Seamless mobility and session continuity with TCP mobility options
阅读说明:本技术 一种具有tcp移动性选项的无缝移动性和会话连续性 (Seamless mobility and session continuity with TCP mobility options ) 是由 伯吉兹·皮特哈瓦拉 乌马·S·春都里 于 2018-06-11 设计创作,主要内容包括:一种为具有会话连续性的传输控制协议(TCP)传输提供移动性的方法。在一个实施例中,所述方法使用TCP无缝移动性选项(TCP-SMO)连接标识符在第一通信设备和第二通信设备之间建立通信会话,其中,所述连接标识符用于标识所述第一通信设备和所述第二通信设备之间的通信会话。通信会话期间,所述方法在所述通信设备和所述第二通信设备之间交换数据。所述方法使用TCP-SMO连接标识符维护所述通信设备和所述第二通信设备之间的通信会话,以响应移动性事件。(A method of providing mobility for Transmission Control Protocol (TCP) transmissions with session continuity. In one embodiment, the method establishes a communication session between a first communication device and a second communication device using a TCP seamless mobility option (TCP-SMO) connection identifier, wherein the connection identifier is used to identify the communication session between the first communication device and the second communication device. During a communication session, the method exchanges data between the communication device and the second communication device. The method maintains a communication session between the communication device and the second communication device using a TCP-SMO connection identifier in response to a mobility event.)
1. A method of providing mobility for Transmission Control Protocol (TCP) transmissions with session continuity between a first communication device and a second communication device, the method comprising:
the first communication device establishing a communication session between the first communication device and the second communication device using a TCP seamless mobility option (TCP-SMO) connection identifier, wherein the connection identifier is used to identify the communication session between the first communication device and the second communication device;
during a communication session, the first communication device exchanging data between the first communication device and the second communication device; and
the first communication device maintains a communication session between the first communication device and the second communication device using the TCP-SMO connection identifier in response to a mobility event.
2. The method of claim 1, wherein the TCP-SMO connection identifier comprises a first TCP-SMO connection identifier of the first communication device.
3. The method of claim 1, wherein the TCP-SMO connection identifier comprises a first TCP-SMO connection identifier of the first communication device and a second TCP-SMO connection identifier of the second communication device.
4. The method of claim 1, wherein establishing the communication session between the first communication device and the second communication device comprises:
the first communication device sending a TCP-synchronization (TCP-SYN) message to the second communication device, wherein the TCP-SYN message has the TCP-SMO connection identifier in a TCP header;
receiving, by the first communication device, a synchronization-acknowledgement (SYN-ACK) message having the TCP-SMO connection identifier in a TCP header of the SYN-ACK message indicating that TCP-SMO is supported by the second communication device; and
the first communication device sends a synchronization-acknowledgement (SYN-ACK) message to the second communication device, wherein a TCP header of the SYN-ACK message has the TCP-SMO connection identifier, acknowledges receipt of the SYN-ACK message, and further establishes a communication session between the first communication device and the second communication device.
5. The method of claim 1, wherein maintaining the communication session between the first communication device and the second communication device in response to the mobility event comprises:
the first communication device receives a new Internet Protocol (IP) address of the second communication device from the second communication device during the communication session in response to the mobility event.
6. The method of claim 1, wherein maintaining the communication session between the first communication device and the second communication device in response to the mobility event comprises:
the first communication device sends the new IP address of the first communication device to the second communication device during the communication session in response to the mobility event.
7. The method of claim 1, wherein maintaining the communication session between the first communication device and the second communication device in response to the mobility event comprises:
during a communication session in response to the mobility event, the first communication device sends the new IP address of the first communication device to the second communication device in a TCP keep-alive probe message.
8. The method of claim 1, wherein the TCP-SMO connection identifier is a randomly generated unique identifier, and wherein the identifier is generated by a TCP stack of the first communication device.
9. The method of claim 1, wherein the TCP-SMO connection identifier is a randomly generated unique identifier that is provided to a TCP layer of the first communication device by one of an application or a second protocol during opening of a TCP socket.
10. The method of claim 1, wherein the TCP-SMO connection identifier is included in a TCP-SMO data structure, wherein the TCP-SMO data structure further comprises a security field for specifying security options.
11. The method of claim 10, wherein the security options comprise a transmission security protocol (TCP-AO), a TCP message digest 5(TCP-MD5), and a diffie-hellman (DH) key exchange algorithm between the first communication device and the second communication device.
12. The method of claim 11, wherein the security field is a two-bit field used to designate any DH packet as a security option to protect an IP address change notification in response to the mobility event.
13. A communication device, comprising:
a network communication interface for implementing communication through a network;
a memory storage unit comprising instructions; and
one or more processors in communication with the network communication interface and the memory storage unit, wherein the one or more processors execute the instructions to:
establishing a communication session between the communication device and a second communication device using a TCP seamless mobility option (TCP-SMO) connection identifier, wherein the connection identifier is used to identify the communication session between the communication device and the second communication device;
exchanging data between the communication device and the second communication device during a communication session; and
maintaining a communication session between the communication device and the second communication device using the TCP-SMO connection identifier in response to a mobility event.
14. The communications device of claim 13, wherein the TCP-SMO connection identifier comprises a first TCP-SMO connection identifier of the communications device.
15. The communications device of claim 13, wherein the TCP-SMO connection identifier comprises a first TCP-SMO connection identifier of the communications device and a second TCP-SMO connection identifier of the second communications device.
16. The communication device of claim 13, wherein establishing the communication session between the communication device and the second communication device comprises:
sending a TCP-synchronization (TCP-SYN) message to the second communication device, wherein the TCP-SYN message has the TCP-SMO connection identifier in a TCP header;
receiving a synchronization-acknowledgement (SYN-ACK) message, wherein the TCP header of the SYN-ACK message has the TCP-SMO connection identifier therein, indicating that the second communication device supports TCP-SMO; and
sending a synchronization-acknowledgement (SYN-ACK-ACK) message to the second communication device, wherein a TCP header of the SYN-ACK-ACK message has the TCP-SMO connection identifier, acknowledging receipt of the SYN-ACK message, and further establishing a communication session between the communication device and the second communication device.
17. The communications device of claim 13, wherein the one or more processors are further configured to: executing the instructions to send a new Internet Protocol (IP) address of the communication device to the second communication device during the communication session in response to the mobility event.
18. The communications device of claim 13, wherein the TCP-SMO connection identifier is a randomly generated unique identifier, the identifier being generated by a TCP stack of the communications device.
19. The communications device of claim 13, wherein the TCP-SMO connection identifier is a randomly generated unique identifier that is provided to the TCP layer by one of an application or a second protocol during opening of a TCP socket.
20. The communications device of claim 13, wherein said TCP-SMO connection identifier is included in a TCP-SMO data structure, wherein said TCP-SMO data structure further comprises a two-bit security field for designating any diffie-hellman (DH) packet as a security option to protect an IP address change notification in response to said mobility event.
Technical Field
Embodiments of the present invention relate to the field of wireless communications, and in particular, to a method and an apparatus for providing seamless mobility and session continuity using a Transmission Control Protocol (TCP) mobility option.
Background
TCP is one of the main protocols of the Internet Protocol (IP) suite. TCP defines how to establish and maintain network communication sessions. TCP provides reliable, ordered and error-detecting eight-bit word streaming between applications running on hosts that communicate over an IP network. The main internet applications of the world wide web, e-mail, remote management and file transfer rely on TCP.
Disclosure of Invention
A first aspect of the present invention provides a method performed by a first communication device of providing mobility for Transmission Control Protocol (TCP) transmissions with session continuity between the first communication device and a second communication device. The method includes establishing a communication session between the first communication device and the second communication device using a TCP seamless mobility option (TCP-SMO) connection identifier, wherein the connection identifier is used to identify the communication session between the first communication device and the second communication device. During a communication session, the method exchanges data between the first communication device and the second communication device. The method maintains a communication session between the first communication device and the second communication device using the TCP-SMO connection identifier in response to a mobility event.
A second aspect of the invention provides a communication device. The communication device includes: a network communication interface for implementing communication through a network; a memory storage unit comprising instructions; and one or more processors in communication with the network communication interface and the memory storage unit, wherein the one or more processors execute the instructions to: establishing a communication session between the communication device and a second communication device using a TCP seamless mobility option (TCP-SMO) connection identifier, wherein the connection identifier is used to identify the communication session between the communication device and the second communication device; exchanging data between the communication device and the second communication device during a communication session; and maintaining a communication session between the communication device and the second communication device using the TCP-SMO connection identifier in response to a mobility event.
A third aspect of the invention provides a data structure. The data structure provides mobility for Transmission Control Protocol (TCP) transmissions with session continuity between the first communication device and the second communication device. The data structure may include one or more of the following fields: a source connection identifier field to specify a source connection identifier; a target connection identifier field to specify a target connection identifier; a mobility event field for specifying a mobility event; a security option field to specify a security option; and an optional data field for specifying a checksum for generating the hash using the content identifier.
In any of the preceding aspects, the TCP-SMO connection identifier may comprise a first TCP-SMO connection identifier of the first communication device and/or a second TCP-SMO connection identifier of the second communication device.
In any of the preceding aspects, establishing the communication session between the first communication device and the second communication device may comprise: the first communication device sending a TCP-synchronization (TCP-SYN) message to the second communication device, wherein the TCP-SYN message has the TCP-SMO connection identifier in a TCP header; receiving, by the first communication device, a synchronization-Acknowledgement (SYN-ACK) message, wherein the TCP header of the SYN-ACK message has the TCP-SMO connection identifier therein, indicating that the second communication device supports TCP-SMO; and the first communication device sending a synchronization-Acknowledgement (SYN-ACK) message to the second communication device, wherein a TCP header of the SYN-ACK message has the TCP-SMO connection identifier, and the SYN-ACK message is acknowledged to be received, thereby establishing a communication session between the first communication device and the second communication device.
In any preceding aspect, maintaining the communication session between the first communication device and the second communication device in response to the mobility event may comprise: the first communication device receives a new IP address of the second communication device from the second communication device during the communication session in response to the mobility event.
In any preceding aspect, maintaining the communication session between the first communication device and the second communication device in response to the mobility event may comprise: the first communication device sends the new IP address of the first communication device to the second communication device during the communication session in response to the mobility event.
In any of the preceding aspects, the new IP address may be sent in a null data packet or a TCP keep-alive probe message.
In any of the preceding aspects, the TCP-SMO connection identifier may be a randomly generated unique identifier generated by a TCP stack of the first communication device or provided to a TCP layer of the first communication device by one of an application or a second protocol.
In any of the preceding aspects, the TCP-SMO connection identifier may be included in a TCP-SMO data structure. The TCP-SMO data structure may include a security field to specify security options. The security options may include a transmission security protocol, TCP, Authentication Option (TCP-Authentication Option, TCP-AO for short), a TCP Message Digest 5(TCP-Message Digest5, TCP-MD5 for short), and Diffie-Hellman (DH for short) key exchange algorithm between the first communication device and the second communication device. The security field may be a two-bit field for designating any DH packet as a security option to protect IP address change notifications in response to the mobility event.
The above aspects, further aspects and advantages thereof are described in the following detailed description.
Drawings
For a more complete understanding of the present invention, reference is now made to the following brief description, taken in connection with the accompanying drawings and detailed description, wherein like reference numerals represent like parts.
Fig. 1 shows a diagram of a current TCP connection between a source device and a target device according to an embodiment of the invention.
Fig. 2 shows a diagram of IP address changes during the TCP connection of fig. 1, according to an embodiment of the invention.
Fig. 3 shows a diagram of a TCP-SMO data structure according to an embodiment of the invention.
Fig. 4 is a diagram illustrating the TCP-SMO data structure of fig. 3 with mobility option activation according to an embodiment of the present invention.
Fig. 5 shows a timing diagram of a communication session with TCP-SMO, according to an embodiment of the invention.
Fig. 6 shows a timing diagram of a communication session without TCP-SMO, according to an embodiment of the invention.
Fig. 7 shows a timing diagram of a communication session with secure TCP-SMO, according to an embodiment of the invention.
Fig. 8 shows a flow diagram of a method of providing seamless mobility for TCP transmissions with session continuity, in accordance with an embodiment of the present invention.
Fig. 9 shows a flow diagram of another method for providing seamless mobility for TCP transmissions with session continuity, in accordance with an embodiment of the present invention.
Fig. 10 shows a diagram of an apparatus according to an embodiment of the invention.
The drawings described are only exemplary and are not intended to assert or imply any limitation with regard to the environments, architectures, designs, or processes in which different embodiments may be implemented. In the illustrated figures, optional components or steps are shown in phantom.
Detailed Description
It should be understood at the outset that although an illustrative implementation of one or more embodiments are provided below, the disclosed systems and/or methods may be implemented using any number of techniques, whether currently known or in existence. The present invention should in no way be limited to the illustrative implementations, drawings, and techniques illustrated below, including the exemplary designs and implementations illustrated and described herein, but may be modified within the scope of the appended claims along with their full scope of equivalents.
As used in this written disclosure and in the claims, the terms "include" and "comprise" are used without limitation, and thus should be understood to mean "include, but not limited to". As used herein, unless otherwise noted, "or" does not require mutual exclusivity, and the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.
A module or unit referenced herein may include one or more hardware or electronic components, such as circuits, processors, and memories dedicated to performing specific functions. The memory may be volatile memory or non-volatile memory that stores data such as, but not limited to, computer-executable instructions, machine code, and other various forms of data. The modules or units may be used to execute one or more instructions using data to perform one or more tasks. In some cases, a unit may also represent a specific set of functions, software instructions, or circuitry for performing a specific task.
A network as referred to herein refers to a system of electronic devices connected together by communication links so as to be able to exchange information and/or share resources. Non-limiting examples of networks include a local-area network (LAN), a wide-area network (WAN), a metropolitan-area network (MAN), a Passive Optical Network (PON), and a Radio Access Network (RAN). The network may include one or more private networks and/or public networks, such as the internet. In various embodiments, the network may employ any type of communication standard and/or protocol.
TCP is a connection-oriented reliable transport protocol layered over IP. TCP is the primary transport protocol used to provide a reliable full duplex connection. The most common use of TCP is to exchange TCP data encapsulated in IP datagrams. An IP datagram includes an IP header and a TCP segment. The TCP segment includes a TCP header and optionally TCP data. TCP segments are exchanged to establish a connection, transfer data, send acknowledgements, advertise window size, and close the connection.
Each TCP connection maintains a connection state, commonly referred to as a TCB in the data structure. The TCB contains information on the connection status, timers, flags, local and remote host numbers and ports, and feedback parameters regarding the transmission properties of the connection. The TCB performs maintenance on a per connection basis. As currently practiced, when a TCP connection is opened with a peer, the initiator and responder of the connection identify the connection (e.g., a TCP session or socket) by source port, destination port, source IP address, and destination IP address. The source port and the destination port are provided in a TCP header. The source IP address and the destination IP address are set in the IP header.
The connection is identified by socket parameters and stored in the TCB. Any change to the connection identifier (e.g., source IP address and/or destination IP address) at both ends of the connection, for example, when an endpoint moves/switches its network connection, can result in a TCP Reset (RST) or a session timeout.
Accordingly, embodiments of the present invention include systems, methods, and new data structures for providing seamless mobility and session continuity with TCP mobility options, also referred to herein as "TCP-seamless mobility options (TCP-SMO)". According to an embodiment of the invention, the TCP-SMO comprises a connection identifier for connection identification in TCB or TCP. Session continuity may be achieved in a communication session established between endpoints supporting the new TCP-SMO by using a connection identifier in the new TCP-SMO instead of a conventional TCB connection identifier currently defined by request for comment (RFC) 793, which uses the source and destination IP addresses in TCP, even if either endpoint of the connection changes its IP address. In embodiments of the present invention, communication delays are reduced by eliminating the time and procedures to terminate a communication session and reestablish a new communication session due to a change in the endpoint IP address.
Fig. 1 shows a current TCP connection between a client or
Fig. 2 illustrates the effect of the
Accordingly, embodiments of the present invention are directed to providing seamless mobility with uninterrupted TCP connections using new TCP-SMO. In one embodiment, the new TCP-SMO introduces connection identifiers and configures TCP to use these identifiers for TCB or connection identification. For example, FIG. 3 shows a schematic diagram of a TCP-
In the embodiment, the TCP-
In one embodiment, the
00: the Diffie-Hellman values are not exchanged.
01: 1024 bit modular exponentiation (ModP) set (mandatory).
10: a 2048 bit ModP group/elliptic curve group having a 200 bit ModP.
11: and (6) reserving.
The above setting is only one exemplary embodiment and the above bits may be used to indicate some other possible ModP DH groups in other embodiments. One of the advantages of the TCP-
Furthermore, in various embodiments, Security Option-2 may be applied to the MultiPath TCP (MultiPath TCP, MPTCP for short) protocol as well as the TCP protocol. Unlike current MP-TCP security, as described by https:// tools. ietf. org/html/draft-ietf-mptcp-rfc6824bis-10# section-2.7, the key is sent in clear in an MP _ CAPABLE message, and the MP _ JOIN message is protected by HMAC-SHA256, Security option-2 in this embodiment of the invention enables the DH exchange to obtain a shared key, which can then be used to protect the MP _ JOIN message.
In an embodiment, the
In one embodiment, the
In one embodiment, the Source Connection Identifier (SCID)
In one embodiment, the
Fig. 5 illustrates a timing diagram 500 of a communication session with TCP-SMO in accordance with an embodiment of the disclosure. In the depicted embodiment, the TCP segment timing diagram 500 represents a complete connection from a three-way handshake to a connection ending with a newly defined TCP-SMO. In the embodiment, the initial IP address of the
At
At
In the embodiment, in
Fig. 6 shows a timing diagram 600 of TCP-SMO with
Fig. 7 illustrates a timing diagram 700 for a communication session using a DH to provide secure TCP-SMO, according to an embodiment of the disclosure. Similar to FIG. 5,
In
In
In
In the above sequence, the DH shared key is used as the key to generate the hash, and a conventional TCP header checksum algorithm is used to compute the checksum of the resulting hash output. The above embodiment does not present a security problem because the generated hash is not truncated to keep it in the 4-byte alternative data, but rather retains the 4-byte checksum of the hash.
When the
The timing diagram described above relies on the "data" to be sent during the three-way handshake. In one embodiment, this data is not application data, but rather the ModP (DH common value) for the selected DH set. In some embodiments, since the size of this data is any size from 1024 bits (DH set-1) to 2048 bits (DH set-2)/200 bits (elliptic curve DH set), it is not possible to send it as part of the optional data (limited option space in TCP header). Although section 3.4 of RFC793 specifies and allows mechanisms to send application data during a TCP three-way handshake, according to an embodiment, this "data" should not be sent to the application until the handshake is complete. Thus, according to an embodiment, the TCP end host stack consumes the data until the handshake process is completed.
Fig. 8 shows a flow diagram of a
Fig. 9 illustrates a flow diagram of a
In
During the source node and the target node communication session, the source node determines in
Fig. 10 is a schematic diagram of an
The
The
Thus, embodiments of the present invention introduce a TCP-SMO data structure that can be used to change the TCP host stack across a connection, including how to look for the TCB defined in RFC793, section 2.7, and then can be used to provide seamless mobility. In one embodiment, when an "open" call is completed at the host stack, then a TCB is created. In one embodiment, during connection opening, a flag may be set to indicate the use of TCP-SMO and additional parameters as needed.
Embodiments of the present invention are superior to current solutions for TCP mobility, such as tunnel-based solutions (e.g., LISP), Encapsulation-based solutions (e.g., HIP and LISP), translation-based solutions (e.g., Identity Location Address (ILA) (with universal User Datagram Protocol (UDP) Encapsulation (GUE))) and multiple TCP connections with load balancing options (e.g., multipath TCP (mptcp)). For example, embodiments of the present invention are superior to any solution for tunneling, encapsulation, or encapsulation with translation-based encapsulation, as all of these solutions incur additional overhead (message size, checksum calculation, and additional layer of separate processing) and depend on the intermediate nodes in the network to be upgraded, whereas embodiments of the present invention do not. In addition, MPTCP requires more complex signaling than the embodiments of the present invention. Other drawbacks of MPTCP include performance issues, congestion control related issues, and MPTCP requires the host to have deep knowledge of the underlying network topology to create multiple paths.
Embodiments of the present invention also provide several key unique advantages or implementations based on other proposed methods, such as the method proposed by Snoeren in https:// tools. For example, the method disclosed by Snoeren requires an additional three-way handshake during the migration of the connection, whereas the embodiments of the present invention do not. Second, the method disclosed by Snoeren requires the use of two separate options: migration permission options and migration options, whereas embodiments of the present invention use only one mobility option. Third, the security options disclosed by Snoeren are limited to truncating elliptic curves, while other DH variants may be used with embodiments of the invention. Fourth, the method disclosed by Snoeren sends the security data in the TCP option itself, while the embodiments of the present invention provide the security data in the data portion of the TCP layer processing. Fifth, in terms of changes in the TCP layer, in the method disclosed by Snoeren, the TCB is migrated after the new three-way handshake, whereas embodiments of the present invention rely on the use of a connection identifier.
Other advantages of embodiments of the present invention over the prior art include, but are not limited to: minimal time delay for continuity; there is no round trip to the peer for the mobile event update; only the terminal host needs to be changed instead of the network infrastructure; an application cannot check the change from an Application Programming Interface (API) to TCP; the user can control which session protects the mobile continuity; security is provided to protect the session using known TCP-AO or IPSec and/or using embedded authentication with DH. In addition, the embodiment of the invention is not influenced by network equipment (95% of routers pass through a TCP option); a Network Address Translation (NAT)/Network Address Port Translation (NAPT) block in the transmission path; and may be used as multiple data planes based on ID protocols (LISP, HIP, and ILA).
In addition, in an embodiment, the embodiment of the present invention does not have any impact on the NAT/NAPT device between the source device and the target device because the TCB only uses the source connection identifier and the target connection identifier. Furthermore, during mobility, the authentication data verifies the hash of both parties (i.e., does not include a new IP address or port) using a stable source identifier.
In an embodiment, because any new TCP option is easily dropped by the middlebox (e.g., this is typically applied to 5% TCP connections per RFC 7413 section 7.1), to handle the problem after the initial timeout of SYN with TCP-SMO, which indicates that the path encounters an unsupported middlebox, the source sends a SYN segment without this option (i.e., falls back to normal TCP-SYN), thereby resorting to the native TCB, and therefore there is no seamless mobility.
Embodiments of the present invention are preferably implemented using secure connections because existing TCP connections can be hijacked by changing the source IP address (connection hijacking). For example, in one embodiment, embodiments of the invention may be implemented using IP (IPsec) or transport layer (TCP-AO/TCP-MD5) security to protect TCP connections including TCP headers. In one embodiment, when TCP-AO is used, the TCP-SMO size must not exceed 12 bytes to accommodate TCP-AO/TCP-
In another embodiment, online computation of TCP-SMO security, which can be used as a key (predefined algorithm) to generate hash values during move, is implemented within the newly defined TCP-SMO by exchanging DH public values and computing a shared key at both ends. In one embodiment, the DH set and the hash algorithm are predefined and implemented using TCP-SMO to provide the required security.
According to an embodiment, when a device/UE (user equipment) connects to a TCP server, in most cases the location of the TCP server does not change. To support device/UE mobility, in one embodiment, the server TCP stack must be updated to support TCP-SMO. In one embodiment, one way to reduce this update on the server side is to implement TCP-SMO by using a TCP server proxy.
Certain embodiments disclosed herein may be considered as potential "data plane" alternatives to existing ID-based protocols, i.e., LISP (RFC 6830) or HIP (RFC 7401) with corresponding control plane protocols. Embodiments of the present invention do not specify any changes to the control plane of existing identifier-based protocols. However, existing identifier-based protocols will limit the use of the "data plane" proposed herein (e.g., limit the length of the identifier in TCP-SMO (variable, maximum 16 bytes)).
Certain embodiments disclosed herein may be used with common control plane protocols based on new flags, such as, but not limited to, those specified in "https:// tools. ietf. org/html/draft-pad-areas-protocol-specification-01," to provide a "data plane" solution for applications using TCP transport, the entire contents of which are incorporated herein. In some embodiments, UDP-based applications may use mobility solutions with a fast UDP network connection (QUIC) protocol that uses the same workflow.
Further, as described above, according to an embodiment, if TCP-SMO does not exist, the TCP connection continues to identify the TCB with the connection identifier specified in RFC 793. Thus, according to an embodiment of the present invention, the proposed embodiments of identifying old methods of connection/TCB according to RFC793 and having connection identifiers in TCP-SMO are supported. For example, in one embodiment, both methods may be supported by maintaining two separate TCBs or by coordinating keys to access existing TCBs.
While the present disclosure provides a number of specific embodiments, it should be understood that the disclosed systems and methods may be embodied in other specific forms without departing from the spirit or scope of the present invention. The present examples are to be considered as illustrative and not restrictive, and the invention is not to be limited to the details given herein. For example, various elements or components may be combined or integrated in another system or certain features may be omitted, or not implemented.
Furthermore, techniques, systems, subsystems, and methods described and illustrated in the various embodiments as discrete or separate may be combined or integrated with other systems, modules, techniques, or methods without departing from the scope of the present disclosure. Other items shown or discussed as coupled or directly coupled or communicating with each other may also be indirectly coupled or communicating through some interface, device, or intermediate component, whether electrically, mechanically, or otherwise. Other alterations, substitutions, and alternative examples will now be apparent to those skilled in the art without departing from the spirit and scope of the disclosure.
- 上一篇:一种医用注射器针头装配设备
- 下一篇:用于提供统一交易接口的适配器