Add outbound requirements for Codex

REQUIREMENTS.md

@@ -37,4 +37,106 @@ TODO: list specific areas of concerns and risks
 
 ### Codex
 
-TODO
+#### Publish Large Messages - Uploader is online
+
+To be used for messages archival in Chat SDK, Qaku, opchan, etc.
+
+**Functionality**
+
+1. Ability to transfer a message of 1MB or more between two or more nodes.
+2. Message's CID is less than 100kB.
+
+
+**Usability**
+
+1. Developer can implement upload feature with 10 lines of code or less.
+2. No configuration is necessary.
+
+**Reliability**
+
+1. Download operation can be resumed.
+2. Upload operation can be resumed.
+3. Uploader can be expected to be online when user are downloading.
+
+**Performance**
+
+None
+
+**Supportability**
+
+1. Library for Browser applications.
+2. Library for Nim desktop applications.
+3. Library for Nim mobile applications.
+
+**+ (Privacy, Anonymity, Censorship-Resistance, Deployments)**
+
+1. The unavailability of a static host (IP, DNS) does not prevent a user to upload or download (censorship-resistance).
+2. TODO (privacy)
+
+#### Publish Large Messages - Uploader is offline
+
+To be used for
+
+- large messages transfers (such as images, videos, audio) in Chat SDK, Opchan, etc.
+- Enhancement of message archival (uploader does not need to be online).
+
+Builds on [Publish Large Messages - Uploader is online](#publish-large-messages---uploader-is-online)
+
+**Functionality**
+
+1. Message is cached to enable retrieval without sender being online (once uploaded).
+2. Best effort in terms of message retention; expectations on restrictions are documented.
+
+**Usability**
+
+1. Receiver can download the large message, even if sender is offline, as long as they get the CID out-of-band.
+
+**Reliability**
+
+1. Uploader may be offline when receiver is retrieving the large message.
+
+**Performance**
+
+None
+
+**Supportability**
+
+1. Library for Browser applications.
+2. Library for Nim applications.
+
+**+ (Privacy, Anonymity, Censorship-Resistance, Deployments)**
+
+TODO (privacy)
+
+#### Publish Large Messages - Retention is guaranteed
+
+In this scenario, the uploader wants to ensure the data is persisted and is willing to pay for it.
+This may be a Qaku Q&A admin, a opchan cell owner or Status Communities owner.
+
+Builds on previous requirements.
+
+**Functionality**
+
+1. Uploader may pay for large message storage to have guaranteed retention.
+
+**Usability**
+
+1. Receiver can download the large message, even if sender is offline, as long as they get the CID out-of-band.
+2. Receiver does not need to pay to retrieve the large message.
+
+**Reliability**
+
+1. Uploader may be offline when receiver is retrieving the large message.
+2. Uploader is guaranteed a period of retention for a given price.
+
+**Performance**
+
+See previous requirements.
+
+**Supportability**
+
+See previous requirements.
+
+**+ (Privacy, Anonymity, Censorship-Resistance, Deployments)**
+
+See previous requirements.