Java Native Access - An essential tool in Java tool box

I recently learned about Java Native Access (JNA) and was simply amazed at how easy it is to make native calls. I have used JNI earlier in my projects to access native code, but it is a bit painful experience. JNA makes it a bit easier to make those native calls. I haven't experimented much with passing structures and getting structures (or pointers to structures) as return values. As far as the arguments and return types are one of the primitive types, the interface is very easy to define and use.

Give it a try, you will like it.

Comments

Post a Comment

Popular posts from this blog

The mysterious ORA-03111 error

Recently one of the applications that I developed started throwing exceptions, that had the following message: SQL state [72000]; error code [1013]; ORA-03111: break received on communication channel When I googled around, I couldn't come across anything useful. Sadly enough most of the sites just showed the documentation for that error, without any explanation from anyone experiencing that issues. So here you go, with the best possible explanation that I could come up with. My application sets two things on the connection that is throwing this exception: It sets the fetchSize to be 2500 rows It sets the query timeout to be 10 seconds The database server and the application are separated over a long latency network (actually there is a NetEm box that emulates the long latency between these two boxes) which has a latency characteristic of 50+/-5 milliseconds. This is the whole setup. It is important to understand how the timeout is handled by the Oracle client (in my case JDBC clien...
Read more

Note on allocationSize parameter of @SequenceGenerator while using JPA

I ran into what I thought as an issue while I was using the sequence ID generation strategy in JPA. The JPA provider I am using is Hibernate. I think sharing my experience will save someone some time. To use a sequence (For e.g. Oracle sequence) to generate values and assign them to the ID field of your persistence object, you will following something like this: @Id @Column(name = "ITEM_ID") @GeneratedValue(strategy = GenerationType.SEQUENCE, generator="ItemIdSeqGenerator") @SequenceGenerator(name="ItemIdSeqGenerator", sequenceName="ITEM_ID_SEQ", allocationSize=1) private long itemId; This means the following things: The @Id annotation says that the field itemId is a primary key. The @Column annotation says that the corresponding column in the database is ITEM_ID. The @GeneratedValue says that the value that needs to be populated in the itemId should be generated, while that object is persisted. The strategy to generate the value is to...
Read more

xVM's vboxmanage.exe command

You can view and edit the configuration of your guest OSs using the vboxmanage command. To view the list of guest OSs you have, give the following command: C:\Program Files\Sun\xVM VirtualBox>VBoxManage.exe list vms VirtualBox Command Line Management Interface Version 2.2.2 (C) 2005-2009 Sun Microsystems, Inc. All rights reserved. "MySolaris" {dc6dc85f-5583-4a1b-bf3e-969941a2cd91} "Ubuntu" {eb973bbf-d86e-4579-85eb-6ea2cd12bf95} "Debian" {3e784597-89d8-4f17-90cb-63e866c651a3} "openSUSE" {6862884e-60e1-4c65-8aab-b57ec38a3922} "Debian-Lenny" {4b561432-abac-4a27-a501-b42af956b96b} To view the specific guest, you can use the UUID of the guest. For e.g. C:\Program Files\Sun\xVM VirtualBox>VBoxManage.exe showvminfo eb973bbf-d86e-4579-85eb-6ea2cd12bf95 VirtualBox Command Line Management Interface Version 2.2.2 (C) 2005-2009 Sun Microsystems, Inc. All rights reserved. Name: Ubuntu Guest OS: Ubuntu UUID: eb973bb...
Read more