Enterprise J2ME Developing Mobile Java Applications [Electronic resources]

Michael Juntao Yuan

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8.5 Commercial Email and PIM Suites

Commercial mobile email and PIM solutions and libraries are also available from several J2ME vendors.

File Systems on Small Devices

One of the limitations of the MIDP is that it supports only RMS stores but not hierarchical file systems for local data storage. The reason is that many phone devices simply do not have file systems. This "lowest common denominator" approach is necessary to ensure the portability of MIDP applications. However, it has frustrated developers who want more power and advanced features. The PDA OP brings file systems to supported devices.

8.5.1 The Espial Suite

Espial is an industry leader of embedded Java solutions. On the client side, it has two productivity suites.

Espial Suite for Devices runs on the CDC or PersonalJava platform. It contains four applications and libraries: Espial Escape, a Java Internet browser; Espial Ebox, a powerful email client; Espial Espresso, a lightweight UI library; and Espial DeviceTop, a graphical OSGi (see Chapter 3) client. Escape, Ebox, and DeviceTop all expose their programming APIs in SDKs. Developers can incorporate an HTML-rendering engine, an email client, or an OSGi manager in custom applications using Espial Suite for Devices SDK.

Espial Suite for Wireless runs on the CLDC/MIDP platform. It contains three small footprint applications: Espial Escape, an 87KB Web browser; Espial Ebox, a 19KB email client; and Espial Assistant, a 42KB contact, task, and calendar manager. Again, all three applications make their programming APIs available through SDKs.

Please visit the Espial Web site (see "Resources") for software, documentation, and sample code on how to use the SDKs.

8.5.2 The ReqWireless Suite

ReqWireless offers three J2ME/MIDP libraries: The 37KB ReqWirelessWeb library provides APIs to fetch, manipulate, and display HTML/Word/PDF Web content using the LCDUI; the 43KB ReqWirelessEmail library provides APIs to access email messages and a variety of MIME attachments (including GIF, JPEG, TIFF images, ZIP archives, Word and PDF documents); the ReqWirelessDB is an MIDP JDBC driver library. ReqWireless also has three applications: WebViewer, WebViewerLite, and EmailViewer, to showcase the capability of their libraries.

The ReqWireless libraries employ a proxy-based architecture. Each library consists of a J2ME client component and a proxy server component that runs in any Java application server. The proxy handles network protocols, conducts round trips, parses the content and then feeds the display content to the client via an optimized proprietary protocol. The proxy architecture is of great importance for mobile applications. In the next section, we will have a look at more sophisticated corporate portals for mobile email and PIM applications.