qJava and Publisher

Community Support
1

I’m trying to run the publisher posted on

https://github.com/exxeleron/qJava/blob/master/src/sample/java/Publisher.java

and I’m getting a very generic error

Press <ENTER> to close application
com.exxeleron.qjava.QException: .u.upd
    at com.exxeleron.qjava.QReader.readError(QReader.java:409)
    at com.exxeleron.qjava.QReader.readObject(QReader.java:189)
    at com.exxeleron.qjava.QReader.read(QReader.java:99)
    at com.exxeleron.qjava.QBasicConnection.sync(QBasicConnection.java:159)
    at PublisherTask.run(Publisher.java:74)
    at java.lang.Thread.run(Thread.java:744)

Anyone seen this? I wish there it has more detail. My Q connection is running on port 5001 and seems to be functioning.

2

it probably expects the remote process to have the function .u.upd defined, which publishes the data to subcribers.

See

http://code.kx.com/wiki/Startingkdbplus/tick

To get you going, and just print the received data on the kdb+ console, define it as

q).u.upd:{0N!(x;y);}

3

That worked! Just a follow up question. Since the ticker subscriber is too complicated for what I want to do, how would you define the u.upd function to write to disk every time it’s called. My file is

q)select from `:dsPricing

id date open close high low volume

Thanks.

4

if you have no symbols in the data, then upsert to the splayed table

.u.upd:{`:dsPricing/ upsert y;}

but this is not suitable for frequent updates; for that you should append in memory, and flush to disk at suitable intervals - e.g. 30 seconds.