The Geospatial Data Abstraction Library (GDAL) is a unifying C/C++ API for accessing raster geospatial data, and currently includes formats like GeoTIFF, Erdas Imagine, Arc/Info Binary, CEOS, DTED, GXF, and SDTS. It is intended to provide efficient access, suitable for use in viewer applications, and also attempts to preserve coordinate systems and metadata. Python, C, and C++ interfaces are available.
Libxml2 is the XML C library developed for the Gnome project. The library code is portable (to Linux, Unix, Windows, embedded systems, etc.) and modular; most of the extensions can be compiled out. Libxml2 implements a number of existing standards related to markup languages, including the XML standard, Namespaces in XML, XML Base, Relax NG, RFC 2396, XPath, XPointer, HTML4, XInclude, SGML Catalogs, and XML Catalogs. In most cases, libxml tries to implement the specifications in a relatively strict way. To some extent, it provides support for the following specifications, but doesn't claim to implement them: DOM, FTP client, HTTP client, and SAX2. Support for W3C XML Schemas is in progress. It includes xmllint, a command line XML validator.
MapServer is a CGI based Web mapping application development tool. It processes user defined configuration files and templates to allow for a wide variety of applications to be developed, including interactive mapping, and spatial query definition and processing. It supports several data formats. Key features include scale dependent map rendering, automatic scalebar and legend building, feature labeling with collision avoidance, logical and thematic classifications, and on-the-fly projection of raster and vector data. The application can also access other WMS servers as a cascading map server.
Pmw is a toolkit for building high-level compound widgets in Python using the Tkinter module. It consists of a set of base classes and a library of flexible and extensible megawidgets built on this foundation. These megawidgets include notebooks, comboboxes, selection widgets, paned widgets, scrolled widgets and dialog windows.
Twisted is an event-based framework for Internet applications. It includes a Web server, an SMTP/POP3 server, a telnet server, an SSH server, an IRC server, a DNS server, a generic client/server pair for remote object access (Perspective Broker), and APIs for creating new protocols. It supports integration with GTK+, GTK+ 2, Qt, Tkinter, wxPython, Mac OS X (PyObjC) and Win32 event loops. It also supports TCP, SSL and TLS, UDP, Unix sockets, multicast, and serial ports. Supported protocols include HTTP, FTP, SMTP, POP3, IMAP, TOC, OSCAR (AIM and ICQ), SSH, DNS, IRC, NNTP, Jabber, SOCKSv4, Telnet, SIP (for VoIP), and XML-RPC and SOAP using external packages. Most protocols are supported as both servers and clients.
Libxslt is a C library for GNOME which allows developers to work with XSLT. It is based on libxml for XML parsing, tree manipulation, and XPath support. Also included is 'xsltproc', a command line XSLT processor. The library is written in plain C, making as few assumptions as possible, and sticking closely to ANSI C/POSIX for easy embedding. It should work on Linux, Unix, and Windows. Though not designed primarily with performances in mind, libxslt seems to be a relatively fast processor. It also include full support for the EXSLT set of extension functions as well as some common extensions present in other XSLT engines.