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162 lines
5.1 KiB
Markdown
162 lines
5.1 KiB
Markdown
<div class="short">
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`%gall`
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=======
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Our application server manager.
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It allows applications and vanes to send messages to applications and
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subscribe to data streams. This requires `%gall` to be a sort of a
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hypervisor. Messages coming into `%gall` are routed to the intended
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application, and the response comes back along the same route. If the
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intended target is on another ship, `%gall` will behind-the-scenes route
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it through ames to the other ship to run. This provides an abstraction
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where all apps on all ships are communicated with over the same
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interface.
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`%gall` neither accepts events from unix nor produces effects. It exists
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entirely for the benefit of other vanes and, in particular,
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applications. Eyre exposes `%gall`'s interface over http, and ames does
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the same over the ames network. `%gall` uses ford to compile and run the
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applications.
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</div>
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------------------------------------------------------------------------
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Cards
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=====
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`%gall` accepts the following cards. The first three are the most
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commonly used, while the others are primarily used internally.
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[`%mess`](#mess)
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================
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Sends a message to an app. This will result in a call to the app's
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`++poke` arm. The response is exactly one of a `%nice` if the action
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succeeded or a `%mean` if not.
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------------------------------------------------------------------------
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[`%show`](#show)
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================
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Subscribes to a stream from an app. This will result in a call to the
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app's either `++peek` or `++peer` arm. The first response will always be
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either a `%nice` or a `%mean`, indicating whether or not the
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subscription was successful. After the first response, there will be
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zero or more responses of either `%rush` or `%rust`, which communicate
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either a differntial or full update to the data stream. There may be a
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`%mean`, which indicates that the subscription has been canceled and no
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more responses will be received along this stream.
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------------------------------------------------------------------------
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[`%nuke`](#nuke)
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================
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Unsubscribes the current duct from its stream. This receives a response
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of either a `%nice` or a `%mean`. Note that a response of `%nice` does
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not imply that the current duct was in fact subscribed to any stream.
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------------------------------------------------------------------------
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[`%init`](#init)
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================
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Initializes a ship's apps. This should be called exactly once for each
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ship on the pier. This produces no moves in response.
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------------------------------------------------------------------------
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[`%sire`](#sire)
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================
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Instantiates a child app. The app will be at path `[p parent-path]`, and
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it will be an instance of the `q` app. The only response will be `%gone`
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when the child dies.
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------------------------------------------------------------------------
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[`%rote`](#rote)
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================
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Signifies a remote request from ames. `r` should be of type `rook`. This
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how an app on a foreign ship may send a `%mess`, `%show`, or `%nuke`
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card. Note that `%gall` automatically converts `%mess`, `%show`, and
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`%nuke` into ames messages behind the scenes, so the only entity that
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should use `%rote` and `%roth` is ames. Formally, the response is either
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a `%nice` or a `%mean`, which ames uses to give a positive or negative
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ack. A logical response comes by passing a `%roth` card.
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------------------------------------------------------------------------
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[`%roth`](#roth)
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================
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Gives the response received from a remote request. `r` should be of type
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`roon`. This is how an app responds to a foreign request with a `%rush`,
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`%rust`, `%nice`, or `%mean`. The response is either a `%nice` or a
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`%mean`. Even though we, as the proverb goes, "never ack an ack", we do
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need to acknowledge these responses since they're really independent
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one-way messages.
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------------------------------------------------------------------------
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[`%wipe`](#wipe)
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================
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Wipes the given app from memory. This is generally considered a hack,
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but it is sometimes useful during development to wipe the state of an
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app. We don't guarantee that this actually completely wipes the app.
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Generally, you want to use a `%cide` card if you actually want to kill
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an app. This gives no response.
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------------------------------------------------------------------------
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[`%cide`](#cide)
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================
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Kills an app and all its children. Even though it's not technically a
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part of `%gall`'s interface since it's not in `++kiss` and can't be
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called from the outside, it's worth mentioning `%cide`, which may be
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called from within `%gall` apps. It should call `++part` to allow the
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app any last words. This gives no response.
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------------------------------------------------------------------------
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Service Gates
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=============
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[`++poke`]()
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============
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Handles incoming messages. Most commonly with an associated `%logo`. For
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example `++poke-json` handles an incoming JSON request from `%eyre`.
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[`++peer`]()
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============
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Handles incoming subscriptions.
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[`++pull`]()
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============
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Handles dropping subscribers.
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[`++pour`]()
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============
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Handles responses to `%pass` moves.
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[`++park`]()
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============
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Save state on update.
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[`++prep`]()
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============
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Load state on update.
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