WHAT-IS: parent versa child

Table Of Contents

• Definition
• What is a "parent" Context ?
• What is a "child" Context ?

Definition

parent	the first context of a client/server communication
child	the second or more context of a client/server communication

What is a "parent" Context ?

• the parent is the first context created
• every new parent-context on the client creates a new communication to a server.
• every new parent-context on the client connect to a new parent-context on the server

    !on local host!              !on remote host!
  
        server1                      server2
           |                            |
   parent-context-1             parent-context-2
           |                            |
  (#MqConfigS::server)   (#MqConfigS::server --fork --tcp --port)
           |                            |                      server
  - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
           |                            |                      client
       (--pipe)               (--tcp --host --port)
           |                            |
   parent-context-1             parent-context-2
           |                            |
           ^-----------client-----------^
  
                   !on local host!
  

• every new parent-context on the server is using a new process image
• the parent-context is controlling the socket communication interface
• a context is a parent-context if no MqConfigS::parent configuration is available
  • tclmsgque Example: connect to a parent on a local host

     set Parent1 [tclmsgque MqS -name MyName --pipe @ server];
    

  • tclmsgque Example: connect to a parent on a network reachable host

     set Parent2 [tclmsgque MqS -name MyName --tcp --host RemoteHost --port RemotePort];
    

What is a "child" Context ?

• the child-context is the second or more context created
• the child-context is created if the MqConfigS::parent was added to the config argument of MqLinkCreate
• every new child-context on the client is creating a new child-context on the already started server
• every new child-context is totally independent from the server-context setup and is able to serve its on services
• the child-context is using the parent-context as a tunnel.

    !on local host!                                  !on remote host!
  
        server1---------x                     x----------server2
           |            |                     |             |
           |     child-context-1       child-context-2      |
           |            |                     |             |                      server
   parent-context-1-----x                     x-----parent-context-2
           |                                                |
  (MqConfigS::server)                  (MqConfigS::server --fork --tcp --port)
           |                                                |
  - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
           |                                                |
       (--pipe)                                   (--tcp --host --port)
           |                                                |
   parent-context-1-----x                     x-----parent-context-2
           |            |                     |             |                      client
           |     child-context-1       child-context-2      |
           |            |                     |             |
           x------------x--------client-------x-------------x
  
                             !on local host!
  

• a child-context can be a parent of an other child-context. A tree like structure is crated.
• the child-context is using the communication interface from the parent-context
  using tclmsgque code

  set Ctx [tclmsgque MqS -name MyName ...]; # I'm a parent
  set Cl1 [tclmsgque MqS -parent $Ctx];     # I'm a child
  set Cl2 [tclmsgque MqS -parent $Ctx];     # I'm an other child
  set Cl3 [tclmsgque MqS -parent $Cl1];     # I'm an other child, even if my '-parent' is a child
  

• if a context is deleted (parent or child) the depending context (parent or child) is deleted too.
• if a context is deleted the depending context-tree is deleted too.