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1 APACHE 2.x ROADMAP
2 ==================
3 Last modified at [$Date$]
6 WORKS IN PROGRESS
7 -----------------
9 * Source code should follow style guidelines.
10 OK, we all agree pretty code is good. Probably best to clean this
11 up by hand immediately upon branching a 2.1 tree.
12 Status: Justin volunteers to hand-edit the entire source tree ;)
14 Justin says:
15 Recall when the release plan for 2.0 was written:
16 Absolute Enforcement of an "Apache Style" for code.
17 Watch this slip into 3.0.
19 David says:
20 The style guide needs to be reviewed before this can be done.
21 http://httpd.apache.org/dev/styleguide.html
22 The current file is dated April 20th 1998!
24 OtherBill offers:
25 It's survived since '98 because it's welldone :-) Suggest we
26 simply follow whatever is documented in styleguide.html as we
27 branch the next tree. Really sort of straightforward, if you
28 dislike a bit within that doc, bring it up on the dev@httpd
29 list prior to the next branch.
31 So Bill sums up ... let's get the code cleaned up in CVS head.
32 Remember, it just takes cvs diff -b (that is, --ignore-space-change)
33 to see the code changes and ignore that cruft. Get editing Justin :)
35 * Replace stat [deferred open] with open/fstat in directory_walk.
36 Justin, Ian, OtherBill all interested in this. Implies setting up
37 the apr_file_t member in request_rec, and having all modules use
38 that file, and allow the cleanup to close it [if it isn't a shared,
39 cached file handle.]
41 * The Async Apache Server implemented in terms of APR.
42 [Bill Stoddard's pet project.]
43 Message-ID: <008301c17d42$9b446970$01000100@sashimi> (dev@apr)
45 OtherBill notes that this can proceed in two parts...
47 Async accept, setup, and tear-down of the request
48 e.g. dealing with the incoming request headers, prior to
49 dispatching the request to a thread for processing.
50 This doesn't need to wait for a 2.x/3.0 bump.
52 Async delegation of the entire request processing chain
53 Too many handlers use stack storage and presume it is
54 available for the life of the request, so a complete
55 async implementation would need to happen 3.0 release.
57 Brian notes that async writes will provide a bigger
58 scalability win than async reads for most servers.
59 We may want to try a hybrid sync-read/async-write MPM
60 as a next step. This should be relatively easy to
61 build: start with the current worker or leader/followers
62 model, but hand off each response brigade to a "completion
63 thread" that multiplexes writes on many connections, so
64 that the worker thread doesn't have to wait around for
65 the sendfile to complete.
68 MAKING APACHE REPOSITORY-AGNOSTIC
69 (or: remove knowledge of the filesystem)
71 [ 2002/10/01: discussion in progress on items below; this isn't
72 planned yet ]
74 * dav_resource concept for an HTTP resource ("ap_resource")
76 * r->filename, r->canonical_filename, r->finfo need to
77 disappear. All users need to use new APIs on the ap_resource
78 object.
80 (backwards compat: today, when this occurs with mod_dav and a
81 custom backend, the above items refer to the topmost directory
82 mapped by a location; e.g. docroot)
84 Need to preserve a 'filename'-like string for mime-by-name
85 sorts of operations. But this only needs to be the name itself
86 and not a full path.
88 Justin: Can we leverage the path info, or do we not trust the
89 user?
91 gstein: well, it isn't the "path info", but the actual URI of
92 the resource. And of course we trust the user... that is
93 the resource they requested.
95 dav_resource->uri is the field you want. path_info might
96 still exist, but that portion might be related to the
97 CGI concept of "path translated" or some other further
98 resolution.
100 To continue, I would suggest that "path translated" and
101 having *any* path info is Badness. It means that you did
102 not fully resolve a resource for the given URI. The
103 "abs_path" in a URI identifies a resource, and that
104 should get fully resolved. None of this "resolve to
105 <here> and then we have a magical second resolution
106 (inside the CGI script)" or somesuch.
108 Justin: Well, let's consider mod_mbox for a second. It is sort of
109 a virtual filesystem in its own right - as it introduces
110 it's own notion of a URI space, but it is intrinsically
111 tied to the filesystem to do the lookups. But, for the
112 portion that isn't resolved on the file system, it has
113 its own addressing scheme. Do we need the ability to
114 layer resolution?
116 * The translate_name hook goes away
118 Wrowe altogether disagrees. translate_name today even operates
119 on URIs ... this mechansim needs to be preserved.
121 * The doc for map_to_storage is totally opaque to me. It has
122 something to do with filesystems, but it also talks about
123 security and per_dir_config and other stuff. I presume something
124 needs to happen there -- at least better doc.
126 Wrowe agrees and will write it up.
128 * The directory_walk concept disappears. All configuration is
129 tagged to Locations. The "mod_filesystem" module might have some
130 internal concept of the same config appearing in multiple
131 places, but that is handled internally rather than by Apache
132 core.
134 Wrowe suggests this is wrong, instead it's private to filesystem
135 requests, and is already invoked from map_to_storage, not the core
136 handler. <Directory > and <Files > blocks are preserved as-is,
137 but <Directory > sections become specific to the filesystem handler
138 alone. Because alternate filesystem schemes could be loaded, this
139 should be exposed, from the core, for other file-based stores to
140 share. Consider an archive store where the layers become
141 <Directory path> -> <Archive store> -> <File name>
143 Justin: How do we map Directory entries to Locations?
145 * The "Location tree" is an in-memory representation of the URL
146 namespace. Nodes of the tree have configuration specific to that
147 location in the namespace.
149 Something like:
151 typedef struct {
152 const char *name; /* name of this node relative to parent */
154 struct ap_conf_vector_t *locn_config;
156 apr_hash_t *children; /* NULL if no child configs */
157 } ap_locn_node;
159 The following config:
161 <Location /server-status>
162 SetHandler server-status
163 Order deny,allow
164 Deny from all
165 Allow from 127.0.0.1
166 </Location>
168 Creates a node with name=="server_status", and the node is a
169 child of the "/" node. (hmm. node->name is redundant with the
170 hash key; maybe drop node->name)
172 In the config vector, mod_access has stored its Order, Deny, and
173 Allow configs. mod_core has stored the SetHandler.
175 During the Location walk, we merge the config vectors normally.
177 Note that an Alias simply associates a filesystem path (in
178 mod_filesystem) with that Location in the tree. Merging
179 continues with child locations, but a merge is never done
180 through filesystem locations. Config on a specific subdir needs
181 to be mapped back into the corresponding point in the Location
182 tree for proper merging.
184 * Config is parsed into a tree, as we did for the 2.0 timeframe,
185 but that tree is just a representation of the config (for
186 multiple runs and for in-memory manipulation and usage). It is
187 unrelated to the "Location tree".
189 * Calls to apr_file_io functions generally need to be replaced
190 with operations against the ap_resource. For example, rather
191 than calling apr_dir_open/read/close(), a caller uses
192 resource->repos->get_children() or somesuch.
194 Note that things like mod_dir, mod_autoindex, and mod_negotation
195 need to be converted to use these mechanisms so that their
196 functions will work on logical repositories rather than just
197 filesystems.
199 * How do we handle CGI scripts? Especially when the resource may
200 not be backed by a file? Ideally, we should be able to come up
201 with some mechanism to allow CGIs to work in a
202 repository-independent manner.
204 - Writing the virtual data as a file and then executing it?
205 - Can a shell be executed in a streamy manner? (Portably?)
206 - Have an 'execute_resource' hook/func that allows the
207 repository to choose its manner - be it exec() or whatever.
208 - Won't this approach lead to duplication of code? Helper fns?
210 gstein: PHP, Perl, and Python scripts are nominally executed by
211 a filter inserted by mod_php/perl/python. I'd suggest
212 that shell/batch scripts are similar.
214 But to ask further: what if it is an executable
215 *program* rather than just a script? Do we yank that out
216 of the repository, drop it onto the filesystem, and run
217 it? eeewwwww...
219 I'll vote -0.9 for CGIs as a filter. Keep 'em handlers.
221 Justin: So, do we give up executing CGIs from virtual repositories?
222 That seems like a sad tradeoff to make. I'd like to have
223 my CGI scripts under DAV (SVN) control.
225 * How do we handle overlaying of Location and Directory entries?
226 Right now, we have a problem when /cgi-bin/ is ScriptAlias'd and
227 mod_dav has control over /. Some people believe that /cgi-bin/
228 shouldn't be under DAV control, while others do believe it
229 should be. What's the right strategy?