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The Dafny server is a command line utility that allows non-.Net editors to take
advantage of Dafny's caching facilities, as used by the Dafny extension for
Visual Studio. The server is essentially a REPL, which produces output in the
same format as the Dafny CLI; clients thus do not need to understand the
internals of Dafny's caching. A typical editing session proceeds as follows:
* When a new Dafny file is opened, the editor starts a new instance of the
Dafny server. The cache is blank at that point.
* The editor sends a copy of the buffer for initial verification. This takes
some time, after which the server returns a list of errors.
* The user makes modifications; the editor periodically sends a new copy of
the buffer's contents to the Dafny server, which quickly returns an updated
list of errors.
The client-server protocol is sequential, uses JSON, and works over ASCII
pipes by base64-encoding queries. It defines one type of query, and two types
of responses:
Queries are of the following form:
verify
<base64 encoded JSON payload>
[[DAFNY-CLIENT: EOM]]
Responses are of the following form:
<list of errors and usual output, as produced by the Dafny CLI>
[SUCCESS] [[DAFNY-SERVER: EOM]]
or
<error message>
[FAILURE] [[DAFNY-SERVER: EOM]]
The JSON payload is an array with 4 fields:
* args: An array of Dafny arguments, as passed to the Dafny CLI
* source: A Dafny program, or the path to a Dafny source file.
* sourceIsFile: A boolean indicating whether the 'source' argument is a
Dafny program or the path to one.
* filename: The name of the original source file, to be used in error
messages
For small files, embedding the Dafny source directly into a message is
convenient; for larger files, however, it is generally better for performance
to write the source snapshot to a separate file, and to pass that to Dafny
by setting the 'sourceIsFile' flag to true.
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Clément Pit--Claudel