Postgres wire protcol -- Graphviz state chart

postgres-wire-protocol-state-chart.dot

digraph state_machine {
  rankdir=LR;
  size="8,5"
  node [shape = doublecircle, style=filled, fillcolor=lightblue]; WaitingForQuery;
  node [shape = doublecircle, style=filled, fillcolor=maroon] GotErrorResponseDuringSimpleQuery;
  node [shape = circle, style=filled, fillcolor=lightgrey];
  InitializingBackend -> GotCommandComplete [ label = "PG3ReadyForQuery", color=green ];
  InitializingBackend -> InitializingBackend [ label = "PG3BackendKeyData", color=orange ];
  GotDataRow -> GotErrorResponseDuringSimpleQuery [ label = "PG3ErrorResponse", color=red ];
  GotDataRow -> GotCommandComplete [ label = "PG3CommandComplete", color=green ];
  GotDataRow -> GotDataRow [ label = "PG3DataRow", color=orange ];
  GotErrorResponseDuringSimpleQuery -> WaitingForQuery [ label = "PG3ReadyForQuery", color=green ];
  GotEmptyQueryResponse -> WaitingForQuery [ label = "PG3ReadyForQuery", color=green ];
  GotEmptyQueryResponse -> GotErrorResponseDuringSimpleQuery [ label = "PG3ErrorResponse", color=red ];
  Querying -> GotErrorResponseDuringSimpleQuery [ label = "PG3ErrorResponse", color=red ];
  Querying -> GotCommandComplete [ label = "PG3CommandComplete", color=green ];
  Querying -> GotRowDescription [ label = "PG3RowDescription", color=orange ];
  Querying -> GotEmptyQueryResponse [ label = "PG3EmptyQueryResponse", color=green ];
  Authenticating -> AuthenticatingWithMD5 [ label = "PG3AuthenticationMD5Password", color=orange ];
  Authenticating -> InitializingBackend [ label = "PG3AuthenticationOkMessage", color=green ];
  AuthenticatingWithMD5 -> InitializingBackend [ label = "PG3AuthenticationOkMessage", color=green ];
  GotCommandComplete -> WaitingForQuery [ label = "PG3ReadyForQuery", color=green ];
  GotCommandComplete -> GotErrorResponseDuringSimpleQuery [ label = "PG3ErrorResponse", color=red ];
  GotCommandComplete -> GotCommandComplete [ label = "PG3CommandComplete", color=green ];
  GotCommandComplete -> GotRowDescription [ label = "PG3RowDescription", color=orange ];
  GotRowDescription -> GotErrorResponseDuringSimpleQuery [ label = "PG3ErrorResponse", color=red ];
  GotRowDescription -> GotCommandComplete [ label = "PG3CommandComplete", color=green ];
  GotRowDescription -> GotDataRow [ label = "PG3DataRow", color=orange ];
}

preview

https://dreampuf.github.io/GraphvizOnline/#digraph%20state_machine%20%7B%0D%0A%20%20rankdir%3DLR%3B%0D%0A%20%20size%3D%228%2C5%22%0D%0A%20%20node%20%5Bshape%20%3D%20doublecircle%2C%20style%3Dfilled%2C%20fillcolor%3Dlightblue%5D%3B%20WaitingForQuery%3B%0D%0A%20%20node%20%5Bshape%20%3D%20doublecircle%2C%20style%3Dfilled%2C%20fillcolor%3Dmaroon%5D%20GotErrorResponseDuringSimpleQuery%3B%0D%0A%20%20node%20%5Bshape%20%3D%20circle%2C%20style%3Dfilled%2C%20fillcolor%3Dlightgrey%5D%3B%0D%0A%20%20InitializingBackend%20-%3E%20GotCommandComplete%20%5B%20label%20%3D%20%22PG3ReadyForQuery%22%2C%20color%3Dgreen%20%5D%3B%0D%0A%20%20InitializingBackend%20-%3E%20InitializingBackend%20%5B%20label%20%3D%20%22PG3BackendKeyData%22%2C%20color%3Dorange%20%5D%3B%0D%0A%20%20GotDataRow%20-%3E%20GotErrorResponseDuringSimpleQuery%20%5B%20label%20%3D%20%22PG3ErrorResponse%22%2C%20color%3Dred%20%5D%3B%0D%0A%20%20GotDataRow%20-%3E%20GotCommandComplete%20%5B%20label%20%3D%20%22PG3CommandComplete%22%2C%20color%3Dgreen%20%5D%3B%0D%0A%20%20GotDataRow%20-%3E%20GotDataRow%20%5B%20label%20%3D%20%22PG3DataRow%22%2C%20color%3Dorange%20%5D%3B%0D%0A%20%20GotErrorResponseDuringSimpleQuery%20-%3E%20WaitingForQuery%20%5B%20label%20%3D%20%22PG3ReadyForQuery%22%2C%20color%3Dgreen%20%5D%3B%0D%0A%20%20GotEmptyQueryResponse%20-%3E%20WaitingForQuery%20%5B%20label%20%3D%20%22PG3ReadyForQuery%22%2C%20color%3Dgreen%20%5D%3B%0D%0A%20%20GotEmptyQueryResponse%20-%3E%20GotErrorResponseDuringSimpleQuery%20%5B%20label%20%3D%20%22PG3ErrorResponse%22%2C%20color%3Dred%20%5D%3B%0D%0A%20%20Querying%20-%3E%20GotErrorResponseDuringSimpleQuery%20%5B%20label%20%3D%20%22PG3ErrorResponse%22%2C%20color%3Dred%20%5D%3B%0D%0A%20%20Querying%20-%3E%20GotCommandComplete%20%5B%20label%20%3D%20%22PG3CommandComplete%22%2C%20color%3Dgreen%20%5D%3B%0D%0A%20%20Querying%20-%3E%20GotRowDescription%20%5B%20label%20%3D%20%22PG3RowDescription%22%2C%20color%3Dorange%20%5D%3B%0D%0A%20%20Querying%20-%3E%20GotEmptyQueryResponse%20%5B%20label%20%3D%20%22PG3EmptyQueryResponse%22%2C%20color%3Dgreen%20%5D%3B%0D%0A%20%20Authenticating%20-%3E%20AuthenticatingWithMD5%20%5B%20label%20%3D%20%22PG3AuthenticationMD5Password%22%2C%20color%3Dorange%20%5D%3B%0D%0A%20%20Authenticating%20-%3E%20InitializingBackend%20%5B%20label%20%3D%20%22PG3AuthenticationOkMessage%22%2C%20color%3Dgreen%20%5D%3B%0D%0A%20%20AuthenticatingWithMD5%20-%3E%20InitializingBackend%20%5B%20label%20%3D%20%22PG3AuthenticationOkMessage%22%2C%20color%3Dgreen%20%5D%3B%0D%0A%20%20GotCommandComplete%20-%3E%20WaitingForQuery%20%5B%20label%20%3D%20%22PG3ReadyForQuery%22%2C%20color%3Dgreen%20%5D%3B%0D%0A%20%20GotCommandComplete%20-%3E%20GotErrorResponseDuringSimpleQuery%20%5B%20label%20%3D%20%22PG3ErrorResponse%22%2C%20color%3Dred%20%5D%3B%0D%0A%20%20GotCommandComplete%20-%3E%20GotCommandComplete%20%5B%20label%20%3D%20%22PG3CommandComplete%22%2C%20color%3Dgreen%20%5D%3B%0D%0A%20%20GotCommandComplete%20-%3E%20GotRowDescription%20%5B%20label%20%3D%20%22PG3RowDescription%22%2C%20color%3Dorange%20%5D%3B%0D%0A%20%20GotRowDescription%20-%3E%20GotErrorResponseDuringSimpleQuery%20%5B%20label%20%3D%20%22PG3ErrorResponse%22%2C%20color%3Dred%20%5D%3B%0D%0A%20%20GotRowDescription%20-%3E%20GotCommandComplete%20%5B%20label%20%3D%20%22PG3CommandComplete%22%2C%20color%3Dgreen%20%5D%3B%0D%0A%20%20GotRowDescription%20-%3E%20GotDataRow%20%5B%20label%20%3D%20%22PG3DataRow%22%2C%20color%3Dorange%20%5D%3B%0D%0A%7D

SVG render (zoom way in):