Orion/Documentation/Developer Guide/Plugging into the shell

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Overview of contributing services to the Shell

The Shell page provides a view through which users can interact with Orion via a command-line interface. The page provides some basic commands for navigating Orion's workspace, and defines a service that allows plug-ins to contribute additional commands.

orion.shell.command

The orion.shell.command service is used to contribute commands to the Shell page. When the service is executed, an object containing the user-supplied argument values is passed to the service's callback method. The command then optionally returns a response (a return value) to be displayed in the Shell.

Service methods

Implementations of orion.shell.command may define the following function:

callback(args)
Takes the user-supplied command-line arguments (if any) as an argument, and optionally returns a response string in plain text (no HTML is allowed).

The only context where a contributed command would not define a service method is to assist with the contribution of sub-commands. For example, to contribute commands "tar create" and "tar extract", a parent command "tar" without a service method must first be contributed.

Service attributes

Implementations of orion.shell.command define the following attributes:

name
The name that is typed at the command line to invoke the command
description
(Recommended) A brief description of the command
manual
(Optional) A longer description of the command
parameters
(Optional) An array of the parameters that the command accepts

The Shell page currently uses GCLI as its underlying shell widget, and consequently has adopted its syntax for parameter specification. For details on this syntax begin reading at the "## Default argument values" header in the GCLI Writing Commands doc. The basic parameter object attributes are:

name
The parameter's identifier
type
One of { string | boolean | number | array | selection | a custom orion.shell.type}
description
(Recommended) A brief description of the parameter
defaultValue
(Optional) The value assumed by the parameter if the user does not supply a value for it, makes the parameter optional

orion.shell.type

The orion.shell.type service is used to contribute parameter types to the Shell page. These enable contributed commands to have custom parameters with dynamically-computed completion suggestions. The service is executed when the Shell page needs either completion suggestion values to display, or the string representation for a given value.

Service methods

Implementations of orion.shell.type define the following functions:

parse(arg, typeSpec, context)
Takes the currently-typed user string and returns an object with completion suggestions. The arguments to this function are:
arg
An object with properties {prefix: string, suffix: string, text: string}, contains the user's currently-typed string for an instance of this parameter
typeSpec
This parameter's typeSpec as defined by the command that is using it
context
An object with additional information; currently its only property is {lastParseTimestamp: number}, which can aid in determining when the completion suggestions being returned should be recomputed

The return value for this service must be either an orion.Deferred (if computation of the result object has to be done asynchronously), or an object with the following properties:

status
One of the following numbers:
0: (MATCH) the currently-typed string matches a valid value (ie.- the typing of this parameter value can now be considered complete)
1: (PARTIAL) the currently-typed string partially matches a valid value (ie.- the typing of a valid value in progress)
2: (ERROR) the currently-typed string does not match a subset of the initial characters of any valid values
message
(Optional) An error message to display in the Shell page
predictions
An array of {name: string, value: object} objects that are valid completions for the currently-typed string (name is the string to display in the suggestions list)
value
If the currently-typed string is a match for a valid value then set this property to that {name: string, value: object} value, otherwise set its value to undefined
stringify(object, typeSpec)
(Optional) Returns an object's string representation that is appropriate for display in the Shell page's output area. An example case where this string may not be the same as the "name" that was specified for it by the parse service is if a typed relative path should be resolved to an absolute path. If this service is not implemented then the object's "name" that was specified for it by the parse service implementation is used as its display string. The arguments to this function are:
object
The object to stringify
typeSpec
This parameter's typeSpec as defined by the command that is using it

Service attributes

Implementations of orion.shell.type define the following attribute:

name
The name of the parameter type (used in the plug-in definition of contributed commands)

Example

The following sample plug-in contributes an "echo" command to the Shell:

<html>
<head>
<script src="http://orionhub.org/orion/plugin.js"></script>
<script>
 var serviceImpl = {
   callback: function(args) {
     return "'" + args.string + "'";
   }
 };
 var serviceProperties = { 
   name: "echo",
   description: "Echo a string",
   parameters: [{
     name: "string",
     type: "string",
     description: "The string to echo back"
   }]
 };
 var provider = new orion.PluginProvider();
 provider.registerServiceProvider(
   "orion.shell.command",
   serviceImpl,
   serviceProperties);
 provider.connect();
</script>
</head>
</html>


When this plug-in is installed the user can use the "echo" command in the Shell. In the first image shown below a user is in the process of entering an echo command, and is shown a hint that argument "string" (the string to echo) is expected.

Orion-shell-command-example1.jpg


In the following image the echo command has executed and its result is shown in the output area.

Orion-shell-command-example2.jpg