X Record Extension Library

Version 1.13

X Consortium Standard

X Version 11, Release 6.8

Martha Zimet Network Computing Devices, Inc.

edited by Stephen Gildea X Consortium

Copyright © 1994 Network Computing Devices, Inc.

Permission to use, copy, modify, distribute, and sell this documentation for any purpose is hereby granted without fee, provided that the above copyright notice and this permission notice appear in all copies. Network Computing Devices, Inc. makes no representations about the suitability for any purpose of the information in this document. This documentation is provided "as is" without express or implied warranty.

Copyright © 1995 X Consortium

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X11, Release 6.8 X Record Extension Library, Version 1.13
1. Record Extension Overview

The purpose of this extension is to support the recording and reporting of all core X protocol and arbitrary X extension protocol. This first section gives an overview of the Record extension. The following sections describe how to use the Record extension library.

1.1. Synchronous Playback

Environment information is generally provided to an X-based playback mechanism, which might use the XTest extension to synthesize input events. This synchronization information defines the X state prior to event synthesis (for example, location of the cursor, window locations and sizes, installed colormap, window manager running, and so on) and the consequences that occur after the playback mechanism synthesizes the event. If the user moves the mouse into the icon window and presses and releases a mouse button, the device events MotionNotify, ButtonPress, and ButtonRelease are generated by the X server. Because X follows an event-driven model, there are consequences that follow from the user actions, or device events, that are in the form of X protocol. As a result of the previous user actions, the client could generate requests such as ImageText8 and PolyLine to the X server, or the X server could send non-device events such as Expose and MapNotify to the client window. Both the requests and non-device events that result from user actions are known as consequences, which can be used as a synchronization, or control point, during playback. That is, the playback mechanism does not generate a specific synthesized event until its matching synchronization condition occurs (for example, the window is mapped or unmapped, the cursor changes, a text string displays, and so on)

Because it cannot be predicted what synchronization information is required during playback, the Record extension makes no assumptions about the intended use of the recorded data. Facilities exist to record any core X protocol or X extension protocol. Therefore, Record does not enforce a specific synchronization methodology.

1.2. Design Approach

The design approach of the extension is to record core X protocol and arbitrary X extension protocol entirely within the X server itself. When the extension has been requested to record specific protocol by one or more recording clients, the protocol data is formatted and returned to the recording clients. The extension provides a mechanism for capturing all events, including input device events that do not go to any clients.

1.3. Record Clients

The recommended communication model for a Record application is to open two connections to the server--one connection for recording control and one connection for reading recorded protocol data.

Information about recording (for example, what clients to record, what protocol to record for each client, and so on) is stored in resources called record contexts (type XRecordContext). Most Record extension functions take a record context as an argument. Although in theory it is possible to share record contexts between applications, it is expected that applications will use their own context when performing recording operations.

A client that wishes to record X protocol does so through the library functions defined in section 3 "Library Extension Requests". A typical sequence of requests that a client would make is as follows:

The header for this library is <X11/extensions/record.h>. All identifiers defined in the interface are supplied by this header and are prefixed with "XRecord". The Xtst library contains the XRecord functions.

2. Common Arguments

The Record extension functions XRecordCreateContext and XRecordRegisterClients allow applications to specify the following:

Protocol in the ranges specified by the recording client will be recorded by the server. The device_events protocol type can be specified by a recording client although it may not be sent to a recorded client. The device_events type differs from delivered_events, which also can be specified by a recording client; delivered_events are actually delivered to one or more clients. These event types are discussed in section 2.3 "Protocol Ranges".

The Record extension functions XRecordCreateContext and XRecordRegisterClients have the common arguments datum_flags, clients, and ranges, which specify whether server time and/or client sequence number should precede protocol elements, the clients or client set to record, and the protocol ranges to record, respectively. These are discussed in the following sections.

2.1. Datum Flags

The datum_flags argument is a set of flags OR’ed together to specify options for the record context. Specify zero to disable all the options.

The XRecordFromServerTime flag specifies that XRecordInterceptData structures with a category of XRecordFromServer will have a server_time field specific to each protocol element.

The XRecordFromClientTime flag specifies that XRecordInterceptData structures with a category of XRecordFromClient will have a server_time field specific to each protocol element.

The XRecordFromClientSequence flag specifies that XRecordInterceptData structures with a category of XRecordFromClient or XRecordClientDied will have a valid client_seq field.

2.2. Selecting Clients

The clients argument is a pointer to an array of XRecordClientSpec. XRecordClientSpec is an integral type that holds a resource ID, a client resource ID base, or one of the client set constants defined below.

Duplicate elements in the array are ignored by the functions, and if any element in the array is not valid, a BadMatch error results. A resource ID references the client that created that resource. The client set may be one of the following constants: XRecordCurrentClients, XRecordFutureClients, or XRecordAllClients.

If the element in the array identifies a particular client, protocol specified by the ranges argument will be recorded by the server. The recorded protocol data will not be returned to the recording client until the record context has been enabled. This is described in section 3.4 "Data Transfer".

If the element is XRecordCurrentClients, the protocol ranges specified by the ranges argument, except for device_events, are associated with each current client connection. If the element is XRecordFutureClients, the protocol ranges specified by the ranges argument are associated with each new client connection. If the element is XRecordAllClients, the protocol ranges specified by the ranges argument are associated with each current client connection and with each new client connection.

When the context is enabled, the data connection is unregistered if it was registered. If the context is enabled, XRecordCurrentClients and XRecordAllClients silently exclude the recording data connection. It is an error to explicitly register the data connection.

2.3. Protocol Ranges

The functions XRecordCreateContext and XRecordRegisterClients have another common argument, ranges, which is an array of pointers to XRecordRange structures. Each structure contains ranges of numeric values for each of the protocol types that can be specified and recorded individually by the Record extension. An XRecordRange structure must be allocated by the Record library using the XRecordAllocRange function.

The XRecordRange typedef is a structure with the following members: __ │

XRecordRange:

The types used in XRecordRange members are defined as follows. The XRecordRange8 typedef is a structure with the following members: __ │

XRecordRange8:

The XRecordRange16 typedef is a structure with the following members: __ │

XRecordRange16:

The XRecordExtRange typedef is a structure with the following members: __ │

XRecordExtRange:

If any of the values specified in XRecordRange is invalid, a BadValue error results.

The core_requests member specifies the range of core X protocol requests to record. Core X protocol requests with a major opcode that is between first and last, inclusive, will be recorded. A BadValue error results if the value of first is greater than the value of last. If the values of both first and last are zero, no core X protocol requests will be recorded.

The core_replies member specifies the range of replies resulting from core X protocol requests to record. Replies that result from core X protocol requests with a major opcode between first and last, inclusive, will be recorded. A BadValue error results if the value of first is greater than the value of last. If the values of both first and last are zero, no core X protocol replies will be recorded.

The ext_requests member specifies the range of X extension requests to record. X extension requests with a major opcode between ext_major.first and ext_major.last, and with a minor opcode between ext_minor.first and ext_minor.last, inclusive, will be recorded. A BadValue error results if the value of ext_major.first is greater than the value of ext_major.last or if the value of ext_minor.first is greater than the value of ext_minor.last. If the values of both ext_major.first and ext_major.last are zero, no X extension requests will be recorded.

The ext_replies member specifies the range of replies resulting from X extension requests to record. Replies that result from an X extension request with a major opcode between ext_major.first and ext_major.last, and a minor opcode that is between ext_minor.first and ext_minor.last will be recorded. A BadValue error results if the value of ext_major.first is greater than the value of ext_major.last or if the value of ext_minor.first is greater than the value of ext_minor.last. If the values of both ext_major.first and ext_major.last are zero, no X extension replies will be recorded.

The delivered_events member specifies the range of both core X events and X extension events to record. These events are delivered to at least one client. Core X events and X extension events with a code value between first and last inclusive will be recorded. A BadValue error results if the value of first is greater than the value of last. If the values of first and last are zero, no events will be recorded.

The device_events member specifies the range of both core X device events and X extension device events to record. These events may or may not be delivered to a client. Core X device events and X extension device events with a code value between first and last inclusive that are not delivered to any clients will be recorded. A BadValue error results if the value of first is greater than the value of last. A BadValue error results if first is less than two or last is less than two, except that if first and last are zero, no events will be recorded.

The errors member specifies the range of both core X errors and X extension errors to record. Core X errors and X extension errors with a code value between first and last inclusive will be recorded. A BadValue error results if the value of first is greater than the value of last. If the values of first and last are zero, no errors will be recorded.

A value of True for the client_started member specifies the connection setup reply from the server to new clients. If False, the connection setup reply is not specified by this XRecordRange.

A value of True for the client_died member specifies notification when a client disconnects. If False, notification when a client disconnects is not specified by this XRecordRange.

3. Library Extension Requests

Recording operations are accessed by programs through the use of new protocol requests. The following functions are provided as extensions to Xlib. An Xlib error results if an extension request is made to an X server that does not support the Record extension. Note that any of the extension protocol requests may generate BadAlloc or BadLength errors.

3.1. Query Extension Version

An application uses the XRecordQueryVersion function to determine the version of the Record extension protocol supported by an X server. __ │

Status
XRecordQueryVersion(Display *display, int *cmajor_return, int *cminor_return)

cmajor_return
Returns the extension protocol major version in use.

cminor_return
Returns the extension protocol minor version in use. │__

The XRecordQueryVersion function returns the major and minor protocol version numbers supported by the server. XRecordQueryVersion returns nonzero (success) only if the returned version numbers are common to both the library and the server; otherwise, it returns zero.

3.2. Create and Modify Context

An application uses the XRecordCreateContext function to create a record context. At the time the record context is created by the recording client, the clients to be recorded and the protocol to record for each client may be specified. __ │

XRecordContext
XRecordCreateContext(Display *display, int datum_flags, XRecordClientSpec *clients, int nclients,
XRecordRange **ranges, int nranges)

datum_flagsSpecifies whether detailed time or sequence info
should be sent.

The XRecordCreateContext function creates a record context and returns an XRecordContext, which is then used in the other Record library calls. This request is typically executed by the recording client over its control connection to the X server. The datum_flags specifies whether server time and/or client sequence number should precede protocol elements recorded by context (see section 2.1). When a clients element identifies a particular client, the client is added to the context and the protocol to record for that client is set to the union of all ranges. When a clients element is XRecordCurrentClients, XRecordFutureClients, or XRecordAllClients, the actions described in section 2.2 "Selecting Clients" are performed.

XRecordCreateContext returns zero if the request failed. XRecordCreateContext can generate BadIDChoice, BadMatch, and BadValue errors.

The ranges argument is an XRecordRange* array, that is, an array of pointers. The structures the elements point to shall be allocated by calling XRecordAllocRange. __ │

XRecordRange *
XRecordAllocRange(void) │__

The XRecordAllocRange function allocates and returns an XRecordRange structure. The structure is initialized to specify no protocol. The function returns NULL if the structure allocation fails. The application can free the structure by calling XFree.

3.2.1. Additions

An application uses the XRecordRegisterClients function to modify a previously created record context, by adding clients or modifying the recorded protocol, typically over its control connection to the X server. __ │

Status
XRecordRegisterClients(Display *display, XRecordContext context, int datum_flags,
XRecordClientSpec *clients, int nclients, XRecordRange **ranges, int nranges)

datum_flagsSpecifies whether detailed time or sequence info
should be sent.

The datum_flags specifies whether server time and/or client sequence number should precede protocol elements for all clients recorded by context (see section 2.1). When a clients element identifies a particular client and the client is not yet targeted for recording in the given context, the client is added to the set of clients to record, and the protocol to record for that client is set to the union of all ranges. When the client is already targeted for recording, the protocol to record for that client is set to the union of all ranges. When the element is XRecordCurrentClients, XRecordFutureClients, or XRecordAllClients, the actions described in section 2.2 "Selecting Clients" are performed.

XRecordRegisterClients returns zero if the request failed; otherwise, it returns nonzero.

XRecordRegisterClients can generate XRecordBadContext, BadMatch, and BadValue errors.

3.2.2. Deletions

An application uses the XRecordUnregisterClients function to delete clients from a previously created record context, typically over its control connection to the X server. __ │

Status
XRecordUnregisterClients(Display *display, XRecordContext context, RecordClientSpec *clients,
int nclients)

When an element in clients identifies a particular client, and the specified client is already targeted for recording in the given context, the client and the set of protocol to record for that client are deleted from the context. If the specified client is not targeted for recording, then no action is performed.

When the element is XRecordCurrentClients, all clients currently targeted for recording in context and their corresponding sets of protocol to record are deleted from context.

When the item is XRecordFutureClients, any future client connections will not automatically be targeted for recording in context.

When the element is XRecordAllClients, all clients currently targeted for recording in context and their corresponding sets of protocol to record are deleted from context. Any future client connections will not automatically be targeted for recording in context.

XRecordUnregisterClients returns zero if the request failed; otherwise, it returns nonzero.

XRecordUnregisterClients can generate XRecordBadContext, BadMatch, and BadValue errors.

3.3. Query Context State

An application uses the XRecordGetContext function to query the current state of a record context, typically over its control connection to the X server. __ │

Status
XRecordGetContext(Display *display, XRecordContext context, XRecordState **state_return)

state_return
Specifies the address of a variable into which the
function stores a pointer to the current state of the
record context. │__

The XRecordState typedef returned by XRecordGetContext is a structure with the following members: __ │

XRecordState:

The enabled member is set to the state of data transfer and is True when the recording client has asked that recorded data be sent; otherwise it is False. The datum_flags member is set to the value of these flags for this context. The nclients member is set to the number of XRecordClientInfo structures returned. The client_info member is an array of pointers to XRecordClientInfo structures that contain the protocol to record for each targeted client. The XRecordClientInfo typedef is a structure with the following members: __ │

XRecordClientInfo:

The client member either identifies a client targeted for recording or is set to XRecordFutureClients to describe how future clients will be automatically targeted for recording. The nranges member is set to the number of protocol ranges to be recorded for the specified client. The ranges member is an array of pointers to XRecordRange structures, which specify the protocol ranges to record.

XRecordGetContext returns zero if the request failed; otherwise, it returns nonzero. The context argument must specify a valid XRecordContext or a XRecordBadContext error results.

Recording clients should use the XRecordFreeState function to free the state data returned by XRecordGetContext. __ │

void
XRecordFreeState(XRecordState *state)

XRecordFreeState frees the data pointed to by state. If the argument does not match an XRecordState pointer returned from a successful call to XRecordGetContext, or if XRecordFreeState has already been called with it, the behavior is undefined.

3.4. Data Transfer

An application uses the XRecordEnableContext and XRecordDisableContext functions to change the state of data transfer between the X server and the recording client. These functions allow the application to start recording and reporting of protocol data and to stop recording and reporting of protocol data, respectively.

3.4.1. Enable Context

To direct the X server to record and report protocol, a program uses XRecordEnableContext, typically over its data connection to the X server. The reporting of recorded protocol back to the recording client is handled by the following data structures and procedure definitions. Each recorded protocol element is reported to the recording client through an XRecordInterceptData typedef, a structure with the following members: __ │

XRecordInterceptData:

The id_base member is set to the resource identifier base sent to the client in the connection setup reply and therefore identifies the client being recorded, except when the recorded protocol data is a device event that may have not been delivered to a client. In this case, id_base is set to zero. The server_time member is set to the time of the server when the protocol was recorded. It is the time that was attached to this protocol element in the reply, if so specified by datum_flags, or else the time from the header of the reply that contained this protocol element. The client_seq member is the sequence number of the recorded client’s most recent request processed by the server at the time this protocol element was recorded, if this information were included in the recorded data; otherwise client_seq is 0. The category member is set to one of the following values: XRecordStartOfData, XRecordFromServer, XRecordFromClient, XRecordClientStarted, XRecordClientDied, or XRecordEndOfData. XRecordStartOfData is immediately sent as the first reply to confirm that the context is enabled. XRecordFromClient indicates the protocol data is from the recorded client to the server (requests). XRecordFromServer indicates the protocol data is from the server to the recorded client (replies, errors, events, or device events). XRecordClientStarted indicates that the protocol data is the connection setup reply from the server. XRecordClientDied indicates that the recorded client has closed its connection to the X server; there is no protocol data. XRecordEndOfData indicates that the context has been disabled and that this is the last datum. It does not correspond to any protocol or state change in a recorded client. There is no protocol data.

The client_swapped member is set to True if the byte order of the client being recorded is swapped relative to the recording client; otherwise, it is set to False. All recorded protocol data is returned in the byte order of the recorded client. Therefore, recording clients are responsible for all byte swapping, if required. Device events are in the byte order of the recording client. For replies of category XRecordStartOfData and XRecordEndOfData, client_swapped is set according to the byte order of the server relative to the recording client.

The data member contains the actual recorded protocol data. When category is set to XRecordStartOfData, XRecordClientDied, or XRecordEndOfData, no protocol data are contained in data.

For the core X events KeyPress, KeyRelease, ButtonPress, and ButtonRelease, the fields of a device event that contain valid information are time and detail. For the core X event MotionNotify, the fields of a device event that contain valid information are time, root, root-x and root-y. The time field refers to the time the event was generated by the device.

For the extension input device events DeviceKeyPress, DeviceKeyRelease, DeviceButtonPress, and DeviceButtonRelease, the fields of a device event that contain valid information are device, time, and detail. For DeviceMotionNotify, the valid device event fields are device and time. For the extension input device events ProximityIn and ProximityOut, the fields of a device event that contain valid information are device and time. For the extension input device event DeviceValuator, the fields of a device event that contain valid information are device, num_valuators, first_valuator, and valuators. The time field refers to the time the event was generated by the device.

The data_len member is set to the length of the actual recorded protocol data in 4-byte units.

When the context has been enabled, protocol data the recording client has previously expressed interest in is recorded and returned to the recording client via multiple replies. Because the X server batches the recorded data, more than one protocol element may be contained in the same reply packet. When a reply is received, a procedure of type XRecordInterceptProc is called for each protocol element in the reply. __ │

typedef void(*XRecordInterceptProc)
(XPointer closure, XRecordInterceptData *recorded_data)

abled.

recorded_data
A protocol element recorded by the server extension. │__

This callback may use the control display connection (or any display connection other than the data connection).

Recording clients should use the XRecordFreeData function to free the XRecordInterceptData structure. __ │

Status
XRecordEnableContext(Display *display, XRecordContext context, XRecordInterceptProc callback,

element received.

XRecordEnableContext enables data transfer between the recording client and the X server. All core and extension protocol received from or sent to targeted clients that the recording client has expressed interest in will be recorded and reported to the recording client.

XRecordEnableContext returns zero if the request failed; otherwise, it returns nonzero. The context argument must specify a valid XRecordContext or a XRecordBadContext error results. The error BadMatch results when data transfer is already enabled on the given context.

3.4.2. Enable Context Asynchronously

Because XRecordEnableContext does not return until XRecordDisableContext is executed on the control connection, a nonblocking interface in addition to XRecordEnableContext is provided. This interface also enables data transfer; however, it does not block.

This interface is defined as follows: __ │

Status
XRecordEnableContextAsync(Display *display, XRecordContext context,
XRecordInterceptProc callback, XPointer closure)

element received.

XRecordEnableContextAsync enables data transfer between the recording client and the X server just as XRecordEnableContext does. Unlike XRecordEnableContext, it does not wait for the context to be disabled before returning; XRecordEnableContextAsync returns as soon as the XRecordStartOfData reply has been received and processed.

XRecordEnableContextAsync returns zero if it could not allocate the necessary memory and nonzero if it sent the request successfully to the server. The context argument must specify a valid XRecordContext or a XRecordBadContext error results. The error BadMatch results when data transfer is already enabled.

Each time it reads data from the server connection, Xlib will check for incoming replies and call callback as necessary. The application may direct Xlib explicitly to check for Record data with the XRecordProcessReplies function. __ │

void
XRecordProcessReplies(Display *display)

XRecordProcessReplies will check for any replies that have not yet been processed by the application. The asynchronous callback will be called as appropriate. XRecordProcessReplies returns when all immediately available replies have been processed. It does not block.

To free the data passed to the XRecordInterceptProc callback, use XRecordFreeData. __ │

void
XRecordFreeData(XRecordInterceptData *data)

XRecordFreeData frees the data pointed to by data. If the argument does not match an XRecordInterceptData pointer earlier passed to an XRecordInterceptProc callback or if XRecordFreeData has already been called with it, the behavior is undefined.

3.4.3. Disable Context

To direct the X server to halt the reporting of recorded protocol, the program executes XRecordDisableContext, typically over its control connection to the X server. __ │

Status
XRecordDisableContext(Display *display, XRecordContext context)

The XRecordDisableContext function disables context, stopping all recording over its data connection. Any complete protocol elements for context that were buffered in the server will be sent to the recording client rather than being discarded. If a program attempts to disable an XRecordContext that has not been enabled, no action will take place.

XRecordDisableContext returns zero if the request failed; otherwise, it returns nonzero. The context argument must specify a valid XRecordContext or an XRecordBadContext error results.

3.5. ID Base Mask

To determine the mask the server uses for the client ID base, use XRecordIdBaseMask. __ │

XID
XRecordIdBaseMask(Display *display)

The XRecordIdBaseMask function returns the resource ID mask passed to the client by the server at connection setup.

3.6. Free Context

Before terminating, the program should request that the server free the record context. This is done with the XRecordFreeContext function, typically over the record client’s control connection to the X server. __ │

Status
XRecordFreeContext(Display *display, XRecordContext context)

The XRecordFreeContext function frees the given context for the requesting client. Freeing a record context releases the clients targeted for recording and their respective protocol ranges to record. If protocol data is being reported to the recording client, generally over the data connection to the X server, the reporting ceases as if XRecordDisableContext had been called on the given context. When a program terminates without freeing its record context, the X server will automatically free that context on behalf of the client.

XRecordFreeContext returns zero if the request failed; otherwise,it returns nonzero. The context argument must specify a valid XRecordContext or a XRecordBadContext error results.

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