simulateTransaction

​

Parameters

​

Response

​

Code Examples

​

Basic Request

curl https://rpc.orbitflare.com -X POST -H "Content-Type: application/json" -d '{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "simulateTransaction",
  "params": [
    "4hXTCkRzt9WyecNzV1XPgCDfGAZzQKNxLXgynz5QDuWWPSAZBZSHptvWRL3BjCvzUXRdKvHL2b7yGrRQcWyaqsaBCncVG7BFggS8w9snUts67BSh3EqKpXLUm5UMHfD7ZBe9GhARjbNQMLJ1QD3Spr6oMTFNhyKNMr3WNFCrXgDS7uV7u",
    {
      "sigVerify": false,
      "commitment": "confirmed",
      "encoding": "base64"
    }
  ]
}'

​

Using web3.js

import { Connection, Transaction, PublicKey, SystemProgram } from '@solana/web3.js';

const connection = new Connection('https://rpc.orbitflare.com');

// Create and simulate transaction
const transaction = new Transaction().add(
  SystemProgram.transfer({
    fromPubkey: new PublicKey('83astBRguLMdt2h5U1Tpdq5tjFoJ6noeGwaY3mDLVcri'),
    toPubkey: new PublicKey('J7rBdM6AecPDEZp8aPq5tPmsPzPhQG4HD6YtAcQBDfJj'),
    lamports: 1000000000
  })
);

const simulation = await connection.simulateTransaction(transaction);
console.log('Simulation result:', simulation);

// Simulate transaction with analysis
async function simulateTransactionWithAnalysis(
  transaction: Transaction,
  config: { 
    sigVerify?: boolean;
    commitment?: string;
    replaceRecentBlockhash?: boolean;
  }
) {
  const simulation = await connection.simulateTransaction(transaction, config);
  
  return {
    simulation: {
      success: !simulation.value.err,
      error: simulation.value.err,
      logs: simulation.value.logs,
      unitsConsumed: simulation.value.unitsConsumed
    },
    transaction: {
      recentBlockhash: transaction.recentBlockhash,
      feePayer: transaction.feePayer?.toBase58(),
      instructions: transaction.instructions.length
    },
    metadata: {
      timestamp: Date.now(),
      commitment: config.commitment
    }
  };
}

​

Notes

1. Simulates sending a transaction without actually sending it
2. The response includes execution logs and errors
3. The simulation is performed on the current state
4. No state changes are persisted
5. Useful for testing and debugging transactions

​

Best Practices

1. Use simulation before sending real transactions
2. Check compute unit consumption
3. Analyze program logs for errors
4. Verify account states after simulation
5. Handle simulation errors appropriately

​

Common Errors

​

Use Cases

1. Transaction Analysis

   interface TransactionAnalysis {
     transaction: {
       instructions: number;
       signers: number;
       estimatedUnits: number;
     };
     simulation: {
       success: boolean;
       error: string | null;
       logs: string[];
       unitsConsumed: number;
     };
     analysis: {
       programInvocations: number;
       accountAccesses: number;
       errorAnalysis?: string;
     };
     metadata: {
       timestamp: number;
       commitment?: string;
     };
   }
   
   class TransactionAnalyzer {
     async analyzeTransaction(
       transaction: Transaction,
       config: { 
         sigVerify?: boolean;
         commitment?: string;
       }
     ): Promise<TransactionAnalysis> {
       const simulation = await connection.simulateTransaction(transaction, config);
       
       const logs = simulation.value.logs || [];
       const programInvocations = logs.filter(log => 
         log.includes('Program') && log.includes('invoke')
       ).length;
       
       const accountAccesses = logs.filter(log =>
         log.includes('Account') || log.includes('Token')
       ).length;
       
       let errorAnalysis;
       if (simulation.value.err) {
         errorAnalysis = this.analyzeError(simulation.value.err);
       }
       
       return {
         transaction: {
           instructions: transaction.instructions.length,
           signers: transaction.signatures.length,
           estimatedUnits: simulation.value.unitsConsumed || 0
         },
         simulation: {
           success: !simulation.value.err,
           error: simulation.value.err,
           logs,
           unitsConsumed: simulation.value.unitsConsumed || 0
         },
         analysis: {
           programInvocations,
           accountAccesses,
           errorAnalysis
         },
         metadata: {
           timestamp: Date.now(),
           commitment: config.commitment
         }
       };
     }
     
     private analyzeError(error: any): string {
       if (typeof error === 'string') {
         if (error.includes('insufficient funds')) {
           return 'Transaction failed due to insufficient funds';
         }
         if (error.includes('invalid account owner')) {
           return 'Transaction failed due to invalid account ownership';
         }
         if (error.includes('account not found')) {
           return 'Transaction failed due to missing account';
         }
       }
       return 'Unknown error occurred during simulation';
     }
   }
   

2. Transaction Validation

   interface TransactionValidation {
     transaction: {
       signature: string;
       blockhash: string;
       feePayer: string;
     };
     checks: Array<{
       name: string;
       passed: boolean;
       details?: string;
     }>;
     recommendations: Array<{
       type: 'fix' | 'warning' | 'info';
       message: string;
     }>;
     metadata: {
       timestamp: number;
     };
   }
   
   class TransactionValidator {
     private readonly maxUnits = 200000;
     private readonly minAccountRent = 890880;
     
     async validateTransaction(
       transaction: Transaction,
       config: { 
         sigVerify?: boolean;
         commitment?: string;
       }
     ): Promise<TransactionValidation> {
       const simulation = await connection.simulateTransaction(transaction, config);
       
       const checks: Array<{
         name: string;
         passed: boolean;
         details?: string;
       }> = [];
       
       const recommendations: Array<{
         type: 'fix' | 'warning' | 'info';
         message: string;
       }> = [];
       
       // Check compute units
       const unitsConsumed = simulation.value.unitsConsumed || 0;
       checks.push({
         name: 'Compute Units',
         passed: unitsConsumed <= this.maxUnits,
         details: `${unitsConsumed} units consumed`
       });
       
       if (unitsConsumed > this.maxUnits) {
         recommendations.push({
           type: 'fix',
           message: 'Transaction exceeds compute unit limit'
         });
       }
       
       // Check for errors
       checks.push({
         name: 'Simulation',
         passed: !simulation.value.err,
         details: simulation.value.err?.toString()
       });
       
       if (simulation.value.err) {
         recommendations.push({
           type: 'fix',
           message: `Fix simulation error: ${simulation.value.err}`
         });
       }
       
       // Analyze logs
       const logs = simulation.value.logs || [];
       checks.push({
         name: 'Program Execution',
         passed: logs.some(log => log.includes('Program log:')),
         details: 'Program execution logs present'
       });
       
       // Check account rent
       const rentWarnings = logs.filter(log => 
         log.includes('insufficient lamports for rent')
       );
       
       if (rentWarnings.length > 0) {
         checks.push({
           name: 'Account Rent',
           passed: false,
           details: 'Insufficient lamports for rent'
         });
         
         recommendations.push({
           type: 'fix',
           message: `Ensure accounts have minimum rent: ${this.minAccountRent} lamports`
         });
       }
       
       return {
         transaction: {
           signature: transaction.signatures[0]?.signature?.toString() || '',
           blockhash: transaction.recentBlockhash || '',
           feePayer: transaction.feePayer?.toBase58() || ''
         },
         checks,
         recommendations,
         metadata: {
           timestamp: Date.now()
         }
       };
     }
   }
   

3. Transaction Optimization

   interface TransactionOptimization {
     original: {
       instructions: number;
       unitsConsumed: number;
     };
     optimized: {
       instructions: number;
       unitsConsumed: number;
       savings: number;
     };
     changes: Array<{
       type: 'merge' | 'remove' | 'reorder';
       description: string;
       impact: number;
     }>;
     metadata: {
       timestamp: number;
     };
   }
   
   class TransactionOptimizer {
     async optimizeTransaction(
       transaction: Transaction
     ): Promise<TransactionOptimization> {
       // Simulate original transaction
       const originalSimulation = await connection.simulateTransaction(transaction);
       const originalUnits = originalSimulation.value.unitsConsumed || 0;
       
       const changes: Array<{
         type: 'merge' | 'remove' | 'reorder';
         description: string;
         impact: number;
       }> = [];
       
       // Create optimized transaction
       const optimizedTransaction = new Transaction();
       const instructions = [...transaction.instructions];
       
       // Analyze and merge similar instructions
       const mergedInstructions = this.mergeInstructions(instructions);
       if (mergedInstructions.length < instructions.length) {
         changes.push({
           type: 'merge',
           description: `Merged ${instructions.length - mergedInstructions.length} similar instructions`,
           impact: 0 // Will be updated after simulation
         });
       }
       
       // Remove redundant instructions
       const cleanedInstructions = this.removeRedundantInstructions(mergedInstructions);
       if (cleanedInstructions.length < mergedInstructions.length) {
         changes.push({
           type: 'remove',
           description: `Removed ${mergedInstructions.length - cleanedInstructions.length} redundant instructions`,
           impact: 0
         });
       }
       
       // Reorder instructions for optimal execution
       const orderedInstructions = this.reorderInstructions(cleanedInstructions);
       changes.push({
         type: 'reorder',
         description: 'Reordered instructions for optimal execution',
         impact: 0
       });
       
       // Add optimized instructions
       orderedInstructions.forEach(instruction => {
         optimizedTransaction.add(instruction);
       });
       
       // Simulate optimized transaction
       const optimizedSimulation = await connection.simulateTransaction(optimizedTransaction);
       const optimizedUnits = optimizedSimulation.value.unitsConsumed || 0;
       
       // Calculate impacts
       const totalSavings = originalUnits - optimizedUnits;
       changes.forEach(change => {
         change.impact = Math.floor(totalSavings / changes.length);
       });
       
       return {
         original: {
           instructions: instructions.length,
           unitsConsumed: originalUnits
         },
         optimized: {
           instructions: orderedInstructions.length,
           unitsConsumed: optimizedUnits,
           savings: totalSavings
         },
         changes,
         metadata: {
           timestamp: Date.now()
         }
       };
     }
     
     private mergeInstructions(
       instructions: Array<any>
     ): Array<any> {
       // Implementation would analyze and merge similar instructions
       // This is a placeholder that returns the original instructions
       return instructions;
     }
     
     private removeRedundantInstructions(
       instructions: Array<any>
     ): Array<any> {
       // Implementation would identify and remove redundant instructions
       // This is a placeholder that returns the original instructions
       return instructions;
     }
     
     private reorderInstructions(
       instructions: Array<any>
     ): Array<any> {
       // Implementation would reorder instructions for optimal execution
       // This is a placeholder that returns the original instructions
       return instructions;
     }
   }