RISC DISC 2/RISC_DISC_2.iso/pd_share/web/arcweb/Problems

Text File | 1995-09-18 | 15.6 KB | 341 lines

Problems
========

This file is part of ArcWeb, and acts as a troubleshooting guide for those
who have had difficulty installing, configuring and operating ArcWeb.  It
assumes that you have read 'Instruct' and 'ReadMe1st', and if the question
is about proxies, then 'WotIsProxy' as well.


Question Summary
================

Q1.  I try to run !ArcWeb or !ArcWebImg and I get a message saying:
"Find ChangeFSI before loading".

Q2.  When I try to load !ArcWeb, it says that it requires the DrawFile
module.  What is it and where do I get it?

Q2b. When I try to load !ArcWeb, it says 'nager: Sprites22'.  What on
earth does this mean?

Q3.  When I use the Open URL dialogue box and specify something like
http://www.demon.co.uk/ in the box, I get an error saying that no fetcher
is available for that URL.

Q4.  When I try to use the Open URL dialogue box to open a local file using
local: URLs, I get an error saying that no fetcher is available for that
URL.

Q5.  When I try to use the Open URL dialogue box to open a local file using
riscos: URLs, I get an error saying that no fetcher is available for that
URL.

Q6.  Sometimes when I load a page, the inlined images are not displayed

Q7.  I have heard that UniSys have been threatening to enforce a patent on
the LZ compression used in the GIF file format, as used by many WWW sites.
Does this affect ArcWeb?

Q8.  My icon bar is too full with the ArcWebImg and ArcWebLcl icons present
in addition to the main ArcWeb icon.  How can I prevent this?

Q9.  I don't have the ArcWebLcl or ArcWebImg icons on the icon bar.  How do
I get them to appear so I can change the configuration?

Q10.  How do I change fonts, colours and default options if I don't like
them?

Q11.  How do I set up !ArcWeb for use on a shared network

Q12.  I try to run ArcWeb and nothing happens/machine locks up/odd errors
appear (eg. Permission denied).

Q13.  What does icon 'x' do?

Q14.  When I follow a link to some URLs, I get a dialogue box saying that
authentication is required.  What does this mean?

Q15.  When I follow a link to some URLs, I get a dialogue box saying that a
non-default port is being used in the URL.  What does this mean?

Q16.  When I try to run !ArcWeb, I get a stack backtrace/Directory Full
errors

Q17.  Why do I get a save dialogue box when trying to read some pages, even
when the object is HTML?

Q18.  Sometimes I get 'Too Long' (or similar) error messages whilst the page
is being drawn and then none of the graphics are on the page.  Why?

Q19.  What do I do to cure 'unable to lookup host's address' errors?


Questions & Answers
===================

Q1.  I try to run !ArcWeb or !ArcWebImg and I get a message saying:
"Find ChangeFSI before loading".

A1.  ArcWebImg uses ChangeFSI as its image manipulator.  It invokes it on the
command line to transform GIFs, JPEGs and other formats into RISC OS sprite
files.  If the Filer has not seen ChangeFSI, then ArcWebImg does not know
where it will be able to find this tool.  Open a directory viewer containing
!ChangeFSI and then try to run ArcWebImg again.  If ArcWebImg was auto run
by ArcWeb, then you will have to quit ArcWeb and load it again, or open the
!WebHelper application (double-click it - no SHIFT required) and run !ArcwebImg
directly.


Q2.  When I try to load !ArcWeb, it says that it requires the DrawFile
module.  What is it and where do I get it?

A2.  The DrawFile module is a relocatable module written by Acorn which
provides SWIs for drawing Draw files (as manipulated by !Draw) on the
screen.  ArcWeb uses this module to reduce its own size (since the module
can be shared by many applications it can reduce memory requirements). You
can FTP it from from ftp.acorn.co.uk in /pub/riscos/releases/drawfile.arc
You require at least version 1.30.  The higher the version the better though.

Q2b. When I try to load !ArcWeb, it says 'nager: Sprites22'.  What on
earth does this mean?

A2b. This appears to happen when an attempt is made to load a newer version
of the DrawFile module over an already loaded version.  Kill the old module
with '*rmkill drawfile' and then try again.


Q3.  When I use the the Open URL dialogue box and specify something like
http://www.demon.co.uk/ in the box, I get an error saying that no fetcher
is available for that URL.

A3.  ArcWeb is not supplied with fetchers for remote documents.  These can be
found on the FTP server at Demon Internet in /pub/archimedes/www.  You need
to run *one* of these HTTP fetchers alongside KA9Q (!TCPIP) in order to be
able to fetch these documents.  ArcWebTCP can be used with Acorn TCP/IP, or
other stack such as Tom Hughes' FreeNet (when it is available).  In fact it
can use anything which provides the same BSD socket interface as Acorn TCP/IP.


Q4.  When I try to use the Open URL dialogue box to open a local file using
local: URLs, I get an error saying that no fetcher is available for that
URL.

A4.  This may indicate that ArcWebLcl isn't running.  ArcWebLcl is required
in order to fetch local: URLs.  If it is running, then this indicates that
some failure occurred finding the file.  This may be because:

  i) the filing system you used does not exist
 ii) the URL specified a non-existent file
iii) you did not specify the URL correctly.  Remember that all / and .
     characters after the :: in the filing system name, are transposed.

Remember that these URLs will look odd.  Examples of valid URLs:
local://ADFS::HardDisc4/$/WWW/index.html  (ADFS::HardDisc4.$.WWW.index/html)
local://SCSI::ScsiDisc7/$/Internet/me.gif (SCSI::ScsiDisc7.$.Internet.me/gif)
local://resources:/$/Apps/!Help           (resources:$.Apps.!Help)

Note in particular the strange format for local URLs on filing systems which
do not use device names (eg. resources:)


Q5.  When I try to use the Open URL dialogue box to open a local file using
riscos: URLs, I get an error saying that no fetcher is available for that
URL.

A5.  riscos: URLs were handled by earlier versions of ArcWebLcl.  This URL
naming scheme is now obsolete, superceded by local: URLs, which you must now
use.  NOTE: Running on old version of ArcwebLcl alongside the new ArcWebLcl
will not work, as support for the riscos: name system in ArcWeb itself has
been removed.  This is because separate routines were needed for resolving
relative references involving riscos: URLs, and these no longer exist.


Q6.  Sometimes when I load a page, the inlined images are not displayed

A6.  This should have been fixed in version 0.13.  Alternatively, look at
the page's menu under the Options submenu to make sure that you haven't
disabled the loading of inlined images.


Q7.  I have heard that UniSys have been threatening to enforce a patent on
the LZ compression used in the GIF file format, as used by many WWW sites.
Does this affect ArcWeb?

A7.  No.  ArcWeb does not contain any code for handling GIF format graphics
files.  It merely tests files for filetype &695 (GIF) or for starting GIF87a
or GIF89a, and pulls out the image pixel size (for imagemaps).  [GIF is a
registered trademark (and service mark) of CompuServe Inc.]


Q8.  My icon bar is too full with the ArcWebImg and ArcWebLcl icons present
in addition to the main ArcWeb icon.  How can I prevent this?

A8.  Edit the !Run file inside !ArcWebImg (hold down SHIFT whilst double
clicking on the icon in a Filer window).  Load the !Run file into !Edit (or
your favourite text editor) and add '-noiconbar' on the last line
of the file.  Save it again. Repeat for !ArcWebLcl.  Now, neither of these
helpers will ever install an icon bar icon.  You can still access the
configuration window by using the Configure menu on the ArcWeb icon bar menu.


Q9.  I don't have the ArcWebLcl or ArcWebImg icons on the icon bar.  How do
I get them to appear so I can change the configuration?

A9.  Double-click on !WebHelper and then double-click on the application you
want.  If you have edited the !Run file for each application (inside Helpers
directory) and added -noiconbar to the last line in the file, you must
remove this option.  Alternatively, to just change the configuration, use the
Configure submenu on the ArcWeb icon bar menu.


Q10.  How do I change fonts, colours and default options if I don't like
them?

A10.  There are two levels at which the changes can be made - system wide,
or user specific.  ArcWeb checks the following files for font definitions
and colour schemes in this order: 1)  <WebCache$Dir>.Choices
2) <ArcWeb$Dir>.Defaults   3) built-in defaults (you can't change these).

If !WebCache is local to your machine and not a per-user installation on a
network, then you should alter the version in the cache directory.
(Double-click SELECT on !WebCache and it will open the directory containing
Choices - edit that file).   For network usage, the user should be
able to change this choices file.   System-wide defaults can be set in the
<ArcWeb$Dir>.Defaults file.  This is a copy of the supplied file in the
cache directory.

Edit the file in order to change the fonts used.  Although there is no
restriction on how you can change the fonts, bear in mind that the italic
version of the body font should be the same size as the normal version of
the body font etc., otherwise you will get odd effects.  Colours can also be
changed.  You can set the foreground colour as three R,G,B quantities, and
if you wish you may also specify a further three values representing the
background colour hint. (See !ArcWeb.Defaults for an example).  Note that
when ArcWeb exports Draw files via its dialogue boxes, it automatically
filters the background hints out (and makes them white).


Q11.  How do I set up !ArcWeb for use on a shared network

In order to stop proliferation of ArcWeb into everyone's home directories,
ArcWeb is willing to cooperate in a network environment.  !ArcWeb may be
installed in a read-only filing system, provided that no -debug option is
set for any of the helpers (which is the state in which ArcWeb is supplied)
Users will also need to have seen a !WebCache application to which they have
exclusive use and to which they have read-write access.  Only one instance
of ArcWeb may use any !WebCache directory.

If you are connected to the Internet via a UNIX gateway, then I strongly
recommend running the CERN httpd on it and using it as a proxy HTTP server.

The system administrator may wish to edit !ArcWeb.!Run to refuse to run if
Arcweb$CacheDir is not set (as supplied, if it isn't set, it sets it to a
subdirectory of itself).  The system administrator may choose to edit the
!ArcWeb.Defaults file to change any system wide options.


Q12.  I try to run ArcWeb and nothing happens/machine locks up/odd errors
appear (eg. Permission denied).

A12.  This might be caused by !WebCache not being installed in a read/write
filing system.  Unless you have appropriate archiving software (eg. SparkFS
or ArcFS 2), you will have to extract the !WebCache application to a
writable filing system, and then double-click on the WebCache icon to
install it.

Q13.  What does icon 'x' do?

A13.  ArcWeb, ArcWebLcl and ArcWebImg all support interactive help.  Load
the Acorn !Help application and you will be given help about the buttons
under the pointer when in an ArcWeb window.  Note that in the window
displaying the page itself, the help is purely the URL which would be opened
if you were to click SELECT.

Q14.  When I follow a link to some URLs, I get a dialogue box saying that
authentication is required.  What does this mean?

A14.  To allow information providers to restrict access to certain web
pages, there is an authentication capability in the HTTP protocol.  The
authentication domain is a combination of the host name and a 'realm' (just
a keyword indicating which user/password is required).  If you do not have
a valid user name and password, then you will not be able to access the URL.
If you do, then enter them in the boxes and press RETURN (or click OK).  If
you toggle the authetication window to full size, you will see which server
is asking for authentication and in which domain.  NOTE:  Authentication
checking is performed at the *server* not the client, so you can't get
around it by hacking at ArcWebTCP.  ArcWebTCP will cache the user/password
together with the server and realm and attempt to auto-authenticate you in
future connections to that server.  This cache is destroyed when ArcWebTCP
exits.

Q15.  When I follow a link to some URLs, I get a dialogue box saying that a
non-default port is being used in the URL.  What does this mean?

Most Internet based protocols such as FTP, HTTP, Finger, SMTP, NNTP etc. are
defined as existing at a particular 'port' on a server which supports the
protocol.  eg. HTTP is usually at port 80, FTP is at port 21.  Sending
control strings of one protocol to a different server port may cause damage
at the local machine (your machine!) or at the server, or it may connect you
to undesirable (and sometimes illegal) services.  To help you recognise
these rogue URLs, you will be asked for confirmation when ArcWebTCP finds
that the default port has been overridden (except for HTTP, as it is
commonly run on port 8001, 8080 as well as 80).  It's not a foregone
conclusion that any non-standard port connection is dangerous or illegal,
but this way you at least have the option of blocking the connection.


Q16.  When I try to run !ArcWeb, I get a stack backtrace/Directory Full
errors

A16.  You must remove your old !WebCache directory before installing the
new !WebCache because the directory hierarchy underneath the !WebCache.Data
directory has changed in order to allow you over a 1000 entries in the cache
instead of limiting it to 75.  If this isn't the problem, then email me the
stack backtrace.  (Tech: you can capture the stack backtrace to a file by
adding " 2>stacktrace " to the end of the last line of !ArcWeb.!Run.  The
stack backtrace will then appear in a file called stacktrace in the current
directory.)


Q17.  Why do I get a save dialogue box when trying to read some pages, even
when the object is HTML?

A17.  If the server did not send, or the fetcher failed to parse, the special
Content-Type header returned by the server (this won't happen with KA9Q), then
ArcWeb does not know what to do with the object.  From version 0.25, there is
an option on the Options menu to attempt to 'execute' unknown objects.  There
is also a fix for an incorrect parse of Content-Type headers in A/TCP 0.21


Q18.  Sometimes I get 'Too Long' (or similar) error messages whilst the page
is being drawn and then none of the graphics are on the page.  Why?

A18.  ArcWebImg uses external programs to convert GIF and JPEG files into
RISC OS sprites.  To do this, it constructs a command line which invokes
the translator and tells it the input and output files.  When RISC OS runs
the command string through its routines, it is possible for an overflow to
occur (ie. the command ends up longer than the maximum permitted command
length).  This is when the OS generates the Too Long error.  To fix it, you
need to move the relevant programs closer to your root directory.
Specifically, !WebCache, !WebHelper, !ChangeFSI are the programs that are
concerned.  Using ..$Path variables does not seem to help, as the OS is
canonicalising the paths.


Q19.  What do I do to cure 'unable to lookup host's address' errors?

A19.  ArcWebTCP uses Adam Goodfellow's InetDB module to perform DNS
lookups (which means the conversion from machine names to addresses
such as mapping www.demon.co.uk to 193.195.1.1).  Sometimes the module
gets into an inconsistent state and refuses to resolve anything.  To
cure it you should issue two commands from the CLI prompt (press F12
to get a CLI prompt):  "*NSCache_Flush"  "*RmReinit InetDB"
If this fails to cure the problem and you are using a dialup Internet
connection, then check that you are using the SerialBuffer module.


--
Stewart Brodie
18 September 1995