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About Siebel Internet Session Network API

Siebel Internet Session Network API (SISNAPI) is a Siebel proprietary message-body format running on top of TCP/IP. SISNAPI is used for communications between the Siebel Application Interface, Siebel Gateway, and Siebel Servers.

When a client request comes to the Siebel Application Interface, the Siebel Application Interface intercepts the request and forwards it in SISNAPI format. The SISNAPI message-body format has the following parts:

• HTTP header
• Object Manager method name
• Method arguments as key-value pairs

HTTP Header

When the Siebel Application Interface requests a new connection, the initial packets of the first SISNAPI message contain an HTTP header. This header includes a Uniform Resource Locator (URL) that provides routing information to the Siebel Enterprise Server, Siebel Server, and server component.

Connection Multiplexing

SISNAPI TCP/IP connections are specific to an Application Object Manager on one Siebel Server. Before a new connection is opened, the Application Object Manager checks to see whether an existing connection is available. If so, then an existing connection is used. Once the connection is established, it remains open to be used by subsequent messages in the session or to be reused by other sessions. For more information about connection multiplexing, see Siebel Performance Tuning Guide.

Transport Layer Security (TLS)

You configure Transport Layer Security (TLS) encryption and authentication for SISNAPI connections. For more information, see Siebel Security Guide. See also the Siebel Installation Guide for the operating system you are using.

User Request Types

The Siebel Application Interface generates three types of user requests. Each request type creates a new connection to a Siebel Server through the load balancer: initial request, retry request, and reconnect request. The Siebel native load balancing functionality is able to recognize and route these request types.

• Initial request. The Siebel Application Interface generates this request to start a new user session as follows:
  • The Siebel Application Interface receives the request to start a user session.
  • The Siebel Application Interface creates the message. The HTTP header specifies the Siebel Enterprise Server and the desired server component. The message does not specify a Siebel Server name.
  • The Siebel Application Interface sends the request message to Siebel Gateway.
  • The Siebel Gateway returns a connect string for a suitable component: the least-loaded Application Object Manager running on one of the Siebel Servers that support that component.
  • The Siebel Application Interface in turn routes the request to the Siebel Server where this Application Object Manager is running. If no connection exists to the Siebel Server, then a new one is created.
  • The Siebel Server receives the message and creates a new user session. The Siebel Server forwards address information back to the Siebel Application Interface.
  • The Siebel Application Interface creates a cookie containing the address information. The Siebel Application Interface receives the cookie information in subsequent session requests. The Siebel Application Interface includes this information in the HTTP header.
  • The load balancer receives subsequent messages and forwards them directly to the specified Siebel Server and server component through the open connection.
• Retry request. If a Siebel Server rejects an initial request, then the request is routed back to the Siebel Application Interface and the following occurs:
  • The Siebel Application Interface modifies the URL contained in the HTTP header by appending the letters RR to it.
  • The Siebel Application Interface resends the request to the Siebel Gateway for a suitable component on a different Siebel Server.
• Reconnect request. The Siebel Application Interface generates a reconnect request when it receives a user request for an existing user session that does not have a SISNAPI connection. The Siebel Application Interface uses the session cookie information to include the Siebel Server address in the HTTP header.

  The reconnect request opens a new connection. Reconnect requests can occur for several reasons:

  • The connection timeout is exceeded and the connection is closed.
  • The network environment closes the connection, for example due to a firewall time-out.