Working with Mediator Framework

Transcription

1 CHAPTER 2 This chapter describes the Mediator framework and includes the following sections: Framework Overview, page 2-1 Configurable Nodes, page 2-2 Composite Nodes, page 2-4 Getting and Setting Node Values, page 2-5 Framework Overview Mediator framework is the software application that provides the core function of the Mediator. The framework gives the Mediator its Multi-Protocol Exchange capabilities, including the following: Assembling a running system from configuration data. Getting and setting values. Processing raw data. Presenting data from disparate sources in a uniform format. Making data easily available to end users. Providing services such as data logging and HTTP services. Providing an environment for custom system configuration. Providing an environment for developing custom solutions. There are two types of framework nodes: Configurable Nodes Composite Nodes All nodes inherit framework from one of two base node types. The composite node may hold child nodes; configurable nodes, on the other hand, are leaf nodes in the hierarchy. The composite node data type is an extension to the configurable node, so all the methods discussed for configurable nodes apply to composite nodes as well. For more information on the framework, see the Cisco Network Building Mediator Release User Guide. 2-1

2 Configurable Nodes Chapter 2 Configurable Nodes This section explains the operations that you can perform with the configurable nodes and includes the following topics: Starting and Stopping Nodes, page 2-2 Starting and Stopping Nodes, page 2-2 Getting and Setting Attributes, page 2-3 Configuring Nodes configure() This section lists the standard APIs used for configurable nodes and includes the following topics: configure(), page 2-2 configuration(), page 2-2 This API function allows the client to configure those parameters or attributes of the node that have been specified as configurable. Requires a single hash map type parameter providing name/value pairs for configurable attributes of the node. The values are usually primitive type, and the appropriate conversions are applied internally. Certain parameters will require explicit values, whereas others may have default values. The proper mechanism for configuring a parent node and name is via this method. Note Invocations of configure() which modify the configuration of a node in the framework are never persisted. Each time the framework starts or restarts, only the configuration information specified in the Broadway XML configuration file is used. configuration() This API function allows the client to query a node for configured attributes. Returns a hash map analogous to the hash map with which the node was configured. Starting and Stopping Nodes This section lists the standard APIs used for starting and stopping nodes and includes the following topics: 2-2

3 Chapter 2 Configurable Nodes start(), page 2-3 stop(), page 2-3 start() This API function allows the client to perform node-specific implementation to initialized configured nodes. stop() This API function allows the client to perform node-specific implementation to clean up node resources, stop associated processes, and scheduled entries. Getting and Setting Attributes getattr() setattr() This section lists the standard APIs used for getting and setting attributes and includes the following topics: getattr(), page 2-3 setattr(), page 2-3 hasattr(), page 2-4 This API function provides the client with a method-based mechanism for retrieving arbitrary named attributes of a node. Requires single parameter naming attribute to retrieve. Returns value of attribute if it exists. This API function provides the client with a method-based mechanism for setting the value of arbitrarily named attributes of a node. 2-3

4 Composite Nodes Chapter 2 hasattr() Requires two parameters: name of attribute to be set, and the value it should be set to. This API function provides the client with a method-based mechanism for querying the node about the existence of attributes. Requires single parameter: name of attribute to check on. Returns Boolean value indicating whether the attribute exists. Composite Nodes This section describes the extended operations that you can perform with the composite nodes and includes the following topics: Starting and Stopping Nodes, page 2-4 Working with Node Children, page 2-4 Starting and Stopping Nodes Composite Node extends the actions of the configurable nodes such that their invocation propagates to all the node descendants. Starting or stopping a parent node automatically starts and stops each of the child nodes in the parent also. Working with Node Children has_child() This section lists the standard APIs used for manipulating node children and includes the following topics: has_child(), page 2-4 get_child(), page 2-5 children_nodes(), page 2-5 children_names(), page 2-5 This API function allows the client to query the node for existence of a child node based on the node name. 2-4

5 Chapter 2 Composite Nodes get_child() Requires on parameter: name of child node to check for. Returns Boolean value indicating whether child with specified name exists. This API function allows the client to query the node for a child node reference by name. Requires one parameter: the name of the child node to get. Returns child node instance if one exists. Note Although this method is part of the composite node API, invoking it remotely over XML-RPC will result in an error. It is described here for completeness. children_nodes() This API function allows the client to query the node for a list of child nodes. Returns list of child node instances. Note Although this method is part of the composite node API, invoking it remotely over XML-RPC will result in an error. It is described here for completeness. children_names() This API function allows the client to query the node for a list of child node names. Accepts no parameter. Returns list of child node names. Getting and Setting Node Values This section lists the additional API functions that you can perform with the composite nodes, these functions are not defined by the base classes. This section includes the following topics: get(), page 2-6 set(), page

6 Composite Nodes Chapter 2 get() This API function allows the client to get the current value of a point node. Returns current value of node. set() This API function allows the client to set the current value of a point node. Requires single parameter: new value of node. 2-6