| Oracle® Communications Converged Application Server Concepts Release 5.1 Part Number E27705-01 |
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PDF · Mobi · ePub |
| Oracle® Communications Converged Application Server Concepts Release 5.1 Part Number E27705-01 |
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PDF · Mobi · ePub |
This chapter introduces the Oracle Communications Converged Application Server.
Converged Application Server is a carrier-class Java EE application server that has been extended with support for the Session Initiation Protocol (SIP) and a number of operational enhancements that allow it to meet the demanding requirements of next-generation Internet Protocol-based communications networks. The Converged Application Server implementation is based on Oracle's widely deployed and time-tested Java EE-compliant WebLogic Server product.
In a typical IMS deployment, Converged Application Server fills the role of the IMS SIP Application Server. Figure 1-1 shows the Converged Application Server in the context of the functional architecture for the provision of service in the IMS, as specified by 3GPP TS 23.002, "Network Architecture."
Converged Application Server supports all of the standard Oracle WebLogic Server programming interfaces and facilities, such as JTA, JAF, JMS, JNDI, JDBC, and EJB. Converged Application Server also supports the protocols typically associated with a standards-compliant Java EE application server, including RMI over IIOP, HTTP 1.1, LDAP, SMTP, POP, IMAP, and SNMPv2.
Converged Application Server builds upon the base Java EE programming model by integrating a SIP Servlet Container that is compliant with the JSR-000116 SIP Servlet API specification. This “converged” container provides an execution environment for applications containing both HTTP and SIP protocol handling components, as well as other protocols such as Diameter.
The “SIP Stack” of Converged Application Server is fully integrated into the SIP Servlet container and is substantially more powerful and easier to use than a traditional protocol stack.
As shown in Figure 1-2, Converged Application Server combines the SIP Servlet container with EJB and HTTP Servlet containers, supporting application convergence through session context sharing.
The SIP Servlet API defines a higher layer of abstraction than simple protocol stacks provide and frees the developer from concern for the mechanics of the SIP protocol itself. Specifically, the API handles the syntactic validation of received requests, transaction layer timers, generation of non-application-related responses, generation of fully-formed SIP requests from request objects (which involves correct preparation of system headers and generation of syntactically correct SIP messages), and lower-layer transport protocols (such as TCP, UDP or SCTP).
The Servlet container distributes request and response objects to components in a structured way, maintains awareness of the state of the larger, converged SIP and HTTP application session, and manages the end-to-end object lifecycle, including resource, transaction, and session state management. The converged SIP and HTTP container thereby frees the developer from much work (and opportunity for error) and allows deployed applications to inherit the high-availability, performance, and operational features provided by the robust Converged Application Server container implementation.
The SIP Servlet API greatly simplifies the task of implementing SIP User Agents, Proxies and Back-to-Back-User-Agents, and it narrows the developers exposure to operational concerns such as resource management, reliability, manageability and interaction between services. (See Chapter 2, "Developing Applications for Converged Application Server," for more information.)
The SIP Servlet API is the ideal choice for exposing the full capabilities of the SIP protocol in a Java and Java EE middleware solution. No equivalent standard exists for defining an Application Programming Interface or programming model that is as well suited to meet both the needs of the application developer and the operational requirements of the service provider.
Converged Application Server incorporates a number of architectural features that allow for its deployment as a highly-available, fault tolerant Single System Image cluster.
The Converged Application Server cluster architecture is based on a multi-tier model in which a load balancer distributes SIP requests to a stateless Engine Tier (often referred to as “Engines”). The Converged Application Server includes a SIP-aware load balancer, the Converged Load Balancer, which distributes traffic among one or more engine tier server instances or clusters.
The engine tier processes all signaling traffic and replicates transaction and session state information to SIP data tier “partitions”. Each partition may consist of one or more replicas distributed across servers or server blades (cluster members). This clustering capability, combined with the Converged Load Balancer or third-party load balancer, transparently provides services with Telco-grade availability, scalability, and fault tolerance (session retention), ensuring that ongoing sessions are not affected by the failure of individual cluster members. A production deployment of Converged Application Server has no single point of failure.
Converged Application Server provides several tools and mechanisms for configuring and administering the Converged Application Server implementation. They include:
Administration Console: Converged Application Server provides an extensive Web-based GUI that supports all configuration management, including deployment of applications, configuration of connectivity, and other common tasks. This interface offers secure, role-based administration of servers from any terminal that has access to the Administration Server and supports a standard HTML Web browser.
JMX: Converged Application Server interoperates with standard network element management systems via the Java Management eXtensions standard. Many common network management suites support JMX natively, which is the standard management technology for Java applications.
SNMP: Converged Application Server interoperates with standard network element management systems via use of the Simple Network Management Protocol, V2. The Converged Application Server SNMP MIB complies with MIB II. Converged Application Server also enables developers to send SNMP traps from within application code, as described in Generating SNMP Traps from Application Code in Developing SIP Applications.
Converged Application Server also uses the SNMP features available in Oracle WebLogic Server 11g, such as SNMP proxying. See the WebLogic SNMP Management Guide in the Oracle WebLogic Server documentation for more information.
Command-line Interface: Converged Application Server provides a Command Line Interface (CLI) for manual runtime configuration from any network terminal with secure access to the Administration Server.
The Converged Application Server Web Administration Console is used for the following tasks:
Configuring application container and related resource properties
Configuring security
Deploying applications or components
Monitoring resource usage
Displaying log messages
Starting and stopping servers
In addition to providing access to the configuration for the implementation, the Converged Application Server Administration console serves as a monitoring and troubleshooting interface. It provides a convenient interface for observing system-wide usage metrics, including SIP traffic activity.
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