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.