Creating a module

A module is contained in a directory, which is not necessarily stored under nucentral. For example, the following layout:

mymodule/
  __init__.py
  mymodule.py

In NuCentral configuration, add the following line to section [modules]:

[modules]
mymodule = yes

Value yes allows to control if a module is activated or not.

Initialization file is very simple: __init__.py:

from mymodule import *

Module initialization

When NuCentral loads a module, it imports it as usual (file __init__.py). In a module, two functions are mandatory:

1. function getServiceList, which must return a dictionary of entries using format 'service_name' : function.
2. function getSyncServiceList, which must return a dictionary of entries with the same format as getServiceList, except that this function will declare only synchronous services, i.e executing the code immediately.
3. function getComponentName which returns the name of the component.

NuCentral automatically handles the compoenent registration, and all its services.

For example:

message = "Hello, world"
def getComponentName():
      return "foo"
def getSyncServiceList():
      services_list = dict()
      services_list['print'] = disp;
      services_list['error'] = error;
      return services_list
def disp(*args):
      return message

Using the introspection functions from NuCentral (soap_explore.py in the scripts directory), we obtain the following output:

[+] foo
      print
      error

Calling a service from a client

The component previously described provides a service print, which simply returns the message (ignoring its arguments).

Use the NuCentralServer object to call the service:

import sys
# path to nucentral installation, if needed
sys.path.append("../")
from nucentral import client
from nucentral.client import NuCentralServer
from nucentral.client import methods
url = "https://localhost:8443/SOAP"
_server = NuCentralServer()
_server.connect(url,methods.METHOD_SOAP)
print _server.call("foo","print")

which returns the following output:

Hello, world

Calling a service from another module

When a module wants to call a service from another module, it must call a function which will handle all the work (either a local call, or a SOAP or XML-RPC call if the procedure is present on a distant NuCentral server).

For example:

from nucentral import client
def myservice(*args):
      result = client.Service.callService(component2,service2)
      return result