SSE
The Social and Solidarity Economy (SSE) refers to a range of enterprises, organizations, and entities—such as cooperatives, mutual societies, associations, foundations, and social enterprises—that conduct economic activities guided by principles of solidarity, democratic governance, and the pursuit of social or environmental objectives rather than profit maximization.[1][2] These entities typically reinvest surpluses to advance collective interests, emphasize worker and community ownership, and integrate ethical considerations into production and distribution processes.[3] Rooted in 19th-century cooperative movements responding to industrial disruptions, SSE has gained international recognition through bodies like the International Labour Organization, which in 2023 adopted a resolution affirming its role in promoting decent work and sustainable development.[4][5] SSE entities operate across sectors including agriculture, finance, housing, and care services, often filling gaps left by market failures or state provision, such as supporting marginalized communities through self-help groups or community-based enterprises.[6] Empirical studies indicate contributions to employment generation, particularly for vulnerable populations, and resilience in economic crises, as seen in cooperatives maintaining jobs during downturns via member solidarity mechanisms.[7][8] Notable successes include large-scale models like Spain's Mondragon Corporation, which employs over 70,000 people with democratic structures, and regional networks advancing circular economy practices by prioritizing resource reuse and local needs.[9] International frameworks, including UN Sustainable Development Goals alignments, highlight SSE's potential in fostering inclusive growth and environmental stewardship, with data from 34 OECD countries showing millions employed in such entities.[10][8] Despite these attributes, SSE faces challenges in scalability and integration with broader economies, as smaller entities often struggle with financing and regulatory hurdles that favor profit-oriented firms.[11] Criticisms include difficulties in measuring impact due to diverse structures, potential inefficiencies from consensus-based decisions, and reliance on public subsidies, which can distort market signals or lead to dependency.[12][13] While proponents cite causal links to reduced inequality through democratic reinvestment, empirical evidence remains uneven, with successes varying by context and limited comparative data against private sector benchmarks.[14][15] Sources advancing SSE narratives, often from international agencies or academic circles, warrant scrutiny for ideological alignment with anti-capitalist paradigms, potentially overlooking cases where SSE models underperform in innovation or growth.[16]Computing and Technology
Streaming SIMD Extensions
Streaming SIMD Extensions (SSE) is a single instruction, multiple data (SIMD) instruction set extension to the x86 architecture, developed by Intel to accelerate parallel processing in multimedia and computational applications. Introduced in 1999 with the Pentium III processor (codename Katmai), SSE added 70 new instructions focused primarily on packed single-precision floating-point operations, enabling four 32-bit floats to be processed simultaneously per instruction.[17][18] SSE introduced eight 128-bit XMM registers, distinct from the earlier MMX registers, which could only handle integer data and required state preservation for floating-point compatibility; the XMM registers support direct SIMD floating-point arithmetic without such overhead. Key instructions include ADDPS for packed addition, MULPS for multiplication, and MOVAPS for aligned moves, alongside support for data packing, unpacking, and comparisons to optimize streaming data flows in applications like 3D graphics rendering and video encoding.[19] These features targeted performance gains in domains such as image processing, speech recognition, and audio synthesis by reducing instruction counts for vectorizable workloads.[19] Designed as a competitor to AMD's 3DNow! extension, SSE emphasized floating-point SIMD for broader scientific computing applicability, though it initially lacked integer support, which was added in the subsequent SSE2 extension with the Pentium 4 in 2000.[20] SSE requires explicit enabling via the CR0 and CR4 control registers and OSFXSR flag, with compiler intrinsics or assembly for utilization, and it laid the foundation for later extensions like SSE3 (2004) that added horizontal operations and complex arithmetic.[18] Adoption was widespread in x86 processors post-1999, with backward compatibility ensured in Intel Core and AMD equivalents, though performance varies by core count and clock speed in vector-heavy tasks.[21]Server-Sent Events
Server-Sent Events (SSE) is a web technology standardized in the HTML Living Standard that allows a server to push real-time updates to a client over a persistent HTTP connection, enabling unidirectional communication from server to browser without requiring client polling or full page reloads.[22] The mechanism relies on the EventSource JavaScript API, where a client establishes a connection to a server endpoint that responds with thetext/event-stream MIME type, after which the server streams discrete events as text data.[23] Proposed around 2006 by Ian Hickson as part of early HTML5 development efforts, SSE provides a lightweight alternative to more complex protocols for scenarios like live notifications or status updates.[24]
Implementation involves the client creating an EventSource instance, such as new EventSource('/events'), which triggers an HTTP GET request with Accept: text/event-stream.[22] The server maintains the connection open and sends events in a line-based format: optional event: type for custom event names, one or more data: payload lines for the message body (UTF-8 encoded text only), optional id: identifier for reconnection tracking, and retry: milliseconds for custom reconnection delays, all terminated by two consecutive newlines (\n\n).[25] Upon receipt, the browser parses and dispatches events via addEventListener('message', handler) or custom types, with built-in handling for connection errors, automatic reconnection (default 3-second delay, exponential backoff up to 40 seconds after five failures), and Last-Event-ID headers for resuming from the last acknowledged event.[22]
SSE differs from WebSockets in its reliance on standard HTTP/1.1 (or HTTP/2), avoiding a dedicated protocol upgrade handshake, which simplifies proxy traversal and fallback to HTTP semantics like caching or authentication.[26] While WebSockets support full-duplex bidirectional exchange and binary data over a single TCP socket, SSE is strictly server-to-client, with lower overhead for one-way streams but requiring separate requests for client-to-server data.[27] This makes SSE preferable for broadcast-style updates, such as dashboards or chat notifications, where server simplicity and automatic recovery outweigh bidirectional needs.[26]
Browser compatibility is robust across modern engines, with full support in Chrome and Chromium-based browsers since version 6 (released September 2010), Firefox since version 6 (August 2011), Safari since version 5 (June 2010), and Edge since version 79 (January 2020); partial or polyfill-required support exists in older Internet Explorer versions via libraries.[28][25] However, browsers enforce per-domain connection limits—typically 6 concurrent HTTP connections in Chrome, affecting SSE streams—which can throttle multiple feeds unless multiplexed via a single endpoint.[29] Servers must flush output buffers promptly and avoid compression (e.g., gzip) on event streams to prevent buffering delays, and cross-origin requests require proper CORS headers like Access-Control-Allow-Origin.[25]
Common applications include real-time feeds for stock prices, social media updates, or monitoring logs, where the protocol's text-only nature suits JSON payloads but excludes binary media like images.[30] Despite its efficiency for unidirectional pushes, SSE adoption remains niche compared to WebSockets due to the latter's versatility, though SSE's native reconnection logic and HTTP compatibility enhance reliability in firewalled environments.[26]
Security Service Edge
Security Service Edge (SSE) is a cloud-native cybersecurity framework that converges multiple security functions to protect user access to the internet, cloud services, SaaS applications, and private resources from distributed points of entry. It emphasizes delivering these protections as-a-service from cloud platforms, enabling consistent policy enforcement regardless of user location or device. Gartner defined SSE in 2021 as a set of technologies encompassing secure web gateways, zero-trust access controls, threat detection, and data loss prevention, aimed at addressing the limitations of legacy perimeter-based security in hybrid and remote work environments.[31][32] SSE emerged as a refinement of broader secure access paradigms in response to the shift toward cloud computing and decentralized workforces, particularly accelerated by the COVID-19 pandemic's remote work surge starting in 2020. The concept builds on Secure Access Service Edge (SASE), a term Gartner coined in 2019 to integrate networking and security convergence, but SSE isolates the security layer to allow organizations to adopt protections independently of networking upgrades.[33][34] Early innovations in cloud-delivered security trace to vendors like Zscaler, which began proxy-based web security in 2008, but the formalized SSE framework gained traction post-2021 as enterprises sought scalable alternatives to VPNs and on-premises appliances.[35] Core components of SSE include:- Secure Web Gateway (SWG): Filters web traffic to block malware, phishing, and unauthorized sites using URL filtering, sandboxing, and SSL inspection.[32]
- Cloud Access Security Broker (CASB): Monitors and enforces policies for SaaS and IaaS usage, including shadow IT discovery, data exfiltration prevention, and compliance controls.[36]
- Zero Trust Network Access (ZTNA): Verifies user identity, device posture, and context before granting granular access to applications, replacing broad VPN tunnels with least-privilege principles.[33]
- Firewall as a Service (FWaaS): Provides next-generation firewall capabilities in the cloud, inspecting traffic for threats without hardware dependencies.[37]
Searchable Symmetric Encryption
Searchable symmetric encryption (SSE) is a cryptographic protocol enabling a client to outsource encrypted data storage to an untrusted server while retaining the ability to query for specific keywords without revealing the plaintext data or query contents to the server.[44] In SSE, the client generates an encrypted index or trapdoors for keywords, which the server uses to identify matching encrypted documents via secure comparisons, returning only identifiers of relevant files for the client to decrypt locally.[45] This approach balances efficiency with privacy, as full decryption of the dataset for each search would be computationally prohibitive for large corpora.[44] The foundational SSE scheme appeared in 2000, proposed by Song, Wagner, and Perrig, who introduced a method using oblivious RAM-like techniques to hide search patterns at the cost of sequential scans over encrypted blocks. Subsequent work in 2006 by Curtmola et al. formalized security definitions distinguishing non-adaptive (CKA1) and adaptive (CKA2) chosen-keyword attacks, where the adversary queries keywords before or interleaved with observing server responses, respectively; they also provided efficient constructions achieving optimal search time of O(log N) for N documents using inverted indices with pseudorandom permutations.[44] These definitions quantify leakage, such as access patterns (which documents match a query) and search patterns (repeated queries for the same keyword), which are inherent to efficient SSE designs but must be minimized to prevent inference attacks.[44] SSE schemes are classified as static, where the document set is fixed post-encryption, or dynamic, supporting insertions and deletions while preserving search efficiency.[46] Dynamic schemes, such as those by Kamara et al. (2012), employ balanced tree structures over encrypted indices to achieve sublinear updates and queries, though they introduce additional leakage from edit patterns.[46] Advanced variants incorporate forward privacy, ensuring new insertions remain hidden from prior searches, and backward privacy, protecting non-matching documents from revealing past access; for instance, Bost's 2016 scheme achieves both using oblivious data structures. Conjunctive SSE extends to multi-keyword queries, as in Cash et al.'s 2013 work, reducing communication via partitioned indices but trading off against volume-pattern leakage. Security in SSE relies on standard primitives like pseudorandom functions and permutations, provably secure under the random oracle model or standard assumptions.[44] However, real-world deployments face side-channel risks, including leakage-abuse attacks that reconstruct databases from observed access patterns over multiple queries, as demonstrated by Islam et al. (2012) against early schemes recovering up to 80% of keywords in simulated datasets. Mitigations include padding to normalize result sizes or multi-server architectures distributing indices, though these increase overhead; recent analyses emphasize auditing leakage functions empirically, as theoretical bounds often underestimate practical inference when queries correlate with document frequencies.[47] SSE finds application in cloud storage services like encrypted email search or database outsourcing, prioritizing sublinear query times over zero-knowledge ideals, with ongoing research addressing SQL-like queries via property-preserving extensions.[48]Economics and Finance
Shanghai Stock Exchange
The Shanghai Stock Exchange (SSE) was established on November 26, 1990, as a membership-based, non-profit public institution under the oversight of the China Securities Regulatory Commission (CSRC), with formal trading commencing on December 19, 1990.[49][50] This marked the reintroduction of organized equity trading in mainland China following the closure of pre-1949 exchanges after the founding of the People's Republic.[51] The SSE primarily facilitates trading in stocks, bonds, funds, and derivatives, serving as a key channel for capital allocation to enterprises amid China's state-directed economic model.[52] As of October 20, 2025, the SSE listed 2,288 companies and securities, with a total market capitalization of 62,154.18 billion RMB and daily turnover of 773.28 billion RMB.[53] Trading occurs on weekdays from 9:30 a.m. to 11:30 a.m. and 1:00 p.m. to 3:00 p.m. local time, primarily in A-shares (RMB-denominated, accessible to qualified domestic and foreign investors) and legacy B-shares (foreign currency-denominated).[53] International access has expanded through mechanisms like the Shanghai-Hong Kong Stock Connect, launched in November 2014, enabling cross-border trading subject to quotas and regulatory approvals.[54] The SSE's flagship SSE Composite Index, introduced on July 15, 1991, tracks the price performance of all listed A- and B-shares using a base value of 100 on December 19, 1990.[55] Specialized segments include the STAR Market, operational since July 22, 2019, which targets high-tech firms with registration-based listing and looser profitability criteria to foster innovation.[56] Main board listing requires applicants to demonstrate at least three years of operational history, positive net profit over the prior two years (or cumulative over three), and a public float of no less than 25% of total shares (or 10% for companies with market caps exceeding 10 billion RMB).[57][58] Delisting triggers include sustained losses, failure to meet disclosure standards, or equity structures falling below public shareholding thresholds.[58] The exchange's operations reflect tight CSRC regulation, including trading halts and circuit breakers implemented since 2016 to mitigate volatility from retail investor dominance and policy influences.[59]Substantial Shareholdings Exemption
The Substantial Shareholdings Exemption (SSE) is a provision under UK corporation tax legislation that exempts companies from tax on chargeable gains (and allowable losses) arising from the disposal of shares in qualifying subsidiaries or associated companies, provided specific conditions are met. Enacted to enhance the UK's competitiveness as an investment destination by mitigating double taxation on corporate share disposals, the SSE applies automatically without the need for election when eligibility criteria are satisfied. It primarily targets trading subsidiaries, exempting gains that would otherwise be subject to the standard corporation tax rate, which stood at 25% for profits over £250,000 as of April 2023.[60][61] Introduced via the Finance Act 2002 and effective for disposals from 1 April 2002, the SSE replaced a narrower prior regime under which only groups could defer gains on intra-group transfers, aiming to align UK rules more closely with those in other jurisdictions that exempt such corporate-level gains outright. Prior to 2002, UK companies faced taxation on share disposals without equivalent relief, discouraging active portfolio management and inbound investment; the exemption addressed this by focusing on "substantial" holdings in trading entities, defined initially with symmetric trading requirements for both investor and investee. Significant reforms under the Finance Act 2017, applicable to disposals on or after 1 April 2017, relaxed these rules by eliminating the trading requirement for the investing company and allowing SSE for investee companies that ceased trading within 12 months prior to disposal or intended to resume trading, broadening applicability to private equity exits and restructurings.[61][62][63] To qualify, the disposed shares must constitute a "substantial shareholding," meaning the investing company held at least 10% of the investee's ordinary share capital, 10% of profits available for distribution to ordinary shareholders, and 10% of assets distributable on winding-up. This threshold must be maintained continuously for at least 12 months within the six-year period ending on the disposal date, with the holding period commencing no earlier than six years before disposal to prevent abuse via long-dormant stakes. The investee company must meet trading conditions: it or its group must be a trading company or the holding company of a trading group at the time of disposal, or have satisfied this within the prior 12 months, or have a fixed intention to become one post-disposal; passive investment activities, such as holding non-trading assets exceeding de minimis levels (e.g., more than 20% non-trading loans or assets in some cases), disqualify under HMRC's "trading" tests derived from case law like Kirkham v Williams.[60][64][65] Special provisions apply to group structures and joint ventures. Within 75% corporate groups, disposals may qualify if the substantial holding test is met at the group level, though anti-avoidance rules under TCGA 1992 Sch 7AC deny SSE for arrangements artificially creating holdings. For joint ventures not in the same group, a modified test permits SSE if the investee is a qualifying joint venture company (e.g., 10% held by the investor with no single party controlling over 50%), provided trading conditions hold. Losses are similarly exempted, preventing their use to offset other taxable gains, which aligns with the policy of neutrality for genuine trading investments but requires careful pre-disposal planning to avoid inadvertent disqualification from minor non-trading activities. HMRC clearance under s138 TCGA 1992 may be sought for borderline trading status, though not mandatory.[66][60][67]| Key SSE Conditions (Post-2017) | Description |
|---|---|
| Substantial Shareholding | ≥10% ordinary shares, profits, and winding-up assets; held ≥12 months in 6-year window ending on disposal.[60] |
| Trading Requirement (Investee) | Trading company/group at disposal, or within 12 months prior, or intends to become; investor need not trade.[64] |
| Exclusions | Artificial arrangements; non-trading investees without grace period/intent; certain joint ventures failing modified tests.[66] |