Common Workflow Language, Draft 2
7 July 2015
This version:
Current version:
Authors:
- Peter Amstutz
, Curoverse - Nebojša Tijanić
, Seven Bridges Genomics
Contributers:
- Luka Stojanovic
, Seven Bridges Genomics - John Chilton jmchilton@gmail.com, Galaxy Project, Pennsylvania State University
- Michael R. Crusoe mcrusoe@msu.edu, Michigan State University
- Hervé Ménager
, Institut Pasteur - Maxim Mikheev mikhmv@biodatomics.com, BioDatomics
- Stian Soiland-Reyes soiland-reyes@cs.manchester.ac.uk, University of Manchester
Abstract
A Workflow is an analysis task represented by a directed graph describing a sequence of operations that transform an input data set to output. This specification defines the Common Workflow Language (CWL), a vendor-neutral standard for representing workflows and concrete process steps intended to be portable across a variety of computing platforms.
Status of This Document
This document is the product of the Common Workflow Language working group. The latest version of this document is available in the "specification" directory at
https://github.com/common-workflow-language/common-workflow-language
The products of the CWL working group (including this document) are made available under the terms of the Apache License, version 2.0.
1. Introduction
The Common Workflow Language (CWL) working group is an informal, multi-vendor working group consisting of various organizations and individuals that have an interest in portability of data analysis workflows. The goal is to create specifications like this one that enable data scientists to describe analysis tools and workflows that are powerful, easy to use, portable, and support reproducibility.
1.1 Introduction to draft 2
This specification represents the second milestone of the CWL group. Since draft-1, this draft introduces a number of major changes and additions:
- Use of Avro schema (instead of JSON-schema) and JSON-LD for data modeling.
- Significant refactoring of the Command Line Tool description.
- Data and execution model for Workflows.
- Extension mechanism though "hints" and "requirements".
1.2 Purpose
CWL is designed to express workflows for data-intensive science, such as Bioinformatics, Chemistry, Physics, and Astronomy. This specification is intended to define a data and execution model for Workflows and Command Line Tools that can be implemented on top of a variety of computing platforms, ranging from an individual workstation to cluster, grid, cloud, and high performance computing systems.
1.3 References to Other Specifications
- JSON
- JSON-LD
- JSON Pointer
- YAML
- Avro
- Uniform Resource Identifier (URI): Generic Syntax
- UTF-8
- Portable Operating System Interface (POSIX.1-2008)
- Resource Description Framework (RDF)
1.4 Scope
This document describes the CWL syntax, execution, and object model. It is not intended to document a specific implementation of CWL, however it may serve as a reference for the behavior of conforming implementations.
1.5 Terminology
The terminology used to describe CWL documents is defined in the Concepts section of the specification. The terms defined in the following list are used in building those definitions and in describing the actions of an CWL implementation:
may: Conforming CWL documents and CWL implementations are permitted but not required to behave as described.
must: Conforming CWL documents and CWL implementations are required to behave as described; otherwise they are in error.
error: A violation of the rules of this specification; results are undefined. Conforming implementations may detect and report an error and may recover from it.
fatal error: A violation of the rules of this specification; results are undefined. Conforming implementations must not continue to execute the current process and may report an error.
at user option: Conforming software may or must (depending on the modal verb in the sentence) behave as described; if it does, it must provide users a means to enable or disable the behavior described.
2. Data model
2.1 Data concepts
An object is a data structure equivalent to the "object" type in JSON, consisting of a unordered set of name/value pairs (referred to here as fields) and where the name is a string and the value is a string, number, boolean, array, or object.
A document is a file containing a serialized object, or an array of objects.
A process is a basic unit of computation which accepts input data, performs some computation, and produces output data.
An input object is an object describing the inputs to a invocation of process.
An output object is an object describing the output of an invocation of a process.
An input schema describes the valid format (required fields, data types) for an input object.
An output schema describes the valid format for a output object.
Metadata is information about workflows, tools, or input items that is not used directly in the computation.
2.2 Syntax
Documents containing CWL objects are serialized and loaded using YAML syntax and UTF-8 text encoding. A conforming implementation must accept all valid YAML documents.
The CWL schema is defined using Avro Linked Data (avro-ld). Avro-ld is an extension of the Apache Avro schema language to support additional annotations mapping Avro fields to RDF predicates via JSON-LD.
A CWL document may be validated by transforming the avro-ld schema to a base Apache Avro schema.
An implementation may interpret a CWL document as JSON-LD and convert a CWL document to a Resource Description Framework (RDF) using the CWL JSON-LD Context (extracted from the avro-ld schema). The CWL RDFS schema defines the classes and properties used by CWL as JSON-LD.
The latest draft-2 schema is defined here: https://github.com/common-workflow-language/common-workflow-language/blob/master/schemas/draft-2/cwl-avro.yml
2.3 Identifiers
If an object contains an id
field, that is used to uniquely identify the
object in that document. The value of the id
field must be unique over the
entire document. The format of the id
field is that of a relative fragment
identifier, and must start
with a hash #
character.
An implementation may choose to only honor references to object types for
which the id
field is explicitly listed in this specification.
When loading a CWL document, an implementation may resolve relative identifiers to absolute URI references. For example, "my_tool.cwl" located in the directory "/home/example/work/" may be transformed to "file:///home/example/work/my_tool.cwl" and a relative fragment reference "#input" in this file may be transformed to "file:///home/example/work/my_tool.cwl#input".
2.4 Document preprocessing
An implementation must resolve import
directives. An import
directive
is an object consisting of the field import
specifying a URI. The URI
referenced by import
must be loaded as a CWL document (including
recursive preprocessing) and then the import
object is implicitly
replaced by the external resource. URIs may include document fragments
referring to objects identified by their id
field, in which case the import
directive is replaced by only the fragment object.
An implementation must resolve include
directives. An include
directive is an object consisting of the field include
specifying a URI.
The URI referenced by include
must be loaded as UTF-8 encoded text
document and the include
directive implicitly replaced by a string with
the contents of the document. Because the loaded resource is unparsed,
URIs used with include
must not include fragments.
2.5 Extensions and Metadata
Implementation extensions not required for correct execution (for example, fields related to GUI rendering) may be stored in process hints.
Input metadata (for example, a lab sample identifier) may be explicitly represented within a workflow using input parameters which are propagated to output. Future versions of this specification may define additional facilities for working with input/output metadata.
Fields for tool and workflow metadata (for example, authorship for use in citations) are not defined in this specification. Future versions of this specification may define such fields.
3. Execution model
3.1 Execution concepts
A parameter is a named symbolic input or output of process, with an associated datatype or schema. During execution, values are assigned to parameters to make the input object or output object used for concrete process invocation.
A command line tool is a process characterized by the execution of a standalone, non-interactive program which is invoked on some input, produces output, and then terminates.
A workflow is a process characterized by multiple subprocess steps, where step outputs are connected to the inputs of other downstream steps to form a directed graph, and independent steps may run concurrently.
A runtime environment is the actual hardware and software environment when executing a command line tool. It includes, but is not limited to, the hardware architecture, hardware resources, operating system, software runtime (if applicable, such as the Python interpreter or the JVM), libraries, modules, packages, utilities, and data files required to run the tool.
A workflow platform is a specific hardware and software implementation capable of interpreting a CWL document and executing the processes specified by the document. The responsibilities of the workflow platform may include scheduling process invocation, setting up the necessary runtime environment, making input data available, invoking the tool process, and collecting output.
It is intended that the workflow platform has broad leeway outside of this specification to optimize use of computing resources and enforce policies not covered by this specifcation. Some areas that are currently out of scope for CWL specification but may be handled by a specific workflow platform include:
- Data security and permissions.
- Scheduling tool invocations on remote cluster or cloud compute nodes.
- Using virtual machines or operating system containers to manage the runtime (except as described in DockerRequirement).
- Using remote or distributed file systems to manage input and output files.
- Translating or rewriting file paths.
- Determining if a process has previously been executed, skipping it and reusing previous results.
- Pausing and resuming of processes or workflows.
Conforming CWL processes must not assume anything about the runtime environment or workflow platform unless explicitly declared though the use of process requirements.
3.2 Generic execution process
The generic execution sequence of a CWL process (including both workflows and concrete process implementations) is as follows.
- Load and validate CWL document, yielding a process object.
- Load input object.
- Validate the input object against the
inputs
schema for the process. - Validate that process requirements are met.
- Perform any further setup required by the specific process type.
- Execute the process.
- Capture results of process execution into the output object.
- Validate the output object against the
outputs
schema for the process. - Report the output object to the process caller.
3.3 Requirements and hints
A process requirement modifies the semantics or runtime environment of a process. If an implementation cannot satisfy all requirements, or a requirement is listed which is not recognized by the implementation, it is a fatal error and the implementation must not attempt to run the process, unless overridden at user option.
A hint is similar to a requirement, however it is not an error if an implementation cannot satisfy all hints. The implementation may report a warning if a hint cannot be satisfied.
Requirements are inherited. A requirement specified in a Workflow applies to all workflow steps; a requirement specified on a workflow step will apply to the process implementation.
If the same process requirement appears at different levels of the
workflow, the most specific instance of the requirement is used, that is,
an entry in requirements
on a process implementation such as
CommandLineTool will take precendence over an entry in requirements
specified in a workflow step, and an entry in requirements
on a workflow
step takes precedence over the workflow. Entries in hints
are resolved
the same way.
Requirements override hints. If a process implementation provides a
process requirement in hints
which is also provided in requirements
by
an enclosing workflow or workflow step, the enclosing requirements
takes
precedence.
Process requirements are the primary mechanism for specifying extensions to the CWL core specification.
3.4 Expressions
An expression is a fragment of executable code which is evaluated by the workflow platform to affect the inputs, outputs, or behavior of a process. In the generic execution sequence, expressions may be evaluated during step 5 (process setup), step 6 (execute process), and/or step 7 (capture output). Expressions are distinct from regular processes in that they are intended to modify the behavior of the workflow itself rather than perform the primary work of the workflow.
An implementation must provide the predefined cwl:JsonPointer
expression
engine. This expression engine specifies a JSON
Pointer
into an expression input object consisting of the job
and context
fields described below.
An expression engine defined with ExpressionEngineRequirement is a command line program following the following protocol:
On standard input, receive a JSON object with the following fields:
engineConfig: A list of strings from the
engineConfig
field. Null ifengineConfig
is not specified.job: The input object of the current Process (context dependent).
context: The specific value being transformed (context dependent). May be null.
script: The code fragment to evaluate.
outdir: When used in the context of a CommandLineTool, this is the designated output directory that will be used when executing the tool. Null if not applicable.
tmpdir: When used in the context of a CommandLineTool, this is the designated temporary directory that will be used when executing the tool. Null if not applicable.
On standard output, print a single JSON value (string, number, array, object, boolean, or null) for the return value.
Expressions must be evaluated in an isolated context (a "sandbox") which permits no side effects to leak outside the context, and permit no outside data to leak into the context.
Implementations may apply limits, such as process isolation, timeouts, and operating system containers/jails to minimize the security risks associated with running untrusted code.
The order in which expressions are evaluated within a process or workflow is undefined.
3.5 Workflow graph
A workflow describes a set of steps and the dependencies between those processes. When a process produces output that will be consumed by a second process, the first process is a dependency of the second process. When there is a dependency, the workflow engine must execute the dependency process and wait for it to successfully produce output before executing the dependent process. If two processes are defined in the workflow graph that are not directly or indirectly dependent, these processes are independent, and may execute in any order or execute concurrently. A workflow is complete when all steps have been executed.
3.6 Success and failure
A completed process must result in one of success
, temporaryFailure
or
permanentFailure
states. An implementation may choose to retry a process
execution which resulted in temporaryFailure
. An implementation may
choose to either continue running other steps of a workflow, or terminate
immediately upon permanentFailure
.
If any step of a workflow execution results in
permanentFailure
, then the workflow status ispermanentFailure
.If one or more steps result in
temporaryFailure
and all other steps completesuccess
or are not executed, then the workflow status istemporaryFailure
.If all workflow steps are executed and complete with
success
, then the workflow status issuccess
.
3.7 Executing CWL documents as scripts
By convention, a CWL document may begin with #!/usr/bin/env cwl-runner
and be marked as executable (the POSIX "+x" permission bits) to enable it
to be executed directly. A workflow platform may support this mode of
operation; if so, it must provide cwl-runner
as an alias for the
platform's CWL implementation.
4. Sample CWL workflow
revtool.cwl:
#!/usr/bin/env cwl-runner
#
# Simplest example command line program wrapper for the Unix tool "rev".
#
class: CommandLineTool
description: "Reverse each line using the `rev` command"
# The "inputs" array defines the structure of the input object that describes
# the inputs to the underlying program. Here, there is one input field
# defined that will be called "input" and will contain a "File" object.
#
# The input binding indicates that the input value should be turned into a
# command line argument. In this example inputBinding is an empty object,
# which indicates that the file name should be added to the command line at
# a default location.
inputs:
- id: "#input"
type: File
inputBinding: {}
# The "outputs" array defines the structure of the output object that
# describes the outputs of the underlying program. Here, there is one
# output field defined that will be called "output", must be a "File" type,
# and after the program executes, the output value will be the file
# output.txt in the designated output directory.
outputs:
- id: "#output"
type: File
outputBinding:
glob: output.txt
# The actual program to execute.
baseCommand: rev
# Specify that the standard output stream must be redirected to a file called
# output.txt in the designated output directory.
stdout: output.txt
sorttool.cwl:
#!/usr/bin/env cwl-runner
#
# Example command line program wrapper for the Unix tool "sort"
# demonstrating command line flags.
class: CommandLineTool
description: "Sort lines using the `sort` command"
# This example is similar to the previous one, with an additional input
# parameter called "reverse". It is a boolean parameter, which is
# intepreted as a command line flag. The value of "prefix" is used for
# flag to put on the command line if "reverse" is true. If "reverse" is
# false, no flag is added.
#
# This example also introduced the "position" field. This indicates the
# sorting order of items on the command line. Lower numbers are placed
# before higher numbers. Here, the "--reverse" flag (if present) will be
# added to the command line before the input file path.
inputs:
- id: "#reverse"
type: boolean
inputBinding:
position: 1
prefix: "--reverse"
- id: "#input"
type: File
inputBinding:
position: 2
outputs:
- id: "#output"
type: File
outputBinding:
glob: output.txt
baseCommand: sort
stdout: output.txt
revsort.cwl:
#!/usr/bin/env cwl-runner
#
# This is a two-step workflow which uses "revtool" and "sorttool" defined above.
#
class: Workflow
description: "Reverse the lines in a document, then sort those lines."
# Requirements specify prerequisites and extensions to the workflow.
# In this example, DockerRequirement specifies a default Docker container
# in which the command line tools will execute.
requirements:
- class: DockerRequirement
dockerPull: debian:8
# The inputs array defines the structure of the input object that describes
# the inputs to the workflow.
#
# The "reverse_sort" input parameter demonstrates the "default" field. If the
# field "reverse_sort" is not provided in the input object, the default value will
# be used.
inputs:
- id: "#input"
type: File
description: "The input file to be processed."
- id: "#reverse_sort"
type: boolean
default: true
description: "If true, reverse (descending) sort"
# The "outputs" array defines the structure of the output object that describes
# the outputs of the workflow.
#
# Each output field must be connected to the output of one of the workflow
# steps using the "connect" field. Here, the parameter "#output" of the
# workflow comes from the "#sorted" output of the "sort" step.
outputs:
- id: "#output"
type: File
source: "#sorted.output"
description: "The output with the lines reversed and sorted."
# The "steps" array lists the executable steps that make up the workflow.
# The tool to execute each step is listed in the "run" field.
#
# In the first step, the "inputs" field of the step connects the upstream
# parameter "#input" of the workflow to the input parameter of the tool
# "revtool.cwl#input".
#
# In the second step, the "inputs" field of the step connects the output
# parameter "#reversed" from the first step to the input parameter of the
# tool "sorttool.cwl#input".
steps:
- inputs:
- { id: "#rev.input", source: "#input" }
outputs:
- { id: "#rev.output" }
run: { import: revtool.cwl }
- inputs:
- { id: "#sorted.input", source: "#rev.output" }
- { id: "#sorted.reverse", source: "#reverse_sort" }
outputs:
- { id: "#sorted.output" }
run: { import: sorttool.cwl }
Sample input object:
{
"input": {
"class": "File",
"path": "whale.txt"
}
}
Sample output object:
{
"output": {
"path": "/tmp/tmpdeI_p_/output.txt",
"size": 1111,
"class": "File",
"checksum": "sha1$b9214658cc453331b62c2282b772a5c063dbd284"
}
}
5. Reference
This section specifies the core object types that make up a CWL document.
5.1 Workflow
Extends Process
A workflow is a process consisting of one or more steps
. Each
step has input and output parameters defined by the inputs
and outputs
fields. A workflow executes as described in execution model.
Dependencies
Dependencies between parameters are expressed using the source
field on
workflow step input parameters and workflow output
parameters.
The source
field expresses the dependency of one parameter on another
such that when a value is associated with the parameter specified by
source
, that value is propagated to the destination parameter. When all
data links inbound to a given step are fufilled, the step is ready to
execute.
Extensions
ScatterFeatureRequirement and SubworkflowFeatureRequirement are available as standard extensions to core workflow semantics.
Fields
field | type | required | description |
---|---|---|---|
id | string | False | The unique identifier for this process object. Inherited from Process |
inputs | array<InputParameter> | True | Defines the input parameters of the process. The process is ready to run when all required input parameters are associated with concrete values. Input parameters include a schema for each parameter which is used to validate the input object. It may also be used build a user interface for constructing the input object. Inherited from Process |
outputs | array<WorkflowOutputParameter> | True | Defines the parameters representing the output of the process. May be used to generate and/or validate the output object. Inherited from Process |
requirements | array<DockerRequirement | SubworkflowFeatureRequirement | CreateFileRequirement | EnvVarRequirement | ScatterFeatureRequirement | SchemaDefRequirement | ExpressionEngineRequirement> | False | Declares requirements that apply to either the runtime environment or the workflow engine that must be met in order to execute this process. If an implementation cannot satisfy all requirements, or a requirement is listed which is not recognized by the implementation, it is a fatal error and the implementation must not attempt to run the process, unless overridden at user option. Inherited from Process |
hints | array<Any> | False | Declares hints applying to either the runtime environment or the workflow engine that may be helpful in executing this process. It is not an error if an implementation cannot satisfy all hints, however the implementation may report a warning. Inherited from Process |
label | string | False | A short, human-readable label of this process object. Inherited from Process |
description | string | False | A long, human-readable description of this process object. Inherited from Process |
class | Workflow_class | True | Must be |
steps | array<WorkflowStep> | True | The individual steps that make up the workflow. Each step is executed when all of its input data links are fufilled. An implementation may choose to execute the steps in a different order than listed and/or execute steps concurrently, provided that dependencies between steps are met. |
5.1.1 WorkflowOutputParameter
Extends OutputParameter
Referenced by Workflow.outputs
Describe an output parameter of a workflow. The parameter must be connected to one or more parameters defined in the workflow that will provide the value of the output parameter.
Fields
field | type | required | description |
---|---|---|---|
type | Datatype | OutputSchema | string | array<Datatype | OutputSchema | string> | False | Specify valid types of data that may be assigned to this parameter. Inherited from Parameter |
label | string | False | A short, human-readable label of this parameter object. Inherited from Parameter |
description | string | False | A long, human-readable description of this parameter object. Inherited from Parameter |
streamable | boolean | False | Currently only applies if |
default | Any | False | The default value for this parameter if not provided in the input object. Inherited from Parameter |
id | string | True | The unique identifier for this parameter object. Inherited from OutputParameter |
source | string | array<string> | False | Specifies one or more workflow parameters that will provide this output value. |
linkMerge | LinkMergeMethod | False | The method to use to merge multiple inbound links into a single array. If not specified, the default method is "merge_nested". |
5.1.2 WorkflowStep
Referenced by Workflow.steps
A workflow step is an executable element of a workflow. It specifies the
underlying process implementation (such as CommandLineTool
) in the run
field and connects the input and output parameters of the underlying
process to workflow parameters.
Scatter/gather
To use scatter/gather, ScatterFeatureRequirement must be specified in the workflow or workflow step requirements.
A "scatter" operation specifies that the associated workflow step or subworkflow should execute separately over a list of input elements. Each job making up a scatter operaution is independent and may be executed concurrently.
The scatter
field specifies one or more input parameters which will be
scattered. An input parameter may be listed more than once. The declared
type of each input parameter is implicitly wrapped in an array for each
time it appears in the scatter
field. As a result, upstream parameters
which are connected to scattered parameters may be arrays.
All output parameter types are also implicitly wrapped in arrays. Each job in the scatter results in an entry in the output array.
If scatter
declares more than one input parameter, scatterMethod
describes how to decompose the input into a discrete set of jobs.
dotproduct specifies that each of the input arrays are aligned and one element taken from each array to construct each job. It is an error if all input arrays are not the same length.
nested_crossproduct specifies the Cartesian product of the inputs, producing a job for every combination of the scattered inputs. The output must be nested arrays for each level of scattering, in the order that the input arrays are listed in the
scatter
field.flat_crossproduct specifies the Cartesian product of the inputs, producing a job for every combination of the scattered inputs. The output arrays must be flattened to a single level, but otherwise listed in the order that the input arrays are listed in the
scatter
field.
Subworkflows
To specify a nested workflow as part of a workflow step, SubworkflowFeatureRequirement must be specified in the workflow or workflow step requirements.
Fields
field | type | required | description |
---|---|---|---|
id | string | False | The unique identifier for this workflow step. |
inputs | array<WorkflowStepInput> | True | Defines the input parameters of the workflow step. The process is ready to run when all required input parameters are associated with concrete values. Input parameters include a schema for each parameter which is used to validate the input object. It may also be used build a user interface for constructing the input object. |
outputs | array<WorkflowStepOutput> | True | Defines the parameters representing the output of the process. May be used to generate and/or validate the output object. |
requirements | array<DockerRequirement | SubworkflowFeatureRequirement | CreateFileRequirement | EnvVarRequirement | ScatterFeatureRequirement | SchemaDefRequirement | ExpressionEngineRequirement> | False | Declares requirements that apply to either the runtime environment or the workflow engine that must be met in order to execute this workflow step. If an implementation cannot satisfy all requirements, or a requirement is listed which is not recognized by the implementation, it is a fatal error and the implementation must not attempt to run the process, unless overridden at user option. |
hints | array<Any> | False | Declares hints applying to either the runtime environment or the workflow engine that may be helpful in executing this workflow step. It is not an error if an implementation cannot satisfy all hints, however the implementation may report a warning. |
label | string | False | A short, human-readable label of this process object. |
description | string | False | A long, human-readable description of this process object. |
run | CommandLineTool | ExpressionTool | Workflow | True | Specifies the process to run. |
scatter | string | array<string> | False | |
scatterMethod | ScatterMethod | False | Required if |
5.1.2.1 WorkflowStepInput
Referenced by WorkflowStep.inputs
The input of a workflow step connects an upstream parameter (from the workflow inputs, or the outputs of other workflows steps) with the input parameters of the underlying process.
Input object
A WorkflowStepInput object must contain an id
field in the form
#fieldname
or #stepname.fieldname
. When the id
field contains a
period .
the field name consists of the characters following the final
period. This defines a field of the workflow step input object with the
value of the source
parameter(s).
Merging
If the sink parameter is an array, or named in a workflow
scatter operation, there may be multiple inbound data links
listed in the connect
field. The values from the input links are merged
depending on the method specified in the linkMerge
field. If not
specified, the default method is "merge_nested".
merge_nested
The input must be an array consisting of exactly one entry for each input link. If "merge_nested" is specified with a single link, the value from the link must be wrapped in a single-item list.
merge_flattened
- The source and sink parameters must be compatible types, or the source type must be compatible with single element from the "items" type of the destination array parameter.
- Source parameters which are arrays are concatenated. Source parameters which are single element types are appended as single elements.
Fields
field | type | required | description |
---|---|---|---|
id | string | True | A unique identifier for this workflow input parameter. |
source | string | array<string> | False | Specifies one or more workflow parameters that will provide input to the underlying process parameter. |
linkMerge | LinkMergeMethod | False | The method to use to merge multiple inbound links into a single array. If not specified, the default method is "merge_nested". |
default | Any | False | The default value for this parameter if there is no |
5.1.2.1.1 LinkMergeMethod
Referenced by WorkflowOutputParameter.linkMerge, WorkflowStepInput.linkMerge
The input link merge method, described in WorkflowStepInput.
5.1.2.2 WorkflowStepOutput
Referenced by WorkflowStep.outputs
Associate an output parameter of the underlying process with a workflow
parameter. The workflow parameter (given in the id
field) be may be used
as a source
to connect with input parameters of other workflow steps, or
with an output parameter of the process.
Fields
field | type | required | description |
---|---|---|---|
id | string | True | A unique identifier for this workflow output parameter. This is the
identifier to use in the |
5.1.2.3 ScatterMethod
Referenced by WorkflowStep.scatterMethod
The scatter method, as described in workflow step scatter.
5.2 CommandLineTool
Extends Process
A CommandLineTool process is a process implementation for executing a non-interactive application in a POSIX environment. To accommodate the enormous variety in syntax and semantics for input, runtime environment, invocation, and output of arbitrary programs, CommandLineTool uses an "input binding" that describes how to translate input parameters to an actual program invocation, and an "output binding" that describes how to generate output parameters from program output.
Input binding
The tool command line is built by applying command line bindings to the
input object. Bindings are listed either as part of an input
parameter using the inputBinding
field, or
separately using the arguments
field of the CommandLineTool.
The algorithm to build the command line is as follows. In this algorithm, the sort key is a list consisting of one or more numeric or string elements. Strings are sorted lexicographically based on UTF-8 encoding.
Collect
CommandLineBinding
objects fromarguments
. Assign a sorting key[position, i]
whereposition
isCommandLineBinding.position
andi
is the index in thearguments
list.Collect
CommandLineBinding
objects from theinputs
schema and associate them with values from the input object. Where the input type is a record, array, or map, recursively walk the schema and input object, collecting nestedCommandLineBinding
objects and associating them with values from the input object.Create a sorting key by taking the value of the
position
field at each level leading to each leaf binding object. Ifposition
is not specified, it is not added to the sorting key. For bindings on arrays and maps, the sorting key must include the array index or map key following the position. If and only if two bindings have the same sort key, the tie must be broken using the ordering of the field or parameter name immediately containing the leaf binding.Sort elements using the assigned sorting keys. Numeric entries sort before strings.
In the sorted order, apply the rules defined in
CommandLineBinding
to convert bindings to actual command line elements.Insert elements from
baseCommand
at the beginning of the command line.
Runtime environment
All files listed in the input object must be made available in the runtime environment. The implementation may use a shared or distributed file system or transfer files via explicit download. Implementations may choose not to provide access to files not explicitly specified by the input object or process requirements.
Output files produced by tool execution must be written to the designated output directory.
The initial current working directory when executing the tool must be the designated output directory.
When executing the tool, the child process must not inherit environment
variables from the parent process. The tool must execute in a new, empty
environment, containing only environment variables defined by
EnvVarRequirement, the default environment of the
Docker container specified in DockerRequirement (if
applicable), and TMPDIR
.
The TMPDIR
environment variable must be set in the runtime environment to
the designated temporary directory. Any files written to the
designated temporary directory may be deleted by the workflow platform when
the tool invocation is complete.
An implementation may forbid the tool from writing to any location in the runtime environment file system other than the designated temporary directory and designated output directory. An implementation may provide read-only input files, and disallow in-place update of input files.
The standard input stream and standard output stream may be redirected as
described in the stdin
and stdout
fields.
Extensions
DockerRequirement, CreateFileRequirement, and EnvVarRequirement are available as standard extensions to core command line tool semantics for defining the runtime environment.
Execution
Once the command line is built and the runtime environment is created, the actual tool is executed.
The standard error stream and standard output stream (unless redirected by
setting stdout
) may be captured by platform logging facilities for
storage and reporting.
Tools may be multithreaded or spawn child processes; however, when the parent process exits, the tool is considered finished regardless of whether any detached child processes are still running. Tools must not require any kind of console, GUI, or web based user interaction in order to start and run to completion.
The exit code of the process indicates if the process completed
successfully. By convention, an exit code of zero is treated as success
and non-zero exit codes are treated as failure. This may be customized by
providing the fields successCodes
, temporaryFailCodes
, and
permanentFailCodes
. An implementation may choose to default unspecified
non-zero exit codes to either temporaryFailure
or permanentFailure
.
Output binding
If the output directory contains a file named "cwl.output.json", that file
must be loaded and used as the output object. Otherwise, the output object
must be generated by walking the parameters listed in outputs
and
applying output bindings to the tool output. Output bindings are
associated with output parameters using the outputBinding
field. See
CommandOutputBinding
for details.
Fields
field | type | required | description |
---|---|---|---|
id | string | False | The unique identifier for this process object. Inherited from Process |
inputs | array<CommandInputParameter> | True | Defines the input parameters of the process. The process is ready to run when all required input parameters are associated with concrete values. Input parameters include a schema for each parameter which is used to validate the input object. It may also be used build a user interface for constructing the input object. Inherited from Process |
outputs | array<CommandOutputParameter> | True | Defines the parameters representing the output of the process. May be used to generate and/or validate the output object. Inherited from Process |
requirements | array<DockerRequirement | SubworkflowFeatureRequirement | CreateFileRequirement | EnvVarRequirement | ScatterFeatureRequirement | SchemaDefRequirement | ExpressionEngineRequirement> | False | Declares requirements that apply to either the runtime environment or the workflow engine that must be met in order to execute this process. If an implementation cannot satisfy all requirements, or a requirement is listed which is not recognized by the implementation, it is a fatal error and the implementation must not attempt to run the process, unless overridden at user option. Inherited from Process |
hints | array<Any> | False | Declares hints applying to either the runtime environment or the workflow engine that may be helpful in executing this process. It is not an error if an implementation cannot satisfy all hints, however the implementation may report a warning. Inherited from Process |
label | string | False | A short, human-readable label of this process object. Inherited from Process |
description | string | False | A long, human-readable description of this process object. Inherited from Process |
class | CommandLineTool_class | True | Must be |
baseCommand | string | array<string> | True | Specifies the program to execute. If the value is an array, the first
element is the program to execute, and subsequent elements are placed
at the beginning of the command line in prior to any command line
bindings. If the program includes a path separator character it must
be an absolute path, otherwise it is an error. If the program does not
include a path separator, search the |
arguments | array<string | CommandLineBinding> | False | Command line bindings which are not directly associated with input parameters. |
stdin | string | Expression | False | A path to a file whose contents must be piped into the command's standard input stream. |
stdout | string | Expression | False | Capture the command's standard output stream to a file written to the designated output directory. If If |
successCodes | array<int> | False | Exit codes that indicate the process completed successfully. |
temporaryFailCodes | array<int> | False | Exit codes that indicate the process failed due to a possibly temporary condition, where excuting the process with the same runtime environment and inputs may produce different results. |
permanentFailCodes | array<int> | False | Exit codes that indicate the process failed due to a permanent logic error, where excuting the process with the same runtime environment and same inputs is expected to always fail. |
5.2.1 CommandInputParameter
Extends InputParameter
Referenced by CommandLineTool.inputs
An input parameter for a CommandLineTool.
Fields
field | type | required | description |
---|---|---|---|
type | Datatype | CommandInputSchema | string | array<Datatype | CommandInputSchema | string> | False | Specify valid types of data that may be assigned to this parameter. Inherited from Parameter |
label | string | False | A short, human-readable label of this parameter object. Inherited from Parameter |
description | string | False | A long, human-readable description of this parameter object. Inherited from Parameter |
streamable | boolean | False | Currently only applies if |
default | Any | False | The default value for this parameter if not provided in the input object. Inherited from Parameter |
id | string | True | The unique identifier for this parameter object. Inherited from InputParameter |
inputBinding | CommandLineBinding | False | Describes how to handle the inputs of a process and convert them into a concrete form for execution, such as command line parameters. Inherited from InputParameter |
5.2.1.1 CommandLineBinding
Extends Binding
Referenced by CommandInputSchema.inputBinding, CommandInputParameter.inputBinding, CommandLineTool.arguments
When listed under inputBinding
in the input schema, the term
"value" refers to the the corresponding value in the input object. For
binding objects listed in CommandLineTool.arguments
, the term "value"
refers to the effective value after evaluating valueFrom
.
The binding behavior when building the command line depends on the data type of the value. If there is a mismatch between the type described by the input schema and the effective value, such as resulting from an expression evaluation, an implementation must use the data type of the effective value.
string: Add
prefix
and the string to the command line.number: Add
prefix
and decimal representation to command line.boolean: If true, add
prefix
to the command line. If false, add nothing.File: Add
prefix
and the value ofFile.path
to the command line.array: If
itemSeparator
is specified, addprefix
and the join the array into a single string withitemSeparator
separating the items. Otherwise first addprefix
, then recursively process individual elements.object: Add
prefix
only, and recursively add object fields for whichinputBinding
is specified.null: Add nothing.
Fields
field | type | required | description |
---|---|---|---|
loadContents | boolean | False | Only applies when |
secondaryFiles | string | Expression | array<string | Expression> | False | Only applies when If the value is an expression, the context of the expression is the input or output File parameter to which this binding applies. If the value is a string, it specifies that the following pattern should be applied to the primary file:
|
position | int | False | The sorting key. Default position is 0. |
prefix | string | False | Command line prefix to add before the value. |
separate | boolean | False | If true (default), then the prefix and value must be added as separate command line arguments; if false, prefix and value must be concatenated into a single command line argument. |
itemSeparator | string | False | Join the array elements into a single string with the elements
separated by by |
valueFrom | string | Expression | False | If If When a binding is part of the |
5.2.1.2 CommandInputSchema
Extends InputSchema
Referenced by CommandInputSchema.type, CommandInputSchema.fields, CommandInputSchema.items, CommandInputSchema.values, CommandInputParameter.type
Fields
field | type | required | description |
---|---|---|---|
type | Datatype | CommandInputSchema | string | array<Datatype | CommandInputSchema | string> | True | The data type of this parameter. Inherited from Schema |
fields | array<CommandInputSchema> | False | When |
symbols | array<string> | False | When |
items | Datatype | CommandInputSchema | string | array<Datatype | CommandInputSchema | string> | False | When |
values | Datatype | CommandInputSchema | string | array<Datatype | CommandInputSchema | string> | False | When |
inputBinding | CommandLineBinding | False | Describes how to handle a value in the input object convert it into a concrete form for execution, such as command line parameters. Inherited from InputSchema |
5.2.2 CommandOutputParameter
Extends OutputParameter
Referenced by CommandLineTool.outputs
An output parameter for a CommandLineTool.
Fields
field | type | required | description |
---|---|---|---|
type | Datatype | CommandOutputSchema | string | array<Datatype | CommandOutputSchema | string> | False | Specify valid types of data that may be assigned to this parameter. Inherited from Parameter |
label | string | False | A short, human-readable label of this parameter object. Inherited from Parameter |
description | string | False | A long, human-readable description of this parameter object. Inherited from Parameter |
streamable | boolean | False | Currently only applies if |
default | Any | False | The default value for this parameter if not provided in the input object. Inherited from Parameter |
id | string | True | The unique identifier for this parameter object. Inherited from OutputParameter |
outputBinding | CommandOutputBinding | False | Describes how to handle the concrete outputs of a process step (such as files created by a program) and describe them in the process output parameter. |
5.2.2.1 CommandOutputBinding
Extends Binding
Referenced by CommandOutputSchema.outputBinding, CommandOutputParameter.outputBinding
Describes how to generate an output parameter based on the files produced by a CommandLineTool.
The output parameter is generated by applying these operations in the following order:
- glob
- loadContents
- outputEval
Fields
field | type | required | description |
---|---|---|---|
loadContents | boolean | False | Only applies when |
secondaryFiles | string | Expression | array<string | Expression> | False | Only applies when If the value is an expression, the context of the expression is the input or output File parameter to which this binding applies. If the value is a string, it specifies that the following pattern should be applied to the primary file:
|
glob | string | Expression | array<string> | False | Find files relative to the output directory, using POSIX glob(3) pathname matching. If provided an array, find files that match any pattern in the array. If provided an expression, the expression must return a string or an array of strings, which will then be evaluated as one or more glob patterns. Only files which actually exist will be matched and returned. |
outputEval | Expression | False | Evaluate an expression to generate the output value. If |
5.2.2.2 CommandOutputSchema
Extends OutputSchema
Referenced by CommandOutputSchema.type, CommandOutputSchema.fields, CommandOutputSchema.items, CommandOutputSchema.values, CommandOutputParameter.type
Fields
field | type | required | description |
---|---|---|---|
type | Datatype | CommandOutputSchema | string | array<Datatype | CommandOutputSchema | string> | True | The data type of this parameter. Inherited from Schema |
fields | array<CommandOutputSchema> | False | When |
symbols | array<string> | False | When |
items | Datatype | CommandOutputSchema | string | array<Datatype | CommandOutputSchema | string> | False | When |
values | Datatype | CommandOutputSchema | string | array<Datatype | CommandOutputSchema | string> | False | When |
outputBinding | CommandOutputBinding | False | Describes how to handle the concrete outputs of a process step (such as files created by a program) and describe them in the process output parameter. |
5.3 ExpressionTool
Extends Process
Execute an expression as a process step.
Fields
field | type | required | description |
---|---|---|---|
id | string | False | The unique identifier for this process object. Inherited from Process |
inputs | array<InputParameter> | True | Defines the input parameters of the process. The process is ready to run when all required input parameters are associated with concrete values. Input parameters include a schema for each parameter which is used to validate the input object. It may also be used build a user interface for constructing the input object. Inherited from Process |
outputs | array<OutputParameter> | True | Defines the parameters representing the output of the process. May be used to generate and/or validate the output object. Inherited from Process |
requirements | array<DockerRequirement | SubworkflowFeatureRequirement | CreateFileRequirement | EnvVarRequirement | ScatterFeatureRequirement | SchemaDefRequirement | ExpressionEngineRequirement> | False | Declares requirements that apply to either the runtime environment or the workflow engine that must be met in order to execute this process. If an implementation cannot satisfy all requirements, or a requirement is listed which is not recognized by the implementation, it is a fatal error and the implementation must not attempt to run the process, unless overridden at user option. Inherited from Process |
hints | array<Any> | False | Declares hints applying to either the runtime environment or the workflow engine that may be helpful in executing this process. It is not an error if an implementation cannot satisfy all hints, however the implementation may report a warning. Inherited from Process |
label | string | False | A short, human-readable label of this process object. Inherited from Process |
description | string | False | A long, human-readable description of this process object. Inherited from Process |
class | ExpressionTool_class | True | Must be |
expression | Expression | True | The expression to execute. The expression must return a JSON object which matches the output parameters of the ExpressionTool. |
5.4 Expression
Referenced by Binding.secondaryFiles, FileDef.filename, FileDef.fileContent, EnvironmentDef.envValue, CommandLineBinding.secondaryFiles, CommandLineBinding.valueFrom, CommandOutputBinding.secondaryFiles, CommandOutputBinding.glob, CommandOutputBinding.outputEval, CommandLineTool.stdin, CommandLineTool.stdout, ExpressionTool.expression
Define an expression that will be evaluated and used to modify the behavior of a tool or workflow. See Expressions for more information about expressions and ExpressionEngineRequirement for information on how to define a expression engine.
Fields
field | type | required | description |
---|---|---|---|
engine | JsonPointer | string | True | Either |
script | string | True | The code to be executed by the expression engine. |
5.4.1 JsonPointer
Referenced by Expression.engine
5.5 ProcessRequirement
Extended by DockerRequirement, SubworkflowFeatureRequirement, CreateFileRequirement, EnvVarRequirement, ScatterFeatureRequirement, SchemaDefRequirement, ExpressionEngineRequirement
A process requirement declares a prerequisite that may or must be fulfilled
before executing a process. See Process.hints
and
Process.requirements
.
Process requirements are the primary mechanism for specifying extensions to the CWL core specification.
Fields
field | type | required | description |
---|---|---|---|
class | string | True | The specific requirement type. |
5.5.1 DockerRequirement
Extends ProcessRequirement
Indicates that a workflow component should be run in a Docker container, and specifies how to fetch or build the image.
If a CommandLineTool lists DockerRequirement
under
hints
or requirements
, it may (or must) be run in the specified Docker
container.
The platform must first acquire or install the correct Docker image as
specified by dockerPull
, dockerLoad
or dockerFile
.
The platform must execute the tool in the container using docker run
with
the appropriate Docker image and tool command line.
The workflow platform may provide input files and the designated output directory through the use of volume bind mounts. The platform may rewrite file paths in the input object to correspond to the Docker bind mounted locations.
When running a tool contained in Docker, the workflow platform must not assume anything about the contents of the Docker container, such as the presence or absence of specific software, except to assume that the generated command line represents a valid command within the runtime environment of the container.
Interaction with other requirements
If EnvVarRequirement is specified alongside a
DockerRequirement, the environment variables must be provided to Docker
using --env
or --env-file
and interact with the container's preexisting
environment as defined by Docker.
Fields
field | type | required | description |
---|---|---|---|
class | DockerRequirement_class | True | Must be |
dockerPull | string | False | Specify a Docker image to retrieve using |
dockerLoad | string | False | Specify a HTTP URL from which to download a Docker image using |
dockerFile | string | False | Supply the contents of a Dockerfile which will be built using |
dockerImageId | string | False | The image id that will be used for |
dockerOutputDirectory | string | False | Set the designated output directory to a specific location inside the Docker container. |
5.5.2 SubworkflowFeatureRequirement
Extends ProcessRequirement
Indicates that the workflow platform must support nested workflows in
the run
field of (WorkflowStep)(#workflowstep).
Fields
field | type | required | description |
---|---|---|---|
class | SubworkflowFeatureRequirement_class | True | Must be |
5.5.3 CreateFileRequirement
Extends ProcessRequirement
Define a list of files that must be created by the workflow
platform in the designated output directory prior to executing the command
line tool. See FileDef
for details.
Fields
field | type | required | description |
---|---|---|---|
class | CreateFileRequirement_class | True | Must be |
fileDef | array<FileDef> | True | The list of files. |
5.5.3.1 FileDef
Referenced by CreateFileRequirement.fileDef
Define a file that must be placed in the designated output directory prior to executing the command line tool. May be the result of executing an expression, such as building a configuration file from a template.
Fields
field | type | required | description |
---|---|---|---|
filename | string | Expression | True | The name of the file to create in the output directory. |
fileContent | string | Expression | True | If the value is a string literal or an expression which evaluates to a string, a new file must be created with the string as the file contents. If the value is an expression that evaluates to a File object, this indicates the referenced file should be added to the designated output directory prior to executing the tool. Files added in this way may be read-only, and may be provided by bind mounts or file system links to avoid unnecessary copying of the input file. |
5.5.4 EnvVarRequirement
Extends ProcessRequirement
Define a list of environment variables which will be set in the
execution environment of the tool. See EnvironmentDef
for details.
Fields
field | type | required | description |
---|---|---|---|
class | EnvVarRequirement_class | True | Must be |
envDef | array<EnvironmentDef> | True | The list of environment variables. |
5.5.4.1 EnvironmentDef
Referenced by EnvVarRequirement.envDef
Define an environment variable that will be set in the runtime environment by the workflow platform when executing the command line tool. May be the result of executing an expression, such as getting a parameter from input.
Fields
field | type | required | description |
---|---|---|---|
envName | string | True | The environment variable name |
envValue | string | Expression | True | The environment variable value |
5.5.5 ScatterFeatureRequirement
Extends ProcessRequirement
Indicates that the workflow platform must support the scatter
and
scatterMethod
fields of WorkflowStep.
Fields
field | type | required | description |
---|---|---|---|
class | ScatterFeatureRequirement_class | True | Must be |
5.5.6 SchemaDefRequirement
Extends ProcessRequirement
This field consists of an
array of type definitions which must be used when interpreting the inputs
and
outputs
fields. When a symbolic type is encountered that is not in
Datatype
, the implementation must check if
the type is defined in schemaDefs
and use that definition. If the type is not
found in schemaDefs
, it is an error. The entries in schemaDefs
must be
processed in the order listed such that later schema definitions may refer to
earlier schema definitions.
Fields
field | type | required | description |
---|---|---|---|
class | SchemaDefRequirement_class | True | Must be |
types | array<SchemaDef> | True | The list of type definitions. |
5.5.6.1 SchemaDef
Extends Schema
Referenced by SchemaDefRequirement.types
Fields
field | type | required | description |
---|---|---|---|
type | Datatype | Schema | string | array<Datatype | Schema | string> | True | The data type of this parameter. Inherited from Schema |
fields | array<Schema> | False | When |
symbols | array<string> | False | When |
items | Datatype | Schema | string | array<Datatype | Schema | string> | False | When |
values | Datatype | Schema | string | array<Datatype | Schema | string> | False | When |
name | string | True | The type name being defined. |
5.5.7 ExpressionEngineRequirement
Extends ProcessRequirement
Define an expression engine, as described in Expressions.
Fields
field | type | required | description |
---|---|---|---|
class | ExpressionEngineRequirement_class | True | Must be |
id | string | True | Used to identify the expression engine in the |
requirements | array<DockerRequirement | SubworkflowFeatureRequirement | CreateFileRequirement | EnvVarRequirement | ScatterFeatureRequirement | SchemaDefRequirement | ExpressionEngineRequirement> | False | Requirements to run this expression engine, such as DockerRequirement for specifying a container to run the engine. |
engineCommand | string | array<string> | False | The command line to invoke the expression engine. |
engineConfig | array<string> | False | Additional configuration or code fragments that will also be passed to the expression engine. The semantics of this field are defined by the underlying expression engine. Intended for uses such as providing function definitions that will be called from CWL expressions. |
5.6 Datatype
Referenced by Schema.type, Schema.items, Schema.values, Parameter.type, InputSchema.type, InputSchema.items, InputSchema.values, OutputSchema.type, OutputSchema.items, OutputSchema.values, InputParameter.type, OutputParameter.type, SchemaDef.type, SchemaDef.items, SchemaDef.values, CommandInputSchema.type, CommandInputSchema.items, CommandInputSchema.values, CommandOutputSchema.type, CommandOutputSchema.items, CommandOutputSchema.values, CommandInputParameter.type, CommandOutputParameter.type, WorkflowOutputParameter.type
CWL data types are based on Avro schema declarations. Refer to the Avro
schema declaration
documentation for
detailed information. In addition, CWL defines File
as a special record type.
Primitive types
- null: no value
- boolean: a binary value
- int: 32-bit signed integer
- long: 64-bit signed integer
- float: single precision (32-bit) IEEE 754 floating-point number
- double: double precision (64-bit) IEEE 754 floating-point number
- bytes: sequence of uninterpreted 8-bit unsigned bytes
- string: Unicode character sequence
Complex types
- record: An object with one or more fields defined by name and type
- enum: A value from a finite set of symbolic values
- array: An ordered sequence of values
- map: An unordered collection of key/value pairs
File type
See File below.
Any type
See Any below.
5.6.1 File
Referenced by File.secondaryFiles
Represents a file (or group of files if secondaryFiles
is specified) that
must be accessible by tools using standard POSIX file system call API such as
open(2) and read(2).
Fields
field | type | required | description |
---|---|---|---|
class | File_class | True | Must be |
path | string | True | The path to the file. |
checksum | string | False | Optional hash code for validating file integrity. Currently must be in the form "sha1$ + hexidecimal string" using the SHA-1 algorithm. |
size | long | False | Optional file size. |
secondaryFiles | array<File> | False | A list of additional files that are associated with the primary file
and must be transferred alongside the primary file. Examples include
indexes of the primary file, or external references which must be
included when loading primary document. A file object listed in
|
5.6.2 Any
Referenced by Parameter.default, InputParameter.default, OutputParameter.default, Process.hints, CommandInputParameter.default, CommandOutputParameter.default, CommandLineTool.hints, ExpressionTool.hints, WorkflowOutputParameter.default, WorkflowStepInput.default, WorkflowStep.hints, Workflow.hints
The Any type validates for any non-null value.
5.7 Process
Extended by CommandLineTool, ExpressionTool, Workflow
The base executable type in CWL is the Process
object defined by the
document. Note that the Process
object is abstract and cannot be
directly executed.
Fields
field | type | required | description |
---|---|---|---|
id | string | False | The unique identifier for this process object. |
inputs | array<InputParameter> | True | Defines the input parameters of the process. The process is ready to run when all required input parameters are associated with concrete values. Input parameters include a schema for each parameter which is used to validate the input object. It may also be used build a user interface for constructing the input object. |
outputs | array<OutputParameter> | True | Defines the parameters representing the output of the process. May be used to generate and/or validate the output object. |
requirements | array<DockerRequirement | SubworkflowFeatureRequirement | CreateFileRequirement | EnvVarRequirement | ScatterFeatureRequirement | SchemaDefRequirement | ExpressionEngineRequirement> | False | Declares requirements that apply to either the runtime environment or the workflow engine that must be met in order to execute this process. If an implementation cannot satisfy all requirements, or a requirement is listed which is not recognized by the implementation, it is a fatal error and the implementation must not attempt to run the process, unless overridden at user option. |
hints | array<Any> | False | Declares hints applying to either the runtime environment or the workflow engine that may be helpful in executing this process. It is not an error if an implementation cannot satisfy all hints, however the implementation may report a warning. |
label | string | False | A short, human-readable label of this process object. |
description | string | False | A long, human-readable description of this process object. |
5.7.1 Parameter
Extended by InputParameter, OutputParameter
Define an input or output parameter to a process.
Fields
field | type | required | description |
---|---|---|---|
type | Datatype | Schema | string | array<Datatype | Schema | string> | False | Specify valid types of data that may be assigned to this parameter. |
label | string | False | A short, human-readable label of this parameter object. |
description | string | False | A long, human-readable description of this parameter object. |
streamable | boolean | False | Currently only applies if |
default | Any | False | The default value for this parameter if not provided in the input object. |
5.7.1.1 Schema
Extended by InputSchema, OutputSchema, SchemaDef
Referenced by Schema.type, Schema.fields, Schema.items, Schema.values, Parameter.type, SchemaDef.type, SchemaDef.fields, SchemaDef.items, SchemaDef.values
A schema defines a parameter type.
Fields
field | type | required | description |
---|---|---|---|
type | Datatype | Schema | string | array<Datatype | Schema | string> | True | The data type of this parameter. |
fields | array<Schema> | False | When |
symbols | array<string> | False | When |
items | Datatype | Schema | string | array<Datatype | Schema | string> | False | When |
values | Datatype | Schema | string | array<Datatype | Schema | string> | False | When |
5.7.1.2 Binding
Extended by CommandLineBinding, CommandOutputBinding
Referenced by InputSchema.inputBinding, InputParameter.inputBinding
Fields
field | type | required | description |
---|---|---|---|
loadContents | boolean | False | Only applies when |
secondaryFiles | string | Expression | array<string | Expression> | False | Only applies when If the value is an expression, the context of the expression is the input or output File parameter to which this binding applies. If the value is a string, it specifies that the following pattern should be applied to the primary file:
|
5.7.2 InputParameter
Extends Parameter
Extended by CommandInputParameter
Referenced by Process.inputs, ExpressionTool.inputs, Workflow.inputs
Fields
field | type | required | description |
---|---|---|---|
type | Datatype | InputSchema | string | array<Datatype | InputSchema | string> | False | Specify valid types of data that may be assigned to this parameter. Inherited from Parameter |
label | string | False | A short, human-readable label of this parameter object. Inherited from Parameter |
description | string | False | A long, human-readable description of this parameter object. Inherited from Parameter |
streamable | boolean | False | Currently only applies if |
default | Any | False | The default value for this parameter if not provided in the input object. Inherited from Parameter |
id | string | True | The unique identifier for this parameter object. |
inputBinding | Binding | False | Describes how to handle the inputs of a process and convert them into a concrete form for execution, such as command line parameters. |
5.7.2.1 InputSchema
Extends Schema
Extended by CommandInputSchema
Referenced by InputSchema.type, InputSchema.fields, InputSchema.items, InputSchema.values, InputParameter.type
Fields
field | type | required | description |
---|---|---|---|
type | Datatype | InputSchema | string | array<Datatype | InputSchema | string> | True | The data type of this parameter. Inherited from Schema |
fields | array<InputSchema> | False | When |
symbols | array<string> | False | When |
items | Datatype | InputSchema | string | array<Datatype | InputSchema | string> | False | When |
values | Datatype | InputSchema | string | array<Datatype | InputSchema | string> | False | When |
inputBinding | Binding | False | Describes how to handle a value in the input object convert it into a concrete form for execution, such as command line parameters. |
5.7.3 OutputParameter
Extends Parameter
Extended by CommandOutputParameter, WorkflowOutputParameter
Referenced by Process.outputs, ExpressionTool.outputs
Fields
field | type | required | description |
---|---|---|---|
type | Datatype | OutputSchema | string | array<Datatype | OutputSchema | string> | False | Specify valid types of data that may be assigned to this parameter. Inherited from Parameter |
label | string | False | A short, human-readable label of this parameter object. Inherited from Parameter |
description | string | False | A long, human-readable description of this parameter object. Inherited from Parameter |
streamable | boolean | False | Currently only applies if |
default | Any | False | The default value for this parameter if not provided in the input object. Inherited from Parameter |
id | string | True | The unique identifier for this parameter object. |
5.7.3.1 OutputSchema
Extends Schema
Extended by CommandOutputSchema
Referenced by OutputSchema.type, OutputSchema.fields, OutputSchema.items, OutputSchema.values, OutputParameter.type, WorkflowOutputParameter.type
Fields
field | type | required | description |
---|---|---|---|
type | Datatype | OutputSchema | string | array<Datatype | OutputSchema | string> | True | The data type of this parameter. Inherited from Schema |
fields | array<OutputSchema> | False | When |
symbols | array<string> | False | When |
items | Datatype | OutputSchema | string | array<Datatype | OutputSchema | string> | False | When |
values | Datatype | OutputSchema | string | array<Datatype | OutputSchema | string> | False | When |