Saturday, April 18, 2015

Docker: OpenDayLight (ODL)

I have always wanted to learn more about Software Defined Network (SDN) when I first heard about it from a colleague (now ex-colleague) about 2 years ago.

However, I have been really busy (a.k.a lazy) with work and family. Not until recently when I stumbled upon an interesting opportunity that drove me to take a peek at it.

Ok, the first big question is "OpenFlow or OpenDayLight"? Since I do not have a lot of time to perform research on their respective strengths and weaknesses, I have resorted to a very "scientific" way to choose among the two. In the end, I chose OpenDayLight because (wait for it...) I prefer their website :).

Since I am a big fan of Docker, it doesn't make sense for me to not install OpenDayLight on Docker. A quick google landed me with this. I am not interested in Debian, so I made some changes to the Dockerfile to switch the base image to Centos 6.6.

FROM centos:6.6

# Install required software (170MB)
RUN yum update -y && yum install -y tar wget java-1.7.0-openjdk

# Download and install ODL
RUN mkdir opendaylight

RUN wget -q "" && \
    tar -xf distribution-karaf-0.2.3-Helium-SR3.tar.gz -C opendaylight --strip-components=1 && \
    rm -rf distribution-karaf-0.2.3-Helium-SR3.tar.gz

EXPOSE 162 179 1088 1790 1830 2400 2550 2551 2552 4189 4342 5005 5666 6633 6640 6653 7800 8000 8080 8101 8181 8383 12001

WORKDIR /opt/opendaylight
ENV JAVA_HOME /usr/lib/jvm/jre-1.7.0-openjdk.x86_64
CMD ["./bin/karaf", "server"]

(i) My test shows that Java 8 is currently not supported and will give weird Java NullPointerException while executing command.
(ii) You can download the Dockerfile here.

By executing "docker build -t opendaylight:helium ." in the directory where the Dockerfile is stored, I ended up with a Docker image that contains OpenDayLight.

OpenDayLight on Docker

After starting the container using "docker run" command (refer to the above screenshot), it is time to SSH connect to it and install some ODL components.

This can be achieved by using the Karaf client (download).

Connect to the ODL container through Karaf client
To list all supported features, you can execute the "feature:list" command.

List all supported features
To list currently installed features, you can use the "feature:list -i" command.

Default installed features
To install some basic features, you can execute "feature:install odl-restconf odl-l2switch-switch odl-mdsal-apidocs odl-dlux-core".

Install some basic features
Now, you can proceed to login to OpenDayLight User Experience (DLUX) using URL "<IP of the Docker container>:8181/dlux/index.html.
The default user ID and password are "admin" and "admin" respectively.

DLUX login page
Voila, you are in!

DLUX login page
To learn ODL further, you can download its documentation from this page.

I am still far from really knowing how to use ODL properly. I might even explore OpenFlow one day.

Anyway, I had fun trying it out and hope that you would too!

Sunday, April 12, 2015

Java: Stream Control Transmission Protocol (SCTP)

If you have not heard about SCTP, don't fret! Me neither, until recently.

For a good explanation about SCTP, you can read this and this and this. In short, SCTP is basically TCP on steroids!

People who knows me well knew that I am always curious about new technology or technology new to me (sorry if I confuse you :).

How can I miss the chance to explore SCTP futher? Of course, the language of choice would be Java - still my favorite language after all these years.

First, I created the SctpServer class to serve as a SCTP server.
Next, I created the SctpClient class to serve as the SCTP client that will connect to multiple SCTP servers started on different ports (same host in this case) through a single socket (YES, you read it right, single socket!).

Two SctpServers listening on port 12000 and 12001. An SCTP client sends message to them on the same socket.
From the image above, you can see that there are 2 SctpServer listening on port 12000 and 12001 respectively.

Once the ScptClient connects to them and send them messages, you can see both servers reported that the connection came from port 43975 with stream number of 0 (SctpServer that listens on port 12000) and 1 (SctpServer that listens on port 12001) respectively.

SctpClient uses SctpMultiChannel for its communication.

Now, if you take a look at the codes for SctpClient, there is no "connect" statement at all. That is because a new association will automatically be created for every "send" command. [reference]

The destination of your message/data is now encapsulated in the MessageInfo object.

If you have the interest to explore SCTP further, you can download the sample codes here.

Enjoy hacking!

Wednesday, April 8, 2015

Docker User Group Malaysia

I created the Docker User Group Malaysia on Facebook a few months ago.

The intention is to share information and knowledge with all Docker users within Malaysia.

From 2 members (myself and a colleague of mine), it has now grown to 8 members (some nice folks from Mindvalley).

If you are interested to join or learn more about Docker, you can visit this Facebook group anytime!

Monday, April 6, 2015

Apache Storm: HBase Bolt

Starting with version 0.9.2-incubating, Storm included support for HBase as bolt. You no longer need to seek third party packages to do that, which is a great news!

To refer to the APIs and documentation, you can go here.

I have coded a simple Storm application that takes Kafka as spout and HBase as bolt. In other words, the application will get its data from Kafka and then write to HBase.

One interesting item within Apache Storm is stream grouping (how tuples produced by spouts will be handled by available bolts). To read more about stream grouping, you can refer here.

Lastly, if you want to try it out yourself, you can download the sample codes here.

Storm UI that shows Kafka spout and HBase bolt processing