This page provides a brief introduction to the Slice interfaces comprising the IceStorm service. See the online Slice API Reference XREF for the Slice documentation.
On this page:
The TopicManager
Interface
The TopicManager
is a singleton object that acts as a factory and repository of Topic
objects. Its interface and related types are shown below:
module IceStorm { dictionary<string, Topic*> TopicDict; exception TopicExists { string name; }; exception NoSuchTopic { string name; }; interface TopicManager { Topic* create(string name) throws TopicExists; idempotent Topic* retrieve(string name) throws NoSuchTopic; idempotent TopicDict retrieveAll(); idempotent Ice::SliceChecksumDict getSliceChecksums(); }; };
The create
operation is used to create a new topic, which must have a unique name. The retrieve
operation allows a client to obtain a proxy for an existing topic, and retrieveAll
supplies a dictionary of all existing topics. The getSliceChecksums
operation returns Slice checksums for the IceStorm definitions.
The Topic
Interface
The Topic
interface represents a topic and provides several administrative operations for configuring links and managing subscribers.
module IceStorm { struct LinkInfo { Topic* theTopic; string name; int cost; }; sequence<LinkInfo> LinkInfoSeq; dictionary<string, string> QoS; exception LinkExists { string name; }; exception NoSuchLink { string name; }; exception AlreadySubscribed {}; exception BadQoS { string reason; }; interface Topic { idempotent string getName(); idempotent Object* getPublisher(); idempotent Object* getNonReplicatedPublisher(); Object* subscribeAndGetPublisher(QoS theQoS, Object* subscriber) throws AlreadySubscribed, BadQoS; idempotent void unsubscribe(Object* subscriber); idempotent void link(Topic* linkTo, int cost) throws LinkExists; idempotent void unlink(Topic* linkTo) throws NoSuchLink; idempotent LinkInfoSeq getLinkInfoSeq(); void destroy(); }; };
The getName
operation returns the name assigned to the topic, while the getPublisher
and getNonReplicatedPublisher
operations return proxies for the topic's publisher object.
The subscribeAndGetPublisher
operation adds a subscriber's proxy to the topic; if another subscriber proxy already exists with the same object identity, the operation throws AlreadySubscribed
. The operation returns a proxy for a subscriber-specific publisher object.
The unsubscribe
operation removes the subscriber from the topic.
A link to another topic is created using the link
operation; if a link already exists to the given topic, the LinkExists
exception is raised. Links are destroyed using the unlink
operation.
Finally, the destroy
operation permanently destroys the topic.