Lesson 229 of 288
Integration & ConnectivityIFS and API Payload Files
Why the IFS is a common place for request/response payloads, logs, and other integration artifacts on IBM i.
Learning Objective
By the end of this lesson, you will be able to explain why the IFS is a common place to find request/response payloads, logs, and other integration artifacts on IBM i.
Simple Explanation
The IFS Basics lesson introduced the Integrated File System as a directory-based way to store stream files on IBM i, separate from traditional libraries and objects. Integration work leans on this heavily: JSON payloads, log files from API calls, and other integration-related files are commonly read from and written to the IFS, because they are plain-text, stream-oriented data, not the fixed, record-based data that traditional native objects are built around.
A typical integration directory structure might look like:
/home/integrations/orders/incoming/order-100234.json
/home/integrations/orders/outgoing/response-100234.json
/home/integrations/orders/logs/2026-07-15.log
An RPGLE or CLLE program involved in integration work might read an incoming JSON payload file from the IFS, process it, and write a response payload file back out, or append a line to a log file to record what happened.
Why It Matters
Native IBM i objects are excellent for structured, record-based business data, but a JSON payload is naturally a stream of text, not a fixed-length record. The IFS is built for exactly this kind of data, which is why integration work so often involves reading and writing IFS stream files alongside the native database work already familiar from earlier in this course.
Practical Example
Imagine an order arrives from a web storefront as a JSON payload,
written to
/home/integrations/orders/incoming/order-100234.json on the IFS. An
RPGLE program reads that file, validates the customer number using the
existing validation logic covered earlier in this course, and writes a
result back to
/home/integrations/orders/outgoing/response-100234.json. A line is
also appended to a daily log file in
/home/integrations/orders/logs/, recording that the order was
received and processed.
This is a simplified, illustrative example rather than a specific real integration, but it reflects a genuinely common pattern.
Common Confusions
"Could this data be stored in a native database file instead of the IFS?" Sometimes, but a JSON payload does not naturally fit a fixed-length record format the way traditional IBM i data does. The IFS is a more natural fit for this kind of stream-oriented, variable-length text data.
"Is every integration required to use the IFS?" No. Some integration approaches pass data directly between programs without ever writing a payload to disk. The IFS is common specifically when a payload, log, or other artifact needs to be written to and read from as a file, such as for auditing or troubleshooting.
"Is this the same as the traditional use of the IFS for things like configuration files?" The underlying mechanism is the same IFS covered in the IFS Basics lesson; what differs here is the purpose, storing integration-related payloads and logs, rather than configuration files.
Quick Recap
- The IFS is a common place for JSON payloads, logs, and other integration artifacts on IBM i.
- JSON payloads are naturally stream-oriented text, which fits the IFS better than fixed-length native records.
- A typical integration flow might read an incoming payload file, process it using existing business logic, and write a response payload or log file back to the IFS.
- This builds directly on the IFS concepts already covered earlier in this course, applied to an integration use case.
Try Asking the AI Tutor
Use the AI Tutor to ask follow-up questions about this lesson. For example, try asking:
- "What are some good habits for naming and organizing integration files in the IFS so they stay easy to troubleshoot later?"
- "Why might a team choose to log each API request and response as a file in the IFS rather than just relying on the job log?"