Product Overview

This page gives a high-level picture of what the Handler is, where it sits in a trading system, and how it relates to the other OnixS products. Read it first if you are evaluating the product or deciding which OnixS SDK your project actually needs.

What the Handler Is

The OnixS C++ ICE iMpact Multicast Price Feed Handler is the C++ edition of the ICE iMpact Market Data Handler SDK, a member of the OnixS directConnect family of venue-specific SDKs.

It is a market data library: it offers an API to receive market data from the ICE iMpact multicast feed. The Handler decodes the protocol, maintains order books and market states on your behalf, and reports the results to your application through callbacks. It ships as a native C++ library (see Distribution Package) that you link into your own process - not as a server, a daemon, or an end-user application.

How the Handler Fits into an Application

The Handler owns everything between ICE and your application's event handlers. It uses both transports the feed defines: a TCP connection to the ICE server, used to log in and obtain the product definitions, and the multicast channels, which carry the live update messages and the snapshots needed for startup and recovery. Incoming packets are received and decoded by the Feed Engine's worker threads, applied to the order books the Handler maintains, and reported to your code through listeners.

In particular, the Handler is responsible for:

• Logging in over TCP and downloading the Product Definitions - the process the API calls Security Definition Recovery - and keeping them in a local Product Definitions Cache between sessions.
• Joining the multicast groups and listening to the live update and snapshot channels - see Subscribing to Multicast Groups, Feed Engine Setup, and the Threading Model.
• Detecting gaps and recovering the books automatically, including handling the exchange's Maintenance Window and session-number changes - see Error Handling and Recovery and Understanding Handler States.
• Maintaining order books and market states for every subscribed market - see Manipulating Order Books.
• Reporting everything to your code through Event Listeners.

Your application is responsible for the trading logic on top: what to subscribe to, what to do with the book updates, and how to act on them.

What the Handler Is Not

Being explicit about the boundaries usually saves an evaluation cycle:

• It is not an order entry or trading solution. The iMpact Multicast Price Feed is a one-directional market data feed; the Handler cannot submit, amend, or cancel orders. Order entry for ICE is covered by separate products.
• It is not a FIX Engine and does not need one. The Handler implements the native binary iMpact protocol and has no dependency on the OnixS C++ FIX Engine or on any FIX library. See Relation to the OnixS FIX Engine.
• It is not a market data source or a subscription. The library gives you the technology to consume the feed; the feed itself, the credentials, and the entitlements come from ICE. See the caution in Getting Started.
• It is not a ready-to-run application. The distribution package ships samples and tools that can be run as-is for testing, but they are reference implementations meant to be a starting point for your own code, not products in their own right.

Capabilities at a Glance

Area	What the Handler provides
Instruments	Futures, options, OTC products, and Futures and Options UDS (user-defined strategies)
Book depth	Full Order Depth (FOD), Top 5 and Top 10 Price Levels, Top of Book (options only)
Price types	Non-implied and full-implied markets, subscribed independently
Subscription granularity	Per market, per multicast group, or per market type - see Subscribing to Multicast Groups and Selecting Securities of Interest
Recovery	Automatic gap detection, snapshot-based book recovery, reconnects, and session-number handling
Threading	Multiple Handlers over a shared or dedicated Feed Engine thread pool, with thread affinity control
Offline processing	Replay of recorded logs (Log Replay) and third-party captures (PCAP Replay)
Raw access	Message Deserialization and packet-level processing for custom pipelines
Verification	Local Order Book Verification and conformance testing tools (Conformance Tools Sample)
Performance	Low latency and high throughput - see Low Latency Best Practices

Language Editions

The same ICE iMpact Market Data Handler SDK is offered for C++, .NET, and Java. The editions share the protocol coverage and the overall design - Handler, subscriptions, and listeners - but each one is a separate product with an API idiomatic to its language, and some concepts exist in one edition only. This Guide documents the C++ edition only. Contact Support if you need one of the other editions.

Other OnixS Solutions for ICE

The Handler covers market data. The remaining ICE workflows are covered by sibling SDKs from the same directConnect family, all available for C++, .NET, and Java:

Solution	Protocol	Purpose
ICE iMpact Market Data Handler SDK	iMpact multicast	This product. Real-time market data, order books, and market state.
ICE Binary Order Entry (BOE) Handler SDK	ICE BOE (binary)	Lowest-latency order entry over the ICE Binary Order Gateway.
ICE FIX Order Entry (ICE OS) Handler SDK	FIX	Order entry and execution over the ICE FIX order routing gateway.
ICE FIX Private Order Feed (ICE POF) Handler SDK	FIX	Private drop-copy style feed of your own order and execution activity.
ICE FIX Trade Capture (ICE TC) Handler SDK	FIX	Post-trade reporting and trade capture.

A typical ICE deployment pairs this Handler with one of the order entry SDKs: the Handler feeds the strategy with prices, and the BOE or FIX Order Entry Handler sends the resulting orders.

Note

The products are independent libraries and can be combined freely in one application. If you do combine them, note the static-linking constraint described in Distribution Package - only one OnixS static library may be linked into an application, so use shared libraries when you need several handlers in the same process.

Relation to the OnixS FIX Engine

The OnixS C++ FIX Engine is a general-purpose FIX protocol implementation used to build applications that speak FIX. It is a different kind of product and is not required by this Handler.

The distinction matters when reading OnixS materials that mention ICE:

• This Handler implements the native ICE iMpact binary protocol end to end. It is self-contained.
• The ICE FIX-based handlers listed above implement specific ICE FIX services as ready-made, pre-certified SDKs.
• The ICE Trading Client found in the FIX Engine distribution package is a sample application shipped with the FIX Engine - a reference implementation demonstrating how to talk to ICE over FIX, not a standalone product.

Relation to Other directConnect Handlers

OnixS provides equivalent market data handlers for other venues - CME Globex, Cboe, Eurex, B3, Euronext, and others. They are separate products with venue-specific APIs, because each exchange's protocol and book semantics differ. However, their C++ editions follow the same architectural concepts: a Handler object configured through settings, a Feed Engine owning the network threads, subscriptions, and listener-based event delivery. Experience with one C++ directConnect handler transfers well to another.

Where to Go Next

• System Requirements - supported platforms, compilers, and deployment environments.
• General - packaging, versioning, and distribution details.
• Getting Started - the first working application, step by step.
• Samples - the sample applications shipped with the distribution package.
• Support - how to reach the OnixS Support Team.