The Event Zero Application Services Web Services API allows access to Application Services, which serve as an interface to Event Zero's Event Processing Network (EPN). The Application Services framework allows direct interaction with Occurrence (for example, event data store or configuration management), and indirect interaction with deployed Agents.

The Event Zero Application Services Web Services API simplifies external access to EPN collected and processed data. Example functions using the API include:

• Start, maintain, and end an user session with Event Zero's Application Services.
• Publish events into the Event Processing Network (EPN) for further processing.
• Identify EPN resources (for example, possible event channels).
• Subscribe to receive event streams from various event channels.
• Receive event streams from Application Services.

Event Zero’s Application Services framework supports the minimum web services security standards required by industry, namely WS-I Basic Profile and WS-I Basic Security Profile. Additionally:

• API - Access to the API is regulated via user credentials. All client applications requesting an API must provide the correct network login and password. A session can be started as an anonymous user; however, this limits EPN access.
• EPN Configuration - Access to all node information in the network can be restricted using an attached read security group. All client applications using the Discovery service must have the correct user credentials before being allowed access.
• Events – Event access is controlled using a read security group defined on the event (explicit access), which contains all users allowed to view the event. All client applications subscribing to event delivery must have the correct permission before the event is delivered.

Because of the potential volume, fine granularity, and low semantic value of EPN events, Event Zero does not recommend dumping raw event streams on an enterprise messaging infrastructure such as an ESB (Enterprise Service Bus) or EMS (Enterprise Messaging System). Using Event Zero’s Application Services framework, events (raw, aggregate, summarized, or synthetic) can be easily aggregated into higher semantic load messages for publication via Web Services to enterprise messaging infrastructure, such as an ESB.

Event Zero’s Application Services Web Services API is designed to be extensible should additional web services specific to customer integration requirements be required.

Services used in the sequence diagram are listed in the table below.

API  Service		Description
Connect		Manages the connection between the client application and Application Services. Functions include connecting and disconnecting to the API, starting and stopping a subscription session, and tracking a session heartbeat.
Discover		Allows the client application to browse configuration-related information on the network server.
Subscribe		Allows clients to subscribe and unsubscribe to data feeds from the EPN.
Deliver		Delivers subscription data to client applications.
Publish		Allows clients to add events into the event network.