0. Setup your environment

Before we’re going to start, we should first make sure we have all the requirements available, so first we’re going to install a backend and frontend machine using Setup a development environment.

The development of the services is being done on the developers local machine, so there are some things which need to be installed first.

• Python 2.7.x (available here)

• ValueA framework (install using pip install ValueAframework-<version>-py2-none-any.whl)

• IDE or text editor, we advise using PyCharm

Note

When installing on Windows, there might be some challenges in guiding pip through the process, therefore it’s advisable to first install numpy (pip install numpy) and geos (pip install geos). Precompiled binaries for windows can be found on http://www.lfd.uci.edu/~gohlke/pythonlibs/ in case other components fail to install.

Then we need a new project, which contains at least the following directory structure and files:

.
|-- config
|   |-- log.conf
|   |-- broker.conf
|-- services
|   |-- valuea
|       |-- __init__.py
|       |-- samples
|           |-- __init__.py
|   |-- __init__.py
|   |-- log

All the __init__.py files should be empty files, log.conf should contain a valid log configuration (example below) and broker.conf contains the connectivity settings to RabbitMQ (example also below). As long as we’re not using any databases this should be the basics to get us started.

Note

The empty __init__.py files are used to make python treat directories as packages.

config/log.conf

[loggers]
keys=root,valueamsg,valuea

[handlers]
keys=filehandler,filehandlerValueA,filehandlerMessages

[formatters]
keys=format01,format02,format03

[formatter_format01]
format=%(asctime)s %(name)s pid:%(process)s %(levelname)s %(message)s
class=logging.Formatter

[formatter_format02]
format=%(asctime)s %(name)s %(caller)s pid:%(process)s parent:%(parent_messageid)s message:%(messageid)s user:%(user)s %(levelname)s %(message)s
class=logging.Formatter

[formatter_format03]
format=%(caller)s %(messageid)s %(message)s
class=logging.Formatter

[logger_root]
level=ERROR
handlers=filehandler

[handler_filehandler]
class=FileHandler
level=ERROR
formatter=format01
args=('log/error.log',)

[logger_valuea]
level=DEBUG
handlers=filehandlerValueA
qualname=valuea

[handler_filehandlerValueA]
class=FileHandler
level=DEBUG
formatter=format02
args=('log/backend.log',)

[logger_valueamsg]
level=DEBUG
handlers=filehandlerMessages
qualname=valuea.messages
propagate=0

[handler_filehandlerMessages]
class=FileHandler
level=DEBUG
formatter=format03
args=('log/messages.log',)

config/broker.conf

[queue1.test1]
host=192.168.56.101
username=admin
password=admin
queue=queue1
exchange=default_exchange
routing_key=#
service_paths=services
processcount=1
profile=False

Above example uses 192.168.56.101 as RabbitMQ’s address, replace this with your address.