Contains: Manages a single TCP connection for sending and receiving commands.
Written by: DTS
Copyright: Copyright (c) 2011 Apple Inc. All Rights Reserved.
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// QCommandConnection is a general purpose class for managing a command-oriented
// network connection.
// The class is run loop based and must be called from a single thread.
// Specifically, the -open and -close methods add and remove run loop sources
// to the current thread's run loop, and it's that thread that calls the
// delegate callbacks.
@interface QCommandConnection : NSObject
- (id)initWithInputStream:(NSInputStream *)inputStream outputStream:(NSOutputStream *)outputStream;
// Creates the command connection to run over the supplied streams.
// You can set other configuration parameters, like the buffer capacities,
// before calling -open on the connection.
// properties set on init
@property (nonatomic, retain, readonly ) NSInputStream * inputStream;
@property (nonatomic, retain, readonly ) NSOutputStream * outputStream;
// properties that must be configured before -open
@property (nonatomic, assign, readwrite) NSUInteger inputBufferCapacity; // default is 0, meaning chose a reasonable default
@property (nonatomic, assign, readwrite) NSUInteger outputBufferCapacity; // default is 0, meaning chose a reasonable default
// You must open or remove run loop modes before opening the connection
- (void)addRunLoopMode:(NSString *)modeToAdd;
- (void)removeRunLoopMode:(NSString *)modeToRemove;
@property (nonatomic, copy, readonly ) NSSet * runLoopModes; // contains NSDefaultRunLoopMode by default
// properties that can be set at any time
@property (nonatomic, assign, readwrite) id<QCommandConnectionDelegate> delegate;
@property (nonatomic, copy, readwrite) NSString * name; // for debugging
// properties that change as the result of other actions
@property (nonatomic, assign, readonly ) BOOL isOpen;
@property (nonatomic, copy, readwrite) NSError * error;
// Opens the connection. It's not legal to call this if the connection has
// already been opened. If the open fails, this calls the
// -connection:willCloseWithError: delegate method.
// Closes the connection. It is safe to call this even if -open has not called,
// or the connection has already closed. Will not call -connection:willCloseWithError:
// delegate method (that method is only called if the connection closes by
- (void)closeWithError:(NSError *)error;
// Closes the connection with the specified error (nil to indicate an end of file),
// much like what happens if the connection tears (or ends). This is primarily for
// subclasses and delegates. It is safe to call this even if -open has not called,
// or the connection has already closed. This /will/ end up calling the
// -connection:willCloseWithError: delegate method.
- (void)sendCommand:(NSData *)command;
// Sends the specified command down the connection. Note that there's no send-side
// flow control here. If the connection stops sending data, eventually the buffer
// space will fill up and connection will tear.
@protocol QCommandConnectionDelegate <NSObject>
- (void)connection:(QCommandConnection *)connection willCloseWithError:(NSError *)error;
// Called when the connection fails to open or closes badly (error is not nil), or if
// there's an EOF (error is nil).
- (NSUInteger)connection:(QCommandConnection *)connection parseCommandData:(NSData *)commandData;
// Called when data arrives on the connection. The delegate is expected to parse the
// data to see if there's a complete command present. If so, it should consume the
// command and return the number of bytes consumed. If not, it should return 0
// and will be called again when the next chunk of data arrives.
// It is more efficient if the delegate parses out multiple commands in one call,
// but that is not strictly necessary.
// If the delegate detects some sort of failure it is reasonable for it to force
// the connection to close by calling -closeWithError:.
// If the delegate does not implement this method, any data arriving on the input stream
// will cause the connection to fail with kQCommandConnectionInputUnexpectedError.
- (void)connection:(QCommandConnection *)connection logWithFormat:(NSString *)format arguments:(va_list)argList;
// Called to log connection activity.
// The following methods are exported for the benefit of subclasses. Specifically,
// they allow subclasses to see the delegate methods without actually being the
// delegate. The default implementation of these routines just calls the
// delegate callback, if any.
@interface QCommandConnection (ForSubclassOverride)
- (void)willCloseWithError:(NSError *)error;
- (NSUInteger)parseCommandData:(NSData *)commandData;
- (void)logWithFormat:(NSString *)format arguments:(va_list)argList;
// The following methods are exported for the benefit of subclasses.
@interface QCommandConnection (ForSubclassUse)
- (void)logWithFormat:(NSString *)format, ...;
// This allows subclasses to log things to the connection delegate.
+ (NSError *)errorWithCode:(NSInteger)code;
// This allows subclasses to construct errors in the kQCommandConnectionErrorDomain.
// Most connection errors come from NSStream, but some are generated internally.
extern NSString * kQCommandConnectionErrorDomain;
kQCommandConnectionOutputBufferFullError = 1,
kQCommandConnectionInputBufferFullError = 2,
kQCommandConnectionOutputCommandTooLongError = 3,
kQCommandConnectionInputUnexpectedError = 4,
kQCommandConnectionInputCommandTooLongError = 5,
kQCommandConnectionInputCommandMalformedError = 6 // for the benefit of our subclasses