reference>
<rank>1</rank>
<content>
<NOTICE>
<EXPRESSION>
<EXPRESSION_TITLE>
<VALUE>Judgment of the Court (Second Chamber) of 8 December 2011. # KME Germany AG, KME France SAS and KME Italy SpA v European Commission. # Appeal - Competition - Agreements, decisions and concerted practices - Market for copper industrial tubes - Fines - Size of the market, duration of the infringement and cooperation capable of being taken into consideration - Effective judicial remedy. # Case C-272/09 P.</VALUE>
</EXPRESSION_TITLE>
<EXPRESSION_USES_LANGUAGE>
<URI>
<IDENTIFIER>ENG</IDENTIFIER>
</URI>
</EXPRESSION_USES_LANGUAGE>
</EXPRESSION>
<MANIFESTATION>
<MANIFESTATION_COURT-REPORT_PART_PAGE_FIRST>
<VALUE>00000</VALUE>
</MANIFESTATION_COURT-REPORT_PART_PAGE_FIRST>
<MANIFESTATION_COURT-REPORT_PART_TYPE>
<VALUE>RJ</VALUE>
</MANIFESTATION_COURT-REPORT_PART_TYPE>
<MANIFESTATION_COURT-REPORT_PART_YEAR>
<VALUE>2011</VALUE>
</MANIFESTATION_COURT-REPORT_PART_YEAR>
</MANIFESTATION>
<WORK>
<ECLI>
<VALUE>ECLI:EU:C:2011:810</VALUE>
</ECLI>
<ID_CELEX>
<VALUE>62009CJ0272</VALUE>
</ID_CELEX>
<WORK_CREATED_BY_AGENT>
<COMPACT_URI>corporate-body:CJ</COMPACT_URI>
<IDENTIFIER>CJ</IDENTIFIER>
<OP-CODE>CJ</OP-CODE>
<PREFLABEL>Court of Justice</PREFLABEL>
<URI>
<IDENTIFIER>CJ</IDENTIFIER>
<TYPE>corporate-body</TYPE>
<VALUE>http://publications.europa.eu/resource/authority/corporate-body/CJ</VALUE>
</URI>
</WORK_CREATED_BY_AGENT>
<WORK_DATE_DOCUMENT>
<DAY>08</DAY>
<MONTH>12</MONTH>
<YEAR>2011</YEAR>
</WORK_DATE_DOCUMENT>
<WORK_HAS_EXPRESSION>
<EMBEDDED_NOTICE>
<EXPRESSION>
<EXPRESSION_USES_LANGUAGE>
<OP-CODE>CES</OP-CODE>
</EXPRESSION_USES_LANGUAGE>
</EXPRESSION>
</EMBEDDED_NOTICE>
</WORK_HAS_EXPRESSION>
<WORK_HAS_EXPRESSION>
<EMBEDDED_NOTICE>
<EXPRESSION>
<EXPRESSION_USES_LANGUAGE>
<OP-CODE>SPA</OP-CODE>
</EXPRESSION_USES_LANGUAGE>
</EXPRESSION>
</EMBEDDED_NOTICE>
</WORK_HAS_EXPRESSION>
<WORK_HAS_EXPRESSION>
<EMBEDDED_NOTICE>
<EXPRESSION>
<EXPRESSION_USES_LANGUAGE>
<OP-CODE>ENG</OP-CODE>
</EXPRESSION_USES_LANGUAGE>
</EXPRESSION>
</EMBEDDED_NOTICE>
</WORK_HAS_EXPRESSION>
<WORK_HAS_EXPRESSION>
<EMBEDDED_NOTICE>
<EXPRESSION>
<EXPRESSION_USES_LANGUAGE>
<OP-CODE>HRV</OP-CODE>
</EXPRESSION_USES_LANGUAGE>
</EXPRESSION>
</EMBEDDED_NOTICE>
</WORK_HAS_EXPRESSION>
<WORK_HAS_EXPRESSION>
<EMBEDDED_NOTICE>
<EXPRESSION>
<EXPRESSION_USES_LANGUAGE>
<OP-CODE>MLT</OP-CODE>
</EXPRESSION_USES_LANGUAGE>
</EXPRESSION>
</EMBEDDED_NOTICE>
</WORK_HAS_EXPRESSION>
<WORK_HAS_EXPRESSION>
<EMBEDDED_NOTICE>
<EXPRESSION>
<EXPRESSION_USES_LANGUAGE>
<OP-CODE>ELL</OP-CODE>
</EXPRESSION_USES_LANGUAGE>
</EXPRESSION>
</EMBEDDED_NOTICE>
</WORK_HAS_EXPRESSION>
<WORK_HAS_EXPRESSION>
<EMBEDDED_NOTICE>
<EXPRESSION>
<EXPRESSION_USES_LANGUAGE>
<OP-CODE>DAN</OP-CODE>
</EXPRESSION_USES_LANGUAGE>
</EXPRESSION>
</EMBEDDED_NOTICE>
</WORK_HAS_EXPRESSION>
<WORK_HAS_EXPRESSION>
<EMBEDDED_NOTICE>
<EXPRESSION>
<EXPRESSION_USES_LANGUAGE>
<OP-CODE>SWE</OP-CODE>
</EXPRESSION_USES_LANGUAGE>
</EXPRESSION>
</EMBEDDED_NOTICE>
</WORK_HAS_EXPRESSION>
<WORK_HAS_EXPRESSION>
<EMBEDDED_NOTICE>
<EXPRESSION>
<EXPRESSION_USES_LANGUAGE>
<OP-CODE>FRA</OP-CODE>
</EXPRESSION_USES_LANGUAGE>
</EXPRESSION>
</EMBEDDED_NOTICE>
</WORK_HAS_EXPRESSION>
<WORK_HAS_EXPRESSION>
<EMBEDDED_NOTICE>
<EXPRESSION>
<EXPRESSION_USES_LANGUAGE>
<OP-CODE>BUL</OP-CODE>
</EXPRESSION_USES_LANGUAGE>
</EXPRESSION>
</EMBEDDED_NOTICE>
</WORK_HAS_EXPRESSION>
<WORK_HAS_EXPRESSION>
<EMBEDDED_NOTICE>
<EXPRESSION>
<EXPRESSION_USES_LANGUAGE>
<OP-CODE>POL</OP-CODE>
</EXPRESSION_USES_LANGUAGE>
</EXPRESSION>
</EMBEDDED_NOTICE>
</WORK_HAS_EXPRESSION>
<WORK_HAS_EXPRESSION>
<EMBEDDED_NOTICE>
<EXPRESSION>
<EXPRESSION_USES_LANGUAGE>
<OP-CODE>RON</OP-CODE>
</EXPRESSION_USES_LANGUAGE>
</EXPRESSION>
</EMBEDDED_NOTICE>
</WORK_HAS_EXPRESSION>
<WORK_HAS_EXPRESSION>
<EMBEDDED_NOTICE>
<EXPRESSION>
<EXPRESSION_USES_LANGUAGE>
<OP-CODE>LIT</OP-CODE>
</EXPRESSION_USES_LANGUAGE>
</EXPRESSION>
</EMBEDDED_NOTICE>
</WORK_HAS_EXPRESSION>
<WORK_HAS_EXPRESSION>
<EMBEDDED_NOTICE>
<EXPRESSION>
<EXPRESSION_USES_LANGUAGE>
<OP-CODE>SLV</OP-CODE>
</EXPRESSION_USES_LANGUAGE>
</EXPRESSION>
</EMBEDDED_NOTICE>
</WORK_HAS_EXPRESSION>
<WORK_HAS_EXPRESSION>
<EMBEDDED_NOTICE>
<EXPRESSION>
<EXPRESSION_USES_LANGUAGE>
<OP-CODE>NLD</OP-CODE>
</EXPRESSION_USES_LANGUAGE>
</EXPRESSION>
</EMBEDDED_NOTICE>
</WORK_HAS_EXPRESSION>
<WORK_HAS_EXPRESSION>
<EMBEDDED_NOTICE>
<EXPRESSION>
<EXPRESSION_USES_LANGUAGE>
<OP-CODE>FIN</OP-CODE>
</EXPRESSION_USES_LANGUAGE>
</EXPRESSION>
</EMBEDDED_NOTICE>
</WORK_HAS_EXPRESSION>
<WORK_HAS_EXPRESSION>
<EMBEDDED_NOTICE>
<EXPRESSION>
<EXPRESSION_USES_LANGUAGE>
<OP-CODE>DEU</OP-CODE>
</EXPRESSION_USES_LANGUAGE>
</EXPRESSION>
</EMBEDDED_NOTICE>
</WORK_HAS_EXPRESSION>
<WORK_HAS_EXPRESSION>
<EMBEDDED_NOTICE>
<EXPRESSION>
<EXPRESSION_USES_LANGUAGE>
<OP-CODE>LAV</OP-CODE>
</EXPRESSION_USES_LANGUAGE>
</EXPRESSION>
</EMBEDDED_NOTICE>
</WORK_HAS_EXPRESSION>
<WORK_HAS_EXPRESSION>
<EMBEDDED_NOTICE>
<EXPRESSION>
<EXPRESSION_USES_LANGUAGE>
<OP-CODE>POR</OP-CODE>
</EXPRESSION_USES_LANGUAGE>
</EXPRESSION>
</EMBEDDED_NOTICE>
</WORK_HAS_EXPRESSION>
<WORK_HAS_EXPRESSION>
<EMBEDDED_NOTICE>
<EXPRESSION>
<EXPRESSION_USES_LANGUAGE>
<OP-CODE>HUN</OP-CODE>
</EXPRESSION_USES_LANGUAGE>
</EXPRESSION>
</EMBEDDED_NOTICE>
</WORK_HAS_EXPRESSION>
<WORK_HAS_EXPRESSION>
<EMBEDDED_NOTICE>
<EXPRESSION>
<EXPRESSION_USES_LANGUAGE>
<OP-CODE>SLK</OP-CODE>
</EXPRESSION_USES_LANGUAGE>
</EXPRESSION>
</EMBEDDED_NOTICE>
</WORK_HAS_EXPRESSION>
<WORK_HAS_EXPRESSION>
<EMBEDDED_NOTICE>
<EXPRESSION>
<EXPRESSION_USES_LANGUAGE>
<OP-CODE>ITA</OP-CODE>
</EXPRESSION_USES_LANGUAGE>
</EXPRESSION>
</EMBEDDED_NOTICE>
</WORK_HAS_EXPRESSION>
<WORK_HAS_EXPRESSION>
<EMBEDDED_NOTICE>
<EXPRESSION>
<EXPRESSION_USES_LANGUAGE>
<OP-CODE>EST</OP-CODE>
</EXPRESSION_USES_LANGUAGE>
</EXPRESSION>
</EMBEDDED_NOTICE>
</WORK_HAS_EXPRESSION>
<WORK_HAS_RESOURCE-TYPE>
<IDENTIFIER>JUDG</IDENTIFIER>
<OP-CODE>JUDG</OP-CODE>
<PREFLABEL>Judgment</PREFLABEL>
<URI>
<IDENTIFIER>JUDG</IDENTIFIER>
<TYPE>resource-type</TYPE>
<VALUE>http://publications.europa.eu/resource/authority/resource-type/JUDG</VALUE>
</URI>
</WORK_HAS_RESOURCE-TYPE>
</WORK>
</NOTICE>
</content>
</result>
</searchResults>
</S:Body>
</S:Envelope>
我想要做的是使用XPath表达式获取ID_CELEX元素。我正在使用XML库，到目前为止我已经完成了以下操作：
# h is the basicTextGatherer that gets updated after running curlPerform to the webservice
# we can also directly parse the provided XML as string
doc <- xmlTreeParse(h$value(), asText = T, useInternalNodes = T)
r <- xmlRoot(doc)
getNodeSet(r, '//ID_CELEX')
# returns
# list()
# attr(,"class")
# [1] "XMLNodeSet"
似乎有ID_CELEX元素的命名空间，但我不清楚
答案 0 :(得分：2)
ID_CELEX元素位于http://eur-lex.europa.eu/search命名空间中，因此您应该使用命名空间前缀：
getNodeSet(r, "//r:ID_CELEX", c(r = "http://eur-lex.europa.eu/search"))
输出
[[1]]
<ID_CELEX>
<VALUE>62009CJ0272</VALUE>
</ID_CELEX>
attr(,"class")
[1] "XMLNodeSet"