5.4.6 notify

Notify process exchanges information on cache supplies and demands with other MEDIATEX servers.

Notice: messages only contains records related to the original sender servers. When receiving a message, server forgives and replace all records previously sends by the related server. Consequently, empty message may be sent too.

Process conceptual model:

• Events in

  [notify]

  from misc (see misc): ask notify by setting a value into share memory and sending a signal.

  <notify>

  from a remote notify process: receive a socket query providing remote cache content index.

• Processing
  • The policy is, sender servers tells each others:
    • final demands they have to extract,
    • local supplies (presently into theire cache) that may be useful to others or are unsafe.
    • Receiver server returns 240.
  • However:
    • servers do not try to send messages to unreachable NAT’s client servers,
    • NAT client servers do not send messages to servers that cannot reach them.
  • So, NAT gateway servers do:
    • forward messages unchanged to its NAT’s client servers,
    • relay (doing masquerade) final demands from its NAT’s client servers.
• Events out

  <notify>

  to a remote notify process: send a socket query providing local cache content index.

• Input data
  • /etc/mediatex/mdtx.conf (see mdtx.conf)
  • ~mdtx/md5sums/mdtx-COLL.md5 (see mdtxCOLL.md5)
  • /etc/mediatex/mdtx-COLL/servers.txt (see servers.txt)

Example: Servers communication between private networks

Code:

src/server/notify.c