| Author: | Jesús Arias Fisteus |
|---|
Ztreamy is a middleware for publishing streams of semantically-described events on the Web. It is implemented on top of the Tornado Web Server. This guide describes how to install the software, start a simple stream and consume its events.
This guide describes how to install Ztreamy in Linux systems. It should work also in Windows, but we have not yet tested it.
In order to install Ztreamy, you need an installation of Python 2.7. Python 3 is not backwards compatible and is not supported yet. Python is installed by default in many Linux distributions. Therefore, its version 2.7 is probably already installed in your system.
You can install Ztreamy globally in your Linux installation, or in a local directory, using virtualenv. The latter is probably better if you just want to try Ztreamy, because this way it can be safely removed just by removing the virtualenv directory.
First, install the virtualenv package using the package manager of your Linux distribution. For example, in Debian and Ubuntu:
sudo apt-get install python-virtualenv
Ztreamy requires the Python header files and the libcurl with its header files to be installed in your system. In Debian and Ubuntu they are packaged as python-dev, libcurl3 and libcurl4-openssl-dev respectively:
sudo apt-get install python-dev libssl-dev curl libcurl3 libcurl4-openssl-dev
Now, somewhere in your user account, create the virtualenv directory in which Ztreamy will be installed. For example, if you call the directory ztreamy-venv:
virtualenv ztreamy-venv source ztreamy-venv/bin/activate
The first command creates the virtual environment and installs Python inside it. The second command makes this virtual environment the default in the current terminal. The second command has to be executed every time a new terminal is opened for using Ztreamy.
Finally, you can install Ztreamy from the PyPI software repository:
pip install ztreamy
If you already have an installation of Ztreamy, pip can also upgrade it to the latest release:
source ztreamy-venv/bin/activate pip install --upgrade ztreamy
In order to try your installation of Ztreamy, you'll create a new stream, run a client to consume it and run a source that publishes data through the stream.
First, remember that, if you have installed Ztreamy inside a virtualenv environment, it must be activated for every terminal in which you run Ztreamy commands. Enter within every terminal the command:
source ztreamy-venv/bin/activate
Then, run a server that publishes a stream at TCP port 9000:
python -m ztreamy.server --port=9000
In another terminal, launch a client to listen to that stream:
python -m ztreamy.client http://localhost:9000/events/stream
Finally, you need an event source that sends events to the server in order to be published in the stream. Ztreamy integrates a tool that creates events for testing purposes. Enter in another terminal:
python -m ztreamy.tools.event_source --distribution="exp[3]" http://localhost:9000/events/publish
It will create and send events to the server. The time between events follows an exponential distribution with an average of 3 seconds. You should see the events arriving at the terminal in which the client is running.
Alternatively to the console client, there is an integrated JavaScript client that allows you to watch the stream from a web browser. Access in your browser the URL http://localhost:9000/events/dashboard.html. The page will show the latest events in the stream and update as soon as new events are published in the stream.
In order to stop the framework, type control-c in the terminals of the event source and the server. The client will stop automatically when the server closes.