Support Dynamic Pricing in Daemon

[anandrgitnirman]

Curretly all payment checks in Daemon are based on fixed pricing We need to support Dynamic prcing ( i.e compute the price of the service call ) , again this is something best defined by the service provider, however we need to have tool/ support this in Daemon For example you call a PackageA.ServiceA.Method1 ( RequestParams) returns (OutPutParms) Now price to call Method1 depends on what RequestParms are ( ex file size, computational complexity etc) , this is again best determined by the service Provider .

so here is the proposal Use method Level Options to tell the method to call to determine Price PS , this method is expected to have the exact same params as the orginal service call method, but will return a standrad message having price . This price will be used by Daemon to do all the validations

Algorithm

• Compute the PriceDetermination methods mapped or to be called for service methods when Dynamic pricing is enabled
• when a service calls comes in
  • get the pricing method to call
  • use the same i/p to invoke this pricing method
  • get the price to be used
  • perform validations in Daemon
  • if all validtions are passed on payment , make the actual service call

syntax = "proto3";
import "google/protobuf/descriptor.proto";
package escrow;
extend google.protobuf.MethodOptions {
    EstimatePrice my_method_option = 9999127;
}
//In Order to Support Dynamic Pricing , we need a way to indicate which of the methods will need dynamic pricing Support
//By Dynamic Pricing , the pricing of the service call will be a variable of the inputs passed.
//The Service Provider is best positioned to determine this
//The below standards are to be followed
// 1) The Input Message for the Pricing RPC call will be exactly same as the Input Message of the Service Call
// 2) The Output Message for the Pricing RPC MUST return PriceInCogs.
// 3) Define the name of the RPC method to be called using Method Option EstimatePrice

//helps determine which method to call for dynamic pricing,
//format is of type "packageName/serviceName/MethodName", Example :"/example_service.Calculator/estimate_add"
//Daemon will invoke the actual RPC method , but will invoke the method defined in the method options before
//to determine the price that needs to be charged for this call
message EstimatePrice {
    string estimatePriceMethod = 1;
}
//The Value returned by  the Pricing call
message PriceInCogs {
    uint64 price = 1;
}

As an example

syntax = "proto3";
import "google/protobuf/descriptor.proto";
import "github.com/singnet/snet-daemon/pricing/pricing.proto";// you need to import both these protos
package example_service;

message Numbers {
    float a = 1;
    float b = 2;
}
message Result {
    float value = 1;
}
service Calculator {
    rpc add( Numbers) returns (Result) {
        option (my_method_option).estimatePriceMethod = "/example_service.Calculator/estimate_add";
    }
    rpc estimate_add( Numbers) returns (PriceInCogs) {
    }
    rpc sub(Numbers) returns (Result) {}
    rpc mul(Numbers) returns (Result) {}
    rpc div(Numbers) returns (Result) {}
}