WIP SRUopener

Author: dr0i

metafacture-biblio/src/main/java/org/metafacture/biblio/SruOpener.java

@@ -0,0 +1,185 @@
+/* Copyright 2013 Pascal Christoph.
+ * Licensed under the Eclipse Public License 1.0 */
+
+package org.metafacture.biblio;
+
+import org.metafacture.framework.FluxCommand;
+import org.metafacture.framework.MetafactureException;
+import org.metafacture.framework.ObjectReceiver;
+import org.metafacture.framework.annotations.Description;
+import org.metafacture.framework.annotations.In;
+import org.metafacture.framework.annotations.Out;
+import org.metafacture.framework.helpers.DefaultObjectPipe;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.io.Reader;
+import java.net.HttpURLConnection;
+import java.net.URL;
+
+/**
+ * Opens an SRU (Search Retrieval by URL) stream and passes a reader to the receiver.
+ * The input should be the base URL of the SRU service to be retrieved from.
+ *
+ * @author Pascal Christoph (dr0i)
+ */
+@Description("Opens a SRU stream and passes a reader to the receiver. The input should be the base URL of the SRU service to be retrieved from. Mandatory argument is: QUERY.")
+@In(String.class)
+@Out(Reader.class)
+@FluxCommand("open-sru")
+public final class SruOpener extends DefaultObjectPipe<String, ObjectReceiver<Reader>> {
+
+    private static final String OPERATION = "searchRetrieve";
+    private static final String RECORD_SCHEMA = "MARC21-xml";
+    private static final String USER_AGENT = "";
+    private static final String VERSION = "2.0";
+
+    private static final int CONNECTION_TIMEOUT = 11000;
+    private static final int MAXIMUM_RECORDS = 10;
+    private static final int START_RECORD = 1;
+    private static final int TOTAL = 10;
+
+    private String operation = OPERATION;
+    private String query;
+    private String recordSchema = RECORD_SCHEMA;
+    private String userAgent = USER_AGENT;
+    private String version = VERSION;
+
+    private int maximumRecords = MAXIMUM_RECORDS;
+    private int startRecord = START_RECORD;
+    private int totalRecords = TOTAL;
+
+
+    /**
+     * Creates an instance of {@link SruOpener}
+     */
+    public SruOpener() {
+    }
+
+    /**
+     * Sets the User Agent to use. <strong>Default value: {@value USER_AGENT}</strong>.
+     *
+     * @param userAgent a user agent to be used when opening a URL
+     */
+    public void setUserAgent(final String userAgent) {
+        this.userAgent = userAgent;
+    }
+
+    /**
+     * Sets the query of the search.
+     * <strong>Setting a query is mandatory.</strong>
+     *
+     * @param query the query
+     */
+
+    public void setQuery(final String query) {
+        this.query = query;
+    }
+
+    /**
+     * Sets total number of records to be retrieved. <strong>Default value: {@value TOTAL}</strong>.
+     *
+     * @param totalRecords total number of records to be retrieved
+     */
+    public void setTotal(final String totalRecords) {
+        this.totalRecords = Integer.getInteger(totalRecords);
+    }
+
+    /**
+     * Sets the maximum of records returned in one lookup. <strong>Default value: {@value MAXIMUM_RECORDS}</strong>.
+     * The lookup is repeated as long as {@link #maximumRecords} is lesser than {@link #totalRecords}.
+     *
+     * @param maximumRecords maximum of records returned in one lookup
+     */
+    public void setMaximumRecords(final String maximumRecords) {
+        this.maximumRecords = Integer.getInteger(maximumRecords);
+    }
+
+    /**
+     * Sets where to start when retrieving records. <strong>Default value: {@value START_RECORD}</strong>.
+     *
+     * @param startRecord where to start when retrieving records
+     */
+    public void setStartRecord(final String startRecord) {
+        this.startRecord = Integer.getInteger(startRecord);
+    }
+
+    /**
+     * Sets the format of the retrieved record data. <strong>Default value: {@value RECORD_SCHEMA}</strong>.
+     *
+     * @param recordSchema the format of the data of the records
+     */
+    public void setRecordSchema(final String recordSchema) {
+        this.recordSchema = recordSchema;
+    }
+
+    /**
+     * Sets the kind of operation of the lookup. <strong>Default value: {@value OPERATION}</strong>.
+     *
+     * @param operation the kind of operation of the lookup
+     */
+    public void setOperation(final String operation) {
+        this.operation = operation;
+    }
+
+    /**
+     * Sets the version of the lookup. <strong>Default value: {@value VERSION}</strong>.
+     *
+     * @param version the version of the lookup
+     */
+    public void setVersion(final String version) {
+        this.version = version;
+    }
+
+    @Override
+    public void process(final String baseUrl) {
+
+        try {
+
+            StringBuilder srUrl = new StringBuilder(baseUrl);
+            if (query != null) {
+                srUrl.append("?query=").append(query).append("&operation=").append(operation).append("&recordSchema=").append(recordSchema).append("&version=").append(version).append("&maximumRecords=").append(maximumRecords).append("&total=").append(totalRecords);
+            }
+            else {
+                throw new IllegalArgumentException("Missing mandatory parameter 'query'");
+            }
+            int retrievedRecords = 0;
+            while (retrievedRecords < totalRecords) {
+                startRecord = retrievedRecords + 1;
+                retrieve(srUrl, startRecord);
+                retrievedRecords = retrievedRecords + maximumRecords;
+            }
+        }
+        catch (final IOException e) {
+            throw new MetafactureException(e);
+        }
+    }
+
+    private void retrieve(StringBuilder srUrl, int startRecord) throws IOException {
+        srUrl.append("&startRecord=").append(startRecord);
+        final URL urlToOpen = new URL(srUrl.toString());
+        final HttpURLConnection connection = (HttpURLConnection) urlToOpen.openConnection();
+
+        connection.setConnectTimeout(CONNECTION_TIMEOUT);
+        if (!userAgent.isEmpty()) {
+            connection.setRequestProperty("User-Agent", userAgent);
+        }
+
+        try (
+            InputStreamReader inputStreamReader = new InputStreamReader(getInputStream(connection))
+        ) {
+            getReceiver().process(inputStreamReader);
+        }
+    }
+
+    private InputStream getInputStream(final HttpURLConnection connection) {
+        try {
+            return connection.getInputStream();
+        }
+        catch (final IOException e) {
+            return connection.getErrorStream();
+        }
+    }
+
+}