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java ipc examples for kdb+

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 5010 on your machine i.e. q -p 5010

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 5010 on your machine i.e. q -p 5010

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 name mytable 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 running q tick.q (the default port is set to 5010).

Run command:

mvn exec:java -pl javakdb-examples -Dexec.mainClass="com.kx.examples.Subscriber"