Script Engine interface for multiple languages6275868Abstract The scripting engine interface provides the capability to interconnect any suitably written application or server with any scripting language. The implementation of the scripting engine itself (language, syntax, persistent format, execution model, and the like) is left entirely to the vendor, and the scripting engine need not come from the same vendor as the host application. The scripting engine interface implements this capability using a set of interfaces, the two most important ones being IActiveScriptSite (implemented by the host application) and IActiveScript (implemented by the language engine.) Together, these interfaces allow a host application to inform a scripting engine about the functionality that can be scripted and to define the scripts that the scripting engine should execute, either immediately or in response to user actions such as mouse clicks. The scripting engine interface redefines the handshake that is required between two specific types of software components in a manner not previously done. Unlike past scripting engine interfaces, which define a unique and proprietary way of hooking up to an application, the interface described here provides a universal hookup mechanism that is simple and direct. Claims What is claimed is: Description FIELD OF THE INVENTION
Term Definition
Script The data that makes up the "program" that the
scripting engine runs. A script is any executable
code, including a piece of text, a block of pcode,
or even machine-specific executable byte codes. A
host computer loads a script into the scripting
engine through one of the IPersist* interfaces or
through the IActiveScriptParse interface.
Script language The language in which a script is written (for example,
VBScript) and the semantics of that language.
Scripting engine The object that processes scripts. A scripting engine
implements IActiveScript and, optionally,
IActiveScriptParse.
Scripting host The application or program that owns the ActiveScript-
ing engine. The scripting host implements
IActiveScriptSite and, optionally,
IActiveScriptSiteWindow.
Scriptlet A portion of a script that gets attached to an object
event through IActiveScriptParse. The aggregate
collection of scriptlets is the script.
Code object An instance created by the scripting engine that is
associated with a named item, such as the module
behind a form in Visual Basic.sup..., or a C++
class associated with a named item.
Named item An object (preferably one that supports OLE Auto-
mation) that the host computer deems interesting to
the script. Examples include the HTML Document ob-
ject in a Web browser, and the Selection object in
Microsoft Word.
Event A signal generated by a user action (such as clicking
a mouse) or by a software component (such as a
software clock with a "tick" event) which
causes associated scriptlets to run whenever the
event occurs.
ActiveX Scripting Background ActiveX Scripting components fall into two categories: ActiveX scripting hosts and ActiveX scripting engines. A scripting host computer creates a scripting engine and calls on the scripting engine to run the scripts. Examples of existing and potential ActiveX scripting hosts include: Web browsers Internet authoring tools Servers Office applications Computer Games ActiveX scripting engines can be developed for any language or run-time environment, including: Microsoft Visual Basic for Applications (VBA) Microsoft Visual Basic Scripting Edition (VBScript) JScript Perl Lisp, Scheme The ActiveX Scripting design isolates the interface elements required only in an authoring environment so that non-authoring host computers (such as browsers and viewers) and scripting engines (for example, VBScript) can be kept lightweight. Basic Architecture FIG. 1 illustrates in block diagram form the operating environment and components which comprise the scripting language engine interface of the present invention, and in particular the interaction between an ActiveX scripting host 105 and an ActiveX scripting engine 101. This example includes the creation of a scripting engine 101 and the execution of a script input thereon. The following description details the steps involved in the interaction between the scripting host 105 and scripting engine 101 (the actual nesting of the function calls is omitted for clarity) and illustrates the flow of information between these components: 1. Create a Project. The scripting host 105 loads a project or document into its workspace from data storage 106 or a data communication interface (not shown) in well-known fashion. (This step is not particular to ActiveX Scripting, but is included here for completeness.) 2. Create the ActiveX Scripting Engine. The scripting host 105 calls the function CoCreateinstance to create a new ActiveX scripting engine 101, specifying the class identifier (CLSID) of the specific scripting engine 101 to use. For example, the HTML browsing component of Internet Explorer receives the scripting engine's class identifier through the CLSID=attribute of the HTML <OBJECT> tag. The scripting host 105 can create multiple scripting engines for use by various applications, and the process of initiating a new scripting engine is well-known. 3. Load the Script. Once the new scripting engine 101 is created, if the script contents have been persisted, the scripting host 105 calls the scripting engine's IPersist*::Load method to feed it the script storage, stream, or property bag that is resident on the scripting host 105. This exposes application's object model to the scripting engine 101, by for example handing one or more application objects to the scripting engine 101. Otherwise, the scripting host 105 uses IPersist*::InitNew or IActiveScriptParse::InitNew to create a null script. A scripting host 105 that maintains a script as text can use IActiveScriptParse::ParseScriptText to feed the scripting engine 101 the text of the script, after calling the function InitNew. 4. Add Items. For each top-level named item 103 (such as pages and forms) imported into the scripting engine's name space 102, the scripting host 105 calls IActiveScript::AddNamedItem to create an entry in the scripting engine's name space 102. This step is not necessary if top-level named items 103 are already part of the persistent state of the script loaded in step 3. A scripting host 105 does not use AddNameditem to add sublevel named items (such as controls on an HTML page); rather, the scripting engine 101 indirectly obtains sublevel items from top-level items by using the host's ITypeInfo and IDispatch interfaces. 5. Run the Script. The scripting host 105 causes the scripting engine 101 to start running the script by passing the SCRIPTSTATE_CONNECTED value to IActiveScript::SetScriptState. This call would likely perform any scripting engine construction work, including static bindings, hooking up to events (see below), and executing code similar to a scripted "main( )" function. 6. Get Item Information. Each time the scripting engine 101 needs to associate a symbol with a top-level item, it calls the IActiveScriptSite::GetItemInfo method, which returns information about the given item. 7. Hook Up Events. Before starting the actual script, the scripting engine 101 connects to the events of all the relevant objects through the IConnectionPoint interface and other methods. As shown in FIG. 1, the IConnectionPoint::Advise(pHandler) message provides the scripting host 105 with a request for notification of any events that occur in the scripting host 105. The message passes an object pHandler that the OAServer can call when an event occurs in the scripting host 105. Once an event occurs in the scripting host 105, the scripting host 105 transmits a message to the scripting engine 101 pdispHandler::Invoke(dispid) to notify the scripting engine 101 that an event occurred in the scripting host 105. If the event matches a monitored event in the scripting engine 101, the scripting engine 101 can activate a response, such as executing user written code. 8. Invoke Properties and Methods. As the script runs, the scripting engine 101 realizes references to methods and properties on named objects through IDispatch::Invoke or other standard OLE binding mechanisms. Additional implementation details of ActiveX Scripting are disclosed herein as well as in Appendix A attached hereto, which document describes ActiveX Scripting Interfaces and Methods. Basically, the user exposes internal objects of the application via OLE Automation and the resultant OLE Automation object is an entity which exposes properties and methods of the application. A method is an action which the object can perform, while a property is an attribute of the object, like a variable. The OLE Automation Interfaces include IDispatch which is an interface to manipulate OLE Automation objects. This process is used to get a property, set a property, or call a method. The process uses "late binding" mechanism that enables a simple, interpreted language. Type information in the OLE Automation includes ITypeinfo which is used for describing an object. A collection of these TypeInfos constitutes a type library, which usually exists on a disk in the form of a data file. The data file can be accessed through ITypeLib and is typically created using MKTypLib. In ActiveX scripting, the type information is provided by scripting hosts and objects that are used by the scripting hosts. The type information is then used by the scripting engines. Active Scripting Engine To write an Active Scripting engine, the user writes an OLE Component Object Model object that supports the following interfaces:
Interface Required? Description
IActiveScript Yes Basic scripting ability.
IPersist* Yes-one of Persistence support.
the following:
IPersistStorage DATA={url} syntax for OBJECT
tag.
IPersistStreamInit . Same as above, as well as DATA=
"string-encoded byte stream"
syntax for OBJECT tag.
IPersistPropertyBag . PARAM= syntax for OBJECT tag.
IActiveScriptParse No Ability to add script text, evaluate
expressions, and the like.
Support for the IActiveScriptParse interface is optional. However, if the IActiveScriptParse interface is not supported, the script engine 101 must implement one of the IPersist* interfaces in order to load a given script. Certain interpreted script languages (for example, VBScript) running in specific scripting host environments (for example, Internet Explorer) may rarely (or never) be called upon to save or restore a script state through IPersist*. Instead, IActiveScriptParse is used by calling IActiveScriptParse::InitNew to create a blank script, then scriptlets are added and connected to events with the function IActiveScriptParse::AddScriptlet and general code is added via IActiveScriptParse::ParseScriptText. Nonetheless, a scripting engine 101 should fully implement at least one IPersist* scheme (preferably IPersistStreamInit), because other scripting host applications may try to make use of them. Registry Standard An ActiveX scripting engine can identify itself as such using component categories. The ActiveX Scripting program currently defines two component
Category Description
CATID_ActiveSport Indicates that the class identifiers (CLSIDs)
are ActiveX scripting engines that support, at
a minimum, IactiveScript and a persistence
mechanism, such as IpersistStorage, IPersist-
StreamInit, or IPersistPropertyBag.
CATID_ActiveScriptParse Indicates that the CLSIDs are ActiveX
scripting engines that support, at a
minimum, IActiveScript and IActiveScript-
Parse.
Although IActiveScriptParse is not a true persistence mechanism, it does support an InitNew method that is functionally equivalent to IPersist*::InitNew. Script Engine States At any given time, an ActiveX scripting engine can be in one of several states, as noted in the following:
State Description
Uninitialized The script has not been initialized or loaded using an
IPersist* interface, or does not have an IActiveScriptSite
set. The scripting engine is generally not usable from this
state until the scripting host takes steps to initialize
the scripting engine.
Initialized The script has been initialized with an IPersist* interface
and has an IActiveScriptSite set, but is not connected
to host objects and sinking events. Note that this
state simply means that Ipersist*::Load,
IPersist*::InitNew, or IactiveScriptParse::InitNew
has been completed, and IActiveScript::SetScriptSite
has been called. The scripting engine cannot run code
in this mode. The scripting engine queues code that
the scripting host passes to it through the function
IActiveScriptParse::ParseScriptText, and executes the
code after transitioning to the started state.
Started The transition from the initialized state to started state
causes the scripting engine to execute any code that
was queued in the initialized state. The scripting
engine can execute code while in the started state,
but it is not connected to events of the objects added
through IActiveScript::AddNamedItem. The scripting
engine can execute code by calling the IDispatch
interface which is obtained from the function
IActiveScript::GetScriptDispatch, or by calling the
function IActiveScriptParse::ParseScriptText. It is
possible that further background initialization
(progressive loading) is still ongoing, and that calling
SetScriptState with the SCRIPTSTATE_CONNECTED
value may cause the script to block until initialization
is complete.
Connected The script is loaded and connected for sinking events
from scripting host objects.
Disconnected The script is loaded and has a run-time state, but
is temporarily disconnected from sinking events from
scripting host objects. This state is distinguished from
the initialized state in that the transition to this
state does not cause the script to reset, the run-time
state of the script is not reset, and a script initializ-
ation procedure is not executed.
Closed The script has been closed. The scripting engine no
longer works and returns errors for most methods.
The functions of these states and their interrelationship is disclosed in the following description of FIGS. 2 and 3. FIG. 2 illustrates in block diagram form the relationships and interactions between the various scripting engine states. FIG. 3 illustrates in flow diagram form the actions and steps that the scripting engine takes during the various state transitions. At step 301 in FIG. 3, the scripting engine instance 101 is created by the scripting host 105 and reserved for future use via execution path 1 in FIG. 2 where the scripting engine 101 is placed in the uninitialized state. The 10 scripting engine 101 executes the functions passed at item 1 in FIG. 2: GO Create Instance ( ) IActiveScript::Clone ( ) to enter the initialized state. The scripting host 105 at step 302 loads data into the scripting engine 101 from data storage or initializes the scripting engine 101 to accept scriptlets. At step 303, the scripting engine 101 runs the function "Main( )", to enter the started state where the scripting engine 101 proceeds to hook up events at step 304 in the connected state. Once the events are hooked up, the scripting engine 101 reenters the initialized state at step 305 to destroy the run time state and unhook the events at step 306. The scripting engine 101 in this process executes the functions passed at item 2 in FIG. 2: IPersist*::Load( ) or IPersist*::InitNew( ) or IActiveScriptParse::IniNew( ) and IActiveScript::SetScriptSite( ) The scripting engine 101 is now in the disconnected state and at step 307 begins the execution of its defined function by rehooking events and executing the defined function. The scripting engine 101 receives, interprets and executes the code that is passed to it by the scripting host 105, in response to script input in the application. The functions that are passed in item 3 of FIG. 2 and executed in this step comprise: IActiveScript::SetScriptState( ) The scripting engine 101 at step 308 completes the execution of the received code and executes the function passed at item 4 in FIG. 2: IActiveScript: :Close( ) The scripting engine 101 at step 308 destroys the run time state and at step 309 unhooks events, releases all held interface pointers and frees the allocated resources. At step 310, the scripting engine 101 is released and ceases operation until it is again activated by the scripting host 105. The final function executed by the script engine 101 and passed on path 5 in FIG. 2 to the scripting host 105 at this step is: Release( ). This completes the creation and operation of the scripting engine 101. ##SPC1## ##SPC2## ##SPC3## ##SPC4## ##SPC5## ##SPC6## ##SPC7## ##SPC8## ##SPC9## ##SPC10## ##SPC11## ##SPC12##
|
Same subclass Same class Consider this |
||||||||||