Invoking external endpoints using JSON is a common activity hence a dedicated JSON adapter, a utility service one's own services can subclass, makes the effort even easier.
Adapter services are intended to use either as pass-through proxy ones or as part of a deeper layer other services invoke, i.e. unless they are proxies, they will not be typically mounted on REST channels.
After subclassing zato.server.service.adapter.JSONAdapter it is possible to configure the service in a declarative manner, without a need to implement the usual self.handle method.
The two required attributes a adapter needs to configure are outconn and method indicating which outgoing REST connection to use and what the HTTP verb is.
A service such as the one below will use self.request.payload as input to be POST-ed to the outgoing connection called billing.eai9.
# -*- coding: utf-8 -*-
# Zato
from zato.server.service.adapter import JSONAdapter
class SetBillingInfo(JSONAdapter):
""" Updates a customer's billing information.
"""
outconn = 'billing.eai9'
method = 'POST'
The following table lists all the configuration parameters.
| Name | Required | Default value | Notes |
|---|---|---|---|
| outconn | Yes | (None) | Name of an outgoing REST connection to use |
| method | Yes | (None) | HTTP method to invoke the external resource with |
| params_to_qs | -- | False | Whether parameters from self.request.payload should form the query string or not |
| force_in_qs | -- | [] | A list of parameters that will always be placed in the query string even if params_to_qs is False |
| load_response | -- | True | Whether the response from the endpoint should be automatically deserialized into a Python object, such as a dictionary |
| params | -- | {} | A dictionary of additional parameters to use when building a request to the endpoint in addition to what has been obtained from self.request.payload |
| apply_params | -- | APPLY_AFTER_REQUEST | Must be either APPLY_AFTER_REQUEST or APPLY_BEFORE_REQEUST from zato.common.ADAPTER_PARAMS. If the former, self.params will take precedence over self.request.payload. The other way around if the latter. |
| raise_error_on | -- | ['4', '5'] | A list of prefixes of status codes returned from the endpoint which will make the adapter raise a zato.common.HTTPException instance. |