Java-Based MiddlewareIT 490

Stan Senesy

IT Program

NJIT

Java-Based Middleware

• Categories– Database oriented

• The most mature element of Java-based integration. Includes the JDBC specification

– Interprocess• Remote Method Invocation (RMI). Analogous to RPC

without many of the problems associated with RPC

– Message Oriented• Java Message Service (JMS) is an application framework

that provides an API to allow message level connectivity between JMS compatible systems.

Java-Based Middleware

• Categories– Application Hosting

• Using an application server allows a Java app to serve as an entry point to centralized resources.

– Connectivity• Java Connector Architecture (JCA) provides a

standardized interface for integrating Java2 Enterprise Edition (J2EE) applications amongst Enterprise Information Systems (EIS)

Java-Based Middleware

• J2EE– J2EE provides XML support through the Java API for

XML Processing (JAXP). This gives the capability to verify, create, access and manipulate XML documents directly from within Java

– JAXP specifications include:• Java API for XML Messaging (JAXM) which allows

transmission and reception of SOAP messages• Java API for XML Registries (JAXR) provides a uniform

standard for interacting with XML registries such as UDDI or ebXML

• Java API for XML-based RPC (JAX-RPC) gives developers access to a Java based RPC library based on the SOAP specifications

Java-Based Middleware

• Transactional J2EE– Java transactions are supported through the used of

the Java Transaction API (JTA).– JTA enables high-level transaction processing in a

distributed environment

• Messaging J2EE– Java Messaging Service (JMS) is a growing

middleware standard that has attracted a wide variety of existing middleware vendors

Java-Based Middleware

• Distributed Application J2EE– RMI provides a limited capability to interact with other

distributed object middlewares such as CORBA– The RMI-IIOP extensions provide an addition to the

Java RMI that allows much greater interaction and integration with CORBA ORBs.

– RMI-IIOP allows developers to connect the two middleware standards together natively, with no transactional binding needing to be implemented

Integration ServersIT 490

Stan Senesy

IT Program

NJIT

Integration Servers

• “Integration servers broker information between on or more target entities with greater ease than traditional middleware models”

• Services that are provided by integration servers include:– Transformation– Intelligent Routing– Rules Processing– Message warehousing– Flow Control– Respository services– Directory services– Management– APIs and adapters

Integration Servers

• Most middleware solutions that we’ve explored so far only deal with portions of the middleware problem.

• Functions such as routing, data format and flow control are not part of a typical middleware package

• Integration servers help this problem by providing a standardized set of services that may be applied across a number of differing middleware domains

Integration Servers

• Integration servers provide a number of differing communications models, including:– One-to-one– One-to-many– Many-to-many– Any-to-any

Integration Servers

• In evaluating the applicability of an integration server, we need to take the following steps:– Evaluate the systems to be integrated. APIs that are

available should be indentified– Use existing APIs to serve as entry points into existing

applications (preventing a rewrite)– Whenever possible, use an adapter to insulate both

the target application and the integration server

Integration Servers

• Let’s look at some integration server services more in depth:– Transformation Layer

• We need to provide a standardized data representation for all systems to be integrated. The functions here include pattern matching, parsing, etc.

– Schema Conversion• Database schema’s must also be compatible (data

federation). This layer is responsible for the conversion to/from a common schema

Integration Servers

– Data Conversion• In addition to changes to the schema, we might need to

make changes to the physical data structure as well.

– Intelligent Routing• Messages need to be routed to the server that is best

available to process them. Often, only the integration server itself can make that determination

– Rules Processing• Data constraints might require knowledge from separate

systems to determine the applicability of rulesets

Integration Servers

– Message Warehousing• It may become necessary to retrieve information for a

period of time. Warehousing provides a persistent storage location for that data

– Repository Services• Central location of information about source and target

applications (metadata, etc)

– User Interface• Common location for the serving of a GUI that allows

access to the interfaced systems

Integration Servers

– Directory Services• Allows integrated applications to intelligently locate any

data on the network. Examples include DNS, Netware, Active Directory, etc.

– Management• System management of the various applications that are

integrated. Current management tools include elements that utilize SNMP.

– Adapters• A common wrapper that allows easier integration than

rewriting an application from scratch.

Integration Servers

• Topologies– Hub-spoke– Multihub– Federated