Internet Programming with Delphi


by Marco Cantù
(http://www.marcocantu.com)
Table of Contents
The Challenges of Internet Programming …………………………………1
Where does Delphi Fit?……………………………………………………………..2
Core TCP/IP Support……………………………………………………………….3
Client Side Protocols Support……………………………………………………4
Server Side Protocols Support …………………………………………………..4
Client Side Web Support……………………………………………………………5
Server Side Web Development………………………………………………….6
Generating HTML pages …………………………………………………………..6
The WebBroker Framework ……………………………………………………..7
Supporting Microsoft’s Windows DNA architecture ………………..9
InternetExpress: XML, ECMAScript, and DHTML……………….10
Third-Party Web Server Extensions ………………………………………..13
Delphi in Action on the Internet……………………………………………..13
Conclusion: The Delphi Advantage…………………………………………14
Borland Delphi is known to be a great environment for the
development of stand-alone and client-server applications on the
Microsoft Windows platform. Its virtues range from full OOP
support to visual development, in a unique combination of
power and ease. However, the new frontier of development is
now Internet programming. What has Delphi got to offer in this
new context? Which are the features you can rely upon to build
great Internet applications with Delphi? That’s what this paper
intends to reveal. We’ll see that Delphi can be used:
• For direct socket and TCP/IP programming;
• In conjunction with third-party components that implement
the most common Internet protocols, on the client or the
server side;
• To produce HTML pages on the server side, with the
WebBroker and Internet Express architectures;
• As well as to work with Microsoft’s core technologies,
including MTS, COM, ASP, and ActiveX.
The Challenges of Internet
Programming
Internet programming poses new challenges to traditional
developer environments and to the programmers using them.
There are issues related with the implementation of standard
protocols, the use of multiple platforms (Microsoft Windows
accounts for most of the client computers on the Internet but
only a fraction of the servers), and the licensing schemes of
some RDBMS systems.
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Most of the problems, however, relate with HTTP development:
Turning existing Windows applications into applications running
within a Web browser is more complex than it might seem at
first sight. The Web is stateless, the development of user
interfaces can be quite an issue, and you invariably have to
consider the incompatibilities of the most widespread browsers.
A new platform specifically aimed at areas of Internet
programming (typically the HTTP world) has emerged. These
environments favor server side development, often also allowing
the inclusion of database information within web pages. A
common solution is to write HTML pages with special
“scripting” tags included, which are going to be expanded by an
engine on the server. Interesting for small projects, most of
these technologies have limited scripting power, and force you to
mix HTML code and scripting code, and GUI scripting code
with database oriented code. On larger applications, this lack of
separation among the different areas of a program is considered
to be far from a good architecture.
Moreover, Microsoft’s DNA is going to be replaced by the new
Microsoft dotNET (or “.NET”) architecture – a new name and
approach that seems to imply that the previous architecture had
indeed serious limitations. DotNET is apparently going to be
more “open” and stresses a lot the importance of XML,
including pushing the support for the SOAP (Simple Object
Access Protocol) invocation protocol. Another key element of
dotNET is that COM is apparently going to be phased out (not a
nice idea for people who’ve invested in the approach Microsoft
was pushing yesterday).
Even with the advent of dotNet, Microsoft’s DNA architecture,
based on ASP for HTML scripting and COM/MTS/COM+ for
database manipulation, offers a higher perspective, but is limited
to the Windows platform and Microsoft’s own IIS Web server,
tends to work primarily with the Internet Explorer browser. The
current incarnation of DNA suffers from several limitations,
including DCOM unfriendliness with firewalls, complex
configuration and administration, some tie-in with Microsoft’s
technologies, databases included, and limited scalability. Also,
the overall architecture, with the separation of many layers
partial with status and partially stateless, seems to be still limited
for the challenges of the Internet.
Where does Delphi Fit?
With this rather complex situation going on, where does a
“traditional” development platform like Delphi fit? The goal of
Delphi in the Internet age is to bring the some power, flexibility,
ease of use, and database support.
• The power of Delphi comes from the fully compiled code,
different from many script-based technologies, and from its
fully object-oriented architecture (which is not an after
thought, but has been the foundation of the language and
its libraries since version 1.0). Delphi natively compiled
applications are simple to deploy, as they are generally made
of a single self-contained executable code (with no extra
runtime libraries and custom component files). Actually,
dividing the single EXE in multiple packages is a useful
option that is offered by Delphi, which programmers can
fine-tune to choose the best deployment solution.
• The flexibility of Delphi comes from a support not limited
to HTTP but open to most Internet protocols, as the
development environment allows you to write lower level
code to support new protocols, as the developers of many
native third-party components have done.
• The ease of use of Delphi comes from the componentbased
environment. Writing a mail client (eventually bound
to a web page) simply implies adding a couple of
components to your program, setting a few properties, and
writing very little code. Some of the samples found in
Delphi and the third party components are basically fullfeatured
email programs!
With the InternetExpress technology of Delphi 5, the easeof-
use has been extended to allow the visual development
of HTML front ends based on data sets.
• Database and client/server support has always been one of
the strongest features of Delphi and client/server
architectures remain the core of most Web applications and
Internet sites. Actually, if you’ve built your Delphi
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applications by separating the user interface from the back
end (typically using Data Modules for the latter) you are
ready to plug in a new user interface to your existing
“business rules” code.
This is particularly true for multi-tier MIDAS applications,
which separate the business logic and the user interface in
two separate applications, running on the client and
application server computers. Using the InternetExpress
technology, as we’ll see, you can simply build a new front
end for a Web server application, and make it available to
the client browsers.
Leveraging your existing Delphi code and allowing you to build
Windows and browsers based front end for the same core
application, are two key reasons to adopt Delphi as your Internet
development platform. But they are not the only reasons, as
other areas of Internet development are equally served by the
technologies included in Delphi.
Finally, with the forthcoming Kylix project (see
http://www.borland.com/linux), Borland are providing a
“Delphi for Linux”, allowing your server side applications to run
equally well on Microsoft Windows or Linux operating systems.
Delphi will be able to leverage features of the two platforms
without any tie-ins to a specific operating system, allowing your
Web server applications to run on the two most widespread
operating systems for Internet servers.
Core TCP/IP Support
The common factor for all Internet and Intranet applications is
communication over TCP/IP sockets. Most of the time the
communication is constrained by a set of rules, known as a
communication protocol. For example, SMTP and POP3 are
two very simple protocols for sending and retrieving mail
messages, defined by the Internet standard bodies.
Using Delphi you can:
• Implement the client and the server side of a proprietary
protocol, using the TServerSocket and TClientSocket
components, found in the Internet page of the component
palette. This is handy for distributed applications, but
creates a closed system, in which other programs not
written by you cannot interact (which might be an
advantage or a disadvantage, depending on the situation).
That is, of course, unless you want to define a new protocol
and publish the specs for others to “join” you.
Figure 1: The Internet page of Delphi’s component palette,
hosting the socket and HTML producer components.
• Implement an existing protocol on the client or on the
server side. This can be done again with the generic socket
components mentioned above, but its generally
accomplished by using protocol-specific Delphi
components provided by third parties, some of which are
even pre-installed in the Delphi IDE.
• Support the HTTP protocol, the core of the Web, and the
HTML file format. As these play such a major role, I’ll
cover them separately from the other protocols.
The support for TCP/IP and socket programming in Delphi is
as powerful as using the direct API (Winsock, in case of the
Windows platform) but far simpler. The socket components, in
fact, shield the programmer from some of the complex technical
details, but surface the Windows handles and low-level APIs,
allowing for custom low-level calls.
Writing simple programs with socket support in plain C calling
the Windows APIs requires hundreds of lines of code, while
using the Delphi socket components, a few lines of code will
suffice, even for complex tasks. That’s the standard advantage of
component-based development. Also, building a simple user
interface for the program is often trivial in Delphi. With other
development environments, you need to program the socket in a
low-level language (such as C) and then write the user interface
with a different visual tool, integrating the two and requiring
knowledge of multiple languages.
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Client Side Protocols Support
To develop the client side of Internet applications, Delphi
provides you ready-to-use components. There are multiple sets
of native VCL components you can adopt, all based on a similar
philosophy:
• The NetMaster components are pre-installed in the Delphi
environment (see the FastNet page of the component
palette), and include client-side support for the most
common Internet protocols (including POP3, SMTP,
NNTP, FTP, and HTTP).
• The Indy open source components (“Internet Direct”,
previously called WinShoes and now “federated” with the
Jedi Project) are available on Delphi 5’s Companion CD and
from their web site (http://www.nevrona.com/indy). It has
been announced that Indy will be included by default in
Delphi 6 and Kylix (Delphi IDE for the Linux platform).
• The free ICS components (“Internet Component Suite”,
available at http://users.swing.be/francois.piette/icsuk.htm,
include the complete source code) and are designed and
maintained by Francois Piette and form another set of very
popular Delphi components, supporting most Internet
protocols.
• A few other commercial offerings, including IP*Works
components (http://www.dev-soft.com/ipwdlp.htm) and
Turbo Power’s Internet Professional
(http://www.turbopower.com/products/IPRO/).
Some of these components map directly to their own WinSock
wrappers, others also use the WinInet library, a Microsoft system
DLL that implements support for the client side of FTP and
HTTP protocols. Regardless of the set of components you are
going to use, they are really quite simple to work with. If you
have an existing application, and want to mail-enable it, just drop
a couple of components onto your form (or data module), set
their properties (which include the indication of the mail server
you want to connect with) and write few lines of code.
For example, to send email with NetMaster’s component, you
can use the following simple code:
// component properties
object Mail: TNMSMTP
Host = ‘mail.server.com’ // your web
service
Port = 25
PostMessage.FromAddress =
‘marco@marcocantu.com’
end
// code to send the above email
message
Mail.PostMessage.ToAddress.Add
(‘davidi@borland.com’);
PostMessage.Subject := ‘Borland
Community Site’;
PostMessage.Body.Add (‘Hi David, I
wanted to ask you…’);
Mail.Connect;
Mail.SendMail;
Mail.Disconnect;
In short, these are the advantages of using Delphi for supporting
Internet client applications:
• Choice among various offerings of components (some of
which are totally free and open source)
• Easy integration with existing applications
• Easy development of new and specific user interfaces, with
Delphi visual and object oriented architecture
Server Side Protocols Support
Besides supporting web protocols in existing applications, or
writing custom client programs specifically for them (as a
completely custom email program), in a corporate environment
you often need to customize Internet server applications. Of
course, many of the available pre-built servers can be used and
customized, but at times you’ll need to provide something that
existing programs do not support.
In that case, you might think of writing your own server, if only
it wasn’t so complex. Using Delphi and a set of server side
components you can build custom servers with only limited
extra effort, compared to a client program, and achieve (or at
times exceed) the performance of professional quality Internet
server programs.
Server side components were pioneered by Jaadu
(http://www.jaadu.com), which offers a web server component
and are now available in the Indy component set (discussed
above). There is also a set of highly optimized native Delphi
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components, called DXSock (http://www.dxsock.com),
specifically aimed at the development of Internet server
programs. Some of the demonstrations of these component sets
are actually full-fledged HTTP, mail, and news servers.
Client Side Web Support
If many Internet protocols are important, and email is one of the
most commonly used Internet services, it is undeniable that the
Web (that is, the HTTP protocol) is the driving force of most of
the Internet development. Web support in Delphi is particularly
rich. Here, we are going to start by exploring the features
available on the client side (to integrate with existing browsers)
and then we’ll move to the server side, devoting plenty of time
to the Web server development that you can do with Delphi.
• The HTTP components available in most suites allow you
to create a custom browser within your application: You can
reach existing Web sites and retrieve HTML files or post
custom queries. At this point you can send the HTML
content returned by the HTTP server to an existing browser
or integrate a custom HTML processor or HTML viewer
within your application. The ways in which can apply are as
follows:
• Sending an HTML file to Microsoft’s Internet Explorer or
Netscape Navigator, either using it as an external
application, by calling the ShellExecute API function:
ShellExecute (Handle, ‘open’,
‘c:\tmp\test.htm’, ”, ”,
sw_ShowNormal);
or integrating the Internet Explorer ActiveX control,
surfaced in Delphi as the ready-to-use WebBrowser
component.
• Processing HTML in a custom way, to extract specific
information; this is useful in case you don’t need to show
the HTML to a user, but want to process it, eventually
extracting specific information from it.
• Showing the HTML within your program using a native
Delphi component (so that end users don’t need to have
Internet Explorer installed). These components are available
by third parties, with the most well known HTML viewer
component being offered by David Baldwin (see the Web
site http://www.pbear.com).
The reverse of integrating a browser within your application, you
can integrate your application within the browser. This is rather
easy to accomplish by using Internet Explorer and the ActiveX
technology. Delphi supports this technology in full using the
ActiveForm technology. An ActiveForm is built in the same
visual way that a plain Delphi form is constructed, but an
ActiveForm is hosted within an HTML page of Internet
Explorer. You can even move existing programs to the Web by
hosting their main form within an ActiveForm.
Figure 2: An example of a wizard built with Delphi (it is
based on a PageControl component) and deployed within
an ActiveForm. The buttons allow you to reach different
pages of the form, without moving outside of the browser’s
page.
This Microsoft specific technology (ActiveX is not supported by
other browsers) can simplify the deployment of simple Delphi
applications within an Intranet, as users can download the
programs they need by pointing their browser to specific pages.
The ActiveX technology, however, is not well suited for the
Internet, as too many people have different browsers or
operating systems, or disable this feature in their browser for
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fear of the potential harm caused by the automatic execution of
programs that are downloaded from the Web.
• The advantage of Delphi in this area is that, once more, it
allows you to customize your existing programs to take
advantage of the Internet, and make them work seamlessly
with Web browsers. Also, if you choose not to use the
ActiveX technology, you won’t be tied to any particular
browser or platform.
Server Side Web Development
As anticipated, all the development related to Web servers is by
far the most important area of Internet development, and again
one where many alternative solutions are available. Delphi has
offered developers strong server side Web development since
version 3, with Delphi 5 being a mature environment for
building Web server extensions. Delphi includes multiple
technologies to support server side development, so I’m going to
cover:
• The HTML Producer components
• The WebBroker technology for building CGI, WinCGI, and
ISAPI/NSAPI server side extensions
• The Internet Express technology (introduced in Delphi 5)
for building database-oriented server side applications,
based on standard technologies such as XML and
ECMAScript (formerly known as JavaScript).
Generating HTML pages
Delphi includes several components aimed at the generation of
dynamic HTML pages. There are two different sets of producer
components, page-oriented and table-oriented ones. When you
use a page oriented HTML producer component, such as the
PageProducer, you provide the Producer component with an
HTML file with custom tags (marked by the # character). You
can then handle the OnTag event of the component to replace
these custom tags with specific HTML code.
The following is sample code for this OnTag event:
procedure
TFormProd.PageProducer1HTMLTag(Sender:
TObject;
Tag: TTag; const TagString: String;
TagParams: TStrings;
var ReplaceText: String);
var
nDays: Integer;
begin
if TagString = ‘date’ then
ReplaceText := DateToStr (Now)
else if TagString = ‘expiration’
then
begin
nDays := StrToIntDef
(TagParams.Values[‘days’], 0);
if nDays <> 0 then
ReplaceText := DateToStr (Now +
nDays)
else
ReplaceText := ‘<I>{expiration
tag error}</I>‘;
end;
end;
This code handles a plain tag, date, which is replaced with the
current date, and a parametric one, expiration, which includes a
parameter indicating the number of days the information on the
page remains valid. The HTML for this custom tag will look like:
Prices valid until <b><#expiration
days=21></b>
The output will be something like: “The prices in this catalog are
valid until 12/24/2000”, as you can see in Figure 3.
Figure 3: The HTML file generated by a PageProducer
component.
The advantage of this approach is that you can generate such a
file using the HTML editor you prefer, simply adding the custom
tags. Notice also that the same OnTag event handler can be
shared by multiple producer components, so you don’t need to
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code the same tag expansion multiple times within the same
program.
A second component of this group, DataSetPageProducer, can
automatically replace tag names with the values of the fields of
the current record of a dataset.
Another group includes HTML table oriented components. The
idea is to convert automatically a dataset (a table or the result set
of a query or stored procedure) into an HTML table. Although a
standard conversion is supplied, you can add custom tags and
styles for the grid, each of the columns, and even specific cells of
the table. The customization is similar to that which can be
applied to a visual DBGrid inside a Windows application. For
example, the following code turns all the cells of the second
column that have a value exceeding 8 digits red in color (with the
effect you can see in Figure 4):
procedure
TFormProd.DataSetTableProducer1FormatC
ell(
Sender: TObject; CellRow,
CellColumn: Integer;
var BgColor: THTMLBgColor; var
Align: THTMLAlign;
var VAlign: THTMLVAlign; var
CustomAttrs, CellData: String);
begin
if (CellColumn = 1) and (Length
(CellData) > 8) then
BgColor := ‘red’;
end;
Figure 4: The output of a DataSetTableProducer, with
custom colors for specific cells.
The second component, the QueryTableProducer is specifically
tailored for building parametric queries based on input from an
HTML search form. The parameters entered in the form are
automatically converted by the component into the parameters
of a SQL query and the resulting dataset is formatted in an
HTML table: all this complex work can be set up with no
custom coding!
Advantages
• You can write the basic HTML code with the editor you
prefer and simply include custom tags.
• You are not mixing scripting code with the HTML code,
but keep them totally separate. The HTML simply includes
a placeholder for the code that is going to be generated.
• The script is replaced by full-performance compiled code.
• Using this technique you can easily access database data,
and render the result of complex queries in HTML tables
with no custom coding!
Further Notes
The HTML producer components can also be used to produce
static web pages, that is plain HTML files that can be placed on
your web server and not server dynamically by a program.
Notice also that beside HTML files, Delphi programs can
produce JPEG files, using the TJPEGImage component. Again,
these files can be placed on a server or produced dynamically
from a server extension. The generation of images includes the
generation of the complex business graphs, available through the
native TeeChart components.
The WebBroker Framework
The development of Web server extensions (that is, custom
applications seamlessly integrated with a Web server) can be
based on multiple competing technologies, including:
• CGI (Common Gateway Interface, common on UNIX
boxes),
• WinCGI (the Windows flavor of the same technology),
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• ISAPI Internet Server API, libraries specifically tailored for
Microsoft’s own IIS) and NSAPI (the corresponding API
offered by Netscape’s web server),
• Apache modules (the same idea, but for the open-source
Apache Web server) – this standard is not currently
supported by Delphi, but Borland has revealed plans to
support it in Kylix, the project for a Linux version of
Delphi.
The problem with most of these technologies is that even if they
are all based on the HTTP protocol, the way you receive the
same information and make it available to the Web server
changes substantially. For this reason, Borland has built in the
VCL a small object-oriented framework, called WebBroker,
which removes those differences. You write all of your code
targeting a few generic base classes, and ask Delphi to provide
you a specific implementation for, say, CGI or ISAPI. This
means you can move your programs (even complex ones) from
one of these technologies to another simply by providing a
different project source code and a few lines of code.
• Once the “bridge” includes Linux based servers beside
Windows ones, the WebBroker technology will be able to
bridge a large variety of web servers on multiple operating
systems.
Not only does WebBroker provide a bridge among multiple
technologies, it also provides a lot of core routines and facilities,
to simplify server side development. For example, you can ask
for a specific value inside a query string by writing:
stringName := Request.QueryString
[‘Name’];
instead of having to parse a complex string yourself. This is just
one simple example, there are a great many timesavers within the
WebBroker architecture, to enable you to really speed up
development.
Consider also that the WebBroker architecture is generally used
in conjunction with the HTML producer components. The
development of a program which executes a query on a SQL
server, formats it using an HTML table, and returns it from a
server side application takes probably less than 20 mouse clicks
and almost no coding!
Figure 5: A query form like this one can be directly tied to
the parameters of an SQL query, via a QueryTableProducer
component and with almost no coding!
For example, if you have the following HTML file with a table
(shown in Figure 5), you can hook it with a script (called
CustQuery.exe) to process the request. This is the HTML code,
with a table having two input fields:
<html><head>
<title>Customer Search
Form</title>
</head>
<body>
<h1>Customer Search Form</h1>
<form
action=”/scripts/CustQuery.exe/search”
method=”POST”>
<table>
<tr><td>State:</td>
<td><input type=”text”
name=”State”></td></tr>
<tr><td>Country:</td>
<td><input type=”text”
name=”Country”></td></tr>
<tr><td></td>
<td><center><input
type=”Submit”></center></td></tr>
</form>
</body>
</html>
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Figure 6: The choices offered by Delphi’s Web Server
Application Wizard.
Now you can create a Delphi WebBroker application, using the
Web Server Application Wizard (see Figure 6), and choosing
CGI (or whatever technology you prefer). Inside the
WebModule Delphi will create and open for you, you can add an
action, by right-clicking on the Actions item of the Objects Tree
View (above in Figure 7) or using the add button or local
command of the resulting actions list editor (below in Figure 7).
You can open the action list editor double clicking on the
WebModule itself.
Figure 7: The actions of a WebModule can been seen in the
Objects Tree View (at top) and in the actions list editor (at
bottom). Their properties are set in the Object Inspector
(at left).
Set the action with the “/search” value in the PathInfo property.
This can be connected (using the Producer property) with a
QueryTableProducer component added to the data module. This
component, in turn, is hooked to a Query component, via its
Query property.
The Query component will be executed when the action is
invoked, passing to its Params the QueryStrings or
ContentStrings parameters of the WebRequest. This means that
Delphi will extract the values entered in the HTML input boxes
and copy them to the query parameters having the same name.
So, we can use a query like the following, with to parameters
having the same name of the input fields (see again the HTML
code above):
SELECT Company, State, Country
FROM CUSTOMER.DB
WHERE
State = :State OR Country = :Country
That’s all! Even with no Delphi code we’ve obtained an HTML
front end for a database search. By customizing the HTML table
output, attaching a style sheet, adding extra code for custom
processing, you can build a professional version of this program
within a few hours.
In short:
• WebBroker allows you a single source code solution for
multiple technologies: CGI, CGI-Win, ISAPI/NSAPI, and
also Apache Modules moving forward.
• Combined with the HTML producer components, your
server side applications can easily produced HTML pages,
particularly showing database data.
• Your WebBroker code will be portable to Linux with little
effort, once Kylix is released.
Supporting Microsoft’s Windows DNA
architecture
Besides talking about the WebBroker framework, and the
Internet Express technology I’ll discuss later, Delphi has a full
and high quality support for the entire Windows’s DNA
architecture (which will be superceded by the dotNet
architecture, but is probably going to remain in use for quite
some time). Delphi has traditionally been the first visual
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development environment to support ActiveX and MTS
technologies, even before Microsoft’s own visual tools provided
such support.
Not only this, but Delphi’s simplified and yet complete COM
support is still unparalleled in the industry. Based on this highquality
low-level COM support, Delphi provides support for
most COM-related technologies, such as Windows Shell
programming, Automation, Active Documents, ActiveX (and
also the Web-oriented ActiveForm technology I’ve already
covered), MTS and COM+, and many others.
Using Delphi you can write MTS object defining your business
rules and database integration code, provide a layer of ASPenabled
COM objects to generate HTML and user interface
elements, and wrap everything in ASP scripts (Microsoft’s Active
Server Pages technology). This corresponds to embrace
Microsoft’s proposal in full, with high quality support.
Giving this past track record, we can probably expect a future
release of Delphi to fully support COM+ (although I have to say
you can already write COM+ applications with Delphi 5, with a
little extra effort) and other emerging Microsoft standards.
In short:
• Delphi’s support for the Windows platform is complete,
including the support for the entire COM architecture and
the Windows DNA model.
• Delphi’s ability to write low-level COM code makes it
possible for you to target new standards without having to
wait for Borland support within the development
environment. You can hardly say the same for any other
visual tool.
• While fully supporting Microsoft technologies, Delphi
allows you to avoid the strong tie-ins you’ll end up with by
using Microsoft tools. With a little engineering effort, you
can build Delphi classes which can exposed their
functionality in a way suitable to Microsoft’s DNA
technologies (for example using the Delphi code inside
ISAPI servers and COM objects) and be able to port them
to other Web Servers and other platforms, such a Linux, by
providing a different wrapper to the same core code.
InternetExpress: XML, ECMAScript, and
DHTML
Delphi 5 has further extended the traditional Delphi offering in
the area of Internet development by providing a brand new
technology based on the most recent open standards.
InternetExpress is based on two key components:
• The XMLBroker component can convert an existing dataset
(using the MIDAS data stream format) into XML data. You
can convert the result of a query, an entire table, and use
any of the Delphi dataset components (those based on the
BDE, the dataset components based on Microsoft’s ADO,
or the native InterBase components), to provide data to the
XMLBroker and surface it on a web page.
• The MidasPageProducer component is a visual component
designed for HTML forms based on the data provided by
the XMLBroker. These pages, once made available in a
browser, not only allow a user to see the database data, but
have full support for editing, deleting, and inserting data in
the database.
The user interface construction becomes similar, in its
capabilities, to the common Windows user interfaces, although it
is a native Web application, capable of running in multiple
browsers with no need of any plug-in or custom extension. The
reason for this openness lies in the fact that the Internet Express
technology is based on open standards, these being:
• XML and an XML DOM
• ECMAScript (the official name of the JavaScript
technology), is the only scripting language supported by
most Web browsers, which can be used to customize the
user interface, apply simple input and editing rules on the
client side, make the user interface interact with the XML
data.
• Dynamic HTML and CSS (Cascading Style Sheets) allow the
development of a modern user interface within a browser,
avoiding a tie-in of graphical elements with the HTML and
the data rules. Quite the contrary, in fact, as the various
Delphi
11
elements (HTML code, business rules, SQL server access)
are kept well separate.
As mentioned earlier the InternetExpress architecture is based
on Borland’s MIDAS 3 technology. In its complete extensions,
the architecture has 4 separate layers (see Figure 8), these being:
Figure 8: The different layers of a multi-tier Internet
Express application.
• The SQL server (any of those supported by BDE, ADO, or
native components), eventually running on a separate
computer
• A MIDAS application server, which connects to the SQL
server, applies specific business rules, and provides the data
to the clients
• A WebBroker Web server extension, which ties to the Web
server, and converts the data received by the MIDAS server
into XML and provides a suitable HTML user interface
• The Web browser, which can be either Internet Explorer or
Netscape (or other complying with the standards) and can
run on any operating system
In the case of simpler projects, the picture can actually be
simplified by merging the MIDAS server and the XML producer
components into a single application. The advantage of the
overall architecture is that you also gain the benefits of the
MIDAS infrastructure, including a proper abstraction of the
business logic, transport independence (it can run on top of
TCP/IP, HTTP, DCOM, MTS, and CORBA), and resource
pooling (to share SQL server connections).
In practice, let me guide you through the steps you’ll need to
build a simple Internet Express front end for editing a simple
database table. The starting point is again the creation of a new
Web Server Application, using the wizard. In the web module
you can add an action (see again Figure 7 and the description of
the related example) and mark this action as the default action,
by setting its Default property to True. Now you need the
following components:
• An actual data set, such as a table or query component,
connected with a database (using BDE, ADO, or another
database access technology). The simplest solution is to use
a BDE Table (from the Data Access tab of the component
palette), setting its DatabaseName and TableName
property. You can use the sample DBDEMOS alias for the
DatabaseName property, and choose any of the available
tables (from the drop-down menu of the property)
• A data set provider component (from the MIDAS tab of
the component palette), hooked with the data set (Table1 in
this case) using its DataSet property
• An XML broker component (from the InternetExpress tab
of the component palette), hooked directly with the
provider (in a “single” tier approach) using its
ProviderName property
• A Midas Page Producer component (again from the
InternetExpress tab of the component palette), connected
with the default action of the web module by setting the
Producer property of the action
At this point you can open the Midas Page Producer (by double
clicking on it), and use its special editor to prepare the HTML
form. For example, you can add a data form, add into it a data
grid (connected with the XML broker) and a navigator (hooked
to the grid using the XMLComponent property).
Delphi
12
Figure 9: The editor MidasPageProducer component
within the WebModule of our InternetExpress application.
After these steps you’ll have a complex data module. To
summarize its key options, I’m going to list the textual version of
its DFM file, an internal Delphi file that reflects the result of
visual development actions. You won’t ever need to type this
code, it is just a summary on the visual setting done in the
Object Inspector, very useful for reference and documentation
purposes. You can view your own WebModule this way by right
clicking on it and then selecting “View as Text” command.
You’ll see more code than that listed here, as I’ve extracted form
the textual definition of this DFM file only its key elements:
object WebModule1: TWebModule1
Actions = <
item
Default = True
Name = ‘WebActionItem1’
PathInfo = ‘/MidasPageProducer1’
Producer = MidasPageProducer1
end>
object Table1: TTable
Active = True
DatabaseName = ‘DBDEMOS’
TableName = ‘country.db’
end
object DataSetProvider1:
TDataSetProvider
DataSet = Table1
end
object XMLBroker1: TXMLBroker
ProviderName = ‘DataSetProvider1’
WebDispatch.PathInfo =
‘XMLBroker1’
end
object MidasPageProducer1:
TMidasPageProducer
HTMLDoc.Strings = (…)
IncludePathURL = ‘/include/’
object DataForm1: TDataForm
object DataGrid1: TDataGrid
XMLBroker = XMLBroker1
end
object DataNavigator1:
TDataNavigator
XMLComponent = DataGrid1
end
end
end
end
Notice you have to remember to set the IncludePathUrl
property of the Midas Page Producer to a URL referring to a
directory where the browser can find the required JavaScript
files. Otherwise the browser will show an error message, and no
data.
Figure 10: The InternetExpress application we have just
built inside a browser (in this case Microsoft Internet
Explorer)
This is all! At this point you’ll have a complete application,
allowing a user not only to see the data inside a browser (any
browser!) but also to edit the data and send it back to the server,
to be posted to the database. See Figure 9 for an example. And,
again, with no coding required we’ve only chosen the basic
options, but with some study (one of the few references,
although limited on this regard, is my own book “Mastering
Delphi 5”) and effort you can build sophisticated program, with
a modern browser-based UI.
Delphi
13
In short:
• With Delphi InternetExpress architecture you can extend
MIDAS multi-tier applications with a browser-based user
interface. Relying on HTTP, XML, and ECMAScript, the
architecture is not tied to any browser or operating system,
which differs from other equally powerful solutions.
• Developing a simple front end for you business data with
InternetExpress is really a very fast and completely visual.
Even without knowing all the core technologies of the
architecture, you can still easily write fully functional and
professional-looking web sites.
Third-Party Web Server Extensions
Besides using Borland’s own InternetExpress technology, you
can use Delphi with some third party components and tools,
which support the development of HTML-based server side
applications with different approaches. There are many tools in
this category, so I’m just mentioning the most popular ones, and
not trying to offer a complete picture.
• HREF (http://www.href.com) offers the popular WebHub
framework, an advanced technology for manipulating
HTML snippets and create Web content based on database
data. WebHub is capable of handling user sessions, separate
the code development from the server side technology used,
and helps developers to move to a proper Web-centric
approach, instead of adapting existing Windows user
interfaces to the Web.
• Nevrona Design offers ND-IntraWeb
(http://www.nevrona.com/intraweb) which follows an
opposite approach: Using a series of custom user interface
components it allows you to build a user interface which
can work equally well inside a Windows program or a Web
browser.
• Marotz Delphi Group offers ASP Express
(http://www.asp-express.com) offers a set of components
designed to encapsulate and simplify the development of
Windows DNA applications. It uses ASP, MSXML, COM,
and other technologies, making it easier to combine
everything with Delphi code.
In short:
• Custom server side solutions provide ready-to-use complex
frameworks for the development of your applications with
Delphi. Some of these technologies have been successfully
used for the development of large and complex web sites.
• Similarly to the use of components wrapping server side
protocols, you can have full control of the entire software
on your web server, with no risk of others people bugs
creeping into your system.
Delphi in Action on the Internet
Delphi’s capabilities in the area of Internet and Web
development can be discussed by their technical merit, as I’ve
done in this paper, but can also be evaluated based on their
success. Delphi is used for the development of many Internetproducts,
ranging from simple shareware utilities to huge ecommerce
Web sites. Although the press is all about other
languages and environments, Delphi has found its inroads in the
Internet era, and is in widespread use right now.
Borland provides a long list of success stories (see
http://www.borland.com/about/cases and
http://www.borland.com/delphi/cases), but there are a few
worth highlighting. Among the web sites powered (at least for
the database oriented portions) by Delphi there are:
• Autobytel.com, a US on-line car dealer
• The National Trust (http://www.nationaltrust.org.uk), a
UK organisation for preserving historical buildings
• iVillage.com, the women’s network web site
• Dulux Trade Paints (http://www.dulux.com), a web site for
choosing paint colors
• CalJobs (http://www.caljobs.ca.gov), the State of California
Internet system for linking employer job listings and job
seeker resumes.
• Travel.World.Net, a complete travel services management
system by Australian World.net.
Delphi
14
Speaking of Internet utility programs, almost half of the
Internet-related shareware programs on the market are built with
Delphi. Some worth mentioning, taken from different categories,
are:
• The powerful email manager The Bat!
(http://www.ritlabs.com) and the freeware mail client Mail
Warrior (http://pages.infinit.net/kaufman), top rated in
many software web sites
• The acclaimed HTML editor HomeSite
(http://www.allaire.com/homesite)
• The MERAK Mail Server (http://www.icewarp.com)
• Two of the most popular IRC clients, Pirch
(http://www.pirchat.com) and Virc
(http://www.megalith.co.uk/virc/)
There are also newsgroup readers, FTP front ends, XML editors,
chat programs, and applications for the client and the server side
almost any possible Internet protocol.
Another area of success in Delphi development is the creation of
high-quality ASP components. Among the most popular ASP
add-ons mentioned on Microsoft’s web site
(http://msdn.microsoft.com/workshop/server/components/ca
talog.asp) there are quite a few written in Delphi, including the
ASP components written by Dimac (http://www.dimac.net) and
including the popular JMail component, described as “the
leading SMTP-component for ASP-coders”.
You can find a rather complete (albeit unofficial) list of Internet
applications and Web sites powered by Delphi on the “Built with
Delphi” area of the Baltic Solution web site
(http://www.balticsolutions.com/bwd).
Conclusion: The Delphi Advantage
After this long detailed paper it is not easy to summarize in only
a few words why you should use Delphi as a core Web
development tool, within your organization. I can certainly say
that Delphi delivers fast-performance applications built with a
rapid development environment for Windows and the Web. It
has optimal Client/Server support and the ability to write goodquality
object-oriented code, both for the building of a complex
application structure and also to delve deep into low-level
programming tasks.
A great tool for the entire Internet needs of any organization.
And a tool you can use today on the Windows platform and get
ready to extend to the Linux operating system with a visual and
high-performance development environment, the ideal solution
for all those who like programming “The Delphi Way”.

Published in: on 24 January 2010 at 5:51 pm  Leave a Comment  
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