Validation sessions (#443)

* Sessions are working,

* adding javadocs to cache

* These changes were already added, the merge re-added them to the RELEASE_NOTES by mistake.

* cleaning code a little

RELEASE_NOTES.md

@@ -0,0 +1 @@
+* adding session ids to validator service

org.hl7.fhir.validation/pom.xml

@@ -100,6 +100,11 @@
             <groupId>org.apache.httpcomponents</groupId>
             <artifactId>httpclient</artifactId>
         </dependency>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-collections4</artifactId>
+            <version>4.4</version>
+        </dependency>
         <dependency>
             <groupId>org.fhir</groupId>
             <artifactId>ucum</artifactId>

org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/IgLoader.java

@@ -1,5 +1,6 @@
 package org.hl7.fhir.validation;
 
+import com.google.gson.JsonObject;
 import lombok.Getter;
 import org.hl7.fhir.convertors.*;
 import org.hl7.fhir.exceptions.FHIRException;
@@ -15,12 +16,15 @@ import org.hl7.fhir.utilities.IniFile;
 import org.hl7.fhir.utilities.TextFile;
 import org.hl7.fhir.utilities.Utilities;
 import org.hl7.fhir.utilities.VersionUtilities;
+import org.hl7.fhir.utilities.json.JSONUtil;
 import org.hl7.fhir.utilities.json.JsonTrackingParser;
 import org.hl7.fhir.utilities.npm.FilesystemPackageCacheManager;
 import org.hl7.fhir.utilities.npm.NpmPackage;
 import org.hl7.fhir.utilities.turtle.Turtle;
+import org.hl7.fhir.utilities.xml.XMLUtil;
 import org.hl7.fhir.validation.cli.utils.Common;
 import org.hl7.fhir.validation.cli.utils.VersionSourceInformation;
+import org.w3c.dom.Document;
 
 import java.io.*;
 import java.net.HttpURLConnection;
@@ -199,6 +203,43 @@ public class IgLoader {
       versions.see(readInfoVersion(source.get("version.info")), "version.info in " + src);
   }
 
+  public void scanForVersions(List<String> sources, VersionSourceInformation versions) throws FHIRException, IOException {
+    List<String> refs = new ArrayList<String>();
+    ValidatorUtils.parseSources(sources, refs, context);
+    for (String ref : refs) {
+      Content cnt = loadContent(ref, "validate", false);
+      String s = TextFile.bytesToString(cnt.focus);
+      if (s.contains("http://hl7.org/fhir/3.0")) {
+        versions.see("3.0", "Profile in " + ref);
+      }
+      if (s.contains("http://hl7.org/fhir/1.0")) {
+        versions.see("1.0", "Profile in " + ref);
+      }
+      if (s.contains("http://hl7.org/fhir/4.0")) {
+        versions.see("4.0", "Profile in " + ref);
+      }
+      if (s.contains("http://hl7.org/fhir/1.4")) {
+        versions.see("1.4", "Profile in " + ref);
+      }
+      try {
+        if (s.startsWith("{")) {
+          JsonObject json = JsonTrackingParser.parse(s, null);
+          if (json.has("fhirVersion")) {
+            versions.see(VersionUtilities.getMajMin(JSONUtil.str(json, "fhirVersion")), "fhirVersion in " + ref);
+          }
+        } else {
+          Document doc = ValidatorUtils.parseXml(cnt.focus);
+          String v = XMLUtil.getNamedChildValue(doc.getDocumentElement(), "fhirVersion");
+          if (v != null) {
+            versions.see(VersionUtilities.getMajMin(v), "fhirVersion in " + ref);
+          }
+        }
+      } catch (Exception e) {
+        // nothing
+      }
+    }
+  }
+
   protected Map<String, byte[]> readZip(InputStream stream) throws IOException {
     Map<String, byte[]> res = new HashMap<>();
     ZipInputStream zip = new ZipInputStream(stream);
@@ -645,7 +686,7 @@ public class IgLoader {
       else if (fn.endsWith(".json") && !fn.endsWith("template.json"))
         r = new JsonParser().parse(new ByteArrayInputStream(content));
       else if (fn.endsWith(".txt"))
-        r = new StructureMapUtilities(context, null, null).parse(TextFile.bytesToString(content), fn);
+        r = new StructureMapUtilities(getContext(), null, null).parse(TextFile.bytesToString(content), fn);
       else if (fn.endsWith(".map"))
         r = new StructureMapUtilities(null).parse(new String(content), fn);
       else

org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/ValidationEngine.java

@@ -193,49 +193,12 @@ public class ValidationEngine implements IValidatorResourceFetcher, IPackageInst
     igLoader = new IgLoader(getPcm(), getContext(), getVersion(), isDebug());
   }
 
-  public ValidationEngine(String src, FhirPublication version, String vString, TimeTracker tt) throws FHIRException, IOException, URISyntaxException {
+  public ValidationEngine(String src, String vString, TimeTracker tt) throws FHIRException, IOException, URISyntaxException {
     loadCoreDefinitions(src, false, tt);
     setVersion(vString);
     igLoader = new IgLoader(getPcm(), getContext(), getVersion(), isDebug());
   }
 
-  public void scanForVersions(List<String> sources, VersionSourceInformation versions) throws FHIRException, IOException {
-    List<String> refs = new ArrayList<String>();
-    ValidatorUtils.parseSources(sources, refs, context);
-    for (String ref : refs) {
-      Content cnt = igLoader.loadContent(ref, "validate", false);
-      String s = TextFile.bytesToString(cnt.focus);
-      if (s.contains("http://hl7.org/fhir/3.0")) {
-        versions.see("3.0", "Profile in " + ref);
-      }
-      if (s.contains("http://hl7.org/fhir/1.0")) {
-        versions.see("1.0", "Profile in " + ref);
-      }
-      if (s.contains("http://hl7.org/fhir/4.0")) {
-        versions.see("4.0", "Profile in " + ref);
-      }
-      if (s.contains("http://hl7.org/fhir/1.4")) {
-        versions.see("1.4", "Profile in " + ref);
-      }
-      try {
-        if (s.startsWith("{")) {
-          JsonObject json = JsonTrackingParser.parse(s, null);
-          if (json.has("fhirVersion")) {
-            versions.see(VersionUtilities.getMajMin(JSONUtil.str(json, "fhirVersion")), "fhirVersion in " + ref);
-          }
-        } else {
-          Document doc = ValidatorUtils.parseXml(cnt.focus);
-          String v = XMLUtil.getNamedChildValue(doc.getDocumentElement(), "fhirVersion");
-          if (v != null) {
-            versions.see(VersionUtilities.getMajMin(v), "fhirVersion in " + ref);
-          }
-        }
-      } catch (Exception e) {
-        // nothing
-      }
-    }
-  }
-
   private void loadCoreDefinitions(String src, boolean recursive, TimeTracker tt) throws FHIRException, IOException {
     NpmPackage npm = getPcm().loadPackage(src, null);
     if (npm != null) {
@@ -252,7 +215,7 @@ public class ValidationEngine implements IValidatorResourceFetcher, IPackageInst
     initContext(tt);
   }
 
-  public void initContext(TimeTracker tt) throws IOException, FileNotFoundException {
+  public void initContext(TimeTracker tt) throws IOException {
     context.setCanNoTS(true);
     context.setCacheId(UUID.randomUUID().toString());
     context.setAllowLoadingDuplicates(true); // because of Forge

org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/ValidatorCli.java

@@ -94,6 +94,8 @@ public class ValidatorCli {
   public static final String JAVA_DISABLED_PROXY_SCHEMES = "jdk.http.auth.proxying.disabledSchemes";
   public static final String JAVA_USE_SYSTEM_PROXIES = "java.net.useSystemProxies";
 
+  private static ValidationService validationService = new ValidationService();
+
   public static void main(String[] args) throws Exception {
     TimeTracker tt = new TimeTracker();
     TimeTracker.Session tts = tt.start("Loading");
@@ -181,42 +183,42 @@ public class ValidatorCli {
   private static void doLeftRightComparison(String[] args, CliContext cliContext, TimeTracker tt) throws Exception {
     Display.printCliArgumentsAndInfo(args);
     if (cliContext.getSv() == null) {
-      cliContext.setSv(ValidationService.determineVersion(cliContext));
+      cliContext.setSv(validationService.determineVersion(cliContext));
     }
     String v = VersionUtilities.getCurrentVersion(cliContext.getSv());
     String definitions = VersionUtilities.packageForVersion(v) + "#" + v;
-    ValidationEngine validator = ValidationService.getValidator(cliContext, definitions, tt);
+    ValidationEngine validator = validationService.initializeValidator(cliContext, definitions, tt);
     ComparisonService.doLeftRightComparison(args, Params.getParam(args, Params.DESTINATION), validator);
   }
 
   private static void doValidation(TimeTracker tt, TimeTracker.Session tts, CliContext cliContext) throws Exception {
     if (cliContext.getSv() == null) {
-      cliContext.setSv(ValidationService.determineVersion(cliContext));
+      cliContext.setSv(validationService.determineVersion(cliContext));
     }
     System.out.println("Loading");
     // Comment this out because definitions filename doesn't necessarily contain version (and many not even be 14 characters long).
     // Version gets spit out a couple of lines later after we've loaded the context
     String definitions = VersionUtilities.packageForVersion(cliContext.getSv()) + "#" + VersionUtilities.getCurrentVersion(cliContext.getSv());
-    ValidationEngine validator = ValidationService.getValidator(cliContext, definitions, tt);
+    ValidationEngine validator = validationService.initializeValidator(cliContext, definitions, tt);
     tts.end();
     switch (cliContext.getMode()) {
       case TRANSFORM:
-        ValidationService.transform(cliContext, validator);
+        validationService.transform(cliContext, validator);
         break;
       case NARRATIVE:
-        ValidationService.generateNarrative(cliContext, validator);
+        validationService.generateNarrative(cliContext, validator);
         break;
       case SNAPSHOT:
-        ValidationService.generateSnapshot(cliContext, validator);
+        validationService.generateSnapshot(cliContext, validator);
         break;
       case CONVERT:
-        ValidationService.convertSources(cliContext, validator);
+        validationService.convertSources(cliContext, validator);
         break;
       case FHIRPATH:
-        ValidationService.evaluateFhirpath(cliContext, validator);
+        validationService.evaluateFhirpath(cliContext, validator);
         break;
       case VERSION:
-        ValidationService.transformVersion(cliContext, validator);
+        validationService.transformVersion(cliContext, validator);
         break;
       case VALIDATION:
       case SCAN:
@@ -232,7 +234,7 @@ public class ValidatorCli {
           Scanner validationScanner = new Scanner(validator.getContext(), validator.getValidator(), validator.getIgLoader(), validator.getFhirPathEngine());
           validationScanner.validateScan(cliContext.getOutput(), cliContext.getSources());
         } else {
-          ValidationService.validateSources(cliContext, validator);
+          validationService.validateSources(cliContext, validator);
         }
         break;
     }

org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/model/ValidationRequest.java

@@ -18,11 +18,19 @@ public class ValidationRequest {
     return cliContext;
   }
 
+  @JsonProperty("sessionId")
+  public String sessionId;
+
   public ValidationRequest() {}
 
   public ValidationRequest(CliContext cliContext, List<FileInfo> filesToValidate) {
+    this(cliContext, filesToValidate, null);
+  }
+
+  public ValidationRequest(CliContext cliContext, List<FileInfo> filesToValidate, String sessionToken) {
     this.cliContext = cliContext;
     this.filesToValidate = filesToValidate;
+    this.sessionId = sessionToken;
   }
 
   @JsonProperty("cliContext")
@@ -42,6 +50,17 @@ public class ValidationRequest {
     return this;
   }
 
+  @JsonProperty("sessionId")
+  public String getSessionId() {
+    return sessionId;
+  }
+
+  @JsonProperty("sessionId")
+  public ValidationRequest setSessionId(String sessionId) {
+    this.sessionId = sessionId;
+    return this;
+  }
+
   public String listSourceFiles() {
     List<String> fileNames = new ArrayList<>();
     for (FileInfo fp : filesToValidate) {

org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/model/ValidationResponse.java

@@ -10,10 +10,18 @@ public class ValidationResponse {
   @JsonProperty("outcomes")
   public List<ValidationOutcome> outcomes = new ArrayList<>();
 
+  @JsonProperty("sessionToken")
+  public String sessionToken;
+
   public ValidationResponse() {}
 
   public ValidationResponse(List<ValidationOutcome> outcomes) {
+    this(outcomes, null);
+  }
+
+  public ValidationResponse(List<ValidationOutcome> outcomes, String sessionToken) {
     this.outcomes = outcomes;
+    this.sessionToken = sessionToken;
   }
 
   @JsonProperty("outcomes")
@@ -27,6 +35,17 @@ public class ValidationResponse {
     return this;
   }
 
+  @JsonProperty("sessionToken")
+  public String getSessionToken() {
+    return sessionToken;
+  }
+
+  @JsonProperty("sessionToken")
+  public ValidationResponse setSessionToken(String sessionToken) {
+    this.sessionToken = sessionToken;
+    return this;
+  }
+
   public ValidationResponse addOutcome(ValidationOutcome outcome) {
     if (outcomes == null) {
       outcomes = new ArrayList<>();

org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/services/SessionCache.java

@@ -0,0 +1,95 @@
+package org.hl7.fhir.validation.cli.services;
+
+import org.apache.commons.collections4.map.PassiveExpiringMap;
+import org.hl7.fhir.validation.ValidationEngine;
+
+import java.util.Set;
+import java.util.UUID;
+import java.util.concurrent.TimeUnit;
+
+/**
+ * SessionCache for storing and retrieving ValidationEngine instances, so callers do not have to re-instantiate a new
+ * instance for each validation request.
+ */
+public class SessionCache {
+
+  protected static final long TIME_TO_LIVE = 60;
+  protected static final TimeUnit TIME_UNIT = TimeUnit.MINUTES;
+
+  private final PassiveExpiringMap<String, ValidationEngine> cachedSessions;
+
+  public SessionCache() {
+    cachedSessions = new PassiveExpiringMap<>(TIME_TO_LIVE, TIME_UNIT);
+  }
+
+  /**
+   * @param sessionLength the constant amount of time an entry is available before it expires. A negative value results
+   *                      in entries that NEVER expire. A zero value results in entries that ALWAYS expire.
+   * @param sessionLengthUnit the unit of time for the timeToLive parameter, must not be null
+   */
+  public SessionCache(long sessionLength, TimeUnit sessionLengthUnit) {
+    cachedSessions = new PassiveExpiringMap<>(sessionLength, sessionLengthUnit);
+  }
+
+  /**
+   * Stores the initialized {@link ValidationEngine} in the cache. Returns the session id that will be associated with
+   * this instance.
+   * @param validationEngine {@link ValidationEngine}
+   * @return The {@link String} id associated with the stored instance.
+   */
+  public String cacheSession(ValidationEngine validationEngine) {
+    String generatedId = generateID();
+    cachedSessions.put(generatedId, validationEngine);
+    return generatedId;
+  }
+
+  /**
+   * Stores the initialized {@link ValidationEngine} in the cache with the passed in id as the key. If a null key is
+   * passed in, a new key is generated and returned.
+   * @param sessionId The {@link String} key to associate with this stored {@link ValidationEngine}
+   * @param validationEngine The {@link ValidationEngine} instance to cache.
+   * @return The {@link String} id that will be associated with the stored {@link ValidationEngine}
+   */
+  public String cacheSession(String sessionId, ValidationEngine validationEngine) {
+    if(sessionId == null) {
+      sessionId = cacheSession(validationEngine);
+    } else {
+      cachedSessions.put(sessionId, validationEngine);
+    }
+    return sessionId;
+  }
+
+  /**
+   * Checks if the passed in {@link String} id exists in the set of stored session id.
+   * @param sessionId The {@link String} id to search for.
+   * @return {@link Boolean#TRUE} if such id exists.
+   */
+  public boolean sessionExists(String sessionId) {
+    return cachedSessions.containsKey(sessionId);
+  }
+
+  /**
+   * Returns the stored {@link ValidationEngine} associated with the passed in session id, if one such instance exists.
+   * @param sessionId The {@link String} session id.
+   * @return The {@link ValidationEngine} associated with the passed in id, or null if none exists.
+   */
+  public ValidationEngine fetchSessionValidatorEngine(String sessionId) {
+    return cachedSessions.get(sessionId);
+  }
+
+  /**
+   * Returns the set of stored session ids.
+   * @return {@link Set} of session ids.
+   */
+  public Set<String> getSessionIds() {
+    return cachedSessions.keySet();
+  }
+
+  /**
+   * Session ids generated internally are UUID {@link String}.
+   * @return A new {@link String} session id.
+   */
+  private String generateID() {
+    return UUID.randomUUID().toString();
+  }
+}

org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/services/ValidationService.java

@@ -1,26 +1,20 @@
 package org.hl7.fhir.validation.cli.services;
 
-import java.io.FileOutputStream;
+import org.hl7.fhir.r5.context.SimpleWorkerContext;
-import java.util.ArrayList;
-import java.util.List;
-
 import org.hl7.fhir.r5.context.TerminologyCache;
 import org.hl7.fhir.r5.elementmodel.Manager;
 import org.hl7.fhir.r5.formats.IParser;
 import org.hl7.fhir.r5.formats.JsonParser;
 import org.hl7.fhir.r5.formats.XmlParser;
-import org.hl7.fhir.r5.model.Bundle;
+import org.hl7.fhir.r5.model.*;
-import org.hl7.fhir.r5.model.DomainResource;
-import org.hl7.fhir.r5.model.FhirPublication;
-import org.hl7.fhir.r5.model.OperationOutcome;
-import org.hl7.fhir.r5.model.Resource;
-import org.hl7.fhir.r5.model.StructureDefinition;
 import org.hl7.fhir.r5.model.StructureDefinition.StructureDefinitionKind;
 import org.hl7.fhir.r5.utils.ToolingExtensions;
 import org.hl7.fhir.utilities.TextFile;
 import org.hl7.fhir.utilities.TimeTracker;
 import org.hl7.fhir.utilities.Utilities;
 import org.hl7.fhir.utilities.VersionUtilities;
+import org.hl7.fhir.utilities.npm.FilesystemPackageCacheManager;
+import org.hl7.fhir.utilities.npm.ToolsVersion;
 import org.hl7.fhir.utilities.validation.ValidationMessage;
 import org.hl7.fhir.validation.IgLoader;
 import org.hl7.fhir.validation.ValidationEngine;
@@ -29,14 +23,32 @@ import org.hl7.fhir.validation.cli.model.*;
 import org.hl7.fhir.validation.cli.utils.EngineMode;
 import org.hl7.fhir.validation.cli.utils.VersionSourceInformation;
 
+import java.io.FileOutputStream;
+import java.util.ArrayList;
+import java.util.List;
+
 public class ValidationService {
 
-  public static ValidationResponse validateSources(ValidationRequest request) throws Exception {
+  private final SessionCache sessionCache;
+
+  public ValidationService() {
+    sessionCache = new SessionCache();
+  }
+
+  protected ValidationService(SessionCache cache) {
+    this.sessionCache = cache;
+  }
+
+  public ValidationResponse validateSources(ValidationRequest request) throws Exception {
     if (request.getCliContext().getSv() == null) {
-      request.getCliContext().setSv(ValidationService.determineVersion(request.getCliContext()));
+      String sv = determineVersion(request.getCliContext(), request.sessionId);
+      request.getCliContext().setSv(sv);
     }
+
     String definitions = VersionUtilities.packageForVersion(request.getCliContext().getSv()) + "#" + VersionUtilities.getCurrentVersion(request.getCliContext().getSv());
-    ValidationEngine validator = ValidationService.getValidator(request.getCliContext(), definitions, new TimeTracker());
+
+    String sessionId = initializeValidator(request.getCliContext(), definitions, new TimeTracker(), request.sessionId);
+    ValidationEngine validator = sessionCache.fetchSessionValidatorEngine(sessionId);
 
     if (request.getCliContext().getProfiles().size() > 0) {
       System.out.println("  .. validate " + request.listSourceFiles() + " against " + request.getCliContext().getProfiles().toString());
@@ -56,23 +68,25 @@ public class ValidationService {
     return response;
   }
 
-  public static VersionSourceInformation scanForVersions(CliContext cliContext) throws Exception {
+  public VersionSourceInformation scanForVersions(CliContext cliContext) throws Exception {
     VersionSourceInformation versions = new VersionSourceInformation();
-    ValidationEngine ve = new ValidationEngine();
+    IgLoader igLoader = new IgLoader(
-    IgLoader igLoader = new IgLoader(ve.getPcm(), ve.getContext(), ve.getVersion(), ve.isDebug());
+      new FilesystemPackageCacheManager(true, ToolsVersion.TOOLS_VERSION),
+      SimpleWorkerContext.fromNothing(),
+      null);
     for (String src : cliContext.getIgs()) {
       igLoader.scanForIgVersion(src, cliContext.isRecursive(), versions);
     }
-    ve.scanForVersions(cliContext.getSources(), versions);
+    igLoader.scanForVersions(cliContext.getSources(), versions);
     return versions;
   }
-  
+
-  public static void validateSources(CliContext cliContext, ValidationEngine validator) throws Exception {
+  public void validateSources(CliContext cliContext, ValidationEngine validator) throws Exception {
     long start = System.currentTimeMillis();
     List<ValidationRecord> records = new ArrayList<>();
     Resource r = validator.validate(cliContext.getSources(), cliContext.getProfiles(), records);
     int ec = 0;
-    System.out.println("Done. "+validator.getContext().clock().report());
+    System.out.println("Done. " + validator.getContext().clock().report());
     System.out.println();
 
     if (cliContext.getOutput() == null) {
@@ -98,24 +112,24 @@ public class ValidationService {
       s.close();
     }
     if (cliContext.getHtmlOutput() != null) {
-      String html = new HTMLOutputGenerator(records).generate(System.currentTimeMillis()-start);
+      String html = new HTMLOutputGenerator(records).generate(System.currentTimeMillis() - start);
       TextFile.stringToFile(html, cliContext.getHtmlOutput());
-      System.out.println("HTML Summary in "+cliContext.getHtmlOutput());
+      System.out.println("HTML Summary in " + cliContext.getHtmlOutput());
     }
     System.exit(ec > 0 ? 1 : 0);
   }
 
-  public static void convertSources(CliContext cliContext, ValidationEngine validator) throws Exception {
+  public void convertSources(CliContext cliContext, ValidationEngine validator) throws Exception {
     System.out.println(" ...convert");
     validator.convert(cliContext.getSources().get(0), cliContext.getOutput());
   }
 
-  public static void evaluateFhirpath(CliContext cliContext, ValidationEngine validator) throws Exception {
+  public void evaluateFhirpath(CliContext cliContext, ValidationEngine validator) throws Exception {
     System.out.println(" ...evaluating " + cliContext.getFhirpath());
     System.out.println(validator.evaluateFhirPath(cliContext.getSources().get(0), cliContext.getFhirpath()));
   }
 
-  public static void generateSnapshot(CliContext cliContext, ValidationEngine validator) throws Exception {
+  public void generateSnapshot(CliContext cliContext, ValidationEngine validator) throws Exception {
     StructureDefinition r = validator.snapshot(cliContext.getSources().get(0), cliContext.getSv());
     System.out.println(" ...generated snapshot successfully");
     if (cliContext.getOutput() != null) {
@@ -123,7 +137,7 @@ public class ValidationService {
     }
   }
 
-  public static void generateNarrative(CliContext cliContext, ValidationEngine validator) throws Exception {
+  public void generateNarrative(CliContext cliContext, ValidationEngine validator) throws Exception {
     DomainResource r = validator.generate(cliContext.getSources().get(0), cliContext.getSv());
     System.out.println(" ...generated narrative successfully");
     if (cliContext.getOutput() != null) {
@@ -131,7 +145,7 @@ public class ValidationService {
     }
   }
 
-  public static void transform(CliContext cliContext, ValidationEngine validator) throws Exception {
+  public void transform(CliContext cliContext, ValidationEngine validator) throws Exception {
     if (cliContext.getSources().size() > 1)
       throw new Exception("Can only have one source when doing a transform (found " + cliContext.getSources() + ")");
     if (cliContext.getTxServer() == null)
@@ -166,7 +180,7 @@ public class ValidationService {
     }
   }
 
-  public static void transformVersion(CliContext cliContext, ValidationEngine validator) throws Exception {
+  public void transformVersion(CliContext cliContext, ValidationEngine validator) throws Exception {
     if (cliContext.getSources().size() > 1) {
       throw new Exception("Can only have one source when converting versions (found " + cliContext.getSources() + ")");
     }
@@ -189,44 +203,54 @@ public class ValidationService {
     }
   }
 
-  public static ValidationEngine getValidator(CliContext cliContext, String definitions, TimeTracker tt) throws Exception {
+  public ValidationEngine initializeValidator(CliContext cliContext, String definitions, TimeTracker tt) throws Exception {
-    tt.milestone();
+    return sessionCache.fetchSessionValidatorEngine(initializeValidator(cliContext, definitions, tt, null));
-    System.out.print("  Load FHIR v" + cliContext.getSv() + " from " + definitions);
-    FhirPublication ver = FhirPublication.fromCode(cliContext.getSv());
-    ValidationEngine validator = new ValidationEngine(definitions, ver, cliContext.getSv(), tt);
-    IgLoader igLoader = new IgLoader(validator.getPcm(), validator.getContext(), validator.getVersion(), validator.isDebug());
-    System.out.println(" - "+validator.getContext().countAllCaches()+" resources ("+tt.milestone()+")");
-    igLoader.loadIg(validator.getIgs(), validator.getBinaries(), "hl7.terminology", false);
-    System.out.print("  Terminology server " + cliContext.getTxServer());
-    String txver = validator.setTerminologyServer(cliContext.getTxServer(), cliContext.getTxLog(), ver); 
-    System.out.println(" - Version "+txver+" ("+tt.milestone()+")");
-    validator.setDebug(cliContext.isDoDebug());
-    for (String src : cliContext.getIgs()) {
-      igLoader.loadIg(validator.getIgs(), validator.getBinaries(), src, cliContext.isRecursive());
-    }
-    System.out.print("  Get set... ");
-    validator.setQuestionnaireMode(cliContext.getQuestionnaireMode());
-    validator.setDoNative(cliContext.isDoNative());
-    validator.setHintAboutNonMustSupport(cliContext.isHintAboutNonMustSupport());
-    validator.setAnyExtensionsAllowed(cliContext.isAnyExtensionsAllowed());
-    validator.setLanguage(cliContext.getLang());
-    validator.setLocale(cliContext.getLocale());
-    validator.setSnomedExtension(cliContext.getSnomedCTCode());
-    validator.setAssumeValidRestReferences(cliContext.isAssumeValidRestReferences());
-    validator.setNoExtensibleBindingMessages(cliContext.isNoExtensibleBindingMessages());
-    validator.setSecurityChecks(cliContext.isSecurityChecks());
-    validator.setCrumbTrails(cliContext.isCrumbTrails());
-    validator.setShowTimes(cliContext.isShowTimes());
-    validator.setFetcher(new StandAloneValidatorFetcher(validator.getPcm(), validator.getContext(), validator));
-    validator.getBundleValidationRules().addAll(cliContext.getBundleValidationRules());
-    TerminologyCache.setNoCaching(cliContext.isNoInternalCaching());
-    validator.prepare(); // generate any missing snapshots
-    System.out.println(" go ("+tt.milestone()+")");
-
-    return validator;
   }
 
-  public static int displayOperationOutcome(OperationOutcome oo, boolean hasMultiples) {
+  public String initializeValidator(CliContext cliContext, String definitions, TimeTracker tt, String sessionId) throws Exception {
+    tt.milestone();
+    if (!sessionCache.sessionExists(sessionId)) {
+      System.out.println("No such cached session exists for session id " + sessionId + ", re-instantiating validator.");
+      System.out.print("  Load FHIR v" + cliContext.getSv() + " from " + definitions);
+      ValidationEngine validator = new ValidationEngine(definitions, cliContext.getSv(), tt);
+      sessionId = sessionCache.cacheSession(validator);
+
+      FhirPublication ver = FhirPublication.fromCode(cliContext.getSv());
+      IgLoader igLoader = new IgLoader(validator.getPcm(), validator.getContext(), validator.getVersion(), validator.isDebug());
+      System.out.println(" - " + validator.getContext().countAllCaches() + " resources (" + tt.milestone() + ")");
+      igLoader.loadIg(validator.getIgs(), validator.getBinaries(), "hl7.terminology", false);
+      System.out.print("  Terminology server " + cliContext.getTxServer());
+      String txver = validator.setTerminologyServer(cliContext.getTxServer(), cliContext.getTxLog(), ver);
+      System.out.println(" - Version " + txver + " (" + tt.milestone() + ")");
+      validator.setDebug(cliContext.isDoDebug());
+      for (String src : cliContext.getIgs()) {
+        igLoader.loadIg(validator.getIgs(), validator.getBinaries(), src, cliContext.isRecursive());
+      }
+      System.out.print("  Get set... ");
+      validator.setQuestionnaireMode(cliContext.getQuestionnaireMode());
+      validator.setDoNative(cliContext.isDoNative());
+      validator.setHintAboutNonMustSupport(cliContext.isHintAboutNonMustSupport());
+      validator.setAnyExtensionsAllowed(cliContext.isAnyExtensionsAllowed());
+      validator.setLanguage(cliContext.getLang());
+      validator.setLocale(cliContext.getLocale());
+      validator.setSnomedExtension(cliContext.getSnomedCTCode());
+      validator.setAssumeValidRestReferences(cliContext.isAssumeValidRestReferences());
+      validator.setNoExtensibleBindingMessages(cliContext.isNoExtensibleBindingMessages());
+      validator.setSecurityChecks(cliContext.isSecurityChecks());
+      validator.setCrumbTrails(cliContext.isCrumbTrails());
+      validator.setShowTimes(cliContext.isShowTimes());
+      validator.setFetcher(new StandAloneValidatorFetcher(validator.getPcm(), validator.getContext(), validator));
+      validator.getBundleValidationRules().addAll(cliContext.getBundleValidationRules());
+      TerminologyCache.setNoCaching(cliContext.isNoInternalCaching());
+      validator.prepare(); // generate any missing snapshots
+      System.out.println(" go (" + tt.milestone() + ")");
+    } else {
+      System.out.println("Cached session exists for session id " + sessionId + ", returning stored validator session id.");
+    }
+    return sessionId;
+  }
+
+  public int displayOperationOutcome(OperationOutcome oo, boolean hasMultiples) {
     int error = 0;
     int warn = 0;
     int info = 0;
@@ -240,29 +264,29 @@ public class ValidationService {
       else
         info++;
     }
-        
+
     if (hasMultiples) {
       System.out.print("-- ");
       System.out.print(file);
       System.out.print(" --");
-      System.out.println(Utilities.padLeft("",  '-', Integer.max(38, file.length()+6)));
+      System.out.println(Utilities.padLeft("", '-', Integer.max(38, file.length() + 6)));
     }
-    System.out.println((error == 0 ? "Success" : "*FAILURE*") + ": " + Integer.toString(error) + " errors, " + Integer.toString(warn) + " warnings, " + Integer.toString(info)+" notes");
+    System.out.println((error == 0 ? "Success" : "*FAILURE*") + ": " + Integer.toString(error) + " errors, " + Integer.toString(warn) + " warnings, " + Integer.toString(info) + " notes");
     for (OperationOutcome.OperationOutcomeIssueComponent issue : oo.getIssue()) {
       System.out.println(getIssueSummary(issue));
     }
     if (hasMultiples) {
       System.out.print("---");
-      System.out.print(Utilities.padLeft("",  '-', file.length()));
+      System.out.print(Utilities.padLeft("", '-', file.length()));
       System.out.print("---");
-      System.out.println(Utilities.padLeft("",  '-', Integer.max(38, file.length()+6)));
+      System.out.println(Utilities.padLeft("", '-', Integer.max(38, file.length() + 6)));
       System.out.println();
     }
     return error;
   }
 
-  private static String getIssueSummary(OperationOutcome.OperationOutcomeIssueComponent issue) {
+  private String getIssueSummary(OperationOutcome.OperationOutcomeIssueComponent issue) {
-    String loc = null;
+    String loc;
     if (issue.hasExpression()) {
       int line = ToolingExtensions.readIntegerExtension(issue, ToolingExtensions.EXT_ISSUE_LINE, -1);
       int col = ToolingExtensions.readIntegerExtension(issue, ToolingExtensions.EXT_ISSUE_COL, -1);
@@ -277,12 +301,16 @@ public class ValidationService {
     return "  " + issue.getSeverity().getDisplay() + " @ " + loc + " : " + issue.getDetails().getText();
   }
 
-  public static String determineVersion(CliContext cliContext) throws Exception {
+  public String determineVersion(CliContext cliContext) throws Exception {
+    return determineVersion(cliContext, null);
+  }
+
+  public String determineVersion(CliContext cliContext, String sessionId) throws Exception {
     if (cliContext.getMode() != EngineMode.VALIDATION) {
       return "current";
     }
     System.out.println("Scanning for versions (no -version parameter):");
-    VersionSourceInformation versions = ValidationService.scanForVersions(cliContext);
+    VersionSourceInformation versions = scanForVersions(cliContext);
     for (String s : versions.getReport()) {
       if (!s.equals("(nothing found)")) {
         System.out.println("  " + s);

org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/utils/Common.java

@@ -87,7 +87,7 @@ public class Common {
 
   public static ValidationEngine getValidationEngine(String version, String txServer, String definitions, String txLog, TimeTracker tt) throws Exception {
     System.out.println("Loading (v = " + version + ", tx server -> " + txServer + ")");
-    ValidationEngine ve = new ValidationEngine(definitions, FhirPublication.fromCode(version), version, tt);
+    ValidationEngine ve = new ValidationEngine(definitions, version, tt);
     ve.connectToTSServer(txServer, txLog, FhirPublication.fromCode(version));
     return ve;
   }

org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/cli/utils/VersionSourceInformation.java

@@ -8,8 +8,8 @@ import java.util.List;
 
 public class VersionSourceInformation {
 
-  private List<String> report = new ArrayList<>();
+  private final List<String> report = new ArrayList<>();
-  private List<String> versions = new ArrayList<>();
+  private final List<String> versions = new ArrayList<>();
 
   public void see(String version, String src) {
     version = VersionUtilities.getMajMin(version);

org.hl7.fhir.validation/src/test/java/org/hl7/fhir/validation/cli/services/SessionCacheTest.java

@@ -0,0 +1,51 @@
+package org.hl7.fhir.validation.cli.services;
+
+import org.hl7.fhir.validation.ValidationEngine;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+
+import java.io.IOException;
+import java.util.UUID;
+import java.util.concurrent.TimeUnit;
+
+class SessionCacheTest {
+
+  @Test
+  @DisplayName("test session expiration works")
+  void expiredSession() throws IOException, InterruptedException {
+    final long EXPIRE_TIME = 5L;
+    SessionCache cache = new SessionCache(EXPIRE_TIME, TimeUnit.SECONDS);
+    ValidationEngine testEngine = new ValidationEngine();
+    String sessionId = cache.cacheSession(testEngine);
+    TimeUnit.SECONDS.sleep(EXPIRE_TIME + 1L);
+    Assertions.assertNull(cache.fetchSessionValidatorEngine(sessionId));
+  }
+
+  @Test
+  @DisplayName("test session caching works")
+  void cachedSession() throws IOException {
+    final long EXPIRE_TIME = 5L;
+    SessionCache cache = new SessionCache(EXPIRE_TIME, TimeUnit.SECONDS);
+    ValidationEngine testEngine = new ValidationEngine();
+    String sessionId = cache.cacheSession(testEngine);
+    Assertions.assertEquals(testEngine, cache.fetchSessionValidatorEngine(sessionId));
+  }
+
+  @Test
+  @DisplayName("test session exists")
+  void sessionExists() throws IOException {
+    SessionCache cache = new SessionCache();
+    ValidationEngine testEngine = new ValidationEngine();
+    String sessionId = cache.cacheSession(testEngine);
+    Assertions.assertTrue(cache.sessionExists(sessionId));
+    Assertions.assertFalse(cache.sessionExists(UUID.randomUUID().toString()));
+  }
+
+  @Test
+  @DisplayName("test null session test id returns false")
+  void testNullSessionExists() {
+    SessionCache cache = new SessionCache();
+    Assertions.assertFalse(cache.sessionExists(null));
+  }
+}

org.hl7.fhir.validation/src/test/java/org/hl7/fhir/validation/cli/services/ValidationServiceTest.java

@@ -0,0 +1,67 @@
+package org.hl7.fhir.validation.cli.services;
+
+import org.apache.commons.io.Charsets;
+import org.apache.commons.io.IOUtils;
+import org.hl7.fhir.r5.elementmodel.Manager;
+import org.hl7.fhir.validation.ValidationEngine;
+import org.hl7.fhir.validation.cli.model.CliContext;
+import org.hl7.fhir.validation.cli.model.FileInfo;
+import org.hl7.fhir.validation.cli.model.ValidationRequest;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.mockito.ArgumentMatchers;
+import org.mockito.Mockito;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.nio.charset.StandardCharsets;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Set;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class ValidationServiceTest {
+
+  @Test
+  void validateSources() throws Exception {
+    SessionCache sessionCache = Mockito.spy(new SessionCache());
+    ValidationService myService = new ValidationService(sessionCache);
+
+    String resource = IOUtils.toString(getFileFromResourceAsStream("detected_issues.json"), StandardCharsets.UTF_8);
+    List<FileInfo> filesToValidate = new ArrayList<>();
+    filesToValidate.add(new FileInfo().setFileName("test_resource.json").setFileContent(resource).setFileType(Manager.FhirFormat.JSON.getExtension()));
+
+    ValidationRequest request = new ValidationRequest().setCliContext(new CliContext()).setFilesToValidate(filesToValidate);
+    // Validation run 1...nothing cached yet
+    myService.validateSources(request);
+    Mockito.verify(sessionCache, Mockito.times(1)).cacheSession(ArgumentMatchers.any(ValidationEngine.class));
+
+    Set<String> sessionIds = sessionCache.getSessionIds();
+    if (sessionIds.stream().findFirst().isPresent()) {
+      // Verify that after 1 run there is only one entry within the cache
+      Assertions.assertEquals(1, sessionIds.size());
+      myService.validateSources(request);
+      // Verify that the cache has been called on once with the id created in the first run
+      Mockito.verify(sessionCache, Mockito.times(1)).fetchSessionValidatorEngine(sessionIds.stream().findFirst().get());
+    } else {
+      // If no sessions exist within the cache after a run, we auto-fail.
+      fail();
+    }
+  }
+
+  private InputStream getFileFromResourceAsStream(String fileName) {
+    // The class loader that loaded the class
+    ClassLoader classLoader = getClass().getClassLoader();
+    InputStream inputStream = classLoader.getResourceAsStream(fileName);
+
+    // the stream holding the file content
+    if (inputStream == null) {
+      throw new IllegalArgumentException("file not found! " + fileName);
+    } else {
+      return inputStream;
+    }
+  }
+}

org.hl7.fhir.validation/src/test/resources/detected_issues.json

@@ -0,0 +1,18 @@
+{
+  "resourceType": "DetectedIssue",
+  "identifier": [ {
+    "system": "http://covidcare.au/app/checkin",
+    "value": "7"
+  } ],
+  "status": "final",
+  "patient": "Patient/4912",
+  "identifiedDateTime": "3020-10-27T13:33:15+11:00",
+  "code": {
+    "coding": [ {
+      "system": "http://covidcare.au/app/alert",
+      "code": "trendNegative",
+      "display": "CovidCare: Vital signs trend negative alert: re-check recommended"
+    } ],
+    "text": "CovidCare alert"
+  }
+}