Study Guide
Table Of Contents
- PayPal Certified Developer Program Study Guide
- Contents
- List of Tables
- Online Payment Processing
- Internet Security and Fraud Prevention
- Why Every Business Should Be Concerned About Internet Fraud
- Liability for Internet Fraud
- Internet Fraud: What It Is and How It Happens
- Who Is at Risk for Online Fraud
- Reducing Exposure to Fraud
- What Banks and Card Associations Are Doing to Prevent Online Credit Card Fraud
- What PayPal Is Doing to Protect Your Business Against Fraud
- Disclosure and Compliance
- PayPal Fraud Protection Services
- Review Questions
- Getting Started With Account Setup
- API Credentials
- Name-Value Pair (NVP) API
- Express Checkout
- Direct Payment API
- Transactions
- Sandbox Testing
- Answers to Review Questions
- General Reference Information
- Glossary
- Index
PayPal Certified Developer Program Study Guide March 2008 57
Name-Value Pair (NVP) API
Technical Details
5
Response Format
A response from the PayPal servers is a URL-encoded name-value pair string, just like the
request. The general format of the response is described in Table 5.3.
Each response includes the ACK field. If the ACK field’s value is Success or
SuccessWithWarning, the application should process the API response fields. In a
successful response, the application can ignore all fields up to and including BUILD; the
important fields begin after BUILD.
The possible successful response fields for each method are detailed in the reference
information for the API. How the application handles the fields depends on the particular API
method called (such as filling in a form, updating a database, and so on).
ACK Parameter Values
Table 5.4 lists the possible values for the ACK parameter.
Error Responses
If the ACK value is Error, the API response fields are not returned. The general format of an
error response is described in Table 5.5.
TABLE 5.3 General Format of a Successful Response
Success response
fields
ACK=Success&TIMESTAMP=date/timeOfResponse&CORRELATIONID=
debuggingTokens&VERSION=3.3&BUILD=buildNumber
N OTE: In the examples in this and other PayPal documents, the successful response
header fields sometimes appear like this:
[successResponseFields]
API response fields &NAME1=value1&NAME2=value2...
T
ABLE 5.4 ACK Parameter Values
Type of Response Value
Successful response Success
SuccessWithWarning
Error response Error
T
ABLE 5.5 Format of an Error Response
Response
fields on
error
ACK=Error&TIMESTAMP=date/timeOfResponse&CORRELATIONID=
debuggingToken&VERSION=3.3&BUILD=buildNumber&
L_ERRORCODE0=errorCode&L_SHORTMESSAGE0=shortMessage&
L_LONGMESSAGE0=longMessage&L_SEVERITYCODE0=severityCode