Qorus Integration Engine®  5.1.31_git
Developing in Java

Table of Contents

Introduction to Java Development in Qorus

Qorus supports native Java development where code attributes of objects can be defined with code in Java in addition to Qore.

Java integration with Qore is implemented using the jni module, which provides tight integration with both languages, including dynamic imports into Java using bytecode generation of wrapper classes for deep language integration based on introspection / reflection of the inported language and runtime data conversions.

All Qore APIs are available in Java using dynamic imports using the special "qore" package.

The main Qorus APIs are:

  • UserApi: available as qore.OMQ.UserApi.UserApi
  • WorkflowApi: available as qore.OMQ.UserApi.Workflow.WorkflowApi
  • ServiceApi: available as qore.OMQ.UserApi.Service.ServiceApi
  • JobApi: available as qore.OMQ.UserApi.Job.JobApi

Java code is defined in class objects, and classpath entries for each object can be specified using the classpath tag in a class object; see Java Classpath Handling in Qorus for more information and examples.

To use Java with Qore, a compatible JDK must be installed on the Qorus server machine; see Java Requirements

Note
The following hardcoded Java APIs available in Qorus JAR files are now deprecated and have not been updated since Qorus 5.0; they are a subset of the dynamic APIs described above:

Java Classpath Handling in Qorus

Generally, the Java classpath is set with the object tag classpath when defining Java code in Qorus. Furthermore, the recommended storage location for jar or class files is in $OMQ_DIR/user/jar.

The classpath tag accepts environment variables, and each element in the classpath should be separated by a colon (":"); see the following examples for more information.

In class definitions, the Java classpath is set with the tag classpath as in the following example:

Example Classpath Tag Value
classpath: $OMQ_DIR/user/jar/my-jar-1.jar:$OMQ_DIR/user/jar/my-jar-2.jar

Compiling Java to Bytecode for Qorus

Either oload or the QoreJavaCompiler must be used to compile Java source using dymamic imports to bytecode.

Both oload and QoreJavaCompiler require the Qore jni JAR file to be available as well:

  • $OMQ_DIR/jar/qore-jni.jar: provides the low-level API connecting Qore and Java

The standard Java compiler cannot be used if your Qorus code uses dynamic API imports.

Using Java in Qorus Workflows

Qorus workflows can be defined in Java by implementing a step class by subclassing one of the following step classes for the step:

Note
The old Qorus-specific JAR files with hardcoded Qorus APIs are deprecated and are no longer receiving updates since Qorus 5.0. The following jar files were used when developing with the deprecated APIs for workflows:
  • $OMQ_DIR/jar/qore-jni.jar: provides the low-level API connecting Qore and Java
  • $OMQ_DIR/jar/qorus-common.jar: (deprecated) the base Qorus API common to all interfaces
  • $OMQ_DIR/jar/qorus-workflow.jar: (deprecated) the Qorus workflow API

Using Java in Qorus Services

Qorus services can be defined in Java by subclassing the QorusService class, available as qore.OMQ.UserApi.Service.QorusService in Java

Note
The old Qorus-specific JAR files with hardcoded Qorus APIs are deprecated and are no longer receiving updates since Qorus 5.0. The following jar files were used when developing with the deprecated APIs for services:
  • $OMQ_DIR/jar/qore-jni.jar: provides the low-level API connecting Qore and Java
  • $OMQ_DIR/jar/qorus-common.jar: (deprecated) the base Qorus API common to all interfaces
  • $OMQ_DIR/jar/qorus-service.jar: (deprecated) the Qorus service API

Deprecated Service Method Annotations

Service method annotations, meant to support the development of Qorus service code in JAR or class files without YAML metadata are deprecated, as the hardcoded JAR files are no longer necessary with the dynamic Java API support introduced in Qorus 5.1, and YAML-metadata-based services are the primary recommended and supported way to implement Qorus services.

When developing service classes or base classes to be delivered in binary format (jar or class files), Qorus service methods must be declared with the QoreMethod annotation as in the following example:

Example (MyJavaService.java):
package com.qoretechnologies.qorus.example;
import qore.OMQ.UserApi.UserApi;
import qore.OMQ.UserApi.Service.*;
import java.time.ZonedDateTime;
class MyJavaService extends QorusService {
public static final ZonedDateTime systemStarted;
static {
try {
systemStarted = (ZonedDateTime)callRestApi("GET", "system/starttime");
} catch (Throwable e) {
throw new RuntimeException(e);
}
}
@QorusMethod(
desc = "initializes the service"
)
public void init() throws Throwable {
}
@QorusMethod(
desc = "an example static service method"
)
public static void other() throws Throwable {
}
}

Using Java in Qorus Jobs

Qorus jobs can be defined in Java by implementing a job class and subclassing the QorusJob class (available as qore.OMQ.UserApi.Job.QorusJob in Java) as in the following example (note the use of the classpath tag to provide the classpath for jobs).

Example Classpath Tag Value
classpath: $OMQ_DIR/user/jar/my-jar-1.jar:$OMQ_DIR/user/jar/my-jar-2.jar
Example (java-example-job-v1.0.qjob.java):
package com.qoretechnologies.qorus.example;
import qore.OMQ.UserApi.Job.QorusJob;
class MyJavaExampleJob extends QorusJob throws Throwable {
// the run method implements the job's logic
public void run() throws Throwable {
logInfo("test job info: %y", getInfo());
}
}
Note
The old Qorus-specific JAR files with hardcoded Qorus APIs are deprecated and are no longer receiving updates since Qorus 5.0. The following jar files were used when developing with the deprecated APIs for jobs:
  • $OMQ_DIR/jar/qore-jni.jar: provides the low-level API connecting Qore and Java
  • $OMQ_DIR/jar/qorus-common.jar: (deprecated) the base Qorus API common to all interfaces
  • $OMQ_DIR/jar/qorus-job.jar: (deprecated) the Qorus job API

Restrictions on Java APIs

Java is not subject to sandboxing controls like Qore code, so it's easier to do dangerous things with Java.

All normal Java programming best practices should be followed when programming in Java; make sure all resources are freed in finally blocks and so forth; Qorus can only manage Qore resources, the Java JVM manages all Java resources normally.

Do not do any of the following:

  • Do not try to call any Qorus functionality from a Java thread not created by Qorus
  • Generally you should not create Java threads; any backgrgound functionality should be handled in a Qorus service
  • Do not make any calls that affect the current running process (ex: System.exit(), Runtime.exit() or Runtime.halt() and similar)

Java Classes Wrapping a Qore Object

Java classes that wrap Qore classes manage a weak reference to the Qore object using the QoreObjectBase class (in manually-generated wrapper classes also with the QoreObjectWrapper class. Strong references to the Qore objects are always managed in Qorus, which means that when creating or acquiring a Qore object in Qorus with Java, the object will normally go out of scope after control returns to Qorus, meaning that the Qore destructor is then run, so that Qore's deterministic garbage collector can also be used in Java code.

For example, locks are released when DynamicDataHelper objects are collected after created from Java step code. The same applies to TempDataHelper or SensitiveDataHelper objects.

See also

Writing Tests in Java for Qorus Interfaces

The following classes can help to write tests written in Java:

The Qorus test APIs are found in the qorus-test.jar file; ex: 

    # compile:
    javac -cp ${OMQ_DIR}/jar/qorus-client.jar:${OMQ_DIR}/jar/qorus-test.jar:${OMQ_DIR}/jar/qore-jni.jar MyTest.java
    # run:
    java -Djava.library.path=$OMQ_DIR/lib/libqore.so -cp ${OMQ_DIR}/jar/qorus-client.jar:${OMQ_DIR}/jar/qorus-test.jar:${OMQ_DIR}/jar/qore-jni.jar:. MyTest
See also
Example Workflow Test
import com.qoretechnologies.qorus.*;
import com.qoretechnologies.qorus.client.*;
import com.qoretechnologies.qorus.test.*;
import java.util.HashMap;
class TestWorkflow {
public static void main(String[] args) throws Throwable {
QorusClientCore.init2();
QorusWorkflowTest test = new QorusWorkflowTest("SIMPLETEST", "1.0");
test.addTestCase("wf test", () -> testWorkflow(test));
test.main();
}
@SuppressWarnings("unchecked")
private static void testWorkflow(QorusWorkflowTest test) throws Throwable {
HashMap<String, Object> static_data = new HashMap<String, Object>();
HashMap<String, Object> order_hash = new HashMap<String, Object>();
order_hash.put("staticdata", static_data);
HashMap<String, Object> result = test.execSynchronous(order_hash);
test.assertEq(OMQ.StatComplete, result.get("status"));
QorusSystemRestHelper qrest = new QorusSystemRestHelper();
QorusClientAPI omqclient = new QorusClientAPI();
HashMap<String, Object> rv = (HashMap<String, Object>)qrest.putRest("workflows/SIMPLETEST/setAutostart?autostart=1");
try {
test.exec(new CheckRunningWorkflow("SIMPLETEST"));
// create a workflow order
int wfiid = omqclient.createWorkflowInstanceName("SIMPLETEST", "1.0", new HashMap<String, Object>());
String name = test.getQorusInstanceName();
test.assertTrue(name != null);
// workaround for bug #2884:
qrest.putRest("workflows/SIMPLETEST/reset");
test.exec(new WaitForWfiid(wfiid));
test.assertEq(OMQ.StatComplete, qrest.getRest("orders/" + wfiid + "/workflowstatus"));
} finally {
qrest.putRest("workflows/SIMPLETEST/setAutostart?autostart=0");
}
}
}
String
const String
OMQ
main Qorus namespace
Definition: QorusRbacAuth.qm:25
Example Service Test
import com.qoretechnologies.qorus.*;
import com.qoretechnologies.qorus.client.*;
import com.qoretechnologies.qorus.test.*;
import java.util.HashMap;
class TestService {
public static void main(String[] args) throws Throwable {
QorusClientCore.init2();
QorusServiceTest test = new QorusServiceTest("http-test");
test.addTestCase("svc test", () -> testService(test));
test.main();
}
private static void testService(QorusServiceTest test) throws Throwable {
CallService call = new CallService("http-test", "echo", 1);
test.exec(call);
test.assertEq(1, ((Object[])call.getResult())[0]);
}
}
Object
const Object
Example Job Test
import com.qoretechnologies.qorus.*;
import com.qoretechnologies.qorus.client.*;
import com.qoretechnologies.qorus.test.*;
import java.util.HashMap;
class TestJob {
public static void main(String[] args) throws Throwable {
QorusClientCore.init2();
QorusJobTest test = new QorusJobTest("test");
test.addTestCase("job test", () -> testJob(test));
test.main();
}
private static void testJob(QorusJobTest test) throws Throwable {
RunJob action = new RunJob();
test.exec(action);
action = new RunJobResult(OMQ.StatComplete);
test.exec(action);
}
}
Note
The test classes anove are based on the Test class which provides a wrapper for the QUnit module in Qore.

Qorus Java Client API

The Java Qorus client API can be found in the com.qoretechnologies.qorus.client package which is delivered in the qorus-client.jar file; ex: 

# compile:
javac -cp ${OMQ_DIR}/jar/qorus-client.jar:${OMQ_DIR}/jar/qore-jni.jar MyQorusClient.java
# run:
java -Djava.library.path=$OMQ_DIR/lib/libqore.so -cp ${OMQ_DIR}/jar/qorus-client.jar:${OMQ_DIR}/jar/qore-jni.jar:. MyQorusClient

See the following section for runtime dependency information for the Qore library when using the Java Qorus client.

Java APIs Based on Qore Functionality

Java libraries for Qorus that depend on the native Qore library and the jni module to provide a wrapper for underlying Qore functionality such as the Java client or test APIs must be run with either the Java runtime option java.library.path or the QORE_LIBRARY environment variable set to the location of the native Qore library.

See also
Using the jni Module From Java for more information