This document summarizes a presentation on message resequencing in MuleSoft. It discusses the need for message resequencing when messages must be received in a specific order. It then overviews the solution, including an API that uses a database to track sequence numbers and store out-of-order messages. The document outlines the API endpoints and database tables used in the solution. It concludes by advertising ways to provide feedback and share information about the MuleSoft meetup group.

1. 23rd October 2021
Calicut MuleSoft Meetup Group
#4 Message Resequencing in Mule

2. Safe Harbour Statement
● Both the speaker and the host are organizing this meet-up in individual capacity only. We are
not representing our companies here.
● This presentation is strictly for learning purposes only. Organizer/Presenter do not hold any
responsibility that same solution will work for your business requirements.
● This presentation is not meant for any promotional activities.
2

3. Organizers
Fathima Farzana John Mathew Philip
NJC Labs NJC Labs
MuleSoft / Integration Developer MuleSoft / Integration
Developer
3

4. 4
● Need of message resequencing
● Solution overview
● Solution code walkthrough
● Demo
● Trivia Quiz and Wrap Up
Agenda

5. Speaker
5
Vishwas Pawar
Apisero

6. 6
● Applications require messages to be received in a specific order without gaps.
● In such cases the application needs to have the ability to re-sequence the message on arrival
and then process them.
● The re-sequencing-utility-api is an API that uses database to keep track of latest valid message
sequence number as well as store the messages that cannot be processed due to sequence
gaps.
Need of message re-sequencing

7. Use case overview
{
"SEQ_TYPE": "Packets",
"SEQ_VERSION": "DPS1",
"SEQ_NUMBER": 1,
"DATA": "M"
}
{
"SEQ_TYPE": "Packets",
"SEQ_VERSION": "DPS1",
"SEQ_NUMBER": 2,
"DATA": "A"
}
{
"SEQ_TYPE": "Packets",
"SEQ_VERSION": "DPS1",
"SEQ_NUMBER": 3,
"DATA": "X"
}
{
"SEQ_TYPE": "Packets",
"SEQ_VERSION": "DPS2",
"SEQ_NUMBER": 1,
"DATA": "R"
}
{
"SEQ_TYPE": "Packets",
"SEQ_VERSION": "DPS2",
"SEQ_NUMBER": 2,
"DATA": "O"
}
{
"SEQ_TYPE": "Packets",
"SEQ_VERSION": "DPS3",
"SEQ_NUMBER": 3,
"DATA": "W"
}
SEQ_VERSION: DPS2
SEQ_VERSION: DPS1

8. 8
Solution Overview
resequencer-utility-api
SEQUENCE_TYPE SEQUENCE_STATE SEQUENCE_STORED_MESSAGE
Retrieves sequence
start number for a
sequence based on its
type
Retrieves latest
sequence number for a
given sequence type
and its revision
Stores the message in
case of gaps, to be
processed later.

9. 9
● GET: /sequence/{type}/{id}/{messageSeqNb}
○ Returns true if the messageSeqNb is next in sequence
○ Returns false if messageSeqNb has gaps
○ Returns 400 is the messageSeqNb is less than the latestSeqNb or the seqStart
● PUT : /sequence/{type}/{id}/{messageSeqNb}
○ Updates the LATEST_SEQ in SEQUENCE_STATE with the messageSeqNb that is processed
○ Requeues the message if there
○ Returns 400 if the messageSeqNb is less than the latestSeqNb or the seqStart
● POST: /sequence/{type}/{id}/{messageSeqNb}
○ Used in case of sequence gaps
○ Message will be stored in SEQUENCE_STORED_MESSAGES
API Endpoints

10. 10
Database Tables
SEQ_TYPE ID LATEST_SEQUENCE
Packets DPS1 1
SEQUENCE_STATE
SEQ_TYPE REQUEUE_EXCHANGE REQUEUE_ROUTINGKEY SEQ_START
Packets null demo-q 1
SEQUENCE_TYPES
SEQ_TYPE ID SEQ_NB SEQ_DATA MIMIE_TYPE TIMESTAMP
Packets DPS1 3 {’hi’:’World’} application/json 23-OCT-2021
SEQUENCE_STORED_MESSAGES

11. All contents © MuleSoft, LLC
DEMOS

12. Trivia Quiz

13. 13
● Share:
○ Tweet using the hashtag #MuleSoftMeetups and #CalicutMuleSoftMeetups
○ Invite your network to join: https://meetups.mulesoft.com/calicut/
● Feedback:
○ Fill out the survey feedback and suggest topics for upcoming events
○ Contact MuleSoft at meetups@mulesoft.com for ways to improve the program
What’s next?

14. Thank you