DLXS software consists of two components. The first component is the DLXS middleware, available as a free Open Source resource. The second component is the XPAT search engine, available in two versions. One version of the search engine (XPAT) is licensed and available for a fee. The other version (XPAT Lite) is freely available but has a limit on the size of the data which can be indexed. Information on the availability of each, as well as proposed enhancements, is included below. For more on DLXS and classes, please see the DLXS Prospectus.) See also the XPAT licensing contract and the DLXS Support Agreement.

DLXS Documentation
  • Up to date for the current release listed below.
  • Links to documentation for previous releases of DLXS.
  • Covers class middleware and XPAT tool set.

XPAT version 5.3.2
  • Supersedes and backward-compatible with versions 5.2.3, 5.3.0.
  • Support for both "valid" and "well-formed" XML indexing.
  • Linux (Intel) and Solaris (Sparc) binaries.
  • Unicode support.
    • Supports UTF-8 encoded data within the Basic Multilingual Plane (Plane 0).
    • Available in the licensed version of XPAT only.
  • XPAT version 5.3.8 is available on a request-only basis. It was created in 2013 to ensure its functionality on newer operating systems. Please send email to DLXS Info or contact John Weise at 734.764-8074 for further information.

XPAT Lite version 5.3.0
  • Same functionality as standard XPAT but:
    • Data size is limited to 10 meg.
    • No Unicode support.
  • Freely available. See Fee section below.
  • Download XPAT Lite 5.3.0 here

Current OAI Tools Package Open Source Releases

Current and Past DLXS Middleware Open Source Releases


An institution may choose to license XPAT (available on CDROM) or use the freely available XPAT Lite software (downloadable from this website). It may also choose to subscribe to DLXS or not.

The ongoing DLXS subscription fee entitles the subscriber to:

  • Vote on and propose DLXS development directions.
  • Receive middleware updates on CDROM.
  • On-call support via phone, email and post.

There are four possibilities.

Includes full XPAT functionality and full benefits of DLXS membership. One time XPAT license fee (1a)/(1b) + ongoing DLXS subscription fee (2a)/(2b).
Includes XPAT Lite functionality and full benefits of DLXS membership. No XPAT fee + ongoing DLXS subscription fee (2a)/(2b).
Full XPAT only
Includes full XPAT functionality without DLXS participation/support. Middleware downloads from website. One time XPAT license fee (1a)/(1b).
XPAT Lite only
XPAT Lite functionality without DLXS participation/support. Middleware and XPAT Lite downloads from website. No cost.

The ongoing DLXS subscription will be charged at a rate of $5,000 per year.
This rate is charged regardless of the number of installations of the search engine (in the case where the institution elects to license XPAT). Support is made available to a single designated representative of the institution. The rate of $5,000 per year is applied to the first representative/membership within an institution; additional memberships within a single institution are charged at the lesser rate of $3000. [2] Should a licensing institution choose to discontinue participation in the DLXS, it may continue to use XPAT and is still bound by the terms of the license for the XPAT engine. An institution that has ceased its membership in DLXS is no longer entitled to CDROM updates of middleware or support for that middleware.

The freely available DLXS XPAT Lite toolset may be downloaded from this web site. Taken together with the middleware this affords an opportunity to use DLXS software with smaller data sets (e.g., indexes are built for source files up to 10 megabytes in size). However, support for the middleware is not available under this option. We encourage your organization to become a DLXS subscriber and thereby participate in shaping and contributing resources to the continued development of DLXS.

A one-time cost of $15,000 is charged for licensing the fully functional XPAT toolset.
This entitles the subscribing institution to install XPAT on a single server (and to use an additional copy on a backup or development server). [1] Additional copies of the search engine will be available to the licensing institution at a reduced rate of $12,000.

(1a) XPAT

first instance, per single computer


(1b) XPAT

subsequent instances, per single computer


(2a) DLXS support/updates

first representative, per year


(2b) DLXS support/updates

Each additional representatives within an institution, per year




any number of instances


DLXS Middleware

Open source



[1] The University of Michigan will not implement mechanisms to police institutions, but evidence of a violation of the XPAT contract will result in suspension of the institution's license and forfeiture of XPAT. The University of Michigan is contractually compelled to enforce compliance with the terms of the XPAT license through our agreement with Open Text.

[2] For example, if a large institution wishes to install additional search engines in other parts of the organization at the lower rate, it must either use a single designated representative for all support, or it may pay fees for additional representatives and thus secure support for each of these representatives.



For more information about DLXS, please send email to DLXS Info or contact John Weise at 734.764-8074.