iLink 3 uses Simple Binary Encoding (SBE) optimized for low latency of encoding and decoding while keeping bandwidth utilization reasonably small. All FIX semantics are supported. This encoding standard describes the wire protocol for iLink 3 messages and is complimentary to other FIX standards for session protocol and application-level behavior.
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iLink 3 message schema supports the Simple Binary Encoding Specification - SBE version 1.0 release candidate 4
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Users must be registered with FIX Protocol Organization to access the Simple Binary Encoding Documentation and will need a User ID provided by FPL to logon to the site. |
The default data ranges and null indicator are listed below for each integer encoding.
Type | Min | Max | Null |
|---|---|---|---|
uInt8 | 0 | 254 | 255 |
uInt16 | 0 | 65534 | 65535 |
uInt32 | 0 | 4294967294 | 4294967295 |
uInt64 | 0 | 9223372036854775807 | 18446744073709551615 |
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- An overall message length including headers to support framing.
- An identifier of the encoding used in the message payload. This supports selecting the correct decoder in the case where multiple message encodings are used on a session. It also aids tools such as protocol analyzers to identify message protocols contained in network packets.
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The framing standard specifies that the framing header will always be encoded in little-endian byte order. |
Simple Open Framing Header (SOFH) (4 bytes) | SBE Header (8 bytes) | SBE Message (Variable Length) |
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Message Length: 2 bytes
| Block Length: 2 bytes
| Customer to CME Globex Messages Example:
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Encoding Type: 2 bytes
| TemplateID: 2 bytes
| CME Globex to Customer Messages Example:
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SchemaID: 2 bytes
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Version: 2 bytes
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In addition to the generic User Name/Password, client systems can connect using the same credential currently used for CME SFTP site. Additional information pertaining to the CME Secure SFTP site is available in CME Clearing Advisory Notice 15-105.
Schema Versioning
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The schema.xml file is versioned each time an update is made. All elements in a message schema are of the same version. The first version of a schema is version zero, and the version number is incremented each time a schema is changed.
iLink 3 message schema is backward compatible. Customers can send messages using the preceding version of a schema, however CME Globex will only send messages using the latest version of a schema.
Schema Header
The following is the layout of the SBE Schema header:
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