IBM Tivoli Access Manager for e-business: WebSEAL Administration ...

HTTP
data
compression
WebSEAL
servers
can
be
configured
to
compress
data
that
is
transferred
over
HTTP
between
the
WebSEAL
server
and
the
client.
WebSEAL
uses
the
gzip
compression
algorithm
described
in
RFC
1952.
Gzip
is
supported
by
all
major
browsers.
HTTP
compression
in
WebSEAL
can
be
configured
based
on
MIME-type,
browser
type,
and
protected
object
policies
(POPs).
See
the
following
sections:
v
“Compression
based
on
MIME-type”
v
“Compression
based
on
user
agent
type”
on
page
81
v
“Compression
policy
in
POPs”
on
page
82
v
“Data
compression
limitation”
on
page
82
v
“Data
compression
configuration”
on
page
82
Compression
based
on
MIME-type
You
can
create
an
entry
in
the
WebSEAL
configuration
file
for
each
MIME-type
or
group
of
MIME-types
for
which
data
compression
is
needed.
The
syntax
is:
[compress-mime-types]
mime_type
=
minimum_doc_size[:compression_level]
The
mime-type
can
specify
one
particular
MIME
type
or
can
use
wildcard
characters
to
specify
a
class
of
MIME
types.
Each
mime-type
declaration
is
a
separate
entry
in
the
[compress-mime-types]
stanza.
The
wildcard
character
(*)
is
limited
to
entries
of
one
collection
of
MIME
types.
For
example,
text/*.
Any
MIME-type
not
listed
in
the
stanza
is
not
compressed.
Order
is
important.
The
first
entry
that
matches
a
returned
document
is
used
for
that
document.
The
minimum_doc_size
value
specifies
policy
regarding
what
size
of
documents
will
be
compressed.
This
value
is
an
integer.
Valid
values
are
shown
in
the
following
list:
v
-1
When
the
minimum
size
is
-1,
documents
of
the
specified
MIME-type
are
never
compressed
v
0
When
the
minimum
size
is
0,
documents
of
the
specified
MIME-type
are
always
compressed
v
Integer
greater
than
zero
When
the
minimum
size
is
greater
than
zero,
documents
of
the
specified
MIME-type
are
compressed
when
the
number
of
bytes
in
the
response
to
WebSEAL
exceeds
this
integer
value
Any
negative
number
other
than
-1
generates
an
error
message.
When
WebSEAL
receives
a
request
from
a
browser,
the
server
examines
the
content-length
field
in
the
HTTP
header
to
determine
the
size
of
the
incoming
data.
However,
not
all
HTTP
responses
contain
the
content-length
field.
When
the
content-length
field
is
not
found,
WebSEAL
compresses
the
document
unless
the
applicable
MIME-type
has
been
configured
to
never
be
compressed
(minimum_doc_size
of
-1).
80
IBM
Tivoli
Access
Manager
for
e-business:
WebSEAL
Administration
Guide