JSP - Java Server Pages
JSP (Java Server Pages) is a technology used to create dynamic web content by embedding Java code within HTML or XML pages. On IBM z/OS, JSPs are typically deployed and executed within a Java EE application server environment, most notably **WebSphere Application Server for z/OS**, to provide web-based user interfaces for applications that often interact with traditional mainframe data and services.
Key Characteristics
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- Server-Side Scripting: JSPs are processed on the server (e.g., WAS for z/OS) before being sent to the client's browser as standard HTML, XML, or other text-based content.
- Java-Based: They leverage the full power of the Java programming language, allowing developers to embed Java code (scriptlets, expressions, declarations) directly into the page or, preferably, use custom tags and Expression Language (EL).
- Compilation to Servlets: The first time a JSP is accessed, it is translated and compiled into a Java servlet. Subsequent requests use this compiled servlet for improved performance, managed by the application server.
- Integration with Java EE: JSPs are a core component of the Java EE specification, enabling them to utilize other Java EE services like Enterprise JavaBeans (EJBs), JDBC for database access, and JNDI for resource lookups, all available within the z/OS Java EE environment.
- Deployment on z/OS UNIX: JSP applications, packaged within
WAR(Web Archive) orEAR(Enterprise Archive) files, are deployed to WebSphere Application Server for z/OS, which runs natively within the z/OS UNIX System Services (z/OS UNIX) environment. - Presentation Layer Focus: Best practices advocate using JSPs primarily for the presentation layer (the "View" in an MVC architecture), with business logic delegated to Java servlets or backend Java classes.
Use Cases
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- Modernizing Mainframe Applications: Creating web front-ends for existing COBOL, PL/I, or Assembler applications, allowing users to interact with mainframe data and transactions via a standard web browser.
- Enterprise Web Portals on z/OS: Developing internal or external web portals that integrate data from various mainframe sources (e.g., DB2 for z/OS, IMS DB, VSAM) and present it through a unified, dynamic web interface.
- Dynamic Reporting and Data Visualization: Generating real-time or on-demand reports and dashboards from operational data residing on the mainframe, accessible through a web interface.
- Self-Service Applications: Building web applications that enable customers or employees to perform self-service tasks (e.g., account inquiries, transaction submissions) that interact directly with backend mainframe systems.
Related Concepts
On z/OS, JSPs are intrinsically linked to WebSphere Application Server for z/OS (WAS for z/OS), which provides the runtime environment for Java EE applications, including JSPs and servlets. They often interact with traditional mainframe data sources like DB2 for z/OS or IMS DB via JDBC or JCA connectors. For transaction processing, JSPs can invoke CICS or IMS TM programs using technologies like CICS Transaction Gateway (CTG) or IMS Connect, bridging modern web interfaces with established mainframe transaction systems. The underlying execution environment for WAS and Java applications is z/OS UNIX System Services.