YAML Files¶
Models and communication between models during are specified by the user in one or more YAML files. YAML files have a human readable structure that can be parsed by many different programming languages to recreate data structures. While the YAML language can express very complex data structures (more information can be found here), only a few key concepts are needed to create a YAML file for use with the cis_interface framework.
- Indentation: Entries with the same indentation belong to the same collection.
- Sequences: Entries that begin with a dash and a space (- ) are members of a sequence collection. Members of a sequence can be text, collections, or a mix of both.
- Mappings: Mapping entries use a colon and a space (: ) to seperate a
key: value
pair. Keys are text and values can be text or a collection.
Model Options¶
At the root level of a cis_interface YAML, should be a mapping key model:
or models:
. This denotes information pertaining to the model(s) that should
be run. The value for this key can be a single model entry:
models:
name: modelA
driver: PythonModelDriver
args: ./src/gs_lesson4_modelA.py
or a sequence of model entries:
models:
- name: modelA
driver: PythonModelDriver
args: ./src/gs_lesson4_modelA.py
- name: modelB
driver: GCCModelDriver
args: ./src/gs_lesson4_modelB.c
At a minimum, each model entry should contain the following keys:
Key | Description |
---|---|
name | Unique name used to identify the model. This will be used to report errors associated with the model. |
driver | The name of the driver class that should be used to run the model. The list of available drivers can be found here. |
args | The full path to the file containing the model program that will be run by the driver or a list starting with the program file and including any arguments that should be passed as input to the program. |
inputs | A mapping object containing the entry for a model input channel or a list of input channel entries. If the model does not get input from another model, this may be ommitted. |
outputs | A mapping object containing the entry for a model output channel or a list of output channel entries. If the model does not output to another model, this may be ommitted. |
Models entries can also have the following optional keys:
Key | Description |
---|---|
is_server | If True , this model will be considered to function as a
server for one or more models. The corresponding channel that
should be passed to the cis_interface API will be the name of
the model. |
client_of | The names of one or more models that this model will call as a
server. If there are more than one, this should be specified as
a sequence collection. The corresponding channel(s) that should
be passed to the cis_interface API will be the name of the
server model joined with the name of the client model with an
underscore <server_model>_<client_model> . There will be one
channel created for each server the model is a client of. |
Any additional keys in the model entry will be passed to the model driver. A full description of the available model drivers and potential arguments can be found here.
Communication Options¶
There are two options for specifying communication channels for the models. One explicitly specifying the drivers and one specifying the connections between communication channels.
Driver Method¶
In specifying communication via drivers, each input/output entry for the models should be a mapping collection with, at minimum, the following keys:
Key | Description |
---|---|
name | The name of the channel that will be provided by the model to the cis_interface API. This can be any text, but should be unique. |
driver | The name of the input/output driver class that should be used. A list of available input/output drivers can be found here. |
args | For connections made to other models, this should be text that matches that of the other model’s corresponding driver. For connections made to files, this should be the path to the file, relative to the location of the YAML file. |
Any additional keys in the input/output entry will be passed to the input/output driver. A full description of the available input/output drivers and potential arguments can be found here.
Connection Method¶
To specify communication via connections, each input/output entry for the models need only contain a unique name for the communication channel. This can be specified as text:
input: channel_name
or a key, value mapping:
input:
name: channel_name
The key/value mapping form should be used when other information about the communication channel needs to be provided (e.g. message format, field names, units).
When using the connection format for specifying communication patterns, the
YAML also needs to contains a connections
key at the same level as the
models
key.
Connection Options¶
The coordesponding value for the connections
key should be one or more
mapping collections with the following keys:
Key | Description |
---|---|
input | The channel/file that messages should be recieved from. To specify
a model channel, this should be the name of an entry in a model’s
outputs section. If this is a file, it should be the absolute
path to the file or the relative path to the file from the directory
containing the YAML. |
output | The channel/file that messages recieved from the input
channel/file should be sent to. If the input value is a file,
the output value cannot be a file. To specify a model channel,
this should be the name of an entry in a model’s inputs section. |
Connection mappings can also have the following optional keys:
Key | Description | |
---|---|---|
format_str | A C-style format string specifying how messages should be formatted/parsed from/to language specifying types (see C-Style Format Strings). | |
field_names | A sequence collection of names for the fields present in the format string. | |
field_untis | A sequence collection of units for the fields present in the format string (see Units). | |
read_meth | Only valid for connections that direct messages from a file to a model input channel. Values indicate how messages should be read from the file and include: | |
Value | Description | |
all | The entire contents of the file are read as a single message. This is the default if not provided. | |
line | The contents of the file are read one line at a time. | |
table | The file is assumed to be an ASCII table and read one row at a time. The format of the table is either read from the header or inferred from the table. | |
table_array | The file is assumed to be an ASCII table and read in its entirety as an array. | |
write_meth | Only valid for connections that direct messages from a model output channel to a file. Values indicate how messages should written to the file and include: | |
Value | Description | |
all | The entire contents of the file are written at once. This is the default if not provided. | |
line | The contents of the file are written one line at a time. | |
table | The file is assumed to be an ASCII table and is written one row at a time. The format of the table must be specified by the model in its API call or as a value in the connection mapping. | |
table_array | The file is assumed to be an ASCII table and is written in its entirety as an array. |
The connection entries are used to determine which driver should be used to connect communication channels/files. Any additional keys in the connection entry will be passed to the input/output driver that is created for the connection. A full description of the available input/output drivers and potential arguments can be found here.