14. Backend / Services

14.1 Intro

To exchange data with backend systems the x0-system offers various methods to choose from.

• Service Connector

• Source Data Objects

• Global Data Storage

The next chapters describe all methods in detail and which method is best suited to a specific application.

14.2 ServiceConnector

A ServiceConnector object defines where to get the backend data from and when.

• Backend Service URL

• Occurring Events which trigger Data Load

Now after a ServiceConnector has been configured in object.json, it must be activated by pointing the DestinationObjects RefID to the ServiceConnector ObjectID in skeleton.json.

After it has been connected, any systems fired event will cause the connected service to re-trigger data load.

14.2.1. Object Properties

Object Type Div Attributes

Property	Value(s)	Description
OnEvent	JS Object	Event Properties

14.2.2. Event Properties

Object Type Div Attributes

Property	Value(s)	Description
Events	Array of EventIDs	Listen to given Events
ServiceCall	Backend Script	Call Backend Script on raised Event(s)

14.2.3. object.json

Define ServiceConnector metadata in object.json.

"TestConnector1":
{
        "Type": "ServiceConnector",
        "Attributes":
        {
                "OnEvent":
                {
                        "Events": [ "TestEvent" ],
                        "ServiceCall": "python/getData.py"
                }
        }
}

14.2.4. skeleton.json

Connect as ParentObject in skeleton.json.

"Screen1":
[
        {
                "TestConnector1":
                {
                        "RefID": "Screen1"
                }
        },
        {
                "TestObject1":
                {
                        "RefID": "TestConnector1"
                }
        }
]

14.3. Source Data Objects

x0-source-data-objects feature is a very smart way to control which data will be sent to the backend.

Just reference multiple x0-system-objects and its realtime data will be sent to the backend service.

The following sub-chapters describe how to use SrcDataObjects JSON format in detail.

Note

x0-source-data-objects are not only usable in combination with

service connector, also buttons support the feature.

14.3.1. Global Objects Array

"SrcDataObjects":
[
        "ObjectID1",
        "ObjectID2",
        "ObjectID3"
]

14.3.2. Hardcoded Values

"SrcDataObjects":
{
        "Dummy":
        {
                "Type": "HardcodedValues",
                "Values": {
                        "LimitRows": 20
                }
        }
}

14.3.3. Global Object

"SrcDataObjects":
{
        "$ObjectID":
        {
                "Type": "GlobalObject"
        }
}

14.3.4. Chaining Object Types

"SrcDataObjects":
{
        "$ObjectID":
        {
                "Type": "GlobalObject"
        },
        "Dummy":
        {
                "Type": "HardcodedValues",
                "Values": {
                        "LimitRows": 10
                }
        }
}

14.4. Global Data

It is possible to store global data (var / value pairs) in the following global data spaces:

• Global Data

• Screen Global Data

14.4.1. Load Global Data

x0-global-data will be loaded by x0-preload-script at x0-init.

INSERT INTO system.config (app_id, config_group, "value") VALUES ('appid', 'preload_script', '"InitSystem.py"');
INSERT INTO system.config (app_id, config_group, "value") VALUES ('appid', 'preload_var', '["GlobalVar1"] = "ret_var1"');
INSERT INTO system.config (app_id, config_group, "value") VALUES ('appid', 'preload_var', '["GlobalVar2"] = "ret_var2"');
INSERT INTO system.config (app_id, config_group, "value") VALUES ('appid', 'preload_var', '["GlobalVar3"] = "ret_var3"');

14.4.2. Pass Screen Global Data

To pass values from x0-screen-global-data to backend using x0-source-data-objects …

"SrcDataObjects":
{
        "$ObjectID":
        {
                "Type": "ScreenGlobalVar",
                "ScreenID": "Screen1"
        }
}

14.5. Notify Indicator

To provide the user with status information (notify) a notification-indicator per backend service call is configurable.

Add a notify indicator by adding “Notify” attribute to x0-button-type like shown in the following example.

"ButtonSubmit": {
        "Type": "Button",
        "Attributes": {
                "TextID": "TXT.BUTTON.SUBMIT",
                "Style": "btn btn-primary w-100 mt-3",
                "OnClick": "/python/example-service.py",
                "SrcDataObjects": [
                        "FormfieldList1",
                        "FormfieldObject1",
                        "FormfieldObject2"
                ],
                "Notify": {
                        "ID": "SubmitIdentifier",
                        "DisplayHeaderID": "TXT.NOTIFY.EXAMPLE"
                }
        }
}

14.6. AAA / Authentication

Currently x0-system only supports certificate based (Apache2 / ingress-nginx) authentication.

Especially when using decentralized / multiple application servers it is strongly advised to integrate an external SSO solution.

For authentication to work correctly x0-preload-script must be set up with the correct x0-preload-vars UserID and UserSession.

INSERT INTO system.config (app_id, config_group, "value") VALUES ('appid', 'preload_script', '"InitSystem.py"');
INSERT INTO system.config (app_id, config_group, "value") VALUES ('appid', 'preload_var', '["UserID"] = "ret_user_id"');
INSERT INTO system.config (app_id, config_group, "value") VALUES ('appid', 'preload_var', '["UserSession"] = "ret_user_session"');

Internally x0-system authentication data will be stored in the following global variables.

sysFactory.sysUserID
sysFactory.sysSessionValue

Warning

Also x0-messaging component relies on setting UserSession the correct way.