PubSub.md

SQL Tables

Subscriber

ID BIGINT PRIMARY IDENTITY, SoapEndpoint NVARCHAR(256), Escalation INT, Other Metadata

Message

ID UNIQUEIDENTIFIER PRIMARY, Payload VARBINARY(MAX), Other Metadata

MessageDelivery

SubscriberID UNIQUEIDENTIFIER PRIMARY, MessageID UNIQUEIDENTIFIER PRIMARY, Retries INT = 0, IsDelivered BIT = 0,

Operations

CreateSubscriber

• Add subscriber to Subscriber table.

DeleteSubscriber

• Remove subscriber from Subscriber table.

BeforeDeliver

VB.Net:

• Create GUID (=mid) SQL:
• Insert message into Message table (ID = mid)
• Foreach Subscriber (sid=ID), insert into MessageDelivery table (SubscriberID = sid, MessageID = mid)
• SELECT MD.SubscriberID, MD.MessageID, MD.Retries, M.Payload, S.SoapEndpoint, S.Escalation From MessageDelivery AS MD JOIN Message AS M ON MD.MessageID = M.ID JOIN Subscriber AS S ON MD.SubscriberID = S.ID WHERE MD.MessageID = @mid AND MD.SubscriberID = @sid AND M.IsDelivered = 0;

Deliver

VB.Net:

• PAUSE (not stop/reset) redeliver tick timer
• For each row from BeforeDeliver -- Call SOAP endpoint with message payload (this will probably be 'anonymous' XML - i.e. WebService with XmlDocument as the only parameter). -- If it fails increase Retries, otherwise set IsDelivered to 1. -- Check to see if Retries matches Escalation, if it does notify admin.
• Resume deliver tick timer

ReDeliver Tick (every say 30s, non-overlapping)

SQL:

SELECT MD.SubscriberID, MD.MessageID, MD.Retries, M.Payload, S.SoapEndpoint, S.Escalation From MessageDelivery AS MD JOIN Message AS M ON MD.MessageID = M.ID JOIN Subscriber AS S ON MD.SubscriberID = S.ID WHERE M.IsDelivered = 0 AND M.Retries < S.Escalation VB.Net:

• For each row returned -- Call SOAP endpoint with message payload (this will probably be 'anonymous' XML - i.e. WebService with XmlDocument as the only parameter). -- If it fails increase Retries, otherwise set IsDelivered to 1. -- Check to see if Retries matches Escalation, if it does notify admin.