Event Scripting

Revision as of 21:25, 21 July 2016

Event Scripting allows users to write scripts that run when certain system events happen. Scriptable events, a.k.a process events, are "fired" when certain parts of the API are called, externally by clients, or internally by other scripts. Events are generated for all services and most resources defined by those services.

Types of Events

service[.resource].verb[.type]

• service is the API name of the service,
• resource is the optional resource path ('/' replaced with '.') either statically defined, or using replacement parameters within {},
• verb is the HTTP verb used in the request
• type is the type of event, see below.

Below are some example base (not including the type section) event names for various service types.

Database Services

• db.get,
• db._schema.get,
• db._schema.post,
• db._schema.put,
• db._schema.patch,
• db._schema.{table_name}.get,
• db._schema.{table_name}.post,
• db._schema.{table_name}.put,
• db._schema.{table_name}.patch,
• db._schema.{table_name}.delete,
• db._schema.{table_name}.{field_name}.get,
• db._schema.{table_name}.{field_name}.put,
• db._schema.{table_name}.{field_name}.patch,
• db._schema.{table_name}.{field_name}.delete,
• db._table.get,
• db._table.{table_name}.get,
• db._table.{table_name}.post,
• db._table.{table_name}.put,
• db._table.{table_name}.patch,
• db._table.{table_name}.delete,
• db._table.{table_name}.{id}.get,
• db._table.{table_name}.{id}.put,
• db._table.{table_name}.{id}.patch,
• db._table.{table_name}.{id}.delete,

File Services

• files.get,
• files.post,
• files.patch,
• files.delete,
• files.{folder_path}.get,
• files.{folder_path}.post,
• files.{folder_path}.patch,
• files.{folder_path}.delete,
• files.{file_path}.get,
• files.{file_path}.post,
• files.{file_path}.put,
• files.{file_path}.patch,
• files.{file_path}.delete,

HTTP Services

HTTP Services, by default, fire no events unless there are paths defined in the Open-API/Swagger Specification. In that case, events are generated based on calls matching paths defined. myservice.makes.count.get would be generated for a call to GET http://example.com/api/v2/myservice/makes/count.

SOAP Services

SOAP Services fire events based on the methods defined in the given WSDL file. For example, myservice.call_method.post would be generated for a call to POST http://example.com/api/v2/myservice/call_method.

Auth Services

• user.get,
• user.password.post,
• user.profile.get,
• user.profile.post,
• user.register.post,
• user.session.get,
• user.session.post,
• user.session.delete,
• user.custom.get,
• user.custom.post,
• user.custom.patch,
• user.custom.delete,
• user.custom.{id}.get,
• user.custom.{id}.patch,
• user.custom.{id}.delete,

System Resources

The system service generates a lot of events, for example, for the root retrieval of resources...

• system.get

for common resources like admin, app, app_group, custom, cors, roles, services, users...

• system.service.get,
• system.service.post,
• system.service.patch,
• system.service.delete,
• system.service.{id}.get,
• system.service.{id}.patch,
• system.service.{id}.delete,

some others include...

• system.cache.delete,
• system.cache.{service}.delete,
• system.config.get,
• system.config.post,
• system.constant.get,
• system.constant.{type}.get,
• system.environment.get,
• system.event.get,
• system.event.{event_name}.get,
• system.event.{event_name}.post,
• system.event.{event_name}.delete,
• system.service_type.get,
• system.script_type.get,
• system.package.get,
• system.package.post,

Scriptable Events

Scriptable events currently fall under three categories, pre-process, post-process, and queued.

Pre-Process

Following the anatomy of an API call, pre-process scripts are run after authentication and authorization, but before the API call is processed by to the handling service. This allows for the following scenarios...

• interrupting the API call before it is processed by throwing exceptions that are returned to the client, i.e. payload validation failures, etc.,
• modifying the contents, parameters, or headers of the request to change how and/or what is processed, i.e. payload modification, etc. (see allow_event_modification in DreamFactory/Features/Scripting#Resources_Available_To_A_Script)
• perform additional functionality before the call is processed, i.e. external validation, tracking API usage, etc.

Post-Process

Likewise, post-process scripts are run after the API call has been processed by the handling service, but before any final formatting and returning to the client. This allows for the following scenarios...

• modifying the contents, status code, or formatting of the response, i.e. adding related data from other services, or removing sensitive information, etc. (see allow_event_modification in DreamFactory/Features/Scripting#Resources_Available_To_A_Script)
• perform additional functionality before the response is returned to the client, i.e. triggering other services upon success or failure, logging, etc.

Queued (Coming Soon)

Queued scripts on the other hand, do not and can not affect the processing of the original API call. Both the request and response of the event are saved along with the script and queued for later execution.