(Delphi DLL) Viewing a Simple Three-Step Execution Plan

See more CURL Examples

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.

Note: This example requires Chilkat v11.5.0 or greater.

For more information, see https://www.chilkatsoft.com/curl_dependency_engine.asp

Chilkat for Delphi Downloads Chilkat non-ActiveX DLL for Delphi Chilkat ActiveX DLL for Delphi * The examples here use the non-ActiveX DLL.

uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, JsonObject, HttpCurl;

...

procedure TForm1.Button1Click(Sender: TObject);
var
success: Boolean;
httpCurl: HCkHttpCurl;
targetCurl: PWideChar;
fnName: PWideChar;
planJson: HCkJsonObject;

begin
success := False;

httpCurl := CkHttpCurl_Create();

// The target curl command requires {{order_id}}.
targetCurl := 'curl -X GET https://api.example.com/orders/{{order_id}}';

// Define a helper function that produces order_id from customer_id.
fnName := 'getOrderId';
CkHttpCurl_AddFunction(httpCurl,fnName,'curl -X GET https://api.example.com/order-id?customer={{customer_id}}');
CkHttpCurl_AddOutput(httpCurl,fnName,'order.id','order_id');

// Define a helper function that produces customer_id from account_name.
fnName := 'getCustomerId';
CkHttpCurl_AddFunction(httpCurl,fnName,'curl -X GET https://api.example.com/customer-id?account={{account_name}}');
CkHttpCurl_AddOutput(httpCurl,fnName,'customer.id','customer_id');

// Provide the starting known input.
CkHttpCurl_SetVar(httpCurl,'account_name','acme');

// Examine the execution plan without running any requests.
planJson := CkJsonObject_Create();
CkJsonObject_putEmitCompact(planJson,False);

success := CkHttpCurl_ExaminePlan(httpCurl,targetCurl,planJson);

// Success is expected to be True.
Memo1.Lines.Add('success = ' + IntToStr(Ord(success)));

Memo1.Lines.Add(CkJsonObject__emit(planJson));

// 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": []
//   }]
// }

CkHttpCurl_Dispose(httpCurl);
CkJsonObject_Dispose(planJson);

end;