INTERPROCESS COMMUNICATION
Interprocess Communication (IPC) is the mechanism that facilitates communications and data sharing between applications.
It enables one application to control another and multiple applications to share the same data without interfering with one
another. IPC utilizes a set of programming interfaces, called communication protocols, which allow programmers to
coordinate activities among different applications.
Applications using IPC are categorized as either Client or Server, in which the Client requests data and the Server responds to
Client requests. Many applications (including ExtendSim) can be either Client or Server, depending on the circumstances.
ExtendSim provides support for IPC through the industry standard technologies shown below. This allows external
applications to control and communicate with ExtendSim and vice versa, in much the same way a user would. Note that, in
addition to several interfaces for interactive data exchange, ExtendSim supports multiple methods for storing and managing
data, such as global and dynamic arrays, embedded objects, linked lists, and (most importantly) an internal relational
database.
IPC Protocols and methods - communicating between external applications and ExtendSim
PROTOCOL/METHOD EXPLANATION
USE
Communicate with, exchange data with, or
COM (Component
A set of object-oriented programming
control another application. Embed or link data
Object Model)
technologies and tools for IPC.
that, when chosen, automatically starts another
application for data editing.
The objects and methods that ExtendSim
Primary method for ExtendSim to be controlled
ExtendSim COM Object
exports for Automation, including Execute,
and communicated with as a COM Automation
Model
Poke, and Request.
Server.
Call an external code segment from a block's
Libraries of routines or functions written in an
code and perform operations. A block can pass
external language, such as C++. These are the
DLLs (Dynamic-Link
data to the DLL, cause the DLL to calculate using
standard methods for linking between the
Libraries)
that data, and get the results back from the DLL.
ExtendSim internal programming language
For example, in ExtendSim, the Rate library
(ModL) and other languages and applications.
blocks communicate with the LPSolve DLL.
ExtendSim can load up and communicate with a
A library developed in an external language,
COM DLL or be controlled by a COM DLL. For
COM DLL
such as C++, to create or define Active X
example, see how ADO is implemented in
objects.
ExtendSim.
A subset of COM (previously OLE Automation).
Enables applications to expose their unique
Access and manipulate (i.e. set properties of or
Automation
features (properties, methods, and events) to call methods on) shared automation objects that
scripting tools and other applications. The
are exported by other applications.
exposed objects are called ActiveX objects.
Send an entire table of information at one time;
high-speed data interchange. In ExtendSim ADO
ADO (ActiveX Data
An Automation protocol for exchanging
is implemented as a COM DLL for
Objects)
information with ADO-compliant databases.
communication with ADO-compliant databases
such as Microsoft Access.
FTP (File Transfer
Protocol for sending files or data to and from Import from, or export to, files located on a
Protocol)
internet web pages.
server or on the web.
An easy way for ExtendSim to send and receive
short (<400 byte) messages. Also provides the
Mail Slots
Functions for inter-computer communication.
ability to broadcast messages across all
computers in a network domain.
A standard programming language middleware
ODBC (Open Database
This legacy technology has been superseded by
API for accessing database management
Connectivity)
ADO.
systems (DBMS).
DDE (Dynamic Data
A protocol that enables applications to
This legacy technology has been superseded by
Exchange)
exchange data in a variety of formats.
Automation.
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Interprocess Communication
Communicating between external applications and ExtendSim
The IPC technologies listed above have been developed as industry standards to allow applications to share and access data
independent of programming language, operating system, and file type. You can incorporate IPC into ExtendSim models by:
1. Using ExtendSim menu commands and blocks for import/export
2. Embedding objects (Windows only)
3. Using the ExtendSim I/O functions – ExtendSim as IPC Client
4. Using an external language to access ExtendSim Automation protocols - ExtendSim as IPC Server
ExtendSim can act as a Client, connecting to and requesting data and services from a Server application. It can also act as a
Server application that is controlled by any Windows application that can be configured as an Automation controller.
The table below shows how ExtendSim can communicate with other applications and with ExtendSim models running on
other computers, even while the simulation is running. This allows ExtendSim to work on a wide variety of tasks jointly with
external applications such as spreadsheets, external databases, word processors, statistics packages, and so forth.
ExtendSim uses and
supports IPC
technologies
through:
Read or Write
blocks
Data Import
Export block
Text
File
Excel
X
X
X
X
Command block
Internal Database
ExtendSim DB
Add-In
ADOCompliant
Databases
X
X
X
External
databases
X
External
languages control
ExtendSim
Other
applications
Other
applications, COM
DLLs
OLE/COM
functions
DLL functions
ADO (user-defined
functions)
Mailslot functions
Internet Access
Serial I/O
functions
FTP site
Excel Macro, DDE
command
OLE Automation ExtendSim as
Server
IPC functions
X
Notes
Value and Item libraries. UG 755.
X
X
Other
Communication
& Control
X
Other
applications
X
Other computers
Web, internet
Equipment
Value library – UG 763; Import and
Export commands – UG 766.
Value library. Select a command to
send and choose when it is sent.
Integrated in ExtendSim. UG 728742.
Allows Excel to create, edit, and
export an ExtendSim DB file. UG
742-747.
DR 111-118. See examples in folder
ExtendSim9\Examples\Developer
Tips\OLE Automation.
DR 239-241; UG 765-771.
DR 241-249; UG 767-769. Example
in ModL library>OLE category.
DR 254-256. Example in the folder
ExtendSim9\Examples\Developer
Tips\DLLs.
DR 380-383 & UG 769 for ADO; DR
79 for Include Files.
DR 249
DR 236.
DR 253-254.
DR 250-253. Example in ModL Tips
library > Input/Output category.
All references are to the ExtendSim 9 User Guide (UG) or Developer Reference (DR), released February 13, 2015.
ODBC functions
X
Communicating with external devices and equipment
There are two methods you can use to communicate with external devices such as scientific equipment and other
hardware:
1. Dynamic Link Libraries (DLLs) on Windows or Shared Libraries for Mac OS. DLLs and Shared Libraries are
segments of code written in a language other than the ExtendSim ModL language, such as Visual Basic or C++. A
standardized interface provides a method for linking between other languages and ModL. DLLs can also be used to
perform complex calculations utilizing specialized hardware.
2. Serial port functions on Windows. To pass data through serial devices, use the serial port functions. (Note that this
is a legacy technology.)
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www.ExtendSim.com
August 2015