javakdb
KDB+ IPC interface for the Java programming language. This will allow your application to
- query kdb+
- subscribe to a kdb+ publisher
- publish to a kdb+ consumer
- serialize/deserialize kdb+ formatted data
- act as a server for a kdb+ instance
Releases
Latest release can be downloaded here. The github master branch will contain the latest development version for testing prior to release (may contain planned major version changes).
Documentation
docs
folder.
Building from source
Java 1.8 (and above) is recommended. Please ensure that your JAVA_HOME
environment variable is set to the version of Java you have installed (or the one preferred if you have multiple versions).
You will also need Apache Maven installed. Run the following to check you have it set up and configured correctly
mvn -version
In order to build the library, run the following within the directory where the pom.xml
file is located (from the downloaded source).
mvn clean compile
If you wish to deploy the library to your machines local repository, in order to be used by other maven projects on your machine, run the following
mvn clean install
Please refer to the Apache Maven documentation for further details
Code examples
Supplied with the code is a series of code examples. The following describes each with an example of how to run from Maven (note: Maven is not required to run the applications, but used here for convenience).
mvn clean install
should be performed prior to running.
GridViewer
Creates a Swing GUI that presents the contents of a KDB+ table (Flip). It shows the mapping of the Flip class to a Swing TableModel. The contents of the table are some random data that we instruct KDB+ to generate.
Prerequisite:
- a kdb+ server running on port 5001 on your machine i.e.
q -p 5001
Run command:
mvn exec:java -pl javakdb-examples -Dexec.mainClass="com.kx.examples.GridViewer"
QueryResponse
Instructs the remote kdb+ process to execute q code (kdb+ native language) and receives the result. The same principle can be used to execute q functions. Example of a sync request.
Prerequisite:
- a kdb+ server running on port 5001 on your machine i.e.
q -p 5001
Run command:
mvn exec:java -pl javakdb-examples -Dexec.mainClass="com.kx.examples.QueryResponse"
SerializationOnly
Example of code that can be used to serialize/deserialize a Java type (array of ints) to kdb+ format.
Run command:
mvn exec:java -pl javakdb-examples -Dexec.mainClass="com.kx.examples.SerializationOnly"
Server
Creates a Java app that listens on TCP port 5010, which a kdb+ process can communicate with. It will echo back sync messages and discard async messages. The following is an example of running kdb+ from the same machine (i.e. running the q executable and typing commands at the q prompt) that will communicate with the Java server.
q
q)h:hopen `::5010
q)h"hello"
q)neg[h]"hello"
Run command:
mvn exec:java -pl javakdb-examples -Dexec.mainClass="com.kx.examples.Server"
Feed
Example of creating an update function remotely (to capture table inserts), along with table creation and population of the table. Table population has an example of single-row inserts (lower latency) and bulk inserts (better throughput and resource utilization).
Prerequisites:
- a kdb+ server running on port 5010 on your machine i.e.
q -p 5010
. - as this example depends on a
.u.upd
function being defined and a table namemytable
pre-existing, you may wish to run the following within the kdb+ server (in normal environments, these table and function definitions should be pre-created by your kdb+ admin).
q).u.upd:{[tbl;row] insert[tbl](row)}
q)mytable:([]time:`timespan$();sym:`symbol$();price:`float$();size:`long$())
Run command:
mvn exec:java -pl javakdb-examples -Dexec.mainClass="com.kx.examples.Feed"
TypesMapping
Example app that creates each of the kdb+ types in Java, and communicates with kdb+ to check that the type has been correctly matched with its q type (kdb+ default language). Prints the Java type and corresponding q type.
Prerequisite:
- a kdb+ server running on port 5010 on your machine i.e.
q -p 5010
.
Run command:
mvn exec:java -pl javakdb-examples -Dexec.mainClass="com.kx.examples.TypesMapping"
Subscriber
Example app that subscribes to real-time updates from a table that is maintained in kdb+.
Prerequisite:
- a kdb+ server running on port 5010 on your machine. The instance must have the
.u.sub
function defined. An example of.u.sub
can be found in KxSystems/kdb-tick, an example tickerplant. You can execute this tickerplant process by runningq tick.q
(the default port is set to 5010).
Run command:
mvn exec:java -pl javakdb-examples -Dexec.mainClass="com.kx.examples.Subscriber"