Add options and is_busy functionality to server

 - Re-factor server code structure
 - Rename arguments request and repository
 - Add options to handler functions
 - Add minimal is_busy logic

src/DiffFusionServer.jl

@@ -9,11 +9,19 @@ using Sockets
 
 include("client/Requests.jl")
 
+# server configurations
 include("server/Config.jl")
 include("server/Errors.jl")
 include("server/Info.jl")
+include("server/Options.jl")
 include("server/Repository.jl")
-include("server/Router.jl")
 include("server/Utils.jl")
 
+# server handlers and router
+include("server/Infos.jl")
+include("server/Gets.jl")
+include("server/Posts.jl")
+include("server/Deletes.jl")
+include("server/Router.jl")
+
 end

src/server/Deletes.jl

@@ -0,0 +1,33 @@
+
+"""
+    api_delete(
+        request::HTTP.Request,
+        repository::AbstractDict,
+        options::Options,
+        )
+
+Delete an object from repository.
+
+Request header must contain field 'alias'. The value of field
+'alias' is the object alias of requested object in the server
+repository.
+"""
+function api_delete(
+    request::HTTP.Request,
+    repository::AbstractDict,
+    options::Options,
+    )
+    res = _check_for_header_field(request, "alias")
+    if isa(res, HTTP.Message)
+        return res
+    end
+    res = _check_for_alias_in_repository(res, repository)
+    if isa(res, HTTP.Message)
+        return res
+    end
+    alias = res
+    obj_type = string(typeof(repository[alias]))
+    delete!(repository, alias)
+    msg = "Deleted object with alias " * alias * " and object type " * obj_type * "."
+    return HTTP.Response(_NO_HTTP_ERROR, JSON3.write(msg))
+end

src/server/Errors.jl

@@ -29,7 +29,7 @@ end
 
 Create error response for unknown server operation in http header.
 
-Allowed operations are COPY and BUILD.
+Allowed operations are COPY and BUILD and BUILD_ASYNC.
 """
 function _error_operation_not_implemented(op::AbstractString)
     HTTP.Response(213, JSON3.write("Operation " * op * " is not implemented."))
@@ -122,3 +122,26 @@ function _error_build_async_fail(alias::AbstractString, e::Exception)
     msg = "Cannot create Future object for alias " * alias * ".\n" * string(e)
     return HTTP.Response(221, JSON3.write(msg))
 end
+
+"""
+    _error_option_not_implemented(option_field::AbstractString, option_value::AbstractString)
+
+Create error response for unknown server option/value combination in http header.
+"""
+function _error_option_not_implemented(option_field::AbstractString, option_value::AbstractString)
+    HTTP.Response(222, JSON3.write("Option " * option_field * " with value " * option_value * " is not implemented."))
+end
+
+
+## Use standard error codes in below error functions
+
+"""
+    _error_server_is_busy()
+
+Create an error response for a rejected (POST) operation due to *is_busy* flag.
+"""
+function _error_server_is_busy()
+    msg = "Cannot process POST request because server is flagged as busy."
+    return HTTP.Response(429, JSON3.write(msg))
+end
+

src/server/Gets.jl

@@ -0,0 +1,147 @@
+
+"""
+    api_get(
+        request::HTTP.Request,
+        repository::AbstractDict,
+        options::Options,
+        )
+
+Return the object with requested alias header field in body of response.
+
+This operation does not modify the server repository.
+
+Request header must contain fields 'alias' and 'op'. The value of field
+'alias' is the object alias of requested object in the server
+repository. Value of field 'op' is 'COPY' or 'BUILD'.
+
+For COPY operation, the requested data is directly written to JSON format.
+
+For BUILD operation, the requested data is first serialised using DiffFusion
+serialise operation. Then the serialised object is written to JSON format.
+
+The resulting JSON object is returned via the response body.
+"""
+function api_get(
+    request::HTTP.Request,
+    repository::AbstractDict,
+    options::Options,
+    )
+    #
+    res = _check_for_header_field(request, "alias")
+    if isa(res, HTTP.Message)
+        return res
+    end
+    res = _check_for_alias_in_repository(res, repository)
+    if isa(res, HTTP.Message)
+        return res
+    end
+    alias = res
+    res = _check_for_header_field(request, "op")
+    if isa(res, HTTP.Message)
+        return res
+    end
+    op = uppercase(res)
+    if !(op in _OPERATIONS)
+        return _error_operation_not_implemented(op)
+    end
+    obj = repository[alias]
+    local out_obj
+    if op==_BUILD_OP
+        try
+            out_obj = DiffFusion.serialise(obj)
+        catch e
+            return _error_object_serialisation_fail(alias, e)
+        end
+    else
+        out_obj = obj
+    end
+    local json3_string
+    try
+        json3_string = JSON3.write(out_obj)
+    catch e
+        return _error_create_json_string_fail(alias, e)
+    end
+    # finally return object...
+    return HTTP.Response(_NO_HTTP_ERROR, json3_string)
+end
+
+
+"""
+    api_bulk_get(
+        request::HTTP.Request,
+        repository::AbstractDict,
+        options::Options,
+        )
+
+Return a list of objects for a list of aliases.
+
+This operation does not modify the server repository.
+
+Request header must contain field 'op'. Value of field 'op' is
+'COPY' or 'BUILD'.
+
+Request body must contain a list of 'alias'. The list of 'alias'
+is iterated. For each 'alias' the corresponding object is retrieved
+from the server repository.
+
+Handling of each individual object follows method `api_get`.
+
+The result is a `Vector` of objects. This result is written to
+JSON and returned via the response body.
+"""
+function api_bulk_get(
+    request::HTTP.Request,
+    repository::AbstractDict,
+    options::Options,
+    )
+    # we need to retrieve the list of alias from the request body
+    local json3_obj
+    try
+        json3_obj = JSON3.read(request.body)
+    catch e
+        return _error_create_json_fail(alias, e)
+    end
+    if !isa(json3_obj, AbstractVector)
+        return _error_bulk_list_not_found(json3_obj)
+    end
+    for alias in json3_obj
+        res = _check_for_alias_in_repository(alias, repository)
+        if isa(res, HTTP.Message)
+            return res
+        end
+    end
+    #
+    res = _check_for_header_field(request, "op")
+    if isa(res, HTTP.Message)
+        return res
+    end
+    op = uppercase(res)
+    if !(op in _OPERATIONS)
+        return _error_operation_not_implemented(op)
+    end
+    res_list = []
+    for alias in json3_obj
+        obj = repository[alias]
+        local out_obj
+        if op==_BUILD_OP
+            try
+                out_obj = DiffFusion.serialise(obj)
+            catch e
+                return _error_object_serialisation_fail(alias, e)
+            end
+        else
+            out_obj = obj
+        end
+        res_list = vcat(res_list, [out_obj])
+    end
+    #
+    local json3_string
+    try
+        json3_string = JSON3.write(res_list)
+    catch e
+        return _error_create_json_string_fail("[]", e)
+    end
+     # finally return objects...
+     return HTTP.Response(_NO_HTTP_ERROR, json3_string)
+end
+

src/server/Infos.jl

@@ -0,0 +1,27 @@
+
+"""
+    api_get_info(request::HTTP.Request)
+
+Return an info string about the API as response.
+"""
+function api_get_info(request::HTTP.Request)
+    return HTTP.Response(_NO_HTTP_ERROR, _INFO_STRING)
+end
+
+
+"""
+    api_get_aliases(
+        request::HTTP.Request,
+        repository::AbstractDict,
+        options::Options,
+        )
+
+Return all aliases from the repository in body of response.
+"""
+function api_get_aliases(
+    request::HTTP.Request,
+    repository::AbstractDict,
+    options::Options,
+    )
+    return HTTP.Response(_NO_HTTP_ERROR, JSON3.write(keys(repository)))
+end

src/server/Options.jl

@@ -0,0 +1,33 @@
+
+"""
+    mutable struct Options
+        is_busy::Bool
+    end
+
+A container that holds flags and data which control the behaviour of the router.
+
+The options object is created at inception of the router and passed to the
+various handler functions.
+
+`Options` element `is_busy` specifies that the server currently does not accept
+POST requests. The flag may be set via the *is_busy* header field in a POST
+request. The flag may be de-activated via the *is_busy* header field in
+(subsequent) GET request.
+"""
+mutable struct Options
+    is_busy::Bool
+end
+
+
+"""
+    initial_options(
+        is_busy::Bool = false,
+        )
+
+Create an `Options` object and initialise with default settings. 
+"""
+function initial_options(
+    is_busy::Bool = false,
+    )
+    return Options(is_busy)
+end