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PRODUCT SPOTLIGHT
Akamai teams with WebSphere to offer global reach, and high performance
for application users. Enterprises are
on-demand edge platform not limited to serving static content
from edge networks; several edge net-
works offer enhanced services. One
At the Edge
such capability is Edge Side Includes
(ESI), which is specifically designed
for dynamic content assembly.
In order to extend the enterprise
J2EE programming platform to the edge
BY JAY PARIKH network, IBM and Akamai have inte-
grated and deployed WebSphere
As more enterprises move their business to or enable their business on the Internet, Application Server (WAS) version 5.0
onto the edge servers. Enterprises can
Web applications have come into widespread use in many enterprise application infra- execute J2EE Web tier applications in an
on-demand WebSphere environment,
structures. The infrastructure to deliver these Web applications typically includes a known as Akamai EdgeComputing
powered by WebSphere, and consume
wide range of technologies such as load balancers, HTTP Web servers, caching Internet computing resources on a pay-
per-use basis.
servers, messaging systems, transaction-processing monitors, application servers, and This widely distributed application
ABOUT THE AUTHOR environment, shown in Figure 2, con-
Jay Parikh is director databases. A typical enterprise application infrastructure is shown in Figure 1. sists of an end user typically using a
of Engineering for browser; the enterprise (origin) run-
s performance and geographic into centralized enterprise applica- ning business logic, legacy systems,
A
Akamai’s globally dis-
tributed computing reach requirements expand, it tion platforms, and generally offer and databases; and the edge servers
service, Edge- becomes increasingly more diffi- enterprises improved fault tolerance running an embeddable WAS server
Computing. He drives cult to scale the Web site infrastructure. and better scalability, through the use that supports the J2EE Web applica-
product direction and IT managers must continually evaluate of intelligent scheduling and load bal- tion programming model.
provides coordination capacity plans to keep pace with the ancing of application workloads.
and continuity in expected peak demand, and planning However, for many of today’s Web Developing Applications
Engineering and must consider events such as market- applications, end users are inherently for an Edge Platform
across other organiza- ing promotions, news events, and other spread across the Internet. The development model remains
tions at Akamai. In events that inevitably create more plan- Congestion and failures in this end- standard J2EE for edge applications
addition to ning uncertainty. Errors in planning can user environment are common and and does not require the use of any
EdgeComputing, Jay result in overloads that can crash sites because of this, centralized enterprise proprietary APIs; it is the deployment
has supported other or cause unacceptably slow response applications can become unreliable model that changes. If your applica-
Akamai customer-fac- times, leading to lost revenue. and their performance can become tions generally follow J2EE component
ing services, including Pre-provisioning extra capacity as unpredictable. programming best practices, adapting
Akamai’s flagship insurance against overload is financially One solution for enterprises is to the existing application for the edge
content delivery ser- unacceptable for most enterprises. Ideally, use a distributed application delivery will be easier. Akamai’s edge applica-
vice, EdgeSuite; Edge enterprises want the needed resources platform at the edge of the Internet to tion platform extends the WebSphere
Side Includes (ESI), a when – and only when – they are needed; ensure optimal application perfor- application programming platform to
markup language for they do not want to buy extra resources mance and reliability. Akamai is one enable the execution of J2EE Web tier
dynamic assembly that sit idle when they are not needed. example of an on-demand edge appli- application components – JSPs,
and delivery of Web “On-demand” computing provides better cation platform. Deployed at the servlets, tag libraries, and JavaBeans.
applications at the utilization of computing resources and “edge” of the network – close to user Development for an edge applica-
edge; and FirstPoint, represents a model in which they are access points – it consists of nearly tion platform still relies on standard
Akamai’s global load- brought into service as needed. 15,000 servers in over 1,100 networks J2EE development tools and best prac-
balancing service. around the world. Enterprises can tices in developing applications, but
On-Demand deploy applications to this distributed you must architect your edge-enabled
E-MAIL Application Platforms platform in order to avoid service bot- application as two cooperating sub-
jay@akamai.com Today, on-demand computing tlenecks and failures, and at the same applications: an edge-side application
technologies have been integrated time provide on-demand scalability, and an enterprise-side application.
32 www.SYS-CON.com/WebSphere J A N U A R Y 2 0 0 4
Presentation Components faces. A session bean facade can be responses from the enterprise can
on the Edge used to expose the necessary business be cached on the edge, so content
The presentation components are logic as a Web service to the edge or data objects can be persisted on
the most common application com- application. The edge application the edge across user requests to
ponents to deploy to the edge. These makes a Web service call back to the further reduce the load on the
components access enterprise data enterprise to invoke the appropriate enterprise.
via the Java Web services client logic through a session bean facade, • JDBC: Akamai provides a Type 3
model. Typically, the Web application perhaps made visible through a JDBC driver that allows edge appli-
will be developed using a framework servlet running on the enterprise cations to tunnel JDBC queries to
based on the Model-View-Controller application servers. The edge applica- the enterprise via HTTP(S). If an
(MVC) architecture. tion can use JAX-RPC to call the Web application has already been
Jakarta’s Struts framework, an open service at the enterprise via developed using JDBC for data
source framework for building Web SOAP/HTTP(S). The edge application transaction with a database, the
applications based on the MVC pat- platform enables an edge application JDBC/HTTP mechanism will make
tern, is well suited for edge deploy- to cache the results of SOAP/HTTP(S) it easier to adapt an application for
ment. Struts provides its own requests to optimize interactions with the edge. The edge application can
Controller component via a servlet of the enterprise. still use JDBC and benefit from the
class ActionServlet. This servlet is con- In addition to Web services as a relational data form. Further, JDBC
figured by defining mappings, communication channel, other stan- query responses can be configured
ActionMappings, between the request- dard communication protocols are to be cached on the edge servers.
ed URI and the class name of an Action supported, including the following: • RMI: WebSphere applications run-
class. For the View, Struts can leverage • HTTP(S): An edge application can ning at the edge can use RMI-IIOP
JSPs and provides a very flexible and make HTTP(S) requests to the cen- tunneled over HTTP(S) to commu-
powerful set of JSP tag libraries that tral enterprise, using the nicate back to the enterprise. In
allow you to build the View portion of HttpURLConnection class, for this configuration, a servlet runs at
an MVC application without embed- example, to request content or the enterprise, intercepts the RMI
ding Java code directly into the JSP data objects. Any content frag- requests from the edge, and trans-
itself. The Model component is com- ments can be fetched and used to lates the requests into the appro-
monly represented by JavaBeans. These build the end-user response. Data priate RMI method calls to the
Model JavaBeans may be self-con- objects such as XML files can be business tier. Since RMI calls are
tained or represent facades for other fetched and then transformed set to be uncacheable in the edge
components such as JDBC or EJBs. (XSLT) or parsed (JAXP) to create application environment, it is rec-
The View and Controller compo- the end-user response. HTTP ommended that you use Web ser-
nents of a Struts application are good
candidates for distribution to the
edge network. These components
execute on the edge servers and can
interact with Model components
(EJBs) running at the enterprise.
Depending on the functionality of
your application, the extent to which
these applications can move onto the
edge application platform will vary.
The edge View and Controller compo-
nents are bundled, along with other
Java classes, into a Web application
archive (WAR) and deployed onto the FIG. 1: A TYPICAL ENTERPRISE APPLICATION INFRASTRUCTURE
edge server network.
Normally in an enterprise environ- DATA ACCESS AND Read-only access Read/write access Read/write access Write access
ment the Web tier will use RMI UPDATE FREQUENCY Low update Low update High update Low/high
(Remote Method Invocation) to com- frequency frequency frequency frequency
municate with the business tier. For
example, a servlet may use RMI-IIOP BEST PRACTICE Local DB on edge Web service from If read access can Tunnel from edge
to call an EJB. However, with J2EE (Cloudscape) edge to origin – be cached and to origin (Akamai
application components running in a cache at edge preserve consistency edge to origin
distributed WAN environment, EJBs needs, use Web service protocol optimizations)
will remain running at the enterprise from edge to origin
and are made accessible to the edge
TABLE 1: BEST PRACTICES FOR DIFFERENT DATA ACCESS REQUIREMENTS
application via Web services inter-
J A N U A R Y 2 0 0 4 www.SYS-CON.com/WebSphere 33
PRODUCT SPOTLIGHT
vices over RMI to achieve better • HttpSession: Akamai supports the query cache at the edge of the net-
performance. standard HttpSession interface on work. This will enable dynamic
the edge application platform. The caching of query results depending
Data Access on the Edge platform provides replication for on the SQL statements issued by the
Any of these HTTP-based protocols HttpSession objects across the edge application.
are useful interfaces that allow your edge server nodes. HttpSession Table 1 outlines suggested best
applications to bridge from the edge to objects are most commonly used practices given the type of data access
the enterprise, but it is still important to keep per-user state information, required by an application running on
to avoid excessive communication for but keeping them small in size is the edge.
edge-origin requests, as end-user important for performance rea-
latency and origin utilization will sons. Edge Application Examples
increase. Since there is an absolute • HTTP cookies: An edge application The following examples describe
cost for every round-trip from the edge can store some user-specific data some applications modeled to run on
to the enterprise, calls should be as in user cookies or URL tokens, but EdgeComputing and illustrate the use of
effective as possible. Requests should privacy and security concerns may WebSphere Web services and Cloudscape
be bundled, if possible, and edge prevent the use of cookies to store in distributed edge applications.
caching should be used to store data data in some situations. • Product catalog: A product catalog
and other objects across requests. • Object caching: As previously browsing application can run
The EdgeComputing platform pro- mentioned, an edge application almost entirely in the edge envi-
vides caching mechanisms to persist can make requests for data or con- ronment. Since most product cata-
application data to minimize the tent (using HTTP, Web services, or logs consist of relatively static
interaction and load on the enterprise JDBC) and these objects can be product data (not including inven-
infrastructure on a request-by-request stored in the edge node’s cache. tory information), the edge appli-
basis. cation can utilize Cloudscape as
• ServletContext: Any data that can Another powerful edge data capa- the local DBMS. The data can be
be used across users for a particu- bility employs IBM’s 100% Pure Java bundled into the edge WAR along
lar application can be stored in the Cloudscape DBMS to host infrequently with the catalog-browsing presen-
application’s ServletContext object. changing, read-only data in an edge tation components. Using this
database. In this model, applica- deployment model, it is feasible
tion data is exported into a JAR for the end user browsing interac-
file (done by the enterprise appli- tion to be handled entirely by the
cation developer), and this “data- edge application. When a user is
base in a JAR” file is bundled into ready to purchase any selected
the edge WAR file under the stan- items, the edge application tun-
dard WEB-INF/lib directory. The nels back to the enterprise for
application’s data source has a order processing.
fixed configuration correspon- • Marketing promotional contest: Say
ding to the location of the data- an enterprise wants to conduct a
base within the JAR file, and the large-scale marketing promotion to
application and corresponding give away a certain new product.
configuration are deployed in the Because of the uncertainty of the
WAR to the edge servers. number of end users (contestants),
FIG. 2: A WIDELY DISTRIBUTED APPLICATION ENVIRONMENT
By using Cloudscape on the an on-demand edge application is
edge, even the Model compo- extremely beneficial to assuring a
nents of an MVC application can be successful outcome. In this scenario,
distributed onto the edge application the application might have “random
platform. Edge applications can make selection” logic to determine if an
use of JavaBeans and JDBC as Model end user is a winner.
components with Cloudscape as the An application can be designed
DBMS to further reduce communica- and developed to execute this logic
tion to the back-end enterprise sys- on the edge, offloading the load from
tems. the enterprise. In addition, the cor-
One disadvantage of this model is porate marketing team can imple-
that any time the application data ment various controls on how long
changes, the application must be the contest runs, how many prod-
redeployed to the edge network. ucts are given out, the rate at which
Future integration development they are disbursed, or other controls.
between IBM and Akamai will enable The edge application executes the
Cloudscape to function as a database corresponding business logic entire-
FIG. 3: THE GUI EXPORT WIZARD
34 www.SYS-CON.com/WebSphere J A N U A R Y 2 0 0 4
ly on the edge and retrieves the con- Summary to attain higher levels of perfor-
trol parameters from the enterprise IBM and Akamai have developed a mance, reliability, and global reach
via Web services calls. new deployment model for J2EE Web and ultimately achieve scalability
applications. The Akamai Edge- on demand. Akamai
Application Deployment Computing powered by WebSphere EdgeComputing powered by
to the Edge Platform service allows application compo- WebSphere helps enterprises
Once designed, developed, and nents to migrate to the edge. By respond to a growing need for “on-
tested, the edge subapplication is extending the WebSphere program- demand” computing and will help
uploaded and provisioned on the ming platform to run on the Akamai many enterprises adapt their busi-
edge network. Akamai has developed edge network, enterprises are able ness functions to the edge.
a provisioning mechanism that is
available via two interfaces. The con-
ventional interface involves using a
browser-based GUI on the Akamai
enterprise portal. A second interface
involves uploading and provisioning
via SOAP-based Web services that can
be invoked programmatically.
IBM and Akamai have developed a
plug-in for WebSphere Studio
Application Developer (WSAD) in the
form of a GUI export wizard, shown in
Figure 3. This plug-in securely invokes
the EdgeComputing provisioning Web
service, and it allows developers to
deploy their applications directly from
the WSAD environment. In addition to
the upload function, the plug-in is
being enhanced to provide validation
and a simulated unit edge test envi-
ronment for the WSAD environment.
EDGE SIDE INCLUDES
Edge Side Includes (ESI) is a simple XML-like FIG. 4: THE ESI LOGIC
markup language that can be used to assemble dynamic,
personalized Web pages at the edge of the Internet. Using ESI can dramatically improve homepage.jsp
the delivery of dynamic Web content. ESI content assembly is based on the fact that a <html>
dynamic Web page is composed of several smaller individual pieces, or fragments. Each <body>
of the individual fragments can have its own cacheability properties. An edge server <h1>XYZ Homepage</h1>
processes the ESI logic and will fetch only noncacheable or expired fragments from the <!-- Assemble the following content on the edge -->
origin Web site. This model of edge page assembly can significantly reduce the load on <jsp:include page=“frag.jsp”/>
the enterprise infrastructure, as well as the amount of data that must be transported to </body>
the edge. </html>
IBM’s WebSphere Dynamic Caching Service component, as part of WebSphere
Application Server, supports the ESI specification and seamlessly integrates with Akamai’s
ESI processing capability. A page composed from a collection of servlets/JSPs (e.g., a fragment.jsp
portal-style page) can be assembled on the Akamai edge servers from either cached or <h1><b>Earnings</b></h1>
uncacheable components. JSP/servlet results can be defined as “edgeable,” using the <p>
WebSphere assembly tool or by directly editing the WebSphere Dynamic Caching Service Today XYZ company reported earnings of $1.20 a
configuration file, cachespec.xml. The ESI logic is illustrated in Figure 4. share. Revenue growth in the 4th quarter was
Upon receiving an end-user request, an Akamai server contacts the enterprise WAS strong…
server. It adds an identification HTTP request header in the form of: Surrogate-Capability:
akam="ESI/1.0". Upon processing this header, WAS returns content containing
esi:include tags instead of a fully built Web page. The embedded ESI tags are processed WAS can invoke an Akamai Web services interface to force an invalidation of any
by the Akamai edge server and the appropriate fragments are fetched (from the enter- templates or fragments. Additionally, IBM and Akamai are developing a mechanism for
prise or from cache) to build the response to the end user. WebSphere cache configuration settings defined in the enterprise’s WebSphere Dynamic
The following code snippets show how a main, or template page, homepage.jsp, Caching Service cachespec.xml to be automatically set in Akamai’s customer cache con-
could call and insert the fragment, fragment.jsp. figuration metadata.
J A N U A R Y 2 0 0 4 www.SYS-CON.com/WebSphere 35
