gidl/README.md

Gidl

Gidl (for Galois Interface Description Language) is a simple IDL for describing structured types and RPC-style interfaces.

Gidl has a type language which permits the user to define types using the following primitives:

• Atomic types:
  • Signed integers of 8, 16, 32, 64 bit width
  • Unsigned integers of 8, 16, 32, 64 bit width
  • IEEE 754 single and double precision floating point numbers
  • Boolean values
• User-defined Enum types:
  • Pairs of names and values, where names and values must have a one-to-one correspondence
  • User specified representation width (8, 16, 32, or 64 bits)
• User-defined Newtypes:
  • Wraps an existing atomic or enum type with a new type
• User-defined Structures:
  • Set of named fields. Corresponds to a record or a C struct.
  • All fields are atomic, enum, or newtypes.

Gidl interfaces are composed of the following primitives:

• Streams, which are sent from server to client periodically
• Attributes, which are read and written according to requests by the client. Attributes have a user defined read/writable permissions.

Interfaces can be composed by subtyping - java style multiple inheritance. (We expect interface composition may change in the future.)

Protocol drift is detected by identifying each stream and attribute message on the wire by a hash of its name, its type, and all child types. Therefore

IDL format

The gidl IDL uses a s-expression based format.

See example format: tests/example.idl

Backends

Gidl currently has backends for:

• Native Haskell
• Ivory types, and Tower interfaces

Build and Test

Use the create-sandbox target in the Makefile to create a local cabal sandbox and install all dependencies.

The default target builds the gidl library. You can then use cabal run gidl -- <OPTIONS> to run the code generator. Use the --help option to get usage information.

Use the test target in the Makefile to generate and test each backend implementation.