8 Managing Client Initiated Connections
This chapter describes how to manage client-initiated connections in Oracle Communications Converged Application Server.
The Session Initiation Protocol (SIP) outbound specification, as defined in
RFC-5656, https://tools.ietf.org/html/rfc5656,
specifies techniques for keeping connections that a User Application (UA) establishes
alive, especially in environments where the UA is behind a Network Address Translation
(NAT) device or a firewall. A SIP Servlet application may take different roles with
respect to those defined in RFC 5626 for keeping the connections alive. For example, a
SIP Servlet application may act as an authoritative proxy, an edge proxy, a registrar,
or a UA. Refer to RFC 5626 for more details about the exact procedure for managing
client-initiated connections.
Converged Application SIP Servlet containers support sending keep alive messages from a user agent as well as responding to keep alive messages defined in RFC 5626. They also support a FlowBinder interface for managing the connections as described in the following sections.
In RFC 5626, a flow is a transport-layer association between two hosts that is represented by the network address and port number of both ends and by the transport protocol. For Transport Control Protocol (TCP), a flow is equivalent to a TCP connection. For User Datagram Protocol (UDP), a flow is a bidirectional stream of datagrams between a single pair of Internet Protocol (IP) addresses and ports of both peers.
From a SIP Servlet application's perspective, the flow is a transport layer association between the SIP Servlet container and another SIP endpoint on a specific transport.
Table 8-1 describes the Flow interface's methods.
Table 8-1 Flow Interface Methods
| Method | Description |
|---|---|
|
getToken() |
Retrieves the flow token representing a flow. |
|
getLocalURI() |
Retrieves the SipURI representation of the local end of transport association. |
|
getRemoteURI() |
Retrieves the SipURI representation of the remote end of transport association. |
|
release() |
Indicates to the container that the application will not use the Flow object any more. |
|
isActive() |
Indicates whether the flow is active or not. Flow becomes inactive when it is closed. |
Applications may get an instance of a Flow that represents this transport layer association by using the SipSession.getFlow(), Proxy.getFlow(), or ProxyBranch.getFlow() methods.