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input stream must be closed only after reading results
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GordeaS authored and GordeaS committed Jul 19, 2024
1 parent b6495c9 commit 4486be2
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377 changes: 198 additions & 179 deletions ...n/src/main/java/eu/europeana/annotation/dereferenciation/MetisDereferenciationClient.java
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Original file line number Diff line number Diff line change
Expand Up @@ -43,196 +43,215 @@
value = {"classpath:annotation.properties", "classpath:config/annotation.user.properties"},
ignoreResourceNotFound = true)
public class MetisDereferenciationClient implements InitializingBean {

private static final Logger LOG = LogManager.getLogger(MetisDereferenciationClient.class);

@Value("${metis.baseUrl}")
private String baseUrl;
@Value("${metis.connection.retries:3}")
private int connRetries;
@Value("${metis.connection.timeout:30000}")
private int connTimeout;

static final String XSLT_TRANSFORMATION_FILE = "/deref2json.xsl";
static final String PARAM_URI = "uri";
static final String PARAM_LANGS = "langs";
Transformer transformer;
private HttpConnection httpConnection;

public void afterPropertiesSet() throws Exception {
synchronized(this) {
if(StringUtils.isBlank(baseUrl)) {
throw new AnnotationDereferenciationException(new RuntimeException("Metis baseUrl cannot be null or empty."));
}

httpConnection = new HttpConnection(connRetries,connTimeout);

TransformerFactory factory = TransformerFactory.newInstance();
InputStream xslFileAsStream = new ClassPathResource(XSLT_TRANSFORMATION_FILE).getInputStream();
StreamSource xslSource = new StreamSource(xslFileAsStream);
Templates templates = factory.newTemplates(xslSource);
transformer = templates.newTransformer();

private static final Logger LOG = LogManager.getLogger(MetisDereferenciationClient.class);

@Value("${metis.baseUrl}")
private String baseUrl;
@Value("${metis.connection.retries:3}")
private int connRetries;
@Value("${metis.connection.timeout:30000}")
private int connTimeout;

static final String XSLT_TRANSFORMATION_FILE = "/deref2json.xsl";
static final String PARAM_URI = "uri";
static final String PARAM_LANGS = "langs";
Transformer transformer;
private HttpConnection httpConnection;

public void afterPropertiesSet() throws Exception {
synchronized (this) {
if (StringUtils.isBlank(baseUrl)) {
throw new AnnotationDereferenciationException(
new RuntimeException("Metis baseUrl cannot be null or empty."));
}

httpConnection = new HttpConnection(connRetries, connTimeout);

TransformerFactory factory = TransformerFactory.newInstance();
InputStream xslFileAsStream =
new ClassPathResource(XSLT_TRANSFORMATION_FILE).getInputStream();
StreamSource xslSource = new StreamSource(xslFileAsStream);
Templates templates = factory.newTemplates(xslSource);
transformer = templates.newTransformer();
}

/**
* This method encodes URLs for HTTP connection
*
* @param url The input URL
* @return encoded URL
* @throws UnsupportedEncodingException
*/
String encodeUrl(String url) {
return URLEncoder.encode(url, StandardCharsets.UTF_8);
}
}

/**
* This method encodes URLs for HTTP connection
*
* @param url The input URL
* @return encoded URL
* @throws UnsupportedEncodingException
*/
String encodeUrl(String url) {
return URLEncoder.encode(url, StandardCharsets.UTF_8);
}

/**
* This method applies the XSLT to the XML output for each of the URIs in the
* list and fills the map with the URI and JSON string. It sends GET HTTP
* request to dereference URI.
*
* @param uris The list of query URIs. The URI is composed from the base URI
* to Metis API completed with query URI from the entity.
* @param language e.g.
* "en,pl,de,nl,fr,it,da,sv,el,fi,hu,cs,sl,et,pt,es,lt,lv,bg,ro,sk,hr,ga,mt,no,ca,ru"
* @return response from Metis API in JSON-LD format
*/
public Map<String, String> dereferenceOne(String uri, String language) {
Map<String, String> res = new HashMap<String, String>();
String jsonLdStr;
InputStream streamResponse=null;

try {
HttpURL metisRequestUrl = new HttpURL(baseUrl);
metisRequestUrl.setQuery(PARAM_URI, uri);
streamResponse = httpConnection.getURLContentAsStream(metisRequestUrl.toString());
if(streamResponse==null) {
throw new UpstreamServerErrorRuntimeException("MetisDereferenciationClient invalid status code or response not available.");
}
jsonLdStr = convertToJsonLd(uri, streamResponse, language).toString();
res.put(uri, jsonLdStr);
} catch (UpstreamServerErrorRuntimeException ex) {
throw ex;
} catch (IOException ex) {//comes from the httpConnection.getURLContentAsStream
throw new UpstreamServerErrorRuntimeException("MetisDereferenciationClient I/O (transport) problem while obtaining the response body.", ex);
} catch (RuntimeException ex) {
throw new AnnotationDereferenciationException(ex);
} finally {
if (streamResponse != null) {
try {
streamResponse.close();
} catch (IOException e) {
if (LOG.isWarnEnabled()) {
LOG.warn("Unexpected exception occured when trying to close metis input stream", e);
}
/**
* This method applies the XSLT to the XML output for each of the URIs in the list and fills the
* map with the URI and JSON string. It sends GET HTTP request to dereference URI.
*
* @param uris The list of query URIs. The URI is composed from the base URI to Metis API
* completed with query URI from the entity.
* @param language e.g.
* "en,pl,de,nl,fr,it,da,sv,el,fi,hu,cs,sl,et,pt,es,lt,lv,bg,ro,sk,hr,ga,mt,no,ca,ru"
* @return response from Metis API in JSON-LD format
*/
public Map<String, String> dereferenceOne(String uri, String language) {
Map<String, String> res = new HashMap<String, String>();
String jsonLdStr;
InputStream streamResponse = null;

try {
HttpURL metisRequestUrl = new HttpURL(baseUrl);
metisRequestUrl.setQuery(PARAM_URI, uri);
streamResponse = httpConnection.getURLContentAsStream(metisRequestUrl.toString());
if (streamResponse == null) {
throw new UpstreamServerErrorRuntimeException(
"MetisDereferenciationClient invalid status code or response not available.");
}
jsonLdStr = convertToJsonLd(uri, streamResponse, language).toString();
res.put(uri, jsonLdStr);
} catch (UpstreamServerErrorRuntimeException ex) {
throw ex;
} catch (IOException ex) {// comes from the httpConnection.getURLContentAsStream
throw new UpstreamServerErrorRuntimeException(
"MetisDereferenciationClient I/O (transport) problem while obtaining the response body.",
ex);
} catch (RuntimeException ex) {
throw new AnnotationDereferenciationException(ex);
} finally {
if (streamResponse != null) {
try {
streamResponse.close();
} catch (IOException e) {
if (LOG.isWarnEnabled()) {
LOG.warn("Unexpected exception occured when trying to close metis input stream", e);
}
}
}


return res;
}
}

/**
* This method applies the XSLT to the XML output for each of the URIs in the
* list and fills the map with the URI and JSON string. It sends GET HTTP
* request to dereference URI.
*
* @param uris The list of query URIs. The URI is composed from the base URI
* to Metis API completed with query URI from the entity.
* @param language e.g.
* "en,pl,de,nl,fr,it,da,sv,el,fi,hu,cs,sl,et,pt,es,lt,lv,bg,ro,sk,hr,ga,mt,no,ca,ru"
* @return response from Metis API in JSON-LD format
*/
public Map<String, String> dereferenceMany(List<String> uris, String language) {
Map<String, String> res = new HashMap<String, String>();
String jsonLdStr;
InputStream streamResponse=null;
try {
@SuppressWarnings({ "rawtypes", "unchecked" })
String urisJson = JsonSerializer.toString((List)uris);
streamResponse = httpConnection.postRequest(baseUrl, urisJson);
if(streamResponse==null) {
throw new UpstreamServerErrorRuntimeException("MetisDereferenciationClient invalid status code or response not available.");
}
String[] urisArray = new String[uris.size()];
urisArray = uris.toArray(urisArray);
jsonLdStr = convertToJsonLd(urisArray, streamResponse, language).toString();
//we need to separate the individual jsons manually
List<Integer> startingPositions = findSubstringIndexes(jsonLdStr, "{ \"@context\":");
for (int i = 0; i < startingPositions.size(); i++) {
if(i==startingPositions.size()-1) {
res.put(uris.get(i), jsonLdStr.substring(startingPositions.get(i), jsonLdStr.length()));
}
else {
res.put(uris.get(i), jsonLdStr.substring(startingPositions.get(i), startingPositions.get(i+1)));

return res;
}

/**
* This method applies the XSLT to the XML output for each of the URIs in the list and fills the
* map with the URI and JSON string. It sends GET HTTP request to dereference URI.
*
* @param uris The list of query URIs. The URI is composed from the base URI to Metis API
* completed with query URI from the entity.
* @param language e.g.
* "en,pl,de,nl,fr,it,da,sv,el,fi,hu,cs,sl,et,pt,es,lt,lv,bg,ro,sk,hr,ga,mt,no,ca,ru"
* @return response from Metis API in JSON-LD format
*/
public Map<String, String> dereferenceMany(List<String> uris, String language) {
Map<String, String> res = new HashMap<String, String>();
String jsonLdStr;
InputStream streamResponse = null;
try {
@SuppressWarnings({"rawtypes", "unchecked"})
String urisJson = JsonSerializer.toString((List) uris);
streamResponse = httpConnection.postRequest(baseUrl, urisJson);
if (streamResponse == null) {
throw new UpstreamServerErrorRuntimeException(
"MetisDereferenciationClient invalid status code or response not available.");
}
String[] urisArray = new String[uris.size()];
urisArray = uris.toArray(urisArray);
jsonLdStr = convertToJsonLd(urisArray, streamResponse, language).toString();
// we need to separate the individual jsons manually
List<Integer> startingPositions = findSubstringIndexes(jsonLdStr, "{ \"@context\":");
for (int i = 0; i < startingPositions.size(); i++) {
if (i == startingPositions.size() - 1) {
res.put(uris.get(i), jsonLdStr.substring(startingPositions.get(i), jsonLdStr.length()));
} else {
res.put(uris.get(i),
jsonLdStr.substring(startingPositions.get(i), startingPositions.get(i + 1)));
}
}
} catch (UpstreamServerErrorRuntimeException ex) {
throw ex;
} catch (IOException ex) {// comes from the httpConnection.postRequest
throw new UpstreamServerErrorRuntimeException(
"MetisDereferenciationClient I/O (transport) problem while obtaining the response body.",
ex);
} catch (RuntimeException ex) {
throw new AnnotationDereferenciationException(ex);
} finally {
if (streamResponse != null) {
try {
streamResponse.close();
} catch (IOException e) {
if (LOG.isWarnEnabled()) {
LOG.warn("Unexpected exception occured when trying to close metis input stream", e);
}
}
} catch (UpstreamServerErrorRuntimeException ex) {
throw ex;
} catch (IOException ex) {//comes from the httpConnection.postRequest
throw new UpstreamServerErrorRuntimeException("MetisDereferenciationClient I/O (transport) problem while obtaining the response body.", ex);
} catch(RuntimeException ex) {
throw new AnnotationDereferenciationException(ex);
}
return res;
}
}
}

/**
* This method need to be moved to utils.
*
* This method finds all indexes of a substring within a string, e.g. for the substring "abc"
* within a string "abcdefabc abc dejjabc", the output will be [0,6,10,18].
* @param input
* @param substring
* @return
*/
private List<Integer> findSubstringIndexes(String input, String substring) {
List<Integer> indexes = new ArrayList<>();
int substringLength = substring.length();
int index = input.indexOf(substring, 0);
if(index!=-1) {
indexes.add(index);
while(index != -1){
index = input.indexOf(substring, index + substringLength);
if (index != -1) {
indexes.add(index);
}


return res;
}

/**
* This method need to be moved to utils.
*
* This method finds all indexes of a substring within a string, e.g. for the substring "abc"
* within a string "abcdefabc abc dejjabc", the output will be [0,6,10,18].
*
* @param input
* @param substring
* @return
*/
private List<Integer> findSubstringIndexes(String input, String substring) {
List<Integer> indexes = new ArrayList<>();
int substringLength = substring.length();
int index = input.indexOf(substring, 0);
if (index != -1) {
indexes.add(index);
while (index != -1) {
index = input.indexOf(substring, index + substringLength);
if (index != -1) {
indexes.add(index);
}
}
return indexes;
}
}

/**
* An XSLT converts dereference output to JSON-LD.
*
* @param response
* @param language e.g.
* "en,pl,de,nl,fr,it,da,sv,el,fi,hu,cs,sl,et,pt,es,lt,lv,bg,ro,sk,hr,ga,mt,no,ca,ru"
* @return dereferenced output in JSON-LD format
*/
public StringWriter convertToJsonLd(Object uris, InputStream response, String language) {

StringWriter result = new StringWriter();
try {
//reuse transformer but update params
transformer.clearParameters();
transformer.setParameter(PARAM_URI, uris);
if (language != null) {
transformer.setParameter(PARAM_LANGS, language);
}
StreamSource text = new StreamSource(response);
transformer.transform(text, new StreamResult(result));
} catch (TransformerConfigurationException e) {
throw new AnnotationDereferenciationException(
"Unexpected exception occured when invoking the MetisDereferenciationClient convertDereferenceOutputToJsonLd method",
e);
} catch (TransformerException e) {
throw new AnnotationDereferenciationException(
"Exception occured when invoking the MetisDereferenciationClient convertDereferenceOutputToJsonLd method",
e);
}
return result;
return indexes;
}

/**
* An XSLT converts dereference output to JSON-LD.
*
* @param response
* @param language e.g.
* "en,pl,de,nl,fr,it,da,sv,el,fi,hu,cs,sl,et,pt,es,lt,lv,bg,ro,sk,hr,ga,mt,no,ca,ru"
* @return dereferenced output in JSON-LD format
*/
public StringWriter convertToJsonLd(Object uris, InputStream response, String language) {

StringWriter result = new StringWriter();
try {
// reuse transformer but update params
transformer.clearParameters();
transformer.setParameter(PARAM_URI, uris);
if (language != null) {
transformer.setParameter(PARAM_LANGS, language);
}
StreamSource text = new StreamSource(response);
transformer.transform(text, new StreamResult(result));
} catch (TransformerConfigurationException e) {
throw new AnnotationDereferenciationException(
"Unexpected exception occured when invoking the MetisDereferenciationClient convertDereferenceOutputToJsonLd method",
e);
} catch (TransformerException e) {
throw new AnnotationDereferenciationException(
"Exception occured when invoking the MetisDereferenciationClient convertDereferenceOutputToJsonLd method",
e);
}
return result;
}

}
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