pm/FURPS/application/sds.md

Scalable Data Sync

Functionality

1. 🏗️ Ability to know that a published message has been received by at least one member of the group (and could therefore eventually be retrieved by other members).
2. 🏗️ Ability for participants to know when they have missed a message, and to retrieve them using Waku store protocol

Usability

1. 🏗️ When sending a message to a large group, the application knows whether it was received by other group members, with high probability
2. 🏗️ When being part of a large group, the application is able to know whether they are missing messages, and is able to retrieve missed messages

Reliability

1. 🏗️ When sending a message in a group, the publisher can ascertain the message was received by at least one recipient (Vac-QA)
2. 🏗️ When receiving messages in a group, the receiver can ascertain most missed messages by receiving one recent message from the group. (Vac-QA)

Performance

Assuming messages in a group are sent at least every S seconds.

1. 🏗️ When sending a message in a group, the publisher can ensure the message was received by at least one recipient withinS seconds (Vac-DST)
2. 🏗️ When receiving messages in a group, the receiver can detect 90% of missed messages within 3*S seconds, and reach eventual consistency within 6*S seconds (Vac-DST)

Supportability

1. 🏗️ Applied to Communities channels only, both Status Mobile and Desktop