The DataWeb Platform
WhitepaperThis paper gives an overview of DataWeb's architecture. The design time
environment, physical architecture, and runtime architecture are explained in
detail. The paper also covers scalability considerations, and the current
feature set. This paper is intended to give a developer, systems administrator,
or technical managers an understanding of how DataWeb works.
Design Time Architecture
DataWeb allows any developer with a web browser to quickly build a web
application that incorporates custom database functionality, scripting,
membership services and security. Examples of these would be: issue-tracking web
applications, content management systems, shopping carts, and discussion boards.
Figure 1: A View file being edited in the DataWeb Builder
The DataWeb Builder is a hosted, browser based IDE for building and customizing every
aspect of a DataWeb application. There is no client code required to run the
Builder other than a web browser and an Internet connection (web applications
created with DataWeb work on all 4.0-level browsers on all operating systems. The
DataWeb Builder requires IE 5 on Windows or Macintosh, and Netscape 6.). The
Builder presents each web site in the familiar metaphor of a file system tree.
Developers can select and edit each file in the tree, as well as manage and set
options for the entire application. The following file types are supported
within a DataWeb application:
- Data tables are SQL tables that are presented as files within the
user’s application. A graphical editor is provided for editing data-table
schema and for displaying the data stored in the table. Data tables support
- Views are XHTML files that can be bound to data tables. Each view
has four modes—insert, update, details and browse—giving a developer
multiple ways of displaying data in a single page. Views understand
multi-table relationships, have full knowledge of the security and
membership model and can show and hide elements based on the users
- Script is processed by the DataWeb Server and is written in ECMA
views, in response to database events (triggers), or directly from URLs. The
object model provides server-side functionality including access to user
profiles, HTTP requests and responses, database operations, and secure
- Static Files are stored in the file tree and are served by the
DataWeb Server. Text files such as .html or .css can be edited in the
Builder, while graphic files can be stored and served but not edited.
DataWeb was designed from the beginning to be a hosted platform, with all
software running on the server. DataWeb is available in three configurations—DataWeb
Online, DataWeb Server – Standard edition, and DataWeb Server – Enterprise
edition—that share similar architecture and provide different levels of
scalability and redundancy.
The hosted version of DataWeb available on www.dataweb.com runs in a cluster
with multiple web-servers running identical copies of the DataWeb Data Engine. Each
server can service requests for any DataWeb application and additional web and
database servers can be added at any time without disruption to the operation of
the Platform. This allows all hosted sites to continue to run seamlessly even
through web server failures. Database servers support RAID and redundant
hardware to increase reliability.
The load balancer is configured to keep sessions tied to the same web server
whenever possible. Individual webs also have an affinity to a set of servers.
This helps ensure that every customer sees a consistent set of data, while
allowing the Engine to do optimistic data caching.
Figure 2: Model Physical Architecture
(Not Pictured: mail, dns and administrative servers)
DataWeb Server, Enterprise Edition
The DataWeb Server, Enterprise Edition is also a clustered solution running
multiple web servers behind a load balancer. It is designed to run inside a
corporation by in-house IT staff. Customers can determine the number of web and
database servers necessary to meet expected loads and provide desired back up
DataWeb Server, Standard Edition
The DataWeb Server, Standard Edition runs on a single web server with out a load
balancer. It lacks failover and redundancy but benefits from the inherent
scalability of DataWeb (see below). It is suitable for a departmental or lower
- Web Servers: DataWeb currently runs on IIS and Windows 2000.
- Database Servers: The database servers run Microsoft SQL server
- Load Balancers: The DataWeb data center uses F5 big IP load
- Auxiliary Servers: Mail gateways and DNS servers run Unix/Linux.
The DataWeb Data Engine is the server-side component of the Platform that handles HTTP
requests from the users of a DataWeb web application. The Engine manages
security, renders views, executes scripts, and caches results for faster
performance. The diagram below outlines how the Engine handles an HTTP request.
- All HTTP requests are checked for permissions and mapped to the
- Assuming the user has sufficient permissions, requests for static files
are handled as usual by the web server.
- Script and view files are cached in compiled form and served as requested;
a call to the file server is made if a file is needed that is not cached.
- The data layer checks security and validates queries and updates.
- The query cache checks if the query results exist in the cache, and if
updates have invalidated cached results, in which case a request is made to
the database server.
Figure 3: HTTP request path
DataWeb is designed to be a highly scalable solution, as discussed in the
Physical Architecture section above.There are several additional features that
support this goal.
- C++ Runtime: The majority of the DataWeb runtime is implemented in
C++, allowing for the highest level of optimization. There are no Java, ASP
or COM components.
- Virtual Database Support: Each DataWeb application has it’s own
custom tables and schema, but many applications can share a single physical
database. This lowers the overhead for each app and allows the back-end to
service many virtual databases efficiently. The DataWeb security layer
guarantees that users read and update tables only if they have appropriate
- Data Caching Layer: In typical web applications many queries are
repetitive, and the results of those queries change infrequently. The DataWeb
data layer caches common query results and invalidates cached results as
updates occur. The data-caching layer also includes a database connection
pool to optimize the use of database resources when SQL queries are
- View and Script Caching: Compiled views and scripts are cached on
web servers to speed request handling.
The following list gives an overview of the feature set of the DataWeb Platform.
- Secure Logon: All logons to the DataWeb system occur over SSL
connections. The logon is preserved over standard HTTP connections and
reauthorized via HTTPs at regular intervals.
- Security and individual pages: Any element of a page can be
displayed or hidden based on user permissions. In addition, elements of a
page can be made editable or non-editable based on user permissions.
- Groups and Roles: DataWeb supports sets of permissions known as “roles”.
Roles include Reader, Depositor, Author, Editor and Builder. These roles
can currently be assigned to a fixed set of groups, though the underlying
architecture supports custom groups.
- Record-level security: The Author role allows groups of users to
create records but limits their update privileges to the records they
created. For example, I might be allowed to read the company address book,
but only allowed to update my own address.
Helpful Data types and Objects
- Access Database Import/Export: The DataWeb server can “upsize”
an Access database to the DataWeb Platform. Views and navigation are created
to allow users to instantly create a web-accessible custom relational
database. Relationships between tables are preserved on both import and
- CSV Import/Export: The DataWeb Platform imports and exports standard
- XML Export: Any query can be returned as an XML dataset from a URL.
- Web Import: Given a URL, DataWeb servers can walk an existing web
application, import pages, and fix up links within the pages. This gives
users a quick start on porting web sites to DataWeb.
- Integrated FTP Server: The Platform includes a custom FTP server
that integrates with the DataWeb security model. This allows developers to
publish content to their DataWeb application from existing web development
tools such as HomeSite and Dreamweaver.
- Archive Support: DataWeb can package an entire application as a zip
file for easy archiving, maintenance and restoration.
- HTML data type: With the HTML data type, formatted text that is
entered into a field is automatically converted to HTML. A graphical HTML
editor makes it easy to format text to be stored as HTML.
- File upload data type: The file upload data type uploads a file to
a folder in your web application and stores a pointer to that file in your
- HTTP Object: The HTTP client objects offer programmatic access to
the data returned by a request to any web server. These objects make it
possible to share data between a DataWeb web application and any other web
site on the Internet.
- Web Schema Objects: Web schema objects offer programmatic access to
the structure of your web application and tables. Using script, you can
create and modify tables, fields, and indexes.
dynamic web applications using DataWeb’s extensive object model. Developers
generate custom pages based on user requests, or to programmatically
manipulate data tables.
- Object Model: The DataWeb object model includes the standard
ECMAScript core object model along with a set of objects that are useful in
a server environment. These include request and response objects, data and
file system access, and user information.
- Class Model: User-created DataWeb script files can be loaded as
classes. New classes can be added to DataWeb without changing the core
- Event Binding/Triggers: Scripts can be associated with database
events and fired on insert, update, or delete of records.
- Tag Embedding: Scripts that produce web pages or email often need
to output large bodies of text. Like ASP and JSP, the script compiler can
mix tags directly in the script for convenience of authoring.
- Webcall: Functions within script files can be marked as “public”,
“private” or “webcall”. Webcall functions can be called directly via
a URL, allowing non-browser clients to automate DataWeb applications.
- Data Regions: Data regions are areas of a page that are bound to
data. Data regions support filtering, sorting, and paging through data. Data
regions can display data in grid, insert, update or details modes. Multiple
modes allow a developer to create a single page and use it to serve
different types of uses.
- Template Pages: Template pages are an innovative way to give a
group of pages within an application a common navigation “frame” and
- Flexible Editing: The Builder has both a graphical editing tool
that allows a developer to author views through the UI, and an editable
source view, for direct editing.
- Script Integration: Script can be used anywhere within a view to
calculate and output values. In addition, script expressions can be used
within many attributes on the server, to change how a page is rendered.
- Auto Joins: Views can include data from multiple tables without
exposing SQL or the concepts of joins. Users can add related fields to the
display of any record and can also display "sub-lists" of related