# Configuration Guide

Contents

- Command Line Configuration
- Application.config
  - General Settings
  - Path Handling
  - Caching
  - Errors
  - Logging
- AppServer.config

# Command Line Configuration

Each of these can be set in the `.config` files, but they can be overridden with the command line. Run `AppServer` with switches in the form `--ClassName.SettingName=value`, e.g. `--AppServer.Port=1`

The `value` is coerced into a Python type: if it starts with one of the characters `({["'` -- i.e., parenthesis (expression), dictionary, list, or string -- then the value with be eval'ed. If it can be turned into an integer or float, then it will be converted, otherwise it will be left as a string. Some examples:

- `1` == 1
- `127.0.0.1` == "127.0.0.1"
- `(10+2)` == 12
- `{'a': 'b'}` == {'a': 'b'}
- `{a: b}` == error
- `[1, 'c', [2, 3]]` == [1, 'c', [2, 3]]

Be careful about special characters in the shell. All the characters `() [] ' "` are special, and need to be quoted (with `\` or with single or double quotation marks).

# Application.config

`Application.config` covers not only the application, but a number of components that use it as a central point of configuration.

## General Settings

`Contexts`:

  This dictionary maps context names to the directory holding the context content. Since the default contexts all reside in WebKit, the paths are simple and relative. The context name appears as the first path component of a URL, otherwise `Contexts['default']` is used when none is specified. When creating your own application, you will add a key such as `"MyApp"` with a value such as `"/home/apps/MyApp"`. That directory will then contain content such as Main.py, SomeServlet.py, SomePage.psp, etc. `Webware/bin/MakeAppWorkDir.py` will set up a context for your use as well. Default:

      {
          'default':   'Examples',
          'Admin':     'Admin',
          'Examples':  'Examples',
          'Docs':      'Docs',
          'Testing':   'Testing',
      }

`AdminPassword`:
  The password that, combined with the `admin` id, allows access to the `AppControl` page of the `Admin` context. Set interactively when `install.py` is run. No default.
`PrintConfigAtStartUp`:
  Print the configuration to the console when AppServer starts.

## Path Handling

These configuration settings control which files are exposed to users, which files are hidden, and some of how those files get chosen.

`DirectoryFile`:
  The list of basic filenames that WebKit searches for when serving up a directory. Note that the extensions are absent since WebKit will look for a file with any appropriate extension (`.py`., `.html`, `.psp`, etc). Default `["index", "Main"]`.
`ExtensionsToIgnore`:
  This is a list of extensions that WebKit will ignore when autodetecting extensions. Note that this does not prevent WebKit from serving such a file if the extension is given explicitly in a URL. Default `['.pyc', '.pyo', '.py~', '.bak']`.
`ExtensionsToServe`:
  This is a list of extensions that WebKit will use exclusively when autodetecting extensions. Note that this does not prevent WebKit from serving such a file if it is named explicitly in a URL. If no extensions are given all extensions will be served (usually anything but `.py` and `.psp` will be served as a static file). Default: `[]`.
`UserCascadingExtensions`:
  If false, WebKit will give a `404 Not Found` result if there is more than one file that could potentially match. If true then WebKit will use the `ExtensionCascadeOrder` setting to determine which option to serve. Default: `1` (true).
`ExtensionCascadeOrder`:
  A list of extensions that WebKit will choose, in order, when files of the same basename but different extensions are available. Note that this will have no effect if the extension is given in the URL. Default: `[".psp", ".py", ".html"]`.
`FilesToHide`:
  File patters to protect from browsing. This affects all requests, and these files cannot be retrieved even when the extension is given explicitly. Default: `[".*", "*~", "*bak", "*.tmpl", "*.pyc", "*.pyo", "*.config"]`.
`FilesToServe`:
  File patterns to serve from exclusively. If the file being served for a particulary request does not match one of these patterns an `HTTP 403 Forbidden` error will be return. This affects all requests, not just requests with autodetected extensions. If set to `[]` then no restrictions are placed. Default: `[]`.
`SessionStore`:
  This setting determines which of the three session stores is used by the application: `File`, `Dynamic` or `Memory`. The `File` store always gets sessions from disk and puts them back when finished. `Memory` always keeps all sessions in memory, but will periodically back them up to disk. `Dynamic` is a good cross between the two, which pushes excessive or inactive sessions out to disk. Default: `Dynamic`.
`SessionTimeout`:
  Determines the amount of time (expressed in minutes) that passes before a user's session will timeout. When a session times out, all data associated with that session is lost. Default: `60`.
`IgnoreInvalidSession`:
  If false, then an error message will be returned to the user if the user's session has timed out or doesn't exist. If true, then servlets will be processed with no session data. Default: `1` (true).
`UseAutomaticPathSessions`:
  If true, then the app server will include the session ID in the URL by inserting a component of the form `_SID_=8098302983` into the URL, and will parse the URL to determine the session ID. This is useful for situations where you want to use sessions, but it has to work even if the users can't use cookies. If you use relative paths in your URLs, then you can ignore the presence of these sessions variables. Default: `0` (false).
`MaxDynamicMemorySessions`:
  The maximum number of dynamic memory sessions that will be retained in memory. When this number is exceeded, the least recently used, excess sessions will be pushed out to disk. This setting can be used to help control memory requirements, especially for busy sites. This is used only if the `SessionStore` is set to `Dynamic`. Default: `10000`.
`DynamicSessionTimeout`:
  The number of minutes of inactivity after which a session is pushed out to disk. This setting can be used to help control memory requirements, especially for busy sites. This is used only if the `SessionStore` is set to `Dynamic`. Default: `15`.
`SessionPrefix`:

  This setting can be used to prefix the session IDs with a string. Possible values are `None` (don't use a prefix), `"hostname"` (use the hostname as the prefix), or any other string (use that string as the prefix). You can use this for load balancing, where each Webware server uses a different prefix. You can then use mod_rewrite or other software for load-balancing to redirect each user back to the computer they first accessed. This way the backend servers do not have to share session data. Default: `None`. @@ ib: need a better mod_rewrite link.

`ExtraPathInfo`:
  When enabled, this setting allows a servlet to be followed by additional path components which are accessible via HTTPRequest's `extraURLPath()`. For subclassers of `Page`, this would be `self.request().extraURLPath()`. Default: `0` (false).
`UnknownFileTypes`:

  This setting controls the manner in which WebKit serves "unknown extensions" such as .html, .gif, .jpeg, etc. The default settings specify that the servlet matching the file be cached in memory, that the contents of the file be cached in memory and that the file timestamp to be checked on every request. This works well for most sites.

  If your site has a large amount of static files being served via WebKit, you should consider changing `"CacheContent"` to 0. If you are confident that your static files do not get updated while the app server is live, then you might consider changing `"CheckDate"` to `0` for (slightly) better performance. If you are concerned about performance, use mod_rewrite to avoid accessing WebKit for static content. @@ ib: link to mod_rewrite

  The `Technique` setting can be switch to `"redirectSansAdapter"`, but this is an experimental setting with some known problems. Default:

      {
          'ReuseServlets': 1,

          # Technique choices:
          # serveContent, redirectSansAdapter
          'Technique': 'serveContent',

          # If serving content:
          'CacheContent': 1,  # set to 0 to reduce memory use
          'CheckDate':    1,
      }

## Caching

`CacheServletClasses`:
  When set to zero, the AppServer will not cache the classes that are loaded for servlets. This is for development and debugging. You usually do not need this, as servlet modules are reloaded if the file is changed. Default `1` (true/caching on).
`CacheServletInstances`:
  When set to zero, the app server will not cache the instances that are created for servlets. This is for development and debugging. You usually do not need this, as servlet modules are reloaded and cached instances purged when the servlet file changes. Default `1` (true/caching on).
`ClearPSPCacheOnStart`:
  When set to zero, the app server will allow PSP instances to persist from one AppServer run to the next. If you have PSPs that take a long time to compile, this can give a speedup. Default: `1` (true/caching does not persist)

## Errors

`ShowDebugInfoOnErrors`:
  If true, then uncaught exceptions will not only display a message for the user, but debugging information for the developer as well. This includes the traceback, HTTP headers, form fields, environment and process ids. You will most likely want to turn this off when deploying the site for users. Default `1`.
`IncludeFancyTraceback`:

  If true, then display a fancy, detailed traceback at the end of the error page. It will include the values of local variables in the traceback. This makes use of a modified version of `cgitb.py` which is included with Webware. The original version was written by Ka-Ping Yee. Default `0` (off).

`FancyTracebackContext`:
  The number of lines of source code context to show if IncludeFancyTraceback is turned on. Default: `5`.
`UserErrorMessage`:
  This is the error message that is displayed to the user when an uncaught exception escapes a servlet. Default: `"The site is having technical difficulties with this page. An error has been logged, and the problem will be fixed as soon as possible. Sorry!"`
`ErrorLogFilename`:
  The name of the file where exceptions are logged. Each entry contains the date and time, filename, pathname, exception name and data, and the HTML error message filename (assuming there is one). Default: `Logs/Errors.csv`.
`SaveErrorMessages`:
  If true, then errors (e.g., uncaught exceptions) will produce an HTML file with both the user message and debugging information. Developers/administrators can view these files after the fact, to see the details of what went wrong. These error messages can take a surprising amount of space. Default: `1` (true/do save).
`ErrorMessagesDir`:
  This is the name of the directory where HTML error messages get stored. Default: `ErrorMsgs`.
`EmailErrors`:
  If true, error messages are e-mailed out according to the ErrorEmailServer and ErrorEmailHeaders settings. You must also set `ErrorEmailServer` and `ErrorEmailHeaders`. Default: `0` (false/do not email).
`EmailErrorReportAsAttachment`:
  1 to make html error reports be emailed as text with an html attachment, or 0 to make the html the body of the message. Default `0` (false/html in body).
`ErrorEmailServer`:
  The SMTP server to use for sending e-mail error messages. Default: `"mail.-.com"` (i.e., unset)
`ErrorEmailHeaders`:

  The e-mail headers used for e-mailing error messages. Be sure to configure `"From"`, `"To"` and `"Reply-to"` before turning `EmailErrors` on. Default:

      {
          'From':         '-@-.com',
          'To':           ['-@-.com'],
          'Reply-to':     '-@-.com',
          'Content-type': 'text/html',
          'Subject':      'Error'
      }

`MaxValueLengthInExceptionReport`:
  Values in exception reports are truncated to this length, to avoid excessively long exception reports. Set this to `None` if you don't want any truncation. Default: `500`.
`RPCExceptionReturn`:
  Determines how much detail an RPC servlet will return when an exception occurs on the server side. Can take the values, in order of increasing detail, `"occurred"`, `"exception"` and `"traceback"`. The first reports the string `"unhandled exception`", the second prints the actual exception, and the third prints both the exception and accompanying traceback. All returns are always strings. Default: `"traceback"`
`ReportRPCExceptionsInWebKit`:
  `1` means report exceptions in RPC servlets in the same way as exceptions in other servlets, i.e. in the logfiles, the error log, and/or by email. `0` means don't report the exceptions on the server side at all; this is useful if your RPC servlets are raising exceptions by design and you don't want to be notified. Default: `1` (true/do report exceptions).

## Logging

`LogActivity`:
  If true, then the execution of each servlet is logged with useful information such as time, duration and whether or not an error occurred. Default: `1` (true).
`ActivityLogFilenames`:
  This is the name of the file that servlet executions are logged to. This setting has no effect if `LogActivity` is 0. The path can be relative to the WebKit location, or an absolute path. Default: `"Logs/Activity.csv"`.
`ActivityLogColumns`:
  Specifies the columns that will be stored in the activity log. Each column can refer to an object from the set: [application, transaction, request, response, servlet, session] and then refer to its attributes using "dot notation". The attributes can be methods or instance attributes and can be qualified arbitrarily deep. Default: `['request.remoteAddress', 'request.method', 'request.uri', 'response.size', 'servlet.name', 'request.timeStamp', 'transaction.duration', 'transaction.errorOccurred']`.

# AppServer.config

`Host`:
  The host the server runs on. There is little reason to change this unless you have a machine with multiple network interfaces, and you don't want Webware to listen on all interfaces. Default `127.0.0.1`.
`Port`:
  The port the application server listens to for requests from the adapter. You cannot point a browser to this port. You may wish to change this if you have another application running at this port, or if you are running more than one AppServer they must each be listening at a different port. Default: `8086`.
`PluginDirs`:

  When the application server starts up, it looks in these locations for plugins. Each plugin is a subdirectory of its own. By default WebKit looks in the `Webware/` directory (`..`) for plugins -- several of which are shipped with Webware. Default `[".."]`. See Creating Plugins for information on creating your own plug-ins. @@ ib: are these really differently cased?

  The advantage of a plug-in directory is that you can add new plug-ins to the app server simply by dropping them into the directory; no additional configuration is necessary.

`PlugIns`:
  Loads the plug-ins from the given locations when starting the AppServer. You must add a directory to the list for every plug-in you use -- `PlugInDirs` is usually easier. Default `[]`.
`PrintConfigAtStartUp`:
  Prints configuration to console at startup. Default `1` (true).
`Verbose`:
  If true, then additional messages are printed while the AppServer runs, most notably information about each request such as size and response time. Default `1` (true).
`ServerThreads`:
  The maximum number of threads in the request handler thread pool, and therefore, the maximum number of concurrent requests that can be served. Unless you have a serious load on a high end machine, the default is generally sufficient. Default `10`. @@ ib: I don't believe this is correct -- I think more threads are created on demand, but only this many threads sit around waiting.
`CheckInterval`:
  The number of virtual instructions after which Python will check for thread switches, signal handlers, etc. This is passed directly to `sys.setcheckinterval()`. Benchmarks have shown 100 to give a worthwhile performance boost with higher values resulting in little gain. Default `100`.