Subsections
5. TANGO Java API
THIS CHAPTER DOCUMENTS THE JAVA API FOR THE TANGO DATABASE
AND DEVICE SERVERS.
This chapter documents the high level interface for Java.
This java api is based on Jacorb ORB implementation.
The Jacorb and Tango classes are both available in TangORB.jar
file.
The basic philosophy is to have high level classes for the database,
properties, device, group and database object info. Classes also exist
for sending and receiving database or device values.
All classes and data types are defined in fr.esrf.TangoApi
package. Group related classes are in a package called fr.esrf.TangoApi.Group.
Event related classes are in a package called fr.esrf.TangoApi.events
- DeviceData:
- Obect used to send and receive data on device.
- DbDatum:
- Object used to put or get properties on database.
- DbDevInfo:
- Object used to read device information on database.
- DbDevImportInfo:
- Object used to read imported device information
on database.
- DbDevExportInfo:
- Object used to read exported device information
on database.
- CallBack:
- Object called at asynchronous call reply
- CmdDoneEvent:
- Object to pass asynchronous command reply data
to a CallBack object.
- ReadAttrEvent:
- Object to pass asynchronous read_attribute reply
data to a CallBack object.
- AttrWrittenEvent:
- Object to pass asynchronous write_attribute
reply data to a CallBack object.
- DeviceProxy:
- Device access (aggregates DbDevice class).
- Group:
- Multiple device access class
- Database:
- Direct access to TANGO database.
- DbClass:
- Class properties access to TANGO database.
- DbServer:
- Server properties access to TANGO database.
- DbDevice
- Device properties access to TANGO database.
For the device and database classes, most methods throw a DevFailed
exception in case of error. See Writing a TANGO Device Server
chapter Reporting Errors (![[*]](crossref.png)
) , except
those which specified.
In opposite, for the data object classes, only the specified method
throw DevFailed exception in case of error.
The reason field could be set to:
- TangoApi_TANGO_HOST_NOT_SET : The TANGO_HOST environment
variable has not been set or has been set with a syntax error.
- TangoApi_DATABASE_CONNECTION_FAILED : The database server
cannot be connected (bad TANGO_HOST or database server stopped).
- TangoApi_CANNOT_IMPORT_DEVICE : The device is exported but
cannot be connected.
- TangoApi_DEVICE_NOT_EXPORTED : The device has not be exported.
Tango client written using Java language needs release 1.5.0
(or above) of the Java environment.
To correctly compile a Java Tango client, the CLASSPATH
environment variable must be set to :
- The jar file with all the Tango, TangoDs, TangoApi and Jacorb package
classes. This file is named TangORB.jar
- The jar file with all the JDK classes (not always necessary, could
be implicit)
- Your own package directory
For UNIX like operating system, setting environment variable is done
with the export or setenv command depending on the shell
used. For Windows, setting environment variable is possible from the
control panel.
The client/server timeout as been fixed by default to 3000 milliseconds
but it can be set to another value a startup using TANGO_TIMEOUT
environement variable.
eg : java -DTANGO_HOST=hal:20000 -DTANGO_TIMEOUT=5000 mypackage.MyClient
Will start MyClient class using the database server running
on the host named hal on port 20000 with a command timeout
of 5 seconds.
The Tango Java API documentation is now managed using the Java tool
javadoc and is available online at
http://www.esrf.eu/computing/cs/tango/tango_doc/kernel_doc/tango_java_api/classes/index.htmlTango Java API reference documentation
Emmanuel Taurel
2013-06-27
![\includegraphics[width=0.8\textwidth]{java_api/picture/architecture}](img5.png)