Homework 1: Trace a Transaction Through All Phases

← Back to Transactors: Understanding the Lifecycle of a Transaction

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Objective

Use logging and debugging to trace a transaction through all four processing phases and document the state changes at each step.

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Prerequisites

• A compiled rippled build (debug mode recommended)

• A running rippled instance in standalone mode

• Familiarity with rippled logging configuration

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Tasks

Part 1: Enable Trace Logging

1. Configure your rippled to enable trace-level logging for the transaction subsystem:

{
    "log_level": "trace",
    "log_channels": {
        "Transactor": "trace",
        "View": "trace"
    }
}

Or use the command-line:

./rippled --standalone --conf=rippled.cfg

Then in another terminal:

./rippled log_level Transactor trace
./rippled log_level View trace

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Part 2: Create Test Accounts

1. Generate two test accounts using the wallet_propose RPC:

./rippled wallet_propose

1. Fund both accounts using the genesis account in standalone mode.

2. Record:

   • Account 1 address and sequence number

   • Account 2 address

   • Initial balances for both accounts

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Part 3: Submit a CheckCreate Transaction

1. Create and sign a CheckCreate transaction:

{
    "TransactionType": "CheckCreate",
    "Account": "<Account1>",
    "Destination": "<Account2>",
    "SendMax": "100000000",
    "Expiration": 800000000,
    "Fee": "12",
    "Sequence": <sequence>
}

1. Submit the transaction using the submit RPC.

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Part 4: Analyze the Logs

Review the logs and identify entries for each phase:

Preflight Phase:

• What checks were logged?

• What was the result?

Preclaim Phase:

• What ledger entries were read?

• What checks were performed?

• What was the result?

doApply Phase:

• What ledger entries were created?

• What directories were modified?

• What owner counts changed?

Finalization:

• What was the final result code?

• What metadata was recorded?

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Part 5: Document State Changes

Create a before/after comparison table:

Object	Field	Before	After
Account1 AccountRoot	Balance	?	?
Account1 AccountRoot	OwnerCount	?	?
Account1 AccountRoot	Sequence	?	?
Check	(new)	N/A	?
Account1 OwnerDir	Entries	?	?
Account2 OwnerDir	Entries	?	?

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Part 6: Verify with RPC

Use RPC commands to verify your analysis:

# Check account state
./rippled account_info <Account1>

# Check account objects
./rippled account_objects <Account1>

# Get transaction details
./rippled tx <transaction_hash>

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Deliverables

1. Log excerpts: Key log entries from each phase (with annotations)

2. State change table: Completed before/after comparison

3. Transaction metadata: The meta field from the tx response

4. Analysis: Brief explanation of what happened in each phase

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Bonus Challenge

Repeat the exercise with a transaction that fails:

1. Create a CheckCreate to a non-existent account

2. Trace through the phases

3. Document where and why it failed

4. Compare the logs to the successful case

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Questions for Reflection

1. At what point does the sequence number get consumed?

2. At what point does the fee get deducted?

3. If doApply fails with tecINSUFFICIENT_RESERVE, what happens to the fee?

4. Why is the Check added to both account directories?