The ranks of Java-based programming in the SAP world are growing.
SAP Enterprise Portal is written in Java, as are parts of the SAP Exchange
Infrastructure. And from the first offering of the SAP J2EE Engine, we’ve
already seen SAP customers successfully develop their own Java applications
for this J2EE runtime environment. To make J2EE project development and
implementation faster and easier for these and future developers, SAP
is pairing the J2EE Engine with a new set of integrated, J2EE-compliant
development tools, which debut for customers with Release 6.30 of SAP
Web Application Server.
SAP NetWeaver Developer Studio is now
available in SAP Web Application Server, and
includes a J2EE Explorer
— a new Eclipse perspective1 for
all your activities regarding J2EE development
(see Figure 1).
J2EE Explorer is the entryway to all the wizards,
editors, and modeling tools SAP offers for
each layer of your J2EE application project
(see sidebar below).
||J2EE Explorer in the SAP NetWeaver Development
What Is J2EE?
J2EE is the Java standard for distributed, enterprise-scale Java
The standard specifies all aspects of a multi-tier application,
- The user interface, running predominantly in a Web browser
(the Web tier)
- The business logic (the Enterprise Java Beans tier)
- The access to underlying databases (the Java persistence tier)
J2EE also offers solutions to issues such as security (authentication,
encryption), transaction management, and connectivity to backend
or legacy systems.
SAP NetWeaver provides support for J2EE with the SAP J2EE Engine
as the runtime environment, and a new tool set for design and development
of J2EE-compliant applications.
Why SAP’s J2EE Tools?
To state the obvious: J2EE is a standard, so as long as your tools are
standard-compliant, you could conceivably use any tool for creating
J2EE-based applications that will run on any J2EE-compliant server. But
there are some very good reasons to use SAP’s own J2EE tools:
- Integration: SAP’s J2EE tool set is fully
integrated in SAP NetWeaver Developer Studio, an integral part of the
SAP NetWeaver application platform included in SAP Web Application Server
6.30. With SAP Web AS, you automatically have a range of design tools
at your fingertips, including those for J2EE development.
- Infrastructure: Like SAP’s other Eclipse perspectives
(such as Web Dynpro), the J2EE tool set is linked to SAP’s development
infrastructure, including the Design Time Repository and the Component
Build Service.2 So whether you’re designing an interface based
on Web Dynpro or J2EE, you can access the same set of development resources,
ensuring consistency and version control.
- Look and feel: Due to the architecture of SAP NetWeaver
Developer Studio, the J2EE tool set is implemented on top of SAP’s
tool framework, and offers developers a rich user interface. Anyone
on your IT team can review a J2EE application or a Web Dynpro interface
and find powerful modeling and design tools with consistent, familiar
- Runtime environment: The J2EE tool set is linked
to SAP’s J2EE runtime environment. Your applications can be immediately
deployed, tested, and debugged on the SAP J2EE Engine.
In addition, the SAP J2EE tool set provides a number of ways to significantly
accelerate development, while assuring that your work — including
user interfaces, application models, and business logic — is strictly
Quick Development Using J2EE Project Wizards
In the Developer Studio, your development efforts are organized as a list
of Eclipse projects, all visible via your Eclipse workspace. A particular
highlight of the J2EE Explorer is its wizards for developing and maintaining
J2EE applications (see Figure 2):
- Web Project: Here you maintain the Web components
of your J2EE applications.
- Web Application Project: You define the Web descriptor
and build the WAR file, which represents the Web tier of your J2EE application.
- EJB Project: This project hosts all your enterprise
java beans (EJBs) containing the business logic.
- EJB Assembly Project: From here you can build the
EJBJAR file, which represents the compiled business logic.
- Enterprise Application Project: This wizard allows
you to maintain the deployment descriptor and to build the EAR archive
that can finally be deployed to the J2EE runtime environment.
||Wizards for Faster, More Accurate J2EE Design
The Web Services Client Proxy Project wizard
is also shown in Figure 2. Web Services are
fully integrated inside the J2EE perspective.
The dependencies of different project types
are reflected in the dependencies of the underlying
Eclipse projects. Once a project is built,
Eclipse checks for required projects and will
build them if necessary.
Developing the User Interface: Java Server
Pages and Servlets
For highly sophisticated, flexible Web user interfaces that can run on
the J2EE Engine, SAP has developed its own Web user interface model, Web
Dynpro technology. 3 Web Dynpro supplements J2EE development, which uses
either servlets or JSP to implement a J2EE-standard user interface in
Servlets are dynamic
extensions of the HTTP protocol. They follow a request/response pattern:
they react to an HTTP request, such as a URL request in a browser or an
HTTP post, and produce a dynamic response, which is simply an HTML page.
A servlet must extend the HTTP protocol and therefore extend certain Java
base classes. Fortunately, with the SAP J2EE tool set, you do not need
to know these classes in detail — the servlet wizard creates a source
skeleton for you; just fill it in with your custom code.
JSP is more design-time
oriented than servlets; you can specify HTML code in a more document-centric
fashion. The HTML code is made dynamic through script code written in
Java. The script code is embedded using the standard syntax <% %>
in JSP pages. SAP’s J2EE tool set includes a JSP Editor —
see Figure 3 — with outstanding features such as:
- Syntax-based color scheme: Portions of code are
colored based on the program’s syntax. Each color represents a
different syntax element for easier editing and greater readability.
- JSP insight: From the JSP Editor, you can inspect
the JSP syntax, insert JSP tags, and incrementally add tags and other
valid options.For instance, in the JSP Editor in Figure 3, the user
can select from valid JSP tags in the dropdown list and place them in
the code — just one more step toward error-free J2EE development.
- Syntax check: After you’ve saved your code,
the SAP NetWeaver Developer Studio reads the document type definition
(DTD) from the Web that describes the JSP syntax and validates the code
automatically. The syntax tree in the outline view (bottom left) illustrates
the logical structure of your JSP page.
- Support for JSP debugging: You can set breakpoints
in the JSP page that are interpreted by the J2EE Engine at runtime.
||The JSP Editor in SAP NetWeaver Developer Studio
Compared to SAP GUI interfaces, SAP users
will find that JSP and servlets support simpler, less dynamic, and more
document-oriented (rather than transaction-oriented) interfaces. However,
JSP and servlets are meant for use in scenarios that require implementation
directly on top of J2EE-standard interfaces — for example, when
HTML design is done by external Web designers or when customers want to
port their existing J2EE applications to the SAP J2EE Engine.
For those looking ahead to J2EE interfaces
that can scale up to manage large-scale, enterprise-level transactions,
the SAP J2EE tool set is designed to develop along with future advances
Implementing the Business Logic: Enterprise
According to the J2EE standard, all business logic is encapsulated in
two types of enterprise java beans (EJBs):
beans, which represent entities that are stored in the underlying
beans, which have no counterpart on the database and therefore
encapsulate objects that are created during a session, but are not persisted
to the database later.
Both types are implemented as Java classes
that support several interfaces, defined by the J2EE standard. These interfaces
control how instances are created (home interface) and what functionality
the instances offer (remote interface).
||Session Bean in SAP NetWeaver Developer Studio
Figure 4 shows a session
bean displayed in SAP NetWeaver Developer Studio. On the left is the outline
with all business and EJB methods. The parameters for the selected method
are also shown. The bean wizard automatically creates the skeleton code
for the bean’s implementation, plus all the interfaces that the
J2EE specification requires. Then, you can easily navigate to the generated
code by selecting the Bean tab at the bottom. With the SAP J2EE tool set,
presentation of EJBs is well-structured to offer full insight into the
business layer of your J2EE application.
Graphical Representation of J2EE Applications
NetWeaver Developer Studio is developed on top of Eclipse, but the addition
of SAP Plug-ins means that all the developer tools share an SAP-specific
graphical framework for a consistent look and feel — so the icons
and connectors are familiar whether you’re modeling a J2EE or Web
Like Web Dynpro tools, the J2EE tool set
allows the creation of new development objects (in this case, new projects
or beans) right from within the model itself.
In Figure 5, a session
bean and an entity bean are displayed graphically using UML notation.
The session bean has a reference (the blue line) to the entity bean. On
the left are palettes of icons for creating new J2EE entities (such as
security roles) and linking entities (such as references between EJBs).
||Modeling Objects in the SAP NetWeaver Developer Studio
The graphical model not only depicts the
current interrelationships between different J2EE entities, it also serves
as a starting point for creating new ones. All changes made to the model
immediately appear in the outline view (shown back in Figure 3), so your
models are always in sync.
So why use SAP’s J2EE tool set? First, it is included as part of
SAP Web Application Server 6.30, where it is an integral part of NetWeaver
Developer Studio. It is designed to help you during all phases of J2EE-compliant
development, from user interface to business logic, and is integrated
with the entire SAP development infrastructure and the SAP J2EE Engine.
Aside from the integration benefits, the
rich graphical user interface helps sidestep some of the more tedious
and error-prone work that comes with J2EE design, such as maintaining
J2EE descriptors manually. Instead, you’ll work with a sophisticated,
multi-page editing framework for viewing the original XML source in a
very readable way, with tree and tabular displays and powerful modeling
tools. Wizards automatically supply consistent, J2EE-compliant code and
related services to help speed up design now and prevent time-consuming
errors from cropping up later.
Look for the SAP Web Application Server
6.30 for an opportunity to experience the new SAP J2EE tool set. For more
information on J2EE tools in the SAP NetWeaver Developer Studio, see http://service.sap.com/technology.
1 Eclipse is the open,
Java-based development environment htat SAP
is using as the platform for all its new
design-time tools for Web applications.
Design-Time Repository holds the development
objects required for Java applications,
to support version control. The Component
Build Service creates corresponding runtime
objects for implementation. See “SAP’s
Strategy Toward an Integrated, Full-Featured
Java Development Environment” in the
January-March 2003 issue of SAP Insider (www.SAPinsider.com).
Kessler joined SAP in 1992. He is the Product Manager of the
ABAP Workbench and the SAP NetWeaver Developer Studio, and is responsible
for all rollout activities. You can reach him via email at email@example.com.