Visual FoxPro

Viewing a Simple Three-Step Execution Plan

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This example demonstrates a straightforward, valid dependency chain that results in a three-step execution plan. The goal is not to execute the requests, but to inspect how the plan is constructed using ExaminePlan.

The target curl command requires {{order_id}}. A helper function is defined to produce order_id, but it depends on customer_id. Another helper function produces customer_id, which depends on account_name.

Because account_name is provided as a known input, the dependency chain can be fully resolved:

• customer_id is obtained from account_name
• order_id is obtained from customer_id
• The target curl command uses order_id

When ExaminePlan is called, it builds and returns a three-step execution plan showing the order in which each function would be executed.

Visual FoxPro

LOCAL lnSuccess
LOCAL loHttpCurl
LOCAL lcTargetCurl
LOCAL lcFnName
LOCAL loPlanJson

lnSuccess = 0

loHttpCurl = CreateObject('Chilkat.HttpCurl')

* The target curl command requires {{order_id}}.
lcTargetCurl = "curl -X GET https://api.example.com/orders/{{order_id}}"

* Define a helper function that produces order_id from customer_id.
lcFnName = "getOrderId"
loHttpCurl.AddFunction(lcFnName,"curl -X GET https://api.example.com/order-id?customer={{customer_id}}")
loHttpCurl.AddOutput(lcFnName,"order.id","order_id")

* Define a helper function that produces customer_id from account_name.
lcFnName = "getCustomerId"
loHttpCurl.AddFunction(lcFnName,"curl -X GET https://api.example.com/customer-id?account={{account_name}}")
loHttpCurl.AddOutput(lcFnName,"customer.id","customer_id")

* Provide the starting known input.
loHttpCurl.SetVar("account_name","acme")

* Examine the execution plan without running any requests.
loPlanJson = CreateObject('Chilkat.JsonObject')
loPlanJson.EmitCompact = 0

lnSuccess = loHttpCurl.ExaminePlan(lcTargetCurl,loPlanJson)

* Success is expected to be 1.
? "success = " + STR(lnSuccess)

? loPlanJson.Emit()

* Expected result:
* 
* {
*   "plan": [{
*     "function": "getCustomerId",
*     "inputs": ["account_name"],
*     "outputs": ["customer_id"]
*   },{
*     "function": "getOrderId",
*     "inputs": ["customer_id"],
*     "outputs": ["order_id"]
*   },{
*     "function": "targetCurl",
*     "inputs": ["order_id"],
*     "outputs": []
*   }]
* }

RELEASE loHttpCurl
RELEASE loPlanJson