Overview
Many systems access data and services from a remote location. For these systems, we provide mechanisms to access data, services, or other functionality in a broad number of contexts

• TCP/IP
  TCP/IP is a widely supported protocol that operates in many technology environments. Our unicast access relies on TCP/IP as a way to achieve the broadest coverage of use cases

• Publisher & Subscriber 
  The publisher & subscriber model is used throughout our messaging protocols and other core systems. We are able to deliver performance and reliability while keeping our unicast access system consistent across the platform

• Request & Reply
  The request & reply model is also used broadly in our overall platform. By supporting a request & reply model, unicast access clients can issue one-off requests in cases where the publisher & subscriber model would be excessive

Service Director 
When dealing with unicast protocols, each client has a separate session to send and receive data. To manage the load balancing and performance of this model, the service director acts as a mechanism to optimally direct traffic

• Service discovery
  The service director acts as the arbiter of all the service offerings accessed by clients. As such, it can provide the ability for a unicast client to discover which services are currently offered by the director

• Load balancing 
  Improperly designed Unicast Services can experience load issues when required to send data to each subscriber separately. Our director is able to spread the load over all available handlers for a particular service

• Fault tolerance
  Due to the session based nature of unicast services, disconnects can happen when a service handler becomes unavailable. Our service director provides a mechanism to automatically redirect the client to a new service handler

Service Handlers 
Our service handler framework allows for quickly developing methods to interact with the requests from a unicast client. The framework reduces the complexity of implementation while allowing each handler to interact with requests uniquely

• Prebuilt list
  We have built sophisticated coverage for most of the core systems enabling out-of-the-box deployment. This includes delivering market data, order entry, position management, reference data, and other core offerings

• Director integration
  The service handler framework manages the interaction between the handler and the service director. This provides a mechanism to notify the directory of current availability and the current state of each handler instance

• Extensible
  The service handler system is architected to focus development on the data or service being offered. This enables our clients to build and maintain a custom service handler in an efficient manner

Entitlements 
As with our core system, entitlements are fundamental for data security and to meet regulatory requirements. We architected an entitlements system designed to solve the problems specific to the session-based nature of unicast

• Secure authentication
  To ensure that security is being enforced and to confirm the recipients of data and services are entitled, we implement a user & password login system. At the time of login, all user and password information is encrypted for security

• Topics based 
  Post authentication, access is controlled by our topic-based permissions system. A user can be provisioned for various levels of access to a specific topic or group of related topics

• Resource based 
  In addition to topic-based controls, a user can be controlled based on the amount of resources they have access to. Limiting a user's consumption of valuable resources benefits the health of the overall system