MEGACO Transactions

MEGACO transactions involve the
passing of commands and the responses to those commands. Commands
are directed towards terminations within contexts. In other words, every
command specifies a context ID and one or more termination IDs to which
the command applies. This is the case even for a command that requires
some action by an idle termination that does not exist in any specific context.
In such a case, the null context is applicable.
Multiple commands may be grouped together in a transaction structure
whereby a set of commands related to one context may be followed by a set
of commands related to another context. The grouped commands are sent
together in a single transaction request. This can be represented as
Transaction Request (Transaction ID {
ContextID1 {Command, Command, . . . Command},
ContextID2 {Command, Command, . . . Command},
ContextID3 {Command, Command, . . . Command} } )
No requirement specifies that a transaction request contain commands
for more than one context or even contain more than one command. It is
perfectly valid for a transaction request to contain just a single command
for a single context.
Upon receipt of a transaction request, the recipient executes the enclosed
commands. The commands are executed sequentially in the order specified
in the transaction request. Upon completed execution of the commands, a
transaction reply is issued. This has a similar structure to the transaction
request in that it contains a number of responses for a number of contexts.
A transaction reply may be represented as
TransactionReply (TransactionID {
ContextID1 {Response, Response, . . . Response},
ContextID2 {Response, Response, . . . Response},
ContextID3 {Response, Response, . . . Response} } ) 355