Cheshire II provides a uniform interface for accessing a number of catalogs and other information sources. It does this through its implementation of the Z39.50 client/server protocol. One of its advantages is that if you don't find what you are looking for at one site, you only need to select a different host and press the Start Search button again to look for the same item(s) elsewhere. (On the downside, this feature restricts the WWW version of Cheshire II to offering only those indices known to be supported on all hosts, namely, author, title, and subject/topic.)
Less obvious, but more exciting, is the availability of ranked retrieval, which permits one to enter terms that may not exactly match those in any particular index and still retrieve highly relevant materials. This is only available at the "UCB Physical Sciences" site and the "UC Berkeley Digital Library" site, which use the Cheshire II server and search engine.
Even less obvious is the recent addition of various servers accessed via the Digital Library InfoBus (a CORBA-based digital information sharing architecture) through a Z39.50 proxy. These are indicated in the information services menu as "InfoBus access to xxx" for a variety of different services. The InfoBus Z39.50 proxy at Stanford sends back the results of searches in a simplified MARC format.
Least obvious of all is the fact that the bibliographic records housed on the Cheshire II server are in SGML format. While you will see no difference between these and the standard MARC format records provided by the other hosts on the menu, Cheshire II's use of SGML means that in the future, Cheshire searches will be able locate and deliver all sorts of documents, and not just bibliographic records.
General| Indexes | Number of Items to Retrieve | Display Formats | Null Retrievals | Known Bugs
While the number of Z39.50 complient servers is increasing rapidly, only about a dozen of these are on the list of catalogs available for searching via the Cheshire II interface. They are sites judged to be of potential interest to UC users , which also happen to be regularly accessible and well-behaved.
The list currently includes the UC Berkeley NSF/NASA/ARPA Digital Library of full-text environmental documents. The UC Berkeley Physical Sciences Libraries, including Astronomy, Mathematics and Statistics, Chemistry, Physics, Geology, etc., three Melvyl (UC-wide) catalogs, the libraries at Penn State University, Duke University, Carnegie Mellon University, UNC Chapel Hill, the Hong Kong University of Science and Technology, and ATT Bell Labs, the CIA World Factbook, the Government Information Locator Service, and four periodical indexes -- ABI Inform, the IAC Computer Database, the Expanded Academic Index, Inspec, and the National Newspaper Index -- which can only be accessed from Berkeley campus computers. (The preceding periodical index links lead to short descriptions of the databases in question and, indirectly, to detailed instructions for accessing them through MELVYL. These contain potentially useful information for the Web Cheshire user, even though specific command sequences and the like will not apply.)
When you retrieve records from one of these hosts, you have the option of clicking an author name or subject heading to get 10 more items by the same person or on the same topic. When you do, these will be retrieved from the same host as the original record set, even if you have changed hosts on the main search screen in the meantime. (If you want or need more than 10 items, click the button at the bottom of the record display to get 10 more; or return to the main screen, type in the author or subject, and ask for as many as you wish.)
General| Hosts | Number of Items to Retrieve | Display Formats | Null Retrievals | Known Bugs
Using the familiar Web browser to access diverse information resources is clearly advantageous, but it imposes limitations as well, one of which is that only those indexes supported by all hosts can appear in the lists of choices.
Cheshire's non-WWW interface does not have this problem, since it adjusts index lists whenever the user chooses a new host; but HTML forms do not currently support this sort of interaction. It is possible that incorporating Java into Web Cheshire will eliminate this limitation, but it has not yet been tried. In the meantime, hosts accessible through Web Cheshire can only be searched by author, title, and subject or topic. (See below for more information on these last two.)
While most of the index selections available on the WWW version of Cheshire II will be familiar to users of online catalogs, it is worth remembering that these are not treated in exactly the same way everywhere. For example, some treat title or subject search terms as keywords and will return any item in which those terms occur in the appropriate fields. Duke University's catalog treats them as a phrase, however. That is, a title search for endangered wetlands will only return items in which those to words occur adjacent to one another in the title. Wetlands: Endangered Habitats won't be found.
As a further example, the CIA World Fact Book will get what you want if you submit the "Algeria" as a topic, author, LC subject heading, or title; but in all but the last instance you also get data on the Cape Verde Islands, the Central African Republic, and other countries.
Topic will be the one unfamiliar index. When you submit a topic search to the UCB Astr-Math-Stat (that is, the Cheshire server itself), the search engine looks in several places for terms similar to those entered, computes the degree of match, and returns a relevance-ranked list of items. Where this kind of sophisticated searching is not supported (that is, everywhere else), but multi-index exact-match searches are, the latter is used. In the remaining cases a standard search is performed against the Library of Congress (LC) subject heading index.
Needless to say, Cheshire's judgment of relevance will not always coincide with its user's, but you should generally find some useful items among the top ranked retrievals; so topic searching "UCB Astr-Math-Stat" is a good way to begin looking for materials in an unfamiliar field of inquiry. (To get a sense of this do a topic search for "local compactness." The top ranked retrievals are clearly relevant, despite the fact that the terms local and compactness don't appear. Title and subject searches for "local compactness" in Melvyl, for example, find nothing.) Avoid topic searches that include common terms -- like "astronomy" or "algebra" -- or terms that have multiple meanings, however, as these frequently lead to disappointing results.
Most servers allow one to narrow or broaden your search by choosing to "and" or "or" search terms (by means of the buttons directly above the search entry windows). There are exceptions, however. The Hong Kong University of Science and Technology catalog permits only single-index searches.
General| Hosts | Indexes | Display Formats | Null Retrievals | Known Bugs
It is usually a good idea to request a relatively small number of items to retrieve when you begin a search. This will enable you to determine if you are on the right track, or if you should change your strategy, without waiting for hundreds of records to be transmitted from the selected host. If you ask to retrieve only 10, say, they seem to be just what you are looking for, and the search results screen says that there are 50 more, you can either get them 10 at a time by clicking the "Next" button at the bottom of the record display; go back to the main search screen, change the number to retrieve to 60, and resubmit the search; set the starting record to 11, change the number to retrieve to 20, to see records 11 thru 30; and so on. On the other hand, if the results screen says that there are 500 more, you should probably concoct a new search.
If you just want to know how many items are available at a site, you can set the number to retrieve to 0 or, equivalently, put nothing in the window at all. (Putting nothing in the starting record window, however, is considered to be a request to begin the display with record number 1.)
General| Hosts | Indexes | Number of Items to Retrieve | Null Retrievals | Known Bugs
You may want to select the short, rather than the (default) long, display format you can reduce the number of screens you need to page through to review your search results. If you are happy with the results, but want to see more information about the items, you must go back to the search screen and resubmit your search after selecting the long format. At the moment, the results of searches submitted by clicking an author or subject hot-link are available in long format only.
If you are searching one of periodical indexes, however, you may well want to use the long display format from the start, since it will include article abstracts if they are available, while the short display format will suppress them.
General| Hosts | Indexes | Number of Items to Retrieve | Display Formats | Known Bugs
It sometimes happens that you submit a search, but get nothing back. Any number of things may be the cause: The source you are checking may simply not have anything matching the description you gave. The selected host may be down temporarily and not accepting requests; it may be refusing to service your search because it contains very common words and would tie up the machinery for an unacceptably long time; or something may have gone awry with the Z39.50 exchange between the client and server. There may be a misspelling in your search request. Or you may have encountered a Cheshire bug as yet undetected by its creators.
Cheshire tries to distinguish among these and displays diagnostic messages when it can, some of which may be cryptic. Efforts are underway to clarify the diagnostic messages, to provide diagnostics where none exist, and to sort out all the error codes returned by the various servers Cheshire communicates with.
General| Hosts | Indexes | Number of Items to Retrieve | Display Formats | Null Retrievals