# Database, HTTP, File and JMS connector behaviors

*MuleSoft Platform Integration Architect Study Guide · Designing and developing Mule applications · Last updated November 13, 2026 · https://www.certifyforce.com/study-guide/mulesoft-platform-integration-architect/designing-and-developing-mule-applications/database-http-file-and-jms-connector-behaviors*

How the Database Connector calls stored procedures and limits Select results, how the HTTP Request operation resolves hosts, builds the Host header and streams bodies, how File Read locks behave, and how JMS acknowledgement modes decide redelivery.

- Certification: Salesforce MuleSoft Platform Integration Architect
- Exam section: Designing and developing Mule applications
- Study guide: https://www.certifyforce.com/study-guide/mulesoft-platform-integration-architect

**Official exam objective:**

> Design Mule applications using common features of core connectors.

## What the exam expects

- Write a stored procedure call the Database Connector supports: parameter order, defaults and date handling.
- Bound a large Select by total rows and network chunk size.
- Recognize HTTP Request behaviors that break partner calls (round-robin DNS, the generated Host header) and their controls.
- Distinguish chunked, internal and response streaming by Mule runtime version.
- Predict File Read lock behavior and JMS redelivery under each acknowledgement mode.

**Callable statement:** the `{ call name(:p1, …) }` text a Stored procedure runs. **Fetch size:** rows returned per network chunk. **Round-robin DNS:** spreading requests across every IP a host resolves to. **Request streaming:** sending an HTTP body in chunks. **ackId:** the attribute identifying a received JMS message for its connection ([HTTP Request](https://docs.mulesoft.com/http-connector/latest/http-request-ref), [JMS acknowledgement](https://docs.mulesoft.com/jms-connector/latest/jms-ack)).

## Key facts

| Fact | Detail | Source |
|---|---|---|
| Stored procedure parameters | All of them, in declaration order, parameterized; no named parameters | [Stored procedures](https://docs.mulesoft.com/db-connector/latest/database-stored-procedure) |
| Null or empty input | Does not push the procedure's default value | [Stored procedures](https://docs.mulesoft.com/db-connector/latest/database-stored-procedure) |
| Select streaming | Transparent and always enabled | [Select](https://docs.mulesoft.com/db-connector/latest/database-connector-select) |
| Max rows / Fetch size | Total row cap / rows per network chunk (driver default often 10) | [Select](https://docs.mulesoft.com/db-connector/latest/database-connector-select) |
| HTTP host resolution | Round-robin DNS by default; opt out per host with `mule.http.disableRoundRobin` | [HTTP Request](https://docs.mulesoft.com/http-connector/latest/http-request-ref) |
| Host header port | Default port included when none configured; omit property needs Mule 4.5+ and HTTP 1.10.3+ | [HTTP Request](https://docs.mulesoft.com/http-connector/latest/http-request-ref) |
| `mule.http.requestStreaming.enable` | false on Mule 4.4 and earlier, true on 4.5 and later | [HTTP Request](https://docs.mulesoft.com/http-connector/latest/http-request-ref) |
| File lock already held | `FILE:FILE_LOCK` error | [File Read](https://docs.mulesoft.com/file-connector/latest/file-read) |
| JMS MANUAL | Unacknowledged messages are not redelivered; recover on the receiving connection | [JMS acknowledgement](https://docs.mulesoft.com/jms-connector/latest/jms-ack) |

## Check yourself

- What is the default maximum size of the HTTP request header section, and which property changes it?
- When a stored procedure's return value is an output parameter, how must the start of the call be written?
- When the JDBC driver is Snowflake, how does the callable statement differ from the standard form?
- Why can a processor after a streamed HTTP response stall, and what bounds the wait?

## Sources

- [Execute Stored Procedures Examples](https://docs.mulesoft.com/db-connector/latest/database-stored-procedure)
- [Query a Database Examples](https://docs.mulesoft.com/db-connector/latest/database-connector-select)
- [Configure HTTP Request Operation](https://docs.mulesoft.com/http-connector/latest/http-request-ref)
- [Read a File Using the File Connector](https://docs.mulesoft.com/file-connector/latest/file-read)
- [Configure Message Acknowledgement with the JMS Connector](https://docs.mulesoft.com/jms-connector/latest/jms-ack)
- [JMS Connector 2.0](https://docs.mulesoft.com/jms-connector/latest/)

## About the full unit

The "Core concepts", "Exam traps" and "Worked scenario" sections of this unit, its 7 linked practice questions, and unlimited timed mock exams are included with the MuleSoft Platform Integration Architect pack (USD $19): https://www.certifyforce.com/practice-exams