Обсуждение: Protocol Message Graph
I have created a directed graph using graphviz that shows the message flow/event stream. Perhaps this will be helpful to someone. Of course, corrections are also welcome. http://www.themactionfaction.com/pg/PGXProtocol.dot http://www.themactionfaction.org/pg/PGXProtocol.svg http://www.themactionfaction.org/pg/PGXProtocol.pdf (Messages in ellipses are sent from the server, rectangle message are sent from the client.) -M ¬ ¬ ¬ ¬ ¬ ¬ ¬ ¬ ¬ ¬ ¬ ¬ ¬ ¬ ¬ ¬ ¬ ¬ AgentM agentm@themactionfaction.com ¬ ¬ ¬ ¬ ¬ ¬ ¬ ¬ ¬ ¬ ¬ ¬ ¬ ¬ ¬ ¬ ¬ ¬
Agent M wrote: > I have created a directed graph using graphviz that shows the message > flow/event stream. Perhaps this will be helpful to someone. Of course, > corrections are also welcome. Interesting. I'm not sure how to read the graph however -- for example what does it mean to have ReadyForQuery in both a rectangle and an ellipse? What do the standalone boxes mean? (e.g. the SSLRequest and CancelRequest? and why are they wrapped in two boxes? why Close/CloseComplete appear from nowhere and they don't lead anywhere?) Maybe it would make more sense to have a graph of states, and the edges would indicate what messages are sent to change from one state to another. -- Alvaro Herrera http://www.CommandPrompt.com/ PostgreSQL Replication, Consulting, Custom Development, 24x7 support
On Apr 23, 2006, at 6:43 PM, Alvaro Herrera wrote: > Agent M wrote: >> I have created a directed graph using graphviz that shows the message >> flow/event stream. Perhaps this will be helpful to someone. Of course, >> corrections are also welcome. > > Interesting. I'm not sure how to read the graph however -- for example > what does it mean to have ReadyForQuery in both a rectangle and an > ellipse? What do the standalone boxes mean? (e.g. the SSLRequest and > CancelRequest? and why are they wrapped in two boxes? why > Close/CloseComplete appear from nowhere and they don't lead anywhere?) > > Maybe it would make more sense to have a graph of states, and the edges > would indicate what messages are sent to change from one state to > another. I tried to group the messages by functionality: asynchronous, simple, extended, copy, function, etc. Since ReadyForQuery shows up in multiple modes, I put it in its own mode (hence the additional bounding box). I agree that the graph isn't perfect, but I also ran up against certain limitations in graphiz itself (e.g., only one level of subgraph is supported). So it's useful as a guide, but it clearly isn't a state machine. -M ¬ ¬ ¬ ¬ ¬ ¬ ¬ ¬ ¬ ¬ ¬ ¬ ¬ ¬ ¬ ¬ ¬ ¬ AgentM agentm@themactionfaction.com ¬ ¬ ¬ ¬ ¬ ¬ ¬ ¬ ¬ ¬ ¬ ¬ ¬ ¬ ¬ ¬ ¬ ¬
On Sun, 2006-04-23 at 18:43 -0400, Alvaro Herrera wrote: > Agent M wrote: > > I have created a directed graph using graphviz that shows the message > > flow/event stream. Perhaps this will be helpful to someone. Of course, > > corrections are also welcome. Thats a good start. > Maybe it would make more sense to have a graph of states, and the edges > would indicate what messages are sent to change from one state to > another. Yes, that would be better. It would be good to do the same for LWLock states, to help check for deadlock possibilities. -- Simon Riggs EnterpriseDB http://www.enterprisedb.com