Referencing Variables
Orchestrating a composite application flow and configuring connectors and processors involve various inputs, outputs, and configurations, which can be referenced as variables when you edit and design a composite application to create efficiency.
Variables of composite applications are classified as system, node, and custom variables. Variables with the same name are prioritized as follows: system variable > node variable > custom variable.
System Variables
System variables indicate system parameters or specific outputs of some connectors. Table 1 lists the system variables for composite applications.
Variable |
Description |
---|---|
step_execution_time |
Execution duration of the previous node, in milliseconds. |
response_code |
Response code of the previous HTTP request node. |
selected_row_count |
Number of data records queried in the previous database node. Only MySQL, Gauss 200, PostgreSQL, Oracle, SQL Server, and Db2 databases are supported. |
updated_row_count |
Number of data records that are inserted, updated, and deleted in the previous database node. Only MySQL, Gauss 200, PostgreSQL, Oracle, SQL Server, and Db2 databases are supported. |
loop_index |
Previous loop node; index of the current loop; the value starts from 0. |
loop_size |
Total number of loops in the previous loop node. |
split_index |
Previous splitter node; index of the current data block during data splitting; the value starts from 0. |
split_size |
Number of data splits on the previous splitter node. |
split_complete |
Whether data splitting is complete in the previous splitter node. |
Node Variables
The execution result of the previous node can be used as a node variable and referenced by subsequent nodes, such as the request body of an OpenAPI, database query result, and HTTP request result.
Node variable reference mode: ${payload}
If the execution result is an object, such as a JSON or XML object, use ${payload.id} or ${payload[0].id} to reference certain data in the execution result.
Example:
If the response body received by an HTTP request node is in JSON format as follows, use ${payload} to reference the JSON data, ${payload.id} to reference the value 00000000, and ${payload.data[0].value} to reference the value x.
{ "id":"00000000", "name":"sample01", "data":[ { "id":1, "value":"x" }, { "id":2, "value":"y" }, { "id":3, "value":"z" } ] }
Custom Variables
Custom variables can be referenced in subsequent nodes, and include the following items: variables added when configuring variables, request parameters added in the OpenAPI and the variable assignment nodes, and output variables configured in the script node.
Custom variable reference mode: ${variable name/parameter name}
- Adding variables on the canvas page
- Log in to the new ROMA Connect console.
- In the navigation pane on the left, choose Composite Applications. On the page displayed, click the target composite application.
- Click on the composite application and choose Modify to enter the canvas page.
- Click Variable on the top of the page.
- In the pop-up box displayed, click Add.
Table 2 Configure variables Parameter
Description
Variable
Enter a variable name to be referenced.
Type
Data type of the variable: string, integer, long integer, decimal, boolean, and password.
Value
Enter the value of the variable.
Scope
Select the effective scope of the variable: global (all composite applications); current composite application.
Description
Enter a description of the variable.
- Click Save.
- Adding request parameters in the OpenAPI node
For details, see OpenAPI.
- Adding variables in the variable assignment node
For details, see Variable Assignment.
- Configuring output variables in the script processing node
For details, see Script.
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