C++

Impossible Execution Plan

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This example demonstrates what happens when it is not possible to construct an execution plan due to missing dependencies.

The target curl command requires a {{drive_id}} value. However, no variable named drive_id has been defined, and no helper function is registered that can produce it. Although a helper function (getSite) is defined, it only produces site_id, which does not satisfy the requirement.

When ExaminePlan is called, it reports that the execution plan cannot be created because a required input is missing and no function exists to provide it.

When DoYourThing is called, it fails for the same reason. The failure is not due to a network or HTTP error, but because the dependency graph cannot be resolved. The FailReason property indicates this condition with a specific error code.

This example highlights that for an execution plan to be valid, every required input must either:

• Already have a defined value, or
• Be producible by a defined curl function with resolvable inputs

If neither condition is met, the system correctly detects the unresolved dependency and prevents execution.

C++

#include <CkHttpCurl.h>
#include <CkJsonObject.h>

void ChilkatSample(void)
    {
    bool success = false;

    CkHttpCurl httpCurl;

    // The final curl command we want to execute.
    // It depends on {{drive_id}}, which is not yet known.
    const char *targetCurl = "curl -X GET https://graph.microsoft.com/v1.0/drives/{{drive_id}}/root/children";

    // Define a helper function that can produce drive_id.
    // This function lists drives for a given site, which requires {{site_id}}.
    const char *fnName = "getDrives";
    httpCurl.AddFunction(fnName,"curl -X GET https://graph.microsoft.com/v1.0/sites/{{site_id}}/drives");

    // Define the output of getDrives.
    // The JSON response contains an array named "value".
    // We take the first element (value[0]) and extract its "id" as drive_id.
    const char *jsonPath = "value[0].id";
    httpCurl.AddOutput(fnName,jsonPath,"drive_id");

    // drive_id depends on site_id, which is also not yet known.
    // Define another helper function to obtain site_id.
    fnName = "getSite";
    httpCurl.AddFunction(fnName,"GET https://graph.microsoft.com/v1.0/sites/root:/sites/{{site_name}}");

    // Map the "id" field from the getSite response to the variable site_id.
    jsonPath = "id";
    httpCurl.AddOutput(fnName,jsonPath,"site_id");

    // Provide the initial known input.
    // site_name is the starting value that allows the dependency chain to be resolved.
    httpCurl.SetVar("site_name","test");

    // ----------------------------------------------------------------------------------------------------------------------
    // Configure OAuth2 authentication using the client credentials flow.
    // Secrets (client_id, client_secret, token_endpoint) are retrieved from the
    // local secrets manager because EnableSecrets is enabled.
    CkJsonObject jsonOAuth2;
    jsonOAuth2.put_EnableSecrets(true);
    jsonOAuth2.UpdateString("oauth2.client_id","!!sharepoint|oauth2|client_id");
    jsonOAuth2.UpdateString("oauth2.client_secret","!!sharepoint|oauth2|client_secret");
    jsonOAuth2.UpdateString("oauth2.scope","https://graph.microsoft.com/.default");
    jsonOAuth2.UpdateString("oauth2.token_endpoint","!!sharepoint|oauth2|token_endpoint");
    httpCurl.SetAuth(jsonOAuth2);
    // ----------------------------------------------------------------------------------------------------------------------

    // Execute the target curl command.
    // Internally, the system will:
    // 
    // 1) Detect that {{drive_id}} is required but not defined.
    // 2) Find that "getDrives" can produce drive_id.
    // 3) Detect that getDrives requires {{site_id}}, which is also not defined.
    // 4) Find that "getSite" can produce site_id.
    // 5) Verify that getSite requires {{site_name}}, which is already known.
    // 6) Build a multi-step execution plan:
    //      - First:  run getSite (produces site_id)
    //      - Second: run getDrives (produces drive_id)
    //      - Third:  run the target curl (uses drive_id)
    success = httpCurl.DoYourThing(targetCurl);
    if (success == false) {
        std::cout << httpCurl.lastErrorText() << "\r\n";
        return;
    }

    // Retrieve and display the HTTP response status code.
    int statusCode = httpCurl.get_StatusCode();
    std::cout << "response status code: " << statusCode << "\r\n";

    // Load and display the JSON response from the final curl command.
    CkJsonObject responseJson;
    responseJson.put_EmitCompact(false);
    httpCurl.GetResponseJson(responseJson);
    std::cout << responseJson.emit() << "\r\n";
    }