Overview
Elektron Message API - Java Edition (EMA API) allows developers integrate the EMA Java application with the Apache Log4j which is a de facto standard logging framework for Java-based application at deployment time by using the Simple Logging Facade for Java (SLF4J) API as a facade for logging utility. The previous article shows how to integrate Log4j with EMA Java application in a manual way which is suitable for earlier versions of EMA Java API. However, the API has been mavenized to support Apache Marven and Gradle build tools since Elektron SDK Java version 1.2, therefore this article will show how to integrate your EMA Java 1.3.x application with Log4j in a Maven way.
How to integrate EMA Java Application with Logging Framework in Maven
The Elektron SDK Java are now available in Maven Central Repository. You can define the following dependency configuration in Maven's pom.xml fil to let Maven automatic downloads the EMA Java library for the application.
<dependency>
<groupId>com.thomsonreuters.ema</groupId>
<artifactId>ema</artifactId>
<version>3.3.1.0</version>
</dependency>Note: This article is based on EMA Java version 3.3.1 L1 (Elektron SDK Java Edition 1.3.1). You can change the library version in <version> configuration to match your project.
The above configuration automatic resolves the API dependencies by downloading the following required libraries for the application.

The EMA Java API binds the SLF4J logging mechanism with Java Logging API by default, so Maven automatic downloads slf4j-api and slf4j-jdk14 libraries for the application. Developers need to perform the following steps to integrate the EMA Java Maven application log with Log4j framework.
- Configure pom.xml file's EMA dependency declaration to not load slf4j-jdk14 libary.
- Add SLF4J-Log4j and Log4j dependencies in pom.xml file.
- Configure Log4j configurations file to Java classpath or JVM option.
Maven pom.xml setting for EMA JAva and Log4j
Developers can configure the EMA Java dependency declaration in pom.xml file to exclude the SLF4J-JDK14 library by using Maven Dependency Exclusions feature.
<dependencies>
<dependency>
<groupId>com.thomsonreuters.ema</groupId>
<artifactId>ema</artifactId>
<version>3.3.1.0</version>
<exclusions>
<exclusion>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-jdk14</artifactId>
</exclusion>
</exclusions>
</dependency>
</dependencies>The Log4j 2 framework requires the following dependencies to intergrate with SLF4J framework.
- log4j-api
- log4j-core
- log4j-slf4j-impl
The above dependencies can be configured in the pom.xml file.
<dependencies>
<dependency>
<groupId>org.apache.logging.log4j</groupId>
<artifactId>log4j-api</artifactId>
<version>2.12.1</version>
</dependency>
<dependency>
<groupId>org.apache.logging.log4j</groupId>
<artifactId>log4j-core</artifactId>
<version>2.12.1</version>
</dependency>
<dependency>
<groupId>org.apache.logging.log4j</groupId>
<artifactId>log4j-slf4j-impl</artifactId>
<version>2.12.1</version>
</dependency>
</dependencies>Note: This article is based on Log4j version 2.12.1. You can change the library version in <version> configuration to match your project.
Example Log4j 2 configurations file
The example of Log4j 2 configuration file for EMA Java application is following.
<?xml version="1.0" encoding="UTF-8"?>
<Configuration>
<Appenders>
<Console name="Console" target="SYSTEM_OUT">
<PatternLayout pattern="current date-%d LEVEL-%-5p Thread-[%t] Method-%M() Class name-%C Message-%m%n"/>
</Console>
<File name="File" fileName="../logs/ema_log4j.log" immediateFlush="false" append="false">
<PatternLayout pattern="current date-%d LEVEL-%-5p Thread-[%t] Method-%M() Class name-%C Message-%m%n"/>
</File>
</Appenders>
<loggers>
<Logger name="com.thomsonreuters.ema" level="TRACE"/>
<root level="TRACE">
<appender-ref ref="Console"/>
<appender-ref ref="File"/>
</root>
</loggers>
</Configuration>The above configurations example set the Log4j to print all EMA Java API ("com.thomsonreuters.ema" package) log messages to console and "ema_log4j.log" log file. Please find a full detail of Log4j configuration parameters in Log4j manual page.
Running the application with Log4j configuration
To let the EMA Java application uses Log4j configurations file, developers can add the Log4j configurations file to the Java classpath or set the JVM option -Dlog4j.configurationFilepoints to the log4j2.xml file at runtime. Please note that if you do not build the application in to a single-all-depencies jar file, you need to include the Log4j 2 libraries files in the Java classpath too.
EMA Java application and Log4j Demo
You can download the EMA Java demo examples with Log4j from GitHub page. You can get it via the following git command:
$>git clone git@github.com:Refinitiv-API-Samples/Article.ESDK.Java.SLF4J.git
The demo applications utilize Log4j to manage logs and console messages. The demo examples are following:
- IProvider_App example: OMM Interactive-Provider application.
- Consumer_App example: OMM Consumer application that connects and consumes data from IProvider_App example.
Note: The Consumer_App demo example can be configured to connect to your local TREP server.
Demo log4j configurations file
The demo applications separate the applications logic and EMA Java API log messages to different consoles and log files.
- The IProvider_App application messages are printed in console and provider_log4j.log file.
- The Consumer_App application messages are printed in console and consumer_log4j.log file.
- The EMA Java API logs from both applications are printed in ema_log4j.log file.
The applications just use SLF4J's logger.info() and logger.error() functions in the source codes to set the application messages, then Log4j will do the rest for application based on the following log4j.xml configuration file.
<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="DEBUG">
<Appenders>
<Console name="LogToConsole" target="SYSTEM_OUT">
<PatternLayout pattern="%d Class name-%C Message-%m%n"/>
</Console>
<File name="emaLogFile" fileName="logs/ema_log4j.log">
<PatternLayout>
<Pattern>%d LEVEL-%-5p Thread-[%t] Method-%M() Class name-%C Message-%m%n
</Pattern>
</PatternLayout>
</File>
<File name="consumerLogFile" fileName="logs/consumer_log4j.log">
<PatternLayout>
<Pattern>%d{HH:mm:ss.SSS} [%t] %-5level %logger{36} - %msg%n
</Pattern>
</PatternLayout>
</File>
<File name="providerLogFile" fileName="logs/provider_log4j.log">
<PatternLayout>
<Pattern>%d{HH:mm:ss.SSS} [%t] %-5level %logger{36} - %msg%n
</Pattern>
</PatternLayout>
</File>
</Appenders>
<Loggers>
<!-- avoid duplicated logs with additivity=false -->
<Logger name="com.thomsonreuters.ema" level="trace" additivity="false">
<AppenderRef ref="emaLogFile"/>
</Logger>
<Logger name="com.refinitiv.ema.consumer" level="info" additivity="false">
<AppenderRef ref="LogToConsole"/>
<AppenderRef ref="consumerLogFile"/>
</Logger>
<Logger name="com.refinitiv.ema.provider" level="info" additivity="false">
<AppenderRef ref="LogToConsole"/>
<AppenderRef ref="providerLogFile"/>
</Logger>
</Loggers>
</Configuration>Demo prerequisite
This example requires the following dependencies softwares and libraries.
- Oracle/Open JDK 8 or Oracle JDK 11.
- Apache Maven project management and comprehension tool.
- Internet connection.
Note: The Elektron SDK Java version 1.3.1 (EMA Java 3.3.1) supports Oracle JDK versions 8, 11 and Open JDK version 8. If you are using other verions of Elektron SDK Java, please check the SDK's README.md file regarding the supported Java version.
Running the demo applications
1. Unzip or download the project into a directory of your choice.
2. Enter the ema_example project folder.
3. Run $> mvn package command in a console to build the demo applications into a single-all-depencies esdk131_maven-1.0-SNAPSHOT-jar-with-dependencies.jar file.
4. The applications jar file will be available in the project's target folder.
5. Then you can run IProvider_App demo with the following command:
$>java -Dlog4j.configurationFile=./resources/log4j2.xml -cp .;target/esdk131_maven-1.0-SNAPSHOT-jar-with-dependencies.jar com.refinitiv.ema.provider.IProvider_App6. In order to run Consumer_App demo, open another console for ema_example folder and run the following command:
$>java -Dlog4j.configurationFile=./resources/log4j2.xml -cp .;target/esdk131_maven-1.0-SNAPSHOT-jar-with-dependencies.jar com.refinitiv.ema.consumer.Consumer_AppDemo Example Results
Consumer_App result
16:39:25.607 [main] INFO com.refinitiv.ema.consumer.Consumer_App - Starting Consumer_App application
16:39:28.462 [main] INFO com.refinitiv.ema.consumer.Consumer_App - Consumer_App: Send item request message
16:39:29.452 [pool-3-thread-1] INFO com.refinitiv.ema.consumer.AppClient - Consumer_App.AppClient: Receives Market Price Refresh message
16:39:29.453 [pool-3-thread-1] INFO com.refinitiv.ema.consumer.AppClient - Item Name: /EUR=
16:39:29.453 [pool-3-thread-1] INFO com.refinitiv.ema.consumer.AppClient - Service Name: ELEKTRON_DD
16:39:29.454 [pool-3-thread-1] INFO com.refinitiv.ema.consumer.AppClient - Item State: Open / Ok / None / 'Refresh Completed'
16:39:29.457 [pool-3-thread-1] INFO com.refinitiv.ema.consumer.AppClient - RefreshMsg
streamId="5"
domain="MarketPrice Domain"
solicited
RefreshComplete
state="Open / Ok / None / 'Refresh Completed'"
itemGroup="00 00"
name="/EUR="
serviceId="1"
serviceName="ELEKTRON_DD"
Payload dataType="FieldList"
FieldList
FieldEntry fid="3" name="DSPLY_NAME" dataType="Rmtes" value="/EUR="
FieldEntry fid="15" name="CURRENCY" dataType="Enum" value="840"
FieldEntry fid="21" name="HST_CLOSE" dataType="Real" value="39.0"
FieldEntry fid="22" name="BID" dataType="Real" value="39.9"
FieldEntry fid="25" name="ASK" dataType="Real" value="39.94"
FieldEntry fid="30" name="BIDSIZE" dataType="Real" value="9.0"
FieldEntry fid="31" name="ASKSIZE" dataType="Real" value="19.0"
FieldListEnd
PayloadEnd
RefreshMsgEnd
16:39:29.458 [pool-3-thread-1] INFO com.refinitiv.ema.consumer.AppClient -
16:39:30.455 [pool-3-thread-1] INFO com.refinitiv.ema.consumer.AppClient - Consumer_App.AppClient: Receives Market Price Update message
16:39:30.455 [pool-3-thread-1] INFO com.refinitiv.ema.consumer.AppClient - Item Name: /EUR=
16:39:30.456 [pool-3-thread-1] INFO com.refinitiv.ema.consumer.AppClient - Service Name: ELEKTRON_DD
16:39:30.456 [pool-3-thread-1] INFO com.refinitiv.ema.consumer.AppClient - UpdateMsg
streamId="5"
domain="MarketPrice Domain"
updateTypeNum="0"
name="/EUR="
serviceId="1"
serviceName="ELEKTRON_DD"
Payload dataType="FieldList"
FieldList
FieldEntry fid="22" name="BID" dataType="Real" value="39.91"
FieldEntry fid="25" name="ASK" dataType="Real" value="39.94"
FieldEntry fid="30" name="BIDSIZE" dataType="Real" value="10.0"
FieldEntry fid="31" name="ASKSIZE" dataType="Real" value="19.0"
FieldListEnd
PayloadEnd
UpdateMsgEnd
...IProvider_App result
16:39:09.009 [main] INFO com.refinitiv.ema.provider.IProvider_App - Starting IProvider_App application, waiting for a consumer application
16:39:29.451 [main] INFO com.refinitiv.ema.provider.AppClient - IProvider_App.AppClient: Sent Market Price Refresh messages
16:39:30.453 [main] INFO com.refinitiv.ema.provider.IProvider_App - IProvider_App: Sent Market Price Update message
16:39:31.456 [main] INFO com.refinitiv.ema.provider.IProvider_App - IProvider_App: Sent Market Price Update messageEMA Java result
EMA Java log messages from both demo applications will be in ema_log4j.log file.
2019-10-17 16:39:10,182 LEVEL-TRACE Thread-[main] Method-log() Class name-com.thomsonreuters.ema.access.ConfigErrorTracker Message-loggerMsg
ClientName: EmaConfig
Severity: Trace
Text: reading configuration file [EmaConfig.xml]; working directory is [/home/api/project/slf4j/ema_example]
loggerMsgEnd
2019-10-17 16:39:10,183 LEVEL-TRACE Thread-[main] Method-initialize() Class name-com.thomsonreuters.ema.access.OmmServerBaseImpl Message-loggerMsg
ClientName: Provider_1_1
Severity: Trace
Text: Print out active configuration detail.
itemCountHint: 10000
serviceCountHint: 10000
requestTimeout: 15000
dispatchTimeoutApiThread: 500
maxDispatchCountApiThread: 500
maxDispatchCountUserThread: 500
userDispatch: 0
configuredName: Provider_1
instanceName: Provider_1_1
xmlTraceEnable: false
defaultServiceName: 14002
acceptMessageWithoutAcceptingRequests: false
acceptDirMessageWithoutMinFilters: false
acceptMessageWithoutBeingLogin: false
acceptMessageSameKeyButDiffStream: false
acceptMessageThatChangesService: false
acceptMessageWithoutQosInRange: false
operationModel: 1
directoryAdminControl: 1
dictionaryAdminControl: 1
refreshFirstRequired: true
maxFieldDictFragmentSize: 8192
maxEnumTypeFragmentSize: 128000
loggerMsgEnd
....
2019-10-17 16:39:10,363 LEVEL-TRACE Thread-[main] Method-initialize() Class name-com.thomsonreuters.ema.access.OmmServerBaseImpl Message-loggerMsg
ClientName: Provider_1_1
Severity: Trace
Text: Provider bound on port = 14022.
loggerMsgEnd
2019-10-17 16:39:25,758 LEVEL-TRACE Thread-[main] Method-log() Class name-com.thomsonreuters.ema.access.ConfigErrorTracker Message-loggerMsg
ClientName: EmaConfig
Severity: Trace
Text: reading configuration file [EmaConfig.xml]; working directory is [/home/api/project/slf4j/ema_example]
loggerMsgEnd
2019-10-17 16:39:25,758 LEVEL-TRACE Thread-[main] Method-initialize() Class name-com.thomsonreuters.ema.access.OmmBaseImpl Message-loggerMsg
ClientName: Consumer_1_1
Severity: Trace
Text: Print out active configuration detail.
itemCountHint: 100000
serviceCountHint: 513
requestTimeout: 15000
dispatchTimeoutApiThread: 0
maxDispatchCountApiThread: 100
maxDispatchCountUserThread: 100
userDispatch: 1
configuredName: Consumer_1
instanceName: Consumer_1_1
xmlTraceEnable: false
obeyOpenWindow: 1
postAckTimeout: 15000
maxOutstandingPosts: 100000
userDispatch: 1
reconnectAttemptLimit: -1
reconnectMinDelay: 1000
reconnectMaxDelay: 5000
msgKeyInUpdates: true
directoryRequestTimeOut: 45000
dictionaryRequestTimeOut: 45000
loginRequestTimeOut: 45000
loggerMsgEnd
...
2019-10-17 16:39:25,787 LEVEL-TRACE Thread-[main] Method-<init>() Class name-com.thomsonreuters.ema.access.CallbackClient Message-loggerMsg
ClientName: LoginCallbackClient
Severity: Trace
Text: Created LoginCallbackClient
loggerMsgEnd
2019-10-17 16:39:25,788 LEVEL-TRACE Thread-[main] Method-initialize() Class name-com.thomsonreuters.ema.access.LoginCallbackClient Message-loggerMsg
ClientName: LoginCallbackClient
Severity: Trace
Text: RDMLogin request message was populated with this info:
LoginRequest:
streamId: 1
userName: api
streaming: true
nameType: 1
applicationId: 256
applicationName: ema
position: 127.0.0.1/apis30
loggerMsgEnd
2019-10-17 16:39:25,789 LEVEL-TRACE Thread-[main] Method-<init>() Class name-com.thomsonreuters.ema.access.CallbackClient Message-loggerMsg
ClientName: DictionaryCallbackClient
Severity: Trace
Text: Created DictionaryCallbackClient
loggerMsgEndConclusion
he EMA Java API is implemented on top of SLF4J API as a facade for logging utility. The latest version of API also supports Maven Central Repository. These features allow developers integrate EMA Java application with their prefer Logging framework by changing the repository and log configurations files without touching the application source code.
References
For further details, please check out the following resources:
- Elektron Java API page on the Refinitiv Developer Community web site.
- Simple Logging Facade for Java (SLF4J) website.
- Apache Log4j 2 website.
- Elektron Message API Java Quick Start
For any question related to this article or Elektron Message API page, please use the Developer Community Q&A Forum.